JPH0979667A - Gas injection type refrigerating cycle equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a return of liquid from gas injection piping by a reliable and simple construction. SOLUTION: A control valve 6 provided for gas injection piping 5 and controlling the amount of injection of gas refrigerant is constituted of a temperature type expansion valve and a temperature-sensitive tube 68 of this temperature type expansion valve is disposed at a position located on the gas injection piping 5 and in the vicinity of a compressor 1 where it is subjected to a thermal effect of the compressor. At the time of a steady-state operation of a cycle, according to this constitution, the temperature-sensitive tube 68 senses a higher temperature than the one of saturated refrigerant gas due to the thermal effect of the compressor 1 and the temperature type expansion valve is fully opened. At a transitional time such as a starting time, on the other hand, the temperature-sensitive tube 68 senses the temperature of the saturated refrigerant gas due to mixing-in of a liquid refrigerant into the gas injection piping 5, the temperature type expansion valve is fully closed and thereby a return of the liquid refrigerant is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas injection type refrigeration cycle device which prevents liquid compression due to liquid return from a gas injection pipe, and is suitable for vehicle air conditioning.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open No. 2-37259 discloses a gas injection type refrigeration cycle in which a control valve is provided in a gas injection pipe, the control valve is closed at the time of starting the compressor, and a certain time has elapsed after the start. Then, it is proposed that the control valve is opened to prevent the liquid from returning from the gas injection pipe to prevent the liquid from being compressed in the compressor.

[0003]

However, in the refrigeration cycle, since the liquid return time to the compressor fluctuates due to fluctuations in operating conditions such as heat load at the time of starting, after the compressor is started, a simple fixed time is required. With the configuration in which the control valve is opened after the passage of time, the control valve does not always close only when the liquid return to the compressor occurs, and if the set time is too short, the If liquid return occurs and the set time is too long, there is a problem that the inefficient operation time due to the stop of gas injection becomes long.

Further, in the above-mentioned prior art, since the control valve is simply opened after a certain period of time has elapsed after the compressor has been started, when the operation mode is switched after the compressor has been started (for example, cooling and heating). It is not possible to deal with the liquid return that occurs when the capacity is changed drastically. Similarly, in the vehicle refrigeration cycle, it is not possible to deal with the liquid return that occurs when the liquid refrigerant suddenly flows out from the gas-liquid separator due to the vibration of the vehicle.

The present invention has been made in view of the above points,
An object of the present invention is to reliably prevent liquid return from a gas injection pipe in a gas injection type refrigeration cycle device with a reliable and simple configuration.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention employs the following technical means. That is, according to the invention of claim 1, in the gas injection type refrigeration cycle apparatus, a control valve (6) provided in the gas injection pipe (5) for controlling the injection amount of the gas refrigerant.
Is constituted by a temperature type expansion valve whose valve opening is adjusted according to the temperature sensed by a temperature sensing cylinder (68) arranged on the gas injection pipe (5), and the temperature sensing cylinder is operated during a steady cycle operation. (68) is characterized in that the temperature type expansion valve is fully opened by sensing a temperature higher than the temperature of the saturated refrigerant gas.

According to the second aspect of the present invention, the temperature sensitive tube (68) is provided.
On the gas injection pipe (5) and in the vicinity of the compressor affected by the heat of the compressor (1),
Due to the influence of heat from the compressor (1), the temperature sensitive tube (6
8) is characterized in that the temperature higher than the temperature of the saturated refrigerant gas is sensed. According to the invention described in claims 1 and 2, since the liquid level in the gas-liquid separator is stable at an appropriate position during the steady cycle, the refrigerant injected through the gas injection pipe is saturated gas. Is. However, since the temperature sensing tube is designed to detect a temperature higher than the temperature of the saturated gas, the temperature type expansion valve is fully opened.

As a result, the required amount of refrigerant is injected into the compressor with almost no pressure reduction of the refrigerant in the control valve (thermal expansion valve), and a normal gas injection effect can be exhibited. On the other hand, the liquid level in the gas-liquid separator may suddenly rise during a transition such as when the compressor is started or when the cooling / heating capacity is significantly changed. In such a case, not only gas but liquid will flow into the refrigerant injected into the compressor through the gas injection pipe.

As a result, the temperature sensitive tube senses a temperature close to that of the saturated gas refrigerant due to the mixing of the liquid refrigerant,
The internal pressure of the temperature sensing cylinder becomes lower than that in the steady state described above.
As a result, the valve opening degree starts to decrease from the setting of the operating characteristics of the temperature type expansion valve described above, and the valve is fully closed. This prevents the liquid refrigerant from being injected into the compressor 1 during the above-mentioned transition, and thus can prevent the reliability of the compressor 1 from being lowered due to the liquid compression.

In particular, according to the present invention, as described above, the temperature type expansion valve constituting the control valve adjusts the valve opening degree by directly judging whether or not liquid is mixed in the injected refrigerant. Therefore, it is possible to detect the mixing of the liquid and close the valve at any transition time, and therefore it is possible to reliably prevent the liquid from returning. In addition, since the control valve can be configured only by a relatively simple mechanical component having no electric circuit portion, which is a temperature type expansion valve, there is an effect that the control valve is highly reliable and can be manufactured at low cost.

Further, in the invention according to claim 2, the temperature sensing cylinder (68) uses the heat effect from the compressor as it is as a heat source for sensing a temperature higher than the temperature of the saturated refrigerant gas in a steady state. Therefore, the structure can be further simplified.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigeration cycle apparatus for air conditioning, and 1 is a compressor that compresses and discharges a refrigerant, for example, a scroll compressor, which is an electric type that is rotationally driven by an electric motor. Reference numeral 2 denotes a condenser for cooling and condensing the gas refrigerant discharged from the compressor 1, which is a cooling fan 2
It is cooled by the cooling air blown by a.

Reference numeral 3 denotes a first pressure reducer for reducing the pressure of the refrigerant discharged from the condenser 2 to an intermediate pressure, which is composed of, for example, an electric expansion valve, a capillary tube, or a fixed throttle such as an orifice. Reference numeral 4 denotes a gas-liquid separator that separates the gas-liquid of the intermediate pressure refrigerant decompressed by the first pressure reducer 3 and has a cylindrical tank shape. Reference numeral 5 is a gas injection pipe, and one end (inlet) of the gas injection pipe is open to the gas refrigerant space in the upper part of the gas-liquid separator 4 so as to introduce the gas refrigerant separated by the gas-liquid separator 4. The other end (outlet) of this gas injection pipe 5
Since the gas refrigerant is returned (injected) during the compression of the compressor 1, is opened in a portion of the compression chamber of the compressor 1 in the middle of compression.

A control valve 6 for controlling the amount of gas injection into the compressor 1 is installed in the middle of the gas injection pipe 5, and the outlet flow path portion of the gas injection pipe 5 (located in the compressor 1) Is provided with a check valve 1a for preventing the gas refrigerant in the compressor 1 from flowing back to the gas-liquid separator 4 side. Reference numeral 7 is a second pressure reducer for reducing the pressure of the liquid refrigerant separated by the gas-liquid separator 4, and is composed of, for example, an electric expansion valve or a temperature expansion valve, and the degree of superheat of the refrigerant at the outlet of the evaporator 8 has a predetermined value. The refrigerant flow rate is adjusted so that The evaporator 8 exchanges heat between the conditioned air blown by the air conditioning fan 8a and the gas-liquid two-phase refrigerant decompressed by the second decompressor 7 to evaporate the refrigerant and cool the conditioned air by the latent heat of evaporation. To do.

Reference numeral 9 denotes an air-conditioning electronic control unit, which is an inverter 1
0 to control the rotation speed of the drive motor of the compressor 1, the blower fans 2a and 8a, and the first and second pressure reducers 3 and 7.
It controls the electric expansion valve and the like constituting the above. The control valve 6, which is a feature of the present invention, is composed of a thermal expansion valve. This thermal expansion valve has a structure as shown in FIG. 2, 60 is its housing, and the valve body 6 is inside thereof.
A valve opening 62 that is opened and closed by 1 is formed. The valve body 61 is connected to a diaphragm 64 via an actuation rod 63. Above and below this diaphragm 64, the first and second
Pressure chambers 65 and 66 of the first pressure chamber 6 are formed.
The pressure P1 of the refrigerant in the temperature-sensitive cylinder 68 acts on 5 through the capillary tube 67.

The pressure P2 of the refrigerant in the gas injection pipe 5 on the downstream side of the valve port 62 acts on the second pressure chamber 66. Further, since the pressing force P3 of the coil spring 69 acts on the valve body 61, the valve opening degree of the valve body 61 is the pressure P1 acting in the valve opening direction and the pressure P2 + P3 acting in the valve closing direction. Adjusted in proportion.

The same refrigerant as in the refrigeration cycle is enclosed in the temperature sensing cylinder 68, and the temperature sensing cylinder 68 is protected from the heat effect from the compressor 1 in the vicinity of the compressor 1 in the gas injection pipe 5. The gas injection pipe 5 is provided at a receiving portion and is fixed by a suitable fixing means (not shown) such as a clamp.
Is fixedly attached. Further, the outer surface of the temperature sensitive tube 68 is covered with a heat insulating material 68a to reduce the influence of heat from the outside air.

The operating characteristic of the temperature type expansion valve is set so that the valve element 66 is fully opened when the temperature sensing cylinder 68 senses a temperature higher than the temperature of the saturated refrigerant gas. Next, the operation of the above configuration will be described. First, in the steady state of the refrigeration cycle, the high-temperature and high-pressure superheated gas refrigerant discharged from the compressor 1 flows into the condenser 2, where the refrigerant exchanges heat with the blown air of the blower fan 2a and is condensed. Next, the refrigerant flowing out of the condenser 2 is decompressed by the first decompressor 3, becomes a gas-liquid two-phase state of intermediate pressure, and flows into the gas-liquid separator 4.

Here, the refrigerant is separated into a saturated gas refrigerant and a saturated liquid refrigerant, the liquid refrigerant flows out from the outlet at the bottom of the gas-liquid separator 4, is decompressed again by the second decompressor 7, and the low-pressure gas-liquid 2 is discharged. It enters a phase state and flows into the evaporator 8. In the evaporator 8, the refrigerant absorbs heat from the air blown by the blower fan 8a and evaporates to become a gas refrigerant, which is sucked into the compressor 1 and compressed again.

On the other hand, the gas refrigerant separated by the gas-liquid separator 4 flows out from the upper part of the gas-liquid separator 4 into the gas injection pipe 5, passes through the control valve 6 and the check valve 1a, and passes through the compressor 1. It is injected into a part of the compression chamber during the compression process. At this time, when the cycle is steady, the liquid level in the gas-liquid separator 4 is stable at an appropriate position, so that the refrigerant injected through the gas injection pipe 5 is a saturated gas. Since the temperature sensitive tube 68 is covered with the heat insulating material 68a and is insulated from the outside air, it is necessary to sense a temperature higher than the temperature of the saturated gas under the influence of heat (heat conduction) from the compressor 1. become.

Here, the operating characteristic of the temperature type expansion valve constituting the control valve 6 is set so that the valve body 61 is fully opened when the temperature sensing cylinder 68 senses a temperature higher than the temperature of the saturated refrigerant gas. Therefore, the valve body 61 is in a fully opened state. In the fully opened state of the valve body 61, the opening area of the valve opening 62 is set to be an opening area commensurate with the required injection amount. Therefore, the refrigerant is hardly decompressed in the control valve 6, and the required injection amount The refrigerant is injected into the compressor 1.

On the other hand, the liquid level in the gas-liquid separator 4 may suddenly rise during a transition such as when the compressor is started or when the cooling and heating capacity is significantly changed. In such a case, not only gas but liquid will flow into the refrigerant injected into the compressor 1 through the gas injection pipe 5. As a result, the temperature-sensitive cylinder 68 senses a temperature close to the temperature of the saturated gas refrigerant due to the mixing of the liquid refrigerant even if it is affected by the heat from the compressor 1, and the internal pressure P1 of the temperature-sensitive cylinder 68 is , Which is lower than the above-mentioned steady state. As a result, the opening degree of the valve body 61 starts to decrease from the setting of the operating characteristics of the temperature type expansion valve described above, and the valve body 61 is fully closed.

This makes it possible to prevent the liquid refrigerant from being injected into the compressor 1 during the above-mentioned transition, so that it is possible to prevent the reliability of the compressor 1 from being lowered due to the liquid compression. In particular, the thermal expansion valve that constitutes the control valve 6 is
As described above, since the opening degree of the valve body 61 is adjusted by directly judging whether or not the liquid is mixed in the injected refrigerant, it is possible to detect the liquid mixing in any transient time. It is possible to close the valve, and thus to reliably prevent liquid return.

Although a normal refrigeration cycle in which the refrigerant flow is not reversed has been described in FIG. 1 in order to briefly show the features of the present invention, a heat pump cycle in which the refrigerant flow is reversed, for example, for a heat pump cycle for air conditioning of an electric vehicle. Of course, the present invention can be applied. In this case, the heat pump cycle may be a heat pump cycle capable of setting many operation modes such as dehumidifying function in addition to cooling and heating.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram showing an embodiment of the present invention.

2 is a cross-sectional view showing an outline of a thermal expansion valve that constitutes a control valve 6 in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Condenser, 3 ... 1st decompressor, 4 ... Gas-liquid separator, 5 ... Gas injection piping, 6 ... Control valve (temperature type expansion valve), 7 ... 2nd decompressor, 8 ... Evaporator, 61 ... Valve body, 62 ... Valve mouth, 68 ... Temperature sensitive tube.

Claims (2)

[Claims] A compressor for compressing and discharging a refrigerant (1)
A condenser (2) for cooling and condensing the gas refrigerant discharged from the compressor (1), and a first pressure reducer (3) for depressurizing the refrigerant discharged from the condenser (2) to an intermediate pressure. , A gas-liquid separator (4) for separating the gas-liquid of the intermediate pressure refrigerant decompressed by the first pressure reducer (3) and the gas refrigerant separated by the gas-liquid separator (4) into the compressor ( 1) a gas injection pipe (5) for returning to the middle of compression, a second pressure reducer (7) for reducing the pressure of the liquid refrigerant separated by the gas-liquid separator (4), and a second pressure reducer (7) A gas injection type refrigeration cycle device comprising: an evaporator (8) for evaporating a decompressed refrigerant, wherein the gas injection pipe (5) controls an injection amount of a gas refrigerant to be returned to the middle of compression of the compressor (1). A control valve (6) for The temperature-sensing cylinder (68) arranged on the gas injection pipe (5) has a valve opening adjusted according to the temperature sensed by the temperature-sensing cylinder (68). 6
8) The gas injection type refrigeration cycle apparatus, wherein the temperature type expansion valve is fully opened by sensing a temperature higher than the temperature of the saturated refrigerant gas. 2. The temperature sensing cylinder (68) is arranged on the gas injection pipe (5) and in the vicinity of the compressor affected by the heat of the compressor (1). 2. The gas injection type refrigeration cycle apparatus according to claim 1, wherein the temperature sensing cylinder (68) senses a temperature higher than the temperature of the saturated refrigerant gas due to the heat effect from (1).