KR20150056069A - Brake system for a vehicle and method for operating the brake system - Google Patents

Abstract

The present invention relates to a vehicle brake system (10). The system comprises a main brake cylinder (30) having at least one pre-filled ring chamber (40) formed as an independent second volume. The main brake cylinder (30) includes at least two surfaces (46, 47) which are fluid-coupled to each other and operate by the hydraulic pressure of a hydraulic fluid from the brake cylinder, the hydraulic fluid reservoir (50) fluid- coupled with the main brake cylinder (30), at least one first and second brake circuits fluid-coupled with wheel brake cylinders of which one side is fluid-coupled with chambers (31, 32) of the main brake cylinder (30) respectively, and the other side is coupled with the wheels of a vehicle generating brake torque, a pedal feel-simulator (600) which can be operated over the total brake pedal path or a section of a full path by a driver. The pedal feel-simulator (600) is fluid-coupled with the chamber (32) of the main brake cylinder (30) through the fluid flow line (100) fluid-coupled with the first brake circuit and/or the second brake circuit from the input side, and the pedal feel-simulator (600) is fluid-coupled with the pre-filled ring chamber (40) as well as the hydraulic fluid reservoir (50) through the fluid line (60) in which a normally blocked valve (70) is disposed on the output side.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a brake system for a vehicle,

Document WO 2009/121645 A1 describes a hydraulic vehicle braking system. The main brake cylinder of the hydraulic vehicle brake system includes a first pressure chamber and a second pressure chamber. The main brake cylinder at one end extended to the brake pedal further comprises an integrated pedal path simulator 22 and the volume of the simulator which can be filled with brake fluid is hydraulically connected to the brake fluid reservoir by a simulator valve . The first pressure chamber adjacent to the volume of the pedal path simulator, which can be filled with brake fluid, is defined by a load piston and a simulator piston formed of stepped pistons.

In addition, document DE 10 2011 006 327 A1 discloses a "brake-by-wire" type of brake system comprising a main brake cylinder with two pistons disposed therein so that it can be moved, A ring volume is formed which is formed of a step piston with two or more hydraulic working surfaces of different sizes so that the step piston shape can be filled with a hydraulic fluid or a brake fluid. In the "brake-by-wire" operating mode, when the main brake cylinder is actuated by the driver, the narrower actuation surfaces act to generate brake torque at the vehicle wheels and, If there is a functional error, a wider working surface will be activated, where the switching from a narrower working surface to a wider working surface will take place in accordance with the hydraulic pressure in the pressure space in the main brake cylinder or according to the worn pedal force.

In power braking systems, the failure replacement state can be planned independently of the hydraulic fluid volume to be transferred during operation by separating the pedal stroke and pedal force during operation. In general, the hydraulically acting surface is determined by taking into account several operating conditions by the volume receiving portion of the brake system for this failure replacement state.

The invention provides a vehicle brake system having the features of claim 1 and a method for operating the brake system in parallel independent claim.

The present invention is directed to operating the brake system such that, for example, in the event of a partial or total failure, such as a failure of an integrated brake system and / or a functional error, the driver is able to engage directly on two hydraulically operable, to provide. By coupling by one skilled in the art, that is to say on one of the faces until a predetermined pressure is reached, the influence of the operating states to be considered is reduced and a greater pressure and hence a greater deceleration is achieved by the provided force .

The deceleration that can be achieved with this action in the mechanical failure replacement state is obviously large without a significant adverse effect on the pedal path due to the operating condition. However, as compared to the brake system already known from the prior art which utilizes the above-mentioned functional principle, the brake system provided according to the present invention can realize the same function by a smaller number of switching valves, so that the cost for driving the switching valve The cost for the brake system can be reduced as well.

Also advantageously, in the case of the provided brake system, the elimination of the switching valve used in front of the input side of the pedal feel-simulator so far offers the advantage that the comfort for the user of the brake system is also increased, Since not only the inertia of the hydraulic system due to the operation of the hydraulic system but also the noise during operation of the hydraulic system. In addition, the weight is also reduced by the removal of the switching valve in the provided brake system, thereby reducing fuel consumption of the vehicle.

In accordance with the present invention, the pedal feel-simulator is fluidly coupled to the chamber of the main brake cylinder through a fluid line fluidly coupled to the first brake circuit and / or the second brake circuit at the input side. According to a further preferred embodiment of the provided brake system, the pedal feel-simulator is fluidly coupled with the chamber of the main brake cylinder directly through the fluid line in fluid communication with the first brake circuit and / or the second brake circuit at the input side . Here, direct fluid coupling means fluid coupling between two components, and the action of additional components for fluid coupling is not provided in such coupling. In other words, additional components should not be placed or acted in the middle between the directly fluidically coupled components.

According to the invention, the main brake cylinder is also provided with at least one first pressure chamber which can be distributed in one first volume and in one second volume, wherein the first volume is limited by the first piston wall of the rod piston Wherein the volume can be varied by movement of the first piston wall and the second volume is defined by the second piston wall of the rod piston wherein the second volume can be varied by movement of the second piston wall, The first volume and the second volume are fluidly coupled to the hydraulic fluid reservoir and the first brake circuit is fluidly coupled to the first volume by a first fluid line.

According to a further embodiment of the provided brake system, the normally shut-off valve can realize the function of the plurality of valves in a single part. With regard to the brake system known from the prior art, in the case of the brake system provided according to the present invention, the magnetic valve 35, which is disposed on the input side of the pedal feel-simulator and is normally shut off according to Fig. 1, The valve referred to as the switching valve 610 and referred to as the so-called " simulator isolation valve " is now integrated into a single normally-closed valve so that the above-described advantages for the provided brake system can be achieved. In addition to this, as described, for example, in the description of FIG. 1, the brake system provided in accordance with the present invention, as compared to the known configuration of the brake system from the prior art, The check valve 210 can be saved.

In accordance with a further embodiment of the provided brake system, a check valve may be additionally provided, the check valve being fluidly coupled to the fluid line of the pedal feel simulator through the fluid line at one end and pre- And is in fluid communication with the ring chamber. The check valve preferably provides an improvement in braking behavior from the pressureless brake condition due to the faster overcoming of the so-called dead volume in each of the connected brake circuits, due to the additional volume provided by the pre-charging ring chamber.

According to a further embodiment, the provided brake system includes a controllable check valve in fluid communication with a normally shut off valve downstream of the normally shut off valve through the fluid line. The inflow of the brake system into each brake circuit and the reflux into the hydraulic fluid reservoir are controlled by the shut-off pressure of the controllable check valve. The controllable check valve described above defines the maximum permissible pressure in the ring piston volume 40, that is, it is used for pressure limitation.

According to a further embodiment of the provided brake system, the pedal feel-simulator is fluidly coupled to the chamber of the main brake cylinder at the output side, wherein the main brake cylinder comprises a corresponding snifting bore for this purpose. Since the so-called 'jump-in valve' used in the limp-in area for the pedal feel-simulator for the characteristic curve and used so far can now be implemented by the main brake cylinder, Is preferably improved as compared with the prior art.

The invention is illustrated by the attached drawings.
1 is a schematic diagram of a hydraulic circuit diagram of a prior art brake system.
2 is a schematic diagram of a hydraulic circuit diagram of a brake system according to a first embodiment of the present invention.
3 is a schematic diagram of a hydraulic circuit diagram of a brake system according to a second embodiment of the present invention.

Before the following embodiments of the present invention are described, a basic configuration of a brake system having a ring volume piston space in the main brake cylinder will be described first, and the configuration is basically the same as in all embodiments of the brake system provided Can be applied. The details of the individual embodiments with reference to FIGS. 2 and 3 will now be described as a variant or supplement to this basic arrangement.

1 shows a schematic diagram of a hydraulic circuit diagram of a brake system 10 according to the prior art in which important components for operating the brake system 10 are mounted in a unit provided by the reference numeral "11 " .

The above-mentioned supplementary device with the step piston 45, which forms the ring volume and whose functioning method is further described below in more detail, is characterized in that it is located at a limited low pressure in the ring volume piston space and at a reference "100" In the first brake circuit to be displayed, an additional brake fluid volume is pushed into the first brake circuit 100. This additional amount is achieved by maximizing the possible vehicle deceleration by increasing the brake pressure in the first brake circuit 100 that can be achieved in the mechanical failure replacement state during full braking.

This effect also compensates for the bubbles contained in the first brake circuit 100 as the case may be, which enables a higher maximum brake pressure in the failing alternate state and, in this regard, a relatively shorter stopping path of the vehicle.

The additional volume also improves the braking behavior by more quickly overcoming the so-called dead volume in the first brake circuit 100 from the no-pressure brake condition. This known principle corresponds to a hydraulic line with a check valve < RTI ID = 0.0 > 15 < / RTI > All of these above-mentioned advantages can also be realized by the brake system according to the invention.

1, both pressure chambers 31 and 32 of a conventional main brake cylinder 30 are provided with pressure chambers 31 and 32 which are both hydraulic surfaces 46 And 47 are located in front of the primary chamber or pre-charging ring chamber 40, which may be varied by one of the faces. The brake input member 48 is coupled to the step piston 45 in a known manner and the member can be pivoted about the point 49. [

The pre-charging ring chamber 40 is short-circuited to the brake fluid (hydraulic fluid) reservoir 50 by driving the magnetic valve 35 during normal operation (i.e. bi-wire) (normally interrupted).

The timing of this drive may be shifted later in time in order to improve the pressure-forming dynamics in the case of braking (for example, in the case of emergency braking) in the case of rapid recognition of the braking. In the operating mode of the " mechanical failure replacement state ", the magnetic valve 35 is shut off (generally because no current is supplied).

The inflow into the brake circuits 100 and 200 and the reflux into the reservoir 50 are controlled by the shutoff pressure of the check valves 210, Check valves in the brake circuits 100 and 200 define the maximum permissible pressure within the ring piston volume 40 while the check valve 55 is pressure limited, 200) and the ring piston volume or the pre-charging ring chamber (40).

When the pressure in the ring piston volume 40 exceeds this pressure threshold, the brake fluid flows from the ring piston area 40 into the brake circuits 100, 200. This state is maintained until the maximum pressure set by the check valve 55 in the pre-charging ring chamber 40 is exceeded, or until the pressure exceeds the pressure threshold by the pressure rise of the brake circuit. This effect is also used in the brake circuit 200 by the implementation of the hydraulic parallel path 115.

In this regard, for the sake of completeness, switching valves 105, 205 are disposed in each (normally open) fluid lines 100, 200 in a known manner and the switching valves are connected to the wheel modulating section 300 Allows direct intervention (ie supply of hydraulic fluid).

1, a device generally known as a wheel modulating portion is indicated by the reference numeral 300, in which the wheel modulating portion 300 includes vehicle wheels (not shown here) Valves and discharge valves, and their function is not described herein for the sake of simplicity, as they are known to those skilled in the art.

In Fig. 1 the actuator is indicated by the reference numeral "400" and the actuator can be operated by an electric motor in the configuration shown in Fig. 1, e. The hydraulic fluid is supplied to the actuator 400 from the reservoir 50 through the fluid line 425. The electric motor M is connected to the fluid lines of the supply connections 450 and 460 independently of the operation of the main brake cylinder 30, for example to compensate for the hydraulic fluid present in the volume 410, The motor moves the piston 405 in the housing back and forth by forward drive or backward drive 415 to transfer the hydraulic fluid into the wheel modulating section 300 (for example, as an ESP function) In a manner that can be achieved. In a known manner, as in other positions of the brake system 10, filter devices 475 and 485 are provided in front of fluid lines 430 and 440, respectively (as viewed from actuator 400) Although switching valves 470 and 480 are provided, they are not dealt with in more detail because they are assumed to be known. However, for the sake of completeness, although pressure sensors are located at various locations in the brake system 10, their function will be known to those skilled in the art. By way of example, a pressure sensor, indicated at 500 in FIG. 1, is implemented at the end of the fluid line 440.

A pedal feeler-simulator-apparatus 600 having a bypass fluid line 615 with a pressure reservoir 605, a switching valve 610, and a check valve 210 is implemented. In parallel with this, a switching valve 620 is disposed. On the other hand, the pedal sensing-simulator-device 600 is intended to emphasize that it is already known to those skilled in the art from the prior art.

2 is a schematic diagram of a hydraulic circuit diagram of a brake system 10 according to a first embodiment of the present invention.

2 and 3 show a corresponding portion of the brake system 10 of FIG. 1 in detail, in which the main brake cylinder 30 is shown connected to the pedal feel-simulator 600 in detail.

2 shows a cross-sectional view of the main brake cylinder 30 (so-called 'parallel plunger') and a rod piston 45 with hydraulically engageable surfaces 46 and 47, a pre-charging ring chamber 40, A floating piston 33 for separating the pressure chambers 31 and 32 from each other, and a hydraulic fluid reservoir 50 are shown.

The fluid lines 100, 200 of the first brake circuit or the second brake circuit are also provided with corresponding valves 105, 205 wherein the fluid lines 100, To " down " (not shown) wheel modulators.

The hydraulic fluid reservoir 50 is in fluid communication with the pressure chambers 31, 32, 40 of the main brake cylinder 30 via the sniffer bores 43a, 43b, 43c, respectively. In addition, the sniffer bores 43a, 43b, 43c are provided with corresponding seals 41, 42, 43, which seals the main brake cylinder 30 against the periphery.

In the event of a functional error in the brake system 10, the driver may nevertheless exert a force indicated by the arrow 900, i.e., by applying a brake pedal (not shown) In order to create pressure in the pressure chambers 31, 32 that is transferred to the wheel modulating portion directly through the fluid lines 100, 200 to create the load piston 45, To the left. This is because the pressure created by the hydraulically acting surface 46 in the pre-charging ring chamber 40 (this pressure can be very difficult to effectively brak and the driver must apply a correspondingly large force against this pressure Is reduced by switching (passage) of the valve 55, and the driver is able to 'brak' by the hydraulically acting surface 47 finally. In this case, the hydraulically acting surfaces 46, 47 are coupled to each other according to function.

The pedal feel-simulator 600 of the brake system 10, which can be actuated by the entire brake pedal path or sections of the full path, which can be actuated by the driver, comprises a first brake circuit and / or a second brake circuit Simulator 600 is fluidly coupled to the pressure chamber 32 of the main brake cylinder 30 via a fluid line 100 in fluid communication with a fluid Is also coupled to the pre-filled ring chamber (40) as well as the hydraulic fluid reservoir (50) via line (60).

Simultaneously through the fluid line 15 a check valve 20 fluidly coupled to the fluid line 60 of the pedal feel simulator 600 at one end and fluidly coupled to the pre-charging ring chamber 40 at the other end is provided, Is provided in the system (10). The brake system 10 also includes a controllable check valve 55 fluidly coupled to the normally shut off valve 70 downstream of the normally shut off valve 70 through the fluid line 71 .

3 is a schematic diagram of a hydraulic circuit diagram of the brake system 10 according to a second embodiment of the present invention.

Since the principle construction of the brake system 10 is similar to the construction according to the first embodiment in Fig. 2, only differences will be described below compared to the first embodiment.

Simulator 600 is fluidly coupled to one of the pressure chambers 32 of the main brake cylinder 30 on the output side for which the main brake cylinder 30 is connected to the corresponding sniffer bore 81, Respectively. The sniffering bore 81 is fluidly coupled with the fluid line 15 downstream of the check valve 20 through the fluid line 82. The sniffer bore 81 has a corresponding lip seal 84 in the main brake cylinder 30 which is positioned within the region of the sniffer bore 81 when the rod piston 45 is positioned, So that the so-called jump-in behavior can be implemented without the sense-simulator 600. [

Claims (10)

A vehicular brake system (10), the brake system comprising:
- a main brake cylinder (30) having one or more pre-charging ring chambers (40) formed as a second independent volume, wherein the main brake cylinder (30) is a hydraulic brake system which hydraulically acts on the hydraulic fluid present in the main brake cylinder, A main brake cylinder (30) including two or more fluid-engaging surfaces (46, 47)
A hydraulic fluid reservoir 50 fluidly coupled to the main brake cylinder 30,
One or more of which are in fluid communication with the wheel brake cylinders associated with the wheels of the vehicle, one side of which is in fluid communication with the chambers 31, 32 of the main brake cylinder 30 and the other side, respectively, 1 and a second brake circuit,
- a pedal feel-simulator (600) operable over a section of the entire brake pedal path or the entire path that can be actuated by the driver,
Simulator 600 is connected to the chamber 32 of the main brake cylinder 30 through a fluid line 100 fluidly coupled with either the first brake circuit or the second brake circuit or both brake circuits on the input side And the pedal feel-simulator 600 is fluidly coupled to the pre-charging ring chamber 40 as well as to the hydraulic fluid reservoir 50 via the fluid line 60 in which the normally shut off valve 70 is disposed, Fluid coupling. A vehicle brake system (10) according to claim 1, characterized in that the normally shut off valve (70) implements the function of the plurality of valves in a single part. The simulator (600) of claim 1 or 2, further comprising: at one end through the fluid line (15) fluidly coupled to the fluid line (60) of the pedal feel simulator (600) Characterized in that a combined check valve (20) is additionally provided. The pedal feeler-simulator (600) according to any one of claims 1 to 5, wherein the pedal feeler-simulator (600) is disposed in the first brake circuit and the second brake circuit Is fluidly coupled to the normally open first switching valve (105) of the first brake circuit upstream of the normally open first switching valve (105). 3. A device according to claim 1 or 2, wherein the check valve further comprises a controllable check valve (55) in fluid communication with the normally shut off valve (70) downstream of the normally shut off valve (70) (10). ≪ / RTI > 6. A method according to claim 5 wherein the fluid line (71) for the controllable check valve (55) is formed as a bypass fluid line, wherein the controllable check valve (55) Is fluidly coupled to the pre-charging ring chamber (60) and is fluidly coupled to the pre-charging ring chamber (40) at the other end. 3. A brake system according to claim 1 or 2, wherein the pedal feel-simulator (600) is fluidly coupled to one of the chambers (32) of the main brake cylinder (30) at the output side, Characterized in that it has a corresponding snifting bore (81) for the vehicle. The vehicle brake system (10) according to claim 1 or 2, characterized in that the brake system (10) is formed in such a way that hydraulic fluid supply can be performed only within one of the brake circuits. 3. A brake system according to claim 1 or 2, wherein the main brake cylinder (30) comprises two or more hydraulic surfaces (46, 47), a floating piston (33) and a load piston (31, 32, 40) or both of said surfaces and said pressure chambers, wherein the rod piston (45) is in fluid communication with the brake Is formed as a stepped piston engageable with the input member (48). In the event of a malfunction of the brake system 10, the brake input member 48 is actuated by the driver and the normally shut off valve 70 is opened such that the hydraulic fluid flows into the hydraulic fluid reservoir 50, Of the brake system (10) according to any one of the preceding claims.

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