Actuator controller and method for regulating the movement of an actuator

Abstract

An actuator controller for actuating an actuator which can be operated fluidically, having a feed line for an inflow of the working fluid to an actuator connector and having a discharge line for an outflow of the working fluid to a fluid outlet, wherein the feed line is assigned a feed line valve and the discharge line is assigned a discharge valve, which valves are configured in each case to influence a volumetric fluid flow at the actuator connector, and having a control device for actuation of the feed line valve and the discharge valve. A throughflow sensor is arranged in a line section between the discharge valve and the fluid outlet, which throughflow sensor is configured for determining a volumetric fluid flow in the discharge line and for providing a throughflow signal.

Claims

1. A method for controlling the movement of an actuator connected to a first actuator port of an actuator controller, wherein the first actuator port is connected to a fluid outlet via a discharge line in which a discharge line valve is located, a flow sensor being assigned to the fluid outlet, the method comprising: detecting a fluid flow rate from the actuator to the fluid outlet at an at least partial opening of the discharge line through the discharge line valve during a movement of the actuator; performing a flow-dependent activation of the discharge line valve in order to influence the movement of the actuator in a manner dependent on a presettable movement profile stored in a control device of the actuator controller, wherein the movement profile comprises an acceleration profile or a speed profile; performing a flow-dependent activation of a feed line valve in a feed line to a second actuator port during the flow-dependent activation of the discharge line valve assigned to the first actuator port; activating the feed line valve in a manner dependent on a sensor signal level of the flow sensor assigned to the fluid outlet of the first actuator port; and activating the feed line valve by taking into account a supply pressure signal of a pressure sensor located in the feed line and coupled to the control device.

2. The method according to claim 1, wherein the pressure sensor is located in the feed line between a fluid supply port and the feed line valve or in the feed line between the feed line valve and the second actuator port.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An advantageous embodiment of the invention is illustrated in the drawing, of which FIG. 1 shows an actuator controller of the operation of a double-acting fluid-operated actuator.

(2) FIG. 2 shows a movement profile for the fluid-operated actuator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) The actuator controller 1 shown in FIG. 1 is provided for the activation of a fluid-operated actuator 2, which is not a part of the actuator controller 1 and is therefore, like a silencer 3 and a fluid source 4, indicated by broken lines in FIG. 1. In the illustrated embodiment, the actuator controller 1 comprises a first actuator port 5 and a second actuator port 6, which are connected by fluid lines 9 and 10 respectively to a first working chamber 7 and a second working chamber 8 of the actuator 2. The working chambers 7, 8 in the actuator 2 are formed in an actuator housing 15 and separated from one another by a displaceable working piston 11 in a size-variable manner, the working piston 11 being assigned a piston rod 12, which passes through the actuator housing 15 and is designed for the transmission of a movement to a machine element not shown in detail. By applying pressure to the first working chamber 7 and/or to the second working chamber 8, a force can be applied to the working piston 11, which is slidably accommodated in the actuator housing 15 while forming a seal. In accordance with a balance of forces for the working piston 11, which results from the pressure conditions for working fluid in the working chambers 7 and 8 and is dependent on the active surfaces of the working piston 11, a force which may, if applicable, result in a movement of the working piston 11 and the piston rod 12 connected thereto is applied to the working piston 11.

(4) The actuator controller 1 of the illustrated embodiment is shown as an assembly, and the components of the actuator controller 1 shown in greater detail below can be implemented both separately and in a combined construction.

(5) The actuator controller 1 comprises a control device 17, several valves 18, 19, 20, 21 as well as activation units 22, 23, 24 and 25 assigned to the valves 18 to 21 and several sensors 28, 29 and 30.

(6) The control device 17 may, for example, be designed as a microcontroller or microprocessor and is electrically connected to the activation units 22 to 25 and the sensors 28, 29 and 30 respectively by control lines 31, 32, 33, 34 and sensor lines 35, 36, 37. The control device 17 of the illustrated embodiment is further assigned a communication line 40, which is provided as a communication link to a higher-order control unit, in particular a programmable logic controller, or to other actuator controllers, and which is, in the illustrated embodiment, provided for data exchange in accordance with a presettable communication protocol, in particular a bus communication protocol.

(7) The valves 18 to 21 of the illustrated embodiment are designed as 2/2-way valves with piezoelectric activation and can be operated as proportional valves. Owing to the piezoelectric activation, the operation of the valves 18 to 21 requires the provision of a high-voltage signal, which is provided by the associated activation units 22 to 25 via the associated activation lines 41 to 44. Each of the valves 18 to 21 can therefore be adjusted freely between a closed position and an open position in response to a control signal provided by the control device 17 for the respective activation unit 22 to 25.

(8) In the illustrated embodiment, it is provided that each of the valves 19 and 20 is in fluidically communicating connection to a supply line 45, the supply line 45 starting at a supply port 46, to which the fluid source 4 can be connected. There is further provided a fluidically communicating connection between the supply line 45 and the sensor 28 designed as a pressure sensor, which converts a pressure level prevailing in the supply line 45 into an electric supply pressure signal which is made available to the control device 17 via the sensor line 35. Accordingly, the supply pressure made available by the fluid source 4 to the supply line 45 and the downstream valves 19, 20 can be detected with the aid of the sensor 28. Furthermore, the valves 19 and 20 are connected to one of the actuator ports 5 and 6 respectively on the outlet side, so that, if the respective valve 19, 20 is opened, a fluidically communicating connection can be established between the supply line 45 and the respective actuator port 5 or 6, in order to allow a feed of working fluid into the respective working chamber 7, 8.

(9) Each of the valves 18 and 21 is connected to the respective actuator port 5 or 6 on the inlet side and to a discharge line 47, which passes through the sensor 29 designed as a flow sensor and terminates at a fluid outlet 48, on the outlet side. In this way, the valves 18 and 21 facilitate a fluid discharge from the associated working chambers 7, 8 of the actuator 2.

(10) For a movement of the working piston 11 along the movement path 16, the following procedure can be provided by way of example: Depending on the desired movement direction for the actuator 2, pressurised working fluid is made available at the actuator port 5 or at the actuator port 6 for the respective working chamber 7, 8 of the actuator 2 by the respective valve 19 or 20 establishing a fluidically communicating connection between the supply line 45 and the respective actuator port 5 or 6.

(11) The following considerations are based on the assumption that an extension movement of the piston rod 12 is to be provided. Accordingly, pressurised working fluid is applied to the working chamber 7, so that the working chamber 8 becomes smaller, accompanied by a fluid discharge from the working chamber 8 via the actuator port 6, owing to the resulting movement of the working piston 11. For applying pressure to the working chamber 7, the valve 19, which is also described as feed line valve, is moved from the illustrated closed position into an open position not shown in the drawing. This results in a fluidically communicating connection between the fluid source 4, the supply line 45 and the actuator port 5, allowing pressurised fluid to flow into the working chamber 7. Owing to the force acting on the working piston 11 in this process, the latter is displaced towards the working chamber 8, thereby reducing its volume. It is further provided that the working fluid in the working chamber 8 is ducted via the fluid line 10, the actuator port 6, the valve 21, which is also described as discharge line valve, and the discharge line 47 to the sensor 29 designed as a flow sensor and to the fluid outlet 48, where it can be discharged into the environment or into a storage tank after flowing through the silencer 3. Depending on the flow rate of the working fluid flowing through the sensor 29, the latter provides an electric flow signal to the control device 17 via the sensor line 36. In the control device 17, the actual flow rate of the working fluid to the fluid outlet is then calculated in a manner dependent on a signal level of the flow signal provided, and on the basis of this calculation, the acceleration and/or speed of the working piston 11 and the piston rod 12 joined thereto is/are determined. In the control device 17 there is preferably stored a movement profile, in particular an acceleration or speed profile, for the movement of the working piston 11, which can be compared to the actual acceleration and/or speed of the working piston as determined using the flow signal. If the stored movement profile deviates from the detected movement profile, the control device 17 can optionally provide a restriction of the working fluid leaving the working chamber 8 and/or a restriction of the working fluid fed into the working chamber 7 by means of a suitable activation of the valve 19.

(12) The movement profile according to FIG. 2 shows a speed profile 100 for the fluid-operated actuator 2 comprising a starting movement from a first end position, a travelling movement and a deceleration movement towards a second end position.

(13) The actual movement profile for the working piston 11 can be matched better to a stored movement profile by processing at least one pressure signal of the sensors 28 and 30 designed as pressure sensors. The sensor 28 detects the supply pressure in the supply line 45 and provides a measurement result in the form of an electric signal to the control device 17. The sensor 30, which is likewise designed as a pressure sensor, detects a working pressure at the actuator port 6 and provides a measurement result in the form of an electric working pressure signal to the control device 17. A use of at least one pressure sensor 28 and/or 30 is of particular interest if the working fluid is a compressible fluid, in particular a gas and preferably compressed air, because an inclusion of the supply pressure and/or the working pressure facilitates an improved movement control. In an embodiment of the actuator controller which is not shown in the drawing, a working pressure sensor connected to the control device is assigned to the second actuator port as well.

(14) For a retraction movement of the piston rod 12 and the working piston 11 coupled thereto, the valves 20 and 18 are activated in a reversal of the above description, so that pressurised fluid can be applied to the actuator port 6 for the working chamber 8, while working fluid can flow from the working chamber 7 via the actuator port 5 through the valve 18 to the discharge line 47 and, after passing through the sensor 29, to the fluid outlet 48. This movement can likewise be controlled for the actuator 2, using the flow signal of the flow sensor.