Method for operating a braking device and braking device for motor vehicles

Abstract

A method operates a braking device for motor vehicles, in particular for utility vehicles. Along a trailer supply line for supplying air to a parking brake of a trailer and/or a trailer control line for supplying air to an operating brake of a trailer, the air pressure is measured by at least one pressure transducer and is transmitted in the form of an electric signal to an electronic control unit of the motor vehicle. In the event of a faulty pressure change response, an open trailer supply line and/or an open trailer control line is detected.

Claims

1. A method for operating a braking device for a motor vehicle, comprising the acts of: along a trailer supply line for aerating a parking brake of a trailer which is provided such that an output of a first switching valve is connected to a first trailer coupling unit, measuring air pressure by way of a first pressure transducer; along a trailer control line for aerating a service brake of a trailer, which is provided such that an output of a second switching valve is connected to a second trailer coupling unit, measuring air pressure by way of a second pressure transducer; transmitting the measured air pressures, in the form of electrical signals, to an electronic control unit of the motor vehicle, so that in case of a faulty pressure change behavior, an open trailer supply line and/or an open trailer control line is detected.

2. The method as claimed in claim 1, wherein the faulty pressure change behavior is detected if the measured air pressures deviate within a predefinable timeframe from a predeterminable pressure change threshold value.

3. The method as claimed in claim 2, wherein in the case of a release of the parking brake of the trailer and tearing away of the trailer supply line and/or the trailer control line, a faulty pressure change behavior exists if the measured air pressures change corresponds to an absolute-value pressure change value which is greater than a predeterminable pressure drop threshold value.

4. The method as claimed in claim 2, wherein in the case of an engaged parking brake of the trailer, after the aerating of the trailer supply line and/or the trailer control line and a non-connected trailer supply line or trailer control line, a faulty pressure change behavior exists if the measured air pressures change corresponds to a pressure change value which is less than a predeterminable pressure increase threshold value.

5. The method as claimed in claim 1, wherein for detecting a faulty compressed air change behavior in the trailer control line, a pneumatic test pulse is generated by the first switching valve in conjunction with the trailer supply line and/or a pneumatic test pulse is generated along an input and an output of the second switching valve in conjunction with the trailer control line.

6. The method as claimed in claim 5, wherein the input and the output of the second switching valve are connected to one another and the pneumatic test pulse can be generated by an inlet valve and/or a vent valve or by an electrical braking signal.

7. The method as claimed in claim 6, wherein the first switching valve is provided in conjunction with the trailer supply line, which is switched with aid of the control unit into the venting state if a faulty pressure change behavior is detected in the trailer supply line and/or the trailer control line.

8. A braking device for a motor vehicle, comprising: at least one compressed air fitting; an electronic control unit; at least one input element; a first switching valve; a first pressure transducer; and a first trailer coupling unit and a second trailer coupling unit, wherein the electronic control unit is connected to the input element, a control input of the first switching valve, and the first pressure transducer, a trailer supply line is provided such that an output of the first switching valve is connected to the first trailer coupling unit, a trailer control line is provided, and a second switching valve, wherein the trailer control line is provided such that an output of the second switching valve is connected to the second trailer coupling unit, the first pressure transducer is provided in conjunction with an output of the first switching valve, and a second pressure transducer is provided in conjunction with an output of the second switching valve.

9. The braking device as claimed in claim 8, further comprising: a coupling line provided so that the trailer supply line is connected to a control input of the second switching valve.

10. The braking device as claimed in claim 8, wherein the at least one input element is provided in conjunction with the electronic control unit, so that the first switching valve is switchable by way of the input element.

11. The braking device as claimed in claim 8, wherein an inlet valve is provided such that an input of the second switching valve is connected or connectable to an output of the inlet valve.

12. The braking device as claimed in claim 11, wherein a vent valve is provided such that an input of the vent valve is connected to the output of the inlet valve.

13. The braking device as claimed in claim 12, further comprising: an anti jackknife braking unit provided in conjunction with the electronic control unit, so that the inlet valve is electrically switchable via a control input and/or the vent valve is electrically switchable via a control input by the control unit.

14. The braking device as claimed in claim 8, wherein the braking device is a utility vehicle braking device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a schematic diagram showing an exemplary embodiment of a braking device for motor vehicles having a first and second pressure transducer.

DETAILED DESCRIPTION OF THE DRAWING

(2) An exemplary embodiment of a braking device 1 for motor vehicles having a compressed air fitting 2 and an electronic control unit 3 is illustrated in FIG. 1.

(3) Compressed air can be supplied to the braking device 1 via the compressed air fitting 2, to be used further for the braking device 1, preferably after compressed air processing to remove oil and moisture from the compressed air.

(4) In particular, the compressed air fitting 2 can be connected to an arbitrary compressed air source.

(5) Furthermore, the electronic control unit 3 represents a central control. The control unit 3 is thus electrically connected to the other components of the braking device 1, such as valves, sensors, switches, or other types of input elements 4.

(6) An input element 4 can be understood in these terms as a sensor, switch, or the like, in particular as an electrical signal of the sensor, switch, or the like at the electronic control unit 3, so that automatic monitoring of the braking device can be triggered as needed.

(7) All signals and data can be supplied to the control unit 3, processed in the control unit 3, and control commands resulting therefrom can be relayed to at least one of the components of the braking device 1.

(8) Furthermore, according to FIG. 1, an input element 4 and a first switching valve 5 having an input 5a, an output 5b, a control input 5c, and a venting output 5d are shown.

(9) The input element 4 is electrically connected to the control unit 3.

(10) The first switching valve 5 is connected via the control input 5c to the control unit 3.

(11) Switching of the first switching valve 5 can thus be effectuated using the input element 4 via the control unit 3.

(12) The first switching valve 5 is switched according to FIG. 1 as a spring-loaded 3/2-way valve in such a way that the output 5b is connected to the venting output 5d.

(13) In particular, the first switching valve 5 can be provided as a bistable switching valve.

(14) Furthermore, the braking device 1 comprises a first trailer coupling unit 9.1 and a second trailer coupling unit 9.2.

(15) The first trailer coupling unit 9.1 is connected via a trailer supply line 10.1 to the output 5b of the first switching valve 5.

(16) According to the switching state of the first switching valve 5 in FIG. 1, the trailer supply line is vented via the venting output 5d of the first switching valve 5.

(17) Compressed air for aerating a parking brake and/or spring-type emergency brake of a trailer can preferably be provided via the trailer supply line 10.1 at the first trailer coupling unit 9.1.

(18) Furthermore, a second switching valve 7 is shown in FIG. 1.

(19) In particular, the second switching valve 7 in terms of FIG. 1 can be provided in the form of a tractor protective valve 6.

(20) The second switching valve 7 comprises an input 7a, an output 7b, and a control input 7c.

(21) The input 7a of the second switching valve 7 is indirectly connected via diverse pneumatic circuit components to the compressed air fitting 2 in such a way that, for example, by actuating a brake pedal, compressed air, in particular processed compressed air, can be supplied to the input 7a of the second switching valve.

(22) The output 7b of the second switching valve 7 is connected via a trailer control line 10.2 to the second trailer coupling unit 9.2 to be able to supply it with compressed air.

(23) The second trailer coupling unit 9.2 can be provided in particular for providing compressed air for a service brake of a trailer.

(24) According to FIG. 1, the second switching valve 7 is provided as a spring-loaded and normally closed or disconnected 2/2-way valve. In these terms, a connection between the input 7a and the output 7b of the second switching valve 7 is disconnected in the switching state according to FIG. 1.

(25) The control input 7c of the second switching valve 7 is connected via a coupling line 12 to the trailer supply line 10.1 and the output 5b of the first switching valve 5.

(26) Switching of the second switching valve 7 can thus be effectuated by changing the air pressure or the fluid pressure in the trailer supply line 10.1.

(27) In these terms, a pressure drop in the trailer supply line 10.1 and/or at the output 5b of the first switching valve 5 can have the result that the second switching valve 7 is transferred from a transmissive switching position into the disconnected switching position shown in FIG. 1.

(28) According to FIG. 1, the switching position of the second switching valve 7 is coupled to the air pressure or the fluid pressure in the trailer supply line 10.1.

(29) In addition, the braking device 1 in FIG. 1 is shown having a first pressure transducer or pressure sensor 8.1 and a second pressure transducer or pressure sensor 8.2.

(30) The first pressure transducer 8.1 is electrically connected to the control unit 3 and also the trailer supply line 10.1, i.e., the first pressure transducer 8.1 detects the air pressure in the trailer supply line 10.1, at the output 5b of the switching valve 5, and/or at the first trailer coupling unit 9.1.

(31) The second pressure transducer 8.2 is electrically connected to the control unit 3 and also the trailer control line 10.2, i.e., the second pressure transducer 8.2 detects the air pressure in the trailer control line 10.2, at the output 7b of the second switching valve 7, and/or at the second trailer coupling unit 9.2.

(32) By means of the first and second pressure transducer 8.1; 8.2, it can be established whether a suitable air pressure for operating the motor vehicle is present in the trailer supply line 10.1 and/or the trailer control line 10.2.

(33) In particular also the coupling state between tractor and trailer at the first and second trailer coupling unit 9.1; 9.2 may be derived from the air pressures in the trailer supply line 10.1 and the trailer control line 10.2.

(34) This function can be understood as a trailer detection function.

(35) If the first pressure transducer 8.1 in the trailer supply line 10.1 detects the air pressure and/or the pressure change behavior and the control unit 3 recognizes a faulty pressure change behavior therein, for example, suitable protective measures can be initiated by the control unit 3.

(36) The same applies to the case in which a faulty pressure change behavior is derived by the control unit 3 from the measured values of the second pressure transducer 8.2 relating to the air pressure in the trailer control line 10.2.

(37) If, during the operation of the braking device 1 in a motor vehicle, an air pressure in the trailer supply line 10.1 unexpectedly drops, switching over of the second switching valve 7 takes place simultaneously with the aid of the coupling line 12 at the control input 7c of the second switching valve 7.

(38) This can be understood as a tractor protective function, wherein by switching over the second switching valve 7 upon pressure loss in the trailer supply line 10.1, a potential possible pressure loss in the trailer control line 10.2 is prevented.

(39) Furthermore, a faulty pressure change behavior in the trailer supply line 10.1 can exist, for example, in the event of an unexpected pressure drop or if no pressure buildup or no sufficient pressure buildup can be established in the trailer supply line 10.1 after the startup of the motor vehicle and with coupled-on trailer.

(40) Faulty pressure change behavior in the trailer control line can exist if a brake pulse, which is also applied in particular at an input 7a of the second switching valve 7, is not detectable in the trailer control line 10.2.

(41) A slowly dropping air pressure in the trailer control line 10.2 can also indicate a leak and/or a faulty pressure change behavior, upon which the control unit 3 can initiate corresponding countermeasures and/or protective measures.

(42) In these terms, the electrical connection of the electronic control unit 3 to the components of the braking device 1 and/or the motor vehicle is necessary, so that the control unit 3 can compare data both about, for example, the switching state of the valves and also about the further components to the measurement data of the first and/or second pressure transducer 8.1; 8.2 and can ascertain a faulty pressure change behavior.

(43) According to FIG. 1 furthermore an anti jackknife braking unit 11 is provided in terms of a further input element 4, i.e., as a source of an electrical signal at the control unit 3, and in electrical connection to the control unit 3.

(44) In addition, FIG. 1 shows an inlet valve 11.1 and a vent valve 11.2, which are controllable via the control unit 3, preferably by means of the anti-jackknife braking unit 11.

(45) For this purpose, a control input 11.1c of the inlet valve 11.1 and a control input 11.2c of the vent valve 11.2 are electrically connected to the control unit 3.

(46) The inlet valve 11.1 additionally comprises, as a normally disconnected 2/2-way valve, an input 11.1a and an output 11.1b.

(47) The input 11.1a is supplied with compressed air via the compressed air fitting 2 and further components of the pneumatic circuit.

(48) The output 11.1b of the inlet valve 11.1 is connected or connectable according to FIG. 1 via a double check valve of the tractor protective valve 6 to the input 7a of the second switching valve 7.

(49) In terms of a typical double check valve, the connection between the output 11.1b of the inlet valve 11.1 and the input 7a of the second switching valve 7 can be at least temporarily interrupted or disconnected in dependence on the pressure conditions at the interconnected double check valve.

(50) The vent valve 11.2 comprises, as a spring-loaded, normally open 2/2-way valve according to FIG. 1, an input 11.2a and a venting output 11.2b.

(51) The input 11.2a of the vent valve 11.2 is connected to the output 11.1b of the inlet valve.

(52) The input 11.2a of the vent valve 11.2 is also connected or connectable to the input 7a of the second switching valve 7 via the interconnected double check valve of the tractor protective valve 6.

(53) In that the inlet valve 11.1 and the vent valve 11.2 are controllable via the anti-jackknife braking unit 11 and the control unit 3, aerating or venting of the input 7a of the second switching valve 7 can be set intentionally.

(54) In particular, anti jackknife braking to stabilize the motor vehicle can be activated by means of the anti jackknife braking unit 11 and can be performed in a controlled manner with the aid of the electronic control unit 3 by activation as needed of the inlet valve 11.1 and the vent valve 11.2.

(55) Furthermore, it can be provided that in particular using the inlet valve 11.1 and/or the vent valve 11.2, a test pulse can be applied at the input 7a of the second switching valve 7 to detect a pressure change behavior to be expected in the trailer control line 10.2.

(56) In these terms, an electrification of the braking device 1 is achieved, inter alia, by the control unit 3 according to FIG. 1.

(57) Alternatively, notwithstanding FIG. 1, only the first pressure transducer 8.1 can be provided in the trailer supply line 10.1 or in the trailer control line 10.2. In this case, the second pressure transducer 8.2 is omitted without a replacement.

(58) If the first pressure transducer 8.1 is provided in the trailer supply line 10.1, a pressure change behavior in the trailer supply line 10.1 can be detected and if necessary switching of the switching valve 5 can be initiated via the control unit 3.

(59) If the first pressure transducer 8.1 is provided in the trailer control line 10.2, a pressure change behavior can be detected in the trailer control line 10.2 and in the trailer supply line 10.1.

(60) A faulty pressure change behavior in the trailer supply line 10.1, in particular a slow pressure drop or an inadequate air pressure buildup upon startup, has the effect via the coupling line 12 that second switching valve 7 has a disconnected switching state.

(61) As a result, a faulty pressure change behavior in the trailer control line 10.2 is ascertainable due to the disconnected switched second switching valve 7, for example, upon actuation of the service brake of the trailer, with the aid of the first pressure transducer 8.1 in the trailer control line 10.2.

(62) Very generally, in this manner, preferably automatic monitoring of the braking device of a motor vehicle can be triggered with the aid of at least one input element 4, in particular in the form of an electrical signal, for example, of a sensor, switch, or the like in the context of a launch detection, by means of the electronic control unit 3.

LIST OF REFERENCE SIGNS

(63) 1 braking device 2 compressed air fitting 3 electronic control unit 4 input element 5 switching valve 5a input of the switching valve 5b output of the switching valve 5c control input of the switching valve 5d venting output of the switching valve 6 tractor protective valve 7 second switching valve 7a input of the second switching valve 7b output of the second switching valve 7c control input of the second switching valve 8.1 first pressure transducer 8.2 second pressure transducer 9.1 first trailer coupling unit 9.2 second trailer coupling unit 10.1 trailer supply line 10.2 trailer control line 11 anti-jackknife braking unit 11.1 inlet valve 11.1a input of the inlet valve 11.1b output of the inlet valve 11.2 vent valve 11.2a input of the vent valve 11.2b output of the vent valve 12 double check valve 13 coupling line