JPH022657Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an air conditioner for automobiles.

In a known automotive air conditioner, as shown in the control circuit diagram in FIG. The magnetic clutch 7 is energized via the contact 40a of the relay 40, which is energized by the air conditioner switch 18 and the cooling system control thermostat 19, and the compressor 6 is driven by the engine. , an expansion valve 10, and an evaporator 11.
The cooled air is appropriately reheated by the heater device 3 by operating the air mix damper 4, and is blown out into the room 5 at an appropriate temperature.

At that time, the control device 20 that controls the air mix damper 4 is operated as shown in FIGS.
Outside air temperature sensor (thermistor) as shown in the figure
30, in-vehicle temperature sensor (thermistor) 29, room temperature setting device (variable resistance) 28, set by the passenger;
The voltage generated by the potentiometer 23 in the power servo 21 is input, and this is compared with the reference voltage in the control device 20. If the temperature inside the vehicle is high, the cool side valve (atmosphere side) of the dual valve 25 is opened. If the temperature inside the vehicle is low, open the hot side valve 26 (negative pressure side) to adjust the pressure inside the vacuum actuator 22 of the power servo 21,
Air mix damper 4 mechanically linked to this
is activated to control the temperature of the air blown inside the car, thereby changing the potentiometer 23 and the temperature inside the car, feeding back the change value to the control device 20, and controlling the temperature inside the car to maintain it at the set value. .

In Fig. 2, the potentiometer 23 is a variable resistor whose resistance increases when the air mix damper 4 is on the cool side, the room temperature setting device 28 is a variable resistor whose resistance increases when the temperature is set, and the vehicle interior temperature sensor. 29. The outside air temperature sensor 30 is a thermistor with a negative characteristic whose resistance value becomes small at high temperature, 33a, 34a, 34.
b and 34c are fixed resistors that determine control constants, respectively; 35a and 35b are fixed resistors that set the offsets of comparators 37 and 38.

The conditions for generating the output H that operates the hot side valve 26 of the dual valve 25 and the output C that operates the cool side valve 27 are shown in Fig. 3 by the branch voltages V _A , V B , and V C at the branch points A, _B , and _C. is set to satisfy the relationship shown. Here, V _CC indicates a constant voltage for control.

However, in such an air conditioner, the branch voltage V _A is a partial voltage of the added resistance value of the outside air temperature sensor 30, the inside temperature sensor 29, the room temperature setting device 28, and the potentiometer 23, and the fixed resistor 33a. There is, and it changes proportionally according to changes in each resistance value, so it is automatically controlled to maintain approximately the set temperature according to changes in outside temperature and inside temperature, but temperature control in this case is as follows: Based on the premise that the heater water temperature is approximately constant and the air temperature blown out from the heater device 3 is approximately constant, the ratio of the amount of cold air distributed by the air mix damper 4 to the amount of hot air distributed to the inside of the vehicle is determined. It is designed to determine the blowing temperature.

Therefore, when the heater water temperature fluctuates widely and the heater outlet air temperature fluctuates greatly, especially when the cooling water of a diesel engine is used as a heat source, even if the air mix damper opening degree is the same, The temperature of the air blown inside the car fluctuates due to fluctuations in the heater water temperature, and as a result, the temperature inside the car changes.Although it is corrected to some extent by the feedback from the car temperature sensor 29, the temperature inside the car stabilizes at a large deviation from the set temperature. This also makes the temperature inside the car less stable.

The present invention was proposed in view of these circumstances, and aims to provide an automobile air conditioner that maintains the temperature inside the car at a set value even if the heater water temperature fluctuates greatly. The air is divided into warm air obtained by passing through a heater that uses hot water as a heat source and cold air that bypasses the heater using an air mix damper. In a device in which the mixture damper is automatically controlled according to the temperature inside the car and the outside air temperature to maintain the temperature inside the car at a set value, a temperature detector is provided to detect the temperature of the hot water flowing into the heater, and the temperature of the hot water is The air mix damper is moved to a cool side or a hot side depending on whether the temperature is high or low.

An embodiment of the present invention will be explained with reference to the drawings.
FIG. 4 is a control circuit diagram thereof, and FIG. 5 is an enlarged block diagram of the control device shown in FIG. 4.

In the above diagram, the same symbols in Figure 1 indicate the same members, 50 is a control device, 51 is attached to the heater inflow side of the heater device 3, and the resistance value increases as the temperature decreases. The water temperature sensor 33b made of a negative characteristic thermistor is a fixed resistor whose resistance value is changed from the fixed resistor 33a shown in FIG. 2 in accordance with the control constant in conjunction with the attachment of the water temperature sensor 51.

According to such a device, the basic operation is the same as that of the conventional system, that is, the output C is determined by the branch voltages V _A , V B , and V _C at the branch points A, _B , and C in the same relationship as shown in FIG. and output H are output respectively, so
Stable state V _B where the vehicle interior temperature approximates the set temperature
When the heater water temperature decreases from >V _A > V _C , the resistance of the water temperature sensor 51, which is a negative characteristic thermistor, becomes large.
When the branch voltage V _A increases and V _A > V _B , the output H
Output.

As a result, the hot side valve 26 of the dual valve 25 opens, and the air mix damper 4 moves to the hot side, increasing the amount of hot air to compensate for the drop in the temperature of the blown air due to the drop in water temperature, and stabilizing the temperature of the blown air inside the car. temperature and stabilize the temperature inside the vehicle. on the other hand,
Synchronizing with the movement of the air mix damper 4 toward the hot side, the resistance value of the potentiometer 23 decreases, and the branch voltage V _A decreases. When V _B > V _A > V _C , the outputs C and H Both become 0, and the air mix damper 4 stops moving toward the hot side.

When the water temperature rises, V _A decreases, and when V _A < V _C , output C is generated, moving the air mix damper 4 to the cool side, and acting in the same way as above. Stabilize the temperature of the blowing air and the temperature inside the car.

According to such a device, the amount of change in the blowout air temperature and car interior temperature due to heater water temperature fluctuations is inputted to the air mix damper control device using a water temperature sensor prior to the occurrence of fluctuations in the blowout air temperature and car interior temperature. By moving the air mix damper to the hot side or the cool side, the blowing temperature can be adjusted.
Since the temperature inside the vehicle can be stabilized, the present invention is particularly effective in diesel engines that use engine cooling water as a heat source for the heater.

By the way, if there is no compensation by water temperature sensor,
Feedback control changes in the order of water temperature change → outlet air temperature change → interior temperature change → air mix damper movement by the control device, and the response is slow, resulting in a decrease in system stability and control accuracy. However, in this invention, Since changes in water temperature are directly detected and the air mix damper is moved via the control device, feedforward control is performed that predicts changes in the temperature of the blown air, improving system stability and control accuracy.

In short, according to the present invention, the air that has passed through the cooling device is divided by an air mix damper into hot air obtained by passing through a heater that uses hot water as a heat source, and cold air that bypasses the heater. The temperature of hot water flowing into the heater is mixed and blown out into the car at an appropriate temperature, and the air mix damper is automatically controlled according to the temperature inside the car and the outside air temperature to maintain the temperature inside the car at the set value. By installing a temperature detector to detect the temperature of the hot water and moving the air mix damper to the cool side or hot side depending on the high or low temperature of the hot water, the room temperature can be stabilized despite changes in the heater water temperature. The present invention is industrially extremely useful because it provides an automobile air conditioner with improved control accuracy.

[Brief explanation of the drawing]

Figure 1 is a control circuit diagram of a known automotive air conditioner, Figure 2 is an enlarged block diagram of the control device in Figure 1, and Figure 3 is a diagram showing the relationship between branch voltage and output in Figure 2. , FIG. 4 is a control circuit diagram of an embodiment of the present invention, and FIG. 5 is an enlarged block diagram of the control device shown in FIG. 4. 1... Blower, 2... Cooling device, 3... Heater device, 4... Air mix damper, 5... Indoor,
6... Compressor, 7... Magnetic clutch, 8... Capacitor, 9... Receiver, 10...
...Expansion valve, 11... Evaporator, 15... Power source, 16... Ignition switch, 17... Fan switch, 18... Air conditioner switch, 19
...Thermostat for cooling system control, 2
1... Power servo, 22... Vacuum actuator, 23... Potentiometer, 25...
Dual valve, 26...Hot side valve, 27
...Cool side valve, 28...Room temperature setting device, 29
... In-vehicle temperature sensor, 30 ... Outside temperature sensor,
33a, 33b, 34a, 34b, 34c, 35
a, 35b... fixed resistor, 37, 38... comparator, 40... relay, 40a... contact, 50...
Control device, 51...Water temperature sensor.

Claims (1)

[Scope of utility model registration request] The air that has passed through the cooling system is separated by an air mix damper into warm air that is obtained by passing through a heater that uses hot water as a heat source, and cold air that bypasses the heater, and then the two are mixed and blown into the car at an appropriate temperature. At the same time, the air mix damper is automatically controlled according to the temperature inside the car and the outside air temperature to maintain the inside temperature at the set value, and a temperature detector is installed to detect the temperature of the hot water flowing into the heater. An air conditioner for an automobile, characterized in that the air mix damper is moved to a cool side or a hot side depending on whether the temperature of the hot water is high or low.