JPH01256765A - Freezing cycle control device for vehicle - Google Patents

Abstract

PURPOSE:To provide normally sufficient cooling capacity of a mixture refrigerant by a method wherein, in consideration of a change in content of the mixture of the refrigerants, the opening of an electronic expansion valve is controlled. CONSTITUTION:During the cooling operation of a freezing cycle responding to the opening of an expansion valve means 1d controlled by an opening control means 2, when a mixture refrigerant circulating through a freezing cycle 1 leaks to the outside, the respective amounts of leaking refrigerants of the mixture refrigerant are different from each other due to the difference between molecular weights of the refrigerants. Even when the content of the mixture refrigerant is changed, a content deciding means 4 decides a composition ratio, and based on the decision composition ratio, a superheat amount regulating means 5 regulates a superheat amount to a value higher than a superheat amount responding to a detecting refrigerant state, and the opening of the expansion valve means 1d is controlled to a valve responding to the regulated superheat amount by means of the opening control means 2. Thus, since, even when the content of the mixture refrigerant is changed, the opening of the expansion valve means 1d is always controlled to a lower value, the degree of expansion of the mixture refrigerant to a vaporizing means 1e is increased to a value higher than the regulated superheat amount, and cooling capacity of the mixture refrigerant can be always utilized to maximum.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a vehicular refrigeration cycle control device, and particularly relates to a vehicular refrigeration cycle control device that employs a mixed refrigerant made by mixing two or more types of refrigerants. .

(Prior art) Conventionally, in this type of vehicle refrigeration cycle control device, a mixed refrigerant is compressed by a compressor and then condensed by a condenser, and the condensed refrigerant is electronically expanded so that its superheat reaches a target value. There is a type of refrigerant in which the air is expanded according to the opening degree of the valve and allowed to flow into the evaporator, and the air flow to be blown out toward the object to be cooled is cooled by the evaporator according to the inflowing and expanded refrigerant.

(Problem to be Solved by the Invention) By the way, in such a configuration, since the compressor is adjacent to the engine in the engine room of the vehicle, the compressor may vibrate mechanically when power is transmitted from the engine to the compressor. . Therefore, in order to absorb such mechanical vibrations of the compressor, the refrigerant inlet of the compressor and the piping extending from the evaporation lake are connected with a rubber hose, and the refrigerant outlet of the compressor and the piping extending from the condenser are connected with a rubber hose. often connected.

Therefore, when the mixed refrigerant passes through each rubber hose, since the molecular weight of the mixed refrigerant is small, the permeation of the mixed refrigerant to the outside through the peripheral wall of the rubber hose cannot be completely blocked. In such a case, the refrigerant with a smaller molecular weight among the refrigerants in the mixed refrigerant has a higher degree of outward permeation than the refrigerant with a larger molecular weight. Therefore, as time passes, the composition ratio of each refrigerant in the mixed refrigerant circulating through the refrigeration cycle control device changes. As a result, the relationship between the pressure and the temperature of the mixed refrigerant changes, making it inappropriate for the expansion valve to control the superheat of the mixed refrigerant, making it difficult to effectively utilize the cooling capacity of the mixed refrigerant.

Therefore, the present invention aims to deal with this problem by controlling the opening degree of the electronic expansion valve in consideration of changes in the composition ratio of each refrigerant in the mixed refrigerant in a vehicle refrigeration cycle control device. The objective is to always make full use of the cooling capacity of the mixed refrigerant.

(Means for solving the problem) In solving the problem, the structural features of the present invention are as follows:
As illustrated in FIG. 1, a compression means 1a that is driven by the engine of a vehicle to compress a mixed refrigerant, a condensing means 1b that condenses the compressed mixed refrigerant, and a gas phase component and a liquid phase of the condensed mixed refrigerant. a gas-liquid separation means 1c for separating into components;
A refrigeration cycle 1 comprising an expansion valve means 1d that expands the liquid phase component according to the opening degree, and an evaporation means 1e that cools the air flow to be blown to the object to be cooled according to the expanded liquid phase component;
A refrigeration cycle control device comprising: an opening degree control means 2 for controlling the opening degree of the expansion valve means 1d so as to make the amount of superheat of the refrigerant flowing from the evaporation means 1e to the compression means 1a normal; a detection means 3 for detecting the refrigerant state of the liquid phase component from the IC to the expansion valve means 1d; and a refrigeration cycle 1.
a composition ratio determination means 4 for determining a composition ratio of the mixed refrigerant that changes in response to leakage of the mixed refrigerant according to the detected refrigerant state; and based on the determination result, the superheat amount is adjusted to the detected refrigerant state. A superheat amount adjusting means 5 is provided which adjusts the amount of superheat to be higher than the corresponding amount of superheat, and the opening control means 2 controls the opening degree of the expansion valve means 1d to a value corresponding to the adjusted amount of superheat. The reason lies in the fact that it is controlled.

(Function) By configuring the present invention in this way, during the cooling action of the refrigeration cycle according to the opening degree of the expansion valve means 1d controlled by the opening degree control means 2, the mixed refrigerant circulating in the refrigeration cycle 1 If leakage occurs to the outside for some reason, even if the leakage amount of each refrigerant in the same mixed refrigerant differs due to the difference in molecular weight of each refrigerant and the composition ratio of the mixed refrigerant changes, the leakage amount will change accordingly. The composition ratio determination means 4 determines the composition ratio of the mixed refrigerant in relation to the detected refrigerant state, and the superheat amount adjustment means 5 adjusts the superheat amount based on the determined composition ratio. The opening degree control means 2 controls the opening degree of the expansion valve means 1d to a value corresponding to the adjusted superheat amount.

(Effect) Therefore, even if the composition ratio of the mixed refrigerant changes as described above, the opening degree of the expansion valve means 1d is always controlled to be small, so that the degree of expansion of the mixed refrigerant to the evaporation means 1e is controlled by the adjustment super. It becomes larger in accordance with the heat it, and as a result, the cooling capacity of the mixed refrigerant can always be utilized to the maximum. Therefore, for example, even if the compression means 1a is connected between the condensation means 1b and the evaporation means 1e by a refrigerant supply member such as a rubber hose, the leakage of the mixed refrigerant from these refrigerant supply members will not occur. , it is possible to always ensure sufficient cooling capacity of the mixed refrigerant.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.
The figure shows an example of a vehicular refrigeration cycle control device according to the present invention. This refrigeration cycle control device has a refrigeration cycle Rs, and the refrigeration cycle Rs is filled with an azeotropic refrigerant mixture of refrigerants R152a and R12 having different molecular weights. In such a case, refrigerant R15
The molecular weight of 2a is smaller than that of refrigerant R12.

Further, the composition ratio of R152a and R12 and the amount of each of them enclosed are determined in consideration of the desired cooling capacity of the refrigeration cycle Rs.

The refrigeration cycle Rs has a compressor 10, and the compressor 10 has an attached electromagnetic clutch 10a.
, power is transmitted from the engine of the vehicle to the piping P1 and the rubber hose Hl connected thereto.
The mixed refrigerant inside is sucked in through the suction port 11, compressed, and discharged as a high-temperature, high-pressure compressed mixed refrigerant from the discharge port 12 through the rubber hose TL2 connected to the rubber hose H2 into the pipe P2 connected to the rubber hose H2.

The condenser 20 condenses the compressed mixed refrigerant in the pipe P2 under the air cooling action of the air cooling fan, and causes the compressed mixed refrigerant to flow into the pipe P3 as a two-phase mixed refrigerant consisting of a liquid phase and a gas phase. The gas-liquid separator 30 separates the two-phase mixed refrigerant from the pipe P3 into a liquid-phase mixed refrigerant and a gas-phase mixed refrigerant, and allows only the liquid-phase mixed refrigerant to flow into the pipe P4. The electronic expansion valve 40 expands the liquid phase mixed refrigerant from the pipe P4 according to its actual opening degree and causes it to flow into the evaporator 50 through the pipe P5. The evaporator 50 cools the air flow from the blower to be discharged toward the object to be cooled in response to the expanded mixed refrigerant from the pipe P5, and causes the vaporized mixed refrigerant to flow into the pipe Pl. In such a case, the actual opening degree of the expansion valve 4o corresponds to the superheat of the vaporized mixed refrigerant flowing into the pipe Pl.

Next, to explain the electric circuit configuration of the refrigeration cycle control device, the temperature sensor 60a detects the actual temperature of the liquid phase mixed refrigerant in the pipe P4 near the outlet of the gas-liquid separator δ■ device 30, and detects the refrigerant temperature. Occurs as a signal. The pressure sensor 60b is located adjacent to the temperature sensor 60a, detects the actual pressure of the liquid phase mixed refrigerant in the pipe P4, and generates a refrigerant pressure detection signal. The temperature sensor 70a detects the actual temperature of the vaporized mixed refrigerant in the pipe Pl near the outlet of the evaporator 50, and generates a refrigerant temperature detection signal.

The pressure sensor 70b is located adjacent to the temperature sensor 70a, detects the actual pressure of the vaporized mixed refrigerant in the pipe Pl, and generates a refrigerant pressure detection signal. Temperature sensor 80 detects the actual temperature of the cooling air flow by evaporator 50 and generates an air temperature detection signal.

The A-D converter 90 receives refrigerant temperature detection signals from both temperature sensors 60a and 70a, and a side pressure sensor 60b.

Each refrigerant pressure detection signal from the temperature sensor 70b and the air temperature detection signal from the temperature sensor 80 are each digitally converted to generate each refrigerant temperature digital signal, each refrigerant pressure digital signal, and the air temperature digital signal. The microcomputer 100 executes A-D according to the flowchart shown in FIG.
llA1& with the converter 90 executes the computer program, and during this execution, the electromagnetic clutch 10
a and each drive circuit 110 connected to the expansion valve 40, respectively.
Performs arithmetic processing necessary for control of 120 degrees. However, the above-mentioned computer program is a microcomputer 100.
is stored in advance in the ROM. Note that the microcomputer 100 is an ignition switch IG of the vehicle.
It operates by being supplied with power from battery B via.

In this embodiment configured as described above, when the engine of the vehicle is started and the microcomputer 100 is activated by closing the ignition switch IC, the microcomputer 100 performs step 200 according to the flowchart of FIG. At step 210, execution of the computer program starts at A-D.
The value of the air temperature digital signal from the converter 90 is expressed as air temperature'
This air temperature Ta is input as the set temperature To (170M of the microcomputer 100).
(previously stored), the microcomputer 100 determines "rYES" in step 220, and in step 220a generates a latch output signal necessary for engaging the electromagnetic clutch 10a.

Then, the electromagnetic clutch lOa responds to the clutch output signal from the microcomputer 100 and the first drive circuit 1
Accordingly, the compressor 10 is driven by the engine, sucks the mixed refrigerant from the evaporator 50 through the pipe P1 and the rubber hose H1, and compresses it as a high-temperature, high-pressure compressed mixed refrigerant. Discharge into P2. Next, the compressed refrigerant in this pipe P2 is condensed by the condenser 20, flows through the pipe P3 into the gas-liquid separator 30, and is separated into a liquid phase component and a gas phase component. At this time, assuming that the expansion valve 40 is at the initial opening degree, the liquid phase component flowing into the pipe P4 from the gas-liquid separator 30 is expanded as a liquid phase mixed refrigerant by the expansion valve 40 according to the initial opening degree. It flows into the evaporator 50 through the pipe P5.

Therefore, the air flow from the blower is transferred to the evaporator 50.
The coolant is cooled by the inflowing refrigerant and then blown out to the object to be cooled.

After the arithmetic processing in step 220a, the microcomputer 100 controls the temperature sensor 60 in step 230.
The value of the refrigerant temperature digital signal from the A-D converter 90 in response to the refrigerant temperature detection signal from the pressure sensor 60b is input as the refrigerant temperature Tra, and the value of the refrigerant temperature digital signal from the A-D converter 90 in response to the refrigerant pressure detection signal from the pressure sensor 60b is inputted as the refrigerant temperature Tra. The value of the refrigerant pressure digital signal is input as the refrigerant pressure Pra. Next, when the computer program proceeds to step 240, the microcomputer 100 determines the composition ratios X and Y of the refrigerant R12 and the refrigerant R152a in the mixed refrigerant in the pipe P4 as follows.

In this judgment, the RO of the microcomputer 100
Data Dh representing the composition ratio of the mixed refrigerant is stored in advance in M. Data Dh specifies the relationship between the composition ratio X of the refrigerant R12 in the mixed refrigerant in a saturated liquid state in the pipe P4 near the outlet of the gas-liquid separator 30 and the refrigerant temperature Tra, using the refrigerant pressure Pra as a parameter. (An example is shown in Fig. 4). In step 240, the microcomputer 100 determines the composition X of the refrigerant R12 in relation to the refrigerant temperature Tra in accordance with the data Dh based on the refrigerant pressure Pra. In such a case, each refrigerant R
12. If the amount of water leaking from each rubber hose H1, H2 of R152a is zero, the value specifies point 1 (a (see Fig. 4) where the refrigerant pressure 'r'ra is greater than or equal to the data Dh. , each rubber hose H1, l of each refrigerant R12°R152a
If the refrigerant temperature Tra rises due to leakage from -12 and specifies the point 1-(b (see Figure 4) where the refrigerant temperature Tra rises and is higher than the data Dh, the composition ratios X and Y of both refrigerants become Xb and Yb, respectively. Become.

In this case, since the refrigerant R152a leaks more easily than the refrigerant R12, (Yb/Xb)<(Ya/Xa) holds true.

After the above-described determination, the microcomputer 100
At step 250, the value of the refrigerant temperature digital signal from the A-D converter 90 corresponding to the refrigerant temperature detection signal from the temperature sensor 70a is input as the refrigerant temperature Trb, and the refrigerant pressure detection signal from the pressure sensor 70b is input. A corresponding to
The value of the refrigerant pressure digital signal from the -D converter 90 is input as the refrigerant pressure 1) rb. When the computer program proceeds to step 260, the microcomputer 100 performs the superheat amount sh as follows.
Determine.

In this judgment, the RO of the microcomputer 100
Other data Dl representing the composition ratio of the mixed refrigerant is stored in M in advance. This data Dβ is expressed as the refrigerant temperature T as the composition ratio
rb is specified using the refrigerant pressure Prb as a parameter (an example is shown in FIG. 4). Therefore, the microcomputer 100 performs the step 260 described above.
, based on the refrigerant pressure Prb (XxX according to the data DJ
Determine the intersection La or Lb of the data DJ2 with the steam line in relation to a or xb, and determine the target super heat 1ts.
Determine h (specified by LaLc or LbLd). In such a case, the target superheat amount sh is for bringing the refrigerant temperature Trb to a temperature specified by points Ld, l, and c, and is, for example, 5 (° C.).

After determining the super heat JfiS h as described above, when the super heat 1-amount sh is equal to or greater than the set amount Sho (previously stored in the ROM of the microcomputer lOO), the microcomputer 100 performs step 2.
At step 70, it is determined that the opening is rYEsJ, and at step 280, an opening increase signal for increasing the opening of the expansion valve 40 is generated. On the other hand, when sh<Sho, the microcomputer 100 determines rNOJ at step 270, and generates an opening reduction signal for decreasing the opening of the expansion valve 40 at step 290. However, the expansion valve 40
is driven by the drive circuit 120 in response to an opening increase signal or an opening decrease signal from the microcomputer 100 to increase or decrease the opening and thereby decrease or increase the degree of expansion of the mixed refrigerant in the pipe R4. This means that the mixed refrigerant from the evaporator 50 is superheated 1. The aim is to control the opening degree of the expansion valve 40 so that s h is maintained at the set amount Sho.

Therefore, as mentioned above, the amount of leakage of the refrigerant R152a from each rubber hose H1, H2 is larger than that of the refrigerant R12, for example,
=Xb, Y=Yb, the composition ratio determination in step 240 and the superheat Hsh based on this are
, After making an appropriate judgment according to the change in Y, S h=S
Since the opening degree of the expansion valve 40 is controlled so that h o,
Each rubber hose 111.1 (each refrigerant R12, R1 from 2
Even if the leakage amount of the evaporator 52a is different, the cooling capacity of the evaporator 50 can always be secured to one minute after proper superheat control. Note that when the determination in step 220 is rNOJ, the microcomputer 100 eliminates the clutch output signal in step 220b and disengages the electromagnetic clutch 10a.

Note that in implementing the present invention, the temperature sensor 60a and the pressure sensor 60b may be arranged so as to detect the temperature and pressure of the refrigerant in the pipe R4 near the inlet of the expansion valve 40. However, since the temperature of the mixed refrigerant is lower than in the above embodiment, a correction is made accordingly.

Furthermore, in carrying out the present invention, the refrigerant in the mixed refrigerant is not limited to R12 and R152a, and a mixed refrigerant of a plurality of refrigerants having different molecules (■) may be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to the structure of the invention described in the claims, FIG. 2 is a block diagram showing an embodiment of the invention, FIG. 3 is a flowchart showing the operation of the microcomputer shown in FIG. FIG. 4 is a characteristic curve diagram showing the relationship between the composition ratio of the mixed refrigerant, the refrigerant temperature, and the refrigerant pressure. Explanation of symbols Rs: Refrigeration cycle, 10: Compressor, 2
0... Condenser, 30... Gas-liquid separator, 40...
- Expansion valve, 50... Evaporator, 60a... Temperature sensor, 60b... Pressure sensor, 100... Microcomputer. Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] a compression means driven by a vehicle engine to compress the mixed refrigerant; a condensing means for condensing the compressed mixed refrigerant; a gas-liquid separation means for separating the condensed mixed refrigerant into a gas phase component and a liquid phase component; A refrigeration cycle comprising an expansion valve means for expanding a phase component according to the degree of opening, and an evaporation means for cooling an air flow to be blown out to an object to be cooled according to the expanded liquid phase component;
and opening control means for controlling the opening degree of the expansion valve means so as to optimize the amount of superheating of the refrigerant from the evaporation means to the compression means, in which: a detection means for detecting a refrigerant state of a liquid phase component to the expansion valve means; and a composition ratio for determining a composition ratio of the mixed refrigerant that changes depending on leakage of the mixed refrigerant from the refrigeration cycle in accordance with the detected refrigerant state. determining means, and a superheat amount adjusting means for adjusting the superheat amount to be higher than the superheat amount corresponding to the detected refrigerant state based on the determination result,
A refrigeration cycle control device for a vehicle, wherein the opening degree control means controls the opening degree of the expansion valve means to a value corresponding to the adjusted superheat amount.