FR2586219A1 - HYDRAULIC BRAKING SYSTEM - Google Patents

Abstract

HYDRAULIC BRAKING SYSTEM FOR MOTOR VEHICLES, INCLUDING A BRAKE MASTER CYLINDER, A BRAKE EFFORT AMPLIFIER SUPPLIED BY A HYDRAULIC ENERGY SUPPLY SYSTEM TO ACTUATE THE BRAKE MASTER CYLINDER, A BRAKE CONTROLLER FOR PRESSURE ACTUATION IN THE BRAKE EFFORT AMPLIFIER CHAMBER, AND INCLUDING WHEEL BRAKE CYLINDERS WHICH, THROUGH CONTROL VALVES OF A SLIP REGULATION DEVICE, CAN BE CONNECTED TO THE SYSTEM WITHOUT PRESSURE ENERGY SUPPLY OR HAS AT LEAST ONE BRAKE DUCT COMMUNICATING WITH THE BRAKE MASTER CYLINDER OUTPUT, THE SAID BRAKE DUCT BEING EQUIPPED WITH A PRESSURE CONTROLLED INPUT VALVE, WHICH ALLOWS CLOSING THE MASTER OUTPUT -BRAKE CYLINDER AND CONNECT THE WHEEL BRAKE CYLINDERS TO THE BRAKE EFFORT AMPLIFIER CHAMBER VIA A CONTROL VALVE OF THE REGULATOR , CHARACTERIZED IN THAT, WHEN THE INPUT VALVE 31, 32 IS IN THE INITIAL POSITION, THE BRAKE LINE 29 30 IS OPEN AND THE PORT 41 LEADING TO THE AMPLIFIER CHAMBER 17 IS CLOSED, AND IN THAT THE VALVE INPUT 31, 32 CAN ONLY BE SWITCHED INTO THE OPEN POSITION WHEN IT IS SIMULTANEOUSLY RECEIVING PRESSURE FROM AMPLIFIER CHAMBER 17 AND PRESSURE FROM BRAKE LINE 29, 30, THE OUTPUT OF BRAKE MASTER CYLINDER 1 IS CLOSED AND THE WHEEL BRAKE CYLINDERS CONNECTED TO AMPLIFIER CHAMBER 17 WHEN THE INPUT VALVE IS IN THE OPEN POSITION.

Description

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  The present invention relates to a hydraulic braking system for a motor vehicle, comprising a master cylinder of

  braking, a brake force amplifier powered by a system

  hydraulic power supply to operate the master

  brake cylinder, a brake valve for controlling the actuation pressure in the brake force amplifier chamber, and comprising wheel brake cylinders which, through control valves of a slip regulation device, can be connected to a pressureless reservoir of the energy supply system or to at least one brake line communicating with the output of the brake master cylinder, this brake line being provided with a valve pressure-controlled input, which closes the output of the brake master cylinder and connects the wheel brake cylinders to the brake force amplifier chamber via a control device valve regulation

slip or "anti-lock".

  In braking systems for motor vehicles of this type, it is essential that the braking master cylinder is kept in the standby position during operation of the

  regulation, during which the pressure liquid, which is necessary

  re upon repeated actuation of the wheel brake cylinders, is provided

  neither by the power supply system and regardless of the material

  braking tre-cylinder, this standby position ensuring that the brakes continue to be actuated by means of the braking master cylinder in the event of a failure of the power supply system or

of the anti-lock device.

  In a braking system for motor vehicles

  Crit in German patent application No. 34 39 258.0, the brake line can be connected to the chamber of the force amplifier

  braking through an electromagnetically controlled control valve

  anti-lock device tick and through a non-return valve installed downstream, to supply the wheel brake cylinders with pressure fluid from the power supply system of the brake force amplifier during operation of

  anti-lock device. In addition, there is provision, between the master-cy-

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  brake line and location of the control valve

  of a manoeuvrable non-return valve which, via the

  pressure introduced by the control valve, is switched to posi-

  tion closed in which only a return of pressure fluid to the brake master cylinder is possible, so that the brake master cylinder is held in the standby position. However,

  this braking system for motor vehicles has an

  is that when a leak occurs on the brake line or on the components connected to it (brake master cylinders and wheel brake cylinders) at the start of the slip regulation, the pressure fluid risk of escaping from the amplifier chamber through the control valve towards the point where the leak has occurred, so that the pressure in the amplifier chamber is relieved and the actuation of a intact brake system connected directly to the amplifier chamber is not

no more possible.

  The present invention therefore aims to improve a

  braking system for motor vehicles of the type indicated above

  so as to maintain the pressure in the amplifier chamber

  brake and therefore the power supply to the brake circuits

  intact, in the event of a leak in the brake line or in the

  nes that are connected to it, even during the operation of the

slip regulation.

  This object is achieved by the present invention in that, when the inlet valve is in the initial position, the brake line is open and the orifice leading to the amplifier chamber is closed, and in that the valve d input can only be switched to the open position when it simultaneously receives a pressure

  the amplifier chamber and a brake line pressure

  ge, the output of the brake master cylinder being closed and the

  wheel brake liners being connected to the amplifier chamber

  when the inlet valve is in the open position. So even when

  the anti-lock device control valve is open, communication between the amplifier chamber to the brake line and the wheel brake cylinders cannot be opened by

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  the pressure-controlled inlet valve only when a pressure

  is established in the brake line, that is to say when the con-

  brake line and the components connected to it are intact. Yes

  the brake line is defective, the inlet valve remains closed

  and the amplifier chamber and the brake line leak point cannot communicate. The operation of a braking circuit directly connected to the amplifier chamber,

  that of other brake circuits of a multiple brake system

  several circuits and that of the anti-lock device are maintained.

  According to an advantageous embodiment of the present in-

  Note, the inlet valve includes two control pistons that can

  move towards each other and delimiting a valve chamber or-

  green towards the brake cylinders roll these two control pistons with valve seats which can be closed

  in the same direction by valve elements resting one on the other

  tre, the distance between these valve seats being greater than the distance

  tance between the valve elements when the control pistons

  are in the initial position, and being less than this distance when

  the control pistons are in the open position. This valve,

  which is simple in design, has an advantage, that the outlet

  brake master cylinder can only be closed before

  the amplifier chamber port is open.

  According to the invention, the first control piston,

  which can be stressed by the pressure prevailing at the orifice of the mat - -

  braking tre-cylinder, is a stepped piston whose stepped face ex-

  very close to the second control piston, delimits a chamber which communicates with a pressureless tank. Consequently, each time a pressure is established in the brake line, the first control piston moves in the direction of the second control piston, its valve seat then reaching a position

  in which it can be closed, when pressurizing the se-

  cond control piston, by the valve element assigned to it.

  Preferably, the actuation stroke of the piston

  mande is limited by a mound sleeve which is integral with the wood-

  tier, which is located between the control pistons and in which the - 4 -

  small diameter part of the first control piston is guided in a

  waterproof lesson. Furthermore, in accordance with the invention, a compression spring

  pressure can be inserted between the control pistons for oar

  the control pistons in the initial position.

  Furthermore, in accordance with the present invention, a simple design of the inlet valve resides in that the two elements

  valve are housed in a central bore of the second piston

  pressure which can be pressurized by the pressure of the amplifier chamber, and in that the valve element assigned to the valve seat of the first control piston is held in the open position by a stop provided on the second piston ordered. This arrangement offers an additional advantage, namely that the control stroke of the inlet valve depends only on a reduced number of tolerances

  dimensional and can therefore be expected to be relatively short.

  The present invention also provides that in.position ini-

  tiale, the valve seat of the second control piston is supported on

  the corresponding valve element, which is applied against a sleeve

  butte town in solidarity with the bootmaker. Closing the valve passage

  of the second control piston is therefore also ensured by the

  compression spell located between the control pistons.

  Finally, appropriately, the brake master cylinder

  brake system for motor vehicles can be a mat-

  tandem braking three-cylinder to which two groups of wheel brake cylinders are connected via two separate braking lines, a pressure-controlled inlet valve being installed on each braking line and the two inlet valves connectable together to the amplifier chamber through

  the anti-lock device control valve. In this mode of rea-

  In addition, the brake lines of the two brake circuits communicating with the tandem brake master cylinder can be supplied by the energy supply system through a control valve of the anti-lock device, without the separation

  between the braking circuits, however, canceled.

  The various objects and characteristics of the invention are-

  will now be detailed in the description which follows, made to

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  by way of nonlimiting example, referring to the single figure an-

  attached which represents a longitudinal section view of an amplificate-

  ur braking force associated with a tandem master cylinder, and

  two inlet valves forming part of a vehicle brake system

  automotive vehicles shown schematically.

  In the braking system for motor vehicles re-

  shown in the figure, a tandem brake master cylinder 1

  forms a structural unit with a hydraulic ef- amplifier

  strong braking 2. The master cylinder in tandem braking 1 commu-

  classic way with two compartments 5, 6 of a tank

  see without pressure 7 via reservoir ports 3, 4. In a third chamber 8 of the reservoir 7 opens an outlet for

  reservoir 9 of the brake force amplifier 2.

  A hydraulic power supply system 10, comprising

  nant a pump 11 driven by a motor and a pressure accumulator

  sion 12, supplies the brake force amplifier 2 with li-

  pressure which is taken from the compartment 8 and which is supplied to a pressure orifice 13 of the brake force amplifier 2. By means of annular grooves and holes, the reservoir outlet 9 and the pressure port 13 communicate with a brake valve 14 mounted in parallel with a piston

  amplifier 15. The actuation of the brake valve 14 is ef-

  carried out by a crossed lever mechanism 16 which is pivotally mounted in an amplifier chamber 17 and which transmits to a control slide 19 of the brake valve 14 a relative movement between an actuating element 18, which can be connected to the brake pedal,

and the amplifier piston 15.

  The rod piston 21 of the tandem brake master cylinder 1 rests on the amplifier piston 15 by means of a

  pusher 20. Two pressure chambers 23, 24 separated from one another

  tre are delimited in the tandem braking master cylinder 1 by a floating piston, these chambers being in communication with the reservoir 7 through central valves 25, 26 which are provided in the floating piston 22 and in the piston with rod 21 and who are

  open in the initial position shown, and through

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  compartments 27 and 28 and connecting lines not shown me-

  leading to the tank openings 3, 4. Braking lines 29, 30 starting from the pressure chambers 23, 24 lead to inlet valves 31, 32 and, from 11, to the cylinders of a front left wheel brake VL and a right front wheel brake VR of the braking system for motor vehicles. In addition, a brake line 33 leads from the amplifier chamber 17 to the cylinders of a rear wheel brake.

  UL left and RH rear wheel brake RH brake system

  swimming for motor vehicles. The wheel brake cylinders may

  wind be isolated from the brake lines 29, 30, 33 by electrical

  valves 34, 35, 36 open in the initial position, and they can

  be connected to a return line 40 opening into the compartment

  ment 8 of the reservoir 7 through solenoid valves 37, 38, 39 closed

  in the initial position. The solenoid valves 34 to 39 are part of a

  anti-lock positive not shown and are used to control the brake actuation pressure in the wheel brake cylinders when

anti-blocking regulation.

  The inlet valves 31, 32 located on the brake lines 29, 30 are mounted in parallel with each other on a connecting line 41 which can be connected to the return line by a control valve 42, electromagnetically controlled by

  the 'hntiblocagd' device, when the valve 42 is in the initial position

  tial, and which can be connected to the amplifier chamber 17 via the brake line 33 when the valve 42 is

  in the switched position. In addition, the inlet valves 31, 32 are re-

  directly related to the return line 40.

  The two inlet valves 31, 32 are of identical design.

  than. They consist of a valve case 43 provided with a stepped case bore 44 which is closed at its front ends by walls 45, 46. The case bore 44 is divided into three compartments 49,, 51 by a first control piston 47, housed in the larger diameter bore portion, and by a second control piston

  48, housed in the bore portion of smaller diameter. The compar-

  timent 49 is delimited by the wall 45 and by the control piston 48 and it is connected, on the two valves 31 and 32, to the line of

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  connection 41. The compartment 51 is delimited by the wall 46 and by the control piston 47. In the inlet valve 31, it is connected to the

  brake line 29 leading to the brake master cylinder in tan-

  dem I and, on the inlet valve 32, to the brake line 30 me-

  nant to the tandem brake master cylinder 1. The intermediate compartment 50 is delimited at the same time by the two control pistons 47, 48 and by an abutment manthon 52 which is integral with the boot and which surrounds the small stage of the piston of control 47. In each case, compartment 50 is connected, in the inlet valve

  31, bypassing the brake line 29 leading to the cylinders

  of the wheel brakes and, in the inlet valve 32, that of the braking line 30. The stop sleeve 52 and the stage of the control piston 47 form an annular chamber 33 which, in the two valves inlet 31, 32, is connected to the return line 40 leading

to tank 8.

  A central bore opening 54 made in the piston

  control 47 connects compartments 50 and 51 and forms, with the surface

  this end of the piston close to the compartment 50, a valve seat 55 which can be closed by a valve element 56. The valve element 56 is housed sliding in a bore 57 of the control piston 48 and

  is pushed by a valve spring 58 towards the piston

  command 47, against a stop provided on the control piston 48. Between

  the valve element 56 and a stop pin 59, which is fixed to the wall

  king 45 and which extends into bore 57, a ball of val-

  ve 60 which cooperates with a valve seat ring 61 which is fixed to

  the bore 57 and which surrounds the narrowed end of the valve element

  ve 56 at a distance from the latter. The valve ball 60 is pushed in.

  the valve seat ring 61 by a valve spring 62 bearing on the control piston 48. In addition, between the control pistons 47, 48 is inserted a compression spring 63 which pushes the control pistons 47, 48 in the initial position shown in which the control piston 47 rests against the wall 46, and

  the control piston 48 rests against the wall 45 by means of

  re of the valve seat ring 61, the valve ball. 60 and the

stop rod 59.

  The operating mode of the vehicle braking system

  cules automobiles described is as follows: In the figure, the tandem brake master cylinder 1, the braking force amplifier 2 and the inlet valves 31, 32 are shown while the brakes are in the released position. To apply the brakes, the brake pedal causes the actuating element 18 to move in the direction of the amplifier piston, which has the effect of introducing into the amplifier chamber.

  17, through the brake valve 14, pressure liquid from

  from the power supply system 10. The increasing pressure in the amplifier chamber 17 moves the amplifier piston in the actuating direction and thus actuates the rod piston 21 and the floating piston 22 resting elastically on the piston with rod 21. The central valves 25, 26 are closed, so that, in the

  pressure chambers 23, 24 can build up a pressure which

  page to the brake cylinders of the front wheels VL, VR via-

  re braking lines 29, 30, open central holes 54 made in the inlet valves 31, 32, and solenoid valves 34,

  also open. At the same time, the intro-

  duit by the brake valve 14 leaves the amplifier chamber 17 and is transmitted, via the brake line 33 and

  of the open solenoid valve 36, to the cylinders of the rear wheel brakes

  re HR, HL. During this brake actuation phase, the actuation pressure acting on the wheel brake cylinders is controlled by the brake valve 14 as a function of the force

  actuation exerted on the brake actuating element 18.

  During this actuation phase, the valve seat rings 61 of the control pistons 48 remain closed. The pressure prevailing in the brake lines 29, 30 is only active in the

  compartments 50, 51 of the inlet valves 31, 32 and acts on the over-

  end faces of different sizes of the control pistons 47, so that comparatively low pressures are sufficient to move the control pistons 47 against the force of the compression springs 63 toward the valve members 56, until they are in abutment against the mound sleeves 52. Given

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  that the displacement stroke of the control pistons 47 is less

  re at the closing stroke of the valve seats 55, the connection between the tandem brake master cylinder 1 and the brake cylinders

wheel remains open.

  When the anti-blocking device "detects an immediate blocking

  nent, the control valve 42 is actuated, which allows the press-

  sion of the amplifier chamber 17 to propagate through the connecting line 41 to reach the compartments 49 of the valves

  input 31, 32. The control pistons 48 are thus moved cons

  the stop sleeves 52, the valve elements 56 being applied

  ques against the valve seats 55 at first and closing the through holes 54, the valve seat rings 61 then being detached by the valve balls 60 which rest against the

  valve elements 56, and the compartments 49 being connected to the

  compartments 50. The brake lines 29, 30 coming from the master-

  tandem cylinder 1 are therefore closed, so that the rod piston 21 and the floating piston 22 can no longer be moved, even if the actuation pressure increases, but remain in the actuation position previously reached , in which they

  still have sufficient actuation travel to allow

  tre, in the event of failure of the energy supply system 10 or of the anti-lock device, reapply the wheel brakes

  before VL, VR without applying the brakes again. The cylin-

  from the two front wheel brakes VL, VR, just like those from the brakes

  rear wheel HL, HR, are then supplied with pressurized fluid

  sion from the amplifier chamber 17 through the inlet valves 31, 32, so that at the start of the slip regulation,

  alternating switching of the solenoid valves 34 to 39 provides sufficient

  pressure fluid to allow a new pressure build-up after each pressure drop in the brake cylinders

wheel.

  If no pressure can be established in the brake line 29 when the brakes are applied, due to a leak due, for example, to a defective seal in the tandem brake master cylinder or to the rupture of the line braking, the

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  control piston 47 remains in the position shown in the figure

  re, in which it abuts against the wall 46. In this po-

  position, the distance between the valve seat 55 and the valve element 56 is so great that the valve element 56 does not reach the valve seat 55 when the control piston 48 comes to bear against the stop sleeve 52. In this case, the valve ball 60 cannot therefore rest on the valve element 56, so that the seat ring

  valve 61 remains closed. If, during braking of this type, the

  positive anti-lock is then activated and if the control valve 42 is open, the pressure introduced into the connection line 41 cannot escape through the inlet valve in the direction of the defective brake line. The intact braking circuits of the braking system for motor vehicles can therefore ensure unrestricted braking, even if the anti-lock device is used, and complete failure of the braking system cannot

not happen.

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Claims (8)

  1. Hydraulic braking system for a motor vehicle   the, comprising a brake master cylinder, a brake force amplifier powered by a hydraulic power supply system for actuating the master brake cylinder, a brake valve for controlling the actuation pressure in the chamber of the brake force amplifier, and comprising cylinders   wheel brake which, through control valves of a device   slip regulation, can be connected to the tank without pressure   power supply system or at least one brake line   swim communicating with the output of the brake master cylinder, the   said brake line being provided with an inlet valve controlled by pressure, which makes it possible to close the outlet of the brake master cylinder and to connect the wheel brake cylinders to the chamber of the brake force amplifier by via a control valve for the regulating device, characterized in that, when the inlet valve (31, 32) is in the initial position, the braking line (29, 30) is open and the orifice (41) leading to the amplifier chamber (17) is closed, and in that the inlet valve (31, 32) can only be switched to the open position when it simultaneously receives pressure from the chamber amplifier (17) and a   brake line pressure (29, 30), the output of the master   brake linder (1) being closed and the wheel brake cylinders   being connected to the amplifier chamber (17) when the supply valve trée is in the open position.   2. Braking system for motor vehicles according to claim 1, characterized in that the inlet valve (31, 32) comprises two control pistons (47, 48) which can move one   towards each other and delimiting a valve chamber (50) open di-   rection of the road brake cylinders and that the two pistons   control (47, 48) have valve seats (55, 61) which can   can be closed in the same direction by valve elements (56, 60) resting on each other, the distance between said valve seats - 12 - - 12 -2586219   (55, 61) being greater than the distance between the valve elements (56, 60) when the control pistons are in the initial position, and being less than this distance when the control pistons are in the open position.   3. Motor vehicle braking system in accordance with   any one of the preceding claims, characterized in   that the first control piston (47), which can be stressed by the pressure prevailing at the orifice of the brake master cylinder, is a stepped piston whose extreme stepped face, close to the second control piston (48), delimits a room (53) which communicates with a pressureless tank (7).   4. Motor vehicle braking system in accordance with   any one of the preceding claims, characterized in   that the actuating stroke of the control pistons (47, 48) is   mitée by a stop sleeve (52) which is integral with the shoemaker and in which the small diameter portion of the first control piston   (47) is tightly guided.   5. Motor vehicle braking system in accordance with   any one of the preceding claims, characterized in   that a compression spring (63) is interposed between the pistons of command (47, 48).   6. Braking system for motor vehicles in accordance with   any one of the preceding claims, characterized in   that the two valve elements (56, 60) are housed in a central bore (57) of the second control piston (48) which can be pressurized by the pressure of the amplifier chamber (17), and in that that the valve element (56) assigned to the valve seat (55) of the first   control piston (47) is held in the open position by a stopper   tee provided on the second control piston (48).   7. Braking system for motor vehicles in accordance with   any one of the preceding claims, characterized in   in the initial position, the valve seat (61) of the second control piston (48) bears on the corresponding valve element (60),   said valve member (60) being applied against a plug pin tee (59) integral with the shoemaker. - 13 - 2586219   8. Braking system for motor vehicles in accordance with   any one of the preceding claims, characterized in   that the brake master cylinder (1) is a tandem brake master cylinder to which two groups of wheel brake cylinders (VL, VR) are connected by means of two separate brake lines (29, 30), a pressure-controlled inlet valve (31, 32) being located on each brake line (29, 30) and said inlet valves (31, 32) being connectable together to the amplifier chamber (17) through the control valve (42) of the   regulation device, slip.