JPH06317251A - Variable delivery type compressor - Google Patents

Abstract

PURPOSE:To increase a pressure gradient between a crank chamber and a suction chamber when delivery is restored, and rapidly reduce pressure in the crank chamber by opening an air extraction passage to communicate the crank chamber with the suction chamber in an area most separated from a suction hole opening part in the suction chamber. CONSTITUTION:When a driving shaft 7 is rotated, since a swinging plate 13 swings longitudinally through a rotary swash plate 11 and a piston 16 makes reciprocating motion in a bore 15, refrigerant gas sucked in the bore 15 from a suction chamber 3a is compressed, and is delivered to a delivery chamber 3b. A stroke of the piston 16 and an inclination of a swinging plate 11 change according to differential pressure between a crank chamber 5 and a suction chamber 3a, and delivery quantity is controlled. By the way, an air extraction passage is communicated with the suction chamber 3a by passing penetratingly through a valve plate 4 and the like from the crank chamber 5. In this case, the extraction passage is opened in an area most separated from a suction hole opening part in the suction chamber 3a. Thereby, a pressure gradient between the crank chamber 5 and the suction chamber 3a is increased when delivery is restored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor suitable for air conditioning of a vehicle, and more particularly to a compressor provided with a suction chamber, a discharge chamber and a crank chamber for adjusting the differential pressure between the suction chamber pressure and the crank chamber pressure. The present invention relates to a variable displacement compressor in which the discharge capacity is controlled by changing the tilt angle (piston stroke) of the rotary swash plate.

[0002]

2. Description of the Related Art Conventionally, as a variable capacity type compressor of this type, one having a structure disclosed in, for example, JP-A-62-203980 is known. This compressor is provided with an air supply passage that connects the discharge chamber and the crank chamber, an opening / closing control valve that opens and closes the air supply passage, and an extraction passage that constantly connects the suction chamber and the crank chamber. When the suction chamber pressure falls below the set value, the on-off control valve that responds to that pressure opens the air supply passage, and when the suction chamber pressure rises above the set value, the on-off control valve feeds. It is designed to close the air passage.

Therefore, during full-capacity operation of the compressor in which the opening / closing control valve closes the air supply passage, the refrigerant gas blow-by from the compression chamber to the crank chamber is constantly recirculated to the suction chamber through the bleed passage and the pressure in the crank chamber increases. The differential pressure from the suction chamber pressure is kept at a very small value, and the rotary swash plate is kept at the maximum tilt angle. Then, when the suction chamber pressure falls below the set value as the heat load decreases, the opening / closing control valve is opened and high-pressure refrigerant gas is supplied from the discharge chamber to the crank chamber to raise the crank chamber pressure. That is, the differential pressure between the crank chamber pressure and the suction chamber pressure increases, and the tilt angle of the rotating swash plate is gradually reduced, so that the discharge capacity of the compressor is reduced. After that, when the low load operation continues, the heat load starts to rise again, and when the suction chamber pressure exceeds the set value and the on-off control valve is closed, the crank gas is returned by the refrigerant gas passing through the extraction passage. The chamber pressure is reduced, that is, the inclination of the rotating swash plate is restored.

[0004]

As described above, in order to sensitively restore the capacity of the compressor in response to heat load, it is necessary to quickly reduce the crank chamber pressure. However, in general, the shape of the suction chamber is often complicated due to design restrictions, and the pressure due to the gas flow is different between the position near the suction hole that opens in the suction chamber and the position most distant from the opening. The loss causes an unexpectedly large pressure difference, and for example, 3.000 r.p.m. p. At a rotational speed of m, the value reaches 0.5 to ¹ kg / cm ² . For this reason, depending on the opening position of the bleed passage communicating with the suction chamber, a considerable disparity may occur in the rate of decrease of the crank chamber pressure, that is, the capacity return rate of the compressor.

Of course, from a point of view of simply promoting gas flow from the crank chamber to the suction chamber, it should be sufficient to set the cross-sectional area of the extraction passage to a large value, but it is sufficient for the above-mentioned low capacity operation. In the case of adopting the control system that positively supplies the discharged refrigerant gas to the crank chamber as in the transition, the supply gas amount increases in proportion to the cross-sectional area of the extraction passage, resulting in power loss. Inevitable problems such as inviting

A problem to be solved by the present invention is to surely improve the responsiveness of the capacity control to the heat load.

[0007]

In order to solve the above problems, the present invention provides a cylinder block having a plurality of bores arranged side by side, a front housing which forms a crank chamber and closes one end of the cylinder block, a suction hole, and A rear housing having an intake chamber and a discharge chamber respectively connected to the discharge holes and closing the other end of the cylinder block via a valve plate, a drive shaft extending into the crank chamber, and a drive shaft extending in the crank chamber. A rotary swash plate that rotates together with the drive shaft and is capable of tilt displacement, a piston that is linked to the rotary swash plate, and that linearly moves in each bore based on the rotational swing thereof, the crank chamber, and the suction chamber. In a variable displacement compressor equipped with a control valve that adjusts the differential pressure between the two chambers via a communicating bleed passage and changes the discharge capacity along with the tilt displacement of the rotary swash plate, the bleed passage is in the suction chamber. It employs a novel configuration that is open to the farthest region from the entry apertures opening.

As a preferred embodiment of the present invention, the control valve is arranged in an air supply passage connecting the discharge chamber and the crank chamber to control positive air supply to the crank chamber.
The present invention can be applied even if it is arranged in the bleed passage to control the bleed air from the crank chamber.

[0009]

[Operation] The bleed passage that connects the crank chamber and the suction chamber is
Since the opening is made in the region farthest from the opening of the suction hole in the suction chamber (the region where the pressure drop is large), the pressure gradient between the crank chamber and the suction chamber at the time of capacity restoration becomes large, and the crank chamber pressure can be increased. It can be lowered promptly. In addition, at the time of shifting to a low capacity, the differential pressure due to the pressure loss naturally decreases as the gas flow rate in the suction chamber decreases due to the decrease in capacity, so that substantially harmful power loss due to the specification of the opening does not occur.

[0010]

Embodiments of the present invention will be specifically described below with reference to FIGS. 1 and 2. In the figure, a front housing 2 is coupled to a front end of a cylinder block 1 which constitutes a part of an outer shell of a compressor, and a rear housing 3 having a suction chamber 5 and a discharge chamber 6 is formed at a rear end of the cylinder block 1 and a valve plate 4. Are connected through. A drive shaft 8 connected to a power source is inserted into a crank chamber 7 formed in the front housing 2, and the drive shaft 8 is rotatably supported by the cylinder block 1 and the front housing 2. A rotation support 9 is fixed to the drive shaft 8 in the crank chamber 7, and a long hole 10a is formed at the tip of a support arm 10 extending to the rear surface side of the rotation support 9. A pin 11 is slidably fitted in the elongated hole 10a.
A rotary swash plate 12 is tiltably connected to the shaft 1.

A sleeve 13 is loosely fitted on the drive shaft 8 adjacent to the rear end of the rotary support 9, and is constantly biased toward the rotary support 9 by a coil spring 14, and at the same time, the sleeve 13 is provided.
Pivot shafts 13a (only one of which is shown) projecting from the left and right sides of the rotary swash plate 12 are fitted into engaging holes (not shown) of the rotary swash plate 12, and the rotary swash plate 12 is supported so as to swing around the pivot shaft 13a. ing.

A swing plate 15 is supported on the rear surface side of the rotary swash plate 12 so as to be relatively rotatable, and a guide portion 15 provided at an outer edge portion.
Rotation is restrained by engaging a with the through bolt 16 and the bore 1 penetrating the cylinder block 1 is provided.
The piston 18 and the oscillating plate 15 inside the connecting rod 19
Has been articulated by. Therefore, the rotary motion of the drive shaft 8 is converted into the back-and-forth swing of the swing plate 15 via the rotary swash plate 12, and the piston 18 reciprocates in the bore 17 to be sucked from the suction chamber 5 into the bore 17. The refrigerant gas is discharged into the discharge chamber 6 while being compressed. Then, the stroke of the piston 18 and the tilt angle of the oscillating plate 15 change according to the pressure difference between the crank chamber pressure and the suction chamber pressure, and the discharge capacity is controlled. The crank chamber pressure is controlled by the on-off control valve 2 described below.
0 controls on the basis of the cooling load.

That is, the opening / closing control valve 20 provided in the rear housing 3 is provided with a suction pressure chamber 21 and a discharge pressure chamber 22 facing each other, and the suction pressure chamber 21 is connected to the suction chamber 5 via a through hole 23. The discharge pressure chamber 22 is communicated with the discharge chamber 6 through the through hole 24. And suction pressure chamber 2
1 is provided with a bellows 26 which is expandable and contractable so as to surround an atmospheric pressure chamber 25 arranged at the center.
Always extends through spring 27 (direction of discharge pressure chamber 22)
Is urged by. On the other hand, the discharge pressure chamber 22 has a suction pressure chamber 2
A valve hole 28 is provided at one end closer to the port 1, and a port 29 that is continuous with the valve hole 28 is connected to the crank chamber 7 via an air supply passage 30. In addition, the bellows 2
A base end of a valve rod 31 is connected to 6 and extends in the direction of the discharge pressure chamber 22. The tip of the valve rod 31 penetrates through the port 29 and the valve hole 28 and faces the discharge pressure chamber 22. A valve body 32 is attached to the tip of the valve rod 31 so as to face the valve hole 28. The valve body 32 is configured to be opened and closed through expansion and contraction of the bellows 26, and to the discharge pressure chamber 22. The inserted spring 33 always keeps the valve hole 28 (closed direction).
Is urged by. Therefore, when the suction chamber pressure introduced into the suction pressure chamber 21 falls below the set value, the bellows 2
6, the valve rod 31 advances to open the valve element 32, and the discharged refrigerant gas is supplied from the valve hole 28 to the crank chamber 7 via the port 29 and the air supply passage 30.

Next, the extraction passage 40, which is a characteristic component of the present invention, will be described. The extraction passage 40 communicates with the suction chamber 5 from the crank chamber 7 through the cylinder block 1 and the valve plate 4, and the flow rate thereof is set to a predetermined value by the fixed throttle 41. As shown in FIG. 2, the suction chamber 5
Is defined so as to surround the discharge chamber 6 formed including the axial center portion, and the suction chamber 5 is connected to the evaporator through the suction hole 5a and a pipe (not shown) connected to the suction hole 5a. On the other hand, the discharge chamber 6 is also connected to the condenser via a similar pipe connected to the discharge hole 6a.

As is clear from the figure, the suction chamber 5 is strongly complicated due to various design restrictions such as the required space of the discharge chamber 6, the connecting hole of the through bolt 16 and the setting position of the connecting flange. As a result, for example, a large pressure difference occurs due to the pressure loss between the refrigerant gas flowing through the suction port 5b near the opening of the suction hole 5a and the refrigerant gas flowing through the suction port 5b 'that is farthest from the opening. ing. The bleed passage 40 that connects the crank chamber 7 and the suction chamber 5 to each other is opened in a region farthest from the opening of the suction hole 5a, that is, in a region where the pressure is the lowest in the suction chamber 5.
a).

Therefore, when the heat load starts to increase due to the continued low capacity operation of the compressor and the opening / closing control valve 20 is closed as the suction chamber pressure exceeds the set value, the bleed passage 4
Although the crank chamber pressure is reduced by the circulation of the refrigerant gas to the suction chamber 5 via 0, the extraction passage 40 is
Since the opening 40a is formed in the region (the lowest pressure region) farthest from the opening of the suction hole 5a, the pressure gradient between the crank chamber 7 and the suction chamber 5 becomes large, and the crank chamber pressure is as fast as possible. The capacity is lowered to provide a quick capacity recovery in response to the heat load.

Further, when the compressor is shifted to a low capacity operation, the suction chamber pressure is decreased by opening the on-off control valve 20, the crank chamber pressure is increased, the capacity is decreased, and the gas flow rate in the suction chamber 5 is decreased. Since the pressure loss is reduced by this, the relative pressure of the region occupied by the opening 40a of the bleed passage 40 to the other region increases, and irrational power consumption such as supplementing the excess bleed with excess air does not occur.

In the above embodiment, the capacity control by adjusting the differential pressure between the crank chamber pressure and the suction chamber pressure is performed by disposing a control valve in the air supply passage connecting the discharge chamber and the crank chamber. Although the compressor of the system that combines the positive air supply control to the crank chamber by the valve and the quantitative extraction from the crank chamber through the extraction passage has been described, the present invention is not necessarily limited to such a control system. Not something.

That is, as a means for increasing the crank chamber pressure, only blow-by gas that leaks into the crank chamber is used, or a fixed throttle passage that connects the discharge chamber and the crank chamber is provided to perform supplementary air supply. On the other hand, on the other hand, a control valve for adjusting the extraction flow rate is provided in the cylinder block or the rear housing in which the extraction passage is formed, and a control system that combines these constant amount air supply and variable air extraction control Needless to say, the present invention can be applied to a control type compressor including a valve mechanism that controls both air and bleed air.

[0020]

As described above in detail, according to the present invention, the bleed passage that connects the crank chamber and the suction chamber is opened in the region that is farthest from the suction hole opening in the suction chamber. By effectively utilizing the pressure loss that occurs in the room, the pressure gradient between the crank chamber and the suction chamber at the time of capacity restoration can be increased, and the crank chamber pressure can be quickly reduced. Since the pressure loss is automatically reduced as the flow rate decreases, the crank chamber pressure can be smoothly increased without wasting power.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the entire structure of a compressor according to an embodiment of the present invention.

FIG. 2 is a sectional side view showing the relationship between the suction chamber and the extraction passage.

[Explanation of symbols]

1 is a cylinder block, 3 is a rear housing, 5 is a suction chamber, 5a is a suction hole, 6 is a discharge chamber, 7 is a crank chamber, 8 is a drive shaft, 12 is a rotary swash plate, 20 is an opening / closing control valve, and 30 is a supply valve. Air passage, 40 is extraction passage, 40a is opening

Front Page Continuation (72) Inventor Shigeyuki Hidaka 2-1-1 Toyota-cho, Kariya City, Aichi Prefecture Toyota Industries Corporation

Claims (3)

[Claims] 1. A cylinder block having a plurality of bores arranged in parallel, a front housing forming a crank chamber to close one end of the cylinder block, and a suction chamber and a discharge chamber respectively connected to the suction hole and the discharge hole. A rear housing that closes the other end of the cylinder block via a valve plate, a drive shaft that extends into the crank chamber, and a rotary tilt that rotates together with the drive shaft in the crank chamber and that is capable of tilt displacement. A plate, a piston that is linked to the rotary swash plate, and that directly moves in each bore based on its rotational oscillation, and a differential pressure between the two chambers via a bleed passage that connects the crank chamber and the suction chamber. In a variable displacement compressor equipped with a control valve that adjusts and changes the displacement of the rotary swash plate with the tilt displacement of the rotary swash plate, the bleed passage is opened in a region farthest from the suction hole opening in the suction chamber. A variable capacity compressor characterized in that 2. The variable displacement type according to claim 1, wherein the control valve is arranged in an air supply passage connecting the discharge chamber and the crank chamber to control positive air supply to the crank chamber. Compressor. 3. The variable displacement compressor according to claim 1, wherein the control valve is arranged in the bleed passage to control bleed air from the crank chamber.