JPH0754120B2 - Variable displacement rotary compressor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary compressor suitable for use as a refrigerant compressor of an air conditioner for automobiles and the like.

2. Description of the Related Art In recent years, a compressor having a variable discharge capacity has been proposed in order to achieve both cooling performance and reduction of compressor power consumption.

This type of conventional variable displacement rotary compressor has a structure as shown in FIG.

That is, a bypass passage 6 that connects the working chamber 4 and the suction passage 5 is provided in the middle of the compression stroke in which the working chamber 4 defined by the cylinder 1, the rotor 2, and the vanes 3 decreases in volume. Open / close valve 7 for opening and closing
When the opening / closing valve 7 is closed, the entire amount of the refrigerant sucked into the working chamber 4 from the suction port 8 is compressed and the discharge port 9 is discharged.
Part of the refrigerant discharged from the suction port 8 to the working chamber 4 in the open state returns to the suction passage 5 through the bypass passage 6, so that the discharge capacity of the compressor can be increased or decreased by opening / closing the bypass passage 6. It has become. (For example,
However, since the refrigerant sucked into the working chamber 4 is slightly compressed and flows into the suction passage 5 from the bypass passage 6 by the structure as described above, The compression work given to the refrigerant becomes a loss, which deteriorates the efficiency of the compressor, and the refrigerant in the suction passage 5 is heated by the loss, and as a result, the temperature of the discharged refrigerant rises and the compressor, There is a problem that durability of refrigerating machine oil and a rubber hose for a refrigerant pipe is deteriorated.

Means for Solving the Problems In order to solve the above problems, the present invention operates an expander capable of recovering the compression work from the return refrigerant by utilizing a part of the suction stroke in which the volume of the working chamber increases. With this structure, the first suction port that communicates with the suction chamber and opens into the working chamber at the end point of the suction stroke and the suction chamber that communicates with the suction chamber through the suction passage operate on the suction side in the vicinity of the minute gap between the rotor and the cylinder. A second inlet opening to the chamber, a bus path passage having one end opened to the high-pressure side space of the compressor or a working chamber in the middle of the compression stroke and the other end opened to the intake passage, and a communicating portion between the bypass passage and the intake passage And a passage switching means capable of selectively communicating the second suction port with the suction chamber or the bypass passage.

Effect of the Invention With the above-described configuration, the return refrigerant that has flowed from the second suction port into the working chamber at the beginning of the suction stroke through the bypass passage expands in the working chamber as the rotor rotates and works on the compressor. In order to do so, the compression work of the return refrigerant is recovered again in the compressor. Then, when the rotor further rotates to increase the volume of the working chamber and the pressure in the working chamber decreases to the pressure on the suction side of the compressor, the working chamber communicates with the first suction port and the refrigerant operates from the first suction port. It flows into the room.

As a result, the compressor discharge capacity can be reduced, and there is no loss due to the return refrigerant, so the compressor efficiency does not decrease, and the discharge temperature does not rise as much as there is no loss.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 3 of the accompanying drawings.

In the figure, 11 is a cylinder having a cylindrical inner wall, and a front side plate 12 and a rear side plate 13 are arranged at both ends of the cylinder 11.

Further, in the cylinder 11, a rotor 14 rotatably supported by an inner wall of the cylinder 11 through a small gap A and a vane 15 slidably held by the rotor 14 are arranged to form a working chamber 16. ing.

The first suction port 17 opens at a position where the maximum volume is formed in the working chamber 16 on the volume increasing side of the working chamber 16 whose volume increases and decreases as the rotor 14 rotates, and the second suction port near the minute gap A. 18 is open. The first suction port 17 communicates with the suction chamber 19, and the second suction port 18 communicates with the suction chamber 19 through a suction passage 20.

On the other hand, one end of the bypass passage 21 is opened in the working chamber 16 on the volume decreasing side, and the discharge port 23 is opened in the vicinity of the minute gap A. The other end of the bypass passage 21 is open to the suction passage 20. A passage switching valve 22 is provided in a communication portion between the bypass passage 21 and the suction passage 20, and operates to connect the second suction port 18 and the suction chamber 19 or to connect the second suction port 18 and the bypass passage 21. Are configured to communicate with each other.

Next, the operation of the configuration of this embodiment will be described.

First, a case where the refrigerating capacity of the compressor is relatively small, such as when the compressor is operated at low speed, will be described.

In this case, the state is detected by an engine speed detection sensor (not shown) and a high / low pressure signal of the refrigeration cycle, and the passage switching valve 22 detects the state of the suction chamber 19 and the second suction port as shown in FIG.
The refrigerant communicating with 18 and flowing into the suction chamber 19 from a refrigeration cycle (not shown) is the first suction port 17 and the second suction port.
It is sucked into the working chamber 16 from 18, and the amount thereof is compressed and discharged from the discharge port 23.

Next, a case will be described in which the refrigerating capacity of the compressor is relatively large, such as when the compressor is operating at high speed, and therefore the discharge capacity is reduced to reduce the power consumption of the compressor.

In this case, the passage switching valve 22 is a bypass passage as shown in FIG.
21 and the second suction port 18 are communicated with each other, so that a part of the refrigerant in the middle of the compression stroke passes from the working chamber 16 through the bypass passage 21, the suction passage 20, and the second suction port 18 to the working chamber 16 in the suction stroke.
Return to. When the vane 15 passes through the second suction port 18 and forms the working chamber 16 on the lag side of the vane 15 by the rotation of the rotor 14, the working chamber 16 returns to the working chamber 16 with pressure increase due to the refrigerant and the volume of the working chamber 16. Although there are two factors at the same time, that is, pressure drop due to increase, by appropriately selecting the amount of the return refrigerant, the re-expansion of the return refrigerant is completed immediately before the working chamber 16 communicates with the first suction port 17 and the working chamber is completed. 16 Intake chamber 19
The internal pressure can be reduced. When the rotor 14 further rotates and the working chamber 16 communicates with the first suction port 17, the refrigerant in the suction chamber 19 is sucked into the working chamber 16.

Therefore, the return refrigerant is expanded to the pressure in the suction chamber 19, that is, the suction pressure of the compressor, so that it works for the compressor by that amount, and the discharge capacity can be reduced without lowering the efficiency of the compressor and the loss is lost. The discharge temperature does not rise as much as there is no discharge.

Although the one end opening of the bypass passage 21 is provided in the working chamber 16 in the middle of the compression stroke in the present embodiment, the same effect can be obtained by providing it on the high pressure side of the refrigeration cycle including the compressor.

Further, in the present embodiment, the communication between the second suction port 18 and the suction chamber 19 or the bypass passage 21 is performed by the passage switching valve 22, but the other end opening of the bypass passage 21 is provided in the vicinity of the minute gap A independently of the suction passage 20. A passage opening / closing valve that opens to the suction side working chamber 16 and independently connects and disconnects the passages may be provided, or a passage opening / closing valve may be provided in the bypass passage and a backflow from the working chamber 16 may be prevented in the second suction port 18. A check valve may be provided.

Further, although a so-called perfect circular vane rotary compressor is shown in the present embodiment, any rotary compressor whose suction stroke can be used as an expander may be used, and the present invention is not limited to the above embodiment. .

EFFECTS OF THE INVENTION The present invention relates to a part of a suction process of a rotary compressor,
A refrigerant which has been given a compression work is returned from the bypass passage through the second suction port to the working chamber by the passage switching valve, and the effective expansion work is taken out from the returning refrigerant before the working chamber communicates with the first suction port. Therefore, even when the compressor is operating at 100% capacity, the second intake port 18 is operated during small capacity operation.
Therefore, the fluid can be supplied into the working chamber 16.

In addition, there is no power loss due to the pressure drop in the working chamber 16 during 100% capacity operation, and the power can be reduced, and the compressed fluid expands only in the working chamber 16 even during small capacity operation to perform effective work for the compressor. A highly efficient compressor can be provided.

[Brief description of drawings]

FIG. 1 is an axial sectional view of a variable displacement rotary compressor according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line XX of FIG. 1, and FIG. 3 is a passage switching in FIG. FIG. 4 is a partial sectional view showing a state in which the valves are switched, and FIG. 4 is a sectional view of the conventional compressor. 11 …… Cylinder, 12 …… Front side plate, 13 …… Rear side plate, 14
...... Rotor, 15 …… Vane, 16 …… Operating chamber, 17 …… First
Suction port, 18 ... second suction port, 19 ... suction chamber, 20 ... suction passage, 21 ... bypass passage, 22 ... passage switching valve.

Claims (1)

[Claims] 1. A cylinder having a cylindrical inner wall, side plates closing both ends of the cylinder, a rotor rotatably disposed in the cylinder with a minute gap formed between the cylinder inner wall and the rotor, or the rotor. A first opening to the working chamber at a position where the working chamber defined by the vane slidably held in the cylinder, the cylinder, the side plate, the rotor and the vane, and having a volume change caused by the rotation of the rotor forms the maximum volume An inlet, a second inlet opening into the working chamber on the volume increasing side in the vicinity of the minute gap, and the first inlet
A suction chamber that communicates with the suction port, a suction passage that communicates the suction chamber with the second suction port, one end of the suction chamber that opens to the high pressure side space of the compressor or the working chamber that is in the middle of volume reduction, and the other end A bypass passage that opens to the suction passage, and a second passage that is disposed in a communication portion between the bypass passage and the suction passage.
A variable displacement rotary compressor comprising: a passage switching means capable of selectively communicating an intake port with an intake chamber or a bypass passage.