Brake circuit.

The invention relates to a brake circuit having at least one by the supply of brake pressure operated brake application device according to the preamble of claims 1 and 2. FIG.

Such a brake circuit is known from Figure 2 of EP-A-0088911. There is the electrical brake pressure control device of the electrical part of a driver-operated brake signal transmitter, an electronic system with an actual-value sensor and the electrically controlled part of a dual-circuit triggered relay valve. Upon actuation of the brake signal transmitter that emits an electrical signal which is fed to the electrical section of the relay valve, after preparation in the electronics and converted by the latter into braking pressure to the brake application. The mechanical brake pressure control device there consists of the pressure part of the brake signal transmitter and the pressure-dependent part of the dual-circuit triggered relay valve. "Mechanical" is this brake pressure control device in this case called because it converts the introduced into the brake signal transmitter operation quantity in a known manner by mechanical means in brake pressure to the brake application.

The known brake circuit is mainly operated by the electrical brake pressure control device. This is achieved in that the electrical signal, the two circuits controlled relay valve because of its great speed of propagation in the associated lines faster response brings a case of the output of the pressure part of the braking power generator brake pressure. If a fault occurs in the electrical brake pressure control device of the brake circuit by means of the mechanical brake pressure control device remains, albeit at a slower functional.

A disadvantage of the known brake circuit, that he is not available to the load sensing control by the electrical brake pressure control device. For the purpose of such control, the braking force delivered from the brake value transmitter electrical signal and thus of the brake pressure to the brake application device to be corrected depending on the load in a known manner. In the known brake circuit the electrical brake pressure control device would indeed cause a rapid response of the relay valve, and thus of the brake circuit in such a case. but then the Ansprechphase would case of the output of the pressure part of the brake signal transmitter and not load dependent corrected brake pressure take priority in controlling the relay valve and make the load-dependent correction of the braking pressure by the electrical brake pressure control device ineffective.

The invention is therefore based on the object, make a brake circuit of the type mentioned accessible by simple means the load-dependent brake force control by the electrical brake pressure control device.

This object is achieved by the specified in the patent claims 1 and 2 invention. Fort developments and advantageous embodiments are indicated in the dependent claims.

The invention provides for a malfunction in the electrical brake pressure control device switching to the mechanical brake pressure control device with simple mechanical means.

The known brake circuit is not the anti-lock means of the electrical brake pressure control device accessible. In this case, the findings made above in relation to the load-dependent brake force control shall apply accordingly. The invention also resolves this disadvantage.

The invention may be run in conjunction with any suitable pressure means.

The invention also allows simplification and cost reduction of the known brake circuit by enabling the replacement of this complicated and expensive, designed for dual-circuit driving through very different media, the relay valve by simply constructed and largely also commercially available components.

Further advantages of the invention are mentioned in the explanation now following based drawings exemplary embodiments. show under continuous use solid or dashed lines for pressure fluid lines and dash-dotted lines for electrical connections and the same reference numerals for components having the same functions<ul><li><b>Fig.1</b> a Pinzipskizze a brake circuit of the invention,</li><li><b>Fig.2</b> Training of the brake circuit</li><li><b>Fig.3</b> according to Fig.1,</li><li><b>Fig.4</b></li><li><b>Fig.5</b> an embodiment of the brake circuit according to Fig.1 with training,</li><li><b>Fig.6</b> another embodiment of the brake circuit according to Fig.1 with training,</li><li><b>Figure 7</b> another embodiment of the brake circuit according to Fig.1 with training,</li><li><b>Figure 8</b> a further development of the brake circuits according to Figure 5 to 7,</li><li><b>Fig.9</b> a vehicle brake system with two brake circuits linked to Figure 6,</li><li><b>Fig.10</b> The vehicle brake system according to Figure 9 with a different type of link,</li><li><b>Fig.11</b> The vehicle brake system according to Figure 10 with a different type of link,</li><li><b>Fig.12</b> a further development of the brake circuits according to Figure 9 to 11th</li></ul>

1 shows in full lines schematically illustrate the basic design of a brake circuit with an actuated by the supply of brake pressure application device (1) and with a mechanical brake pressure control device (3, 5) and an electrical brake pressure control device (6, 9, 12, 13). The pressure medium is air. With appropriate adjustment to the following remarks, however, onset of other pressure medium brake circuits are with.

The mechanical brake pressure control device (3, 5) consists inter alia of the pressure member (5) of a brake value transmitter (7). The electrical brake pressure control device (6, 9, 12, 13) consists of the electric part (6) of the brake value transmitter (7), an electronic system (9), which includes a braking value sensor (13), and a brake pressure modulator (12).

The aforementioned components of the brake circuit are of known types. The brake signal transmitter (7) are in operation by the driver on the electrical section (6), of the actuating force or actuating travel of the electrical signal dependent, following actuation signal from; at the same time it controls the printing part (5) from a pressure reservoir (8) comprises also dependent on the above-mentioned quantities of brake pressure, which is the in the brake pressure control device (3, 5) set braking pressure.

The electronic system (9) receives the operating signal and prepares this on to a corresponding turn-on the brake pressure modulator (12). The brake pressure modulator (12) is on the one hand connected to the pressure reservoir (8) and on the other hand with the application device (1) and closes during the reception of the switch-on the brake application device (1) to the pressure reservoir (8), so that build up in these, a brake pressure can.

The electronic system (9) forms the actuating signal, a reference signal with which it compares the signal of the brake value sensor (13), below the brake value signal. Given equality of the two signals, the electronics (9) turns off the turn. whereupon the braking pressure modulator (12) the brake application device (1) from the pressure reservoir (8) separates. The brake pressure in the brake application device (1) by the electrical brake pressure control device (6,9, 12, 13) thus restricted to a value at which the brake value signal, and thus the corresponding braking value have a achieved by the actuation signal and thus predetermined by the driver value , In return operation of the brake value generator, ie reducing the actuating force or actuating travel, extend the functions described in the reverse direction, the corresponding brake pressure reduction in the brake application device (1) takes place in that in this case, the braking pressure modulator (12) the brake application device (1) connects with the atmosphere.

As braking value of the brake pressure takes even into account, in which case the electrical brake pressure control device (6, 9, 12, 13) forms a control circuit for the brake pressure. In this case, the brake value sensor (13) is often integrated into the brake pressure modulator (12).

When braking power but can come into consideration other parameters of the brake circuit. Is, for example, by means of the brake pressure of the brake application device (1) and the associated wheel brake generated braking force of the braking value, form the electrical brake pressure control device (6, 9, 12, 13), which brake application device (1) and the wheel brake a control circuit for this braking force with the brake pressure as an actuator. Other parameters that are used as braking value into consideration, for example, the temperature of the wheel brake, the adhesion utilization of braked by means of the brake circuit wheels and the vehicle deceleration.

The mechanical brake pressure control device (3, 5) still contains a retaining device (3). This concerned that the application device (1) of the brake pressure priority by the electrical brake pressure control device (5, 9, 12, 13) is supplied. The actuation of the brake circuit is so controlled electrically in normal operation and in emergency operation, that in case of faulty electrical brake pressure control device (6, 9, 12, 13) is pressure controlled, take place.

The retainer (3) is formed for this purpose in a first embodiment, so that the in the mechanical brake pressure control device (3, 5) set braking pressure which is that of the pressure member (5) being controlled, as long retain as the electrical brake pressure control device ( 6, 9, 12, 13) modulates a brake pressure. The retainer (3) is in one of the pressing member (5) to the application device (1) reaching pressure line (2, 4). Characterized it is detected in normal operation, on the one hand by the pressure member (5) being actuated and on the other hand by the electrical brake pressure control device (6, 9, 12, 13) being steueren brake pressure. The first-mentioned brake pressure is on the upstream of the retaining device (3) located conduit part (4), the latter brake pressure is on the downstream of the Rückhalteeinichtung (3) located conduit part (2). The retainer (3) must therefore be designed in a suitable way in detail that, as long as the electrical brake pressure control device (6, 9, 12, 13) modulates a higher brake pressure than atmospheric pressure, the pressure line (2, 4) blocks. In this embodiment, the disturbance of the electrical brake pressure control device (6, 9, 12, 13) is defined as the total loss is used, whereby the unavoidable residual braking pressure is not gerechtnet.

In another embodiment, the retaining means (3) is designed such that it retains the in the mechanical brake pressure control device (3, 5) set braking pressure as long as this braking pressure is not at least a predetermined multiple of the electrical brake pressure control device (6, 9, 12 , is 13) modulated brake pressure. This embodiment has compared to the first-mentioned the advantage that by its intended purpose determination of (pressure) multiples, in which the transfer takes place, as a disturbance already a restriction of the operability of the electrical brake pressure control device (6, 9, 12, 13) and not only their (almost) total failure is defined. In this case, the retaining means (3) must be in a suitable manner on the ratio of the braking pressures in the conduit parts (2) and (4) responsive formed.

About the above-described basic scope of the brake circuit also shows Fig.1 dashed still training the same.

With (14) is representative of other application devices, a second application device indicated. If the application devices (1, 14) are arranged on an axis and distributed on both sides of the vehicle, operate the mechanical brake pressure control device (3, 5) and the electrical brake pressure control device (6, 9, 12, 13) and the further below described anti-lock device axle. The application devices (1, 14) but may also be distributed to various vehicle axles.

With the reference numeral (10) and (11) is still indicated that the braking value generator (7) and the electronics can be (9) are components of the mechanical or electrical brake pressure control devices further brake circuits.

In figures 2, 3 and 4 of the brake circuit just described is by integration of an anti-lock device, hereinafter referred to as ABS, in the electrical brake pressure control device (6, 9, 12, 13) continuously formed.

The ABS is in a known manner from the wheel speed sensors, an ABS electronics and control valves, hereinafter ABS valves. For clarity, the wheel speed sensors are not shown, and the ABS electronics unit is adopted in a known manner integrated in the electronics (9). The ABS electronic controller may also be configured in a known manner separated from the electronics (9).

In Figure 2, the pressure modulator (12) also serves as the ABS valve, while in the Figure 3 and 4 a separate ABS valve (16) is provided.

In Fig.2, the retaining means (3) is provided with a direction indicated by (15) electrical control device which is electrically connected to the electronics (9) and by means of which it from the ABS in the use of an ABS operation irrespective of the brake pressures in the line parts (2) and (4) is switched to its restraint position. This is an undesired and disadvantageous under certain circumstances switching to the mechanical brake pressure control device (3, 5) from a decrease of the electrical brake pressure control device (6, 9, 12, 13) controlled brake pressure is avoided by the ABS.

In Figure 3, the ABS valve (16) is from the perspective of the electrical brake pressure control device (6, 9, 12, 13) downstream of the retaining device (3) arranged so such that it does not affect the in the line section (2) applied pressure , In this case the retaining device (3) detected during the operation of the ABS of the electrical brake pressure control device (6, 9, 12, 13) modulated brake pressure. Therefore, there is mentioned according to Fig.2 the brake circuit possibility of switching to the mechanical brake pressure control device (3, 5) during the ABS operation is not, so that the just mentioned electric control unit (15) is dispensed on the retaining device (3).

In Figure 4, the ABS valve (16) is from the perspective of the electrical brake pressure control device (6, 9, 12, 13) upstream of the retaining device (3) is arranged, that is such that it also the conduit part (2) applied pressure detected. In this case the retaining device (3) detected by said ABS valve (16) in the outgoing intervention by the electrical brake pressure control device (6, 9, 12, 13) modulated brake pressure. Therefore, there is again the possibility of switching the mechanical brake pressure control device (3, 5) during the ABS operation, so that the retaining means (3) requires analogously to the brake circuit according to Figure 2 the electrical control device (15).

The brake circuit shown in Fig.5 has the application devices (1) and (14). The here with (6, 25, 12, 13, 28, 29) to be designated electrical brake pressure control device is partly due to the application devices (1) or (14) divided in such a manner that they at any brake application device (1) or (14) respectively a separate brake pressure modulates. The division is that the braking pressure modulator (12) and the brake value sensor (13) are only the one application device (1) is assigned, while the other application device (14) are associated with a further brake pressure modulator (28) and a further brake value sensor (29), and that here denoted by (25) electronics for each group of braking pressure modulator and brake value sensor (12, 13) or (28, 29) having its own channel which, considered in isolation, as the complete electronics (9) of the previous embodiment acts. The distribution is a "partial" because the electric part (6) of the brake signal transmitter (7) not for each channel of the electronics (25) emits its own actuating signal.

The here with (5, 21) to be designated by mechanical brake pressure control device has as a restraint systems towards a pressure-controlled 3/2-way valve (21). This is in a pressure line (24, 27, 31) is arranged, which extends from the pressure part (5) of the brake value transmitter (7) to the application devices (1) and (14).

The 3/2-way valve (21) is acted upon by the control side of the electrical brake pressure control device (6, 25, 12, 13, 28, 29) modulated brake pressure. For this purpose, its control input via a pressure line (30) and a Doppelabsperreinrichtung (33) to the outputs of the two brake pressure modulators (12) and (28) is connected. The Doppelabsperreinrichtung (33) is adapted to the lower of the signals present at their inputs pressures in the pressure line (30) through controls. On the control side to the 3/2-way valve (21) of the lower of the braking pressure modulators (12) and (28) is thus fed out brake pressure.

A Doppelabsperreinrichtung of this type is known for example from WABCO WESTINGHOUSE publication "double-check valve 434 500" known.

In the Basic configuration described so far this brake circuit works as follows.

In the non-actuated brake circuit, the 3/2-way valve (21) is in its designated by (20) through position, in which it holds open the pressure line (24, 27, 31). For safe adjustment of the passage position (20), the 3/2-way valve (21) be provided in a known manner with a restoring device, such as a return spring.

Will now be an intact electrical brake pressure control device (6, 25, 12, 13, 28, 29) of the brake value transmitter (7) is actuated, each brake pressure modulator (12) and (28) controls to the associated brake application device (1) or (14) a brake pressure. The lower is the Doppelabsperreinrichtung (33) through controlled in the pressure line (30) acts upon the control input of the 3/2-way valve (21) and switches it into its designated by (22) locking position in order, in which it the upstream conduit portion ( 24) closes and the downstream conduit portion (27, 31) connects with the atmosphere. The of the pressing member (5) of the brake signal transmitter (7) in the line (24) out brake pressure which is in the mechanical brake pressure control device (5, 21) set, so it can not penetrate to the application devices (1) and (14). In this normal operation, therefore, the brake circuit of the electrical brake pressure control device (29 6, 25, 12, 13, 28,) controlled.

If the electrical brake pressure control device (6, 25, 12, 13, 28, 29) is disturbed, ie (7) builds upon actuation of the brake signal transmitter at the output of a brake pressure modulator (12) or (28) or at the outputs of both brake pressure modulators (12) the 3/2-way valve (21) and (28) and thus in the associated brake application devices or to the no braking pressure, so at the control input receives no control pressure and remains in the passage position (20). In the now given emergency operation of the of the pressure member (5) being controlled brake pressure to the brake application devices (1) and (14) is controlled, in other words, by the electrical brake pressure control device (6, 25, 12, 13, 28, 29) is on the mechanical brake pressure control device (5, 21) switched.

It should be noted that if the 3/2-way valve (21) is provided with a resetting device, which has just been mentioned switching triggering disorder not only at the complete failure of the braking pressure at the output of a brake pressure modulator (12) or (28) or the outputs of both braking pressure modulators (12) and (28), but is given as a result of the action of the return means already at a residual brake pressure.

The Doppelabsperreinrichtung (33) has the consequence that only a 3/2-way valve (21) is required as a retaining device. An alternative would be any brake application device (1) and (14) to assign a separate 3/2-way valve and to link such that in case of failure of the braking pressure, or in his waste to the rest of the brake pressure at the outlet of a brake pressure modulator, switching it undivided to mechanical brake pressure control device cause.

About the previously described basic scope, the embodiment includes dashed nor explained below trainings.

With (23) an additional electrical control device of the 3/2-way valve (21) is indicated, by means of which this in the case of integration of an ABS in the electrical brake pressure control device (6, 25, 12, 13, 28, 29) during an ABS is operation of the electronic system (25) in the locking position (22) switchable. The electric control device (23) thus assumes the present braking circuit the function of the in the brake circuits of Figures 2 and 4 schematically indicated electric control device (15). In the illustration of Figure 5 are used in the case of the presence of ABS, analogous to Figure 2, the braking pressure modulators (12) and (28) as ABS valves. This braking circuit can also be equipped with separate ABS valves, for their arrangement and the need for additional electrical control device (23) at the 3/2-way valve (21) are the statements made in connection with the 3 and 4 in accordance , although, due to the partial division of the electrical brake pressure control device (6, 25, 12, 13, 28, 29) for each brake application device (1) and (14) is a separate ABS valve required.

By a utilization of the vehicle or the brake circuit associated with the axle (s) monitored load sensor (26) is indicated, that the electrical brake pressure control device (6, 25, 12, 13, 28, 29) may include a load-dependent brake pressure regulator. In this case, the load signal of the load sensor (26) of the electronics (25) is taken into account in the formation of the reference signal, what and when not fully loaded trailer or not fully loaded axis to a reduction of the reference signal and thus of the of the braking pressure modulators (12) (28) controlled brake pressures leads. As a result of the described priority of the electrical brake pressure control device (6, 25, 12, 13, 28, 29) of the brake pressure regulator is operable in normal operation.

A load-dependent brake pressure regulator is in the mechanical brake pressure control device (5, 21) is not provided, so that the brake circuit experiences a load-dependent brake force control only in normal operation for this training. One possible se load-dependent brake pressure control also in the mechanical brake pressure control device would be a more expensive mean the same, of which may be waived because this controller is designed to ensure only emergency.

For the separation of the braking pressure-carrying parts of the electrical brake pressure control device (6, 25, 12, 13, 28, 29) and the mechanical brake pressure control device (5, 21) must be in so far described extent, the brake application device (1) and (14) have a double circuit, ie, for example, for each brake pressure control device having a separate chamber. The brake application device (1) and (14) may be normal single circuit if them is fed the brake pressure on upstream 2-way valves, such as are indicated by (32) and (34). As illustrated, the 2-way valves (32) and (34) on the one hand to the output of the respective brake application device (1) or (14) associated brake pressure modulator (12) or (28) and on the other hand with the conduit member (31) are connected , the latter in emergency operation the zoom leads then from the mechanical brake pressure control device (5, 21) modulated brake pressure.

In the brake circuit according to Figure 6 3/2-way valve (21) of the previous embodiment is here replaced by a 3/2-way valve (41), which is controlled by the ratio of two pressures. The mechanical brake pressure control device thus bears here the reference numeral (5, 41).

Such a 3/2-way valve is, for example, from the Handbook of WABCO Westinghouse control technology "Find out more about pneumatics", 1980 edition, page 160, known as a non-member or inhibition.

The 3/2-way valve (41) has two control inputs. At one control input, it is via the pressure line (30) and the Doppelabsperreinrichtung (33) with the lesser of the of the braking pressure modulators (12) and (28) controlled brake pressures as from the electrical brake pressure control device (6, 25, 12, 13, 28, 29) ausgesteuertem brake pressure applied. At the other control input, it is the pressure of the part (5) of the brake value transmitter (7) being controlled as that in the mechanical brake pressure control device (5, 41) is applied to set braking pressure. The latter, as shown, on one of the line (24) branching off outer stub, but also take place in a manner not shown, via an internal connection.

In one embodiment of the 3/2-way valve (41) this and the control means so constructed that it is switched from the communicating position again designated by (20) in the back with (22) called the locking position, as long as that of the pressure member (5 ) outsorted brake pressure does not amount to a predetermined multiple of the in the pressure line (30) pending brake pressure or more, which is intact electrical brake pressure control device (6, 25, 12, 13, 28, 29) is the case.

In another embodiment, the 3/2-way valve (41) this and the control means are so constructed that it is held in the locking position (22) as long as that of the prints express (5) being controlled brake pressure is not the predetermined multiple of the pressure line (30) is pending brake pressure. In this case, the 3/2-way valve is also in the non-actuated brake circuit in the locking position (22).

This brake circuit has on the previous to already in the embodiment mentioned by Fig.1 advantage that the disturbance already restricting the operability of the electrical brake pressure control device (6, 25, 12, 13, 28, 29) and not only their (almost) completely fail is defined.

The definition of the offense "failure" by predetermining the multiples can be adapted to the characteristics of the particular application. In the event that this brake circuit is continuously formed around a load-dependent brake force control of the type explained above, it is advantageous for the above-mentioned predetermined multiple identical or make substantially equal to the largest occurring control ratio of the brake pressure regulator above. Characterized a switchover to the mechanical brake pressure control device (5, 41) within the control range of the load-dependent brake pressure regulator is avoided.

In the event that an ABS is integrated in this embodiment in the electrical brake pressure control device (29 6, 25, 12, 13, 28,), the statements made above with respect to the design and arrangement of the ABS valves apply accordingly. For this case is to take over the functions of OE additional electrical control means (15) or (23) in broken lines an electrically controlled 3/2-way valve (40) is shown which in the pressure line (24, 27, 31) in series with the 3/2-way valve (41) is arranged. The 3/2-way valve (40) is downstream of the 3/2-way valve (41) shown, but may also be upstream of the same can be arranged with equal effect.

The 3/2-way valve (40) is also controlled by the electronics (25). It takes outside an ABS operation his again with (20) designated through position and is switched on if the ABS operation of the electronics (25) in its back with (22) called locking position, in which it is independent of the position of the 3 / 2-way valve (41) a Aussteuern of the of the pressure member (5) is prevented in the line section (24) modulated brake pressure to the brake application devices (1) and (14) and thus switching to the mechanical brake pressure control device (5, 41).

As further development of the embodiment showing in phantom a pressure in the downstream of the 3/2-way valve (41) located conduit part (27, 31) monitoring Schwellwertdruckschalter (42). This is electrically connected to the electronics (25) and turned on and thus the electrical brake pressure control device (6, 25, 12, 13, 28, 29) when the pressure in the line part (27, 31) once has reached the threshold value. This ensures that at the time to be disturbed detected electrical brake pressure control device (6, 25, 12, 13, 28, 29) can not be switched back to previous without manual intervention. If the existing approximately 3/2-way valve (40) downstream of the 3/2-way valve (41), the Schwellwertdruckschalter (42) may be disposed between the two.

In the brake circuit according to Figure 7 the retaining device consists of an electrical pressure ratio switch (51) and an electrically controlled 3/2-way valve (53), so that the mechanical brake pressure control means here the reference numeral (5, 51, 53) bears.

The pressure ratio switch (51) is designed such that it switches an integrated switching element (52), as long as two pressures applied to it does not reach a predetermined ratio to one another. Such pressure ratio switch is known, for example from the WABCO Westinghouse publication "reversing switch 446 020". The pressure ratio switch (51) is in the exemplary embodiment on the one hand via the pressure line (30) and the Doppelabsperreinrichtung (33) with the lesser of the of the braking pressure modulators (12) or (28) controlled brake pressures and on the other hand with that of the pressure member (5) of the brake value transmitter (7) in the pipe member (24) being controlled than in the mechanical brake pressure control device (5, 51, 53) set braking pressure applied. It is so designed that it switches the switching element (52) as long as that of the pressure member (5) out brake pressure does not amount to the the previous embodiment mentioned predetermined multiple of the brake pressure in the pressure line (30) or more, with an intact electrical brake pressure control device ( 6, 25, 12, 13, 28, 29) is the case.

The 3/2-way valve (53) corresponds to the 3/2-way valve (40) of the previous embodiment and is like that in the pressure line (24, 27, 31) arranged. Its control means is electrically connected to the switching element (52). Upon actuation of the brake circuit with an intact electrical brake pressure control device (6, 25, 12, 13, 28, 29) on the pressure ratio switch (51) via its switching element (52), the 3/2-way valve (53) from its back with (20) designated through position into his back with (22) designated blocking position.

If a fault in the electrical brake pressure control device (6, 25, 12, 13, 28, 29) is built up when the brake circuit in the pressure line (30) only a pressure, wherein the of the pressing member (5) out brake pressure mentioned the reaches or exceeds multiples, so that the pressure ratio switch (51), the 3/2-way valve (53) does not switch into the blocking position, with the result that the mechanical brake pressure control device (5, 51, 53) becomes effective and the emergency operation begins.

In this embodiment, therefore, act the pressure ratio switch (51) and the 3/2-way valve (53) as the 3/2-way valve (41) of the previous embodiment in the former embodiment. Also the execution of the other embodiment of the 3/2-way valve (41) is a corresponding design of the 3/2-way valve (53) and of the pressure ratio switch (51), in particular the switching element (52) possible.

Again, in the manner described above in the electrical brake pressure control device (6, 25, 12, 13, 28, 29) an ABS to be integrated. In this case, as shown, the control device of the 3/2-way valve (53) are connected in parallel to the switching element (52) with the electronics (25), so that these during an ABS operation of the 3/2-way valve (53 ) switches into its blocking position, whereby the function of the oE additional control means (15) and (23) is ensured substantially without additional effort.

Under the switching element (52) can be understood, depending on the configuration of the controller of the 3/2-way valve (53) to open or close.

In a further development of the present embodiment, the pressure ratio switch (51) can be equipped with one indicated by dashed lines further switching element (50), which is switched when the of the pressing member (5) out brake pressure reaches or exceeds the aforementioned predetermined multiple. The switching element (50) is electrically connected to the electronics (25), and sets the electrical brake pressure control device (6, 25, 12, 13, 28, 29) to a manual intervention inoperative. Therefore, the switching element (50) is an alternative to that described in the previous embodiment Schwellwertdruckschalter (42).

8 shows that, to improve the time behavior of the brake circuits in accordance with the Figure 2 to 7 in emergency operation the mechanical brake pressure control devices (5, 21 or 5, 41 or 5, 41, 40 or 5, 51, 53) to a relay valve (54) can be added. This is in the downstream of the respective restraint device, ie, the 3/2-way valves (21 or 41 or 40 or 53) located conduit part (27, 31) to arrange, with this in a control line (27) and a working line (31 ) of the relay valve (54) is divided. supply each relay valve (54) as usual directly from the pressure reservoir (8). The display indicates more that can be arranged in this training of Schwellwertdruckschalter (42) on the control line (27) and / or to the working line (31).

In the embodiment of Figure 9 two brake circuits according to the embodiment of Figure 6 are linked to a vehicle brake system.

The vehicle brake system includes, for each brake circuit an electrical brake pressure control device of the type described in the earlier embodiments, where the electric part (6) of the brake value transmitter (7) is common, and of which for the sake of clarity, only this electric part (6) and the braking pressure modulators (12, 28) are shown. In addition to the electrical part (6), other components of these electrical brake pressure control devices can be combined functionally and structurally, which is especially true for the electronics and the load-dependent brake pressure regulator.

The mechanical brake pressure control devices of each brake circuit are connected to a mechanical brake pressure control device for the entire vehicle brake system, is only switched on if the same problems occur in the electrical brake pressure control devices of both brake circuits corresponding to the given according to Figure 6 in the brake circuit definition.

This is achieved in that, while each brake circuit a private 3/2-way valve by way of the 3/2-way valve (41) associated with the Figure 6, but that the downstream thereof located lead portions (60, 66, 67 or 64 , 66, 63) of the of the pressing member (5) of the brake signal transmitter (7) to the application devices (1) and (14) of the brake circuits reaching pressure lines (24, 60, 66, 67) or (62, 64, 66, 63 ) are connected via an AND gate (61) to each other.

When AND gate (61), the device comes to the already mentioned WABCO Westinghouse publication "double-check valve 434 500˝ into consideration. If this applied only to an input pressure, it assumes its blocking position. Only when both inputs is acted upon by pressure, it can be carried to its output pressure, namely the lower.

Occurs when actuation of the vehicle brake system in the electrical brake pressure control device of a brake circuit a fault occurs, so the AND element (61) is acted upon at an input, assumes its locking position and thus prevents switching over to the here with (5, 41, 41, 61) to be designated by mechanical brake pressure control device. Only when the electrical brake pressure control devices of both brake circuits are disrupted, the AND gate (61) is applied at both inputs with pressure, thereby permeable, and allows switching to the mechanical brake pressure control device (5, 41, 41, 61).

Is here in the electrical brake pressure control means, an ABS integrated, then the mentioned in the earlier embodiments, locking of the mechanical brake pressure control device (5, 41, 41, 61) in the ABS operation by means of only one electrically controlled 3/2-way valve by way of the 3 / 2-way valve (40) of Figure 6 are obtained when this, as shown, downstream of the AND gate (61) in a two brake circuits common line part, in this case (66) is disposed.

The embodiment according to Figure 10 shows a detail of the previous embodiment in which the AND gate (61) by an OR gate (70) is replaced. When OR gate (70) is for example a 2-way valve into consideration. The OR gate (70) is already permeable, if it is applied only at one input with pressure. In contrast to the previous embodiment of a brake circuit is therefore in this embodiment, even with a fault in the electrical brake pressure control device is switched to the here with (5, 41, 41, 70) to be designated by mechanical brake pressure control device.

In the vehicle braking system according to 9 and 10, the disturbance defining multiples of being controlled by the electrical brake pressure control device brake pressure (pressure lines (30)) can be predetermined differently for each brake circuit. That is, that the 3/2-way valves (41) of the individual brake circuits, at least there may be differences in the control devices. This possibility is particularly exercised when the electrical brake pressure control devices comprise a brake pressure controller and this has a different control ratio for each brake circuit.

For cases in which this possibility does not matter 11 shows a possibility to simplify the vehicle brake system according to Fig.10. In this, the OR gate (70) by an AND gate (61) are replaced and for the mechanical brake pressure control devices (61 5, 41) only a 3/2-way valve (41) is provided, which joint in a two mechanical brake pressure control devices line part (24, 66) the pressure of the part (5) to the application devices (1) and (14) reaching pressure lines (24, 66, 67) or (24, 66, 63) is arranged. Be of the electrical brake pressure control device associated control input is connected to the output of the AND gate (61) whose inputs are applied to each of the outsorted by the electrical brake pressure control device of a brake circuit the brake pressure. As such, brake pressure is used from the above-mentioned reasons by means of the Doppelabsperreinrichtung (33) of each circle of the respectively smaller of the braking pressure modulators (12) and (28) being controlled brake pressure.

The described arrangement of the AND gate (61), the 3/2-way valve (41) is associated with an actuation of the vehicle brake system at its the electrical brake pressure control device control input is always applied with the lowest existing in the electrical brake pressure control device brake pressure so that, as in the vehicle brake system according to Figure 10, each fault in an electrical brake pressure control device to the mechanical brake pressure control device (5, 41, 61) is switched.

In the vehicle braking system according to Figure 9, 10 and 11, the 3/2-way valves (41) can be prepared by a 3/2-way valves by way of the 3/2-way valve (21) of Figure 5 are replaced with the result that , is performed as in that brake circuit, the switchover to the mechanical brake pressure control device only at (virtually) complete power failure of the electrical brake pressure control means (Fig.9) or the electrical brake pressure control device of a brake circuit (Fig.10, 11).

12 shows that the mechanical brake pressure control devices (5, 41, 41, 61) or (5, 41, 41, 70) and (5, 41, 61) of the vehicle brake systems according to Figure 9 to 11 to a relay valve (54) by type of can be supplemented in Figure 8 shown. It is sufficient a relay valve when this via the common line part (66) is driven and when the line parts (63) and (67) to the application devices (1) and (14) of the individual brake circuits at its working connection or, if there are several operating connections has, connected to these.

Representing all embodiments is in the Figure 9 to 11 by using (65) or (71) Marked dashed borders still indicated that components of the embodiments may be combined to form units. For example, with (71) an assembly of relay valve (54) and an electrically controlled 3/2-way valve (40) (for ABS operation) and with (65) a structural unit consisting of a 3/2-way valve (41), the AND -element (61) or the oR gate (70), the Schwellwertdruckschalter (42) and the 3/2-way valve (40) or, if appropriate, and the structural unit (71) indicated.

In all other respects, insofar as nothing contradictory from the foregoing, the information given for the basic version and the training of an embodiment of the other embodiments directly or in a corresponding manner with.

The skilled artisan will appreciate that the scope of the invention is not exhausted in the embodiments, but rather covers all embodiments, the characteristics of which is subordinated to the claims.