JPS6248776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blower fan control device used when simultaneously operating air conditioners installed at the front and rear of a vehicle compartment.

In recent years, in order to maintain comfortable air conditioning conditions throughout the vehicle interior,
It has been proposed that air conditioners are installed in each of the front and rear parts of the passenger compartment. In such air conditioners, each air conditioner is provided with a blower fan. For this reason, either one or both of the blower fans may be driven to adjust the air volume. On the other hand, the speed of blower fans is usually controlled by duty control in order to be able to finely adjust the air volume.

That is, in the conventional duty control circuit shown in FIG. 1, 1f is an air volume setting device for the front air conditioner, 1r is an air volume setting device for the rear air conditioner, and 2
3 is a sawtooth wave oscillator, 3 is a comparator that outputs a pulse signal _Pf with the on/off time ratio (duty ratio) determined by the setting signal e f of the air volume setting device 1f, and 4 is the setting signal e _r of the air volume setting device 1r. a comparator that outputs a pulse signal Pr with a predetermined on/off time ratio;
5 and 6 are transistors that are controlled on and off by pulse signals Pf and Pr, respectively; 7f is a drive motor for a front air conditioner blower fan driven by transistor 5; and 7r is a rear air conditioner rotationally driven by transistor 6. drive motor for a blower fan (for example, "Fundamentals and Applications of Precision Small Motors" published by Sogo Denshi Publishing Co., Ltd., Volumes 230 to 231)
(See page 53-87553).

The blower fan is controlled by the above circuit.
As shown in the time chart in the figure, taking the drive of a blower fan for a front air conditioner as an example, the setting signal e _f of the air volume setting device 1f and the sawtooth wave signal from the sawtooth wave oscillator 2 are connected to the comparator 3. When the sawtooth wave signal exceeds the setting signal e _f , the comparison output becomes H level and turns on the transistor 5, and when the sawtooth signal falls below the setting signal e _f , the comparison output becomes L level and transistor 5
is turned off, and the transistor 5 is turned on and off every cycle of the sawtooth signal by such a pulse signal _Pf .
The transistor on time within a period is adjusted to increase. Similarly, the rotation of the drive motor 7r for the rear air conditioner is also controlled in accordance with the setting signal e _r of the air volume setting device 1r.

Here, the drive currents If and Ir flowing through the drive motors 7f and 7r under the control of the blower fan as described above are
, at the beginning of each cycle when the sawtooth signal starts rising at a predetermined slope, both transistors 5 and 6 are always turned on, and the drive motors 7f and 7 are turned on.
Drive currents If and Ir flow through each of r, and the current I supplied from the battery to the motors 5 and 6 is the drive current
This is the combined current of If and Ir.

Therefore, at each period of the sawtooth signal, the current supplied from the battery to the motors 5 and 6 changes rapidly, causing a pulsation in which the battery power supply voltage repeatedly decreases as the current increases. . This type of pulsation does not affect other devices when power consumption is low, such as during the day, but when power consumption increases and the power supply voltage drops, such as at night, it may affect other devices. The power supply is also affected, for example, when lighting instruments,
There is a problem that the brightness fluctuates.

The present invention has been made in view of the above, and in order to suppress pulsations in the power supply voltage, when the blower fan motors of two air conditioners are driven simultaneously, one of the duty signals for driving each of the blower fan motors is The rising edge of one pulse is made to match the falling edge of the other pulse.

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

FIG. 3 is a block diagram showing one embodiment of the present invention. First, to explain the configuration, 1f is an air volume setting device for the front air conditioner, 1r is an air volume setting device for the rear air conditioner, 2 is a sawtooth wave oscillator, 3 and 4 are comparators that operate as pulse width modulators, and 5 , 6 are transistors for driving the motor, 7f is a blower fan motor for the front air conditioner, and 7r is a blower fan motor for the rear air conditioner, and these structures are the same as the conventional device shown in FIG.

In addition to the above configuration, in this embodiment, an inverting circuit 8 is provided between the sawtooth oscillator 2 and the comparator 4,
An inverted signal e' _s of the sawtooth wave signal e _s is input to one input terminal of the comparator 4 .

The inverting circuit 8 operates as a subtracter. For example, if the sawtooth wave signal e _s is a signal that increases at a constant slope, one input terminal (plus side) of the inverting circuit 8 is set by the variable resistor VR. constant voltage e ₀
By applying , the output becomes e ₀ −e
_s ), and it is possible to output an inverted sawtooth wave signal e′ _s whose change decreases at a constant slope.

Next, the operation of the above embodiment will be explained with reference to the time chart of FIG.

First, the comparator 3 uses the setting signal e _f from the setter 1 f for the sawtooth signal e _s as a reference level, and produces an H level output (on) when e _f > e _s , and when e _f ≦ e _s. This H-L change is repeated every cycle of the sawtooth signal e _s , and the time ratio is determined by the level of the setting signal e _f , and when the setting signal e _f is When the setting signal e f is large, the on time (H level) for each cycle becomes long, and when the setting signal e _f is small, the off time (L level) for each cycle becomes short.
The transistor 5 is turned on and off in accordance with the pulse signal Pf, and each time the transistor 5 is turned on, a drive current Ir flows through the motor 7f, and the rotational speed of the motor 7f changes in proportion to the on-time of the transistor 5.

On the other hand, the comparator 4 is applied with the sawtooth signal e' _s inverted by the inverting circuit 8, and the comparator 4 uses the setting signal e _r from the setting device 1r for the sawtooth signal e _s as a reference level. , an H level output (on) is produced when e _r >e' _s , and an L level output (off) is produced when e _r ≦e' _s . In addition, in FIG. 4, time t _o
Previously, the setting device 1r had set the setting signal e _r1 , and with the adjustment at time t _o , after t _o the setting signal e r1 was set.
The case where _r2 (however, e _r2 > e _r1 ) is set is shown.

Therefore, the comparator 4 has an on/off time ratio determined by the setting signals e _r1 and e _r2 for each period of the sawtooth signal e' _s , and a pulse signal Pf of the comparator 3 for each period. On the contrary, the pulse signal Pr has a reversed phase relationship, first turning off and then turning on.
The transistor 5 controls the motor 7r to turn on and off.

In this way, since the motors 7f and 7r are driven by the pulse signals Pf and Pr whose on and off phases are inverted, _each cycle _is The motor 7r is turned on after the motor 7f is turned off at each time, and as a result, the supply current I from the battery is
If Ir=If, only a current change occurs when only one of the motors 7f and 7r is driven.

Also, the time t _o when the setting signal e _r2 becomes a large value
From now on, the lowest current will be the drive current for either motor 7f or 7r, and motors 7f and 7r will have the lowest current.
The current increases to I = If + Ir in the part where the on state of 2 is superimposed, but the change in current itself is equal to the change in current when either motor 7f or 7r is driven, and the current I is zero. There is no sudden change from the state to I=If+Ir.

Therefore, compared to the conventional device, the change in the current supplied from the battery can be suppressed to half, and since there is no sudden increase in the current, the pulsation of the battery voltage can also be suppressed to less than half compared to the conventional device.

In the above embodiment, the sawtooth wave signal e _s is inverted and inputted to the comparator 4, but even if the signal is replaced as in the case of the comparator 3, the same result will be obtained.

As explained above, according to the present invention, the configuration is changed from on to off at each cycle so that the on/off time ratio is determined by setting adjustment using a sawtooth wave signal of one fixed cycle. One of the blower fan motors is driven by a pulse signal, and a signal obtained by inverting the sawtooth wave signal is used to change the pulse signal from off to on at each cycle so that the on/off time ratio is determined by adjusting the settings. Since the other blower fan motor is driven by a pulse signal with a reversed phase relationship, even if two blower fan motors are operated in parallel, a control state will occur in which both motors are switched from off to on at the same time. The current change when controlling two motors on and off is suppressed to the same current change as when only one motor is turned on and off, and therefore sudden changes in current do not occur. Therefore, there is only a slight drop in battery voltage, and it is possible to significantly suppress the adverse effects on other devices caused by pulsations in battery voltage caused by operating the air conditioner.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional device, and Figure 2 is a block diagram of a conventional device.
3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a time chart showing the operation of FIG. 3. 1f, 1r...Air volume setting device, 2...Sawtooth wave oscillator,
3, 4... Comparator, 5, 6... Transistor, 7f,
7r...Blower fan motor, 8...Reversing circuit.

Claims (1)

[Claims] 1 Drive means 5 and 6 that drive each of the two blower fan motors provided at the front and rear of the vehicle compartment based on two pulse signals Pf and Pr, and duty ratio setting means 1f that sets the duty ratio of the pulse signals. _{. _ _} A blower fan control device for a vehicle air conditioner, characterized in that it has phase shifting means for matching the rising timing of one pulse signal Pf or Pr with the falling timing of the other pulse signal Pr or Pf based on .