VALVE ASSEMBLY AND METHOD FOR CONTROLLING THE AIR SUSPENSION LEVEL OF A RAIL VEHICLE

Abstract

The disclosure relates to a valve assembly and a method for controlling the air suspension level of a rail vehicle. A system is provided, which is constructionally simple to build and easy to parameterise, for controlling the air suspension level of a rail vehicle. The object of the disclosure is achieved by a valve assembly for controlling the air suspension level of a rail vehicle, comprising a proportional directional valve, a sensor means for continuously detecting a distance variable representing the distance of a carriage body from a chassis or bogie of the rail vehicle, and a digital control device, wherein the control device is designed to be programmable for determining a control deviation based on the actual distance detected by the sensor means and a comparison with a predefinable target distance, and for continuously generating control variables as a linear function of the determined control deviation and the carriage body travelling speed. The object is also achieved by a method for controlling the air suspension level of a rail vehicle with a proportional directional valve, a sensor means for continuously detecting a distance variable representing the distance of the carriage body from a chassis or bogie, and a digital control device, wherein a control deviation is determined by the control device based on a comparison of the actual distances detected by the sensor means with a predefinable target distance, and a control variable is generated continuously as a linear function of the determined control deviation and the carriage body travelling speed.

Claims

1. A valve assembly for controlling the air suspension level of a rail vehicle, comprising a proportional directional valve, a sensor means for continuously detecting a distance variable representing the distance of a carriage body from an undercarriage or bogie of the rail vehicle, and a digital control device, wherein the control device is programmed to determine a control deviation on the basis of the actual distance detected by the sensor means and a comparison with a specifiable desired distance, and to continuously generate correcting variables as a linear function of the determined control deviation and the carriage body traveling speed.

2. The valve assembly as claimed in claim 1, wherein the carriage body traveling acceleration is included as an additional control parameter of the linear function.

3. The valve assembly as claimed in claim 1, wherein the dynamics of the control function can be selected, specified or adjusted by a changed parameterization of individual control parameters or the setting of a modification factor for the control action, the correcting variable or the actual distance.

4. The valve assembly as claimed in claim 1, wherein the dynamics of the control function can be selected, specified or adjusted by intensity—and/or time-related filtering of the actual distance or of the control deviation.

5. The valve assembly as claimed in claim 3, wherein the dynamics of the control functions or the filtering can be selected, specified or adjusted on the basis of the mode of operation or the traveling speed of the rail vehicle.

6. The valve assembly as claimed in claim 1, wherein the proportional directional valve is a 3-way proportional valve which has a venting position and an inflation position, each with continuously variable opening cross sections, and a closed position.

7. The valve assembly as claimed in claim 1, wherein the proportional directional valve or the 3-way proportional valve occupies a venting position in the deenergized state and an electronically controllable switching means is arranged downstream of its venting connection, which switching means occupies a closed position in the deenergized state and an open position in the actuated position.

8. The valve assembly as claimed in claim 1, wherein a working connection of the proportional directional valve or of the 3-way proportional valve is connected via a connecting line to a combined inflation/venting connection of at least one air suspension device and there is arranged with the connecting line a switching means which is actuatable mechanically via a lever and a measuring rod connected to the carriage body and the undercarriage, which switching means occupies a closed position in its rest position and, from a lever position representing a determinable actual distance, switches into an open position, wherein it connects the connecting line to a venting outlet.

9. The valve assembly as claimed in claim 1, wherein the control device is configured with at least one data communication interface which is compatible with at least one industrial protocol standard.

10. The valve assembly as claimed in claim 3, wherein the control device is programmed to parameterize or to select, specify or adjust the dynamics of the control function or of the filtering via the data communication interface.

11. The valve assembly as claimed in claim 9, wherein the proportional directional valve or the 3-way proportional valve is configured with a sensor means for detecting the valve output pressure, and the control device is programmed to determine a definable pressure drop and to generate an error signal and transmit that signal via the data communication interface.

12. A method for controlling the air suspension level of a rail vehicle with a proportional directional valve, a sensor means for continuously detecting a distance variable representing the distance of the carriage body from an undercarriage or bogie, and a digital control device, wherein a control deviation is determined by means of the control device on the basis of a comparison of the actual distances detected by the sensor means with a specifiable desired distance, and a correcting variable is continuously generated as a linear function of the determined control deviation and the carriage body traveling speed.

13. The method as claimed in claim 12, wherein the carriage body traveling acceleration is included as an additional control parameter of the linear function.

14. The method as claimed in claim 12, wherein the dynamics of the control function can be selected, specified or adjusted by a changed parameterization of individual control parameters or the setting of a modification factor for the control action, the correcting variable or the actual distance.

15. The method as claimed in claim 12, wherein the dynamics of the control function can be selected, specified or adjusted by intensity—and/or time-related filtering of the actual distance or of the control deviation.

16. The method as claimed in claim 14, wherein the dynamics of the control functions and/or the filtering can be selected, specified or adjusted on the basis of the mode of operation or the traveling speed of the rail vehicle.

Description

[0026] Further advantages of the invention will be explained in greater detail hereinbelow by means of the figures together with the description of preferred exemplary embodiments of the invention. In the figures:

[0027] FIG. 1 is a schematic rear view of a portion of a rail vehicle having an air suspension and a valve assembly;

[0028] FIG. 2 is a schematic diagram of a valve assembly according to FIG. 1 for controlling the air suspension level of a rail vehicle;

[0029] FIG. 3 FIG. 2 is a diagram with a characteristic field of the control behavior of the valve assembly.

[0030] FIG. 1 shows a portion of a rail vehicle in a schematic rear view. The valve assembly 1 is arranged in the lower region of a carriage body 2. It is mechanically connected to the undercarriage frame 5 via the lever 3 and the measuring rod 4. The undercarriage frame 5 can here also be in the form of a bogie. Between the undercarriage frame 5 and the carriage body 2 there is arranged as secondary suspension an air suspension device, which is formed by the two air suspension bellows 6 and 6′. The current lift h of the secondary suspension 6 is thus identical to the distance of the carriage body 2 from the undercarriage frame 5. Alternatively, the secondary suspension can also be in the form of a single suspension bellows. Beneath the undercarriage frame 5 there is arranged the primary suspension 7, by means of which the wheel axle 8 and the two wheels 9 and 9′ are resiliently mounted relative to the undercarriage 5. The current lift h of the secondary suspension 6 is dependent on the current load of the carriage body 2 and is represented mechanically by the position of the measuring rod 4 and of the lever 3 connected thereto.

[0031] FIG. 2 shows a schematic diagram of the valve assembly 1 with the lever 3 and the measuring rod 4, which is shown only in truncated form in FIG. 2, and the air suspension bellows 6 and 6′. The components of the valve assembly 1 are formed in a common housing—symbolized by a dot-and-dash border. The measuring rod 4 is articulated with this housing via the lever 3. For inflating and venting the two air suspension bellows 6 and 6′, which are arranged outside the housing of the valve assembly 1 and are connected to the valve assembly via the connecting line 10, the 3/3-way proportional valve 11 is arranged in the connecting line 10. The 3/3-way proportional valve 11 is activatable via the proportional solenoid 12 against the spring load of the mechanical return spring 13 and connects the air suspension bellows 6 and 6′ via the connecting line 10, in each case with changeable valve opening cross sections, in a switch position to the compressed air source 14 and in its starting and rest position to the venting outlet 15. The compressed air source 14 can be a compressed air pump, a compressor or, for example, also an interposed compressed air reservoir. The 3/3-way proportional valve 11 can further be switched, via the proportional solenoid 12, into a closed middle position, in which the connecting line 10 is completely closed. In its rest position in the deenergized state, the 3/3-way proportional valve 11 is switched completely into its venting position, in which the connecting line 10 is connected without throttling to the venting outlet 15. The electronic activation of the proportional solenoid 12 takes place via a control device, which is integrated in the form of a microcontroller 16 into the valve assembly 1. The microcontroller 16 is in the form of a single-board computer (SBC), in which all the electronic components necessary for operation (CPU, memory, input and output interfaces, A/D converter, DMA controller, etc.) are combined on a single printed circuit board. The microcontroller 16 receives from the angle sensor 17 a continuous electrical signal, which represents the current distance h of the carriage body 2 from the undercarriage frame 5. The angle sensor 17 is for this purpose connected mechanically to the lever 3 and detects the current actual distance via the position of the lever. The microcontroller 16 is programmed to determine a control deviation e on the basis of the actual distance detected and transmitted by the angle sensor by comparing the actual distance with a specifiable desired distance, and to continuously generate correcting variables u for the actuation of the proportional solenoid 12 of the 3/3-way proportional valve 11 as a linear function of the determined control deviation e and the carriage body traveling speed {dot over (x)} derivable on the basis of the change over time of the actual distance. If the desired distance specified for the running time is constant over time, the carriage body traveling speed is also derivable directly on the basis of the change over time of the determined control deviation e. The carriage body acceleration {umlaut over (x)} derivable on the basis of the change over time of the carriage body traveling speed {dot over (x)} can additionally be taken into account as a further control parameter. Each control parameter can thereby be configured to be parameterizable via coefficients k.sub.1,k.sub.2k.sub.3, so that u=f (k.sub.1e,k.sub.2{dot over (x)},k.sub.3{umlaut over (x)}) applies.

[0032] The valve assembly 1 further comprises the electrically actuatable switching valve 18. The switching valve 18 is switchable via the switching solenoid 19 against the spring load by the mechanical return spring 20 and connects the venting connection 21 of the 3/3-way proportional valve 11 in its switched state to the venting outlet 15 and closes the venting outlet 21 in its deenergized starting and rest position (normal closed=NC). In normal operation, the switching valve 18 is switched open via the microcontroller 16. In the case of a power failure, the switching valve 18 closes automatically and thus prevents venting of the 3/3-way proportional valve 11 and thus also of the system as a whole (consequently also of the air suspension bellows 6 and 6′ and the compressed air source 14, which can also be, for example, an interposed pressure reservoir).

[0033] Finally, the valve assembly 1 comprises the mechanically actuatable shut-off valve 22. This valve is closed in its rest state but switches into an open position by mechanical actuation via the lever 3 from a lever position representing a specific lift h, whereby it connects the connecting line 10 to the venting outlet 15.

[0034] The microcontroller 16 is configured with a data communication interface 23. The data communication interface 23 serves for data connection with a superordinate train control (not shown in FIG. 2) via the data communication line 24. The data communication interface 23 is for this purpose configured, as required, as, for example, a field bus interface (for example compatible with Profibus, DeviceNet/ControlNet or CANopen) or as an industrial Ethernet interface (for example compatible with Profinet, EtherNet/IP, Ethernet Powerlink or EtherCat). It can be configured to be compatible with multiple protocol standards simultaneously. By means of the data communication interface 23, the microcontroller 16 can be integrated into a superordinate train control in that, for example, the parameterization or adjustment of the dynamics of the control function or of the filtering for programming the microcontroller 16 can be selected, specified or adjusted by the superordinate control. Conversely, the microcontroller 16 can also be programmed to report process values to the superordinate train control, for example the actual distance.

[0035] The control behavior of an exemplary linear control function for determining the correcting variable by the correspondingly programmed microcontroller 16 is depicted in FIG. 3 as a characteristic area 25. The characteristic area 25 thereby represents the control space for the correcting variable values u in dependence on determined control deviation values e as the proportional element and carriage body traveling speed values {dot over (x)} (dx) as the differential element of the exemplary linear control function.

LIST OF REFERENCE NUMERALS

[0036] 1 valve assembly

[0037] 2 carriage body

[0038] 3 lever

[0039] 4 measuring rod

[0040] 5 undercarriage frame

[0041] 6, 6′ air suspension bellows

[0042] 7 primary suspension

[0043] 8 wheel axle

[0044] 9, 9′ wheel

[0045] 10 connecting line

[0046] 11 3/3-way proportional valve

[0047] 12 proportional solenoid

[0048] 13, 20 return spring

[0049] 14 compressed air source

[0050] 15 venting outlet

[0051] 16 microcontroller

[0052] 17 angle sensor

[0053] 18 switching valve

[0054] 19 switching solenoid

[0055] 21 venting connection

[0056] 22 shut-off valve

[0057] 23 data communication interface

[0058] 24 data communication line

[0059] 25 characteristic area