DE102019134843A1 - Control air system for a hydrodynamic retarder - Google Patents

Abstract

A control air system is proposed for providing compressed air with an adjustable air pressure in an air space, which is preferably suitable for controlling the braking torque of a hydrodynamic retarder. The basic structure of the control air system comprises: - a control connection via which the air space can be filled with compressed air to provide a control air pressure, - a compressed air supply line into which an electrically actuatable inlet valve is connected to supply compressed air to the air space, - a vent line into which an electrically actuated vent valve is connected to discharge compressed air from the air space; - a sensor for at least indirect detection or calculation of the pressure between the inlet valve and the outlet valve; as well as a control device which is set up to control or regulate the control air pressure in the air space. According to the invention, it is proposed that a switching device is connected upstream of the inlet valve in the compressed air supply line in the direction of flow of the compressed air, which interrupts the compressed air supply line to a compressed air connection when not actuated.

Description

The invention relates to a control air system, MRCU, for providing compressed air with an adjustable air pressure in an air space, preferably for controlling the braking torque of a hydrodynamic retarder. The invention also relates to a method for checking the functional state of the control air system.

In a motor vehicle, the compressed air supply of the control air system for the hydrodynamic retarder is usually connected to the compressed air system of the motor vehicle, for example the compressed air supply for the brake air system that is used in commercial vehicles to release the brakes.

Variously structured control air systems and methods for regulation, monitoring and function control are known from the StdT. So reveals the DE 199 29 152 A1 for example a control air system with valves for controlling the braking torque of a hydrodynamic retarder.

DE 10 2011 106 522 B3 describes a control air system and a method for controlling a hydrodynamic retarder by means of a control air system. To control the hydrodynamic retarder, an air space is provided which can be filled or emptied with compressed air via the control air system, so that a desired control air pressure is set in the air space. The control air pressure is recorded by means of a sensor which is arranged between an inlet valve and an outlet valve. The functionality of the inlet valve and the outlet valve is determined by predetermined switching sequences solely by means of the control air pressure detected by the sensor.

DE 10 2014 201 750 A1 describes a method for monitoring a supply pressure in a pneumatic or hydraulic pressure system. The supply pressure is made available from a pressure supply. Furthermore, the actual value of the supply pressure is recorded and compared with a target pressure value. If the recorded actual value is less than the setpoint pressure value assigned in the comparison, a warning message is output and / or the printing system or a unit controlled by it is put out of operation. The acquisition and comparison of the actual value of the supply pressure and repetitions can be made dependent on the pressure curve in the pressure source.

The object of the invention is to propose an alternative structure for a control air system with which an extended method for functional diagnosis can be carried out.

The object is achieved according to the invention by a control air system according to claim 1 and a method according to claim 8. Further advantageous features of the embodiment according to the invention can be found in the subclaims.

• - einem Regelanschluss, über den der Luftraum zur Bereitstellung eines Steuerluftdruckes mit Druckluft befüllbar ist,
• - eine Druckluftzuleitung, in welche ein elektrisch betätigbares Einlassventil geschaltet ist, um dem Luftraum Druckluft zuzuführen,
• - eine Entlüftungsleitung in welche ein elektrisch betätigbares Entlüftungsventil geschaltet ist, um Druckluft aus dem Luftraum abzuleiten;
• - einen Sensor, zum wenigstens mittelbaren Erfassen oder Berechnen des Druckes zwischen dem Einlassventil und dem Auslassventil; sowie
• - eine Steuereinrichtung, welche eingerichtet ist, den Steuerluftdruck im Luftraum zu steuern oder zu regeln.

A control air system is proposed for providing compressed air with an adjustable air pressure in an air space, which is preferably suitable for controlling the braking torque of a hydrodynamic retarder. The basic structure of the control air system includes:

• - a control connection via which the air space can be filled with compressed air to provide a control air pressure,
• - a compressed air supply line into which an electrically actuatable inlet valve is connected in order to supply compressed air to the air space,
• - A vent line in which an electrically actuatable vent valve is connected in order to discharge compressed air from the air space;
• - A sensor for at least indirectly detecting or calculating the pressure between the inlet valve and the outlet valve; as
• - A control device which is set up to control or regulate the control air pressure in the air space.

According to the invention, it is proposed that a switching device is connected upstream of the inlet valve in the compressed air supply line in the direction of flow of the compressed air, which switching device interrupts the compressed air supply line to a compressed air connection in the non-actuated state. A switching device within the meaning of the invention means a device by means of which the control system can be connected to a compressed air supply or the compressed air supply can be interrupted, with the switching device not being able to vent the air space. The switching device enables the function of the inlet valve to be checked via a diagnostic cycle.

To enlarge the passage cross-section, two or more separately controllable inlet valves can also be connected in parallel. The function of the inlet valves can be tested individually in a diagnostic cycle.

In a preferred embodiment, the switching device can comprise an electrically actuatable pilot valve and a pneumatically actuatable pilot valve, the pilot valve being switchable via a control line connected to the compressed air connection in which the pilot valve is switched.

Furthermore, the inlet valve, the outlet valve and the pilot valve can be designed as a 2/2-way valve and the pilot valve as a 3/2-way valve.

In addition, in an expanded version, a secondary outlet can be provided between the pilot control valve and the inlet valve, and a secondary line into which a secondary valve is connected can also be connected to the secondary connection. This secondary valve is preferably an electrically controllable 2/2 way valve which can also be switched by means of the control device. The secondary valve can be any external valve. Through the coupling with the control air system, the function of the secondary valve can advantageously also be checked or incorporated into the diagnostic cycle.

• gleichzeitiges schalten der Schaltvorrichtung in der Druckluftzuleitung, von einer Schließstellung in eine Offenstellung, und schalten des Auslassventils in eine Schließstellung, wobei zur Überprüfung des Funktionszustands der Ventile
  • - in einem ersten Schritt das Einlassventil für ein festgelegtes Zeitintervall in die Offenstellung geschaltet wird, so dass der Luftraum über die Druckluftzuleitung und den Regelanschluss mit Druckluft befüllt wird, wobei auf einen Fehler des Einlassventils geschlossen wird, wenn der vom Sensor wenigstens mittelbar erfasste oder berechnet Druck, einen festlegbaren Mindestdruck, innerhalb eines festlegbaren Zeitinterwalls, nicht erreicht;
  • - in einem zweiten Schritt die Schaltvorrichtung in die Schließstellung geschaltet wird, wobei auf einen Fehlerzustand des Einlassventils und/oder der Schaltvorrichtung geschlossen wird, wenn der vom Sensor wenigstens mittelbar erfasste oder berechnet Druck, innerhalb eines festlegbaren Zeitinterwalls, auf einen festlegbaren Druck sinkt, und
  • - in einem dritten Schritt das Auslassventil in die Offenstellung geschaltet wird, wobei auf einen Fehlerzustand des Auslassventils geschlossen wird, wenn der vom Sensor wenigstens mittelbar erfasste oder berechnete Druck, nicht innerhalb eines festlegbaren Zeitinterwalls, auf den Umgebungsdruck sinkt.

Furthermore, a method for controlling a control air system, for providing compressed air with an adjustable air pressure in an air space, preferably for controlling the braking torque of a hydrodynamic retarder, is proposed. The control air system has at least the basic structure described above (according to claim 1), the method for checking the functional state of the inlet valve and outlet valve comprising the following steps:

• simultaneous switching of the switching device in the compressed air supply line, from a closed position to an open position, and switching of the outlet valve to a closed position, for checking the functional state of the valves
  • - In a first step, the inlet valve is switched to the open position for a defined time interval, so that the air space is filled with compressed air via the compressed air supply line and the control connection, with a fault in the inlet valve being deduced if the at least indirectly detected or calculated by the sensor Pressure, a definable minimum pressure, within a definable time interval, not reached;
  • - In a second step, the switching device is switched to the closed position, in which case a fault state of the inlet valve and / or the switching device is inferred if the pressure detected or calculated at least indirectly by the sensor falls to a definable pressure within a definable time interval, and
  • - In a third step, the outlet valve is switched to the open position, a fault condition of the outlet valve being deduced if the pressure detected or calculated at least indirectly by the sensor does not fall to the ambient pressure within a definable time interval.

In an extended version, a secondary outlet can be provided between the pilot valve and the inlet valve, a secondary line being connected to the secondary connection into which a secondary valve is connected, in which, in an intermediate step between the second and third step, to check the functional state of the secondary valve closed switching device, the inlet valve is switched to the open position, it being possible to deduce an error state of the secondary valve if the pressure detected or calculated at least indirectly by the sensor falls below a definable minimum pressure within a definable time interval.

To further check the functional state of the secondary valve, in an intermediate step between the second and third step, with the switching device closed, the inlet valve and the secondary valve can be switched to the open position, with an error state of the secondary valve being deduced if the sensor detected at least indirectly or calculates pressure, within a definable time interval, does not fall below a definable minimum pressure.

The secondary valve is preferably switched via the control device of the control air system, so that the entire diagnostic cycle can take place via the control device.

• 1 Steuerluftsystem mit Nebenventil
• 2 ein möglicher vorteilhafter Diagnosezyklus

On the basis of exemplary embodiments, further advantageous features of the invention are explained with reference to the drawings. The features mentioned can not only be implemented advantageously in the combination shown, but can also be combined individually with one another. The figures show in detail:

• 1 Control air system with secondary valve
• 2 a possible beneficial diagnostic cycle

1 shows a control air system 1 with secondary valve 13th . The control air system 1 or also called MRCU (Mechatronic Retarder Control Module), is required for controlling or regulating the hydrodynamic retarder in a motor vehicle. The retarder is not shown here in its entirety, since the air space is shown for the description of the invention 11 sufficient. The air space is a space in the retarder's oil tank. By filling the airspace 11 at the control outlet A1 is connected, the oil in the tank is pressed into the working space of the retarder so that the Retarder switches from non-braking operation to braking operation. The air space is used to end the braking process 11 vented via the MRCU so that the oil is pumped from the working area back into the tank.

The control air system 1 is via a control system that is only hinted at 12th or CPU controlled or regulated, the electrically switchable valves 3 , 5a , 5b , 6th , 13th and the sensor 8th connected to it or switched through it. There is also a secondary outlet A2 provided to which an external secondary valve 13th is connected that can also be controlled via the control of the MRCU.

The MRCU 1 is as shown here on a compressed air system 2 connected. This can be, for example, the compressed air supply to the service brake system. The connection is made via the switching device, consisting of the electrically operated pilot valve 3 and the pneumatically operated pilot valve 4th . The pilot valve 4th is connected to the compressed air connection via a 2 connected control line 9 in which the pilot valve 3 is switched, switched. The compressed air line 7b, to which the two inlet valves 5a, b and the secondary valve are connected, compressed air is only filled when the pilot valve 3 is switched or controlled so that the pilot valve is actuated by means of the compressed air and switches to the open position. In the non-actuated state, the compressed air supply line is 7a, b to the compressed air connection 2 interrupted.

In the embodiment shown, there are two inlet valves connected in parallel 5a, b provided, which can be controlled separately. In this way, the flow resistance can be regulated in at least two stages. With the inlet valves open 5a, b and closed, actuated outlet valve 5 is the air space 11 filled. According to the desired braking torque of the retarder, the filling takes place up to a desired pressure, which is determined by means of the sensor 8th is measured.

To switch to the non-braking mode, the valves 5a, b and 6th switched to the basic position so that via the outlet valve 6th the airspace 11 is vented.

To ensure the pneumatic functions within the MRCU, a diagnosis must be carried out every time the vehicle is started. This is carried out when the vehicle ignition is switched on with the aim of detecting pneumatic malfunctions on the individual valves of the MRCU when the diagnostic cycle is run through.

The MRCU is also designed to ensure that the at the secondary outlet A2 connected secondary valve 13th can be checked. Recognizing the function of the (external) secondary valve 13th is extremely advantageous to ensure a further function in the overall product retarder.

In the diagnostic cycle described below, as in 2 all pneumatic functions of the switching valves within the MRCU and the external auxiliary valve are shown 13th checked. Individual steps of the diagnostic cycle can be omitted if, for example, there is only one inlet valve 5a, b or if there was no external auxiliary valve.

• Gestartet wird der Diagnosezyklus dadurch, dass die Schaltvorrichtung, also das Pilotventil 3 angesteuert wird, so dass das Vorsteuerventil 4 in der Druckluftzuleitung 7a, b, von einer Schließstellung in eine Offenstellung bewegt wird. Gleichzeitig wird das Auslassventil 6 in eine Schließstellung geschaltet, so dass die Entlüftungsleitung 10a, b verschlossen wird.

The procedure for checking the functional status of the valves comprises the following steps:

• The diagnostic cycle is started by the switching device, i.e. the pilot valve 3 is controlled so that the pilot valve 4th in the compressed air supply line 7a, b , is moved from a closed position to an open position. At the same time the exhaust valve 6th switched to a closed position so that the vent line 10a , b is closed.

In a first step, the two inlet valves 5a, b tested one after the other by switching each of them into the open position for a specified time interval, so that the air space 11 via the compressed air supply line 7a, b and the control connection A1 is filled with compressed air in two stages, eg first to 1 bar and then to 2 bar. The measured pressure on the sensor 8th thus increases in two stages, with a fault in the inlet valve being tested after each pressure increase 5a, b can be closed when the from the sensor 8th at least indirectly recorded or calculated pressure a definable minimum pressure ( 1 bar or 2 bar), not reached within a definable time interval.

In a second step, the switching device 3 , 4th switched to the closed position, with one of the closed inlet valves in a fault condition 5a, b or the switching device 3 , 4th is closed when the sensor 8th at least indirectly detected or calculated pressure drops to a definable pressure within a definable time interval. If there is no pressure drop, the system is tight.

In an intermediate step, this can be done on the auxiliary connection A2 connected secondary valve 13th to be checked. As shown, this is done with the switching device closed 3 , 4th , the inlet valve 5b switched to the open position, with an error state of the secondary valve 13th is closed when the sensor 8th at least indirectly detected or calculated pressure, within a definable time interval, below a definable one Minimum pressure drops. If there is no pressure drop, the system is up to the secondary valve 13th tight.

To further check the function of the secondary valve 13th , becomes the secondary valve 13th with the switching device closed ( 3 , 4th ) and open inlet valve 5b switched to the open position, with a fault in the secondary valve 13th is closed when the sensor 8th at least indirectly detected or calculated pressure, within a definable time interval, does not fall below a definable minimum pressure. By opening the secondary valve, the pressure on the sensor is increased 8th reduced by the flow of compressed air into the ancillary system until the pressure has been equalized. If the pressure at the sensor falls 8th the ancillary system is not tight under a specified pressure.

In a third step, the exhaust valve 6th be switched to the open position, with a fault condition of the exhaust valve 6th is closed when the sensor ( 8th ) at least indirectly detected or calculated pressure does not fall to the ambient pressure within a definable time interval.

If desired, it is also possible to use the exit A2 via the temporary opening of the inlet valves 5a and or 5b and the de-energized open vent valve 6th to vent or depressurize.

In the event of a fault, it is also conceivable that the vent valve 6th the exit A1 via the temporary opening of the secondary valve 13th with the switching device closed 3 , 4th to vent or depressurize

List of reference symbols

1

Control air system

2

Compressed air connection

3

Pilot valve

4th

Pilot valve

5a, b

Inlet valve

6th

Vent valve

7a, b

Compressed air supply

8th

Pressure sensor

9

Control line

10a, b, c

Vent line

11

airspace

12th

Control device

13th

Secondary valve

14th

Secondary line

A1

Control outlet

A2

Secondary outlet

R.

Venting

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19929152 A1 [0003]
• DE 102011106522 B3 [0004]
• DE 102014201750 A1 [0005]

Claims (10)

Control air system (1) for providing compressed air with an adjustable air pressure in an air space (11), preferably for controlling the braking torque of a hydrodynamic retarder, - with a control connection (A1) via which the air space (11) can be filled with compressed air to provide a control air pressure is; - With a compressed air supply line (7a, b, c) into which an electrically actuatable inlet valve (5a, b) is connected in order to supply compressed air to the air space (11); - With a vent line (10a) into which an electrically actuatable vent valve (6) is connected in order to discharge compressed air from the air space (11); - With a sensor (8) for at least indirect detection or calculation of the pressure between the inlet valve (5a, b) and the outlet valve (6); - as well as a control device (12) which is set up to control or regulate the control air pressure in the air space (11), characterized in that a switching device (3 , 4) is connected upstream, which in the non-actuated state interrupts the compressed air supply line (7a, b) to a compressed air connection (2). Control air system (1) Claim 1 characterized in that the switching device (3, 4) comprises an electrically operated pilot valve (3) and a pneumatically operated pilot valve (4), the pilot valve (4) via a control line (9) connected to the compressed air connection (2) in which the pilot valve (3) is switched, is switchable. Control air system (1) Claim 2 characterized in that the inlet valve (5a, b), the outlet valve (6) and the pilot valve (4) are designed as a 2/2-way valve and the pilot valve (3) as a 3/2-way valve. Control air system (1) Claim 1 characterized in that a secondary outlet (A2) is provided between the pilot valve (4) and the inlet valve (5a, b). Control air system (1) Claim 1 characterized in that a secondary line (14), into which a secondary valve (13) is connected, is connected to the secondary connection (A2). Control air system (1) Claim 1 characterized in that the secondary valve (13) is an electrically controllable 2/2 way valve which can be switched by means of the control device (12). Method for controlling a control air system (1), for providing compressed air with an adjustable air pressure in an air space (11), preferably for controlling the braking torque of a hydrodynamic retarder Claim 1 , wherein the method for checking the functional state of inlet valve (5a, b) and outlet valve (6) comprises the following steps: switching the switching device (3, 4) in the compressed air supply line (7a, b) from a closed position to an open position, and at the same time switch the outlet valve (6) into a closed position, whereby to check the functional state of the valves (5a, 5b, 6) - in a first step the inlet valve (5a, b) is switched to the open position for a defined time interval, so that the air space (11) is filled with compressed air via the compressed air supply line (7a, b) and the control connection (A1), in which case a fault in the inlet valve (5a, b) is inferred if the pressure detected or calculated at least indirectly by the sensor (8) is a definable minimum pressure, within a definable time interval, not reached; - In a second step, the switching device (3, 4) is switched to the closed position, a fault state of the inlet valve (5a, b) and / or the switching device (3, 4) being inferred if the sensor (8) is at least indirectly detected or calculated pressure drops to a definable pressure within a definable time interval, and - in a third step, the outlet valve (6) is switched to the open position, whereby an error state of the outlet valve (6) is deduced if the sensor ( 8) at least indirectly detected or calculated pressure does not fall to the ambient pressure within a definable time interval. Procedure according to Claim 7 characterized in that a secondary outlet (A2) is provided between the pilot valve (4) and the inlet valve (5a, b), a secondary line (14) into which a secondary valve (13) is connected is connected to the secondary connection (A2) , wherein to check the function of the secondary valve (13), in an intermediate step between the second and third step, with the switching device (3, 4) closed, the inlet valve (5a, b) is switched to the open position, with an error state of the secondary valve (13) is closed when the pressure detected or calculated at least indirectly by the sensor (8) falls below a definable minimum pressure within a definable time interval. Procedure according to Claim 8 characterized in that for further checking of the functional state of the secondary valve (13), in an intermediate step between the second and third step, with the switching device (3, 4) closed, the inlet valve (5a, b) and the secondary valve (13) be switched into the open position, with a fault in the secondary valve (13) being inferred if the pressure detected or calculated at least indirectly by the sensor (8) does not fall below a definable minimum pressure within a definable time interval. Procedure according to Claim 7 or 8th characterized in that the secondary valve (13) is switched via the control device (12) of the control air system (1).

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