JPS623283Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle air conditioner, and more particularly to a heater unit control device that controls temperature by controlling the amount of hot water flowing into a heater core per unit time by opening and closing a valve.

Until now, this type of control device outputs a pulse signal whose pulse width changes depending on input signals such as outside air temperature, inside car temperature, and inside set temperature, and uses this pulse signal to connect the hot water flow path to the heater core. There is a valve that opens and closes the valve. To increase the amount of air heated by the heater core, increase the valve opening ratio, and to decrease it, increase the opening ratio. FIG. 1 shows this control characteristic, and the amount of heating is affected not only by the valve opening ratio but also by the engine speed. That is, the hot water flowing into the heater core is engine cooling water, and this hot water is supplied by a pump driven by the engine.

In order to eliminate the instability of temperature control caused by such an influence, in addition to providing a solenoid valve 2 at the inlet of the heater core 1, a valve 3 is provided at the inlet and outlet of the heater core 1, as shown in FIG. By returning hot water to the outlet side, the amount of hot water flowing into the heater core 1 is made constant. However, in such an example, piping work is troublesome, and as shown in the flow rate characteristics of valve 3 in Figure 3, valve 3 only acts as a limiter to prevent hot water from flowing in beyond a certain amount. It is not possible to solve the problem of insufficient hot water inflow in the low rotational speed range of the engine. Additionally, this type of valve has the disadvantage that installation and piping are very cumbersome.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a heater unit control device that can perform stable temperature control without being affected by engine speed fluctuations.

The heater unit control device according to the present invention controls the opening time of the hot water inlet valve per unit time according to the temperature setting of a predetermined part, for example, the inside of the vehicle, and also responds to a signal corresponding to the engine speed, for example, the engine speed. The opening time of the hot water inlet valve is corrected by using ignition pulses whose pulse intervals vary.

Examples of the present invention will be described below.

FIGS. 4 and 5 are a block diagram and a flow chart showing the operation progress of the device of the present invention realized using a microcomputer, respectively.

In FIG. 4, a pulse signal from an ignition coil 10 disposed in an engine is sent to a microcomputer (hereinafter abbreviated as microcomputer) 12 through a waveform shaping circuit 11. Microcomputer 1
In step 2, pulses having different pulse intervals depending on the engine speed are received as digital signals. Further, voltage signals from the temperature setter 13 such as the vehicle interior temperature or the heater core outlet temperature are sent to the microcomputer 12 through the AD converter 14. In microcontroller 12, A
- Perform a predetermined calculation based on the signal from the D converter 14 to calculate the basic opening time of the hot water inlet valve 15 by the solenoid valve, and then perform a predetermined calculation based on the signal from the waveform shaping circuit 11. Then, the basic valve opening time is corrected. 16 is a valve opening/closing driving circuit, which opens and closes the hot water inlet valve 15 based on a signal from the microcomputer 12. 17 is a heater core.

Next, the operation transition will be explained with reference to FIG. 5 as well.

When the step is started, initial settings are carried out.
A timer is set in step. This timer is built into a microcomputer and sets the opening/closing cycle of the hot water inflow valve 15.

In step, the microcomputer 12 reads a signal representing the set temperature Ts from the temperature setting device 13 and a signal representing the engine speed N from the waveform shaping circuit 11.

In step, the basic valve opening time t _b of the hot water inlet valve 15 is calculated based on the signal representing the set temperature Ts. Here, the basic valve opening time 0 to tset is changed linearly within the adjustment range of the temperature setting device 13. That is, the basic valve opening time t _b can be calculated from the linear equation t _b =K ₀ ·T _s (where K ₀ is a constant) of the set temperature T _s .

In step, the basic valve opening time t _b is corrected based on the engine speed N. Here, the correction characteristics for the basic valve opening time are determined in advance through experiments and a correction calculation formula is obtained. That is, the corrected valve opening time t _r can be calculated from the quadratic expression of the engine rotation speed N and the basic valve opening time t _b shown below.

t _r =K ₁・N・t _b +K ₂・N+K ₃・t _b +K ₄ (however, when N<N ₁ ) t _r =K ₅・N・t _b +K ₆・N+K ₇・t _b +K ₈ (However, when N≧N ₁ ) However, K ₁ to K ₈ are constants. In the step, the time elapse is checked, and the timer set in the step is counted up in the step. -- is executed repeatedly. Then, when the set period t set of the timer has elapsed from the step, a signal specifying the corrected valve opening time _tr is sent from the microcomputer 12 to the valve opening/closing drive circuit 1.
6, and the hot water inflow valve 15 is opened.

Thereafter, the process returns to the step, the timer is set, and the above operation is repeated. On the other hand, the hot water inflow valve 15 is closed after the corrected valve opening time t _r has elapsed. Here, it goes without saying that the timer setting cycle t set ≧ the corrected valve opening time _tr .

As described above, in this embodiment, the hot water inflow valve is opened by calculating the optimum corrected valve opening time t _r according to the change in engine speed at every cycle t set set by the timer built in the microcomputer. It acts on Therefore, the temperature can be maintained at a stable level regardless of the engine speed under all driving conditions.

In the above embodiment, an ignition pulse is used as a signal corresponding to the engine speed, but an input circuit for other signals may be provided so that a plurality of types of signals can be selectively used.
Furthermore, the method for obtaining the corrected valve opening time _tr is not limited to the above embodiment. For example, a correction value for the basic valve opening time t _b due to engine rotational speed fluctuations may be stored in advance in a memory, read out each time, and added to the basic valve opening time t _b .

FIG. 6 is a circuit diagram of another embodiment of the present invention realized by an electronic circuit, and FIG. 7 is a chart showing the operation progress of each part thereof.

20 is a circuit that converts ignition pulses having different pulse intervals depending on the engine speed into an analog voltage Va. The conversion circuit 20 is supplied with an ignition pulse that is supplied to an ignition coil 22 that excites an ignition plug 21 . In other words, as the engine speed increases, the interval between ignition pulses becomes narrower and the voltage Va increases; conversely, as the engine speed decreases, the voltage Va increases.
Va also decreases.

Figure 8 shows voltage that changes depending on engine speed
This is a diagram showing Va, and the characteristics change as shown by curves A, B, and C by operating the variable resistor VR. variable resistance
VR is used to switch the strength of temperature control.

Reference numeral 30 denotes an oscillation circuit which outputs a triangular wave signal Vb having a predetermined maximum value and minimum value and a constant period. 40 is a switching circuit, and the voltage
It has a comparator 41 that compares Va and Vb, and turns on and off the transistor _Q2 according to the comparison result. In other words, when the voltage Va<Vb, the transistor
Q ₂ is turned on to open the hot water inflow valve 15 which is a solenoid valve, and when the voltage Va>Vb, the transistor Q ₂ is turned off and the hot water inflow valve 15 is closed. Hot water inflow valve 15
is provided in the hot water flow path to the heater core in the heater unit to turn on the flow of hot water to the heater core.
Turn off.

Here, the maximum value and minimum value of the voltage Vb are set to values that include the voltage Vamax and the voltage Vamin obtained at the highest and lowest engine speeds assumed in advance. With this circuit configuration, when the engine speed changes, the variable resistance
Even if VR is fixed, the voltage
Va changes, and the opening time of the hot water inflow valve 15 is corrected according to the level of this voltage Va. Therefore, if the basic heating condition is set using the variable resistor VR, as long as the voltage Va is within the range between the maximum and minimum values of the voltage Vb, it will flow into the heater core without being affected by changes in engine speed. The average amount of hot water can be kept constant.

As explained above, the present invention is a device that controls the temperature inside the vehicle by controlling the amount of hot water flowing into the heater core of the heater unit by opening and closing the valve.
By using a signal that corresponds to the engine speed, it is possible to obtain a stable outlet air temperature that is independent of the engine speed in all driving conditions, and has high practical value.

The ignition pulse is used to obtain a signal with a level corresponding to the engine speed, but this pulse may vary depending on the type of car, such as a 4-cylinder or 6-cylinder engine. There may be a discrepancy in the response. In this case, the time constant of the CR circuit of the conversion circuit 20 can be changed, or a frequency dividing circuit can be added after the waveform shaping circuit 11 in FIG. 4 to provide multiple input circuit systems and use them selectively. By having the same correspondence relationship, it is possible to increase versatility, and the effect is great.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between valve opening ratio and outlet air temperature in the conventional hot water inflow control method.
Figure 2 shows a conventional control method using a constant flow valve, Figure 3 shows the relationship between engine speed and hot water inflow using this control method, and Figure 4 shows a conventional control method using a microcomputer. A block configuration diagram of an embodiment of the invention, FIG. 5 is a flowchart of its operation,
Fig. 6 is a circuit diagram of another embodiment of the present invention, Fig. 7 is a diagram showing changes in signals and operating states of each part thereof,
FIG. 8 is a characteristic diagram showing the relationship between the voltage at point a in FIG. 6 and the engine speed. In the figure, 10 is an ignition coil, 11 is a waveform shaping circuit, 12 is a microcomputer, 13 is a temperature setting device, 14 is an A/D converter, 15 is a hot water inlet valve, 16 is a valve opening/closing drive circuit, and 17 is a heater core. , 20 is a conversion circuit, 30 is an oscillation circuit, 40 is a switching circuit, 21 is a spark plug, and 22 is an ignition coil.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a vehicle air conditioner equipped with a heater unit that controls the temperature inside the vehicle by controlling the flow rate of hot water per unit time by opening and closing the hot water flow path to the heater core with a valve, a first signal generating means that generates a signal that changes according to the temperature setting of the location where the engine rotates; a second signal generating means that generates a signal that corresponds to the engine rotation speed; and a pulse width that varies depending on the two signals. and a third signal generating means for generating a pulse having the following values as an opening/closing signal for the valve. 2. A heater unit control device for a vehicle air conditioner as set forth in claim 1 of the utility model registration claim, characterized in that a plurality of circuits with different characteristics are selectively provided as the second signal generating means. .