DE3446590A1 - Brake system for vehicles - Google Patents

Abstract

The invention relates to a brake system for motor vehicles, for example passenger motor vehicles, which are provided with at least one wheel brake, a brake pedal and a hydraulic circuit connecting the brake pedal to the wheel brake. According to the invention, at least one sensor (90, 91) is provided in order to detect a certain operating state of the vehicle, for example the vehicle speed, the operation of the accelerator pedal, the fastening of the driver-seat safety belt, the operation of the handbrake etc. In the hydraulic circuit, a control valve (for example 52) is provided by means of which in the activated state hydraulic pressure is transmitted to the wheel brake (117), independently of any release of the brake pedal (115). A control circuit (for example 53) is connected to the sensors (90, 91) and the control valve (for example 52), by means of which the control valve (52) can be actuated in a predetermined operating state of the vehicle. <IMAGE>

Description

Braking system for vehicles

The present invention relates to a braking system for vehicles, in particular passenger cars, with at least one wheel brake, a brake pedal as well as a pressure medium circuit connecting the brake pedal to the wheel brake according to FIG the preamble of claim 1.

When driving a vehicle, such as an automobile, turns out to be it is often desirable to maintain the existing braking force even when even if the brake pedal is released, for example when the vehicle is on is brought to a stop on a sloping road or within traffic congestion frequent stopping appears necessary. For this reason are already Brake systems for motor vehicles known, -which depending on a certain State the braking force is automatically generated or maintained.

Such a brake system is provided with a valve unit, which are within the brake line between the brake master cylinder and the wheel brake is arranged to thereby selectively disconnect or disconnect the Control connection via the brake line.

When the intended brake pedal is depressed, it becomes more hydraulic Transfer pressure to the wheel brake, whereupon the valve unit based on a predetermined Operation, such as releasing the brake pedal is operated so that on This way the hydraulic pressure also applies to the wheel brake itself over the point in time the operation of the brake pedal is maintained.

Another known brake system is between the brake pedal and the master cylinder, a pneumatic brake booster is provided, wherein this brake booster has an outer housing with a power piston arranged therein has through which the interior of the housing using a flexible membrane is divided into two pressure chambers. The power piston is with a delivery shaft connected, with which the piston of the master cylinder is actuated.

Under normal conditions, when the brake pedal is depressed, atmospheric pressure is reached into the pressure chamber, from which the gases flow into a vacuum chamber, as soon as the brake pedal is released.

However, when a certain operation occurs, the in the pressure prevailing in the pressure chamber even when the brake pedal is released received, so that the effectiveness of the wheel brake is maintained in this way.

It is also a hydraulic braking system for motor vehicles known (see Japanese Patent Application 41838/1977), in which between the Brake pedal and the master cylinder a pneumatic servo brake booster is provided. The brake system in question has an electromagnetic one Element on which between the brake pedal and the input shaft of the brake booster arranged is. When a certain operating condition of the vehicle occurs, the electromagnetic Element activated, whereby the input shaft in the actuated state automatically is locked. It is found, however, that such an electromagnetic element has a relatively high electrical power consumption and that the entire construction is relatively complicated.

Finally, a brake system for motor vehicles is also known (see Japanese utility model application 60563/1983), in which with the help of a electromagnetic element locks the brake pedal in the braked Position is feasible. In this case a brake interlock circuit is provided, from which, in a given situation, a brake lock signal to the electromagnetic element is emitted.

The brake system in question is also equipped with a seat sensor for generation a signal when the driver's seat is not loaded, an alarm to generate an alarm signal with the simultaneous presence of the brake lock signal and the seat signal as well as an enabling circuit for enabling the brake interlocking circuit and the alarm provided depending on the actuation of a parking brake.

Although the electromagnetic element in question for locking of the brake pedal is not shown in full detail in this case, so may however, it is believed to be quite complicated to construct is and that a relatively high power consumption due to this electromagnetic Element comes about.

It is therefore the object of the present invention to provide the brake system of the type mentioned to the effect that with relatively easier Construction of the Maintaining the braking force required Power consumption is relatively low.

According to the invention this is achieved in that the brake system with at least one sensor, such as a vehicle speed sensor, an accelerator pedal position sensor, a seat belt buckle sensor and / or a handbrake actuation sensor is that, furthermore, a control valve within the hydraulic pressure medium circuit is provided, which ensures in the actuated state that regardless of a possible release of the brake pedal hydraulic pressure on the wheel brake is exercised and that in addition a control unit connected to the sensors is provided with which activation in certain driving states of the vehicle of the control valve takes place.

An advantageous development of the invention is that the same is provided with a pneumatic brake booster, which is constructed as follows is: a) inside the outer housing is a flexible diaphragm with a one on it attached power piston is provided, making the interior of the housing into a Pressure chamber of constant pressure and a pressure chamber of variable pressure is divided, b) a valve mechanism is provided within the power piston, which with communicates with an input shaft, whereby. the one ruling within the chamber Pressure is controllable, c) the power piston (4) is also provided with a delivery shaft connected, via which the power output takes place, d) between the output shaft and a counter-pressure mechanism is also provided for the input shaft, with which a certain counter pressure can be exerted on the input shaft, e) within a control chamber is arranged a control piston through which the control chamber divided into a constant pressure chamber and a variable pressure chamber and f) the control piston provided with the input shaft is designed in such a way that that it exerts a force on the input shaft in the brake actuation direction, as soon as the control piston in the presence of a differential pressure between the two Chambers is moved, the control valve with the brake booster in such a way is connected that the pressure prevailing within the second chamber can be influenced is (Fig. 1).

Advantageous further developments of the invention result from the further subclaims.

The invention will now be described in greater detail on the basis of exemplary embodiments will be explained and described, reference being made to the accompanying drawings is. 1 shows a longitudinal sectional view of a vacuum brake booster according to a first embodiment of the invention with simultaneous representation the electrical circuit for controlling the brake booster concerned, FIG. 2 is a side view, partly in section, of the brake booster from FIG Fig. 1, Fig. 3 is a detailed view of the brake lines and the electrical Circuit of the brake booster of Fig. 1, 4 is a graph to show the dependency of the pressure differences occurring in the power piston and of the control piston in the brake booster of FIG. 1, FIG. 5 is a curve diagram to explain the dependency of the input and output force of the brake booster 1, FIG. 6 shows a circuit diagram similar to FIG. 3 of a hydraulic circuit according to FIG a second embodiment of the invention, FIGS. 7 and 8 are graphs similar 4 and 5 of the second embodiment of FIG. 6, FIG. 9 is a side sectional view similar to FIG. 1 of a brake booster according to a third embodiment of FIG Invention, FIGS. 10 and 11 are graphs of the time-dependent braking vehicle speed and similar parameters of the brake booster of FIG. 9, FIG. 12 a lateral View, partly in section, of a modified embodiment of the brake booster 1 and 13 show a side view, partly in section, of a brake booster according to a fourth embodiment of the invention, Fig. 14 and 15 are schematic circuit diagrams of the hydraulic and electrical circuits, respectively a fifth and sixth embodiment of the invention, and Fig. 16 is a schematic Circuit diagram of a modified embodiment of the circuit arrangement of Fig. 15th

Figs. 1 to 5 relate to a first embodiment of the invention. Fig. 1 shows the housing 1 of a brake booster, which is part of a brake system for motor vehicles is. This housing 1 consists of a front housing part 2 and a rear housing part 3. Inside this housing 1 is with the help of a A power piston 4 is mounted on the flexible diaphragm 5, the power piston 4 and the membrane 5 the interior of the housing 1 in one in the drawing on the left Side shown first front chamber A and a first rear chamber B share.

The outer circumference of the membrane 5 is between the two housing parts 2, 3 clamped while the inner circumference of this diaphragm 5 on the power piston 4 is attached.

The power piston 4 consists essentially of a piston plate 6, a piston holder 7 and a valve body 8. The inner circumference of the annular formed piston plate 6 is firmly together with the membrane 5 between the piston holder 7 and the valve body 8 clamped. According to FIG. 2, the piston holder 7 and the valve body 8 held together by means of screws 9 and corresponding nuts 10, whereby a control chamber 11 is formed between them. Within this Control chamber 11, a control piston 13 is held by means of a flexible membrane 12, whereby the interior of the control chamber 11 into a second front chamber C and a second rear chamber D is divided. According to Fig. 2 are in the area of the screws 9 sealing rings 14 are also provided.

One or more bores 16 are located inside the piston holder 7 provided, whereby a connection between the two chambers A and C is established will. On the front side of the piston holder 7 there is also a protruding one Part 17 is provided through which a channel 18 passes. This channel 18 is standing in connection with a further channel arranged inside the valve body 8 19, thereby communicating with the second rear chamber D.

A central stepped bore 20 is provided within the piston holder 7, which have a small diameter area and a large diameter area having. In the large diameter area of the stepped bore 20, one is off an elastic material, for example rubber, existing counter-pressure disk 21 and a flange 23 provided at the rear end of a dispensing shaft 22 Diameter used. The counterpressure disk 21 is in a recess 24 of the flange 23 used.

The rear end portion of the valve body 8 is slidable stored within a central opening of the rear housing part 3. To this The purpose is a sealing element between the rear housing part 3 and the valve body 8 25 provided. Inside the valve body 8 is a central stepped bore having a valve bore portion 26 of large diameter and a valve bore portion 27 small diameter provided. Inside the valve bore portion 27 is a plunger 28 is slidably mounted using a sealing ring 29.

This plunger 28 has a small area at its front end Diameter, which is slidable within the small diameter range the stepped bore 20 of the piston holder 7 is arranged. The front end area of the plunger 28 passes through the central areas of the flexible diaphragm 12 and of the control piston 13 and is attached to the diaphragm with the aid of a fastening element 30 12 and the control piston 13 attached. The rear end of the plunger 28 is with a recess 32 is provided in which a ball shoulder 34 is mounted, which is on front end of an input shaft 33 is provided.

A brake pedal, not shown, is connected to the rear end of the Input shaft 33 connected. The counter pressure disk 21 and the plunger 28 form a counter pressure mechanism to apply a counter force of the dispensing shaft 22 to the input shaft 33 to transfer.

The brake booster in question is also concentric with two mutually arranged valve seats 35 and 36 are provided, which in the area of the rear The end of the valve bore section 27 and the plunger 28 come to rest. Within of the valve bore portion 26 is made of an elastic material such as rubber existing flap valve 37 is provided, which is in operative engagement with the valve seats 35 and 36 reached. The annular rear end portion of the flap valve 37 is fixed within the valve bore portion 26, while the radially extending annular anterior Area of this flap valve 37 is pressed against the valve seats 35 and 36 under the influence of a compression spring 39.

The compression spring 39 is with the help of an annular shoulder 38 of the input shaft 33 held.

Inside the piston holder 7 and the valve body 8 is a channel 42 is provided, which is the first front chamber A with the valve bore portion 26 on the rear side of the valve seat 35 connects. Inside the valve body 8 a channel 43 is also provided, which the first rear chamber B with the valve bore portion 27 connects. Finally, around the plunger 28 are a noise dampening ring 45 and an air filter ring 44 are also provided.

In the normal non-actuated state of the brake booster is between the rear surface of the platen 21 and the front surface of the plunger 28 a predetermined distance 46 is maintained. Between the front one Housing part 2 and the power piston 4, a return spring 47 is also provided, which pushes the power piston 4 backwards. The front housing part 2 is finally provided with two pipe sockets 48 and 49, of which the pipe socket 48 establishes a connection with the first chamber A, while the pipe socket 49 establishes a connection to the channel 18.

A stretchable sealing element 50, for example a bellows, seals the pipe socket 49 and the channel 18 opposite the first chamber A from. On the back Housing part 3, another pipe extension 51 is attached, which a connection with the pressure chamber B.

The pipe socket 48 is with a vacuum source, such as the Intake manifold of an internal combustion engine, connected and leads also to a valve unit also connected to the pipe sockets 49 and 51 52. This valve unit 52 has three, according to FIG. 3, which are closed in the idle state electromagnetic valves 54 to 56 and an electromagnetic valve that is open in the idle state Valve 57 on, the two electromagnetic valves 54 and 55 with corresponding Regulators 58 and 59 are connected to achieve constant volume ratios.

of the electromagnetic valves 54 to 57 are electrically connected to a Control unit 53 connected. The electromagnetic valve 57 is finally still connected to the pipe sockets 48 and 49, while the electromagnetic valve 56 is connected to the pipe connections 51 and 49.

The control unit 53 receives signals 60, which certain operating states of the vehicle. These are signals such as a vehicle speed signal E, an accelerator pedal position signal F, a handbrake operating signal G, a vehicle weight display signal H, a seat belt buckle indication signal I, and the like signals. As soon as appropriate Signals 60 are fed to the control unit 53, the electromagnetic activation takes place Valves 54 to 57. Finally, a sensor, not shown, is also provided, to be able to determine the actuation of the brake pedal.

The functioning of the braking system described is as follows: In the normal, non-actuated state, as shown in FIGS is and in which the brake pedal is not actuated, the pipe socket 49 protrudes the electromagnetic valve 57 with the pipe socket 48 in connection, which is permanent with the vacuum source connected is. The two pressure chambers C and D are therefore exposed to the same negative pressure. The brake booster in question thus works like an ordinary single-diaphragm vacuum brake booster.

Accordingly, when the brake pedal is depressed, a corresponding Force transmitted to the input shaft 33 so that the plunger 28 forward is pushed. The provided on the plunger 28 valve seat 36 thus lifts from the Flap valve 37 down so that atmospheric air over on the rear side of the valve body 8 provided opening, the inside of the valve bore portion 28 of the valve body 8, the central opening of the flap valve 37, the distance between the flapper valve 37 and the valve seat 36, the inside of the valve bore portion 27 of the valve body 8 and the radial channel 43 of the valve body 8 in the first Pressure chamber B can reach. Since .die first pressure chamber A exposed to the negative pressure is, there is a pressure difference between the two chambers A and B, so that the Power piston 4 receives an increased compressive force in the forward direction.

This compressive force is transmitted to the delivery shaft 22 while a counterforce of this delivery shaft 22 via the counter pressure disc 21 and the plunger 28 is transferred to the input shaft 33. The between the plunger 28 and the Counterpressure disk 21 existing spacing 46 is effective to avoid an erratic To achieve response characteristics. Due to the forward displacement of the valve body 8, the distance between the flap valve 37 and the valve seat 36 is reduced gradually down to a value zero, so that the brake booster is in its equilibrium state achieved. The brake booster generates an output force which is the same the product the input force and the brake booster factor is.

If the brake pedal is released again as a result, shifts the tappet 28 with the flap valve 27 backwards, whereby the valve seat 35 of the valve body 8 lifts off the flap valve 37 and the two pressure chambers A and B can be associated with one another.

The power piston 4 returns to its starting position.

When the weight of a motor vehicle increases or decreases in number is changed by passengers or the weight of the cargo, then it seems advantageous to that the brake booster factor of the brake booster changes automatically will. In the case of conventional braking systems in motor vehicles, the driver of the vehicle must however, in such a case change the pressing force on the brake pedal to achieve optimal braking of the motor vehicle regardless of the vehicle weight to be able to.

In the first embodiment of the invention is between the with the pressure chamber A connected to the pipe socket 28, the pressure chamber A connected to the pipe socket 51 Pressure chamber B and the pressure chamber D connected to the pipe socket 49, a valve unit 52 is provided, with which the brake booster factor, i.e. the ratio between input force and output force, according to the pressure difference between the two chambers B and A and correspondingly from different sensors, for example signals derived from a sensor that determines the vehicle's weight can be.

The control unit 53 shown in Fig. 1 receives this from a Sensor, not shown, derived vehicle speed signal E, the accelerator pedal position signal F. the parking brake actuation signal G, the vehicle weight display signal H and the seat belt buckle indicator signal I.

As soon as the signals E, F, G and I indicate a predetermined state, the control unit 53 controls the valve unit 52 in accordance with the following table 1: Table 1 W <W1 W1 # W <W2 W2 # W <W3 W3 # W Valve 54 off on off off Valve 55 off off off on Valve 56 off off on off Valve 57 off on on on where W corresponds to the weight of the vehicle and W1 W2 <W3.

3 shows the state for W <W1, in which case the brake booster acts as a single-diaphragm brake booster.

As soon as W1 is # W # W2, the two pressure chambers B and D protrude the valve 54 and the regulator 58 in communication with each other. The regulator 58 regulates the pressure inside chambers A, B and D according to the following equation: VA - VD = K (VA - VB) where 0 <K <1, VA is the negative pressure in the chamber A, VB the negative pressure in the chamber B and VD the negative pressure in the chamber D corresponds to. The control piston 13 is the differential pressure between the two Chambers D and C exposed to which in a predetermined relationship to the differential pressure is between the chambers A and B, so that the shaft 33 acting on the input Input force is increased.

As soon as W2 W is W3, chambers B and D are above the electromagnetic Valve 56 in communication with each other while the differential pressure between the chambers C and D is equal to the differential pressure between chambers A and B. Since K <1, there is a further increase in the input force.

In the event that W3 <W, the chambers B and D are above the electromagnetic valve 55 and regulator 59 in communication with each other. Of the Regulator 59 acts in a similar way to regulator 58, but with the predetermined pressure ratio K ') 1, so that the differential pressure between the chambers C and D is greater than the differential pressure between chambers A and B.

The input force acting on the input shaft 33 is applied thereto Way further enlarged. Figs. 4 and 5 show the above-mentioned conditions. As can be seen from the figures in question, there is the possibility of the braking force increases automatically depending on an increase in the vehicle weight raise. FIG. 5 also shows the values I1 to I4, which correspond to the jump-shaped Represent the use of the delivery force.

In the first embodiment, the abrupt use of the Output force and the brake booster factor automatically depending on a Change in vehicle weight controlled. However, the present invention is not limited to such an embodiment.

6 to 8 show a second embodiment of the invention in which the valve unit 52 provided in the first embodiment is replaced by a valve unit 62 which is made up of an electromagnetic valve 63 and a regulator 64 generating a constant differential pressure. The valve unit 62 is controlled with the aid of a control unit 65 to which signals similar to the signals 60 supplied in the first embodiment are supplied. Furthermore, the relevant control unit 65 is supplied with a further signal 66 which corresponds to the input force transmitted on the input shaft or the pressure force transmitted to the brake pedal. The control unit 65 controls the electromagnetic valve in accordance with the following table 2 as soon as the brake pedal is subjected to a normal actuation force: Table 2: W # W1 W1 # W <W2 W2 # W Valve 63 off on on Position of the Regu- l1 l1 l2 lators 64 where W1 <W2 and t1 <t2. In the normal or de-energized state, the setting of the regulator 64 is as long as W <W1, the valve 63 is in the state shown in FIG. 6, in which the chamber D is connected to the vacuum source and the brake booster acts as a single-membrane brake booster .

However, if W1 # W <W2 then chamber D is over the regulator 64 and the valve 63 are connected to the negative pressure source, with the following condition prevails: VA D VD = the pressure difference between chambers C and D. and the control piston 13 increase the input force acting on the input shaft 33, whereby the output force is increased. As soon as the force signal 66 of the control unit 65 is supplied, the electromagnetic valve 63 is activated, which indicates that the brake booster is working. The connection between the pressure chamber B and the valve unit 62 is omitted in this case, since the a constant pressure differential regulator 64 is atmospheric pressure of the chamber D can feed.

As soon as W2 <W, the chamber D is via the regulator 64 and that Valve 63 is connected to the vacuum chamber A similarly to the case described above. However, the setting of the regulator 64 satisfies the following condition: VA - VD = l2 (l2> l1).

As a result, the input force continues to increase.

Figs. 7 and 8 show the characteristics of the second embodiment. So As can be seen from the figures, the brake booster factor is increased to kept a constant value, while on the other hand the use of leaps and bounds the initial force is changed significantly. With known brake boosters is to increase the output force in the starting state, the distance 46 between the The plunger and the counter-pressure disc are increased, but this has the consequence that the service life the counter pressure disc decreases significantly. In the context of the present invention results However, there is the possibility of a change in the abrupt operational characteristics to be carried out without adversely affecting the service life of the counter-pressure disk will.

The control mechanism shown in Fig. 3 or 6 can also modified to the effect that that prevailing between chambers C and D. Differential pressure is controlled in that the control unit 53 or 65 due to a braking delay derived signals supplied when braking the vehicle will.

FIGS. 9-11 deal with a third embodiment of FIG Invention. According to FIG. 9, a brake booster is provided which is constructed similarly to the brake booster of FIG. For this reason are in Fig. 9 corresponding parts of the brake booster with the same reference numerals as provided in Fig. 1, while on the other hand to a detailed description can be dispensed with. The pipe socket 51 shown in Fig. 1 is in this case omitted while during the constant with the vacuum source related pipe socket 48 via a pressure reduction valve 71 with a electromagnetic valve 72 is connected.

The electromagnetic valve 72 protrudes on the other side a flow reducing valve 73 in communication with the outside atmosphere. The pipe socket 48 is with another electromagnetic valve 74 and a differential pressure switch 75 connected. The valves 72 and 74 and the differential pressure switch 75 are connected to the pipe socket 49. Furthermore, a control unit 76 is provided, which is electrically connected to valves 72 and 74 and switch 75. The control unit 76 receives signals such as the vehicle speed signal E, the accelerator pedal position signal F and the handbrake actuation signal G supplied. In addition, inside the vehicle cabin, a manually operable one (not shown) is possible Switch provided, from which a signal M is derived, which is also the Control unit 76 is supplied. The control unit 76 finally receives another Differential switch signal N and possibly other signals.

Fig. 9 shows the non-actuated operating state in which the Chamber D through the channels 19 and 18, the pipe socket 49 and the valve 74 with the Vacuum source is connected, so that between the chambers C and D no differential pressure occurs and the brake booster acts as a single-diaphragm brake booster.

As soon as the control unit 74 is supplied with a vehicle speed signal E is, indicating that the vehicle speed is below a predetermined Is the speed value V1, at the same time an accelerator pedal position signal F occurs, whereby the non-actuated state is indicated, at the same time the handbrake actuation signal G indicates the non-actuated state and simultaneously the switch position signal M occurs, the electromagnetic valves 72 and 74 are activated at the same time, so that atmospheric pressure through the flow reducing valve 73, the electromagnetic Valve 72 and the pipe socket 49 can get into the chamber D. Because of the between The differential pressure resulting from the chambers D and C is followed by the control piston 13 moved forward, with the result that the plunger 28 with respect to the valve body 8 also receives movement in the forward direction. The valve seat 36 of the The plunger 28 is thus lifted from the flap valve 37, so that atmospheric pressure via the opening at the rear end of the valve body 8, the middle opening of the flap valve 37, the distance between the valve seat 36 and the flap valve 37 and the radial opening 43 of the valve body 8 can get into the chamber B. This in turn has the consequence that between the chambers B and A there is a differential pressure occurs so that the power piston 4 receives a forward thrust. The brake booster consequently generates an output force which is determined by the equilibrium between the of the counter-pressure disc 21 on the plunger 28 transmitted counterforce and the due to the differential pressure between chambers B and C. is fixed.

As soon as the vehicle comes to a stop due to the procedure described above has been brought, the manual switch operated simultaneously with the accelerator pedal If the brake pedal and the handbrake are released, the speed decreases V of the vehicle decreases rapidly, while at the same time the braking deceleration g at time of the vehicle at a standstill has reached its maximum value. The front part of the vehicle lowers itself, whereupon it swings back when the vehicle is stationary comes about upwards. Around the occurring phenomena control, it is provided in the embodiment in Fig. 9 that upon decrease the vehicle speed V to a predetermined speed value V2 automatic energization of the electromagnetic valve 72 comes about so that the in the chamber D prevailing pressure is lowered. In this way one results predetermined reduced pressure difference which is generated by the pressure reduction valve 71 is set. If then in the sequence the vehicle speed V except for one If the value is reduced to zero, the electromagnetic activation takes place automatically Valve 74, whereby the braking force is increased. Fig. 10 shows the running Occurrence. By operating the hand switch, the two valves 72 and 74 activated so that the braking force Fg gradually increases while the vehicle speed V gradually decreases. The pressure difference between chambers C and D. also gradually increases during this process. The occurring pressure difference can exceed a predetermined value of a differential pressure, which is determined by the switch 75. As soon as the vehicle speed V up to has decreased a value V2, the valve 72 is activated, whereby it is achieved that the braking force Fg drops to a predetermined value. With this arrangement there is a slight lowering of the front part of the vehicle and a renewed swing back as shown in the figure, but these oscillation processes are in the Significantly reduced compared to known brake systems.

The differential pressure switch 75 is used to switch off the valve 72 to prevent until the differential pressure between chambers C and D. exceeds the pressure value specified by the switch 75, this pressure value almost equal to the given pressure of the differential pressure valve 71 is. 11 shows the sequence resulting in this connection.

The feature of automatically generating a braking force according to the Standstill of the vehicle proves to be advantageous for the prevention of rear-end collisions, generated by following vehicles after stopping the vehicle in question will.

A renewed release of the braking force can either be done with the help of the manually operated Switch or by pressing the accelerator pedal. A deactivation of the electromagnetic valves 72 and 74 can also according to FIG. 9 through Applying the handbrake can be triggered.

In the embodiment shown in FIG. 9, the braking force automatically generated by operating the manual switch so that the vehicle is brought to a stop in accordance with a predetermined braking sequence.

In the first embodiment, the rear housing part 3 is provided with a Pipe socket 51 is provided, which connects the chamber B to the valve unit 52 manufactures. In the modified embodiment shown in FIG on the other hand, the piston holder 7 is provided with a tubular extension 81 through which a channel 82 leads.

Furthermore, a connecting bore is located inside the valve body 8 83 is provided, which establishes a connection between the chamber W and the channel 82. The front housing part 2 is in this case with a pipe socket attached to it 84 provided, within which the tubular extension 81 is slidably mounted. The tubular extension 81 is also made of an expandable sealing element 85 surrounded, which seals against the Chamber A produces. By connecting the pipe socket 84 with a valve unit 52 it can be achieved that this embodiment operates similarly to the first embodiment. In the The embodiment shown in FIG. 12, however, proves to be used for fastening the brake booster on a vehicle as advantageous because all pipe sockets 48, 49, 84 in the area of the front housing part 2 are provided.

Fig. 13 shows a fourth embodiment of the invention in which the housing 1 'of a tandem brake booster from a front housing part 2 'and a rear housing part 3'. The housing 1 'is used to accommodate a front power piston 106, a partition 108 and a rear Power piston 8 ', these elements being the interior of the housing 1' in a vacuum chamber A ', a pressure chamber B', a negative pressure chamber C 'and a pressure chamber B' subdivide.

The front power piston 106 is made with the aid of a flexible diaphragm 105 mounted axially displaceably along the inner circumference of the housing 1 '. To the Front power piston 106 is a tubular member 107 having a small diameter portion and a large diameter portion, the small diameter portion passes through the central region of the front power piston 106 and is attached to the same.

A dispensing shaft 22 'provided with a flange 23' is within of the tubular member 107 arranged and attached to the same. According to FIG. 1 the left-hand front end of the dispensing shaft 22 'extends in a sealed manner through the front housing part 2 'to the outside of the Housing 1 'and is designed such that a connection with the piston one master cylinder not shown are produced can. At the rear end of the dispensing shaft 22 'is one in the axial direction extending recess 22'a is provided. The one having a large diameter Section of tubular member 107 is maintaining a seal within of the central part of the partition wall 108 mounted displaceably. Between the delivery staff 22 'and the inner circumference of the small diameter portion of the tubular element 107, a channel 106a is provided through which a permanent Connection between the chambers A 'and C' is established.

The outer peripheral region of the partition wall 108 forks into one rearwardly extending annular portion and one radially extending Area which is attached to the rear housing part 3 '. The radial after the area of the partition wall 108 extending on the outside is provided with connection openings 108a provided, while the rearwardly extending region of the partition wall 108 forms an annular chamber along the inner circumference of the rear housing part 3 ', which is part of the pressure chamber 'B'.

The rear power piston 8 'and associated parts are designed similarly to the first embodiment, with corresponding parts are provided with the same reference numerals with corresponding lines. The rear End of the valve bore section serving to slidably receive the plunger 28 ' 27 'is provided with a counterbore in which the tubular element 109 with his Areas of large and small diameter is used. The one small diameter having area of the tubular element 109 is used for the displaceable recording the reduced diameter front end of the plunger 28 ', during the large diameter area of the counter pressure disk 21 'and the rear end of an enlarged diameter Power transmission shaft 108 is used, the latter as a dispensing shaft for the rear Power piston 8 'is used. The front end of the power transmission shaft 108 'protrudes into a recess 22'a, which is provided at the rear end of the dispensing shaft 22 ' is. The brake booster in question finally also has an annular disk 110, with which the rearward movability of the plunger 28 ' is limited.

The pipe connections 49 'provided on the rear housing part 3' and 51 'are in communication with chambers B' and D ', respectively. These pipe sockets 49 'and 51 ′ are connected to one another to the outside via an electromagnetic valve 86. This electromagnetic valve 86 is designed such that in a first Position the chambers B 'and D' are in communication with each other, while in the second position a mutual separation comes about, although the Chamber B 'is brought into communication with the outside atmosphere. The electromagnetic Valve 86 is connected to a control unit 87 which receives the vehicle speed signal E which is derived from a sensor 90 attached to a suitable Position of the vehicle is attached to determine the vehicle speed. The control unit 87 is also supplied with the accelerator pedal position signal F, which is derived from a sensor, not shown, which then always sends a signal to disposal adjusts when the accelerator pedal is in the depressed state is located. The control unit 87 then receives the seat belt buckle indication signal I, which is issued by a seat belt buckle sensor whenever the The driver of the vehicle has put on the seat belt. Finally, the control unit 87 a steering wheel touch signal from a corresponding steering wheel touch sensor is also supplied will.

The control unit 87 causes the activation of the electromagnetic Valve 86 as soon as the supplied signals meet predetermined conditions. in the Normal operation, the electromagnetic valve 86 assumes its first state, in which the two chambers B 'and D' are in communication with one another. The control unit 87 is additionally provided with a warning unit 88 and a display device (not shown) connected to indicate the status of the supplied signals and when they occur certain conditions, for example in the absence of the seat belt buckle indicator signal I with simultaneous receipt of the accelerator pedal position signal F or the steering wheel touch signal trigger an alarm. The control unit is used to carry out the relevant processes 87 is connected to a voltage source 89.

The mode of operation of the brake booster shown in FIG. 13 will now be explained in more detail: Stand in the normal non-actuated state the two chambers B 'and D' via the pipe connections 49 'and 51' and the electromagnetic Valve 86 in communication with one another. Then when the brake pedal is depressed, move the input shaft 33 'and the tappet 28' together with the flap valve 37 ' or its front end area in relation to the rear power piston 8 ' forward, the latter in its position is held. The flap valve 37 'engages with the valve seat 35t of the rear Power piston 8 ', whereby the connection between the chambers C' and D 'is interrupted will. When the input shaft 33 'is pushed in further, the lifts on the Plunger 28 'provided valve seat 36' from the flap valve 37 ', so that on this Way atmospheric air can get into the chamber D '. The one entering chamber D ' Atmospheric air also flows over the pipe socket 49 ', the electromagnetic one Valve 86 and the pipe socket 51 'into the chamber B'. Stand on the other side the chambers A 'and C' via the pipe socket 48 'permanently with a vacuum source, for example the intake manifold of an internal combustion engine in connection. The front power piston 106 and the rear power piston 8 'are thereby pushed forward so that an increased output force is achieved in this way.

A corresponding counterforce is generated by the power transmission shaft 108 'is transferred to the plunger 28' via the counter-pressure disk 21 ', with the counter-pressure disk 21 'is elastically deformed.

If an operating state occurs as a result, in which due to of the vehicle speed signal E indicates that the vehicle speed is below a predetermined value, the accelerator pedal position signal F den not operated state indicates the seat belt buckle indicator signal I the closure of the Notifies seat belt and the steering wheel touch signal by touching the steering wheel indicates the driver of the vehicle, then the electromagnetic Valve 86 activated, which has the consequence that over the valve 86 and the connecting pipe 51 'atmospheric air can get into chamber B'. The front power piston 106 is therefore moved forward so that on this way a braking force is automatically generated. This automatic application of the brakes appears particularly advantageous when the vehicle operator is on an incline The road applies the brakes or a frequent application in a traffic jam the brakes is necessary.

If as a result of such an automatic braking process the The vehicle driver loosens the seat belt or lifts his hand off the steering wheel the warning unit 88 a warning signal, while after a predetermined period of time the electromagnetic valve 86 returns to the starting position shown in FIG. The vehicle driver must therefore within the above-mentioned period or before apply the handbrake before performing the actions mentioned. Furthermore it appears to be advantageous if a handbrake actuation sensor is also provided which is connected to the control unit 87, whereby it can be achieved that the electromagnetic valve 86 cannot return to its original position, before the handbrake has been applied.

The seat belt buckle sensor and / or the steering wheel contact sensor can may be omitted, so that an automatic braking force even then is triggered when the driver does not touch the steering wheel and / or the seat belt has not been created.

In the embodiment shown in Fig. 13 is within the Chamber A a simple coil spring 47 'is provided to the two power pistons 106 and 8 'to push backwards. However, it appears beneficial within the chamber C 'is also a weaker one than that Coil spring 47 ' formed further coil spring to provide to achieve that the power piston 8 'reliably moves into its non-actuated position as soon as for the automatic Actuation of the brake booster, the electromagnetic valve 86 is operated.

14 shows a brake system according to a fifth embodiment the invention. In this embodiment, a tandem master brake cylinder 116 is provided, which is operated with the aid of a brake pedal 115, whereby pressure fluid the two wheel brakes 117 and 118 is supplied. Between the master cylinder 116 and the wheel brake 117 is in the connection line an electromagnetic Valve 86§ inserted, with which the line connection can be interrupted. The relevant valve 86 'is controlled with the aid of a control unit 87', which in a corresponding manner to the control unit 87 of the embodiment of FIG Fig. 13 is formed.

The mode of operation of the embodiment shown in FIG. 14 is essentially identical to the mode of operation of the embodiment of FIG. 13 with the exception, however, that an automatic release of the brakes is not possible is.

Fig. 15 shows a sixth embodiment of the invention which is a Modification compared to the embodiment shown in FIG. 14 represents. the The hydraulic brake system is essentially identical to that of the embodiment of Fig. 14 formed. By doing however, the case in question is in the pressure line between the brake master cylinder 116 and the wheel brakes 117 electromagnetic valve 86 ″ used, which is similar to the electromagnetic Valve 86 'of Fig. 14 is formed, but via corresponding rods 121, 123 and 124 have a mechanical connection with the clutch pedal 120. Between the two linkages 123 and 124 is an electromagnetic connection unit 128 interposed, with which the connection between the clutch pedal 120 and the electromagnetic valve 86 "can be electrically controlled. This connection unit 128 is controlled by a control unit 87 ″, which is similar to the embodiments 13 and 14, the seat belt buckle indication signal I and the steering wheel touch signal is fed. The relevant figure also shows a brake operating lever 122, the internal engine 125, the engine clutch 126, and the transmission 127.

The described arrangement works as follows: As soon as the seat belt buckle indicator signal I and the steering wheel touch signal from the control unit 87 "are supplied, the electromagnetic connection unit 128 'takes those Position in which the two rods 123 and 124 are connected to one another. However, when the brake pedal 115 is operated and a depression at the same time of the clutch pedal 120 occurs, the electromagnetic is activated Valve 86 ", so that the braking force transmitted to the wheel brakes 117 even then is maintained when brake pedal 115 is released. However, in the event that the seat belt is not fastened or the driver of the vehicle does not touch the steering wheel, the electromagnetic link unit is interrupted 128 the mechanical connection between the valve 86 "and the Clutch pedal 120, so that in this case there is no possibility of the braking force automatically maintain.

Fig. 16 shows a modified embodiment in which the electromagnetic Connection unit 128 of FIG. 15 is replaced by an electromagnetic valve 129 is. This valve 129 assumes its open position as soon as the similar like the control unit 87 "of Fig. 15 configured control unit 87" 'both that Seat belt buckle signal I receives as well as the steering wheel touch signal. The clutch pedal 120 is connected to a clutch master cylinder 130 in this case, one of which from pressure fluid is supplied to the coupling 126 via a pipeline 131. The clutch master cylinder 130 is also via an electromagnetic valve 129 connected to the valve 86 "', the electromagnetic valve 129 in the Pipes 131 and 132 is inserted.

Accordingly, when both signals are supplied to the control unit 87 '' ' and at the same time the clutch pedal 120 is operated, pressure fluid flows from the clutch master cylinder 130 through the electromagnetic valve 129 to the control valve 86 "', whereby it is achieved that the pressure supplied to the wheel brakes 117 is maintained will.

In the context of the present invention there is thus the possibility of that at least one wheel brake regardless of the release of the brake pedal in the presence a predetermined operating state of the vehicle automatically in its braked State can be held or that at least one wheel brake without actuation of the brake pedal automatically in the presence of predetermined operating states of the vehicle is operated, whereby a corresponding improvement in operational safety of the respective vehicle is reached.

- blank page -

Claims (5)

Brake system for vehicles Patent claims 1. Brake system for vehicles, in particular passenger cars, with at least one wheel brake, a brake pedal as well as a pressure medium circuit connecting the brake pedal to the wheel brake, thereby g e k e n n -z e i c h n e t that the same with at least one sensor (90, 91) such as a vehicle speed sensor (90), an accelerator pedal position sensor, a Seat belt buckle sensor (91) and / or a handbrake sensor or the like is that, furthermore, a control valve within the hydraulic pressure medium circuit (52, 62, 72, 86, 86 ', 86 ", 86"') is provided, which ensures in the actuated state, that regardless of a possible release of the brake pedal (115) hydraulic Pressure is exerted on the wheel brake (117, 118), and that in addition one with control unit (53, 65, 76, 87, 87 ', 87 ", 87"') connected to the sensors (90, 91) is provided with which at certain Driving conditions of the vehicle the control valve is activated. 2. Brake system according to claim 1, characterized in that g e k e n n -z e i c h n e t that the same is provided with a pneumatic brake booster, which is constructed as follows: a) inside the outer housing (1) is a flexible one Diaphragm (5) is provided with an attached power piston (4), whereby the interior of the housing (1) into a pressure chamber (A) and a constant pressure Pressure chamber (B) of variable pressure is divided, b) within the power piston (4) a valve mechanism (28, 37) is provided which has an input shaft (33) is in communication, whereby the pressure prevailing inside the chamber (B) is controllable, c) the power piston (4) is also equipped with a delivery shaft (22) connected, via which the power output takes place, d) between the output shaft (12) and the input shaft (33) is additionally provided with a counter-pressure mechanism (21), with which a certain counter pressure can be exerted on the input shaft (33), e) A control piston (13) is arranged within a control chamber (11) through which the control chamber into a chamber (C) with constant pressure and a chamber (D) with variable pressure is shared and f) that provided with the input shaft (33) Control piston (13) is designed such that the same in the brake actuation direction exerts a force on the input shaft (33) as soon as the control piston (13) closes Presence of a differential pressure between the two chambers (C and D) shifted will, wherein the control valve (52) with the brake booster in such a way is connected that the pressure prevailing within the second chamber (D) can be influenced is (Fig. 1). 3. Brake system according to claim 2, characterized in that g e k e n n -z e i c h n e t that the control chamber (11) is arranged within the power piston (4) and that a second flexible membrane (12) is provided with which in communication with the control piston (13) a division of the control chambers (11) into the two chambers (C and D) takes place. 4. Brake system according to claim 2 or 3, characterized in that g e k e n n z e i c It should be noted that the control circuit (60) is provided with a manually operated switch which allows actuation of the control valve (52). 5. Brake system according to claim 1, characterized in that g e k e n n -z e i c h n e t that it is provided with a tandem type pneumatic brake booster is, which is constructed as follows: a) Inside the housing (1 ') is a first Diaphragm (105) is provided to which a power piston (106) is attached, whereby the interior of the housing (1 ') into a chamber (A') with constant pressure and a chamber (B ') is divided with variable pressure, b) within the power piston (106) a valve mechanism (28 ', 37') is mounted, with which the connection of the chamber (B ') variable pressure compared to the chamber (A') constant pressure and the External atmosphere can be produced or interrupted, c) the valve mechanism (28 ', 37') is connected to an input shaft (33 '), d) with the aid of a second membrane (12 ') and a control piston attached to it (13 ') is a second chamber (C') of constant pressure within the housing (1 ') and a second chamber (D ') of variable pressure is formed, e) the control piston (13') acts on a delivery shaft (22 ') and f) the force of the power piston (106) becomes transferred to the delivery shaft (22 ') with the aid of a power transmission shaft (108'), wherein the control valve (86) is connected to the brake booster such that in this way the pressure prevailing within the second chamber (D ') can be influenced is.