Compression device and oil pump

Abstract

A compression device (1) is provided with a motor case (200) and a housing (310) that accommodates a control unit (300). The motor case (200) and the housing (310) form a cooling water flow space (320) therebetween. The cooling water flow space (320) has: an inflow part (321); an outflow part (322) provided independently of the inflow part (321); and a communication part (323) that causes the inflow part (321) and the outflow part (322) to be in communication with each other, and through which a cooling water flows from the inflow part (321) toward the outflow part (322). A rear surface (200a) of the motor case (200) has: a first recessed part (200b) that is recessed in a direction away from a front surface (310a) and defines the inflow part (321); and a second recessed part (200c) that is recessed in a direction away from the front surface (310a) and defines the outflow part (322). The front surface (310a) of the housing (310) has a plurality of groove parts (310b) that are recessed in a direction away from the rear surface (200a), and that extend from a position overlapping the first recessed part (200b) to a position overlapping the second recessed part (200c) when seen in the axial direction.

Description

TECHNICAL FIELD

[0001] The present invention relates to a compression device and an oil pump.

[0002] Priority is claimed on Japanese Patent Application No. 2023-103652, filed June 23, 2023, the content of which is incorporated herein by reference.BACKGROUND ART

[0003] A compression device including a reciprocating compressor that generates high-pressure compressed air is known. The compressed air compressed in a cylinder of the reciprocating compressor is supplied to a pneumatic machine via a discharge port. Since compression heat is generated in a process of compressing air, temperatures of a cylinder and a piston rise during operation of the reciprocating compressor. Furthermore, since an electric motor that drives the reciprocating compressor is driven by an applied current, Joule heat is generated by the applied current. Thus, a temperature of the electric motor also increases. Furthermore, a control unit that controls the electric motor also generates heat. Two-stage reciprocating compressors which compress air in two stages are also known. The two-stage reciprocating compressor includes a low-pressure side cylinder and a high-pressure side cylinder. In the two-stage reciprocating compressor, air compressed in the low-pressure side cylinder is transferred to the high-pressure side cylinder and is further compressed in the high-pressure side cylinder.Citation ListPatent Document

[0004] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H09-264253SUMMARY OF INVENTIONTechnical Problem

[0005] There is a demand for further improvement in a cooling effect in a compression device having a reciprocating compressor, particularly in a two-stage reciprocating compressor in which compression heat generated when air is compressed may increase.

[0006] Therefore, the present invention is to provide a compression device and an oil pump which have excellent cooling efficiency.Solution to Problem

[0007] A compression device according to a first aspect of the present invention includes a rotary drive source, a first case configured to accommodate the rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a compression element configured to compress gas using rotation of the rotary shaft as power, a control unit configured to control the rotary drive source, and a second case configured to accommodate the control unit and which is coupled to the first case to overlap the first case in a predetermined direction, wherein the first case and the second case define a cooling water flow space therebetween through which cooling water flows, the first case has a first surface that defines the cooling water flow space, the second case has a second surface that defines the cooling water flow space, the cooling water flow space has an inflow part, an outflow part provided independently of the inflow part, and a communication part that causes the inflow part and the outflow part to be in communication with each other and allows the cooling water to flow from the inflow part to the outflow part, the first surface has a first recessed part that is recessed in a direction away from the second surface and defines the inflow part, and a second recessed part that is recessed in a direction away from the second surface and defines the outflow part, and the second surface has a plurality of groove parts that are recessed in a direction away from the first surface and extend from a position overlapping the first recessed part to a position overlapping the second recessed part when seen in the predetermined direction.

[0008] According to the first aspect, since the plurality of groove parts through which the cooling water flows are formed in the second case that accommodates the control unit, a surface area in the second case that comes into contact with the cooling water is ensured, and thus the control unit can be cooled efficiently.

[0009] A compression device according to a second aspect of the present invention includes a rotary drive source having a rotor and a stator disposed around the rotor, a case configured to accommodate the rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the case includes an inner case that holds the stator, and an outer case that surrounds the inner case, the inner case and the outer case form a water passage therebetween through which cooling water flows, and the water passage extends spirally around a rotation axis of the rotary drive source.

[0010] According to the second aspect, the cooling water can be circulated around the entire circumference of the inside of the case that accommodates the rotary drive source. Therefore, the rotary drive source can be efficiently cooled.

[0011] A compression device according to a third aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a first compression element configured to compress gas using rotation of the rotary shaft as power, and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein the first compression element includes a first piston connected to the rotary shaft, and a first cylinder block having a first cylinder chamber into which the first piston is slidably fitted, the second compression element includes a second piston connected to the rotary shaft, and a second cylinder block having a second cylinder chamber into which the second piston is slidably fitted, the first cylinder block has a first cylinder water passage through which cooling water flows, and the second cylinder block has a second cylinder water passage through which the cooling water flowing into the first cylinder water passage flows.

[0012] According to the third aspect, in the first and second cylinder blocks, the second cylinder block which becomes hotter due to heat exchange with the compressed gas can be cooled with low-temperature cooling water before heat exchange with the first cylinder block. Therefore, the first compression element and the second compression element can be cooled efficiently.

[0013] A compression device according to a fourth aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a first compression element configured to compress gas using rotation of the rotary shaft as power, and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein at least one of the first compression element and the second compression element has a piston connected to the rotary shaft, and a cylinder block having a cylinder chamber into which the piston is slidably fitted, and the cylinder block has a ventilation passage through which the compressed gas discharged from the first compression element passes, and a water passage formed between the ventilation passage through and the cylinder chamber and through which cooling water flows.

[0014] According to the fourth aspect, since the water passage is formed between the wall surface of the cylinder chamber and the wall surface of the ventilation passage through which perform heat exchange with the compressed air, wall parts of the cylinder chamber and the ventilation passage through can be efficiently cooled.

[0015] A compression device according to a fifth aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the compression element includes a piston connected to the rotary shaft, a cylinder block having a cylinder chamber into which the piston is slidably fitted, a cylinder head that is fixed to the cylinder block and defines the cylinder chamber on the side opposite the piston, and a cylinder head cover that covers the cylinder head from the side opposite the cylinder block and forms an air chamber, which is in communication with the cylinder chamber, between the cylinder head and the cylinder head cover, and the cylinder head cover has a wall surface that defines the air chamber and has a plurality of recessed parts formed therein.

[0016] According to the fifth aspect, the plurality of recessed parts can reflect and attenuate vibrations of the air in the air chamber in a complex manner. Therefore, sound emitted by the compression element is attenuated, and a compression device that suppresses noise generation can be provided.

[0017] A compression device according to a sixth aspect of the present invention includes a rotary drive source, a crankshaft configured to rotate due to an output of the rotary drive source, a piston connected to the crankshaft, a cylinder having a cylinder chamber into which the piston is slidably fitted, and an intake chamber that is in communication with the cylinder chamber and external air, a crankcase having a crank chamber that accommodates the crankshaft, and a connection part configured to cause the intake chamber and the crank chamber to be communicating with respect to each other.

[0018] According to the sixth aspect, since the crank chamber is in communication with the intake chamber, pressure fluctuations in the crank chamber caused by a displacement of the piston can be alleviated. Thus, it is possible to curb leakage of gas, lubricating oil, or the like from the crank chamber due to the pressure fluctuations in the crank chamber. It is also possible to curb problems with the supply of the lubricating oil occurring due to fluctuations in supply pressure of the lubricating oil in the crank chamber caused by the pressure fluctuations in the crank chamber. Furthermore, it is possible to curb fluctuations in a load applied to drive parts such as the pistons due to the pressure fluctuations in the crank chamber.

[0019] An oil pump according to a seventh aspect of the present invention includes a connecting ring fitted onto an eccentric shaft to be rotatable relative to the eccentric shaft, having an inner circumferential surface and an outer circumferential surface, and having a through hole that is open to the inner circumferential surface and the outer circumferential surface, a pump cylinder having a pump chamber configured to extend in a pump axial direction perpendicular to an axial direction of the eccentric shaft and having a first opening that is open toward the connecting ring and a second opening that is provided separately from the first opening, a hollow stem having a first end portion inserted into the through hole from the outer circumferential surface and a second end portion inserted into the pump chamber through the first opening, the second end portion being in sliding contact with a wall surface of the pump chamber in a liquid-tight manner while being movable in the pump axial direction within the pump chamber and tiltable relative to the pump cylinder, thereby causing the through hole and the pump chamber to be in communication with each other, a first valve part configured to allow a flow of liquid from an inner space of the stem to the through hole and block the flow of liquid from the through hole to the inner space of the stem, a second valve part configured to close the second opening of the pump chamber in an openable manner, allow a flow of liquid from an outer space of the pump cylinder to the pump chamber, and block the flow of liquid from the pump chamber to the outer space of the pump cylinder, and a filter configured to cover the second opening from the outside of the pump cylinder.

[0020] According to the seventh aspect, when the eccentric shaft is rotated, the connecting ring swings. When the connecting ring swings, the stem reciprocates in a pump axial direction while tilting around a contact portion with the pump cylinder. When the stem moves, and negative pressure is generated in the pump chamber, liquid flows into the pump chamber through the second opening. As internal pressure of the pump chamber increases with the movement of the stem, the lubricating oil inside the stem, which is in communication with the pump chamber, opens the first valve part and flows into the through hole of the connecting ring. Thus, the oil pump discharges the liquid from an opening of the through hole in the inner circumferential surface of the connecting ring. As described above, it is possible to provide an oil pump that operates using the rotation of the eccentric shaft.

[0021] A compression device according to an eighth aspect of the present invention includes a rotary drive source, a reciprocating compressor operated by an output of the rotary drive source, and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes a casing, a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source, a piston connected to the crank pin, and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, and when the control unit controls the rotary drive source to rotate the crankshaft but fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft.

[0022] When the starting torque input to the crankshaft is insufficient and the reciprocating compressor fails to start, the crankshaft receives a reaction force and rotates in a reverse direction to pass through a starting position. According to the eighth aspect, by rotating the crankshaft again, it is possible to ensure a larger run-up angle of the crankshaft than at the time of the previous start, and thus it is possible to improve a probability of successful start of the reciprocating compressor. Therefore, the reciprocating compressor can be reliably started.

[0023] A compression device according to a ninth aspect of the present invention includes a rotary drive source, a reciprocating compressor operated by an output of the rotary drive source, and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes a housing, a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source, a piston connected to the crank pin, and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, and when the control unit controls the rotary drive source to rotate the crankshaft in a first rotation direction and fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft in a second rotation direction opposite to the first rotation direction and then rotate the crankshaft in the first rotation direction.

[0024] According to the ninth aspect, when the starting torque input to the crankshaft in a first rotation direction is insufficient and the reciprocating compressor fails to start, the crankshaft can be rotated in the reverse direction to pass through the starting position by rotating the crankshaft in a second rotation direction. Therefore, by rotating the crankshaft in the first rotation direction again, it is possible to ensure a larger run-up angle of the crankshaft than at the previous start, thereby improving a probability of successful start of the reciprocating compressor. Therefore, the reciprocating compressor can be started reliably.Advantageous Effects of Invention

[0025] According to the present invention, it is possible to provide a compression device and an oil pump which have excellent cooling efficiency.BRIEF DESCRIPTION OF DRAWINGS

[0026] [FIG. 1] A perspective view showing an exterior of a compression device according to an embodiment. [FIG. 2] A perspective view showing the exterior of the compression device according to the embodiment. [FIG. 3] A cross-sectional view taken along line III-III in FIG. 1. [FIG. 4] A cross-sectional view taken along line IV-IV in FIG. 1. [FIG. 5] A cross-sectional view taken along line V-V in FIG. 3. [FIG. 6] A bottom view of a first cylinder head cover according to the embodiment when seen from the first cylinder head side. [FIG. 7] A perspective view showing an exhaust-side valve member. [FIG. 8] A perspective view showing a part of the exhaust-side valve member shown in FIG. 7. [FIG. 9] A cross-sectional view taken along line IX-IX in FIG. 3. [FIG. 10] A side view of a drive mechanism according to the embodiment. [FIG. 11] A plan view of the drive mechanism according to the embodiment. [FIG. 12] A front view of the drive mechanism according to the embodiment. [FIG. 13] A cross-sectional view of a reciprocating compressor according to the embodiment, which shows an enlarged vertical cross section including an axis O. [FIG. 14] A perspective view showing an inner case. [FIG. 15] A view showing a rear surface of a motor case. [FIG. 16] A view showing a front surface of a housing. [FIG. 17] A cross-sectional view taken along line XVII-XVII in FIG. 3. [FIG. 18] A graph showing a relationship between a rotation angle of a crankshaft and a torque acting on the crankshaft in a reciprocating compressor of the embodiment. [FIG. 19] A graph showing the relationship between the rotation angle of the crankshaft and the torque acting on the crankshaft in the reciprocating compressor of the embodiment. DESCRIPTION OF EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of the components may be omitted.

[0028] FIGS. 1 and 2 are perspective views showing an exterior of a compression device according to an embodiment.

[0029] As shown in FIGS. 1 to 3, the compression device 1 includes a reciprocating compressor 2, a rotary drive source 3, and a control device 4. The rotary drive source 3 outputs a rotary drive force about an axis O to drive the reciprocating compressor 2. Hereinafter, a direction in which the axis O extends will be referred to as an axial direction. In this embodiment, the axial direction is parallel to a horizontal direction. The reciprocating compressor 2, the rotary drive source 3, and the control device 4 are arranged in this order in the axial direction. In the axial direction, a direction in which the reciprocating compressor 2 is disposed relative to the rotary drive source 3 is defined as the front, and a direction opposite thereto is defined as the rear.(Reciprocating Compressor)

[0030] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1.

[0031] As shown in FIGS. 1 to 3 , the reciprocating compressor 2 is a two-stage reciprocating compressor. In this embodiment, the reciprocating compressor 2 takes in external air to generate compressed air and supplies the generated compressed air to a pneumatic machine (not shown). The reciprocating compressor 2 includes a casing (a crankcase) 100, a first cylinder 120 and a second cylinder 140 mounted in the casing 100, and a two-axis oscillating linear drive mechanism 180 provided within the casing 100 and within the first cylinder 120 and the second cylinder 140. Hereinafter, the two-axis oscillating linear drive mechanism 180 will be simply referred to as a drive mechanism 180.

[0032] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1.

[0033] As shown in FIGS. 3 and 4, the casing 100 is formed to have a hollow box shape. The casing 100 includes a casing main body 101, a bottom plate 102, a front cover 103, and a rear cover 104. The casing main body 101 is a strength member of the casing 100. The casing main body 101 includes an eye bolt 106 that protrudes upward (refer to FIGS. 1 and 2). The casing main body 101 has a lower opening closed by the bottom plate 102, a front opening closed by the front cover 103, and a rear opening closed by the rear cover 104. The bottom plate 102 is disposed on a bottom surface of the casing 100 and is fastened to the casing main body 101. The front cover 103 is disposed on a front surface of the casing 100 and is fastened to the casing main body 101. A recessed part 103a that is coaxial with the axis O is formed in an inner surface of the front cover 103. The rear cover 104 is disposed on a rear surface of the casing 100 and is fastened to the casing main body 101. A through hole 104a that is coaxial with the axis O is formed in the rear cover 104. An inner space of the casing 100 is a crank chamber that accommodates the drive mechanism 180. A lower portion of the inner space of the casing 100 forms an oil reservoir that is defined from below by the bottom plate 102.

[0034] The first cylinder 120 protrudes upward from the casing main body 101 in a first direction. The second cylinder 140 protrudes upward from the casing main body 101 in a second direction. In this embodiment, the first direction and the second direction are perpendicular to each other.

[0035] The first cylinder 120 includes a first cylinder block 121, a first cylinder head 122, and a first cylinder head cover 123. The first cylinder block 121 is coupled to the casing 100. The first cylinder head 122 is fixed to the first cylinder block 121 from the side opposite the casing main body 101. The first cylinder head cover 123 covers the first cylinder head 122 from the side opposite the first cylinder block 121. The first cylinder head cover 123 is fixed to the first cylinder head 122.

[0036] The first cylinder block 121 includes a first cylinder chamber 124 that extends in the first direction. The first cylinder chamber 124 is open on both sides in the first direction and is in communication with the inner space of the casing 100. A first piston P1 is slidably fitted into the first cylinder chamber 124 from the inner space side of the casing main body 101. The first cylinder block 121 includes a first cylinder liner 121a that has a cylindrical shape and forms an inner circumferential surface of the first cylinder chamber 124, and a first cylinder block main body 121b in which the first cylinder liner 121a is mounted. The first cylinder block main body 121b is formed integrally with the casing main body 101. The first cylinder block main body 121b is formed to have a tubular shape that is open at both ends in the first direction and is in communication with the inner space of the casing main body 101. The first cylinder liner 121a is fitted inside the first cylinder block 121.

[0037] FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3.

[0038] As shown in FIGS. 3 and 5, an exhaust passage 130 through which a gas forcibly fed by the reciprocating compressor 2 flows and a first cylinder water passage 131 through which cooling water flows are formed in the first cylinder block 121. The exhaust passage 130 is a part of a ventilation passage through which the compressed air discharged from the first cylinder chamber 124 passes. The exhaust passage 130 is formed in the first cylinder block main body 121b. The exhaust passage 130 extends in the first direction and opens into an end surface of the first cylinder block 121 on the first cylinder head 122 side. The exhaust passage 130 extends around the first cylinder chamber 124 so as to surround a part of the first cylinder chamber 124 when seen in the first direction.

[0039] The first cylinder water passage 131 includes a first cylinder first water passage 132 and a first cylinder second water passage 133 through which the cooling water flowing into the first cylinder first water passage 132 flows.

[0040] The first cylinder first water passage 132 is formed between the first cylinder liner 121a and the first cylinder block main body 121b. More specifically, the first cylinder first water passage 132 is a gap between an outer circumferential surface of the first cylinder liner 121a and an inner circumferential surface of the first cylinder block main body 121b. The first cylinder first water passage 132 extends annularly around the entire circumference of the first cylinder chamber 124. The first cylinder first water passage 132 extends in the first direction between a pair of annular seal members spaced apart in the first direction and interposed between the outer circumferential surface of the first cylinder liner 121a and the inner circumferential surface of the first cylinder block main body 121b. Both ends of the first cylinder first water passage 132 in the first direction are sealed by seal members. The first cylinder first water passage 132 is in communication with the outside of the first cylinder 120 through a discharge pipe 134 mounted in the first cylinder block main body 121b.

[0041] The first cylinder second water passage 133 is directly connected to the first cylinder first water passage 132. The first cylinder second water passage 133 is formed in the first cylinder block main body 121b. The first cylinder second water passage 133 is located on the side opposite the first cylinder chamber 124 with the first cylinder first water passage 132 interposed therebetween. The first cylinder second water passage 133 extends in the first direction and opens to an end surface of the first cylinder block 121 on the first cylinder head 122 side. An opening of the first cylinder second water passage 133 on the first cylinder head 122 side is tightly closed by the first cylinder head 122. The first cylinder second water passage 133 extends around the first cylinder chamber 124 so as to surround a part of the first cylinder chamber 124 when seen in the first direction. The first cylinder second water passage 133 is connected to the first cylinder first water passage 132 at one end when seen in the first direction, and is connected to the second cylinder water passage 152, which will be described below, at the other end when seen in the first direction. The first cylinder second water passage 133 opens on the inner circumferential surface of the first cylinder block main body 121b in an extension direction (a circumferential direction) of the first cylinder first water passage 132 when seen in the first direction. Thus, the cooling water discharged from the first cylinder second water passage 133 flows to circulate through the first cylinder first water passage 132.

[0042] The first cylinder water passage 131 is located between the entire exhaust hole 122b and the first cylinder chamber 124. In this embodiment, the first cylinder first water passage 132 and the first cylinder second water passage 133 are located between the exhaust hole 122b and the first cylinder chamber 124.

[0043] As shown in FIGS. 3 and 4, the first cylinder head 122 defines the first cylinder chamber 124 from the side opposite the first piston P1. The first cylinder head 122 is formed in a plate shape. The first cylinder head 122 is disposed so as to overlap the end surface of the first cylinder block 121. An intake hole 122a and the exhaust hole 122b that are in communication with the first cylinder chamber 124, and a ventilation hole 122c that is in communication with the exhaust passage 130 are formed in the first cylinder head 122. The intake hole 122a, the exhaust hole 122b, and the ventilation hole 122c pass through the first cylinder head 122 in the first direction. At least one of the intake hole 122a and the exhaust hole 122b may be formed in plurality and arranged in a predetermined direction. For example, the intake hole 122a and the exhaust hole 122b may be arranged in accordance with an exterior of the opening of the first cylinder chamber 124. A plurality of ventilation holes 122c may be formed and arranged in a predetermined direction. For example, the ventilation holes 122c may be arranged in a straight line in accordance with a shape of the opening of the exhaust passage 130.

[0044] The first cylinder head cover 123 forms an intake chamber 125 and an exhaust chamber 126 that are in communication with the first cylinder chamber 124 between the first cylinder head cover 123 and the first cylinder head 122. The intake chamber 125 and the exhaust chamber 126 are independent of each other. The intake chamber 125 is in communication with the first cylinder chamber 124 through the intake hole 122a, and is also in communication with external air through an intake pipe 129 mounted in the first cylinder head cover 123. The exhaust chamber 126 is in communication with the first cylinder chamber 124 through the exhaust hole 122b, and is also in communication with the exhaust passage 130 through the ventilation hole 122c.

[0045] FIG. 6 is a bottom view of the first cylinder head cover according to the embodiment, when seen from the first cylinder head side.

[0046] As shown in FIGS. 3 and 6, the first cylinder head cover 123 has a wall surface 123a that defines each of the intake chamber 125 and the exhaust chamber 126. A plurality of recessed parts 123b are formed in the wall surface 123a. The recessed parts 123b are formed in the wall surface 123a at a location that defines the intake chamber 125 and at a location that defines the exhaust chamber 126, respectively. The plurality of recessed parts 123b form a so-called honeycomb structure in which the recessed parts 123b formed in a regular hexagonal shape when seen in the first direction are planarly filled. However, a shape of each of the recessed parts is not limited to a regular hexagon and may be, for example, a rectangular or circular shape.

[0047] As shown in FIG. 3, an intake-side valve member 127 and an exhaust-side valve member 128 are provided at the first cylinder head 122. The intake-side valve member 127 and the exhaust-side valve member 128 are each a check valve.

[0048] The intake-side valve member 127 is disposed in the first cylinder chamber 124. The intake-side valve member 127 allows a flow of gas from the intake chamber 125 to the first cylinder chamber 124, and also blocks a flow of gas from the first cylinder chamber 124 to the intake chamber 125. The intake-side valve member 127 is formed in a thin plate shape and is disposed along a surface of the first cylinder head 122 on the first cylinder chamber 124 side. The intake-side valve member 127 is sandwiched between the first cylinder block 121 and the first cylinder head 122 and is held at a position along the surface of the first cylinder head 122 on the first cylinder chamber 124 side. The intake-side valve member 127 receives negative pressure in the first cylinder chamber 124 and deforms to be away from an opening edge of the intake hole 122a, thereby allowing communication between the intake chamber 125 and the first cylinder chamber 124.

[0049] The exhaust-side valve member 128 is disposed in the exhaust chamber 126. The exhaust-side valve member 128 allows a flow of gas from the first cylinder chamber 124 to the exhaust chamber 126, and also blocks a flow of gas from the exhaust chamber 126 to the first cylinder chamber 124.

[0050] FIG. 7 is a perspective view showing an exhaust-side valve member, and FIG. 8 is a perspective view showing a part of the exhaust-side valve member shown in FIG. 7.

[0051] As shown in FIGS. 7 and 8, the exhaust-side valve member 128 includes a valve main body 128a formed in a thin plate shape and disposed along the surface of the first cylinder head 122 on the exhaust chamber 126 side, and a retaining member 128b that holds the valve main body 128a. The valve main body 128a is formed to be elongated in plan view. The retaining member 128b is formed to be elongated along the valve main body 128a and is detachably fixed to the first cylinder head 122. The retaining member 128b holds both ends of the valve main body 128a between the retaining member 128b and the first cylinder head 122. The retaining member 128b is provided to cover the valve main body 128a with a gap therebetween, and allows the valve main body 128a to deform so as to be away from the opening edge of the exhaust hole 122b. The valve main body 128a receives negative pressure in the exhaust chamber 126 and deforms to be away from the opening edge of the exhaust hole 122b, thereby allowing communication between the first cylinder chamber 124 and the exhaust chamber 126 .

[0052] As shown in FIG. 1, a communication pipe 136 is connected to the first cylinder 120. The communication pipe 136 is disposed outside the casing 100. The communication pipe 136 is connected to the front cover 103 of the casing 100 and the first cylinder head cover 123. The communication pipe 136 extends in the horizontal direction or in a direction inclined upward from the horizontal direction from a connection part with the front cover 103 to a connection part with the first cylinder head cover 123. The communication pipe 136 is a connection part that communicates the inner space of the casing 100 with the intake chamber 125. Thus, the communication pipe 136 communicates the inner space of the casing 100 with the external air.

[0053] As shown in FIGS. 3 and 4, the second cylinder 140 includes a second cylinder block 141, a second cylinder head 142, and a second cylinder head cover 143. The second cylinder block 141 is coupled to the casing 100. The second cylinder head 142 is fixed to the second cylinder block 141 from the side opposite the casing main body 101. The second cylinder head cover 143 covers the second cylinder head 142 from the side opposite the second cylinder block 141. The second cylinder head cover 143 is fixed to the second cylinder head 142.

[0054] The second cylinder block 141 includes a second cylinder chamber 144 extending in the second direction. The second cylinder chamber 144 is open on both sides in the second direction and is in communication with the inner space of the casing 100. The second cylinder chamber 144 has a smaller diameter than the first cylinder chamber 124. A second piston P2 is slidably inserted into the second cylinder chamber 144 from the inner space side of the casing main body 101. The second cylinder block 141 includes a second cylinder liner 141a that has a cylindrical shape and forms an inner circumferential surface of the second cylinder chamber 144, and a second cylinder block main body 141b in which the second cylinder liner 141a is mounted. The second cylinder block main body 141b is formed integrally with the casing main body 101. The second cylinder block main body 141b is formed in a tubular shape that is open at both ends in the second direction and is in communication with the inner space of the casing main body 101. The second cylinder liner 141a is fitted inside the second cylinder block 141.

[0055] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 3.

[0056] As shown in FIGS. 3 and 9, an intake passage 150 and an exhaust passage 151 through which the gas forcibly fed by the reciprocating compressor 2 flows, and a second cylinder water passage 152 through which cooling water flows are formed in the second cylinder block 141. The intake passage 150 and the exhaust passage 151 are part of the ventilation passage through which compressed air discharged from the first cylinder chamber 124 passes. The intake passage 150 and the exhaust passage 151 are formed in the first cylinder block main body 121b. The intake passage 150 is in direct communication with the exhaust passage 130 of the first cylinder 120. The intake passage 150 extends in the second direction and is open at an end surface of the second cylinder block 141 on the second cylinder head 142 side. The intake passage 150 extends around the second cylinder chamber 144 at a position on the first cylinder 120 side relative to the second cylinder chamber 144 so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The exhaust passage 151 extends in the second direction and is open to an end surface of the second cylinder block 141 on the second cylinder head 142 side. The exhaust passage 151 extends around the second cylinder chamber 144 at a position on the side opposite the intake passage 150 with the second cylinder chamber 144 interposed therebetween so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The exhaust passage 151 is in communication with the outside of the compression device 1 through an exhaust pipe 156 mounted in the second cylinder block main body 141b.

[0057] The second cylinder water passage 152 includes a second cylinder first water passage 153, a second cylinder second water passage 154 through which cooling water flowing into the second cylinder first water passage 153 flows, and a second cylinder third water passage 155 through which cooling water flowing out of the second cylinder first water passage 153 and flowing into the first cylinder second water passage 133 flows.

[0058] The second cylinder first water passage 153 is formed between the second cylinder liner 141a and the second cylinder block main body 141b. More specifically, the second cylinder first water passage 153 is a gap between an outer circumferential surface of the second cylinder liner 141a and an inner circumferential surface of the second cylinder block main body 141b. The second cylinder first water passage 153 extends annularly around the entire circumference of the second cylinder chamber 144. The second cylinder first water passage 153 extends in the second direction between a pair of annular seal members spaced apart in the second direction. The pair of seal members are interposed between the outer circumferential surface of the second cylinder liner 141a and the inner circumferential surface of the second cylinder block main body 141b. Both ends of the second cylinder first water passage 153 in the second direction are sealed by the seal members.

[0059] The second cylinder second water passage 154 is directly connected to the second cylinder first water passage 153. The second cylinder second water passage 154 is formed in the second cylinder block main body 141b. The second cylinder second water passage 154 is located on the side opposite the second cylinder chamber 144 with the second cylinder first water passage 153 interposed therebetween. The second cylinder second water passage 154 extends in the second direction and is open to the end surface of the second cylinder block 141 on the second cylinder head 142 side. An opening of the second cylinder second water passage 154 on the second cylinder head 142 side is tightly closed by the second cylinder head 142. The second cylinder second water passage 154 extends around the second cylinder chamber 144 so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The second cylinder second water passage 154 is connected to the second cylinder first water passage 153 at one end when seen in the second direction, and is connected to a downstream connection part 213 of a water passage 210 of a motor case 200 described below at the other end when seen in the second direction. The second cylinder second water passage 154 is open in the inner circumferential surface of the second cylinder block main body 141b in an extension direction (a circumferential direction) of the second cylinder first water passage 153 when seen in the second direction. Thus, the cooling water discharged from the second cylinder second water passage 154 flows through the second cylinder first water passage 153 so as to circulate around the second cylinder chamber 144.

[0060] The second cylinder third water passage 155 is directly connected to the second cylinder first water passage 153. The second cylinder third water passage 155 is formed in the second cylinder block main body 141b. The second cylinder third water passage 155 is located on the side opposite the second cylinder chamber 144 with the second cylinder first water passage 153 interposed therebetween.

[0061] The second cylinder water passage 152 is located between the entire exhaust hole 142b and the second cylinder chamber 144. In this embodiment, the second cylinder first water passage 153 and the second cylinder second water passage 154 are located between the exhaust hole 142b and the second cylinder chamber 144. Additionally, the second cylinder water passage 152 is located between the entire intake hole 142a and the second cylinder chamber 144. In this embodiment, the second cylinder first water passage 153 and the second cylinder third water passage 155 are located between the intake hole 142a and the second cylinder chamber 144.

[0062] As shown in FIGS. 3 and 4, the second cylinder head 142 defines the second cylinder chamber 144 from the side opposite the second piston P2. The second cylinder head 142 is formed in a plate shape. The second cylinder head 142 is disposed to overlap the end surface of the second cylinder block 141. The intake hole 142a and the exhaust hole 142b that are in communication with the second cylinder chamber 144, an intake-side ventilation hole 142c that is in communication with the intake passage 150, and an exhaust-side ventilation hole 142d that is in communication with the exhaust passage 151 are formed in the second cylinder head 142. The intake hole 142a, the exhaust hole 142b, the intake-side ventilation hole 142c, and the exhaust-side ventilation hole 142d pass through the second cylinder head 142 in the second direction. At least one of the intake hole 142a and the exhaust hole 142b may be formed in plurality and arranged in a predetermined direction. At least one of the intake-side ventilation hole 142c and the exhaust-side ventilation hole 142d may be formed in plurality and arranged in a predetermined direction. For example, the intake-side ventilation holes 142c may be arranged in accordance with a shape of the opening of the intake passage 150.

[0063] The second cylinder head cover 143 forms an intake chamber 145 and an exhaust chamber 146 that are in communication with the second cylinder chamber 144 between the second cylinder head cover 143 and the second cylinder head 142. The intake chamber 145 and the exhaust chamber 146 are independent of each other. The intake chamber 145 is in communication with the second cylinder chamber 144 through the intake hole 142a, and is also in communication with the intake passage 150 through the intake-side ventilation hole 142c. The exhaust chamber 146 is in communication with the second cylinder chamber 144 through the exhaust hole 142b, and is also in communication with the exhaust passage 151 through the exhaust-side ventilation hole 142d.

[0064] The second cylinder head cover 143 has a wall surface 143a that defines each of the intake chamber 145 and the exhaust chamber 146. A plurality of recessed parts 143b are formed in the wall surface 143a. The recessed parts 143b are formed in the wall surface 143a at portions that define the intake chamber 145 and at portions that define the exhaust chamber 146. The recessed parts 143b are formed in the same manner as the recessed parts 123b formed in the first cylinder head cover 123.

[0065] As shown in FIG. 3, the second cylinder head 142 is provided with an intake-side valve member 147 and an exhaust-side valve member 148. The intake-side valve member 147 and the exhaust-side valve member 148 are each a check valve.

[0066] The intake-side valve member 147 allows a flow of gas from the intake chamber 145 to the second cylinder chamber 144 and blocks a flow of gas from the second cylinder chamber 144 to the intake chamber 145. The intake-side valve member 147 is formed in a thin plate shape and is disposed along a surface of the second cylinder head 142 on the second cylinder chamber 144 side. The intake-side valve member 147 is sandwiched between the second cylinder block 141 and the second cylinder head 142 and is held at a position along a surface of the second cylinder head 142 on the second cylinder chamber 144 side. The intake-side valve member 147 receives negative pressure in the second cylinder chamber 144 and deforms so as to be away from an opening edge of the intake hole 142a, thereby allowing communication between the intake chamber 145 and the second cylinder chamber 144.

[0067] The exhaust-side valve member 148 allows a flow of gas from the second cylinder chamber 144 to the exhaust chamber 146, and blocks a flow of gas from the exhaust chamber 146 to the second cylinder chamber 144. The exhaust-side valve member 148 is configured in the same manner as the exhaust-side valve member 128 provided in the first cylinder head 122.

[0068] As shown in FIGS. 3 and 4, the drive mechanism 180 includes the first piston P1 slidably fitted into the first cylinder chamber 124 of the first cylinder 120, and the second piston P2 slidably fitted into the second cylinder chamber 144 of the second cylinder 140. The first piston P1 moves linearly up and down in the first direction. The first piston P1 cooperates with the first cylinder 120 to form a first compression element that compresses gas using rotation of a crankshaft CR (a rotary shaft) (described below) as power. The second piston P2 moves linearly up and down in the second direction. The second piston P2 cooperates with the second cylinder 140 to form a second compression element that further compresses the compressed gas discharged from the first compression element using the rotation of the crankshaft CR as power. In this embodiment, the first piston P1 has a larger diameter than the second piston P2.

[0069] FIG. 10 is a side view of the drive mechanism according to the embodiment. FIG. 11 is a plan view of the drive mechanism according to the embodiment. FIG. 12 is a front view of the drive mechanism according to the embodiment.

[0070] As shown in FIGS. 10 to 12, the drive mechanism 180 includes, as components disposed inside the casing 100, the crankshaft CR that rotates about the axis O due to an output of the rotary drive source 3, a first counterweight W1 and a second counterweight W2 that rotate integrally with the crankshaft CR, and connecting rods CN1 and CN2 that are connected to the crankshaft CR.

[0071] The crankshaft CR has a pair of main shafts M1 and M2 having a first central axis C1, and a first crank pin CP1 and a second crank pin CP2 that are eccentric with respect to the first central axis C1. The first central axis C1 is coaxial with the axis O. The pair of main shafts M1 and M2 are spaced apart from each other in the axial direction by a predetermined distance. The pair of main shafts M1 and M2 are a first main shaft M1 and a second main shaft M2. The first main shaft M1 is connected to a front end of the first crank pin CP1 via the first counterweight W1. The second main shaft M2 is connected to a rear end of the second crank pin CP2 via the second counterweight W2. The first crank pin CP1 and the second crank pin CP2 are coupled to each other so as to be rotatable integrally with each other. The first crank pin CP1 and the second crank pin CP2 connect the pair of main shafts M1 and M2 to each other so that they cannot rotate relative to each other. In this embodiment, the main shaft M2 and the second counterweight W2 are integrally formed, and the main shaft M1 and the first counterweight W1 are integrally formed.

[0072] The first main shaft M1 is inserted into the recessed part 103a in the front cover 103 of the casing 100 and is rotatably supported by the front cover 103. The second main shaft M2 is inserted into the through hole 104a in the rear cover 104 and is rotatably supported by the rear cover 104. Thus, the crankshaft CR is supported at both sides of the casing 100. The second main shaft M2 protrudes from the casing 100 to the outside and constitutes an input / output shaft. An eccentric part E1 (an eccentric shaft) that is eccentric with respect to the first central axis C1 is provided at the second main shaft M2. The eccentric part E1 is located between the rear cover 104 and the second counterweight W2.

[0073] One end of the connecting rod CN1 is rotatably connected to the first piston P1 via a piston pin, and the other end of the connecting rod CN1 is rotatably connected to an outer circumferential surface of the first crank pin CP1. Thus, the first piston P1 is connected to the crankshaft CR via the connecting rod CN1. The first piston P1 moves linearly in the first direction as the first crank pin CP1 rotates. When the first piston P1 moves linearly, the first cylinder 120 functions as a guide body that guides the linear movement of the first piston P1 in the first direction.

[0074] One end of the connecting rod CN2 is rotatably connected to the second piston P2 via a piston pin, and the other end of the connecting rod CN2 is rotatably connected to an outer circumferential surface of the second crank pin CP2. Thus, the second piston P2 is connected to the crankshaft CR via the connecting rod CN2. The second piston P22 moves linearly in the second direction as the second crank pin CP2 rotates. When the second piston P2 moves linearly, the second cylinder 140 functions as a guide body that guides the linear movement of the second piston P2 in the second direction.

[0075] FIG. 13 is a cross-sectional view of the reciprocating compressor according to the embodiment, and is an enlarged view of a vertical cross section including the axis O.

[0076] As shown in FIG. 13, the reciprocating compressor 2 includes an oil pump 160 for supplying lubricating oil for lubricating drive parts of the reciprocating compressor 2 to each of the parts. The oil pump 160 is disposed inside the casing 100. The oil pump 160 includes a connecting ring 161, a pump cylinder 163, a hollow stem 166, a first valve part 168, a second valve part 169, and a filter 171.

[0077] The connecting ring 161 is formed in an annular shape. The connecting ring 161 is fitted onto the eccentric part E1 of the second main shaft M2 of the crankshaft CR so as to be rotatable relative to the eccentric part E1. A through hole 161a that is open to inner and outer circumferential surfaces is formed in the connecting ring 161. The through hole 161a extends downward from an opening in the inner circumferential surface of the connecting ring 161 toward an opening in the outer circumferential surface thereof. The opening of the through hole 161a in the inner circumferential surface of the connecting ring 161 is a discharge hole of the oil pump 160.

[0078] The pump cylinder 163 is disposed in the lower portion of the inner space of the casing 100 and is supported by the casing 100. The pump cylinder 163 is disposed with a gap in an up-down direction relative to the bottom plate 102 of the casing 100. The pump cylinder 163 includes a cylinder block 163a and a cylinder cover 163b. The cylinder block 163a has a thickness in the up-down direction. The cylinder cover 163b is disposed to overlap the cylinder block 163a from below. The cylinder cover 163b is fastened to the casing main body 101 together with the cylinder block 163a.

[0079] The pump cylinder 163 has a pump chamber 164 that extends in the up-down direction (a pump axial direction). The pump chamber 164 passes through the cylinder block 163a and the cylinder cover 163b in the up-down direction. The pump chamber 164 has a circular cross section. The pump chamber 164 has a first opening 164a that is open toward the connecting ring 161, and a second opening 164b that is provided separately from the first opening 164a. The first opening 164a is formed in the cylinder block 163a. The second opening 164b is formed in the cylinder cover 163b. The pump chamber 164 extends with a constant inner diameter from the first opening 164a to the second opening 164b in the cylinder block 163a.

[0080] The stem 166 extends in the up-down direction. The stem 166 has an upper end portion (a first end portion) inserted into the through hole 161a of the connecting ring 161 from the outer circumferential surface, and a lower end portion (a second end portion) inserted into the pump chamber 164 of the pump cylinder 163 through the first opening 164a. The stem 166 communicates between the through hole 161a and the pump chamber 164. The upper end portion of the stem 166 is fitted into the connecting ring 161 in a liquid-tight manner and fixed to the connecting ring 161. The lower end portion is in sliding contact with a wall surface of the pump chamber 164 in a liquid-tight manner, while being movable up and down within the pump chamber 164 and tiltable relative to the pump cylinder 163.

[0081] The first valve part 168 is disposed in the through hole 161a. The first valve part 168 closes an upper end opening of the stem 166 in an openable manner. The first valve part 168 allows a flow of lubricating oil from an inner space of the stem 166 to the through hole 161a, and blocks a flow of lubricating oil from the through hole 161a to the inner space of the stem 166. In this embodiment, the first valve part 168 is a ball valve.

[0082] The second valve part 169 is disposed in the pump chamber 164. The second valve part 169 closes the second opening 164b of the pump chamber 164 in an openable manner. The second valve part 169 allows a flow of liquid from a space outside the pump cylinder 163 to the pump chamber 164, and blocks a flow of liquid from the pump chamber 164 to the space outside the pump cylinder 163. The second valve part 169 is formed in a thin plate shape and is disposed along an upper surface of the cylinder cover 163b. The second valve part 169 is sandwiched between the cylinder block 163a and the cylinder cover 163b and is held at a position along the upper surface of the cylinder cover 163b. The second valve part 169 receives negative pressure in the pump chamber 164 and deforms so as to be away from an opening edge of the second opening 164b, thereby allowing communication between the pump chamber 164 and the outside of the pump cylinder 163 .

[0083] The filter 171 covers the second opening 164b from the outside of the pump cylinder 163. The filter 171 filters the lubricating oil that flows into the pump chamber 164 through the second opening 164b. The filter 171 includes an inner filter 171a and an outer filter 171b.

[0084] For example, the inner filter 171a is made of a metal. The inner filter 171a is formed in a cylindrical shape with a bottom and an upward opening, and is disposed in a state in which an opening edge abuts on a circumferential edge of the second opening 164b. The inner filter 171a has a flange that extends radially outward from the opening edge. The inner filter 171a is disposed in a state in which the flange fits along a lower surface of the cylinder cover 163b. The flange is sandwiched around its entire circumference between the cylinder cover 163b and a washer fastened to the cylinder cover 163b so as to fit along the lower surface of the cylinder cover 163b. Thus, the inner filter 171a is disposed not to be displaceable relative to the pump cylinder 163.

[0085] For example, the outer filter 171b is made of sponge. The outer filter 171b is disposed between the pump cylinder 163 and the bottom plate 102 of the casing 100. The outer filter 171b is formed in a cylindrical shape with a thickness in a radial direction and is disposed to surround the inner filter 171a. The outer filter 171b is disposed so that its lower end opening is located inside a recessed part formed in an upper surface of the bottom plate 102. Thus, the oil pump 160 suctions up the lubricating oil accumulated inside the bottom plate 102 through an inner space of the outer filter 171b.(Rotary Drive Source)

[0086] As shown in FIG. 3, the rotary drive source 3 is an electric motor. The rotary drive source 3 includes the motor case 200 (a first case, a case), a motor shaft 220, a rotor 230, and a stator 240.

[0087] The motor case 200 is fastened to the casing 100 of the reciprocating compressor 2 from the rear. The motor case 200 has an inner space that passes through the inside thereof along the axis O. The motor case 200 has a hollow cylindrical shape. The motor case 200 includes an outer case 201 and an inner case 202.

[0088] The outer case 201 is formed in a cylindrical shape with a bottom that is open toward the reciprocating compressor 2. An outer circumferential surface of the outer case 201 forms an outer circumferential surface of the motor case 200. The outer case 201 has a shaft hole that passes through a bottom wall thereof. The shaft hole extends coaxially with the axis O. The shaft hole is closed by a cap.

[0089] The inner case 202 is formed in a cylindrical shape with a bottom that opens towards the side opposite to the reciprocating compressor 2. The inner case 202 is fitted inside the outer case 201 and is surrounded by the outer case 201. The inner case 202 has a shaft hole that passes through a bottom wall thereof. The shaft hole extends coaxially with the axis O. The second main shaft M2 that protrudes from the casing 100 of the reciprocating compressor 2 is inserted into the shaft hole.

[0090] The inner case 202 has a flange 202a that protrudes radially outward from an end edge of its circumferential wall on the reciprocating compressor 2 side. The flange 202a abuts against an opening edge of the outer case 201. The flange 202a is fastened to the outer case 201. Furthermore, the flange 202a is fastened to the casing main body 101 with the bottom wall of the inner case 202 covering the rear cover 104 of the casing 100 of the reciprocating compressor 2. Thus, the motor case 200 is coupled to the casing 100 of the reciprocating compressor 2.

[0091] The water passage 210 through which cooling water flows is formed in the motor case 200. The water passage 210 includes a spiral part 211 formed between the outer case 201 and the inner case 202, and an upstream connection part 212 and a downstream connection part 213 connected to the spiral part 211.

[0092] The spiral part 211 is a gap between an inner circumferential surface of the outer case 201 and an outer circumferential surface of the inner case 202. On an outer circumferential surface of the inner case 202, a partition wall 202b extends spirally in the axial direction around the axis O (refer to FIG. 14). The gap between the inner circumferential surface of the outer case 201 and the outer circumferential surface of the inner case 202 extends spirally between the partition walls 202b adjacent to each other in the axial direction.

[0093] The upstream connection part 212 is provided on the outer case 201. The upstream connection part 212 passes through the outer case 201. The upstream connection part 212 is open to the inner circumferential surface of the outer case 201 and is in communication with the spiral part 211. The upstream connection part 212 is in communication with a portion of the spiral part 211 on one end side that is closer to the rear than a middle portion in the extension direction of the spiral part 211. The upstream connection part 212 is open to the control device 4 side (the rear) at an end surface of the outer case 201 in the axial direction.

[0094] The downstream connection part 213 is provided on the inner case 202. The downstream connection part 213 passes through the inner case 202. The downstream connection part 213 is open to the outer circumferential surface of the inner case 202 and is in communication with the spiral part 211. The downstream connection part 213 is in communication with a portion of the spiral part 211 on the other end side that is closer to the front than the middle portion in the extension direction of the spiral part 211. The downstream connection part 213 is open on the reciprocating compressor 2 side (the front) at the end surface of the outer case 201 in the axial direction and is in communication with the second cylinder second water passage 154 of the reciprocating compressor 2.

[0095] The motor shaft 220 is disposed in the inner space of the motor case 200. The motor shaft 220 is rotatably supported by the bottom wall of the outer case 201 and the bottom wall of the inner case 202 via bearings. The motor shaft 220 is formed to be hollow. The second main shaft M2 of the reciprocating compressor 2 is inserted into an end portion of the motor shaft 220 on the reciprocating compressor 2 side. The motor shaft 220 is coupled to the second main shaft M2 at its inner side so as not to rotate relative to the second main shaft M2.

[0096] The rotor 230 is disposed in the inner space of the motor case 200. The rotor 230 is coupled to the motor shaft 220 so as not to rotate relative to the motor shaft 220.

[0097] The stator 240 is disposed in the inner space of the motor case 200. The stator 240 is held on the inner circumferential surface of the inner case 202. The stator 240 is formed in a cylindrical shape that is coaxial with the motor shaft 220. The stator 240 is disposed to surround the rotor 230.(Control Device 4)

[0098] The control device 4 includes a control unit 300 (a control part) that controls the rotary drive source 3 and a housing 310 (a second case) that accommodates the control unit 300. The control unit 300 includes a substrate and various electronic components mounted on the substrate. The control unit 300 is disposed with its front and back surfaces of the substrate facing in the axial direction.

[0099] The housing 310 is coupled to the motor case 200 in an overlapping manner. The housing 310 is fastened to the motor case 200 from the rear. The housing 310 has an inner space in which the control unit 300 is disposed. The housing 310 includes a housing main body 311 that has a box shape and is open on the side opposite the rotary drive source 3, and a lid body 312 that closes an opening of the housing main body 311. The housing main body 311 is fastened to the outer case 201 of the motor case 200 in a state in which it covers the entire rear end surface of the motor case 200. The lid body 312 is formed in a flat plate shape. The lid body 312 is fastened to the motor case 200 with its front and back surfaces facing in the axial direction.

[0100] The housing 310 cooperates with the motor case 200 to form a cooling water flow space 320, through which the cooling water flows, between the housing 310 and the motor case 200. The motor case 200 has a rear surface 200a that faces the control device 4 (the rear) in the axial direction as a first surface that defines the cooling water flow space 320. The housing 310 has a front surface 310a that faces the rotary drive source 3 (the front) in the axial direction as a second surface that defines the cooling water flow space 320.

[0101] FIG. 15 is a view showing the rear surface of the motor case.

[0102] As shown in FIG. 15, the rear surface 200a of the motor case 200 is provided on the bottom wall of the outer case 201. The rear surface 200a includes a first recessed part 200b recessed in a direction (toward the front) away from the front surface 310a of the motor case 200, and a second recessed part 200c recessed in a direction away from the front surface 310a of the motor case 200. The first recessed part 200b and the second recessed part 200c are provided independently of each other and adjacent to each other in the circumferential direction about the axis O. The first recessed part 200b and the second recessed part 200c are located to be biased in the circumferential direction. Thus, the rear surface 200a has a fan-shaped flat part 200d in which the first recessed part 200b and the second recessed part 200c are not formed.

[0103] FIG. 16 is a view showing the front surface of the housing.

[0104] As shown in FIG. 16, the front surface 310a of the housing 310 has a plurality of groove parts 310b that are recessed in a direction (toward the rear) away from the rear surface 200a of the motor case 200. The plurality of groove parts 310b are formed in the housing main body 311. The plurality of groove parts 310b are formed at positions that overlap a heat generation element in the control unit 300 when seen in the axial direction. The plurality of groove parts 310b are parallel to each other and extend in the circumferential direction about the axis O. Each of the groove parts 310b extends from a position overlapping the first recessed part 200b, through a position overlapping the flat part 200d, to a position overlapping the second recessed part 200c when seen in the axial direction (refer to also FIGS. 12 and 14).

[0105] FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. 3.

[0106] As shown in FIGS. 15 and 17, the cooling water flow space 320 includes an inflow part 321, an outflow part 322 that is provided independently of the inflow part 321, and a communication part 323 that causes the inflow part 321 and the outflow part 322 to be in communication with each other. The inflow part 321 is defined by the first recessed part 200b. The inflow part 321 is in communication with an inflow passage 324 through which the cooling water flows in. The inflow passage 324 passes through the housing main body 311 and is connected to a cooling water pump (not shown) via an inflow pipe 326 (refer to FIG. 16) mounted in the housing main body 311. The outflow part 322 is defined by the second recessed part 200c. The outflow part 322 is in communication with an outflow passage 325 through which the cooling water flows out. The outflow passage 325 passes through the housing main body 311 and causes the outflow part 322 and the upstream connection part 212 of the water passage 210 in the motor case 200 to be in communication with each other. The communication part 323 is formed by the plurality of groove parts 310b. Cooling water flows through the communication part 323 from the inflow part 321 toward the outflow part 322.(Operation of the Reciprocating Compressor)

[0107] As shown in FIG. 10, during an operation of the reciprocating compressor 2, a rotational force is input to the second main shaft M2, and the crankshaft CR rotates around the first central axis C1. Accordingly, the first crank pin CP1 and the second crank pin CP2 revolve around the first central axis C1.

[0108] Thus, the first piston P1 connected to the first crank pin CP1 via the connecting rod CN1 moves linearly in the first direction. The linear movement of the first piston P1 is guided by the first cylinder 120. As the first piston P1 moves up and down within the first cylinder 120, a gas within the first cylinder 120 is compressed and pressurized, and is supplied to the outside through the exhaust hole 122b.

[0109] The second piston P2 connected to the second crank pin CP2 via the connecting rod CN2 moves linearly in the second direction. The linear movement of the second piston P2 is guided by the second cylinder 140. As the second piston P2 moves up and down within the second cylinder 140, a gas within the second cylinder 140 is compressed and pressurized, and is supplied to the outside through the exhaust hole 142b.

[0110] When the first piston P1 and the second piston P2 have different diameters, a so-called two-stage compression compressor may be realized. That is, a first stage of compression is performed using a large-diameter first piston P1 to pressurize a gas to approximately a desired pressure, and then a second stage of compression is performed using a small-diameter second piston P2 to adjust a pressurized state.

[0111] When the second main shaft M2 rotates around the first central axis C1, the connecting ring 161 of the oil pump 160 swings around the first central axis C1. When the connecting ring 161 swings, the stem 166 reciprocates in the up-down direction while tilting left and right with a contact portion with the pump cylinder 163 as a center. When the stem 166 moves up, a negative pressure is generated in the pump chamber 164, and the lubricating oil flows into the pump chamber 164 through the second opening 164b. When the stem 166 moves down, an internal pressure of the pump chamber 164 increases, and thus the lubricating oil inside the stem 166 that is in communication with the pump chamber 164 opens the first valve part 168 at the upper end opening of the stem 166 and flows into the through hole 161a of the connecting ring 161. Thus, the oil pump 160 discharges the lubricating oil from an opening of the through hole 161a in the inner circumferential surface of the connecting ring 161 and supplies the oil to a desired location.(Cooling Structure of Compression Device)

[0112] The compression device 1 is cooled by cooling water pumped by a cooling water pump (not shown). The cooling water pumped by the cooling water pump is introduced into the cooling water flow space 320 through the inflow pipe 326 and the inflow passage 324 of the control device 4. The cooling water introduced into the cooling water flow space 320 flows through the inflow part 321, the communication part 323, and the outflow part 322 in this order. The cooling water mainly cools a heat generation part of the control unit 300 while flowing through the communication part 323 in the cooling water flow space 320. The cooling water in the outflow part 322 is discharged from the control device 4 through the outflow passage 325 toward the rotary drive source 3.

[0113] The cooling water discharged from the control device 4 is introduced into the water passage 210 of the rotary drive source 3. The cooling water introduced into the water passage 210 flows through the upstream connection part 212, the spiral part 211, and the downstream connection part 213 in this order. The cooling water that has flowed through the downstream connection part 213 is discharged from the rotary drive source 3 toward the reciprocating compressor 2.

[0114] The cooling water discharged from the rotary drive source 3 is introduced into the second cylinder water passage 152 of the second cylinder 140 of the reciprocating compressor 2. The cooling water introduced into the second cylinder water passage 152 flows through the second cylinder second water passage 154, the second cylinder first water passage 153, and the second cylinder third water passage 155 in this order. The cooling water that has flowed through the second cylinder third water passage 155 flows toward the first cylinder water passage 131 of the first cylinder 120.

[0115] The cooling water that has flowed into the first cylinder water passage 131 flows through the first cylinder second water passage 133 and the first cylinder first water passage 132 in this order. The cooling water that has flowed through the first cylinder first water passage 132 is discharged from the reciprocating compressor 2 through the discharge pipe 134. The cooling water discharged from the reciprocating compressor 2 is cooled through a heat exchanger or the like, and is again pumped by the cooling water pump toward the control device 4.(Start-up Control of Reciprocating Compressor)

[0116] The control unit 300 controls the rotary drive source 3 to start the reciprocating compressor 2. When starting the reciprocating compressor 2 fails as a result of controlling the rotary drive source 3 to rotate the crankshaft CR, the control unit 300 performs a predetermined startup control. In this embodiment, the reciprocating compressor 2 fails to start when the crankshaft CR, which is rotated in the first rotation direction by the output of the rotary drive source 3, does not have enough run-up, and therefore does not pass through a phase (a rotation angle) of the crankshaft CR at which torque acting on the crankshaft CR is maximized. For example, the phase of the crankshaft CR at which the torque acting on the crankshaft CR is maximized is determined by at least one of a positional relationship between the first piston P1 and the first cylinder 120 and a positional relationship between the second piston P2 and the second cylinder 140 in the drive mechanism 180.

[0117] In this embodiment, due to the positional relationship between the first piston P1 and the first cylinder 120, the torque acting on the crankshaft CR reaches a maximum every time the crankshaft CR rotates by 180 degrees. Furthermore, due to the positional relationship between the second piston P2 and the second cylinder 140, the torque acting on the crankshaft CR reaches a maximum every time the crankshaft CR rotates 180 degrees. Thus, in this embodiment, the torque acting on the crankshaft CR reaches a maximum four times per rotation of the crankshaft CR.

[0118] As the predetermined start-up control, the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR again in a first rotation direction. In addition, as the predetermined start-up control, the control unit 300 may control the rotary drive source 3 to rotate the crankshaft CR in a second rotation direction (a reverse direction) opposite to the first rotation direction and then rotate the crankshaft CR again in the first rotation direction. In this case, the control unit 300 may detect a load on the crankshaft CR and determine whether or not to rotate the crankshaft CR in the reverse direction based on a magnitude of the load.

[0119] As described above, the compression device 1 of this embodiment includes the motor case 200 that accommodates the rotary drive source 3, and the housing 310 that accommodates the control unit 300 and is coupled to the motor case 200 to overlap the motor case 200 in a predetermined direction. The motor case 200 and the housing 310 define the cooling water flow space 320 therebetween, through which the cooling water flows. The motor case 200 has the rear surface 200a that defines the cooling water flow space 320. The housing 310 has the front surface 310a that defines the cooling water flow space 320. The cooling water flow space 320 has the inflow part 321, the outflow part 322 that is provided independently of the inflow part 321, and the communication part 323 that causes the inflow part 321 and the outflow part 322 to be in communication with each other and through which the cooling water flows from the inflow part 321 to the outflow part 322. The rear surface 200a has the first recessed part 200b that is recessed in the direction away from the front surface 310a and defines the inflow part 321, and the second recessed part 200c that is recessed in the direction away from the front surface 310a and defines the outflow part 322. The front surface 310a is recessed in the direction away from the rear surface 200a and has the plurality of groove parts 310b that extend from the position overlapping the first recessed part 200b to the position overlapping the second recessed part 200c when seen in a predetermined direction.

[0120] With this configuration, since the plurality of groove parts 310b through which the cooling water flows are formed in the housing 310 that accommodates the control unit 300, a surface area of the housing 310 that comes into contact with the cooling water is ensured, and the control unit 300 can be cooled efficiently.

[0121] The compression device 1 includes the motor case 200 that accommodates the rotary drive source 3. The motor case 200 includes the inner case 202 that holds the stator 240, and the outer case 201 that surrounds the inner case 202. The inner case 202 and the outer case 201 define the water passage 210 between them through which the cooling water flows. The water passage 210 extends spirally around the axis O of the rotary drive source 3.

[0122] With this configuration, the cooling water can be circulated around the entire circumference of the motor case 200 that accommodates the rotary drive source 3. Therefore, the rotary drive source 3 can be efficiently cooled.

[0123] The compression device 1 includes the first compression element that compresses gas using the rotation of the crankshaft CR as power, and the second compression element that further compresses the compressed gas discharged from the first compression element using the rotation of the crankshaft CR as power. The first compression element includes the first piston P1 connected to the crankshaft CR, and the first cylinder block 121 having the first cylinder chamber 124 into which the first piston P1 is slidably fitted. The second compression element includes the second piston P2 connected to the crankshaft CR, and the second cylinder block 141 having the second cylinder chamber 144 into which the second piston P2 is slidably fitted. The first cylinder block 121 has the first cylinder water passage 131 through which the cooling water flows. The second cylinder block 141 has the second cylinder water passage 152 through which the cooling water flowing into the first cylinder water passage 131 flows.

[0124] With this configuration, in the first cylinder block 121 and the second cylinder block 141, the second cylinder block 141 which becomes hotter due to heat exchange with the compressed gas can be cooled with the low-temperature cooling water in a state before heat exchange with the first cylinder block 121. Therefore, the first compression element and the second compression element can be cooled efficiently.

[0125] The first cylinder block 121 has the exhaust passage 130 through which the compressed gas discharged from the first compression element passes, and the first cylinder water passage 131 formed between the exhaust passage 130 and the first cylinder chamber 124 and through which the cooling water flows. The second cylinder block 141 has the intake passage 150 and the exhaust passage 151 through which the compressed gas discharged from the first compression element passes, and the second cylinder water passage 152 formed between each of the intake passage 150 and the exhaust passage 151 and the second cylinder chamber 144 and through which the cooling water flows.

[0126] With this configuration, since the first cylinder water passage 131 is formed between the wall surface of the first cylinder chamber 124 which performs heat exchange with the compressed air, and the wall surface of the exhaust passage 130, the wall part of the first cylinder chamber 124 and the wall part of the exhaust passage 130 can be efficiently cooled. In addition, since the second cylinder water passage 152 is formed between the wall surface of the second cylinder chamber 144 which performs heat exchange with the compressed air, and the wall surfaces of the intake passage 150 and the exhaust passage 151, the wall parts of the second cylinder chamber 144, the intake passage 150, and the exhaust passage 151 can be efficiently cooled.

[0127] The first compression element has the first cylinder head cover 123 that forms the intake chamber 125 and the exhaust chamber 126 that are in communication with the first cylinder chamber 124 between the first cylinder head 122 and the first cylinder head cover 123. The first cylinder head cover 123 has the wall surface 123a that defines the intake chamber 125 and the exhaust chamber 126 and has the plurality of recessed parts 123b formed therein.

[0128] With this configuration, the plurality of recessed parts 123b can reflect and attenuate vibrations of the air in the intake chamber 125 and the exhaust chamber 126 in a complex manner. The same applies to the recessed parts 143b of the second cylinder head cover 143 of the second compression element. Therefore, the sound emitted by the compression element is attenuated, and the compression device 1 can be provided with reduced noise generation.

[0129] The compression device 1 includes the first cylinder 120 having the first cylinder chamber 124 and the intake chamber 125 that is in communication with the external air, the casing 100 having the crank chamber that accommodates the crankshaft CR, and the communication pipe 136 that causes the intake chamber 125 and the crank chamber to be in communication with each other.

[0130] With this configuration, since the crank chamber is in communication with the intake chamber 125, pressure fluctuations in the crank chamber caused by the displacement of the pistons P1 and P2 can be alleviated. Thus, it is possible to prevent gas and lubricating oil from leaking from the crank chamber due to the pressure fluctuations in the crank chamber. Further, it is possible to curb problems with the supply of the lubricating oil from occurring due to fluctuations in supply pressure of the lubricating oil in the crank chamber caused by the pressure fluctuations in the crank chamber. Furthermore, it is possible to curb fluctuations in the load applied to the drive parts such as the pistons P1 and P2 due to the pressure fluctuations in the crank chamber.

[0131] FIGS. 18 and 19 are graphs showing a relationship between the rotation angle of the crankshaft and the torque acting on the crankshaft in the reciprocating compressor of the embodiment. In FIGS. 18 and 19, a horizontal axis represents the rotation angle of the crankshaft CR, and a vertical axis represents the torque acting on the crankshaft CR.

[0132] As shown in FIG. 18, in the case of the start-up of the reciprocating compressor 2, when starting torque input to the crankshaft CR is insufficient as shown by (1) in the drawing and the reciprocating compressor 2 fails to start, the crankshaft CR receives a reaction force and rotates in the reverse direction to pass through a start position. In this embodiment, when the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR and fails to start the reciprocating compressor 2, the control unit 300 controls the rotary drive source 3 again to rotate the crankshaft CR.

[0133] With this configuration, by rotating the crankshaft CR again, it is possible to ensure a larger run-up angle of the crankshaft CR than at the time of the previous start, and thus it is possible to improve a probability of successful start of the reciprocating compressor 2. In the example shown in FIG. 18, a second starting operation shown in (2) in the drawing is able to secure a larger run-up angle of the crankshaft CR than a first starting operation shown in (1) in the drawing, but fails to start the reciprocating compressor 2. Furthermore, in a third starting operation shown in (3) in the drawing, the run-up angle of the crankshaft CR can be secured more than in the second starting operation, and the reciprocating compressor 2 is successfully started. Therefore, the reciprocating compressor 2 can be reliably started.

[0134] When the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR in the first rotation direction and fails to start the reciprocating compressor 2, the control unit 300 may control the rotary drive source 3 to rotate the crankshaft CR in the second rotation direction and then rotate it in the first rotation direction again.

[0135] With this configuration, as shown in FIG. 19, when the starting torque input to the crankshaft CR in the first rotation direction is insufficient and the reciprocating compressor 2 fails to start at (1) in the drawing, the crankshaft CR can be rotated in the reverse direction to pass through the starting position by rotating the crankshaft CR in the second rotation direction at (2) in the drawing. Therefore, by rotating the crankshaft CR again in the first rotation direction at (3) in the drawing, it is possible to ensure a larger run-up angle of the crankshaft CR than at the previous start, thereby improving the probability of successful start of the reciprocating compressor 2. Therefore, the reciprocating compressor 2 can be started reliably.

[0136] The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications are possible within the technical scope of the present invention.

[0137] For example, in the above embodiment, the reciprocating compressor 2 is configured to generate compressed air, but the compressed gas generated by the reciprocating compressor is not limited to air. For example, the reciprocating compressor may be configured to compress a refrigerant.

[0138] Furthermore, although the reciprocating compressor 2 in the above embodiment is a two-cylinder and two-stage reciprocating compressor, the compression device to which the present invention is applied is not limited to one equipped with the two-stage reciprocating compressor. That is, the present invention may be applied to a single-cylinder reciprocating compressor, or to a multi-stage reciprocating compressor having three or more cylinders.

[0139] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the gist of the present invention.

[0140] Among the embodiments disclosed in this specification, those that are configured of multiple members may be integrated into one member, and conversely, those that are configured of a single member may be separated into multiple members. Regardless of whether they are integrated or not, they may be configured to achieve the object of the invention.INDUSTRIAL APPLICABILITY

[0141] According to the present invention, it is possible to provide a compression device and an oil pump having excellent cooling efficiency.REFERENCE SIGNS LIST

[0142] 1 Compression device 2 Reciprocating compressor 3 Rotary drive source 100 Casing (crankcase) 121 First cylinder block 123 First cylinder head cover (cylinder head cover) 123a Wall surface 123b Recessed part 124 First cylinder chamber (cylinder chamber) 125 Intake chamber (air chamber) 131 First cylinder water passage 141 Second cylinder block 143 Second cylinder head cover (cylinder head cover) 143a Wall surface 143b Recessed part 144 Second cylinder chamber (cylinder chamber) 145 Intake chamber (air chamber) 146 Exhaust chamber (air chamber) 152 Second cylinder water passage 160 Oil pump 161 Connecting ring 161a Through hole 163 Pump cylinder 164 Pump chamber 164a First opening 164b Second opening 166 Stem 168 First valve part 169 Second valve part 171 Filter 200b First recessed part 200c Second recessed part 201 Outer case 202 Inner case 210 Water passage 230 Rotor 240 Stator 300 Control unit (control part) 310b Groove part 320 Cooling water flow space 321 Inflow part 322 Outflow part 323 Communication part C1 First central axis CR Crankshaft (rotary shaft) E1 Eccentric part (eccentric shaft) M1 First main shaft (main shaft) M2 Second main shaft (main shaft) O Axis (rotation axis) P1 First piston (piston) P2 Second piston (piston)

Examples

Embodiment Construction

[0027]Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of the components may be omitted.

[0028]FIGS. 1 and 2 are perspective views showing an exterior of a compression device according to an embodiment.

[0029]As shown in FIGS. 1 to 3, the compression device 1 includes a reciprocating compressor 2, a rotary drive source 3, and a control device 4. The rotary drive source 3 outputs a rotary drive force about an axis O to drive the reciprocating compressor 2. Hereinafter, a direction in which the axis O extends will be referred to as an axial direction. In this embodiment, the axial direction is parallel to a horizontal direction. The reciprocating compressor 2, the rotary drive source 3, and the control device 4 are arranged in this order in the axial direction. In the axial direction, a d...

TECHNICAL FIELD

[0001] The present invention relates to a compression device and an oil pump.

[0002] Priority is claimed on Japanese Patent Application No. 2023-103652, filed June 23, 2023, the content of which is incorporated herein by reference.BACKGROUND ART

[0003] A compression device including a reciprocating compressor that generates high-pressure compressed air is known. The compressed air compressed in a cylinder of the reciprocating compressor is supplied to a pneumatic machine via a discharge port. Since compression heat is generated in a process of compressing air, temperatures of a cylinder and a piston rise during operation of the reciprocating compressor. Furthermore, since an electric motor that drives the reciprocating compressor is driven by an applied current, Joule heat is generated by the applied current. Thus, a temperature of the electric motor also increases. Furthermore, a control unit that controls the electric motor also generates heat. Two-stage reciprocating compressors which compress air in two stages are also known. The two-stage reciprocating compressor includes a low-pressure side cylinder and a high-pressure side cylinder. In the two-stage reciprocating compressor, air compressed in the low-pressure side cylinder is transferred to the high-pressure side cylinder and is further compressed in the high-pressure side cylinder.Citation ListPatent Document

[0004] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H09-264253SUMMARY OF INVENTIONTechnical Problem

[0005] There is a demand for further improvement in a cooling effect in a compression device having a reciprocating compressor, particularly in a two-stage reciprocating compressor in which compression heat generated when air is compressed may increase.

[0006] Therefore, the present invention is to provide a compression device and an oil pump which have excellent cooling efficiency.Solution to Problem

[0007] A compression device according to a first aspect of the present invention includes a rotary drive source, a first case configured to accommodate the rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a compression element configured to compress gas using rotation of the rotary shaft as power, a control unit configured to control the rotary drive source, and a second case configured to accommodate the control unit and which is coupled to the first case to overlap the first case in a predetermined direction, wherein the first case and the second case define a cooling water flow space therebetween through which cooling water flows, the first case has a first surface that defines the cooling water flow space, the second case has a second surface that defines the cooling water flow space, the cooling water flow space has an inflow part, an outflow part provided independently of the inflow part, and a communication part that causes the inflow part and the outflow part to be in communication with each other and allows the cooling water to flow from the inflow part to the outflow part, the first surface has a first recessed part that is recessed in a direction away from the second surface and defines the inflow part, and a second recessed part that is recessed in a direction away from the second surface and defines the outflow part, and the second surface has a plurality of groove parts that are recessed in a direction away from the first surface and extend from a position overlapping the first recessed part to a position overlapping the second recessed part when seen in the predetermined direction.

[0008] According to the first aspect, since the plurality of groove parts through which the cooling water flows are formed in the second case that accommodates the control unit, a surface area in the second case that comes into contact with the cooling water is ensured, and thus the control unit can be cooled efficiently.

[0009] A compression device according to a second aspect of the present invention includes a rotary drive source having a rotor and a stator disposed around the rotor, a case configured to accommodate the rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the case includes an inner case that holds the stator, and an outer case that surrounds the inner case, the inner case and the outer case form a water passage therebetween through which cooling water flows, and the water passage extends spirally around a rotation axis of the rotary drive source.

[0010] According to the second aspect, the cooling water can be circulated around the entire circumference of the inside of the case that accommodates the rotary drive source. Therefore, the rotary drive source can be efficiently cooled.

[0011] A compression device according to a third aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a first compression element configured to compress gas using rotation of the rotary shaft as power, and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein the first compression element includes a first piston connected to the rotary shaft, and a first cylinder block having a first cylinder chamber into which the first piston is slidably fitted, the second compression element includes a second piston connected to the rotary shaft, and a second cylinder block having a second cylinder chamber into which the second piston is slidably fitted, the first cylinder block has a first cylinder water passage through which cooling water flows, and the second cylinder block has a second cylinder water passage through which the cooling water flowing into the first cylinder water passage flows.

[0012] According to the third aspect, in the first and second cylinder blocks, the second cylinder block which becomes hotter due to heat exchange with the compressed gas can be cooled with low-temperature cooling water before heat exchange with the first cylinder block. Therefore, the first compression element and the second compression element can be cooled efficiently.

[0013] A compression device according to a fourth aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, a first compression element configured to compress gas using rotation of the rotary shaft as power, and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein at least one of the first compression element and the second compression element has a piston connected to the rotary shaft, and a cylinder block having a cylinder chamber into which the piston is slidably fitted, and the cylinder block has a ventilation passage through which the compressed gas discharged from the first compression element passes, and a water passage formed between the ventilation passage through and the cylinder chamber and through which cooling water flows.

[0014] According to the fourth aspect, since the water passage is formed between the wall surface of the cylinder chamber and the wall surface of the ventilation passage through which perform heat exchange with the compressed air, wall parts of the cylinder chamber and the ventilation passage through can be efficiently cooled.

[0015] A compression device according to a fifth aspect of the present invention includes a rotary drive source, a rotary shaft configured to rotate due to an output of the rotary drive source, and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the compression element includes a piston connected to the rotary shaft, a cylinder block having a cylinder chamber into which the piston is slidably fitted, a cylinder head that is fixed to the cylinder block and defines the cylinder chamber on the side opposite the piston, and a cylinder head cover that covers the cylinder head from the side opposite the cylinder block and forms an air chamber, which is in communication with the cylinder chamber, between the cylinder head and the cylinder head cover, and the cylinder head cover has a wall surface that defines the air chamber and has a plurality of recessed parts formed therein.

[0016] According to the fifth aspect, the plurality of recessed parts can reflect and attenuate vibrations of the air in the air chamber in a complex manner. Therefore, sound emitted by the compression element is attenuated, and a compression device that suppresses noise generation can be provided.

[0017] A compression device according to a sixth aspect of the present invention includes a rotary drive source, a crankshaft configured to rotate due to an output of the rotary drive source, a piston connected to the crankshaft, a cylinder having a cylinder chamber into which the piston is slidably fitted, and an intake chamber that is in communication with the cylinder chamber and external air, a crankcase having a crank chamber that accommodates the crankshaft, and a connection part configured to cause the intake chamber and the crank chamber to be communicating with respect to each other.

[0018] According to the sixth aspect, since the crank chamber is in communication with the intake chamber, pressure fluctuations in the crank chamber caused by a displacement of the piston can be alleviated. Thus, it is possible to curb leakage of gas, lubricating oil, or the like from the crank chamber due to the pressure fluctuations in the crank chamber. It is also possible to curb problems with the supply of the lubricating oil occurring due to fluctuations in supply pressure of the lubricating oil in the crank chamber caused by the pressure fluctuations in the crank chamber. Furthermore, it is possible to curb fluctuations in a load applied to drive parts such as the pistons due to the pressure fluctuations in the crank chamber.

[0019] An oil pump according to a seventh aspect of the present invention includes a connecting ring fitted onto an eccentric shaft to be rotatable relative to the eccentric shaft, having an inner circumferential surface and an outer circumferential surface, and having a through hole that is open to the inner circumferential surface and the outer circumferential surface, a pump cylinder having a pump chamber configured to extend in a pump axial direction perpendicular to an axial direction of the eccentric shaft and having a first opening that is open toward the connecting ring and a second opening that is provided separately from the first opening, a hollow stem having a first end portion inserted into the through hole from the outer circumferential surface and a second end portion inserted into the pump chamber through the first opening, the second end portion being in sliding contact with a wall surface of the pump chamber in a liquid-tight manner while being movable in the pump axial direction within the pump chamber and tiltable relative to the pump cylinder, thereby causing the through hole and the pump chamber to be in communication with each other, a first valve part configured to allow a flow of liquid from an inner space of the stem to the through hole and block the flow of liquid from the through hole to the inner space of the stem, a second valve part configured to close the second opening of the pump chamber in an openable manner, allow a flow of liquid from an outer space of the pump cylinder to the pump chamber, and block the flow of liquid from the pump chamber to the outer space of the pump cylinder, and a filter configured to cover the second opening from the outside of the pump cylinder.

[0020] According to the seventh aspect, when the eccentric shaft is rotated, the connecting ring swings. When the connecting ring swings, the stem reciprocates in a pump axial direction while tilting around a contact portion with the pump cylinder. When the stem moves, and negative pressure is generated in the pump chamber, liquid flows into the pump chamber through the second opening. As internal pressure of the pump chamber increases with the movement of the stem, the lubricating oil inside the stem, which is in communication with the pump chamber, opens the first valve part and flows into the through hole of the connecting ring. Thus, the oil pump discharges the liquid from an opening of the through hole in the inner circumferential surface of the connecting ring. As described above, it is possible to provide an oil pump that operates using the rotation of the eccentric shaft.

[0021] A compression device according to an eighth aspect of the present invention includes a rotary drive source, a reciprocating compressor operated by an output of the rotary drive source, and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes a casing, a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source, a piston connected to the crank pin, and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, and when the control unit controls the rotary drive source to rotate the crankshaft but fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft.

[0022] When the starting torque input to the crankshaft is insufficient and the reciprocating compressor fails to start, the crankshaft receives a reaction force and rotates in a reverse direction to pass through a starting position. According to the eighth aspect, by rotating the crankshaft again, it is possible to ensure a larger run-up angle of the crankshaft than at the time of the previous start, and thus it is possible to improve a probability of successful start of the reciprocating compressor. Therefore, the reciprocating compressor can be reliably started.

[0023] A compression device according to a ninth aspect of the present invention includes a rotary drive source, a reciprocating compressor operated by an output of the rotary drive source, and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes a housing, a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source, a piston connected to the crank pin, and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, and when the control unit controls the rotary drive source to rotate the crankshaft in a first rotation direction and fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft in a second rotation direction opposite to the first rotation direction and then rotate the crankshaft in the first rotation direction.

[0024] According to the ninth aspect, when the starting torque input to the crankshaft in a first rotation direction is insufficient and the reciprocating compressor fails to start, the crankshaft can be rotated in the reverse direction to pass through the starting position by rotating the crankshaft in a second rotation direction. Therefore, by rotating the crankshaft in the first rotation direction again, it is possible to ensure a larger run-up angle of the crankshaft than at the previous start, thereby improving a probability of successful start of the reciprocating compressor. Therefore, the reciprocating compressor can be started reliably.Advantageous Effects of Invention

[0025] According to the present invention, it is possible to provide a compression device and an oil pump which have excellent cooling efficiency.BRIEF DESCRIPTION OF DRAWINGS

[0026] [FIG. 1] A perspective view showing an exterior of a compression device according to an embodiment. [FIG. 2] A perspective view showing the exterior of the compression device according to the embodiment. [FIG. 3] A cross-sectional view taken along line III-III in FIG. 1. [FIG. 4] A cross-sectional view taken along line IV-IV in FIG. 1. [FIG. 5] A cross-sectional view taken along line V-V in FIG. 3. [FIG. 6] A bottom view of a first cylinder head cover according to the embodiment when seen from the first cylinder head side. [FIG. 7] A perspective view showing an exhaust-side valve member. [FIG. 8] A perspective view showing a part of the exhaust-side valve member shown in FIG. 7. [FIG. 9] A cross-sectional view taken along line IX-IX in FIG. 3. [FIG. 10] A side view of a drive mechanism according to the embodiment. [FIG. 11] A plan view of the drive mechanism according to the embodiment. [FIG. 12] A front view of the drive mechanism according to the embodiment. [FIG. 13] A cross-sectional view of a reciprocating compressor according to the embodiment, which shows an enlarged vertical cross section including an axis O. [FIG. 14] A perspective view showing an inner case. [FIG. 15] A view showing a rear surface of a motor case. [FIG. 16] A view showing a front surface of a housing. [FIG. 17] A cross-sectional view taken along line XVII-XVII in FIG. 3. [FIG. 18] A graph showing a relationship between a rotation angle of a crankshaft and a torque acting on the crankshaft in a reciprocating compressor of the embodiment. [FIG. 19] A graph showing the relationship between the rotation angle of the crankshaft and the torque acting on the crankshaft in the reciprocating compressor of the embodiment. DESCRIPTION OF EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of the components may be omitted.

[0028] FIGS. 1 and 2 are perspective views showing an exterior of a compression device according to an embodiment.

[0029] As shown in FIGS. 1 to 3, the compression device 1 includes a reciprocating compressor 2, a rotary drive source 3, and a control device 4. The rotary drive source 3 outputs a rotary drive force about an axis O to drive the reciprocating compressor 2. Hereinafter, a direction in which the axis O extends will be referred to as an axial direction. In this embodiment, the axial direction is parallel to a horizontal direction. The reciprocating compressor 2, the rotary drive source 3, and the control device 4 are arranged in this order in the axial direction. In the axial direction, a direction in which the reciprocating compressor 2 is disposed relative to the rotary drive source 3 is defined as the front, and a direction opposite thereto is defined as the rear.(Reciprocating Compressor)

[0030] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1.

[0031] As shown in FIGS. 1 to 3 , the reciprocating compressor 2 is a two-stage reciprocating compressor. In this embodiment, the reciprocating compressor 2 takes in external air to generate compressed air and supplies the generated compressed air to a pneumatic machine (not shown). The reciprocating compressor 2 includes a casing (a crankcase) 100, a first cylinder 120 and a second cylinder 140 mounted in the casing 100, and a two-axis oscillating linear drive mechanism 180 provided within the casing 100 and within the first cylinder 120 and the second cylinder 140. Hereinafter, the two-axis oscillating linear drive mechanism 180 will be simply referred to as a drive mechanism 180.

[0032] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1.

[0033] As shown in FIGS. 3 and 4, the casing 100 is formed to have a hollow box shape. The casing 100 includes a casing main body 101, a bottom plate 102, a front cover 103, and a rear cover 104. The casing main body 101 is a strength member of the casing 100. The casing main body 101 includes an eye bolt 106 that protrudes upward (refer to FIGS. 1 and 2). The casing main body 101 has a lower opening closed by the bottom plate 102, a front opening closed by the front cover 103, and a rear opening closed by the rear cover 104. The bottom plate 102 is disposed on a bottom surface of the casing 100 and is fastened to the casing main body 101. The front cover 103 is disposed on a front surface of the casing 100 and is fastened to the casing main body 101. A recessed part 103a that is coaxial with the axis O is formed in an inner surface of the front cover 103. The rear cover 104 is disposed on a rear surface of the casing 100 and is fastened to the casing main body 101. A through hole 104a that is coaxial with the axis O is formed in the rear cover 104. An inner space of the casing 100 is a crank chamber that accommodates the drive mechanism 180. A lower portion of the inner space of the casing 100 forms an oil reservoir that is defined from below by the bottom plate 102.

[0034] The first cylinder 120 protrudes upward from the casing main body 101 in a first direction. The second cylinder 140 protrudes upward from the casing main body 101 in a second direction. In this embodiment, the first direction and the second direction are perpendicular to each other.

[0035] The first cylinder 120 includes a first cylinder block 121, a first cylinder head 122, and a first cylinder head cover 123. The first cylinder block 121 is coupled to the casing 100. The first cylinder head 122 is fixed to the first cylinder block 121 from the side opposite the casing main body 101. The first cylinder head cover 123 covers the first cylinder head 122 from the side opposite the first cylinder block 121. The first cylinder head cover 123 is fixed to the first cylinder head 122.

[0036] The first cylinder block 121 includes a first cylinder chamber 124 that extends in the first direction. The first cylinder chamber 124 is open on both sides in the first direction and is in communication with the inner space of the casing 100. A first piston P1 is slidably fitted into the first cylinder chamber 124 from the inner space side of the casing main body 101. The first cylinder block 121 includes a first cylinder liner 121a that has a cylindrical shape and forms an inner circumferential surface of the first cylinder chamber 124, and a first cylinder block main body 121b in which the first cylinder liner 121a is mounted. The first cylinder block main body 121b is formed integrally with the casing main body 101. The first cylinder block main body 121b is formed to have a tubular shape that is open at both ends in the first direction and is in communication with the inner space of the casing main body 101. The first cylinder liner 121a is fitted inside the first cylinder block 121.

[0037] FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3.

[0038] As shown in FIGS. 3 and 5, an exhaust passage 130 through which a gas forcibly fed by the reciprocating compressor 2 flows and a first cylinder water passage 131 through which cooling water flows are formed in the first cylinder block 121. The exhaust passage 130 is a part of a ventilation passage through which the compressed air discharged from the first cylinder chamber 124 passes. The exhaust passage 130 is formed in the first cylinder block main body 121b. The exhaust passage 130 extends in the first direction and opens into an end surface of the first cylinder block 121 on the first cylinder head 122 side. The exhaust passage 130 extends around the first cylinder chamber 124 so as to surround a part of the first cylinder chamber 124 when seen in the first direction.

[0039] The first cylinder water passage 131 includes a first cylinder first water passage 132 and a first cylinder second water passage 133 through which the cooling water flowing into the first cylinder first water passage 132 flows.

[0040] The first cylinder first water passage 132 is formed between the first cylinder liner 121a and the first cylinder block main body 121b. More specifically, the first cylinder first water passage 132 is a gap between an outer circumferential surface of the first cylinder liner 121a and an inner circumferential surface of the first cylinder block main body 121b. The first cylinder first water passage 132 extends annularly around the entire circumference of the first cylinder chamber 124. The first cylinder first water passage 132 extends in the first direction between a pair of annular seal members spaced apart in the first direction and interposed between the outer circumferential surface of the first cylinder liner 121a and the inner circumferential surface of the first cylinder block main body 121b. Both ends of the first cylinder first water passage 132 in the first direction are sealed by seal members. The first cylinder first water passage 132 is in communication with the outside of the first cylinder 120 through a discharge pipe 134 mounted in the first cylinder block main body 121b.

[0041] The first cylinder second water passage 133 is directly connected to the first cylinder first water passage 132. The first cylinder second water passage 133 is formed in the first cylinder block main body 121b. The first cylinder second water passage 133 is located on the side opposite the first cylinder chamber 124 with the first cylinder first water passage 132 interposed therebetween. The first cylinder second water passage 133 extends in the first direction and opens to an end surface of the first cylinder block 121 on the first cylinder head 122 side. An opening of the first cylinder second water passage 133 on the first cylinder head 122 side is tightly closed by the first cylinder head 122. The first cylinder second water passage 133 extends around the first cylinder chamber 124 so as to surround a part of the first cylinder chamber 124 when seen in the first direction. The first cylinder second water passage 133 is connected to the first cylinder first water passage 132 at one end when seen in the first direction, and is connected to the second cylinder water passage 152, which will be described below, at the other end when seen in the first direction. The first cylinder second water passage 133 opens on the inner circumferential surface of the first cylinder block main body 121b in an extension direction (a circumferential direction) of the first cylinder first water passage 132 when seen in the first direction. Thus, the cooling water discharged from the first cylinder second water passage 133 flows to circulate through the first cylinder first water passage 132.

[0042] The first cylinder water passage 131 is located between the entire exhaust hole 122b and the first cylinder chamber 124. In this embodiment, the first cylinder first water passage 132 and the first cylinder second water passage 133 are located between the exhaust hole 122b and the first cylinder chamber 124.

[0043] As shown in FIGS. 3 and 4, the first cylinder head 122 defines the first cylinder chamber 124 from the side opposite the first piston P1. The first cylinder head 122 is formed in a plate shape. The first cylinder head 122 is disposed so as to overlap the end surface of the first cylinder block 121. An intake hole 122a and the exhaust hole 122b that are in communication with the first cylinder chamber 124, and a ventilation hole 122c that is in communication with the exhaust passage 130 are formed in the first cylinder head 122. The intake hole 122a, the exhaust hole 122b, and the ventilation hole 122c pass through the first cylinder head 122 in the first direction. At least one of the intake hole 122a and the exhaust hole 122b may be formed in plurality and arranged in a predetermined direction. For example, the intake hole 122a and the exhaust hole 122b may be arranged in accordance with an exterior of the opening of the first cylinder chamber 124. A plurality of ventilation holes 122c may be formed and arranged in a predetermined direction. For example, the ventilation holes 122c may be arranged in a straight line in accordance with a shape of the opening of the exhaust passage 130.

[0044] The first cylinder head cover 123 forms an intake chamber 125 and an exhaust chamber 126 that are in communication with the first cylinder chamber 124 between the first cylinder head cover 123 and the first cylinder head 122. The intake chamber 125 and the exhaust chamber 126 are independent of each other. The intake chamber 125 is in communication with the first cylinder chamber 124 through the intake hole 122a, and is also in communication with external air through an intake pipe 129 mounted in the first cylinder head cover 123. The exhaust chamber 126 is in communication with the first cylinder chamber 124 through the exhaust hole 122b, and is also in communication with the exhaust passage 130 through the ventilation hole 122c.

[0045] FIG. 6 is a bottom view of the first cylinder head cover according to the embodiment, when seen from the first cylinder head side.

[0046] As shown in FIGS. 3 and 6, the first cylinder head cover 123 has a wall surface 123a that defines each of the intake chamber 125 and the exhaust chamber 126. A plurality of recessed parts 123b are formed in the wall surface 123a. The recessed parts 123b are formed in the wall surface 123a at a location that defines the intake chamber 125 and at a location that defines the exhaust chamber 126, respectively. The plurality of recessed parts 123b form a so-called honeycomb structure in which the recessed parts 123b formed in a regular hexagonal shape when seen in the first direction are planarly filled. However, a shape of each of the recessed parts is not limited to a regular hexagon and may be, for example, a rectangular or circular shape.

[0047] As shown in FIG. 3, an intake-side valve member 127 and an exhaust-side valve member 128 are provided at the first cylinder head 122. The intake-side valve member 127 and the exhaust-side valve member 128 are each a check valve.

[0048] The intake-side valve member 127 is disposed in the first cylinder chamber 124. The intake-side valve member 127 allows a flow of gas from the intake chamber 125 to the first cylinder chamber 124, and also blocks a flow of gas from the first cylinder chamber 124 to the intake chamber 125. The intake-side valve member 127 is formed in a thin plate shape and is disposed along a surface of the first cylinder head 122 on the first cylinder chamber 124 side. The intake-side valve member 127 is sandwiched between the first cylinder block 121 and the first cylinder head 122 and is held at a position along the surface of the first cylinder head 122 on the first cylinder chamber 124 side. The intake-side valve member 127 receives negative pressure in the first cylinder chamber 124 and deforms to be away from an opening edge of the intake hole 122a, thereby allowing communication between the intake chamber 125 and the first cylinder chamber 124.

[0049] The exhaust-side valve member 128 is disposed in the exhaust chamber 126. The exhaust-side valve member 128 allows a flow of gas from the first cylinder chamber 124 to the exhaust chamber 126, and also blocks a flow of gas from the exhaust chamber 126 to the first cylinder chamber 124.

[0050] FIG. 7 is a perspective view showing an exhaust-side valve member, and FIG. 8 is a perspective view showing a part of the exhaust-side valve member shown in FIG. 7.

[0051] As shown in FIGS. 7 and 8, the exhaust-side valve member 128 includes a valve main body 128a formed in a thin plate shape and disposed along the surface of the first cylinder head 122 on the exhaust chamber 126 side, and a retaining member 128b that holds the valve main body 128a. The valve main body 128a is formed to be elongated in plan view. The retaining member 128b is formed to be elongated along the valve main body 128a and is detachably fixed to the first cylinder head 122. The retaining member 128b holds both ends of the valve main body 128a between the retaining member 128b and the first cylinder head 122. The retaining member 128b is provided to cover the valve main body 128a with a gap therebetween, and allows the valve main body 128a to deform so as to be away from the opening edge of the exhaust hole 122b. The valve main body 128a receives negative pressure in the exhaust chamber 126 and deforms to be away from the opening edge of the exhaust hole 122b, thereby allowing communication between the first cylinder chamber 124 and the exhaust chamber 126 .

[0052] As shown in FIG. 1, a communication pipe 136 is connected to the first cylinder 120. The communication pipe 136 is disposed outside the casing 100. The communication pipe 136 is connected to the front cover 103 of the casing 100 and the first cylinder head cover 123. The communication pipe 136 extends in the horizontal direction or in a direction inclined upward from the horizontal direction from a connection part with the front cover 103 to a connection part with the first cylinder head cover 123. The communication pipe 136 is a connection part that communicates the inner space of the casing 100 with the intake chamber 125. Thus, the communication pipe 136 communicates the inner space of the casing 100 with the external air.

[0053] As shown in FIGS. 3 and 4, the second cylinder 140 includes a second cylinder block 141, a second cylinder head 142, and a second cylinder head cover 143. The second cylinder block 141 is coupled to the casing 100. The second cylinder head 142 is fixed to the second cylinder block 141 from the side opposite the casing main body 101. The second cylinder head cover 143 covers the second cylinder head 142 from the side opposite the second cylinder block 141. The second cylinder head cover 143 is fixed to the second cylinder head 142.

[0054] The second cylinder block 141 includes a second cylinder chamber 144 extending in the second direction. The second cylinder chamber 144 is open on both sides in the second direction and is in communication with the inner space of the casing 100. The second cylinder chamber 144 has a smaller diameter than the first cylinder chamber 124. A second piston P2 is slidably inserted into the second cylinder chamber 144 from the inner space side of the casing main body 101. The second cylinder block 141 includes a second cylinder liner 141a that has a cylindrical shape and forms an inner circumferential surface of the second cylinder chamber 144, and a second cylinder block main body 141b in which the second cylinder liner 141a is mounted. The second cylinder block main body 141b is formed integrally with the casing main body 101. The second cylinder block main body 141b is formed in a tubular shape that is open at both ends in the second direction and is in communication with the inner space of the casing main body 101. The second cylinder liner 141a is fitted inside the second cylinder block 141.

[0055] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 3.

[0056] As shown in FIGS. 3 and 9, an intake passage 150 and an exhaust passage 151 through which the gas forcibly fed by the reciprocating compressor 2 flows, and a second cylinder water passage 152 through which cooling water flows are formed in the second cylinder block 141. The intake passage 150 and the exhaust passage 151 are part of the ventilation passage through which compressed air discharged from the first cylinder chamber 124 passes. The intake passage 150 and the exhaust passage 151 are formed in the first cylinder block main body 121b. The intake passage 150 is in direct communication with the exhaust passage 130 of the first cylinder 120. The intake passage 150 extends in the second direction and is open at an end surface of the second cylinder block 141 on the second cylinder head 142 side. The intake passage 150 extends around the second cylinder chamber 144 at a position on the first cylinder 120 side relative to the second cylinder chamber 144 so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The exhaust passage 151 extends in the second direction and is open to an end surface of the second cylinder block 141 on the second cylinder head 142 side. The exhaust passage 151 extends around the second cylinder chamber 144 at a position on the side opposite the intake passage 150 with the second cylinder chamber 144 interposed therebetween so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The exhaust passage 151 is in communication with the outside of the compression device 1 through an exhaust pipe 156 mounted in the second cylinder block main body 141b.

[0057] The second cylinder water passage 152 includes a second cylinder first water passage 153, a second cylinder second water passage 154 through which cooling water flowing into the second cylinder first water passage 153 flows, and a second cylinder third water passage 155 through which cooling water flowing out of the second cylinder first water passage 153 and flowing into the first cylinder second water passage 133 flows.

[0058] The second cylinder first water passage 153 is formed between the second cylinder liner 141a and the second cylinder block main body 141b. More specifically, the second cylinder first water passage 153 is a gap between an outer circumferential surface of the second cylinder liner 141a and an inner circumferential surface of the second cylinder block main body 141b. The second cylinder first water passage 153 extends annularly around the entire circumference of the second cylinder chamber 144. The second cylinder first water passage 153 extends in the second direction between a pair of annular seal members spaced apart in the second direction. The pair of seal members are interposed between the outer circumferential surface of the second cylinder liner 141a and the inner circumferential surface of the second cylinder block main body 141b. Both ends of the second cylinder first water passage 153 in the second direction are sealed by the seal members.

[0059] The second cylinder second water passage 154 is directly connected to the second cylinder first water passage 153. The second cylinder second water passage 154 is formed in the second cylinder block main body 141b. The second cylinder second water passage 154 is located on the side opposite the second cylinder chamber 144 with the second cylinder first water passage 153 interposed therebetween. The second cylinder second water passage 154 extends in the second direction and is open to the end surface of the second cylinder block 141 on the second cylinder head 142 side. An opening of the second cylinder second water passage 154 on the second cylinder head 142 side is tightly closed by the second cylinder head 142. The second cylinder second water passage 154 extends around the second cylinder chamber 144 so as to surround a part of the second cylinder chamber 144 when seen in the second direction. The second cylinder second water passage 154 is connected to the second cylinder first water passage 153 at one end when seen in the second direction, and is connected to a downstream connection part 213 of a water passage 210 of a motor case 200 described below at the other end when seen in the second direction. The second cylinder second water passage 154 is open in the inner circumferential surface of the second cylinder block main body 141b in an extension direction (a circumferential direction) of the second cylinder first water passage 153 when seen in the second direction. Thus, the cooling water discharged from the second cylinder second water passage 154 flows through the second cylinder first water passage 153 so as to circulate around the second cylinder chamber 144.

[0060] The second cylinder third water passage 155 is directly connected to the second cylinder first water passage 153. The second cylinder third water passage 155 is formed in the second cylinder block main body 141b. The second cylinder third water passage 155 is located on the side opposite the second cylinder chamber 144 with the second cylinder first water passage 153 interposed therebetween.

[0061] The second cylinder water passage 152 is located between the entire exhaust hole 142b and the second cylinder chamber 144. In this embodiment, the second cylinder first water passage 153 and the second cylinder second water passage 154 are located between the exhaust hole 142b and the second cylinder chamber 144. Additionally, the second cylinder water passage 152 is located between the entire intake hole 142a and the second cylinder chamber 144. In this embodiment, the second cylinder first water passage 153 and the second cylinder third water passage 155 are located between the intake hole 142a and the second cylinder chamber 144.

[0062] As shown in FIGS. 3 and 4, the second cylinder head 142 defines the second cylinder chamber 144 from the side opposite the second piston P2. The second cylinder head 142 is formed in a plate shape. The second cylinder head 142 is disposed to overlap the end surface of the second cylinder block 141. The intake hole 142a and the exhaust hole 142b that are in communication with the second cylinder chamber 144, an intake-side ventilation hole 142c that is in communication with the intake passage 150, and an exhaust-side ventilation hole 142d that is in communication with the exhaust passage 151 are formed in the second cylinder head 142. The intake hole 142a, the exhaust hole 142b, the intake-side ventilation hole 142c, and the exhaust-side ventilation hole 142d pass through the second cylinder head 142 in the second direction. At least one of the intake hole 142a and the exhaust hole 142b may be formed in plurality and arranged in a predetermined direction. At least one of the intake-side ventilation hole 142c and the exhaust-side ventilation hole 142d may be formed in plurality and arranged in a predetermined direction. For example, the intake-side ventilation holes 142c may be arranged in accordance with a shape of the opening of the intake passage 150.

[0063] The second cylinder head cover 143 forms an intake chamber 145 and an exhaust chamber 146 that are in communication with the second cylinder chamber 144 between the second cylinder head cover 143 and the second cylinder head 142. The intake chamber 145 and the exhaust chamber 146 are independent of each other. The intake chamber 145 is in communication with the second cylinder chamber 144 through the intake hole 142a, and is also in communication with the intake passage 150 through the intake-side ventilation hole 142c. The exhaust chamber 146 is in communication with the second cylinder chamber 144 through the exhaust hole 142b, and is also in communication with the exhaust passage 151 through the exhaust-side ventilation hole 142d.

[0064] The second cylinder head cover 143 has a wall surface 143a that defines each of the intake chamber 145 and the exhaust chamber 146. A plurality of recessed parts 143b are formed in the wall surface 143a. The recessed parts 143b are formed in the wall surface 143a at portions that define the intake chamber 145 and at portions that define the exhaust chamber 146. The recessed parts 143b are formed in the same manner as the recessed parts 123b formed in the first cylinder head cover 123.

[0065] As shown in FIG. 3, the second cylinder head 142 is provided with an intake-side valve member 147 and an exhaust-side valve member 148. The intake-side valve member 147 and the exhaust-side valve member 148 are each a check valve.

[0066] The intake-side valve member 147 allows a flow of gas from the intake chamber 145 to the second cylinder chamber 144 and blocks a flow of gas from the second cylinder chamber 144 to the intake chamber 145. The intake-side valve member 147 is formed in a thin plate shape and is disposed along a surface of the second cylinder head 142 on the second cylinder chamber 144 side. The intake-side valve member 147 is sandwiched between the second cylinder block 141 and the second cylinder head 142 and is held at a position along a surface of the second cylinder head 142 on the second cylinder chamber 144 side. The intake-side valve member 147 receives negative pressure in the second cylinder chamber 144 and deforms so as to be away from an opening edge of the intake hole 142a, thereby allowing communication between the intake chamber 145 and the second cylinder chamber 144.

[0067] The exhaust-side valve member 148 allows a flow of gas from the second cylinder chamber 144 to the exhaust chamber 146, and blocks a flow of gas from the exhaust chamber 146 to the second cylinder chamber 144. The exhaust-side valve member 148 is configured in the same manner as the exhaust-side valve member 128 provided in the first cylinder head 122.

[0068] As shown in FIGS. 3 and 4, the drive mechanism 180 includes the first piston P1 slidably fitted into the first cylinder chamber 124 of the first cylinder 120, and the second piston P2 slidably fitted into the second cylinder chamber 144 of the second cylinder 140. The first piston P1 moves linearly up and down in the first direction. The first piston P1 cooperates with the first cylinder 120 to form a first compression element that compresses gas using rotation of a crankshaft CR (a rotary shaft) (described below) as power. The second piston P2 moves linearly up and down in the second direction. The second piston P2 cooperates with the second cylinder 140 to form a second compression element that further compresses the compressed gas discharged from the first compression element using the rotation of the crankshaft CR as power. In this embodiment, the first piston P1 has a larger diameter than the second piston P2.

[0069] FIG. 10 is a side view of the drive mechanism according to the embodiment. FIG. 11 is a plan view of the drive mechanism according to the embodiment. FIG. 12 is a front view of the drive mechanism according to the embodiment.

[0070] As shown in FIGS. 10 to 12, the drive mechanism 180 includes, as components disposed inside the casing 100, the crankshaft CR that rotates about the axis O due to an output of the rotary drive source 3, a first counterweight W1 and a second counterweight W2 that rotate integrally with the crankshaft CR, and connecting rods CN1 and CN2 that are connected to the crankshaft CR.

[0071] The crankshaft CR has a pair of main shafts M1 and M2 having a first central axis C1, and a first crank pin CP1 and a second crank pin CP2 that are eccentric with respect to the first central axis C1. The first central axis C1 is coaxial with the axis O. The pair of main shafts M1 and M2 are spaced apart from each other in the axial direction by a predetermined distance. The pair of main shafts M1 and M2 are a first main shaft M1 and a second main shaft M2. The first main shaft M1 is connected to a front end of the first crank pin CP1 via the first counterweight W1. The second main shaft M2 is connected to a rear end of the second crank pin CP2 via the second counterweight W2. The first crank pin CP1 and the second crank pin CP2 are coupled to each other so as to be rotatable integrally with each other. The first crank pin CP1 and the second crank pin CP2 connect the pair of main shafts M1 and M2 to each other so that they cannot rotate relative to each other. In this embodiment, the main shaft M2 and the second counterweight W2 are integrally formed, and the main shaft M1 and the first counterweight W1 are integrally formed.

[0072] The first main shaft M1 is inserted into the recessed part 103a in the front cover 103 of the casing 100 and is rotatably supported by the front cover 103. The second main shaft M2 is inserted into the through hole 104a in the rear cover 104 and is rotatably supported by the rear cover 104. Thus, the crankshaft CR is supported at both sides of the casing 100. The second main shaft M2 protrudes from the casing 100 to the outside and constitutes an input / output shaft. An eccentric part E1 (an eccentric shaft) that is eccentric with respect to the first central axis C1 is provided at the second main shaft M2. The eccentric part E1 is located between the rear cover 104 and the second counterweight W2.

[0073] One end of the connecting rod CN1 is rotatably connected to the first piston P1 via a piston pin, and the other end of the connecting rod CN1 is rotatably connected to an outer circumferential surface of the first crank pin CP1. Thus, the first piston P1 is connected to the crankshaft CR via the connecting rod CN1. The first piston P1 moves linearly in the first direction as the first crank pin CP1 rotates. When the first piston P1 moves linearly, the first cylinder 120 functions as a guide body that guides the linear movement of the first piston P1 in the first direction.

[0074] One end of the connecting rod CN2 is rotatably connected to the second piston P2 via a piston pin, and the other end of the connecting rod CN2 is rotatably connected to an outer circumferential surface of the second crank pin CP2. Thus, the second piston P2 is connected to the crankshaft CR via the connecting rod CN2. The second piston P22 moves linearly in the second direction as the second crank pin CP2 rotates. When the second piston P2 moves linearly, the second cylinder 140 functions as a guide body that guides the linear movement of the second piston P2 in the second direction.

[0075] FIG. 13 is a cross-sectional view of the reciprocating compressor according to the embodiment, and is an enlarged view of a vertical cross section including the axis O.

[0076] As shown in FIG. 13, the reciprocating compressor 2 includes an oil pump 160 for supplying lubricating oil for lubricating drive parts of the reciprocating compressor 2 to each of the parts. The oil pump 160 is disposed inside the casing 100. The oil pump 160 includes a connecting ring 161, a pump cylinder 163, a hollow stem 166, a first valve part 168, a second valve part 169, and a filter 171.

[0077] The connecting ring 161 is formed in an annular shape. The connecting ring 161 is fitted onto the eccentric part E1 of the second main shaft M2 of the crankshaft CR so as to be rotatable relative to the eccentric part E1. A through hole 161a that is open to inner and outer circumferential surfaces is formed in the connecting ring 161. The through hole 161a extends downward from an opening in the inner circumferential surface of the connecting ring 161 toward an opening in the outer circumferential surface thereof. The opening of the through hole 161a in the inner circumferential surface of the connecting ring 161 is a discharge hole of the oil pump 160.

[0078] The pump cylinder 163 is disposed in the lower portion of the inner space of the casing 100 and is supported by the casing 100. The pump cylinder 163 is disposed with a gap in an up-down direction relative to the bottom plate 102 of the casing 100. The pump cylinder 163 includes a cylinder block 163a and a cylinder cover 163b. The cylinder block 163a has a thickness in the up-down direction. The cylinder cover 163b is disposed to overlap the cylinder block 163a from below. The cylinder cover 163b is fastened to the casing main body 101 together with the cylinder block 163a.

[0079] The pump cylinder 163 has a pump chamber 164 that extends in the up-down direction (a pump axial direction). The pump chamber 164 passes through the cylinder block 163a and the cylinder cover 163b in the up-down direction. The pump chamber 164 has a circular cross section. The pump chamber 164 has a first opening 164a that is open toward the connecting ring 161, and a second opening 164b that is provided separately from the first opening 164a. The first opening 164a is formed in the cylinder block 163a. The second opening 164b is formed in the cylinder cover 163b. The pump chamber 164 extends with a constant inner diameter from the first opening 164a to the second opening 164b in the cylinder block 163a.

[0080] The stem 166 extends in the up-down direction. The stem 166 has an upper end portion (a first end portion) inserted into the through hole 161a of the connecting ring 161 from the outer circumferential surface, and a lower end portion (a second end portion) inserted into the pump chamber 164 of the pump cylinder 163 through the first opening 164a. The stem 166 communicates between the through hole 161a and the pump chamber 164. The upper end portion of the stem 166 is fitted into the connecting ring 161 in a liquid-tight manner and fixed to the connecting ring 161. The lower end portion is in sliding contact with a wall surface of the pump chamber 164 in a liquid-tight manner, while being movable up and down within the pump chamber 164 and tiltable relative to the pump cylinder 163.

[0081] The first valve part 168 is disposed in the through hole 161a. The first valve part 168 closes an upper end opening of the stem 166 in an openable manner. The first valve part 168 allows a flow of lubricating oil from an inner space of the stem 166 to the through hole 161a, and blocks a flow of lubricating oil from the through hole 161a to the inner space of the stem 166. In this embodiment, the first valve part 168 is a ball valve.

[0082] The second valve part 169 is disposed in the pump chamber 164. The second valve part 169 closes the second opening 164b of the pump chamber 164 in an openable manner. The second valve part 169 allows a flow of liquid from a space outside the pump cylinder 163 to the pump chamber 164, and blocks a flow of liquid from the pump chamber 164 to the space outside the pump cylinder 163. The second valve part 169 is formed in a thin plate shape and is disposed along an upper surface of the cylinder cover 163b. The second valve part 169 is sandwiched between the cylinder block 163a and the cylinder cover 163b and is held at a position along the upper surface of the cylinder cover 163b. The second valve part 169 receives negative pressure in the pump chamber 164 and deforms so as to be away from an opening edge of the second opening 164b, thereby allowing communication between the pump chamber 164 and the outside of the pump cylinder 163 .

[0083] The filter 171 covers the second opening 164b from the outside of the pump cylinder 163. The filter 171 filters the lubricating oil that flows into the pump chamber 164 through the second opening 164b. The filter 171 includes an inner filter 171a and an outer filter 171b.

[0084] For example, the inner filter 171a is made of a metal. The inner filter 171a is formed in a cylindrical shape with a bottom and an upward opening, and is disposed in a state in which an opening edge abuts on a circumferential edge of the second opening 164b. The inner filter 171a has a flange that extends radially outward from the opening edge. The inner filter 171a is disposed in a state in which the flange fits along a lower surface of the cylinder cover 163b. The flange is sandwiched around its entire circumference between the cylinder cover 163b and a washer fastened to the cylinder cover 163b so as to fit along the lower surface of the cylinder cover 163b. Thus, the inner filter 171a is disposed not to be displaceable relative to the pump cylinder 163.

[0085] For example, the outer filter 171b is made of sponge. The outer filter 171b is disposed between the pump cylinder 163 and the bottom plate 102 of the casing 100. The outer filter 171b is formed in a cylindrical shape with a thickness in a radial direction and is disposed to surround the inner filter 171a. The outer filter 171b is disposed so that its lower end opening is located inside a recessed part formed in an upper surface of the bottom plate 102. Thus, the oil pump 160 suctions up the lubricating oil accumulated inside the bottom plate 102 through an inner space of the outer filter 171b.(Rotary Drive Source)

[0086] As shown in FIG. 3, the rotary drive source 3 is an electric motor. The rotary drive source 3 includes the motor case 200 (a first case, a case), a motor shaft 220, a rotor 230, and a stator 240.

[0087] The motor case 200 is fastened to the casing 100 of the reciprocating compressor 2 from the rear. The motor case 200 has an inner space that passes through the inside thereof along the axis O. The motor case 200 has a hollow cylindrical shape. The motor case 200 includes an outer case 201 and an inner case 202.

[0088] The outer case 201 is formed in a cylindrical shape with a bottom that is open toward the reciprocating compressor 2. An outer circumferential surface of the outer case 201 forms an outer circumferential surface of the motor case 200. The outer case 201 has a shaft hole that passes through a bottom wall thereof. The shaft hole extends coaxially with the axis O. The shaft hole is closed by a cap.

[0089] The inner case 202 is formed in a cylindrical shape with a bottom that opens towards the side opposite to the reciprocating compressor 2. The inner case 202 is fitted inside the outer case 201 and is surrounded by the outer case 201. The inner case 202 has a shaft hole that passes through a bottom wall thereof. The shaft hole extends coaxially with the axis O. The second main shaft M2 that protrudes from the casing 100 of the reciprocating compressor 2 is inserted into the shaft hole.

[0090] The inner case 202 has a flange 202a that protrudes radially outward from an end edge of its circumferential wall on the reciprocating compressor 2 side. The flange 202a abuts against an opening edge of the outer case 201. The flange 202a is fastened to the outer case 201. Furthermore, the flange 202a is fastened to the casing main body 101 with the bottom wall of the inner case 202 covering the rear cover 104 of the casing 100 of the reciprocating compressor 2. Thus, the motor case 200 is coupled to the casing 100 of the reciprocating compressor 2.

[0091] The water passage 210 through which cooling water flows is formed in the motor case 200. The water passage 210 includes a spiral part 211 formed between the outer case 201 and the inner case 202, and an upstream connection part 212 and a downstream connection part 213 connected to the spiral part 211.

[0092] The spiral part 211 is a gap between an inner circumferential surface of the outer case 201 and an outer circumferential surface of the inner case 202. On an outer circumferential surface of the inner case 202, a partition wall 202b extends spirally in the axial direction around the axis O (refer to FIG. 14). The gap between the inner circumferential surface of the outer case 201 and the outer circumferential surface of the inner case 202 extends spirally between the partition walls 202b adjacent to each other in the axial direction.

[0093] The upstream connection part 212 is provided on the outer case 201. The upstream connection part 212 passes through the outer case 201. The upstream connection part 212 is open to the inner circumferential surface of the outer case 201 and is in communication with the spiral part 211. The upstream connection part 212 is in communication with a portion of the spiral part 211 on one end side that is closer to the rear than a middle portion in the extension direction of the spiral part 211. The upstream connection part 212 is open to the control device 4 side (the rear) at an end surface of the outer case 201 in the axial direction.

[0094] The downstream connection part 213 is provided on the inner case 202. The downstream connection part 213 passes through the inner case 202. The downstream connection part 213 is open to the outer circumferential surface of the inner case 202 and is in communication with the spiral part 211. The downstream connection part 213 is in communication with a portion of the spiral part 211 on the other end side that is closer to the front than the middle portion in the extension direction of the spiral part 211. The downstream connection part 213 is open on the reciprocating compressor 2 side (the front) at the end surface of the outer case 201 in the axial direction and is in communication with the second cylinder second water passage 154 of the reciprocating compressor 2.

[0095] The motor shaft 220 is disposed in the inner space of the motor case 200. The motor shaft 220 is rotatably supported by the bottom wall of the outer case 201 and the bottom wall of the inner case 202 via bearings. The motor shaft 220 is formed to be hollow. The second main shaft M2 of the reciprocating compressor 2 is inserted into an end portion of the motor shaft 220 on the reciprocating compressor 2 side. The motor shaft 220 is coupled to the second main shaft M2 at its inner side so as not to rotate relative to the second main shaft M2.

[0096] The rotor 230 is disposed in the inner space of the motor case 200. The rotor 230 is coupled to the motor shaft 220 so as not to rotate relative to the motor shaft 220.

[0097] The stator 240 is disposed in the inner space of the motor case 200. The stator 240 is held on the inner circumferential surface of the inner case 202. The stator 240 is formed in a cylindrical shape that is coaxial with the motor shaft 220. The stator 240 is disposed to surround the rotor 230.(Control Device 4)

[0098] The control device 4 includes a control unit 300 (a control part) that controls the rotary drive source 3 and a housing 310 (a second case) that accommodates the control unit 300. The control unit 300 includes a substrate and various electronic components mounted on the substrate. The control unit 300 is disposed with its front and back surfaces of the substrate facing in the axial direction.

[0099] The housing 310 is coupled to the motor case 200 in an overlapping manner. The housing 310 is fastened to the motor case 200 from the rear. The housing 310 has an inner space in which the control unit 300 is disposed. The housing 310 includes a housing main body 311 that has a box shape and is open on the side opposite the rotary drive source 3, and a lid body 312 that closes an opening of the housing main body 311. The housing main body 311 is fastened to the outer case 201 of the motor case 200 in a state in which it covers the entire rear end surface of the motor case 200. The lid body 312 is formed in a flat plate shape. The lid body 312 is fastened to the motor case 200 with its front and back surfaces facing in the axial direction.

[0100] The housing 310 cooperates with the motor case 200 to form a cooling water flow space 320, through which the cooling water flows, between the housing 310 and the motor case 200. The motor case 200 has a rear surface 200a that faces the control device 4 (the rear) in the axial direction as a first surface that defines the cooling water flow space 320. The housing 310 has a front surface 310a that faces the rotary drive source 3 (the front) in the axial direction as a second surface that defines the cooling water flow space 320.

[0101] FIG. 15 is a view showing the rear surface of the motor case.

[0102] As shown in FIG. 15, the rear surface 200a of the motor case 200 is provided on the bottom wall of the outer case 201. The rear surface 200a includes a first recessed part 200b recessed in a direction (toward the front) away from the front surface 310a of the motor case 200, and a second recessed part 200c recessed in a direction away from the front surface 310a of the motor case 200. The first recessed part 200b and the second recessed part 200c are provided independently of each other and adjacent to each other in the circumferential direction about the axis O. The first recessed part 200b and the second recessed part 200c are located to be biased in the circumferential direction. Thus, the rear surface 200a has a fan-shaped flat part 200d in which the first recessed part 200b and the second recessed part 200c are not formed.

[0103] FIG. 16 is a view showing the front surface of the housing.

[0104] As shown in FIG. 16, the front surface 310a of the housing 310 has a plurality of groove parts 310b that are recessed in a direction (toward the rear) away from the rear surface 200a of the motor case 200. The plurality of groove parts 310b are formed in the housing main body 311. The plurality of groove parts 310b are formed at positions that overlap a heat generation element in the control unit 300 when seen in the axial direction. The plurality of groove parts 310b are parallel to each other and extend in the circumferential direction about the axis O. Each of the groove parts 310b extends from a position overlapping the first recessed part 200b, through a position overlapping the flat part 200d, to a position overlapping the second recessed part 200c when seen in the axial direction (refer to also FIGS. 12 and 14).

[0105] FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. 3.

[0106] As shown in FIGS. 15 and 17, the cooling water flow space 320 includes an inflow part 321, an outflow part 322 that is provided independently of the inflow part 321, and a communication part 323 that causes the inflow part 321 and the outflow part 322 to be in communication with each other. The inflow part 321 is defined by the first recessed part 200b. The inflow part 321 is in communication with an inflow passage 324 through which the cooling water flows in. The inflow passage 324 passes through the housing main body 311 and is connected to a cooling water pump (not shown) via an inflow pipe 326 (refer to FIG. 16) mounted in the housing main body 311. The outflow part 322 is defined by the second recessed part 200c. The outflow part 322 is in communication with an outflow passage 325 through which the cooling water flows out. The outflow passage 325 passes through the housing main body 311 and causes the outflow part 322 and the upstream connection part 212 of the water passage 210 in the motor case 200 to be in communication with each other. The communication part 323 is formed by the plurality of groove parts 310b. Cooling water flows through the communication part 323 from the inflow part 321 toward the outflow part 322.(Operation of the Reciprocating Compressor)

[0107] As shown in FIG. 10, during an operation of the reciprocating compressor 2, a rotational force is input to the second main shaft M2, and the crankshaft CR rotates around the first central axis C1. Accordingly, the first crank pin CP1 and the second crank pin CP2 revolve around the first central axis C1.

[0108] Thus, the first piston P1 connected to the first crank pin CP1 via the connecting rod CN1 moves linearly in the first direction. The linear movement of the first piston P1 is guided by the first cylinder 120. As the first piston P1 moves up and down within the first cylinder 120, a gas within the first cylinder 120 is compressed and pressurized, and is supplied to the outside through the exhaust hole 122b.

[0109] The second piston P2 connected to the second crank pin CP2 via the connecting rod CN2 moves linearly in the second direction. The linear movement of the second piston P2 is guided by the second cylinder 140. As the second piston P2 moves up and down within the second cylinder 140, a gas within the second cylinder 140 is compressed and pressurized, and is supplied to the outside through the exhaust hole 142b.

[0110] When the first piston P1 and the second piston P2 have different diameters, a so-called two-stage compression compressor may be realized. That is, a first stage of compression is performed using a large-diameter first piston P1 to pressurize a gas to approximately a desired pressure, and then a second stage of compression is performed using a small-diameter second piston P2 to adjust a pressurized state.

[0111] When the second main shaft M2 rotates around the first central axis C1, the connecting ring 161 of the oil pump 160 swings around the first central axis C1. When the connecting ring 161 swings, the stem 166 reciprocates in the up-down direction while tilting left and right with a contact portion with the pump cylinder 163 as a center. When the stem 166 moves up, a negative pressure is generated in the pump chamber 164, and the lubricating oil flows into the pump chamber 164 through the second opening 164b. When the stem 166 moves down, an internal pressure of the pump chamber 164 increases, and thus the lubricating oil inside the stem 166 that is in communication with the pump chamber 164 opens the first valve part 168 at the upper end opening of the stem 166 and flows into the through hole 161a of the connecting ring 161. Thus, the oil pump 160 discharges the lubricating oil from an opening of the through hole 161a in the inner circumferential surface of the connecting ring 161 and supplies the oil to a desired location.(Cooling Structure of Compression Device)

[0112] The compression device 1 is cooled by cooling water pumped by a cooling water pump (not shown). The cooling water pumped by the cooling water pump is introduced into the cooling water flow space 320 through the inflow pipe 326 and the inflow passage 324 of the control device 4. The cooling water introduced into the cooling water flow space 320 flows through the inflow part 321, the communication part 323, and the outflow part 322 in this order. The cooling water mainly cools a heat generation part of the control unit 300 while flowing through the communication part 323 in the cooling water flow space 320. The cooling water in the outflow part 322 is discharged from the control device 4 through the outflow passage 325 toward the rotary drive source 3.

[0113] The cooling water discharged from the control device 4 is introduced into the water passage 210 of the rotary drive source 3. The cooling water introduced into the water passage 210 flows through the upstream connection part 212, the spiral part 211, and the downstream connection part 213 in this order. The cooling water that has flowed through the downstream connection part 213 is discharged from the rotary drive source 3 toward the reciprocating compressor 2.

[0114] The cooling water discharged from the rotary drive source 3 is introduced into the second cylinder water passage 152 of the second cylinder 140 of the reciprocating compressor 2. The cooling water introduced into the second cylinder water passage 152 flows through the second cylinder second water passage 154, the second cylinder first water passage 153, and the second cylinder third water passage 155 in this order. The cooling water that has flowed through the second cylinder third water passage 155 flows toward the first cylinder water passage 131 of the first cylinder 120.

[0115] The cooling water that has flowed into the first cylinder water passage 131 flows through the first cylinder second water passage 133 and the first cylinder first water passage 132 in this order. The cooling water that has flowed through the first cylinder first water passage 132 is discharged from the reciprocating compressor 2 through the discharge pipe 134. The cooling water discharged from the reciprocating compressor 2 is cooled through a heat exchanger or the like, and is again pumped by the cooling water pump toward the control device 4.(Start-up Control of Reciprocating Compressor)

[0116] The control unit 300 controls the rotary drive source 3 to start the reciprocating compressor 2. When starting the reciprocating compressor 2 fails as a result of controlling the rotary drive source 3 to rotate the crankshaft CR, the control unit 300 performs a predetermined startup control. In this embodiment, the reciprocating compressor 2 fails to start when the crankshaft CR, which is rotated in the first rotation direction by the output of the rotary drive source 3, does not have enough run-up, and therefore does not pass through a phase (a rotation angle) of the crankshaft CR at which torque acting on the crankshaft CR is maximized. For example, the phase of the crankshaft CR at which the torque acting on the crankshaft CR is maximized is determined by at least one of a positional relationship between the first piston P1 and the first cylinder 120 and a positional relationship between the second piston P2 and the second cylinder 140 in the drive mechanism 180.

[0117] In this embodiment, due to the positional relationship between the first piston P1 and the first cylinder 120, the torque acting on the crankshaft CR reaches a maximum every time the crankshaft CR rotates by 180 degrees. Furthermore, due to the positional relationship between the second piston P2 and the second cylinder 140, the torque acting on the crankshaft CR reaches a maximum every time the crankshaft CR rotates 180 degrees. Thus, in this embodiment, the torque acting on the crankshaft CR reaches a maximum four times per rotation of the crankshaft CR.

[0118] As the predetermined start-up control, the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR again in a first rotation direction. In addition, as the predetermined start-up control, the control unit 300 may control the rotary drive source 3 to rotate the crankshaft CR in a second rotation direction (a reverse direction) opposite to the first rotation direction and then rotate the crankshaft CR again in the first rotation direction. In this case, the control unit 300 may detect a load on the crankshaft CR and determine whether or not to rotate the crankshaft CR in the reverse direction based on a magnitude of the load.

[0119] As described above, the compression device 1 of this embodiment includes the motor case 200 that accommodates the rotary drive source 3, and the housing 310 that accommodates the control unit 300 and is coupled to the motor case 200 to overlap the motor case 200 in a predetermined direction. The motor case 200 and the housing 310 define the cooling water flow space 320 therebetween, through which the cooling water flows. The motor case 200 has the rear surface 200a that defines the cooling water flow space 320. The housing 310 has the front surface 310a that defines the cooling water flow space 320. The cooling water flow space 320 has the inflow part 321, the outflow part 322 that is provided independently of the inflow part 321, and the communication part 323 that causes the inflow part 321 and the outflow part 322 to be in communication with each other and through which the cooling water flows from the inflow part 321 to the outflow part 322. The rear surface 200a has the first recessed part 200b that is recessed in the direction away from the front surface 310a and defines the inflow part 321, and the second recessed part 200c that is recessed in the direction away from the front surface 310a and defines the outflow part 322. The front surface 310a is recessed in the direction away from the rear surface 200a and has the plurality of groove parts 310b that extend from the position overlapping the first recessed part 200b to the position overlapping the second recessed part 200c when seen in a predetermined direction.

[0120] With this configuration, since the plurality of groove parts 310b through which the cooling water flows are formed in the housing 310 that accommodates the control unit 300, a surface area of the housing 310 that comes into contact with the cooling water is ensured, and the control unit 300 can be cooled efficiently.

[0121] The compression device 1 includes the motor case 200 that accommodates the rotary drive source 3. The motor case 200 includes the inner case 202 that holds the stator 240, and the outer case 201 that surrounds the inner case 202. The inner case 202 and the outer case 201 define the water passage 210 between them through which the cooling water flows. The water passage 210 extends spirally around the axis O of the rotary drive source 3.

[0122] With this configuration, the cooling water can be circulated around the entire circumference of the motor case 200 that accommodates the rotary drive source 3. Therefore, the rotary drive source 3 can be efficiently cooled.

[0123] The compression device 1 includes the first compression element that compresses gas using the rotation of the crankshaft CR as power, and the second compression element that further compresses the compressed gas discharged from the first compression element using the rotation of the crankshaft CR as power. The first compression element includes the first piston P1 connected to the crankshaft CR, and the first cylinder block 121 having the first cylinder chamber 124 into which the first piston P1 is slidably fitted. The second compression element includes the second piston P2 connected to the crankshaft CR, and the second cylinder block 141 having the second cylinder chamber 144 into which the second piston P2 is slidably fitted. The first cylinder block 121 has the first cylinder water passage 131 through which the cooling water flows. The second cylinder block 141 has the second cylinder water passage 152 through which the cooling water flowing into the first cylinder water passage 131 flows.

[0124] With this configuration, in the first cylinder block 121 and the second cylinder block 141, the second cylinder block 141 which becomes hotter due to heat exchange with the compressed gas can be cooled with the low-temperature cooling water in a state before heat exchange with the first cylinder block 121. Therefore, the first compression element and the second compression element can be cooled efficiently.

[0125] The first cylinder block 121 has the exhaust passage 130 through which the compressed gas discharged from the first compression element passes, and the first cylinder water passage 131 formed between the exhaust passage 130 and the first cylinder chamber 124 and through which the cooling water flows. The second cylinder block 141 has the intake passage 150 and the exhaust passage 151 through which the compressed gas discharged from the first compression element passes, and the second cylinder water passage 152 formed between each of the intake passage 150 and the exhaust passage 151 and the second cylinder chamber 144 and through which the cooling water flows.

[0126] With this configuration, since the first cylinder water passage 131 is formed between the wall surface of the first cylinder chamber 124 which performs heat exchange with the compressed air, and the wall surface of the exhaust passage 130, the wall part of the first cylinder chamber 124 and the wall part of the exhaust passage 130 can be efficiently cooled. In addition, since the second cylinder water passage 152 is formed between the wall surface of the second cylinder chamber 144 which performs heat exchange with the compressed air, and the wall surfaces of the intake passage 150 and the exhaust passage 151, the wall parts of the second cylinder chamber 144, the intake passage 150, and the exhaust passage 151 can be efficiently cooled.

[0127] The first compression element has the first cylinder head cover 123 that forms the intake chamber 125 and the exhaust chamber 126 that are in communication with the first cylinder chamber 124 between the first cylinder head 122 and the first cylinder head cover 123. The first cylinder head cover 123 has the wall surface 123a that defines the intake chamber 125 and the exhaust chamber 126 and has the plurality of recessed parts 123b formed therein.

[0128] With this configuration, the plurality of recessed parts 123b can reflect and attenuate vibrations of the air in the intake chamber 125 and the exhaust chamber 126 in a complex manner. The same applies to the recessed parts 143b of the second cylinder head cover 143 of the second compression element. Therefore, the sound emitted by the compression element is attenuated, and the compression device 1 can be provided with reduced noise generation.

[0129] The compression device 1 includes the first cylinder 120 having the first cylinder chamber 124 and the intake chamber 125 that is in communication with the external air, the casing 100 having the crank chamber that accommodates the crankshaft CR, and the communication pipe 136 that causes the intake chamber 125 and the crank chamber to be in communication with each other.

[0130] With this configuration, since the crank chamber is in communication with the intake chamber 125, pressure fluctuations in the crank chamber caused by the displacement of the pistons P1 and P2 can be alleviated. Thus, it is possible to prevent gas and lubricating oil from leaking from the crank chamber due to the pressure fluctuations in the crank chamber. Further, it is possible to curb problems with the supply of the lubricating oil from occurring due to fluctuations in supply pressure of the lubricating oil in the crank chamber caused by the pressure fluctuations in the crank chamber. Furthermore, it is possible to curb fluctuations in the load applied to the drive parts such as the pistons P1 and P2 due to the pressure fluctuations in the crank chamber.

[0131] FIGS. 18 and 19 are graphs showing a relationship between the rotation angle of the crankshaft and the torque acting on the crankshaft in the reciprocating compressor of the embodiment. In FIGS. 18 and 19, a horizontal axis represents the rotation angle of the crankshaft CR, and a vertical axis represents the torque acting on the crankshaft CR.

[0132] As shown in FIG. 18, in the case of the start-up of the reciprocating compressor 2, when starting torque input to the crankshaft CR is insufficient as shown by (1) in the drawing and the reciprocating compressor 2 fails to start, the crankshaft CR receives a reaction force and rotates in the reverse direction to pass through a start position. In this embodiment, when the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR and fails to start the reciprocating compressor 2, the control unit 300 controls the rotary drive source 3 again to rotate the crankshaft CR.

[0133] With this configuration, by rotating the crankshaft CR again, it is possible to ensure a larger run-up angle of the crankshaft CR than at the time of the previous start, and thus it is possible to improve a probability of successful start of the reciprocating compressor 2. In the example shown in FIG. 18, a second starting operation shown in (2) in the drawing is able to secure a larger run-up angle of the crankshaft CR than a first starting operation shown in (1) in the drawing, but fails to start the reciprocating compressor 2. Furthermore, in a third starting operation shown in (3) in the drawing, the run-up angle of the crankshaft CR can be secured more than in the second starting operation, and the reciprocating compressor 2 is successfully started. Therefore, the reciprocating compressor 2 can be reliably started.

[0134] When the control unit 300 controls the rotary drive source 3 to rotate the crankshaft CR in the first rotation direction and fails to start the reciprocating compressor 2, the control unit 300 may control the rotary drive source 3 to rotate the crankshaft CR in the second rotation direction and then rotate it in the first rotation direction again.

[0135] With this configuration, as shown in FIG. 19, when the starting torque input to the crankshaft CR in the first rotation direction is insufficient and the reciprocating compressor 2 fails to start at (1) in the drawing, the crankshaft CR can be rotated in the reverse direction to pass through the starting position by rotating the crankshaft CR in the second rotation direction at (2) in the drawing. Therefore, by rotating the crankshaft CR again in the first rotation direction at (3) in the drawing, it is possible to ensure a larger run-up angle of the crankshaft CR than at the previous start, thereby improving the probability of successful start of the reciprocating compressor 2. Therefore, the reciprocating compressor 2 can be started reliably.

[0136] The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications are possible within the technical scope of the present invention.

[0137] For example, in the above embodiment, the reciprocating compressor 2 is configured to generate compressed air, but the compressed gas generated by the reciprocating compressor is not limited to air. For example, the reciprocating compressor may be configured to compress a refrigerant.

[0138] Furthermore, although the reciprocating compressor 2 in the above embodiment is a two-cylinder and two-stage reciprocating compressor, the compression device to which the present invention is applied is not limited to one equipped with the two-stage reciprocating compressor. That is, the present invention may be applied to a single-cylinder reciprocating compressor, or to a multi-stage reciprocating compressor having three or more cylinders.

[0139] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the gist of the present invention.

[0140] Among the embodiments disclosed in this specification, those that are configured of multiple members may be integrated into one member, and conversely, those that are configured of a single member may be separated into multiple members. Regardless of whether they are integrated or not, they may be configured to achieve the object of the invention.INDUSTRIAL APPLICABILITY

[0141] According to the present invention, it is possible to provide a compression device and an oil pump having excellent cooling efficiency.REFERENCE SIGNS LIST

[0142] 1 Compression device 2 Reciprocating compressor 3 Rotary drive source 100 Casing (crankcase) 121 First cylinder block 123 First cylinder head cover (cylinder head cover) 123a Wall surface 123b Recessed part 124 First cylinder chamber (cylinder chamber) 125 Intake chamber (air chamber) 131 First cylinder water passage 141 Second cylinder block 143 Second cylinder head cover (cylinder head cover) 143a Wall surface 143b Recessed part 144 Second cylinder chamber (cylinder chamber) 145 Intake chamber (air chamber) 146 Exhaust chamber (air chamber) 152 Second cylinder water passage 160 Oil pump 161 Connecting ring 161a Through hole 163 Pump cylinder 164 Pump chamber 164a First opening 164b Second opening 166 Stem 168 First valve part 169 Second valve part 171 Filter 200b First recessed part 200c Second recessed part 201 Outer case 202 Inner case 210 Water passage 230 Rotor 240 Stator 300 Control unit (control part) 310b Groove part 320 Cooling water flow space 321 Inflow part 322 Outflow part 323 Communication part C1 First central axis CR Crankshaft (rotary shaft) E1 Eccentric part (eccentric shaft) M1 First main shaft (main shaft) M2 Second main shaft (main shaft) O Axis (rotation axis) P1 First piston (piston) P2 Second piston (piston)

Examples

Embodiment Construction

[0027]Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of the components may be omitted.

[0028]FIGS. 1 and 2 are perspective views showing an exterior of a compression device according to an embodiment.

[0029]As shown in FIGS. 1 to 3, the compression device 1 includes a reciprocating compressor 2, a rotary drive source 3, and a control device 4. The rotary drive source 3 outputs a rotary drive force about an axis O to drive the reciprocating compressor 2. Hereinafter, a direction in which the axis O extends will be referred to as an axial direction. In this embodiment, the axial direction is parallel to a horizontal direction. The reciprocating compressor 2, the rotary drive source 3, and the control device 4 are arranged in this order in the axial direction. In the axial direction, a d...

Claims

1. A compression device comprising: a rotary drive source; a first case configured to accommodate the rotary drive source; a rotary shaft configured to rotate due to an output of the rotary drive source; a compression element configured to compress gas using rotation of the rotary shaft as power; a control unit configured to control the rotary drive source; and a second case configured to accommodate the control unit and which is coupled to the first case to overlap the first case in a predetermined direction, wherein the first case and the second case define a cooling water flow space therebetween through which cooling water flows, the first case has a first surface that defines the cooling water flow space, the second case has a second surface that defines the cooling water flow space, the cooling water flow space has an inflow part, an outflow part provided independently of the inflow part, and a communication part that causes the inflow part and the outflow part to be in communication with each other and allows the cooling water to flow from the inflow part to the outflow part, the first surface has a first recessed part that is recessed in a direction away from the second surface and defines the inflow part, and a second recessed part that is recessed in a direction away from the second surface and defines the outflow part, and the second surface has a plurality of groove parts that are recessed in a direction away from the first surface and extend from a position overlapping the first recessed part to a position overlapping the second recessed part when seen in the predetermined direction.

2. A compression device comprising: a rotary drive source having a rotor and a stator disposed around the rotor; a case configured to accommodate the rotary drive source; a rotary shaft configured to rotate due to an output of the rotary drive source; and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the case includes an inner case that holds the stator, and an outer case that surrounds the inner case, the inner case and the outer case form a water passage therebetween through which cooling water flows, and the water passage extends spirally around a rotation axis of the rotary drive source.

3. A compression device comprising: a rotary drive source; a rotary shaft configured to rotate due to an output of the rotary drive source; a first compression element configured to compress gas using rotation of the rotary shaft as power; and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein the first compression element includes a first piston connected to the rotary shaft, and a first cylinder block having a first cylinder chamber into which the first piston is slidably fitted, the second compression element includes a second piston connected to the rotary shaft, and a second cylinder block having a second cylinder chamber into which the second piston is slidably fitted, the first cylinder block has a first cylinder water passage through which cooling water flows, and the second cylinder block has a second cylinder water passage through which the cooling water flowing into the first cylinder water passage flows.

4. A compression device comprising: a rotary drive source; a rotary shaft configured to rotate due to an output of the rotary drive source; a first compression element configured to compress gas using rotation of the rotary shaft as power; and a second compression element configured to further compress the compressed gas discharged from the first compression element using the rotation of the rotary shaft as power, wherein at least one of the first compression element and the second compression element has a piston connected to the rotary shaft, and a cylinder block having a cylinder chamber into which the piston is slidably fitted, and the cylinder block has a ventilation passage through which the compressed gas discharged from the first compression element passes, and a water passage formed between the ventilation passage through and the cylinder chamber and through which cooling water flows.

5. A compression device comprising: a rotary drive source; a rotary shaft configured to rotate due to an output of the rotary drive source; and a compression element configured to compress gas using rotation of the rotary shaft as power, wherein the compression element includes a piston connected to the rotary shaft, a cylinder block having a cylinder chamber into which the piston is slidably fitted, a cylinder head that is fixed to the cylinder block and defines the cylinder chamber on the side opposite the piston, and a cylinder head cover that covers the cylinder head from the side opposite the cylinder block and forms an air chamber, which is in communication with the cylinder chamber, between the cylinder head and the cylinder head cover, and the cylinder head cover has a wall surface that defines the air chamber and has a plurality of recessed parts formed therein.

6. A compression device comprising: a rotary drive source; a crankshaft configured to rotate due to an output of the rotary drive source; a piston connected to the crankshaft; a cylinder having a cylinder chamber into which the piston is slidably fitted, and an intake chamber that is in communication with the cylinder chamber and external air; a crankcase having a crank chamber that accommodates the crankshaft; and a connection part configured to cause the intake chamber and the crank chamber to be in communication with each other.

7. An oil pump comprising: a connecting ring fitted onto an eccentric shaft to be rotatable relative to the eccentric shaft, having an inner circumferential surface and an outer circumferential surface, and having a through hole that is open to the inner circumferential surface and the outer circumferential surface; a pump cylinder having a pump chamber configured to extend in a pump axial direction perpendicular to an axial direction of the eccentric shaft and having a first opening that is open toward the connecting ring and a second opening that is provided separately from the first opening; a hollow stem having a first end portion inserted into the through hole from the outer circumferential surface and a second end portion inserted into the pump chamber through the first opening, the second end portion being in sliding contact with a wall surface of the pump chamber in a liquid-tight manner while being movable in the pump axial direction within the pump chamber and tiltable relative to the pump cylinder, thereby causing the through hole and the pump chamber to be in communication with each other; a first valve part configured to allow a flow of liquid from an inner space of the stem to the through hole and block the flow of liquid from the through hole to the inner space of the stem; a second valve part configured to close the second opening of the pump chamber in an openable manner, allow a flow of liquid from an outer space of the pump cylinder to the pump chamber, and block the flow of liquid from the pump chamber to the outer space of the pump cylinder; and a filter configured to cover the second opening from the outside of the pump cylinder.

8. A compression device comprising: a rotary drive source; a reciprocating compressor operated by an output of the rotary drive source; and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes: a casing; a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source; a piston connected to the crank pin; and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, wherein when the control unit controls the rotary drive source to rotate the crankshaft but fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft.

9. A compression device comprising: a rotary drive source; a reciprocating compressor operated by an output of the rotary drive source; and a control unit configured to control the rotary drive source, wherein the reciprocating compressor includes: a housing; a crankshaft including a main shaft having a first central axis and a crank pin located eccentrically with respect to the main shaft, both end portions of the main shaft in an axial direction being supported by the casing to be rotatable around the first central axis, and the crankshaft rotating around the first central axis by the output of the rotary drive source; a piston connected to the crank pin; and a guide body provided not to be displaceable relative to the casing and configured to guide linear movement of the piston, wherein when the control unit controls the rotary drive source to rotate the crankshaft in a first rotation direction and fails to start the reciprocating compressor, the control unit controls the rotary drive source again to rotate the crankshaft in a second rotation direction opposite to the first rotation direction and then rotate the crankshaft in the first rotation direction.

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