Two-stage reciprocating compressor

Abstract

To provide a two-stage reciprocating compressor with improved cooling efficiency. [Solution] The reciprocating compressor comprises: an output shaft that extends axially and outputs rotation from the rotational drive source housed in the internal space of the motor case, with one end protruding from the end face of the motor case; a crankcase having an internal space partitioned from the internal space of the motor case by a partition wall; a crankshaft positioned in the internal space of the crankcase so as to penetrate the partition wall and extend to the internal space of the motor case, to which rotational driving force from the output shaft is transmitted; a low-pressure compression element that compresses air by the rotational motion of the crankshaft; an intercooler that cools the compressed air discharged from the low-pressure compression element; a high-pressure compression element that further compresses the compressed air cooled by the intercooler by the rotational motion of the crankshaft; and a blower fan connected to the output shaft and positioned axially between the end face of the motor case and the intercooler.

Description

Technical Field

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[0001] The present invention relates to a two-stage reciprocating compressor.

Background Art

[0002] In order to obtain high-pressure compressed air, a two-stage reciprocating compressor that compresses air in two stages is known. The two-stage reciprocating compressor has a low-pressure side cylinder and a high-pressure side cylinder. In a two-stage reciprocating compressor, the air compressed in the low-pressure side cylinder is sent into the high-pressure side cylinder and further compressed in the high-pressure side cylinder. The compressed air compressed in the high-pressure side cylinder is supplied to a pneumatic machine through a discharge port. When the two-stage reciprocating compressor is mounted on a commercial vehicle, the compressed air discharged from the high-pressure side cylinder head is supplied to, for example, brakes or an air suspension. A conventional two-stage reciprocating compressor is disclosed in Japanese Patent Application Laid-Open No. 2013-040586.

[0003] Since compression heat is generated in the process of compressing air, the temperatures of the cylinder and the piston rise during the operation of the reciprocating compressor. In addition, since the electric motor is driven by the rated current, Joule heat is generated by this rated current. As a result, the temperature of the electric motor also rises. Therefore, a cooling fan is often provided in a conventional reciprocating compressor. A two-stage reciprocating compressor provided with a cooling fan is disclosed in Japanese Patent Application Laid-Open No. 9-264253 and Japanese Patent Application Laid-Open No. 2016-070233. <0000=13>

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Further improvements in cooling efficiency are required for two-stage reciprocating compressors equipped with cooling fans.

[0006] One of the purposes of this disclosure is to improve the cooling effect in a two-stage reciprocating compressor. Other purposes of this disclosure will be understood by referring to the entire description of this specification. [Means for solving the problem]

[0007] A two-stage reciprocating compressor according to one aspect of the present invention comprises: a rotary drive source housed in a case; an axially extending output shaft that outputs rotation from the rotary drive source and has one end protruding from the end face of the case; a low-pressure compression element that compresses air using the rotational drive force from the output shaft as a power source; an intercooler that cools the compressed air discharged from the low-pressure compression element; a high-pressure compression element that further compresses the compressed air cooled by the intercooler using the rotational drive force from the motor output shaft as a power source; and a blower fan connected to the output shaft and positioned in the axial direction between the end face of the housing and the intercooler.

[0008] In one embodiment of the present invention, the case has a plurality of ribs extending in the axial direction on its outer surface.

[0009] In one embodiment of the present invention, the case has a plurality of other ribs extending in a direction perpendicular to the axial direction.

[0010] A two-stage reciprocating compressor according to one aspect of the present invention further comprises a silencer that supplies the air to the low-pressure compression element.

[0011] A two-stage reciprocating compressor according to one aspect of the present invention further comprises a case, a low-pressure compression element, an intercooler, a high-pressure compression element, and a fan, with at least a portion of these covered.

[0012] One aspect of the present invention relates to an automobile, which is equipped with the above-described two-stage reciprocating compressor. [Effects of the Invention]

[0013] According to embodiments of the present invention, the cooling effect in a two-stage reciprocating compressor can be improved. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic perspective view showing a two-stage reciprocating compressor according to one embodiment. [Figure 2] Figure 1 is a schematic side view of the two-stage reciprocating compressor. [Figure 3] Figure 2 is a schematic cross-sectional view showing a two-stage reciprocating compressor cut along line AA. [Figure 4] This is a schematic perspective view showing a two-stage reciprocating compressor according to another embodiment. [Figure 5] This is a schematic cross-sectional view of a two-stage reciprocating compressor according to another embodiment. [Modes for carrying out the invention]

[0015] A two-stage reciprocating compressor 1 according to various embodiments of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a schematic perspective view of a two-stage reciprocating compressor 1 according to one embodiment of the present invention, Figure 2 is a schematic side view of the two-stage reciprocating compressor 1 of Figure 1, and Figure 3 is a schematic cross-sectional view showing a cross-section of the two-stage reciprocating compressor 1 cut along line AA in Figure 2. When the vertical direction is referred to herein, the vertical direction shown in Figure 1 is used as the reference unless otherwise specified in the context. When the front-rear direction is referred to herein, the front-rear direction shown in Figure 2 is used as the reference unless otherwise specified in the context. Figure 2 shows an axis C that coincides with the central axis of the crankshaft, which will be described later. Axis C extends in the front-rear direction. In this specification, the direction along axis C is sometimes called the axial direction, and the direction extending perpendicular to axis C from axis C is sometimes called the radial direction.

[0016] As shown in FIG. 1, the two-stage reciprocating compressor 1 includes a housing 10. The housing 10 has a motor case 11, a crank case 12, a first cylinder 13a, and a second cylinder 13b. The first cylinder 13a and the second cylinder 13b are respectively provided above the crank case 12. Four legs are attached to the lower surface of the housing 10 via support portions 19. The two-stage reciprocating compressor 1 is installed at a desired installation location via legs 18.

[0017] On the outer surface of the motor case 11, a plurality of first ribs 11a extending along the axial direction and a second rib 11b extending along the vertical direction are provided. The upper end of the second rib 11b is connected to the rear end of the corresponding first rib 11a. Some of the plurality of first ribs 11a extend from the rear end to the front end of the motor case 11, and the remainder extends forward from the rear end of the motor case 11 and is connected to the second rib 11b midway.

[0018] An internal space penetrating therethrough along the axis C is formed in the motor case 11. The motor case 11 has a generally hollow cylindrical shape. A motor 22 is disposed in the internal space of the motor case 11. The motor 22 has a stator coil 22a attached to the inner wall of the motor case 11, a rotor 22b incorporated radially inside the stator coil 22a, and a motor rotating shaft 22c that rotates together with the rotor 22b. The motor 22 may include a rotation detection sensor for detecting the rotation position of the rotor 22b. The through hole of the motor case 11 is closed by a rear cap 23 at the rear end. Thereby, the rear surface of the rear cap 23 becomes the rear end surface 11c of the motor case 11. A through hole connecting the internal space and the external space of the motor case 11 is provided at the radial center of the rear cap 23. The motor rotating shaft 22c extends to the outside of the housing 10 through the through hole provided in the rear cap 23. The motor rotating shaft 22c is rotatably supported with respect to the motor case 11 via a bearing.

[0019] A blower fan 24 is attached to the rear end of a motor rotating shaft 22c that protrudes rearward from a motor case 11. The blower fan 24 rotates around a central axis C together with the motor rotating shaft 22c. Due to the rotation of the blower fan 24, an air current fi flowing from the rear in the axial direction of the blower fan 24 toward the fan and an air current fo flowing axially along the outer surface of the housing 10 from the front of the blower fan 24 are generated.

[0020] An internal space penetrating therethrough along an axis C is formed in the crank case 12. The internal space of the crank case 12 and the internal space of the motor case 11 are partitioned by a partition wall 20. A through hole provided in the crank case 12 is closed by a front cap 21 at its front end. The front cap 21 has a substantially disk-shaped cap body 21a and a dome 21b protruding forward at the center in the radial direction of the cap body 21a.

[0021] A crank mechanism is disposed in the internal space of the crank case 12. This crank mechanism has a crankshaft 15. The crankshaft 15 extends along the central axis C inside the crank case 12 and the motor case 11. The crankshaft 15 is supported by the front cap 21 at its front end. The crankshaft 15 penetrates into the motor case 11 through a through hole provided in the partition wall 20 and is supported by the inner peripheral surface of a hollow motor rotating shaft 22c inside the motor case 11. The crankshaft 15 is attached to the motor rotating shaft 22c so as to rotate around the central axis C together with the motor rotating shaft 22c. Thereby, the rotational driving force from the motor 22 is transmitted to the crankshaft 15 via the motor rotating shaft 22c.

[0022] The crankshaft 15 has a first eccentric portion 15a and a second eccentric portion 15b located axially rearward of the first eccentric portion 15a. The first eccentric portion 15a and the second eccentric portion 15b have a circular shape in cross-sectional view taken in a cross section perpendicular to the axis C. The center of the eccentric portion 15a is eccentric from the axis C. The first piston 16a is connected to the first eccentric portion 15a via a first connecting rod 14a. Similarly, the second piston 16b is connected to the second eccentric portion 15b via a second connecting rod 14b. The rotational motion of the crankshaft 15 is converted into reciprocating motion of the first piston 16a by the first connecting rod 14a and into reciprocating motion of the second piston 16b by the second connecting rod 14b. In this way, the first piston 16a reciprocates inside the first cylinder 13a, and the second piston 16b reciprocates inside the second cylinder 13a.

[0023] The first eccentric portion 15a and the second eccentric portion 15b have different phases from each other. For example, the phase of the first eccentric portion 15a and the phase of the second eccentric portion 15b are shifted by 180° from each other. Due to this phase shift, when the first piston 16a is driven in the direction of compressing the cylinder chamber of the first cylinder 13a, the second piston 16b is driven in the direction of expanding the cylinder chamber of the second cylinder 13b. Conversely, when the second piston 16b is driven in the direction of compressing the cylinder chamber of the second cylinder 13b, the first piston 16a is driven in the direction of expanding the cylinder chamber of the first cylinder 13a.

[0024] A first cylinder head 17a is provided at the tip of the first cylinder 13a, and a second cylinder head 17b is provided at the tip of the second cylinder 13b. The first cylinder head 17a has an intake port 27a for drawing air into its internal space and an exhaust port 27b for discharging compressed air. The internal space of the first cylinder head 17a is divided into an intake chamber and a discharge chamber by a partition wall. Air flowing into the intake chamber from outside the first cylinder head 17a through the intake port 27a is drawn into the first cylinder 13a, compressed by the first piston 16a reciprocating within the cylinder 13a, and then discharged into the discharge chamber. This compressed air is introduced to the intercooler 25 through piping 26a from the exhaust port 27b of the first cylinder head 17a, cooled in the intercooler 25, and then introduced to the second cylinder head 17b through piping 26b. The second cylinder head 17b has an intake port 28a for drawing in compressed air from piping 26b and an exhaust port (not shown) for discharging compressed air that has undergone the second stage of compression in the second cylinder 13b. Air flowing into the second cylinder head 17b via the intake port 28a is drawn into the second cylinder 13b, compressed for the second stage by the first piston 16b reciprocating within the cylinder 13b, and then discharged to the outside of the second cylinder head 17b via the exhaust port. The compressed air that has undergone the second stage of compression in the second cylinder 13b can be supplied to various pneumatic machines (not shown). Pneumatic machines include various devices that operate using compressed air. When the two-stage reciprocating compressor 1 is installed in a commercial vehicle, the compressed air from the second cylinder 13b can be supplied to, for example, air brakes, air suspension, and various other pneumatic machines installed in the commercial vehicle.

[0025] Thus, in the two-stage reciprocating compressor 1, the air introduced from the outside is compressed in the first stage in the first cylinder 13a and in the second stage in the second cylinder 13b. Thus, the first cylinder 13a is a low-pressure cylinder, and the second cylinder 13b is a high-pressure cylinder. In this specification, the first cylinder 13a may be referred to as the low-pressure compression element, and the second cylinder 13b may be referred to as the high-pressure compression element. The low-pressure compression element may include the first piston 16a and the first cylinder head 17a. The high-pressure compression element may include the second piston 16b and the second cylinder head 17b.

[0026] As shown in Figure 3, the intercooler 25 is positioned axially behind the blower fan 24. In other words, the blower fan 24 is positioned between the intercooler 25 and the rear end face of the motor case 11. The intercooler 25 is attached to the motor case 11, for example, by bolts (not shown).

[0027] The intercooler 25 is connected to the exhaust port 27b of the first cylinder head 17a via piping 26a and to the intake port 28a of the second cylinder head 17b via piping 26b. The intercooler 25 has a meandering pipe connecting pipes 26a and 26b, and numerous fins provided on this pipe. High-temperature compressed air compressed in the first cylinder 13a is supplied to the intercooler 25 from pipe 26a. As described above, an airflow fi flows as the blower fan 24 rotates, and this airflow passes through the intercooler 25. This airflow fi flows along the outer surface of the piping and fins of the intercooler 25, so that the compressed air passing inside the intercooler 25 is cooled.

[0028] Next, the operation of the two-stage reciprocating compressor 1 will be described. When current is applied to the stator coil 22a, the rotor 22b rotates relative to the stator coil 22a. At this time, the rotation of the rotor 22b is transmitted to the crankshaft 15 and the blower fan 24 via the motor rotating shaft 22c. The rotational motion of the crankshaft 15 is converted into the reciprocating motion of the first piston 16a by the first connecting rod 14a, and then converted into the reciprocating motion of the second piston 16b by the second connecting rod 14b. Due to the reciprocating motion of the first piston 16a and the second piston 16b, the air introduced from the outside is compressed in the first stage in the first cylinder 13a and in the second stage in the second cylinder 13b. The air compressed in the first cylinder 13a is cooled by the intercooler 25 and then introduced into the second cylinder 13b. Cooling air is supplied to the intercooler 25 from the blower fan 24, which is rotated by the rotational driving force from the motor 22.

[0029] Figure 4 is a perspective view showing a two-stage reciprocating compressor 1 according to another embodiment of the present invention. The two-stage reciprocating compressor 1 in Figure 4 differs from the two-stage reciprocating compressor 1 shown in Figure 1 in that it includes a cover 40. The cover 40 is a soundproof cover. The cover 40 may cover the entire circumference of the two-stage reciprocating compressor 1. In the illustrated embodiment, for convenience of mounting to the vehicle body, the legs 18 of the two-stage reciprocating compressor 1 are exposed from the cover 40. The cover 40 may have through holes in a part thereof that connect the inside and outside of the cover 40. The cover 40 is made of a soundproofing material. The material of the cover 40 may be, for example, felt, polyvinyl chloride, or other soundproofing material. This cover 40 can suppress the leakage of sound generated from the two-stage reciprocating compressor 1 to the outside.

[0030] Figure 5 is a perspective view showing a two-stage reciprocating compressor 1 according to another embodiment of the present invention. The two-stage reciprocating compressor 1 of Figure 5 differs from the two-stage reciprocating compressor 1 shown in Figure 1 in that it includes a silencer 50. The silencer 50 is attached to the dome 21b of the front cover 21. The silencer 50 has, for example, a hollow cylindrical shape. The internal space of the silencer 50 is defined as a first chamber that takes in outside air from an intake port 50a, and a sound-dampening chamber connected to the first chamber that takes in air from the first chamber. The intake port 50a can be provided at any position on the silencer 50. The silencer 50 may have partitioned spaces other than the internal space, the first chamber, and the sound-dampening chamber. The sound-dampening chamber is connected to the intake port 27a of the first cylinder head 17a. When the motor 22 is driven, the intake chamber of the first cylinder head 17a becomes negative pressure, so air is drawn into the first chamber from outside the silencer 50. This air enters the soundproofing chamber from the first chamber. The air expands in the soundproofing chamber, thus dampening the sound. This makes it possible to reduce intake noise generated when outside air is drawn in.

[0031] The above-described two-stage reciprocating compressor 1 can be installed, for example, in a commercial vehicle. One aspect of the present invention is a vehicle equipped with the two-stage reciprocating compressor 1.

[0032] The effects and advantages of the above embodiment are described below. In one embodiment of the present invention, a blower fan 24 is provided in the axial direction between the rear end surface 11c of the motor case 11 and the intercooler 25. This makes it easier for the cooling air generated by the blower fan 24 to pass through the intercooler 25, thereby improving the cooling effect of the compressed air in the intercooler 25. In conventional two-stage reciprocating compressors, the intercooler is provided in the axial direction between the rear end surface of the motor case and the blower fan. In this arrangement of conventional two-stage reciprocating compressors, the cooling air sent from the blower fan to the intercooler collides with the rear end surface of the motor case, causing turbulence in the airflow, and the cooling air from the blower fan does not sufficiently contribute to the cooling of the intercooler. In the embodiment of the present invention, the cooling effect is improved by changing the axial arrangement of the blower fan and the intercooler.

[0033] In the above embodiment, the outer surface of the motor case 11 is provided with a plurality of first ribs 11a extending in the axial direction and a plurality of second ribs 11b extending in the vertical direction. When the two-stage reciprocating compressor 1 is in operation, Joule heat is generated by the applied current applied to the stator coil 22a, and this heat generated in the stator coil 22a is transferred to the motor case 11. Because the surface area of ​​the outer surface of the motor case 11 is increased by the first ribs 11a and the second ribs 11b, the heat generated in the stator coil 22a can be efficiently dissipated into the atmosphere. Furthermore, the first rib 11a guides the cooling air from the blower fan 24 axially along the outer surface of the motor case 11. As a result, the cooling air from the blower fan 24 flows between adjacent first ribs 11a, further improving the heat dissipation efficiency.

[0034] The dimensions, materials, and arrangements of each component described herein are not limited to those explicitly described in the embodiments, and each component can be modified to have any dimensions, materials, and arrangements that fall within the scope of the present invention. Furthermore, components not explicitly described herein may be added to the described embodiments, and some of the components described in each embodiment may be omitted.

[0035] Some variations are illustrated below. The motor case 11 and the crankcase 12 may have an integrated one-piece structure. The motor case 11 and the crankcase 12 may be constructed as separate components. The two-stage reciprocating compressor 1 may be provided with a control circuit for controlling the motor 22.

[0036] The invention described in the original claims of the present application is listed below. [1] A rotary drive source housed in a case, An output shaft extending axially is provided, which outputs rotation from the aforementioned rotational drive source, with one end protruding from the end face of the case, A low-pressure compression element that compresses air using the rotational driving force from the output shaft as a power source, An intercooler for cooling the compressed air discharged from the low-pressure compression element, A high-pressure compression element that uses the rotational driving force from the output shaft as a power source to further compress the compressed air cooled by the intercooler, A blower fan connected to the output shaft and positioned between the end face of the case and the intercooler in the axial direction, A two-stage reciprocating compressor equipped with the following features. [2] The case has a plurality of ribs extending in the axial direction on its outer surface, [1] The two-stage reciprocating compressor described above. [3] The case has a plurality of other ribs extending in a direction perpendicular to the axial direction, [2] The two-stage reciprocating compressor described below. [4] The system further comprises a silencer that supplies the air to the low-pressure compression element. A two-stage reciprocating compressor as described in any of [1] to [3]. [5] The case, the low-pressure compression element, the intercooler, the high-pressure compression element, and the blower fan are further covered by a cover that covers at least a portion of them. A two-stage reciprocating compressor as described in any of [1] to [4]. [6] An automobile equipped with a two-stage reciprocating compressor as described in any of [1] to [5]. [Explanation of Symbols]

[0037] 1. Two-stage reciprocating compressor 10 Housing 11 Motor Case 12 Crankcase 13a First cylinder (low-pressure side cylinder) 13b Second cylinder (high-pressure side cylinder) 14a First connecting rod 14b Second connecting rod 15 Crankshaft 15a 1st eccentric part 15b 2nd eccentric part 16a First Piston 16b Second Piston 17a First Cylinder Head 17b Second Cylinder Head 18 Legs 19 Support part 21 Front cap 22 motors 22a Stator Coil 22b Rotor 22c motor rotation shaft 23 Rear cap 24 Blower fan 25 Intercooler

Claims

1. A rotary drive source housed in the internal space of the motor case, An output shaft extending axially is provided, which outputs rotation from the aforementioned rotational drive source, with one end protruding from the end face of the motor case, A crankcase having an internal space separated from the internal space of the motor case by a partition wall, A crankshaft is positioned within the internal space of the crankcase, extending through the partition wall to the internal space of the motor case, and to which rotational driving force from the output shaft is transmitted. A low-pressure compression element that compresses air by the rotational motion of the crankshaft, An intercooler for cooling the compressed air discharged from the low-pressure compression element, A high-pressure compression element that further compresses the compressed air cooled by the intercooler by the rotational motion of the crankshaft, A blower fan connected to the output shaft and positioned on the end face of the motor case in the axial direction, Equipped with, Two-stage reciprocating compressor.

2. The output shaft is formed to be hollow, The crankshaft is supported within the motor case by the inner circumferential surface of the output shaft. A two-stage reciprocating compressor according to claim 1.

3. The motor case and the crankcase have an integrated one-piece structure, as described in claim 1 or 2, for a two-stage reciprocating compressor.

4. The two-stage reciprocating compressor according to claim 1 or 2, further comprising a silencer that supplies the air to the low-pressure compression element.

5. A two-stage reciprocating compressor according to claim 1 or 2, further comprising a cover that covers at least a portion of the case, the low-pressure compression element, the intercooler, the high-pressure compression element, and the blower fan.

6. An automobile equipped with a two-stage reciprocating compressor according to any one of claims 1 to 5.

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