KR100799486B1 - Device for driving solenoid valve in a vehicle - Google Patents

Abstract

The present invention relates to a device for driving a solenoid valve for regulating brake fluid of a wheel cylinder in an anti-lock brake system. In particular, the switching characteristic of the switching device for driving a solenoid valve is improved to supply a stable constant current to the solenoid coil. The present invention relates to a solenoid valve driving device for stably operating a valve.

The present invention uses a non-inverting amplifier that requires a relatively small amount of passive elements instead of a conventional differential amplifier which requires a relatively large amount of passive elements for amplifying the output signal of the shunt resistor for detecting current flowing through the solenoid coil. Minimizing signal delay in the amplifier improves switching characteristics in switching devices that switch the current flowing through the solenoid coil. As a result, a stable constant current is supplied to the solenoid coil so that the solenoid valve is operated stably to improve the brake performance.

Description

Solenoid valve driving device {Device for driving solenoid valve in a vehicle}

1 is a control circuit diagram of a solenoid valve driving apparatus according to the prior art.

FIG. 2 is a graph of current flowing through the solenoid coil of FIG. 1. FIG.

3 is a brake hydraulic control circuit diagram of the anti-lock brake system to which the solenoid valve driving device according to the present invention is applied.

4 is a control circuit diagram of a solenoid valve device according to an embodiment of the present invention.

FIG. 5 is a graph of current flowing through the solenoid coil of FIG. 4. FIG.

* Description of the symbols for the main functions of the drawings *

10 solenoid valve 20 field effect transistor

30: shunt resistor 40: non-inverting amplifier

50: comparator 60: microcomputer

The present invention relates to a solenoid valve driving apparatus, and more particularly, to a solenoid valve device for improving brake braking force by maintaining a constant current flowing through a solenoid valve used for brake hydraulic pressure control of a vehicle to improve solenoid valve characteristics.

In general, a vehicle equipped with an anti-lock brake system (hereinafter referred to as ABS) is equipped with solenoid valves at the inlet and outlet sides of four wheels. In such ABS vehicles, the braking force is a friction force between the wheel of the vehicle and the road surface. If it starts to skid over, the solenoid valve on the wheel will actuate the pressure to relieve the pressure, and when the vehicle starts to roll, the solenoid valve will actuate the wheels continuously. By this ABS operation, the vehicle does not slip and braking is performed stably.

1 is a control circuit diagram of a conventional solenoid valve device. As shown in FIG. 1, a conventional solenoid valve device includes a solenoid valve 1 for controlling brake hydraulic pressure of a vehicle, a field effect transistor (FET) 2 for turning the solenoid valve 1 on or off, and a coil in the solenoid valve. A shunt resistor (R1) (3) for detecting the current flowing in (L), a differential amplifier (4) for differentially amplifying the output signal of the shunt resistor (R1), and an output signal and a reference signal of the differential amplifier (4). A comparator 5 for comparing and outputting a corresponding signal, a second transistor Q2 having a base connected to an output terminal of the comparator 5, a drain terminal connected to an emitter terminal of the first transistor Q2, and an emitter terminal A control unit for enabling or disabling the constant current regulation function according to the grounded first transistor Q1 and an output port connected to the base terminal of the first transistor Q1 to turn on / off the first transistor Q1. 6).                         

The differential amplifier 4 is an operational amplifier that enters two inverting (-) and non-inverting (+) input terminals and outputs a difference of input signals. A low pass filter consisting of a resistor R2 and a capacitor C1 and a resistor R3 are connected in series between the non-inverting input terminal + and one terminal of the shunt resistor R1. In addition, a low pass filter made of a resistor R4 and a capacitor C2 and a resistor R6 are connected in series between the inverting input terminal (−) and the other terminal of the shunt resistor. A negative feedback loop is formed between the inverting input terminal (-) and the output terminal through the resistor R7.

However, in the related art, the switching characteristics of the field effect transistor are relatively low due to the passive elements by using a differential amplifier which requires a relatively large number of passive elements such as resistors and capacitors. As shown, the wave period T and amplitude A of the current supplied to the solenoid coil become relatively large, so that the current is not stabilized at 1 A, the desired constant current. As a result, the solenoid valve may be operated relatively unstable, which may adversely affect the brake performance.

The present invention is to solve the above problems, an object of the present invention to improve the switching characteristics of the solenoid valve drive switching device to provide a stable constant current to the solenoid coil to provide a solenoid valve drive device for improving the brake performance. There is.

Solenoid valve driving apparatus according to the present invention for achieving the above object is a brake hydraulic pressure control solenoid valve, switching unit for turning on or off the solenoid valve, current detection unit for detecting the current flowing in the coil of the solenoid valve, the current detection unit A solenoid valve device comprising an amplifier for amplifying an output signal of a predetermined level and a constant current regulation circuit for performing constant current regulation according to the output signal of the amplifier, wherein the amplifier is an inverting input terminal for minimizing a delay of an output signal. Is grounded, and the non-inverting input terminal is a non-inverting amplifier connected to one terminal of the current detection unit.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

3 is a brake hydraulic control circuit diagram of the anti-lock brake system to which the solenoid valve device according to the present invention is applied. As shown in FIG. 3, the brake pedal 1 operated by the driver during braking, and the power booster 1a and the master cylinder 1b for generating brake pressure by amplifying the force transmitted from the pedal 1. Is prepared.

Then, a plurality of solenoid valves 3 and 4 for supplying the generated brake hydraulic pressure to the wheel cylinder 2, and a low pressure accumulator (LPA) 5 in which brake fluid discharged from the wheel cylinder 2 are temporarily stored. And a motor 6 and a pump 7 for pumping the brake fluid stored in the low pressure accumulator 5 to reflux to the master cylinder 1b or the wheel cylinder 2, which are installed compactly in the modulator block. do.

The solenoid valves 3 and 4 are respectively disposed at the inlet side and the outlet side of the wheel cylinder 2 for inflow or outflow of the brake hydraulic pressure generated in the master cylinder 1b and supplied to the wheel cylinder 2, The solenoid valve 3 is a normal open type (NO) solenoid valve that maintains an open state and the solenoid valve 4 is a normal closed type (NC) solenoid valve that maintains an off state.

Opening or closing the solenoid valves 3 and 4 during ABS braking causes the brake pressure in the wheel cylinder 2 to be reduced, maintained, and increased to brake the vehicle. That is, in the case of ABS braking, the solenoid valve 3 is first closed and the solenoid valve 4 is opened to release the brake pressure of the wheel cylinder, thereby reducing the brake pressure at the wheel cylinder. Subsequently, the solenoid valve 4 is closed to maintain the brake pressure at the wheel cylinder 2, and the solenoid valve 3 is opened to increase the brake pressure.

Hereinafter, the reference numerals of the normally open solenoid valve 3 and the normal closed solenoid valve 4 will be uniformly described as 10.

4 is a control circuit diagram of a solenoid valve device according to an embodiment of the present invention. As shown in FIG. 4, the solenoid valve device according to the present invention includes a solenoid valve 10 for controlling hydraulic pressure of a vehicle, a switching unit 20 for turning the solenoid valve 10 on or off, and a solenoid valve 10. A current detector 30 for detecting a current flowing through the coil L, an amplifier 40 for amplifying the output signal of the current detector 30 to a predetermined level, and a switching unit according to the output signal of the amplifier 40. And a constant current regulation circuit Q1, Q2, 60 which controls the driving of the 20 to perform a constant current regulation function on the coil L in the solenoid valve 10.                     

The constant current regulation circuit includes a comparator 50 for comparing the output signal of the amplifier 40 with a reference signal and outputting the corresponding signal, a second transistor Q2 having a base connected to the output terminal of the comparator 50, A first transistor Q1 having a drain terminal connected to the emitter terminal of the first transistor Q2 and an emitter terminal grounded, and an output port connected to the base terminal of the first transistor Q1 are connected to the first transistor Q1. And a controller 60 for enabling or disabling the constant current regulation function upon turning on / off.

The current detector 30 includes a shunt resistor R1 connected in series between the solenoid coil L and the ground side.

The amplifying unit 40 has one output terminal and two inverting (-) and non-inverting (+) input terminals, and converts a signal input to the non-inverting (+) input terminal into a signal having a predetermined level of in phase It is a non-inverting amplifier to output. The non-inverting input terminal (+) is connected to one terminal of the shunt resistor (R10). In addition, a resistor R11 is connected between the inverting input terminal (-) and ground. A negative feedback loop is formed between the inverting input terminal (-) and the output terminal through the resistor R12. By adjusting the resistance values of the resistors R11 and R12, the voltage gain of the amplified output signal is adjusted. The output terminal of the non-inverting amplifier 40 is again connected to the input terminal of the comparator 50, and a reference voltage source connected between the non-inverting input terminal (+) and the ground of the comparator 50 is connected. Accordingly, the comparison unit 50 compares the output signal of the non-inverting amplifier 40 with the reference signal by the reference voltage source, and outputs a high level signal or a low level signal to the second transistor Q2 to output the second transistor. Turns Q2 on or off. At this time, when the second transistor Q2 is turned on by the output signal of the comparator 50, the controller 60 turns on the first transistor Q1 to enable the constant current regulation function. As the current is supplied to the gate terminal of the field effect transistor (FET) of the driver 20 to turn on the FET, the current by the battery is supplied to the solenoid coil 10.

As described above, the current flowing through the solenoid coil L is configured by replacing the amplifier 40 with a non-inverting amplifier that requires a relatively small number of passive elements instead of a conventional differential amplifier requiring a relatively large amount of passive elements. By increasing the wave period and amplitude of the passive element which adversely affects the constant current regulation, passive elements such as R11 and R12 can be drastically reduced. As a result, the delay of the signal output from the non-inverting amplifier is relatively shortened by the time constant of the passive element, so that the switching of the field effect transistor 20 is relatively faster, thereby improving the switching characteristics. Thus, as shown in FIG. 5, the wave period of the current flowing through the solenoid coil is shortened from T to T 'and the amplitude is reduced from A to A'. Accordingly, it is possible to stably supply the constant current close to the desired target current (for example, 1A), so that the operation of the solenoid valve is performed stably. The wave period and amplitude of the current flowing through the solenoid coil L are greatly reduced, so that the current is stabilized around 1A.

As described in detail above, the present invention provides a switching characteristic of a switching device for switching a solenoid valve by reducing signal delay in an amplifier by using a non-inverting amplifier that requires relatively few passive elements instead of a conventional differential amplifier. By improving and supplying a stable constant current to the solenoid valve, the brake performance is improved.

Claims (3)

The brake hydraulic control solenoid valve 10, the switching unit 20 for turning on or off the solenoid valve 10, the current detection unit 30 for detecting a current flowing in the coil (L) of the solenoid valve 10, the A solenoid comprising an amplifier 40 for amplifying the output signal of the current detector 30 to a predetermined level, and constant current regulation circuits Q1, Q2, 60 for performing constant current regulation according to the output signal of the amplifier 40. In the valve device, The amplifying unit 40 is a solenoid valve device, characterized in that the inverting input terminal is grounded to minimize the delay of the output signal, the non-inverting input terminal is a non-inverting amplifier connected to one terminal of the current detector (30) . The non-inverting amplifier 40 of claim 1, wherein the inverting input terminal and the output terminal form a closed loop, and the resistance value provided with a resistance between the inverting input terminal and the output terminal, and the inverting input terminal and the ground, respectively. Solenoid valve device characterized in that for adjusting the voltage gain. 3. The solenoid valve device according to claim 2, wherein the resistance values are set to adjust the voltage id of the signal output from the output terminal.

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