Work machine and work machine system

Abstract

Provided are a work machine and a work machine system with improved workability. In this work machine, when a connected battery pack is a battery pack capable of 18 / 36 V switching, a charge / discharge circuit 400 allows discharging from the connected battery pack to a motor 14, and charging to the connected battery pack. When the connected battery pack is an 18 V battery pack, the charge / discharge circuit 400 prohibits discharging from the connected battery pack to the motor 14, and allows charging to the connected battery pack. When the connected battery pack is a 36 V battery pack, the charge / discharge circuit 400 allows discharging from the connected battery pack to the motor 14, and prohibits charging to the connected battery pack. 18 / 36 V switching circuits 121, 122 make it possible to switch between a first state in which a voltage across terminals of battery packs 67, 68 is a first voltage value (36 V), and a second state in which the voltage across terminals of the battery packs 67, 68 is a second voltage value (18 V).

Description

[Technical Field]

[0001] The present invention relates to a work machine to which a power supply device such as a battery pack can be connected, and to a work machine system including the power supply device. [Background technology]

[0002] The work machine described in Patent Document 1 below has a motor that is driven by power from a battery pack, and a charging circuit that charges the battery pack with power from a commercial power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 220704 Summary of the Invention [Problem to be solved by the invention]

[0004] There are battery packs (hereinafter referred to as "variable voltage battery packs") whose inter-terminal voltage differs when connected to a work machine having a load and when connected to a charger having a charging circuit. In a work machine such as that described in Patent Document 1, if a variable voltage battery pack is connected, proper charging is not possible unless the inter-terminal voltage of the battery pack is made different between when discharging and when charging. This makes it difficult to automatically switch from a state connected to a load to a state where charging is performed, leaving room for improvement in operability. There are also battery packs (hereinafter referred to as "fixed voltage battery packs") whose inter-terminal voltage is constant regardless of the device to which they are connected. If the inter-terminal voltage of the battery pack is made different between when discharging and when charging, operability is poor if the fixed voltage battery pack is connected and neither discharging nor charging is possible.

[0005] An object of the present invention is to provide a work machine and a work machine system with improved workability. [Means for solving the problem]

[0006] One aspect of the present invention is a work machine. The work machine includes a first connection portion to which a first power supply device is connected, the first power supply device having a terminal-to-terminal voltage of a first voltage value during discharging and a terminal-to-terminal voltage of a second voltage value during charging, a second connection portion to which a commercial power source is connected to receive power, and a circuit portion connected to the first connection portion and the second connection portion, the circuit portion including a load portion capable of consuming the power received from the first connection portion and a charging portion capable of outputting power received from the second connection portion to the first connection portion, and a switching portion capable of switching between a first state in which the terminal-to-terminal voltage of the first power supply device is the first voltage value and a second state in which the terminal-to-terminal voltage of the first power supply device is the second voltage value. Another aspect of the present invention is a work machine. This work machine comprises a first connection section to which a first power supply device capable of switching the voltage between its terminals between a first voltage value and a second voltage value and a second power supply device whose terminal voltage is either the first voltage value or the second voltage value are alternatively connected to input power, a second connection section to which a commercial power source is connected to input power, and a circuit section connected to the first connection section and the second connection section, the circuit section comprising a load section capable of consuming power input to the first connection section, and a charging section capable of outputting power input from the second connection section to the first connection section, and when the first power supply device is connected to the first connection section, the circuit section allows consumption by the load section of the power input to the first connection section and output by the charging section, and when the second power supply device is connected to the first connection section, prohibits either consumption by the load section of the power input to the first connection section or output by the charging section.

[0007] Another aspect of the present invention is a work machine system. The work machine system includes a first power supply device capable of switching a terminal-to-terminal voltage between a first voltage value and a second voltage value, a second power supply device whose terminal voltage is either the first voltage value or the second voltage value, and a work machine. The work machine includes a first connection portion that selectively connects the first power supply device and the second power supply device to receive power, a second connection portion that is connected to a commercial power source to receive power, and a circuit portion connected to the first connection portion and the second connection portion. The circuit portion includes a load portion that can consume the power received from the first connection portion, and a charging portion that can output the power received from the second connection portion to the first connection portion. When the first power supply device is connected to the first connection portion, the circuit portion allows the load portion to consume the power received from the first connection portion and the charging portion to output the power, and when the second power supply device is connected to the first connection portion, the circuit portion prohibits either the load portion from consuming the power received from the first connection portion or the charging portion from outputting the power.

[0008] Another aspect of the present invention is a work machine. a first power supply device having a terminal voltage of a first voltage value; is the a first connection section to which a second power supply device having two voltage values ​​is selectively connected and to which power is input; a second connection portion that is connected to a commercial power source and receives power; a circuit portion connected to the first connection portion and the second connection portion, The circuit unit includes: a load unit capable of consuming the power input to the first connection unit; a charging unit capable of outputting power input from the second connection unit to the first connection unit, The circuit unit includes: When the first power supply device is connected to the first connection section, power input to the first connection section is allowed to be consumed by the load section; When the second power supply device is connected to the first connection section, the power supply prohibits the load section from consuming the power input to the first connection section and allows the charging section to output the power.

[0009] The present invention may be expressed as an "electrical device" or an "electrical device system", and such expressions are also valid as aspects of the present invention. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a work machine and a work machine system with improved workability. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. [Figure 2] 2(A) and 2(B) are external views of the work machine. [Figure 3] 3(A) and 3(B) are external views of the work machine. [Figure 4] FIG. 2 is a perspective view of the appearance of the work machine with the cover removed. [Figure 5] 5(A) and 5(B) are external views of the working machine with the cover removed. [Figure 6] 6(A) and 6(B) are external views of the working machine with the cover removed. [Figure 7] 7(A) is a cross-sectional view of the working machine taken along line AA in FIG. 6(A), and FIG. 7(B) is a cross-sectional view of the working machine taken along line BB in FIG. 6(A). [Figure 8] FIG. 8(A) is an external view of the tank, FIG. 8(B) is an enlarged cross-sectional view of a portion of the tank, and FIG. 8(C) is an enlarged cross-sectional view of a portion of a modified tank. [Figure 9] FIG. 2 is an overall circuit block diagram of the work machine. [Figure 10] FIG. 2 is a circuit block diagram showing an enlarged main circuit portion of the overall circuit block diagram. [Figure 11] FIG. 2 is an enlarged circuit block diagram showing a portion of the overall circuit block diagram that includes an assist power supply, which is an auxiliary circuit section that performs power assist using a battery pack. [Figure 12] FIG. 3 is an enlarged circuit block diagram showing a portion of the auxiliary circuit section including a charging section. [Figure 13] This is a circuit block diagram related to charging and discharging of a battery pack in a work machine, and is a circuit block diagram when a battery pack whose inter-terminal voltage can be switched between a first voltage value (36 V) and a second voltage value (18 V) is connected. [Figure 14] FIG. 10 is a circuit block diagram relating to charging and discharging of a battery pack in a work machine, in which a battery pack having a second voltage value (18V) between its terminals is connected. [Figure 15] FIG. 2 is a circuit block diagram relating to charging and discharging of a battery pack in a work machine, in which a battery pack having a terminal voltage of a first voltage value (36 V) is connected. [Figure 16] 4 is a flowchart of charge / discharge control in a work machine. [Figure 17] FIG. 10 is an explanatory diagram of another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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 supply source of compressed air to a pneumatic tool that uses the pressure of the compressed air to drive nails or screws into workpieces such as wood.

[0013] <Overall Configuration> Fig. 1 is an external perspective view of a work machine (air compressor) 1. Fig. 2(A) is an external view of the air compressor 1 as seen from the arrow AR1 in Fig. 1, Fig. 2(B) is an external view of the air compressor 1 as seen from the arrow AR2 in Fig. 1, Fig. 3(A) is an external view of the air compressor 1 as seen from the arrow AR4 in Fig. 1, and Fig. 3(B) is an external view of the air compressor 1 as seen from the arrow AR3 in Fig. 1.

[0014] 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, the tanks 51, 52, 53, and 54 may be collectively referred to as tank 50 when no distinction is needed.

[0015] The cover 2 covers the gap of the tank 50 that surrounds the components of the air compressor 1, as will be described later. 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 are arranged in cooperation 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.

[0016] 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, and the like, 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 in the vertical direction with the entire compressed air generating unit 10, which will be described later, so that the compressed air generating unit 10 cannot be seen from above the top cover 2e. Similarly, the bottom cover 2f is arranged so as to overlap in the vertical direction with the entire compressed air generating unit 10, which will be described later, so that the compressed air generating unit 10 cannot be seen from below the bottom cover 2f.

[0017] 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.

[0018] Fig. 4 is an external perspective view of the air compressor 1 in 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 AA in Fig. 6(A), and Fig. 7(B) is a cross-sectional view of the air compressor 1 taken along line BB in Fig. 6(A).

[0019] 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 .

[0020] 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.

[0021] The motor 14 is a brushless motor having a rotor 14a and a stator 14b, and is a drive unit that generates driving force by the 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).

[0022] 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.

[0023] 7(A), 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.

[0024] 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.).

[0025] 7(A), the first compression section 11 includes a first cylinder 20, a first cylinder head 21, and a first piston 22 housed in the first cylinder 20 so as to be capable of reciprocating. The second compression section 12 includes a second cylinder 30, a second cylinder head 31, and a second piston 32 housed in the second cylinder 30 so as to be capable of reciprocating. 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 a 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.

[0026] 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.

[0027] 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.

[0028] <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) that intersects with the direction of the output shaft 14c (front-rear direction).

[0029] 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.

[0030] 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.

[0031] 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 located 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. The pipes connecting the tanks 50 will be described in detail later.

[0032] <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.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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.

[0037] The tanks 51, 52, 53, and 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.

[0038] 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.

[0039] 6(A), an imaginary rectangle 60 is defined as 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.

[0040] 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.

[0041] 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).

[0042] <Regarding the Legs> As shown in FIG. 8(B), 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 legs 83. The attachment portion 81 is a cylindrical member, such as a metal boss, and is fixed by welding 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 that connects the outer surface to 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 legs 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 attachment portion 81 and the fixing portion 82 are fixing members that attach the rubber legs 83 to the end wall 50a.

[0043] 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 underside of the end walls 50a and elastically abut against the mounting surface (ground or floor). Typically, the air compressor 1 is placed upright so that the four rubber feet 83 are in contact with the mounting 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 mounting surface.

[0044] <Regarding the Control Unit> As shown in FIG. 7(A), 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.

[0045] <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.

[0046] <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 tanks 51 and 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. In other words, the coupler 61 is disposed so that it is surrounded by the multiple tanks 51, 52, 53, and 54 when viewed from above and below. 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)).

[0047] The coupler 61 is connected to the tank 51 by a pipe 95. Compressed air is taken out from the tank 51 via this coupler 61. Note that, although FIG. 5(A) 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.

[0048] 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 disposed 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 disposed 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 disposed 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.

[0049] <Connecting Portions> As shown in FIG. 5(A), the air compressor 1 has two connecting portions 64, 65 on its front side, which are connectors for connecting to external working machines (air compressors). 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 by 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 working machine or compressed air provided to an external working machine passes. The connecting portion 65 is connected to a flow path (e.g., a hose) through which compressed air supplied from another external working machine or compressed air provided to another external working machine passes. In other words, by having the two connecting portions 64, 65, the air compressor 1 can be connected to two different external working 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.

[0050] 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, air compressors can be connected without any limit on the number. 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 can be connected to the connecting portion of the first air compressor. In addition to the first air compressor, a fourth air compressor can be connected to the connecting portion of the second air compressor. In addition to the first air compressor, a fifth air compressor can 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.

[0051] 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 workability.

[0052] <About the Power Supply> 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 part 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 part 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.

[0053] <Regarding Piping> As described above, 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), tanks 51 and 52 are in communication with one another via piping 90, tanks 52 and 53 are in communication with one another via piping 91, and tanks 53 and 54 are in communication with one another via piping 92. Pipe 90 is provided below the front of air compressor 1, pipe 91 is provided below the left side of air compressor 1, and pipe 92 is provided below the rear of air compressor 1. Tanks 51 and 54 are also in communication with one another via piping provided below the right side of air compressor 1. As a result, compressed air generated by compressed air generating unit 10 is introduced into 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 air compressor 1.

[0054] <Regarding the Drain Discharge Mechanism> The drain discharge mechanism 70 discharges drainage from the tank 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.

[0055] 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 inside the tank 50 collects near the top of the lowest part 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 inside the tank 50 flows into the inside of the mounting portion 81.

[0056] 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.

[0057] The drain cock 72 shown in Figures 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 inside the tank 50 is discharged together with the compressed air. That is, the drain that has flowed inside the mounting portion 81 flows into the drain suction pipe 71 inserted inside the mounting portion 81. When the drain cock 72 is operated, the drain inside the tank 51 flows into the tank 52 via the pipe 90. The drain inside the tank 52 flows into the tank 53 via the pipe 91. The drain inside the tank 53 passes through the drain suction pipe 71 and is discharged from the drain pipe 73. The drain inside the tank 51 also flows into the tank 54 via a pipe provided below the right side of the air compressor 1. The drain inside the tank 54 passes through the pipe 93 and is discharged from the drain pipe 73.

[0058] 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. In addition, 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.

[0059] The above description has focused on the mechanical configuration of the air compressor 1. This mechanical configuration provides the following effects.

[0060] (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 from the top to bottom. Each of the plurality of tanks 50 has a shape in which the length in the top-bottom direction is greater than the width in the left-right direction. This allows the area occupied by the air compressor 1 on the mounting surface to be smaller than when tanks 50 of the same capacity are arranged so that their longitudinal directions are parallel to the mounting surface.

[0061] (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 the top and bottom. This allows the air compressor 1 to be stably placed on a placement surface.

[0062] (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 ensures that the air compressor 1 is not larger than the longitudinal length of the tank 50, thereby contributing to the vertical miniaturization of the air compressor 1.

[0063] (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.

[0064] (5) The leg portion 80 is fixed to the end wall 50a by the attachment portion 81 and the fixing portion 82 which penetrate the end wall 50a. This allows the leg portion 80 to be attached to the tank 50 in a simple manner.

[0065] (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 wall 50a in the front-rear and left-right directions. This allows drainage to be accumulated in the lower part of the tank 50 and discharged to the outside of the tank 50 without having to change the attitude of the air compressor 1, thereby improving workability.

[0066] (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 from above and below. 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.

[0067] (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.

[0068] The above-described mechanical configuration can be modified as follows.

[0069] (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 has rubber legs 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 and left-to-right directions 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 allows for the same effects as those of the leg 80 of the embodiment to be obtained.

[0070] (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.

[0071] The following description will focus on the circuit configuration of the air compressor 1.

[0072] As shown in Fig. 9, the air compressor 1 has battery pack connectors 47 and 48 as first connectors. In the example of Fig. 9, battery packs 67 and 68 are connected (attached) to the battery pack connectors 47 and 48, respectively. The air compressor 1 with the battery packs connected to the battery pack connectors 47 and 48 is an example of a work machine system. The air compressor 1 has a commercial power connector 49 as a second connector that is connected to a commercial power source 139 to input electric power.

[0073] The air compressor 1 has a motor 14 for rotating and driving the first compression section 11 and the second compression section 12 to send compressed air into the tank 50. The motor 14 is a load that can consume power (power from the battery packs 67 and 68) input to the battery pack connectors 47 and 48. The air compressor 1 includes a main circuit section 200 for driving the motor 14 using a commercial power supply 139 (commercial AC power supply), which is an external AC power supply, and an auxiliary circuit section 300 for power assist that uses the two battery packs 67 and 68.

[0074] The air compressor 1 has 18 / 36V switching circuits 121, 122 as switching units. The 18 / 36V switching circuits 121, 122 are circuits that can switch the voltage between the terminals of the battery packs 67, 68 between 18V and 36V.

[0075] When the air compressor 1 receives power supply from the battery packs 67, 68, i.e., when the power input to the battery pack connectors 47, 48 is consumed by the motor 14 as a load, the 18 / 36V switching circuits 121, 122 set the voltage between the terminals of the battery packs 67, 68 to 36V. When the air compressor 1 charges the battery packs 67, 68, the 18 / 36V switching circuits 121, 122 set the voltage between the terminals of the battery packs 67, 68 to 18V.

[0076] As shown in Figures 9 and 10, the main circuit section 200 is provided with a rectifier section 131, an AC side power supply boost circuit 132 as a second power supply section, an inverter section 133, and a main control section 140 for controlling the inverter section 133, in order to drive the motor 14 by receiving supply of a commercial power supply 139 (AC 100V: for example, a maximum rated current of a socket is 15A) which is an external AC power supply.

[0077] A noise filter 134 is inserted between the commercial power supply 139 and the rectifier 131. A smoothing capacitor 135 is connected to the rectified output side of the rectifier 131. AC power from the commercial power supply 139 is rectified by the rectifier 131, and the DC power smoothed by the smoothing capacitor 135 is supplied to the AC-side power supply boost circuit 132. A current detection resistor 136 is inserted in the connection line between the rectifier 131 and the AC-side power supply boost circuit 132. An AC-side load current detection unit 137 detects (monitors) the AC load current based on the voltage drop across the current detection resistor 136, and outputs an AC load current detection signal to the main control unit 140.

[0078] The AC power supply boost circuit 132 includes a boost circuit such as a DC-DC converter, and the boosted DC power is supplied to the motor 14 via the inverter unit 133. The rectifier unit 131, the AC power supply boost circuit 132, and the smoothing capacitor 135 are an example of an AC power supply unit.

[0079] In the illustrated example, the AC-side power supply boost circuit 132 is a chopper-type DC-DC converter having a choke coil 321, a switching element 322, a diode 323, and a capacitor 324, and has a boost voltage control unit 325 that controls the switching operation of the switching element 322. A boost voltage detection unit 138 is provided on the boost output side of the AC-side power supply boost circuit 132.

[0080] The main control unit 140 receives as input a boost voltage monitoring signal from the boost voltage detection unit 138, a rotation detection signal from a rotation sensor 141 that detects the rotation of the motor 14, and a pressure detection signal from a pressure sensor 142 that detects the pressure inside the tank. The main control unit 140 outputs a boost voltage control signal to the AC side power supply boost circuit 132 (boosted voltage control unit 325) and outputs an inverter control signal to the inverter unit 133, and supplies the DC power boosted by the AC side power supply boost circuit 132 to the motor 14 via the inverter unit 133, thereby controlling the rotation of the motor 14 by, for example, PWM control. The first compression unit 11 and the second compression unit 12 are rotationally driven by the motor 14, and air discharged from the first compression unit 11 and the second compression unit 12 is sent to the tank 50.

[0081] The operation panel unit 196 has a display panel 191 that displays warnings such as the tank pressure and overload, an operation button 192 that switches the power on and off, a charge button 193 that commands charging of the battery packs 67, 68, a mode change button 194 that commands switching between operation modes, and an assist button 195 that commands power assistance using the battery packs 67, 68, and is provided with a switch panel control unit 190 to control these. The switch panel control unit 190 is connected to the main control unit 140 via a communication circuit 197.

[0082] A circuit power supply unit 290 is provided to supply a stabilized DC voltage to the main control unit 140, the operation panel unit 196, the communication circuit 197, etc. The circuit power supply unit 290 uses the DC output of the rectifier unit 131 to supply a power supply voltage Vcc(A) to the main control unit 140, etc., and a power supply voltage Vcc(C) to the switch panel control unit 190, the communication circuit 197, etc. The circuit power supply unit 290 has a step-down transformer 291 having one primary winding and two secondary windings, a switching element 292 that switches the transformer primary side, a circuit power supply drive circuit 293 that outputs a drive signal to the switching element 292, and rectifying and smoothing circuits 294 and 295 that are provided for the two secondary windings, respectively. The DC output voltage of the rectifying and smoothing circuit 294 is supplied as Vcc(A) to the main control unit 140 and the like, and the DC output voltage of the rectifying and smoothing circuit 295 is supplied as Vcc(C) to the switch panel control unit 190, communication circuit 197 and the like.

[0083] 9, 11, and 12, the auxiliary circuit unit 300 includes an assist power supply unit 150 as a first power supply unit for assisting the drive of the motor 14 with a battery power source (DC power source), a charging unit 170 for charging the battery packs 67, 68 as battery power sources, a sub-controller 180, a circuit power supply unit 110, and a communication circuit 100. The sub-controller 180 includes a control circuit such as a CPU, and controls the operation of the assist power supply unit 150 and the charging unit 170 in cooperation with the main control unit 140. The circuit power supply unit 110 supplies a stabilized DC voltage to the sub-controller 180, the communication circuit 100, etc. The communication circuit 100 forms an electrically insulated communication line between the main control unit 140 and the sub-controller 180.

[0084] Battery voltage detection units 146 and 147 are provided to detect the voltages of the battery packs 67 and 68 (hereinafter referred to as "battery voltages" respectively). Battery voltage detection signals from the battery voltage detection units 146 and 147 are supplied to the sub-control unit 180 respectively. The battery packs 67 and 68 can communicate with the sub-control unit 180. The sub-control unit 180 acquires battery information (rated voltage, battery temperature, etc.) from the battery packs 67 and 68 respectively.

[0085] The assist power supply unit 150 includes a DC-DC step-up converter configuration as a step-up circuit. The assist power supply unit 150 includes switching elements (e.g., MOSFETs) 152 and 153 connected in a push-pull manner to the primary side of a step-up transformer 151, an assist power supply drive circuit 154 that alternately switches the switching elements 152 and 153, a rectifier unit 155 connected to the secondary side of the step-up transformer 151, a choke coil 163, a smoothing capacitor 156, and an assist current control unit 157. By providing the smoothing choke coil 163 on the output side of the rectifier unit 155 and configuring the choke coil 163 and smoothing capacitor 156 as a choke input type smoothing circuit, it is possible to reduce pulsation in the output voltage of the assist power supply unit 150 even when the duty of the PWM control of the switching elements 152 and 153 (hereinafter referred to as "duty") is small. This is advantageous in terms of the withstand voltage of the smoothing capacitor 156 because when a high assist output voltage is set, the voltage is applied to the smoothing capacitor 156 via the choke coil 163 (the withstand voltage can be lower than when there is no choke coil).

[0086] A current detection resistor 158 is inserted in the connection line between the rectifier unit 155 and the inverter unit 133. The assist current control unit 157 detects (monitors) the output current (also referred to as "assist output current") of the assist power supply unit 150 from the voltage drop across the current detection resistor 158, and feeds back an assist current detection signal to the assist power supply drive circuit 154 via a photocoupler 159 serving as a feedback circuit. The photocoupler 159 is used here to electrically insulate the main circuit unit 200, which is electrically connected to the commercial power supply 139, from the auxiliary circuit unit 300, which is electrically connected to the battery packs 67, 68, and the use of a photocoupler in the following explanation will be based on the same reason.

[0087] The DC power of one or both of the battery packs 67, 68 is supplied to the primary side of a step-up transformer 151 of the assist power supply unit 150. An assist voltage detection unit 160 for detecting the output voltage of the assist power supply unit 150 (also referred to as "assist output voltage") is provided on the output side of the rectification unit 155 of the assist power supply unit 150, and an assist voltage control unit 161 for controlling the assist output voltage. The DC output power of the assist power supply unit 150 is supplied to the inverter unit 133 via a series diode 182 (where it is combined with the DC output power of the AC-side power supply step-up circuit 132).

[0088] The sub-controller 180 outputs an output current control signal to the assist current control unit 157 of the assist power supply 150 via the photocoupler 162 , and outputs an output voltage control signal for the assist power supply 50 to the assist voltage control unit 161 via the photocoupler 164 .

[0089] The output terminal of the AC power supply boost circuit 132 and the output terminal of the assist power supply 150 are connected in parallel via a series diode 182. In other words, the AC power supply boost circuit 132 and the assist power supply 150 are electrically connected in parallel to the motor 14.

[0090] Specifically, the assist power supply unit 150 receives an output current control signal and an output voltage control signal from the sub-controller 180 to control the drive signal of the assist power supply drive circuit 154, and by changing the duty when alternately switching the switching elements 152, 153, it is possible to perform voltage variable control to increase or decrease the DC voltage across the output-side smoothing capacitor 156. In other words, the assist power supply unit 150 can drive the motor 14 with PAM control that increases or decreases the voltage supplied to the inverter 33. Also, an assist power on / off signal is supplied from the sub-controller 180 to the assist power supply drive circuit 154 of the assist power supply unit 150. When the assist power on / off signal commands "assist power on," the assist power supply drive circuit 154 is activated to enable switching, and when the signal commands "assist power off," the operation of the assist power supply drive circuit 154 is stopped.

[0091] The charging unit 170 is a circuit that can output power input from the commercial power supply connection unit 49 to the battery pack connection units 47, 48, that is, a circuit for charging the battery packs 67, 68 with power from the commercial power supply 139. The charging unit 170 includes a configuration of a step-down DC-DC converter.

[0092] Charging unit 170 has rectifying unit 171 that receives supply from commercial power supply 139 via noise filter 134, smoothing capacitor 172, step-down transformer 173, switching element 174 that switches the primary side of the transformer, charging power supply drive circuit 175 that drives switching element 174 on and off, diode 176 and smoothing capacitor 177 that serve as a rectifying and smoothing circuit that rectifies and smoothes the secondary side output of transformer 173, charging current control unit 178, and charging voltage control unit 179.

[0093] A current detection resistor 181 is inserted in the connection line between the rectifying and smoothing circuit on the secondary side of transformer 173 and battery packs 67, 68. Charging current control unit 178 detects (monitors) the charging current from the voltage drop across current detection resistor 181. A charging current detection signal from charging current control unit 178 and a charging voltage control signal from charging voltage control unit 179 are fed back to charging power supply drive circuit 175 via photocoupler 182, which serves as a feedback circuit.

[0094] The circuit power supply unit 110 uses the DC output of the rectifier unit 171 of the charging unit 170 to supply a power supply voltage Vcc(B) to the sub-controller 180 and other components, and also supplies power to a photocoupler 185 that transmits a charging power on / off signal. The circuit power supply unit 110 includes a step-down transformer 111 having one primary winding and two secondary windings, a switching element 112 that switches the transformer primary side, a circuit power supply drive circuit 113 that outputs a drive signal to the switching element 112, and rectifying and smoothing circuits 114 and 115 that are provided for the two secondary windings, respectively. The DC output voltage of the rectifying and smoothing circuit 114 is supplied as Vcc(B) to the sub-controller 180, photocoupler 182, and other components. The DC output voltage of the rectifying and smoothing circuit 115 is supplied to the photocoupler 185. The photocoupler 185 transmits the charging power on / off signal from the sub-controller 180 to the charging power supply drive circuit 175. When the charging power on / off signal indicates "charging power on," the charging power drive circuit 175 is operated to switch the switching element 174, and when the signal indicates "charging power off," the operation of the charging power drive circuit 175 is stopped.

[0095] A relay 186 (first cutoff circuit) is provided to turn on / off the connection between the battery pack 68 (battery pack connection unit 48) and the charging unit 170. A relay 187 (second cutoff circuit) is provided to turn on / off the connection between the battery pack 67 (battery pack connection unit 47) and the charging unit 170. A relay 188 is provided to turn on / off the connection between the battery pack 68 (battery pack connection unit 48) and the assist power supply unit 150. A relay 189 is provided to turn on / off the connection between the battery pack 67 (battery pack connection unit 47) and the assist power supply unit 150. The relays 186 to 189 are each controlled to turn on / off by a relay on / off signal from the sub-control unit 180.

[0096] The communication circuit 100 has two photocouplers 101 and 102, and forms an electrically insulated communication line between the main control unit 140 and the sub-control unit 180. The photocoupler 101 transmits information signals from the main control unit 140 to the sub-control unit 180, and the photocoupler 102 transmits information signals from the sub-control unit 180 to the main control unit 140.

[0097] A thermistor Th3 for temperature detection is provided in the switching elements 152 and 153 of the assist power supply unit 150. A temperature monitoring signal from the thermistor Th3 is output to the sub-control unit 180. If the temperature rise of the battery packs 67 and 68 or the switching elements 152 and 153 exceeds an allowable range, the sub-control unit 180 stops operation.

[0098] In the operation panel unit 196 of Figure 10, the display panel 191 is a display unit that displays various information from the main control unit 140. The operation button 192 is a switch that instructs the air compressor 1 to start or stop operation. The charge button 193 is a switch that instructs the battery packs 67, 68 to be allowed to charge or to stop charging. The mode switching button 194 is a switch that switches the operation mode of the air compressor 1. The assist button 195 is a switch that switches between a mode that uses power assist with the battery pack and a mode that does not use power assist.

[0099] 9 to 12, the air compressor 1 is used while connected to a commercial power supply 139 (100V AC). Since the main circuit section 200 receives power from the commercial power supply 139, it is controlled by the main control section 140 based on the value of the AC side load current detection section 137 so that the input current from the commercial power supply 139 is 15 A or less. This is because the maximum rated current of an AC outlet is generally 15 A.

[0100] During normal operation, if the AC load current value is about to exceed 15 A, the main control unit 140 lowers the target rotation speed of the motor 14. The target rotation speed also varies depending on the load on the inverter unit 133 and the pressure inside the tank 50. Specifically, the target rotation speed is set high when the load is light, and low when the pressure inside the tank is increasing or when a large amount of compressed air is being used.

[0101] During power assist by operating the assist power supply unit 150, the AC current value drops when the target rotation speed is reached, so the main control unit 140 increases the target rotation speed so as to maintain the AC load current value of 15 A, thereby making it possible to supply insufficient power from one or both of the battery packs 67, 68. At this time, the sub-control unit 180 applies restrictions to the supply current or power from the battery packs 67, 68, thereby keeping the rotation speed of the motor 14 within a certain range.

[0102] Here, the following point should be noted. The AC-side power supply boost circuit 132 performs feedback control so that the boost voltage reaches a target value. However, if the series diode 323A is not inserted, and particularly if the assist voltage from the assist power supply unit 150 is too high, the boost voltage will be controlled to be lowered. If the boost voltage drops, the current supply from the commercial power supply 139 will decrease, causing the current supply from the battery packs 67, 68 to become excessive, ultimately leading to a reduction in the power assist time. In this case, the series diode 323A can be omitted if the assist output voltage (the output voltage of the assist power supply unit 150) is controlled to be approximately the same as the forward voltage drop (1 V to 2 V) of the series diode 182.

[0103] On the other hand, when the series diode 323A is inserted, it is necessary to provide a voltage junction electrolytic capacitor 324A at the point where the boost voltage and the assist voltage are connected. This is to absorb the surge energy that occurs when the motor 14 is stopped, and a large-capacity, high-voltage-resistant capacitor is used. However, when the series diode 323A is omitted as described above, it can be substituted by the electrolytic capacitor 324 of the AC-side power supply boost circuit 132, so the voltage junction electrolytic capacitor can also be omitted. This not only reduces the area on the board and the cost of electronic components, but also improves efficiency reductions due to diode loss and voltage drop.

[0104] Generally, when multiple battery packs are connected in parallel, reverse current prevention diodes 148 and 149, shown by dotted lines in Figure 11, are required to prevent reverse current between the battery packs. However, by alternately charging the battery packs 67 and 68 so that the potential difference between them is within a predetermined potential difference value (e.g., 0.5 V), it is possible to practically suppress the reverse current between the battery packs to the same level as the charging current. For this reason, diodes 148 and 149 may be omitted. This eliminates the problems of output reduction due to the resistance of diodes 148 and 149 and heat generation due to diodes 148 and 149.

[0105] Even if the potential difference between the battery packs 67, 68 exceeds a predetermined potential difference value (0.5 V) during power assist when the battery packs 67, 68 are connected in parallel, the assist continues until the battery voltage of one of the battery packs falls below the assist stop voltage V1.

[0106] If an attempt is made to stop assisting only one of the battery packs 67, 68 during the power assist period, the discharge current of the other battery pack 67, 68 will become excessively large at the same time as the stop, so it is necessary to reduce the current value, for example by lowering the target rotation speed of the motor 14. To actually stop the battery pack, it is necessary to turn off relay 188 or 189 while it is energized. From the perspective of preventing contact failure, it is best to stop the assist itself when the voltage of one battery falls below the assist stop voltage V1. The reason for this is that if an attempt is made to continue assisting until the voltage of both batteries falls below the assist stop voltage V1, the battery pack whose voltage drops first will consume more current, accelerating the voltage drop and heat generation, and slowing down the recharge and re-assist cycle.

[0107] The charging and discharging of the battery packs 67, 68 in the air compressor 1 will be described below.

[0108] Fig. 13 is a circuit block diagram related to charging and discharging of battery packs 67, 68 in air compressor 1. A charging and discharging circuit 400 in Fig. 13 is an example of a circuit section, and corresponds to the entire circuit in air compressor 1 other than battery packs 67, 68 and battery pack connecting sections 47, 48 in Fig. 9.

[0109] Each of the battery packs 67 and 68 is an example of a first power supply device that can switch the inter-terminal voltage between a first voltage value and a second voltage value. Hereinafter, as an example, the first voltage value is 36 V and the second voltage value is 18 V. The battery packs 67 and 68 have the same configuration.

[0110] The battery pack connectors 47, 48 and battery packs 67, 68 of the air compressor 1 each have an upper C+ terminal, a lower C+ terminal, an upper + terminal, a lower + terminal, an upper - terminal, and a lower - terminal. Terminals with the same names on the battery pack connector 47 and the battery pack 67 are connected to each other. Terminals with the same names on the battery pack connector 48 and the battery pack 68 are connected to each other. The inter-terminal voltage of the battery packs 67, 68 is the voltage between the upper C+ terminal and the upper + terminal and the lower - terminal. Each terminal of the battery pack connectors 47, 48 is an example of a connector terminal set.

[0111] Each of the battery packs 67, 68 has 18V battery cell sets 211, 212, and when the battery cell sets 211, 212 are connected in series to each other depending on the configuration of the connected device, the inter-terminal voltage becomes a first voltage value (36V), and when the battery cell sets 211, 212 are connected in parallel to each other depending on the configuration of the connected device, the inter-terminal voltage becomes a second voltage value (18V).

[0112] The positive electrode of the battery cell set 211 is connected to the upper C+ terminal and the upper + terminal. The negative electrode of the battery cell set 211 is connected to the upper - terminal. The positive electrode of the battery cell set 212 is connected to the lower C+ terminal and the lower + terminal. The negative electrode of the battery cell set 212 is connected to the lower - terminal.

[0113] Although not shown in the figure, a 36V input power tool has a shorting bar (short-circuiting member) that shorts the lower + terminal and upper - terminal of the connected battery pack 67 (or 68), and is configured so that the 36V that appears between the upper + terminal and the lower - terminal is used as the input voltage.

[0114] On the other hand, the charger has a terminal structure that shorts the upper C+ terminal and the lower C+ terminal of the connected battery pack 67 (or 68) and shorts the upper - terminal and the lower - terminal, and is configured to set the inter-terminal voltage to 18 V. This allows the charger to charge the battery packs 67, 68 with the same circuit configuration as a battery pack with an inter-terminal voltage fixed at 18 V (hereinafter referred to as an "18 V battery pack").

[0115] The air compressor 1 has 18 / 36V switching circuits 121, 122 between the battery packs 67, 68 and the charge / discharge circuit 400. The 18 / 36V switching circuits 121, 122 are circuits that can switch between a first state in which the terminal voltage of the battery packs 67, 68 is a first voltage value (36V) and a second state in which the terminal voltage of the battery packs 67, 68 is a second voltage value (18V).

[0116] The 18 / 36V switching circuits 121, 122 have switches 123 to 125. The switches 123 to 125 are configured by, for example, semiconductor switching elements or relays. The on / off of the switches 123 to 125 is controlled by the charge / discharge circuit 400 (for example, controlled by the sub-control unit 180 described above).

[0117] A switch 123 is provided between the upper C+ terminal and the lower C+ terminal. A switch 124 is provided between the lower + terminal and the upper - terminal. A switch 125 is provided between the upper - terminal and the lower - terminal.

[0118] Switches 123 and 125 are turned off when charging battery packs 67 and 68 and turned on when discharging battery packs 67 and 68. Switch 124 is turned on when charging battery packs 67 and 68 and turned off when discharging battery packs 67 and 68. As a result, the terminal voltage of battery packs 67 and 68 is 18 V when charging and 36 V when discharging.

[0119] The charge / discharge circuit 400 has a charge + terminal that applies a charge voltage to the upper C+ terminals of the battery packs 67, 68, a battery voltage monitor terminal that monitors the voltage of the upper C+ terminals of the battery packs 67, 68, a discharge + terminal to which a discharge voltage is input from the upper + terminals of the battery packs 67, 68, an 18V connection signal output terminal that applies an ON signal to switches 123, 125 during charging, a 36V connection signal output terminal that applies an ON signal to switch 124 during discharging, an upper bank - side voltage monitor terminal that monitors the voltage of the upper - terminals of the battery packs 67, 68, and a - terminal that is connected to the lower - terminals of the battery packs 67, 68.

[0120] 14 is a circuit block diagram in which battery packs 67 and 68 in FIG. 13 are replaced with battery pack 69. Battery pack 69 is an 18V battery pack and is an example of a second power supply device whose inter-terminal voltage is the second voltage value (18V). Battery pack 69 can also be connected to battery pack connectors 47 and 48.

[0121] The battery pack 69 has a C+ terminal, a + terminal, and a - terminal. The C+ terminal is connected to the upper C+ terminal of the battery pack connectors 47, 48. The + terminal is connected to the upper + terminal of the battery pack connectors 47, 48. The - terminal is connected to the lower - terminal of the battery pack connectors 47, 48.

[0122] The battery pack 69 has 18V battery cell pairs 213 and 214 connected in parallel to each other. The positive electrodes of the battery cell pairs 213 and 214 are connected to the C+ terminal and the + terminal. The negative electrodes of the battery cell pairs 213 and 214 are connected to the - terminal. When the battery pack 69 is connected to the battery pack connectors 47 and 48, all of the switches 123 to 125 are turned off.

[0123] 15 is a circuit block diagram in which battery packs 67 and 68 in FIG. 13 are replaced with battery pack 74. Battery pack 74 is a battery pack with a fixed inter-terminal voltage of 36 V (hereinafter referred to as "36 V battery pack") and is an example of a second power supply device with an inter-terminal voltage of the first voltage value (36 V). Battery pack 74 can also be connected to battery pack connectors 47 and 48.

[0124] The battery pack 74 has a C+ terminal, a + terminal, and a - terminal. The C+ terminal is connected to the upper C+ terminal of the battery pack connectors 47, 48. The + terminal is connected to the upper + terminal of the battery pack connectors 47, 48. The - terminal is connected to the lower - terminal of the battery pack connectors 47, 48.

[0125] The battery pack 74 has a 36V battery cell set 215. The positive electrode of the battery cell set 215 is connected to the C+ terminal and the + terminal. The negative electrode of the battery cell set 215 is connected to the - terminal. When the battery pack 74 is connected to the battery pack connectors 47 and 48, all of the switches 123 to 125 are turned off.

[0126] 16 is a flowchart of charge / discharge control in the air compressor 1. The user connects a battery pack to at least one of the battery pack connectors 47, 48 (S1). The sub-controller 180 communicates with the battery pack connected to at least one of the battery pack connectors 47, 48 (hereinafter referred to as the "connected battery pack") and determines the type of the connected battery pack, i.e., the rated voltage, etc. (S3).

[0127] If the motor 14 is operating (Yes in S5), the sub-controller 180 stops or keeps the charging by the charge / discharge circuit 400 stopped (S7), and enters or keeps the discharging mode (S9).

[0128] If the connected battery pack is capable of discharging at 36V (hereinafter referred to as "36V dischargeable battery pack") (Yes in S10), the sub-controller 180 switches the switches 123-125 to or maintains them for 36V discharge (S11) and permits discharge from the connected battery pack (S15). If the discharge flag is "H" (Yes in S17), the sub-controller 180 discharges the connected battery pack (S19). If the discharge flag is not "H" (No in S17), the sub-controller 180 stops or maintains the stopped state of discharge from the connected battery pack (S23). The discharge flag is set to "H" if no abnormality such as over-discharge or high temperature is detected, and is set to "L" if an abnormality is detected.

[0129] If the connected battery pack is not a 36V dischargeable battery pack (No in S10), the sub-controller 180 prohibits discharge (S21) and stops or maintains the stopped state of discharge from the connected battery pack (S23). Note that battery packs 67, 68, and 74 are examples of battery packs capable of discharging 36V. Battery pack 69 is an example of a battery pack that is not a 36V dischargeable battery pack.

[0130] If the motor 14 is not operating (No in S5), the sub-controller 180 stops or keeps the discharge from the connected battery pack stopped (S27), and enters or keeps the charging mode (S29).

[0131] If the connected battery pack is a battery pack that can be charged at 18V (hereinafter referred to as "18V rechargeable battery pack") (Yes in S30), the sub-controller 180 switches the switches 123-125 to or maintains the 18V charging mode (S31) and permits charging of the connected battery pack (S35). If the connected battery pack is fully charged (Yes in S37), the sub-controller 180 stops or maintains charging of the connected battery pack in a stopped state (S39). If the connected battery pack is not fully charged (No in S37), the sub-controller 180 charges the connected battery pack (S41).

[0132] If the connected battery pack is not an 18V rechargeable battery pack (No in S30), the sub-controller 180 prohibits charging (S43). Note that battery packs 67, 68, and 69 are examples of 18V rechargeable battery packs. Battery pack 74 is an example of a battery pack that is not an 18V rechargeable battery pack. Battery packs 67 and 68 are 36V dischargeable battery packs and 18V rechargeable battery packs, and will be referred to as "18 / 36V switchable battery packs" below.

[0133] The above-described circuit configuration and charge / discharge control of the air compressor 1 provide the following advantageous effects.

[0134] (1) When the connected battery pack is an 18 / 36V switchable battery pack, the charge / discharge circuit 400 allows discharging from the connected battery pack to the motor 14 and charging the connected battery pack. When the connected battery pack is an 18V battery pack, the charge / discharge circuit 400 prohibits discharging from the connected battery pack to the motor 14 and allows charging to the connected battery pack. When the connected battery pack is a 36V battery pack, the charge / discharge circuit 400 allows discharging from the connected battery pack to the motor 14 and prohibits charging to the connected battery pack. Therefore, the charge / discharge circuit 400 is configured to change the inter-terminal voltage of the connected battery pack when discharging and charging the connected battery pack, allowing appropriate charging and discharging of the 18 / 36V switchable battery pack, while also being able to charge the 18V battery pack and discharge from the 36V battery pack, resulting in good operability.

[0135] (2) The air compressor 1 can be switched between a first state in which the terminal voltage of the battery packs 67, 68 is a first voltage value (36 V) and a second state in which the terminal voltage of the battery packs 67, 68 is a second voltage value (18 V) by the 18 / 36 V switching circuits 121, 122. This allows the battery packs 67, 68, which are 18 / 36 V switchable battery packs, to be appropriately charged and discharged.

[0136] (3) The 18 / 36V switching circuits 121, 122 switch between the first state and the second state by switching the connection state between each terminal (connection terminal set) of the battery pack connectors 47, 48 and the charge / discharge circuit 400. Therefore, the 18 / 36V switching circuits 121, 122 can appropriately switch between the first state and the second state for battery packs 67, 68 of a type in which the inter-terminal voltage switches between a first voltage value (36V) and a second voltage value (18V) depending on the terminal configuration of the connected device.

[0137] 17(A) to 17(D) relate to a work machine according to another embodiment of the present invention. The following mainly describes the differences from the above-described embodiment. Battery pack 75 is a type in which the inter-terminal voltage switches between a first voltage value (36 V) and a second voltage value (18 V) depending on the state of its internal circuitry.

[0138] The battery pack 75 has a switching member 128. The switching member 128 switches its state as shown in Figures 17(A) and 17(B) when engaged with the device to which it is connected. This switches the interconnection of the battery cell pairs 217 and 218 of the battery pack 75 between a series connection and a parallel connection as shown in Figures 17(C) and 17(D), and switches the inter-terminal voltage between a first voltage value (36 V) and a second voltage value (18 V).

[0139] 17(A) and 17(B) when the battery pack 75 is being charged or discharged, the work machine has solenoid actuators 126 and 127 as switching units, and the solenoid actuators 126 and 127 switch the state of a switching member 128 (switch the internal circuit of the battery pack 75) as shown in Figures 17(A) and 17(B) when the battery pack 75 is being charged or discharged, switching between a first state in which the voltage across the terminals of the battery pack 75 is a first voltage value (36 V) and a second state in which the voltage across the terminals of the battery pack 75 is a second voltage value (18 V). The solenoid actuators 126 and 127 are members that replace the switches 123 to 125 in Figure 13.

[0140] According to another embodiment, the solenoid actuators 126, 127 switch between the first state and the second state by switching the internal circuit of the battery pack 75. Therefore, the switching between the first state and the second state can be appropriately performed for a battery pack 75 of a type in which the inter-terminal voltage switches between a first voltage value (36 V) and a second voltage value (18 V) depending on the state of its own internal circuit.

[0141] While the present invention has been described above using the embodiments as examples, it will be understood by those skilled in the art that various modifications can be made to the components and processes of the embodiments within the scope of the claims. Modifications will be discussed below.

[0142] The number of battery pack connection parts that a work machine has is not limited to two, and may be one, or three or more. The work machine is not limited to an air compressor, and may be any work machine that is capable of discharging from and charging a battery pack. The first voltage value and second voltage value, the voltage and number of battery cell sets, and the like, which are given as specific numerical values ​​in the embodiments, do not in any way limit the scope of the invention and can be changed as desired to suit the required specifications.

[0143] Alternatively, the first power supply device may be a 36V battery pack whose terminal voltage cannot be switched from a first voltage value (36V), and the second power supply device may be an 18V battery pack whose terminal voltage cannot be switched from a second voltage value (18V), and the circuit unit may be configured to allow power consumption by the load unit when a 36V battery pack is connected to the first connection unit, and to only allow charging and prohibit power consumption when an 18V battery pack is connected. [Explanation of symbols]

[0144] 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, 47, 48...Battery pack connection section (first connection section), 49...Commercial power supply connection section (second connection section), 50, 51, 52, 53, 54...Tank, 50a, 50b...End wall, 50c...Side wall , 61...coupler, 62...pressure reducing valve, 64,65...connecting portion, 67,68,69...battery pack (battery), 70...drain discharge mechanism, 71...drain suction pipe, 74,75...battery pack (battery)<80...leg portion, 81,84...mounting portion, 82...fixing portion, 83...rubber foot, 85...fixing member, 121,122...18 / 36V switching circuit, 123~125...switch, 126,127...solenoid actuator, 400...charge / discharge circuit (circuit portion).

Claims

1. a first connection portion to which a first power supply device is connected, the first power supply device having a first voltage value across its terminals during discharging and a second voltage value across its terminals during charging; a second connection portion that is connected to a commercial power source and receives power; a circuit portion connected to the first connection portion and the second connection portion, The circuit unit includes: a load unit capable of consuming the power input to the first connection unit; a charging unit capable of outputting power input from the second connection unit to the first connection unit, a switching unit that can switch between a first state in which the voltage across the terminals of the first power supply device is the first voltage value and a second state in which the voltage across the terminals of the first power supply device is the second voltage value.

2. the first connection unit is selectively connected to the first power supply device and a second power supply device whose inter-terminal voltage is either the first voltage value or the second voltage value regardless of whether the first power supply device is being discharged or charged; The circuit unit includes: When the first power supply device is connected to the first connection section, consumption of the power input to the first connection section by the load section and output of the power by the charging section are permitted; 2. The work machine according to claim 1, wherein when the second power supply device is connected to the first connection portion, either consumption of the power input to the first connection portion by the load portion or output of the charging portion is prohibited.

3. The work machine according to claim 2 , wherein the circuit unit inhibits output from the charging unit when the second power supply device is connected to the first connection unit.

4. the voltage across the terminals of the second power supply device is a first voltage value; The work machine according to claim 3 , wherein the first voltage value is greater than the second voltage value.

5. the first connection portion has a connection portion terminal set that is connected to a terminal set of the first power supply device, The work machine according to claim 1 , wherein the switching unit switches between the first state and the second state by switching a connection state between the connection terminal set and the circuit unit.

6. The work machine according to claim 1 , wherein the switching unit switches between the first state and the second state by switching an internal circuit of the first power supply device.

7. a first connection section to which a first power supply device capable of switching an inter-terminal voltage between a first voltage value and a second voltage value and a second power supply device whose inter-terminal voltage is either the first voltage value or the second voltage value are alternatively connected to receive power; a second connection portion that is connected to a commercial power source and receives power; a circuit portion connected to the first connection portion and the second connection portion, The circuit unit includes: a load unit capable of consuming the power input to the first connection unit; a charging unit capable of outputting power input from the second connection unit to the first connection unit, The circuit unit includes: When the first power supply device is connected to the first connection section, consumption of the power input to the first connection section by the load section and output of the power by the charging section are permitted; A work machine that, when the second power supply device is connected to the first connection section, prohibits either consumption by the load section of the power input to the first connection section or output by the charging section.

8. a first power supply device capable of switching a terminal voltage between a first voltage value and a second voltage value; a second power supply device whose inter-terminal voltage is either the first voltage value or the second voltage value; A work machine, The work machine is a first connection section to which the first power supply device and the second power supply device are selectively connected and to which power is input; a second connection portion that is connected to a commercial power source and receives power; a circuit portion connected to the first connection portion and the second connection portion, The circuit unit includes: a load unit capable of consuming the power input to the first connection unit; a charging unit capable of outputting power input from the second connection unit to the first connection unit, The circuit unit includes: When the first power supply device is connected to the first connection section, consumption of the power input to the first connection section by the load section and output of the power by the charging section are permitted; A work machine system that, when the second power supply device is connected to the first connection section, prohibits either consumption by the load section of the power input to the first connection section or output by the charging section.

9. a first connection section to which a first power supply device having a terminal voltage of a first voltage value and a second power supply device having a terminal voltage of a second voltage value are selectively connected and to which power is input; a second connection portion that is connected to a commercial power source and receives power; a circuit portion connected to the first connection portion and the second connection portion, The circuit unit includes: a load unit capable of consuming the power input to the first connection unit; a charging unit capable of outputting power input from the second connection unit to the first connection unit, The circuit unit includes: When the first power supply device is connected to the first connection section, power input to the first connection section is allowed to be consumed by the load section; When the second power supply device is connected to the first connection portion, the work machine prohibits the load portion from consuming the power input to the first connection portion and allows the charging portion to output the power.

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