JPS5925683B2 - Vehicle air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioner for a vehicle, and more particularly to an air conditioner that prevents freezing using a temperature sensor for adjusting the opening of a mix door.

Conventionally, an automatic air conditioner has an evaporator 1 installed on the upstream side and a heater core 2 on the downstream side, as shown in FIG. 1. The evaporator 1 has the function of cooling incoming air. A cooling cycle is composed of a compressor 3, a condenser 6, a liquid receiver 7, and an expansion valve 8. Its drive is performed by turning on and off the electromagnetic clutch 4 of the compressor 3, and its drive is controlled by a controller. This is done using the output from 5.

The heater core 2 has the function of warming incoming air, and the heating temperature is controlled by opening and closing the water cock 9, and the supply of air is controlled by the actuator 11 for controlling the air mix door 10.

Actuator 11 is controlled by controller 5.

That is, the air mix door 10 is provided upstream of the heater core 2, and the temperature is appropriately controlled by changing the mixing ratio of cold air and hot air depending on the opening degree of the air mix door 10.

The blower 12 selectively sucks outside air or inside air from an outside air port 13 or an inside air port 14 depending on the position of the inside/outside air switching door 15, and sends it to the evaporator 1.

The rotation speed of the blower 12 is sequentially controlled from stop to maximum rotation by the output from the controller 5.

The inside/outside air switching door 15 is controlled by the output of the controller 5 via an actuator 16.

The most downstream part of this device is branched into an upper outlet 17 and an outlet 18, and the outlet 18 is further branched into a defrost outlet 18 and a lower outlet 182. A door 19 for mode switching is provided at the branching portion of the air outlet 18, and a door 20 for mode switching is provided at the outlet 18. The door 19 is controlled by an actuator 22, and the door 20 is similarly controlled by an actuator 23.

In this case, the mix door 10 is automatically adjusted to maintain the temperature inside the vehicle at the set temperature.

Conventionally, when the outside air temperature becomes low, for example approximately 10 to 15 degrees Celsius, the compressor is set to stop (heater mode) based on the output signal from the previous outside air temperature detection sensor or air mix door opening detection to save power. However, the compressor turns on and off due to this, and there are differences in the blowout temperature depending on whether the evaporator 1 is in a cooling state or not, so a temperature sensor 30 is installed on the downstream side of the evaporator 1. , this temperature sensor 3
With the output of 0, the opening degree of the door 10 is corrected to eliminate the level difference in the blowout temperature.

Furthermore, in the heater mode, the inside/outside air switching door is in the inside air introduction mode, but it is switched to the inside air introduction mode at the beginning of the operation of the air conditioner, when the car enters a tunnel, etc.

For this reason, a level difference occurs in the temperature of the air blown out of the duct, resulting in a decrease in feeling, but the temperature sensor 30 is also effective in eliminating such a level difference.

An object of the present invention is to make it possible to detect the occurrence of freezing in the evaporator 1 by using the temperature sensor 30 having the above function, and to reduce the number of installed temperature sensors and the number of control circuits associated therewith. This is intended to improve the safety of the cooling cycle operation by making it possible to prevent freezing, and will be described in detail below using examples.

FIG. 2 is a circuit diagram showing an embodiment of the vehicle air conditioner according to the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals.

In the same figure, 30 is a temperature sensor located directly or adjacent to the downstream side of the evaporator 1 in order to correct the operation of the mix door 10 described above, and one end of this is connected to the movable contact 31 of the switching contact 31. and the other end is grounded.

The fixed contact 312 is connected to the fixed contact 32□ of the switching contact 32, the fixed contact 313 is connected to the freeze detection circuit 33,
A contact 33□ turned on by the output of this circuit 33 is connected to a relay 34 for driving an electromagnetic clutch control contact 34□.

One fixed contact 322 of the switching contact 32 is grounded via a resistor 35, and this movable contact 323 is connected to the controller 5 via a solar radiation sensor 36, an outside air sensor 37, and an inside air sensor 38, and the output of the controller 5 is It is supplied to the actuator 11.

The freeze detection circuit 33 and the contact 33 constitute a freeze prevention means S, and the switching contacts 31 and 32 constitute the temperature sensor 3.
A switching means T is configured to switch between 0 and the resistor 35.

Note that the actuator 11 is feedback-controlled by a position detector 39.

The output supplied from the controller 5 to the relays 34 and 31 is at the L level in the heater mode (a mode in which the compressor is completely stopped), and is at the H level in the cooler mode (a mode in which the compressor is driven).

Here, the resistor 35 functions as a signal supply means P, and its resistance value is set to the average value of the resistance values when the temperature sensor 30 is used for anti-freezing.

Note that each switching contact 31, 32 is controlled by a relay 3□ that is controlled by a signal from an operating mode detector of the compressor 3.

In the above structure, when the outside temperature is low and the heater mode, that is, the compressor 3 is completely off mode, the relay 3□ is deenergized and the movable contact 31 of the switching contacts 31 and 32
□, 323 is the state shown by the solid line, the temperature sensor 30 detects the cold air from the evaporator 1, sends its output to the controller 5 for driving the actuator, thereby correcting the opening degree of the mix door 10, Prevents differences in blowout temperature.

Next, when in the cooler mode, the relay 3 is activated and the switching contact 3L32 is switched, and the temperature sensor 30 becomes the freeze detector 3.
Send the output to 3.

The freeze detector 33 determines the output of the sensor 30, and when determining that freezing has occurred, turns off the contact 331 and turns off the relay 3.
4 and the contact 34□ is turned off to stop the operation of the compressor 3.

For this reason, the compressor is driven intermittently (cycling drive).

At this time, since a resistor 35 corresponding to the resistance value of the sensor 30 is connected to the circuits of the inside air sensor 38, outside air sensor 37, and solar radiation sensor 36 instead of the temperature sensor 30, there is no problem in the operation of the controller 5.

In the past, when the temperature of the evaporator fluctuated, especially during cycling of the compressor, the air mix door would swing unnecessarily due to the action of this temperature sensor, which would wear out the link mechanism of the actuator, but according to the present application, , since the output of the fixed resistor 35 is constant, such inconvenience does not occur.

As explained above, according to the present invention, the output of the temperature sensor, which is placed close to the cooler and is used for correcting the opening of the air mix door that adjusts the mixing ratio of warm air and cold air, is sent to the freeze detector. Since the temperature sensor is supplied, the opening degree of the air mix door can be corrected using one temperature sensor, and freezing can also be prevented.

Therefore, the number of parts can be reduced, freezing can be prevented with a relatively simple circuit configuration, and the cooling cycle can be operated safely.Furthermore, it is possible to keep the evaporator pressure constant at all times for the purpose of preventing freezing, unlike conventional methods. Complicated configurations can also be made unnecessary.

[Brief explanation of the drawing]

FIG. 1 is a simplified configuration diagram for explaining a conventional vehicle air conditioner, and FIG. 2 is a circuit diagram showing an embodiment of the vehicle air conditioner according to the present invention. 3...Compressor, 5...Controller,
30... Temperature sensor, 33... Freeze detector, S... Freeze prevention means, T...
Switching means, P...Signal supply means.

Claims (1)

[Claims] 1. Freezing prevention means that compares a blower, an evaporator, and a heater core housed in a duct with an evaporative lake temperature signal corresponding to the temperature of the evaporator and a set value, and turns off the compressor when the temperature of the evaporator falls to the set value; Based on the air mix door opening correction signal corresponding to the temperature inside the duct, the air mix door opening is corrected to suppress fluctuations in the outlet air temperature. Based on the output signal, the compressor is set to heater mode, which completely stops the compressor when the outside temperature is lower than the set value.
In a vehicle air conditioner equipped with a controller that operates a compressor in a cooler mode when the outside air temperature is higher than a set value, a temperature sensor provided near the evaporator and an approximately average value of the signal of this temperature sensor are provided. a signal supply means for sending out a signal corresponding to the temperature sensor, and a signal supply means for supplying a signal from the temperature sensor to the controller as the air mix door opening correction signal in the heater mode, and a signal supply means for sending out a signal corresponding to the temperature sensor to the above-mentioned freezing prevention means in the cooler mode. 1. An air conditioner for a vehicle, comprising switching means for supplying the signal from the signal supply means to a controller as a signal and as a substitute for the air mix door opening correction signal.