JPS6246371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle air conditioner that accurately controls the temperature inside a vehicle interior.

Modern vehicles are equipped with air conditioners (hereinafter referred to as "air conditioning systems") that heat or cool the air inside the vehicle to optimally adjust the interior to suit the season, time of day, or passenger preference. Equipped.

As shown in Figure 1, the conventional vehicle air conditioner is
The air sucked into the device from the air intake port 2 by the blower 1 is dehumidified and cooled by the evaporator 3, and part of the cold air coming out of the evaporator 3 is passed through the heater core 4 to become warm air, which is then converted into cold air from the evaporator 3. A power servo 6 operates an air mix door 7 and a hot water valve 8 to change the mixing ratio of hot air and cold air and the hot water flow rate of the heater core 4. The air temperature is controlled by adjusting the blowout temperature, and the room temperature is controlled by adjusting the blowout air volume by changing the rotation speed of the blower drive motor 9.
55-87612).

FIG. 2 shows the configuration of a blowout temperature and air volume control device conventionally used in this air conditioner to maintain the room temperature at a set value. In FIG. 2, 10 is a temperature detection thermistor, 11 and 12 are temperature setting sliding resistors, 13 is a feedback sliding resistor, and 1
4 and 15 are fixed resistors, and the deviation between the input signal (resistance value) from the thermistor 10 corresponding to the room temperature and the reference input (resistance value) from the sliding resistors 11 and 12 corresponding to the set temperature is 10 to 15. It is converted into a potential difference between points a and b and between points a and c of a resistive bridge consisting of a resistor bridge, which is extracted and applied to comparators 16 and 17 to determine whether the deviation is large or small and whether it is positive or negative. As a result, the obtained control signal is transferred to the amplifying transistor 1.
8 and 19, the outputs are converted into power outputs, and the coils 20 and 21 are selectively excited by the respective outputs. Three-way valves 22, 23 operated by coils 20, 21 serve to switch both sides of a piston 24 in the negative pressure actuator 6 to a negative pressure side 25 and an atmospheric side 26, 27.

For example, if the room temperature is now lower than the set temperature, the potential at point a increases due to an increase in the resistance value of the thermistor 10, and the comparator 16 outputs a control signal of "1". This signal causes transistor 18 to conduct and coil 20 to be energized. Then, the lower side of the piston 24 becomes negative pressure due to the operation of the three-way valve 22, so the piston 24 moves to the H side, and the air mix door 7 and the hot water valve (first
Operate 8) in the figure in the direction to increase the blowing temperature. Along with this, the sliding resistance 1 for feedback
Since the resistance value of point 3 increases and pushes up the potential at point b, the control system becomes in an equilibrium state at a certain point. That is, the output of the comparator 16 becomes "0" and the transistor 18 becomes non-conductive. Therefore, the three-way valve 22
returns to its original state, and the piston 24 stops at that position. When the room temperature rises above the set temperature, a control signal from the comparator 17 causes the operation opposite to the above to be performed. If the set temperature is increased, the sliding resistance 1
As the reference input from 1 and 12 decreases, the potential difference between points a and b changes to become smaller. Conversely, if the set temperature is lowered, the increase in the reference input from sliding resistors 11 and 12 causes the potential difference between points a and c to decrease. changes in the direction of decreasing the potential difference.

On the other hand, the contact 29 of the sliding resistor 28 interlocks with the air mix door 7 and switches the contact 30, thereby changing the voltage applied to the blower drive motor 9. As a result, the motor rotation speed changes and the air mix door 7 moves to the maximum heating position. The blowout air volume also reaches its maximum when it is at the maximum cooling position P ₁ (see Figure 1) and the maximum cooling position P ₃ (see Figure 1).

In such a control device, the blowout temperature changes depending on the opening degree of the air mix door, but in conventional air conditioners, the opening degree of the air mix door relative to the difference between the set temperature and the room temperature, that is, the difference in temperature, is as shown in Figure 3. It is set. In other words, when the temperature difference is larger than T, the air mix door takes the maximum cooling (full cool) position (P ₃ in Fig. 1) with an opening degree of 0, which does not allow cold air to pass through the heater core 4, and when the temperature difference becomes smaller than T, Therefore, depending on the temperature difference, arrow A
Gradually increase the door opening in the direction of , and change the mixing ratio of cold air and warm air. On the other hand, the temperature difference
When the temperature difference is larger than T', the air mix door takes the maximum heating (full hot) position (P 1 in Fig. 1) where the opening degree is 100%, which allows all the cold air to pass through the heater core ₄ , and as the temperature difference becomes smaller than T', Then, depending on the temperature difference, the door opening degree is gradually reduced in the direction of arrow B, changing the mixing ratio of cold air and hot air. In this way, the opening degree of the air mix door is ultimately set to stabilize at around 50%. Normally, T and T' are set at ±6 to 8°C to control the room temperature to the set temperature.

Incidentally, the slope θ of the characteristic line a in FIG. 3, which shows the change in the opening degree of the air mix door with respect to the temperature difference, determines the response sensitivity of the air mix door, and if this slope θ is large, the door opening degree with respect to the temperature difference changes rapidly. Therefore, the room temperature reaches the set temperature quickly, but when the set temperature is exceeded, the same phenomenon (so-called overshoot) occurs and it takes time for the room temperature to reach the set temperature _T3 , as shown by curve C in Figure 4. It takes. Further, in this case, since the sensitivity is good, the degree of door opening changes rapidly in response to a slight change in temperature difference due to external disturbances, which causes the problem that the room temperature becomes unstable. On the other hand, when the slope θ of the characteristic line a is small, the change in the opening degree of the air mix door with respect to the temperature difference is small, so that it takes time for the room temperature to reach the set temperature as shown by D in FIG. 4. Furthermore, when a characteristic line is set between characteristic lines a and b, the problems of both characteristic lines a and b are alleviated, but still occur.

The present invention has been made in view of the above points, and in order to accurately control the temperature inside the vehicle interior, when the temperature difference between the set temperature and the room temperature is less than a predetermined value, the temperature difference exceeds the predetermined value. The slope of the air mix door opening characteristic curve with respect to temperature difference is smaller than that of the previous model.

Next, the present invention will be explained based on the drawings.

FIG. 5 shows a block diagram of a control circuit for an air conditioner according to the present invention, in which 31 is a room temperature detection sensor, 32 is a room temperature setting device, and 33 is an air conditioning operation switch. Signals from these are sent to a discrimination circuit 34. is input. In the discrimination circuit 34, the temperature setting device 3
The temperature difference signal between the set temperature signal from 2 and the room temperature signal from the room temperature sensor 31 is determined, and the signal output from the air conditioning operation switch 33 is determined, and the following determination is made.

(1) When the air conditioning activation signal is output from the air conditioning activation switch 33 and the temperature difference is greater than the predetermined value B in FIG. 7, the air mix door is fully closed or fully opened.

(2) After that, until the temperature difference reaches the set value C, the opening degree of the air mix door is controlled according to pattern b shown in FIG.

(3) After operating in pattern b, when the temperature difference reaches the set value C, the opening control of the air mix door is switched to pattern a shown in FIG.

In FIG. 5, 36 indicates the air conditioning operation pattern, that is, the opening degree of the air mix door is determined by the signal from the discrimination circuit 34, whether it is fully closed or fully open, pattern a or pattern b.
This is a switching circuit for changing the pattern, and by switching the pattern, the power servo control circuit 37 is controlled, and a room temperature control device such as the air mix door 38 is controlled. That is, when the air conditioning operation switch 33 is turned on, the temperature difference is calculated, and when the temperature difference is larger than the predetermined value B, the air mix door is fully closed or fully opened. Controlled by pattern b. Thereafter, when the room temperature approaches the set temperature and the difference in temperature becomes less than the set value C, the control of the air mix door is switched to pattern a, and the control is continued. FIG. 7 shows changes in the opening degree of the air mix door with respect to such temperature differences.

By performing such control, it is possible to rapidly bring the indoor temperature close to the set temperature during air conditioning operation, and to perform stable conventional control after the temperature approaches the set temperature.

FIG. 8 shows a detailed circuit configuration of an embodiment of the switching circuit 36, in which 40 is a differential amplifier, and electrical signals V _R , 40 of the room temperature T _R and the set temperature T _s ,
The difference in V _s is output as V ₀₁ . This characteristic is shown in Figure 9A. The _operational amplifiers 41 _{and 42} constitute a window comparator with the characteristics _shown in FIG. High) level. 43 is an oscillator that generates a clock signal, and 44 is a JK master/slave flip-flop, the truth table of which is shown in FIG. As can be seen from this truth table, the air conditioning operation switch 33
When turned on, the air conditioning operation signal changes from the L (low) level (OV) to the H level (+), and the clearing of the flip-flop 44 is released.

Now, if the temperature difference between the set temperature T _s and the room temperature T _R is greater than a certain level, as is clear from the characteristics shown in Figure 9 (b), V ₀₂ will be at the L level, and therefore the output Q will also be It becomes L level, and transistor 45
is off. When the temperature difference between the set temperature T _s and the room temperature T _R falls within a certain range, V ₀₂ changes to H level, so the output Q becomes H level, and transistor 45
is conductive.

FIG. 11 shows the circuit configuration of another embodiment of the switching circuit.

50 is a differential amplifier, which outputs the difference between the electrical signals V _R and V _s of the room temperature T _R and the set temperature T _s as V ₀₃ . This characteristic is the same as in FIG. 9A. Hysteresis comparators 51 (characteristics are shown in FIG. 12A) and 52 (characteristics are shown in FIG. 12B) are
This constitutes a hysteresis window comparator with the characteristics shown in Figure C. In Figure 12 C, room temperature T
When _R approaches the set temperature T _s and the output V ₀₃ goes from V _R5 to V _R6 , the comparator output V ₀₄ goes low.
The level changes from the high level to the H level, and therefore the transistor 53 becomes conductive. Also, when V ₀₄ is at H level, the room temperature T _R changes and V ₀₃ becomes smaller than V _R5 or V
When it becomes larger than _R7 , V ₀₄ changes to L bell,
Transistor 53 becomes non-conductive.

As shown in Fig. 13, the control pattern of the air mix door becomes a rapid pattern (pattern b) when the temperature difference between the set temperature T _s and the room temperature T _R exceeds a certain level, and when they match, the control pattern changes to the conventional pattern (pattern a). ).

FIG. 14 shows an embodiment of the air mix door control signal generation circuit, where 60 is the switching circuit shown in FIG. Do the following. The room temperature sensor 62 is a b-pattern sensor and has a large change in resistance value with respect to temperature changes. The room temperature sensor 63 is an a-pattern sensor, and has less change in resistance value than the room temperature sensor 62. In the switching circuits shown in FIGS. 8 and 11, the transistor 45 or 53
conducts, a relay (not shown) operates and the room temperature sensor is switched from 63 to 62, and as a result, the control pattern of the air mix door is set to a in Figure 11.
The pattern can be switched to pattern b. 64,
65 is a comparator.

As explained above, in the present invention, when the air conditioning operation switch is turned on, a control pattern is adopted in which the air mix door responds quickly when the temperature difference is larger than a preset value, and when the temperature difference is smaller than that value, the response is slow. Since the normal control pattern is used, the room temperature can be rapidly brought close to the set temperature, and when it reaches the set temperature, it can be controlled using the conventional control pattern, and the room temperature can be brought to the set temperature in a short time.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a typical configuration of an air conditioner, Fig. 2 is a schematic diagram of a control device used in the air conditioner shown in Fig. 1, Fig. 3 is a conventional air mix door control characteristic, and Fig. 4 is a schematic diagram showing a typical configuration of an air conditioner. A graph showing the room temperature change characteristics when controlled by an air mix door having the characteristics shown in Figure 3, Figure 5 is a block diagram of the air conditioner according to the present invention, and Figure 6 shows the opening degree change characteristics of the air mix door of the air conditioner according to the present invention. 7 is an opening change characteristic diagram when room temperature is controlled using an air mix door having the opening characteristics shown in FIG. 6, and FIG. 8 is a detailed circuit diagram of an embodiment of the switching circuit used in the present invention. 9 is a characteristic diagram of the operational amplifier used in the circuit shown in FIG. 8, FIG. 10 is a truth table of the flip-flop used in the circuit shown in FIG.
Figure 1 is a circuit diagram of another embodiment of the switching circuit.
FIG. 12 is a characteristic diagram of the comparator shown in FIG. 11, FIG. 13 is a characteristic curve showing a control pattern of the air mix door according to the present invention, and FIG. 14 is an air mix door control signal generation circuit. 1... Blower, 2... Air intake port, 3... Evaporator, 4... Heater core, 5... Air outlet,
6...Power servo, 7...Air mix door,
8...Hot water valve, 9...Blower drive motor, 10
...Thermistor, 11, 12...Sliding resistance for room temperature setting.

Claims (1)

[Claims] 1 A room temperature setting means, a room temperature detection means, and when the temperature difference between the temperature set by the room temperature setting means and the room temperature detected by the room temperature detection means is less than a predetermined value, the temperature difference exceeds the predetermined value. 1. A vehicle air conditioner comprising means for controlling temperature by reducing the slope of an opening characteristic curve of an air mix door relative to a temperature difference.