JPH076507B2 - Variable capacity swash plate compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a variable displacement swash plate compressor.

(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 differential pressure 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 so that the top dead center of the compression stroke of the piston becomes a fixed position, it is possible to reduce the control limit on the small capacity side to the minimum capacity as much as possible. . However, in a wobble type compressor that controls the tilt angle of the swash plate by the pressure opposition 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 compared to a swash plate compressor equipped with a double-headed piston.

A variable capacity compressor having the cooling efficiency of a double-headed piston compressor is disclosed in Japanese Patent Application Laid-Open No. 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. It varies according to the plate tilt angle, and substantial compression and discharge cannot be performed even in the compression action region on the small capacity side where the swash plate tilt angle is larger than zero. That is, as the tilt angle of the swash plate becomes smaller, the residual amount of the refrigerant gas discharged in the compression chamber increases, and the residual gas re-expands in the suction stroke to decrease the suction amount, whereby compression and expansion without discharge are repeated. However, the controllable cooling load range cannot reach the level of the wobble compressor.

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. The dead point intended for the swash plate type compressor with a fixed position, provided with a control pressure chamber for capacity control, intervene sliding control member to vary the volume of the control pressure chamber,
The control pressure chamber and the discharge pressure region are connected to introduce a refrigerant gas equivalent to the discharge pressure into the control pressure chamber, and at the same time, the pressure in the front cylinder bore and the pressure in the control pressure chamber are passed through the swash plate and the sliding control body. The control pressure chamber and the suction pressure region are connected to each other, and the capacity control valve mechanism is interposed on this connection passage to urge the swash plate in the direction of decreasing the inclination angle against the pressure in the control pressure chamber. A control pressure correction means having a pair of spring members is provided for increasing the spring action force on the swash plate in response to an increase in the tilt angle only near the maximum tilt angle of the swash plate, and for both spring members. The spring characteristics were set so as to shift the starting position.

(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 fluctuates according to the differential pressure between the total pressure of the swash plate swinging force due to the pressure in the front and rear cylinder bores and the spring force of the pair of spring members and the pressure in the control pressure chamber. 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. In the compressor having the above structure, there is a pressure characteristic that the differential pressure between the pressure in the rear side cylinder bore and the pressure in the front side cylinder bore near the maximum inclination angle increases and then decreases as the inclination angle increases. 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. The pair of spring members corrects the pressure characteristic in the uncontrollable region, and by this correction, the required control pressure in the control pressure chamber increases (decreases) as the tilt angle increases (decreases) even near the maximum tilt angle.
To do. 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 a pin 9b is fitted in the middle portion of the swash plate 9 so as to project from both sides. The bridge 9a is sandwiched between both connecting bodies 5 and 6, and the pin 9b is fitted into the guide holes 5a and 6a of the connecting bodies 5 and 6, whereby the swash plate 9 rotates in the swash plate chamber 1a. Rotate with axis 4. Rotating shaft 4, swash plate 9 and guide bush 7
Are connected to each other in a guide relationship between the pin 9b and the guide holes 5a and 6a and in a rotatable relationship of the swash plate 9 with respect to the guide bush 7 which is slidable forward and backward, whereby the swash plate 9 slides on the guide bush 7. The swing center C is set on the peripheral side of the swash plate 9.

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.
The intake passages 1d and 1e are formed correspondingly on the rotation locus and between the front cylinder bore 1b and the rear cylinder bore 1c. Contains a double-headed piston 10. The double-headed pistons 10 and the swash plate 9 are engaged with each other via shoes 11 and 12, and the double-headed piston 10 reciprocates back and forth 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 distal end of the guide bush 7 is projected into the rear suction chamber 20 and the 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 swash plate rocking force generated by the pressure in the front side compression chamber Pf and the pressure in the rear side compression chamber Pr via 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 the discharge to the sliding partition 24 in the control pressure chamber 20a is performed. The action of refrigerant gas 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 element 33 is moving to the open side, and the discharge to the sliding partition 24 in the control pressure chamber 20a is performed. The action of the refrigerant gas is reduced. As a result, the sliding partition 24 is held on the right side as shown in FIG.
The inclination angle of the swash plate 9 becomes smaller. Therefore, the front and rear compression chambers Pf, Pr
In this case, the compression capacity becomes smaller and the small capacity operation is performed, and the suction pressure increases 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 corresponding to the maximum capacity is set, and the displacement position L corresponds to the minimum tilt position, and the curved line C1 shown by the broken line in the figure indicates the discharge capacity (% display).
Indicates. In the rear compression chamber Pr having a constant top dead center in the compression stroke, substantial compression is performed regardless of the tilt angle of the swash plate 9, but in the front compression chamber Pf, it corresponds to a singular point on the discharge capacity curve C1. From the displacement position L1 of the sliding partition body 24 to the small capacity side, compression and expansion without substantial discharge are performed.

Curves C2 and C3 show 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 changes from the increasing direction to the decreasing direction as the inclination angle of the swash plate 9 increases. Therefore, in order to increase (decrease) the tilt angle of the swash plate 9 near the maximum tilt angle, the control pressure chamber 20
The control pressure in a must be changed from the increasing (decreasing) direction to the decreasing (increasing) direction, but such continuous control is essentially impossible.

In view of this, in this embodiment, the guide bush 7 and the pair of pressing springs 8 and 36 constitute a control pressure correction means, and the guide bush 7 is directed in a direction opposing the pressure in the control pressure chamber 20a, that is, in the direction of decreasing the inclination angle of the swash plate 9. The pressure spring 8 in the guide bush 7 and the pressure spring 36 in the rear suction chamber 20 capable of urging the pressure are set to have spring characteristics shown by straight lines D1 and D2 in FIG. That is, the two pressing springs 8 and 36 increase the pressing force to the guide bush 7 only in the vicinity of the maximum tilt angle in accordance with the increase in the tilt angle, and the above-mentioned uncontrollable region is corrected by the cooperation of the two spring characteristics. The displacement position L2 of the sliding partition 24 in FIG. 4 corresponds to the left-hand chain line position in FIG. 3, and if it shifts from this position to the side of the minimum tilt angle L, the pressing spring 36 separates from the spring receiver 35 and the guide bush. The pressing action of the pressing spring 36 against 7 is eliminated. The displacement position L3 of the sliding partition 24 corresponds to the position of the right-hand chain line in FIG. 3, and if this position shifts to the side of the minimum tilt angle L, the pressing spring 8 separates from the inner end of the guide bush 7 and The pressing action of the pressing spring 8 disappears.

The pressing action start position L3 of the pressing spring 8 is set to the right side of the displacement position L1 corresponding to the singular point of the discharge capacity curve C1, and the pressing action start position L2 of the pressing spring 36 is set to the left side of the displacement position L1. Has been done. That is, the operating region of the pressing spring 8 is set with a margin so as to include the displacement position L1 that cannot be accurately specified, and the portion of the curve C3 with a small decrease variation near the displacement position L1 is the pressing spring 8 It is corrected by the pressing action of the low level region of. The operating area of the pressing spring 36 is set so as to include the curve C3 portion near the maximum tilt angle where the pressure spring relatively decreases and changes greatly. It is corrected by the total pressing action of the pressing action of the level region and the pressing action of the pressing spring 36.

By such a correction action of both the pressing springs 8 and 36, the curve C3 corresponding to the vicinity of the maximum tilt angle is corrected as the curve C4, and the necessary control pressure in the control pressure chamber 20a is changed to the tilt angle as shown by the curves C4 and C2. It will fall to the right over the entire area. 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.

Further, by setting the spring characteristics of the both pressing springs 8 and 36 as described above, it is possible to suppress the load per unit expansion and contraction amount in both of the pressing springs 8 and 36, and maintain good spring performance for a long period of time. be able to.

Of course, the present invention is not limited to the above-mentioned embodiment, and, for example, the spring characteristics of the pressing springs 8 and 36 in the above-mentioned embodiment are exchanged, or only one of the guide bush 7 and the rear suction chamber 20 has a pair of spring characteristics. Embodiments such as inserting a pressing spring or constructing a sliding partition by integrating the guide bush 7 and the sliding partition 24 are also possible.
It is also possible to employ 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 the suction pressure information.

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 increases (decreases) as the tilt angle increases (decreases) even near the maximum tilt angle, and as with the wobble compressor, it stabilizes from the maximum tilt angle to the minimum tilt angle side. It has an excellent effect that the above-mentioned capacity control can be performed.

[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 a housing to form both front and rear suction chambers. Is connected to the swash plate chamber via the suction passage, the front and rear discharge chambers are connected to the compressor outlet for discharging the refrigerant gas through the discharge passage, and the two-headed piston is housed in the front and rear cylinder bores so as to reciprocate. Is rotatably accommodated and supported, and a swash plate is supported on the rotary shaft so as not to be relatively rotatable and swingable back and forth around its peripheral side, and the swing center position is set near the rear cylinder bore. , The reciprocating region of the double-headed piston is set on the rotation region of the center of swinging associated with the rotation of the rotary shaft, and the double-ended piston is reciprocally driven by the rotation of the swash plate. The compression stroke top dead center position and the swash plate type compressor, provided with a control pressure chamber for capacity control, intervene sliding control member to vary the volume of the control pressure chamber,
The control pressure chamber and the discharge pressure region are connected to introduce a refrigerant gas equivalent to the discharge pressure into the control pressure chamber, and the swash plate swinging force generated by the refrigerant gas compression and the control pressure chamber through the swash plate and the sliding control body. 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, and the swash plate is inclined in the direction of decreasing the inclination angle against the pressure in the control pressure chamber. A control pressure correction means having a pair of spring members for urging is provided, and both spring members increase the spring action force on the swash plate only in the vicinity of the maximum inclination angle of the swash plate in accordance with the increase in the inclination angle. A variable displacement swash plate compressor in which spring characteristics are set so as to shift the spring action start position of the spring member.