JPS619324A - Control device for vehicle air-conditioner - Google Patents

Abstract

PURPOSE:To reduce variations in the temperature of blow-out air and to hold the temperature of air in the vehicle compartment in a stable condition, by adjusting the medium discharge capacity of a compressor in accordance with the difference between a signal indicating an air temperature difference between the upstream and downstream sides of a medium evaporator, and a signal indicating a thermal load in the passenger's compartment. CONSTITUTION:The thermal load of the passenger's compartment of a vehicle and a present cooling capacity which is obtained from a temperature difference between the upstream and downstream sides of an evaporator, are compared with each other by comparator circuits 41, 42, and the cooling medium discharge capacity of a compressor 50 is adjusted in accordance with the result of comparison. That is, when the temperature difference between the upstream and downstream sides of the evaporator may correspond to the thermal load of the passenger's compartment, an electromagnetic clutch 51 is deenergized to isolate the compressor 50 from its power source while when the temperature difference is between the upper and lower limits of the thermal load, the clutch 51 is energized and therefore an electromagnetic device 25 is also energized to operate the compressor 51 as its one-half capacity. Further, when the temperature difference is below the lower limit of the thermal load, the electromagnetic device 52 is deenergized so that the compressor 50 is operated at its full capacity. With this arrangement the cooling capacity may be controlled in three stages, and therefore, the heat gain of supply air may correspond to the thermal load, thereby it is possible to reduce variations in the temperature of blow-out air.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a vehicle air conditioner using an air cooling device including an evaporator of a refrigeration cycle using a refrigerant.

[Prior Art] Among this type of air conditioner, one is already known that includes an air cooling device that is operated intermittently by a refrigerant compressor that is operated intermittently.

The most commonly known method is to obtain an intermittent signal by comparing the cooling air temperature downstream of the evaporator with an arbitrary set value. In this method, if the set value is fixed or variable depending on the occupant, it is difficult to maintain the cabin air temperature constant despite fluctuations in the cabin heat load. For this reason, a method has also been proposed in which the set value is changed depending on, for example, the air temperature inside the vehicle.

[Problems to be Solved by the Invention] However, in this method, the rate of change in the temperature of the air inside the vehicle is extremely slow compared to the rate of change in the temperature of the outlet air.
There is a problem that the temperature of the blown air is greatly hunting and the feeling is bad.

[Means for Solving the Problems] Therefore, in order to solve the above problems, the present invention is characterized by being configured as follows. That is, a refrigeration cycle including a compressor whose refrigerant discharge capacity can be adjusted; an air cooling device including an evaporator for the refrigerant pumped by the compressor; a first signal generating means for generating a signal; a second signal generating means for generating a second signal corresponding to the air temperature downstream of the evaporator; upon,
temperature difference signal generation means for generating a temperature difference signal corresponding to a downstream air temperature difference; load signal generation means for generating a heat load signal corresponding to a heat load in the passenger compartment; and a temperature difference signal of the temperature difference signal generation means. and a drive means for adjusting the refrigerant discharge capacity of the compressor of the refrigeration cycle based on the difference between the heat load signal of the load signal generation means and the heat load signal of the load signal generation means.

[Function] With this configuration, the capacity of the refrigeration cycle is adjusted so that the measured cabin heat load corresponds to the cooling capacity of the evaporator obtained by the temperature difference signal generating means. Since the capacity of the refrigeration cycle is adjusted by a variable capacity compressor, changes in the amount of heat supplied to the passenger compartment are
It corresponds to the heat load and has little fluctuation.

[Examples] Hereinafter, the present invention will be described according to examples shown in the accompanying drawings. FIG. 1 shows an air cooling device, in which a refrigerant evaporator 11 and a blower device 12 are installed in an air duct 10 arranged to mainly circulate air inside a vehicle. Temperature sensors 13.1 are provided on the upstream and downstream sides of the evaporator 11, respectively.
4 is provided, and generates an electric signal according to the upstream air temperature and the downstream air temperature.

In FIG. 2 illustrating the control device, temperature sensor 13.
The electrical signal generated by 14 is input to the differential amplification circuit [120] as a voltage signal. The differential amplifier circuit 20 generates a voltage signal according to the temperature difference between the upstream air temperature and the downstream air temperature.

A temperature setting resistor 31 that sets a desired target temperature, an inside air temperature sensor 32 that measures the air temperature inside the vehicle, and an outside air temperature sensor 33 that measures the air temperature inside the vehicle are connected in series and are supplied with current from a constant current circuit 34. Ru. Series resistance circuit 3
The combined resistance value of 1 to 33 is inversely proportional to the cabin heat load, and the terminal voltage proportional to the combined resistance value is input to the inverting amplifier circuit 35.

The output of the amplifier circuit 35 increases as the thermal load increases, and is divided into two different voltages Va and vb by voltage dividing resistors 36, 37, and 38. These two voltages indicate the range of required cooling capacity determined depending on the heat load.

The two divided output voltages are the voltage representing the temperature difference appearing at the output of the differential amplifier circuit 20 and the comparison amount 1?841.4.
2 are compared respectively. The first comparator circuit 41 produces a high level output when the temperature difference is greater than the upper limit of the heat load (that is, when the heat load exceeds the cooling capacity), and the second comparator circuit 42 produces a high level output when the temperature difference is greater than the upper limit of the heat load. A high-level output is produced when the temperature difference is greater than (a low-level output is produced when neither produces a high-level output).

The variable capacity compressor 50 is configured to forcefully feed refrigerant to the evaporator 11 shown in FIG. The discharge capacity of the compressor is 1 when energized.
/2.

The electromagnetic clutch 51 connects the compressor 50 to the power source when the drive relay 44 is energized under the energization of the reversing drive circuit 43 by the low level output from the first comparator circuit 41 . Further, the electromagnetic device 52 is energized by the high level output of the second comparison circuit 42 and the low level output of the first comparison circuit 41 via the AND gate 45 and the drive circuit 46.

The air blower 12 is driven by the electric mower 1 driven by an amplified signal obtained by amplifying the load signal from the inverting amplifier circuit 35 by the amplifier circuit 60 with an air blowing capacity corresponding to the thermal load.

In the device configured as described above, when the key switch 71 is turned on, power supply from the on-vehicle battery 70 is started, and a constant voltage is applied from the constant voltage circuit 72 to circuit elements that require constant voltage.

In this operating state, the actual cooling capacity obtained from the cabin heat load and the temperature difference between the upper and downstream sides of the evaporator is compared in the first and second comparison circuits 41 and 42, and the comparison result is The refrigerant discharge force of the compressor 50 is adjusted by this. If the temperature difference between the upper and lower reaches of the evaporator 11 is large enough to meet the heat load, the electromagnetic clutch 51 is deenergized and the compressor 50 is cut off from the power source.

When the temperature difference is between the lower limit and the upper limit of the thermal load, the electromagnetic clutch 51 is energized, and the electromagnetic device 52 is also energized, so that the compressor 51 is operated at 1/2 capacity. Further, when the temperature difference is less than the lower limit of the heat load, the electromagnetic device 52 is deenergized, so the compressor 50 is operated at full capacity.

In this way, the cooling capacity of the freezing cycle is adjusted so that the air temperature difference between the upper and lower reaches of the evaporator 11 is adjusted to a desired value in three stages (full capacity, 1/2 capacity, and stop) that corresponds to the heat load. By controlling the temperature, the amount of heat of the air supplied into the passenger compartment is commensurate with the heat load at the time, and since there is little change over time, there is little temperature variation in the blown air, which improves the thermal sensation of the passengers. This is preferable, and the number of times the compressor is turned on and off is small, which reduces the burden on the power source.

Note that the air blowing capacity of the air blower 12 is controlled in accordance with the heat load.

In addition to the configuration using the analog electric circuit described above, the present invention also includes
Analog calculations can also be replaced with digital calculations using a microcomputer. Furthermore, the compressor 50 may be one whose capacity can be adjusted in three or more stages.

[Effects of the Invention] As described above, according to the present invention, the capacity of the compressor is controlled in accordance with the temperature of the air above and below the evaporator, which is determined in accordance with the heat load. To stably maintain the vehicle interior air temperature at a set temperature with little fluctuation. Also,
This has the effect of reducing load fluctuations on the compressor power source.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout diagram of an air conditioner to which the present invention is applied, and FIG. 2 is an electrical wiring diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Evaporator, 13... Temperature sensor (first signal generation means), 14... Temperature sensor (second signal generation means), 20... Differential amplifier circuit (temperature difference signal generation) means)
, 31... Setting resistance, 32... Inside air temperature sensor, 3
3... Outside air temperature sensor, 35... Inverting amplifier circuit (constituting load signal generation means with elements 31 to 33), 4
1... first comparison circuit, 42... second comparison circuit,
45... AND gate, 46... Drive relay (forms drive means with elements 41, 42, 45, and 46),
50... Compressor, 52... Electromagnetic device for adjusting discharge capacity.

Claims (1)

[Scope of Claims] A refrigeration cycle including a compressor whose refrigerant discharge capacity can be adjusted; an air cooling device including an evaporator for the refrigerant pumped by the compressor; a first signal generating means for generating a first signal corresponding to the temperature of the air on the downstream side of the evaporator; a second signal generating means for generating a second signal corresponding to the downstream air temperature of the evaporator; temperature difference signal generating means for generating a temperature difference signal according to the air temperature difference between above and downstream of the evaporator; load signal generating means for generating a heat load signal according to the heat load of the vehicle compartment; and the temperature difference. a drive means for adjusting the refrigerant discharge capacity of the compressor of the refrigeration cycle based on the difference between the temperature difference signal of the signal generation means and the heat load signal of the load signal generation means; Control device for.