JPH0474546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable stroke compressor, and particularly to a variable stroke compressor suitable for vehicle air conditioning.

[Conventional technology]

A conventional axial type compressor with a single swash plate mechanism is known from Japanese Patent Application Laid-Open No. 158382/1982, etc., but the position where the resultant force of the compression reaction force of a plurality of pistons arranged on a concentric circumference is in the direction of top dead center. On the other hand, in the variable stroke mechanism, the fulcrum pin that supports the resultant force is disposed offset in the direction of the top dead center, although it is displaced in the shaft rotation direction.

[Problem that the invention seeks to solve]

The above conventional technology does not take into account the relationship between the resultant force of the compression reaction force of the piston and the swash plate support pin, and unreasonable force acts on each component of the variable stroke mechanism during operation, which deteriorates the durability and reliability of the compressor. There was a problem with negative effects.

The purpose of the present invention is to prevent excessive force from acting on the component parts of the variable stroke mechanism due to the compression reaction force of the piston during operation, and to improve the durability of each component and the reliability of the variable stroke mechanism's smooth operation. The goal is to improve.

[Means for solving problems]

The above object is achieved by supporting the variable stroke mechanism near the rear on the line of action of the resultant force of the compression reaction forces acting on each piston during operation.

Preferably, the resultant force of the compression reaction force of each piston is
Since it acts on the swash plate in the direction of top dead center and at a position shifted in the direction of shaft rotation, the protrusion (drive plate) fixed to the shaft will then support the resultant force via the fulcrum pin, i.e. transmitting rotational force by contacting the ears provided on the swash plate;
This is achieved by shifting the contact surface of the protrusion fixed to the shaft in the direction of top dead center and in the direction of shaft rotation so as to bring it closer to the line of action of the resultant force.

[Effect]

With the above means, the line of action of the resultant force of the compression reaction force of each piston acting on the swash plate becomes very close to the line of action of the reaction force from the shaft protrusion that supports it via the fulcrum pin, and these By combining these forces, the moment force generated on the swash plate can be made extremely small.

The moment force generated on the swash plate due to the combination of the above forces can be supported by the shaft via the pin and sleeve described below, or supported by the fulcrum pin.
It will be supported by the cam groove of the protrusion fixed to the shaft. Therefore, the line of action of the resultant force of the compression reaction force of each piston acting on the swash plate becomes close to the line of action of the reaction force from the shaft protrusion that supports it via the support pin, which prevents prying between the parts. Since the moment force that causes this can be kept very small, the above problem can be prevented from occurring.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. In the compressor shown in FIG. 1, the swash plate is at its maximum tilt angle, that is, the piston stroke is at its maximum. In this compressor, shaft 1
The drive plate 2 is fixed by press fitting or a dowel pin. A cam groove 3 is provided in the drive plate, and a fulcrum pin 4 is provided in the groove so as to be movable along a cam curve, and at the same time, the fulcrum pin 4 is fitted into an ear portion 6 of a swash plate 5. There is. Further, the ear portion 7 (the above-mentioned protrusion) provided with the cam groove 3 of the drive plate 2 and the swash plate ear portion 6 are structured so as to come into contact with each other in the rotational direction on a plane parallel to the shaft 1. . (See FIG. 2) As a result, when the drive plate 2 rotates due to the rotation of the shaft 1, rotational force is applied from the ear portion 7 of the drive plate to the ear portion 6 of the swash plate 5, causing the swash plate 5 to rotate. A sleeve 8 is incorporated into the shaft 1 so as to be slidable at least in the axial direction with respect to the shaft, and the sleeve is connected to the swash plate 5 by a pin 9 parallel to the fulcrum pin 4. It is rotatably fastened around 9. Therefore, as the shaft 1 rotates, the drive plate 2, swash plate 5, and sleeve 8 rotate together. A piston support 11 is rotatably fitted to the swash plate 5 via a bearing 20, and a retaining ring 12 is fixed to the swash plate 5.
As a result, the inner ring of the bearing 20 is fixed to the swash plate 5 so as not to move in the direction of its rotation axis. On the other hand, the piston support 11 is connected to the bearing 1 by the protrusion 13.
0, movement to the right in the figure is restricted, and movement to the left in the figure is restricted by a thrust bearing 20 installed between the swash plate 5 and the swash plate 5. The piston support 11 also has a shaft 1 in the radial direction.
4 is fixed by a method such as press fitting, and the shaft 14
A ball 15 is fitted so that it can rotate and slide. In order to prevent the piston support 11 from rotating around the axis of the shaft 1, the ball 15 is provided with an axial groove 17 having an arcuate cross-sectional shape provided on the inner circumference of the front cover 16.
The movement around the axis of the shaft 1 is regulated.

Further, a plurality of connecting rods 18 having spherical sections at both ends are attached to the piston support 11 so as to be rotatable around the center by one spherical section, and a piston 19 is attached to the spherical section at the other end.
is rotatably attached around the center of the spherical surface. The piston 19 is connected to a cylinder bore 21a (sixth cylinder bore 21a) provided in the cylinder block 21.
(see figure). The cylinder block 21 is provided with a suction valve plate 22 provided with a suction valve, a cylinder head 23, a discharge valve (not shown), a discharge valve support/packing 24, and a rear cover 25. 5. It is fixed integrally with a front cover 16 formed to surround the piston support 11 etc. with bolts or the like. The cylinder head 23 is provided with an intake port and a discharge port (not shown) corresponding to each cylinder bore 21a. The rear cover 25 includes a low pressure chamber 27 in which only the suction port is open and communicates with the suction port 26 of the compressor;
Only the discharge port is open, and a high pressure chamber 28 is provided which communicates with a discharge port (not shown) of the compressor. Further, the compression reaction force of each piston that finally acts on the shaft 1 due to the compression action of the compressor is absorbed by the thrust bearing 29 installed between the drive plate 2 and the front cover 16.
Further, the radial force acting on the shaft 1 is received by radial bearings 30 and 31 provided on the front cover 16 and the cylinder block 21.

Further, a pressure control valve 32 is incorporated in the rear cover 25, and the pressure control valve 32 is connected to a valve body 3.
4, a bellows 35, and a seal plate 39.

Suction gas flows in through the suction port 26 provided in the rear cover 25, flows into the low pressure chamber 27 through the pressure control valve 32, and is finally sucked into the compression chamber (not shown) via the suction valve 22. The passageway is structured so that

Further, the swash plate chamber 37 is connected to the upstream side of the pressure control valve 32 by a communication passage 33.

In the compressor of this structure, the pressure control valve 3
2, when the upstream suction gas pressure is higher than a predetermined pressure, that is, when the heat load of the refrigeration cycle is high relative to the compressor capacity, the bellows 35 contracts as shown in Fig. 1, and the valve body 34 lowers to change the opening degree. becomes large, the differential pressure before and after the pressure control valve 32 is small, and the pressure of the gas sucked into the compression chamber is high. In this state, since the pressure acting on the head of the piston 19 is high, the force pushing the swash plate 5 through the piston 19, the connecting 18, and the piston support 11 causes
Moment that tilts the swash plate 5 (clockwise in the figure)
increases, and the swash plate reaches its maximum tilt as shown in Figure 1.
That is, the piston stroke is controlled in the direction in which it is maximized.

On the other hand, when the suction gas pressure upstream of the pressure control valve 32 becomes lower than a predetermined pressure, that is, when the heat load of the refrigeration cycle is low relative to the compressor capacity, the bellows 35 extends and the valve body 34 moves upward. , the valve opening becomes smaller, the pressure difference across the pressure control valve 32 becomes larger, and the pressure of the gas sucked into the compression chamber becomes lower. In this state, the piston 19
Since the pressure acting on the head of the piston is relatively low, the pressure acting on the back surface of the piston head is relatively low.
7 (control valve upstream pressure) increases, and the force due to this differential pressure generates a moment (counterclockwise in the figure) that makes the swash plate 5 stand up, and the swash plate 5 reaches its minimum tilt, that is, the piston. The stroke is controlled in the direction that minimizes it.

Based on the above principle, in the compressor of this embodiment, the swash plate angle, that is, the piston stroke, can be increased or decreased to change the capacity of the compressor according to the thermal load.

The above is the basic structure, but in this example, in particular,
As shown in FIG. 2, the ear portion 7 of the drive plate 2
is formed such that its center is offset in the rotational direction of the shaft 1, and a corresponding swash plate 5 is formed.
The contact surface A with the ear portion 6 of the drive plate is the contact surface of the drive plate ear portion 7' without the conventional offset.
Compared to A', the amount of offset from the shaft center axis (indicated by the broken line in the figure) is larger (l ₁ > l ₂ ).

Figures 3 to 5 show the variable stroke type compressor (5 cylinders) of this embodiment during operation.
This is a diagram showing a state in which the piston of the book is at the top dead center position, with only the internal variable stroke mechanism taken out and viewed from the top dead center direction. In Fig. 3, the piston below the center line is in the compression stroke, and the pressure acting on the piston head is the pressure acting on the back of the piston (swash plate chamber pressure = compressor inlet pressure).
The differential pressure acts to the left as shown by the arrow in the figure. Further, the closer the piston is to this side, the closer the compression stroke is to the final stage of the compression stroke, and the above-mentioned differential pressure is large. On the other hand, all the pistons above the center line are in the suction stroke state, and the pressure acting on these piston heads is in a high heat load state whose stroke is not controlled by the pressure control valve (Fig. 1-32). In this case, the compressor inlet pressure, that is, the pressure in the swash plate chamber acting on the back of the piston is approximately equal, and the differential pressure between these can be considered to be zero. Therefore, the position where the resultant force of the compression reaction force generated by the pressure difference before and after all the pistons acts is as shown in Figure 1.
and near the position indicated by arrow F _b in FIG.

More precisely, the position of action of the resultant force of the above compression reaction force is 5
Figure 6 shows the calculations for the cylinder.
In FIG. 6, circle C represents a plurality of piston bores 21.
The arrangement circle (diameter φ _d ) in which a is arranged is shown.
The upper part of the figure indicates the top dead center direction, that is, the direction in which the swash plate is closest to the cylinder. The above-mentioned direction of the top dead center rotates with the rotation of the shaft, but since FIG. 6 is shown in a rotating coordinate system that rotates with the shaft, the direction of the top dead center is always upward.

At this time, for the reason explained in FIG. 3, the resultant force of the compression reaction force acts on the upper left position in FIG. 6, but in reality, the acting position is one closed curve D as shown in FIG. It moves periodically along with the rotation of the shaft. (This period is 360°/n in shaft rotation angle when the number of cylinders in the compressor is n.) This means that when the shaft rotates from the state shown in Figure 3, the position of each piston relative to the top dead center direction. This is because the differential pressure acting on each of them changes with a period of 360°/n. Furthermore, the closed curve D, which is the moving locus of the point of application of the resultant force of the compression reaction force, changes depending on the operating conditions, that is, the compressor suction pressure Ps and the discharge pressure _Rd . conditions (durability test conditions)
The calculation results for the case of P _d =30Kg/cm ² G and Ps = 2Kg/cm ² G are shown.

Note that the point of action of the resultant force of the compression reaction force not only moves on the closed curve described above, but also changes the magnitude of the force, reaching a maximum value near point E in the figure. Change in point E from top dead center direction l _E is piston arrangement diameter φ _d
When =φ70mm, it is approximately 7.5mm, which is approximately 22% of the arrangement radius (=φ _d /2).

Returning to Figures 3 and 4, if there is no offset in the conventional drive plate ear 7' shown by the broken line in the figures, the A' plane is centered relative to the line of action of the resultant force of the compression reaction force (arrow F _b ). Since it is located near the line, the supporting force F _f ' from the drive plate ear 7' acts within the plane of the edge A' of the ear, forming a couple with the force F _b on the swash plate, as shown by the broken line in the figure. Generates a rotational moment M _A ′.

In order to support this rotational moment M _A ′, the cam groove 3
A prying point P occurs between the fulcrum pin 4 and the swash plate 5, the pin 9, the sleeve 8 (Fig. 4), and the shaft 1, which may affect the durability of each part and the smoothness of the variable stroke mechanism. Decreases operational reliability.

In contrast, the drive plate ear portion 7 of the embodiment of the present invention shown by the solid line is offset in the shaft rotation direction, and the A side is located outside of the central axis relative to the resultant force F _b of the compression reaction force, and the drive plate ear portion 7 is offset in the shaft rotation direction. The supporting force F _f from the ear portion 7 acts inside the cam groove immediately behind the resultant force F _b of the compression reaction force, and unlike the conventional example, no rotational moment is generated in the swash plate 5. No problems occur due to this.

It is desirable that the amount of offset _l1 of surface A from the axis of rotation of the shaft be at least greater than the displacement _lE of point E from the top dead center direction in FIG. (No rotational moment is generated on the swash plate when F _b is the largest.) In other words, we want l _pff >φ _d /2×0.22.

〔Effect of the invention〕

As described above, according to the present invention, in a variable stroke mechanism, it is possible to reduce the rotational moment that causes strain between the cam groove of the drive plate and the fulcrum pin, or between the swash plate, pin, sleeve, and shaft parts. This has the effect of improving durability and reliability.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the overall structure of an embodiment of the compressor of the present invention, FIG. 2 is a sectional view taken along the line -- in FIG. 1, and FIG. 3 is a central portion of the variable stroke mechanism explaining the effects of the present invention. FIG. 4 is a perspective view, FIG. 4 is a sectional view taken from FIG. 1, FIG. 5 is a sectional view taken from FIG. . 1...Shaft, 2...Drive plate, 3
...Cam groove, 4...Fully pin, 5...Swash plate, 6,
7...Ear part, 8...Sleeve, 9...Pin.

Claims (1)

[Claims] 1. A shaft that is rotationally driven in a predetermined direction, a drive plate attached to the shaft,
A swash plate is connected to the drive plate via an ear for torque transmission, and the strokes of the plurality of pistons are variably controlled by changing the angle of inclination of the swash plate with respect to the shaft using the cam groove of the ear. In the swash plate type variable stroke compressor, the mounting position of the ear with respect to the drive plate and the ear is parallel to the rotation direction of the shaft from a perpendicular position passing through the rotation center line of the shaft. A variable stroke compressor characterized in that it is configured to be offset by a predetermined distance. 2. In claim 1, the predetermined offset distance is based on the radius of the bore center arrangement of the plurality of cylinders into which the plurality of pistons are fitted.
A variable stroke type compressor characterized by being set at 22% or more. 3 In what is stated in claim 1,
A variable stroke compressor characterized by an offset range of 22% or more of the radius of the cylinder bore relative to the shaft rotation axis. 4. A swash plate with a variable tilt angle, a piston support that is given rocking motion by the swash plate, and a plurality of piston supports that are connected to the piston support by a connecting rod and that reciprocate in the axial direction within the cylinder bore. In a variable stroke compressor having a piston and a pressure control means for generating a differential pressure between a drive section space and a cylinder working chamber suction pressure, the swash plate is attached to a protrusion (drive plate) fixed to the shaft. When the tilting angle of the swash plate changes, it comes into contact with an ear provided on the swash plate near the center of rotation, forming a contact surface parallel to the axis of shaft rotation that transmits rotational torque to the swash plate. A variable stroke compressor characterized by being configured to be shifted in the direction of top dead center and in the shaft direction so as to approach the line of action of the resultant force of compression reaction forces acting on each piston during operation.