JP2017008777A - air compressor - Google Patents

Abstract

An object of the present invention is to reduce noise caused by contact between a piston and a cylinder and improve assembly without increasing the time and labor required for assembling the piston into the cylinder.
A reciprocating type air compressor, a cylinder 51a, a piston 52a reciprocating in the cylinder 51a, a rider ring 70a attached to the outer peripheral surface of the piston 52a and reciprocating integrally with the piston 52a, The annular elastic bodies 76 and 78 are provided between the rider ring 70a and the piston 52a.
[Selection] Figure 5

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

  Various sounds are generated during operation of the air compressor, one of which is a sound (sounding sound) generated by contact between the piston and the cylinder. Specifically, the piston moving up and down in the cylinder is tilted left and right or front and rear, and the piston outer peripheral surface and the cylinder inner peripheral surface come into contact with each other, and a hitting sound is generated. In particular, a hitting sound often occurs when the piston starts to descend from the top dead center toward the bottom dead center. Various sounds including the hitting sound generated during the operation of the air compressor are recognized as noise.

  Therefore, a sliding member called “rider ring” may be attached to the piston in order to reduce the hitting sound. The rider ring is interposed between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, and reduces (narrows) the gap between them. That is, the rider ring suppresses the inclination of the piston due to the gap between the piston outer peripheral surface and the cylinder inner peripheral surface, and reduces the hitting sound. Therefore, it is desirable that the gap between the outer peripheral surface of the rider ring attached to the piston and the inner peripheral surface of the cylinder be as small (narrow) as possible. In other words, it is desirable that the outer diameter of the piston including the rider ring is substantially the same as the inner diameter of the cylinder. Here, “the outer diameter of the piston including the rider ring” is synonymous with the outer diameter of the rider ring attached to the piston.

  However, if the difference between the outer diameter of the piston including the rider ring and the inner diameter of the cylinder is small, it is difficult to incorporate the piston into the cylinder. Specifically, when the piston is assembled into the cylinder, a rider ring is attached to the piston in advance. That is, it is necessary to insert the piston with the rider ring attached into the cylinder. Therefore, the smaller the difference between the outer diameter of the piston, including the rider ring, and the inner diameter of the cylinder, the more precisely the piston and cylinder must be aligned, and the time and effort required to incorporate the piston into the cylinder. Will increase.

  An object of the present invention is to reduce the hitting sound caused by the contact between the piston and the cylinder without increasing the time and labor required for assembling the piston into the cylinder.

The air compressor according to the present invention is a reciprocating type air compressor, and includes a cylinder, a piston that reciprocates in the cylinder, a connecting rod that converts rotational motion into a reciprocating motion, and a piston that connects the piston and the connecting rod. A pin and a rider ring that is attached to the outer peripheral surface of the piston and reciprocates integrally with the piston. An annular elastic body is provided between the piston and the rider ring, and the annular elastic body has a force toward the outside of the piston. Has occurred.
In one aspect of the present invention, the annular elastic body presses the rider ring against the cylinder inner wall.
In another aspect of the present invention, the annular elastic body is detachably provided by holding means provided on the piston.
In one aspect of the present invention, the holding means comprises a groove provided in the piston.
In one aspect of the present invention, a plurality of grooves are provided in the piston.
In one aspect of the present invention, the annular elastic bodies provided in the plurality of grooves have different elastic constants.
In one aspect of the present invention, the annular elastic body provided below the annular elastic body provided above the piston pin has a larger elastic constant.
In one aspect of the present invention, the annular elastic body is attached only below the piston pin.
In one embodiment of the present invention, the annular elastic body has a plurality of protrusions.
In one aspect of the present invention, the annular elastic body is made of metal or resin.

  According to the present invention, it is possible to reduce the hitting sound caused by the contact between the piston and the cylinder without increasing the time and labor required for assembling the piston into the cylinder.

It is a perspective view of an air compressor. It is sectional drawing of an air compressor. It is a partial expanded sectional view of an air compressor. It is an expansion perspective view of a 1st piston. It is a schematic diagram of the partial expansion of a 1st piston. It is a schematic diagram of AA sectional drawing shown by FIG.

  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 generation unit that uses a 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 includes a skeleton portion such as a frame and two air tanks 10 a and 10 b that are connected to the skeleton portion and are parallel to each other. Legs 12 are attached to the lower surfaces of both end portions of each of the air tanks 10a and 10b, and the air compressor 1 is placed at a desired installation location by the four legs 12. Further, a handle 13 is provided on the upper portion of the air compressor 1, and an operator can carry the air compressor 1 by holding the handle 13.

  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 (stator coil) 21, a rotor (rotor) 22 incorporated inside the stator 21, a rotating shaft (motor rotating shaft) 23 fixed to the rotor, and a rotor 22. A DC brushless motor having a Hall element or the like that detects a rotational position, and is disposed outside the crankcase 40. However, the motor 20 is fixed to the side surface of the crankcase 40 and integrated with the crankcase 40. The motor 20 in the present embodiment is an inner rotor type electric motor, but may be replaced with another type of motor, for example, an outer rotor type electric motor, or may be replaced with an axial gap motor.

  One end side of the motor rotation shaft 23 protrudes from the rotor 22 and penetrates the crankcase 40. One end side of the motor rotating shaft 23 penetrating the crankcase 40 is rotatably supported by a bearing provided in the crankcase 40.

  A fan 24 is disposed on the side opposite to the crankcase 40 across the motor 20. That is, the motor 20 is disposed between the crankcase 40 and the fan 24. The fan 24 is fixed to the other end side of the motor rotation shaft 23 protruding from the rotor 22 and rotates integrally with the motor rotation shaft 23 to generate cooling air. The wind cooling air generated by the fan 24 cools the motor 20, the compressed air generating unit 30, the control board, the piping forming the compressed air flow path, and the like.

  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. Is rotatably coupled to an eccentric cam mounted on the motor rotating shaft 23. 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. 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 are provided inside cylinder heads 54a and 54b provided in the respective cylinders 51a and 51b, and check valves are provided between the upper chambers of the respective cylinders 51a and 51b and the respective buffer chambers. Is provided. 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 reverse between the upper chamber of the first cylinder 51a and the buffer chamber is present. A stop valve is opened. Then, the air compressed by the first piston 52a is sent to the upper chamber of the second cylinder 51b via the first pipe that connects the first cylinder 51a and the second cylinder 51b.

  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 reverse between the upper chamber of the second cylinder 51b and the buffer chamber is present. A stop valve is opened. Then, the air compressed by the second piston 52b is sent to the air tank 10a through the second pipe that connects the second cylinder 51b and the air tank 10a, and stored. The air tanks 10a and 10b communicate with each other via a third pipe. Therefore, the pressure in the air tanks 10a and 10b is kept uniform. The first pipe, the second pipe, and the third pipe in the present embodiment are all 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 (low-pressure side compressor section) cylinder, and the second cylinder 51b is a second-stage high-pressure (high-pressure side compressor section) 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 end of the air tank 10a. 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 an open valve 18 that automatically opens when the pressure in the air tank 10a, 10b becomes higher than a predetermined pressure. A drain device may be provided in one of the air tanks 10a and 10b. In this case, when the drain device 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.

  Next, the first piston 52a and the second piston 52b shown in FIG. 2 will be described in more detail. However, although the first piston 52a and the second piston 52b have different dimensions, the basic structure is the same. Therefore, the first piston 52a will be described in detail, and details of the second piston 52b will be appropriately referred to as necessary.

  As shown in FIG. 3, a piston ring 60 and a rider ring 70a that reciprocate integrally with the first piston 52a are attached to the first piston 52a. The piston ring 60 is mounted at a position closer to the piston upper surface than the rider ring 70a, and the rider ring 70a is mounted at a position closer to the piston lower surface than the piston ring 60.

  The piston ring 60 and the rider ring 70a are common in that they are sliding members interposed between the outer peripheral surface of the first piston 52a and the inner peripheral surface of the first cylinder 51a. On the other hand, the piston ring 60 is different in that it mainly functions to maintain airtightness (seal function), and the rider ring 70a mainly functions to support the first piston 52a (support function).

  As shown in FIG. 4, a first annular groove 55 and a second annular groove 56 are formed on the outer peripheral surface of the first piston 52 a over the entire circumference, and the piston ring 60 is in the first annular groove 55. The rider rings 70a are mounted in the second annular grooves 56, respectively. More specifically, the piston ring 60 is annular and is fitted in the first annular groove 55. On the other hand, the rider ring 70 a has a belt shape and is wound around the second annular groove 56. As a result, the outer peripheral surface of the piston ring 60 is pressed against the inner peripheral surface of the first cylinder 51a shown in FIG. 3, and the airtightness of the upper chamber is maintained.

  The rider ring 70a shown in FIGS. 3 and 4 is made of, for example, a fluororesin, more specifically, polytetrafluoroethylene (PTFE (polytetrafluoroethylene)).

  Note that the rider ring 70b attached to the second piston 52b shown in FIG. 2 is also made of fluororesin. The rider ring 70a and the rider ring 70b have the same shape although the dimensions are different. The second piston 52b is also provided with a piston ring similar to the piston ring 60 shown in FIGS.

  As shown in FIG. 4, a triangular convex portion 71 is formed in one end (front end) in the longitudinal direction of the rider ring 70a in plan view, and a triangular concave portion in plan view in the other longitudinal end (rear end). 72 is formed. As shown in FIG. 4, when the rider ring 70 a is wound around the first piston 52 a (second annular groove 56), the convex portion 71 is disposed inside the concave portion 72, and the convex portion 71 and the concave portion 72 are separated from each other. The surface is flush, that is, there is almost no step between the convex portion 71 and the concave portion 72.

The outer diameter (D2) of the rider ring 70a attached to the first piston 52a is slightly larger than the outer diameter (D1) of the first piston 52a. In addition, the outer diameter (D3) of the piston ring 60 attached to the first piston 52a is slightly larger than the outer diameter (D2) of the rider ring 70a (D1 <D2 <D3).
As shown in FIG. 5, the first piston 52 a of the low-pressure side compressor portion is provided with a third annular groove 75 and a fourth annular groove 77, and the third and fourth annular grooves 75 and 77 are provided in the third and fourth annular grooves 75 and 77. Are provided with detachable annular elastic bodies 76 and 78 for pressing the rider ring 70a against the inner peripheral surface of the first cylinder 51a. The annular elastic bodies 76 and 78 are made of an elastic resin material or a metal member (piano wire or the like). As shown in FIG. 6, three protrusions 76a are arranged on the outer periphery at about 120 ° intervals. The rider ring 70a is pressed against the inner peripheral surface of the cylinder 51a. Similarly, the annular elastic body 77 is similarly provided with a protrusion.

  The annular elastic bodies 76 and 78 are set to have different spring constants so that the spring constant (elastic constant) of the annular elastic body 77 on the first connecting rod 53a side is larger than the spring constant of the annular elastic body 76. Is set. The shape of the annular elastic bodies 76 and 78 shown in FIG. 6 is an example, and any shape can be used as long as it has a function of pressing the rider ring 70a against the inner peripheral surface of the cylinder 51a. good.

When attaching the annular elastic bodies 76, 78 to the third and fourth annular grooves 75, 77, the annular elastic bodies 76, 78 are attached to the outer radial direction using a tool or the like.
With this configuration, the cylinder 51 and the rider ring 70a are always in close contact with each other by the annular elastic bodies 76 and 78 without strictly managing the thickness of the rider ring 70a. The vibration generated by the gap between the cylinder 51 and the rider ring 70a during the reciprocating motion of 52a can be suppressed, and the noise of the compressor can be reduced.

As the first piston 52a reciprocates, the first piston 52a tries to vibrate while tilting left and right by the gap between the first piston 52a and the cylinder 51 around the piston pin 80, but the rider ring 70a is caused by the annular elastic bodies 76 and 78. Since it is urged in two places, it can follow the inclination of the first piston 52a.
Furthermore, the inclination width of the first piston 52a is larger in the lower part than in the upper part in the present embodiment, depending on the position of the piston pin 80, and therefore the spring of the annular elastic body 78 located in the lower part. Since the constant is made larger than that of the upper annular elastic body 76, the inclination of the first piston 52a can be made uniform, so that the knitting wear of the rider ring 70a can be suppressed, the life can be improved, and the noise can be improved. Can also be reduced.
Furthermore, although the case where two annular elastic bodies are provided has been described, one annular elastic body may be provided. In this case, by providing the annular elastic body below the piston pin 80, the upper part of the piston 52a is connected to the piston ring 60 and the lower part. It is held in the cylinder 51 by an annular elastic body provided on the side.
Although the above description has been made on the low pressure side compressor section, the same applies to the high pressure side compressor section.

  The air compressor 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 12 Leg part 13 Handle 14 Cover 15a, 15b Coupler 16a, 16b Pressure reducing valve 17a, 17b Pressure gauge 18 Release valve 19 Operation panel 20 Motor 21 Stator 22 Rotor 23 Motor rotating shaft (Crankshaft )
24 Fan 30 Compressed air generating part 40 Crankcase 51a First cylinder 51b Second cylinder 52a First piston 52b Second piston 53a First connecting rod 53b Second connecting rod 54a, 54b Cylinder head 55 First annular groove 56 Second annular groove Groove 60 Piston ring 70A Base material 70a, 70b Rider ring 71 Convex part 72 Concave part 73 Groove 76, 78 Annular elastic body 100a, 100b, 100c, 100d Roller

Claims (10)

A reciprocating air compressor,
A cylinder,
A piston that reciprocates within the cylinder;
A connecting rod for converting rotational motion into reciprocating motion, a piston pin for connecting the piston and the connecting rod;
A rider ring mounted on the outer peripheral surface of the piston and reciprocating integrally with the piston;
An annular elastic body is provided between the piston and the rider ring,
An air compressor characterized in that the annular elastic body generates a force toward the outside of the piston. The air compressor according to claim 1, wherein the annular elastic body presses the rider ring against the inner wall of the cylinder. The air compressor according to claim 1, wherein the annular elastic body is detachably provided by holding means provided on the piston. 4. The air compressor according to claim 3, wherein the holding means is a groove provided in the piston. The air compressor according to claim 4, wherein a plurality of the grooves are provided in the piston. The air compressor according to claim 5, wherein the annular elastic bodies provided in the plurality of grooves have different elastic constants. The air compressor according to claim 6, wherein the plurality of annular elastic bodies has a larger elastic constant than the annular elastic body provided below the annular elastic body provided above the piston pin. The air compressor according to claim 1, wherein the annular elastic body is attached only below the piston pin. The air compressor according to claim 1, wherein the annular elastic body has a plurality of protrusions. The air compressor according to claim 1, wherein the annular elastic body is made of metal or resin.