DE102011116819B4 - Method for controlling an electrically operable actuating means for a fluid control valve and valve device - Google Patents

Abstract

Method for activating an electrically operable actuating means (11, 12) for a fluid control valve (5), the actuating means (11, 12) being coupled to a valve body (16, 17) which is located in a valve chamber (14) of the fluid control valve (5) for influencing a fluidic cross-section between an input port (6) of the fluid control valve (5) and a working port (7) of the fluid control valve (5) is arranged to be movable relative to a valve seat (18, 19) of the fluid control valve (5) in order to cause a fluid inflow from a Influencing a fluid source (9) through the fluid control valve (5) to a fluid consumer (3) and a fluid outflow from the fluid consumer (3) through the fluid control valve (5) into a fluid sink, with the steps: determining an actual value provided to the fluid consumer (3). -Pressure value, comparing the actual pressure value with a predeterminable setpoint pressure value and determining a setpoint-actual value difference and changing the provision of electrical energy to d as adjusting means (11, 12) at a first activation point in time when the setpoint/actual value difference exceeds a first predefinable threshold value (33) or falls below a second predefinable threshold value (32), characterized in that the change in the provision of electrical energy is ended, if the setpoint-actual value difference enters a threshold value interval between the first and the second threshold value (32, 33) and that the time at which the setpoint-actual value difference enters the threshold value interval is followed by a predefinable waiting time (tw), during which there is no change in the provision of electrical energy, with the target/actual value difference being determined during the waiting time (tw) and that after the target/actual value difference has exited the threshold value interval and the target/actual value difference has subsequently reappeared in the threshold interval during the waiting time requires a restart of the waiting time follows.

Description

The invention relates to a method for activating an electrically operable actuating means for a fluid control valve, the actuating means being coupled to a valve body which is arranged in a valve chamber of a fluid control valve so as to be movable relative to a valve seat in order to influence a fluidic cross section between an inlet port and a working port influencing a fluid inflow from a fluid source to a fluid consumer and a fluid outflow from the fluid consumer into a fluid sink, with the steps: determining an actual pressure value provided to the fluid consumer, in particular in the valve chamber, comparing the actual pressure value with a predeterminable setpoint pressure value and determining a setpoint-actual value difference and changing the provision of electrical energy to the actuating means at a first activation time, with a change in the provision of electrical energy being provided when the setpoint-actual value Di difference exceeds a first predefinable threshold value or falls below a second predefinable threshold value. Furthermore, the invention relates to a valve device.

A 3/3-way fluid control valve, for example, can be operated with such a method, with the aid of which a fluid flow to and from a consumer is influenced. The 3/3-way fluid control valve has a valve chamber in which first adjusting means for influencing a free fluid cross section between a supply port, to which a source for pressurized fluid can be connected, and a working port, which is connected to the fluid consumer, are arranged is. Furthermore, a second adjusting means is provided in the valve chamber, which is designed to influence a free fluid cross section between the working connection and a venting connection, through which pressurized fluid can be discharged into a fluid sink such as a fluid tank or into the environment. The actuating means are electromechanical converters that convert electrical energy that is provided into a movement, for example a coil drive or a piezo drive. By suitably controlling the first and second actuating means, each of which is assigned a valve body which can be placed sealingly against a valve seat or removed from it by the movement of the respective actuating means in order to effect the desired influencing of the fluid flow, the valve connected to the working connection Fluidic consumers are aerated or vented, for example. The two actuators are controlled as a function of a predeterminable setpoint pressure value and a measured actual pressure value, which are related to one another in order to determine a manipulated variable with which the actuators are controlled. In order to avoid constant pressure fluctuations, a three-point control is provided, in which the actuating means are activated only when the setpoint-actual value difference exceeds a predeterminable first threshold value or falls below a second predeterminable threshold value. The actuating means are not actuated for setpoint/actual value differences that lie between the first and second threshold values.

the DE19516627A1 discloses a method for controlling an output variable of a process with the steps: detecting a sampled value of the output variable, comparing the sampled value of the output variable with a target value and determining a target value deviation, calculating a value of a manipulated variable depending on the determined target value deviation in such a way that the output variable of the process the setpoint is approached, and inputting the manipulated variable into the process, after a waiting time has elapsed, redetermining a value of the manipulated variable, the waiting time being variable and based on the difference between the value of the manipulated variable and a previous value of the manipulated variable recorded on the calculated based on a previous sample is calculated.

From the DE 11 2009 001 361 T5 is a solenoid valve having a delivery port fluidly connected to a source of compressed air; a feed port; a bore selectively fluidly connected to the supply and delivery ports; an anchor in the bore; a pole piece in the bore and a coil around the armature and pole piece selectively energized with electrical power, the armature and pole piece being selectively in sealing engagement and moving as an integral armature/pole piece unit as a function of electrical power in the coil and wherein a position of the armature/pole piece within the bore controls a fluidic connection between the delivery port and the delivery port.

The object of the invention is to provide a method for activating an electrically operable actuating means of a valve device and a valve device which have improved control behavior with dynamically changing boundary conditions.

According to a first aspect of the invention, this object is achieved with the features of claim 1 . It is envisaged that the change in the provision of electrical Energy is ended when the setpoint-actual value difference enters a threshold value interval between the first and the second threshold value, that at the point in time when the setpoint-actual value difference enters the threshold value interval, a specifiable waiting time follows, during which there is no change in the provision electrical energy takes place, and that during the waiting time the target-actual value difference is determined and that after the target-actual value difference has left the threshold value interval and the target-actual value difference has subsequently re-entered the threshold value interval during the waiting time The waiting time is restarted.

These measures ensure that when there is a dynamic change in the boundary conditions for the fluid control valve to be controlled according to the method, for example due to changes in the setpoint pressure value and/or the actual pressure value, a reaction is delayed by the waiting time. As a result, an undesired overshoot of the fluidic system, which is formed from the fluid control valve and the fluidic consumer, can be avoided.

The change in the provision of electrical energy can be a provision of electrical energy starting from a state in which the actuating means or means were not supplied with electrical energy. Alternatively, the change in the provision of electrical energy can mean a complete shutdown of a previous provision of electrical energy. In a further alternative, the change in the provision of electrical energy can mean an increase or reduction in an electrical voltage and/or a current flow that is provided to the actuating means.

The restart of the waiting time according to the invention is based on the consideration that if the target/actual value difference re-enters the threshold value interval during the waiting time for the fluidic system, there is no need to influence it until the end of the subsequent waiting time. The waiting time can be chosen to be constant, in particular it can be predetermined by parameterization. Alternatively, it can be provided that the waiting time is dynamically adapted to the requirements of the fluidic system, for example as a function of the pressure provided by the fluid source and/or other operating parameters. Furthermore, it can be additionally or alternatively provided that the subsequent waiting time is set depending on when the target-actual value difference re-enters the threshold value interval during the previous waiting time and/or how long the target-actual value difference lasts during the waiting time was outside the threshold interval.

Advantageous developments of the invention are specified in the dependent claims.

It is expedient if a change amount for the provision of electrical energy is selected independently of the activation time or as a function of the setpoint/actual value difference. For example, either at the first activation time or after one or more waiting time intervals have elapsed at a second activation time, the actuating means is activated with a predefinable and always constant amount of electrical energy. Accordingly, the fluid control valve provided with the actuating means is preferably operated in the manner of a switching valve, which selectively enables a blocking or a complete release of a fluidic flow cross section between the input port and the working port.

Alternatively, it can be provided that the change in the provision of electrical energy at the first or second activation time is dependent on the setpoint/actual value difference. In this case, the fluid control valve is preferably designed as a proportional valve that is set up to adjust the free fluid cross section between the input port and the working port between a blocking position and a release position in a freely selectable step-by-step or infinitely variable manner.

It is advantageous if the change in the provision of electrical energy takes place as the provision or disconnection of a specifiable electrical supply voltage. Thus, only two different states of the provision of electrical energy are provided to the actuating means, either no provision of electrical energy or provision of electrical energy at a predefinable level, for example a predefinable voltage level. As a result, the construction of the control unit provided for the provision of electrical energy can be kept simple, since no complex, for example stepless, influencing of the provision of electrical energy is necessary.

The waiting time is preferably specified by a preferably adjustable timer. The timer can be implemented electrically or electronically; the timer is preferably implemented in a program sequence of a microprocessor or microcontroller that is used to control the actuating means and can thus be set by parameterization.

The object of the invention is achieved according to a second aspect with the features of claim 5. In this case, a valve device is provided with a control unit for providing control signals to a fluid control valve and with a fluid control valve, the fluid control valve comprising an electrically operable actuating means which is coupled to a valve body which is located in a valve chamber of the fluid control valve to influence a fluidic cross section between an input connection and a working connection is arranged to be movable relative to a valve seat in order to influence a fluid inflow from a fluid source to a fluid consumer and a fluid outflow from the fluid consumer into a fluid sink, and wherein the control unit is designed to carry out the method according to claims 1 to 5. The valve device can be designed as a single module for controlling one or more fluid consumers. It can be provided that the valve device can be actuated by an operator using one or more operating elements such as an electric pushbutton switch in order to influence a fluid consumer fluidically coupled to the valve device, such as a fluid cylinder or a fluid motor. Such an arrangement is provided, for example, in a personal support device such as a pneumatically adjustable hospital bed. Alternatively, the valve device is designed for integration into a chain of modules, which can be constructed from a plurality of valve devices of at least essentially the same design and a control device. In this way, for example, a large number of fluid consumers, such as linear actuators, can be controlled centrally in a device, for example in a production machine. By implementing the method according to the invention in the control unit of the valve device, a control behavior is achieved for the individual fluid consumers in which undesired pressure fluctuations are at least largely suppressed.

It is expedient if the adjusting means is designed as a piezoelectric actuator. A piezoelectric actuator allows for a very fast actuating movement for the coupled valve member and thus ensures that a control signal that is provided leads to the desired actuating movement of the valve body relative to the valve seat in a short time. The waiting time and the waiting time can thus be set directly, since practically no latency of the adjusting means has to be taken into account.

It is advantageous if a pressure sensor which is electrically coupled to the control unit and is designed to provide the actual pressure value is arranged in the valve chamber. This ensures a simple construction of the valve device and a simple electrical connection of the valve device.

• 1 eine schematische Schnittdarstellung durch eine Ventileinrichtung und
• 2 ein Signalverlaufsdiagramm für eine bekannte Ansteuerung der Ventileinrichtung gemäß 1 und
• 3 ein Signalverlaufsdiagramm für ein erfindungsgemäße Ansteuerung der Ventileinrichtung gemäß 1.

An advantageous embodiment of the invention is shown in the drawing. This shows:

• 1 a schematic sectional view through a valve device and
• 2 a signal curve diagram for a known control of the valve device according to FIG 1 and
• 3 according to FIG 1 .

In the 1 a fluidic system 1 is shown schematically, which includes a valve device 2 and a fluid consumer 3 . The valve device 2 includes a control unit 4, which is designed to provide control signals to a fluid control valve 5 and a fluid control valve 5. The fluid control valve 5 is designed as a 3/3-way valve, for example, and has a supply port 6, a working port 7 and an outlet port 8 . A fluid source 9 designed as a compressed air source is connected to the supply connection 6 , for example. The fluid consumer 3 embodied as a pneumatic cylinder, for example, is connected to the working connection 7 . A muffler 10 is attached to the outlet connection 8, for example, which ensures that the noise that occurs when fluid flows out into the environment is dampened. The control unit 4 is electrically connected to the fluid control valve 5 in order to actuate a first and a second actuating means 11, 12 there and to detect signals from a pressure sensor 15.

The first and the second adjusting means 11, 12 are each produced as a bending beam made of piezoelectric material and are arranged in a valve chamber 14 enclosed by a valve housing 13. A valve body 16, 17 is assigned to each of the two adjusting means 11, 12 at a front, freely movable end. Depending on an electrical voltage provided by the control unit 4, this valve body 16, 17 can be lifted off a respectively assigned valve seat 18, 19 or pressed onto the valve seat 18, 19 by a voltage-dependent bending movement of the respective actuating means 11, 12 will. As a result, a fluidic cross-section can be set between a blocking position and a release position through a fluid channel 20, 21 opening out at the respective valve seat 18, 19. The two fluid channels 20, 21 each open into the valve chamber 14. The pressure sensor 15, which is designed to detect the actual pressure in the valve chamber 14, is also arranged in the valve chamber 14.

With the aid of the two adjusting means 11, 12 and the components (fluid source 9 and silencer 10) connected to the fluid channels 20, 21, a fluid flow can take place from the fluid source 9 through the valve chamber 14 to the fluid consumer 3 and alternatively a fluid discharge from the fluid consumer 3 through the valve chamber 14 be evoked in the environment. As a result, a fluid pressure can be set at the working connection 7 and thus at the fluid consumer 3 , which is connected to the working connection 7 via a fluid line 22 .

The pressure in the fluid chamber 14 is influenced by the position of the two adjusting means 11, 12, by the properties of the fluid source 9 and by the operating state of the fluid consumer 3. The fluid source 9 usually delivers a substantially constant pressure, so that a change in the pressure conditions in the valve chamber 14 depends on external forces on the fluid consumer 3 and/or on the position of the two adjusting means 11, 12. A pressure increase in the valve chamber 14 can occur as a result of external forces being introduced onto the fluid consumer 3, for example as a result of loading the pivotable section 23, which is designed as a head part, of the hospital bed 24 shown as an example with a weight force. Additionally or alternatively, a user (not shown) can send control commands to the control unit 4 by actuating a keypad 24 provided on the hospital bed 24 in order to lower or raise the pivotable section 23 with the aid of a linear movement of the fluid consumer 3 . The control processes occurring in the control unit 4 in the event of such a change in the setpoint pressure value are given as an example in FIG 2 shown.

the 2 shows a signal curve diagram 28, which reproduces the control behavior of a known three-point controller according to the prior art. In the 3 a signal curve diagram 29 is shown, which shows an example of the control behavior of the controller according to the invention and implemented in the control unit 4 .

The signal waveform diagram 28 in the 2 The initial situation specified is, for example, that at time t0a there is a sudden change in a setpoint pressure value 31 from a lower level to a higher level. As a result, at time t0a there is a setpoint/actual value difference between setpoint pressure value 31 and an actual pressure value 30 since actual pressure value 30 is suddenly below setpoint pressure value 31 . The target pressure value 31 is, for example, at a constant level from the point in time t0a. The change in the target pressure value 31 at the time t0a is due to a user input via the in 1 shown keypad 25 takes place. During the in the 2 illustrated period of time from t0a to t11a or tOb to t8b according to 3 there is no further setpoint change.

Based on the difference between the actual pressure value 30 and the setpoint pressure value 31 at the time t0a, the control unit 4 generates a control signal 34 directed to the first actuating means 11 in order to increase the pressure in the valve chamber 14 by supplying pressurized fluid and thus to achieve the to reduce the setpoint/actual value difference.

The first adjusting means 11 therefore opens the fluidic cross-section between the fluid source 9 and the fluid consumer 3 connected to the working connection 7, so that the desired pressure increase can take place. Since the valve chamber 14 has a very small volume and a pressure equalization with the fluid line 22 and the fluid consumer 3 takes place with a time delay that is considerably greater than the switching time of the actuating means 11, 12, the opening process in the valve chamber 14 causes a sudden pressure increase a positive pressure peak. The fluid pressure measured in the valve chamber 14 quickly exceeds the lower threshold value 32 which, for example, can be located equidistant from the desired value 31 by a predetermined amount. When the lower threshold value 32 is reached at the time t1a, the control unit 4 provides a control signal 34 directed to the first actuating means 11 in order to interrupt further fluid supply into the valve chamber 14. As a result, the first adjusting means 11 is brought back into a position in which no further fluid is supplied to the valve chamber 14 . However, a certain time has elapsed between the detection of the actual pressure value 30 in the valve chamber 14 and the switching off of the fluid supply to the valve chamber 14, within which the actual pressure value 30 in the valve chamber has continued to rise and also an upper threshold value 33, which is also equidistant by can be located at a distance from the desired value 31 by a predetermined amount. This causes a further switching process, but now with a switching signal 35 for the second actuating means 12 in the control unit 4, which is used to set the pressure in the valve chamber 14 below the upper threshold value 33 again. As a result, the fluidic system 1 can only settle down after some time and a large number of switching processes (ventilation and venting) for the two actuating means 11, 12 follow, which, among other things, lead to an undesired emission of switching noises due to the high-frequency recurring actuation of the actuating means 11, 12 leads.

In order to reduce this noise, the control method according to the invention is used, as in FIG 3 is shown. This results in the switching behavior for the actuating means 11, 12 shown in the signal curve diagram 29. Based on the same initial situation as in the signal curve diagram 28, there is initially an actual setpoint value difference at the time t0b, which occurs without delay with a switching operation (switching signal 34 at the time t0b) for the setting means 11 is answered. This is due to the fact that the control unit 4 is designed, for example, in such a way that in the event of actual pressure values outside the threshold value interval delimited by the threshold values 32, 33, it immediately activates the respective actuating means 11, 12, in this case the actuating means 11 with the switching signal 34 to increase the pressure. At time t1b, the actual pressure value reaches lower threshold value 32, as a result of which a timer (not shown in detail) is activated in control unit 4, which specifies a waiting time tw. During this first waiting time tw, the control unit 4 continues to consider changes in the actual setpoint value difference, however, regardless of the setpoint/actual value difference that occurs during the waiting time tw, there is no change in the provision of electrical energy to the two actuating means 11, 12 instead of. If, during the waiting time tw, both the actual pressure value 30 exits the threshold value interval and the actual pressure value 30 re-enters the threshold value interval, as is the case in FIG 3 e.g. at time t2b or t3b, then at the time when the actual pressure value re-enters the setpoint interval, in this case at time t3b, the waiting time tw is restarted. The second waiting time tw extends in the 3 from time t3b to time t4b. Since the actual pressure value 30 left the target value interval during the second waiting time tw, i.e. between t3b and t4b, but did not re-enter the threshold value interval at the end of the waiting time tw, i.e. at time t4b, waiting time tw is not restarted. Rather, the waiting time tw expires completely, which is why it is shown in cross-hatching. At time t4b, due to the deviation of actual pressure value 30 from the setpoint interval, actuating means 11 is actuated in order to increase the pressure in valve chamber 14 and bring actual pressure value 30 back into the setpoint interval.

Control signal 34 ends at point in time t5b when actual pressure value 30 enters the threshold value interval. At the same time, the waiting time tw is started again at time t5b, in this case for the third time. Since the actual pressure value 30 leaves the setpoint interval during the third waiting time tw at time t6b, but re-enters the setpoint interval before the end of the third waiting time at time t7b, waiting time tw is restarted for the fourth time at time t7b. The fourth waiting time tw extends from the time t7b to the time t8b and is shown in cross-hatching since the waiting time tw has elapsed completely. Since at time t8b there is a difference between the setpoint and the actual value, the amount of which is less than the difference between the upper threshold value 33 and the lower threshold value 32, no further adjustment of the actual pressure value 30 is required and the two adjusting means 11, 12 remain in the respective position.

The respective waiting time tw therefore significantly reduces the tendency of the fluidic system to oscillate, so that a reduced number of switching cycles for the actuating means 11, 12 per time unit and thus a reduced noise level for the fluid control valve 5 can be guaranteed with a similar reaction speed.

In an embodiment of the invention that is not shown, it is provided that the waiting time is selected as a function of a previously determined maximum setpoint-actual value difference such that the waiting time is selected to be shorter if the setpoint-actual value difference is large than if the setpoint-actual value difference is small. Difference.

Claims (6)

Method for activating an electrically operable actuating means (11, 12) for a fluid control valve (5), the actuating means (11, 12) being coupled to a valve body (16, 17) which is located in a valve chamber (14) of the fluid control valve (5) for influencing a fluidic cross-section between an inlet port (6) of the fluid control valve (5) and a working port (7) of the fluid control valve (5) is arranged to be movable relative to a valve seat (18, 19) of the fluid control valve (5) in order to cause a fluid inflow from a Influencing a fluid source (9) through the fluid control valve (5) to a fluid consumer (3) and a fluid outflow from the fluid consumer (3) through the fluid control valve (5) into a fluid sink, with the steps: determining an actual value provided to the fluid consumer (3). -Pressure value, comparing the actual pressure value with a predeterminable setpoint pressure value and determining a setpoint-actual value difference and changing the provision of electrical energy to d as adjusting means (11, 12) at a first triggering time when the setpoint/actual value difference exceeds a first predefinable threshold value (33) or falls below a second predefinable threshold value (32), characterized in that the change in the provision of electrical energy is ended, if the setpoint-actual value difference enters a threshold value interval between the first and the second threshold value (32, 33) and that the time at which the setpoint-actual value difference enters the threshold value interval is followed by a predefinable waiting time (tw), during which there is no change in the provision of electrical energy, with the target/actual value difference being determined during the waiting time (tw) and that after the target/actual value difference has exited the threshold value interval and the target/actual value difference has subsequently reappeared in the threshold interval during the waiting time, the waiting time is restarted. procedure after claim 1 , characterized in that a change amount for the provision of electrical energy is selected independently of the activation time or as a function of the setpoint-actual value difference. procedure after claim 1 or 2 , characterized in that the change in the provision of electrical energy takes place as the provision or disconnection of a predefinable electrical supply voltage. Procedure according to one of Claims 1 until 3 , characterized in that the waiting time (tw) is specified by a preferably adjustable timer. Valve device with a control unit (4) for providing control signals to a fluid control valve (5) and with a fluid control valve (5) which comprises an electrically operable actuating means (11, 12) which is coupled to a valve body (16, 17) which in a valve chamber (14) of the fluid control valve (5) for influencing a fluidic cross section between an inlet port (6, 8) and a working port (7) is arranged to be movable relative to a valve seat (18, 19) in order to ensure a fluid inflow from a fluid source ( 9) to a fluid consumer (9) and to influence a fluid outflow from the fluid consumer (9) into a fluid sink, characterized in that the control unit (4) is designed to carry out a method according to one of the preceding claims and wherein in the valve chamber (14 ) a with the control unit (4) electrically coupled pressure sensor (15) is arranged, which is designed to provide the actual pressure value. valve device claim 5 , characterized in that the actuating means (11, 12) is designed as a piezoelectric actuator.

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