DE102006045353A1 - Control unit and method for controlling an electromagnetic valve arrangement - Google Patents

Abstract

The invention discloses an electromagnetic valve assembly comprising a magnetic circuit (110) having a stator (111) with a valve spool (L11) and a movable armature. The valve coil (L11) is to be connected to a control unit (140) and is acted upon by this with controllable control current. An applied, controllable control current generates a magnetic field surrounding the valve coil (L11), which causes a force acting on the armature. The armature moves a valve member relative to its valve seat. The valve arrangement is characterized in that the magnetic circuit has a measuring winding (L12). The measuring winding (L12) must be connected to the control unit (140). The winding (L12) is arranged in the magnetic circuit so as to be at least partially penetrated by the magnetic field, wherein a change in the magnetic flux in the magnetic field induces a measurable voltage in the measuring winding (L12). About the magnetic flux can be closed to the position of the armature. The pressure in a valve can thus be regulated.

Description

The The invention relates to a valve arrangement, a control unit for an electromagnetic Valve unit and a method for controlling such electromagnetic Valve unit.

State of the art

electromagnetic Valves, such as those used in hydraulic braking systems for ABS / TC systems usually used a magnetic circuit with at least one valve spool on. The valve spool is acted upon by a control unit with a pulse width modulated control current, with the aim of setting a predefined pressure level in the brake system.

Of the Hydraulic pressure in such a valve can be achieved by means of a closed loop control. It is also possible to use the through the valve coil generated magnetic flux by means of a Hall probe to detect and regulate this.

The problem underlying the invention

One Problem with pressure control with a closed control loop is that for that expensive pressure sensors needed which increase the cost of the ABS / TC system. In the regulation of the magnetic Flow by means of a Hall probe is the space required for the Hall probe and the associated electronics problematic, which impairs a compact design of the ABS / TC system. Besides that is a Hall probe is a sensitive and therefore failure-prone electrical component.

Inventive solution

The present invention proposes a space-saving and cost-effective Arrangement with associated Procedure before. In the magnetic circuit of the valve assembly is a additional Mounted measuring winding, at which an induced voltage measured becomes. This voltage is proportional to the magnetic flux of the Valve generated magnetic field, and thus also caused by the magnetic field Force acting on the moving armature of the magnetic circuit and influenced the position of the anchor. The space required for the measuring winding is much lower than that for a Hall probe or for the pressure sensor. The cost of a winding of thin Wire are also wesent Lich lower than that of an expensive pressure sensor for the Control by means of a closed control loop. Besides that is one coil less failure prone like a Hall probe.

The Invention is based on the fact that the position of the armature the magnetic field, which is generated in the electromagnetic circuit of the valve influenced. Especially the flux density of the magnetic field is influenced and thus also the magnetic flux. The position of the armature in the valve is determined the hydraulic pressure set in the valve. By determination of the magnetic flux can therefore on the position of the armature and thus closed to the pressure prevailing in the valve hydraulic pressure become. It can thus be determined an actual value for the hydraulic pressure which serves a control unit as a control variable for the pressure control.

The Electromagnetic valve device with magnetic circuit, which for the inventive Method is to use, has a stator with a valve spool and a movable anchor. The valve spool is equipped with a control unit to connect and can from this with a controllable control current be charged. An applied controllable control current generated a magnetic field surrounding the valve coil, the one on the armature produces an effective force. The armature relatively moves a valve member to the valve seat. The magnetic circuit also has a measuring winding which is to be connected to a control unit. The measuring winding is arranged in the magnetic circuit so that it is from the magnetic field to the valve spool is at least partially interspersed, with a change of the magnetic flux in the magnetic field, a measurable voltage in the measuring winding induced. The measuring winding is an integrator, a filter, preferably a low-pass filter, and a radier downstream.

Preferably is the control unit for the inventive method to supply a controlled variable, which is detected at the measuring winding. The valve spool is from the Control unit, preferably pulse width modulated, control current as a control variable. From Outside the control unit is a setpoint for the armature to be caused Specify force as a reference variable. The controlled variable is one Supply A / D converter in the control unit. As a controlled variable is the Control unit to supply the induced voltage in the measuring winding, which is proportional to the force influencing the anchor. Around To obtain the controlled variable the measuring winding is an integrator, a filter, preferably a Low-pass filter, and a Radizierer downstream. The number of turns the measuring winding is preferably chosen so that one of the terminals of the Measuring winding voltage applied directly from a downstream A / D converter is to process. There is no need for an amplifier which will reduce the cost of the ABS / TC system additionally low being held.

In order to set the force acting on the armature as accurately as possible, the following procedure is preferably used according to the invention: a) Setting a control current for a force to be set at the armature as a manipulated variable; b) determining a variable proportional to the force acting on the armature as a controlled variable; c) Step by step approach the manipulated variable for the valve spool, so that the controlled variable changes in the direction of the reference variable, as long as the controlled variable deviates from the reference variable. The detected controlled variable corresponds to the force acting on the armature. Changing the control current also alters the force acting on the armature. By approximating the controlled variable to the reference variable, the force to be set at the armature is approximated. The voltage measurement on the measurement winding results in a value that is converted by means of an integrator, a filter, preferably a low-pass filter, and a radier into a proportional to the magnetic force acting on the armature, which is to be supplied to the control unit as a controlled variable.

in the Following are two embodiments of the invention explained in more detail with reference to drawings:

1 shows an exemplary circuit arrangement with valve assembly and control unit.

2 shows an alternative exemplary circuit arrangement, with valve assembly and control unit.

The exemplary representation of a circuit arrangement 1 in 1 shows the electromagnetic circuit 110 a valve assembly (not further illustrated) with a stator 111 , a valve spool 111 , a movable armature (not shown) and a measuring winding 112 which has two terminals. The measuring winding 112 is with an integrator 120 connected, the first entrance 121 , a second entrance 122 , as well as an exit 123 having. The two connections are the measuring winding 112 with the first entrance 121 or the second input 122 of the integrator 120 connected. The integrator 120 is made up of an operational amplifier U11, a capacitor C11 and a resistor R11. The first entrance 121 of the integrator 120 is connected to the non-inverting input (+) of the operational amplifier. The non-inverting input (+) and the first input 121 are connected to a reference potential 0. The second entrance 122 of the integrator 120 is connected via the resistor R11 to the inverting input (-) of the operational amplifier U11. The exit 123 of the operational amplifier U11 is fed back via the capacitor C11 to the inverting input (-) of the operational amplifier U11. Furthermore, the integrator points 120 an electrically operable switch U12. The electrically operated switch U12 is preferably an electronic switch, which is shown here in simplified form as a relay. The exit 123 of the operational amplifier U11 is connected via the electromagnetic switch U12 to the inverting input (-) of the operational amplifier U11. In the rest position of the electrically operable switch U12 so that the feedback via the capacitor C11 is bridged. The exit 123 of the integrator 120 is with an input P11 of a filter 130 connected. The filter 130 also has a port G11 over which the filter 130 is connected to the reference potential 0, and an output P13 which is connected to an input IN of a Radizierers 150 connected is. The Radierer 150 is via an output OUT with a control input (-) of a control unit 140 connected. The Radierer 150 is also connected via a terminal G12 to the reference potential 0. The control unit 140 is with the valve spool 111 of the electromagnetic circuit 110 connected via a MOSFET transistor X11, wherein the gate terminal of the MOSFET transistor X11 of the control unit 140 is controlled via an output PWM. Via a drain connection, the MOSFET transistor X11 is connected to a first terminal of the valve coil L11 and a freewheeling diode D11. The freewheeling diode D11 is connected in parallel to the valve coil L11 and serves to protect against inductive overvoltages. The second connection of the valve coil L11 is connected to a positive connection v + of a power supply. The source and the substrate of the MOSFET transistor X11 are connected to the reference potential 0. Furthermore, the control unit 140 connected via an output ROUT to an input A of the electrically actuatable switch U12, which is connected via an output B to the reference potential 0. The control unit 140 For example, the valve coil L11 can be supplied with a controllable and pulse width modulated control current by controlling the MOSFET transistor X11. The control unit 140 also has an input r +, for a desired value F _Soll and a terminal G13, via which the control unit is connected to the reference potential 0. The freewheeling diode D11 and the valve coil L11 are also connected to the positive terminal v + of a power supply V1 whose ground terminal v- is also connected to the reference potential 0.

am beweglichen Anker hervorruft, wobei F die Kraft, B die magnetische Flussdichte im Magnetfeld um die Ventilspule L11, A der magnetische Querschnitt des Ankers, und μ₀ die Permeabilität der Luft ist. Durch Verändern des Steuerstroms verändert sich die auf den Anker wirkende Kraft F so, dass die Stellung des Ankers verändert wird. Die magnetische Flussdichte B des magnetischen Feldes ergibt sich aus

wobei H die erzeugte magnetische Feldstärke und μ_r die Permeabilitätszahl des für den Anker und den Stator verwendeten Materials ist. Die magnetische Feldstärke H ist definiert als der Elektrische Strom I multipliziert mit dem Quotienten aus der Windungszahl N₁ der Ventilspule L11 und der Magnetfeldlänge l. Die Magnetfeldlänge l variiert mit der Stellung des Ankers im Magnetfeld und beeinflusst dadurch die magnetische Flussdichte B. Der Strom I variiert mit der Spannung U = V1 und dem Widerstand Q der Ventilspule L11. Der Widerstand der Ventilspule L11 ist abhängig von der Temperatur. Eine Änderung der Stellung des Ankers führt zu einer Veränderung der magnetischen Flussdichte B, dadurch zu einer Veränderung der Kraft Fund folglich zu einer Veränderung des eingestellten Drucks im Ventil. Über die Beziehung

steht die magnetische Flussdichte Bauch in Beziehung mit dem magnetischen Fluss Φ im Magnetfeld. Da die magnetische Flussdichte B von der Stellung des Ankers beeinflusst ist, ist auch der magnetische Fluss Φ abhängig von der Stellung des Ankers.When the valve coil L11 is supplied with a control current, a magnetic field is formed around the valve coil L11, which generates a force F according to the relationship

at the movable armature, where F is the force, B is the magnetic flux density in the magnetic field around the valve coil L11, A is the magnetic cross section of the armature, and μ _{0 is} the permeability of the air. Changing the control current changes the on the armature acting force F so that the position of the armature is changed. The magnetic flux density B of the magnetic field results

where H is the magnetic field strength produced and μ _{r is} the permeability of the material used for the armature and the stator. The magnetic field strength H is defined as the electric current I multiplied by the quotient of the number of turns N _{1 of} the valve coil L11 and the magnetic field length l. The magnetic field length l varies with the position of the armature in the magnetic field and thereby influences the magnetic flux density B. The current I varies with the voltage U = V1 and the resistance Q of the valve coil L11. The resistance of the valve coil L11 depends on the temperature. A change in the position of the armature leads to a change in the magnetic flux density B, thereby changing the force Fund consequently to a change in the set pressure in the valve. About the relationship

The magnetic flux density belly is related to the magnetic flux Φ in the magnetic field. Since the magnetic flux density B is influenced by the position of the armature, the magnetic flux Φ is also dependent on the position of the armature.

N₂ ist hierbei die Windungszahl der Messwicklung 112 und dΦ die Änderung des magnetischen Flusses Φ nach der Zeit t.The magnetic field also penetrates at least partially in magnetic coupling with the valve coil L11 in the magnetic circuit 110 located measuring winding 112 , Changing the control current through the control unit 140 The magnetic flux Φ also changes in the magnetic field around the valve coil L11. A change in the magnetic flux Φ in the magnetic field around the valve coil L11 induced in the measurement winding 112 a voltage U for which applies:

N ₂ here is the number of turns of the measuring winding 112 and dΦ the change of the magnetic flux Φ after the time t.

By integration of the induced voltage values U over time with the integrator 120 a value is determined which is proportional to the magnetic flux Φ in the magnetic field. The electrically operable switch U12 is used to control the start state of the integrator 120 define. The contact in the electrically operable switch U12 is therefore before the start of a valve activation of the control unit 140 opened by the electrically operated switch U12 a switching signal from the output ROUT of the control unit 140 receives.

Due to the inertia of the iron material used for its production and the high frequency (approximately 200-10,000 Hz) of the pulse width modulated signal, the armature will not follow the signal path of the pulse width modulated signal. Rather, he will assume a position that corresponds to the mean magnetic flux Φ. The filter 130 is designed as a low-pass filter and forms the mean value of the magnetic flux Φ in the magnetic field. The transfer function of the low pass coincides at least approximately with the transfer function of the mechanical armature spring system of the valve so as to be able to conclude from the mean value of the magnetic flux Φ on the armature position.

verknüpft. Der magnetische Fluss Φ ist somit quadratisch proportional zu der im Ventil wirkenden Kraft F. Durch das Radizieren des Wertes für den mittleren magnetischen Fluss Φ in einem dem Tiefpassfilter nachgeschalteten Radizierer 150 wird ein Wert erzeugt, der der am Anker wirkenden Kraft F direkt proportional ist. Dieser Wert wird der Regeleinheit 140 als Regelgröße F_Regel zugeführt. Die Regeleinheit 140 vergleicht die Regelgröße F_Regel mit einer Führungsgröße F_Soll, die der Regeleinheit 140 von außen über einen Eingang r+ zugeführt wird. Da die Regelgröße F_Regel über den magnetischen Fluss Φ ebenfalls von der Magnetfeldlänge l und damit von der Ankerstellung abhängt, lässt sich von der Regelgröße F_Regel auf die Ankerstellung und damit auf den im Ventil eingestellten hydraulischen Druck schließen. Die Regeleinheit 140 verändert mit dem Steuerstrom am Ausgang PWM die Stellgröße in der Art, dass sich die Regelgröße F_Regel der Führungsgröße F_Soll annähert. Auf diese Weise wird im Ventil der gewünschte hydraulische Druck eingestellt. Durch die beschriebene Regelung können Einflüsse der Versorgungsspannung, der Temperatur auf die verschiedenen Komponenten, Geometrieänderungen des Ventils und die magnetische Sättigung der Materialien ausgeregelt werden.The magnetic flux Φ is related to the force produced in the valve through the relationship

connected. The magnetic flux Φ is thus quadratically proportional to the force F acting in the valve. By etching the value of the mean magnetic flux Φ in a radiser downstream of the low-pass filter 150 a value is generated which is directly proportional to the force F acting on the armature. This value becomes the control unit 140 fed as a controlled variable F _rule . The control unit 140 compares the controlled variable F _rule with a command variable F _target , that of the control unit 140 from the outside via an input r + is supplied. Since the controlled variable F _rule via the magnetic flux Φ also depends on the magnetic field length l and thus on the armature position, the control variable F _{can be used} to infer the armature position and thus the hydraulic pressure set in the valve. The control unit 140 changed with the control current at the output PWM the manipulated variable in the way that the controlled variable F _rule of the reference variable F _target approaches. In this way, the desired hydraulic pressure is set in the valve. By the described control influences of the supply voltage, the temperature on the various components, geometry changes of the valve and the magnetic saturation of the materials can be compensated.

2 shows an alternative exemplary circuit arrangement 2 for carrying out the method according to the invention. 2 shows the electromagnetic circuit 210 a valve assembly (not illustrated) with a stator 211 , a valve spool 121 , a movable armature (not shown) and a measuring winding 122 , which has two connections on. The measuring winding 122 is over a first connection 212 connected to reference potential 0.

Via a second connection 213 is the measurement winding 122 with a first connection 221 a first RC element 220 connected. The first RC element 220 also has a second port 222 , a third connection 223 and a fourth connection 224 on. The first RC element 220 has a resistor R21, which is the first terminal 221 with the third connection 223 of the first RC element 220 combines. The second connection 222 of the first RC element 220 is with the fourth connection 224 of the first RC element 220 connected. Furthermore, the first RC element 220 a capacitor C21, the resistor R21 of the first RC element 220 is downstream. The capacitor C21 of the first RC element 220 connects the third port 223 with the fourth connection 224 , The second connection 222 and the fourth connection 224 of the first RC element 220 are connected to the reference potential 0.

A second RC element 230 is in series with the first RC element 220 connected. It has a first connection 231 , a second connection 232 , a third connection 233 and a fourth connection 234 on. The first connection 231 is with the third connection 233 connected via a resistor R22. The second connection 232 is with the fourth connection 234 of the second RC element 230 connected. The second RC element further includes a capacitor C22, which is the resistor R22 of the second RC element 230 is downstream. Furthermore, the capacitor connects the second RC element 230 the third connection 233 with the fourth connection 234 ,

The third connection 223 of the first RC element 220 is with the first connection 231 of the second RC element 230 connected. The fourth connection 224 of the first RC element 220 is with the second connection 232 of the second RC element 230 connected.

The second RC element 230 is about the third connection 233 with an A / D converter (not further illustrated) of a control unit 240 connected.

The control unit 240 is with the valve spool 121 of the electromagnetic circuit 210 via a MOSFET transistor X21, wherein a gate terminal of the MOSFET transistor X21 from the control unit 240 is controlled via an output PWM. About its drain terminal of the MOSFET transistor X21 is connected to a first terminal of the valve coil 121 and a freewheeling diode D21. The freewheeling diode D21 is connected in parallel with the valve coil L21 and serves to protect against inductive overvoltages. The second connection of the valve spool 121 is connected to a positive terminal v + a power supply V2. The source and the substrate of the MOSFET transistor X21 are connected to the reference potential 0. The control unit 240 can the valve spool 121 with a controllable and pulse width modulated control current by controlling the MOSFET transistor X21 act. The control unit 240 also has an input r + for a nominal value Soll and a terminal GND, via which the control unit is connected to the reference potential 0. The freewheeling diode D21 and the valve coil 121 are also connected to a positive terminal v + of the power supply V2 whose ground terminal v- is also connected to the reference potential 0. The control unit 240 is also connected via a supply input supply to the positive pole v + the power supply V2.

The physical relationships of control current, magnetic field, magnetic flux density B, magnetic field strength H, magnetic field length l and influence of the position of the armature are already for the embodiment according to 1 explained. Likewise, the relationship between induced voltage U, magnetic flux Φ and armature force F has already been described.

The resistor R21 and the capacitor C21 of the first RC element 220 are dimensioned so that by the first RC element 220 an integrator is implemented (R21 · C21 >> measuring time). By integration with the first RC element 220 a value is determined which is proportional to the magnetic flux Φ in the magnetic field.

The armature will, due to the inertia of the iron material used for its production and the high frequency (about 200-10,000 Hz) of the pulse width modulated signal, the waveform of the pulse width modulated signal does not follow. Rather, he will assume a position that corresponds to the mean magnetic flux Φ. The resistor R22 and the capacitor C22 of the second RC element 230 are therefore dimensioned so that by the second RC element 230 a low pass is realisiet. The second RC element 230 forms the mean value of the magnetic flux Φ in the magnetic field. The transfer function of the second RC element 230 realized low pass is at least approximately in accordance with the transfer function of the mechanical armature spring system of the valve, so that the mean value of the magnetic flux Φ can be concluded on the armature position.

The mean magnetic flux Φ serves as the control unit 240 as input value for their A / D converter.

In the control unit 240 will after the A / D conversion of the input value erodes and thus generates a value that is directly proportional to the force acting on the armature F. This value serves as a controlled variable. The control unit 240 compares the controlled variable with a reference variable target, that of the control unit 240 via an input r + is supplied. Since the generated value for the controlled variable via the magnetic flux Φ is also proportional to the force in the valve, the generated value can be used to infer the hydraulic pressure set in the valve. The control unit 240 changed with the control current, the manipulated variable in the way that the controlled variable approaches the reference variable target. In this way, the desired hydraulic pressure is set in the valve.

In a third alternative embodiment, which is not further illustrated, the integration of the measured and low-pass filtered value can also be taken over by the control unit. The swapping of the steps of filtering and integrating is opposite to the example 2 also possible because they are linear systems in terms of system theory, with which the signal processing is performed. It is also possible to use a four-pole RC filter with the terminals of the measuring winding 122 to interconnect and integrate and radiate in the control unit 240 perform. Finally, it would also be possible to map the low pass also by arithmetic operations in the control unit.

In conclusion, be pointed out that the inventive method for controlling hydraulic valves not for use in ABS / TC systems and for use the circuitry described herein is limited.

Claims (11)

An electromagnetic valve arrangement with a magnetic circuit ( 110 ), the - a stator ( 111 ) with a valve coil (L11) and - has a movable armature, wherein - the valve coil (L11) - with a control unit ( 140 ) is to be connected and from this - acted upon by controllable control current, wherein - an applied controllable control current generates a magnetic field surrounding the valve coil (L11), - which causes a force acting on the armature; wherein - the armature - a valve member moves relative to the valve seat; characterized in that - the magnetic circuit has a measuring winding (L12), - the measuring winding ( 112 ) with the control unit ( 140 ) is to be connected; - The measuring winding (L12) is arranged in the magnetic circuit that it is at least partially penetrated by the magnetic field, wherein - a change in the magnetic flux in the magnetic field induces a measurable voltage in the measuring winding (L12). The electromagnetic valve arrangement according to claim 1, wherein - the measuring winding is an integrator ( 120 ), a filter ( 130 ) and a Radizierer ( 150 ) are connected downstream. The electromagnetic valve assembly of claim 2, wherein - the filter ( 130 ) is a low-pass filter. A control unit ( 140 ) for an electromagnetic valve assembly according to claim 1, wherein - the control unit ( 140 ) is to convey a controlled variable; - the valve coil (L11) of the control unit ( 140 ) is to supply a control current as a manipulated variable; - the control unit ( 140 ) is preset as a reference variable from the outside a target value for the force to be caused at the anchor; and - the control unit ( 140 ) contains an A / D converter to which the controlled variable is to be supplied, characterized in that - as a controlled variable in a measuring winding ( 112 ) induced voltage of the control unit ( 140 ) is to be supplied; and - the controlled variable is proportional to the force influencing the armature. The control unit according to claim 4, wherein - between measuring winding (L12) and control unit ( 140 ) an integrator ( 120 ), a filter ( 130 ) and a Radizierer ( 150 ) for converting the value of the voltage induced at the measuring winding (L12) into the controlled variable, wherein - the integrator ( 120 ) and the Radizierer ( 150 ) realized either as a separate switching elements, or in the control unit ( 140 ) are integrated. The control unit according to claim 5, wherein - the filter ( 130 ) is a low-pass filter. The control unit according to claim 4, 5 or 6, wherein - the number of turns the measuring winding (L12) is selected is that one on the connectors the measuring winding (L12) voltage directly from one downstream A / D converter is to process. The control unit according to one of claims 4 to 7, wherein - the control unit ( 140 ) drives the valve coil (L12) with a pulse width modulated signal. A method for operating a control unit ( 140 ) according to claim 4, comprising the steps of: - determining a control current as a manipulated variable for the valve coil (L11) of the valve arrangement; - detecting voltage values at the measuring winding (L12); - transforming the detected voltage values into a controlled variable that corresponds to the force acting on the armature; - supplying the converted voltage values as controlled variable to the control unit ( 140 ); and - gradually changing the control current as a manipulated variable at the valve spool (L11), and thus the force acting on the armature, so that the controlled variable changes in the direction of the reference variable, as long as the controlled variable deviates from the reference variable, whereby the set at the anchor Force is approximated. The method of claim 9, wherein the reshaping comprises the steps of - integrating the voltage values with an integrator ( 120 ), - filtering the voltage values with a filter ( 130 ), and - Radieren the voltage values with a Radizierer ( 150 ) having. The method of claim 10, wherein - for filtering a low pass filter is used.