JPH0676794B2 - Variable capacity swash plate compressor - Google Patents

Description

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

[Prior Art] A variable capacity compressor having the cooling efficiency of a double-headed piston compressor is disclosed in Japanese Patent 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. However, since the swing center of the swash plate is set to a fixed position on the rotation axis, the top dead center of the compression stroke of the double-headed piston fluctuates according to the swash plate tilt angle in both the front and rear compression chambers. In the compression action area on the small capacity side where the tilt angle is close to zero side, substantial compression and discharge cannot be performed.

A variable capacity compressor that has improved this drawback is disclosed in JP-A-63-147977.
It is disclosed in the publication. In this compressor, the swing center of the swash plate is set at the radial position of the rotary shaft corresponding to the cylinder bore of the cylinder block accommodating the double-headed piston, and the rotation center position of the swash plate is variable. Therefore, the top dead center of the compression stroke in the cylinder bore on one side of the double-headed piston is defined at a fixed position, and substantial compression and discharge are performed even in the compression action area on the small capacity side where the swash plate tilt angle is close to zero.

The swash plate tilt angle changes the volume of the control pressure chamber that is switched and connected to the discharge pressure region or the suction pressure region.The swash plate swinging force and the pressure in the control pressure chamber due to the pressure in both front and rear cylinder bores through the sliding control body and the swash plate. The sliding control body is slidably supported on the rotary shaft. The acting force applied to the rotary shaft by the swash plate swinging due to this pressure resistance is received by the guide hole on the rotary shaft side via the guide pin on the swash plate side, and the swash plate tilt angle is changed by the guide relationship between the guide pin and the guide hole. It is controlled.

[Problems to be Solved by the Invention] In the conventional device, in order to prevent an excessive load from being applied to the thrust bearing that bears the thrust load at the time of maximum capacity, the sliding control body is brought into contact with the stopper to prevent the sliding control body from sliding. Had regulated the position of.

However, when the position of the sliding control body at the maximum capacity is regulated by abutting it on the stopper, the sliding control body abuts on the stopper to adjust the stroke and top clearance during assembly. There is a problem that it is necessary to sharpen the surface and it takes a lot of time and labor.

In addition, the conventional compressor cannot bring about a monotonic increase in the control pressure on the maximum capacity side, and in this region it is necessary to correct the control pressure in the pulling direction using a correction spring.
The configuration in which the correction spring is interposed between the rotary shaft and the sliding control body complicates the mechanism. Further, when the ratio between the discharge pressure and the suction pressure, that is, when the compression ratio is low, it is necessary to increase the spring force of the correction spring to raise the control pressure for correction. In this way, when the correction spring for increasing the control pressure on the maximum capacity side is used, the delay in the start time of the capacity change from 100% capacity to the low capacity side, that is, the pressure in the control pressure chamber decreases. However, there is a problem that the movement of the sliding control body is not started in synchronization with the decrease of the pressure, and a dead zone for the control pressure appears.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to eliminate the need for adjusting the stroke and the top clearance at the time of assembling, and to eliminate the dead area on the maximum capacity side. The object of the present invention is to provide a variable displacement swash plate compressor having improved followability and improved capacity controllability.

Means for Solving the Problem] In order to achieve the above object, in the present invention, a control pressure chamber for capacity control that is switched to a pressure equivalent to a discharge pressure or a suction pressure is provided, and the volume of the control pressure chamber is changed. The sliding control body to be changed is slidably supported on the rotating shaft in the axial direction thereof, and the suction pressure acts on the surface of the anti-control pressure chamber of the sliding control body. The motive power and the pressure in the control pressure chamber are opposed via a swash plate and a sliding control body, and a guide pin is attached to the swash plate side which is swung by this opposition, and the guide pin and the guide relationship are provided on the rotary shaft side. Is provided as a guide curve for defining the shape of the large-capacity side of the guide hole with the displacement position of the guide pin in the axial direction of the rotating shaft as a variable. Monotonically increasing By adopting a large and downwardly convex curve, the pressure in the control pressure chamber applied to the sliding control body at the maximum capacity at the maximum compression ratio generated in the refrigerant circuit and the pressure applied to the sliding control body from the anti-control pressure chamber side The pressure receiving area of the sliding control body was set so that

[Operation] The swash plate tilt angle changes depending on the pressure difference between the swash plate swinging force due to the pressure difference in the front side cylinder bore and the rear side cylinder bore and the pressure in the control pressure chamber. The acting force of the swash plate on the rotary shaft is received by the guide hole on the rotary shaft side via the guide pin on the swash plate side, and the tilt angle of the swash plate is also controlled by the guide relationship between the guide hole and the guide pin. The guide pin is displaced along the guide curve, but on the large capacity side, a guide curve that is monotonically increasing and convex downward is adopted as the guide curve with respect to the displacement of the guide pin in the increasing direction of the swash plate inclination. The pressure increases monotonically with the displacement of the guide pin in the direction of increasing the tilt angle of the swash plate. Further, since the pressure in the control pressure chamber, that is, the discharge pressure applied to the sliding control body at the maximum capacity (at 100% capacity) and the pressure applied to the sliding control body from the side opposite to the control pressure chamber are balanced, the sliding control body The position is maintained at a predetermined position without a stopper that restricts the displacement of the sliding control body in the rotation axis direction. This holds even when the compression ratio is changed except when the compression ratio is low, and even when the compression ratio is low, the required control pressure at the maximum capacity is equal to or lower than the discharge pressure and close to the discharge pressure. , Even if there is no stopper, there will be no control problems. In addition, since there is no correction spring for increasing the control pressure on the maximum capacity side, the sliding control body follows the change of the control pressure when the capacity is decreased from the maximum capacity, and the dead area is reduced. The controllability is improved.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, 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, and a rotary shaft 4 is attached to the front housing 2 and the cylinder block 1 and a front shaft portion 4a. It is rotatably supported via. The rear shaft portion 4b is connected and fixed to the inner end side of the front shaft portion 4a via the bearing receiving plate 5 and the connecting members 6 and 7, and the connecting members 6 and 7 are formed with guide holes 6a and 7a. A thrust bearing 8 is interposed between the bearing receiving plate 5 and the inner end of the cylinder block 1.

A guide bush 9 is slidably fitted to the rear shaft portion 4b. A shaft pin 10 (only one is shown) is provided on both left and right sides of the base end portion of the guide bush 9 and the shaft pin 10 is provided.
A swash plate 11 is rotatably supported by the. A bridge 11a is formed on the front surface of the swash plate 11, and guide pins 12 are fitted to the middle portion of the swash plate 11 so as to project to both sides, and a rotor 13 is attached to both end portions of the guide pin 12. Has been. The bridge 11a is sandwiched between both connecting bodies 6 and 7, and both rotors 13 are fitted in the guide holes 6a and 7b of the connecting bodies 6 and 7, whereby the swash plate 11 is inside the swash plate chamber 14. To rotate with the rotating shaft 4.

The rotating shaft 4, the swash plate 1 and the guide bush 9 are guide pins.
12 and the guide holes 6a, 7a, and the swash plate 11 is pivotally connected to the guide bush 9 slidable back and forth. As a result, the swash plate 11 can swing with the slide of the guide bush 9, and the swing center C is set on the peripheral side of the swash plate 11. Swash plate
A double-headed piston 15 is housed in a plurality of front-side cylinder bores 1a and rear-side cylinder bores 1b formed correspondingly on the rotation locus of 11, and the plurality of double-headed pistons 15 are accommodated.
The swash plate 15 and the swash plate 11 are engaged with each other through the shoes 16 and 17, and the double-headed piston 15 reciprocates back and forth as the swash plate 11 rotates.

Partition plates 18 and 19 and valve forming plates 20 and 21 are interposed between the cylinder block 1 and the front and rear housings 2 and 3, and suction chambers 22 and 23 and a discharge chamber 24 are provided in the front and rear housings 2 and 3. , 25 are sectioned. Refrigerant gas in the suction pipeline 26 constituting the external refrigerant gas circuit enters the swash plate chamber 14 from the inlet 27 as the double-headed piston 15 reciprocates, and the front side suction passage 28, the rear side suction passage 29, and the front side. Inhalation chamber 22
Also, it is sucked into the front side compression chamber Pf and the rear side compression chamber Pr via the rear side suction chamber 23 and the suction ports 18a, 19a opened / closed by the suction valves 20a, 21a to be compressed. The refrigerant gas discharged from both compression chambers Pf, Pr to discharge chambers 24, 25 through discharge ports 18b, 19b opened and closed by discharge valves 30, 31 is discharged from outlet 33 via discharge passage 32.

The swing center C of the swash plate 11 is set on the peripheral side of the swash plate 11 and near the rear cylinder bore 1b, whereby the top dead center of the compression stroke of the double-headed piston 15 in the front compression chamber Pf is set. Although it changes according to the angle of inclination of the swash plate 11, the top dead center of the compression stroke of the double-headed piston 15 in the rear compression chamber Pr is defined at the fixed position shown in FIG. Therefore, when the swash plate tilt angle is small in the front compression chamber Pf, only compression and expansion without substantial suction and discharge are performed, but in the rear compression chamber Pr where the top dead center of the compression stroke is constant, there is no slope. A substantial compression action involving suction and discharge is performed regardless of the tilt angle of the plate 11.

A sliding control body 34 having a cylindrical shape with a bottom and a flange portion 34a at the rear end is fitted in the rear suction chamber 23 so as to be slidable in the front-rear direction, and the rear suction chamber 23 is fitted by the flange portion 34a.
Is partly formed in the control pressure chamber 23a. The sliding control body 34 has its cylindrical portion 34b supported by the guide bush 9 via a thrust bearing 35 and a radial bearing 36 so as to be relatively rotatable. As a result, the pressure in the control pressure chamber 23a becomes the swash plate swinging force generated by the pressure in the front side compression chamber Pf and the pressure in the rear side compression chamber Pr via the slide control body 34, the guide bush 9 and the swash plate 11. Oppose.

The sliding control body 34 has a compression ratio, that is, a ratio of the suction pressure Ps and the discharge pressure Pd.
The maximum compression ratio where Ps / Pd occurs in the refrigerant circuit, eg Ps / Pd =
The pressure in the control pressure chamber 23a applied to the sliding control body 34 at the maximum capacity in 3/31, that is, the control pressure equal to the discharge pressure, and the pressure applied to the sliding control body 34 from the side opposite to the control pressure chamber are balanced. The pressure receiving area of the sliding control body 34 is set.

The control pressure chamber 23a, the rear discharge chamber 25 in the discharge pressure region, the swash plate chamber 14 in the suction pressure region, and the suction pipe line 26 are connected to a capacity control valve mechanism (not shown), and the displacement of the sliding control body 34 in the front and rear direction is prevented. It is designed to be controlled by the fluctuation of the suction pressure in the suction pipe line 26. That is, the control pressure chamber 23a is switched to the high pressure equivalent to the discharge pressure or the low pressure equivalent to the suction pressure by opening / closing the valve in the capacity control mechanism based on the suction pressure in the suction pipe line 26, and the swash plate 11 is controlled.
Is arranged to switch between a maximum tilt angle position shown in FIG. 1 and a minimum tilt angle position (not shown).

The swing of the swash plate 11 is guided through the shape of the guide holes 6a, 7a on the rotating shaft 4 side and the rotor 13 on the swash plate 11 side, and the guide holes 6a, 7a for providing this guiding action are Is obliquely intersected with the axis line 1 of. Displacement curve of guide pin 12, that is, guide hole
As shown in FIG. 3, the guide curve S of 6a and 7a has a displacement position x _{0 with the} displacement position x of the guide pin 12 in the axial direction as a variable.
Has an inflection point s ₀ , and at x ₀ ≦ x ≦ x ₁ on the large capacity side, the slope α of the tangent line of the guide curve S increases as the variable x increases, that is, a positive monotone increase curve, that is, the swash plate inclination angle increases A monotonically increasing and downwardly convex curve is used for the displacement of the guide pin 12 in the direction, and when 0 ≦ x ≦ x ₀ , the slope α of the tangent line of the guide curve S decreases as the variable x increases. Is used. The displacement position x ₁ of the guide pin 12 is the position of the shaft pin 10 shown by the solid line in FIG. 3, that is, the swash plate inclination angle β
Corresponds to the maximum discharge capacity, and the discharge capacity becomes maximum. The displacement position x = 0 of the guide pin 12 corresponds to the position of the shaft pin 10 shown by the chain line on the right side of FIG. 3, that is, the case where the swash plate inclination angle β is minimum, and the discharge capacity is minimum.

Next, the operation of the compressor configured as described above will be described. When an electromagnetic clutch (not shown) is connected and the rotational driving force of the engine is transmitted to the rotary shaft 4, the swash plate 11 rotates integrally with the rotary shaft 4. Since the swash plate 11 is inclined with respect to the rotating shaft 4, the rotation of the swash plate 11 is accompanied by rocking. The swing of the swash plate 11 is transmitted to the double-headed piston 15 via the shoes 16 and 17, and the double-headed piston 15 reciprocates in the cylinder bores 1a and 1b.

The discharge capacity of the compressor is variably controlled by changing the tilt angle of the swash plate 11. FIG. 1 shows a state in which the inclination angle of the swash plate 11 is maximum, and the discharge capacity of the compressor is maximum in this state. At this time, the control pressure in the control pressure chamber 23a is applied to the rear surface of the sliding control body 34, and the swash plate vibration generated on the front surface by the pressure in the front compression chamber Pf and the pressure in the rear pressure chamber Pr. Power and suction pressure are added. Further, since the sliding control body 34 has its pressure receiving area set so as to balance the two when the discharge pressure is applied as the control pressure at the maximum capacity, the sliding control body 34 corresponds to the control pressure. It is moved to a predetermined position and held at that position. That is, since a stopper for restricting the position of the sliding control body 34 at the time of maximum capacity is unnecessary, it is not necessary to adjust the stroke and the top clearance when assembling the compressor, and the time and labor required for the assembling are reduced. Significantly reduced.

Maximum compression ratio generated in the circuit, that is, suction pressure Ps and discharge pressure Pd
When and are expressed in units of (kgf / cm ² abs), the ratio is Ps / P
Shows the relationship between the balance Pc and the capacity ratio when the pressure receiving area of the sliding control body 34 is set so that the balance Pc (required control pressure) at 100% capacity at d = 3/31 becomes equal to the discharge pressure Pd. The diagram is shown in FIG. 4 (f). The balance Pc monotonically decreases from the capacity ratio of 100% as the capacity ratio decreases. The values of the compression ratio Ps / Pd of the sliding control body 34 having this pressure receiving area are variously changed, and the result of the relationship between the balance Pc and the capacity ratio obtained by the simulation for each compression ratio is
It shows in figure (a)-(e). As is clear from the figure, Ps / P
When the value of d is as large as 3/26, 3/21, 3/16, the balance Pc at 100% capacity takes a value equal to the discharge pressure Pd as in the case of 3/31. 10 even if the compression ratio is relatively small, 3/8
The balance Pc at 0% capacity is below the discharge pressure and takes a value close to the discharge pressure. That is, the pressure in the control pressure chamber 23a applied to the sliding control body 34 at the time of maximum capacity at a certain compression ratio on the high compression ratio side and the pressure applied to the sliding control body 34 from the non-control pressure chamber side are balanced. By setting the pressure receiving area of the sliding control body 34, the balance Pc at the maximum capacity becomes equal to the discharge pressure at that time at almost all compression ratios. Therefore, a stopper that regulates the position of the slide control body 34 is not needed.

Further, as shown in FIGS. 4 (a) to 4 (f), the balance Pc has a monotonically increasing relationship with the increase in the capacity ratio at each compression ratio, and the control pressure by the correction spring in the maximum capacity side region is large. Is not raised, the insensitive region to the change in the control pressure is eliminated, and the movement of the sliding control body 34, that is, the change in the capacity is performed with good followability in response to the change in the control pressure.

The present invention is not limited to the above embodiment,
For example, when the compressor is started from a state where the swash plate tilt angle is at the minimum side, the return spring 37 for eliminating the inconvenience that the swash plate 11 does not easily move to the maximum tilt side is provided with the control pressure chamber.
You may interpose in 23a. Since this spring does not raise the control pressure on the maximum capacity side, the capacity can be smoothly changed from the maximum capacity to the small capacity side as in the above embodiment.

[Effects of the Invention] As described in detail above, according to the present invention, the pressure in the control pressure chamber applied to the slide control body at the maximum capacity and the pressure applied to the slide control body from the side opposite to the control pressure chamber are balanced. Since the pressure receiving area of the sliding control body is set, the stopper for regulating the position of the sliding control body is not required so that the swash plate tilt angle at the maximum capacity becomes a predetermined value, and the stroke and Since there is no need to adjust the top clearance, the time and labor required for assembly are greatly reduced. In addition, since the sliding control body is held at a predetermined position only by the pressure balance at the maximum capacity, if the control pressure is changed to change the capacity, the sliding control body will follow the change of the control pressure and smoothly. It has an excellent effect that the insensitive area to the control pressure is eliminated and the controllability is improved.

[Brief description of drawings]

1 to 4 show an embodiment embodying the present invention, in which FIG. 1 is a longitudinal sectional view of a compressor, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. The figure is a diagram for explaining the guide hole and the guide curve, and FIGS. 4A to 4F are diagrams showing the relationship between the balance Pc (required control pressure) and the capacity ratio when the compression ratio is changed, FIG. 5 is a partial sectional view of a modified example. Cylinder block 1, rotating shaft 4, guide holes 6a, 7a, swash plate 1
1, guide pin 12, double-headed piston 15, control pressure chamber 23a, sliding control body 34, guide curve S.

Claims (1)

[Claims] 1. A cylinder block rotatably accommodating and supporting a double-headed piston, wherein a swash plate for reciprocally driving the double-headed piston is relatively non-rotatable on the rotary shaft and its peripheral side. Is supported so as to be able to swing back and forth around the center, and the swing center position is set near the rear 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. However, in the swash plate type compressor in which the top dead center of the compression stroke in the rear side cylinder bore is a fixed position, a control pressure chamber for capacity control that is switched to a pressure equivalent to the discharge pressure or the suction pressure is provided, and the control pressure chamber A sliding control body that changes the volume is supported on the rotating shaft so as to be slidable in the axial direction thereof, and suction pressure acts on the surface of the anti-control pressure chamber of the sliding control body. The swash plate swinging force generated and the pressure in the control pressure chamber are opposed via the swash plate and the sliding control body, and a guide pin is attached to the side of the swash plate which is swung by this opposition, and the above-mentioned on the rotating shaft side. A guide hole having a guide relationship with the guide pin is provided, and a guide curve for increasing the inclination angle of the swash plate is used as a guide curve that defines the shape of the guide hole on the large-capacity side with the displacement position of the guide pin in the axial direction of the rotating shaft as a variable Adopts a curve that increases monotonously with the displacement of the pin and is convex downward, and the pressure in the control pressure chamber applied to the sliding control body at the maximum capacity at the maximum compression ratio generated in the refrigerant circuit and the anti-control of the sliding control body A variable displacement swash plate compressor in which the pressure receiving area of the sliding control unit is set so as to balance with the pressure applied from the pressure chamber side.