DE102007008908A1 - Intake valve chain controlling method for use during anti-blocking brake system regulation process, involves controlling separating valve in such manner that increase in fluid pressure occurs in wheel brake unit with smaller gradients - Google Patents

Abstract

The method involves connecting a separating valve (2) to an upstream of an intake valve (3) in an inlet side. The intake valve is completely opened during the admission of fluid into a wheel brake unit. The separating valve is controlled in such a manner that increase in fluid pressure occurs in the wheel brake unit with gradients smaller than that of a completely opened separating valve. The separating valve is subjected to the flow of fluid, during anti-blocking brake system regulation using homogeneous friction value. An independent claim is also included for an electronically controlled motor vehicle brake system.

Description

The The invention relates to a method according to the preamble of claim 1 and an electronically controlled motor vehicle brake system according to the preamble of claim 7.

It is among others from the DE 10 2005 014 097 A1 known to use in ABS control units for motor vehicle brake systems, but also in so-called vehicle dynamics controllers with additional functions such as ESP, etc., analogously regulating electrically controllable hydraulic valves for controlling the hydraulic pressure. These so-called analog / digital valves (A / D valves) are in principle conventional electromagnetic (solenoid) switching valves, which are controlled by means of a pulse width modulated current (PWM) in such a way that the valve stem occupies a floating position. In this way, a pressure control is possible, provided that the current control can be performed sufficiently accurate and reproducible. This is usually possible without major problems if the einzuregelnde pressure can be adjusted via a pressure sensor in conjunction with a control loop. It is considerably more difficult to carry out a corresponding analog control method without a pressure sensor in the pressure circuit to be regulated.

It are in this context quite a number of pressure control methods become known, dealing with the problem of pressure adjustment of an A / D valve without a pressure sensor in the regulated circuit deal. As is known, the opening flow of the valve is among other parameters depends on the voltage applied to the valve pressure difference. Therefore, the regulator, which has the opening current over the electric current setting regulates the pressure in the to be regulated Circle (for example in the wheel brake cylinder) know. In a brake hydraulic device, to which the invention relates, after all, the form can be sensory so that the problem can be identified by identifying the Reduced pressure in the circuit to be controlled.

to Determination of wheel pressure has already been proposed, a provision wheel pressure in an electronically controlled automotive brake system perform in which in the Radkreisen, z. B. over Inlet and exhaust valves, the pressure at least in part by means of A / D valves is set. For this it is necessary that on the tape and / or at least once in the factory and / or in the vehicle an electronically controlled calibration procedure of the A / D valve, in particular of the intake valve, is performed with the one or more inlet valves with regard to their opening flow behavior calibrated (creation and storage of an opening current characteristic), and during a wheel pressure control process for verification of the wheel pressure the A / D valve, in particular the inlet valve, one Brake circuit by corresponding electrical control of the valve is opened briefly, while the current is measured, which then flows when the valve has just opened (Opening current) and the measured current as a proviso to determine the wheel pressure taking into account the Calibration values determined for the calibration procedure for the corresponding inlet valve is used.

One alternative method for determining the wheel pressure is according to a known model, the valve openings according to duration and scope calculated together with other known To take into account sizes.

in principle can build up pressure in a wheel circle with a conventional Switching valve, an A / D inlet valve or via control panels respectively. If A / D inlet valves are used, the pressure model, which is the drive currents for the A / D inlet valve taken into account, being able to be so accurate that, if necessary existing tolerances of the control valve over a longer period.

The above measures for damping the pressure inlet, such as A / D intake valves or shift louvers, allow for ABS control operations that are more comfortable and quieter compared to ABS control operations with pure-switching intake and exhaust valves. By an A / D inlet valve about the increase in pressure in the wheel brake can be done with a reduced pressure gradient. As a result, disturbing pressure pulsations on the brake pedal and associated noise are reduced. With the noise problem in ABS control operations is also the DE 10 2004 029 A1 apart. As a measure, it is proposed to provide diaphragms in the inlet lines of an ABS / ESP hydraulic unit. For the same purpose, a damping chamber is arranged in the region of the pump outlet, which dampens pressure pulsations of the pump.

The Invention sets itself the goal of an alternative comfortable and Low-noise method for controlling an intake valve chain during an ABS control operation of a fluid pressure controlled Specify wheel brake, wherein the intake valve chain of a in series, associated with the wheel brake inlet valve and an isolation valve that input side of the inlet valve upstream.

These The object is achieved by the method according to claim 1.

Of the Pressure in the wheel brake increases, if at a sufficiently high Form the inlet valve is opened. The inlet valve is preferably a conventional switching valve (no A / D valve or proportional valve). In the inlet channel of the ABS hydraulic power pack is preferably no noise damper intended.

The Isolating valve of the hydraulic device with which the ABS control process is executed is part of hydraulic circuits, the for an active pressure build-up without brake pedal operation necessary. It is a valve, which between Inlet valve of the wheel brake circuit and the connection where the from Driver input form is applied, is switched. It is preferable that normally when no active pressure build-up needed is, the isolation valve is always open. The isolation valve is therefore in particular open without current. It is further preferred that the Isolating valve is an A / D valve. An active pressure build-up always becomes then needed if the electronically controlled braking system without driver's request, brake pressure has to build up, which for example during ESP, TCS or ACC (ESP: Electronic Stability Program; TCS: Traction Control System or ASR: traction control; ACC: Adaptive Cruise Control). These include conventional brake systems preferably at least one pump. That isolation valve is at a active pressure build-up closed to the pressure by means of the pump to increase in the wheel brake circuit.

From the EP 1 023 212 31 For example, there is known an ABS control method in which the isolation valve is initially closed for an accelerated pressure build-up initiated by the pump at the beginning of an ABS control event. The method described allows a high braking performance even with only slightly above the blocking pressure level lying form level. The closing of the isolation valve is switching, that is, the valve is fully closed during the active pressure build-up.

in the In contrast, the inventive leads Method in ESP brake systems for optimization (reduction) the pressure build-up dynamics during ABS control operations, in which the separating valve also targeted, ie in particular with a closed suitable closing current, without an active pump realizing an active pressure build-up. As a result, at least in a part of the control situations a comfort increase (less pressure pulsations on the brake pedal felt) reached become.

Especially Preferably, the above-described control of the isolation valve takes place with a predetermined current, which is an opening pressure in the range of about 1 bar to about 10 bar corresponds. Most notably preferred is an opening pressure of about 3 bar to about 7 bar chosen. By the made precise Activation of the isolation valve can be done with activated pump for the driver noticeable pressure pulsation be reduced. It prevents at the same time that by the activated pump caused an active build-up of pressure in the wheel cylinder as with a fully energized, fully closed isolation valve the case would be.

Prefers is the method of the invention, the isolation valve during an ABS control applied to homogeneous friction with power. In this way it is possible to similar pressure build-up the function of a switch panel or an A / D inlet valve to set a lower gradient. When controlling the Separating valve for a pressure gradient with reduced gradient In particular, the pressurized fluid through a Bypass bypasses the isolation valve. The bypass contains particularly preferably a hydraulic resistance, for example an aperture of a check valve. The hydraulic resistance is preferably in a range of about the hydraulic resistance of one to two conventional switching panels corresponds.

To Beginning of an ABS control and / or after a Reibwertsprung becomes preferably the separating valve is opened. This can be at Need to build up pressure with a high pressure rise gradient. The response is thus by the thus operated ABS controller not deteriorated at the expense of comfort.

Further preferred embodiments will be apparent from the dependent claims and the following description of an embodiment Hand of a figure.

It shows

1 a schematic representation of a braking device for ABS and ESP control operations.

In 1 is tandem master cylinder (THZ) 5 with hydraulic unit 6 (HCU) of an electronic vehicle brake system. electronics unit 7 (ECU) comprises a microcontroller system with which the actuators and sensors contained in the valve block can be electronically controlled or measured. hydraulic unit 6 comprises two brake circuits I and II. Furthermore, each of the brake circuits comprises two wheel pressure circuits (A, B or C, D), each with one intake 3 respectively. 3 ' and an exhaust valve 4 respectively. 4 ' , The intake and exhaust valves can be controlled by the electronics of the ECU 7 operated only switched. reference numeral 2 respectively. 2 ' denote normally open isolation valves and 8th respectively. 8th' normally closed electronic changeover valves. In the to master cylinder 5 leading hydraulic line 8th there is an inlet pressure sensor 9 , There are no other pressure sensors in the wheel pressure circuits themselves. pump 1 respectively. 1' is used for independent pressure build-up, for example in the ASR or ESP case. At the output of the pump is a damping chamber 16 respectively. 16 ' which dampens pressure pulsations during active pressure build-up and associated sounds when ESP is active.

During an ABS control operation, the pressure in the wheel pressure circuits is regulated according to the specifications of the electronics unit. For this purpose, the intake valves 3 . 3 ' and the exhaust valves 4 . 4 ' alternately open or closed. During a conventional ABS control process, in which the isolation valve control according to the invention is not carried out, occur - at least with sufficiently high admission pressure- by the high pressure pulsations when switching the intake and exhaust valves in addition to noise vibrations to the brake pedal 11 on. This is mainly the relatively low hydraulic resistance and thus high hydraulic flow through lines 12 . 13 and 14 responsible. If the control program in ECU 7 By observing the wheel speed signals after a few control cycles has determined that the current ABS control takes place on a road surface with a homogeneous coefficient of friction, is separating valve 2 respectively. 2 ' energized so that this closes. When the isolation valve is closed, a flow of hydraulic fluid is only via channel 10 respectively. 10 ' possible. channel 10 respectively. 10 ' is a hydraulic bypass channel parallel to the isolation valve 2 , which is a check valve 15 respectively. 15 ' includes.

The energization of the isolation valve 2 respectively. 2 ' can be chosen very small, in particular with a current corresponding to a pressure difference in a range of about 2 to 8 bar. This ensures that at a higher pressure difference on the isolation valve, the pressure difference over that in the bypass 10 arranged check valve 15 he follows. As a result, the risk of active pressure build-up is prevented. By controlling the isolation valve 2 with a "low pressure relief valve pressure" also the penetration of the pump control (pump pulses) is reduced to the brake pedal.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005014097 A1 [0002]
• DE 102004029 A1 [0007]
• - EP 102321231 [0012]

Claims (7)

Method in which, during an ABS control process, an intake valve chain of a fluid pressure-controlled wheel brake unit is actuated in an electronically controlled motor vehicle brake system, wherein the intake valve chain consists of a series-connected inlet valve assigned to the wheel brake unit and at least one separating valve ( 2 . 2 ' ) and wherein the at least one isolation valve upstream of the inlet valve, characterized in that the inlet valve is completely opened and the isolation valve is controlled such that the fluid pressure increase occurs in the wheel brake with a smaller gradient than when fully opened isolation valve. Method according to claim 1, characterized in that the separating valve ( 2 . 2 ' ) is energized during an ABS control at a homogeneous coefficient of friction. A method according to claim 1 or 2, characterized in that, in the control of the reducing gradient fluid pressure increase valve, the pressurized fluid is bypassed ( 10 . 10 ' ) on the separating valve ( 2 . 2 ' ) is bypassed. Method according to claim 3, characterized that the bypass contains a hydraulic resistance. Method according to claim 4, characterized in that the hydraulic resistance is a diaphragm and / or a diaphragm a check valve is. Method according to at least one of the claims 1 to 5, characterized in that at the beginning of an ABS control and / or opened after a Reibwertsprung the isolation valve becomes. An electronically controlled motor vehicle brake system comprising a pressure generating means ( 5 ) with the driver dependent fluid via pressure lines in a hydraulic unit ( 6 ) can be controlled with separating valves ( 2 . 2 ' ) for separating the wheel pressure circuits (A .... D) from the fluid ( 5 ) and inlet valves ( 3 . 3 ' ), which are hydraulically connected to the isolation valves and the Raddruckkreisen, further comprising means for an active pressure build-up ( 8th . 8th' . 1 . 1' ), characterized in that with this a method according to any one of claims 1 to 6 is performed.