Parking brake device for a motor vehicle

Abstract

A parking brake device for a motor vehicle, in particular a utility vehicle, includes at least one compressed air connection, at least one first control solenoid valve unit, at least one trailer control bistable valve, and at least one first compressed air outlet. The compressed air connection is connectable to the first control solenoid valve unit and the trailer control bistable valve. The first control solenoid valve is connectable to the trailer control bistable valve via at least one first control line. The trailer control bistable valve is connectable to the first compressed air outlet via at least one trailer control outlet line. The parking brake device has at least one towing vehicle control bistable valve and at least one second compressed air outlet. The compressed air connection is connectable to the towing vehicle control bistable valve. The towing vehicle control bistable valve is connectable to the second compressed air outlet via at least one towing vehicle control outlet line. At least one towing vehicle outlet branch is arranged in the towing vehicle control outlet line between the towing vehicle control bistable valve and the second compressed air outlet. The first control solenoid valve unit is connectable to the towing vehicle control outlet line via at least one bypass control line and via the towing vehicle control outlet branch.

Claims

1. A parking brake device for a motor vehicle, comprising: at least one compressed air port; at least one first control solenoid valve unit; at least one trailer control bistable valve; and at least one first compressed air outlet, wherein the compressed air port is connectable to the first control solenoid valve unit and to the trailer control bistable valve, wherein the first control solenoid valve unit is connectable to the trailer control bistable valve via at least one first control line, and wherein the trailer control bistable valve is connectable to the first compressed air outlet via at least one trailer control outlet line, at least one tractor vehicle control bistable valve; and at least one second compressed air outlet, wherein the compressed air port is connectable to the tractor vehicle control bistable valve, and wherein the tractor vehicle control bistable valve is connectable to the second compressed air outlet via at least one tractor vehicle control outlet line, wherein at least one tractor vehicle outlet branch is arranged in the tractor vehicle control outlet line, between the tractor vehicle control bistable valve and the second compressed air outlet, and wherein the first control solenoid valve unit is connectable to the tractor vehicle control outlet line via at least one bypass control line and via the tractor vehicle outlet branch, wherein the first control solenoid valve unit has at least one first control solenoid valve and at least one second control solenoid valve, and at least one pressure sensor is arranged in a connecting line between the first and second control solenoid valves.

2. The parking brake device as claimed in claim 1, wherein the first control solenoid valve unit is configured in such a way that the first control solenoid valve is arranged between the compressed air port and the first control line, and the second control solenoid valve is arranged between the first control line and the bypass control line.

3. The parking brake device as claimed in claim 1, wherein at least one first control branch is arranged in the first control line, between the trailer control bistable valve and the first control solenoid valve unit, at least one trailer outlet branch is arranged in the trailer control outlet line, between the trailer control bistable valve and the first compressed air outlet, and the first control line is connected to the trailer control outlet line at the first control branch via at least one first feedback line at the trailer outlet branch.

4. The parking brake device as claimed in claim 3, wherein at least one first throttle unit is arrangeable in the trailer control outlet line, wherein the first throttle unit is arranged between the trailer control bistable valve and the trailer outlet branch, and/or wherein the first throttle unit is arrangeable in the first feedback line.

5. The parking brake device as claimed in claim 3, wherein the first feedback line forms, in conjunction with the first control branch and the trailer outlet branch, a feedback connection between a first control inlet and a first outlet of the trailer control bistable valve.

6. The parking brake device as claimed in claim 1, wherein the parking brake device has at least one second control solenoid valve unit which is connectable to the compressed air port and to the tractor vehicle control bistable valve, and the second control solenoid valve unit is connectable to the tractor vehicle control bistable valve via at least one second control line.

7. The parking brake device as claimed in claim 6, wherein at least a second control branch is arranged in the second control line, between the tractor vehicle control bistable valve and the second control solenoid valve unit, and the second control line is connected to the tractor vehicle control outlet line at the second control branch, via at least one second feedback line at the tractor vehicle outlet branch.

8. The parking brake device as claimed in claim 6, wherein the parking brake device has at least one second throttle unit which is arranged in the second feedback line, between the tractor vehicle outlet branch of the tractor vehicle control outlet line and the second control branch of the second control line.

9. The parking brake device as claimed in claim 6, wherein the second control solenoid valve unit has at least one third control solenoid valve and at least one venting solenoid valve with at least one venting outlet.

10. The parking brake device as claimed in claim 9, wherein the second control solenoid valve unit is configured in such a way that the third control solenoid valve is arranged between the compressed air port and the second control line, and the venting solenoid valve is arranged between the second control line and the venting outlet.

11. The parking brake device as claimed in claim 7, wherein the second feedback line forms, in conjunction with the second control branch and the tractor vehicle outlet branch, a feedback connection, via the second throttle unit, between a control inlet and an outlet of the tractor vehicle control bistable valve.

12. The parking brake device as claimed in claim 1, wherein the tractor vehicle control bistable valve is embodied as a tractor vehicle control relay valve, and/or the trailer control bistable valve is embodied as a trailer control relay valve or as a 3/2-way valve which is actuated pneumatically.

13. The parking brake device as claimed in claim 1, wherein the parking brake device is a utility vehicle parking brake device.

14. The parking brake device of claim 1 wherein the trailer control bistable valve comprises an inlet, a working outlet, a control inlet, and a venting outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a first exemplary embodiment of a parking brake device according to the invention in a parked state; and

(2) FIG. 2 shows a second exemplary embodiment of a parking brake device according to the invention in a parked state.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 shows a schematic illustration of a parking brake device 1 for a motor vehicle, here a utility vehicle.

(4) The parking brake device 1 has a compressed air port 10 and a first control solenoid valve unit 20a and a trailer control bistable valve 40a for a trailer.

(5) The trailer control bistable valve 40a is embodied as a trailer control relay valve 40a.

(6) The trailer control relay valve 40a is provided with an inlet 43a, with an outlet or working outlet 44a, a control inlet 45a and a venting outlet 46a.

(7) The compressed air port 10 is connected to the inlet 43a of the trailer control relay valve 40a.

(8) The trailer control relay valve 40a constitutes a bistable element.

(9) Various operating states of the parking brake device 1 for a trailer or its trailer control valve, in particular a first and a second parked state, a driving state and a graduated braking state, can be modelled in the form of air pressures as a function of the pressure at the control inlet 45a of the trailer control relay valve 40a, at its outlet 44a.

(10) Furthermore, an anti-jack-knife braking state can also be provided in the sense of the first exemplary embodiment according to FIG. 1.

(11) In particular, in FIG. 1 the exemplary embodiment is illustrated in a first parked state.

(12) The first control solenoid valve unit 20a is also provided with a first control solenoid valve 21a and a second control solenoid valve 22a.

(13) The first control solenoid valve 21a and the second control solenoid valve 22a are provided as 2/2-way valves which can be electrically activated or actuated.

(14) The first control solenoid valve 21a is configured to be closed in the currentless state.

(15) The second control solenoid valve 22a is configured to be closed in the currentless state.

(16) The compressed air port 10 is connected to the first control solenoid valve unit 20a, in particular to the first control solenoid valve 21a.

(17) The compressed air port 10 is represented here by a compressed air source (not illustrated in more detail) and a nonreturn valve 11 which is shown.

(18) Furthermore, the parking brake device 1 is provided with a first control line 41a.

(19) The first control line 41a is connected to the first control solenoid valve unit 20a in such a way that the first control solenoid valve 21a and the second control solenoid valve 22a are connected to the first control line 41a independently of one another.

(20) The first control line 41 is connected to the control inlet 45a of the trailer control relay valve 40a.

(21) A pneumatic connection is therefore available between the first control solenoid valve unit 20a and the first control inlet 45a of the trailer control relay valve 40a. The first control line 41a has a first control branch 42a upstream of the trailer control relay valve 40a.

(22) Furthermore, the parking brake device 1 has a first feedback line 51a.

(23) The first feedback line 51a is connected to the first control line 41a via the first control branch 42a.

(24) Furthermore, the first feedback line 51a is connected to a trailer control outlet line 80a via a trailer outlet branch 81a.

(25) Accordingly, a feedback connection is present between the control inlet 45a and the working outlet 44a of the trailer control relay valve 40a via the first feedback line 51a.

(26) The first feedback line 51a is therefore connected to the outlet or working outlet 44a of the trailer control relay valve 40a via the trailer outlet branch 81a.

(27) In this way, the first feedback line 51a forms a feedback connection between the outlet 44a and the control inlet 45a of the trailer control relay valve 40.

(28) The parking brake device 1 also has a first compressed air outlet 71 in the form of a trailer control outlet 71.

(29) According to FIG. 1, compressed air can be directed from the outlet 44a of the trailer control relay valve 40a to the trailer control outlet 71 via the trailer control outlet line 80a.

(30) Starting from the trailer control outlet 71, the compressed air can preferably be fed to a control inlet of a trailer control valve (not shown in FIG. 1) for controlling one or more spring-loaded brake cylinders of the trailer.

(31) According to the present invention, there is generally preferably provision that a first throttle unit 52a is arranged in the trailer control outlet line 80a, between the outlet 44a of the trailer control relay valve 40a and the trailer outlet branch 81a.

(32) In addition, according to the present invention there is additionally or alternatively provision that a further throttle unit is arranged along the first feedback line 51a, between the first control branch 42a of the first control line 41a and the trailer outlet branch 81a of the trailer control outlet line 80a.

(33) The fluid pressure or air pressure at the outlet 44a of the trailer control relay valve 40a can be set and open-loop and closed-loop controlled in a targeted fashion by means of the first feedback line 51a with the first throttle unit 52a.

(34) Moreover, a first pressure sensor 73a can be arranged in a connecting line between the first and second control solenoid valves 21a, 22a.

(35) Therefore, the air pressure or fluid pressure at the control inlet 45a of the trailer control relay valve 40a can be detected and open-loop and/or closed-loop controlled in a targeted fashion.

(36) Furthermore, a tractor vehicle control bistable valve 40b and a second control solenoid valve unit 20b of the parking brake device 1 are shown in FIG. 1.

(37) The tractor vehicle control bistable valve 40b is embodied as a tractor vehicle control relay valve 40b.

(38) The second control solenoid valve unit 20b is shown with a third control solenoid valve 21b, a venting valve or venting solenoid valve 22b and a venting outlet 23b.

(39) The venting outlet 23b can be present integrated into the venting solenoid valve 22b according to FIG. 1.

(40) The third control solenoid valve 21b is accordingly configured in a way comparable to the first control solenoid valve 21a.

(41) The third control solenoid valve 21b and the tractor vehicle control relay valve 40b are preferably connected to the compressed air port 10.

(42) Alternatively there can also be provision that the third control solenoid valve 21b and the tractor vehicle control relay valve 40b are connected to a separate, second compressed air port, which is embodied in a way essentially comparable to the compressed air port 10 described above.

(43) The second compressed air port (not shown in FIG. 1) can therefore also be embodied by means of a compressed air source (not illustrated in more detail) and a second nonreturn valve.

(44) Furthermore, the parking brake device 1 has a second control line 41b according to FIG. 1.

(45) The second control solenoid valve unit 20b and the tractor vehicle control relay valve 40b are connected to one another via the second control line 41b.

(46) Like the trailer control relay valve 40a, the tractor vehicle control relay valve 40b has an inlet 43b, an outlet 44b, a control inlet 45b and a venting outlet 46b.

(47) The second control line 41b is connected to the control inlet 45b of the tractor vehicle control relay valve 40b.

(48) The method of functioning of the trailer control relay valve 40a and tractor vehicle control relay valve 40b is preferably identical and comparable.

(49) A second control branch 42b is provided upstream of the tractor vehicle control relay valve 40b in the second control line 41b.

(50) Moreover, the parking brake device 1 has a second feedback line 51b which is connected to the second control line 41b via the second control branch 42b.

(51) The second feedback line 51b is connected to a tractor vehicle control outlet line 80b via a tractor vehicle outlet branch 81b.

(52) The tractor vehicle control outlet line 80b is connected to the outlet 44b of the tractor vehicle control relay valve 40b.

(53) The second feedback line 51b therefore forms a feedback from the outlet 44b of the tractor vehicle control relay valve 40b to the control inlet 45b of the tractor vehicle control relay valve 40b via the tractor vehicle control outlet line 80b, the tractor vehicle outlet branch 81b, the second control branch 42b and the control line 41b.

(54) A second throttle unit 52b is arranged in the second feedback line 51b, between the tractor vehicle outlet branch 81b of the tractor vehicle control outlet line 80b and the second control branch 42b of the second control line 41b.

(55) Therefore, by virtue of the second feedback line 51b and the second throttle unit 52b, an, in particular throttled, feedback is continuously present between the outlet 44b and the controlled inlet 45b of the tractor vehicle control relay valve 40b.

(56) Moreover, a second pressure sensor 73b can be arranged in the second feedback line 51b of the tractor vehicle control relay valve 40b.

(57) Therefore, the air pressure or fluid pressure at the outlet 44b of the tractor vehicle control relay valve 40b can be detected and open-loop and/or closed-loop controlled in a targeted fashion.

(58) According to FIG. 1, compressed air can be passed on from the outlet 44b of the tractor vehicle control relay valve 40b, along the tractor vehicle control outlet line 80b via the select high valve 70 to a second compressed air outlet 72 in the form of a spring-loaded brake cylinder outlet 72 for the tractor vehicle of a utility vehicle.

(59) The select high valve 70 is connected via the tractor vehicle control outlet line 80b to the second feedback line 51b, the spring-loaded brake cylinder outlet 72 and further compressed air outlet 74, embodied as a service brake outlet 74 for a tractor vehicle.

(60) The spring-loaded brake cylinder outlet 72 and the service brake outlet 74 constitute in this way compressed air outlets for one or more spring-loaded brake cylinders of the parking brake or for one or more service brake cylinders of the service brake.

(61) The switching behavior of the select high valve 70 follows the primary pressure gradient present.

(62) Therefore, the spring-loaded brake cylinder outlet 72 is aerated with a high pressure of the outlet 44b of the tractor vehicle control relay valve 40b, wherein the connection to the service brake outlet 74 at which a relatively low pressure is present is blocked.

(63) Moreover, when the service brake is activated and there is build up in pressure associated therewith at the service brake outlet 74, it is possible for compressed air to pass from the service brake outlet 74 into the spring-loaded brake cylinder outlet 72 via the select high valve 70.

(64) If a higher pressure is present at the service brake outlet 74 than at the outlet 44b of the tractor vehicle control relay valve 40b, the select high valve 70 opens, according to the pressure gradient, a connection between the service brake outlet 74 and the spring-loaded brake cylinder outlet 72.

(65) It is consequently possible to achieve a combined braking effect when the service brake of the tractor vehicle is activated at the service brake outlet 74 in combination with at least one spring-loaded brake cylinder of the tractor vehicle at the spring-loaded brake cylinder outlet 72 by means of the select high valve 70.

(66) A connection of the tractor vehicle control relay valve 40b, in particular its outlet 44b and the select high valve 70, in particular the service brake 74 and/or the spring-loaded brake cylinder outlet 72, to the second control line 41b along the second feedback line 51b can be controlled or monitored by means of the second throttle unit 52b.

(67) The pneumatic connection of the trailer control relay valve 40a and of the tractor vehicle control relay valve 40b are essentially comparable with one another in respect of their basic design.

(68) However, the pneumatic connection of the trailer control outlet line 80a and of the tractor vehicle control outlet line 80b between the trailer and tractor vehicle outlet branches 81a, 81b and the respectively assigned outlets 71, 72, 74 differs.

(69) Therefore, for example according to FIG. 1, the arrangement of the select high valve 70 is provided for connecting the spring-loaded brake cylinder outlet 72 and the service brake outlet 74 to the outlet 44b of the tractor vehicle control relay valve 40b only in conjunction with the pneumatic connection of the tractor vehicle control relay valve 40b.

(70) In addition, the first control solenoid valve unit 20a has a different pneumatic connection than the second control solenoid valve unit 20b.

(71) Therefore, the second control solenoid valve unit 20b according to FIG. 1 has a third control solenoid valve 21b, a venting solenoid valve 22b and a venting outlet 23b.

(72) According to FIG. 1, the venting outlet 23b can be embodied integrated in the venting solenoid valve 22b.

(73) The first control solenoid valve unit 20a in turn has a first control solenoid valve 21a which is comparable with the second control solenoid valve unit 20b and is correspondingly connected in a comparable pneumatic fashion.

(74) However, the second control solenoid valve 22a of the first control solenoid valve unit 20a and the venting solenoid valve 22b of the second control solenoid valve unit 20b differ in their design and in their pneumatic connection in the parking brake device 1.

(75) Instead of the venting outlet 23b according to the venting solenoid valve 22b, the second control solenoid valve 22a has a further control port in the form of a bypass control port 22a.1.

(76) The second control solenoid valve 22a is connected to the tractor vehicle control outlet line 80b by means of this bypass control port 22a.1, via a bypass control line 41c, preferably via the tractor vehicle outlet branch 81b.

(77) According to FIG. 1, the tractor vehicle control outlet line 80b can be connected at its tractor vehicle outlet branch 81b (arranged between the tractor vehicle control relay valve 40b and the spring-loaded brake cylinder outlet 72 or the service brake outlet 74) to the first control solenoid valve unit 20a by means of the bypass control line 41c.

(78) The trailer control outlet line 80a can be connected to the tractor vehicle control outlet line 80b via the first feedback line 51a and the first control line 41a on the basis of this additional bypass connection, so that the operating pressure can be applied to the trailer control outlet line 80a by the tractor vehicle control outlet line 80b.

(79) In addition, in order to set a stepped operating pressure reduction, both the tractor vehicle control outlet line 80b and the trailer control outlet line 80a can be vented by means of the venting solenoid valve 22b.

(80) The method of operation of the parking brake device 1 according to FIG. 1 will be explained below:

(81) In a first parked state or according to a first parking strategy (respective switch positions of the valves as illustrated in FIG. 1), the first and the second control solenoid valves 21a; 21b are connected in a currentless and pneumatically blocked fashion.

(82) Therefore, compressed air cannot enter the first control line 41a or the second control line 41b from the compressed air port 10 or from an external compressed air source.

(83) Therefore, there is no feedback in each case present between the respective outlet 44a; 44b and the respective control inlet 45a; 45b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b.

(84) Furthermore only the inlets 43a; 43b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b are supplied with compressed air.

(85) Since there is no pressure present at the control inlets 45a; 45b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b the respective venting outlets 46a; 46b thereof are opened.

(86) The first feedback line 51a and the second feedback line 52a are vented via the venting outlets 46a; 46b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b.

(87) By means of the pneumatic connection according to FIG. 1, the first control line 41a is also vented via the venting outlet 46a, and likewise the second control line 41b is vented via the venting outlet 46b.

(88) The spring-loaded brake cylinder outlet 72 of the parking brake device for the tractor vehicle and the trailer control outlet 71 for actuating a control inlet of the trailer control valve (each not shown in FIG. 1) are therefore also vented.

(89) The venting of the spring-loaded brake cylinder outlet 72 brings about corresponding venting of the spring compression spaces of the spring-loaded brake cylinders of the vehicle, in response to which the tractor vehicle brake system is activated.

(90) However, the venting of the trailer control outlet 71 causes, owing to the inverse pneumatic actuation of the control inlet of the trailer control valve, the service brake cylinders of the trailer to be supplied with compressed air, so that the trailer is also in a braked parked state.

(91) This first parked state is present in the form of a braked parked state of the trailer, in particular in an at least partially laden state of the trailer.

(92) Such trailers are embodied, e.g. as a trailer-convertor dolly and can be used, for example, to transport elongate material for transportation which is to a certain extent self-supporting, such as tree trunks, beams and bars (made of wood, steel, concrete etc.).

(93) The spring-loaded brake cylinder of the tractor vehicle or the service brake cylinders of the trailer are activated in this way and provide a braking force.

(94) The service brake outlet 74 of the parking brake device 1 for the tractor vehicle is vented in the first parked state. The service brake of the tractor vehicle is released in this way.

(95) In a second parked state or according to a second parking strategy (not illustrated in FIG. 1), the first control solenoid valve 21a is energized so that it is changed into an open position.

(96) The second control solenoid valve 21b for controlling the parking brake of the tractor vehicle is also connected, as illustrated in FIG. 1, in a currentless and pneumatically blocked fashion.

(97) The open position of the first control solenoid valve 21a causes the control inlet 45a of the trailer control relay valve 40a to be aerated, in response to which the trailer control relay valve 40a changes from a blocked position into an open position when a control threshold pressure is reached.

(98) The inlet 43a and the outlet 44a of the trailer control relay valve 40a are consequently connected to one another pneumatically so that compressed air is provided by its inlet 43a at its outlet 44a.

(99) This provision of compressed air also results in aeration of the first feedback line 51a, of the first control line 41a and in particular of the trailer control outlet line 80a.

(100) As soon as the control inlet 45a and the trailer control outlet 71 are sufficiently aerated, the first control solenoid valve 21a is switched to a disconnected or closed position.

(101) The stable aeration above the control threshold pressure of the first control inlet 45a of the trailer control relay valve 40a takes place when the first control solenoid valve 21a is now closed, via the first feedback line 51a and the operating pressure of the trailer control outlet line 80a. The trailer control outlet 71 is therefore aerated.

(102) The aeration of the trailer control outlet 71 caused, by means of the inverse pneumatic actuation of the control limit of the trailer control valve, the service brake cylinders of the trailer not to be supplied with compressed air or vented so that the trailer is an unbraked parked state.

(103) This second parked state of the trailer, which is configured, e.g. as a trailer-convertor dolly in the form of an unbraked parked state, in particular in an unladen state of the trailer.

(104) The spring-loaded brake cylinders of the tractor vehicle are in turn vented as in the first parked state and as result activated and provide a braking force.

(105) Only the service brake cylinders of the trailer are deactivated in this way and do not provide any braking force.

(106) The service brake outlet 74 of the parking brake device 1 for the tractor vehicle is also vented in the second parked state. The service brake of the tractor vehicle is released in this way.

(107) In order to change from the first parked state into a driving state, according to FIG. 1 the first and second control solenoid valves 21a; 21b are energized and switched to an open or transmitting position in contrast to the first parked state.

(108) In order correspondingly to change from the second parked state into a driving state, according to FIG. 1 the first control solenoid valve 21a is not actuated, in contrast with the second parked state, since, as explained above, according to the second parked state it is at least temporarily already switched to an open or transmitting position and the trailer control outlet line 80a is already aerated.

(109) Compressed air is fed into the first and second control lines 41a; 41b through the control solenoid valves 21a; 21b which are now switched to the open position.

(110) The control inlets 45a; 45b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b are aerated via the control lines 41a; 41b.

(111) When a control threshold pressure is reached or exceeded, a connection between the inlet 43a; 43b and the outlet 43a; 43b is respectively established in the relay valves 40a; 40b so that compressed air is provided at the outlets 44a; 44b.

(112) When the control threshold pressure at the control inlets 45a; 45b is reached or exceeded, the venting outlets 46a; 46b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b are closed.

(113) The service pressure which is then present at the outlet 44b of the trailer vehicle control relay valve 40b is passed on, in accordance with the prevailing pressure difference, along the tractor vehicle control outlet line 80b to the spring-loaded brake cylinder outlet 72 via the select high valve 70.

(114) Accordingly, the service brake of the outlet 44a of the trailer control relay valve 40a is also passed on to the trailer control outlet 71.

(115) The spring-loaded brake cylinder outlet 72 and the trailer control outlet 71 are therefore aerated. In this way, the parking brake of the tractor vehicle and the service brake of the trailer are released so that a braking force is not applied and the utility vehicle is in a driving state.

(116) As soon as the spring-loaded brake cylinder outlet 72 and the trailer control outlet 71 are sufficiently aerated, the first and the second control solenoid valves 21a; 21b are switched to a disconnected or closed position.

(117) The stable aeration above the control threshold pressure of the respective control inlets 45a, 45b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b is carried out when the control solenoid valves 21a, 21b are then closed, via the respective first and second feedback lines 51a, 51b and the service pressure of the trailer control outlet line 80a and the tractor vehicle control outlet line 80b.

(118) The trailer control outlet 71 and the spring-loaded brake cylinder outlet 72 are therefore aerated.

(119) The service brake outlet 74 for a tractor vehicle is vented.

(120) In this way, a driving state of the motor vehicle in the form of a utility vehicle, with a tractor vehicle and a trailer, is brought about.

(121) In order to change from a driving state correspondingly into the first parked state, the control solenoid valve 22a and the venting solenoid valve 22b are firstly switched to an open or transmitting position starting from the driving state, so that basically compressed air can escape via the venting outlet 23b.

(122) The service pressure of the first and second control lines 41a, 41b is reduced or vented in conjunction with the control inlets 45a; 45b.

(123) The venting of the second control line 41b then takes place directly via its corresponding port to the venting solenoid valve 22b.

(124) In contrast, the venting of the first control line 41a also takes place via the venting solenoid valve 22b, but the venting path which is correspondingly provided for this purpose is formed by: the second control solenoid valve 22a, the bypass control line 41c, the second feedback line 51b and the first control line 41a.

(125) The respective pneumatic connection between the inlets 43a; 43b and the outlets 44a; 44b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b is disconnected by means of the decreasing pressure in the controlled inlets 45a; 45b.

(126) The venting outlets 46a; 46b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b are opened again.

(127) The service pressure from the second feedback line 51b in conjunction with the tractor vehicle control outlet line 80b and the spring-loaded brake cylinder outlet 72 is then additionally vented via the venting outlet 46b of the tractor vehicle control relay valve 40b.

(128) Furthermore, venting of the tractor vehicle control outlet line 80b and of the spring-loaded brake cylinder outlet 72 takes place via the venting solenoid valve 22b which is switched to the open position, owing to the continuously present feedback via the second feedback line 51b to the second throttle unit 52b.

(129) Moreover, the service pressure from the first feedback line 51a is additionally vented, in conjunction with the trailer control outlet line 80a and the trailer control outlet 71, via the venting outlet 46a of the trailer control relay valve 40a.

(130) At least partial venting of the trailer control outlet line 80a and of the trailer control outlet 71 takes place via the venting valve 22b which has been switched to the open position owing to the continuously present feedback via the first feedback line 51a and via the venting path described above.

(131) As soon as the spring-loaded brake cylinder outlet 72 and the trailer control outlet 71 are sufficiently vented, the second control solenoid valve 22a and the venting solenoid valve 22b are switched to a closed position so that the first parked state is then present.

(132) Therefore, a first parked state according to FIG. 1 with the vented spring-loaded brake cylinder outlet 72 and the vented trailer control outlet 71 is brought about.

(133) The parking brake of the tractor vehicle and of the trailer are activated and apply a corresponding braking effect.

(134) In order to change from a driving state correspondingly into the second parked state, only the venting solenoid valve 22b is switched to the open or transmitting position starting from driving state, so that compressed air can escape via the venting outlet 23b.

(135) The venting of the tractor vehicle control outlet line 80b and of the spring-loaded brake cylinder outlet 72 then takes place in a way comparable to its corresponding venting according to the change described above from a driving state into a first parked state.

(136) In order to change from a driving state into the second parked state, the second control solenoid valve 22a remains in its blocked position so that when the tractor vehicle control outlet line 80b is vented, the trailer control outlet line 80a remains nevertheless in an aerated state, as already described above in relation to the second parked state.

(137) The transfer of the parking brake device 1 according to the invention from the driving state in the first or second parked state can also take place automatically as a function of the load state of the utility vehicle.

(138) The sensing of the load state of the utility vehicle and preferably of the trailer is carried out by means of one or more load sensors.

(139) The load sensors are preferably configured and designed to sense the load state of the trailer, e.g. in the form of a laden weight, laden volume and its respective distribution within the trailer.

(140) A pneumatic connection of the parking brake device 1 according to the second parked state also moreover corresponds to a so-called trailer test state of the parking brake device 1.

(141) Such connection of the parking brake device 1 is carried out independently of the load state of the trailer in response to a corresponding trailer test command of a vehicle driver.

(142) Furthermore, a graduated braking state can also be brought about from the driving state.

(143) The control solenoid valves 21a; 21b; 22a and the venting solenoid valve 22b are preferably connected to a partially open or transmitting state, in particular by means of a plurality of short successive pulsed activation operations.

(144) The first and second control lines 41a; 41b are therefore aerated or vented.

(145) The control inlets 45a; 45a of the trailer control relay valve 40a and tractor vehicle control relay valve 40b are aerated with a specific control pressure which is between 0 bar and the maximum system pressure.

(146) The specific control pressure can be set as a function of the degree of opening of the control solenoid valves 21a; 21b; 22a and the venting solenoid valve 22b.

(147) Proportional pressures are preferably provided at the outlets 44a; 44b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b by means of the specific pressure at the control inlets 45a; 45b.

(148) The spring-loaded brake cylinder outlet 72 and the trailer control outlet 71 are vented in such a way that a partial braking effect of the tractor vehicle and of the trailer is brought about.

(149) As described above (in relation to the changeover from a driving state correspondingly into the first parked state), stepped venting of the trailer control outlet line 80a and of the tractor vehicle control outlet line 80b take place together via the venting solenoid valve 22b and the correspondingly described venting path.

(150) A graduated braking state with partial braking effect of the motor vehicle can be provided.

(151) In this way, constant pressures can be maintained and changed incrementally over a specific time period at the outlets 44a; 44b of the trailer control relay valve 40a and tractor vehicle control relay valve 40b.

(152) Since the spring-loaded brake cylinder outlet 72 and the trailer control outlet 71 are at certain times aerated with constant, incrementally changed pressures, the braking effect of the tractor vehicle and of the trailer can be varied incrementally.

(153) Moreover, it is also possible to implement an anti-jack-knife state with the exemplary embodiment according to FIG. 1, in particular from a driving state.

(154) The switching over into the operating state for the anti-jack-knife function is based essentially on the switching processes described above.

(155) The spring-loaded brake cylinder outlet 72 of the tractor vehicle is preferably aerated in the anti-jack-knife state.

(156) The trailer control outlet 71 can be vented or aerated as required, in particular by means of the tractor vehicle control relay valve 40b in conjunction with the first control solenoid valve unit 20a.

(157) The trailer control outlet 71 can therefore be expediently aerated with compressed air or vented, in particular in a way which can be graduated.

(158) A braking effect which can be graduated of the trailer is therefore available, in order to extend the motor vehicle during the driving state and in this way stabilize it.

(159) The second exemplary embodiment (illustrated in FIG. 2) of the parking brake device 1 according to the invention has essentially the same structural and functional features as the first exemplary embodiment of the parking brake device 1 according to the invention which is described according to FIG. 1.

(160) Only the following, in particular structural, differences in respect of features are to be indicated:

(161) Instead of the trailer control relay valve 40a, the second exemplary embodiment of the parking brake device 1 according to the invention has a bistable 3/2-way valve 40a, which can be actuated pneumatically and fed back, for the purpose of performing open-loop and/or closed-loop control of the first trailer control outlet line 80a.

LIST OF REFERENCE SYMBOLS

(162) 1 Parking brake device 10 Compressed air port 11 Nonreturn valve 20a First control solenoid valve unit 20b Second control solenoid valve unit 21a First control solenoid valve 21b Third control solenoid valve 22a Second control solenoid valve 22a.1 Bypass control port 22b Venting solenoid valve 23b Venting outlet 40a Trailer control relay valve 40b Tractor vehicle control relay valve 41a First control line 41b Second control line 41c Bypass control line 42a First control branch 42b Second control branch 43a Inlet of the trailer control relay valve 43b Inlet of the tractor vehicle control relay valve 44a Outlet of the trailer control relay valve 44b Outlet of the tractor vehicle control relay valve 45a Control inlet of the trailer control relay valve 45b Control inlet of the tractor vehicle control relay valve 46a Venting outlet of the trailer control relay valve 46b Venting outlet of the tractor vehicle control relay valve 51a First feedback line 51b Second feedback line 52a First throttle unit 52b Second throttle unit 70 Select high valve 71 Trailer control outlet 72 Spring-loaded brake cylinder outlet 73a First pressure sensor 73b Second pressure sensor 74 Service brake outlet 80a Trailer control outlet line 80b Tractor vehicle control outlet line 81a Trailer outlet branch 81b Tractor vehicle outlet branch 1 Parking brake device 10 Compressed air port 11 Nonreturn valve 20a First control solenoid valve unit 20b Second control solenoid valve unit 21a First control solenoid valve 21b Third control solenoid valve 22a Second control solenoid valve 22a.1 Bypass control port 22b Venting solenoid valve 23b Venting outlet 40a Bistable 3/2-way valve 40b Tractor vehicle control relay valve 41a First control line 41b Second control line 41c Bypass control line 42a First control branch 42b Second control branch 43a Inlet of the bistable 3/2-way valve 43b Inlet of the tractor vehicle control relay valve 44a Outlet of the bistable 3/2-way valve 44b Outlet of the tractor vehicle control relay valve 45a Control inlet of the bistable 3/2-way valve 45b Control inlet of the tractor vehicle control relay valve 46a Venting outlet of the bistable 3/2-way valve 46b Venting outlet of the tractor vehicle control relay valve 51a First feedback line 51b Second feedback line 52a First throttle unit 52b Second throttle unit 70 Select high valve 71 Trailer control outlet 72 Spring-loaded brake cylinder outlet 73a First pressure sensor 73b Second pressure sensor 74 Service brake outlet 80a Trailer control outlet line 80b Tractor vehicle control outlet line 81a Trailer outlet branch 81b Tractor vehicle outlet branch