DE102004016554B4 - Method and device for controlling a solenoid valve - Google Patents

Abstract

method for controlling a solenoid valve (15), in particular a quantity control valve, in a fuel supply system of an internal combustion engine, wherein the solenoid valve (15) is normally closed, wherein the solenoid valve (15) about a tightening voltage (U_an) opened and over holding a holding voltage (U_halt) in an opened state, characterized in that the tightening voltage (U_an) and / or the holding voltage (U_halt) as a function of operating variables of High pressure pump can be determined.

Description

State of the art

The The invention is based on a method for controlling a solenoid valve and a device for driving a solenoid valve after the genus of independent Claims.

Farther The invention relates to a computer program product for carrying out the Procedure on a computer or controller.

From the DE 199 13 477 A1 For example, a method for operating a fuel supply device with a solenoid valve is already known. The solenoid valve is normally open and is driven to close with a constant voltage - the battery voltage -, whereby the current increases in a characteristic manner. After switching off the voltage, the current again falls in a characteristic manner and the valve opens shortly after the current has dropped. The activation duration of the solenoid valve is influenced as a function of the battery voltage and / or as a function of the coil resistance of the solenoid valve.

From the DE 102 01 453 A1 For example, a method of operating a solenoid valve for a brake cylinder is known. The disclosed solenoid valve is normally open and is driven to close with a constant voltage. When a maximum pull-in current is reached, the coil of the solenoid valve is driven with a pulsed voltage so that the current through the coil drops to a minimum allowable holding current. To open the solenoid valve, the voltage applied to the solenoid valve abge is turned off, the current drop starting from the holding current takes place faster in time than at a present maximum tightening current.

From the DE 101 40 093 A1 a method for driving a solenoid valve is known, which changes further properties of a Ansteuerstromprofil in addition to the drive time, at least for short drive times. This change in the current profile allows accurate metering of fuel at short injection times.

From the DE 34 17 102 A1 for controlling a monostable relay, in which a higher electrical power is supplied during the suit than during holding, wherein in the holding phase the relay, a clocked supply voltage is supplied as holding pulses.

The inventive method and the device has the features of the independent claims In contrast, the advantage that a closed when de-energized solenoid valve, in particular a quantity control valve in a fuel supply system of a Internal combustion engine, is driven, the solenoid valve via a tightening voltage open and over a holding voltage in an open Condition is maintained, depending on operating variables of the high-pressure pump and / or internal combustion engine the tightening and / or holding voltage is determined. By this procedure, it is possible in an advantageous manner, the itself by the applied voltages adjusting coil current to the respective existing operating variables of the high-pressure pump and / or adapt the internal combustion engine and the thermal load conditioned by the flowing Coil current as possible to keep small.

By these in the subclaims listed activities are further advantageous developments and improvements of inventive device possible.

Especially It is advantageous to bear against the coil of the solenoid valve Holding voltage depending the speed and / or the speed of the piston of the high-pressure pump to determine. This procedure makes it possible, for example low speeds of the high pressure pump a low holding voltage to choose, whereby the current flowing through the coil of the solenoid valve current and also reduces the thermal load of the solenoid valve.

According to one further advantageous embodiment is the tightening and / or holding voltage depending on a solenoid valve influencing Temperature determined. This procedure is advantageous Way the temperature dependence of the ohmic resistance of the coil of the solenoid valve compensated.

According to one further advantageous embodiment, The pull-in and / or hold voltage will pass through in their effective voltage value Pulse width modulation influenced. This has the advantage that all Voltages starting from a base voltage, for example the Battery voltage only by pulse width modulation accordingly the desired voltage level can be adjusted.

According to one further advantageous embodiment It is envisaged that the suit tension and / or the suit duration of farm sizes of High pressure pump and / or the internal combustion engine are dependent. So can advantageously in the presence of a low supply voltage the suit duration extended and shortened at high become.

According to others advantageous embodiments hang Tightening tension and / or the tightening duration of the speed or of the speed of the piston of the high-pressure pump as well as of a temperature affecting the solenoid valve. By consideration these sizes will be in an advantageous way the influences of these sizes the solenoid valve compensated.

According to one further advantageous embodiment, a device for driving a solenoid valve is provided, the means for controlling the solenoid valve, wherein tightening and / or holding voltage (U_an, _hold) and / or tightening duration (t_fit) in dependence of Operating variables of High-pressure pump and / or internal combustion engine are determined.

drawings

Further Features, applications and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention shown in the drawings. Make up all features described or illustrated alone or in any combination the subject of the invention, regardless of its summary in the claims or their relationship as well as independent of their formulation or presentation in the description or in the drawings.

It demonstrate:

1 schematically shows a fuel supply system of an internal combustion engine;

2 schematically shows a fuel pump in a suction phase with a de-energized solenoid valve;

3 schematically shows a fuel pump in a delivery phase with an energized solenoid valve;

4 schematically shows a fuel pump in a delivery phase with a de-energized solenoid valve;

5 schematically shows the time course of the piston stroke, stroke of the solenoid valve and associated current and voltage waveforms;

6 schematically shows the current and voltage curve at different speeds of the high-pressure pump;

7 schematically shows the time course of the piston stroke, stroke of the solenoid valve and associated current and voltage curves for different piston speeds;

8th schematically shows the time deviation of the start of delivery due to higher currents.

description

The "de-energized closed "concept offers advantages in terms of function with high turning and cam numbers.

During the funding phase the pump piston is energized, the normally closed solenoid valve, so that the unneeded Amount of fuel over the imprinted Inlet valve can flow back. The necessary magnetic force to hold the inlet valve open bigger than the occurring flow force be at the inlet valve plus a small spring force. Then it will be the solenoid valve is switched off, the inlet valve closes and the Remaining amount is conveyed in the direction of the high pressure side. Closing the Inlet valve is assisted by a spring to close the closing time shorten.

in the Compared to the normally open concept, the maximum magnetic force must be in the tightened state - so at a relatively small residual air gap - be applied. At the normally open solenoid valve must have a relatively large spring force at a relatively large Overcome residual air gap become.

The necessary magnetic forces are smaller when the electroless closed solenoid valve, whereby the Solenoid valve together with magnetic circuit builds more compact. A small magnetic circuit is dynamically better, shorter Switching times can will be realized. In addition, the normally closed quantity control concept regarding tolerances less sensitive.

adversely is the longer one Duty cycle especially for small flow rates. For small flow is the normally closed solenoid valve until the end of För derphase switched off the pump piston. Without additional measures (eg current regulation) there is a risk of thermal overload of the solenoid valve.

1 shows a fuel system 10 an internal combustion engine. A prefeed pump 12 pumps the fuel from the fuel tank 11 over the line 13 to the fuel pump 14 , The solenoid valve 15 is at the fuel pump 14 attached and regulates the flow rate of the fuel pump 14 , The required flow rate is compressed to a relatively high pressure and over the line 16 in a fuel manifold 17 promoted, from where the fuel via injectors 18 in the internal combustion engine 19 is injected. At the fuel manifold 17 there is a pressure sensor 20 , At the internal combustion engine 19 there is a speed sensor 21 , A control unit 23 controls the solenoid valve 15 , wherein in the calculation of the control the pressure over sensor 20 and the speed via sensor 21 received. Furthermore, other variables can be included in the calculation of the control. For example the temperature via a sensor 22 , The program for calculating the control of the solenoid valve 15 is on a storage medium 24 stored in the control unit 23 located.

2 shows the fuel pump 14 in the suction phase. The piston 27 moves down and follows the contour of the cam 28 , The fuel flows through the pipe 13 via the inlet valve 25 in the pump room 26 , Downstream of the pump room 26 is a check valve 29 arranged in the suction phase the way to the line 16 closes. The magnet armature 31 is from a magnetic coil 33 enclosed with a pestle 32 from the magnet armature 31 in the direction of the inlet valve 25 has. In 2 shown de-energized state of the solenoid valve 15 becomes the magnet armature 31 together with the pestle 30 over a spring 30 in one of the inlet valve 25 pioneering position held. Because the piston 27 moved down and thus the volume of the delivery chamber 26 increases the pressure of the fuel increases in the delivery chamber 26 opposite to the fuel pressure in the pipe 13 in the low pressure area, so that the inlet valve 26 due to the existing pressure difference opens automatically and fuel can flow into the pump room. Towards the end of the suction phase, the pressure difference between delivery chamber increases 26 and direction 13 from, so without energizing the Mengesteuerventils 15 the inlet valve 25 typically closes again.

To the inlet valve 25 for the subsequent flow control in the suction phase to keep in an open state, the solenoid valve is energized before the start of the promotion phase. The magnetic coil 33 builds up a magnetic field and pulls, as in 3 shown the magnet armature 31 against the spring 30 to the right in the direction of the inlet valve 25 , About the pestle 32 becomes the inlet valve 25 pushed. The unneeded fuel now flows into the line 13 back to the low pressure side.

To pump the fuel into the pipe 16 the high pressure side is turned off during the delivery phase, the solenoid valve. When de-energized, the magnetic field degrades and over the force of the spring 30 becomes the magnet armature 31 , as in 4 shown, along with ram 32 moves to the left and gives the inlet valve 25 free. The inlet valve 25 closes and the remaining quantity or flow rate is via the check valve 29 on the high pressure side in the pipe 16 and thereafter into the fuel manifold 17 promoted.

In 5 are the piston stroke H_k, the stroke of the solenoid valve H_MSV and the time course of voltage U and current I shown. At the beginning of the suction phase is the solenoid valve 15 initially unpowered. Even during the suction phase, the solenoid valve 15 energized / energized, so that at the beginning of the funding phase, the inlet valve 25 is open. The tightening voltage U_an for quickly tightening the armature 31 must have a relatively high rms value. In the embodiment according to 5 a substantially constant tightening voltage U_an is applied over the duration t_suit. Is the magnet armature 31 attracted, the current I can be reduced to hold. The amperage is reduced by that at the solenoid coil 33 of the quantity control valve 15 voltage applied U is reduced to a holding voltage U_Halt. In the present embodiment, this is done by pulse-width modulation of the applied voltage. The effective applied voltage is set by selecting the pulse and pause ratios. By lowering the effective voltage applied to the solenoid coil, the current I falls to a holding current I_Halten. The current I is so far reduced over the duration t_Halten that the magnetic force to hold open the intake valve 25 is sufficient. The magnetic force must be greater than the spring force and the inlet valve 25 be an attacking flow force.

To close the inlet valve 25 the voltage U is switched off. About a freewheeling diode, the current I is deleted and reduced the magnetic force. The remaining amount of fuel is delivered to the high pressure side.

The control of the flow rate is preferably carried out via the pressure. If less fuel is delivered, the actual pressure in the fuel rail decreases 17 , By comparing the setpoint and actual pressures in the fuel rail, the holding period is recalculated. In the case of too low actual pressure, the holding time t_Halten the solenoid valve 25 shortened, whereby the promotion starts earlier and more amount in the fuel rail 17 is pumped.

The flow force at the inlet valve 25 is caused by the back flow of the unneeded amount of fuel to the low pressure side. Since the flow force depends on the flow velocity, there is a direct relationship between flow force, piston velocity and pump speed; ie as the pump speed increases, the speed of the piston increases 27 and thus also the flow velocity in the direction of the low-pressure region and that on the inlet valve 25 acting flow force.

At low speed is the flow force at the inlet valve 25 low, the magnetic force to hold and thus also necessary for holding current I and the applied holding voltage U_Halt can be significantly lowered.

Different at high speed, here the holding force must be greater. The voltage and current curves over a switching period are in 6 for a high and a low speed compared. The voltage curve is always solid, the current waveform is shown in dashed lines. At high speed, the duty cycle, ie the frequency of the voltage pulses of the PMW signal during the hold phase is greater than at low speed. The effective voltage U_eff and thus the current I increases or decreases with the duty cycle. The at the solenoid valve 15 applied effective holding voltage U_Halt increases with increasing speed and / or speed of the piston 27 the high pressure pump 14 at.

A lowering of the current level at low speeds is necessary because the relative current consumption increases. Without this measure, there is a risk of thermal overload of the solenoid valve 15 , At high speed, the holding current level is higher, but the relative current supply time is lower. In particular, small flow rates are critical in terms of thermal overload, since the start of delivery is at the end of the delivery phase of the pump piston and the holding time is maximum.

According to one another embodiment it provided that in addition to the pump speed and the battery voltage be compensated by PWM. At high battery voltage that is duty cycle while the holding phase correspondingly smaller, which sets the same current as at low battery voltage.

In a further embodiment of the invention, it is provided, the temperature dependence in particular to consider the solenoid of the solenoid valve, by modeling temperature influences or measured, in the PWM calculation. At lower (high) temperature, the ohmic resistance of the solenoid lower (higher), thereby the current strength lowered (increased) can must).

In a further embodiment of the invention, it is provided to take the cam contour into account by incorporating the cam contour into the PWM calculation. The flow or piston speed depends directly on the cam contour. A higher piston speed is compensated by a correspondingly higher current intensity. A corresponding embodiment is in 7 shown. After tightening the solenoid valve 25 the current I is lowered to a first low holding current I_Halten1. At the beginning of the delivery phase is the pump piston 27 at bottom dead center, the piston speed is zero. Then the piston moves 27 up, with the piston speed increasing. By changing the duty cycle of the holding current is tracked. In the area of the maximum piston speed, the current has assumed a second higher holding current I_Halten2. The incipient current extinction results in a magnetic force drop, whereby the inlet valve closes and begins the promotion in the direction of the high pressure side. Ideally, the holding current is adjusted in proportion to the square of the piston speed, so that switching time and power loss are minimal.

The Tightening time t_Train must be securely tightened in every operating state of the magnet. To compensate for tension and temperature while tightening can, as above described, a duty cycle be issued. About that In addition, the suit duration can be suit of even battery voltage and Temperature depend. At high battery voltage the duration of the suit can be shortened, it must be longer if the battery voltage is low. Likewise, at low temperature the tightening duration must be shorter, because of the ohmic resistance the solenoid is lower or the current is higher.

Because the solenoid valve 15 At the beginning of the funding period, it must be ensured that the start of the tax has commenced for a longer period of use, and vice versa.

Farther it is intended to output the tightening duration as a function of the speed. At high speed, the power is within the available Delete time (concerns in particular the deletion with freewheeling diode) not complete reduced. A residual current at the beginning of the next suit pulse can by a correspondingly shorter Tightening duration can be compensated.

Furthermore, it is provided to output the activation start in dependence on the start of delivery. At early start of the promotion, the start of tax is timed forward and vice versa. In principle, it must be ensured that the mechanical tightening process of the solenoid valve takes place during the suction phase. Any internal pressure could prevent the stroke of the inlet valve and thus also of the solenoid valve. Due to dead times in the dynamic magnetic force build-up, the start of control can definitely protrude into the end of the previous funding phase. In addition, at very high speed and early start of delivery, the drive time can be reduced. All at the expense of security.

Furthermore, it is provided to regulate the start of control in certain operating states depending on the start of delivery. To large flow rates (early start of delivery), the holding phase is correspondingly shorter. In extreme cases - high flow at high speed - the holding phase can be completely eliminated. In 8th it is shown by way of example how high currents affect the start of delivery. The holding phase is too short to bring the current to holding current level. At the beginning of the erasure, the current is higher, whereby the start of delivery begins later. In this case, the start of actuation is to be presented at a constant holding time. Preferably, the control start can be regulated by the pressure. If, as in the example, the promotion in the direction of high pressure later, less amount is promoted. The actual pressure in the fuel rail decreases. The actual pressure is reported by the pressure sensor to the control unit. By comparing setpoint and actual pressures, the start of control is recalculated. If the actual pressure is too low, the control must start a little earlier.

• 1. Bei niedriger Drehzahl mit langen Haltephasen erfolgt die Regelung der Fördermenge über die Haltedauer. Ansteuerbeginn, Anzugsdauer und Tastverhältnis werden über ein Kennfeld gesteuert.
• 2. Bei hoher Drehzahl mit kurzen Haltephasen erfolgt die Regelung der Fördermenge über den Ansteuerbeginn. Haltdauer, Anzugsdauer und Tastverhältnis werden über ein Kennfeld gesteuert. Im Extremfall kann die Haltedauer zu Null werden.

Overall, the delivery rate control for fuel pumps for different speeds is as follows:

• 1. At low speed with long holding phases, the flow rate is controlled over the holding period. Activation start, starting time and duty cycle are controlled by a map.
• 2. At high speed with short holding phases, the control of the flow rate is carried out via the start of control. Stopping duration, starting time and duty cycle are controlled via a characteristic diagram. In extreme cases, the holding period can become zero.

Claims (10)

Method for controlling a solenoid valve ( 15 ), in particular a quantity control valve, in a fuel supply system of an internal combustion engine, wherein the solenoid valve ( 15 ) is normally closed, the solenoid valve ( 15 ) via a pull-in voltage (U_an) is opened and maintained in an open state via a holding voltage (U_halt), characterized in that the pull-in voltage (U_an) and / or the holding voltage (U_halt) in dependence on Operating variables of the high-pressure pump can be determined. A method according to claim 1, characterized in that the tightening and / or holding voltage (U_an, _Halt) as a function of the speed and / or the speed of the piston ( 27 ) of the high-pressure pump ( 14 ) is determined. Method according to at least one of the preceding claims, characterized in that the starting voltage (U_an) and / or the holding voltage (U_Halt) in dependence of the solenoid valve ( 15 ) influencing temperature can be determined. Method according to at least one of the preceding Claims, characterized in that the tightening voltage (U_an) and / or the holding voltage (U_Halt) in their effective voltage value Pulse width modulation can be influenced. Method for controlling a solenoid valve ( 15 ), in particular a quantity control valve, in a fuel supply system of an internal combustion engine, wherein the solenoid valve ( 15 ) is normally closed, the solenoid valve ( 15 ) is opened via a tightening voltage (U_an) during a tightening duration t_suit, characterized in that the tightening tension (U_an) and / or the tightening duration t_suitment are determined as a function of operating variables of the high-pressure pump. A method according to claim 5, characterized in that the tightening tension (U_an) and / or the tightening duration t_Szug depending on the speed and / or the speed of the piston ( 27 ) of the high-pressure pump ( 14 ). A method according to claim 5 or 6, characterized in that the tightening voltage (U_an) and / or the tightening duration t_Anzug depending on a solenoid valve ( 15 ) influencing temperature. Method according to claims 5 to 7, characterized that the tightening duration t_Suit depending on the battery voltage is determined. Device for actuating a solenoid valve ( 15 ), in particular a control device in a motor vehicle, wherein the device provides means for controlling the solenoid valve, and wherein the device, the solenoid valve with a pull-in voltage (U_an) during a Tightening suit t_Szug and a holding voltage (U_Halt) drives, characterized that the tightening voltage and / or the holding voltage (U_an, U_Halt) and / or the tightening duration t_Suit are determined as a function of operating variables of the high-pressure pump. Computer program product with program code on a machine readable carrier is stored to carry of the method according to any one of claims 1 to 8, when the program is up running a computer becomes.