JPH048875A - Swash plate variable displacement compressor - Google Patents

Abstract

PURPOSE:To simplify the construction of a compressor by supporting the shaft thereof with a plurality of bearings fitted to a housing for preventing shaft dislocation or the like, and inserting the shaft portion of a spool through the cylindrical portion of the shaft for engagement with a slider pin. CONSTITUTION:When a shaft 15 is driven for rotation, a swash plate 28 performs oscillation motion as well as the same rotary motion as the shaft 15. The vector of the oscillation motion causes a piston 9 to generate reciprocating motion in an axial direction, and the first and second operation chambers 12 and 13 perform a compression work for a fluid. On the other hand, when the pressure of a control pressure chamber 43 is changed with a pressure control valve 46 for changing delivery capacity, the shaft portion 39 of a spool 38 axially moves in the cylindrical portion 32 of the shaft 15, thereby allowing the axial shift of a slider pin 31 and the center of a swash plate 28. In this case, the shaft 15 is directly supported in a radial direction with a housing 1 at two positions of a front radial bearing 16 and a rear radial bearing 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a swash plate type variable capacity compressor suitable for use as a refrigerant compressor in, for example, an automobile air conditioner.

[Conventional technology]

The present inventors previously developed a swash plate type variable displacement compressor that can maintain the piston top clearance at a small value by simultaneously moving the rotation center position of the swash plate when changing the inclination angle of the swash plate. did. This compressor uses a double-headed piston, and by keeping the top clearance of one piston head to a small value as described above, a dead volume is created on the other piston head side and no pumping action occurs. It has excellent control performance in that the discharge volume can be changed widely from small volume to large volume by maintaining a small volume pumping action on the one piston head side even when the piston head is in use.

In the previously developed swash plate type variable displacement compressor, a rear radial bearing was installed inside the spool as a control fluid pressure piston, which moved in the axial direction when the control pressure of the pressure control valve was changed. , thereby bearing the rear shaft with the ball joint at the center of the swash plate, and as the spool moves in the axial direction, these radial bearings, the shaft with the ball joint, the swash plate, etc. move in the axial direction. It was configured to do so.

[Problem to be solved by the invention]

Conventional compressors have the above-mentioned configuration, so when the control pressure is changed to control the discharge capacity and the spool is moved in the axial direction, the rear bearing and shaft supported by it are also affected. However, since there is a small clearance between the spool and the surface that guides it in the axial direction to allow sliding, the radial force applied to the rear bearing causes the spool to move. The center axis of the spool may be slightly tilted, resulting in axial misalignment between the front and rear bearings, causing the shaft to whirl around, and the spool to tilt, resulting in smooth axial movement. It has been found that there is a problem in that there is a risk of abnormal wear and seizure due to the failure of the capacitance, which adversely affects capacity controllability and durability.

The present invention solves the above-mentioned problem, and the shaft that drives the compressor is reliably supported by the housing at two points on both sides of the swash plate, so that tilting or misalignment of the axis that causes abnormal wear or seizure does not occur. In addition, it is an object of the invention to provide a swash plate inclination angle adjustment/holding mechanism for capacity control that has a simpler and more robust structure than conventional ones.

[Means to solve the problem]

As a means for solving the above problems, the swash plate type variable displacement compressor of the present invention is provided with a cylinder bore serving as a first working chamber and a cylinder bore serving as a second working chamber facing each other. a housing, a double-headed piston inserted across the opposing pair of cylinder bores, a shaft inserted into the housing and driven by an external power, and a double-headed piston driven by the shaft. a swash plate that engages with the piston to provide reciprocating motion in the axial direction; a slider pin that is inserted into a long hole in the axial direction provided in the shaft and serves as a center of tilting of the swash plate; a cam device for raising the swash plate; a plurality of bearings directly attached to the housing for bearing the shaft at front and rear positions of the swash plate on the shaft; and a shaft inserted into the housing of the shaft. a cylindrical portion formed at an end including a long hole in the axial direction; a shaft portion inserted into the cylindrical portion of the shaft from the shaft end side and engaged with the slider pin; and a control pressure chamber. and a spool having a disk-shaped head that receives control fluid pressure.

[For production]

When the shaft is rotationally driven by external power, the double-headed pistons inserted into the paired cylinder bores are driven by the swash plate and reciprocate in the axial direction, performing compression work within each cylinder bore.

When changing the discharge capacity, the control fluid pressure in the control pressure chamber is changed by a pressure control valve, and the spool having a disc-shaped head that receives the control fluid pressure is moved in the axial direction. The spool is equipped with a shaft part that is inserted into a cylindrical part provided at the end of the shaft, and the tip of the shaft part is inserted into a long hole in the axial direction provided in the shaft part of the slider. Since it engages the pin and is the central axis of tilting of the swashplate, an axial movement equal to the axial movement of the spool is imparted to the swashplate. This axial movement prevents the top clearance on one side of the double-headed piston from increasing and ensures operation of the compressor at small displacements.

According to the axial movement of the swash plate, a predetermined inclination angle is given to the swash plate by the cam device, and the stroke of the double-headed piston reciprocated by the swash plate changes. This results in a change in the discharge capacity of the compressor.

As described above, the control force transmission mechanism for changing the axial position of the swash plate and changing the inclination angle to change the discharge capacity is a mechanism that connects the shaft of the spool inserted into the cylindrical part of the shaft and the swash plate. Since it consists of a slider pin, the mechanism is not exposed to the outside of the shaft. Therefore, the shaft can have a structure in which the bearing provided at the end of the shaft is directly supported by the housing, and similarly
Together with other bearings that are directly supported by the housing, it is possible to firmly and reliably support the shaft to prevent it from wobbling.

〔Example〕

In FIG. 1 showing the overall structure of an embodiment of the compressor of the present invention, 1 is a housing made of light alloy, a front cylinder 2,
It is composed of a rear cylinder 3, a front nose housing 4, and a rear nose housing 5, and these parts are integrally connected by several through bolts 6. 7 is a cylinder bore on the front side that opens into the front cylinder 2, and 8 is a cylinder bore on the rear side that opens into the front cylinder 2.
Although only one pair is shown in the figure, such paired cylinder bores 7.8 are evenly distributed within the nozzle housing 1 in this example. Five sets are arranged parallel to each other. A double-headed piston 9 is inserted into each pair of cylinder bores 7.8, and a first working chamber 12 on the front side is pumped by the piston head 10 on the front side and the cylinder bore 7, and a first working chamber 12 on the front side is pumped by the piston head 10 on the front side and the cylinder bore 7. The side piston rod 11 and the cylinder bore 8 form a second working chamber 13 on the rear side which also performs a pumping action. In the figure, reference numeral 14 indicates a near guide that prevents the rotation of the piston 9 and guides it in the axial direction.

Reference numeral 15 denotes a shaft for driving the compressor, which extends into the housing 1 through approximately the center of the front housing 4, front cylinder 2, and rear cylinder 3, and is connected to a front radial bearing 16 provided in a through hole of the front cylinder 2. , and a rear radial bearing 17 provided in a through hole of the rear cylinder 3. The shaft 15 is also axially supported by a front thrust bearing 18 and a rear thrust bearing 19, which are provided in the front and rear cylinders 2.3, respectively, so as to engage in their steps. 2
0 indicates a shaft seal provided in the through hole of the shaft 15 of the front housing 4, 21 is a front bushing, and 22 is a rear bushing, which hold thrust bearings 18 and 19, respectively.

Reference numeral 23 denotes a large portion formed in a part of the shaft 15, which is cut so as to form two surfaces parallel to each other in the axial direction, and only one surface 24 is shown in FIG. . A cam groove 25 opens diagonally across the axis in the enlarged portion 23.

In order to reciprocate all the pistons 9 in the axial direction,
An annular disk-shaped swash plate 28 that engages with the center portion of each piston 9 through shoes 26 and 27 that form part of a ball is supported by the shaft 15 within a swash plate chamber 29 that is the inner cavity of the rear cylinder 3. It will be established.

That is, a slider pin 31 is inserted in the diametrical direction of the swash plate 28 into a generally cylindrical swash plate guide 30 that is press-fitted and integrated into the swash plate 28 . It engages with a long hole 33 provided in the axial direction across a part of it. In this way, the swash plate 28 can be tilted with respect to the shaft 15 by the slider pin 31 and the elongated hole 33, and at the same time can also move in the axial direction on the shaft 15 within the range of the elongated hole 33. .

Note that the slider pin 31 is prevented from being removed by press-fitting the swash plate guide 30 into the opening of the swash plate 28. Swash plate 2
8, the swash plate guide 30 is provided with two plate-like arms parallel to each other in the axial direction (only a part of the arm 34 on one side is shown in FIG. 1). ), an arm pin 35 inserted between these arms and prevented from being removed is provided on the enlarged portion 23 of the shaft 15 via an arm roller 36 fitted therein. It engages with the aforementioned cam groove 25.

In order to change the inclination angle of the swash plate 28 with respect to the shaft 15 and simultaneously move the center of the swash plate 28, that is, the slider pin 31 in the axial direction, a cylindrical inner surface 37 of a cylindrical portion 32 formed at the right end of the shaft 15 is provided with a cylindrical inner surface 37. , spool 38
An integral shaft portion 39 extending from the center of the spool 38 is loosely fitted to the shaft 15 so as to be slidable in the axial and rotational directions, and a disc-shaped head 40 serving as a control piston of the spool 38 is attached to the rear It is slidably fitted into a control cylinder 41 provided as a cylindrical inner cavity in the housing 5 in a fluid-sealed manner by a ring 42 . The spool 38 forms a control pressure chamber 43 between it and the control cylinder 41 on the rear side of the disk-shaped head 40, and is biased to the left in the axial direction in the figure by a compression spring 44 provided therein. , the tip of the shaft portion 39 is always in contact and engagement with the slider pin 31.

The suction pressure (low pressure) and discharge pressure (high pressure) of the compressor can be selectively communicated to the control pressure chamber 43 by a pressure control valve 46, thereby changing the pressure of the control pressure chamber 43 and controlling the spool. The spool 38 is moved to a position where it balances the suction pressure acting on the left side of the disk-shaped head 40 of the spool 38. This movement moves from the shaft portion 39 of the spool to the slider pin 31.
, the swash plate 28 moves in the axial direction against the axial force (acting to the right in the figure) due to the reaction force of the compression action that the swash plate 28 receives from the piston 9 (the slider pin 31 moves into the elongated hole 3
3), and accordingly, the swash plate 28 is tilted by the action of the cam groove 25 and the arm pin 35.

FIG. 1 shows a state in which the center of the swash plate 28 (slider pin 31) has been moved to the far left in this way, and the swash plate 28 has taken the maximum angle of inclination (with respect to the plane perpendicular to the shaft 15). In this state, the reciprocating stroke of the piston 9 is at its maximum, and accordingly, the discharge capacity of the compressor is at its maximum. As is clear from Fig. 1, the piston 9
moves to the right, the second working chamber 13 contracts to indicate the discharge stroke, and conversely, the first working chamber 12 expands to indicate the suction stroke, but in the state shown in Fig. 1, the left and right pistons Since the heads 10 and 11 are both moved to a position with minimum head clearance, both the first and second working chambers 12 and 13 perform effective compression work (pumping action).

On the other hand, as shown in FIG. 2, when the pressure in the control pressure chamber 43 is set to suction pressure (low pressure) and the spool 38 is pushed to the right by the axial force due to the compression reaction force that the piston 9 receives. As the slider pin 31 moves to the right within the elongated hole 33, the arm pin 35 also moves within the cam groove 25 of the shaft, and the inclination angle of the swash plate 35 (with respect to the plane perpendicular to the shaft 15) becomes small. (In the case of Figure 2, it is close to zero.)

Therefore, the stroke of the reciprocating movement of the piston 9 becomes small, the compression ratio becomes small in the first working chamber 12, and no effective compression work (pumping action) is performed, but the center of the swash plate 28 moves to the right. However, as a result of the center of the reciprocating motion of the piston 9 also shifting to the right, the top clearance of the rad 11 to the rear piston is kept small as in Fig. 1.
The compression work (pumping action) of the second working chamber 13 is maintained.

Returning to FIG. 1, the front housing 4 is provided with a first suction chamber 47 in order to suck low-pressure fluid (for example, refrigerant gas) to be compressed into the first working chamber 12 and the second working chamber 13. , a second suction chamber 48 is provided in the rear housing 5.
are provided, which communicate with the swash plate chamber 29 by suction passages 49 and 50 bored in the front and rear cylinders 2 and 3, respectively. The swash plate chamber 29 communicates with the suction port 51, and in the case of an automobile air conditioner, receives refrigerant gas containing lubricating oil mist from a refrigerant evaporator. Each suction chamber 47.48 and each working chamber 12.1
A side plate 54.55 having a suction hole 52.53 that communicates with the suction chamber 3 is provided with a suction valve that opens when each working chamber 12.13 has a lower pressure than each suction chamber 47, 48. The intake valve is omitted in the drawing. Moreover, as is clear from FIGS. 1 and 2, the spool 3
The chamber 56 on the left side of the disc-shaped head 40 is the control piston of 8.
communicates with the suction chamber 48 and, as previously described, the spool 38
The differential pressure between the suction pressure and the control pressure chamber 43 generates an unparalleled control force that changes the axial position and inclination angle of the swash plate 28 to change the discharge capacity of the compressor.

Further, 57 is a first discharge chamber, 58 is a second discharge chamber,
Between these discharge chambers and each working chamber 12.13 are a discharge hole 59.60 and a discharge valve 61.62 that opens when the pressure in each working chamber becomes higher than the pressure in each discharge chamber. The above-mentioned side play) 54 and 55 are provided respectively. 2
The two discharge chambers 57 and 58 merge into a discharge passage (not shown), and in the case of an air-conditioned stomach for an automobile, are connected to a condenser. As mentioned above, the swash plate 28 is close to the state shown in FIG.
When the inclination angle becomes small, the compression ratio in the first working chamber 12 becomes small, and the pressure becomes such that the fluid compressed there pushes open the discharge valve 61 and flows out to the first discharge chamber 57. Therefore, the discharge valve 61 does not open, the first working chamber 12 becomes a dead volume, and no effective compression work is performed. As described above, even in such a case, the second working chamber 13 maintains the compression action in order to generate high pressure and push open the discharge valve 62 even if the discharge amount is small.

When the shaft 15 is rotationally driven by an automobile engine or the like, the swash plate 28 also performs a swinging movement in addition to the same rotational movement. The rotational motion component only causes the shoes 26 and 27 fitted in the piston 9 to slide against the peripheral edge of the swash plate 28, and does not cause any movement of the piston 9, but the swinging motion component causes the piston 9 to generate reciprocating motion in the axial direction, and the first working chamber 12 and the second working chamber 13, or the second working chamber 13 at the time of small capacity, performs fluid compression work. At this time, the shoes 26 and 27, which form part of the sphere, perform a tilting motion within the spherical surface provided in the recess at the center of each piston 9, with the peripheral edge of the swash plate 28 sandwiched therebetween.

In order to change the discharge volume, the pressure in the control pressure chamber 43 is changed by the pressure control valve 46, and the shaft portion 39 of the spool 38
It has also been mentioned that the slider pin 31 moves axially within the cylindrical portion 32 of the shaft 15 to allow the center of the slider bin 31 and the swash plate 28 to move axially. In this way, in this embodiment, the control force transmission mechanism using the spool 38 is mainly
It is characterized in that it is composed of a spool shaft portion 32 provided in a cylindrical portion 32 of the shaft 15 and a slider pin 31 that connects the swash plate 28 to the shaft 15, thereby making the control mechanism as a whole. Not only is the shaft 15 better and the structure simpler, but the shaft 15 can pass through the opening in the swash plate 28 and extend as a unit to near the right end of the rear cylinder 3, and the rear radial bearing 17 directly attached to the rear cylinder 3 allows the shaft 15 to be reliably and It also becomes possible to be firmly supported, and there is an advantage that glaze shift and accompanying shaft runout do not occur at all.

In this way, the shaft 15 has two radial bearings, the front radial bearing 16 and the rear radial bearing 17.
At this point, the shaft is directly supported by the housing 1, so that the axial movement of the spool 38 is smooth, and the cylindrical portion 32 of the shaft 15 and the shaft portion 39 of the spool 38 are connected to each other. Since the central axis does not tilt and can always maintain an immovable position, there is no large frictional force between the two, and the spool 3
8 does not rotate along with the shaft 15, and does not cause abnormal wear or seizure, and smooth capacity controllability and excellent durability can be obtained.

FIG. 3 shows a modification of the shaft portion 39 of the spool 38 inserted into the cylindrical portion 32 of the shaft 1, which is one of the essential parts of the present invention. 63 is formed.

The shaft portion 39 of the spool is for transmitting control force in the axial direction and does not require large bending rigidity. This reduces the area of friction between the spool 38 and the shaft 15, and more reliably prevents the spool 38 from being dragged around by the shaft 15.

〔Effect of the invention〕

With the configuration of the present invention, the shaft of the compressor is reliably supported by the plurality of bearings attached to the housing, and the central axis is maintained in an immovable position without causing any axial deviation or axial vibration. In addition to preventing abnormal wear and seizure by not applying excessive force to the shaft or spoon knob bearings, etc., the shaft of the spool is inserted into the cylindrical part of the shaft and connected directly to the swash plate. Since the control force transmission mechanism is engaged with the slider pin, the mechanism is simple and well-organized, is extremely robust, has good capacity controllability, and has high overall durability.

Further, since there is no axis deviation and there is little friction between the shaft portion of the spool and the cylindrical portion of the shaft, the spool is prevented from rotating along with the shaft, and the above effects are further enhanced in this aspect as well.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view showing one embodiment of the present invention, Fig. 2 is a longitudinal sectional front view showing another operating state of the same embodiment, and Fig. 3 is a longitudinal sectional view showing only the main parts of another embodiment. It is a diagram. DESCRIPTION OF SYMBOLS 1...Housing, 2...Front cylinder, 3...Rear cylinder, 4...Front housing, 5...Rear housing, 6...Through bolt,
7. 8...Cylinder bore, 9...Piston, 10
・11... Piston head, 12... First working chamber (front side), 13... Second
Working chamber (rear side), 14... Linear guide, 15... Shaft, 16...
...Front radial bearing, 17...Rear radial bearing, 18...Front thrust bearing, 19...Rear thrust bearing, 20...Shaft sealing device, 21, 22...Bushing, 23... Huge portion, 24... faces, 2
5...Cam L 26.27...C2-
28... Swash plate, 29... Swash plate chamber, 30
... Swash plate guide, 31 ... Slider pin, 32.
... Cylindrical part, 33... Long hole, 34... Arm, 35... Arm pin, 36... Arm roller, 37... Cylinder inner surface, 38... Spool,
39... Shaft portion, 40... Disc-shaped head (control piston), 41... Control cylinder, 42... O-ring, 43... Control pressure chamber, 44... Compression spring, 45 ...Snap ring, 46...Pressure control valve, 47...First suction chamber, 48...Second
Suction chamber, 49.50... Suction passage, 51... Suction port, 52.53... Suction hole, 54.55... Side plate, 56... Left side chamber, 57... No. 1 discharge chamber,
58...Second discharge chamber, 59.60...Discharge hole, 61, 62...Discharge valve, 63...Meat steal portion. Fig. 3 17... Rear radial bearing 32... Shaft cylindrical portion 59... Spool shaft portion 63... Thin portion

Claims (1)

[Claims] 1. The housing includes a housing in which a cylinder bore serving as a first working chamber and a cylinder bore serving as a second working chamber are provided facing each other, and a double-headed housing inserted astride the pair of facing cylinder bores. a piston, a shaft inserted into the housing and driven by external power, a swash plate driven by the shaft and engaged with the double-headed piston to provide reciprocating motion in the axial direction; and a swash plate provided on the shaft. A slider pin that is inserted into an axial elongated hole and serves as a center of tilting of the swash plate, a cam device that causes the swash plate to tilt, and a cam device that axially supports the shaft at a position before and behind the swash plate on the shaft. a cylindrical portion formed in a portion of the shaft end inserted into the housing that includes the elongated hole in the axial direction; The spool includes a shaft portion inserted into the cylindrical portion from the shaft end side and engaged with the slider pin, and a spool having a disk-shaped head that receives control fluid pressure in a control pressure chamber. A swash plate type variable capacity compressor.