METHOD OF CONTROLLING A HYDRAULIC ACTUATOR DRIVE, CONTROLLER AND ACTUATOR DRIVE CONTROLLER

Abstract

A method controls a hydraulic actuator drive that has an actuator and the position of the actuator is set by at least one electrohydraulic proportional valve that has at least one electrical input and at least one hydraulic output. First, the position of the actuator is detected and an actual position value is generated therefrom. Second, a target position value is specified in dependence on a default for a desired position of the actuator and a target/actual value difference is corrected by the at least one electrohydraulic proportional valve, so that the actuator assumes a position corresponding to the target position value. The method is characterized in that the target position value is also varied if the default remains unchanged for a desired position of the actuator.

Claims

1-20. (canceled)

21. A method of controlling a hydraulic actuator drive (1) with an actuator and a position of the actuator is set by at least one electrohydraulic proportional valve having at least one electrical input and at least one hydraulic output, which method comprises the following steps of: detecting the position of the actuator and an actual position value is generated therefrom; specifying a target position value in dependence on a default for a desired position of the actuator; controlling a difference between the target position value and the actual position value via the at least one electrohydraulic proportional valve so that the actuator assumes a position that corresponds to the target position value; and varying the target position value even when the default for the desired position of the actuator is not changed.

22. The method according to claim 21, wherein: the hydraulic actuator drive has at least two electrohydraulic proportional valves that respectively each have the at least one electrical input and the at least one hydraulic output, and the hydraulic output of each of the two electrohydraulic proportional valves are connected together for actuating the actuator drive with a shared hydraulic input pressure; and during manipulation of the target position value supplied to one of the electrohydraulic proportional valves, in order to keep the shared hydraulic input pressure for the hydraulic actuator drive constant, a pressure change in the hydraulic output of the one electrohydraulic proportional valve is compensated by a change in a pressure at the hydraulic output of the at least one other of the electrohydraulic proportional valves.

23. The method according to claim 21, wherein a target position value variation takes a form of a regular or irregular oscillation superimposition on the target position value specified in dependence on the default for the desired position of the actuator.

24. The method according to claim 21, wherein a variation of the target position value takes place in a form of discrete magnifications and/or reductions of the target position value which is predetermined in dependence on the default for the desired position of the actuator.

25. The method according to claim 22, wherein in addition to a target value variation, the function of the electrohydraulic proportional valves and in particular of additional components used for controlling are tested by successively selectively reducing target values supplied to the electrohydraulic proportional valves and monitoring whether the pressure in the hydraulic output changes accordingly.

26. The method according to claim 25, wherein in a test a pressure reduction in one said hydraulic output is compensated by a set pressure increase in another said hydraulic output in order to keep constant the shared hydraulic input pressure for the hydraulic actuator drive.

27. The method according to claim 22, which further comprises equalizing pressures in the hydraulic outputs with each other again after a compensation by changing the pressure in the other hydraulic output.

28. The method according to claim 26, wherein a variation of the target position value and/or the test may be switched off.

29. The method according to claim 21, which further comprises detecting the position of the actuator with at least two position sensing devices and a 1-of-2, 1-of-3 or 2-of-3 selection is made from actual position values that the position sensing devices generate, wherein a selected actual position value is used for regulation.

30. A controller for controlling at least one electrohydraulic proportional valve for controlling a hydraulic actuator drive having an actuator, the controller comprising: inputs and outputs for at least one actual position value and a target position value of a position of the actuator; said controller configured to: detect the position of the actuator and the actual position value is generated therefrom; specify the target position value in dependence on a default for a desired position of the actuator; control a difference between the target position value and the actual position value by the at least one electrohydraulic proportional valve so that the actuator assumes a position that corresponds to the target position value; and vary the target position value even when the default for the desired position of the actuator is not changed.

31. An actuator drive controller for controlling a hydraulic actuator drive having an actuator, the actuator drive controller comprising: a shared hydraulic pressure selection device; at least two redundantly disposed electrohydraulic proportional valves for generating a hydraulic input pressure for the hydraulic actuator drive, each of said electrohydraulic proportional valves having at least one electrical input and at least one hydraulic output, hydraulic outputs of said at least two electrohydraulic proportional valves are interconnected via said shared hydraulic pressure selection device for actuating the hydraulic actuator drive with a shared input pressure; a target position value input for each of said electrxohydraulic proportional valves and each said target position value input connected to said electrical input of a respective one of said electrohydraulic proportional valves; at least one position sensing device for sensing a position of said actuator of the hydraulic actuator drive, said position sensing device generating an actual position value; and each of said electrohydraulic proportional valves having a position controller configured with a target position value from said target position value input and the actual position value from said position sensing device, for controlling a difference between the target position value and the actual position value; at least one electronic switching device with which at least one said target position value from said target position value input, and/or the actual position value from said position sensing device, may optionally be replaced by a default value.

32. The actuator drive controller according to claim 31, wherein said electronic switching device is one of a plurality of electronic switching devices that may be switched individually to replace the target position value or the actual position value.

33. The actuator drive controller according to claim 32, wherein said at least one position sensing device is one of at least two position sensing devices respectively furnished for generating in each case the actual position value in dependence on the position of the actuator.

34. The actuator drive controller according to claim 33, wherein: said at least two position sensing devices are connected to at least two of said electronic switching devices in such a way that a first actual position value of a first switching device of said electronic switching devices is fed back, a second actual position value of a second switching device of said electronic switching devices is fed back and a third actual position value is fed back, as a reserve actual position value in case at least one of the two other actual position values fails; or a 1-of-2, 1-of-3 or 2-of-3 selection is made from among the actual position values of said at least two position sensing devices, and a selected actual position value or selected actual position values are fed back to said first and second switching devices.

35. The actuator drive controller according to claim 32, wherein: said electrohydraulic proportional valves each have a position controller; four of said electronic switching devices are furnished; a first two of said electronic switching devices are respectively interconnected with one said target position value input and said position controller of a respective said electrohydraulic proportional valve; said first two of said electronic switching devices also respectively have a default value input; and a second two of said electronic switching devices are respectively connected to said position controller of a respective said electrohydraulic proportional valve and a respective said position sensing device, and also respectively have a default value input.

36. The actuator drive controller according to claim 31, wherein said at least one electronic switching device has a switching input via which said electronic switching device is switched by applying a signal to replace the actual position value or the target position value with a default value.

37. The actuator drive controller according to claim 31, wherein said pressure selection device is a maximum pressure selection device.

38. A valve control apparatus, comprising: a hydraulic actuator drive having an actuator and an actuator drive controller according to claim 31.

39. The valve control apparatus according to claim 38, wherein said hydraulic actuator drive has a pressure chamber that is connected to said shared hydraulic pressure selection device for applying a hydraulic pressure to said pressure chamber in dependence on the position of said two electrohydraulic proportional valves.

40. The valve control apparatus according to claim 39, wherein said actuator has a preload spring and is operable with the hydraulic pressure in said pressure chamber against a force of said preload spring.

Description

[0053] The invention will be described below through examples, with reference to an exemplary embodiment and FIG. 2.

[0054] In FIG. 2, corresponding components that have already been shown in FIG. 1, are marked with the same reference signs. In detail, an actuator drive 1 with an actuator 1.1 is shown that actuates a valve 28 of an engine or driven machine, in particular in the mass flow supply thereof. The drawing shows, by way of example, a steam turbine 29 that is supplied with live steam, the mass flow of which is adjusted by means of the valve 28. The steam turbine 29, for example, drives a compressor or electric generator. In particular, a rapid shut-off valve 31 may be connected upstream of the valve 28. A different engine or driven machine could however be furnished, in place of the steam turbine 29.

[0055] The way valve module has two electrohydraulic proportional valves 2, 3, which are referred to below as way valves due to their configuration in the present exemplary embodiment, and which convert an electrical signal or a current or voltage into a hydraulic pressure that is supplied to a pressure chamber 1.2 of the actuator drive 1 in order to extend the actuator 1.1 more or less against the force of a preload spring 1.3. The respective way valves 2 and 3 each have an electrical input 4 and 5 and hydraulic output 6 and 7 for this purpose. The hydraulic outputs 6, 7 are connected to the pressure selection device 8, which in turn supplies the pressure chamber 1.2 with a shared input pressure as a function of the hydraulic pressure at the hydraulic outputs 6, 7.

[0056] Although the invention is illustrated herein with reference to an actuator drive controller with two way valves, other electrohydraulic proportional valves 2, 3 may be furnished instead of the way valves. In addition, a controller according to the invention may also be used to control a hydraulic actuator drive in which only one electrohydraulic proportional valve is furnished.

[0057] The way valve module has a target position value 9, 10 for each way valve 2, 3, which is connected to the electrical input 4, 5 of the respective way valve 2, 3. In the connection, a position controller 14, 15 is provided for each way valve 2, 3, and an actual position value is fed to that controller in addition to a target position value. Unless replaced by a default value, the actual position value is derived from one of the position sensing devices 11, 12, that detects the position of actuator 1.1 of the actuator drive and generates an appropriate actual position value. A third position sensing device 13 is additionally furnished, that likewise generates an actual position value as a function of the position of the actuator 1.1 of the actuator drive and returns that value for further processing by a logic of the way valve module. According to another embodiment, the actual position values of all three position sensing devices 11, 12, 13 are first processed in such a way that one of these actual position values or also an average value of the actual position values is selected as suitable, in particular in the logic of the way valve module, and is fed to all position controllers 14, 15.

[0058] In addition to this actual position value of the third position sensing device 13, the measured hydraulic pressure from each hydraulic output 6, 7 of the two way valves 2, 3 may for example also be fed to the logic, as shown in FIG. 2. The values supplied to the logic may be analog values or, according to another embodiment, digital values.

[0059] Four electronic switching devices 16, 17, 18, 19 are furnished. The first electronic switching device 16 has an actual position value input 32 for the actual position value of the first position sensing device 11, and also a default value input 22 and an actual position value output 34. The actual position value output 34 is connected to the position controller 14 of the first way valve 2. As shown, alternatively a 1-of-2 selection or a 1-of-3 or 2-of-3 selection of the actual position values of all position sensing devices 11, 12, 13 is made, and the selected actual position value(s) are fed to the first electronic switching device 16.

[0060] The second electronic switching device 17 has an actual position value input 33 to which the actual position value from the second position sensing device 12 is applied, and which is correspondingly connected to the second position sensing device 12. The second switching device 17 additionally has a default value input 23 and an actual position value output 35. The actual position value output 35 is connected to the position controller 15 of the second way valve 3. The same applies here to the 1-of-2 selection and to the 1-of-3 or 2-of-3 selection of the first way valve 2.

[0061] The third electronic switching device 18 is connected on the input side to the target position value input 9 and on the output side to the position controller 14 of the first way valve 2. It also has a default value input 20. As long as no malfunction is detected, the default value input 20 is connected to the position controller 14 in order to use a varied target position value, instead of the target position value present at the target value input 9, to control the first way valve 2. Only when a malfunction is detected, the target position value input 9 is directly connected to the output of the third electronic switching device 18 and supplied to the first way valve 2 as a target value.

[0062] The fourth electronic switching device 19 also has a default value input 21 and is connected to the target position value input 10 on the input side, and to the position controller 15 of the second way valve 3 on the output side. Here too, as long as no malfunction has been detected, the default value from the default value input is fed to the position controller 15 of the second way valve 3. In the event of an error, however, the target value of the target position value input 10 is fed to position controller 15 of the second way valve 3.

[0063] The functionality described for the third and fourth electronic switching devices 18, 19 is also applicable for the first and/or second electronic switching device 16, 17, namely that as long as no malfunction is detected, the default value input is connected to the output, and if a malfunction is detected, the target position value input is connected to the output. Here either the actual position value input 32, 33 (malfunction detected) or the default value input 22, 23 (no malfunction detected) is connected to the actual position value output 34, 35.

[0064] An external 1-of-2, 1-of-3 or 2-of-3 selection of target values may also be envisioned.

[0065] Each switching device 16, 17, 18, 19 has a switching input 24 by means of which the device may be switched by applying a signal or a voltage or a current for replacing the actual position value or target position value on the input side by the default value at the default value input 20, 21, 22, 23, so that in the switched state, correspondingly, the default value of the default value input is applied on the output side of the switching device 16, 17, 18, 19 and fed to the corresponding position controller 14, 15. Although a hardware solution is shown here, using relays by way of example, the switching devices 16, 17, 18, 19 may also be implemented as software.

[0066] As shown by the dashed lines, numerous signals and/or pressures may be fed back for further processing in an electronic controller or control logic of the way valve module.

[0067] Although not shown in FIG. 2, a pressure supply, in particular with pump and hydraulic tank, may be furnished analogously to FIG. 1 in order to provide the necessary hydraulic pressure for the way valves 2, 3.

[0068] The control apparatus or actuator drive controller according to the invention, and the method according to the invention, may replace externally predetermined target position values, here for example the target position values of the control system 30, with default values that correspond to a changed target position value, in order to carry out the manipulation of the target value according to the invention, so as to avoid a too long stationary state and improve the reaction speed of the system, or in order to carry out a functional test as shown.