ABS (Acrylonitrile Butadiene Styrene) control valve and method for functionally checking such ABS control valve

Abstract

The invention relates to an ABS control valve (4) and to a method for functionally checking such an ABS control valve, having a brake pressure input (32), a brake pressure output (34), an exhaust gas output (36), a pressure-controlled inlet valve (38) and a pressure-controlled outlet valve (44), the inlet valve and the outlet valve each being associated with a 3 / 2 reversing solenoid valve as a pilot valve (40, 46), the pilot valve (40, 46) being connected to the brake pressure input (32), the brake pressure output (34), the exhaust gas output (36) and the pressure-controlled inlet valve (38) and the pressure-controlled outlet valve (44) being connected to the brake pressure output (34). The inlet valve can be closed and the outlet valve can be opened by energizing the pilot valve, the ABS control valve being arranged in a wheel brake line (30) of an electropneumatic brake system (1) of a vehicle between an axle modulator valve (2) and at least one wheel brake cylinder (6) in order to carry out the method, and the ABS control valve being arranged between the axle modulator valve (2) and the at least one wheel brake cylinder (6) in the wheel brake line (30) of the electropneumatic brake system (1) of the vehicle. The pneumatic switching function capability of the ABS control valve is checked by means of the test function. According to the method, the brake pressure pBE is controlled into the wheel brake line (30) by means of the axle modulator valve, and then a brake pressure profile pBE (t) in an input-side section (30a) of the wheel brake line is measured by means of a pressure sensor (26) and stored in an electronic brake control unit (8), at least one switching of the inlet valve or the outlet valve is caused by switching at least one of the pilot valves of the ABS control valve on or off during the measurement of the brake pressure profile, and finally a determination is made on the basis of the brake pressure profile, the input control channel (70, 70a, 70b) or the output control channel (68, 68a) connecting the two pilot valves to one another is open or closed.

Description

Technical Field

[0001] The present invention relates to an ABS control valve and a method for functional testing of the ABS control valve, wherein the ABS control valve has a brake pressure input, a brake pressure output, an exhaust output, a pressure-controlled inlet valve and a pressure-controlled outlet valve, wherein a 3 / 2-way solenoid valve is respectively assigned to the inlet valve and the outlet valve as a pre-control valve, and the inlet valve can be closed and the outlet valve can be opened by energizing the pre-control valve, wherein the ABS control valve is arranged between an axle modulator valve and at least one wheel brake cylinder in a wheel brake circuit of an electropneumatic brake system of a vehicle, and wherein a pneumatic switching function of the ABS control valve can be tested by means of a test function. Background Art

[0002] The use of the method according to the invention therefore presupposes an electropneumatic brake system of a vehicle known per se, in which the wheel brakes of the axles are assigned to different brake circuits. In this case, the brake pressure of the wheel brake cylinders for the front axle and at least one rear axle is controlled via an axle modulator valve in each case to the wheel brake circuits leading to the wheel brake cylinders as a function of a brake value detected by sensors or calculated in a control program as a function of operating parameters of the vehicle. The brake pressures controlled to be introduced are each detected by means of a pressure sensor, which can be arranged inside or outside the respective axle modulator valve. In the wheel brake circuits, an ABS control valve is arranged between the axle modulator valve and the wheel brake cylinder or directly at the axle modulator valve, by means of which the brake pressure of each wheel brake cylinder can be reduced as required, in particular when the associated wheel is locked or has a tendency to lock.

[0003] Such an electropneumatic brake system is known, for example, from DE 10 2017 007 788 A1. In such a brake system, the ABS control valve of the front axle is arranged in each case in the wheel brake circuit between the axle modulator valve and the associated wheel brake cylinder, while the ABS control valve of the rear axle is arranged directly at the axle modulator valve or integrated into the axle modulator valve. DE 2017 007 788 A1 also explains the structure and mode of operation of the axle modulator valve of the front axle with reference to FIG. 3 therein.

[0004] ABS control valves usually have an inlet valve and an outlet valve in order to realize the switching functions "increase brake pressure", "maintain brake pressure" and "reduce brake pressure". In the brake systems of passenger cars and light commercial vehicles, ABS control valves are usually designed as directly controlled solenoid valves, while in the brake systems of heavy commercial vehicles, such as trucks and buses, due to the large wheel brake cylinders installed there, it is preferred to use pre-controlled inlet valves and pre-controlled outlet valves, which are designed as pressure-controlled diaphragm valves or piston valves that can be driven by solenoid valves.

[0005] DE 10 2019 131 128 A1 discloses a typical ABS control valve having a pre-controlled inlet valve and an outlet valve in the form of a diaphragm valve, wherein the inlet valve is controlled by means of a diaphragm valve. Figure 2 The structure and working mode of ABS regulating valve are explained.

[0006] While the axle modulator valve is usually fixed centrally on the vehicle frame near the respective axle to which it is assigned, the ABS control valve, if not integrated into the relevant axle modulator valve or flange-connected to the axle modulator valve, is arranged in or on the corresponding wheel housing near the wheel brake cylinder. This allows for a short flow path of the inflowing and outflowing compressed air for ABS control and thus a fast response behavior of the wheel brake. However, since the ABS control valve is strongly exposed to external influences, such as blown-up dirt or splashing water, in this arrangement, there is a risk that dirt particles and moisture will penetrate into the housing of the ABS control valve from the outside and cause a blockage of the control channel, especially due to corrosion phenomena, especially when the diaphragm seal structure at the exhaust outlet is damaged or embrittled, that is, no longer elastic. However, it is also possible that dirt particles and moisture enter the ABS control valve together with the compressed air supplied by the compressed air preparation device via the relevant axle modulator valve. In order to ensure the driving safety of the relevant vehicle, it is necessary to check the pneumatic switching function of the ABS control valve in its installed state.

[0007] DE 10 2008 022 953 A1 discloses a method for monitoring a solenoid valve of an electrical parking brake, wherein the current profile or voltage profile at the magnetic coil of the solenoid valve is measured during the switching of the solenoid valve and subsequently evaluated. When the solenoid valve is functioning properly, the current or voltage profile that rises during the switching of the solenoid valve has a disturbance that is caused by the self-induction when the valve piston moves, but does not occur when the valve piston is not moving. However, this known method can only check the electromechanical switching function of the solenoid valve.

[0008] DE 10 2016 101 700 A1 describes a method for monitoring a solenoid valve, wherein a test signal is applied to one side of a magnetic coil and a measuring signal is tapped off at the other side of the magnetic coil, and wherein the state of the solenoid valve is determined by comparing the measuring signal with the test signal. In a preferred embodiment of the method, the test signal consists of a specific number of voltage pulses. The state of the solenoid valve is determined by comparing the number of voltage pulses of the measuring signal with the number of voltage pulses of the test signal. However, only the electrical functional capability of the solenoid valve can be checked with this known method. Summary of the invention

[0009] The object of the present invention is to describe a method for functional testing of an ABS control valve of the structure and arrangement described at the outset, by means of which the pneumatic switching functionality of the ABS control valve can be tested. In addition, the present invention also relates to an ABS control valve with which the method can be performed.

[0010] The object relating to the method is achieved by a method having the features of claim 1. The associated dependent method claims describe advantageous developments. The independent device claim defines the features of an ABS control valve that can be used to carry out the method.

[0011] Therefore, the present invention firstly relates to a method for functional testing of an ABS control valve, the ABS control valve having a brake pressure input, a brake pressure output, an exhaust outlet, a pressure-controlled inlet valve and a pressure-controlled outlet valve, wherein a 3 / 2-way solenoid valve is respectively assigned to the inlet valve and the outlet valve as a pilot valve, and the inlet valve can be closed and the outlet valve can be opened by energizing the pilot valve, wherein the ABS control valve is arranged between an axle modulator valve and at least one wheel brake cylinder in a wheel brake circuit of an electropneumatic brake system of a vehicle, and wherein the pneumatic switching functionality of the ABS control valve is checked by means of a test function.

[0012] In order to achieve the stated object, the method provides for the brake pressure p to be adjusted by means of an axle modulator valve. B_E The control is then fed into the wheel brake circuit, whereupon the time profile of the brake pressure p is measured in the input-side section of the wheel brake circuit by means of a pressure sensor. B_E (t) and storing the measured value of the brake pressure variation curve in the electronic brake control unit. B_E During (t), at least one of the pilot valves of the ABS control valve is switched on or off, causing at least one switching of the inlet valve or the outlet valve, and finally using the brake pressure curve p B_E(t) Determine whether the input-end control channel or the output-end control channel connecting the two pilot control valves to each other is open or closed.

[0013] By turning on (i.e., energizing) or off at least one of the two pilot valves of the ABS control valve during the measurement of the brake pressure variation curve, the inlet valve or outlet valve is switched, but the switching is actually only performed when the input control channel is open or the output control channel is open. The inlet valve or the outlet valve is also kept closed, which also only occurs when the input control channel is open or the output control channel is open. Therefore, it can be judged by the brake pressure variation curve whether the input control channel or the output control channel that pneumatically connects the two pilot valves to each other is open or closed.

[0014] According to one embodiment of the method, provision is made for the brake pressure p B_E After the control is introduced into the wheel brake circuit, in the first part of the test function, the inlet valve is closed by switching on the associated first pilot valve, and when the brake pressure p B_E When the brake pressure p B_E When falling, the input control channel is judged to be closed.

[0015] When the input control channel is closed, the brake pressure entering the control chambers of the inlet and outlet valves is not or only strongly delayed and throttled, so that the inlet valve remains open and the outlet valve is opened, which leads to a drop in the brake pressure in the wheel brake circuit.

[0016] The method is only continued if it has been confirmed in the first part of the test function that the input-end control channel is open, wherein in the immediately following second part of the test function it is provided that if it has been confirmed in the first part of the test function that the input-end control channel is open, the second part of the test function is carried out directly thereafter, the second part providing that the outlet valve is opened in a pulsed manner by briefly switching on the associated second pilot valve, subsequently the inlet valve is opened in a pulsed manner by briefly switching off the associated first pilot valve, and the output-end control channel is opened at the brake pressure p B_E The decrease is considered to be opening and the brake pressure p B_E It is considered closed when it remains constant.

[0017] When the output control channel is closed, the ambient pressure does not enter or only enters with a great delay into the control chambers of the inlet valve and the outlet valve during the opening pulse, so that both valves remain closed, which leads to the maintenance of the brake pressure in the section on the input side of the wheel brake circuit.

[0018] Typically, two wheel brake circuits with one ABS control valve each are connected to each axle modulator valve, i.e., a wheel brake circuit with one ABS control valve per vehicle side. In order to clearly distribute the results of the test function, according to another advantageous embodiment of the method, provision is made for the test function to be carried out individually in a defined sequence for each of the ABS control valves in a plurality of ABS control valves connected to the axle modulator valves via one wheel brake circuit each.

[0019] In order to ensure driving safety of the vehicle, it can also be advantageously provided that the current operating state of the vehicle is determined before the test function is executed, and the test function is only executed when the vehicle is in an operating state that is not dangerous to driving safety.

[0020] This can be done, for example, by detecting the current driving speed v by sensors before the test function is carried out. F and the current operating state of the parking brake, and only when the vehicle is parked (v F = 0) and the parking brake is actuated.

[0021] During the execution of the test function, there should also be no actuation of the brake pedal or a braking request from the control program, since this prevents or at least hinders the detection of a closed control channel of the ABS control valve. It is therefore provided that the current operating state of the vehicle system is detected by sensors before the execution of the test function, and the test function is only executed when the vehicle brake system is not actuated.

[0022] According to another embodiment of the method, the test function is preferably carried out each time the vehicle is put into operation.

[0023] However, it can also be provided in addition that the test function is carried out at each driving interruption, the driving interruption occurring after a predetermined driving distance has elapsed or after the driving time of the vehicle has expired since the last carrying out of the test function.

[0024] After carrying out the test function, in order to provide information to the driver, advantageously an acoustic and / or optical signal is output in the driver's seat area, indicating the end of the test function with this signal. In addition, the result of the test function can be displayed in a display of the infotainment system for this reason.

[0025] Furthermore, if a blocked input control channel is detected in the first part of the test function or a blocked output control channel of the ABS control valve is detected in the second part of the test function, an acoustic and / or visual warning signal should be output in the area of ​​the driver's seat.

[0026] It can also be advantageously provided that, when it is confirmed in the first part of the test function that the input-end control channel of the ABS control valve is closed or when it is confirmed in the second part of the test function that the output-end control channel of the ABS control valve is closed, a fault message is stored in the fault memory of the brake control unit and a request to drive to a repair station is displayed on the display of the infotainment system.

[0027] In order to solve the task related to the device, an ABS control valve is proposed, which has a brake pressure input end, a brake pressure output end, an exhaust output end, a pressure-controlled inlet valve and a pressure-controlled outlet valve, wherein the inlet valve and the outlet valve are respectively equipped with a 3 / 2-way solenoid valve as a pre-control valve, and the inlet valve can be closed and the outlet valve can be opened by energizing the pre-control valve. In this ABS control valve, according to the present invention, the two pre-control valves are pneumatically connected to each other through an input control channel and an output control channel. As mentioned above, it is possible to check whether this ABS control valve can operate normally by using the method explained above. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be explained in more detail below with reference to the embodiments shown in the accompanying drawings.

[0029] Figure 1 The schematic diagram shows a section of an electropneumatic brake system having an axle modulator valve, an ABS control valve, wheel brake cylinders and an electronic brake control unit; and

[0030] Figure 2 The enlarged view shows Figure 1 ABS regulating valve. DETAILED DESCRIPTION

[0031] exist Figure 1 The part of an electropneumatic brake system 1 of a vehicle shown in illustrative figures comprises an axle modulator valve 2 assigned to an axle, ABS control valves 4 assigned to the wheels of this axle, wheel brake cylinders 6 and an electronic brake control unit 8 .

[0032] The simplified axle modulator valve 2 has a reserve input 10, a brake control input 12, a brake pressure output 14 and a venting output 16. A reserve line 18 is connected to the reserve pressure input 10, in which a pneumatic reserve pressure p V The brake control line 20 is connected to the brake control input 12, in which a brake control pressure p is applied when the service brake system 1 of the vehicle is actuated. B_S .

[0033] The axle modulator valve 2 comprises at least two Figure 1The electromagnetic valves are connected to the brake control unit 8 via electrical control lines 22, 24. The electromagnetic valves can be directly controlled inlet valves and outlet valves or pre-control valves for the inlet valves and outlet valves. The axle modulator valve 2 can be used in normal operation according to the electronic brake value and in the case of redundancy, that is, in the event of failure of the electronic control according to the brake control pressure p B_S Control the brake pressure p B_E , the brake pressure is applied at the brake pressure output terminal 14. This brake pressure p B_E The detection is carried out with the aid of a pressure sensor 26 , which is arranged in the present case, for example, in the axle modulator valve 2 and is connected to the brake control unit 8 via an electrical sensor line 28 .

[0034] The wheel brake line 30 is connected to the brake pressure output 14 of the axle modulator valve 2 and is led to the wheel brake cylinder 6 of the relevant axle. The ABS control valve 4 is arranged in the wheel brake line 30 between the axle modulator valve 2 and the wheel brake cylinder 6. The ABS control valve 4 has a brake pressure input 32, a brake pressure output 34 and an exhaust outlet 36. The brake pressure p is applied to the brake pressure input 32 which is connected to the brake pressure output 14 of the axle modulator valve 2 via the input-side section 30a of the wheel brake line 30. B_E The output brake pressure p is applied to the brake pressure output 34 connected to the wheel brake cylinder 6 via the output-side section 30b of the wheel brake line 30. B_A , which can deviate from the input brake pressure p depending on the operating state of the ABS control valve 4 B_E The ABS control valve 4 has a pressure-controlled inlet valve 38 and a pressure-controlled outlet valve 44, to which a first pilot valve 40 or a second pilot valve 46 is respectively assigned. The two pilot valves 40, 46 are configured as 3 / 2-way solenoid valves, which are connected to the brake control unit 8 via an electrical control line 42, 48, respectively.

[0035] Next, with the help of Figure 2 The enlarged view of the ABS control valve 4 in the figure explains the structure and working mode of the ABS control valve 4 in more detail.

[0036] The ABS control valve 4 has an input channel 50 leading from the brake pressure input end 32 to the inlet valve 38, an output channel 52 leading from the inlet valve 38 to the brake pressure output end 34, a side channel 54 branching from the output channel 52 and leading to the outlet valve 44, and a discharge chamber 56 leading from the outlet valve 44 to the exhaust outlet end 36. The output channel 52 can be alternately connected to the input channel 50 via the inlet valve 38 or can be blocked relative to this input channel depending on the switching position of the inlet valve 38. The side channel 54 can be alternately connected to the discharge chamber 56 via the outlet valve 44 or can be blocked relative to this discharge chamber depending on the switching position of the outlet valve 44.

[0037] The inlet valve 38 is configured as a diaphragm valve and includes a valve seat 58, a diaphragm 60, a valve spring 62 and a first control chamber 64. When the brake pressure input end 32 is pressure-free, the diaphragm 60 is pressed toward the valve seat 58 by the valve spring 62, so that the inlet valve 38 is as shown in FIG. Figure 2 The first control chamber 64 of the inlet valve 38 can be alternately closed via the associated first pilot valve 40 with the ambient pressure p applied at the exhaust gas outlet 36. U Or with the input brake pressure p applied to the brake control input 32 B_E Loading. For this purpose, the control channels 66, 66a leading to the control chamber 64 of the inlet valve 38 are connected to the discharge chamber 56 via the output control channels 68, 68a when the first pilot valve 40 is closed, that is, not energized. This results in the opening of the inlet valve 38 when pressure is introduced to the brake pressure input end 32. When the first pilot valve 40 is connected, that is, energized, the control channels 66, 66a are connected to the input channel 50 via the input control channels 70, 70a, which results in the closing of the inlet valve 37 by means of the valve spring 62.

[0038] The outlet valve 44 is also configured as a diaphragm valve and includes a valve seat 72, a diaphragm 74, a valve spring 76, and a second control chamber 78. When the brake pressure input end 32 is pressure-free and the brake pressure output end 34 is pressure-free, the diaphragm 74 is pressed toward the valve seat 72 by the valve spring 76, so that the outlet valve 44 is as shown in FIG. Figure 2 The control chamber 78 of the outlet valve 44 can be alternately filled with the input brake pressure p applied to the brake control input 32 via the associated second pilot valve 46. B_E Or the ambient pressure p applied at the exhaust gas outlet 36 UTo this end, when the second pilot valve 46 is closed, i.e., not energized, the control channel 80 leading to the control chamber 78 of the outlet valve 44 is connected to the input channel 50 via the input control channel 70, 70b, which results in the closure of the outlet valve 44 when pressure is introduced into the brake pressure input end 32. Conversely, when the second pilot valve 46 is connected, i.e., energized, the control channel 80 is connected to the discharge chamber 56 via the output control channel 68, which results in the opening of the outlet valve 44.

[0039] Therefore, when the pilot valves 40 and 46 are not energized, the inlet valve 38 is opened and the outlet valve 44 is closed, which corresponds to the switching function of the ABS control valve 4, "increase brake pressure". When the first pilot valve 40 is energized and the second pilot valve 46 is not energized, the inlet valve 38 and the outlet valve 44 are closed, which corresponds to the switching function of the ABS control valve 4, "maintain brake pressure". When the pilot valves 40 and 46 are energized, the inlet valve 38 is closed and the outlet valve 44 is opened, which corresponds to the switching function of the ABS control valve 4, "reduce brake pressure".

[0040] In such an ABS control valve 4, dirt particles and moisture can enter the input channel 50 together with the compressed air flowing in via the brake pressure input end 32, which may lead to a blockage of the input control channels 70, 70a, 70b due to corrosion phenomena. In particular, when arranged in or at the wheel housing of the axle, the ABS control valve 4 is strongly exposed to external influences, such as the influence of blown-up dirt or splashing water. Therefore, when the diaphragm seal structure 82 at the exhaust outlet 36 is damaged or embrittled, that is, no longer elastic, the main danger is that dirt particles and moisture penetrate into the exhaust chamber 80 from the outside, which may lead to a blockage of the output control channels 68, 68a, especially due to corrosion phenomena. When the input control channels 68, 68a and / or the output control channels 70, 70a, 70b are blocked, the switching function of the inlet valve 38 and / or the outlet valve 44 is no longer obtained or at least strongly limited.

[0041] Therefore, the method according to the invention for functional testing of the ABS control valve 4 provides for testing the pneumatic switching function of the ABS control valve 4 by executing a test function. For this purpose, it is usually provided that the brake pressure p B_E The control is then carried out into the wheel brake circuits 30, 30a, and the brake pressure time curve p in the input-side section 30a of the wheel brake circuit 30 is then measured and stored electronically by means of the pressure sensor 26 arranged in the axle modulator valve 2. B_E (t), by detecting the brake pressure change curve p B_EDuring (t), at least one of the two pilot valves 40, 46 of the ABS control valve 4 is switched on or off, causing at least one switching of the inlet valve 38 or the outlet valve 44, and finally the brake pressure time curve p B_E (t) Determine whether the input-side control passages 70 , 70 a , 70 b or the output-side control passages 68 , 68 a of the two pilot control valves 40 , 46 are open or closed.

[0042] In a preferred embodiment of the method, provision is made specifically for the brake pressure p B_E After control has been introduced into the wheel brake circuits 30, 30a, inlet valve 38 is closed in a first part of the test function by switching on the associated first pilot valve 40 and when the brake pressure p B_E Then, when the brake pressure p is kept at least as constant as possible, it is determined that the input control channel 70, 70a, 70b is open and when the brake pressure p B_E When the input control channels 70, 70a, 70b are closed, the control input brake pressure p B_E There is no or only a strongly delayed and throttled entry into the two control chambers 64 , 78 of the inlet valve 38 and the outlet valve 44 , so that the inlet valve 38 remains open and the outlet valve 44 is opened, which results in a brake pressure p in the wheel brake circuits 30 , 30 a , 30 b . B_E of decline.

[0043] If it is confirmed in the first part of the test function that the input control channels 70, 70a, 70b are open, the second part of the test function is carried out directly thereafter. This second part of the test function provides that the outlet valve 44 is opened in a pulsed manner by briefly switching on the associated second pilot valve 46, then the inlet valve 38 is opened in a pulsed manner by briefly closing the associated first pilot valve 40, and the output control channels 68, 68a are opened at the brake pressure p B_E is considered open when the brake pressure p B_E It is considered closed when held.

[0044] When the output control channels 68, 68a are closed, the ambient pressure p U During the opening pulse, there is no or only a greatly delayed entry into control chamber 64 of inlet valve 38 and control chamber 78 of outlet valve 44, so that both valves 38, 44 remain closed, which results in a brake pressure p in inlet-side section 30a of wheel brake circuit 30. B_E remains constant.

[0045] List of reference numerals (part of the description)

[0046] 1Electro-pneumatic brake equipment

[0047] 2 Axle modulator valve

[0048] 4ABS regulating valve

[0049] 6 wheel brake cylinders

[0050] 8Electronic brake control unit

[0051] 10 Reserve pressure input

[0052] 12 Brake control input terminal

[0053] 14 Brake pressure output terminal

[0054] 16 Exhaust output port

[0055] 18 Reserve Lines

[0056] 20 Brake control circuit

[0057] 22 control lines

[0058] 24 control lines

[0059] 26 Pressure Sensor

[0060] 28 sensor lines

[0061] 30 wheel brake lines

[0062] 30a Wheel brake circuit, input-side section

[0063] 30b Wheel brake circuit, output-side section

[0064] 32 Brake pressure input terminal

[0065] 34 Brake pressure output terminal

[0066] 36 Exhaust output

[0067] 38 Inlet valve, diaphragm valve

[0068] 40 first pilot valve, 3 / 2 reversing solenoid valve

[0069] 42 control lines

[0070] 44 outlet valve, diaphragm valve,

[0071] 46 Second pilot valve, 3 / 2 reversing solenoid valve

[0072] 48 control lines

[0073] 50 input channels

[0074] 52 output channels

[0075] 54 Side Channel

[0076] 56 Exhaust Chamber

[0077] 58 Inlet valve seat

[0078] 60 Diaphragm for inlet valve

[0079] 62 Valve spring of inlet valve

[0080] 64 first control chamber

[0081] 66, 66a control channel

[0082] 68, 68a output control channel

[0083] 70, 70a, 70b input control channel

[0084] 72 Valve seat of outlet valve

[0085] 74 Diaphragm of outlet valve

[0086] 76 Valve spring of outlet valve

[0087] 78 Second control chamber

[0088] 80 control channels

[0089] 82 diaphragm seal structure

[0090] ABS Anti-lock Braking System

[0091] p B_A Braking pressure, output brake pressure

[0092] p B_E Brake pressure, input brake pressure

[0093] p B_S Brake control pressure

[0094] P U Ambient pressure

[0095] p V Reserve Pressure

[0096] t time

[0097] v F Travel speed

Claims

1. Method for functional testing of the ABS control valve (4), The ABS regulating valve comprises a brake pressure input end (32), a brake pressure output end (34), an exhaust gas output end (36), a pressure-controlled inlet valve (38) and a pressure-controlled outlet valve (44). in, The inlet valve (38) and the outlet valve (44) are respectively provided with 3 / 2-way solenoid valves as pre-control valves (40, 46). By energizing the pilot valve, the inlet valve (38) can be closed and the outlet valve (44) can be opened. The ABS control valve (4) is arranged in a wheel brake circuit (30) of an electropneumatic brake system (1) of a vehicle between an axle modulator valve (2) and at least one wheel brake cylinder (6), and wherein the pneumatic switching capability of the ABS control valve (4) is checked by means of a test function, It is characterized in that The brake pressure (p B_E ) controls the entry into the wheel brake circuit (30, 30a), The time profile (p ) of the brake pressure in an input-side section (30a) of the wheel brake circuit (30) is then measured using a pressure sensor (26). B_E (t)) and storing it in the electronic brake control unit (8), By measuring the brake pressure variation curve (p B_E (t)), switching on or off at least one of the pilot valves (40, 46) of the ABS control valve (4) causes at least one switching of the inlet valve (38) or the outlet valve (44), And finally with the aid of the brake pressure variation curve (p B_E (t)) determines whether the input-side control channel (70, 70a, 70b) or the output-side control channel (68, 68a) connecting the two pilot valves (40, 46) to each other is open or closed.

2. The method according to claim 1, characterized in that When the brake pressure (p B_E ) after the control enters the wheel brake circuit (30, 30a), in a first part of the test function, the inlet valve (38) is closed by switching on the associated first pilot valve (40), The input control channel (70, 70a, 70b) is controlled at the braking pressure (p B_E ) remains constant and is considered to be open and at the brake pressure (p B_E ) is considered closed when descending.

3. The method according to claim 2, characterized in that When it is confirmed in the first part of the test function that the input control channel (70, 70a, 70b) is open, Directly thereafter, a second part of the test function is executed, which provides that the outlet valve (44) is opened in a pulsed manner by briefly switching on an associated second pilot valve (46). The inlet valve (38) is then opened in a pulsed manner by briefly closing the associated second pilot valve (40). The output control channel (68, 68a) is controlled at the braking pressure (p B_E ) decreases and is judged to be open and B_E ) remains constant and is considered closed.

4. The method according to any one of claims 1 to 3, characterized in that The test function is carried out in a fixed sequence for each of the ABS control valves (4) individually for a plurality of ABS control valves (4) connected to the axle modulator valve (2) via the respective wheel brake lines (30).

5. The method according to any one of claims 1 to 4, characterized in that Before executing the test function, the current running state of the vehicle is known. Furthermore, the test function is only carried out when the vehicle is in an operating state that is not hazardous to driving safety.

6. The method according to claim 5, characterized in that Before executing the test function, the current driving speed (v F ) and the current operating status of the parking brake, And only when the vehicle stops (v F = 0) and the parking brake is actuated.

7. The method according to any one of claims 1 to 6, characterized in that Before carrying out the test function, the current operating state of the service brake system (1) is detected by means of sensors. The test function is then only carried out when the service brake system (1) is not actuated.

8. The method according to any one of claims 1 to 7, characterized in that The test function is carried out each time the vehicle is put into operation.

9. The method according to any one of claims 1 to 8, characterized in that The test function is executed at each driving interruption, which occurs after a predetermined mileage or driving time of the vehicle has elapsed since the last execution of the test function.

10. The method according to any one of claims 1 to 9, characterized in that After the test function has been carried out, an acoustic and / or optical signal is output in the driver's seat area, which signal indicates the end of the test function. The result of the test function is displayed on a display of the infotainment system.

11. The method according to any one of claims 1 to 10, characterized in that When it is confirmed in the first part of the test function that the input control channel (70, 70a, 70b) is closed or in the second part of the test function that the output control channel (68, 68a) is closed, an acoustic and / or visual warning signal is output in the area of ​​the driver's seat.

12. The method according to any one of claims 1 to 11, characterized in that If it is confirmed in the first part of the test function that the input control channel is closed or in the second part of the test function that the output control channel is closed, a fault message is stored in a fault memory of the brake control unit (8) and a request to drive to a repair station is displayed on a display of the infotainment system. 13.ABS regulating valve (4), It has a brake pressure input end (32), a brake pressure output end (34), an exhaust gas output end (36), a pressure-controlled inlet valve (38) and a pressure-controlled outlet valve (44), in, The inlet valve (38) and the outlet valve (44) are respectively provided with 3 / 2-way solenoid valves as pre-control valves (40, 46). By energizing the pilot valve, the inlet valve (38) can be closed and the outlet valve (44) can be opened. It is characterized in that The two pilot control valves (40, 46) are pneumatically connected to one another via an input control channel (70, 70a, 70b) and an output control channel (68, 68a).

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