JPH0346963Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a vehicle air conditioner that reduces fuel consumption by stopping compressor operation when the evaporator temperature of a cooling unit drops.

(Prior Art) Conventionally, there is a vehicle air conditioner known as a so-called automatic air conditioner that automatically controls the air outlet temperature so as to obtain a target temperature set by an operator, as shown in FIG. 1, for example.

In FIG. 1, 1 is an air conditioning unit, in which a blower fan 5 is provided following an intake door 4 that switches between an outside air inlet 2 and an inside air inlet 3, and the air from the blower fan 5 is sent to an evaporator 6 that recirculates refrigerant. Furthermore, an air mix door 8 installed at the inlet of the heater core 7 that recirculates the engine cooling water determines the mixing ratio of cold air and warm air, and the mixture ratio of cold air and warm air is sent into the passenger compartment through the air outlet 9. are vent, heat,
Alternatively, it can be switched according to the selection operation of each mode of the defroster.

On the other hand, in order to control the compressor 10 on and off, a temperature sensor 11 using a thermistor or the like is installed in the evaporator 6 to detect the fin temperature.
The output of the temperature sensor 11 is given to the control unit 12 of the air conditioner, and when the temperature detected by the temperature sensor 11 falls below a preset threshold temperature, the control unit 12 cuts off the power to the relay 13 and closes the relay contact. 13a is opened, the electromagnetic clutch 14 of the compressor 10 is cut off, and the operation of the compressor 10 is stopped.

As shown in Figure 2, compressor on/off control based on the cooling temperature of the evaporator is performed by controlling the vent, heat, and defroster regardless of the target temperature of the air conditioner depending on the operating position of the control finisher. There is a method in which the threshold temperature for stopping the operation of the compressor 10 is fixed in all modes, but as shown in Fig. 3, the target temperature is set by a control finisher in all modes of vent, heat, and defroster. A method is also known in which the threshold temperature at which the operation of the compressor 10 is stopped is varied in accordance with the maximum cooling time, and the threshold for the operation stop temperature of the compressor is raised to lower the operating rate of the compressor except during maximum cooling.

Generally, in vent blowing mode, it is necessary to reheat a portion of the low, constant temperature wind coming out of the evaporator of an air conditioner and mix it with the above-mentioned wind in order to raise the temperature to a predetermined level. This increases the compressor's operating rate. Therefore, in the method shown in Fig. 2, in which the compressor shutdown temperature (threshold temperature) is kept constant at all times, the total shutdown time in compressor on/off control is shortened, resulting in a reduction in fuel consumption. You won't be able to get enough.

On the other hand, in the method shown in Fig. 3 in which the compressor shutdown temperature (threshold temperature) is raised in accordance with the target temperature, when the target temperature is high in the heat blowing or defroster blowing mode, the compressor operating time is shortened. Therefore, there was a problem that a sufficient dehumidifying effect could not be obtained.

(Purpose of the invention) The present invention has been developed in view of these conventional problems, and is designed to reduce fuel consumption by controlling the compressor on and off without impairing the functions of the vent, heat, and defroster modes. The purpose of the present invention is to provide a vehicle air conditioning system that achieves the following.

(Structure of the invention) To achieve this object, the present invention provides a device for setting the threshold temperature that stops the compressor operation in a vehicle air conditioner that stops the compressor operation when the evaporator cooling temperature of the air conditioning unit is below the threshold temperature. , threshold value setting means for setting the threshold value to vary according to the set value of the set temperature in the vent blowing mode, and maintaining the threshold value at a constant value regardless of the set value of the set temperature in the heat blowing mode or the defroster blowing mode. A threshold value holding means for changing the threshold value and a threshold value switching means for changing the threshold value at the time of mode switching are provided.

(Embodiment) FIG. 4 is an explanatory circuit diagram showing an embodiment of the present invention together with an air conditioning unit.

First, to explain the configuration, 1 is an air conditioning unit, which includes an intake door 4 that switches between an outside air inlet 2 and an inside air inlet 3, a blower fan 5, and a blower fan 5.
Evaporator 6, heat core 7, air mix door 8 that cools and dehumidifies the air sent in.
The evaporator 6 is provided with a temperature sensor 11 using a thermistor or the like to detect the temperature of the cooling fin.

The output of the temperature sensor 11 is given to a control unit 12 of the air conditioner, and a circuit for controlling operation and stop of the compressor 10 based on the detected temperature of the evaporator 6 is provided in the control unit 12. That is, a threshold temperature setter 15 using a variable resistor whose resistance value changes in conjunction with the target temperature setting operation by a control finisher provided on the operation panel of the air conditioning unit is provided in the control unit 12. A fixed resistor 16 for setting a constant threshold temperature is connected in series with the setter 15, and each connection point between the variable terminal of the threshold temperature setter 15 and the fixed resistor 16 is connected as an input to a changeover switch 17. Changeover switch 17
is a switch that operates in conjunction with the mode switching of the air conditioner between vent mode and heat and defroster mode.When in vent mode, it closes to the switching contact a side shown in the figure, and when it is in heat and defroster mode, it closes to the switching contact b side. Switch. 18 is a comparator, which is a temperature sensor 11 provided in the evaporator 6.
When the detected temperature of the temperature sensor 11 is higher than the threshold temperature for stopping the compressor operation obtained through the changeover switch 17, an H level output is generated; When the detected temperature of the sensor 11 falls below the threshold temperature of the changeover switch 17, an L level output is generated, and the output of the comparator 18 is connected to the base of the transistor 19, which connects the relay 13 as an emitter load. and
An electromagnetic clutch 14 provided in the compressor 10 is controlled to be turned on and off via a relay contact 13a of the relay 13.

Next, the operation of the above embodiment will be explained.

First, when vent mode is selected, the fifth
A control characteristic is obtained in which the threshold temperature for stopping the compressor operation increases in accordance with an increase in the set target temperature determined by the operating position of the control finisher shown in FIG.

That is, when the vent mode is selected, the selector switch 17 is switched to the switching contact a side as shown in FIG. 4, and the resistance value of the variable terminal of the threshold temperature setting device 15 changes in conjunction with the operating position of the control finisher. When the set target temperature is set higher, the changeover switch 17 inputs the threshold temperature given by the voltage determined by the fixed resistor 16 and the position of the variable terminal of the threshold temperature setter 15 to the comparator 18, and this threshold temperature is equal to the target temperature. changes in proportion to. Therefore, if the target temperature is set to a higher value by operating the control finisher while the vent mode is selected, the comparator 18 for stopping the operation of the compressor 10
The threshold temperature for the target temperature also increases according to the characteristics shown in FIG. The operating rate of the compressor 10 can be lowered to save fuel consumption without any damage.

That is, when the cooling temperature of the evaporator 6 detected by the temperature sensor 11 is higher than the threshold temperature obtained via the changeover switch 17, the transistor 19 is turned on by the H level output of the comparator 18, and the relay 13 is turned on.
When energized, the relay contact 13a is closed, the electromagnetic clutch 14 is connected to the engine pulley, and the compressor 10 is operated to compress the refrigerant. When the cooling temperature of the evaporator 6 falls below the threshold temperature due to the operation of the compressor 10, the output of the comparator 18 falls to the L level, and the relay 13 is deenergized by turning off the transistor 19, opening the relay contact 13a, and closing the electromagnetic clutch 14. By opening it, the operation of the compressor 10 is stopped, and the off-on control of the compressor 10 is repeated so that the cooling temperature of the evaporator 6 reaches the threshold temperature.

On the other hand, when the heat or defroster mode is selected, the changeover switch 17 of the control unit 12 is switched to the changeover contact b side, and the comparator 18
A constant threshold temperature determined by a fixed resistor 16 is set. That is, as shown in FIGS. 5b and 5c, in the heat and defroster modes, a threshold temperature (off temperature) is set to always stop compressor operation at a constant level in response to changes in target temperature due to control finisher operation. .

Therefore, even if a higher target temperature is set using the control finisher in heat or defroster mode, the threshold temperature for stopping compressor operation is always kept constant, making it possible to obtain a sufficient dehumidification effect in heat or defroster mode. can.

(Effects of the invention) As explained above, according to the invention, in a vehicle air conditioner that stops compressor operation when the evaporator cooling temperature of an air conditioning unit is below a threshold temperature, the threshold temperature for stopping compressor operation is set. The device includes a threshold value setting means for setting the threshold value to change according to the set value of the set temperature in the vent blowing mode, and a threshold value setting means that sets the threshold value to a constant value regardless of the set value of the set temperature in the heat blowing mode or the defroster blowing mode. Since the compressor is provided with a threshold value holding means for holding the threshold value and a threshold value switching means for switching the threshold value when switching modes, the total compressor operating time in the vent mode where the compressor operating rate is high is shortened, and fuel consumption is reduced. On the other hand, in the heat or defroster mode, an appropriate dehumidification effect can be obtained over the entire target temperature control range.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional example, Fig. 2 is a conventional threshold temperature characteristic diagram for stopping compressor operation,
Fig. 3 is another conventional threshold temperature characteristic diagram for stopping compressor operation, Fig. 4 is an explanatory diagram showing an embodiment of the present invention, and Fig. 5 is a diagram of the compressor in vent, heat, and defroster modes according to the present invention. It is a characteristic diagram of the threshold temperature which stops operation. 1...Air conditioning unit, 2...Outside air inlet, 3...
...Inside air inlet, 4...Intake door, 5...Blower fan, 6...Evaporator, 7...Heater core, 8...Air mix door, 9...Blowout port, 10...Compressor, 11...Temperature sensor, 12... ... Control unit, 13 ... Relay, 13a ... Relay contact, 14 ... Electromagnetic clutch, 15 ... Threshold temperature setter, 16 ... Fixed resistance, 17 ... Changeover switch, 18 ... Comparator, 1
9...Transistor.

Claims (1)

[Scope of Claim for Utility Model Registration] In a vehicle air conditioner that stops compressor operation when the evaporator cooling temperature of an air conditioning unit is below a threshold temperature, as a setting device for the threshold temperature that stops compressor operation, in vent blowout mode, Threshold value setting means for setting the threshold value to vary according to a temperature setting value; and threshold value holding means for maintaining the threshold value at a constant value regardless of the temperature setting value in the heat blowing or defroster blowing mode. 1. A vehicle air conditioner comprising: threshold value switching means for switching the threshold value when switching modes.