JPS633154A - Refrigeration cycle device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a refrigeration cycle device having an electric expansion valve, and is suitable for use in, for example, an automobile air conditioner.

[Conventional technology]

As seen in Japanese Unexamined Patent Publication No. 60'-1485, a system has been proposed in which the flow rate of refrigerant in a refrigeration cycle is controlled by a proportional control type electric expansion valve. However, in such a proportional control electric expansion valve, the amount of lift is controlled by a small amount to adjust the flow rate, so in order to actually operate in a refrigeration cycle, the frictional force acting on the valve body must be reduced. In other words, it is necessary to take measures to reduce hysteresis, which inevitably requires a precise structure and is expensive.

Therefore, instead of controlling the lift amount of the valve body, the refrigerant flow rate is controlled by moving the valve body through its entire stroke and controlling the ratio of the valve opening time to the valve closing time, that is, the duty ratio. Something has also been proposed. According to this method, the above problem can be solved.

[Problem that the invention seeks to solve]

However, according to experimental research by the present inventors, in the latter case, the high-pressure refrigerant on the upstream side of the valve is in a liquid state, so the pressure rises rapidly the moment the valve is closed, and this pressure rise There is a problem in that it occurs intermittently due to repeated opening and closing, causing piping vibration.

Therefore, an object of the present invention is to reduce vibrations of high-pressure refrigerant piping upstream of the electric expansion valve caused by duty control in a refrigeration cycle apparatus using a duty-controlled electric expansion valve.

[Means for solving problems]

In order to achieve the above object, the present invention adopts a technical means of providing an auxiliary source pressure system π for reducing the pressure of the high-pressure side liquid refrigerant into a gas-liquid two-phase state on the upstream side of a duty-controlled electric expansion valve. .

[Operation] According to the above technical means, not only liquid refrigerant but also gaseous refrigerant is present upstream of the electric expansion valve.
Since the gas refrigerant is compressible, the presence of the gas refrigerant can significantly reduce the sudden pressure rise that occurs at the moment the valve body of the electric expansion valve closes.

〔Effect of the invention〕

Therefore, in the present invention, vibrations in the high-pressure refrigerant piping caused by duty control can be favorably reduced with an extremely simple configuration in which an auxiliary pressure reducing device is additionally installed.

〔Example〕

The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a refrigeration cycle device for automobile air conditioning. In the figure, a compressor 10 is driven by an automobile running engine 12 via an electromagnetic clutch 11. A condenser 13 is connected to the discharge side of the compressor 10, and the condenser 13 cools the gas refrigerant discharged from the compressor 10 with cooling air blown by a cooling fan 14 to perform pseudo-condensation. The cooling fan 14 is driven by a motor 14a.

On the downstream side of the condenser 13, there is a receiver 15 that stores liquid refrigerant.
is connected thereto, and further connected to an electric expansion valve 16 via an orifice 19 constituting an auxiliary pressure reducing device. The expansion valve 16 is electrically duty-controlled to repeatedly open and close to adjust the flow rate of the refrigerant, and depressurizes and expands the liquid refrigerant from the receiver 15.

An evaporator 17 is connected to the downstream side of the electric expansion valve 16, and this evaporator 17 combines the gas-liquid two-phase refrigerant that has passed through the expansion valve 16 with the air inside the vehicle or outside the table room blown by the ventilation fan 18. , to evaporate the liquid refrigerant by exchanging heat. The cold air cooled by the latent heat of vaporization of the refrigerant is sent to the heater unit 24.
It blows out into the passenger compartment through the. As is well known, the heater unit 24 includes a heater core 24 that uses engine cooling water as a heat source.
1. A temperature control damper 243 and the like is built in to adjust the air volume ratio of warm air heated by passing through the heater core 241 and cold air passing through the bypass path 242 of the heater core 241 to adjust the temperature of the air blown into the vehicle interior. ing. Evaporator 17
The downstream side of is connected to the suction side of the compressor 10. A refrigerant temperature sensor 20 is installed at the inlet piping of the evaporator 17 and detects the saturated refrigerant temperature TE at the inlet of the evaporator, and is composed of a thermistor.

A refrigerant temperature sensor 21 is installed at the outlet piping of the evaporator 17 and detects the refrigerant temperatures T and l on the evaporator outlet side, and is composed of a thermistor. Both refrigerant temperature sensors 20 and 21 are installed inside the refrigerant piping to directly detect the refrigerant temperature, and one is fixed tightly to the surface of the refrigerant piping and the sensor mounting part is covered with heat insulating material to detect the piping surface temperature. Although any method may be used, the former method is advantageous in order to accurately measure the refrigerant temperature.

Reference numeral 22 designates a control circuit, which includes an input circuit 22a into which the detection signals of the sensors 20 and 21 are input, a microcomputer 22b that performs predetermined arithmetic processing based on the input signals from the input circuit 22a, and the microcomputer 22.
It has an output circuit 22c that controls energization of the electromagnetic clutch 11 and the electric expansion valve 16 based on the output signal of the output circuit 22c.

The input circuit 22a has a built-in A-D converter etc. that converts an analog signal into a digital signal, and the output circuit 22a
c has a built-in relay circuit etc. that drives the load.

On the other hand, the microcomputer 22b is a single-chip L
The microcomputer 22b is formed by a digital computer consisting of SI, and this microcomputer 22b has a constant voltage circuit (
(not shown) and is placed in a ready state for operation. In this case, the constant voltage circuit is
In response to the closing of the ignition switch (not shown) No. 2, the constant voltage is generated by receiving a DC voltage from an on-vehicle DC power source (battery). The microcomputer 22b includes a central processing unit (hereinafter referred to as CPU), a memory (RO
The CPU, memory (ROM, RAM), and clock circuit are connected to each other via a path line. The memory (RAM) of the microcomputer 22b is the input circuit 22.
It receives and temporarily stores each digital signal from a, and selectively provides each of these signals to the CPU. The clock circuit of the microcomputer 22b generates a clock signal having a predetermined frequency in cooperation with a crystal oscillator, and allows the microcomputer 22b to execute a predetermined control program based on this clock signal.

In the memory (ROM) of the microcomputer 22b, the predetermined control program is stored in advance in order to execute predetermined arithmetic processing within the microcomputer 22b.

2(a) and 2(b) illustrate the specific structure of the orifice 19, and the orifice 19 in this example is a pipe 19a integrally formed with a pipe 19a.
It is connected to the middle of the high-pressure refrigerant piping between the electric expansion valve 16 and the receiver 15 by means of connection fittings (not shown) provided at both ends.

FIG. 3 illustrates a specific structure of the electric expansion valve 16, and 160 is a base member, which has a refrigerant inlet passage 161 at one end thereof and a refrigerant outlet passage 162 at the other end thereof. are doing. 163 is a cylindrical member made of a non-magnetic material, and has two valve holes 163a and 163b opened at symmetrical positions for decompressing and expanding the refrigerant. 164 is a magnetic plunger (valve body) slidably inserted into the inner circumference of the cylindrical member 163
When the excitation coil 166 is not energized, it is pressed by the coil spring 165 and is at the lowest position, and the two valve holes 163a and 163b are fully opened by the ring-shaped groove 164a on the outer periphery.

A fixed magnetic pole member 167 is installed opposite the plunger 164, and is fixed to the upper end of the cylindrical yoke 168. 1
Reference numeral 69 denotes a magnetic end plate that constitutes a magnetic circuit of the excitation coil 166 together with the members 164, 167 and 168. When the excitation coil 166 is energized, a magnetic attraction force is generated between the plunger 164 and the fixed magnetic pole member 167, and the plunger 1
64 is attracted to the fixed magnetic pole member 167 against the spring force of the coil spring 165, and closes the valve holes 163a and 163b. Therefore, by applying a pulse waveform voltage to the excitation coil 166, the plunger 164 continuously reciprocates, and the valve holes 163a and 163b are continuously opened and closed. By changing the duty ratio (on-off ratio in a predetermined cycle) of the pulse waveform input voltage to the excitation coil 166, the opening/closing ratio of the valve holes 163a, 163b changes, and the refrigerant flow rate can be adjusted. That is, by changing the duty ratio of the input voltage to the excitation coil 166, the opening degree of the expansion valve 16 can be substantially adjusted.

On the other hand, the electric expansion valve 16 has an outlet refrigerant temperature T of the evaporator 17.
The control circuit 22 controls the valve opening so that the temperature difference between R and the inlet refrigerant temperature TE (i.e., superheat) becomes constant.
controlled by Here, the valve opening degree is adjusted by changing the opening/closing time ratio by duty control, so the refrigerant passage repeats opening and closing continuously, so the high pressure refrigerant piping upstream of the expansion valve is Such pressure pulsations occur, causing problems such as vibration and noise in the high-pressure refrigerant piping. In FIG. 4, ΔPH can reach as much as 3 kg/adG.

However, in the device of this embodiment, the electric expansion valve 16
The electric expansion valve 16 Gas can be generated in the upstream refrigerant, and by utilizing compression of the gas refrigerant, pressure pulsations in the high-pressure side refrigerant pipe can be favorably reduced.

As shown in Fig. 6, the smaller the opening area of the orifice 19 is, the more effective it is to reduce the range of fluctuations in high pressure (pressure pulsation). Must be above. Therefore, the opening area of the orifice 19 is
It is desirable to set it to about 1 to 2 times the maximum opening area of No. 6.

The orifice 19 may be installed anywhere between the outlet of the receiver 15 and the inlet of the electric expansion valve 16.

For example, the orifice 19 may be provided inside the refrigerant inlet passage 161 of the electric expansion valve 16 as shown in FIG.

In this way, the orifice 19 and the electric expansion valve 16
This is advantageous in practice because it can reduce the number of components of the refrigeration cycle.

Alternatively, the orifice 19 may be provided in the outlet piping section of the receiver 15 and integrated with the receiver 15.

In addition to the orifice 19, pressure reducing devices such as nozzles and capillary tubes can also be used.

Further, the present invention can be similarly implemented in a refrigeration cycle in which the receiver 15 is eliminated and an accumulator is provided on the outlet side of the evaporator 17 instead.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration cycle diagram showing one embodiment of the apparatus of the present invention, including an electric control circuit. Figure 2 (a), (b)
) is a sectional view illustrating the specific structure of the orifice 19 shown in FIG. 1, FIG. 3 is a sectional view illustrating the specific structure of the electric expansion valve 16 shown in FIG. A graph showing fluctuations in the refrigerant pressure on the inlet side of the expansion valve, and FIG. 5 is a Mollier diagram for explaining the operation of the present invention. 16... Electric expansion valve, 19... Orifice (auxiliary pressure reducing device). Representative patent attorney Takashi Okabe ta) (b) Figure 2 Figure 3 051゜ Orifice Sekiguchi area mm2 Figure 6 Written amendment to procedure (bin) July 73, 1988

Claims (4)

[Claims] (1) In a refrigeration cycle device having a duty-controlled electric expansion valve that continuously repeats opening and closing of the valve body and adjusts the refrigerant flow rate according to the opening/closing ratio, a high-pressure side liquid is placed on the upstream side of the electric expansion valve. A refrigeration cycle device equipped with an auxiliary pressure reducing device that reduces the pressure of the refrigerant to a gas-liquid two-phase state. (2) The refrigeration cycle device according to claim 1, wherein the auxiliary pressure reducing device is formed of an orifice. (3) The refrigeration cycle device according to claim 1 or 2, wherein the opening area of the auxiliary pressure reducing device is set to approximately 1 to 2 times the maximum opening area of the electric expansion valve. (4) The refrigeration cycle device according to any one of claims 1 to 3, wherein the auxiliary pressure reducing device is integrally provided in a refrigerant inlet passage of an electric expansion valve.