JPS6368777A - Swash plate type compressor - Google Patents

Abstract

PURPOSE:To make the discharge of a refrigerant simply restrainable, by installing a slider, being pressed to a swach plate by dint of a spring, in a piston, and making a stroke of the piston smaller at a time when a pressure differential acting on both ends of the piston is large enough. CONSTITUTION:A control chamber 30 is formed in a piston 10, and this control chamber 30hr a peripheral part of a swash plate 8. And, at each side of both surfaces of the control chamber 30, there are provided with a pair of springs 31 and also a pair of slides 32 being pressed by these springs. And, each semispherical shoe 11 is slidably housed in these sliders 32, and each semispherical shoe 11 is made contact with both surfaces of the swash plate 8 free of slide motion. With this contact, both sides of the swash plate 8 are pinched by pressing force of each spring 31 via each semispherical shoe 11. Therefore, if revolution of a compressor becomes higher, balance in each spring 31 comes down, whereby the piston 10 fails to keep its full stroke, thus the stroke becomes smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a swash plate compressor for a refrigeration cycle.

[Conventional technology]

A swash plate type compressor is known as a compressor for a car air conditioner, and the conventional swash plate type compressor will be explained based on FIG. 4.

1 and 2 are aluminum cylinder bodies divided into two in the axial direction, 3 is an aluminum front housing, and 4 is an aluminum rear housing, respectively. These front housing 3, cylinder bodies 1 and 2, and rear housing 4 are integrally connected by bolts 5 passed through in the axial direction.

A drive shaft 6 is inserted through the center of the front housing 3, cylinder body 1.2, and rear housing 4, and the drive shaft 6 is rotatably supported by a bearing 7.7. The drive shaft B is rotated by the engine, and an aluminum swash plate 8 is attached to the drive shaft B so as to rotate together with the drive shaft B.

A plurality of cylinder bores 9 are formed around the drive shaft B between the two divided cylinder bodies 1 and 2. These cylinder bores 9 are formed parallel to the drive shaft 6, and a piston 10 is slidably accommodated in each cylinder bore 9.

Teflon is used on the circumferential surface of piston 1o...

Coating has been applied.

The peripheral portion of the swash plate 8 is slidably inserted into the intermediate portion of the piston 10, so that the piston lO...
・ straddles the periphery of the swash plate 8.

A pair of hemispherical shoes 11.11 made of bearing steel (SUJ) are accommodated in the piston 10, and these hemispherical shoes 11,
11 is in sliding contact with both sides of the swash plate 8.

Therefore, when the swash plate 8 rotates, the pistons 1G are reciprocated in the axial direction within the cylinder bores 9 according to the inclination angle of the swash plate 8.

The front housing 3 and the rear housing 4 have low-pressure suction passages 12, 13, and high-pressure discharge passages 14 facing the cylinder bores 9, respectively.
. , 15 . . . are formed. Aluminum valve seats 16 and 17 and gaskets 18 and 19 that also serve as retainers are sandwiched between the front housing 3 and one cylinder body 1, and between the other cylinder body 2 and rear housing 4, respectively. and
These valve seats 18, 17 and a gasket lit which also serves as a retainer, 19 are each of the above cylinder bores 9...
The inside of the suction passages 12..., 13... and the high-pressure discharge passages 14..., 15... are partitioned.

The valve seat 18.17 has a suction valve 20 and a discharge valve 2.
1 is provided.

In the figure, 22 is a thrust bearing, 23... is an O-ring as a sealing member, and 24 is a shaft sealing mechanism.

In the compressor having such a configuration, when the swash plate 8 rotates due to the rotation of the drive shaft 6, the piston lO... is reciprocated in the axial direction within the cylinder bore 9... according to the inclination angle of the swash plate 8. .

When the piston lO... moves in one direction within the cylinder bore 9..., the refrigerant is compressed within the bore 9a in the direction of movement, so the refrigerant within the bore 9a is force-fed to the discharge passage 14 through the discharge valve 21. At this time, refrigerant is sucked into the bore 9b on the opposite side from the suction passage 13 via the suction valve 20.

When the pistons 10... move to the other side, the refrigerant in the bore 9b in the direction of movement is compressed and is forced into the discharge passage 15 through the discharge valve 21. Refrigerant is sucked in through the suction valve 2o.

Therefore, as the swash plate 8 rotates, the piston IO.
... are reciprocated, thereby alternately sucking in and discharging refrigerant, creating a so-called pumping action.

[Problem that the invention seeks to solve]

In the conventional swash plate compressor described above, the piston 10 is always fully stroked regardless of the rotational speed, so it exhibits characteristics as shown by the solid line in FIG. 4. That is, as the compressor rotation speed increases, the high pressure increases and the low pressure decreases. The low-pressure side is connected to suck refrigerant from the evaporator through the suction passage 12 or 13, so when this low-pressure pressure drops below approximately 2 Kl/d, the surface temperature of the evaporator drops below 0°C. become. Therefore, the dehumidified water in the evaporator solidifies and frosts).
There is a problem in that the airflow passing through the evaporator is obstructed, resulting in a significant decrease in cooling capacity.

To avoid this, measures have been adopted such as using a thermistor to detect the temperature of the air passing through the evaporator and stopping the compressor when the air temperature falls below a predetermined value, but this method requires large-scale equipment. There are disadvantages such as increased cost.

Furthermore, the control of starting and stopping using a thermistor has a problem in that a shock is generated each time the device is started and stopped.

The present invention aims to provide a swash plate compressor that can prevent an excessive drop in low pressure by itself and prevent dehumidified water from coagulating in an evaporator without installing any special external equipment. It is something to do.

[Means for solving problems]

The present invention provides a slider inside the piston that is pressed against the swash plate by a spring, and when the difference between high and low pressures acting on both end surfaces of the piston is large, the stroke of the piston is reduced by compression of the spring. Features.

(Function) According to the present invention, when the compressor rotation speed increases and the high pressure increases and the low pressure decreases, resulting in an increase in the pressure difference between the high and low pressures, the spring provided in the piston expands and contracts, causing the piston to move. As a result, the piston is unable to maintain a full stroke and the stroke becomes smaller.This suppresses the discharge amount, prevents high pressure rises and low pressure drops, and keeps the surface temperature of the evaporator below 0℃. prevent

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in FIGS. 1 to 3.

In this embodiment, the same members as those in the conventional system shown in FIG. 4 are designated by the same numbers and their explanations will be omitted.

A control chamber 30 is formed in the piston lO according to this embodiment, and a peripheral portion of the swash plate 8 is accommodated in this control chamber 30. The control chamber 30 includes a pair of springs 81, 31 located on both sides of the swash plate 8, and these springs 3.
A slider 32.32, pressed at 1.31, is accommodated. The slider 12.32 is made of, for example, aluminum and has a cylindrical shape, and the slider 12.32 is made of aluminum and has a cylindrical shape.
It is slidable in the stroke direction of O....

The slider 32.32 slidably encloses hemispherical shoes 11.11, which abut slidably on both sides of the swash plate 8. Therefore, these hemispherical shoes 11.11 are connected to the springs 31, 31
Both sides of the swash plate 8 are held in place by the pressing force of the swash plate 8.

Other configurations may be the same as the conventional one shown in FIG.

The operation of the embodiment with such a configuration will be explained.

When the drive shaft 6 is rotated by the engine, this drive shaft B
The swash plate 8 fixed to also rotates integrally. The rotation of the swash plate 8 causes the pistons 1o to reciprocate in the axial direction within the cylinder bores 9.

When the piston 1o moves in one direction in the cylinder bore 9, it compresses the refrigerant in the bore in the direction of movement, so the refrigerant in the bore is transferred to the discharge passage 1 through the discharge valve 21.
4... or 15..., and in the bore on the opposite side, the suction passage 12... or 13 is passed through the suction valve 20.
Refrigerant is sucked from... And piston lO...
When * moves to the other side, the refrigerant in the bore in the direction of movement is compressed and sent to the discharge passage 14... or 15..., and the suction passage 12... or 13 is in the bore on the opposite side. Refrigerant is sucked from...

In this way, as the swash plate 8 rotates, the piston 10 and
The reciprocating action of reciprocating the refrigerant from the suction passage 12 or 13 through the suction and compression action within the cylinder bore lO, compressing it, and sending it out to the discharge passage 14 or I5 is the same as before. It is.

By the way, when the compressor rotation speed is low, the compressed refrigerant pressure on the high pressure side and the suction refrigerant pressure on the low pressure side.

The difference is relatively small. Therefore, both springs 31
．． 31 remains balanced, the sliders 32, 82 remain stationary, and the pistons 10... make a full stroke as shown in FIG.

As the compressor rotation speed increases, the difference between the compressed refrigerant pressure on the high-pressure side and the suction refrigerant pressure on the low-pressure side increases, and the pressure difference acting on both end surfaces of the piston IO increases. For this reason, the balance between the pressing forces of both springs 31 and 31 is disrupted.

That is, the spring 31 provided on the end face side to which the high-pressure side pressure is applied contracts, and the spring 31 on the opposite side expands, so that the piston 10 no longer operates at its full stroke. That is, as the compressor rotation speed increases, the stroke of the piston IO becomes smaller, as shown in FIG.

As a result, the volumetric efficiency changes and the amount of refrigerant discharged per stroke decreases. Therefore, as shown by the broken line in FIG. 5, the pressure difference between the high pressure side refrigerant pressure and the low pressure side refrigerant pressure is reduced,
The low pressure at the evaporator outlet is maintained at about 2 Kg/d or higher to prevent the dehumidified water in the evaporator from frosting. Therefore, a significant decrease in cooling capacity is prevented.

Note that the amount of change in stroke changes by selecting and adjusting various strengths of the springs 31, 31, and the relationship between the amount of stroke change and volumetric efficiency is shown in FIG. Entry point ηV in the diagram
It was found that in order to reduce the amount of refrigerant discharged from the compressor by about half from -0.75 to point B ηV -0.38, it is sufficient to change the piston stroke by about 0.4 m + 1. This has the advantage that the amount of refrigerant discharged can be greatly changed with a certain amount of stroke change.

In the above embodiment, a coil spring is used as the spring, but since the amount of refrigerant discharged can be increased (changed) with a small stroke change, it is possible to use a disc spring or leaf spring with a small displacement. It is also possible to implement using

〔Effect of the invention〕

As explained above, according to the present invention, when the compressor rotation speed increases, even if the high pressure increases and the low pressure decreases, resulting in an increase in the pressure difference between the high and low pressures, the spring provided in the piston expands and contracts. The piston attempts to keep the piston in pressure balance, so the piston is no longer able to maintain a full stroke and its stroke becomes smaller. Therefore, the discharge amount is suppressed, and it is possible to prevent an excessive drop in the low pressure and to prevent the dehumidified water from solidifying in the evaporator. Moreover, this type has a simple structure because the discharge amount is automatically controlled by the compressor itself without providing any special external equipment.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, where Figure 1 is a sectional view in a low rotational speed state, Figure 2 is a sectional view in a high rotational speed state, and Figure 3 is a stroke change amount and volume. FIG. 4 is a sectional view showing a conventional structure, and FIG. 5 is a characteristic diagram showing the relationship between compressor rotation speed and high pressure and low pressure. 1.2... Cylinder body, 3... Front housing, 4... Rear housing, 6... Drive shaft 6.8
... Swash plate, 9... Cylinder bore, IO... Piston, 11... Hemispherical shoe, 12.13... Suction passage, 14.15... Discharge passage, 20... Suction valve, 21
...Discharge valve, 30...Control room, 31.81...Spring, 32.32...Slider. Applicant's agent Patent attorney Takehiko Suzue 3rd WJ 5gJ

Claims (1)

[Claims] A swash plate is fixed to the drive shaft, a plurality of pistons are engaged around the swash plate, spanning the swash plate, and as the swash plate rotates, the pistons reciprocate within a cylinder bore parallel to the drive shaft. In the swash plate type compressor, a slider is provided in the piston and is pressed against the swash plate by a spring, and when the difference in high and low pressures acting on both end surfaces of the piston is large, the stroke of the piston is reduced by compression of the spring. A swash plate type compressor characterized by having a small size.