JPS6237745B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure reducing device for a refrigeration system,
For example, it is suitable as a refrigeration system for an automobile air conditioner.

As shown in FIG. 1, a conventional refrigeration system includes a compressor 1, a condenser 2, a capillary tube 3b forming a pressure reducing device 3, an evaporator 4, and the refrigerant from the evaporator 4 is divided into gas refrigerant and liquid refrigerant. and an accumulator 5 that separates the gas refrigerant into the compressor 1 and supplies only the gas refrigerant to the compressor 1. In the automobile refrigeration system, the compressor 1 is driven by an automobile engine (not shown) via an electromagnetic clutch 1a.

In addition, in conventional devices of this kind, in order to prevent the evaporator 4 from freezing, a pressure switch 6 is attached to the low-pressure side circuit components such as the accumulator 5, and the pressure switch 6 is used to turn off and turn on the electromagnetic clutch 1a. 1 is operated intermittently. That is, when the refrigerant pressure (low-pressure side pressure) in the accumulator 5 falls below a predetermined value, the pressure switch 6 is opened, and the electromagnetic clutch 1a is de-energized to stop the compressor 1, while the refrigerant pressure in the accumulator 5 is When the pressure rises above a predetermined value, the pressure switch 6
returns to the closed state, and the compressor 1 is restarted.

However, as described above, the refrigeration system that performs so-called ON-OFF control, which uses the pressure switch 6 to intermittent operation depending on the pressure on the low pressure side of the cycle, has the following drawbacks in actual use. That is, when the above-mentioned device shown in FIG. Due to the difference between the internal pressure of the condenser 2 and the internal pressure (low-pressure side pressure) of the condenser 2, it flows into the evaporator 4 through the capillary tube 3b, which is a fixed throttle. Therefore, the rising speed of the pressure on the low pressure side becomes faster, and this causes the ON-OFF cycle of the refrigeration system to become shorter, which inevitably increases the number of times the compressor 1 is turned on and off, causing the compressor 1 and the electromagnetic clutch 1a to It has the disadvantage that it has a negative effect on the durability life and cooling feeling.

In view of the above points, the present invention uses a supercooling degree control valve that completely closes the refrigerant passage when the equipment is stopped as a pressure reducing device for a refrigeration equipment, and controls the equipment according to the supercooling degree control valve and the low pressure side pressure. By combining this with a pressure switch that intermittents operation, when the pressure switch stops the equipment, the subcooling degree control valve works to prevent refrigerant from flowing from the condenser to the evaporator side, allowing the pressure on the low pressure side to rise slowly. It is an object of the present invention to provide a refrigeration system capable of reducing the number of times the compressor is turned on and off, thereby improving its durability and cooling feeling.

The present invention will be described below with reference to embodiments shown in the drawings. FIG. 2 shows an example in which the present invention is applied to an automobile air conditioner. Reference numeral 1 denotes a compressor, which is driven by an automobile engine (not shown) via an electromagnetic clutch 1a. A condenser 2 is installed around the radiator in the engine room of the automobile, and is cooled by a fan 2a. Reference numeral 3 denotes a pressure reducing device, which is composed of a subcooling degree control valve 3a that controls the degree of subcooling of the liquid refrigerant at the outlet of the condenser. It is desirable to set it up as a

Reference numeral 4 denotes an evaporator, which is installed at the bottom of the instrument panel inside the vehicle interior, and is used to cool the air inside or outside the vehicle blown by a fan 4a, and the cooling air is sent into the vehicle interior through an outlet (not shown). It's starting to blow out. 5 is an accumulator, and evaporator 4
The refrigerant is separated into gas refrigerant and liquid refrigerant, and only the gas refrigerant is sucked into the compressor 1, and is installed in the engine room of an automobile. Reference numeral 6 denotes a pressure switch attached to the accumulator 5, which opens and closes depending on the refrigerant pressure within the accumulator 5, that is, the pressure on the low pressure ^side . When the pressure on the low pressure side rises to 2.5 to 4 kg/cm ² G or more, the valve becomes closed. As this pressure switch 6, a known one such as a diaphragm type may be used. This pressure switch 6 is provided in series with the energizing circuit of the electromagnetic clutch 1a of the compressor 1, as shown in FIG. 7 is a manual operation switch for the refrigeration system, and 8 is a power battery for the automobile.

Next, the detailed structure of the supercooling degree control valve 3a described above is shown in FIG. A refrigerant outlet passage 11 connected to the inlet side of the refrigerant is provided. 12 is a cylindrical cavity formed in the main body case 9; 13 is a cylindrical bellows made of phosphor bronze, which is disposed within the cavity 12; a seat 13a at one end of the bellows is provided with a metal conduit; 14 is brazed, and a needle valve 15 is brazed to the other end. The same refrigerant (R-12) as the refrigerant sealed in the refrigeration cycle is introduced into the bellows 13 via the conduit 14, and by brazing the end of the conduit 14, the refrigerant inside the bellows 13 is It is sealed to prevent leakage.

The bellows 13 is provided with a bellows portion 13b on its outer surface so that it can be expanded and contracted. The bellows 13 is housed in the cavity 12 via a spring 17 so that the needle valve 15 is located within the nozzle portion 16 of the refrigerant outlet passage 11, and is provided on the inner periphery of the cavity 12. By screwing and fixing the adjusting nut 18 with the through hole 18a into the female threaded portion 12a, the adjusting nut 18 and the spring 17
It is held so that it does not fall off between the two. Note that by changing the screwing amount of the adjusting nut 18, the amount of expansion and contraction of the bellows 13, that is, the nozzle portion 1 of the needle valve 15, can be adjusted.
The amount of protrusion into 6 can be changed. 19
is a blind bolt, which is airtightly fixed to the female threaded portion 12a of the main body case 9 via an O-ring 20, and the open end of the cavity 12 is sealed by this blind bolt 19. 21 is the refrigerant inlet passage 10
This is a wire mesh filter that is tightly fixed to the stepped portion of the refrigerant, and is used to remove foreign matter such as dust from the refrigerant.

Next, the operation of the apparatus of the present invention having the above structure will be explained. The gas refrigerant compressed by the compressor 1 is transferred to the condenser 2
It condenses to become a liquid refrigerant. This liquid refrigerant enters the cavity 12 from the refrigerant inlet passage 10 of the supercooling degree control valve 3a, passes through the constriction formed between the needle valve 15 and the nozzle part 16, is depressurized, and then flows through the refrigerant outlet passage 11. Then, it flows into the evaporator 4. Then, the refrigerant that has exited the evaporator 4 flows into the accumulator 5, where it is separated into gas refrigerant and liquid refrigerant, and the gas refrigerant is sent to the compressor 1.

To explain the operation of the subcooling degree control valve 3a in detail, the liquid refrigerant flowing in from the refrigerant inlet passage 10 passes through the bellows 13.
come into contact with. At this time, if the degree of supercooling of the liquid refrigerant is excessive compared to the predetermined degree of supercooling, the bellows 1
The refrigerant pressure inside the bellows 13 is relatively lower than that outside the bellows 13, and the bellows 13
It will shrink due to the load. Therefore, since the opening area of the constriction between the needle valve 15 and the nozzle part 16 increases, the flow path resistance of the refrigerant decreases, and as a result, the refrigerant flow rate increases and the liquid refrigerant in the condenser 2 flows into the accumulator. 5, the degree of supercooling of the refrigerant on the outlet side of the condenser 2 decreases to a predetermined value. On the other hand, if the degree of subcooling of the refrigerant on the outlet side of the condenser 2 is too small, the refrigerant pressure in the bellows 13 increases and the bellows 13 expands, so that the constriction between the needle valve 15 and the nozzle part 16 The opening area decreases, and as a result, the flow path resistance of the refrigerant increases, so the refrigerant flow rate decreases and the proportion of liquid refrigerant in the condenser 2 increases. Therefore, the degree of subcooling of the refrigerant will increase to a predetermined value. Therefore, the refrigeration cycle is always efficiently operated in the optimum subcooling degree range.

Furthermore, in order to prevent frosting of the evaporator 4, the pressure switch 6 is used to intermittently control the operation of the compressor 1 by intermittent power supply to the electromagnetic clutch 1a, and now the low pressure side pressure has reached a predetermined value. When the pressure decreases and the pressure switch 6 opens and the operation of the compressor 1 is stopped, the high-pressure side pressure quickly decreases, which is the same as a decrease in the degree of supercooling, and the degree of supercooling control valve The opening area of the throttle portion 3a continues to decrease until it is completely closed, preventing the refrigerant in the condenser 2 from flowing into the evaporator 4 side. Therefore, when the compressor is stopped, the pressure inside the evaporator 4, that is, the pressure on the low pressure side, increases slowly, and as a result, the compressor can be stopped for a longer time, and the ON-OFF cycle of the compressor 1 becomes longer. ,
The number of compressor interruptions can be reduced. Moreover, this reduces the operating time of the compressor, which is advantageous from the viewpoint of power saving.

Furthermore, when the compressor 1 is restarted, the pressure on the high pressure side rises quickly, resulting in the same phenomenon as when the degree of supercooling is excessive, and the opening area of the throttle part of the degree of supercooling control valve 3a becomes sufficiently large, allowing the restart Sufficient refrigerant corresponding to the cooling load is supplied to the evaporator 4 from the initial stage of startup, so that the cooling capacity per unit of power consumed by the compressor can be significantly improved.

FIG. 5 shows the characteristics of the ON-OFF control according to the present invention. The vertical axis shows the pressure P on the low pressure side of the cycle, and the horizontal axis shows the time t. The solid line A shows the compression by the device of the present invention. Indicates the machine ON-OFF cycle,
The broken line B shows the compressor ON-OFF cycle according to the conventional device. As is clear from the comparison of cycles A and B, in the present invention, the OFF time of the compressor 1 can be extended by more than twice that of the conventional device due to the action of the subcooling degree control valve 3a, and as a result, the OFF time of the compressor 1 can be extended by more than twice that of the conventional device. ―
The OFF period can be significantly lengthened, and the number of times the compressor 1 is turned on and off can be reduced.

Note that, although the above-described embodiments illustrate preferred embodiments of the present invention, the present invention is not limited thereto and can be modified in various ways. FIG. 6 shows another embodiment of the present invention, in which a capillary tube 3b is used in addition to the supercooling degree control valve 3a as the pressure reducing device 3. In this example, as shown in the Mollier diagram of FIG. 7, the pressure between a and b is reduced by the supercooling degree control valve 3a, and the pressure between b and c is reduced by the capillary tube 3b, so that: The pressure reduction width borne by the supercooling degree control valve 3a is reduced, the manufacturing precision thereof may be low, and manufacturing is facilitated.

FIG. 8 shows still another embodiment of the present invention, in which a control circuit 22 automatically controls the operation of the compressor 1.
In this refrigeration system, a pressure switch 6 is connected to the input side of a control circuit 22. In this example, the relay 22c is opened and closed via the amplifier circuit 22b in response to signals from the detection unit 22a such as the engine speed and room temperature, thereby intermittent operation of the compressor 1, and in response to the opening and closing of the pressure switch 6. The relay 22c is opened and closed via the amplifier circuit 22b, and the operation of the compressor 1 is interrupted. Therefore, only a small current for controlling the amplifier circuit 22b flows through the pressure switch 6, and the current capacity of the pressure switch 6 can be reduced. Further, the pressure switch 6 may be wired so as to directly switch on and off the coil current of the relay 22c.

The specific structure of the subcooling degree control valve 3a is as follows.
It is not limited to the bellows type shown in the figure, but may also be a diaphragm type, and various modifications can be made.

Further, the mounting location of the pressure switch 6 is not limited to the accumulator 5, but can be mounted anywhere within the low pressure side circuit from the outlet of the pressure reducing device 3 to the inlet of the compressor 1.

Furthermore, it goes without saying that the present invention is not limited to automotive air conditioners, but can be widely applied to refrigeration systems in general.

As described above, in the present invention, the subcooling degree control valve 3a that controls the degree of subcooling of the liquid refrigerant at the outlet of the condenser is used as the pressure reducing device 3 of the refrigeration system, and the degree of subcooling is optimized by the degree of subcooling control valve 3a. Since it prevents large deviations from the value, the optimal degree of supercooling can always be obtained under any operating conditions, allowing efficient operation of the refrigeration equipment. When controlling the operation of the compressor on and off using the low pressure side pressure switch 6, it is possible to prevent unnecessary refrigerant from flowing into the evaporator from the condenser when the compressor is stopped, thereby slowing down the rate of increase in the low pressure side pressure. Therefore, compressor 1 ON-OFF
This has the excellent effect of lengthening the cycle and reducing the number of times the compressor is turned on and off, extending the life of cycle components such as the compressor, and improving the cooling feeling.

Furthermore, since the pressure on the low pressure side of the refrigeration cycle also decreases due to a decrease in the outside temperature and a decrease in the amount of refrigerant sealed in the cycle, the pressure switch 6 in the present invention decreases.
can serve as an outside temperature sensor to stop the compressor 1 when the outside temperature is low, and as a refrigerant amount sensor to stop the compressor 1 when there is a refrigerant shortage. This has a great effect in contributing to the simplification of the system.

[Brief explanation of the drawing]

Fig. 1 is a refrigeration cycle diagram of a conventional device, Fig. 2 is a refrigeration cycle diagram of an embodiment of the device of the present invention, Fig. 3 is an electric circuit diagram of an embodiment of the device of the present invention, and Fig. 4 is a diagram of the refrigeration cycle of an embodiment of the device of the present invention. A sectional view illustrating the specific structure of the supercooling degree control valve, FIG. 5 is an explanatory diagram of the operation of the device of the present invention,
FIG. 6 is a refrigeration cycle diagram showing another embodiment of the device of the present invention, FIG. 7 is a Mollier diagram for explaining the operation of the device shown in FIG. 6, and FIG. 8 is a diagram showing still another embodiment of the present invention. It is an electrical circuit diagram. 1... Compressor, 2... Condenser, 3... Pressure reduction device, 3a
...supercooling degree control valve, 3b...capillary tube,
4...Evaporator, 5...Accumulator, 6...Pressure switch.

Claims (1)

[Claims] 1. In a refrigeration system configured with a closed circuit in which a compressor, a condenser, a pressure reducing device, an evaporator, and an accumulator are sequentially connected, the degree of supercooling is used as the pressure reducing device to control the degree of supercooling of the refrigerant at the outlet of the condenser. The compressor is characterized in that it has at least a control valve, and that a pressure switch is provided in the low-pressure side circuit between the pressure reducing device and the compressor, and that is opened and closed according to the low-pressure side pressure, and the operation is made intermittent by this pressure switch. Refrigeration equipment.