Working machine

Abstract

The objective of the present invention is to reduce a surface area occupied on a mounting surface by an air compressor without reducing the capacity of a tank. An air compressor 1 comprises: a motor 14 having an output shaft 14c extending in a horizontal direction; a first compressing unit 11 and a second compressing unit 12 which compress and discharge gas by means of a rotating motion of the output shaft 14c; and a plurality of tanks 50 into which the gas discharged from the first compressing unit 11 and the second compressing unit 12 flows. The number of the plurality of tanks 50 is at least three, and the plurality of tanks 50 are provided so as to surround the first compressing unit 11 and the second compressing unit 12 as seen in a vertical direction. Each of the plurality of tanks 50 has a shape having a length in the vertical direction that is greater than widths in front-back and left-right directions.

Description

Work equipment

[0001] The present invention relates to a work machine.

[0002] Conventionally, air compressors having tanks for storing compressed air have been known. The air compressor disclosed in Patent Document 1 has two tanks. The two tanks are arranged sideways with their longitudinal directions parallel to the surface on which the air compressor is placed, and legs are provided on each side for placing the tanks on the surface. Furthermore, a storage section for storing drainage is provided in a portion of the lower part of the tanks.

[0003] JP 2016-121588 A

[0004] However, it is desirable to make the area that the air compressor occupies on the mounting surface when viewed from above smaller than the area that the air compressor of Patent Document 1 occupies on the mounting surface.

[0005] Furthermore, there is a demand for improved durability against impacts that are transmitted from the mounting surface to the tank via the legs when the air compressor is mounted on the mounting surface.

[0006] Furthermore, when draining the drain, it is necessary to perform operations such as tilting the tank to store the drain in the storage section, which reduces the efficiency of drainage.

[0007] A work machine according to a first aspect includes a drive unit having an output shaft extending horizontally, a compression unit that compresses and discharges gas by rotational motion of the output shaft, and a plurality of tanks into which the gas discharged from the compression unit flows. The number of the plurality of tanks is at least three. The plurality of tanks are arranged to surround the compression unit when viewed in the vertical direction. Each of the plurality of tanks has a shape in which the length in the vertical direction is greater than the width in the front-rear and left-right directions.

[0008] According to the present invention, the area occupied by the air compressor on the mounting surface can be reduced without reducing the capacity of the tank.

[0009] 1 is a perspective view of the working machine's exterior. FIGS. 2(A) and 2(B) are external views of the working machine. FIGS. 3(A) and 3(B) are external views of the working machine. 2 is a perspective view of the working machine's exterior with the cover removed. FIGS. 5(A) and 5(B) are external views of the working machine with the cover removed. FIGS. 6(A) and 6(B) are external views of the working machine with the cover removed. FIGS. 7(A) and 7(B) are cross-sectional views of the working machine taken along line A-A in FIG. 6(A), and FIG. 7(B) is a cross-sectional view of the working machine taken along line B-B in FIG. 6(A). FIG. 8(A) is an external view of the tank, FIG. 8(B) is a cross-sectional view of an enlarged portion of the tank, and FIG. 8(C) is a cross-sectional view of an enlarged portion of the tank of a modified example. 3 is a schematic diagram of a working machine of a second modified example.

[0010] An air compressor, which is a work machine according to an embodiment, will be described with reference to the drawings. The air compressor described below is a reciprocating air compressor having a compressed air generating unit that compresses air in two stages. The use of the air compressor is not particularly limited, but it is suitable for use as a source of compressed air for a pneumatic tool that uses the pressure of the compressed air to drive nails or screws into a workpiece such as wood.

[0011] <Overall Configuration> Figure 1 is an external perspective view of a work machine (air compressor) 1. Figure 2(A) is an external view of the air compressor 1 as seen from the arrow AR1 in Figure 1, Figure 2(B) is an external view of the air compressor 1 as seen from the arrow AR2 in Figure 1, Figure 3(A) is an external view of the air compressor 1 as seen from the arrow AR4 in Figure 1, and Figure 3(B) is an external view of the air compressor 1 as seen from the arrow AR3 in Figure 1.

[0012] The air compressor 1 includes a cover 2, multiple tanks 51, 52, 53, and 54, and a power cord 58 that connects to an external commercial power outlet (AC power). The tanks 51, 52, 53, and 54 have substantially the same shape and dimensions. In the following description, when there is no need to distinguish between the tanks 51, 52, 53, and 54, they may be collectively referred to as tank 50.

[0013] The cover 2 covers the gap of the tank 50, which surrounds the components of the air compressor 1, as described below. The cover 2 is made of, for example, metal or resin and includes four side covers 2a, 2b, 2c, and 2d, a top cover 2e, and a bottom cover 2f. The side cover 2a is provided between the tank 51 and the tank 52 (see FIGS. 1, 2(A), and 3(A)). The side cover 2b is provided between the tank 52 and the tank 53 (see FIGS. 1, 2(B), and 3(A)). The side cover 2c is provided between the tank 53 and the tank 54 (see FIGS. 3(A) and 3(B)). The side cover 2d is provided between the tank 54 and the tank 51 (see FIG. 3(A)). In other words, the tank 50 is partially exposed between the four side covers 2a, 2b, 2c, and 2d. On the other hand, the four side covers 2a, 2b, 2c, and 2d and the tank 50 cooperate to be arranged so as to overlap the entire compressed air generating unit 10 in the front-to-back and left-to-right directions, and the compressed air generating unit 10 is not visible when viewed in the front-to-back and left-to-right directions from outside the four side covers 2a, 2b, 2c, and 2d and the tank 50. Note that the cover 2 is appropriately formed with openings that ensure operator access to a coupler 61, a pressure reducing valve 62, a pressure gauge 63, battery packs 67 and 68, etc., which will be described in detail below.

[0014] The top cover 2e is provided at the top end of the tank 50. The top cover 2e is provided with an operation unit 2g for operating the air compressor 1, switching between operating modes, etc., and a display unit 2h for displaying the pressure inside the tank 50, etc. (see FIGS. 1 and 3(A)). The bottom cover 2f is provided at the bottom ends of the side covers 2a, 2b, 2c, and 2d and at the bottom end of the tank 50. The top cover 2e is arranged so as to overlap the entire compressed air generating unit 10 (described later) in the vertical direction, so that the compressed air generating unit 10 is not visible from above the top cover 2e. Similarly, the bottom cover 2f is arranged so as to overlap the entire compressed air generating unit 10 (described later) in the vertical direction, so that the compressed air generating unit 10 is not visible from below the bottom cover 2f.

[0015] In the following description, the side where side cover 2a is provided will be referred to as the front or front, the side where side cover 2b is provided will be referred to as the left side or left side, the side where side cover 2c is provided will be referred to as the rear or rear, and the side where side cover 2d is provided will be referred to as the right side or right side. Also, the side where top cover 2e is provided will be referred to as the top side or upper side, and the side where bottom cover 2f is provided will be referred to as the bottom side or lower side.

[0016] Fig. 4 is an external perspective view of the air compressor 1 of Fig. 1 with the cover 2 removed. Fig. 5(A) is an external view of the air compressor 1 shown in Fig. 4 as seen from the front, and Fig. 5(B) is an external view of the air compressor 1 shown in Fig. 4 as seen from the left side. Fig. 6(A) is an external view of the air compressor 1 shown in Fig. 4 as seen from above, and Fig. 6(B) is an external view of the air compressor 1 shown in Fig. 4 as seen from the rear. Fig. 7(A) is a cross-sectional view of the air compressor 1 taken along line A-A in Fig. 6(A), and Fig. 7(B) is a cross-sectional view of the air compressor 1 taken along line B-B in Fig. 6(A).

[0017] In addition to the tank 50 , the air compressor 1 has a compressed air generating unit 10 , a control unit 17 , a power control unit 18 , a coupler 61 , connecting units 64 and 65 , and a drain discharge mechanism 70 .

[0018] 7(A) and 7(B), the compressed air generating unit 10 has a first compression unit 11, a second compression unit 12, a crankcase 13, a motor 14, and a propeller fan 15. A support member 59 attached below the crankcase 13 is connected to each of the tanks 51, 52, 53, and 54, so that the compressed air generating unit 10 is arranged so as to be surrounded by the tanks 51, 52, 53, and 54.

[0019] The motor 14 is a brushless motor having a rotor 14a and a stator 14b, and serves as a drive unit that generates driving force through rotation of the rotor 14a. The rotor 14a of the motor 14 is attached to an output shaft 14c. The output shaft 14c is supported so as to be rotatable in the front-to-rear direction on a plane parallel to the mounting surface (ground or floor).

[0020] The first compression section 11 compresses outside air, and the second compression section 12 further compresses the outside air (air) compressed by the first compression section 11. That is, the first compression section 11 is a low-pressure compression section, and the second compression section 12 is a high-pressure compression section.

[0021] 7A , the first compression section 11 and the second compression section 12 are provided at positions facing each other across the output shaft 14c of the motor 14 that penetrates the crankcase 13 (i.e., in the left-right direction across the output shaft 14c). More specifically, the first compression section 11 and the second compression section 12 are provided at positions that are 180 degrees apart in the rotational direction of the output shaft 14c, and are facing each other across the crankcase 13. In other words, the crankcase 13 is provided between the first compression section 11 and the second compression section 12.

[0022] The output shaft 14c that passes through the crankcase 13 is rotatably supported by a plurality of bearings. As shown in Fig. 7(B) , the propeller fan 15 is attached to one end (rear side) of the output shaft 14c that protrudes from the crankcase 13. The propeller fan 15 generates cooling air that mainly cools the compressed air generating unit 10 (the motor 14, the crankcase 13, etc.).

[0023] 7A , the first compression section 11 includes a first cylinder 20, a first cylinder head 21, and a first piston 22 reciprocally housed in the first cylinder 20. The second compression section 12 includes a second cylinder 30, a second cylinder head 31, and a second piston 32 reciprocally housed in the second cylinder 30. The first piston 22 included in the first compression section 11 and the second piston 32 included in the second compression section 12 are driven by the motor 14. In other words, the motor 14 is a common drive source for the first compression section 11 and the second compression section 12.

[0024] To convert the rotational motion of the output shaft 14c into the reciprocating motion of the first piston 22, one end of a first connecting rod 23 is coupled to the first piston 22, and the other end of the first connecting rod 23 is rotatably coupled to an eccentric cam provided on the output shaft 14c. In other words, the first connecting rod 23 straddles the crankcase 13 and the first cylinder 20, connecting the output shaft 14c and the first piston 22.

[0025] In order to convert the rotational motion of the output shaft 14c into the reciprocating motion of the second piston 32, one end of a second connecting rod 33 is coupled to the second piston 32, and the other end of the second connecting rod 33 is rotatably coupled to another eccentric cam provided on the output shaft 14c. In other words, the second connecting rod 33 straddles the crankcase 13 and the second cylinder 30, connecting the output shaft 14c and the second piston 32.

[0026] <Operation of the First Compression Section and the Second Compression Section> The rotational motion of the output shaft 14c of the motor 14 is converted into reciprocating motion by a conversion mechanism including the eccentric cam, connecting rod, etc., and is transmitted to the first piston 22 and the second piston 32. In other words, the rotational force output from the motor 14 is converted into reciprocating motion by the conversion mechanism and is input to the first piston 22 and the second piston 32. As a result, the first piston 22 and the second piston 32 reciprocate in a direction (left-right direction) intersecting the direction of the output shaft 14c (front-rear direction).

[0027] The two eccentric cams are eccentric in the same direction relative to the movement directions of the first piston 22 and the second piston 32. Therefore, when the first piston 22 moves in a direction that compresses the upper chamber of the first cylinder 20, the second piston 32 moves in a direction that causes gas (air) to flow into the upper chamber of the second cylinder 30. On the other hand, when the second piston 32 moves in a direction that compresses the upper chamber of the second cylinder 30, the first piston 22 moves in a direction that causes gas (air) to flow into the upper chamber of the first cylinder 20.

[0028] A buffer chamber is provided inside each of the first cylinder head 21 and the second cylinder head 31. Furthermore, a check valve is provided between the upper chamber of the first cylinder 20 and the buffer chamber in the first cylinder head 21, and between the second cylinder 30 and the buffer chamber in the second cylinder head 31. When the first piston 22 moves in a direction compressing the upper chamber of the first cylinder 20 and the air pressure in the upper chamber exceeds a predetermined pressure, the check valve between the upper chamber of the first cylinder 20 and the buffer chamber opens. Then, the air compressed by the first piston 22 is sent to the upper chamber of the second cylinder 30 via a pipe connecting the first cylinder 20 and the second cylinder 30.

[0029] Thereafter, the second piston 32 moves in a direction compressing the upper chamber of the second cylinder 30. When the air pressure in the upper chamber exceeds a predetermined pressure, a check valve between the upper chamber of the second cylinder 30 and the buffer chamber opens. The air compressed by the second piston 32 is then sent to the tank 51 via a pipe 19 (see FIGS. 5A, 6A, and 7B) that connects the second cylinder 30 to the tank 51. The four tanks 51, 52, 53, and 54 are connected to one another via the pipes. Therefore, compressed air generated by the compressed air generator 10 is sent to the tank 51 and then automatically and simultaneously distributed to the other tanks 52, 53, and 54. As a result, the internal pressure of all the tanks 50 is maintained uniform. Details of the pipes connecting the tanks 50 will be described later.

[0030] <Regarding the Tank> Figure 8(A) is an external view of the tank 50, and Figure 8(B) is an enlarged cross-sectional view of the lower part of the tank 50. As shown in Figure 8(A), each tank 50 has a pair of end walls 50a, 50b and a side wall 50c. The side wall 50c is formed in a cylindrical shape, with a hemispherical end wall 50a provided at one end of the side wall 50c and a hemispherical end wall 50b provided at the other end.

[0031] In the tank 50, the central axis 57 of the side wall 50c is set to pass through the center (top) of the pair of end walls 50a, 50b. The tank 50 is arranged so that this central axis 57 is aligned in the up-down direction. As a result, the side wall 50c has a cylindrical shape that extends in the up-down direction, i.e., a shape in which the length in the up-down direction is greater than the width in the front-rear and left-right directions.

[0032] The pair of end walls 50a, 50b close the side wall 50c in the vertical direction. Specifically, the end wall 50a is provided with a hemispherical top on the opposite side of the side wall 50c, thereby closing the lower side of the side wall 50c and protruding downward. The end wall 50b is provided with a hemispherical top on the opposite side of the side wall 50c, thereby closing the upper side of the side wall 50c and protruding upward. Legs 80 are provided near the top of the end wall 50a (i.e., at the lower end of the tank 50).

[0033] As shown in FIG. 4 , the four tanks 51, 52, 53, and 54 are arranged around the compressed air generator 10 with their respective central axes 57a, 57b, 57c, and 57d parallel or substantially parallel to one another, surrounding the compressed air generator 10. Specifically, the central axis 57a of the tank 51 is substantially parallel to the central axes 57b, 57c, and 57d of the other tanks 52, 53, and 54. Similarly, the central axis 57b of the tank 52 is substantially parallel to the central axes 57a, 57c, and 57d of the other tanks 51, 53, and 54. The central axis 57c of the tank 53 is substantially parallel to the central axes 57a, 57b, and 57d of the other tanks 51, 52, and 54. The central axis 57d of the tank 54 is substantially parallel to the central axes 57a, 57b, and 57c of the other tanks 51, 52, and 53.

[0034] Furthermore, the central axes 57a and 57d of the tanks 51 and 54 are perpendicular to the output shaft 14c of the motor 14. That is, the central axes 57a and 57d extend in the vertical direction. This means that the central axes 57b and 57c of the tanks 52 and 53 are also perpendicular to the output shaft 14c of the motor 14, that is, extend in the vertical direction. That is, the central axes 57a, 57b, 57c, and 57d of all the tanks 51, 52, 53, and 54 are perpendicular to the output shaft 14c and extend in the vertical direction.

[0035] The tanks 51 , 52 , 53 , 54 are arranged so as to protrude downward and upward from the compressed air generating section 10 having the first compression section 11 and the second compression section 12 .

[0036] As shown in FIG. 7(A), the tank 51 is disposed forward of the first compression section 11, and the tank 54 is disposed rearward of the first compression section 11. In other words, the first compression section 11 is disposed between the adjacent tanks 51 and 54. Also, as shown in FIG. 7(A), the tank 52 is disposed forward of the second compression section 12, and as shown in FIG. 7(B), the tank 53 is disposed rearward of the second compression section 12. In other words, the second compression section 12 is disposed between the adjacent tanks 52 and 53.

[0037] 6A, an imaginary rectangle 60 is defined by a first imaginary line A1 circumscribing the tanks 51 and 52, a second imaginary line A2 circumscribing the tanks 52 and 53, a third imaginary line A3 circumscribing the tanks 53 and 54, and a fourth imaginary line A4 circumscribing the tanks 54 and 51. This imaginary rectangle 60 is an area surrounded by the four tanks 51, 52, 53, and 54 when viewed from above and below. In other words, the imaginary rectangle 60 corresponds to the area occupied by the air compressor 1 when placed on a mounting surface.

[0038] As described above, the first compression section 11 and the second compression section 12 are disposed between adjacent tanks 50, and therefore, it can be said that the first compression section 11 and the second compression section 12 are disposed inside the imaginary rectangle 60. In other words, the first compression section 11 and the second compression section 12 are disposed so as to be surrounded by the tanks 50 when viewed in the vertical direction. Furthermore, the components of the air compressor 1 are disposed inside the imaginary rectangle 60. In other words, the components of the air compressor 1 are disposed so as to be surrounded by the tanks 50 when viewed in the vertical direction.

[0039] The tanks 51, 52, 53, and 54 arranged as described above are directly or indirectly connected via a plurality of connecting frames. As shown in Fig. 5(A), the tanks 51 and 52 are connected to each other via a connecting frame 55a. As shown in Fig. 5(B), the tanks 52 and 53 are connected to each other via a pair of connecting frames 55b and 55c. As shown in Fig. 6(B), the tanks 53 and 54 are connected to each other via a connecting frame 55d. The tanks 54 and 51 are connected to each other via a connecting frame in the same manner as the tanks 52 and 53 shown in Fig. 5(B).

[0040] <Regarding the Legs> As shown in FIG. 8B , legs 80 are provided on the underside of the lower end wall 50a of the tank 50. The legs 80 include an attachment portion 81, a fixing portion 82, and rubber feet 83. The attachment portion 81 is a cylindrical member, such as a metal boss, and is welded to an opening formed in the center of the end wall 50a of the tank 50 in the left-right and front-rear directions (i.e., the position through which the central axis 57 passes). The attachment portion 81 has a groove or hole connecting the outer surface and the inner surface. Furthermore, a thread groove is formed on the inner surface of the attachment portion 81. The fixing portion 82 is, for example, a metal coupler, and is fixed by screwing it onto the inner surface of the attachment portion 81 via a sealing member, such as an O-ring. The rubber feet 83 are formed of an elastic member, such as rubber, and are attached to the lower side of the fixing portion 82 by screwing or the like. That is, the mounting portion 81 and the fixing portion 82 are fixing members that fix the rubber leg 83 to the end wall 50a.

[0041] Rubber feet 83 are provided on the lower end walls 50a of the four tanks 51, 52, 53, and 54, respectively, so that four rubber feet 83 are provided on the bottom of the air compressor 1. As a result, the rubber feet 83 are attached to the undersides of the end walls 50a and elastically abut against the support surface (ground or floor). Typically, the air compressor 1 is placed upright so that the four rubber feet 83 are in contact with the support surface (ground, floor, etc.). In this case, as shown in FIG. 7(A), the reciprocating motion direction (sliding direction) of the first piston 22 and the second piston 32 is parallel or approximately parallel to the support surface.

[0042] <Regarding the Control Unit> As shown in FIG. 7A , the control unit 17 has a control board housed in a metal box provided below the crankcase 13. The control board is equipped with an inverter circuit necessary for inverter-controlling the motor 14, a boost circuit that boosts the voltage supplied from a commercial power source via a power cord 58 and supplies it to the inverter circuit, and various electronic components necessary for comprehensive control of the air compressor 1. The control unit 17 is provided between the tanks 51 and 52 and between the tanks 53 and 54 in the left-right direction. The box for the control unit 17 is bolted to the lower side of the support member 59. As a result, the control unit 17 is disposed inside the imaginary rectangle 60, i.e., surrounded by the multiple tanks 51, 52, 53, and 54 when viewed in the up-down direction. The control unit 17 is also disposed so that the multiple tanks 51, 52, 53, and 54 protrude downward from the control unit 17.

[0043] <Regarding the Power Control Unit 18> As shown in Figure 6(A), the power control unit 18 includes a circuit board housed in a metal box provided above the crankcase 13. The circuit board of the power control unit 18 is provided with a battery power supply circuit that controls the battery packs 67, 68. Specifically, the circuit board includes a boost circuit that boosts the power supplied from the battery packs 67, 68, a charging circuit that charges the battery packs 67, 68 with power supplied from a commercial power source via the power cord 58, and a control board that controls the boost circuit and the charging circuit. The power control unit 18 is provided between the tanks 51 and 52 and between the tanks 53 and 54 in the left-right direction. The box of the power control unit 18 is bolted to the connecting frame 55d.

[0044] <About the Coupler> As shown in Fig. 5(A) , the air compressor 1 has a coupler 61 on its front side, which is an air outlet through which compressed air is taken from the tank 50 to the pneumatic tool. The coupler 61 is provided between the tank 51 and the tank 52. The coupler 61 is disposed so that its front end is located rearward of the first imaginary line A1 shown in Fig. 6(A) , i.e., inside the imaginary rectangle 60. That is, the coupler 61 is disposed so that it is surrounded by the multiple tanks 51, 52, 53, and 54 when viewed in the up-down direction. The coupler 61 is also disposed so that the multiple tanks 51, 52, 53, and 54 protrude upward beyond the coupler 61 (see Figs. 5(A) , 5(B) , 6(B) , 7(A) and 7(B) ).

[0045] The couplers 61 are connected to the tank 51 by piping 95. Compressed air is extracted from the tank 51 via the couplers 61. Note that, although Fig. 5A shows a case where four couplers 61 are arranged in the vertical direction, the number of couplers 61 is not limited to four, and the direction in which the multiple couplers 61 are arranged is not limited to the vertical direction.

[0046] A pressure reducing valve 62, which is an adjustment unit that adjusts the pressure of the compressed air discharged from the coupler 61, is provided near the coupler 61. The pressure reducing valve 62 is arranged so that its front end is located rearward of the first imaginary line A1, i.e., inside the imaginary rectangle 60. That is, the pressure reducing valve 62 is arranged so that it is surrounded by the multiple tanks 51, 52, 53, and 54 when viewed in the vertical direction. The pressure reducing valve 62 is also arranged so that the multiple tanks 51, 52, 53, and 54 protrude above the pressure reducing valve 62 (see FIGS. 5(A), 5(B), 6(B), 7(A), and 7(B)). The pressure of the compressed air adjusted by the pressure reducing valve 62 is measured and displayed by a pressure gauge 63 provided near the pressure reducing valve 62.

[0047] <Connecting Portions> As shown in FIG. 5A , the air compressor 1 has two connecting portions 64, 65, which are connectors for connecting to external work machines (air compressors), on its front side. The connecting portions 64, 65 are arranged side by side in the left-right direction between the tank 51 and the tank 52 and are connected to the tank 51 via a pipe 96. The connecting portion 64 is connected to a flow path (e.g., a hose) through which compressed air supplied from an external work machine or compressed air provided to an external work machine passes. The connecting portion 65 is connected to a flow path (e.g., a hose) through which compressed air supplied from another external work machine or compressed air provided to another external work machine passes. In other words, by having the two connecting portions 64, 65, the air compressor 1 can be connected to two different external work machines. Note that the air compressor 1 is not limited to having two connecting portions 64, 65 and may have three or more connecting portions. This allows one air compressor 1 to be connected to three or more external work machines depending on the scale and content of the work.

[0048] If there were only one connecting portion, only two air compressors could be connected. Specifically, for example, when a first air compressor and a second air compressor each have only one connecting portion, only the second air compressor could be connected to the connecting portion of the first air compressor. On the other hand, when two connecting portions 64, 65 are provided as in the embodiment, an unlimited number of air compressors can be connected. Specifically, for example, when first to fifth air compressors each have two connecting portions 64, 65, the second air compressor and the third air compressor could be connected to the connecting portion of the first air compressor. In addition to the first air compressor, a fourth air compressor could be connected to the connecting portion of the second air compressor. In addition to the first air compressor, a fifth air compressor could be connected to the third air compressor. By being able to connect air compressors without any limit on the number, it is possible to increase the capacity of the tank connected to the air compressor 1 and increase the amount of usable air.

[0049] A changeover cock 66 is provided near the connecting parts 64, 65 to switch between communication between the connecting parts 64, 65 and the tank 51 and disconnection. This makes it possible to connect an external work machine to the air compressor 1 with the changeover cock 66 disconnecting the connecting parts 64, 65 from the tank 51. As a result, it is no longer necessary to temporarily discharge the compressed air inside the tank 50 when connecting to an external work machine, thereby improving operability.

[0050] <About the Power Supply Unit> In addition to power obtained from a commercial power source via the power cord 58 described above, the air compressor 1 can obtain power from battery packs (batteries) 67, 68 (see FIGS. 4, 5(A), 5(B), 6(A), and 6(B)), which are DC power sources. The battery pack 67 is detachably attached to a mounting portion provided between the tanks 51 and 54 on the right side of the air compressor 1. The battery pack 68 is detachably attached to a mounting portion provided between the tanks 52 and 53 on the left side of the air compressor 1. The power from the battery packs 67, 68 is boosted by a boost circuit in the power control unit 18 and supplied to the control board of the control unit 17. On the control board of the control unit 17, the output terminal of the boost circuit in the control unit 17 and the output terminal of the boost circuit in the electronic control unit 18 are electrically connected in parallel to the input terminal of the inverter circuit. The boost circuit of the control unit 17 and the boost circuit of the power control unit 18 are controlled so that their output voltages are approximately the same, so that the power supplied via the power cord 58 and the power of the battery packs 67, 68 are combined and supplied to the compressed air generating unit 10.

[0051] <Regarding Piping> As described above, the tanks 51, 52, 53, and 54 are in communication with one another via piping. Specifically, as shown in FIGS. 5(A), 5(B), and 6(B), the tanks 51 and 52 are in communication with one another via piping 90, the tanks 52 and 53 are in communication with one another via piping 91, and the tanks 53 and 54 are in communication with one another via piping 92. The piping 90 is provided below the front of the air compressor 1, the piping 91 is provided below the left side of the air compressor 1, and the piping 92 is provided below the rear of the air compressor 1. The tanks 51 and 54 are also in communication with one another via piping provided below the right side of the air compressor 1. As a result, compressed air generated by the compressed air generating unit 10 is introduced into the tank 51 via piping 19, and is then automatically and simultaneously introduced into the other tanks 52, 53, and 54 via piping 90, 91, and 92 and piping provided below the right side of the air compressor 1.

[0052] <Regarding the Drain Discharge Mechanism> The drain discharge mechanism 70 discharges drainage from the tanks 50. As shown in Figures 6(B), 7(B), and 8(B), the drain discharge mechanism 70 has a drain suction pipe 71 provided inside each tank 50, a drain cock 72 provided outside the tank 50, and a drain pipe 73. As shown in Figure 8(B), one end of the drain suction pipe 71 is inserted from above into the inside of a mounting portion 81 attached to the lower end wall 50a of the tank 50. In other words, one end of the drain suction pipe 71 is located in the center of the end wall 50a of the tank 50 in the front-to-rear and left-to-right directions.

[0053] As described above, the end wall 50a of the tank 50 is hemispherical, and the tank 50 is positioned so that the top of the end wall 50a faces downward. Therefore, drainage water in the tank 50 collects near the bottom of the top of the end wall 50a. As described above, the mounting portion 81 has grooves and holes that connect the outer surface and the inner surface, so that drainage water in the tank 50 flows into the inside of the mounting portion 81.

[0054] The other end of the drain suction pipe 71 is connected to a pipe for communicating with another tank 50. Specifically, the other end of the drain suction pipe 71 provided in tank 51 is connected to a pipe 90, the other end of the drain suction pipe 71 provided in tank 52 is connected to a pipe 91, the other end of the drain suction pipe 71 provided in tank 53 is connected to a pipe 92, and the other end of the suction pipe 71 provided in tank 54 is connected to a pipe 92.

[0055] The drain cock 72 shown in FIGS. 6(B) and 7(B) is provided near the connection between the tank 53 and the pipe 92. When the drain cock 72 is operated, the drain in the tank 50 is discharged together with the compressed air. That is, the drain that has flowed into the inside of the mounting portion 81 flows into the drain suction pipe 71 inserted into the inside of the mounting portion 81. When the drain cock 72 is operated, the drain in the tank 51 flows into the tank 52 via the pipe 90. The drain in the tank 52 flows into the tank 53 via the pipe 91. The drain in the tank 53 passes through the drain suction pipe 71 and is discharged from the drain pipe 73. The drain in the tank 51 also flows into the tank 54 via a pipe provided below the right side of the air compressor 1. The drain in the tank 54 passes through the pipe 93 and is discharged from the drain pipe 73.

[0056] As described above, one end of the drain suction pipe 71 is located near the bottom of the lower end wall 50a of the tank 50, which makes it possible to prevent drain from remaining in the tank 50. Furthermore, because the drain is discharged from near the bottom of the tank 50, there is no need for the operator to change the position of the tank 50 or the air compressor 1, for example by tilting it.

[0057] According to the above-described embodiment, the following advantageous effects can be obtained.

[0058] (1) The air compressor 1 has a plurality of tanks 50 into which gas discharged from the first compression section 11 and the second compression section 12 flows. The plurality of tanks 50 are arranged to surround the first compression section 11 and the second compression section 12 when viewed in the vertical direction. Each of the plurality of tanks 50 has a shape in which the length in the vertical direction is greater than the width in the horizontal direction. This allows the air compressor 1 to occupy a smaller area on the mounting surface than when tanks 50 of the same capacity are arranged with their longitudinal directions parallel to the mounting surface.

[0059] (2) The four tanks 51, 52, 53, and 54 are provided so as to surround the first compression section 11 and the second compression section 12 when viewed from above and below. This allows the air compressor 1 to be stably placed on a placement surface.

[0060] (3) Each of the plurality of tanks 50 has a cylindrical side wall 50c extending in the vertical direction and a pair of end walls 50a, 50b that close the hemispherical side wall 50c in the vertical direction, and is disposed so as to protrude downward beyond the first compression section 11 and the second compression section 12. This prevents the air compressor 1 from being larger than the longitudinal length of the tank 50, which contributes to making the air compressor 1 smaller in the vertical direction.

[0061] (4) Each of the tanks 50 has legs 80 attached to the underside of the end wall 50a and elastically abutting against the mounting surface. This prevents vibrations from being transmitted from the mounting surface to the tank 50 via the legs 80, thereby improving the durability of the air compressor 1.

[0062] (5) The leg portion 80 is fixed to the end wall 50a by the mounting portion 81 and the fixing portion 82 that penetrate the end wall 50a. This allows the leg portion 80 to be attached to the tank 50 in a simple manner.

[0063] (6) The tanks 50 each have a plurality of drain suction pipes 71 for discharging drainage accumulated therein, and the ends of the drain suction pipes 71 are located at the center of the end walls 50a in the front-rear and left-right directions. This allows the drainage to be accumulated in the lower part of the tanks 50 and discharged to the outside of the tanks 50 without having to change the attitude of the air compressor 1, thereby improving workability.

[0064] (7) The coupler 61 that extracts compressed air to an external pneumatic tool, the pressure reducing valve 62 that adjusts the pressure of the compressed air passing through the coupler 61, and the control unit 17 that controls the operation of the first compression unit 11 and the second compression unit 12 are surrounded by the multiple tanks 50 when viewed in the vertical direction. This makes the area occupied by the air compressor 1 smaller than the area of ​​an imaginary rectangle 60 that circumscribes the multiple tanks 50, thereby contributing to the miniaturization of the air compressor 1.

[0065] (8) The air compressor 1 has connecting sections 64, 65 that connect the flow paths through which compressed air supplied from an external work machine or compressed air provided to an external work machine passes. This allows one air compressor 1 to be connected to three or more external work machines depending on the scale and content of the work.

[0066] The above-described embodiment can be modified as follows.

[0067] (1) The leg 80 is not limited to being attached to the end wall 50a of the tank 50 as shown in FIG. 8(B). For example, as shown in FIG. 8(C), the leg 80 includes a rubber leg 83, a mounting portion 84 formed from a metal plate, and a fixing member 85. The mounting portion 84 is fixed by welding to the center in the front-to-back, left-to-right direction of the underside of the end of the end wall 50a (i.e., the position where the central axis 57 passes). The fixing member 85 is, for example, a screw, which passes through a mounting hole formed in the mounting portion 84 via the rubber leg 83 to fix the rubber leg 83. This provides the same effects as the leg 80 of the embodiment.

[0068] (2) In the above embodiment, the tank 50 is described as being made up of four tanks 51, 52, 53, and 54, but the number of tanks 50 may be three, or may be five or more.

[0069] FIG. 9 is a plan view, viewed from above, schematically illustrating an air compressor 1 according to a second modified example having three tanks 50. The tanks 50 are arranged to surround the compressed air generating unit 10. In particular, the center of gravity G of the compressed air generating unit 10 is located within a triangular imaginary region TR formed by connecting the axes of the multiple tanks 50. Therefore, even with three tanks 50, the air compressor 1 can stand on its own using the legs 80. By using three tanks 50, the weight of the air compressor 1 can be reduced. On the other hand, if the number of tanks 50 is five or more, the air compressor 1 becomes more stable when placed on a surface and the amount of compressed air that can be stored in the tanks 50 can be increased.

[0070] Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0071] 1...Work machine (air compressor), 2...Cover, 10...Compressed air generating section, 11...First compression section, 12...Second compression section, 13...Crankcase, 14...Motor, 14a...Rotor, 14b...Stator, 14c...Output shaft, 15...Propeller fan, 17...Control section, 18...Power control section, 50, 51, 52, 53, 54...Tank, 50a, 50b...End wall, 50c...Side wall, 61...Coupler, 62...Pressure reducing valve, 64, 65...Connecting section, 67, 68...Battery pack (battery), 70...Drain discharge mechanism, 71...Drain suction pipe, 80...Leg, 81, 84...Mounting section, 82...Fixing section, 83...Rubber leg, 85...Fixing member

Claims

1. a drive unit having an output shaft extending horizontally; a compression section that compresses and discharges gas by the rotational movement of the output shaft; a plurality of tanks into which the gas discharged from the compression section flows, the number of the plurality of tanks is at least three, and the plurality of tanks are arranged to surround the compression unit when viewed in the up-down direction, A work machine, wherein each of the plurality of tanks has a shape in which the length in the up-down direction is greater than the width in the front-rear and left-right directions.

2. The output shaft extends in the front-rear direction, The work machine according to claim 1 , wherein the compression section includes a cylinder extending in the left-right direction, and a piston that reciprocates in the left-right direction within the cylinder when the rotational motion of the output shaft is transmitted thereto.

3. The output shaft extends in the front-to-rear direction, the plurality of tanks include a first tank and a second tank disposed adjacent to each other in the left-right direction, The work machine according to claim 1 , wherein at least a portion of the output shaft is disposed between the first tank and the second tank.

4. A work machine as described in claim 3, having a fan attached to the output shaft and positioned between the first tank and the second tank.

5. The plurality of tanks includes a third tank arranged adjacent to the first tank in the fore-and-aft direction, The work machine according to claim 4 , wherein the distance between the first tank and the second tank is greater than the distance between the first tank and the third tank.

6. The compression section includes a cylinder extending in the left-right direction, and a piston that reciprocates in the left-right direction within the cylinder to which the rotational motion of the output shaft is transmitted; The work machine according to claim 5 , wherein at least a portion of the cylinder is disposed between the first tank and the third tank.

7. The work machine according to claim 1 , wherein the number of the plurality of tanks is four, and the plurality of tanks are provided so as to surround the compression unit when viewed in the up-down direction.

8. 2. The work machine according to claim 1, wherein each of the plurality of tanks has a cylindrical side wall extending in the vertical direction and a pair of end walls that close the side wall in the vertical direction and are formed in a hemispherical shape, and is positioned so as to protrude downwardly below the compression section.

9. The work machine according to claim 8 , wherein each of the plurality of tanks has legs attached to the lower surface of the end wall and elastically abutting against a mounting surface.

10. The work machine according to claim 9 , wherein the legs are fixed to the end walls by fixing members that pass through the end walls.

11. The work machine according to claim 9 , wherein the leg portion is fixed to the end wall by a fixing member that passes through an attachment portion that is welded to the end wall.

12. a plurality of drain suction pipes for discharging drainage accumulated inside each of the plurality of tanks; The work machine according to claim 8 , wherein an end of the drain suction pipe is located at a center portion of the end wall in the front-rear and left-right directions.

13. an air outlet through which compressed air is taken out; an adjusting unit that adjusts the pressure of the compressed air passing through the air outlet; a control unit that controls the drive of the compression unit, The work machine according to claim 1 , wherein the air outlet, the adjustment unit, and the control unit are arranged to be surrounded by a plurality of the tanks when viewed in the up-down direction.

14. The work machine according to claim 1 , further comprising a plurality of connecting portions to which flow paths through which compressed air supplied from an external work machine or compressed air provided to the external work machine passes are connected.

15. A plurality of legs formed of elastic members and arranged between the end walls of each of the plurality of tanks and the mounting surface; a lower cover located below the plurality of tanks and arranged to overlap the entire compression unit and the plurality of tanks in the vertical direction; The work machine according to claim 8 , wherein the legs protrude downwardly beyond the lower cover.

16. a compression section that compresses and discharges gas; a plurality of tanks into which the gas discharged from the compression section flows, the number of the plurality of tanks is at least three, and the plurality of tanks are arranged to surround the compression unit when viewed in the up-down direction, Each of the plurality of tanks has a cylindrical side wall extending in the up-down direction and a pair of end walls formed in a hemispherical shape and closing the up-down direction of the side wall, and has a shape in which the length in the up-down direction is greater than the width in the front-rear and left-right directions, The tank further includes a plurality of legs formed of elastic members and disposed between the end wall of each of the plurality of tanks and the mounting surface, A work machine, wherein each of the plurality of legs is disposed on the central axis of each of the plurality of tanks.

17. The apparatus further comprises a bottom cover located below the plurality of tanks and arranged to overlap the entire compression section and the plurality of tanks in the vertical direction; The work machine according to claim 16, wherein the leg portion protrudes downwardly beyond the lower cover.