JPS6229999B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for a vehicle control device, for example, a drive circuit for a control device such as a blower motor for introducing inside and outside air in a vehicle air conditioner.

The rotation speed of the above blower motor is mainly controlled according to the setting value of the cabin temperature setting device.
As shown in the figure, this motor M is connected to the output stage of a transistor T, and the input stage of this transistor T is supplied with the output from an amplifier A which amplifies the signal from the input circuit I. The above input circuit I consists of a plurality of resistors R connected in parallel to an output terminal S, and an input terminal P connected to each resistor R, and converts digital signals supplied from all input terminals P into analog signals. This signal is supplied from S to an amplifier A, which amplifies this signal and supplies it to the input stage of a transistor T. Based on the operation of this transistor T, an input from a power supply V _CC is supplied to a blower motor M, The rotation speed is set to the optimum value.
In this case, the output stage of the transistor T is connected to the amplifier A via the feedback circuit F, thereby suppressing fluctuations in the rotational speed of the motor M due to fluctuations in the output from the amplifier A.

However, according to the above-mentioned conventional drive circuit, when the voltage of the power supply V _CC fluctuates, the fluctuation directly affects the motor M, causing the rotational speed of the motor M to fluctuate and cause unevenness in the rotational speed. This has the disadvantage that the amount of air blown out from the vehicle air conditioner and the temperature of the air fluctuate because the volume of the inside air and outside air introduced fluctuates, resulting in a reduction in the feeling given to the occupants.

An object of the present invention is to eliminate the above-mentioned drawbacks by making the input voltage of a vehicle control device such as a blower motor independent of the power supply voltage, thereby preventing fluctuations or unevenness in the rotational speed of the control device due to fluctuations in the power supply voltage. This will be explained in detail below using examples.

FIG. 2 is a circuit diagram showing an example of a drive circuit for a vehicle control device according to the present invention, particularly a circuit for controlling the drive of a control device consisting of a blower motor. The voltage V ₊ at the connection point between the resistors 3 and 4 that divides the voltage V _CC of the power supply 9 is supplied to the side, and the voltage V ₅ from the constant voltage source 10 is supplied to the inverting input side of the resistor 5.
Further, the signal from the output terminal ₆₁ of the input circuit I is supplied. The input circuit I mentioned above acts as a D-A conversion circuit, and the output terminal 6
Resistors 11 to ₁ (n) are connected in parallel in order from the one with the largest resistance value to V 1 and the input voltage V ₁ is connected to one end of each resistor 11 to 1(n).
The digital signal supplied to each input _{terminal 62} is converted into an analog signal and output from the output _{terminal 61} to the operational amplifier 1.
Send it to the inverted input side of. The output stage of the operational amplifier 1 is connected via an amplification transistor 7 to the input stage of a motor control transistor 8, which has a blower motor M connected to its output stage. Above motor M
One end is connected to the power supply 9 of the vehicle, and the other end is connected to the collector side of the transistor 8.
A feedback resistor 2 is connected between the connection point between the motor M and the transistor 8 and the inverting input side of the operational amplifier 1. The operational amplifier 1 has a capacitor 1a in the feedback circuit and a resistor 1b on the non-inverting input side, and the transistor 7 has a resistor 7a and a resistor 7b on the base side and a resistor 7c on the collector side. , the transistor 8 has a resistor 8a on the base side.

Here, let the resistance values of resistor 2, resistor 3, resistor 4, and resistor 5 be R ₂ , R ₃ , R ₄ , and R ₅ , and the resistance values of resistor 11 to resistor 1(n) respectively.
R ₁₁ to R _1(o) . (However, n is 1, 2, 3,
...) In this case, the resistance value of the resistor 11 is set to be the smallest, and as the constant n increases, the resistance value of that resistor is set to increase sequentially. Specifically, R _1(o+1) = 2 ⁿ R ₁₁ … satisfies the formula. Further, regarding the voltage V ₊ , the following formula is satisfied: V ₊ =R ₄ /R ₃ +R ₄ V _CC . Here, when calculating the input voltage V ₀ of motor M, the input resistance of D-A is
There are four cases: R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ .

V ₀ =V _CC +(V ₁ −V ₊ )R ₂ /R ₁₁ +(V ₂ −V ₊ )R ₂ /R ₁₂ +(V ₃ −V ₊ )R ₂ /R
₁₃ + (V ₄ −V ₊ )R ₂ /R ₁₄ + (V ₅ −V ₊ )R ₂ /R
₅ -V ₊ , and rearranging the above formula, V ₀ = (V ₁ /R ₁₁ +V ₂ /R ₁₂ +V ₃ /R ₁₃ +V
₄ /R ₁₄ +V ₅ /R ₅ )R ₂ +V _CC -(1+R ₂ /R ₁₁ +R ₂ /R ₁₂ +R ₂ /R ₁₃
+R ₂ /R ₁₄ +R ₂ /R ₅ )V ₊ .... By substituting the expressions and expressions into the equations and rearranging them, V ₀ = (V ₁ +V ₂ /2+V ₃ /4+V ₄ /8)R ₂ /R _1
1 +R ₂ /R ₅ V ₅ +{1-(1+15R ₂ /8R ₁₁ +R ₂ /R ₅ )R
₄ /R ₃ +R ₄ }V _CC .... In order to enable V ₀ to ignore the influence of V _CC , the coefficient of the V _CC term in the equation may be set to 0.
Therefore, the conditional expression is determined as follows.

1-(1+ _15R2 / _8R11 + _R2 / _R5 ) _R4
/R ₃ +R ₄ =0 ∴15R ₂ /8R ₁₁ +R ₂ /R ₅ =R ₃ /R ₄ ...
The resistances 1(n), 2, 3,
If 4 and 5 are set, fluctuations in the power supply voltage can be ignored.
Further, the minimum voltage of V ₀ is R ₂ /R ₅ V ₅ from the formula.

Therefore, even if the voltage of the power supply 9 changes by setting the resistance value of each resistor so as to satisfy the formula, this means that the input voltage of the blower motor M V ₀
Since it has nothing to do with the rotation speed, it is possible to suppress fluctuations in the rotation speed, and therefore, it is possible to introduce a specified amount of outside air and inside air. It is possible to accurately adjust the value according to the setting amount of the setting device, and improve the feeling of the passenger.

Although the present embodiment describes a circuit that drives a blower motor, the present invention is not limited to this, but may include a motor for controlling an air mix door that adjusts the mixing ratio of warm air and cold air in a vehicle air conditioner. The present invention can be similarly applied to a circuit that drives a control device, or can be similarly applied to a drive circuit of other control devices in a vehicle.

As explained above, according to the present invention, the voltage at the connection point between the resistors 3 and 4 connected in series, which divide the power supply voltage, is supplied to the non-inverting input side of the operational amplifier 1, and the voltage at the connection point between the resistors 3 and 4, which are connected in series to divide the power supply voltage, is supplied to the non-inverting input side of the operational amplifier 1, and the The input from the voltage source is supplied through the resistor 5, and the output terminal 6 is connected in parallel to the input terminal ₆ at one end.
₂ , the output of the operational amplifier 1 is supplied to the input stage of the control transistor 8 of the vehicle control equipment, and the control The signal from the output stage of transistor 8 is passed through resistor 2 to operational amplifier 1.
Since the circuit is configured by feeding back to the inverting input side of Fluctuations in the input voltage of devices can be suppressed, and vehicle air conditioners etc. can be controlled in a stable manner at all times.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional drive circuit for a vehicle control device, and FIG. 2 is a circuit diagram showing an embodiment of a drive circuit for a vehicle control device according to the present invention. 1...Operation amplifier, 2, 3, 4, 5...Resistor, 7,
8...transistor, 9...power supply, 10...constant voltage source,
11-1(n)...Resistor, M...Motor, I...Input circuit.

Claims (1)

[Claims] 1 The connection point voltage of two resistors 3 and 4 connected in series that divide the power supply voltage is supplied to the non-inverting input side, and the voltage supplied from the constant voltage source via the resistor 5 and the output terminal to the inverting input side. An operational amplifier is supplied with an output voltage from an input circuit I consisting of a plurality of resistors that are sequentially connected in parallel to _6.1 and each has an input terminal _6.2 at one end, and the output of this operational amplifier is supplied to an input stage. A circuit is constituted by a control transistor 8 of the vehicle control device and a resistor 2 that feeds back the signal from the output stage of the control transistor 8 to the inverting input side of the operational amplifier, and the power supply voltage is applied to the vehicle control device. 1. A drive circuit for a vehicle control device, characterized in that the resistance values of the resistors 2, 3, 4, and 5 and the resistors constituting the input circuit I are set so that fluctuations in the resistance do not occur.