JPH0330774Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) The present invention is a refrigerator that is used in vehicles, homes, etc., and is equipped with an evaporator antifreeze function.
The present invention relates to an evaporation pressure control device in a refrigeration cycle.

(Prior Art) A conventional evaporation pressure control device for a refrigeration cycle as described above is, for example, disclosed in Japanese Utility Model Publication No. 50-40123.
As disclosed in the publication, an evaporation pressure controller is installed in the middle of the piping connecting the evaporator and compressor that make up the refrigeration cycle, and a pressure equalization pipe of the expansion valve is connected to the discharge side of the evaporation pressure controller. It was a directly connected structure.

(Problem to be solved by the invention) In such a conventional device, since the pressure equalization pipe is directly connected to the discharge side of the evaporation pressure controller, the suction side pressure of the evaporation pressure controller is at the lowest level during low heat load. The pressure is controlled to 2.1Kg/cm ² G or more. However, the discharge side pressure of the evaporation pressure controller becomes less than 1 kg/cm ² G, especially when the compressor rotates at high speed, and the expansion valve becomes close to fully open. As a result, a problem arises in that more than the appropriate amount of refrigerant flows into the evaporator, which adversely affects the compressor due to liquid back and the like, and the power consumption of the compressor increases.

This invention was made in view of the above circumstances,
It is an object of the present invention to provide an evaporation pressure control device in a refrigeration cycle that prevents the compressor from being adversely affected by liquid back caused by more than an appropriate amount of refrigerant flowing into the evaporator, and also significantly reduces the power consumption of the compressor. shall be.

(Means for Solving the Problems) In order to achieve the above object, the present invention condenses refrigerant gas compressed by a compressor in a condenser and stores it as a refrigerant liquid in a liquid receiver, and transfers this refrigerant liquid to a thermosensor tube. The refrigerant flows into an expansion valve whose opening degree is determined by the sensed temperature of the refrigerant and the pressure of the pressure equalizing pipe, and is adiabatically expanded to form an atomized state. After evaporating this atomized refrigerant in an evaporator, In a refrigeration cycle in which suction is returned to the compressor via an evaporation pressure controller for freezing prevention, the outlet of the pressure equalization pipe connecting the evaporation pressure controller and the expansion valve is connected to the suction of the evaporation pressure controller. and a discharge side of the evaporation pressure controller, and a pressure equalizer is installed in the middle of the pressure equalization pipe to adjust the pressure on the discharge side of the evaporation pressure controller when the pressure difference between the suction side and the discharge side of the evaporation pressure controller is less than a predetermined value. The present invention is characterized in that a three-way switching valve is provided which operates to transmit the suction side pressure, which is higher than the discharge side pressure, to the pressure equalization tube when the pressure difference is above a predetermined value.

(Function) When the pressure difference between the suction side and the discharge side of the evaporation pressure controller is less than a predetermined value, the three-way switching valve switches to a predetermined state, and the pressure on the discharge side of the evaporation pressure controller is transferred to the pressure equalization pipe. The cooldown performance will be carried out as before. Also, when the pressure difference between the suction side and the discharge side of the evaporation pressure controller is more than a predetermined value,
The three-way switching valve is switched to a predetermined state, and the suction side pressure, which is higher than the discharge side pressure of the evaporation pressure controller, is transmitted to the pressure equalization pipe, the opening degree of the expansion valve is lowered, and superheat is maintained. , liquid back is improved.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram of a refrigeration cycle equipped with an evaporation pressure control device according to the present invention, in which 1 is a condenser, 2 is a compressor, 3 is a liquid receiver, 4 is an expansion valve, and 5
6 is an evaporator, and 6 is an evaporation pressure controller installed in the middle of the discharge side pipe 7 connecting the evaporator 5 and the discharge port of the compressor 2, and controls the evaporation pressure of the evaporator 5 to control the evaporation. This prevents the container 5 from freezing. Further, 8 is a temperature-sensitive tube that detects the temperature of the discharge side pipe 7 of the evaporator 5, and is used to adjust the valve opening degree of the expansion valve 4.

Suction side 6a and discharge side 6 of evaporation pressure controller 6
A pressure equalizing pipe 10 is connected between the expansion valve 4 and the expansion valve 4. In the middle of this pressure equalizing pipe 10, there is a pressure P ₁ on the suction side 6a of the evaporation pressure controller 6, and a pressure P1 on the discharge side 6b.
A three-way switching valve 11 that opens and closes depending on the pressure difference ΔP _c between the pressure P ₂ and the pressure P 2 and transmits the pressure P ₁ or P ₂ to the expansion valve 4 is interposed.

As shown in FIGS. 2 and 3, the three-way switching valve 11 has an inlet port 11a connected to the inlet side 6a of the evaporation pressure controller 6, a discharge port 11b connected to the discharge side 6b, and an expansion valve. The valve casing 1 includes a pressure equalizing port 11c connected to the pressure equalizing pipe 10 of No. 4.
2, a valve body 14 having a concave cross section and an opening 13 is slidably fitted in the valve body 14. This valve body 14 is always connected to the suction port 11a by a spring 15 provided inside the discharge port 11b side. biased toward the side.

Note that the pressure on the suction side 6a of the evaporation pressure controller 6
The pressure difference ΔP _c between P ₁ and the pressure P ₂ on the discharge side 6b is set to a predetermined value, for example, 0.8 Kg/cm ² , the spring constant of the spring 15 is 0.02 Kg/mm, and the diameter of the valve body 14 is 5φ.
Then, the strain length of the spring 15 when the valve body 14 is opened is π/4×0.5 ² ×0.8/0.02=8
mm.

Now, if P ₁ - P ₂ = 1Kg/cm ² , the spring 15 is 0.2Kg/cm ² ×π/4×0.5 ² ×0.02 = 2mm
The refrigerant is compressed and opened, and the refrigerant on the suction side 6a of the evaporation pressure controller 6 flows into the capillary on the pressure equalization pipe 10 side of the expansion valve 4. Therefore, the pressure equalization port 11 of the expansion valve 4
The pressure _P3 of c is the discharge side pressure of the evaporation pressure controller 6.
When a pressure higher than P ₂ is reached, the valve opening of the expansion valve 4 is throttled to an appropriate opening.

Next, the operation of the evaporation pressure control device of the present invention having the above configuration will be explained.

First, the refrigerant gas compressed by the compressor 2 is condensed by the condenser 1 and stored in the receiver 3 as a refrigerant liquid. Then, the valve opening degree of the expansion valve 4 is determined by the three-way switching valve 11 and the pressure equalization pipe 10 connected to the temperature sensing tube 8 and the evaporation pressure controller 6, and the refrigerant liquid flows into the expansion valve 4. The liquid expands adiabatically and becomes atomized. Furthermore, this atomized refrigerant is evaporated in the evaporator 5, and the air that has exchanged heat with the refrigerant is cooled.

At this time, the evaporator 5 is controlled by the evaporating pressure controller 6.
The internal pressure is controlled to prevent the temperature of the fins and tube wall of the evaporator 5 from dropping below the freezing point and freezing.

Next, the operation of the three-way switching valve 11 will be explained in detail.

For example, when a clutch (not shown) is turned on when the heat load is high, the pilot valve and main valve (not shown) of the evaporation pressure controller 6 are nearly fully open, allowing a large amount of refrigerant to flow.

At this time, the pressure on the suction side 6a of the evaporation pressure controller 6
Since the pressure difference ΔP _c between P ₁ and the pressure P ₂ on the discharge side 6b is less than a predetermined value (P ₁ −P ₂ <ΔP _c ), as shown in FIG. is shut off and the discharge port 11b and the pressure equalization port 11c are in communication with each other, the discharge side pressure _P2 is transmitted to the pressure equalization pipe 10 of the expansion valve 4, and the cool-down performance is maintained as before. Ru.

On the other hand, the suction side pressure _P1 of the evaporation pressure controller 6 at low heat load and especially at high rotation is the lowest pressure (2.1Kg/cm ² G)
At the same time, the pressure difference ΔP _c with the discharge side pressure P ₂ of the evaporation pressure controller 6 is maintained at a predetermined value or more (P ₁ −
When P ₂ > ΔP _c ), the three-way switching valve 11 switches to the second switching mode, as shown in FIG. state, the suction side pressure _P1 , which is higher than the discharge side pressure _P2 , is transmitted to the pressure equalization pipe 10, the opening degree of the expansion valve 4 becomes smaller, and the superheat (heating degree) is maintained constant. Therefore, the liquid back is improved.

(Effects of the invention) As described above, the present invention condenses the refrigerant gas compressed by the compressor in the condenser and stores it in the liquid receiver as refrigerant liquid. The atomized refrigerant is allowed to flow into an expansion valve whose opening degree is determined by the pressure and is adiabatically expanded to form an atomized state, and then evaporated in an evaporator. In a refrigeration cycle in which suction is fed into the compressor again via a pressure controller, an outlet of a pressure equalizing pipe connecting the evaporation pressure controller and the expansion valve is connected to the suction side and the discharge side of the evaporation pressure controller. are provided in the middle of the pressure equalization pipe, and transmit the pressure on the discharge side of the evaporation pressure controller to the pressure equalization pipe when the pressure difference between the suction side and the discharge side of the evaporation pressure controller is less than a predetermined value; The present invention is characterized in that a three-way switching valve is provided which operates to transmit the suction side pressure higher than the discharge side pressure to the pressure equalizing pipe when the pressure difference is greater than a predetermined value.

Therefore, the refrigerant flow rate can be controlled so that the refrigerant on the discharge side of the evaporator has a constant heating degree, and it is possible to prevent adverse effects such as liquid back from acting on the compressor, and to reduce the consumption of the compressor. This has the effect that power can be significantly reduced and a refrigeration cycle with high operating efficiency can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a block diagram of a refrigeration cycle equipped with an evaporation pressure control device according to the present invention, and FIGS. 2 and 3 are explanatory diagrams of the operation of a three-way switching valve in the device. It is. 1...Condenser, 2...Compressor, 3...Liquid receiver,
4... Expansion valve, 5... Evaporator, 6... Evaporation pressure controller, 6a... Suction side, 6b... Discharge side, 8...
Temperature sensing tube, 10...Pressure equalization pipe, 11...Three-way switching valve, _P1 ...Suction side pressure, _P2 ...Discharge side pressure, ΔP _c
...Pressure difference, P ₃ ...Pressure at pressure equalization port.

Claims (1)

[Scope of utility model registration request] Refrigerant gas compressed by a compressor is condensed in a condenser and stored as refrigerant liquid in a liquid receiver, and this refrigerant liquid is transferred to an expansion valve whose valve opening degree is determined by the sensed temperature of a temperature-sensitive cylinder and the pressure of a pressure equalization pipe. After the atomized refrigerant is evaporated in an evaporator, it is sucked into the compressor again via an evaporation pressure controller for freezing prevention of the evaporator. In the refrigeration cycle, an outlet of the pressure equalization pipe connecting the evaporation pressure controller and the expansion valve is provided on the suction side and the discharge side of the evaporation pressure controller, respectively. When the pressure difference between the suction side and the discharge side of the pressure controller is less than a predetermined value, the discharge side pressure of this evaporation pressure controller is transmitted to the pressure equalization pipe, and when the pressure difference is more than a predetermined value, the discharge side pressure is transmitted to the pressure equalization pipe. An evaporation pressure control device for a refrigeration cycle, comprising a three-way switching valve that operates to transmit the high suction side pressure to the pressure equalization pipe.