JPH076505B2 - Variable capacity swash plate compressor - Google Patents

Description

The present invention relates to a variable displacement swash plate compressor having a double-headed piston.

(Prior Art) In a so-called wobble type variable displacement compressor in which a swash plate is supported so that it can swing back and forth with respect to a rotation shaft and can rotate relative to the rotation shaft, the tilt angle of the swash plate is equal to the control pressure in the swash plate accommodating chamber. It varies depending on the pressure difference through the piston with the suction pressure that reflects the cooling load, and the displacement displacement control according to the cooling load is performed by this tilt angle variation. Moreover, since the swing center of the swash plate is set in the vicinity of the reciprocating position of the piston viewed in the radial direction of rotation of the swash plate, the top dead center of the compression stroke of the piston is set at a fixed position. It is possible to make the control limit on the capacity side, that is, the minimum capacity as small as possible. However, in a wobble type compressor that controls the tilt angle of the swash plate by the pressure resistance between the control pressure and the suction pressure in the swash plate accommodating chamber, only one compression chamber can correspond to one piston. Inferior cooling efficiency cannot be denied in comparison with a swash plate compressor that does not have a variable function and that has a swash plate that rotates integrally with a rotary shaft and a double-headed piston.

A variable capacity compressor having the cooling efficiency of a swash plate compressor without a variable function is disclosed in JP-A-58-162782. In this compressor, a swash plate is supported integrally with a rotating shaft so as to be rotatable and swingable back and forth, and the tilt angle of the swash plate is controlled based on suction pressure information reflecting the cooling load. ing.

(Problems to be solved by the invention) However, since the swing center of the swash plate is set at a fixed position on the rotation axis, the top dead center of the compression stroke of the double-headed piston is inclined in both front and rear compression chambers. Even if the swash plate tilt angle changes depending on the plate tilt angle and the swash plate tilt angle is close to zero, it is not possible to perform substantial compression and discharge even in the compression acting region. That is,
As the tilt angle of the swash plate becomes smaller, the residual amount of refrigerant gas discharged in the compression chamber increases, and the residual gas is re-expanded in the suction stroke to reduce the suction amount, whereby compression and expansion without discharge are repeated. It will be just a state. Therefore, while having the same cooling efficiency as a swash plate compressor without a variable function, it is not possible to perform stable control on the small capacity side, and the controllable cooling load range can reach the level of a wobble type variable capacity compressor. There is an inconvenience that it does not exist.

Configuration of the Invention (Means for Solving Problems) In the present invention, therefore, a plurality of swash plate chambers for introducing a refrigerant gas, a pair of front and rear suction chambers, a pair of front and rear discharge chambers, and a plurality of front and rear pairs connecting these chambers are provided. The cylinder bore is partitioned within the housing, and the swash plate chamber and the front and rear suction chambers are connected by a suction passage, and the double-headed piston is housed in the front and rear cylinder bores so that it can reciprocate. In addition to supporting the swash plate, the swash plate is supported on the rotary shaft such that the swash plate cannot rotate relative to the rotary shaft and can swing back and forth around its peripheral side, and the swing center position is set near the rear cylinder bore and the rotary shaft rotates. The reciprocating region of the double-headed piston is set on the rotation region of the swing center associated with, and the compression stroke in the rear cylinder bore of the double-headed piston is reciprocally driven by the rotation of the swash plate. Targeting a swash plate type compressor with a dead point as a fixed position, a sliding partition body for partitioning and forming a control pressure chamber is interposed in the rear suction pressure chamber, and the control pressure chamber and the discharge pressure region are connected to each other to discharge. A refrigerant gas equivalent to the pressure is introduced, and the swash plate swinging force that reduces the tilt angle of the swash plate due to the pressure in the front and rear cylinder bores via the sliding partition body opposes the pressure in the control pressure chamber to control the control pressure. A pair of spring members for connecting the chamber and the suction pressure region, and interposing a capacity control valve mechanism on the connection passage, and for urging the swash plate in the inclination decreasing direction against the pressure in the control pressure chamber. A control pressure correction means is provided, and one spring member is set with a spring characteristic that increases the spring action force to the swash plate in accordance with the increase in the tilt angle of the swash plate, and the other spring member is provided. Is inclined only near the maximum inclination of the swash plate as the inclination increases. The spring characteristics were set to increase the spring action force on the plate.

(Operation) That is, by setting the swing center of the swash plate near the rear cylinder bore on the reciprocating region of the double-headed piston, the top dead center of the compression stroke of the double-headed piston in the front cylinder bore depends on the tilt angle of the swash plate. Although it fluctuates, the top dead center of the compression stroke in the rear side of the cylinder is fixed at a fixed position regardless of the tilt angle of the swash plate. The tilt angle of the swash plate is the pressure in the control pressure chamber,
It fluctuates according to the swash plate swinging force that reduces the swash plate angle due to the difference between the pressure in the front and rear cylinder bores, the suction pressure in the rear suction chamber, and the total pressure of the spring action forces of the pair of spring members. The capacity control valve mechanism controls the flow rate of the refrigerant gas from the control pressure chamber side to the suction pressure region side, and the flow rate control controls the pressure in the control pressure chamber for introducing the refrigerant gas corresponding to the discharge pressure. In the compressor configured as described above, the force for reducing the swash plate inclination angle due to the pressure in the rear side cylinder bore and the pressure in the front side cylinder bore decreases from an increase with an increase in the inclination angle near the maximum inclination angle, and a suction pressure near the minimum inclination angle. That is, there is a characteristic that the pressure in the compressor becomes negative, and the capacity control in the vicinity of the maximum tilt angle and in the vicinity of the minimum tilt angle cannot be performed only by the pressure control of the control pressure chamber excluding the action of the pair of spring members. The pair of spring members corrects the characteristic of the uncontrollable region, and by this correction, the required control pressure in the control pressure chamber increases (decreases) as the tilt angle increases (decreases) with a value exceeding the suction pressure.
Therefore, by controlling the pressure in the control pressure chamber, stable tilt angle control, that is, capacity control, can be performed over the entire tilt angle.

(Example) Hereinafter, one example which materialized the present invention is described based on a drawing. A front housing 2 and a rear housing 3 are joined and fixed to both front and rear end surfaces of a cylinder block 1 forming a housing, and a rotary shaft 4 is rotatably attached to the front housing 2 and the cylinder block 1 via a front shaft portion 4a. It is supported. A rear shaft portion 4b is connected and fixed to the inner end side of the front shaft portion 4a via connecting members 5 and 6, and guide members 5a and 6a are formed in the connecting members 5 and 6, respectively. A guide bush 7 is slidably fitted in the portion 4b, and a pressing spring 8 is interposed between the tip of the rear shaft portion 4b and the inner end of the guide bush 7.

The base end portion 7a of the guide bush 7 is formed into a spherical shape, and the swash plate 9 is rotatably fitted to the spherical surface portion 7a. A bridge 9a is formed on the front surface of the swash plate 9, and pins 9b and 9c are projectingly formed on both side surfaces of the middle portion thereof.
The bridge 9a is sandwiched between both connecting bodies 5 and 6, and
The pins 9b and 9c are fitted in the guide holes 5a and 6a of the coupling bodies 5 and 6, so that the swash plate 9 rotates together with the rotary shaft 4 in the swash plate chamber 1a. The guide relationship between the pins 9b, 9c and the guide holes 5a, 6a and the swash plate 9 for the guide bush 7 slidable back and forth.
The swash plate 9 can swing while sliding back and forth on the guide bush 7 due to the rotational relationship of the swash plate 9.
Is set on the peripheral side of.

On the front side and the rear side of the cylinder block 1, a plurality of cylinder bores 1b and 1c (five in this embodiment) are provided on the swash plate 9.
Are formed correspondingly on the rotation locus of the rocking center due to the rotation of, and suction passages 1d and 1e are formed between the front cylinder bore 1b and the rear cylinder bore 1c. A double-headed piston 10 is housed in each of the cylinder bore 1b and the rear cylinder bore 1c.
The double-headed pistons 10 and the swash plate 9 are engaged with each other through the shoes 11 and 12, and the double-headed piston 10 reciprocates back and forth at the rotation locus position of the swing center C as the swash plate 9 rotates.

Side plates 13 and 14 and valve forming plates 15 and 16 are interposed between the cylinder block 1 and the front and rear housings 2 and 3, and a suction chamber 17 is sucked between the front housing 2 and the side plate 13. It is partitioned so as to be connected to the front side intake passage 1d via the valve 15a, and the discharge chamber 18 is connected to the front side compression chamber Pf between the side plate 13 and the double-headed piston 10 via the discharge valve 19. It is partitioned and formed. Rear housing 3 and side plate
A suction chamber 20 is defined between the discharge chamber 21 and the suction chamber 21 so as to be connected to the rear suction passage 1e via a suction valve 16a.
Through the discharge valve 22 the side plate 14 and the double-headed piston 10
Is formed so as to be connected to the rear-side compression chamber Pr between and. Then, the front discharge chamber 18 and the rear discharge chamber 21
And are connected by the discharge passage 1f.

Refrigerant gas enters the swash plate chamber 1a from the inlet 23 as the double-headed piston 10 reciprocates, passes through the front suction passage 1d, the rear suction passage 1e, the front suction chamber 17, and the rear suction chamber 20, and the front compression chamber. It is sucked into Pf and the rear side compression chamber Pr and is compressed. Then, the refrigerant gas discharged from the compression chambers Pf, Pr is discharged from the outlet 30 via the front side discharge chamber 18, the rear side discharge chamber 21, and the discharge passage 1f in the cylinder block 1. The swing center C of the swash plate 9 is set on the peripheral side of the swash plate 9 and near the rear cylinder bore 1c, so that the top end of the compression stroke of the double-headed piston 10 in the front compression chamber Pf is reached. Varies depending on the tilt angle of the swash plate 9, but the top dead center of the compression stroke of the double-headed piston 10 in the rear compression chamber Pr is defined at the fixed position shown in FIGS.

The tip of the guide bush 7 is projected into the rear suction chamber 20, and a sliding partition 24 is fitted in the rear suction chamber 20 so as to be slidable in the front-rear direction. Is partly formed in the control pressure chamber 20a.
Sliding partition 24 and flange 7b at the tip of guide bush 7
A thrust bearing 25 is interposed between the flange portion 7b and the side plate 14, and a thrust bearing 26, a spring bearing 35, and a pressing spring 36 are interposed between the flange portion 7b and the side plate 14. The pressure opposes the sliding force that tends to reduce the swash plate inclination angle through the sliding partition 24, the guide bush 7 and the swash plate 9.

The control pressure chamber 20a and the rear discharge chamber 21 are connected by a pipe line 27, and a narrowed portion 27a is provided in the middle of the pipe line 27. A conduit 27 between the throttle portion 27a and the control pressure chamber 20a is connected to the swash plate chamber 1a via a conduit 28, and a capacity control valve mechanism 29 is interposed in the conduit 28. The control pressure chamber 20a is connected to the inflow port 29a of the capacity control valve mechanism 29, the swash plate chamber 1a is connected to the outflow port 29b, and the control port 29c has a suction pipe line 31 connected to the inlet 23. Pipeline 32
Connected through. The valve body 33 that controls the flow rate of the refrigerant gas from the inflow port 29a side to the outflow port 29b side is a total pressure of the pressure spring 34 and the atmospheric pressure that presses and urges the valve body 33 in the opening direction, and the suction refrigerant gas pressure. When the valve body 33 is moved downward by driving so as to maintain the suction pressure at the set value p by counteracting the pressure of, the part of the refrigerant gas corresponding to the discharge pressure in the control pressure chamber 20a is swash plate chamber according to the suction pressure. Flow into 1a.

When the suction pressure in the suction pipe line 31 is higher than the set value p, that is, when the cooling load is high, the valve body 33 is moving to the closing side and is discharged to the sliding partition 24 in the control pressure chamber 20a. A pressure equivalent to the pressure is introduced, and the effect of increasing the swash plate inclination angle is increasing. As a result, the sliding partition 24 is pressed and held to the left side as shown in FIG. 1, and the swash plate 9 is largely tilted. Therefore, the compression capacities in the front and rear compression chambers Pf, Pr become large values, large capacity operation is performed, and the suction pressure decreases toward the set value.
When the suction pressure in the suction pipe line 31 is lower than the set value p, that is, when the cooling load is low, the valve body 33 is moved to the open side, and the valve body 33 is inclined relative to the sliding partition body 24 in the control pressure chamber 20a. The effect of increasing the plate tilt angle is reduced. As a result, the sliding partition 24 is held on the right side as shown in FIG. 3, and the inclination angle of the swash plate 9 is reduced. Therefore, the compression capacity in the front and rear compression chambers Pf, Pr becomes a small value, the small capacity operation is performed, and the suction pressure rises toward the set value.

The origin of the horizontal axis in the graph of FIG. 4 is the maximum tilt angle of the swash plate 9,
That is, the displacement position of the sliding partition 24 is set to correspond to the maximum capacity, the displacement position L corresponds to the minimum tilt position, and the curve C1 shown by the broken line in the figure indicates the discharge capacity (% display). In the rear compression chamber Pr where the top dead center of the compression stroke is constant, substantial compression accompanied by discharge is performed regardless of the tilt angle of the swash plate 9, but in the front compression chamber Pf, the compression point becomes an inflection point on the discharge capacity curve C1. From the displacement position L1 of the corresponding sliding partition 24, compression and expansion without substantial discharge are performed on the small capacity side.

A curve C2 shows the necessary control pressure in the control pressure chamber 20a when the spring action of the pressure spring 8 in the guide bush 7 and the pressure spring 36 in the rear suction chamber 20 is removed. That is, the differential pressure between the total pressure of the pressure in the front-side compression chamber Pf and the pressure in the rear-side suction chamber 20 with respect to the sliding partition 24 and the pressure in the rear-side compression chamber Pr becomes the characteristic indicated by the curve C2. In the vicinity of the maximum inclination angle, the differential pressure turns from the increasing direction to the decreasing direction as the inclination angle of the swash plate 9 increases, and in the vicinity of the minimum inclination angle, the differential pressure becomes equal to or less than the suction pressure Ps indicated by the straight line D. Therefore, in order to increase (decrease) the tilt angle of the swash plate 9 near the maximum tilt angle, it is necessary to change the control pressure in the control pressure chamber 20a from the increasing (decreasing) direction to the decreasing (increasing) direction. Such continuous control is essentially impossible. Further, since the minimum pressure in the refrigerant gas circuit including the compressor is about the suction pressure Ps, the control pressure in the control pressure chamber 20a cannot be lower than the suction pressure Ps.
Tilt control near the minimum tilt is impossible.

In view of this, in this embodiment, the control pressure correction means is constituted by the guide bush 7 and the pair of pressing springs 8 and 36.
The pressure spring 8 in the guide bush 7 and the pressure spring 36 in the rear suction chamber 20 that can urge the guide bush 7 in the direction opposite to the internal pressure, that is, in the direction of decreasing the inclination angle of the swash plate 9, are linear in FIG. The spring characteristics are set to D1 and D2, and the uncontrollable region is corrected by the cooperation of both spring characteristics. That is, the pressing spring 8 applies a force to the guide bush 7 in the direction of increasing the tilt angle of the swash plate 9 in accordance with the increase in the tilt angle of the swash plate 9, and moves the entire curve C2 upward.
The pressing spring 36 increases the pressing force on the guide bush 7 only in the vicinity of the maximum tilt angle in response to the increase in the tilt angle, and prevents the curve C2 from falling to the left. The displacement position L2 of the sliding partition 24 in FIG. 4 corresponds to the chain line position in FIG. 3, and if the position shifts to the minimum tilt position L side, the pressing spring 36 separates from the spring receiver 35, and the guide bush 7 The pressing action of the pressing spring 36 against the is eliminated. With the correction action of both the pressing springs 8 and 36, the curve C2 is corrected over the entire tilt angle, and the control pressure chamber is
The required control pressure in 20a falls to the right over the entire tilt angle as shown by the curve C3, and exceeds the suction pressure Ps.
Accordingly, if the control pressure in the control pressure chamber 20a is increased or decreased in any region from the maximum inclination angle to the minimum inclination angle, the inclination angle of the swash plate 9 is increased or decreased accordingly, and continuous control of the discharge capacity becomes possible. Therefore, it is possible to achieve stable capacity control while achieving the same minimum capacity as the wobble type compressor.

Further, since the pressing spring 8 constantly acts on the guide bush 7, the thrust bearing 26 between the sliding partition 24 and the flange portion 7b is constantly in contact with both, and noise is not generated due to contact and separation between these members. Avoided.

The present invention is of course not limited to the above embodiment, but an embodiment in which an electromagnetic valve is adopted as the capacity control valve mechanism and the opening / closing control of the electromagnetic valve is performed based on suction pressure information is also possible.

EFFECTS OF THE INVENTION As described in detail above, the present invention provides a pair of variable displacement type swash plate type compressors having a predetermined spring characteristic as the control pressure in which the top dead center of the compression stroke of the rear side compression chamber of the double-headed piston is fixed. Since it is corrected by the spring member, the required control pressure will increase (decrease) as the inclination angle increases (decreases) near the maximum tilt angle, and the required control pressure will exceed the suction pressure even near the minimum inclination angle. Thus, the excellent effect that stable capacity control can be performed from the maximum tilt angle to the minimum tilt angle while achieving the same minimum capacity as that of the wobble type compressor is achieved.

[Brief description of drawings]

The drawings show an embodiment embodying the present invention. FIG. 1 is a side sectional view of a compressor and a displacement control valve mechanism, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. FIG. 4 is a side cross-sectional view showing a displacement operation state, and FIG. 4 is a graph showing fluctuations in control pressure and discharge capacity. A cylinder block 1 forming a housing, a front housing 2 and a rear housing 3, a rotary shaft 4, pressing springs 8 and 36 forming a control pressure correcting means, a guide bush 7, a swash plate 9, a double-headed piston 10, a rear suction chamber. 20 Control pressure chamber 20a, sliding partition 24, capacity control valve mechanism 29, swing center C.

Claims (1)

[Claims] 1. A swash plate chamber for introducing a refrigerant gas, a pair of front and rear suction chambers, a pair of front and rear discharge chambers, and a pair of front and rear cylinder bores connecting these chambers are defined in the housing, and the swash plate chamber is formed. The front and rear suction chambers are connected by a suction passage, and the rotary shaft is rotatably accommodated and supported in the housing that accommodates the double-headed pistons in the front and rear cylinder bores so that the pistons can reciprocate. It is impossible and can be rocked back and forth around its peripheral edge,
This swing center position is set near the rear side cylinder bore, and the reciprocating region of the double-headed piston is set on the rotation region of the swing center accompanying the rotation of the rotary shaft. In a swash plate compressor having a fixed top dead center of a compression stroke in the rear cylinder bore of a piston, a sliding partition body for partitioning a control pressure chamber is provided in the rear suction pressure chamber, and a control pressure chamber and a discharge pressure chamber are provided. The pressure in the control pressure chamber and the swinging force that tries to reduce the inclination angle of the swash plate due to the pressure in the front and rear cylinder bores through the sliding partition while introducing the refrigerant gas equivalent to the discharge pressure by connecting the area And the control pressure chamber and the suction pressure region are connected to each other, and a capacity control valve mechanism is interposed on this connection passage.
A control pressure correction means is provided which has a pair of spring members for urging the swash plate in a direction of decreasing the tilt angle against the pressure in the control pressure chamber, and one spring member has a tilt angle over the entire tilt angle region of the swash plate. A spring that sets a spring characteristic that increases the spring action force to the swash plate according to the increase, and a spring that increases the action force to the swash plate only in the vicinity of the maximum tilt angle of the swash plate to the other spring member Variable capacity swash plate compressor with specified characteristics.