Electropneumatic parking brake control device, and braking system of a vehicle

Abstract

An electropneumatic parking brake control device controls a parking brake including at least one spring brake actuator. The control device includes a relay valve with a control chamber and a vent. The control chamber can be connected to the vent via at least one second throttle element and/or at least one third throttle element depending on the position of the relay piston.

Claims

1. An electropneumatic parking brake control device for controlling a parking brake having at least one spring brake actuator, comprising: a) a connection for the at least one spring brake actuator, b) a solenoid valve device which is controllable by an electronic control device, c) a relay valve whose pneumatic control inlet is connected at one end to the solenoid valve device and at the other end to a working outlet and to the connection for the at least one spring brake actuator, d) a supply connection for at least one pressurized air supply which is connected at one end to the solenoid valve device and at the other end to a supply inlet of the relay valve, e) a feedback line through which the working outlet and the pneumatic control inlet of the relay valve are connected to one another, wherein f) the relay valve has a control chamber which is connected to the pneumatic control inlet, at least one relay piston which is controlled by the pressure in the control chamber and activates a double seat valve, and a working chamber which is connected to the working outlet, wherein the relay piston is guided within a relay valve housing and bounds the control chamber and the working chamber, and the double seat valve comprises at least one inlet seat and at least one outlet seat, wherein when the outlet seat is opened, the working chamber is connected to a vent, and when the inlet valve is opened said working chamber is connected to the supply inlet, and wherein g) at least one first throttle element is arranged in the feedback line in such a way that the working outlet and the pneumatic control inlet of the relay valve always have a throttled flow connection to one another, and wherein h) the control chamber of the relay valve is connected to the vent via at least one second throttle element exclusively when the relay piston is in a venting position or in an intermediate position, but the connection of the control chamber to the vent is interrupted by the at least one second throttle element if the relay piston is in an aeration position, wherein h1) the venting position of the relay piston within the relay valve housing is characterized in that the outlet seat is completely opened and the inlet seat of the double seat valve is completely closed, and as a result a pressure arises at the connection for the at least one spring brake actuator, which pressure corresponds to an application pressure of the at least one spring brake actuator, at which pressure said actuator is completely applied, and wherein h2) the aeration position of the relay piston within the relay valve housing is characterized in that the inlet seat is completely opened and the outlet seat is completely closed, and as a result a pressure arises at the connection for the at least one spring brake actuator, which pressure corresponds to a release pressure of the at least one spring brake actuator, at which pressure said actuator is completely released, and wherein h3) the intermediate position of the relay piston within the relay valve housing is characterized in that a pressure arises at the connection for the at least one spring brake actuator, which pressure is higher than the application pressure but lower than the release pressure, and further wherein i) the control chamber of the relay valve is connected to the vent via at least one third throttle element exclusively when the relay piston is in the venting position, but the connection between the control chamber and the vent is interrupted by the at least one third throttle element if the relay piston is in the aeration position or in the intermediate position, and wherein j) a flow cross-section which is made available by the at least one third throttle element is larger than a flow cross-section which is made available by the at least one first throttle element, and k) a flow cross-section which is made available by the at least one second throttle element is smaller than the flow cross-section which is made available by the at least one first throttle element.

2. The electropneumatic parking brake control device as claimed in claim 1, wherein the at least one second throttle element and/or the at least one third throttle element comprise at least one drilled through-hole in a wall of the relay piston, and an element which is secured to the relay valve housing is provided, which element interacts with the at least one second throttle element and/or with the at least one third throttle element in such a way that depending on the position of the relay valve within the relay valve housing the control chamber is connected to the vent via the at least one second throttle element and/or via the at least one third throttle element, or such a connection is blocked.

3. The electropneumatic parking brake control device as claimed in claim 2, wherein a throttle cross-section of the at least one second throttle element and/or a throttle cross-section of the at least one third throttle element is formed by the at least one drilled through-hole.

4. The electropneumatic parking brake control device as claimed in claim 2, wherein a region on a side of an end, facing the control chamber, of the element which is secured to the relay valve housing is connected to the control chamber, wherein a) if the at least one drilled through-hole projects at least partially beyond the end in the direction of the control chamber, the control chamber is connected to the vent via the at least one second throttle element and/or via the at least one third throttle element, and b) if the at least one drilled through-hole does not project beyond the end in the direction of the control chamber, such a connection is blocked.

5. The electropneumatic parking brake control device as claimed in claim 2, wherein the element which is secured to the relay valve housing comprises at least one relay piston seal which is secured to the relay valve housing and against which a lateral wall of the relay piston, in which the at least one drilled through-hole is formed, forms a seal.

6. The electropneumatic parking brake control device as claimed in claim 1, wherein the relay piston is loaded into the venting position by a spring means.

7. The electropneumatic parking brake control device as claimed in claim 1, wherein the electronic control device is connected to an electrical parking brake signal connection for an electric parking brake signal generator, via which parking brake signal connection parking brake signals are input into the electronic control device.

8. The electropneumatic parking brake control device as claimed in claim 7, wherein the solenoid valve device comprises two 2/2-way solenoid valves each with a closed position and an open position, wherein a first 2/2-way solenoid valve is connected as an inlet valve between the pneumatic control inlet of the relay valve and the supply connection, and a second 2/2-way solenoid valve is connected between the pneumatic control inlet of the relay valve and a pressure sink.

9. The electropneumatic parking brake control device as claimed in claim 8, wherein the first 2/2-way solenoid valve and the second 2/2-way solenoid valve each have a currentless closed position and an energized open position.

10. The electropneumatic parking brake control device as claimed in claim 8, wherein when a parking brake signal which represents a “drive” state is input into the electronic control device or generated in the electronic control device, the second 2/2-way solenoid valve is controlled by the electronic control device into the closed position, and the first 2/2-way solenoid valve is firstly controlled into the open position and then into the closed position.

11. The electropneumatic parking brake control device as claimed in claim 8, wherein when a parking brake signal which represents an “activate parking brake with a specific brake pressure value” state is input into the electronic control device or generated in the electronic control device, the electronic control device controls the first 2/2-way solenoid valve and/or the second 2/2-way solenoid valve into the closed position or into the open position depending on the respective brake pressure value.

12. The electropneumatic parking brake control device as claimed in claim 11, wherein the electronic device controls the first 2/2-way solenoid valve and/or the second 2/2-way solenoid valve alternately or in a pulsed fashion into the closed position and into the open position.

13. The electropneumatic parking brake control device as claimed in claim 8, wherein when a parking brake signal which represents a “park” or “parking brakes” state is input into the electronic control device or generated in the electronic control device, the electronic control device controls the first 2/2-way solenoid valve into the closed position, and firstly controls the second 2/2-way solenoid valve into the open position and then controls the second 2/2-way solenoid valve into the closed position.

14. The electropneumatic parking brake control device as claimed in claim 1, wherein at least one pressure sensor with the connection for the at least one spring brake actuator, and/or at least one pressure sensor with the pneumatic control inlet of the relay valve, inputs a signal which represents an actual pressure into the electronic control device.

15. The electropneumatic parking brake control device as claimed in claim 14, wherein the electronic control device is configured such that, on the basis of the signal which represents the actual pressure and a signal which represents a value for a setpoint pressure, a setpoint/actual comparison is carried out within the scope of a pressure regulating process and/or a pressure plausibility check, and/or determines the supply pressure which arises at the supply connection.

16. The electropneumatic parking brake control device as claimed in claim 1, wherein the supply connection is secured by a nonreturn valve.

17. A brake system of a vehicle comprising an electropneumatic parking brake control device as claimed in claim 1.

18. The brake system as claimed in claim 17, wherein the brake system is an electropneumatic parking brake for the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic circuit diagram of a preferred embodiment of an electropneumatic parking brake control device according to the invention;

(2) FIG. 2 shows a schematic cross-sectional illustration of a relay valve of the electropneumatic parking brake control device from FIG. 1 in the “park” or “parking brakes” position;

(3) FIG. 3 shows a schematic cross-sectional illustration of the relay valve of the electropneumatic parking brake control device from FIG. 1 in an “activate parking brake with a specific brake pressure value” position within the scope of an emergency braking function or auxiliary braking function; and

(4) FIG. 4 shows a schematic cross-sectional illustration of the relay valve of the electropneumatic parking brake control device from FIG. 1 in the “drive” position.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1 shows a schematic circuit diagram of a preferred embodiment of an electropneumatic parking brake control device 1. The electropneumatic parking brake control device 1 preferably represents a control device of an electropneumatic parking brake device of a tractor vehicle-trailer combination and is arranged on the tractor vehicle.

(6) The electropneumatic parking brake control device 1 has a supply connection 2 which is protected by means of a nonreturn valve 4. A supply line 6 extends from the supply connection 2, on the one hand to a first solenoid valve device 8 with a first 2/2-way solenoid valve 10 as the inlet valve and a second 2/2-way solenoid valve 12 as the outlet valve. The first 2/2-way solenoid valve 10 is, like the second 2/2-way solenoid valve 12, located in the shown closed position when not energized, while both valves 10, 12 switch over into the open position when energized and are controlled by an electronic control device 14.

(7) Furthermore, a supply inlet 16 of a relay valve is also connected to the supply connection 2 via the supply line 6. A pneumatic control inlet 20 of the relay valve 18 is connected via a control line 22 to the combination of the inlet valve 10 (first 2/2-way solenoid valve) and outlet valve 12 (second 2/2-way solenoid valve).

(8) In particular, in the currentless closed position of the second 2/2-way solenoid valve 12 the connection between the control line 22 and the control inlet 20 of the relay valve 18 and a pressure sink 24 is interrupted, while this connection is connected in the energized open position. In an analogous fashion, in the currentless closed position of the first 2/2-way solenoid valve 10 the connection between the control line 22 or the control inlet 20 of the relay valve 18 and the supply connection 2 is interrupted, while this connection is connected in the energized open position.

(9) Furthermore, a first throttle element 30, by which the flow cross-section of the feedback line 26 is constricted and the air mass flow between the working outlet and the pneumatic control inlet of the relay valve is limited or throttled by means of the flow cross-sectional constriction is connected into a feedback line 26 between a working outlet 28 of the relay valve 18 and the control inlet 20 of the relay valve 18.

(10) The two 2/2-way solenoid valves 10, 12 are preferably prestressed under spring loading into their currentless position and are switched over by energization by means of the control device 14.

(11) The working outlet 28 of the relay valve 18 is connected to a connection 40 for at least one spring brake actuator by means of a working line 38. Two spring brake actuators (not shown here) on the rear axle are preferably connected to this connection 40.

(12) Depending on the switched position of the first 2/2-way-solenoid valve 10 and of the second 2/2-way solenoid valve 12 (inlet/outlet solenoid valve combination) the control line 22 or the control inlet 20 of the relay valve 18 is aerated or vented, so that aeration or ventilation by increasing the quantity of air by means of the relay valve 18 results in corresponding aeration or venting of the working outlet 28 and therefore of the connection 40 for the at least one spring brake actuator.

(13) The relay valve 18 is firstly constructed in a widely known manner and comprises a control chamber 42 which is connected to the control line via the control inlet 20, a relay piston 46 which bounds the control chamber 42, can be moved in a housing and has a valve body 48 which is formed on the relay piston 46 or on its relay valve piston rod and, which forms an outlet valve of a double seat valve with an outlet seat 50 on a collar 52 which is also movably accommodated in the housing 44. Furthermore, the relay valve 18 comprises an inlet seat 54 which is formed on the housing 44 and against which the collar 52 is pretensioned and forms together with said inlet seat 54 an inlet valve of the double seat valve. The collar 52 also has a central drilled through-hole which, when the relay piston 46 is lifted off from the collar 52, connects a venting means 56 to a working chamber 58 which is connected to the working outlet 28 in order to vent the latter. On the other hand, when the collar 52 is lifted off from the inlet seat 54, a supply chamber 60 which is connected to the supply inlet 16 is connected to the working chamber 58 in order to ventilate the working outlet 28. The position of the relay piston 46 which, with its valve body 48, can press the collar 52 downward in order to lift it off from the inlet seat 54 is accordingly determined by the pressure at the control inlet 20 or in the control chamber 42. Finally, the collar 52 is forced against the inlet seat 54 by means of a collar spring 62. Moreover, a relay piston spring 64 forces the relay piston 46 away from the outlet seat 50 in the direction of the control chamber 42 by means of the force F.sub.F.

(14) The switched states of the two 2/2-way solenoid valves 10, 12 are determined by the control device 14, in particular in accordance with the parking brake signals which are present at the parking brake signal connection 32. For this purpose, the parking brake signal generator 36 is designed in such a way that it modulates parking brake signals in accordance with activation, which signals represent the operating states which are described further below.

(15) The control device can also be connected to a vehicle data bus (not illustrated in the figures) via the parking brake signal connection or via a further signal connection, via which vehicle data bus the digital data can be received from other control devices and transmitted thereto. Instead of parking brake signals being input by the or in addition to the parking brake signal generator 36 which can be operated manually by the driver, parking brake signals can also be input into the control device 14 by a further control device, for example via a vehicle data bus, for example by a driver assistance system such as, for example, by a starter aid system on slopes. By means of signals which are received via such a vehicle data bus, parking brake signals can then be generated by the control device 14 itself. For example, the parking brake can be automatically applied if the vehicle has come to a standstill, or can be released automatically if it is detected that the vehicle is to drive away.

(16) Against this background, the method of functioning of the electromagnetic parking brake control device 1 is as follows:

(17) In the basic state (shown in FIG. 1) of the electropneumatic parking brake control device 1 both the first 2/2-way solenoid valve 10 and the second 2/2-way solenoid valve 12 are unenergized so that the control inlet 20 is always connected to the working outlet 28 of the relay valve 18 via the first throttle element 30. The feedback is therefore stable, and pressurized air cannot pass from the supply connection 2 to the control inlet 20 of the relay valve 18 or escape from the latter to the pressure sink 24. Therefore, the pressure which is currently prevailing at the connection 40 is also kept constant for the at least one spring brake actuator, and as a result also its applied position or release position.

(18) If the pressure at the connection 40 for the at least one spring brake actuator is then to be increased in response to a corresponding parking brake signal, for example in the “activate parking brake with a specific brake pressure value” operating state within the scope of an emergency braking function or auxiliary braking function, the first 2/2-way solenoid valve 10 is switched into the open position by energizing it, and as a result the pressure in the control chamber 42 of the relay valve 18 is increased. This takes place, in particular, by pulsing the first 2/2-way solenoid valve 10.

(19) The relay piston 46 then moves downward, and opens the inlet seat 54 of the double seat valve and allows supply pressure to flow into the working chamber 58. Then, the relay piston 46 moves back as far as its neutral position in which the inlet seat 54 and the outlet seat 50 of the double seat valve are closed.

(20) However, if for example a relatively low pressure is to be applied at the connection 40 for the at least one spring brake actuator in the “activate parking brake with a specific brake pressure valve” operating state within the scope of an emergency braking function or auxiliary braking function in response to a corresponding parking brake signal, the control pressure in the control chamber 42 is preferably lowered by pulsing the second 2/2-way solenoid valve 12.

(21) The relay piston 46 then moves in the direction of the control chamber 42 and vents the working chamber 58 via the outlet seat 50 of the double seat valve until an equilibrium of forces is restored, in response to which the relay piston 46 returns to the neutral position.

(22) Since the same pressures do not generally prevail during the open-loop or closed-loop pressure control, as described above, in the control chamber 42 and in the working chamber 58 and a certain quantity of air always flows in the direction of the lower pressure via the first throttle element 30, component of the changing pressure resulting therefrom is preferably compensated in the control chamber 42 by corresponding pulsed control of the first 2/2-way solenoid valve 10 or of the second 2/2-way solenoid valve 12. This applies both to increasing the pressure, reducing the pressure and maintaining the pressure, even if the precise supply pressure or atmospheric pressure are not to prevail at the connection 40 for the at least one spring brake actuator.

(23) In order to bring about the “drive” operating state in response to a corresponding parking brake signal, the first 2/2-way solenoid valve 10 is, for example, energized over a relatively long time. As a result, the control chamber 42 is aerated, even if at first a relatively small part of the air which is conducted from the first 2/2-way solenoid valve 10 to the control chamber flows away into the working chamber through the throttle element (30). The pressure in the working chamber 58 then rises more quickly than in the control chamber 42 until it ultimately exceeds it. Then, air flows from the working chamber 58 into the control chamber 42 via the feedback line 26 and the first throttle element 30 so that the process reinforces itself.

(24) As a result, the relay piston 46 is forced in a stable fashion into its lower end position which points to the working chamber 58, so that said relay piston 46 continuously opens the inlet seat 54 of the double seat valve and connects the working chamber 58 to the supply connection 2.

(25) Since the control chamber 42 is then continuously supplied with supply pressure via the first throttle element 30, the working chamber 58 and the inlet seat 54, the first 2/2-way solenoid valve 10 can also be de-energized in order to switch into its closed position.

(26) In order to bring about the “park” operating state, the second 2/2-way solenoid valve 12 is energized over a certain time period. As a result, the control chamber 42 is aerated until atmospheric pressure prevails there. Then, the relay piston 46 moves in the direction of the control chamber 42 and vents the working chamber 58 via the outlet seat 50 of the double seat valve.

(27) The relay piston spring 64 which loads the relay piston 46 ensures that it moves as far as its upper end position and stays there, as a result of which the outlet seat 50 is continuously completely opened. Since the control chamber 42 is then continuously connected to the atmosphere via the throttle element 30, the working chamber 58 and the opened outlet seat 50, the second 2/2-way solenoid valve 12 can be de-energized and therefore moved into its closed position.

(28) In order to assume the “park” state in a stable fashion in any case in the event of a power failure during the execution of an emergency braking function or auxiliary braking function, a second throttle element 65 is provided. This ensures that in the event of a power failure during the execution of the emergency braking function or auxiliary braking function the control pressure in the control chamber 42 of the relay valve 18 drops, as a result of which the brake pressure in the spring-loaded brakes drops and accordingly the “park” state can be assumed in a stable fashion.

(29) The second throttle element 65 is preferably formed by a radial drilled through-hole in an outer lateral wall 68 of the relay piston 46. In this context, the diameter of the drilled through-hole represents the flow cross-section or throttle cross-section of the second throttle element 65. Instead of a single drilled through-hole 65, a plurality of drilled through-holes can also be provided, for example distributed over the circumference in the lateral wall 68.

(30) In order to avoid undesired release of the applied parking brake in the event of possibly occurring leaks with respect to a region conducting a supply pressure, a third throttle element 66 is then provided. The third throttle element 66 is preferably formed by a plurality of radial drilled-through-holes, arranged distributed over the circumference of the lateral wall 68 of the relay piston 46, in the outer lateral wall 68. In this context, the sum of the diameters of the drilled through-holes forms the flow cross-section or throttle cross-section of the third throttle element 66. Instead of a plurality of small drilled through-holes 66, just a single relatively large drilled through-hole can also be provided in the lateral wall 68.

(31) In this context, the second throttle element 65 and the third throttle element 66 are arranged one behind the other when viewed in the axial direction of movement 70 of the relay piston 46.

(32) Furthermore, an element 67 which is secured to the relay valve housing 44 is provided, which element 67 interacts with the second throttle element 65 and with the third throttle element 66 in such a way that depending on the position of the relay piston 46 within the relay valve housing 44 the control chamber 42 is connected to the venting means 56 via the second throttle element 65 and via the third throttle element 66 or such a connection is blocked.

(33) In particular, the element which is secured to the relay valve housing 44, is formed here, for example, by a relay piston seal 67 against which the lateral wall 68 of the relay piston 46 forms a seal.

(34) As is apparent, in particular, from FIG. 2 to FIG. 4, a region of the relay valve 18 which is located on this side of an end 72 of the relay piston seal 67 facing the control chamber 42 is connected to the control chamber 42.

(35) If the drilled through-hole 65 forming the second throttle element at least partially projects, when viewed in the axial direction of movement 70 of the relay piston 46, beyond the end 72, facing the control chamber 42, of the relay piston seal 76 in the direction of the control chamber 42, the control chamber 42 is connected to the venting means 56 via the second throttle element 65, as shown in FIG. 2, which shows the venting position of the relay piston 46 in the “park” state. In the venting position of the relay piston 46, the outlet seat 50 is completely opened and the inlet seat 54 is completely closed.

(36) There is then a flow connection, indicated by the arrow 74 in FIG. 2, between the control chamber 42 and the venting means 56 via the drilled through-hole 65, a, for example here, oblique transverse drilled hole 76 in the relay piston 46 and via the then opened outlet seat 50 of the double seat valve.

(37) The same also applies to the intermediate position, shown in FIG. 3, of the relay piston 46 which corresponds to the “activate parking brake with a specific brake pressure value” state within the scope of the emergency braking function or auxiliary braking function. Then, either the outlet seat 50 is partially opened and the inlet seat 54 is partially closed in order to increase the parking braking force, or the outlet seat 50 is completely closed and the inlet seat 54 is partially opened in order to reduce the parking braking force. After a certain time, both the outlet seat 50 and the inlet seat 54 are closed owing to the equilibrium of forces which then occur at the relay piston 46.

(38) If, on the other hand, in the aeration position of the relay piston 46 which is shown in FIG. 4 the “drive” state is assumed and the relay piston is moved downward for (completely) opening the inlet seat 54 and for (completely) closing the outlet seat 50, the drilled through-hole 65 which forms the second throttle element is covered or closed off by the end 72 of the relay piston seal 67 so that the flow connection between the control chamber 42 and the venting means 56 via the second throttle element is blocked.

(39) Consequently, a flow connection between the control chamber 42 and the venting means 56 through the second throttle element is only possible in the “park” state and in the “activate parking brake with a specific brake pressure value” state, but not in the “drive” state.

(40) The intermediate position of the relay piston 46 which is shown in FIG. 3 is located, when viewed in the axial direction of movement of the relay piston 46, between the venting position of FIG. 2 (“park”) and the aeration position of FIG. 4 (“drive”).

(41) Furthermore, the flow cross-section which is made available by the second throttle element 65 is smaller than the flow cross-section which is made available by the first throttle element 30. As a result, during an emergency braking operation or auxiliary braking operation in the case of a power failure in which the brake pressure which is set last electrically would continue to act, the brake pressure can drop as far as the application pressure of the spring-loaded brake, as a result of which even in the event of power failure during an emergency braking operation or auxiliary braking operation the “park” state is still assumed in a stable fashion. Therefore, the problems described at the beginning with respect to case b) are eliminated.

(42) The venting position of the relay piston 46 (“park”) which is shown in FIG. 2 is consequently characterized in that the outlet seat 50 is completely opened and the inlet seat 54 of the double seat valve is completely closed, and as a result a pressure which corresponds to an application pressure of the at least one spring brake actuator in which said actuator is completely applied arises at the connection 40 for the at least one spring brake actuator.

(43) The aeration position of the relay piston 46 (“drive”) which is shown in FIG. 4 is, on the other hand, characterized in that the inlet seat 54 is completely opened and the outlet seat 50 is completely closed and as a result a pressure which corresponds to a release pressure of the at least one spring brake actuator in which said actuator is completely released arises at the connection 40 for the at least one spring brake actuator.

(44) An intermediate position of the relay piston 46 which is shown in FIG. 3 is characterized in that a pressure which is higher than the application pressure but lower than the release pressure arises at the connection 40 for the at least one spring brake actuator.

(45) As far as the third throttle element 66 and the drilled through-holes forming the latter are concerned, said holes are arranged in FIG. 1 to FIG. 4 underneath the drilled-through-hole which forms the second throttle element 65, in such a way that a flow connection between the control chamber 42 and the venting means 56 via the third throttle element 66 and transverse drilled hole 76 can, as illustrated by the arrow 78 in FIG. 2, come about only in the venting position of the relay piston 46, which corresponds to the “park” state.

(46) Because in addition the flow cross-section which is made available by the third throttle element 66 is larger than the flow cross-section which is made available by the first throttle element 30, in the “park” state, i.e. in the venting position of the relay valve 46, undesired release of the applied parking brake in the case of possibly occurring leaks of, for example, the inlet valve (first 2/2-way solenoid valve) 10 are avoided.

(47) However, because the third throttle element 66 in the form of the drilled through-holes 66 is not covered by the end 72 of the relay piston seal and therefore closed off merely in the venting position of the relay piston 46 and therefore in the “park” state, but is already in the emergency braking case and in the auxiliary braking case and in the “drive” state, a flow connection between the control chamber 42 and the venting means 56 via the third throttle element 66 is possible only exclusively in the “park” state, however not in the emergency braking case and auxiliary braking case (FIG. 3) and in the “drive” state (FIG. 4).

(48) The relay piston 46 with the second throttle element 65 and the third throttle element 66 is embodied in each case as drilled-through-holes in its lateral wall 68, and therefore forms a slide of a slider valve, wherein depending on the position of the relay piston 46 with respect to the end 72 of the relay piston seal 76 a flow connection comes about between the control chamber 42 and the venting means 56 or not. In this context, the end of the relay piston seal 67 which is secured to the relay valve housing 44 opens or closes the second throttle element 65 and/or the third throttle element 66 depending on the position of the relay valve piston 46.

(49) If actuation of a trailer control valve by means of the electropneumatic parking brake control device 1 is provided, this actuation can be executed in such a way that the pressure which arises at the connection 40 for the at least one spring brake actuator is conducted at the same time to a connection for a trailer control valve.

(50) According to one embodiment, the electronic control device 14 is designed in such a way that on the basis of a signal representing an actual pressure and of a parking brake signal representing a value for a setpoint pressure it carries out a setpoint/actual value comparison within the scope of a pressure regulating process and/or a pressure plausibility check and/or determination of the supply pressure which arises at the supply connection 2.

(51) If, for example, a pressure sensor 88 at the working outlet 28 of the relay valve 18 is closed and therefore can also be or is also connected to the connection 40 for the at least one spring brake actuator or to the connection 66 for the trailer control valve, the actual pressure can thus be determined there and the operating state of the at least one spring brake actuator (released, applied or partially released or partially applied) can be determined therefrom. The same then also applies to the operating state of the trailer brakes, which state can be determined from the actual pressure at the connection for the trailer control valve. Furthermore, it is then possible to implement a pressure regulating circuit in which the solenoid valve device 8 forms, in conjunction with the relay valve 18, the actuator elements. However, if the pressure sensor 88 is used exclusively, the pressure regulator does not however detect pressure deviations until a deviation has already occurred in the working outlet pressure of the relay valve 18. This can lead to increased consumption of pressurized air.

(52) If a pressure sensor 89 is connected to the control inlet 20 of the relay valve, the actual pressure which is applied by the first and second 2/2-way solenoid valves 10, 12 can be determined very quickly, which results in high dynamics of the pressure regulating circuit. Furthermore, the operating state of the at least one spring brake actuator (released, applied or partially released or partially applied) and the actual brake pressure prevailing there can also be determined, but with less accuracy compared to the use of the pressure sensor 88, since the response behavior and hysteresis of the relay valve 18 are included as errors. The same then also applies to the operating state of the trailer brakes. When the pressure sensor 89 is used, the pressure regulator can particularly advantageously compensate pressure deviations in the control chamber 42 so precisely that they do not lead to pressure deviation at the working outlet of the relay valve.

(53) If a first pressure sensor 88 is connected to the working outlet 28, and a second pressure sensor 89 is connected to the control inlet of the relay valve 18, this also permit troubleshooting by means of plausibility checking. For example, the actual pressure values of the first and second pressure sensors 88, 89 must be in a specific relationship with respect to one another depending on the operating state, taking into account specific tolerances. In this context, the troubleshooting or fault monitoring can be carried out quickly, completely and in a plurality of operating states. Furthermore, faster pressure regulation with less consumption of pressurized air occurs than if just one pressure sensor 88 is arranged at the working outlet 28 of the relay valve 18, and more precise pressure regulation of the working outlet pressure occurs than if just one pressure sensor 89 is arranged at the control inlet 20 of the relay valve 18.

(54) According to one embodiment, the relay valve 18, the first solenoid valve device 8 (first and second 2/2-way solenoid valves 10, 12), the nonreturn valve 4, the first throttle element 30, the electronic control device 14 and the supply connection 2, the connection 2 for the at least one spring brake actuator and the parking brake signal connection 32 can be embodied in one structural unit, which constitutes here a basic module which can be expanded. Furthermore, at least one pressure sensor 88 and/or 89 can be integrated into the basic module or the structural unit 92. Furthermore, of course the electrical and pneumatic lines which connect the specified components to one another pneumatically or electrically are also integrated into the structural unit. The structural unit or the basic module can have a single housing or be composed of a plurality of housings or housing parts which are connected to one another in a releasable or nonreleasable fashion.

(55) It is also to be mentioned that a combination of the electropneumatic parking brake control device with another electronically controlled vehicle system to form one structural unit can be advantageous, since one common electronic control device can be provided. In particular, the combination with an air conditioning system provides advantages, since the supply line to the electropneumatic parking brake control device can also be dispensed with here.

(56) It is possible to combine features of different embodiments of the invention, and this is suggested herewith.

LIST OF REFERENCE SYMBOLS

(57) 1 Brake control device

(58) 2 Supply connection

(59) 4 Nonreturn valve

(60) 6 Supply line

(61) 8 Solenoid valve device

(62) 10 First 2/2-way solenoid valve

(63) 12 Second 2/2-way solenoid valve

(64) 14 Control device

(65) 16 Supply inlet

(66) 18 Relay valve

(67) 20 Control inlet

(68) 22 Control line

(69) 24 Pressure sink

(70) 26 Feedback line

(71) 28 Working outlet

(72) 30 First throttle element

(73) 32 Parking brake signal connection

(74) 34 Signal line

(75) 36 Parking brake signal generator

(76) 38 Working line

(77) 40 Connection for spring brake actuator

(78) 42 Control chamber

(79) 44 Relay valve housing

(80) 46 Relay piston

(81) 48 Valve body

(82) 50 Outlet seat

(83) 52 Collar

(84) 54 Inlet seat

(85) 56 Vent

(86) 58 Working chamber

(87) 60 Supply chamber

(88) 62 Collar spring

(89) 64 Relay piston spring

(90) 65 Second throttle element

(91) 66 Third throttle element

(92) 67 Relay piston seal

(93) 68 Lateral wall

(94) 70 Axial direction of movement

(95) 72 End

(96) 74 Arrow

(97) 76 Transverse drilled hole

(98) 78 Arrow

(99) 88 First pressure sensor

(100) 89 Second pressure sensor