JPH05203291A - Refrigeration cycle - Google Patents

Abstract

PURPOSE:To operate a vaporizer effectively and enhance its cycle efficiency by controlling the dryness of refrigerant at the inlet of the vaporizer so as to minimize the dryness. CONSTITUTION:In a dryness control valve 16 installed on the down stream side of an indoor vaporizer the opening of a throttling section 16a of the valve in controlled by the balance between the pressure (pressure corresponding to the temperature of refrigerant at the outlet of the indoor vaporizer) inside a heat sensing bulb 16h acting on the upper side of a diaphragm 16c, the pressure on the lower pressure side on the down stream of the throttling section 16a acting on the lower side of the diaphragm 16c and a spring force of an adjustable spring 16g. More specifically, the refrigerant condensed and liquefied in the indoor vaporizer is cooled in a subcooled state to a saturated temperature corresponding to the total pressure of the lower pressure on the down stream side of the throttling section 16a of the dryness control valve 16 and the spring force of the adjustable spring 16g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating cycle used for an air conditioner for a vehicle and the like, and more particularly to controlling the dryness of a refrigerant at an evaporator inlet.

[0002]

2. Description of the Related Art In a refrigeration cycle, the efficiency of the evaporator can be improved and the cooling capacity can be improved by reducing the dryness of the refrigerant at the inlet of the evaporator. The dryness of the refrigerant at the inlet of the evaporator will be described with reference to the receiver cycle shown in FIGS. 4 and 5. FIG. 4 is a known refrigeration cycle in which a compressor 100, a condenser 101, a receiver 102, an expansion valve 103, and an evaporator 104 are annularly connected, and the state points (a to d) of the refrigerant on the cycle are shown. 5 is shown in the Mollier diagram. In this case, the dryness x at the evaporator inlet is the gas-liquid weight flow rate ratio at the point c depressurized by the expansion valve at a certain high pressure (Pb) and low pressure (Pc), and the point b after condensation (subcool = 0. ) Is determined by the state.

Therefore, conventionally, as a method of changing the dryness at the point c, the subcool at the point b is changed as follows. A subcool heat exchanger is installed downstream of the receiver to obtain a subcool. A throttle is provided upstream of the receiver to give a subcool inside the condenser. A throttle such as a capillary tube is provided as a depressurizing means of the accumulator cycle so that a subcool is provided in the condenser. A subcool is obtained by providing a subcool control valve 200 (see Japanese Patent Laid-Open No. 56-151858) shown in FIG. 6 in place of the above capillary tube. In addition, the subcool control valve 200 is installed in the diaphragm 201.
A valve body 203 that opens and closes the throttle portion 202 in conjunction with
This displacement of the valve element 203 is caused by the pressure inside the temperature sensing cylinder 204 acting on the upper side of the diaphragm 201 and the diaphragm 201.
It is adjusted by the balance between the high pressure acting on the lower side and the spring force of the adjustment spring 205, and the opening of the throttle portion 202 is determined by the displacement of the valve body 203.

[0004]

In the above method, however, the dryness of the evaporator inlet changes, but these are all the consequences of controlling the subcool. For example, the subcool control valve 200 detects the refrigerant temperature and pressure at the valve inlet (high pressure side), and has the subcool for the saturation temperature of the pressure corresponding to the spring force of the adjusting spring 205 so as to have the subcool. The opening is controlled. Therefore, in the Mollier diagram shown in FIG. 7 (accumulator cycle using the subcool control valve 200), when the high pressure rises from Pb to Pb1, the cycle is from abcd to a1.
b1 c1 d, and the dryness changes from x to x1.

Further, as shown in FIG. 8, the low pressure is Pc.
When changing from Pc2 to Pc2, the cycle changes from abcd to a2 bc2 d2, and the dryness changes from x to x2. In this way, the dryness x changes (increases) as the high pressure or the low pressure changes. In particular, in the heat pump cycle, it is necessary to control the inlet refrigerant dryness of the evaporator, which is the heat exchanger on the heat absorption side, to be constantly small.If the dryness is large as described above, the efficiency of the evaporator is reduced and the pressure is reduced. The loss also increases, and the cycle efficiency (COP) deteriorates significantly. The present invention has been made based on the above circumstances, and an object thereof is to control the dryness of the refrigerant at the inlet of the evaporator to be small, thereby effectively operating the evaporator and improving cycle efficiency. ..

[0006]

In order to achieve the above object, the present invention provides a pressure reducing means provided downstream of a refrigerant condenser for controlling the flow rate of the refrigerant flowing out from the refrigerant condenser to expand the pressure reduction. In the provided refrigeration cycle, the decompression means includes a throttle portion that throttles a refrigerant flow rate, a valve body that opens and closes the throttle portion, and a biasing means that biases the valve body in a direction of increasing the opening degree of the throttle portion. And a temperature sensitive portion for converting a temperature change of the refrigerant flowing out of the refrigerant condenser into a pressure change, the pressure of the temperature sensitive portion being a low pressure side pressure downstream of the throttle portion and a biasing force of the biasing means. It is adopted as a technical means that the valve body is displaced so as to be balanced with the total pressure to adjust the opening degree of the throttle portion.

[0007]

In the refrigeration cycle of the present invention having the above structure, the valve body is displaced to a position where the pressure of the temperature sensing portion and the total pressure of the low pressure side pressure and the biasing force of the biasing means are balanced. And
The opening degree of the throttle portion is adjusted according to the position of the valve body, and the flow rate of the refrigerant passing through the throttle portion is controlled. Therefore, the refrigerant condensed and liquefied in the refrigerant condenser has a supercooling degree up to the saturation temperature corresponding to the total pressure of the low-pressure side pressure downstream of the throttle portion and the urging force of the urging means, and the downstream of the throttle portion. The degree of dryness of the refrigerant is adjusted to a predetermined value determined based on the urging force of the urging means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a vehicle air conditioner using the refrigeration cycle of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a vehicle air conditioner.
This vehicle air conditioner is installed in an electric vehicle, and includes a duct 1 for guiding blown air into the vehicle compartment, a blower 2 for generating an air flow toward the vehicle interior in the duct 1, and an accumulator type. A refrigeration cycle 3 is provided.
The duct 1 is provided with an inside air introduction port 4 and an outside air introduction port 5 for introducing air into the duct 1 at the upstream end thereof, and the introduction amounts of the respective introduction ports 4 and 5 are adjusted by the inside / outside air switching damper 6. It The downstream end of the duct 1 is a DEF outlet 7 that discharges blast air toward the window glass of the vehicle, and a VEN that discharges blast air toward the upper body of the occupant.
The T outlet 8 and the FOOT outlet 9 that discharges the blast air toward the vicinity of the feet of the occupant are communicated with each other, and the respective outlets 7 to 9 are
It is switched by the blower outlet switching dampers 10, 11, 12 which operate according to the selected blower outlet mode.

The refrigeration cycle 3 is arranged in the refrigerant compressor 14 driven by the electric motor 13 and the duct 1.
An indoor condenser 15 (refrigerant condenser of the present invention) that condenses and liquefies the high-temperature and high-pressure refrigerant compressed by the refrigerant compressor 14, a dryness control valve 16 (described below) that is a decompression means of the present invention, and this dryness The indoor evaporator 17 and the outdoor evaporator 18 that evaporate the refrigerant decompressed and expanded by the temperature control valve 16 and the accumulator 19 that guides only the gas-phase refrigerant to the refrigerant compressor 14 are provided with the refrigerant pipe 20 to form an annular shape. It is connected to the. The indoor evaporator 17 is arranged in the duct 1 on the upstream side of the indoor condenser 15 in the air direction, and performs heat exchange between the refrigerant decompressed and expanded by the dryness control valve 16 and the blast air flowing in the duct 1. The outdoor evaporator 18 is arranged outside the duct 1 and exchanges heat between the refrigerant introduced from the indoor evaporator 17 and the outdoor air.

As shown in FIG. 2, the dryness control valve 16 has a valve body 16b having a throttle portion 16a, a diaphragm 16c provided on the valve body 16b, and a displacement of the diaphragm 16c. An adjustment spring 16g (of the present invention) that biases the valve body 16d in a direction in which the opening degree of the throttle portion 16a increases (upward in FIG. 2) via the valve body 16d that opens and closes the throttle portion 16a, the pin 16e, and the spring guide 16f. Urging means), a temperature sensing cylinder 16h (temperature sensing part of the present invention) that detects the temperature of the refrigerant upstream of the throttle part 16a (the temperature of the refrigerant exiting the indoor condenser 15) and converts the temperature change into a pressure change. It is composed of The valve body 16b includes an indoor condenser 1
5, an inlet port 16i connected to the outlet of 5 and an outlet port 16j connected to the inlet of the indoor evaporator 17 are attached.
It is communicated through.

The temperature sensitive cylinder 16h is filled with a gas refrigerant and is in contact with the outlet side refrigerant pipe 20 of the indoor condenser 15. The temperature sensitive cylinder 16h converts a temperature change of the refrigerant flowing through the refrigerant pipe 20 into a pressure change. , To the upper side of the diaphragm 16c via the capillary tube 16k. The communication hole 1 provided in the valve body 16b is provided below the diaphragm 16c.
The pressure downstream of the throttle portion 16a is applied through 6l. The valve element 16d has a structure in which the pressure inside the temperature sensitive tube 16h acting on the upper side of the diaphragm 16c and the diaphragm 16
The pressure on the low pressure side downstream of the throttle portion 16a acting on the lower side of c is displaced to a position where the spring force of the adjusting spring 16g is balanced, and the opening of the throttle portion 16a is determined by the displacement of the valve body 16d. The spring force of the adjusting spring 16g is adjusted by the adjusting screw 16n screwed to the hitching 16m attached to the lower portion of the valve body 16b. The spring guide 16f is provided with a communication hole 16o,
High-pressure side pressure is introduced into the spring accommodating chamber 16p through the communication hole 16o to cancel the influence of the high-pressure side pressure applied to the spring guide 16f.

Next, the operation of this embodiment will be described with reference to the Mollier diagram shown in FIG. The Mollier diagram of FIG. 3 shows the state points of the refrigerant in the refrigeration cycle 3 of FIG. The high-temperature, high-pressure gas-phase refrigerant (point in FIG. 3a) discharged from the refrigerant compressor 14 is condensed and liquefied in the indoor condenser 15 (point in FIG. 3b) and then decompressed when passing through the dryness control valve 16. (Fig. 3c point). The depressurized refrigerant is evaporated by heat exchange with air in the indoor evaporator 17 and the outdoor evaporator 18 (point in FIG. 3d), and is sucked into the refrigerant compressor 14 via the accumulator 19. On the other hand, the air introduced into the duct 1 by the operation of the blower 2 is
After being cooled by 7 and dehumidified, it is heated when passing through the indoor condenser 15 and is discharged into the vehicle interior from the selected outlets 7 to 9, thereby performing dehumidification heating of the vehicle interior.

In this operation, the dryness control valve 16 is
The flow rate is controlled so that the pressure in the temperature sensitive cylinder 16h balances with the pressure obtained by adding the spring force Fk of the adjusting spring 16g to the pressure on the low pressure side downstream of the throttle portion 16a. That is, the dryness control valve 1
6 The valve body 16d is closed until the temperature of the refrigerant on the upstream side has a sub-cooling up to the saturation temperature corresponding to the pressure obtained by adding the spring force Fk to the pressure on the downstream side of the dryness control valve 16, and further upstream of the dryness control valve 16 When the refrigerant is cooled, the valve body 16d is opened. As a result, the refrigerant condensed and liquefied in the indoor condenser 15 subcools to a saturation temperature corresponding to the total pressure of the pressure on the low pressure side downstream of the throttle portion 16a of the dryness control valve 16 and the spring force Fk of the adjusting spring 16g. I will have. Therefore, now
Considering the case where the high pressure rises from Pb to Pb1, the degree of refrigerant dryness at the inlet of the indoor evaporator 17 changes because the degree of supercooling is conventionally controlled to be constant (see FIG. 7).
However, in this embodiment, the cycle abcd is the cycle a1 b
1 cd, the degree of supercooling becomes large, and the indoor evaporator 1
The dryness x of the refrigerant at the 7th inlet does not change.

When the low pressure decreases from Pc to Pc2, the refrigerant condensed and liquefied in the indoor condenser 15 is supercooled to a saturation temperature corresponding to the total pressure of the low pressure Pc2 and the spring force Fk. Therefore, the cycle abcd becomes the cycle a2 b2 c2 d2, and the dryness of the refrigerant at the inlet of the indoor evaporator 17 becomes x2. In this low pressure region (Pc to Pc2),
As shown in FIG. 3, the dryness line is almost proportional to the pressure on the Mollier diagram. Therefore, the dryness of the refrigerant at the inlet of the indoor evaporator 17 can be practically considered to be x = x2. As a result, by using the dryness control valve 16 of the present embodiment, the dryness of the refrigerant at the inlet of the indoor evaporator 17 can be controlled to a predetermined value regardless of the change in the high pressure or the low pressure.

[0015]

According to the refrigeration cycle of the present invention, the dryness of the refrigerant at the evaporator inlet can be controlled to be small at all times regardless of the change in the high pressure or the low pressure. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a vehicle air conditioner.

FIG. 2 is a sectional view of a dryness control valve.

FIG. 3 is a Mollier diagram showing the state points of the refrigeration cycle.

FIG. 4 is a receiver cycle diagram according to the prior art.

5 is a Mollier diagram showing the state points of the refrigerant on the cycle shown in FIG.

FIG. 6 is a configuration diagram of a subcool control valve.

FIG. 7 is a Mollier diagram for explaining the conventional technique.

FIG. 8 is a Mollier diagram illustrating a conventional technique.

[Explanation of symbols]

 3 Refrigeration cycle 15 Indoor condenser (refrigerant condenser) 16 Dryness control valve (pressure reducing means) 16h Temperature sensing tube (temperature sensing portion) 16a Throttling portion 16d Valve body 16g Adjustment spring (biasing means)

Front page continuation (72) Inventor Keita Honda 1-1, Showa-cho, Kariya city, Aichi prefecture

Claims (1)

[Claims] 1. A refrigeration cycle comprising a decompression means provided downstream of a refrigerant condenser for controlling and decompressing and expanding a refrigerant flow rate flowing out from the refrigerant condenser, wherein the decompression means restricts a refrigerant flow rate. Section, a valve body that opens and closes the throttle section, an urging means that urges the valve element in a direction of increasing the opening degree of the throttle section, and a pressure change that changes the temperature of the refrigerant flowing out from the refrigerant condenser. A temperature-sensing section for converting the valve body to a pressure-sensing section so that the pressure of the temperature-sensing section is balanced with the total pressure of the low pressure side downstream of the throttle section and the biasing force of the biasing means. A refrigeration cycle characterized by being configured to adjust the opening degree of the refrigeration cycle.