JP2941432B2 - Compressor piston and piston type compressor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a piston-type compressor that converts the rotation of a rotating shaft into a reciprocating linear motion of a piston by a driving body such as a swash plate, and particularly relates to the piston.

BACKGROUND ART Generally, a piston-type compressor is known as a compressor for performing air conditioning in a room of a vehicle. In this piston type compressor, a driving body such as a swash plate for reciprocating the piston is supported by a rotating shaft in the crank chamber. The driver converts the rotation of the rotating shaft into a reciprocating linear motion of the piston in the cylinder bore. With the reciprocation of the piston, the refrigerant gas sucked into the cylinder bore from the suction chamber is compressed in the cylinder bore and discharged to the discharge chamber.

As the above-mentioned piston type compressor, there is a type in which refrigerant gas from an external refrigerant circuit is introduced into a suction chamber via a clamp chamber. As described above, in the compressor in which the crank chamber forms a part of the passage of the refrigerant gas, the refrigerant gas from the external refrigerant circuit passes through the crank chamber. Each part such as a piston and a driving body in the room is sufficiently lubricated.

On the other hand, there is a compressor in which refrigerant gas from an external refrigerant circuit is introduced into a suction chamber without passing through a crank chamber. Japanese Patent Application Laid-Open No. Sho 60-175783 discloses a compressor of this type. As described above, in the compressor in which the crank chamber is not configured as a part of the passage of the refrigerant gas, each component in the crank chamber is lubricated mainly by the lubricating oil supplied to the crank chamber together with the blow-by gas. The blow-by gas is a refrigerant gas leaking from the inside of the cylinder bore to the crank chamber through a space between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore when the piston compresses the refrigerant gas in the cylinder bore. .

The amount of the blow-by gas, in other words, the amount of the lubricating oil that can be supplied into the crank chamber depends on the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore. Therefore, in order to supply a sufficient amount of lubricating oil into the crankcase to be able to satisfactorily lubricate each component in the crankcase, it is necessary to increase the clearance. However, if the clearance between the piston and the cylinder bore is large, the compression efficiency of the compressor decreases.

In order to solve the above problems, for example, FIG.
A compressor having a structure as shown in FIG. 12A or FIG. In the compressor shown in FIG.
A swash plate 124 as a driving body is mounted on a rotating shaft (not shown) so as to be integrally rotatable. The shoe 125 is disposed between the swash plate 124 and the tail of the single-headed piston 122. Shoe 125
Has a spherical surface that slidably engages with the holding recess 122a of the piston 122 and a plane that slides on front and rear surfaces of the swash plate 124. When the swash plate 124 rotates with the rotation of the rotating shaft, the piston 122 reciprocates in the cylinder bore 123 via the shoe 125 by the action of the swash plate 124.

On the other hand, in the compressor shown in FIG. 12B, a rocking plate 128 as a driving body is mounted on a rotating shaft (not shown) so as to be relatively rotatable. The swing plate 128 swings with the rotation of the rotation shaft. The rod 129 has spheres 129a at both ends, and each sphere 129a is slidably held by a holding recess 128a of the rocking plate 128 and a holding recess 126a of the piston 126, respectively. When the swinging plate 128 swings with the rotation of the rotating shaft, the swing is transmitted to the piston 126 via the rod 129, and the piston 12
6 reciprocates in the cylinder bore 127.

In each of the compressors described above, the annular grooves 121 are formed on the outer peripheral surfaces of the pistons 122 and 126, respectively. Piston 122,1
With the reciprocation of 26, the lubricating oil adhering to the inner peripheral surfaces of the cylinder bores 123 and 127 is raked up in the groove 121. Groove 121
When the pistons 122 and 126 are moved to the bottom dead center, the pistons are exposed from the inside of the cylinder bores 123 and 127 into the crank chamber. Therefore, the lubricating oil collected in the groove 121 is discharged toward the swash plate 124 and the rocking plate 128 (that is, the crank chamber) when the groove 121 is exposed from the cylinder bores 123 and 127. This lubricating oil lubricates the connection between the swash plate 124 and the oscillating plate 128 and the pistons 122 and 126, and the like. In the compressor having such a structure, it is possible to satisfactorily lubricate each part in the crank chamber without increasing the clearance between the pistons 122 and 126 and the cylinder bores 123 and 127, in other words, without reducing the compression efficiency of the compressor. Can be.

However, the compressors shown in FIGS. 12A and 12B have the following disadvantages.

As the pistons 122 and 126 approach the bottom dead center, the portions accommodated in the cylinder bores 123 and 127 decrease.
However, the pistons 122 and 126 reciprocate in the bores 123 and 127 while being supported by the inner peripheral surfaces of the cylinder bores 123 and 127. For this reason, when the portions of the pistons 122 and 126 accommodated in the bores 123 and 127, in other words, the portions supported by the bores 123 and 127 are reduced, the support by the bores 123 and 127 becomes unstable and rattles. For this reason, as shown exaggeratedly in FIGS. 12 (a) and 12 (b), the pistons 122, 126
The opening edge of the groove 121 interferes with the opening edges of the cylinder bores 123 and 127. As a result, not only the pistons 122 and 126 are not smoothly reciprocated, but also the opening edges of the grooves 121 and the cylinder bores 123 and 127 of the pistons 122 and 126 are worn or damaged.

In particular, in the compressor shown in FIG. 12A, the rotational movement of the swash plate 124 is converted into the reciprocating movement of the piston 122 via the shoe 125. In such a compressor, for example, a piston
As 122 moves from bottom dead center toward top dead center to compress the refrigerant gas, the compression reaction force and the inertial force of piston 122 act on swash plate 124 via piston 122. Swash plate 12
Although the force acting on 4 acts as a reaction force on the piston 122, the swash plate 124 is inclined with respect to a plane orthogonal to the axis of the rotating shaft, so a part of the reaction force acting on the piston 122 is , And acts in a direction to press the piston 122 against the inner peripheral surface of the cylinder bore 123. For this reason, in the compressor shown in FIG. 12A, the groove 121 of the piston 122 collides violently with the opening edge of the cylinder bore 123 as compared with the compressor shown in FIG. It becomes more noticeable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a piston of a compressor and a piston type compressor in which a piston moves smoothly and lubricating oil can be sufficiently supplied to a member for driving the piston.

DISCLOSURE OF THE INVENTION In order to achieve the above object, the piston in the compressor of the present invention, with the rotation of the rotating shaft, through a driving body mounted on the rotating shaft in the crank chamber, the top dead center in the cylinder bore and Reciprocates with the bottom dead center. The piston has an outer peripheral surface that is in sliding contact with the inner peripheral surface of the cylinder bore. A groove extending in the axial direction of the piston is provided on the outer peripheral surface of the piston.

Therefore, according to the present invention, lubricating oil adhering to the inner peripheral surface of the cylinder bore accumulates in the groove as the piston reciprocates. If, for example, the groove is exposed from the cylinder bore into the crank chamber as the piston reciprocates, the lubricating oil in the groove is supplied into the crank chamber, and the lubricating oil lubricates the driving body and the like in the crank chamber. Since the groove extending in the axial direction of the piston does not interfere with the opening edge of the cylinder bore, the piston moves smoothly. Also, this groove
The sliding resistance between the piston and the cylinder bore is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a compressor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the piston arranged at the top dead center.

FIG. 3 is a perspective view showing a piston disposed between a top dead center and a bottom dead center.

FIG. 4 is a perspective view showing the piston arranged at the bottom dead center.

 FIG. 5 is a partially enlarged sectional view of the piston.

FIG. 6A is a graph showing the relationship between the rotation angle of the rotation shaft (movement position of the piston) and the magnitude of the side force acting on the piston.

FIG. 6B is a schematic diagram for explaining a suitable formation position of the second groove.

FIG. 7 is an enlarged sectional view of a main part, in which a state in which a piston arranged at the top dead center is inclined is exaggerated.

FIG. 8 is a perspective view showing a piston according to a first modification.

FIG. 9 is a perspective view showing a piston according to a second modification.

FIG. 10 is a perspective view showing a piston according to a third modification.

FIG. 11A is a perspective view showing a piston according to a fourth modification.

FIG. 11B is a partial perspective view showing a piston according to a fifth modification.

FIG. 11C is a partial perspective view showing a piston according to a sixth modification.

FIG. 12A is an enlarged sectional view of a main part showing a conventional compressor.

FIG. 12B is an enlarged sectional view of a main part showing another conventional compressor.

FIG. 13 is a longitudinal sectional view showing a compressor according to a second embodiment of the present invention.

 FIG. 14 is a cross-sectional view taken along line 14-14 of FIG.

 FIG. 15 is a cross-sectional view taken along line 15-15 of FIG.

 FIG. 16 is a cross-sectional view taken along line 16-16 of FIG.

 FIG. 17 is a sectional view taken along line 17-17 in FIG.

 FIG. 18 is a perspective view showing a piston.

FIG. 19 is a perspective view showing a piston according to the first modification.

FIG. 20 is a perspective view showing a piston according to the second modification.

FIG. 21 is a perspective view showing a piston according to the third modification.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a first embodiment of a piston type variable displacement compressor embodying the present invention will be described with reference to FIGS.

As shown in FIG. 1, the front housing 1 is joined to a front end surface of a cylinder block 2. The rear housing 3 is connected to the cylinder block 2 via a valve plate 4.
To the rear end face. The front housing 1, the cylinder block 2, and the rear housing 3 constitute a compressor housing. The suction chamber 3a and the discharge chamber 3b are formed between the rear housing 3 and the valve plate 4. Refrigerant gas from an external refrigerant circuit (not shown)
It is directly introduced into the suction chamber 3a via the inlet 3c.

The valve plate 4 has a suction port 4a, a suction valve 4b, a discharge port 4c, and a discharge valve 4d. The crank chamber 5
It is formed between the front housing 1 and the cylinder block 2. The rotating shaft 6 is rotatably supported by the front housing 1 and the cylinder block 2 via a pair of bearings 7, and penetrates through the crank chamber 5. The support hole 2b is formed at the center of the cylinder block 2.
The rear end of the rotating shaft 6 is inserted into the support hole 2b, and the rear end is supported by the inner peripheral surface of the support hole 2b via the bearing 7.

The lug plate 8 is fixed to the rotating shaft 6. The swash plate 9 as a driving body is supported by the rotating shaft 6 in the crank chamber 5 so as to be slidable and tiltable in the direction of the axis L thereof. The swash plate 9 is connected to the lug plate 8 via the hinge mechanism 10.
It is connected to. The hinge mechanism 10 includes a support arm 19 formed on the lug plate 8 and a pair of guide pins 20 formed on the swash plate 9. Guide pin 20
It is slidably fitted in a pair of guide holes 19a formed in the support arm 19. The hinge mechanism 10 rotates the swash plate 9 integrally with the rotation shaft 6. Further, the hinge mechanism 10
It guides the movement of the swash plate 9 in the direction of the axis L and the tilting of the swash plate 9.

The plurality of cylinder bores 2 a are formed in the cylinder block 2 around the rotation shaft 6, and extend along the axis L of the rotation shaft 6. The hollow single-headed piston 11 is housed in the cylinder bore 2a. Groove in the tail of piston 11
11a is formed. The hemispherical portions of the pair of chutes 12 are relatively slidably fitted to the inner wall surfaces of the groove 11a facing each other. The swash plate 9 is slidably held between the flat portions of the two shoes 12. The rotational motion of the swash plate 9 is converted into a reciprocating linear motion of a piston 11 via a shoe 12,
Reciprocates back and forth in the cylinder bore 2a. During the suction stroke in which the piston 11 moves from top dead center to bottom dead center, the suction chamber
Refrigerant gas in 3a pushes open suction valve 4b from suction port 4a and flows into cylinder bore 2a. During the compression stroke in which the piston 11 moves from bottom dead center to top dead center, the cylinder bore 2a
The refrigerant gas inside is compressed and discharged from discharge port 4c to discharge valve 4d.
Is pushed open to be discharged into the discharge chamber 3b.

The thrust bearing 21 is disposed between the lug plate 8 and the front housing 1. With the compression of the refrigerant gas, a compression reaction force acts on the piston 11. This compression reaction force is received by the front housing 1 via the piston 11, the swash plate 9, the lug plate 8, and the thrust bearing 21.

As shown in FIGS. 1 to 4, a detent member 22 is integrally formed on the tail of the piston 11. Detent member 22
Has a peripheral surface having substantially the same diameter as the inner peripheral surface of the front housing 1. The peripheral surface of the detent member 22 is in contact with the inner peripheral surface of the front housing 1 to prevent the rotation of the piston 11 about the central axis S.

As shown in FIG. 1, the supply passage 13 connects the discharge chamber 3b and the crank chamber 5. The electromagnetic valve 14 is attached to the rear housing 3 and is arranged in the supply passage 13. When the solenoid 14a of the electromagnetic valve 14 is excited, the valve body 14b closes the valve hole 14c. When the solenoid 14a is demagnetized, the valve element 14b opens the valve hole 14c.

The pressure release passage 6a is formed in the rotating shaft 6. Pressure relief passage
6a has an inlet opening into the crank chamber 5 and an outlet opening inside the support hole 2b. The pressure release hole 2c is
Is connected to the suction chamber 3a.

When the supply passage 13 is closed by the excitation of the solenoid 14a, the high-pressure refrigerant gas in the discharge chamber 3b is not supplied to the crank chamber 5. In this state, the refrigerant gas in the crank chamber 5 only flows out to the suction chamber 3a through the pressure release passage 6a and the pressure release hole 2c, and the pressure in the crank chamber 5 is reduced to a low pressure in the suction chamber 3a. Approaching. Therefore, the difference between the pressure in the crank chamber 5 and the pressure in the cylinder bore 2a becomes small,
As shown in FIG. 1, the inclination angle of the swash plate 9 is maximized, and the displacement of the compressor is maximized.

When the supply passage 13 is opened by the demagnetization of the solenoid 14a, the high-pressure refrigerant gas in the discharge chamber 3b
And the pressure in the crank chamber 5 rises. Therefore, the difference between the pressure in the crank chamber 5 and the pressure in the cylinder bore 2a becomes large, the inclination angle of the swash plate 9 becomes minimum, and the discharge capacity of the compressor becomes minimum.

When the stopper 9a formed on the front surface of the swash plate 9 abuts on the lug plate 8, the swash plate 9 is regulated so as not to incline beyond a predetermined maximum inclination angle. Swash plate 9
Is restricted to the minimum inclination angle by contacting the ring 15 mounted on the rotating shaft 6.

As described above, the pressure in the crank chamber 5 is adjusted by closing and opening the supply passage 13 in accordance with the excitation and the demagnetization of the solenoid 14a of the electromagnetic valve 14. When the pressure in the crank chamber 5 changes, the front surface of the piston 11 (FIG. 1)
The difference between the pressure in the crank chamber 5 acting on the left surface of the swash plate 9 and the pressure in the cylinder bore 2a acting on the rear surface of the piston 11 (the right surface in FIG. 1) also changes, and the inclination of the swash plate 9 changes I do. The movement stroke of the piston 11 changes with the change of the inclination angle of the swash plate 9, and the displacement of the compressor is adjusted.
The solenoid 14a of the electromagnetic valve 14 is selectively excited and demagnetized under the control of a controller (not shown) according to information such as a cooling load. That is, the discharge capacity of the compressor is adjusted according to the cooling load.

As shown in FIGS. 1 to 5, the ring-shaped first groove 16 as the collecting means is formed on the outer peripheral surface of the head of the piston 11 so as to extend in the circumferential direction. As shown in FIG. 4, the first groove 16 is formed at a position where the first groove 16 is not exposed from the inside of the cylinder bore 2a into the crank chamber 5 when the piston 11 moves to the bottom dead center. The swash plate 9 shown in FIGS. 1 to 4 is in the state of the maximum inclination.

The second groove 17 as the communication means is formed on the outer peripheral surface of the piston 11 so as to extend along the central axis S of the piston 11. The base end of the second groove 17 is located near the first groove 16. The second groove 17 is provided at a position described below on the peripheral surface of the piston 11. FIG. 6 (b)
As shown in FIG. 5, the piston 11 is viewed from the side where the rotation direction R of the rotation shaft 6 is the clockwise rotation direction (in this figure, the piston 11 is viewed from the tail side), and the center of the rotation shaft 6 is A straight line M passing through the axis L and the central axis S of the piston 11 is virtually provided. Intersection P between this straight line M and the peripheral surface of the piston 11
Of the points P1 and P2, the point P1 farthest from the center axis L of the rotary shaft 6 is
12 o'clock position. In this case, the second groove 17 is
Is provided in a range E from 9 o'clock to 10:30 on the circumferential surface.

Further, as shown in FIG. 2, the second groove 17 is formed in such a position and length that the piston 11 is not exposed from the inside of the cylinder bore 2a into the crank chamber 5 when the piston 11 is moved near the top dead center. . The second groove 17 is not connected to the first groove 16. FIG.
As shown in the figure, the inner bottom surface 18 on the distal end side of the second groove 17 is
It forms a slope that is slightly connected to the peripheral surface of the piston 11.

The surface of the piston 11 is polished by, for example, a centerless polishing method. Although not particularly shown, in this centerless polishing method, a chuck for holding a piston 11 as a workpiece is not used, and the piston 11 is polished while being rotated together with a polishing wheel while being mounted on a receiving table. You.
For this reason, for example, when a plurality of the second grooves 17 are provided in the circumferential direction of the piston 11, the rotation center of the piston 11 mounted on the receiving table is not stable, so that the polishing cannot be performed with high accuracy. . Therefore, in order to accurately polish the piston 11 by the centerless polishing method, the number of the second grooves 17 is preferably as small as possible. In the present embodiment, only one second groove 17 having the minimum width and depth necessary for supplying the lubricating oil into the crank chamber 5 is formed.

Now, in the above-described compressor, the refrigerant gas in the suction chamber 3a is sucked into the cylinder bore 2a during the suction stroke in which the piston 11 moves from the top dead center to the bottom dead center. At this time, a part of the lubricating oil contained in the refrigerant gas adheres to the inner peripheral surface of the cylinder bore 2a. On the other hand, during the compression stroke in which the piston 11 moves from the bottom dead center to the top dead center, the refrigerant gas in the cylinder bore 2a is compressed and discharged to the discharge chamber 3b. At this time, a part of the refrigerant gas in the cylinder bore 2a leaks as blow-by gas to the crank chamber 5 through a narrow clearance K between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a. At that time, part of the lubricating oil contained in the blow-by gas adheres to the inner peripheral surface of the cylinder bore 2a.

The lubricating oil adhering to the inner peripheral surface of the cylinder bore 2a is reciprocated by the piston 11 and the opening edge 16 of the first groove 16 of the piston 11 is moved.
It is scraped off by a and stored in the first groove 16.

When the piston 11 is in the compression stroke, the refrigerant gas (blow-by gas) leaking from the cylinder bore 2a causes the first groove
The pressure inside 16 increases. Only when the piston 11 is moved to the vicinity of the top dead center, the second groove 17 is entirely formed in the cylinder bore.
2a is closed by the inner peripheral surface, otherwise the second groove 17
Is exposed into the crank chamber 5. For this reason, the pressure in the second groove 17 is equal to or slightly higher than the pressure in the crank chamber 5. The first groove 16 communicates with the second groove 17 via a narrow clearance K. Therefore, when the piston 11 is in the compression stroke, the lubricating oil in the first groove 16 is supplied to the second groove 16 via the clearance K based on the difference between the pressure in the first groove 16 and the pressure in the second groove 17. It flows into 17. The lubricating oil flowing into the second groove 17 flows into the crank chamber 5 through a portion of the second groove 17 exposed into the crank chamber 5. This lubricating oil is used to connect the swash plate 9 and the piston 11,
In other words, it is supplied to between the swash plate 9 and the shoe 12 and between the shoe 12 and the piston 11 to lubricate those parts well.

When the inclination angle of the swash plate 9 becomes small, the second groove 17 may not be exposed from the inside of the cylinder bore 2a even if the piston 11 is moved to the bottom dead center. However, in this embodiment, the second
The length from the tip of the groove 17 to the peripheral edge on the tail side of the piston 11 is short. For this reason, the lubricating oil in the second groove 17 is easily discharged from the tip of the second groove 17 to the crank chamber 5 side via the clearance K, and the connection portion between the swash plate 9 and the piston 11 is satisfactorily lubricated. I do.

In this way, the lubricating oil raked by the first groove 16 as the collecting means is supplied to the crank chamber 5 by the second groove 17 as the communicating means.

By the way, the piston 11 receives a reaction force (hereinafter referred to as a side force) from the inner peripheral surface of the cylinder bore 2a due to the compression reaction force and its own inertia force during the reciprocating movement. For this reason, it is desirable that the second groove 17 is formed on the peripheral surface of the piston 11 at a position that is not affected by the side force as much as possible (a position corresponding to the range E shown in FIG. 6B).

Specifically, as shown in FIGS. 2 and 7, when the piston 11 is near the top dead center, the compression reaction force acting on the piston 11 becomes the largest. The compression reaction force and the inertial force of the piston 11 act on the swash plate 9. Therefore, piston 11
Receives a large reaction force Fs according to the resultant force Fo of the compression reaction force and the inertia force from the swash plate 9 inclined with respect to the plane orthogonal to the center axis L of the rotating shaft 6. This Fs is decomposed into a component force f1 along the moving direction of the piston 11 and a component force f2 toward the central axis L of the rotating shaft 6 according to the inclination angle of the swash plate 9. This component force f2 is a force that causes the tail side of the piston 11 to tilt in the direction of the component force f2. For this reason, the peripheral surface on the tail side of the piston 11 has a component force on the inner peripheral surface near the opening of the cylinder bore 2a.
Pressed with force according to f2. In other words, the peripheral surface on the tail side of the piston 11 receives a large reaction force (side force) Fa corresponding to the component force f2 from the inner peripheral surface near the opening of the cylinder bore 2a.

The position where the side force Fa acts on the piston 11 changes with the movement of the piston 11. For example, swash plate 9
During a period from the state shown in FIG. 2 to the state shown in FIG. 3 after rotating 90 ° in the direction of arrow R, the compressed refrigerant gas remaining in the cylinder bore 2a moves from the top dead center of the piston 11 to the bottom dead center. Re-expands with the movement of. When the swash plate 9 is close to the state shown in FIG. 3, the re-expansion of the compressed refrigerant gas in the cylinder bore 2a ends, and the suction of the refrigerant gas into the cylinder bore 2a is started. In this state, no compression reaction force acts on the swash plate 9, and the force Fo used on the swash plate 9 is
Most have inertia. Accordingly, the piston 11 receives the reaction force Fs from the swash plate 11 mainly based on the inertial force. This reaction force
Fs is a component force f1 along the moving direction of the piston 11 and a component force substantially along the rotation direction R of the swash plate 9 according to the inclination of the swash plate 9.
Decomposed into f2. This component force f2 is a force that causes the tail side of the piston 11 to tilt in the direction of the component force f2. For this reason,
The piston 11 receives a side force Fa corresponding to the component force f2 from the inner peripheral surface near the opening of the cylinder bore 2a. In addition,
As will be described later, in practice, when the swash plate 9 is in the state shown in FIG. 3, the force Fo acting on the swash plate 9 becomes substantially zero, so that the side force Fa hardly acts on the piston 11.

When the swash plate 9 is further rotated by 90 ° in the direction of arrow R from the state shown in FIG. 3 to the state shown in FIG. 4, the piston 11 is disposed at the bottom dead center. In this state, the direction of the component force f2 acting on the piston 11 is opposite to that in the case of FIG. 2 (when the piston 11 is arranged at the top dead center). Therefore, the piston 11 receives the side force Fa in the direction opposite to that in FIG. 2 from the inner peripheral surface near the opening of the cylinder bore 2a. Side force at this time
The size of Fa is smaller than in FIG.

As shown in FIGS. 2 and 7, the head of the piston 11 receives a side force Fb according to the component force f2 from the inner peripheral surface on the back side of the cylinder bore 2a. However, the first groove 16 is formed on the head side of the piston 11, and the second groove 17 is formed at least in the first groove 16.
It is provided on the tail side of the piston 11. Therefore,
The side force Fb does not directly act on the peripheral surface of the piston 11 from the base end to the front end of the second groove 17. Therefore, when determining an appropriate arrangement position of the second groove 17 in the circumferential direction of the piston 11, it is not necessary to consider the side force Fb acting on the head side of the piston 1.

FIG. 6A is a graph showing the relationship between the rotation angle of the rotating shaft 6 (in other words, the movement position of the piston 11) and the magnitude of the side force Fa acting on the piston 11. In this graph, the rotation angle of the rotating shaft 6 when the piston 11 is at the top dead center is 0 °. The schematic diagram drawn below the horizontal axis of the graph is a diagram showing the direction of the side force Fa acting on the piston 11 corresponding to the rotation angle of the rotary shaft 6 shown on the horizontal axis. In this schematic view, the piston 11 is viewed from its tail side. This schematic diagram shows that the portion of the peripheral surface of the piston 11 on which the side force Fa acts changes in the same direction as the rotation direction R thereof as the rotation shaft 6 and the swash plate 9 rotate. In other words, while the piston 11 reciprocates once between the top dead center and the bottom dead center to perform the suction and compression strokes, the side force Fa acts on the entire circumference of the piston 11 sequentially.

As shown in FIG. 6 (a), from the state where the piston 11 is at the top dead center to the time when the rotating shaft 6 rotates 90 °, in other words, the swash plate 9 changes from the state of FIG. 2 to the state of FIG. In the meantime, the side force Fa may become a negative value. This means that, when the swash plate 9 is in the state in front of FIG. 3, the directions of the respective forces shown in FIG. 3 are reversed.

In the graph of FIG. 6A, when the rotation angle of the rotation shaft 6 is 0 ° (= 360 °), that is, when the piston 11 is at the top dead center, the side force Fa acting on the piston 11 becomes maximum. It is shown that. The position where the largest side force Fa is received on the peripheral surface of the piston 11 is the position at 6 o'clock as shown in FIG. 6B. Large side force Fa at 6 o'clock on the circumference of piston 11
Acts, the range E1 from 3 o'clock to 9 o'clock around the 6 o'clock position is strongly pressed against the inner peripheral surface of the cylinder bore 2a. Therefore, the second groove 17 is located in the range E1.
In this case, the opening edge of the second groove 17 is strongly pressed against the inner peripheral surface of the cylinder bore 2a, and the piston 11 and the cylinder bore 2a may be worn or damaged. Therefore, the second
The groove 17 is desirably provided on the peripheral surface of the piston 11 in a range excluding a range E1 from 3:00 to 9:00, that is, a range E2 from 9:00 to 3:00.

In order to further avoid the influence of the side force Fa, the second
The groove 17 is desirably provided in a range that receives the smallest side force Fa in the range E2 from 9 o'clock to 3 o'clock on the peripheral surface of the piston 11. The graph of FIG.
The side force Fa acting on the piston 11 is
Is in the compression stroke (when the rotation angle of the rotary shaft 6 is 180 ° to 3
This indicates that when the piston 11 is in the suction stroke (when the rotation angle of the rotating shaft 6 is 0 ° to 180 °) is relatively smaller than when the piston 11 is in the suction stroke.

In the suction stroke, when the re-expansion of the residual refrigerant gas in the cylinder bore 2a is completed, no compression reaction force acts on the swash plate 9, and the force acting on the swash plate 9 is almost the inertial force of the piston 11. . In particular, as shown in FIG. 6 (a), when the rotation angle of the rotating shaft 6 is 90 ° (when the swash plate 9 is in the state shown in FIG. 3), at 9 o'clock on the peripheral surface of the piston 11 The side force Fa hardly acts on the position. Therefore,
The side force Fa acting on the piston 11 is relatively smaller during the suction stroke than during the compression stroke in which a compression reaction force occurs. In other words, of the range E2 from 9 o'clock to 3 o'clock on the peripheral surface of the piston 11, the side force Fa acting on the range from 9 o'clock to 12 o'clock acts on the range from 12 o'clock to 3 o'clock. Is relatively smaller than the side force Fa.

In addition, as shown in FIG. 6A, when the piston 11 is located at the bottom dead center,
A relatively large side force Fa also acts at 12 o'clock. When the piston 11 is moved near the bottom dead center,
The length supported by the cylinder bore 2a is short, and it is likely to be unstable. For this reason, it is preferable not to provide the second groove 17 near the 12 o'clock position on the peripheral surface of the piston 11.

As a result of considering the above, in the present embodiment, FIG.
As shown in (b), the second groove 17 is provided on the peripheral surface of the piston 11 in a range E from 9 o'clock to 10:30.

In the first embodiment configured as described above, the following effects can be obtained.

The lubricating oil collected by the first groove 16 is
11 is reliably supplied to the crank chamber 5 through a second groove 17 formed so as to extend along the central axis S thereof. For this reason, even if the refrigerant gas from the external refrigerant circuit is introduced into the suction chamber 3a without passing through the crank chamber 5,
Each part in the crank chamber 5, such as the connection between the swash plate 9 and the piston 11, is lubricated well.

Even if the piston 11 moves to the bottom dead center,
The first annular groove 16 formed along the circumferential direction is not exposed from inside the cylinder bore 2a. For this reason, the first groove 16 does not interfere with the opening edge of the cylinder bore 2a. Also the piston
The second groove 17 extending in the direction of the axis S of 11 does not interfere with the opening edge of the cylinder bore 2a. Therefore, the piston 11 smoothly reciprocates, and wear and damage of the piston 11 and the cylinder bore 2a are prevented.

The first annular groove 16 scrapes the lubricating oil adhered to the inner peripheral surface of the cylinder bore 2a over the entire inner peripheral surface. Therefore, it is possible to supply as much lubricating oil as possible into the crank chamber 5.

In the compressor of this embodiment, the rotation of the swash plate 9
Is converted into the reciprocating motion of the piston 11 via the. In such a compressor, the compression reaction force acting on the swash plate 9 and the piston
Due to the inertial force of 11, the piston 11 is pressed toward the inner peripheral surface of the cylinder bore 2a. Therefore, it is particularly effective to embody the configuration of the present invention in such a type of compressor.

The first groove 16 and the second groove 17 are not directly connected on the peripheral surface of the piston 11, and the two grooves 16, 17 are connected via a narrow clearance K between the piston 11 and the cylinder bore 2a. Communicate. Therefore, the refrigerant gas in the first groove 16 flows into the second groove 17 in a state narrowed by the narrow clearance K, so that the flow becomes slow. Therefore, the piston 11
Is moved to the vicinity of the top dead center, the high-pressure refrigerant gas in the cylinder bore 2a is prevented from escaping to the crank chamber 5 through the two grooves 16 and 17 at once. As a result, a reduction in the compression efficiency of the compressor is prevented as much as possible.

The inner bottom surface 18 on the distal end side of the second groove 17 forms an inclined surface that smoothly connects to the peripheral surface of the piston 11. Therefore, when the piston 11 moves from the bottom dead center to the top dead center, the opening edge of the second groove 17 on the tip side is prevented from interfering with the opening edge of the cylinder bore 2a. As a result, the piston
11 smoothly reciprocates, and wear and damage of the piston 11 and the cylinder bore 2a are prevented.

The second groove 17 is located at a position on the peripheral surface of the piston 11 where the influence of the side force Fa caused by the compression reaction force and the inertial force of the piston 11 is minimized {a position corresponding to the range E shown in FIG. ｝ Is formed. Therefore, the portion of the second groove 17 of the piston 11 is prevented from being strongly pressed against the cylinder bore 2a, and wear and damage of the piston 11 and the cylinder bore 2a are more reliably prevented.

Since the hollow piston 11 is lightweight, the inertial force of the piston 11 is small. When the inertial force is small, the piston 11
Further, wear and damage of the cylinder bore 2a are more effectively prevented.

The temperature of the compressor gradually increases with operation, and the piston 11 thermally expands. Hollow objects have a slightly lower degree of thermal expansion than solid objects. Since the piston 11 of this embodiment is hollow, the clearance K between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a is suppressed from being reduced due to the thermal expansion of the piston 11. For this reason, an increase in sliding resistance between the piston 11 and the cylinder bore 2a is prevented.

The compressor according to the present embodiment is a variable displacement compressor capable of controlling a discharge capacity. In such a compressor, a clutch that transmits and disconnects power is not provided between the external drive source and the rotating shaft of the compressor, and the external drive source and the compressor are directly connected. For this reason, the compressor of this embodiment is operated as long as the external drive source is operating. Therefore, in such a compressor, it is important to properly lubricate each part. That is, it is very effective to employ the piston 11 of the present embodiment having the first groove 16 and the second groove 17 in a variable displacement compressor.

The first embodiment can be modified as follows.

First, a first embodiment will be described. When the piston 11 is near the top dead center, the piston 11 tilts counterclockwise in the cylinder bore 2a as shown in an exaggerated manner in FIG.
Then, the lower part of the first groove 16 in the figure is opened toward the inner side of the cylinder bore 2a. As a result, the high-pressure refrigerant gas compressed in the cylinder bore 2a leaks into the first groove 16, and the compression efficiency decreases.

Therefore, in the first modified example, as shown in FIG. 8, the first groove 16 is provided only on the peripheral surface of the upper half of the piston 11. In other words, the first groove 16 is provided only on the peripheral surface of the piston 11 in the range E2 from 9:00 to 3:00 shown in FIG. 6B. In this way, even if the piston 11 near the top dead center tilts as shown in FIG.
The first groove 16 is not opened toward the inner side of the cylinder bore 2a. As a result, the high-pressure refrigerant gas compressed in the cylinder bore 2a does not leak into the first groove 16, and a decrease in compression efficiency is prevented.

Next, a second modification will be described. In the second modification, as shown in FIG. 9, the second groove 17 is connected to the first groove 16. By doing so, the lubricating oil in the first groove 16 flows smoothly into the second groove 17.

Next, a third modification will be described. In the third modification, as shown in FIG. 10, the tip of the second groove 17 extends to the peripheral edge of the piston 11 on the tail side, and the second groove 17 is always directly connected to the crank chamber 5. ing. This prevents the tip of the second groove 17 from interfering with the opening edge of the cylinder bore 2a when the piston 11 moves from the bottom dead center to the top dead center. As a result, the piston 11 reciprocates more smoothly, and the piston 11 and the cylinder bore 2a
Wear and damage are more reliably prevented. In addition, the second
The lubricating oil in the groove 17 flows out into the crankcase 5 more smoothly. In the third modification, as shown by a two-dot chain line in FIG.
17 may be connected to the first groove 16 so that the first groove 16 always communicates with the crank chamber 5.

Next, a fourth modification will be described. In the fourth modification, as shown in FIG. 11A, a plurality of (three in the drawing) elongated grooves 16a are arranged in the first groove 16 along the circumferential direction of the piston 11. , 16b, 16c. Also, the second groove 17 is formed by three grooves constituting the first groove 16.
It is constituted by a plurality of grooves 17a, 17b, 17b respectively corresponding to 16a, 16b, 16c. As shown by a two-dot chain line in FIG. 11 (a), at least one of the three grooves 17a, 17b, 17b constituting the second groove 17 is connected to the piston 11 so that it is always connected to the crank chamber 5. May be extended to the peripheral portion on the tail side of the vehicle.

In the fifth modification, as shown in FIG. 11B, the grooves 17a, 17b, 17c in the fourth modification are connected to the corresponding grooves 16a, 16b, 16c, respectively. Note that FIG.
As shown by a two-dot chain line in FIG.
At least one of the grooves 17a, 17b, 17b may extend to the peripheral edge on the tail side of the piston 11 so that it is always connected to the crank chamber 5.

In the sixth modification, as shown in FIG. 11C, the grooves 17a, 17a on both sides of the second groove 17 in the fourth modification are used.
c is connected in the middle of the central groove 17b. As shown by a two-dot chain line in FIG. 11C, the central groove 17b may be extended to the peripheral portion on the tail side of the piston 11 so as to be always connected to the crank chamber 5.

In the eighth modification, as shown by a two-dot chain line in FIG. 5, a second groove 17 is formed on the inner peripheral surface of the cylinder bore 2a. This second groove 17 is always connected to the crankcase 5,
It extends to the opening edge of the cylinder bore 2a. In this case, a second groove 17 may be formed on the peripheral surface of the piston 11,
It is not necessary to form.

In the ninth modification, as shown by a two-dot chain line in FIG. 6B, the second groove 17 is provided on the peripheral surface of the piston 11 in a range E3 from 7:30 to 9:00. As described above, when the large side force Fa acts on the 6 o'clock position on the peripheral surface of the piston 11, the range E1 from 3 o'clock to 9 o'clock around the 6 o'clock position is within the cylinder bore 2a. It is strongly pressed against the peripheral surface. However, the strongest pressing is at the 6 o'clock position, and the pressing force becomes weaker as the distance from the 6 o'clock position increases. Therefore, actually, the range E3 from 7:30 to 9 o'clock away from the 6 o'clock position
Is not so strongly pressed against the inner peripheral surface of the cylinder bore 2a. In addition, as shown in FIG. 6A, when the rotation angle of the rotation shaft 6 is short of 90 °, the side force Fa becomes a negative value. This means that the side force Fa does not directly act on the range E3 from 7:30 to 9:00 on the peripheral surface of the piston 11.

From the above, even if the second groove 17 is provided in the range E3 from 7:30 to 9 o'clock on the peripheral surface of the piston 11, no trouble occurs.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the following, description will be made focusing on differences from the first embodiment.

As shown in FIG. 13, the compressor of the second embodiment has basically the same structure as the compressor of the first embodiment. That is, the rotational motion of the swash plate 9 caused by the rotation of the rotary shaft 6 is converted into a reciprocating motion of the piston 11 in the cylinder bore 2a via the shoe 12.

A pulley 26 is fixed to the front end of the rotating shaft 6. The pulley 26 is rotatably supported at the front end of the front housing 1 via an angular bearing 27. The pulley 26 is operatively connected via a belt 28 to an engine (not shown) of the vehicle, which is an external drive source. The angular bearing 27 receives a load in the thrust direction and a load in the radial direction.

The accommodation hole 29 is formed at the center of the cylinder block 1,
It extends along the axis L of the rotating shaft 6. The cylindrical spool 30 whose rear end is closed is slidably accommodated in the accommodation hole 29. A coil spring 31 is interposed between the spool 30 and the inner surface of the housing hole 29. The coil spring 31 urges the spool 30 toward the swash plate 9.

The rear end of the rotating shaft 6 is inserted into the spool 30. The radial bearing 32 is disposed between the rear end of the rotating shaft 6 and the inner peripheral surface of the spool 30. The rear end of the rotating shaft 6 is supported by the inner peripheral surface of the housing hole 29 via the bearing 32 and the spool 30. The bearing 32 is movable along the axis L of the rotating shaft 6 together with the spool 30. The thrust bearing 33 is disposed on the rotating shaft 6 between the spool 30 and the swash plate 9. The thrust bearing 33 is movable along the axis L of the rotating shaft 6.

The suction passage 34 is formed at the center of the rear housing 3. The suction passage 34 communicates with the housing hole 29. The positioning surface 35 is formed on the valve plate 4 between the accommodation hole 29 and the suction passage 34. The rear end surface of the spool 30 can contact the positioning surface 35. When the rear end surface of the spool 30 contacts the positioning surface 35, the movement of the spool 30 in the direction away from the swash plate 9 is restricted, and the suction passage
Communication between 34 and accommodation hole 29 is cut off.

As the swash plate 9 moves toward the spool 30 while decreasing the inclination angle, the swash plate 9 presses the spool 30 via the thrust bearing 33. Therefore, the spool 30 is moved toward the positioning surface 35 against the urging force of the coil spring 31, and the spool 30 contacts the positioning surface 35. At this time, the inclination of the swash plate 9 is regulated to be minimum. The minimum inclination angle of the swash plate 9 is slightly larger than 0 °. Here, the inclination angle when the swash plate 9 is arranged on a plane orthogonal to the rotation axis 6 is defined as 0 °.

The suction chamber 3a communicates with the housing hole 29 via the communication port 36. When the spool 30 contacts the positioning surface 35, the communication port 36
Is shut off from the suction passage. The pressure release passage 6 a formed in the rotary shaft 6 has an inlet opening into the crank chamber 5 and an outlet opening inside the spool 30. The pressure release port 37 is formed on the peripheral surface on the rear end side of the spool 30. Pressure relief port 37
Communicates the inside of the spool 30 with the accommodation hole 29.

The external refrigerant circuit 37 includes a suction passage 34 for introducing refrigerant gas into the suction chamber 3a, and an outlet 38 for discharging refrigerant gas from the discharge chamber 3b.
And are connected. On the external refrigerant circuit 37, a condenser 39, an expansion valve 40, and an evaporator 41 are provided. A temperature sensor 42 is arranged near the evaporator 41. The temperature sensor 42 detects the temperature in the evaporator 41 and outputs a signal based on the detected temperature to the controller C.

The controller C controls the solenoid 14a of the electromagnetic valve 14 based on a signal from the temperature sensor 42. The controller C is an operation switch for operating the air conditioner.
When the temperature detected by the temperature sensor 42 becomes equal to or lower than a preset value in a state where 43 is turned on, the solenoid 14a is used to prevent the occurrence of frost in the evaporator 41.
Degauss. Further, the controller C operates the operation switch 43
The solenoid 14a is demagnetized in response to the OFF.

When the supply passage 13 is opened by the demagnetization of the solenoid 14a, the high-pressure refrigerant gas in the discharge chamber 3b
And the pressure in the crank chamber 5 rises. Therefore, as in the first embodiment, the swash plate 9 moves to the minimum inclination angle. When the spool 30 contacts the positioning surface 35, the swash plate 9
Is minimized, and the space between the suction passage 34 and the suction chamber 3a is shut off. Therefore, the refrigerant gas is supplied to the external refrigerant circuit 37.
From flowing into the suction chamber 3a, and the circulation of the refrigerant gas around the external refrigerant circuit 37 and the compressor is stopped.

Since the minimum inclination angle of the swash plate 9 is not 0 °, even when the inclination angle of the swash plate 9 is minimum, the refrigerant gas is sucked into the cylinder bore 2a from the suction chamber 3a and discharged from the cylinder bore 2a to the discharge chamber 3b. Have been. Therefore, when the inclination angle of the swash plate 9 is at a minimum, the refrigerant gas flows in the compressor around the discharge chamber 3a, the supply passage 13, the crank chamber 5, the pressure release passage 6a, the pressure release port 30a, the suction chamber 3a, and the cylinder bore 2a. Circulate in the circulation passage. Therefore, the lubricating oil flowing with the refrigerant gas lubricates each part in the compressor. There is a pressure difference between the discharge chamber 3b, the crank chamber 5, and the suction chamber 3a. This pressure difference and pressure relief port 30a
Has a large effect on stably holding the swash plate 9 at the minimum inclination angle.

When the supply passage 13 is closed by the excitation of the solenoid 14a, the refrigerant gas in the crank chamber 5 flows out to the suction chamber 3a through the pressure release passage 6a and the pressure release port 30a, and the crank chamber 5
The pressure in the chamber approaches the low pressure in the suction chamber 3a. Therefore, as in the first embodiment, the swash plate 9 moves to the maximum inclination angle.

FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. FIG. 14 mainly shows a hinge mechanism 10 for connecting the swash plate 9 and the lug plate 8, and a detent member 22 formed on the piston 11 to prevent the rotation of the piston 11.
FIG. 15 is a cross-sectional view taken along line 15-15 of FIG. This figure
Reference numeral 15 mainly shows the relationship between the suction chamber 3a and the discharge chamber 3b formed in the rear housing 3 and the cylinder bore 2a.

As shown in FIGS. 13 and 16 to 18, a plurality of (four in the present embodiment) grooves 44 are formed on the outer peripheral surface of the piston 11 so as to extend along the central axis S of the piston 11. . In other words, in the second embodiment, the first groove 16 in the first embodiment is not provided, and the groove corresponding to the second groove 17 is not provided.
Only 44 are provided. The groove 44 is provided on the peripheral surface of the piston 11 at a position as described below. As shown in FIG. 17, similarly to the first embodiment, the piston 11 is viewed from the side where the rotation direction R of the rotating shaft 6 is the clockwise rotation direction (in this figure, the piston 11 is , The center axis L of the rotating shaft 6 and the piston 11
Is virtually provided with a straight line M passing through the center axis line S of the line. Of the intersections P1 and P2 between the straight line M and the peripheral surface of the piston 11, a point P1 farther from the center axis L of the rotating shaft 6 is defined as a 12 o'clock position.
In this case, the groove 44 is provided on the peripheral surface of the piston 11 at a position excluding the position at 12:00 and the range E1 from 3:00 to 9:00.

The piston 11 shown in the lower part of FIG. 13 is arranged at the bottom dead center. When the piston 11 is located near the bottom dead center, a part of the groove 44 is exposed from inside the cylinder bore 2a into the crank chamber 5.

As shown in FIG. 17, on the peripheral surface of the piston 11, 3
A pair of recesses 45 are formed in a range E1 from time to 9:00. By providing the concave portion 45, the piston 11 is hollowed, and as a result, the piston 11 is reduced in weight as in the first embodiment. The concave portion 45 is open on the outer peripheral surface of the piston 11, and extends along the central axis S of the piston 11. Therefore, the recess 45 has the same function as the second groove 17 in the first embodiment, like the groove 44.

As described in the first embodiment, when the large side force Fa acts on the 6 o'clock position on the peripheral surface of the piston 11, the range E1 from 3 o'clock to 9 o'clock around the 6 o'clock position is used. Is strongly pressed against the inner peripheral surface of the cylinder bore 2a. In addition, when the piston 11 is located at the bottom dead center, a relatively large side force Fa also acts on the peripheral surface of the piston 11 at 12:00.

Further, as shown in FIG. 16, the piston 11 is in the compression stroke.
When is located between the bottom dead center and the top dead center, the piston 11 receives from the swash plate 11 a reaction force Fs corresponding to the resultant force Fo of the compression reaction force and the inertia force. This reaction force Fs is decomposed into a component force f1 along the moving direction of the piston 11 and a component force f2 substantially in the same direction as the rotation direction R of the swash plate 9. This component force f2 is a force that causes the tail side of the piston 11 to tilt in the direction of the component force f2. In addition, since a sliding resistance is generated between the swash plate 9 and the shoe 12, the rotation of the swash plate 9 exerts a force on the piston 11 to incline the tail side thereof in the same direction as the component force f2. This force increases as the rotation speed of the swash plate 9 increases. Therefore, the swash plate 9
When the rotation speed is high, a large side force Fa acts at the 3 o'clock position on the peripheral surface of the piston 11.

As a result of considering the above, in the present embodiment, as shown in FIG.
It is provided at a position excluding the hour position and the range E1 from 3:00 to 9:00. In other words, the groove 44 is formed on the peripheral surface of the piston 11 at a position that is not significantly affected by the side force Fa. Therefore, the groove 44 of the piston 11
Is strongly pressed against the cylinder bore 2a, and the piston 11 slides smoothly in the cylinder bore 2a.

Also in the second embodiment, the lubricating oil adhering to the inner peripheral surface of the cylinder bore 2a accumulates in the groove 44 as the piston 11 reciprocates. When the piston 11 moves to the vicinity of the bottom dead center, the groove 44 moves from the cylinder bore 2a to the crank chamber 5
The lubricating oil exposed to the inside and accumulated in the groove 44 is supplied into the crank chamber 5. For this reason, even when only the groove 44 extending along the central axis S of the piston 11 is provided on the peripheral surface of the piston 11, the connection portion between the swash plate 9 and the piston 1 can be improved similarly to the first embodiment. Can be lubricated.

In the second embodiment, since a groove corresponding to the first groove 16 in the first embodiment is not provided in the piston 11, there is a problem that the groove extending in the circumferential direction of the piston 11 interferes with the opening edge of the cylinder bore 2a. Of course not. The effect of forming the groove 44 at a position that is not significantly affected by the side force Fa is the same as that of the first embodiment. Furthermore, the effect of forming the piston 11 in a hollow shape is also provided.
This is the same as the first embodiment.

As the clearance K between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a decreases, the sliding resistance between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a increases. This is because a force acting between the molecules of the lubricating oil contained in the refrigerant gas causes an adhesion between the piston 11 and the cylinder bore 2a. This adhesion decreases as the clearance K increases. The lubricating oil present between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a suppresses the refrigerant gas in the cylinder bore 2a from leaking to the crank chamber 5 through the clearance K with the compression. It is important to suppress the leakage of the refrigerant gas in order to improve the compression efficiency of the compressor. Therefore, the depth of the groove 44 is
The depth is set so as to minimize the adhesive force generated by the force acting between the molecules of the lubricating oil as long as the function of the lubricating oil that suppresses the leakage of the refrigerant gas is not impaired. Such a groove 44 reduces sliding resistance between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a.

The compressor of the present embodiment is a variable displacement compressor as in the first embodiment, and is operated as long as the outer peripheral drive source is operating. Therefore, in such a compressor, if the sliding resistance between the piston 11 and the cylinder bore 2a decreases,
Power loss can be greatly reduced. That is, it is very effective to adopt the piston 11 of the present embodiment having the groove 44 for a variable displacement compressor used in a state directly connected to an external drive source.

The second embodiment can be modified as follows.

First, a first embodiment will be described. In the second embodiment, the groove 44 having a relatively wide width is formed in the piston 11. On the other hand, in the first modification, as shown in FIG. 19, instead of the groove 44 in the second embodiment, a number of linear grooves 46 are provided on the peripheral surface of the piston 11 on the central axis S thereof. It is formed so as to extend along. The groove 46 is provided on the peripheral surface of the piston 11 at substantially the same position as the groove 44 in the second embodiment. Also, the depth of the groove 46,
As with the groove 44 in the second embodiment, the depth is set so that the adhesion force generated by the force acting between the molecules of the lubricating oil can be reduced as much as possible without impairing the function of the lubricating oil to suppress the leakage of the refrigerant gas. Have been. Therefore, in the first modified example, the same effect as in the second embodiment can be obtained.

In the second modification, as shown in FIG. 20, the groove 44 is provided on the peripheral surface of the piston 11 at a position excluding the position of 6:00 and the range E2 from 9:00 to 3:00. . This groove 44
Is the same as the groove 44 described in the second embodiment.
In the second modification, the same effect as in the second embodiment can be obtained.

In the third modification, as shown in FIG. 21, the groove 44 is located on the peripheral surface of the piston 11 at the position of 12:00, the position of 3
It is provided at a position excluding the hour position and the 9 o'clock position. This groove 44 is the same as the groove 44 described in the second embodiment. The piston 11 is formed in a hollow shape by, for example, welding another member to the open end of a cylindrical body having a bottom. Also in the third modification, the second
The same effect as that of the embodiment can be obtained.

The present invention is not limited to the above embodiment, but can be embodied with the following modifications.

(1) In each of the above embodiments, the second groove 17 and the grooves 44, 46
May be provided at any position on the peripheral surface of the piston 11. In this case, it is preferable that the second groove 17 and the grooves 44 and 46 are provided on the peripheral surface of the piston 11 at positions other than the 6 o'clock position where the generally largest side force Fa acts. More preferably, the second groove 17 and the groove 4
It is preferable that the wheels 4 and 46 are provided on the peripheral surface of the piston 11 at positions other than the positions of 12 o'clock, 3 o'clock, and 6 o'clock.
At the 12 o'clock and 3 o'clock positions on the circumference of the piston 11,
A relatively large side force Fa acts.

(2) The number, length, depth and width of the second groove 17 and the grooves 44 and 46 in each of the above embodiments are appropriately changed.

(3) In the first embodiment and the respective modifications of the first embodiment, the lubrication that the depth of the first groove 16 and the second groove 17 is suppressed to suppress the leakage of the refrigerant gas as in the second embodiment. The depth must be set so as to minimize the adhesive force generated by the force acting between the molecules of the lubricating oil as long as the oil function is not impaired. This reduces the sliding resistance between the outer peripheral surface of the piston 11 and the inner peripheral surface of the cylinder bore 2a.

(4) In the second embodiment and the modified examples of the second embodiment, the tips of the grooves 44, 46 are extended to the peripheral portion on the tail side of the piston 11 so that the grooves 44, 46 are always connected to the crank chamber 5. Connect directly.

(5) In the second embodiment and the modified examples of the second embodiment, the inner bottom surfaces on the distal ends of the grooves 44 and 46 are smoothly connected to the peripheral surface of the piston 11 as in the first embodiment. Forming on a slope, in this way,
When piston 11 moves from bottom dead center to top dead center, groove 4
The opening edge on the tip end side of 4, 46 is prevented from interfering with the opening edge of cylinder bore 2a.

(6) In the first and second embodiments, the present invention is embodied by a variable displacement compressor having a single-headed piston. For example, a compressor having a fixed inclination of a swash plate, a double-headed piston-type compressor 23, a compressor in which a piston is connected to a rocking plate via a rod as shown in FIG. 23, or a wave-cam type compressor. Wave cam type compressor
A compressor having a wave cam having a wave-like cam surface instead of a swash plate.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuru Hashimoto 2-1-1 Toyota-cho, Kariya-shi, Aichi Pref. (56) References Japanese Patent Publication No. 37-7540 (JP, B1) Japanese Utility Model Publication No. 43-18930 (JP, Y1) (58) Field surveyed (Int. Cl. ⁶ , DB name) F04B 27 / 08

Claims (31)

(57) [Claims] 1. A swash plate (9) mounted on a rotating shaft (6) in a crank chamber (5) with rotation of the rotating shaft (6).
And a piston of a compressor that reciprocates between a top dead center and a bottom dead center in a cylinder bore (2a) through a shoe (12), wherein the piston (11) is in contact with an inner peripheral surface of the cylinder bore (2a). An outer peripheral surface that is in sliding contact with the piston (11)
A groove (17; 44; 46) extending in the direction of the axis (S) of the piston is provided, and the piston (11) is viewed from the side where the rotation direction (R) of the rotation shaft (6) is the clockwise rotation direction. Rotary axis (6)
A virtual line (M) passing through the center axis (L) of the piston (11) and the center axis (S) of the piston (11) is virtually provided, and an intersection (P1) between the straight line (M) and the outer peripheral surface of the piston (11) is provided. , (P
When the point (P1) farthest from the center axis line (L) of the rotating shaft (6) in the 2) is set at 12 o'clock, the groove (17; 44; 46)
Is at 12 o'clock and 6 on the circumference of the piston (11).
The piston of the compressor provided at a position other than the hour position. 2. The groove (17; 44; 46) guides lubricating oil existing between the outer peripheral surface of the piston (11) and the inner peripheral surface of the cylinder bore (2a) into the crank chamber (5). The piston of a compressor according to claim 1, wherein the piston (11) is exposed from the inside of the cylinder bore (2a) into the crank chamber (5) at least when the piston (11) moves to the bottom dead center. 3. The groove (17; 44; 46) is for guiding lubricating oil existing between the outer peripheral surface of the piston (11) and the inner peripheral surface of the cylinder bore (2a) into the close chamber (5). 2. The compressor piston according to claim 1, wherein the piston is always directly connected to the crankcase. 4. The groove (17; 44; 46) is provided on the peripheral surface of the piston (11) at a position other than a position where the groove is strongly pressed against the inner peripheral surface of the cylinder bore (2a). The piston of the compressor according to claim 1. 5. The compression according to claim 1, wherein said groove (17; 44; 46) is provided in a range (E) from 9 o'clock to 10:30 on the peripheral surface of the piston (11). Machine piston. 6. The compression according to claim 1, wherein said groove (17; 44; 46) is provided in a range (E3) from 7.30 to 9 on the peripheral surface of the piston (11). Machine piston. 7. The lubricating oil present between the outer peripheral surface of the piston (11) and the inner peripheral surface of the cylinder bore (2a) is such that compressed refrigerant gas in the cylinder bore (2a) is removed from the outer peripheral surface of the piston (11). It prevents leakage into the crank chamber (5) through the space between the inner surface of the cylinder bore (2a) and the close contact force between the outer surface of the piston (11) and the inner surface of the cylinder bore (2a). And the depth of the groove (17; 44; 46) is:
2. The piston of the compressor according to claim 1, wherein the piston is set to a depth such that the adhesion can be reduced as far as possible without impairing the function of the lubricating oil that suppresses leakage of the refrigerant gas. 3. 8. The compressor piston according to claim 1, wherein said piston is hollow. 9. A piston (1) in said groove (17; 44; 46).
The inner bottom surface of the end on the tail side of (1) forms an inclined surface that smoothly connects to the outer peripheral surface of the piston (11).
A piston of a compressor according to claim 1. 10. The outer peripheral surface of the piston (11) further comprises:
A collecting means (16) for scraping the lubricating oil adhered to the inner peripheral surface of the cylinder bore (2a) is provided at a position which is not always exposed from the inside of the cylinder bore (2a), and the lubricating oil in the collecting means (16) is 2. The compressor piston according to claim 1, wherein the piston is guided into the crank chamber (5) via a groove (17) extending in the direction of the axis (S) of the piston (11). 3. 11. A compressor piston according to claim 10, wherein said recovery means is a recovery groove (16) formed on an outer peripheral surface of said piston (11). 12. The piston of a compressor according to claim 11, wherein said recovery groove (16) extends along a circumferential direction of said piston (11). 13. The compressor piston according to claim 12, wherein said recovery groove (16) has a ring shape. 14. A groove (17) extending in the direction of the axis (S) of the piston (11) is separated from the recovery groove (16), and both grooves (16) and (17) are formed on the outer periphery of the piston (11). 12. The compressor piston according to claim 11, wherein the piston communicates via a narrow clearance (K) between the surface and the inner peripheral surface of the cylinder bore (2a). 15. The compressor piston according to claim 11, wherein the groove (17) extending in the direction of the axis (S) of the piston (11) is connected to the recovery groove (16). 16. A groove (17) extending in the direction of the axis (S) of the piston (11) except for a position on the peripheral surface of the piston (11) which is strongly pressed against the inner peripheral surface of the cylinder bore (2a). 12. The piston of the compressor according to claim 11, wherein the piston is provided at an inclined position. 17. When the piston (11) is viewed from the side where the rotation direction (R) of the rotation shaft (6) is in the clockwise rotation direction, the center axis (L) of the rotation shaft (6) and the piston ( A straight line (M) passing through the center axis (S) of (11) is virtually provided, and among the intersections (P1) and (P2) of the straight line (M) and the outer peripheral surface of the piston (11), When the point (P1) farther from the center axis (L) of (6) is set to the position of 12:00,
17. The compressor piston according to claim 16, wherein the groove (17) is provided on the peripheral surface of the piston (11) at positions other than the 12 o'clock position, the 3 o'clock position, and the 6 o'clock position. . 18. A housing (1, 2, 3) having a cylinder bore (2a) and a crank chamber (5), a rotating shaft (6) rotatably supported by the housing (1, 2, 3), and a crank. A swash plate (9) mounted on a rotating shaft (6) in a chamber (5), and a piston (11) housed in a cylinder bore (2a). In a piston type compressor in which a piston (11) reciprocates between a top dead center and a bottom dead center in a cylinder bore (2a) via a plate (9) and a shoe (12), the piston (11) is a cylinder bore. (2a) has an outer peripheral surface that is in sliding contact with the inner peripheral surface. One of the outer peripheral surface of the piston (11) and the inner peripheral surface of the cylinder bore (2a) has a piston (1
A groove (17; 44; 46) extending in the direction of the axis (S) of 1) is provided, and the piston (11) is viewed from the side where the rotation direction (R) of the rotation shaft (6) is the clockwise rotation direction. And the rotation axis (6)
A virtual line (M) passing through the center axis (L) of the piston (11) and the center axis (S) of the piston (11) is virtually provided, and an intersection (P1) between the straight line (M) and the outer peripheral surface of the piston (11) is provided. , (P
When the point (P1) farthest from the center axis line (L) of the rotating shaft (6) in the 2) is set at 12 o'clock, the groove (17; 44; 46)
Is on the outer peripheral surface of the piston (11) or the cylinder bore (2a)
A piston-type compressor provided on the inner peripheral surface of the vehicle at a position other than the 12 o'clock position and the 6 o'clock position. 19. The piston (11), wherein the groove (17; 44; 46) is
In order to guide the lubricating oil existing between the outer peripheral surface of the cylinder bore and the inner peripheral surface of the cylinder bore (2a) into the crank chamber (5), when the piston (11) moves at least to the bottom dead center, the cylinder bore (2a) Exposed in the crankcase (5) from the
19. The piston type compressor according to item 18. 20. The groove (17; 44; 46) includes a piston (11).
20. The piston-type compressor according to claim 19, wherein the piston-type compressor is provided at a position other than a position where it is strongly pressed against an inner peripheral surface of the cylinder bore (2a). 21. The groove (17; 44; 46) has a piston (11).
19. The piston type compressor according to claim 18, wherein the piston type compressor is provided in a range (E) from 9:00 to 10:30 on the peripheral surface of the piston. 22. The groove (17; 44; 46) is provided with a piston (11).
19. The piston-type compressor according to claim 18, wherein the piston-type compressor is provided in a range (E3) from 7:30 to 9:00 on the peripheral surface of the piston. 23. Lubricating oil existing between the outer peripheral surface of the piston (11) and the inner peripheral surface of the cylinder bore (2a) is formed by compressing refrigerant gas in the cylinder bore (2a) with the outer peripheral surface of the piston (11). Leakage into the crank chamber (5) through the space between the inner surface of the cylinder bore (2a) and the piston (11)
Between the outer peripheral surface of the cylinder bore and the inner peripheral surface of the cylinder bore (2a). The depth of the groove (17; 44; 46) 19. The piston type compressor according to claim 18, wherein the depth is set so as to reduce the adhesion as much as possible without impairing the function. 24. An inner bottom surface at an end of the groove (17; 44; 46) on the tail side of the piston (11) forms a slope which is smoothly connected to an outer peripheral surface of the piston (11).
19. The piston type compressor according to item 18. 25. An outer peripheral surface of the piston (11) further comprises:
A collecting groove (16) for collecting the lubricating oil attached to the inner peripheral surface of the cylinder bore (2a) is provided at a position that is not always exposed from the inside of the cylinder bore (2a), and the lubricating oil in the collecting groove (16) is Groove (1) extending in the axis (S) direction of the piston (11)
20. The device according to claim 19, wherein said device is guided into said crankcase via said 7).
A piston-type compressor according to item 1. 26. The piston type compressor according to claim 25, wherein the recovery groove (16) extends along the circumferential direction of the piston (11) and has a ring shape. 27. A groove (17) extending in the direction of the axis (S) of the piston (11) is separated from the recovery groove (16), and both grooves (16) and (17) are formed on the outer periphery of the piston (11). 26. The piston-type compressor according to claim 25, wherein the piston-type compressor communicates via a narrow clearance (K) between the surface and the inner peripheral surface of the cylinder bore (2a). 28. A cylinder bore (2a) having a groove (17) extending in the axis (S) direction of the piston (11) instead of or in addition to the outer peripheral surface of the piston (11).
26. The piston type compressor according to claim 25, formed on the inner peripheral surface of the piston. 29. A piston type compressor according to claim 25, wherein said piston (11) is hollow. 30. The piston is a single-headed piston (11) having a head at one end, and the driving body includes a swash plate (9) mounted on a rotating shaft (6) so as to be integrally rotatable. Shoe (12) between plate (9) and tail of piston (11)
26. The piston type compressor according to claim 25, wherein a rotary motion of the swash plate (9) is converted into a reciprocating motion of the piston (11) via the shoe (12). 31. The piston is a single-headed piston (11) having a head at one end, and the driving body includes a swash plate (9) tiltably supported on a rotating shaft (6). (9)
Changes the inclination angle with respect to the rotating shaft (6) according to the difference between the pressure in the crank chamber (5) and the pressure in the suction chamber (3a),
26. The piston type compressor according to claim 25, wherein the displacement is adjusted by changing the movement stroke of the piston (11) according to the inclination angle of the swash plate (9).