JPH0712780B2 - Air conditioner for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating cycle of a vehicle air conditioner having an electromagnetic proportional expansion valve, and particularly to a rapid change in the engine speed due to a sudden change in the engine speed. Attempts are sometimes made to prevent problems due to excess or deficiency of the refrigerant flow rate.

[Conventional technology]

A refrigeration cycle using an electric expansion valve has been disclosed in Japanese Patent Laid-Open No. 59-19.
No. 1853, etc., but as shown in FIG. 3, this is an evaporator 1, a compressor 2, a condenser 3, a receiver 4, an electric expansion valve 5.
Are sequentially connected in series by piping. Here, a temperature sensor 6 and a pressure sensor 7 are arranged on the outlet side of the evaporator 1, and the refrigerant temperature T and the pressure P on the outlet side of the evaporator 1 are arranged.
It is designed to detect In addition, the temperature sensor 6
And valve control means 8 for adjusting the opening degree of the expansion valve 5 so that the superheat degree of refrigerant at the outlet of the evaporator is set to a predetermined value based on the detection signal from the pressure sensor 7. The valve control means 8 is provided when the air conditioner switch is turned on. The heat load state detecting means 9 for detecting the heat load state of the above, and the valve opening degree determining means 10 for obtaining the initial opening degree of the expansion valve 5 based on the output of the heat load state detecting means 9.
A valve adjuster 11 for adjusting the opening of the expansion valve 5 based on the output of the valve opening determining means 10, and a superheat degree on the outlet side of the evaporator 1 based on the detection signals of the temperature sensor 6 and the pressure sensor 7. And a superheat degree calculated by the arithmetic unit 12 is compared with a reference superheat degree, and when the two do not match, the superheat degree is output to the valve control unit 11 to open the expansion valve 5. It has a command unit 13 for adjusting the degree. The valve control means 8
A / D converter 14 is provided before and after.

Next, the operation will be described with reference to FIG. At step S1, the air conditioner switch is turned on. Then, in step S2, the valve control means 8 first detects the heat load state. Next, in step S3, the valve control means 8 calculates the opening degree of the expansion valve 5 based on the heat load state. After that, in step S4, the compressor 2 and the blower (not shown) are operated. Next, in step S5, the valve adjusting unit 11 causes the expansion valve 5 to
The opening degree of is adjusted to the value calculated in step S3. Thereafter, in step S6, the valve control means 8 obtains the superheat degree on the outlet side of the evaporator 1 based on the refrigerant temperature T and the pressure P,
When the degree of superheat does not match the reference degree of superheat in step S7, the opening degree of the expansion valve 5 is adjusted in step S8, and thereby the degree of superheat on the outlet side of the evaporator 1 is maintained in an ideal state.

[Problems to be solved by the invention]

By the way, in the conventional refrigeration cycle thus configured, it is assumed that, for example, the engine speed rapidly increases, and as a result, the compressor 2 rapidly increases. In this case, since the pressure change speed is fast with respect to the refrigerant temperature change immediately after the rotational speed of the compressor 2 rapidly increases, the apparent degree of superheat becomes large. However, this is a momentary phenomenon, and in reality, due to the pressure increase at the inlet side of the expansion valve 5 and the pressure drop at the outlet side, the expansion valve 5
Since the differential pressure in the opening becomes large, the flow rate of the refrigerant increases, and as a result, the degree of superheat moves contrary to the above and decreases with time. That is, the degree of superheat is detected and feedback-controlled to the expansion valve 5, but after the change in the refrigerant flow rate is detected by the sensors 6 and 7 and the valve opening degree is controlled. It takes a certain amount of time. For this reason, not only is there a problem that the valve opening control cannot quickly follow the change in the rotational speed of the compressor 2, but also the valve opening control cannot be properly controlled due to the apparent degree of superheat as described above. However, there was a problem of liquid backing to the compressor 2 and an excessive phenomenon of superheat.

[Means for solving problems]

The present invention provides a detection means for detecting the refrigerant temperature and pressure on the evaporator outlet side of a refrigeration cycle having an electric expansion valve, and a predetermined superheat degree of the refrigerant on the evaporator outlet side based on a detection signal from this detection means. In the vehicle air conditioner configured to control the opening of the expansion valve to obtain a value, pressure change detection means for detecting a pressure change value per unit time of the pressure value detected by the detection means, and a reference A storage means for storing a value and a pressure control means for comparing the reference value with the pressure change value and controlling the opening of the expansion valve based on the difference between the reference value and the pressure change value. is there.

[Action]

The valve opening control means adjusts the opening of the expansion valve by comparing the pressure change per unit time with a reference value.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same components as those of the conventional technique are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 21 is a pressure change detection means, and the pressure change detection means 21
The output of the pressure sensor 7 detects the pressure change value of the pressure on the outlet side of the evaporator 1 per unit time.

22 is a pressure control means, which compares the pressure change value with the memory 23 that stores a reference value and the pressure change value, and when both do not match, a signal proportional to the difference between the two is output. It is composed of a comparing means 24 for outputting and a control section 25 for adjusting the opening degree of the expansion valve 5 by a signal from the comparing means 24.

Next, the operation of the refrigeration cycle according to the present invention will be described below.
A description will be given based on the figure. Since steps S1 to S5 in the figure are the same as those of the conventional refrigeration cycle, the description thereof will be omitted. Therefore, in step S9, the pressure change value per unit time on the outlet side of the evaporator 1 is detected.

Next, in step S10, it is assumed that the pressure change value does not match the reference value. Then, in step S13, the opening degree of the expansion valve 5 is adjusted according to the difference between the pressure change value and the reference value. In this case, when the pressure change value is positive, the opening degree of the expansion valve 5 is small, and when the pressure change value is negative, the opening degree of the expansion valve 5 is large.

When the pressure change value and the reference value match in step S10, the degree of superheat is detected in step S11, and the match with the reference value is determined in step S12. If they do not match, the valve opening is changed in step S13 according to the degree of superheat, and the process returns to step S9. If they do match, the process returns to step S9.

〔effect〕

As described above, according to the present invention, the pressure change detection means for detecting the pressure change value per unit time of the pressure value detected by the detection means for detecting the refrigerant temperature and the pressure on the evaporator outlet side, and the reference value For example, the engine is provided with a storage unit that stores the pressure and a pressure control unit that compares the reference value with the pressure change value and controls the opening of the expansion valve based on the difference between the reference value and the pressure change value. Even if the number of revolutions of the compressor suddenly changes due to a sudden change in the number of revolutions, it is possible to quickly follow this and maintain the superheat degree at a good value.

[Brief description of drawings]

1 is a block diagram of a refrigeration cycle according to the present invention, FIG. 2 is a flow chart of the cycle of FIG. 1, FIG. 3 is a block diagram of a refrigeration cycle according to the prior art, and FIG. 4 is a cycle diagram of the cycle of FIG. It is a flowchart. 1 ... Evaporator, 2 ... Compressor, 21 ... Pressure change detection means, 22 ... Pressure control means.

Claims (1)

[Claims] 1. A detection means for detecting the refrigerant temperature and pressure at the evaporator outlet side of a refrigeration cycle having an electric expansion valve, and a superheat degree of the refrigerant at the evaporator outlet side based on a detection signal from this detection means. In the vehicle air conditioner configured to control the opening of the expansion valve to have a predetermined value, pressure change detection means for detecting a pressure change value per unit time of the pressure value detected by the detection means, Pressure control for storing the reference value and comparing the reference value stored in this storage means with the pressure change value, and controlling the opening of the expansion valve based on the difference between the reference value and the pressure change value. An air conditioner for a vehicle, comprising: