KR100683163B1 - Pump operation control apparatus and thereof control method for hydraulic brake system - Google Patents

Abstract

The present invention relates to a drive control apparatus for a hydraulic pump for generating brake hydraulic pressure and a method of controlling the same, and an object of the present invention is to minimize the driving noise of a hydraulic pump while preventing the hydraulic motor from being stopped. The duty ratio of the PWM signal for driving the hydraulic motor is variable.

The driving control apparatus of the hydraulic pump according to the present invention calculates the minimum driving current of the hydraulic motor based on the hydraulic pressure sensing means for detecting the brake hydraulic pressure in the accumulator, the brake hydraulic pressure in the accumulator sensed by the hydraulic pressure sensing means, and the brake Target current determination means for determining a target current supplied to the hydraulic motor larger than the minimum driving current based on the pressure difference between the hydraulic pressure and the preset target brake hydraulic pressure; and determining the target current if the brake fluid pressure in the accumulator is less than or equal to the predetermined target pressure. And a hydraulic motor control means for driving the hydraulic motor based on the target current determined by the means and the current driving current of the hydraulic motor, and stopping the hydraulic motor if the brake fluid pressure in the accumulator is equal to or greater than a predetermined target pressure.

Description

Hydraulic pump drive control device for hydraulic brake system and control method thereof

1 is a control block diagram of a conventional hydraulic pump drive control apparatus.

2 is a control block diagram of a hydraulic pump drive control apparatus for a hydraulic brake system according to the present invention.

3 is a logic diagram of a driving control method of a hydraulic pump according to the present invention.

4 is a configuration diagram of a hydraulic pump in the present invention.

5 is a graph showing the current and torque characteristics of the hydraulic motor in the present invention.

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

20: low pressure accumulator 21: high pressure accumulator

22: hydraulic pump 23: pressure sensor

24: hydraulic motor 25: current sensor

26: switching element 27: drive unit

28: control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control apparatus for a hydraulic pump for generating brake hydraulic pressure and a control method thereof, and more particularly, to a drive control apparatus and a control method for a hydraulic pump for minimizing drive noise of a hydraulic pump.

In general, hydraulic pumps in hydraulic brake systems such as electrohydraulic brake control, anti-lock brake control and traction control control are mechanically connected to the hydraulic motor so that the piston of the hydraulic pump reciprocates by the rotational movement of the hydraulic motor. do. This reciprocating motion generates a vacuum portion lower than atmospheric pressure at the pump inlet, and the vacuum liquid sucks up the brake fluid in the brake fluid reservoir and discharges it to the accumulator. The brake fluid in the accumulator is supplied to the wheel cylinder when necessary.

As shown in FIG. 1, the hydraulic pump driving device in the conventional hydraulic brake system provided with such a hydraulic pump includes a brake fluid reservoir 1, a hydraulic pump 2, an accumulator 3, a hydraulic motor 4, The pressure sensor 5 and the electronic controller 6 are included.

The brake fluid reservoir 1 is connected to the suction side of the hydraulic pump 2 and stores brake fluid. The accumulator 3 is connected to the discharge side of the hydraulic pump 2. The hydraulic pump 2 pumps the brake fluid from the brake fluid reservoir 1 to increase the brake fluid pressure in the accumulator 3. The hydraulic motor 4 is connected to the hydraulic pump 2 to drive the hydraulic pump 2.

The pressure sensor 5 is connected to the accumulator 3 and detects the brake hydraulic pressure in the accumulator 3.

The electronic controller 6 outputs a control signal for driving the hydraulic motor. When the brake pressure is detected by the pressure sensor 5 and the current pressure of the accumulator reaches the preset target pressure, the hydraulic motor 4 Outputs a control signal for stopping).

The switching element 7 interrupts the supply of the battery voltage Vbat to the hydraulic motor 4 according to the control signal of the electronic controller 6.

In the conventional hydraulic pump drive control apparatus, the hydraulic motor is driven by outputting a pulse width modulation (PWM) signal having a predetermined duty ratio to drive the hydraulic motor.

However, when the duty ratio of the PWM signal is set too high, the driving noise of the hydraulic pump is generated a lot. On the other hand, when the duty ratio of the PWM signal is set too low, the pressure of the accumulator increases as the pressure of the accumulator increases. The piston is prevented from reciprocating due to the pressure difference between the two ends of the piston. As a result, the rotation of the hydraulic motor is forcibly stopped so that an overvoltage higher than the rated driving voltage is applied to the hydraulic motor to drive the hydraulic motor and the hydraulic motor. The furnace may be damaged.

Usually, the rated motor voltage is set in consideration of the counter electromotive force generated by the rotation of the motor when designing a hydraulic motor. For example, if the battery voltage is 12V and the counter electromotive force generated during the rotation of the motor is 4V, the motor is designed to be driven by the rated driving voltage of 8V (12V-4V). When the rotation of the hydraulic motor is stopped, Even when no back EMF is generated in the hydraulic motor, the overvoltage of 12V higher than the rated driving voltage of 8V is supplied, which may damage the hydraulic motor and the driving circuit for driving the hydraulic motor.

The present invention is to solve the above problems, an object of the present invention is to provide a duty of the PWM signal for driving the hydraulic motor in accordance with the pressure of the accumulator to prevent the hydraulic motor is stopped while minimizing the drive noise of the hydraulic pump To vary the ratio.

The present invention for achieving the above object is a drive control apparatus for a hydraulic pump for pumping the brake fluid stored in the brake reservoir by the drive of the hydraulic motor to the accumulator, comprising: hydraulic pressure sensing means for detecting the brake fluid pressure in the accumulator; Target current determining means for determining a target current supplied to the hydraulic motor based on a pressure difference between the brake fluid pressure in the accumulator sensed by the hydraulic pressure sensing means and a predetermined target brake fluid pressure; If the brake hydraulic pressure in the accumulator is less than or equal to the target brake hydraulic pressure, the hydraulic motor is driven so that the current driving current of the hydraulic motor follows the target current determined by the target current determining means, and the brake hydraulic pressure in the accumulator is the target brake hydraulic pressure. If it is above, it is characterized by including a hydraulic motor control means for stopping the hydraulic motor.

In addition, the present invention is a drive control method of a hydraulic pump for pumping the brake fluid stored in the brake reservoir to the accumulator by the operation of the hydraulic motor, the current discharge pressure of the hydraulic pump to sense the current of the hydraulic motor at the discharge pressure Calculating a minimum driving current required for driving; Calculating an output current by proportional control with respect to a pressure difference between the detected current pressure and a preset target pressure, and then calculating a target current by adding the calculated output current and the calculated minimum driving current; Sensing the current driving current of the hydraulic motor and driving the hydraulic motor by varying a PWM signal so that the current driving current follows the target current by proportional integral control with respect to the current deviation from the calculated target current. It is done.

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

2 is a control block diagram of a hydraulic pump drive control apparatus for a hydraulic brake system according to the present invention.

As shown in FIG. 2, the hydraulic pump driving control apparatus according to the present invention pumps the brake fluid from the brake fluid reservoir 20 in which the brake fluid is stored, and supplies the hydraulic fluid to the accumulator 21 and the hydraulic pump 22. To the hydraulic motor 24 and the hydraulic motor 24 for driving the hydraulic pump 22 by applying the pressure sensor 23 for detecting the brake fluid pressure supplied to the accumulator 21 and the battery voltage Vbat. The current sensor 25 for detecting the current to be supplied, the switching element (FET) 26 for interrupting the supply of the battery voltage Vbat to the hydraulic motor 24, the switching element 26 in accordance with a predetermined control signal Reads the values detected from the driving unit 27, the pressure sensor 23 and the current sensor 25 for driving and performs a predetermined operation, and PWM of a predetermined duty ratio for controlling the driving unit 27 according to the operation result. A control unit 28 for outputting a control signal is included.

The brake fluid reservoir 20 is connected to the suction side of the hydraulic pump 22 and stores brake fluid. The accumulator 21 is connected to the discharge side of the hydraulic pump 22. The hydraulic pump 22 pumps the brake fluid from the brake fluid reservoir 20 to increase the brake fluid pressure in the accumulator 21. The hydraulic motor 24 is connected to the hydraulic pump 22 to drive the hydraulic pump 22.

The pressure sensor 23 is connected to the accumulator 21 to sense the brake fluid pressure in the accumulator 21.

The controller 28 outputs a PWM control signal for driving the hydraulic motor and receives the brake fluid pressure sensed by the pressure sensor 23 based on the pressure difference between the present pressure of the accumulator 21 and the preset target pressure. The target current required for driving the hydraulic motor 24 is calculated. When the target current is calculated, the controller 28 senses the current current of the hydraulic motor 24 detected by the current sensor 25 to compensate for the temperature characteristic change of the hydraulic motor 24 due to mechanical causes. The duty ratio of the PWM signal is varied so that the current follows the target current.

The current sensor 25 is replaceable with a shunt resistor, and the unidirectional diode D protects the hydraulic motor 24 from reverse current.

Hereinafter, a drive control method of a hydraulic pump according to the present invention will be described with reference to a preferred embodiment.

3 is a logic diagram of a driving control method of a hydraulic pump according to the present invention.                     

As shown in FIG. 3, first, the control unit 28 substitutes the present pressure P0 of the accumulator 21 detected by the pressure sensor 23 into Equation 4 to be described later as an initial value of the hydraulic motor 24. Find the minimum drive current (I) to stop the operation of the hydraulic motor.

Looking at the method for obtaining the minimum drive current of the hydraulic motor with reference to Figures 4 and 5, as shown in Figure 4, the hydraulic pump 22 is eccentric to the hydraulic motor 24 shaft to reciprocate the rotational motion of the motor The circular cam 22a which converts into the structure consists of a structure which pushes the piston 22b.

Here, since the force F acting on the piston 20b is the product of the pressure P of the accumulator 21 and the piston cross-sectional area S, it can be expressed by the following equation (1).

F = P × S -------- (Equation 1)

The point at which the maximum torque is generated in the hydraulic motor 24 is when the shaft center and the center are 90 ° with the movement direction of the piston 8b. At this time, the torque (T) is a product of the force (F) acting on the piston (8b) and the eccentric amount (d), it can be expressed by the following equation (2).

T = F × d ------- (Equation 2)

If you rearrange Equation 2 using Eq. (1),

T = P × S × d

In general, a DC motor is used as the hydraulic motor 24, and the current and torque characteristics of the DC motor are in a proportional relationship as shown in FIG.

This can be summarized as in Equation 3.                     

I = K0 + K1 × T -------- (Equation 3)

(Where K0 and K1 are constants depending on the motor)

By substituting Equation 2 into Equation 3,

I = K0 + K1 × (P × S × d) ------ (Equation 4)

Since the piston cross-sectional area (S), the eccentricity (d), K0 and K1 are predetermined, if the pressure (P) of the accumulator 21 is known, the rotation of the hydraulic motor at a specific pressure of the accumulator 21 is continued. It is possible to find the minimum driving current.

On the other hand, after obtaining the minimum driving current of the hydraulic motor 24, the control unit 28 is proportional control (Proportion control) so that the current pressure (P0) detected by the pressure sensor 23 follows the target pressure (P1) preset Perform

The control unit 28 calculates the target current I1 (I + ΔI) by adding the output current ΔI obtained by the proportional control and the minimum driving current I obtained above. Since the pressure difference between the present pressure P0 and the target pressure P1 is large at first, the output current by proportional control is also initially large and gradually decreases as the present pressure reaches the target pressure.

When the target current is determined, the controller 28 reads the current current I0 of the hydraulic motor 24 from the current sensor 23 so that the current current I0 follows the target current I1. Perform an integral control. At this time, the main purpose of the proportional integral control is to eliminate the current deviation Δi which is the difference between the target current command and the current current command. In proportional integral control, the controller 28 compares the sign of the current deviation Δi obtained by subtracting the current current command signal from the target current command signal with the current deviation of the previous step, and the sum of the accumulated current deviation is zero since the sign is reversed. Until the duty ratio of the PWM signal of the hydraulic motor 24 is varied to drive the hydraulic motor.

At this time, the duty ratio of the PWM motor of the hydraulic motor is not directly set from the target current, and a current sensor is further provided to perform the proportional integral control of the current and the target current to change the duty ratio. This is because by detecting and using it, it is possible to reflect the characteristic change according to the temperature change of the coil of the hydraulic motor and the counter electromotive force according to the rotation of the hydraulic motor.

As described in detail above, the present invention has an effect of preventing the hydraulic motor from stopping before the pressure of the accumulator reaches the target pressure, thereby preventing damage to the hydraulic motor and the driving circuit of the hydraulic motor.

The present invention does not drive the hydraulic motor with unnecessary large current has the effect of reducing the driving noise of the hydraulic pump as much as possible.

Claims (6)

In the drive control apparatus of the hydraulic pump for pumping the brake fluid stored in the brake reservoir by the accumulator by driving the hydraulic motor, Hydraulic pressure sensing means for detecting the brake fluid pressure in the accumulator, Target current determination means for determining a target current supplied to the hydraulic motor based on a pressure difference between the brake hydraulic pressure in the accumulator sensed by the hydraulic pressure sensing means and a predetermined target brake hydraulic pressure; If the brake hydraulic pressure in the accumulator is less than or equal to the target brake hydraulic pressure, the hydraulic motor is driven so that the current driving current of the hydraulic motor follows the target current determined by the target current determining means, and the brake hydraulic pressure in the accumulator is the target brake hydraulic pressure. If it is, the drive control apparatus for a hydraulic pump comprising a hydraulic motor control means for stopping the hydraulic motor. The method of claim 1, The hydraulic motor control means further comprises a current sensing means for detecting a drive current flowing in the hydraulic motor drive control apparatus of the hydraulic pump. The method of claim 1, The target current determining means calculates the minimum drive current of the hydraulic motor at the time when the hydraulic motor generates the maximum torque at the pressure in the accumulator sensed by the pressure sensing means. . The method of claim 1, The target current determining means calculates a minimum driving current of the hydraulic motor based on the brake hydraulic pressure in the accumulator sensed by the hydraulic pressure sensing means, and based on the pressure difference between the brake hydraulic pressure and a predetermined target brake hydraulic pressure. And a target current supplied to the hydraulic motor is greater than the minimum driving current. The method of claim 1, And the hydraulic motor control means varies the duty ratio of the PWM signal with respect to the target current supplied to the hydraulic motor so that the current driving current of the hydraulic motor estimates the target current. In the drive control method of the hydraulic pump for pumping the brake fluid stored in the brake reservoir by the accumulator by driving the hydraulic motor, Sensing the current discharge pressure of the hydraulic pump to calculate the minimum drive current required to drive the hydraulic motor at the discharge pressure; The output current is calculated by proportional control with respect to the pressure difference between the detected current pressure and the preset target pressure, and then the target current is calculated by summing the calculated output current and the calculated minimum driving current. Sensing the current driving current of the hydraulic motor and driving the hydraulic motor by varying a PWM signal so that the current driving current follows the target current by proportional integral control with respect to the current deviation from the calculated target current. Drive control method of hydraulic motor.

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