JP2017057808A - air compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a cooling effect on objects to be cooled in an air compressor without upsizing a cooling fan.SOLUTION: An air compressor 1 comprises: a motor 20 comprising a stator 21, a rotor 22, and a motor rotating shaft 23 integrated with the rotor 22 and penetrating the rotor 22; and a cooling fan 70 provided on a protruding part of the motor rotating shaft 23 protruding from the rotor 22 to generate an air flow toward the motor 20. The cooling fan 70 includes: a centrifugal fan 80 integrated with the motor rotating shaft 23; and an axial fan 90 integrated with the centrifugal fan 80. The axial fan 90 is provided coaxially with the centrifugal fan 80 around the centrifugal fan 80, and surrounds the centrifugal fan 80.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an air compressor, and more particularly, to a reciprocating type air compressor.

  A reciprocating type air compressor includes a power source, a piston that is reciprocated by a driving force output from the power source, a cylinder that accommodates the piston so as to reciprocate, and a volume that changes as the piston reciprocates. ,including. An electric motor that outputs a rotational driving force may be used as the power source. In this case, the rotational driving force output from the electric motor is converted into a reciprocating driving force by a conversion mechanism and transmitted to the piston.

  When the piston in the cylinder moves from the top dead center to the bottom dead center, the volume of the cylinder increases, the inside of the cylinder becomes negative pressure, and air is introduced into the cylinder. The air introduced into the cylinder is compressed by the piston moving from the bottom dead center to the top dead center in the cylinder, and the pressure is increased. The compressed air (high pressure air) is sent to an air tank via a predetermined pipe and stored in the air tank.

  There is also a multistage air compressor including two or more sets of pistons and cylinders as described above. In such an air compressor, air compressed in one cylinder is sent to the other cylinder via a pipe and further compressed (Patent Document 1). That is, the air is compressed in stages.

JP2013-40586A

  During operation of the air compressor, the temperature of each part rises. For example, during operation of an air compressor, the temperature of pistons, cylinders, and their surroundings increases due to compression heat. Further, the temperature of the electric motor and the control circuit of the electric motor rises due to Joule heat caused by the load current. Thus, the air compressor includes a plurality of elements that increase in temperature during operation. Therefore, many air compressors include a cooling fan that supplies cooling air to an element (cooling target) whose temperature rises during operation.

  In order to increase the cooling effect on the object to be cooled, it is necessary to increase the air volume of the cooling air. However, if the size of the cooling fan is increased or the number of fans is increased, the air volume of the cooling air can be easily increased. However, an increase in the size and number of cooling fans leads to an increase in size and weight of the entire air compressor and an increase in cost. On the other hand, particularly in a portable small air compressor, the entire air compressor is required to be reduced in size and weight from the viewpoint of operator convenience.

  An object of the present invention is to enhance the cooling effect on the cooling object in the air compressor without increasing the size of the cooling fan.

  The air compressor of the present invention is an air compressor using an electric motor as a power source. The air compressor includes a stator, a rotor, an electric motor that is integrated with the rotor and includes a rotating shaft that passes through the rotor, and a piston that is coupled to the first protruding portion of the rotating shaft that protrudes from the rotor. A cylinder that accommodates the piston in a reciprocable manner, and a cooling fan that is provided in a second projecting portion that projects in a direction opposite to the first projecting portion from the rotor and that generates an airflow toward the electric motor. Have. The cooling fan includes a centrifugal fan and an axial fan provided on the second protrusion, and the axial fan is provided around the centrifugal fan and coaxially with the centrifugal fan and surrounds the centrifugal fan. Yes.

  In one aspect of the present invention, the centrifugal fan and the axial fan are integrated.

  In another aspect of the present invention, the centrifugal fan has a plurality of fins arranged at a predetermined pitch along the rotation direction and facing the rotor.

  In another aspect of the present invention, a partition plate for partitioning each fin in the direction of the rotation axis is provided, and each fin is positioned closer to the electric motor than the partition plate by the partition plate. It is divided into an inner fin part and an outer fin part located on the opposite side to the inner fin part across the partition plate.

  In another aspect of the present invention, a fan guide including a motor-side opening facing the electric motor and an anti-motor-side opening located on the opposite side of the motor-side opening is provided around the fin. It is done. The diameter of the non-motor side opening is smaller than the diameter of the motor side opening.

  In another aspect of the invention, the stator is more likely to pass air in the direction of the rotation shaft than the rotor.

  In another aspect of the present invention, an air flow path penetrating the stator in the direction of the rotation shaft is provided between the inner peripheral surface and the outer peripheral surface of the stator.

  In another aspect of the present invention, the air flow path in the stator is provided between stator coils wound around adjacent teeth of the stator.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling effect with respect to the cooling target object in an air compressor can be heightened, without enlarging a cooling fan.

It is a perspective view of an air compressor. It is a horizontal sectional view of an air compressor. It is a perspective view of a cooling fan. It is another perspective view of a cooling fan. It is an expanded sectional view of a cooling fan. It is sectional drawing which shows typically the air flow produced | generated by a cooling fan. It is sectional drawing of an electric motor.

  Hereinafter, an example of an embodiment of an air compressor of the present invention is explained. The air compressor according to the present embodiment is a reciprocating type air compressor including a compressed air generating unit that uses an electric motor (hereinafter referred to as “motor”) as a power source. The application of the air compressor according to the present embodiment is not particularly limited, but is suitable for use as a supply source for supplying compressed air to an air tool for driving nails or screws into wood or the like by the pressure of compressed air. Hereinafter, the air compressor according to the present embodiment will be described in detail with reference to the drawings.

  As shown in FIG. 1, the air compressor 1 has a base 11 including a skeleton such as a frame and two air tanks 10 a and 10 b that are connected to the skeleton and are parallel to each other. Legs 12 are attached to the lower surfaces of both end portions of each of the air tanks 10 a and 10 b, and the air compressor 1 is placed at a desired installation location by the four legs 12. Moreover, the handle | steering-wheel 13 is provided in the both ends of the base 11, and the operator can hold the handle | steering-wheel 13 and can carry the air compressor 1 in it.

  The base 11 is mounted with the motor 20 shown in FIG. 2 and a compressed air generation unit 30 using the motor 20 as a power source. Usually, the motor 20 and the compressed air generation part 30 are covered with the cover 14 shown by FIG. Referring to FIG. 2 again, the compressed air generation unit 30 includes a crankcase 40 and two cylinders (a first cylinder 51a and a second cylinder 51b).

  The motor 20 includes a stator 21, a rotor 22 incorporated inside the stator 21, a rotating shaft (motor rotating shaft) 23 integrated with the rotor 22, a hall element that detects the rotational position of the rotor 22, and the like. A DC brushless motor, which is disposed outside the crankcase 40. However, the motor 20 is fixed to one cover (first crankcase cover 40 a) of the crankcase 40 and integrated with the crankcase 40.

  The motor rotating shaft 23 penetrates the rotor 22 and protrudes on both axial sides of the rotor 22. The first protrusion 23 a that protrudes to one axial side of the rotor 22 passes through the crankcase 40 and is rotatably supported by a bearing provided in the crankcase 40. Specifically, the first protrusion 23a of the motor rotating shaft 23 passes through the first crankcase cover 40a and the other cover (second crankcase cover 40b) of the crankcase 40 facing the first crankcase cover 40a. The bearings 40a and 40b are rotatably supported by bearings.

  A control circuit board 60 on which a semiconductor switching element for controlling the inverter of the motor 20 is mounted is disposed on the opposite side of the crankcase 40 from the motor 20. The control circuit board 60 is disposed so as to face the second crankcase cover 40b, and is fixed to the air tank 10b. A cooling fan 61 is disposed between the control circuit board 60 and the crankcase 40 (second crankcase cover 40b), and the control circuit board 60 is cooled by the airflow (cooling air) generated by the cooling fan 61. The The cooling fan 61 is fixed to the end of the first protrusion 23a protruding from the second crankcase cover 40b, and rotates integrally with the motor rotating shaft 23 to generate cooling air.

  A first cylinder 51 a and a second cylinder 51 b are attached to both sides of the crankcase 40. The first cylinder 51a and the second cylinder 51b are arranged at positions different by 180 degrees with respect to the rotation direction of the motor rotating shaft 23. The first piston 52a is accommodated in the first cylinder 51a so as to be able to reciprocate. A second piston 52b is accommodated in the cylinder 51b so as to reciprocate.

  In order to convert the rotational movement of the motor rotating shaft 23 into the reciprocating movement of the first piston 52a, one end of the first connecting rod 53a is pin-coupled to the first piston 52a, and the other end of the first connecting rod 53a. Are rotatably coupled to an eccentric cam mounted on the motor rotating shaft 23 (first projecting portion 23a). That is, the first connecting rod 53a straddles the crankcase 40 and the first cylinder 51a and connects the motor rotating shaft 23 and the first piston 52a. Further, in order to convert the rotational movement of the motor rotating shaft 23 into the reciprocating movement of the second piston 52b, one end of the second connecting rod 53b is pin-coupled to the second piston 52b, and the second connecting rod 53b The other end is rotatably coupled to another eccentric cam mounted on the motor rotating shaft 23 (first projecting portion 23a). That is, the second connecting rod 53b straddles the crankcase 40 and the second cylinder 51b and connects the motor rotating shaft 23 and the second piston 52b. Therefore, in the following description, the motor rotation shaft 23 may be referred to as “crankshaft 23”. The rotational driving force output from the motor 20 is converted into a reciprocating driving force by a conversion mechanism including a crankshaft 23, an eccentric cam, and a connecting rod (first connecting rod 53a, second connecting rod 53b), and a piston (first piston). 52a and the second piston 52b).

  Here, the respective eccentric cams are eccentric in opposite directions with respect to the driving directions of the pistons 52a and 52b. Therefore, when the first piston 52a is driven in the direction of compressing the upper chamber of the first cylinder 51a, the second piston 52b is driven in the direction of expanding the upper chamber of the second cylinder 51b. On the other hand, when the second piston 52b is driven in the direction of compressing the upper chamber of the second cylinder 51b, the first piston 52a is driven in the direction of expanding the upper chamber of the first cylinder 51a. The upper chambers of the cylinders 51a and 51b are spaces above the pistons 52a and 52b in the cylinders 51a and 51b.

  Buffer chambers 55a and 55b are provided inside the cylinder heads 54a and 54b provided in the respective cylinders 51a and 51b, and between the upper chambers of the cylinders 51a and 51b and the buffer chambers 55a and 55b. Each has a check valve. When the first piston 52a is driven in a direction to compress the upper chamber of the first cylinder 51a and the pressure of the air in the upper chamber becomes higher than a predetermined pressure, the first piston 52a is located between the upper chamber of the first cylinder 51a and the buffer chamber 55a. Check valve is opened. Then, the air compressed by the first piston 52a is sent to the upper chamber of the second cylinder 51b through the first pipe 56 that connects the first cylinder 51a and the second cylinder 51b. In addition, the 1st piping 56 in this embodiment is a metal pipe.

  When the second piston 52b is driven in a direction to compress the upper chamber of the second cylinder 51b and the pressure of the air in the upper chamber becomes higher than a predetermined pressure, the second piston 52b is located between the upper chamber of the second cylinder 51b and the buffer chamber 55b. Check valve is opened. Then, the air compressed by the second piston 52b is sent and stored in the air tank 10a through a second pipe (not shown) that connects the second cylinder 51b and the air tank 10a. The air tanks 10 a and 10 b communicate with each other via the third pipe 58. Therefore, the pressure in the air tanks 10a and 10b is kept uniform. In addition, the 2nd piping and the 3rd piping 58 in this embodiment are metal pipes.

  Here, outside air is introduced into the upper chamber of the first cylinder 51a shown in FIG. That is, the first piston 52a compresses the outside air, and the second piston 52b further compresses the outside air (air) compressed by the first piston 52a. In other words, the first piston 52a is a first-stage low-pressure piston, and the second piston 52b is a second-stage high-pressure piston. The first cylinder 51a is a first-stage low-pressure cylinder, and the second cylinder 51b is a second-stage high-pressure cylinder. Thus, the air compressor 1 according to the present embodiment compresses air in two stages. Specifically, compressed air of about 1.0 [MPa] is generated by the first piston 52a, and compressed air of about 4.0 to 4.5 [MPa] is generated by the second piston 52b.

  As shown in FIG. 1, couplers 15a and 15b, which are outlets for compressed air, are provided above the ends of the air tanks 10a and 10b. Further, pressure reducing valves 16a and 16b for adjusting the pressure of the compressed air are provided between the air tanks 10a and 10b and the couplers 15a and 15b, respectively. The pressure of the compressed air adjusted by the pressure reducing valves 16a and 16b is measured and displayed by pressure gauges 17a and 17b installed in the vicinity of the pressure reducing valves 16a and 16b.

  As shown in FIG. 2, the air tank 10a is provided with a safety valve 18a that automatically opens when the pressure in the air tanks 10a and 10b becomes higher than a predetermined pressure. On the other hand, the air tank 10b is provided with a drain device 18b. When the drain device 18b is operated, the compressed air and moisture in the air tanks 10a and 10b are discharged. As shown in FIG. 1, an operation panel 19 is provided on the upper surface of the cover 14, and a start command for the motor 20 (FIG. 2) is provided via an input unit (not shown) provided on the operation panel 19. And the rotation speed is input.

  Here, during the operation of the air compressor 1, a load current is generated in the motor 20 which is a driving source of the pistons 52a and 52b. Therefore, the temperature of the motor 20 rises due to Joule heat accompanying the load current. Further, the temperatures of the cylinders 51a and 51b and the pistons 52a and 52b rise due to the compression heat generated in the compression process. Further, as the temperature of the motor 20 and the cylinders 51a and 51b increases, the temperature of the crankcase 40 in contact with them also increases. Therefore, in order to avoid overheating of the motor 20 and the compressed air generation unit 30 (the crankcase 40, the cylinders 51a and 51b, the pistons 52a and 52b, etc.), it is necessary to cool them.

  Therefore, as shown in FIG. 2, a cooling fan 70 is installed on the opposite side of the crankcase 40 across the motor 20. As described above, the cooling fan 61 for mainly cooling the control circuit board 60 is fixed to the other end of the crankshaft 23. That is, in this embodiment, the cooling fan 61 is provided at one end of the crankshaft 23 and the cooling fan 70 is provided at the other end. In other words, the motor 20 and the compressed air generating unit 30 (the crankcase 40, the cylinders 51a and 51b, the pistons 52a and 52b, etc.) are arranged between the two cooling fans 61 and 70 facing each other.

  The cooling fan 70 is fixed to the end of the second protrusion 23 b of the motor rotation shaft 23 that protrudes in the opposite direction from the first protrusion 23 a from the rotor 22 of the motor 20, and is integrated with the motor rotation shaft 23. Yes. When the cooling fan 70 rotates, an airflow (cooling air) directed toward the motor 20 is generated, and the motor 20 and the compressed air generating unit 30 (the crankcase 40, the cylinders 51a and 51b, the pistons 52a and 52b, etc.) are cooled by the cooling air. The

  3 and 4 are different perspective views of the cooling fan 70. FIG. 3 is a perspective view of the cooling fan 70 as viewed from the motor 20 (FIG. 2) side. On the other hand, FIG. 4 is a perspective view of the cooling fan 70 viewed from the side opposite to the motor 20 (FIG. 2).

  As shown in FIGS. 3 and 4, the cooling fan 70 includes two types of multiblade fans provided coaxially. Specifically, the cooling fan 70 includes a centrifugal fan 80 and an axial fan 90. The axial fan 90 is provided around the centrifugal fan 80 and surrounds the centrifugal fan 80. That is, the axial fan 90 is provided on the radially outer side of the centrifugal fan 80, and the centrifugal fan 80 is provided on the radially inner side of the axial fan 90.

  At the center of the centrifugal fan 80, a mounting hole 81 into which the second protrusion 23b (FIG. 2) of the motor rotating shaft 23 is inserted is formed. In the present embodiment, the centrifugal fan 80 is fixed to the end of the second projecting portion 23b inserted into the mounting hole 81 and integrated with the second projecting portion 23b. And integrated. That is, the cooling fan 70 is integrated with the second protrusion 23 b of the motor rotation shaft 23. However, it is only necessary that the cooling fan 70 rotates with the rotation of the motor rotation shaft 23, and it is not essential that the cooling fan 70 is integrated with the motor rotation shaft 23 (second projecting portion 23b). It is not essential that the fan 80 and the axial fan 90 are integrated.

  The centrifugal fan 80 includes a plurality of fins 82 arranged at a predetermined pitch along the rotation direction. As shown in FIG. 5, these fins 82 face the motor 20, and more specifically, face the rotor 22 of the motor 20.

  As shown in FIGS. 3 and 4, the centrifugal fan 80 includes a disk-shaped partition plate 83 in addition to the fins 82. As shown in FIG. 5, the partition plate 83 partitions each fin 82 in the direction of the motor rotation shaft 23. Specifically, each fin 82 is divided by a partition plate 83 into an inner fin portion 82a positioned on the motor side of the partition plate 83 and an outer side positioned on the opposite side of the inner fin portion 82a across the partition plate 83. It is divided into fin portions 82b. The mounting hole 81 is formed at the center of the partition plate 83.

  As shown in FIGS. 3 and 4, a fan guide 84 surrounding the fins 82 of the centrifugal fan 80 is provided around the fins 82. A part of each fin 82 is connected to the partition plate 83, and the other part is connected to the inner peripheral surface of the fan guide 84. In other words, the partition plate 83 and the fan guide 84 are connected to each other via the plurality of fins 82. In other words, the fan guide 84 is supported from the inside by a plurality of fins 82.

  As shown in FIG. 5, the fan guide 84 has a substantially cylindrical shape, a motor side opening 84a facing the motor 20, a counter motor side opening 84b located on the opposite side of the motor side opening 84a, It has. The diameter of the non-motor side opening 84b is smaller than the diameter of the motor side opening 84a.

  As shown in FIGS. 3 and 4, the plurality of fins 91 constituting the axial fan 90 are arranged on the outer peripheral surface of the fan guide 84 at a predetermined pitch. That is, the fan guide 84 also functions as a base member on which the fins 91 constituting the axial flow fan 90 are mounted. In the present embodiment, the fan guide 84 that also functions as a base member is supported by a large number of fins 82 from the inside thereof, and the strength of the fan guide 84 is enhanced.

  Here, the diameter of the non-motor side opening 84 b of the fan guide 84 is set smaller than the diameter of the partition plate 83. Thereby, the cooling fan 70 including the fin 82, the partition plate 83, the fan guide 84, and the fin 91 can be injection-molded with one mold.

  As shown in FIG. 6, when the cooling fan 70 rotates, a plurality of airflows are generated. In FIG. 6, each air flow generated with the rotation of the cooling fan 70 is schematically shown by arrows. When the cooling fan 70 rotates, the axial flow fan 90 generates an air flow CA1 that mainly passes toward the cylinders 51a and 51b through the periphery of the motor 20. At the same time, an air flow CA2 mainly toward the stator 21 is generated by the outer fin portion 82b (FIG. 5) of the centrifugal fan 80. Furthermore, the air flow CA3 mainly toward the rotor 22 is generated by the inner fin portion 82a (FIG. 5) of the centrifugal fan 80.

  Please refer to FIG. Of the space between the motor 20 and the centrifugal fan 80 facing each other, the flow resistance of the airflow in the region R1 inside the inner peripheral surface of the stator 21 is the region between the inner peripheral surface and the outer peripheral surface of the stator 21. It is larger than the flow resistance of the airflow in R2. Here, the flow resistance is mainly a flow resistance in the direction of the motor rotating shaft 23. Specifically, as shown in FIG. 7, a plurality of air flow paths 24 penetrating the stator 21 in the direction of the motor rotation shaft 23 are provided between the inner peripheral surface 21 a and the outer peripheral surface 21 b of the stator 21. It has been. The air flow path 24 is provided between the stator coils 26 wound around the teeth 25 adjacent to the stator 21. In other words, the stator coil 26 is wound around each tooth 25 so that a gap serving as the air flow path 24 is formed. On the other hand, the rotor 22 is not provided with an air flow path corresponding to the air flow path 24. That is, the rotor 22 is not provided with a gap that penetrates the rotor 22 in the direction of the motor rotation shaft 23. For this reason, when the stator 21 and the rotor 22 are compared, the stator 21 is easier to pass air in the direction of the motor rotation shaft 23 than the rotor 22.

  As described above, the region R1 shown in FIG. 5 is a substantially closed space. For this reason, as shown in FIG. 6, the airflow CA3 becomes a vortex that rotates in the direction of accelerating the airflow CA2. As a result, the airflow CA2 passing through the air flow path 24 (FIG. 7) is accelerated by the airflow CA3, and the cooling effect of the stator 21 is enhanced. Further, since the region R1 is divided by the rotor 22 into the crankcase side and the cooling fan side, the cooling air whose temperature has risen through the air flow path 24 (FIG. 7) may be sucked into the cooling fan side. Absent. Therefore, there is no possibility that the temperature of the cooling air (air flow CA2) flowing into the air flow path 24 (FIG. 7) rises and the cooling effect of the stator 21 decreases.

  A plurality of wind windows 14 a are formed in a region of the cover 14 facing the cooling fan 70. A plurality of wind windows 14 b are also formed in a region of the cover 14 facing the cooling fan 61.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the air compressor 1 according to the above embodiment is a multistage air compressor including two sets of cylinders and pistons, but the cylinders and pistons may be one set or three or more sets.

DESCRIPTION OF SYMBOLS 1 Air compressor 10a, 10b Air tank 13 Handle 15a, 15b Coupler 16a, 16b Pressure reducing valve 17a, 17b Pressure gauge 20 Electric motor (motor)
21 Stator 21a Inner peripheral surface 21b Outer peripheral surface 22 Rotor 23 Motor rotating shaft (crankshaft)
23a 1st protrusion part 23b 2nd protrusion part 24 Air flow path 25 Teeth 26 Stator coil 30 Compressed air generation part 40 Crankcase 51a 1st cylinder 51b 2nd cylinder 52a 1st piston 52b 2nd piston 60 Control circuit boards 61 and 70 Cooling fan 80 Centrifugal fan 82 Fin 82a Inner fin portion 82b Outer fin portion 83 Partition plate 84 Fan guide 84a Motor side opening 84b Counter motor side opening 90 Axial fan 91 Fins CA1, CA2, CA3 Airflow

Claims (8)

An air compressor using an electric motor as a power source,
An electric motor that is integrated with a stator, a rotor, and the rotor, and includes a rotating shaft that penetrates the rotor;
A piston connected to the first protrusion of the rotating shaft protruding from the rotor;
A cylinder for accommodating the piston in a reciprocable manner;
A cooling fan that is provided in a second projecting portion that projects in the opposite direction to the first projecting portion from the rotor, and that generates an airflow toward the electric motor,
The cooling fan includes a centrifugal fan and an axial fan provided in the second protrusion,
The axial fan is provided coaxially with the centrifugal fan around the centrifugal fan and surrounds the centrifugal fan;
air compressor.   The air compressor according to claim 1, wherein the centrifugal fan and the axial fan are integrated. The centrifugal fan is arranged at a predetermined pitch along the rotation direction, and has a plurality of fins facing the rotor.
The air compressor according to claim 1 or 2. A partition plate that partitions each fin in the direction of the rotation axis;
Each of the fins is divided into an inner fin portion positioned on the electric motor side of the partition plate and an outer fin portion positioned on the opposite side of the inner fin portion with the partition plate interposed therebetween. Partitioned,
The air compressor according to claim 3. Around the fin, a fan guide is provided that includes a motor-side opening facing the electric motor and an anti-motor-side opening located on the opposite side of the motor-side opening,
The diameter of the non-motor side opening is smaller than the diameter of the motor side opening,
The air compressor according to claim 3 or 4. The stator is easier to pass air in the direction of the rotation shaft than the rotor.
The air compressor according to any one of claims 1 to 5. Between the inner peripheral surface and the outer peripheral surface of the stator, an air flow path that penetrates the stator in the direction of the rotating shaft is provided.
The air compressor according to claim 6. The air flow path in the stator is provided between stator coils wound around adjacent teeth of the stator,
The air compressor according to claim 7.

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