JPH0526954B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in a refrigeration and cooling system configured to circulate refrigerant between a refrigeration evaporator and a cooling evaporator using a single refrigerant compressor. It relates to a refrigerant compressor and is suitable for use in refrigerated vehicles.

[Conventional technology]

Japanese Utility Model Publication No. 56-50362 describes a cooling/refrigeration system configured to circulate refrigerant between a cooling evaporator and a refrigerating/freezing evaporator using a single multi-cylinder refrigerant compressor. cylinders are divided into two groups, one group is used for freezing and the other group is used for cooling, and when either freezing or cooling is used, both groups perform cooling or freezing operation. , has been disclosed in which the refrigeration operation takes priority over the cooling operation when the refrigeration and cooling operations are used together.

[Problem that the invention seeks to solve]

In this type of device, the temperature of the refrigerant in the cooling evaporator is adjusted to prevent freezing of the fin surface.
Generally, the temperature is not lower than 5°C, and to achieve this, the evaporation pressure of the refrigerant in the cooling evaporator is controlled to be about 2.5 kg/cm ² . On the other hand, an evaporator for refrigerating and freezing is required to make ice, so the temperature is -21
℃, the evaporation pressure of the refrigerant in the refrigeration/freezing evaporator is controlled to be lower, for example, about 0.5 kg/cm ² .

Therefore, the cylinders of a multi-cylinder compressor are divided into two groups, with the first group drawing high-pressure refrigerant from, for example, a cooling evaporator, and the second group drawing low-pressure refrigerant from a refrigeration-refrigeration evaporator. When the refrigerant is sucked in and compressed in the cylinders of each group, a large difference occurs in the discharge amount per cylinder between the first and second groups. That is, even if all the cylinders of the compressor have the same volume, 2.5
The discharge volume of each cylinder in the second group, which sucks and compresses 0.5 kg/cm ² of low-pressure refrigerant, is greater than the discharge volume of each cylinder in the first group, which sucks and compresses high-pressure refrigerant of 0.5 kg/cm ² . Since the refrigerant is much smaller, the number of cylinders for low-pressure refrigerant should be increased accordingly, or the volume of the cylinder for low-pressure refrigerant should be increased accordingly.
As a result, there is a problem in that the compressor becomes larger.

[Means for solving problems]

In the present invention, a multi-cylinder swash plate compressor is used, but instead of dividing the plurality of cylinders into two groups, low-pressure refrigerant is sucked into all the cylinders from the main suction port. Then, at the final stage of the suction stroke of the selected cylinder, the high-pressure refrigerant is also sucked into the selected cylinder by utilizing the pressure difference between the low-pressure refrigerant and the high-pressure refrigerant. In order to suck the high-pressure refrigerant in this way, the swash plate chamber is always communicated with the high-pressure refrigerant sub-intake port, and a communication mechanism is provided to communicate the swash plate chamber with the selected cylinder. In order to facilitate the machining of this communication mechanism, the selected cylinders are arranged side by side in the circumferential direction of the swash plate chamber, and the communication mechanism is formed on the bottom surface of the recess in the cylinder block constituting the swash plate chamber. The slit is cut in the circumferential direction centering on the axis of the swash plate chamber, and opens in the shape of a notch in the inner peripheral surface of the selected cylinder at the final stage of the suction stroke of the selected cylinder. be.

〔Effect of the invention〕

Since the low-pressure refrigerant for refrigeration is sucked into all cylinders and compressed, the discharge amount is larger than if the selected cylinder was dedicated to low-pressure refrigerant, so the compressor could be made smaller accordingly. Not only is this achieved, but the slits cut in the bottom of the recess in the cylinder block in the circumferential direction of the swash plate chamber form a communication mechanism that draws high-pressure refrigerant into the selected cylinder from the swash plate chamber. Therefore, the slit can be easily formed by lathe processing, etc., which contributes to cost reduction.

〔Example〕

FIG. 5 schematically shows a refrigeration cycle configured to perform refrigeration and room cooling using a single refrigerant compressor 1.
For convenience, the compressor 1 is shown as having a piston driven by a crank; however, it should be understood that the compressor 1 is of a multi-cylinder swash plate type as will be described later.

The refrigerant discharged from the discharge port 2 of the compressor 1 passes through the high-pressure pipe 3, the condenser 4, and the receiver 5, and then branches into an evaporator 6 for freezing and an evaporator 7 for cooling.
A temperature-operated expansion valve 1 is provided on the upstream side of the refrigeration evaporator 6.
A solenoid valve 14 is provided upstream of the evaporator 2, and a check valve 17 is provided downstream of the evaporator 6. Main suction port 9 which is a suction port for low pressure refrigerant
It is connected to the. Further, a temperature-operated expansion valve 13 is provided upstream of the cooling evaporator 7, and an electromagnetic valve 15 is provided upstream thereof. Evaporator 7
The downstream side of the refrigerant is connected via a high-pressure pipe 10 to an auxiliary suction port 11 that is a high-pressure refrigerant suction port of the compressor 1 . The sub-inlet 11 communicates with a swash plate chamber 18 within the compressor 1, and the swash plate chamber 18 communicates with the cylinder via a communication mechanism 19 at the final stage of the suction stroke of the compressor. The low pressure pipe 8 and the high pressure pipe 10 are connected by a pipe 16a having a solenoid valve 16 in the middle. Since the refrigeration evaporator 6 needs to be cooled down to a low temperature (for example -21°C) for ice making, the expansion valve 12 is operated so that the evaporation pressure of the refrigerant in the evaporator 6 is, for example, approximately
It is set to be maintained at ^around 0.5Kg/cm2, while
The cooling evaporator 7 is required to prevent the temperature from dropping below, for example, 5° C. so as not to cause frosting on the fins, so the expansion valve 13 maintains the evaporation pressure within the evaporator 7 at, for example, approximately 2.5 kg/cm ^{2 .} It is set as follows.
Therefore, low pressure refrigerant gas flows from the freezing evaporator 6 to the main suction port 9, and high pressure refrigerant gas from the cooling evaporator 7 flows to the sub suction port 11 and flows into the swash plate chamber 18. When the machine 1 sucks low-pressure refrigerant and reaches the final stage of its suction stroke, the swash plate chamber 18 communicates with the cylinder through the communication mechanism 19, and the swash plate chamber 18
The high-pressure refrigerant flows into the cylinder due to the pressure difference with the low-pressure refrigerant and mixes with the low-pressure refrigerant. The pressure of this mixed refrigerant is approximately the same as the pressure in the swash plate chamber 18, and therefore approximately equal to the evaporation pressure of the cooling evaporator 7. Therefore, the compressor 1 moves from the pressure of the low-pressure refrigerant for refrigeration to the compression stroke. Compression starts from the pressure of the high-pressure refrigerant used for air conditioning. As a result, the compressor 1 has a large discharge capacity compared to its cylinder volume.

By closing the solenoid valve 16 and leaving the solenoid valves 14 and 15 open, freezing and cooling can be performed at the same time, and by opening the solenoid valve 14 and closing the solenoid valves 15 and 16, only refrigeration operation can be performed. It is also possible to perform only cooling operation by closing the solenoid valve 14 and opening the solenoid valves 15 and 16.

Next, the structure of the compressor 1 will be explained with reference to FIGS. 1 to 3 and FIG. 4, which schematically shows the internal structure of the compressor.

The compressor 1 has a cylinder housing 20 comprised of front and rear cylinder blocks 20a and 20b that are hermetically assembled in axial alignment with each other. cylinder housing 2
Five cylinder bores A-E are formed in 0,
There are five pistons 21 inside these cylinder bores.
are slidably mounted, and both end surfaces of each piston cooperate with cylinder bores A to E to form ten cylinders (cylinder chambers) 22.

The two cylinder blocks 20a, 20b
Circular recesses 18a and 18b recessed in the axial direction are formed in the center of the mutually abutted end surfaces, and these two recesses are combined facing each other to form the swash plate chamber 18. . A swash plate 24 is disposed within the swash plate chamber 18 and is fixed to the shaft 23 and rotates therewith. When the plate 24 rotates, the rotation is converted into an axial reciprocating motion of the piston 21.

At both ends of the cylinder housing 20, circular valve plates 27, 27 each have a plurality of suction ports 25 and the same number of discharge ports 26.
Front side and rear side end plates 28a and 28b are attached via. The suction port 25 and the discharge port 26 are connected to each cylinder 2.
2, the suction port 25 is provided with a suction valve 25a, and the discharge port 26 is provided with a discharge valve 26a.

The main suction port 9 is provided on the upper side of the circumferential wall of the cylinder housing 20 and communicates with a suction passage 29 extending in the axial direction within the circumferential wall. Suction chambers 30a, 30 are provided inside the front and rear end plates.
b is formed and communicates with the suction passage 29 and also communicates with all the suction ports 25. Similarly, the discharge port 2 is also provided on the upper side of the peripheral wall of the cylinder housing 20, and a discharge passage 31 extends in the axial direction within the peripheral wall.
communicate with. Discharge chambers 32a, 32 are provided inside the front and rear end plates 28a, 28b.
b is also formed and communicates with the discharge passage 31 and also with the discharge port 26.

One end of the shaft 23 rotatably passes through the front end plate 28a and protrudes outside the compressor, and a pulley 33 is fixed to this protruding end and is drivingly connected to a rotational drive device such as an engine by a belt. ing.

The swash plate chamber 18 communicates with a communication chamber 18c formed outside the circular row of cylinders 22 within the cylinder housing 20, and this communication chamber 18 communicates with the sub-intake port 11 provided on the side of the peripheral wall of the cylinder housing 20. It communicates with

Cylinder bores A-E open at the bottoms of recesses 18a and 18b forming swash plate chamber 18, but piston 21 in the cylinder bore closes the inner end of cylinder 22 (the end adjacent to swash plate chamber 18). There is.
However, in the compressor of the present invention, when the piston 21 in the cylinder 22 moves to near the final position of its intake stroke, the cylinder 22
and the swash plate chamber 18 communicate with each other via the communication mechanism 19. This communication mechanism 19 consists of a slit cut in the bottom surface of a recess 18b forming the swash plate chamber 18 of the cylinder block 22b in a circumferential direction centered on the axis of the swash plate chamber 18. As is clear from FIGS. 3 and 4, this slit 19 opens in the shape of a notch in the inner peripheral surface of the cylinder 22 when the piston 21 moves to the vicinity of its bottom dead center (the end of the suction stroke). It's becoming like that.

As mentioned above, since the slit 19 is cut in the bottom surface of the recess 18b in the circumferential direction around the axis of the swash plate chamber 18, it can be easily formed by lathe processing etc. The notch opens on the inner surface of the cylinder only when the piston moves to the vicinity of its bottom dead center.In other words, after the low-pressure refrigerant for refrigeration has been sufficiently sucked into the cylinder, the cylinder and diagonal The high-pressure refrigerant for cooling is introduced into the cylinder from the swash plate chamber by communicating with the plate chamber 18. Therefore, high-pressure refrigerant is introduced into the cylinder while maintaining a sufficient amount of low-pressure refrigerant sucked into the cylinder 22. It has the effect of introducing it well and reliably.

Although FIG. 2 shows only the cylinder block 20b provided with the slit 19, in this embodiment the slit 19 is provided in both cylinder blocks 20, 20b as shown in FIG.

The operation of the compressor 1 seems obvious from the above explanation, but just to be sure, the main suction port 9
The low-pressure refrigerant from the freezing evaporator 6 flows through the suction passage 29 and reaches the suction ports 30a and 30b, while the high-pressure refrigerant from the cooling evaporator 7 flows from the sub-suction port into the communication chamber 18c. It flows into the swash plate chamber 18 through the. When each piston 21 begins to move toward the bottom dead center during the suction stroke, the suction valve 25a opens and the suction chambers 30a, 30b open.
A low pressure refrigerant is introduced into the cylinder 22 from the cylinder 22 . When the piston 21 moves to a position near its bottom dead center, the slit 19 opens to the cylinder 22, so that cooling refrigerant with a pressure higher than the pressure of the low-pressure refrigerant in the cylinder 22 flows from the swash plate chamber 18 through the slit 19. The refrigerant flows through the cylinder 22 and mixes with the low pressure refrigerant. Therefore, the pressure of the refrigerant in the cylinder 22 is approximately equal to the evaporation pressure of the cooling evaporator 7, and this cylinder starts the compression stroke from this pressure, so the discharge amount is lower than when only low-pressure refrigerant is sucked and compressed. is large. The compressed refrigerant is discharged into the discharge chambers 32a, 3 by opening the discharge valve 26a.
2b, from here through the discharge passage 31 to the discharge port 2, and from here through the high pressure pipe 3 to the condenser 4.
flows into. The flow of the refrigerant after this is as described above.

In the above embodiment, the slits 19 are cut in the bottom surfaces of the recesses 18a, 18b in the front and rear cylinder blocks 20a, 20b in the circumferential direction centered on the axis of the swash plate chamber 18. Front and rear cylinder blocks 20a, 20
Although the five cylinders 22 in b are connected in the circumferential direction by the slits 19 (see FIG. 2), the present invention is not limited to such a structure. If necessary, a slit 19 is formed only on the bottom of the recess 18a or 18b in the cylinder block on the front side only or on the rear side only.
Alternatively, as shown in FIG. 6, the rear cylinder block 20b (or
The slits 19 may be cut so as to connect only selected cylinders (three in FIG. 6) of the five cylinders 22 in the front cylinder block 20a) in the circumferential direction. In either case, the selected cylinders are arranged in parallel in the circumferential direction of the swash plate chamber 18 to facilitate machining of the slit 19.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a refrigerant compressor according to an embodiment of the present invention, and Fig. 2 is a front view of one cylinder block viewed from the other cylinder block, showing the shaft and diagonal view. Figure 3 is a fragmentary enlarged sectional view showing the relationship between the swash plate chamber, cylinder, piston, and slit, and Figure 4 schematically shows the internal structure of the compressor. The explanatory diagram, FIG. 5, is a diagram showing a refrigeration cycle using the compressor of the present invention, and FIG. 6 is a diagram similar to FIG. 2, showing a modified embodiment of the slit. 1...Compressor, 2...Discharge port, 4...Condenser,
5... Receiver, 6... Refrigeration evaporator, 7... Cooling evaporator, 9... Main inlet, 11... Sub-inlet, 18... Swash plate chamber, 18a, 18b... Recess,
19... Communication mechanism (slit), 20... Cylinder housing, 21... Piston, 22... Cylinder (A to E... Cylinder bore), 30a, 30
b...Suction chamber, 32a, 32b...Discharge chamber.

Claims (1)

[Claims] 1. A main suction port for low-pressure refrigerant from a freezing evaporator, a sub-suction port for high-pressure refrigerant from a cooling evaporator, a suction chamber that constantly communicates with the main suction port, and a suction valve that a cylinder housing formed with a plurality of cylinders communicating with the chamber; a piston slidably mounted in the cylinder in the axial direction; and a swash plate chamber formed in the cylinder housing and constantly communicating with the sub-intake port. , a swash plate disposed within the swash plate chamber and rotating with the shaft to drive the piston; a communication mechanism that communicates with the swash plate chamber, the selected cylinders are arranged side by side in the circumferential direction of the swash plate chamber, and the communication mechanism includes a recess in a cylinder housing that constitutes the swash plate chamber. a notch-like opening in the inner circumferential surface of the selected cylinders at the final stage of the suction stroke of the selected cylinders; A refrigerant compressor comprising a slit.