DE102007034333A1 - Electronically adjustable hydraulic brake system - Google Patents

Abstract

The invention is based on an electronically pressure-controllable hydraulic brake system of a vehicle. Such brake systems (10) comprise, in addition to a master cylinder (12) for actuating the brake system (10), a plurality of wheel brakes (14) and a hydraulic unit (16) for modulating the brake pressure at the wheel brakes (14) as a function of critical driving conditions of the vehicle. The hydraulic unit (16) is equipped with a pressure generator (60) with controllable solenoid valves (46, 48, 54, 58, 68) and an electronic control unit (70). On the hydraulic unit (16) pressure-carrying channels and hydraulic connections (18, 20, 24, 26, 28, 30) are also formed. According to the invention, in a conventional hydraulic unit (16) with four connections (26, 28, 28, 30) for wheel brakes (14) to at least one of these connections (24, 26, 28, 30) to connect an additional hydraulic consumer (32) wherein the application of hydraulic pressure can be effected independently of an actuation of the wheel brakes (14). The additional consumer (32) may preferably be a friction clutch, which connects a vehicle to a trailer and whose clamping force is variable depending on the applied hydraulic pressure.

Description

State of the art

The The invention is based on an electronically pressure-controllable hydraulic brake system for a vehicle according to the preamble of claim 1.

electronic Pressure-adjustable brake systems are used in vehicles for anti-lock braking, Traction slip or driving stability control used. at such braking systems are the driver by pressing a Master cylinder a braking request. The master cylinder is hydraulically connected to the wheel brakes, being between the Master cylinder and the wheel brakes connected a hydraulic unit is.

This Hydraulic unit modulates the brake pressure in anti-lock mode at the wheel brakes in dependence a slip detected by vehicle sensors on the wheels of the vehicle. Make vehicle-mounted sensors an unstable Driving condition of the vehicle, moreover, in a traction or in driving stability control mode a brake pressure on at least one of the wheel brakes by the hydraulic unit independently be built by a braking request of the driver.

to Pressure generation and modulation is the hydraulic unit with a drivable Pressure generator, with electronically controlled solenoid valves, storage and other hydraulic components. The drive of the Pressure generator and the control of the solenoid valves is from a electronic control unit made, which in addition to the signals of the vehicle-mounted sensors evaluates. The control unit Can save space on the hydraulic unit or off the hydraulic unit be attached to the body of the vehicle.

The mentioned Hydraulic components are on a metallic housing block attached to the hydraulic unit. On this housing block are this recordings intended. Pressure medium channels, the using holes in the housing block are formed, make pressure fluid connections between the components according to one of the brake system underlying hydraulic circuit diagram ago. For contacting the master brake cylinder and the wheel brakes with the hydraulic unit are also (hydraulic) connections on the housing block educated.

such Hydro units are in large numbers for vehicles produced with four hydraulic wheel brakes. You assign for each of the existing wheel brakes of the vehicle a separate connection.

The mentioned Hydraulic components are only for brief admission of Wheel brakes designed with brake pressure. Functions that are permanent Require applying hydraulic pressure to a consumer, are therefore not implemented. Solutions, for example, a continuous pressure supply of a hydraulic Consumers require, accordingly, have next to the hydraulic unit a separate pressure generator and possibly additional Means for pressure regulation. They build accordingly expensive, expensive and take up a lot of installation space.

Disclosure of the invention

Advantages of the invention

at The invention will be a conventional hydraulic unit with connections for a total Four wheel brakes are used, in addition to all. Wheel brakes of a brake system additionally a hydraulic additional consumer with under hydraulic pressure to supply standing pressure medium. The hydraulic additional consumer is over one of the connections, which are provided for contacting the wheel brakes, to the hydraulic unit connected; above the remaining 3 connections All wheel brakes of the brake system are contacted with the hydraulic unit.

Complementary hydraulic Facilities are between the hydraulic unit and the additional consumer connected. they allow a separate independent Pressurization of the wheel brakes and additional consumers. Thereby is it possible different Press about different long periods at the wheel brakes and at the additional consumer. The anyway on the hydraulic unit existing pressure generator worried the pressure build-up as well as the wheel brakes as well as for the additional consumer and thus saves the use of a separate Pressure generator on. The solenoid valves on the hydraulic unit can be used to control a pressure build-up at the additional consumer, so that only minor structural changes to a conventional Hydraulic unit are required.

The Invention is particularly suitable for vehicles that are by nature have less than four hydraulic wheel brakes, for example two or three-wheeled Vehicles, but also for vehicles with an electrically and a hydraulically braked axle, further for vehicles, where not all existing wheel brakes are separated need to be regulated or for Car trailers, which are equipped with their own brake system.

As mentioned, let yourself the pressure level of the wheel brakes regardless of the pressure level at the additional consumer to adjust. Advantageously, the additional consumer can also permanently charged with hydraulic pressure. A particularly advantageous Application of the invention is, for example, when the additional consumer a hydraulic friction clutch is over which a towing vehicle with a trailer is coupled. In such friction clutches can on the Clamping force the effective friction force between the clutch partners pressure dependent changed become. Leave it over unwanted Relative movements of the trailer across from the vehicle (trailer commuting) with a view to stabilizing the team.

Further Advantages or advantageous developments of the invention result from the dependent claims the following description.

drawing

One embodiment is shown in the drawing and detailed in the following description described. The single figure shows the hydraulic circuit diagram of a equipped with a hydraulic additional load brake system.

Description of the embodiment

The brake system shown in the figure 10 includes a master cylinder 12 and one between the master cylinder 12 and three wheel brakes 14 switched hydraulic unit 16 , The hydraulic unit 16 is essentially of a known type and has two connections 18 . 20 on, over which the master cylinder 12 connected. The two connections 18 . 20 of the hydroaaggregate 16 are two brake circuits I . II assigned, each brake circuit I . II at least one of the wheel brakes shown 14 having. An application of the brake circuits I . II With brake pressure can be done by the driver by muscle power, if this is the master cylinder 12 over a pedal 22 actuated.

Furthermore, the total hydraulic unit 4 connections 24 - 30 for wheel brakes 14 intended. According to the invention, all wheel brakes are connected to 3 of these 4 connections 14 the brake system 10 connected while the 4th connection 30 solely for the hydraulic supply of an additional consumer 32 serves. This additional consumer 32 is indirect with the hydraulic unit 16 contacted. This is between the Hdroaggregat 16 and the additional consumer 32 a check valve 34 , a high-pressure accumulator 36 and a consumer control valve 38 connected. The check valve 34 is the hydraulic unit 16 after and the high-pressure accumulator 36 upstream and allows loading of the high-pressure accumulator 36 with pressure medium from the hydraulic unit 16 , At the same time prevents this check valve 34 a pressure medium reflux from the high-pressure accumulator 36 back to the hydraulic unit 16 and thus an unwanted pressure reduction in the high-pressure accumulator 36 ,

The high-pressure accumulator 36 downstream is the consumer control valve 38 , It is an electronically controllable solenoid valve, which in accordance with its control, a pressure medium connection from the high-pressure accumulator 36 to the additional consumer 32 releases, closes or throttles. Based on the consumer control valve 38 can thus be the additional consumer 32 determine the pressure level to be applied.

From the additional consumer 32 leads a drain line 40 on the direct way back to the hydraulic unit 16 , For contacting this drain line 40 is on the hydraulic unit 16 According to the invention, an additional connection 42 provided. This connection 42 is in connection with a return flow channel 44 inside the hydraulic unit 16 , This return flow channel 44 is through an exhaust valve 46 Electromagnetically controllable and opens into a to a suction side of a pressure generator 60 leading return 56 one.

To modulate the brake pressure at the wheel brakes are on the hydraulic unit 16 Other electronically controlled hydraulic components according to an underlying hydraulic circuit interconnected. Since both brake circuits I . II are constructed largely identical and have the same hydraulic components, was in the figure of Überüberkleit half to the detailed illustration of the brake circuit I waived.

The brake circuit II starts at the inlet side connection 20 for the master cylinder 12 and ends at the outlet ports 28 . 30 of the hydraulic unit 16 , To these outlet side connections 28 . 30 is, as mentioned, on the one hand one of the wheel brakes 14 and according to the invention the additional hydraulic consumer 32 , which is not a wheel brake, connected.

The brake circuit II includes immediately behind the port 20 of the master cylinder 12 a changeover valve 48 , This is electronically controlled and allows the master cylinder 12 opposite the hydraulic consumers 14 . 32 disconnect if necessary. This is a pressure build-up in the brake circuit II independently of the driver's request. This case occurs, for example, during a traction or vehicle stability control.

Behind the pilot valve 48 branches the brake circuit II in a first and in a second leg 50 . 52 , where these line branches 50 . 52 in each case to one of the outlet-side connections 28 . 30 of the hydraulic unit 16 lead. In each of these lines 50 . 52 there is a so-called intake valve 54 , This is preferably a normally open valve, which serves to the inflow of pressure medium to the associated outlet-side connection 28 . 30 to control.

In the area between an inlet valve 54 and the connection 28 for the wheel brake 14 branches a return 56 from. This return 56 is through an exhaust valve 58 controllable and leads to the suction side of a pressure generator 60 , The outlet valve 58 is usually a normally closed electronically controllable solenoid valve, which helps to lower the brake pressure in the wheel brake 14 is switched to its passage position.

Outflowing pressure medium passes through the return line 56 first in a the pressure generator 60 upstream accumulator 62 and from there on. an intermediate check valve 64 to the suction side of the pressure generator 60 , The check valve 64 locks in the direction of the accumulator 62 This prevents and prevents from the pressure generator 60 generated negative pressure to one of the outlet side connections 28 . 30 spread out. In the pressure fluid store 62 can pressure fluid coming out of the wheel brake 14 in the event of a necessary pressure reduction flows, be cached, to quickly reduce the brake pressure at this wheel brake 14 to ensure. A pressure side of the pressure generator 60 opens between the one switching valve 48 and the intake valves 54 back into the brake circuit II one.

As is well known, can be achieved by suitable control of the intake and exhaust valves 54 ; 46 . 58 the pressure level at the connections 28 . 30 adjust as needed. An electronic control unit 70 evaluates the signals from the vehicle side sensors (not shown) and controls the explained hydraulic components accordingly.

In addition, there is still a suction line 66 available from the terminal 20 of the master cylinder 12 also to the suction side of the pressure generator 60 leads. This intake pipe 66 is from a so-called high-pressure switching valve 68 controllable. With an electronic control of this high pressure switching valve 68 can the pressure generator 60 if necessary, pressure medium directly from the master cylinder 12 suck in and for a pressure build-up on the connections 28 . 30 in the brake circuit II feed.

In the case of the connection 30 the brake circuit II connected hydraulic additional consumers 32 For example, it may be a hydraulically loadable friction clutch between a towing vehicle and a trailer. That in the high-pressure accumulator 36 storable under a predetermined pressure pressure medium can be used to adjust a clamping force of this friction clutch. With variable application force, the friction conditions between the clutch partners can be changed so that unwanted relative movements between the towing vehicle and the trailer braked or their emergence can be ideally avoided completely. The pressure build-up in the high-pressure accumulator 36 worried the pressure generator 60 in the hydraulic unit 16 , The pressure buildup is by driving the associated intake valve 54 controllable and can take place continuously or step by step in stages. A pressure build-up preferably takes place when the brake system 10 the vehicle is currently not needed for traction slip anti-lock or driving stability control.

Through a coordinated control of the inlet and outlet valves 54 ; 46 . 58 and of both lines 50 . 52 common pressure generator 60 through the control unit 70 can the pressure level in the high pressure accumulator 36 be built independently of the rest of the braking system. The additional consumer 32 required pressure level is then controlled by a consumer inlet valve 38 and the exhaust valve 46 in the hydraulic unit 16 set. The additional consumer 32 required pressure level may be as a mathematical function of a driving condition descriptive size, such as the driving speed and / or a, a pendulum motion of a trailer descriptive size, such as the yaw rate or the lateral acceleration in the electronic control unit 70 be deposited. Likewise, the pressure level can be regulated depending on signals from other sensors, which, for example, the pressure level at the additional consumers 32 evaluate. The invention described enables the additional consumer 32 permanently or at limited intervals with hydraulic pressure.

Of course, changes or supplements possible in the described embodiment, without deviate from the basic idea of the invention.

Claims (10)

Electronically adjustable hydraulic brake system ( 10 ) for a vehicle, comprising a master cylinder actuatable by the driver by muscular force ( 12 ), a hydraulic unit ( 16 ) and several vehicle-mounted wheel brakes ( 14 ), where the hydro aggregate ( 16 ) between the master cylinder ( 12 ) and the wheel brakes ( 14 ) and connected to a pressure generator ( 60 ), with controllable valves ( 46 . 48 . 54 . 58 . 68 ), with a the operation of the pressure generator ( 60 ) and the control of the valves ( 46 . 48 . 54 . 58 . 68 ) controlling electronic control unit ( 70 ) and with hydraulic connections ( 18 . 20 . 24 . 26 . 28 . 30 ) for contacting the master cylinder ( 12 ) and the wheel brakes ( 14 ), characterized in that at least one of the terminals ( 24 . 26 . 28 . 30 ) of the hydraulic unit ( 16 ) for contacting the wheel brakes ( 14 ) a hydraulic additional consumer ( 32 ), which is not a wheel brake, is connected, the additional consumer ( 32 ) separated and independent of an operation of the wheel brakes ( 14 ) can be acted upon by pressure medium under pressure. Electronically pressure-controllable hydraulic brake system according to claim 1, characterized in that the additional consumer ( 32 ) can be acted upon permanently during operation of the vehicle with hydraulic pressure, whereby the additional consumer ( 32 ) acting pressure in its height is variable. Electronically pressure-controllable hydraulic brake system according to claim 1 or 2, characterized in that the additional consumer ( 32 ) via a high-pressure accumulator ( 36 ) indirectly with the hydraulic unit ( 16 ) and that a fluid connection of the high pressure accumulator ( 36 ) with the additional consumer ( 32 ) is electronically controlled or regulated. Electronically pressure-controllable hydraulic brake system according to one of claims 1 to 3, characterized in that on the hydraulic unit ( 16 ) one of a valve ( 46 ) controllable, to the pressure generator ( 60 ) and with a connection ( 42 ) equipped return ( 44 ), wherein a sequence ( 40 ) of the additional consumer ( 32 ) directly with this connection ( 42 ) connected is. Electronically pressure-controllable hydraulic brake system according to one of claims 1 to 4, characterized in that the high-pressure accumulator ( 36 ) a check valve ( 34 ), which is a flow direction from the high-pressure accumulator ( 36 ) to the hydraulic unit ( 16 ) locks. Electronically pressure-controllable hydraulic brake system according to claim 4 or 5, characterized in that at least the additional consumer ( 32 ) away from the hydraulic unit ( 16 ) can be arranged on the vehicle. Electronically pressure-controllable hydraulic brake system according to one of claims 1 to 6, characterized in that the additional consumer ( 32 ) is a friction clutch with hydraulically controllable or adjustable application force between a vehicle and a vehicle trailer. Electronically adjustable hydraulic brake system according to claim 7, characterized in that the clamping force of the Friction clutch depending on the driving speed and / or one, a pendulum movement of a trailer The vehicle descriptive size, changeable is. Electronically pressure-controllable hydraulic brake system according to claim 8, characterized in that pressure-measuring sensors for controlling or regulating the height of the additional consumer ( 32 ) are provided adjacent hydraulic pressure. Electronically pressure-controllable hydraulic brake system according to one of claims 1 to 9 and with a hydraulic unit ( 16 ) with four separate hydraulic connections ( 24 . 26 . 28 . 30 ) for wheel brakes ( 14 ), characterized in that the hydraulic brake system ( 10 ) less than four independently adjustable hydraulic wheel brakes ( 14 ).