JPH08109874A - Swash plate compressor - Google Patents

Abstract

PURPOSE: To provide a swash plate type compressor which is reliably and smoothly prevented from rotation of a piston through simple structure. CONSTITUTION: A protrusion part 82 having an arcuate protrusion surface 82a having a radius R2 larger than the radius R1 of a piston is formed on the outer surface of the fit-in part 23b on the rear end side of a piston 23 in such a state that the central axis of the arcuate protrusion surface 82a is positioned eccentrically from a piston axis by a given distance on the opposite side to the protrusion part 82. A recessed part 83 having an arcuate recessed surface 83a having an inner radius R3 exceeding the radius R2 of the arcuate protrusion surface 82a is formed on the inner peripheral surface of a casing positioned facing the protrusion part 82 in such a state that the recessed part is separated away from the protrusion part 82 of the piston 23 by a given distance L1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in swash plate compressors.

[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.

This variable displacement swash plate compressor includes a drive shaft that is rotationally driven by an engine that is transmitted via a belt, a pulley, and the like, and a disc-shaped swash plate that is mounted on the drive shaft in a variable tilt angle. When the drive shaft is rotated, the swash plate in the inclined 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, the cross section of the piston is approximately U at the rear end side.
A V-shaped fitting portion is formed, and a substantially hemispherical shoe is fitted into two spherical concave portions formed at opposing positions on both inner surfaces of the fitting portion, and these both shoes are used to attach the front and back surfaces of the swash plate. Both flat surfaces are clamped. 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 portions of the shoe, and the piston has a spherical concave portion formed at its rear end. Sliding contact with the spherical surface of the corresponding shoe. In this way, the piston
The rear end is slidably connected to the swash plate.

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.

[0007]

By the way, in the case of reciprocating the piston by rotating the inclined swash plate, as shown in FIG.
An axial force acts on 23 through both shoes 71, 72, and the piston 123 slides along the cylinder chamber toward the top dead center or the bottom dead center in the direction perpendicular to the plane of FIG. . Note that FIG. 4 is a diagram of the piston 123 viewed from the axial rear side. 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 123 is inserted through the shoes 71 and 72. There was a problem that the force to rotate B in the B direction worked.

On the other hand, as shown in FIG. 4, a convex portion 124 having a rectangular parallelepiped shape is provided on the outer peripheral surface of the piston 123, and the inner peripheral surface of the casing 112 is movable in the axial direction with the convex portion 124. The piston 123 is prevented from rotating by forming the sliding groove 127 that engages as described above. 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. .

However, such a conventional piston rotation preventing mechanism has the following drawbacks. That is, first, the processing of the rectangular parallelepiped convex portion 124 and the sliding groove 127 is performed by processing both end faces 1 in the circumferential direction.
In addition to 24a, 124b, 127a, 127b, there is machining of the top portion 124c and the bottom portion 127c, both of which are plane machining, and therefore a lot of tools are fed, and the same machining is required for the number of pistons arranged, for example, 5 places. For,
This has led to an increase in man-hours.

Further, since the detent has a structure in which it is supported by the end face in the circumferential direction, it is necessary to secure a predetermined contact area, and the convex portion 124 tends to become large, which increases the weight of the piston and causes high-speed reciprocating motion. The burden on

Further, a certain clearance is required between the convex portion 124 and the sliding groove 127 in order to prevent excessive resistance to the reciprocating motion of the piston. However, there is also a problem that the end faces of the convex portion 124 and the sliding groove 127 are impacted with each other, resulting in abnormal noise.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is a variable capacity swash plate type which can reliably and smoothly prevent rotation of a piston with a simple structure. To provide a compressor.

[0013]

SUMMARY OF THE INVENTION A variable capacity swash plate type compressor according to the present invention for achieving the above object comprises a casing for rotatably supporting a drive shaft and a tilt angle variable with respect to the drive shaft. Attached swash plate, multiple cylinder chambers formed in the casing, multiple pistons that reciprocate in the axial direction inside the cylinder chambers, and inner surfaces on both sides of the fitting portion on the rear end side of each piston. In a variable capacity swash plate type compressor having two spherical concave portions formed to face each other, sandwiching both front and back surfaces of the swash plate, and having shoes in sliding contact with these, facing the casing behind the piston. On the outer surface, a convex portion having a circular arc convex surface with a radius larger than the piston radius is arranged so that the center axis of the circular arc convex surface is eccentric to the piston shaft on the side opposite to the convex portion by a predetermined distance. A concave portion having an arc concave surface with an inner radius of at least the radius of the circular arc convex surface is formed on the inner peripheral surface of the casing facing the convex portion at a predetermined distance from the convex portion of the piston. Characterize.

Further, the arcuate concave surface of the concave portion formed facing the convex portion of each piston constitutes all or part of the cylindrical surface formed over the entire circumference in the vicinity of the inner peripheral surface of the casing. You may

[0015]

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 at a high speed in the circumferential direction, a force for rotating the piston around the piston shaft is exerted via these shoes.
When the piston is rotated, the convex portion formed on the outer peripheral surface of the fitting portion on the rear end side of the piston is rotated around the piston shaft. Here, the circular arc convex surface of the convex portion is formed so that its central axis is eccentric to the piston shaft on the side opposite to the convex portion by a predetermined distance, and therefore the circular arc convex surface is defined as a part of the circumference. The circle is rotated around the piston axis as if it were revolving.

As a result, the arcuate convex surface of the convex portion approaches the arcuate concave surface of the concave portion formed on the inner peripheral surface of the casing, and is abutted so as to make substantially surface contact. Therefore, the rotation of the piston is prevented reliably and smoothly. Moreover, since the rotation does not stop due to a shocking collision, the generation of abnormal noise is prevented.

[0018]

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 rotation stopping mechanism of the piston.

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 provided at the left end of the front head 1.
1 and three are integrally connected 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.

A front head side of a drive shaft 19 which is inserted through the casing 12 is projected through the front head 11, and a pulley 20 is connected to an end of the drive shaft 19. The electromagnetic clutch 2 is provided between the drive shaft 19 and the pulley 20.
7 is provided, the electromagnetic clutch is turned on when cooling is required,
The rotation of the engine is transmitted via the belt. If the electromagnetic clutch is turned off when cooling is not required, the connection between the engine and the compressor is cut off, and the drive shaft 19
Does not rotate, only the pulley spins.

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 23 on its front end side.
a, a fitting portion 23b having a substantially U-shaped cross section is formed on the rear end side. The spherical surface portions of the shoes 71, 72 are fitted into the spherical concave portions 23c, 23d formed so as to face the inner surfaces of both sides of the fitting portion 23b. It is sandwiched and comes into slidable contact.

In this embodiment, in particular, as shown in FIGS. 2A and 2B, a convex portion 82 is formed on the outer surface of the fitting portion 23b on the rear end side of the piston 23, and the convex portion 82 is formed. Reference numeral 82 has an arcuate convex surface 82a. On the other hand, as shown in FIG. 2B, the inner peripheral surface of the casing 12 facing the convex portion 82 of the piston 23 has an arcuate concave surface 83a spaced from the convex portion 82 by a predetermined distance L1. The concave portion 83 is formed.

Further, as shown in FIG. 3, the radius R2 of the circular arc convex surface 82a of the convex portion 82 is equal to the radius R1 of the piston 23.
The convex portion 82 is formed such that the central axis O2 of the arcuate convex surface 82a is eccentric to the piston axis O1 on the side opposite to the convex portion 82 by a predetermined distance L2. On the other hand, the arcuate concave surface 83a of the concave portion 83
Is at least the radius R2 of the arcuate convex surface 82a of the convex portion 82.
The above inner radius R3 is set.

With this setting, the inclined swash plate 25
When the piston 23 is reciprocated by rotating, the flat surface of the outer edge portion of the swash plate 25 causes the shoes 71, 7 to move.
Even if a force that slidably moves between the two and the piston 23 is rotated in the C direction shown in FIG. 3 via these shoes 71 and 72, the arcuate convex surface 82a of the convex portion 82 is concave. The circular arc concave surface 83a of 83 abuts on the surface of the piston 2
The rotation of 3 can be prevented.

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 length is set to be equal to or longer than the length that does not interfere with the movement of the convex portion 82 of the piston 23 due to the reciprocating movement of. Further, the above-mentioned radii R1 to R3 and the distances L1 and L2 can be appropriately set based on the design standard, but the distance L1 does not interfere with the reciprocating motion of the piston, and in addition, the distance L1 is ensured. Is preferably set to 0.5 mm or less.

A left side portion of the drive shaft 19 in the drawing is supported by the front head 11 via a bearing 26, and a rotary member 28 rotated by the drive shaft 19 is provided inside the bearing 26. 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. Swash plate 2
5 and the rotating member 28 have links 30b and 30a, respectively.
And the links 30b and 30a are provided with a long hole 3
1 and the pin member 32, and the swash plate 25 is rotated by the rotation of the rotating member 28.

Therefore, this swash plate 25 is
The pin member 32 is tilted as a fulcrum as the shaft 9 moves in the axial direction, and the tilt angle (the tilt angle with respect to the plane orthogonal to the axis of the drive shaft 19) can be mechanically adjusted. The inclination angle of the swash plate 25 is the balancer 2 of the swash plate 25.
The maximum inclination angle is given at the position where 5a comes into contact with 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.

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, in the suction, compression, and discharge of the refrigerant, as described above, the swash plate 25 in the inclined state is reciprocally moved by imparting an axial force to the piston 23 by the slewing rotation. 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 O1 acts via 72.

Such a rotational force is due to a difference in local sliding state 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 C direction shown in FIG. 3, the convex portion 82 formed on the outer surface of the fitting portion 23b on the rear end side of the piston 23 becomes
It is rotated about the piston axis O1. Here, since the arcuate convex surface 82a of the convex portion 82 is formed so that its central axis O2 is eccentric to the piston axis O1 on the side opposite to the convex portion 82 by a predetermined distance L2, the circular arc convex surface 82a is A circle that is part of the circumference (indicated by the chain double-dashed line in Fig. 3)
As if it were revolving around the piston axis O1, it would be rotated in the direction of arrow D.

As a result, the arcuate convex surface 82a of the convex portion 82 approaches the arcuate concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the casing 12 and abuts them so as to come into almost surface contact. Therefore, the rotation of the piston 23 can be reliably and smoothly prevented. Moreover, since the rotation does not stop due to a shocking collision, the generation of abnormal noise can be prevented.

Further, the convex portion 8 formed on the piston 23
2 and the recessed portion 83 formed in the casing 12 are each mainly formed of an arcuate surface, so that they can be easily processed and the number of steps can be reduced, and the product cost can be reduced.

Further, although the convex portion 82 is shown in an exaggerated and large size in FIG. 3, it is sufficient that the convex portion 82 slightly protrudes from the outer surface of the fitting portion 23b on the rear end side of the piston 23. It is possible to fulfill the function of preventing rotation of the piston, and therefore the weight of the piston can be made lighter than before. Therefore, the load on the high-speed reciprocating motion of the piston can be reduced.

Since the convex portion 82 is provided at the rear end portion of the piston 23 as shown in FIG. 2, the rigidity of the corner portion is improved.

It should be noted that the embodiments described above are described 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 embodiment described above, FIG.
As shown in FIG. 3 and FIG. 3, the arcuate concave surface 83a of the concave portion 83 formed on the inner peripheral surface of the casing 12 is formed around each central axis O3 relatively close to each piston axis O1. That is, the arcuate concave surfaces 83a centering on different central axes O3 are formed so as to face the convex portions 82 of each piston 23. However, the present invention is not limited to such a configuration, and the arcuate concave surface 83a of the concave portion 83 formed facing the convex portion 82 of each piston 23 is in the vicinity of the inner peripheral surface of the casing 12. It is also possible to form all or part of the cylindrical surface formed over the entire circumference.
That is, in this case, the central axis O3 of the circular arc concave surface 83a is
Will coincide with the position of the center of symmetry of the plurality of pistons 23 arranged at equal intervals on the circumference. 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. Further, as the simplest configuration, the inner peripheral surface of the casing 12 can be used as it is to form the circular arc concave surface 83a.

Although the variable capacity swash plate compressor has been described above 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.

[0042]

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 convex portion formed on the outer surface facing the casing behind the piston is rotated about the piston axis, and as a result, the arc convex surface of the convex portion is the concave portion formed on the inner peripheral surface of the casing. The rotation of the piston can be surely and smoothly prevented by approaching the concave surface of the circular arc and contacting it so as to make a substantially surface contact. Moreover, since the rotation does not stop due to a shocking collision, the generation of abnormal noise can be prevented.

Further, since the convex portion formed on the piston and the concave portion formed on the casing are both shaped to have an arcuate surface as a main component, they are easily machined and the number of machining steps is reduced, and consequently the product cost is reduced. Can be achieved.

Furthermore, the above-mentioned convex portion can sufficiently fulfill the function of preventing the rotation of the piston by only slightly protruding from the outer peripheral surface of the fitting portion on the rear end side of the piston.
Therefore, the weight of the piston can be made lighter than before. Therefore, the load on the high-speed reciprocating motion of the piston can be reduced.

If the circular arc concave surface constitutes all or part of the cylindrical surface formed over the entire circumference in the vicinity of the inner peripheral surface of the casing, the circular arc concave surface for all pistons can be processed at once. It is also possible to further reduce the processing man-hour.

[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 mechanism of a piston.

FIG. 4 is a view of a piston of a conventional variable displacement 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 ... Fitting part, 2
3c, 23d ... spherical concave portion, 25 ... swash plate,
71, 72 ... shoe, 82 ... convex portion,
82a ... Convex arc surface, 83 ... Concave portion, 83
a ... Arc concave surface, L1, L2 ... Distance, R1 to R
3 ... radius, O1 ... piston axis, O2 ... central axis.

Claims (2)

[Claims] 1. A drive shaft (19) rotatably mounted on a casing (12) and a swash plate connected to the drive shaft (19) provided in a crank chamber (14) of the casing (12). (25), a plurality of cylinder chambers (13) formed in the casing (12), and a plurality of pistons (i.e., reciprocally moved in the axial direction in the cylinder chamber (13) by rotation of the swash plate (25). 23) and two inner surfaces of the fitting portion (23b) on the rear end side of each piston (23) so as to face each other.
In a swash plate type compressor having two spherical recesses (23c, 23d) fitted respectively and sandwiching both front and back surfaces of the swash plate (25) and having shoes (71, 72) in sliding contact with them, the piston (23 ) On the outer surface facing the rear casing (12),
Convex surface (82) with radius (R2) larger than piston radius (R1)
a) with a convex portion (82) having a central axis (O
2) is formed so as to be eccentric by a predetermined distance (L2) on the side opposite to the convex part (82) with respect to the piston shaft (O1), and the inner circumference of the casing (12) facing the convex part (82) A concave portion (83) having an arc concave surface (83a) with an inner radius (R3) greater than or equal to the radius (R2) of the arc convex surface (82a) at a predetermined distance from the convex portion (82) of the piston (23). A swash plate compressor characterized in that it is formed so as to be separated by (L1). 2. The arc concave surface (83a) of the concave portion (83) formed so as to face the convex portion (82) of each piston (23) is a casing.
The swash plate compressor according to claim 1, wherein all or part of a cylindrical surface formed over the entire circumference in the vicinity of the inner peripheral surface of (12).