JPH08282256A - Swash plate type compressor - Google Patents

Abstract

PURPOSE: To surely and smoothly regulate rotation of a piston by sliding a swash plate between both shoes to slide in the circumferential direction, and rotating a rotation lock part on an outer surface of an engagement part facing a casing about a shaft in the case where a piston rotates to apply it to smoothly get in surface-contact with a recessed curvature surface. CONSTITUTION: A recessed part 83 having an arc-shaped recessed surface 83a as a curvature surface is formed on an inner circumferential surface of a casing 12 facing a rotation lock part 82 of a piston 23, and both abutting parts 82b and the arc-shaped recessed surface 83a are respectively disposed to be apart from each other for a specified distance L1. In the case of reciprocating the piston 23 by rotating an inclined swash plate, a flat surface of an outer edge part of the swash plate slides to move between both shoes, and even in the case where rotating force is applied to the piston 23 in a direction of D through both shoes, an arc-shaped protruded surface 82a smoothly gets in surface-contact with the arc-shaped recessed surface 83a to regulate rotation of the piston 23, thereby lubricating oil flows in to form oil film easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type compressor, and more particularly to improvement of a piston detent structure for a swash plate type compressor.

[0002]

2. Description of the Related Art As a compressor used in an air conditioner for an automobile, a fixed capacity swash plate type compressor having a swash plate whose inclination angle with respect to a drive shaft is fixed, and an inclination angle with respect to a drive shaft for adjusting a discharge refrigerant amount. There is known a variable capacity swash plate type compressor having a swash plate that is variable.

For example, the variable capacity swash plate type compressor has a drive shaft which is rotationally driven by an engine transmitted through a belt, a pulley and the like, and a disc-shaped swash plate which is mounted on the drive shaft in a variable inclination angle. When the drive shaft is rotated, the swash plate in a tilted state rotates together with the drive shaft while performing a so-called rasping motion. Further, this variable displacement swash plate compressor has a plurality of cylinder chambers and pistons that slide along the cylinder chambers, but the rotating swash plate and pistons described above are connected via a piston rod. There is one that is directly connected without sliding.

In such a compressor in which the swash plate and the piston are directly connected to each other, each piston has a piston head that reciprocates in the cylinder chamber, and a cross-section approximately U that engages the swash plate.
It is composed of a letter-shaped engaging portion. Then, for example, substantially hemispherical shoes are fitted in two spherical concave portions formed at opposite positions on both inner surfaces of the engaging portion, and the both flat surfaces of the swash plate are sandwiched by these shoes. Here, the sliding surfaces formed on both the front and back surfaces of the outer edge portion of the swash plate are in sliding contact with the corresponding flat portions of the shoe, and the piston has a spherical concave portion formed in its engaging portion. , Sliding contact with the spherical surface of the corresponding shoe. In this way, the piston is slidably connected to the swash plate at its engaging portion.

Therefore, when the drive shaft is rotated to rotate the inclined swash plate, when the piston slidably connected to the swash plate makes sliding contact with the outer edge of the rotating swash plate closest to the cylinder chamber side. Is moved to the top dead center position, and is moved to the bottom dead center position when it comes into sliding contact with the outer edge of the rotating swash plate farthest from the cylinder chamber side. That is, by slidably contacting the swash plate inclined with respect to the drive shaft and the piston whose sliding direction is regulated by the cylinder chamber, the swash plate's rubbing rotary motion is converted into a reciprocating motion of the piston. Will be.

When the piston reciprocates in this manner, the refrigerant sucked from the suction port in the compressor is compressed and then discharged to the discharge port, and the refrigerant circulates to function as a compressor.

By the way, in the case of reciprocating the piston by rotating the inclined swash plate, as shown in FIG.
From the swash plate to the piston 123,
A force in the axial direction acts on the piston 123
Is on the top dead center side or bottom dead center side along the cylinder chamber,
It slides and moves in the direction perpendicular to the paper surface of FIG. In addition, in FIG.
It is the figure which looked at piston 123 from the direction back. In this case, the flat surface of the outer edge portion of the swash plate moves at high speed between the shoes 71 and 72 in the direction of arrow A and slides on each other, so that the piston 12 passes through these shoes 71 and 72.
Since the force for rotating 3 in the B direction works, it is necessary to regulate the rotation of this piston.

Therefore, as shown in FIG. 4, the piston 1
A rectangular parallelepiped convex portion 124 is provided on the outer peripheral surface of the casing 23, and a sliding groove 127 is formed on the inner peripheral surface of the casing 112 so as to engage with the convex portion 124 so as to be movable in the axial direction. Stop the rotation of 123. By doing so, it is possible to prevent a situation in which the piston 123 is largely rotated and a part thereof locally contacts the swash plate, and abrasion powder is generated at that time, which adversely affects the piston operation. .

[0009]

However, in such a conventional piston detent structure, the projections 124 and the sliding grooves 127 each having a rectangular parallelepiped shape are machined in the respective circumferential end faces 124a, 124b. , 127a, 127b
In addition to the processing of the top part 124c and the bottom part 127c,
Since all of them are flat machining, many tools are fed, and the same machining is required for the number of pistons arranged, for example, 5 places, resulting in an increase in man-hours and a significant cost increase.

Further, a certain clearance is required between the convex portion 124 and the sliding groove 127 in order not to give an extra resistance to the reciprocating movement of the piston. In this case, the end faces of the convex portion 124 and the sliding groove 127 may be abutted against each other in an impact, which may cause abnormal noise.

On the other hand, as shown in FIG. 5, on the rear surface of the piston 133 facing the inner peripheral surface of the casing 112, the rotation range of the piston 133 is restricted so that the piston 13 is prevented.
3 is provided with a rotation-regulating convex curved surface 134 for avoiding interference between the engaging portion with the swash plate and the peripheral edge of the swash plate. By making it larger than the radius of curvature Rp of the surface and smaller than the inner radius of curvature R2 of the inner peripheral surface of the casing 112, the inner peripheral surface of the casing 112 and the rotation-regulating convex curved surface 134 are brought into a state of near surface contact. There is a device in which noise and wear are suppressed by interfering with each other (see JP-A-6-346844).

However, this Japanese Patent Laid-Open No. 6-34684
Even the piston detent structure described in Japanese Patent No. 4 has the following drawbacks. That is, when the piston 133 is rotated to the position shown by the chain double-dashed line in FIG. 5 due to the rotation of the swash plate, further rotation is restricted, but in this case, the rotation with the inner peripheral surface of the casing 112 is restricted. Rather than the interference with the movement-regulating convex curved surface 134 in a state of being close to surface contact, in practice, the end 135 of the rotation-regulating convex curved surface 134
Only a hits the inner peripheral surface of the casing 112 by an edge,
There is a problem that the rotation restricting convex curved surface 134 does not serve as a curved surface. In this case, there is a possibility that abrasion powder will be generated, the rotational play of the piston will gradually increase, and abnormal noise will also increase.

Further, the splash of the lubricating oil in the crank chamber due to the rotation of the swash plate is blown off in the direction of arrow C by centrifugal force,
Although it is splashed toward the rotation restricting convex curved surface 134, the end 135a is rotated to the position of the reference numeral "135a '" and hits the edge on the inner peripheral surface of the casing 112, so that the lubricating oil is dammed up. There is also a problem that an oil film cannot be easily formed from this portion and the sliding portion is not sufficiently lubricated.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to reliably and smoothly rotate a piston at low cost without causing abnormal noise or wear. It is to provide a swash plate compressor that can be regulated.

[0015]

The present invention for achieving the above object comprises a drive shaft rotatably mounted on a casing, and a swash plate provided in a crank chamber of the casing and connected to the drive shaft. , A plurality of pistons axially reciprocated in the cylinder chamber through a plurality of cylinder chambers formed in the casing and shoes arranged in contact with both front and back surfaces of the swash plate by rotation of the swash plate In a swash plate compressor having a piston, the piston includes a piston head that reciprocates in the cylinder chamber and an engaging portion that engages with the swash plate through a shoe, and the outer surface of the engaging portion of the piston that faces the casing. , A rotation preventing portion having a convex curved surface having a radius of curvature larger than the radius of the piston head is formed, and contact portions having a predetermined radius of curvature are formed at both circumferential ends of the convex curved surface. Then, on the inner peripheral surface of the casing facing the rotation preventing portion of the piston, a concave portion having a concave curved surface having an inner curvature radius larger than the piston head radius and smaller than the curvature radius of the convex curved surface of the rotation preventing portion is formed. The swash plate compressor is characterized in that it is provided with a predetermined distance from both abutting portions of the detent portion of the piston.

Further, the concave curved surface of the concave portion of the casing formed facing the rotation preventing portion of the piston forms all or part of the inner surface of the cylinder formed along the entire inner surface of the casing. You may comprise.

Further, it is preferable to set the distance between both abutting portions of the detent portion of the piston to be 0.9 times or more the diameter of the piston head.

[0018]

In the present invention thus constructed, the driving shaft is rotated and slanted by the swash plate in a tilted state.
A force is applied to the piston in the axial direction to reciprocate. In this way, when converting the rotational motion of the inclined swash plate into the reciprocating motion of the piston, the swash plate causes the piston to reciprocate. , Axial force acts through the shoe,
The piston reciprocates along the cylinder chamber.

In this case, since the swash plate slides between the shoes in the circumferential direction at a high speed, a force for rotating the piston around the piston axis is exerted via these shoes.
Then, when the piston is rotated, the rotation preventing portion formed on the outer surface of the engagement portion of the piston is rotated around the piston axis, and the contact portion of the rotation preventing portion is smoothly curved to the concave curved surface of the concave portion. Since it is abutted so that it comes into surface contact with a curved surface,
The rotation of the piston is regulated reliably and smoothly.

Further, the lubricating oil blown off by centrifugal force due to the rotation of the swash plate does not come into edge contact with the inner peripheral surface of the casing due to the rotation preventing portion of the piston, so that the lubricating oil flows in the circumferential direction from the surface-contacting portion on the curved surface. As a result, an oil film is easily formed.
Further, lubricating oil also flows in from the axial direction, and an oil lubrication space is formed between the convex curved surface of the rotation preventing portion of the piston and the concave curved surface of the concave portion of the casing. It functions as an oil reservoir for the inflowing lubricating oil. As a result, the sliding portion is sufficiently lubricated.

Due to such a smooth curved surface contact, the piston is prevented from rotating and the sliding portion is sufficiently lubricated to prevent abnormal noise and wear.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic cross-sectional view of a variable displacement swash plate compressor according to an embodiment of the present invention, FIG. 2 (A) is a front view of a piston shown in FIG. 1, and FIG. 2 (B) is a left side view of the same. 3A and 3B are views for explaining the piston detent structure.

The variable capacity swash plate compressor of the present embodiment shown in FIG. 1 has a cylindrical casing 12 having a rear head 10 and a front head 11 attached to both ends at each end thereof. The cylinder chamber 13,
A crank chamber 14 is provided. The rear head 10
Is attached to the right end of the casing 12 via the valve seat 16 and is integrally connected with the front head 11 provided at the left end of the casing by a bolt (not shown). Valve forming plates (not shown) are provided on both surfaces of the valve seat 16, and a retainer 18 is attached to the discharge valve side.

The front head side of the drive shaft 19 provided through the casing 12 penetrates through the front head 11 and is projected, and a pulley 20 is connected to the end portion. The electromagnetic clutch 2 is provided between the drive shaft 19 and the pulley 20.
7 is provided, and the electromagnetic clutch 27 is turned on when cooling is required, and the rotation of the engine is transmitted via a belt (not shown) mounted on the pulley 20. If the electromagnetic clutch 27 is turned off when cooling is not required, the connection between the engine and the compressor is cut off, the drive shaft 19 does not rotate, and only the pulley 20 idles.

A plurality of cylinder chambers 13 are provided in the casing 12 at equal intervals in the circumferential direction, and pistons 23 are installed in the respective cylinder chambers 13. Each of these pistons 23 has a piston head 23a that reciprocates in the cylinder chamber 13, and an engaging portion 23b that has a substantially U-shaped cross section and that engages with the swash plate 25 via the substantially hemispherical shoes 71 and 72. Consists of. The shoe 7 is attached to the spherical concave portions 23c and 23d formed so as to face the inner surfaces on both sides of the engaging portion 23b.
The spherical parts of 1, 72 are fitted, and these shoes 71, 7
Both the front and back surfaces of the swash plate 25 are sandwiched between the two flat portions and slidably contact each other.

The left side portion of the drive shaft 19 in the figure is supported by the front head 11 via a bearing 26.
A rotary member 28 that is rotated by the drive shaft 19 is provided inward. A sleeve 29 is provided on the inner end side of the rotating member 28 so as to be slidable in the axial direction. The outer peripheral surface of the sleeve 29 is arcuate, and the arcuate outer surface is slantably inclined. The concave inner surface of the plate 25 is in contact.
The swash plate 25 and the rotary member 28 have links 30b,
30a is provided so that both links 30b and 30a are
The rotation member 28 is connected by the long hole 31 and the pin member 32.
Is rotated so that the swash plate 25 is rotated.

Therefore, this swash plate 25 is
With the axial movement of 9, the pin member 32 is tilted about the fulcrum, and the tilt angle (which is the tilt angle with respect to the plane orthogonal to the axis of the drive shaft 19) can be adjusted. The swash plate 25 has a maximum inclination angle at the position where the balancer 25a of the swash plate 25 contacts the rotating member 28 (state of FIG. 1).

In this variable displacement swash plate compressor, a control valve Cv is provided in the rear head 10, and the pressure in the crank chamber 14 is adjusted according to the suction pressure of the returning refrigerant to change the angle of the swash plate 25. The amount of refrigerant discharged from the compressor is adjusted so that the suction pressure of the compressor is constant.

A suction port 33 and a discharge port 34 are provided in the rear head 10, and the suction port 33 has:
The return refrigerant from the evaporator flows in, and this refrigerant is sucked against the elastic closing force of the intake valves formed in the valve forming plate (not shown) on the left surface of the valve seat 16 in the drawing in the circumferential direction. It is designed to sequentially flow into the cylinder chamber 13 in the suction process through the port 33a, and the discharge port 34
The refrigerant compressed by the piston is in the valve seat 1
Discharge is performed against the elastic closing force of a plurality of discharge valves formed in the circumferential direction on a valve forming plate (not shown) on the right side surface in FIG.

In this embodiment, in particular, as shown in FIGS. 2A and 2B, a detent portion 82 is provided on the outer surface of the engaging portion 23b of the piston 23, and the detent portion 82 is convex. A circular arc convex surface 82a is formed as a curved surface. Further, abutting portions 82b having a predetermined radius of curvature r are formed at both circumferential ends of the arcuate convex surface 82a.

On the other hand, as shown in FIG. 3, a concave portion 83 having a circular arc concave surface 83a as a concave curved surface is formed on the inner peripheral surface of the casing 12 facing the detent portion 82 of the piston 23. Then, both contact portions 82b of the rotation preventing portion 82 of the piston 23 and the arcuate concave surface 83a of the inner peripheral surface of the casing 12 are arranged so as to be separated from each other by a predetermined distance L1. Therefore, when the piston 23 is reciprocated by rotating the inclined swash plate 25, the flat surface of the outer edge portion of the swash plate 25 slides between the shoes 71 and 72, and both shoes 71 , 72, even if a force to rotate the piston 23 in the D direction shown in FIG. 3 acts, the arcuate convex surface 82a of the rotation stopping portion 82 makes a smooth curved surface contact with the arcuate concave surface 83a of the concave portion 83. The rotation of the piston 23 can be restricted. Also,
Since the edge does not hit the inner peripheral surface of the casing, the lubricating oil easily flows in and an oil film is easily formed.

Here, as shown in FIG. 3, the piston 2
The distance L2 between both contact portions 82b of the detent portion 82 of No. 3
Is set to 0.9 times or more the diameter of the piston head. More specifically, when the piston 23 is rotated left and right, both contact portions 82b of the rotation stopping portion 82 come into contact with the arcuate concave surface 83a of the concave portion 83 of the casing 12,
It is preferable to set the distance L2 between the left and right contact points to be 0.9 times or more the diameter Dp of the piston head 23a. With this configuration, the rotation preventing portion 82 of the piston 23 is formed in the concave portion formed on the inner peripheral surface of the casing 12 even if the friction coefficient thereof is considered to be the maximum in a range in which all lubrication states are assumed in the practical range. 8
It is possible to surely avoid a situation in which 3 is caught.

The radius of curvature r of the contact portion 82b is positively rounded (for example, radius of curvature of 1 mm or more) rather than so-called thread chamfering so that abnormal noise and wear can be reduced to an allowable range in terms of quality. However, it does not necessarily have to have a circular arc shape as long as it has a predetermined radius of curvature r at the contact point with the casing 12.
However, in order to secure an oil lubrication space described later, there is an upper limit to the size of the radius of curvature r.

As shown in FIG. 3, the radius of curvature R1 of the arcuate convex surface 82a of the detent portion 82 is set to a value larger than the piston head radius Rp of the piston 23. Also,
The arcuate concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the casing 12 is formed so as to have an inner radius of curvature R2 that is larger than the piston head radius Rp and smaller than the radius of curvature R1 of the convex curved surface 82a. The radius of curvature R1 of the arcuate convex surface 82a can be infinitely increased, that is, the arcuate convex surface 82a can be formed as a flat surface.

In this way, the oil lubrication space 85 can be formed in the portion surrounded by the arcuate convex surface 82a of the piston 23 and the arcuate concave surface 83a of the casing 12. Then, the splash of the lubricating oil in the crank chamber, which is blown off by the centrifugal force by the rotation of the swash plate, is as described above.
The oil-lubricating space 85 serves as a reservoir for the lubricating oil that has flowed in in the circumferential direction from between the contact portion 82b of the rotation-stopping portion 82 of the piston 23 and the arcuate concave surface 83a of the casing 12 and also in the axial direction. Can function. As a result, the sliding portion can be sufficiently lubricated.

The axial length of the concave portion 83 formed on the inner peripheral surface of the casing 12 is at least the piston 23.
The reciprocating motion of the piston 23 is set to be equal to or longer than the length that does not interfere with the movement of the rotation stopping portion 82 of the piston 23. Also,
The above-mentioned (curvature) radii R1, R2, Rp and distances L1, Lp
2 is adjusted appropriately based on the design specifications.

Next, the operation of this embodiment will be described. When the electromagnetic clutch 27 is turned on and the drive shaft 19 is rotated by the engine via the belt and the pulley, the rotating member 28 is rotated accordingly, and the swash plate 25 is also connected via both the links 30a and 30b and the pin member 32. Rotate. When the swash plate 25 is tilted with respect to the drive shaft 19, the swash plate 25 is rotated in a rasping motion, and the piston 23 is reciprocally moved in accordance with this, and refrigerant is sucked, compressed, and discharged.

Here, when the heat load in the cooling cycle is large, the pressure of the return refrigerant returns at a relatively high pressure. In this case, a relatively high suction pressure is introduced into the crank chamber 14 by the action of the control valve Cv, so that the internal pressure becomes substantially equal to the suction pressure. Therefore, the pressure difference between the front and the rear of the piston 23 in the suction process is almost eliminated, and the piston 23 can be smoothly retracted in the cylinder chamber 13 of the cylinder 15, and the stroke of the piston 23 increases. When compression is performed in this state, the amount of discharged refrigerant increases, the flow rate of the refrigerant circulating in the cooling cycle increases, and the appropriate refrigerant flow rate according to the heat load is discharged again, and the suction pressure of the compressor gradually decreases. Finally, the suction pressure will be kept constant.

On the other hand, when the heat load in the cooling cycle is small, the pressure of the return refrigerant is not sufficient to obtain a superheat amount, and the refrigerant is returned at a low pressure. In this case, by the action of the control valve Cv, the high-pressure refrigerant compressed by the piston 23 and guided to the discharge port 34 is introduced into the crank chamber 14, and the internal pressure of the crank chamber 14 is increased. As a result, the moment of the force applied to each of the plurality of pistons 23 centering on the pin 32 is different, and each piston 2
The pressure balance before and after 3 changes, and the inclination angle of the swash plate 25 decreases.

By the way, the suction, compression, and discharge of the refrigerant can be reciprocated by applying a force in the axial direction to the piston 23 by slewing rotation of only the inclined swash plate 25, as described above. But in this case,
The flat surface of the outer edge of the swash plate 25 slides between the shoes 71 and 72 at a high speed in the circumferential direction, and these shoes 71 and 72
A force for rotating the piston 23 around the piston axis acts via 72.

Such a rotating force is due to a difference in local sliding condition when sliding while pressing the flat surface of the shoe, a difference in sliding speed due to a difference in distance from the center of rotation, and the like. It is thought to occur in. For example, when the piston 23 is rotated in the D direction shown in FIG. 3, the detent portion 82 provided on the outer surface of the engaging portion 23b of the piston 23 is rotated around the piston axis, and the detent portion 82 is rotated. Since the abutting portion 82b abuts on the arcuate concave surface 83a of the concave portion 83 so as to make a smooth curved surface contact, the rotation of the piston 23 can be reliably and smoothly regulated.

Further, the splash of the lubricating oil in the crank chamber, which is blown off by the centrifugal force due to the rotation of the swash plate, does not cause the rotation stopping portion 82 to hit the inner peripheral surface of the casing at the edge, so that the surface contact portion is a curved surface. To flow in the circumferential direction to facilitate formation of an oil film. Further, the lubricating oil also flows in from the axial direction, and further, the oil lubrication space 85 can be formed in the portion between the arc convex surface 82a of the piston 23 and the arc concave surface 83a of the casing 12, so that the oil lubricating space is formed. 8
5 can function as an oil reservoir for the inflowing lubricating oil. As a result, the sliding portion can be sufficiently lubricated.

Therefore, it is possible to prevent abnormal noise and wear by preventing rotation of the piston due to such smooth curved surface contact and sufficient lubrication of the sliding portion.

Further, the rotation preventing portion 82 formed on the piston 23 and the concave portion 83 formed on the casing 12
Can be easily processed, and the number of steps can be reduced, and the product cost can be reduced.

Furthermore, the detent portion 82 is a portion that slightly protrudes from the outer surface of the engaging portion 23b of the piston 23, and can sufficiently fulfill the function of detent of the piston 23. As a result, the amount of the lubricating space 85 formed between the circular arc convex surface 82a and the circular arc concave surface 83a of the casing 12 is reduced as compared with the conventional piston engaging portion (see FIG. 5). As a result, the weight of the piston can be reduced. Therefore, it is possible to reduce the load on the high-speed reciprocating motion of the piston.

It should be noted that the embodiments described above are provided for facilitating the understanding of the present invention and not for limiting the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents within the technical scope of the present invention.

For example, in the above-described embodiment, the arcuate concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the casing 12.
The center of the inner radius of curvature R2 is not on the central axis of the drive shaft 19, but is set at a position which is close to the piston shaft by a predetermined distance from the drive shaft 19. That is, the arcuate concave surfaces 83a centering on different central axes are formed so as to face the detent portions 82 of each piston 23. However, the present invention is not limited to such a configuration, and the rotation stopping portion 8 of each piston 23 is
2. The arcuate concave surface 83a of the concave portion 83 formed so as to face 2
However, it is also possible to form all or part of the inner surface of the cylinder formed along the entire inner surface of the casing 12. In this case, the circular arc concave surface 8
The central axis of 3a coincides with the central axis of the drive shaft 19. That is, the arcuate concave surface 83a may be machined over the entire circumference along the inner peripheral surface of the casing 12, or may be a portion that is not required to prevent piston rotation between the pistons when the casing 12 is molded. It is also possible to mold so as to allow the oil to escape and leave a portion of the casting surface, and to grind only the portion facing the rotation stopping portion 82 of each piston. With such an arcuate concave surface 83a of the concave portion 83, it is possible to machine the arcuate concave surface 83a for all pistons (for example, five pistons evenly arranged in the circumferential direction) at one time, and the number of machining steps is further increased. Can be reduced.

Although the variable capacity swash plate compressor has been described as an example, the contents of the present application can be applied not only to the variable capacity compressor but also to the fixed capacity swash plate compressor. Further, the piston can be applied to one having piston heads on both sides in the axial direction of the engaging portion with the swash plate.

[0049]

As described above, according to the present invention, when the swash plate slides between the shoes at a high speed in the circumferential direction, the piston is rotated through the shoes. The detent portion formed on the outer surface of the engagement portion of the piston facing the casing is rotated about the piston axis, and as a result, the detent portion formed on the piston is
The piston is rotated around the piston shaft, and the contact portion of the rotation preventing portion is brought into contact with the concave curved surface of the concave portion so as to smoothly come into surface contact with the curved surface, so that the rotation of the piston is reliably and smoothly regulated. be able to.

Further, the lubricating oil blown off by the centrifugal force due to the rotation of the swash plate does not come into contact with the inner peripheral surface of the casing due to the edge of the rotation preventing portion of the piston, so that the lubricating oil flows in the circumferential direction from the curved surface contact portion. As a result, an oil film is easily formed.
Further, the lubricating oil also flows in from the axial direction, and since an oil lubrication space can be formed in the portion surrounded by the convex curved surface of the rotation preventing portion of the piston and the concave curved surface of the concave portion of the casing, the oil lubricating space can be formed. The lubricating space can function as an oil sump for the lubricating oil that has flowed in. As a result, the sliding portion can be sufficiently lubricated.

Therefore, it is possible to prevent abnormal noise and wear by preventing the piston from rotating due to such smooth curved surface contact and sufficiently lubricating the sliding portion.

Moreover, both the rotation preventing portion formed on the piston and the concave portion formed on the casing are easy to process, and the number of steps can be reduced, and the product cost can be reduced.

Further, the anti-rotation portion is a portion that slightly protrudes from the outer surface of the engagement portion of the piston, and can sufficiently perform the anti-rotation function of the piston. Moreover, the convex curved surface of the piston and the casing As a result, the amount of the lubricating space formed in the portion surrounded by the concave curved surface is reduced as compared with the engaging portion of the conventional piston,
The weight of the piston can be reduced. Therefore, it is possible to reduce the load on the high-speed reciprocating motion of the piston.

Further, when the concave curved surface of the casing constitutes all or a part of the cylindrical surface formed over the entire circumference along the inner peripheral surface of the casing, the concave curved surface is machined for all the pistons at one time. It is also possible to further reduce the processing man-hour.

Further, if the distance between both abutting portions of the detent portion of the piston is set to be 0.9 times or more the diameter of the piston head, the friction coefficient will be within the range assuming all lubrication states in the practical range. Even if the maximum is taken into consideration, it is possible to surely avoid the situation where the rotation stopping portion of the piston is caught in the concave portion formed on the inner peripheral surface of the casing.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a variable capacity swash plate compressor according to an embodiment of the present invention.

2A is a front view of the piston shown in FIG. 1, and FIG. 2B is a left side view of the same.

FIG. 3 is a diagram illustrating a rotation stopping structure of a piston.

FIG. 4 is a view of a piston of a conventional swash plate compressor as viewed from the axial rear side thereof.

FIG. 5 is a view of a piston of a conventional swash plate compressor as viewed from the axial rear side thereof.

[Explanation of symbols]

12 ... Casing, 13 ... Cylinder chamber, 14 ... Crank chamber, 19 ... Drive shaft, 23 ... Piston, 23a ... Piston head, 23b ... Engaging part, 23c, 23d ... Spherical recessed part, 25 ... Swash plate, 71, 72 ... Shoe, 82 ...
Anti-rotation part, 82a ... Arc convex surface (convex curved surface), 82b ...
Abutting portion, 83 ... concave portion, 83a ... arc concave surface (concave curved surface), 85 ... oil lubrication space, L1, L2 ... distance, R1,
R2, r ... radius of curvature. Rp ... piston radius.

Claims (3)

[Claims] 1. A drive shaft (19) rotatably mounted on a casing (12), and a swash plate (19) provided in a crank chamber (14) of the casing (12) and connected to the drive shaft (19). 25), a plurality of cylinder chambers (13) formed in the casing (12), and a swash plate (2
A plurality of pistons (23) reciprocally moved in the axial direction inside the cylinder chamber (13) via shoes (71, 72) arranged in contact with both front and back surfaces of the swash plate (25) by the rotation of (5). ), The piston (23) engages the swash plate (25) through the piston head (23a) that reciprocates in the cylinder chamber (13) and the shoes (71, 72). A convex portion having a curvature radius (R1) larger than the piston head radius (Rp) on the outer surface of the engagement portion (23b) of the piston (23) facing the casing (12). The anti-rotation part (82) having the curved surface (82a) is provided, and the abutting part (82b) having a predetermined radius of curvature (r) is formed at both ends in the circumferential direction of the convex curved surface (82a). The casing (1) facing the detent (82) of (23)
The inner peripheral surface of (2) has a concave curved surface (R2) having an inner curvature radius (R2) larger than the piston head radius (Rp) and smaller than the curvature radius (R1) of the convex curved surface (82a) of the rotation stop (82). The slanted portion (83) in which the 83a) is formed is separated from both contact portions (82b) of the rotation stopping portion (82) of the piston (23) by a predetermined distance (L1). Plate compressor. 2. A concave curved surface (83) of a concave portion (83) of a casing (12) formed so as to face a detent portion (82) of a piston (23).
a) forms all or a part of an inner surface of a cylinder formed along the entire inner surface of the casing (12).
The swash plate compressor described. 3. The distance (L2) between both abutting portions (82b) of the detent portion (82) of the piston (23) is the diameter of the piston head (23a).
The piston detent structure for a swash plate compressor according to claim 1 or 2, which is 0.9 times or more of (Dp).