JPH02203175A - Refrigerator - Google Patents

Abstract

PURPOSE:To control not only the superheating at the outlet of an evaporator but also the circulating amount of refrigerant liquid to a compressor, and to suppress the superheating of refrigerant to be input to the compressor by providing a sub-spring for biasing a throttle valve in an opening direction in addition to a main spring for energizing the valve toward an interrupting direction, and using nonazeotropic mixture refrigerant as the refrigerant. CONSTITUTION:A refrigerator 21 has a controller 29 for sufficiently performing a function as an air conditioner and holding in a compartment comfortable state. A compression coil spring 31 (sub spring) for energizing a throttle valve 11 reversely to a compression coil spring 13 (main spring) is engaged with a push rod 12 above the valve 11, and supported by a spring seat 32 secured to the rod 12 and the main body 2 of an expansion unit 1A. In the refrigerator 21, nonazeotropic mixture refrigerant is used, and the same nonazeotropic mixture refrigerant is sealed in a temperature sensing cylinder 14 disposed in the outlet of an evaporator 27. A compression coil spring 31 is disposed oppositely to the spring 13, and because the nonazeotropic mixture refrigerant is employed, the elastic forces of both the springs 13, 31 are suitably set to stably control refrigerant circulating liquid quantity.

Description

[Detailed description of the invention] Star! TECHNICAL FIELD The present invention relates to a vapor compression type refrigeration system, and particularly to a refrigeration system suitably used in an automobile air conditioner.

Conventional Art and Problems to be Solved by the Invention A vapor compression refrigeration system is mainly composed of a compressor, a condenser, an expander, and an evaporator, and the refrigerant is distributed in the following order: It flows through a mechanical circulation path (refrigeration cycle). Conventionally, in refrigeration systems used in automobile air conditioners, etc., in order to protect the compressor, a degree of superheating (SH) is applied to prevent liquid refrigerant from flowing into the compressor at the inlet of the compressor. , the completely gaseous refrigerant is returned to the compressor. However, as in automotive air conditioners, the compressor is located far from the evaporator, and the superheat detection device is installed at the evaporator outlet rather than the compressor inlet, and the piping from the evaporator outlet is connected to the high ambient temperature zone (engine room). If the gas refrigerant flows through the compressor, the degree of superheat of the gas refrigerant flowing into the compressor becomes too high. As a result, the temperature of the refrigerant after compression exceeds, for example, 120°C, causing deterioration of rubber hoses, refrigerating machine oil, etc. Therefore, it would be better to reduce the degree of superheat (SH) at the outlet of the evaporator, but with conventionally used refrigerants and expansion valves, when the degree of superheat (SH) = 0, the refrigerant liquid returns to the compressor. In reality, the amount of reflux liquid may become excessive because the reflux amount cannot be controlled, and it is necessary to ensure a degree of superheat (SH) at the outlet of the evaporator.

Hereinafter, problems with such prior art will be explained with reference to the drawings.

FIG. 8 shows a conventional expander 1. The expander 1 includes a diaphragm 3 and a head cover 4 that presses the diaphragm 3 at one open end of the main body 2, and has a first diaphragm chamber 5 and a second diaphragm chamber 6 separated by the diaphragm 3. A throttle valve 11 that opens and closes the refrigerant passage 7 between an inlet 8 and an outlet 9 formed across the refrigerant passage 7 and is connected to the diaphragm 3 via a presser rod 12; It is equipped with a compression coil spring 13 that biases 11 in the blocking direction.

Further, on the downstream side of the throttle valve 11, the refrigerant passage 7 is connected to the second diaphragm chamber 6 via the bypass passage 10, and the first diaphragm chamber 5 has a heat-sensitive The tubes 14 are connected to each other via a capillary tube 15. The heat-sensitive tube 14 is filled with the same refrigerant used in the refrigeration cycle.

In the above configuration, a condenser (not shown)
When the high-temperature, high-pressure liquid refrigerant that enters the refrigerant passage 7 from the side passes through the throttle section (orifice) defined by the throttle valve 11, it rapidly expands and becomes a low-temperature, low-pressure mist refrigerant. It enters the evaporator through outlet 9. The amount of refrigerant flowing into the evaporator is regulated by the opening degree of the throttle valve 11. If a certain amount of refrigerant is flowing and the ambient temperature surrounding the evaporator rises, the refrigerant will evaporate quickly and the evaporator will The temperature at the outlet increases, the gas in the heat-sensitive tube 14 expands, the pressure P in the first diaphragm chamber 5 increases, and the diaphragm 3 is pushed.
Therefore, the throttle valve 11 is pushed down against the elastic force of the compression coil spring 13, and the flow rate of the refrigerant increases.

In such a device, the pressure in the second diaphragm chamber 6 is PL relative to the pressure P in the first diaphragm chamber 5.

When the pressure applied to the diaphragm 3 by the compression coil spring 13 is PS, the pressure P0 inside the heat-sensitive cylinder 14 is
Control is performed at the temperature inside the heat-sensitive cylinder 14 (evaporator outlet temperature) that satisfies the relational expression P = p, + p8. The degree of superheat (SH) when controlling in the range of degree of superheat (SH) > O is shown in a refrigeration cycle (single stage) in a T-s diagram (T is absolute temperature and S is entropy). What is shown is FIG. However, the degree of superheating (SH
) = 0, the evaporator outlet temperature is within the saturation temperature (Ts constant) range, as shown in Figure 10, so it becomes impossible to control the refrigerant flow rate based on the temperature difference. .

The present invention was created against this technical background, and in a refrigeration system, it controls not only the degree of superheating at the outlet of the evaporator but also the amount of refrigerant liquid returned to the compressor, thereby controlling the superheating of the refrigerant flowing into the compressor. The purpose is to keep the degree low.

This is achieved by

The objective is to provide a refrigeration system comprising a compressor, a condenser, an expander and an evaporator, the expander comprising a diaphragm and a first diaphragm chamber and a second diaphragm chamber separated by the diaphragm. a diaphragm chamber, a refrigerant passage communicating between a refrigerant inlet and a refrigerant outlet, a throttle valve that opens and closes the refrigerant passage and blocks it, a spring body that biases the throttle valve in the blocking direction, and a second diaphragm chamber side The refrigerant passage on the downstream side of the throttle part is in communication with the second diaphragm chamber inside or outside the expander, and the diaphragm and the throttle valve are connected to each other. In a refrigeration system in which a heat-sensitive cylinder disposed in a section and a first diaphragm chamber communicate with each other, and the same refrigerant as the above-mentioned refrigerant is sealed in the heat-sensitive cylinder, the upper spring body biases the throttle valve in the shutoff direction. other,
An auxiliary spring body is provided to bias the throttle valve in the opening direction, and a non-azeotropic mixed refrigerant is used as the refrigerant. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a refrigeration system (refrigeration cycle) for an air conditioner located at the front of an automobile body. In the figure,
Reference numeral 20 denotes an engine, in which a compressor 22 of a refrigeration system 21 is driven in conjunction with the crankshaft of the engine 20, and the high temperature refrigerant gas discharged from the compressor 22 is passed through a pipe 23. After that, it reaches the condenser 24, and the engine 20
It is air-cooled by a cooling fan and liquefied, becomes a high-pressure liquid, and is temporarily stored in a liquid receiver 25 via a pipe 23A.Then, the liquid passes through a pipe 26 to an expander 1A, and the pressure drops through the expander 1A. It flows into the evaporator 27. The refrigerant that has become a gas in the evaporator 27 is sucked into the compressor 22 through a pipe 28, and then similarly circulated through the refrigeration cycle.

FIG. 2 schematically shows the refrigeration device 21. The refrigeration system 21 is equipped with a control device 29 that fully functions as an air conditioner and keeps the interior of the vehicle in a comfortable state. In the figure, 30 indicates a pressure sensor connected to the outlet piping of the liquid receiver 25.

FIG. 3 shows the internal structure of the expander 1A.

Since most of the structure of the expander 1A is the same as that of the expander 1 described above, the same reference numerals are used for the same members and the explanation thereof will be omitted. The differences from expander 1 are as follows:
A compression coil spring 31 (secondary spring body) that biases the throttle valve 11 in the opposite direction to the compression coil spring 13 (main spring body) is fitted onto the presser rod 12 above the throttle valve 11. The main body 2 of the expander 1A is supported by a spring seat 32 fixed to the main body 2 of the expander 1A.

In the refrigeration system 21, a non-azeotropic mixture refrigerant whose evaporation temperature changes even in a saturated gas-liquid state is used. A refrigerant, its main refrigerant, or a single refrigerant (or an azeotropic refrigerant mixture) having vapor pressure characteristics close to those of the non-azeotropic refrigerant mixture is sealed. Figure 4 shows the characteristics of the non-azeotropic refrigerant mixture. The figure shows the mixing ratio of refrigerants (A) and (B) on the horizontal axis and the temperature on the vertical axis, and shows the temperature characteristics of the non-azeotropic mixed refrigerant when the pressure (P) is kept constant. The curve line indicates a saturated liquid line, the curve II indicates a saturated vapor line, T indicates the boiling point of the refrigerant (A), and T2 indicates the boiling point of the refrigerant (B). Refrigerant (A), (B)
When the non-azeotropic mixed refrigerant mixed in an appropriate proportion evaporates in the evaporator 27, it gradually evaporates from the low boiling point refrigerant (A), and finally the high boiling point refrigerant (B). (T-s
(Diagram) As shown in the figure, evaporation occurs as the temperature increases from the inlet to the outlet of the evaporator 27 (see line III). In this figure, the degree of superheat (SH)>0.

Here, in order to make the degree of superheat (SH) > 0, the pressure applied to the diaphragm 3 by the compression coil spring 13 (main spring body) is Ps□, and the pressure applied to the diaphragm 3 by the compression coil spring 31 (secondary spring body) is When Ps□ (applying a force to the diaphragm 3 in the same direction as the pressure P0 in the first diaphragm chamber 5), the following formula (% formula %) is given: where T8 indicates the saturation temperature and TM indicates the evaporator outlet temperature.) The relationship between the spring pressures PS□ and PS□ may be set so as to satisfy the following. The spring pressure PS2 of the compression coil spring 13 is determined by rotating the adjustment rod 17 after removing the cap 16 from the main body, and forming a spring seat 18 integral with the adjustment rod 17 on the inner peripheral surface of the cylindrical portion of the main body 2. It is adjusted by moving it along the female screw.

If P = p, the balance is established at PL = P1, so the degree of superheating (SH) becomes 0 (see Figure 7).

As contemplated by the present invention, in order to make the degree of superheat (SH) < 0, the relationship between the spring pressures Ps□ and PS□ may be set so as to satisfy the following formula (%) (see FIG. 7). The larger PS□ is, the more throttle valve 1
It is clear that the amount of retraction of the valve 1 increases, the valve opening increases, and the amount of refrigerant recirculated liquid can be increased. The Ts diagram in this case is as shown in FIG.

In this way, by arranging the compression coil spring 31 (secondary spring body) opposite to the compression coil spring 13 (main spring body) and using a non-azeotropic mixed refrigerant, the elasticity of both compression coil springs 13 and 31 is reduced. A bus path 10 is provided to enable stable refrigerant recirculation liquid volume control by appropriately setting the power generation, and a refrigerant path 7 and a second diaphragm chamber 6 are provided on the downstream side of the throttle valve 11.
(internal pressure equalization type); however, instead of the bypass path 10, a pipe may be provided to communicate and connect the outlet portion of the evaporator 27 and the second diaphragm chamber 6 (external pressure equalization type). It should be noted that the latter type also has a structure in which the refrigerant passage on the downstream side of the throttle portion and the second diaphragm chamber are connected in communication.

As is clear from the above description, the expander includes a diaphragm, a first diaphragm chamber and a second diaphragm chamber separated by the diaphragm, and a refrigerant passage communicating between a refrigerant inlet and a refrigerant outlet. comprising a throttle valve that opens and closes the refrigerant passage to shut off the throttle valve, a spring body that biases the throttle valve in a blocking direction, and a presser rod that is located on the second diaphragm chamber side and connects the diaphragm and the throttle valve; The refrigerant passage on the downstream side of the throttle part is in communication with the second diaphragm chamber inside or outside the expander, and the heat-sensitive tube disposed at the evaporator outlet is in communication with the first diaphragm chamber. A refrigerant having the same or similar vapor pressure characteristics as the refrigerant is sealed in a heat-sensitive cylinder, and in addition to a main spring body that biases the throttle valve in the closing direction, there is also a secondary spring body that biases the throttle valve in the opening direction. According to the present invention, there has been provided a refrigeration apparatus characterized in that a non-azeotropic mixed refrigerant is used as a refrigerant.

In this refrigeration system, the refrigerant evaporates while increasing in temperature from the inlet to the outlet of the evaporator, so the degree of superheat (SH
) < 0, and this control can be performed by using a main spring body that biases the throttle valve in the shutoff direction, as well as a
By providing an auxiliary spring body that biases the throttle valve in the opening direction, this can be easily carried out, thereby making it possible to stably control the amount of refrigerant recirculated to the compressor.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an air conditioner refrigeration system (refrigeration cycle) located at the front of an automobile body, FIG. 2 is a diagram schematically showing the refrigeration system, and FIG. 3 is a diagram showing an embodiment of the present invention. Figure 4 is a graph showing the vapor pressure characteristics of a non-azeotropic mixed refrigerant, and Figure 5 is a diagram showing the internal structure of the expander involved. Refrigeration cycle and T
-s diagram, Figure 6 shows the degree of superheat (S) using a non-azeotropic mixed refrigerant.
H) Refrigeration cycle and T-s diagram when <0, 7th
The figure is a graph showing the saturated vapor pressure characteristics of a non-azeotropic mixed refrigerant, Figure 8 is a diagram showing a known expander, and Figure 9 is a graph showing the saturated vapor pressure characteristics of a non-azeotropic mixed refrigerant. The refrigeration cycle and T-s diagram, Figure 10 shows the degree of superheat (S) using a single refrigerant.
It is a refrigeration cycle and a Ts diagram when H)<O. DESCRIPTION OF SYMBOLS 1... Expander, 2... Main body, 3... Diaphragm, 4... Head cover, 5... First diaphragm chamber, 6... Second diaphragm chamber, 7... Refrigerant passage , 8
...Inlet, 9...Exit, 10...Bypass path, 1
DESCRIPTION OF SYMBOLS 1... Throttle valve, 12... Presser rod, 13... Compression coil spring, 14... Heat sensitive tube, 15... Capillary tube, 20... Engine, 21... Refrigeration device, 2
2... Compressor, 23... Piping, 24... Condenser,
25...Liquid receiver, 26...Piping, 27...Evaporator, 28...Piping, 29...Control device, 30...Pressure sensor, 31...Compression coil spring.

Claims (3)

[Claims] (1) A refrigeration system including a compressor, a condenser, an expander, and an evaporator, wherein the expander includes a diaphragm, a first diaphragm chamber and a second diaphragm chamber separated by the diaphragm, and a refrigerant inlet. A refrigerant passage that communicates between the refrigerant outlets, a throttle valve that opens and closes the refrigerant passage and shuts it off, a spring body that biases the throttle valve in a blocking direction, and a diaphragm and the throttle valve that are located on the second diaphragm chamber side. The refrigerant passage on the downstream side of the throttle part is in communication with the second diaphragm chamber inside or outside the expander, and the heat-sensitive In a refrigeration system in which a cylinder and a first diaphragm chamber communicate with each other and a refrigerant having vapor pressure characteristics identical to or similar to the refrigerant is sealed in a heat-sensitive cylinder, the main spring body biases the throttle valve in the shutoff direction. Additionally, an auxiliary spring body is provided to bias the throttle valve in the opening direction, and
A refrigeration system characterized in that a non-azeotropic mixed refrigerant is used as the refrigerant. (2) The refrigeration system according to claim (1), wherein the refrigeration system is configured so that the degree of superheat at the outlet of the evaporator is negative. (3) In the refrigeration device according to claim (2),
The pressure exerted on the diaphragm by the main spring body is P_
S__2, the pressure applied to the diaphragm by the secondary spring body is P_S_1, and the pressure inside the first diaphragm chamber is P_
1 When the pressure inside the second diaphragm chamber is P_L, the following relational expression P_L=P_1-(P_S_2-P_S_1), P_
A refrigeration system characterized in that the spring forces of the main and auxiliary spring bodies are set so as to satisfy S_2<P_S_1, so that the degree of superheat at the outlet of the evaporator becomes negative.