JP3285747B2 - Swash plate compressor - Google Patents

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 an improvement in a swash plate type compressor.

[0002]

2. Description of the Related Art A compressor used in an air conditioner for a vehicle includes a fixed displacement swash plate type compressor having a swash plate having a fixed inclination angle with respect to a shaft, and a variable inclination angle with respect to a shaft in order to adjust a discharge refrigerant amount. A variable displacement swash plate type compressor having a swash plate described above is known.

[0003] For example, the variable displacement swash plate compressor includes a shaft rotatably driven by an engine transmitted through a belt, a pulley, and the like, and a disk-shaped swash plate attached to the shaft at a variable inclination angle. When the shaft is rotated, the swash plate in the inclined state rotates together with the shaft while performing a so-called razor motion. Also, this variable capacity swash plate compressor
It has a plurality of cylinder chambers and pistons that slide along the cylinder chambers, but the above-mentioned rotating swash plate and pistons are directly slidably connected without a piston rod. There is.

In such a compressor in which a swash plate and a piston are directly connected, each piston has a head that reciprocates in a cylinder chamber and a neck having a substantially U-shaped cross section that engages with the swash plate. For example, approximately hemispherical shoes are fitted into two spherical concave portions formed at positions facing the inner surfaces on both sides of the neck, and both front and rear flat surfaces of the swash plate are sandwiched by these two shoes. Here, the sliding surfaces formed on both the front and back surfaces of the outer edge of the swash plate are in sliding contact with the corresponding flat surfaces of the shoes, and the pistons are fitted in the spherical concave portions formed on the neck thereof. Sliding contact with the spherical part of the shoe. In this way, the piston is slidably connected to the swash plate at its neck.

Therefore, when the inclined swash plate is rotated by rotating the shaft, the piston slidably connected to the swash plate is slidably in contact with the outer edge of the rotating swash plate closest to the cylinder chamber. The swash plate is moved to the top dead center position, and is moved to the bottom dead center position when the rotating swash plate comes into sliding contact with the outer edge farthest from the cylinder chamber side. That is, the sliding motion of the swash plate is converted into a reciprocating motion of the piston by bringing the swash plate inclined with respect to the shaft into sliding contact with the piston whose sliding direction is regulated by the cylinder chamber. Will be.

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

When the piston is reciprocated by rotating the inclined swash plate, FIG.
As shown in FIG.
An axial force acts through the piston 5, and the piston 133 slides along the cylinder chamber toward the top dead center or the bottom dead center in a direction perpendicular to the plane of FIG. FIG. 6 is a view of the piston 133 as viewed from the crankcase side in the axial direction. In this case, the flat surface of the outer edge portion of the swash plate moves at high speed between the two shoes 4 and 5 in the direction of arrow A and slides with each other. It is necessary to regulate the rotation of the piston in order to exert a force for rotating the piston in the B direction.

Therefore, as shown in FIG. 6, on the back surface of the piston 133 facing the inner peripheral surface of the casing 112,
A rotation restricting convex surface 134 is provided for restricting the rotation range of the piston 133 to avoid interference between the neck of the piston 133 and the peripheral edge of the swash plate, and the curvature radius R1 of the rotation restricting convex surface 134 is determined. , The radius of curvature Rp of the inner peripheral surface of the casing 112 is larger than the radius of curvature Rp of the peripheral surface of the piston.
In some cases, the piston 133 is prevented from rotating by making the inner peripheral surface of the casing 112 and the convex curved surface 134 for rotation restriction interfere with each other in a state close to surface contact by making the inner surface of the casing 112 smaller than 2 (Japanese Patent Application Laid-Open No. Hei 6 (1994) -6380). -346844). By doing so, it is possible to prevent a situation in which the piston 133 is largely rotated and a part thereof locally hits the swash plate, and at that time, abrasion powder is generated and adversely affects the piston operation. .

[0009]

However, such a conventional piston detent structure still has the following disadvantages. That is, as shown in FIG. 7A, a predetermined gap L0 is provided in design between the rotation regulating convex curved surface 134 of the piston 133 and the inner peripheral surface of the casing 112 opposed thereto. There is no problem if the piston 133 is reciprocated while maintaining this gap. However, as described above, actually, the rotation of the swash plate 2 causes the piston 133 to be moved by, for example, a two-dot chain line in FIG. The rotation is restricted to the position shown in the figure, and further rotation is restricted.
The piston 133 is reciprocated in a state where 5c is in contact with the inner peripheral surface of the casing 112. Accordingly, there is a problem that the edges of the axial ends 135a and 135b of the rotation regulating convex curved surface 134 and the inner peripheral surface of the casing 112 rub against each other, causing abrasion. Also, for example, the casing 1
When the piston 12 and the piston 133 are made of the same aluminum alloy, and the piston 133 is provided with a coating layer for improving the slidability, the coating layer is peeled off by rubbing and the same material comes into contact. Therefore, there is a possibility that the sliding resistance increases and the piston operation is adversely affected.

[0010] In particular, in the case of a single-headed piston 133 as shown in FIG. 7, as shown in FIG. 7 (B), in the compression step, the piston 133 causes the bending moment Ma due to the pressing force of the swash plate 2. In response to this, the swash plate 2 is tilted with respect to the axis as shown in the drawing, and further rotated until the swash plate 2 comes into contact with the inner peripheral surface of the casing 112 as shown in FIG. The edge and the inner peripheral surface of the casing 112 rub at almost one point, resulting in a great increase in wear. Also, as shown in FIG. 7C, immediately after the suction process is completed and the process proceeds to the compression process, the piston 133
Means that the bending moment M
As shown in the drawing, it is inclined with respect to the axis in response to b, so that the edge of the axial end 135a promotes wear.

On the other hand, the piston 133 caused by the rotation of the swash plate 2
Is regulated by the rotation regulating convex curved surface 134,
In this case, rather than the inner peripheral surface of the casing 112 and the rotation regulating convex curved surface 134 interfering with each other in a state close to surface contact, in practice, the circumferential end 1 of the rotation regulating convex curved surface 134
There is also a problem that the 35c alone hits the edge on the inner peripheral surface of the casing 112, and the rotation regulating convex curved surface 134 does not serve as a curved surface. In this case, abrasion powder is generated, and the rotation backlash of the piston gradually increases, and there is a possibility that abnormal noise may increase.

Further, the splash of the lubricating oil in the crank chamber due to the rotation of the swash plate 2 is blown off by the centrifugal force in the direction of arrow C shown in FIG. 6, and is splashed toward the rotation regulating convex curved surface 134. Since the directional end 135c is rotated to the position indicated by reference numeral "135c '" and hits the edge on the inner peripheral surface of the casing 112, the lubricating oil is blocked and does not enter from this portion, making it difficult to form an oil film. There is a possibility that lubrication of the sliding portion is not sufficient.

The present invention has been made in view of the above-mentioned various problems of the prior art, and it is an object of the present invention to reliably and smoothly regulate the rotation of a piston at low cost without causing wear. To provide a swash plate type compressor that can be used.

[0014]

The present invention for achieving the above object is specified as follows for each claim. The invention according to claim 1 includes a shaft rotatably mounted on a casing, a swash plate provided in a crank chamber in the casing and connected to the shaft, and a plurality of cylinder chambers formed in the casing. A swash plate compressor having a plurality of pistons axially reciprocated inside the cylinder chamber via shoes arranged in contact with the front and back surfaces of the swash plate by rotation of the swash plate, wherein the pistons are: The piston comprises a head reciprocating in the cylinder chamber, and a neck connected to the swash plate via the shoe. The piston rotates around its axis outwardly facing the inner surface of the casing of the neck of the piston. In this case, a detent portion is provided which has a contact surface which comes into contact with the inner surface of the casing and regulates the rotation thereof within a predetermined angle range, and an intersection between the contact surface and a plane including the axis of the piston is provided. It is characterized in that it comprises a convex curve outwardly with a predetermined radius of curvature.

In the invention specified in this manner, the piston is caused to reciprocate by applying an axial force to the swash plate in a state where the shaft is rotated and tilted by the sliding motion. When the rotational motion of the inclined swash plate is converted into the reciprocating motion of the piston as described above, an axial force acts on the piston from the swash plate via the shoe, and the piston moves along the cylinder chamber. Reciprocate. In this case, the swash plate slides at a high speed in the circumferential direction between the two shoes, so that a force for rotating the piston around the piston axis acts on both the shoes, but the swash plate is moved outside the neck of the piston. The contact surface of the detent portion formed on the side contacts the inner surface of the casing, and the rotation of the piston is regulated. Here, a shaft end having a roundness of a predetermined radius of curvature is formed at both ends in the axial direction of the detent portion, so that the piston reciprocates in a state where the contact surface of the detent portion is in contact with the inner surface of the casing. Even if it does, it slides smoothly at the shaft end. Therefore, unlike the conventional case, the edge of the axial end portion of the rotation preventing portion and the inner surface of the casing do not rub against each other, so that abrasion does not occur.

According to a second aspect of the present invention, in the swash plate type compressor according to the first aspect, the curve is formed by two axial end convex curves respectively formed at both axial end portions of the contact surface. It is characterized by having.

According to a third aspect of the present invention, in the swash plate type compressor according to the first aspect, the curve is formed by one axial center convex formed over substantially the entire axial length of the contact surface. It is characterized by having a curve.

According to a fourth aspect of the present invention, in the swash plate type compressor according to the first aspect, an intersecting line between the contact surface and a plane perpendicular to the axis of the piston is larger than a radius of the head. A circumferential center convex curve having a radius, and a circumferential end convex curve formed at both ends of the circumferential center convex curve and having a smaller radius of curvature than the circumferential center convex curve, facing the detent portion of the piston. The inner peripheral surface of the casing is provided with a concave portion formed with an abutted surface where rotation of the piston is restricted by abutting the abutting surface of the detent portion, and the abutting surface and the shaft of the piston are provided. The line of intersection with the plane perpendicular to the heart includes a concave curve having an inner radius of curvature larger than the head radius and smaller than the radius of curvature of the circumferential central convex curve.

In the invention specified in this manner, since the rounded peripheral ends are formed at both ends in the circumferential direction of the detent portion, when the piston tries to rotate around the piston axis, Since the peripheral end portion of the detent portion comes into contact with the abutted surface of the concave portion so as to make smooth surface contact, the rotation of the piston is reliably and smoothly regulated.

Further, since the lubricating oil blown off by the centrifugal force due to the rotation of the swash plate does not come into contact with the edge of the inner peripheral surface of the casing, the lubricating oil flows in a circumferential direction from a portion which comes into surface contact with the curved surface. As a result, an oil film is easily formed.
Lubricating oil also flows in from the axial direction, and an oil lubricating space is formed between the abutment surface of the detent part of the piston and the abutted surface of the concave part of the casing to provide sufficient lubrication. Done in

According to a fifth aspect of the present invention, in the swash plate type compressor according to the fourth aspect, the abutted surface includes:
It is characterized in that it forms all or a part of a cylindrical inner surface formed over the entire circumference along the inner peripheral surface of the casing. In the invention specified in this way, it is possible to process the abutted surfaces on all the pistons at one time.

According to a sixth aspect of the present invention, in the swash plate type compressor according to the fourth or fifth aspect, the distance between both ends in the circumferential direction of the contact surface is 0.9 times the diameter of the head. It is characterized by the above. In the invention specified in this way, the situation where the detent portion of the piston bites into the concave portion formed on the inner peripheral surface of the casing is reliably avoided.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a variable displacement swash plate type compressor according to an embodiment of the present invention.
(A) is a side view of the piston shown in FIG. 1, FIG.
(B) is a view of the piston as viewed from the crank chamber side in the axial direction. FIG. 3 is a view for explaining a piston detent structure.
Is an enlarged view of a portion indicated by E in FIG. 2A, and members common to those shown in FIGS. 6 and 7 are denoted by the same reference numerals.

The variable displacement swash plate type compressor shown in FIG. 1 has a cylinder block 21. A rear housing 20r is provided on the right end of the cylinder block 21, and a front housing 20f is provided on the left end. The two housings 20r and 20f are connected by a bolt V. The cylinder block 21 and the two housings 20r and 20f form a casing of the present invention.

At the center of the front housing 20f,
A through-hole 23 for inserting the shaft 1 is formed. A radial bearing 24 for rotatably supporting the shaft 1 is press-fitted into the through-hole 23, and an oil seal 25 is also disposed near the radial bearing 24. ing.

Between the inner wall of the front housing 20f and the cylinder block 21, a crank chamber 3 is provided.
A hinge mechanism K for transmitting the rotation of the shaft 1 to the swash plate 2 is provided.

The swash plate 2 is formed by separately forming a cast iron journal 2a and a high Young's modulus steel flat plate 2b by a screw N. That is,
The flat plate portion 2b of the swash plate 2 is made of a material having a high Young's modulus capable of withstanding a large compression reaction force, that is, a material having high mechanical strength such as tensile strength and bending rigidity, specifically, carbon steel, alloy steel, or the like. The material of the journal portion 2a to which relatively no force is applied is made of cast iron.

The hinge mechanism K has a base end fitted to the shaft 1 and a distal end 26a having an elongated hole 26b formed therein, and a rotating arm 26 having a distal end from the back surface of the journal 2a of the swash plate 2. A driven arm 29 protruding toward the portion 26a and having a hole corresponding to the elongated hole 26b;
And a pin 30 inserted through the elongated hole 26b.

A bush 28 repelled by springs B1 and B2 is provided on the shaft 1 so as to be slidable in the axial direction on the shaft 1. The outer surface of the bush 28 is formed at the center of the journal 2a of the swash plate 2. The journal portion 2a and the bush 28 are connected to each other by a pair of pins 31 projecting from the journal portion 2a along the center axis of the bush 28. I have. Therefore, the swash plate 2 can rotate about the pin 31 while being rotated by the shaft 1, that is, the swash plate 2 is inclined about the pin 31 as a fulcrum, and the inclination angle (with respect to a plane orthogonal to the axis of the shaft 1) (Referred to as an inclination angle).

A thrust bearing 31t is provided between the inner wall surface of the front housing 20f and the rotary arm 26.

The other end of the shaft 1 is connected to a cylinder block 2
1 and is rotatably supported by a radial bearing 31r. A thrust bearing 32 is provided on the end surface of the shaft 1.

In the cylinder block 21, a plurality of cylinder chambers 7 are provided at equal intervals in the circumferential direction, and a piston 6 is installed in each of the cylinder chambers 7. Each of these pistons 6 has a cylinder chamber 7 as shown in FIG.
This is a so-called single-head type having a head 6a reciprocating in the inside and a neck 6b having a substantially U-shaped cross section connected to the swash plate 2 via substantially hemispherical shoes 4 and 5. The piston 6 is connected to the cylinder block 21 and the two housings 20.
It is made of the same aluminum alloy as r and 20f, and has a coating layer (made of, for example, fluororesin) on the surface to improve the slidability during reciprocation of the piston.

The neck 6b has connecting portions 9 and 10, and opposing spherical concave portions 9s and 10s are formed on inner surfaces of both sides of the connecting portions 9 and 10. Further, the shoes 4 and 5 are fitted with the flat surfaces 4a and 5a smoothed so as to slide on the flat portion 2b of the swash plate 2 and the spherical concave portions 9s and 10s of the connecting portions 9 and 10, respectively. Spherical convex surfaces 4b and 5b. Flat surfaces 4a, 5 of these two shoes 4, 5
The flat surface 2b of the swash plate 2 is sandwiched between the front and back surfaces of the swash plate 2 so as to slidably contact with each other. The swash plate 2 and the piston 6 are connected to the shoes 4 and 5 so that a single spherical surface is formed by the spherical concave portions 9 s and 10 s regardless of the inclination angle of the swash plate 2. Are connected via.

A suction port 35 for sucking the refrigerant and a discharge port 36 for discharging the refrigerant are provided at one end surface of the silicide chamber 7, and the refrigerant flows to the suction port 35 and the discharge port 36. Is provided with a valve forming plate 37, 38 in which a plurality of suction valves and discharge valves for controlling the pressure are formed.

Returning refrigerant from the evaporator flows into the suction port 35 through the suction chamber 40, and is subjected to elastic closing force of a suction valve formed on the valve forming plate 37 on the left side of the valve plate 39 in the drawing. In contrast, it flows into the cylinder chamber 7 in the suction process. Further, the refrigerant compressed by the piston is discharged to the discharge port 36 against the elastic closing force of the discharge valve formed on the valve forming plate 38 on the right side of the valve plate 39 in the drawing. The discharge port 36 is guided to the discharge chamber 41.

Further, a control valve Cv for adjusting the pressure state in the crank chamber 3 and adjusting the inclination angle of the swash plate 2.
Are installed in the rear housing 20r. The control valve Cv adjusts the pressure in the crank chamber 3 in accordance with the suction pressure of the returning refrigerant to change the angle of the swash plate 2 to adjust the amount of refrigerant discharged from the compressor. It is controlled to be constant.

That is, since the swash plate 2 is provided with a plurality of pistons 6 at equal angular intervals, a reaction force accompanying the compression of the refrigerant is applied to the swash plate 2 from the pistons 6 in the compression stroke. , A moment M1 acts around the hinge mechanism K. This moment M1 is
Since the moment by the piston 6 located farther from the pin 30 of the swash plate 2 is larger, it acts clockwise in FIG.

The moment M2 acts counterclockwise due to the resilience of the spring B1. Further, there is a moment M3 caused by the pressure difference between the crank chamber 3 and the suction chamber 40, but this moment M3 can be ignored since the pressure in the suction chamber 40 and the pressure in the crank chamber 3 are almost equal.

Here, the resilience of the spring B1 is M1> M2.
Therefore, the inclination angle of the swash plate 2 is increased by a moment acting clockwise about the hinge mechanism K. The swash plate 2 is inclined until the pin 30 of the hinge mechanism K is located at the upper end of the elongated hole 26b.

As a result, the stroke of the piston 6 increases, the amount of refrigerant discharged increases, the flow rate of the refrigerant circulating in the cooling cycle increases, and a proper flow rate of the refrigerant in accordance with the heat load is discharged. Gradually descends, and finally is maintained at a constant suction pressure.

In the present embodiment, as shown in FIGS. 2A and 2B, the piston 6 rotates around its axis outwardly of the neck 6b of the piston 6 facing the front housing 20f. In this case, a detent part 82 is provided which comes into contact with a concave part 83 to be described later and restricts its rotation within a predetermined angle range, and this detent part 82 has an arc-shaped convex surface 82a as a contact surface.

On the other hand, as shown in FIG. 3, a concave portion 83 having an arcuate concave surface 83a as an abutted surface is formed on the inner peripheral surface of the front housing 20f facing the detent portion 82 of the piston 6. , The detent portion 82 on the piston 6 side
And the arcuate concave surface 83a on the front housing 20f side,
Both ends of the rotation preventing portion 82 in the circumferential direction, that is, a circumferential end portion 82c
At a predetermined distance L1.

Therefore, when the piston 6 is reciprocated by rotating the inclined swash plate 2, the swash plate 2
The flat surface of the outer rim slides between the two shoes 4 and 5,
Even if a force for rotating the piston 6 in the direction D shown in FIG. 3, for example, acts via these two shoes 4 and 5, the arc-shaped convex surface 82a of the detent portion 82 becomes the arc-shaped concave surface 8 of the concave portion 83.
The rotation of the piston 6 can be regulated by abutting on 3a.

In this embodiment, in particular, the arcuate convex surface 82
The line of intersection of a with the plane containing the axis of the piston 6 includes two outwardly convex axially convex curves formed at both axial ends of the arc-shaped convex surface 82a and having a predetermined radius of curvature r1. It is configured as follows. That is, at both ends in the axial direction of the rotation preventing portion 82, shaft ends 82b having roundness as shown in FIG. 2A are formed. Thereby, the detent part 82
Even if the piston 6 reciprocates in a state in which the arc convex surface 82a of the above is in contact with the arc concave surface 83a of the concave portion 83, the piston 6 smoothly slides on the rounded shaft end portion 82b and rubs against the edge as in the conventional case. No wear occurs.

The intersection line between the arc-shaped convex surface 82a and the plane perpendicular to the axis of the piston 6 is a circumferential central convex curve having a curvature radius R1 larger than the head radius Rp, and a circumferential central convex curve. Are formed at both ends, respectively, and have a circumferential end convex curve having a radius of curvature r2 smaller than the circumferential central convex curve. That is, at both ends in the circumferential direction of the detent portion 82, rounded end portions 82c as shown in FIG. 3 are formed. Thereby, the detent part 8
The second arcuate convex surface 82a smoothly contacts the arcuate concave surface 83a of the concave portion 83 with a curved surface to restrict the rotation of the piston 23. In addition, since the inner peripheral surface of the front housing does not come into contact with the edge, lubricating oil flows and an oil film is easily formed.

Here, as shown in FIG.
The distance L2 between the two contact portions 82c of the detent portion 82 is
It is set to 0.9 times or more of the diameter of the head. That is, when the piston 6 is rotated left and right, the detent portion 82
Are in contact with the arcuate concave surface 83a of the concave portion 83 of the front housing 20f, so that the distance L2 between the right and left contact points is at least 0.9 times the diameter Dp of the head 6a. It is preferable to set. In this way, within the range in which all lubrication states in the practical range are assumed, even if the friction coefficient is considered to the maximum,
The detent portion 82 of the piston 6 is
It is possible to reliably avoid a situation in which the concave portion 83 is formed on the inner peripheral surface of the f.

The radius of curvature r1 of the shaft end 82b and the radius of curvature r2 of the peripheral end 82c are not so-called yarn chamfering but positive so that abnormal noise and abrasion can be reduced to an acceptable range in quality. Round (for example, a radius of curvature of 1 m)
m or more is preferable), but the front housing 2 may not necessarily have an arc shape.
It suffices that a predetermined radius of curvature is provided at a contact portion with the concave portion 83 formed on the inner peripheral surface of 0f.

The axial dimension of the piston 6 is controlled in order to secure a space for the reciprocation of the piston 6 without waste. As shown in FIG. 4, a broken line in the figure at the end face 6c of the neck 6b is used. Is machined, but the rounded portion having the radius of curvature r1 of the shaft end portion 82b of the detent portion 82 is not removed.

Further, in this embodiment, as shown in FIG. 3, the circular concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the front housing 20f is perpendicular to the circular concave surface 83a and the axis of the piston 6. The intersection line with the plane to be formed is formed so as to include a concave curve having an inner radius of curvature R2 larger than the head radius Rp and smaller than the radius of curvature R1 of the circumferential central convex curve. Here, the arc convex surface 82a
It is also possible to increase the radius of curvature R1 of the central convex curve in the circumferential direction to infinity, that is, to form the circular convex surface 82a as a plane.

In this manner, an oil lubricating space 85 can be formed in a portion between the circular convex surface 82a of the piston 6 and the circular concave surface 83a of the front housing 20f. Then, the splash of the lubricating oil in the crank chamber blown off by the centrifugal force due to the rotation of the swash plate is, as described above, from between the peripheral end portion 82c of the detent portion 82 of the piston 6 and the circular concave surface 83a of the front housing 20f. In addition to flowing in the circumferential direction, it also flows in the axial direction, and the oil lubrication space 85 can function as an oil reservoir for the lubricating oil that has flowed in. Thereby, lubrication of the sliding portion can be sufficiently performed.

The axial length of the concave portion 83 formed on the inner peripheral surface of the front housing 20f is determined by at least the rotation preventing portion 8
The length is set to a length that does not interfere with the movement of 2.
In addition, the aforementioned (curvature) radii R1, R2, Rp and the distance L
1 and L2 are appropriately adjusted based on the design specifications.

Next, the operation of the present embodiment will be described. When an electromagnetic clutch (not shown) is turned on and the shaft 1 is rotated by an engine (neither is shown) via a belt and a pulley, the rotating arm 26 is rotated accordingly, and the swash plate is rotated via the hinge mechanism K. 2 also rotates. If the swash plate 2 is inclined with respect to the shaft 1, the swash plate 2 pivots in a shaking motion, and the piston 6 reciprocates accordingly, and is sucked from the suction port 35 into the cylinder chamber 7. Refrigerant is
It is compressed and discharged from the discharge port 36 to the discharge chamber 41. Note that the shoes 4 and 5 maintain the swash plate 2 even when the swash plate 2 rotates.
Only slides on the flat portion 2a of the
Is not transmitted, and the rotational force of the swash plate 2 is converted into the reciprocating motion of the piston 6.

Here, the heat load in the cooling cycle is
If the temperature is higher than a predetermined set temperature, the suction pressure of the refrigerant increases. In this case, a relatively high suction pressure is introduced into the crank chamber 3 by the action of the control valve Cv, so that the internal pressure becomes substantially equal to the suction pressure. For this reason, even in the piston 6 in the suction process, there is almost no pressure difference between the front and the rear, and the piston 6 can smoothly retreat in the cylinder chamber 7, and a compression reaction force is applied to the piston 6 in the compression process. By taking into account the moment due to the spring force of the spring applied to the swash plate 2 due to the moment about the pin 30, FIG.
Is dominant, the inclination angle of the swash plate 2 increases, and the stroke of the piston 6 increases. When compression is performed in this state, the amount of discharged refrigerant increases, the amount of refrigerant circulating in the cooling cycle increases, an appropriate amount of refrigerant is discharged again according to the heat load, and the suction pressure of the compressor gradually decreases. Finally, a constant suction pressure is maintained.

On the other hand, if the heat load in the cooling cycle becomes small or the refrigerant becomes excessive due to the high speed rotation of the compressor, the pressure of the returned refrigerant does not provide a sufficient amount of superheat and returns at a low pressure. Pressure becomes lower. In this case, the high-pressure refrigerant compressed by the piston 6 and guided to the discharge port 36 is introduced into the crank chamber 3 by the action of the control valve Cv,
The internal pressure of the crank chamber 3 is increased. As a result, a difference occurs in the moment of the force applied to each of the plurality of pistons 6 centering on the pin 30. At some point, the above-mentioned moment becomes M1 <M2 + M3, and the swash plate 2 operates the hinge mechanism K. The moment acting in the counterclockwise direction as the center reduces the tilt angle. Therefore, the stroke of the piston 6 is reduced, and the amount of the discharged refrigerant is reduced.

As described above, the suction, compression, and discharge of the refrigerant are performed by the swash plate 2 inclined with respect to the shaft 1,
This is achieved by bringing the piston 6 whose sliding direction is regulated by the cylinder chamber 7 into sliding contact via the shoes 4 and 5, and converting the swash plate 2 slewing rotational movement into reciprocating movement of the piston 6. However, in this case, the flat surface of the outer edge of the swash plate 2 slides between the shoes 4 and 5 at high speed in the circumferential direction, and the piston 6 is moved through the shoes 4 and 5 by the piston. The force to rotate around the axis works. Such a rotational force is caused by a difference in a local sliding state when the swash plate 2 slides while pressing the flat surfaces 4a and 5a of the shoe, and a sliding speed based on a difference in a distance from the rotation center. It is thought to be caused by differences.

For example, when the piston 6 is rotated in the direction D shown in FIG. 3, the detent portion 82 provided outside the neck 6b of the piston 6 is rotated about the piston axis, and the detent portion 82 is rotated. The arc-shaped convex surface 82a of 82 has a concave portion 83
The rotation of the piston 6 is restricted because of contact with the circular concave surface 83a.

According to this embodiment, the axial end portion 82b having a roundness with a radius of curvature r1 at both axial ends of the rotation preventing portion 82.
Is formed, so that the circular convex surface 82 of the rotation preventing portion 82 is formed.
Even if the piston 6 reciprocates in a state in which a is in contact with the arcuate concave surface 83a of the concave portion 83 as described above, it is possible to slide smoothly on the shaft end 82b.

Accordingly, the edge of the axial end of the rotation preventing portion and the inner surface of the casing are rubbed as in the prior art, causing abrasion, and the piston is provided with a coating layer for improving slidability. In such a case, it is possible to avoid the possibility that the coating layer is peeled off by the rubbing and the same material comes in contact with each other to increase the sliding resistance and adversely affect the reciprocating operation of the piston.

Further, at both ends in the circumferential direction of the detent portion 82,
Since the peripheral end portion 82c having a rounded radius of curvature r2 is formed, when the piston 6 tries to rotate around the piston axis, the peripheral end portion 82c of the rotation preventing portion 82 becomes a concave portion 8c.
The third circular-arc concave surface 83a abuts so as to make smooth surface contact with the curved surface, so that the rotation of the piston 6 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 hit the edge of the inner peripheral surface of the front housing 20f with the detent portion 82. The oil film is likely to flow in the circumferential direction from a portion where the oil film is formed. Further, the lubricating oil also flows in from the axial direction, and the circular convex surface 82 of the piston 6
Since the oil lubricating space 85 can be formed in a portion surrounded by a and the arcuate concave surface 83a of the front housing 20f, the oil lubricating space 85 can function as an oil reservoir for the lubricating oil that has flowed in. Thereby, lubrication of the sliding portion can be sufficiently performed.

Therefore, the occurrence of abnormal noise and abrasion can be prevented by the detent of the piston and the sufficient lubrication of the sliding portion due to such smooth curved surface contact.

Further, the detent portion 82 slightly protrudes from the outside of the neck 23b of the piston 6 and can sufficiently fulfill the function of preventing the detent of the piston 6. The lubrication space 85 formed in a portion surrounded by the convex surface 82a and the arc-shaped concave surface 83a of the front housing 20f is consequently reduced compared to the conventional piston neck (see FIG. 6). Thus, the weight of the piston can be reduced. Therefore, the burden on the high-speed reciprocating motion of the piston can be reduced.

FIG. 5 is a side view showing a neck portion of a piston according to another embodiment. In this embodiment, as shown in the figure, a circular convex surface 92 as a contact surface is
a is formed.

The line of intersection between the arc-shaped convex surface 92a and the plane including the axis of the piston 6 extends substantially over the entire length of the arc-shaped convex surface 92a in the axial direction and has an outwardly convex shape having a predetermined radius of curvature R3. It consists of two axially central convex curves. Except for this point, it is the same as the above embodiment. According to this embodiment, the curved surface of the arc-shaped convex surface 92a can be brought into contact with the inner peripheral surface of the front housing 20f, and in this state, the piston 6 can reciprocate while sliding smoothly. . Therefore, effects similar to those of the above embodiment can be obtained. In this case, it is not always necessary to form the rounded shaft end portions 82b at both ends in the axial direction of the rotation preventing portion 82 as in the above embodiment.

The embodiments described above are described to facilitate understanding of the present invention, but not to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above embodiment, the center of the inner radius of curvature R2 of the arcuate concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the front housing 20f is not on the central axis of the shaft 1, Are set at a predetermined distance from each other in the direction of each piston axis. That is,
Opposite to each detent portion 82 of each piston 6, a respective arcuate concave surface 83a centered on a different central axis is formed. However, the present invention is not limited to such a configuration, and the circular concave surface 8 of the concave portion 83 formed to face the detent portion 82 of each piston 6.
It is also possible that 3a constitutes all or a part of a cylindrical inner surface formed along the entire inner peripheral surface of the front housing 20f. In this case, the central axis of the arcuate concave surface 83a coincides with the central axis of the shaft 1. That is, the arcuate concave surface 83a may be formed by cutting the entire circumference along the inner peripheral surface of the front housing 20f, or may be necessary to prevent the rotation of the piston between the pistons when the front housing 20f is formed. It is also possible to form the part that does not exist by leaving it, leaving the cast surface, and shaving only the part of each piston that faces the detent part 82. With such an arcuate concave surface 83a of the concave portion 83, the arcuate concave surface 83a can be machined for all pistons (for example, five pistons arranged evenly in the circumferential direction) at one time,
The number of processing steps can be reduced.

Although the description has been given by taking the variable capacity swash plate type compressor as an example, the present invention can be applied not only to the variable capacity type compressor but also to the fixed capacity swash plate type compressor. Although the piston used in the above-described embodiment is of a single-head type, the piston may be of a so-called double-head type having heads on both sides in the axial direction of a connecting portion with the swash plate.

It should be noted that various types of control valves of the present invention can be used. For example, as a control means for adjusting the pressure in the crank chamber 3, a control valve having a structure in which a gas of a predetermined pressure is sealed in a bellows, or a control valve may be used. The bellows expands and contracts in accordance with the suction pressure, opening and closing the valve by this operation, and introducing a high discharge pressure into the crank chamber 3 and at the same time
Electronic control according to the heat load of the refrigeration cycle, such as a method of cutting off the communication to the suction chamber 40 or a method of reducing the pressure of the crank chamber 3 by connecting the crank chamber 3 to the suction chamber 40 by cutting off the high discharge pressure. A system in which the pressure introduced into the crank chamber 3 is controlled in a system may be used. The suction chamber 40 and the crank chamber 3 are always in communication with each other through an orifice, and a method of controlling the amount of high-pressure discharge pressure introduced into the crank chamber 3 can be used.

[0069]

As described above, according to the present invention, the following effects can be obtained for each claim. According to the first to third aspects of the present invention, since the axial ends having a predetermined radius of curvature are formed at both ends in the axial direction of the detent portion, the contact surface of the detent portion contacts the inner surface of the casing. Even if the piston reciprocates in this state, it can be slid smoothly at the shaft end.

Therefore, the edge of the axial end of the rotation preventing portion and the inner periphery of the casing rub against each other, causing abrasion, and a coating layer for improving the slidability is formed on the piston. In such a case, it is possible to avoid the possibility that the coating layer is peeled off by the rubbing and the same material comes into contact with each other, the sliding resistance is increased, and the reciprocating operation of the piston is adversely affected.

According to the fourth aspect of the present invention, when the swash plate slides between the two shoes at a high speed in the circumferential direction and the piston is rotated through the two shoes,
The detent portion formed on the piston is rotated about the piston axis, and the contact portion of the detent portion is brought into contact with the concave contact surface so as to make smooth surface contact with the curved surface. Therefore, the rotation of the piston can be reliably and smoothly regulated.

Further, since the lubricating oil blown off by the centrifugal force due to the rotation of the swash plate does not hit the edge of the inner peripheral surface of the casing against the detent, the lubricating oil flows in a circumferential direction from a portion which comes into surface contact with the curved surface. As a result, an oil film is easily formed.
Further, lubricating oil flows in from the axial direction, and an oil lubricating space can be formed in a portion between the contact surface of the detent portion of the piston and the contact surface of the concave portion of the casing. Therefore, the oil lubrication space can function as an oil reservoir for the lubricating oil that has flowed in. Thereby, lubrication of the sliding portion can be sufficiently performed.

Therefore, the occurrence of abnormal noise and abrasion can be prevented by the detent of the piston and the sufficient lubrication of the sliding portion due to such smooth curved surface contact.

According to the fifth aspect of the present invention, the contact surface of the casing is constituted so as to form all or a part of a cylindrical surface formed over the entire circumference along the inner peripheral surface of the casing. It is also possible to process the concave curved surface for all the pistons at a time, and it is possible to reduce the number of processing steps.

According to the sixth aspect of the present invention, the distance between the circumferential ends of the contact surface of the detent portion of the piston is set to 0.9 times or more of the diameter of the head, so that any lubrication in a practical range is possible. It is possible to reliably avoid the situation where the detent part of the piston bites into the concave part formed on the inner peripheral surface of the casing, even if the friction coefficient is considered to the maximum within the range assumed for the state. It is.

[Brief description of the drawings]

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

2 (A) is a side view of the piston shown in FIG. 1, and FIG. 2 (B) is a view of the piston as seen from the crank chamber side in the axial direction.

FIG. 3 is a diagram illustrating a structure for preventing rotation of a piston.

FIG. 4 is an enlarged view of a portion indicated by E in FIG.

FIG. 5 is a side view showing a neck portion of a piston according to another embodiment.

FIG. 6 is a view of a piston of a conventional swash plate type compressor as viewed from its crank chamber side in the axial direction.

FIGS. 7A to 7C are schematic cross-sectional views around a piston of a conventional swash plate compressor.

[Explanation of symbols]

1 ... shaft, 2 ... swash plate, 3 ... crankcase, 4, 5 ... shoe, 6 ... piston,
6a ... head, 6b ... neck,
7 ... Cylinder chamber, 20f ... Front housing (casing), 20r ... Rear housing (casing), 21 ... Cylinder block (casing), 82 ...
Detent part, 82a ... arc convex surface (contact surface), 82b ...
Shaft end, 82c: peripheral end, 83: concave portion, 83a: arc concave surface (contact surface), 85: oil lubricating space, L1, L2: distance, R1, R2, R3, r1, r2
... radius of curvature, Rp ... piston radius.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-346844 (JP, A) JP-A-7-189900 (JP, A) JP-A-6-66253 (JP, A) JP-A-6-66253 JP-A-3-88975 (JP, A) JP-A-63-93480 (JP, U) JP-A-6-25573 (JP, U) JP-A-5-12673 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B60H 1/32 F25B 31/00 F04B 27/08 F04B 39/00

Claims (6)

(57) [Claims] 1. A shaft (1) rotatably mounted on a casing, a swash plate (2) provided in a crank chamber (3) in the casing and connected to the shaft (1), and a swash plate (2) provided in the casing. The cylinder chamber (7) is formed via a plurality of cylinder chambers (7) formed and shoes (4, 5) arranged in contact with the front and back surfaces of the swash plate (2) by rotation of the swash plate (2). A swash plate compressor having a plurality of pistons (6) reciprocated in the axial direction inside the swash plate, wherein the piston (6) includes a head (6a) reciprocating in a cylinder chamber (7), and a shoe ( A neck (6b) connected to the swash plate (2) via the swash plate (2, 4), and the piston (6) has a piston (6f) outwardly facing the inner surface of the casing (20f). (6) A non-rotating stop formed with a contact surface (82a, 92a) that contacts the inner surface of the casing (20f) and restricts the rotation within a predetermined angle range when rotated around its axis. A portion (82) is provided, and an intersection line between the contact surface (82a, 92a) and a plane including the axis of the piston (6) has an outwardly convex shape having a predetermined radius of curvature (r1, R3). A swash plate compressor including a curve. 2. The swash plate compressor according to claim 1, wherein the curve has two axial end convex curves formed at both axial ends of the contact surface (82a). 3. The swash plate type as claimed in claim 1, wherein the curve has one axial central convex curve formed over substantially the entire axial length of the contact surface (92a). compressor. 4. An intersection line between the contact surface (82a, 92a) and a plane perpendicular to the axis of the piston (6) is a circumferential direction having a radius of curvature (R1) larger than the radius of the head (Rp). A central convex curve, and a peripheral end convex curve formed at both ends of the circumferential central convex curve and having a radius of curvature (r2) smaller than the circumferential central convex curve, and a detent portion of the piston (6) ( 82) (2)
0f), a concave surface (83a) formed with a contact surface (83a) in which the rotation of the piston (6) is restricted by the contact surface (82a) of the rotation preventing portion (82) abutting against the inner peripheral surface. 83) is provided, and the line of intersection of the contact surface (83a) and a plane perpendicular to the axis of the piston (6) is larger than the head radius (Rp) and the curvature of the circumferential central convex curve. Inner radius of curvature smaller than radius (R1)
The swash plate type compressor according to claim 1, comprising a concave curve having (R2). 5. The casing (20) is provided with a contact surface (83a).
5. The swash plate type compressor according to claim 4, wherein the swash plate compressor forms all or a part of a cylindrical inner surface formed over the entire circumference along the inner peripheral surface of f). 6. The distance (L2) between circumferential ends of the contact surface (82a) is at least 0.9 times the diameter (Dp) of the head (6a). Swash plate compressor.