JPH0517433Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to a variable capacity compressor that adjusts the amount of refrigerant discharged according to the pressure state of the return refrigerant. This invention relates to improvement of a protection device when a variable capacity compressor experiences abnormally high pressure.

(Prior Art) Recently, among the compressors used in automobile air conditioners, there is a variable capacity swash plate type compressor that adjusts the amount of refrigerant discharged (for example, Japanese Patent Application Laid-Open No. 158-382 Or Utsukai 61-
(See Publication No. 145,885).

As shown in FIG. 2, the variable capacity swash plate type compressor 3 uses the internal volume of the compression chamber in the cylinder 25 as the suction pressure of the refrigerant returned to the compressor 3.
The amount of refrigerant discharged from the compressor 3 is adjusted by changing it according to Ps, and the suction pressure of this compressor 3 is
Ps is controlled to a predetermined set value.

By controlling the suction pressure Ps in this way, the refrigerant pressure at the outlet of the evaporator (that is, the evaporation pressure of the refrigerant in the evaporator) can be controlled to a certain extent, thereby making it possible to avoid freezing of the evaporator at low loads. become.

The variable displacement swash plate type compressor 3 has a drive shaft 11 in a closed casing 17, which is rotationally driven by the engine via a belt, a pulley 2, and a magnetic clutch 2a. This drive shaft 11
A drive rod 11a is provided to protrude in a direction perpendicular to the drive shaft 11, and is adapted to rotate together with the drive shaft 11 within the crank chamber 12.

A drive swash plate 13 is connected to the drive rod 11a via a link (not shown) so that it can tilt and swing with respect to the drive shaft 11 with the pin 11b as a fulcrum, and the rotational force of the drive shaft 11 is connected to the drive rod 11a. The power is transmitted to the drive swash plate 13 via the drive rod 11a, pin 11b, etc. A non-rotating wobble plate 16 is slidably attached to the drive swash plate 13 via a thrust bearing 14 and a radial bearing 15.

The wobble plate 16 has a shoe 19 slidably connected to a guide pin 18 fixed to a closed casing 17 in which a crank chamber 12 is formed, and is prevented from rotating by this shoe 19. On the other hand, reciprocating motion in the axial direction is permitted.

Five piston rods 22 are attached to this wobble plate 16 via spherical bearings 22a at equal intervals in the circumferential direction, and a piston is attached to the other end of the piston rod 22 via a spherical bearing 22a as shown in FIG. 23 are connected.

As the driving swash plate 13 rotates, the wobble plate 16 performs a so-called wobbling motion and reciprocates in the axial direction, thereby causing the piston 23 to reciprocate linearly via the piston rod 22. Cylinder 2 into which this piston 23 is inserted
The front side portion of the piston 23 of No. 5 has a compression chamber (second
In the figure, the piston 20 is located at the frontmost end, so it is not shown), and the rear side portion communicates with the crank chamber 12.

The cylinder head 30 is provided with a suction port 29 and a discharge port 33, into which the return refrigerant from the evaporator flows, and this refrigerant flows into the suction port 29 formed in the valve plate 20.
The air flows into the cylinder bore 26 against the closing elastic force of the suction valve 34 that closes the air intake valve 7 .

Further, this refrigerant is passed through a communication passage 32a that communicates with the suction port 29 formed in the cylinder head 30.
It is designed to be guided to the suction side pressure chamber 32 via.

On the other hand, the discharge port 33 is a part from which compressed refrigerant is discharged, and the discharge port 33 is a part from which compressed refrigerant is discharged.
It communicates with a pipe (none of which is shown) that sends the refrigerant discharged from a discharge port 28 opened to the condenser, and further communicates with the discharge side pressure chamber 35 via a communication passage 35a.

A control valve as shown in FIG. 2 is provided between the suction side pressure chamber 32 and the discharge side pressure chamber 35.
Cv is provided, and this control valve Cv has a first control valve 36 at the bottom and a second control valve 39 at the top. A bellows 37 that expands and contracts accordingly, and a spring 3 provided within this bellows 37.
The opening degree of the first valve port 40 is adjusted by balancing the force with the first valve port 8, and the refrigerant in the suction side pressure chamber 32 is
0, the passage 41, the through hole 42, the passage 43, the center hole 44 of the cylinder 25, and the center passage 45 of the drive shaft 11.
It is designed to lead to the crank chamber 12 through.

Further, the first control valve 36 is provided with an actuation rod 46, and this actuation rod 46 causes the second control valve 3
9 is now open. Both control valves 36 and 39 operate in conjunction with each other, and when the first control valve 36 increases the opening degree of the first valve port 40 as described above, the second control valve 36 and 39 operate in conjunction with each other. 39 is designed to reduce the opening degree of the second valve port 47.

Therefore, when the heat load in the cooling cycle is small, the pressure of the return refrigerant returns at a low pressure, so the pressure in the suction side pressure chamber 32 (the suction pressure described above)
Ps) becomes lower, and the bellows 37 extends upward.
As a result, the first control valve 36 closes the first valve port 40, and the valve operating rod 46 moves upward to close the second control valve 36.
This will push up 9. Therefore, the second valve port 47 opens wide, and a part of the high-pressure refrigerant (hereinafter referred to as discharge pressure Pd) compressed by the piston 23 in the compression process is transferred from the discharge port 28 to the second valve port 4.
7 into the crank chamber 12 through passages 48 and 49, thereby increasing the internal pressure of the crank chamber 12 (hereinafter referred to as compressor internal pressure Pc).

Here, the inclination angle of the wobble plate 16 is controlled by the balance of pressures applied to the plurality of pistons 23 before and after, and when the pressure Pc in the crank chamber 12 becomes larger than the suction pressure Ps, the inclination angle of the plurality of pistons 23 increases. The combined force of the forces applied to the back surface acts on the wobble plate 16 as a moment about the pin 11b, and acts to reduce the inclination angle of the wobble plate 16.

For this reason, the high discharge pressure Pd is
2, the pressure balance acting on the front and rear surfaces of each piston 23 changes, and the pin 11b
The moment acting on the piston on the compression side and the piston on the suction side about Only a small compression stroke can be made.

As a result, the amount of compressed refrigerant is reduced, the amount of refrigerant discharged is also reduced, and the flow rate of refrigerant circulating within the cooling cycle is reduced, resulting in an appropriate amount of refrigerant corresponding to the low heat load. Due to this decrease in the amount of refrigerant, compressor 3
The suction pressure Ps gradually increases, and as a result, the suction pressure Ps is kept constant.

Furthermore, when the heat load in the cooling cycle is large, the suction pressure Ps increases, the bellows 37 contracts, the first control valve 36 moves downward, the opening degree of the first valve port 40 increases, and the first control valve 36 moves downward. Since the opening degree of the second valve port 47 becomes smaller, the high discharge pressure is transferred to the crank chamber 1.
2, the internal pressure of the crank chamber 12 is transferred from the center passage 45 → center hole 44 → passage 43 → through hole 42 →
By flowing down through the through hole 41 → first valve port 40 → suction side pressure chamber 32, the compressor internal pressure Pc
becomes almost equal to the suction pressure Ps.

Therefore, the wobble plate 16 and the drive swash plate 13 are tilted to the maximum with respect to the drive shaft 11 due to the action of the above-mentioned moment, so that the reciprocating stroke of the piston 23 becomes longer.

Therefore, if compression is performed in this state, the discharged refrigerant amount will increase, the refrigerant flow rate circulating within the cooling cycle will increase, and the refrigerant flow rate will be appropriate according to the high heat load, and the suction pressure Ps of the compressor 3 will increase. As a result, the suction pressure Ps is controlled to gradually decrease to a predetermined suction pressure Ps.

(Problem to be solved by the invention) However, in the conventional variable capacity swash plate type compressor mentioned above, when the discharge pressure becomes abnormally high, a large amount of force is applied inside the compressor, which significantly reduces the durability of the internal parts. Problems such as a sudden drop in performance may occur. For this reason, in order to ensure the safety of each member and device of the cooling circuit, a safety valve that releases this high pressure to the atmosphere and a pressure switch that senses this pressure and disconnects the compressor clutch are provided.

However, in the case of a safety valve that opens to the atmosphere like this, once it is activated, most of the refrigerant will be released into the atmosphere, so if you want to restart the cooling operation, you must replace the safety valve and The disadvantage is that the refrigerant must be charged, which is not only uneconomical but also requires troublesome work.

The present invention was developed to solve the above-mentioned drawbacks and problems of the conventional technology, and even if the discharge pressure becomes abnormally high, the refrigerant is not released to the atmosphere, but is released into the crank chamber, and this refrigerant is recycled. The purpose is to make it accessible.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention forms a crank chamber in a sealed casing, provides a drive shaft in the crank chamber, and connects the drive shaft to the crank chamber. A drive swash plate is attached with a variable inclination angle, and the rotation of the drive swash plate causes a plurality of pistons to linearly reciprocate via the wobble plate and the piston rod, and the refrigerant is returned to the sealed casing. The suction pressure of the piston and the discharge pressure discharged from the piston to the protruding port are appropriately selected by a control valve and guided into the crank chamber, and the inclination angle of the driving swash plate is controlled by adjusting the pressure inside the crank chamber. The variable capacity swash plate compressor is characterized in that a check valve that opens when the discharge pressure becomes abnormally high is provided in the communication passage that communicates the discharge port with the crank chamber. .

(Function) In this way, when the discharged refrigerant reaches abnormally high pressure, the check valve provided in the communication passage that communicates the discharge port and the crank chamber opens, releasing this high pressure into the crank chamber and increasing the pressure inside the crank chamber. This makes it possible to limit the amount of compression of the piston and eliminate the abnormally high pressure.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a main part showing an embodiment of the present invention, and corresponds to a cross section taken along the - line in FIG. 3. The same reference numerals are given to the same members, and the explanation thereof will be omitted hereafter.

Variable capacity swash plate type compressor 60 shown in Fig. 1
A protection device 61 is provided to release the discharge pressure to the crank chamber 12 when the discharge pressure becomes abnormally high (20 to 30 kg/cm ² ).

For example, when cooling the inside of a car that climbs a steep slope in the summer, heat dissipation in the condenser is insufficient due to low ram pressure, and the compressor must perform its maximum capacity. The discharge pressure of the compressor may become abnormally high.

When such an abnormally high pressure occurs, in this embodiment, the protection device 61 allows this high pressure to escape to the crank chamber 12.

This protection device 61 connects a communication passage 62 that communicates the discharge port 33 and the crank chamber 12 to the cylinder 25.
A check valve 63 is provided in the communication passage 62.

This check valve 63 has a ball valve 65 that closes a valve seat portion 64 provided in the communication passage 62, and the ball valve 65 is moved by a coil spring 66 in a direction that prevents refrigerant from flowing in from the discharge port 33 side. It is designed to be repelled by a predetermined pressure.

In the protection device 61 having such a check valve 63, when abnormally high-pressure refrigerant is discharged to the discharge port 33, the ball valve 65 resists the elastic force of the coil spring 66 due to the pressure of this refrigerant. The high-pressure refrigerant is separated from the valve seat 64 and transferred to the crank chamber 12 with a large volume.
This will increase the pressure inside the crank chamber 12.

Due to the inflow of this high-pressure refrigerant, the inside of the crank chamber 12 becomes high pressure, but this high pressure makes it difficult for the piston 23 to retreat as described above.
The amount of compression due to 3 is reduced.

Therefore, the amount of refrigerant flowing into the cooling circuit is reduced, and various members or devices provided in this cooling circuit are no longer affected by the abnormally high pressure, and the abnormally high pressure refrigerant is not released into the atmosphere. It can also be prevented from happening.

In the embodiment described above, the check valve 63 is provided between the discharge port 33 and the crank chamber 12, but in other embodiments, a solenoid valve (see FIG. (not shown), and the solenoid valve may be configured to open when a pressure sensor that detects the discharge pressure of the compressor detects abnormal pressure.

[Effects of the invention] As described above, according to the invention, a check valve that opens when the discharge pressure becomes abnormally high is provided in the communication passage that communicates the discharge port and the crank chamber. Even if the pressure becomes abnormally high, the refrigerant is not released to the atmosphere, but is allowed to escape into the crank chamber and can be reused, making it extremely economical and eliminating the need for troublesome work such as re-injecting the refrigerant.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing the main parts of an embodiment of the present invention, Fig. 2 is a sectional view showing a conventional variable capacity swash plate type compressor, and Fig. 3 is a view taken along the - line in Fig. 2. It is a schematic sectional view. 11... Drive shaft, 12... Crank chamber, 13...
... Drive swash plate, 16 ... Wobble plate, 17 ... Casing, 22 ... Piston rod, 23 ... Piston, 36, 39 ... Valve member, 61 ... Valve casing, 62 ... Communication path, 63 ... Reverse stop valve,
Cv...Control valve, Pd...Discharge pressure, Ps
...Suction pressure.

Claims (1)

[Scope of utility model registration request] A crank chamber 12 is formed in a sealed casing 17, a drive shaft 11 is provided in this crank chamber 12,
A drive swash plate 13 is attached to the drive shaft 11 with a variable inclination angle, and rotation of the drive swash plate 13 causes a plurality of pistons 23 to linearly reciprocate via the wobble plate 16 and the piston rod 22. At the same time, the suction pressure Ps of the refrigerant returning to the sealed casing 17 and the piston 23
The discharge pressure Pd discharged to the protruding port 33 from the control valve Cv is appropriately selected and guided into the crank chamber 12, and the inclination angle of the drive swash plate 13 is controlled by adjusting the pressure inside the crank chamber 12. In the variable capacity swash plate type compressor, a check valve 63 that opens when the discharge pressure Pd becomes abnormally high is connected to the discharge port 3.
1. A protection device for a variable capacity swash plate type compressor, characterized in that it is provided in a communication passage 62 that communicates between a crank chamber 12 and a crank chamber 12.