EP1044323A1

EP1044323A1 - Electromagnetic injection valve

Info

Publication number: EP1044323A1
Application number: EP99953630A
Authority: EP
Inventors: Matthias Philipp; Bernd Herrmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-09-02
Filing date: 1999-08-28
Publication date: 2000-10-18
Anticipated expiration: 2019-08-28
Also published as: JP2002524683A; EP1044323B1; US6657846B1; DE19839863C1; WO2000014395A1; DE59907542D1

Abstract

The invention relates to an electromagnetic injection valve (1) comprising two counterwound magnet coils (SP1, SP2) which have identical characteristic quantities and which are placed on the same magnetic circuit so that the force effects of the magnet coils (SP1, SP2) are nullified when they are flown through by the same excitation current. By virtue of the double coil (SP1, SP2) having a canceling effect, the actual energizing process of the valve (1), i.e. the opening of the same, is transformed in one of both coils in a deenergizing process. The rapid current decay is now determined by dimensioning the extinction voltage (UZD2). As a result, it is possible to obtain rapid force build-up times without increasing the supply voltage (Ubatt). The valve can be controlled by using a conventional switching output stage or by using a current-controlled switching output stage. It is also possible to shorten the closing process by reversing the differential current (Id) during deenergizing.

Description

Electromagnetic injector

State of the art

The invention relates to an electromagnetic injection valve with a double coil, in which a first and a second magnetic coil with the same parameters are arranged on the same magnetic circuit, one end of which is connected together to a supply voltage and the other ends of which are individually connected to a first and second switching means of an electronic control circuit. wherein a hold circuit that can be controlled by the control circuit is connected in parallel to the first magnet coil.

Such an electromagnetic injection valve is known from DE-OS 2 306 007. In the known electromagnetic injection valve, two or more magnetic coils on the same magnetic circuit and a functional electronic control device adapted to this arrangement serve to open and close the shut-off element of the injection valve by a first excitation of an electromagnetic opening the shut-off element from its closed state

Attraction, by a second excitation an electromagnetic holding the shut-off device after it has been opened once in its open state Attraction, and finally, by a third excitation, an opposite magnetic flux is generated to quench the induced magnetic flux so that the shut-off device is closed from its open state.

In general, in the case of an electromagnetic injection valve, the current rise and therefore also the force increase in the armature is essentially determined by the inductance and the resistance of the valve coil and the supply voltage Ubatt of the coil. The inductance results from the number of turns of the coil and the design of the magnetic circuit. In the motor vehicle, the supply voltage is limited to 12 volts. Today's requirements for the on-time of an electromagnetic used in the motor vehicle

In the case of a simple valve coil, the injection valve led to very high currents which could not be achieved with previous switching transistors and the existing line resistances.

To date, the necessary rapid current and force increase in the injection valve when switching on with higher voltage is achieved from a booster capacitor that is charged with a DC-DC converter or by recharge. The DC voltage

DC converters are necessary for magnetic circuits with high eddy current losses, since a recharge with the inductance of the valve is too poor in efficiency. In addition, the recharge with the valve would lead to long charging times for the booster capacitor. The recharge current leads to excitation in the magnetic circuit, which reduces the security against leakage and unintentional opening of the valve. Objects and advantages of the invention

It is therefore the object of this invention to achieve a reliably working electromagnetically actuated injection valve with the shortest possible switch-on and switch-off times and low switching effort.

The above object is achieved in a generic electromagnetic injection valve in that the two solenoids are wound in opposite directions, so that their force effects cancel each other out with the same excitation current, and in that the control circuit controls the switching means during a complete open-hold-close cycle of the valve so that

in a first phase an initial charging process takes place with the valve closed, both switching means being closed when the hold circuit is inactive and the current flowing through the two solenoid coils increasing relatively slowly,

in a second phase, which is an opening phase of the valve, the current through the second solenoid is quickly switched off by opening the second switching means, while the first switching means is closed and the holding circuit remains inactive,

during a third phase, a hold phase, the hold circuit is activated and thus the current through the first magnet coil is reduced to a holding current, and in a fourth phase, which is a closing phase, at least the holding circuit is deactivated to close the valve and the first switching means is opened.

Due to the double coil with canceling effect, the actual switching on of the valve, i.e. the opening of the valve in the second phase is converted into a shutdown in one of the two coils. The rapid drop in current is now determined by the dimensioning of the extinguishing voltage. Rapid rise times of the force can thus be achieved without increasing the supply voltage. The injection valve can be controlled with a conventional switching output stage or with a current-controlled switching output stage. By reversing the differential current when switching off, it is also possible to shorten the closing process. A major advantage of the invention is thus the simplification and cost-effectiveness of the final stage. The booster capacitor and the DC-DC converter can be omitted in the control unit. This also makes it easier to integrate the output stage in the control unit.

Further features and advantages of the invention will become apparent in the dependent claims and in the following description of a preferred embodiment of an electromagnetic injection valve according to the invention with a double coil when this description is read with reference to the accompanying drawing.

drawing

Figure 1 shows schematically and in the form of a

Block diagram of a preferred circuit of a electromagnetic injection valve with double coil in connection with output stages of the control circuit; and

FIGS. 2A to 2E show waveforms of in the circuit of FIG

Figure 1 occurring signals as a function of time to explain the operation of the circuit shown in Figure 1.

Embodiment

In the circuit shown in FIG. 1, 1 is an equivalent circuit diagram of an electromagnetic injection valve with a double coil. The magnetic circuit of the injection valve 1 consists of two magnet coils SP1 and SP2 wound in opposite directions. Both solenoids SP1, SP2 have the same parameters, ie number of turns, inductance L and winding resistance R _cu , and their force effect is canceled out due to the opposite winding direction at the same current ISP1, ISP2. Both solenoid coils SP1 and SP2 are connected at one end to a supply voltage, for example, in the motor vehicle Ubatt = 12 volts. A first switching means S1, which is symbolically represented as a simple controllable switch, is shown in

Row to the first solenoid coil SP1 is assigned to a current-controlled switching output stage 2 and is opened and closed by a control signal Al / 2 thereof. In the circuit of the first magnetic coil SP1 there is also a current measuring element, which in FIG. 1 is in series with the first

Switching means S1 is resistance R _sens , the voltage dropping across this resistance R _{sens being} proportional to the current ISP1 of the circuit flowing through it first magnet coil SPl.

A first extinguishing means, for example in the form of a Zener diode ZD1 with the Zener voltage U _ZD1 , is connected in parallel with the first switching means S1 and the current measuring element R _sens .

Alternatively, an RC deletion can be provided. The first extinguishing agent ZD1 is used for quickly switching off the current ISP1 through the first magnet coil SP1, as will be explained in more detail below. Furthermore, a holding circuit formed by a control signal l / l openable and closable by the current-controlled switching output stage 2 and a diode and a diode is connected in parallel to the first solenoid SPl, which serves to hold the open state of the injection valve when the first switching means S1 is open, as explained in more detail below.

In addition, in series with the second magnet coil SP2 there is a second switching means S2 which can be opened and closed by a control signal A2 and to which a second extinguishing means in the form of a Zener diode ZD2 is connected in parallel. The second

Switching means S2 is actuated by an uncontrolled simple switching output stage 3. The Zener diode ZD2, which is located in parallel with the second switching means S2 and serves as a second extinguishing means, is used for quickly switching off the current ISP2 through the second magnet coil SP2, as will be explained below.

As an alternative to the preferred circuit configuration shown in FIG. 1, it is also possible to operate the double coil injection valve 1 in other configurations with two simple switching output stages without current control. The current reduction of the holding phase described below is then not possible. The function and mode of operation of the circuit according to the invention of the electromagnetic double-coil injector described and shown in FIG. 1 are described below using the signal-time diagram shown in FIG. 2A-2E show the time sequences of the control signal A2 for the second switching means (FIG. 2A), the control signal Al / 2 for the first switching means S1 (FIG. 2ß), the control signal Al / 1 for the holding circuit (FIG. 2C), of the differential current Id = ISP1 - ISP2 of the currents through the first and second magnet coils SPl and SP2 (FIG. 2D) and of the individual currents ISP1, ISP2 through the first and second magnet coils SPl and SP2 over a total in four phases, phase 1, phase 2, Phase 3, phase 4 divided

Open-hold-close cycle from a time tO to a time t6 is shown. The description below follows in the order of phase 1 to phase 4.

Charging, phase 1; tO-tl

At tO both switching means S1, S2 are switched on; A2 and Al / 2 are ON (Figure 2A and B). The currents ISP1, ISP2 rise relatively slowly

(Figure 2E). The maximum current I ₀ -ON = Ubatt / R _cu at Ubatt = 12 volts is less than I ₀ -OFF when switching off in phase 2. Both coils SP1, SP2, ie both switching means S1, S2 must therefore be relatively early before the actual opening of valve 1 can be switched on. The current in this phase can be controlled by a suitable choice of the closing time before phase 2 (opening time tl). An alternative possibility is the current regulation in both coils SP1, SP2 represents. The slope of the current rise at the time tO indicates the time constant Tau = L / R _cu . Because of the same parameters and the opposite winding of the two solenoids SP1, SP2, the differential current Id = ISP1 - ISP2 = 0 (Figure 2D).

Opening the valve, phase 2; tl-t3:

At the beginning at the time t1, the current Isp2 is quickly switched off by opening S2 with A2 = OFF with the simple switching output stage 3 with quenching by the second Zener diode ZD2 (FIG. 2A). The current gradient when switching off at time tl is determined by I ₀ -OFF = U _2D2 / Rcu and Tau = L / Rcu. With a correspondingly high quenching voltage U _{ZD2 of} the Zener diode ZD2, this current gradient is significantly higher than when switching on. The current ISP1 through the solenoid coil SPl remains switched on at the pull-in current level I ₀ -ON. Alternatively, this can also be carried out by current regulation (cf. FIG. 2E). The increase in force in the valve is proportional to the square of the differential current Id = ISP1 - ISP2 and therefore very fast (short switch-on time).

Hold phase 3 with valve open: t3-t5

The residual current Id (FIG. 2D) is lowered to the holding current level at the solenoid coil SP1 in the holding phase with the current-controlled switching output stage 2, which contains the current regulator 4, and regulated by the current control between Id-Hmax and Id-Hmin. Switching off Sl with the

Control signal Al / 2 takes place with current quenching by the first Zener diode ZDl. It also applies here that a correspondingly high Zener voltage U _ZD1 the deletion and thus the Shutdown of the current ISP1 accelerated. To hold the holding current level, the holding circuit, ie the switching means S1 / 1, is closed by the control signal Al / 1 (FIG. 2C) and S1 is opened and closed intermittently (FIG. 2ß). The holding current ISP1-H is regulated in phase 3 between ISPl-Hmax and ISPl-Hmin.

Closing the valve; Phase 4, t5-t6:

To close the valve, either only the current ISP1 through the solenoid coil SP1 is switched off or, which is not shown in FIG. 2, to support the closing process with even shorter switch-off times, the current ISP1 through the coil SP1 while simultaneously briefly switching on the current ISP2 through the solenoid coil 2 switched off. The differential current Id and thus the force effect are reversed.

Figure 2 also shows in phases 2, 3 and 4 the high negative achievable with the measures according to the invention

Current gradients, which are symbolized by the entered time constants Tau.

Due to the double solenoid provided according to the invention with a canceling effect, the actual switching-on process of the electromagnetic injection valve, i.e. its opening in phase 2 converted into a shutdown in one of the two solenoids. The rapid drop in current is determined by the dimensioning of the extinguishing voltage. Fast rise times of the force are without it

Measures increasing supply voltage can be implemented. The control of the electromagnetic injection valve is with conventional switching output stage or, as in the above preferred embodiment, can be realized with a current-controlled switching output stage. By reversing the differential current Id when switching off in phase 4, it is also possible to shorten the closing process.

A major advantage of the invention is thus the simplification of the final stage. The booster capacitor and the DC-DC converter in the control unit are omitted. This makes it easier to integrate the output stage in the control unit.

Claims

Expectations

1. Electromagnetic injection valve (1) with

Double coil, in which a first and second magnetic coil (SPl, SP2) with the same parameters on the same

Magnetic circuit are arranged, one ends of which are connected together with a supply voltage (Ubatt) and the other ends of which are individually connected to a first and second switching means (S1, S2) of an electronic control circuit (2, 3), a holding circuit (S1 / 1) is connected in parallel to the first magnet coil (SPl), characterized in that the two magnet coils (SPl, SP2) are wound in opposite directions, so that their force effects are the same

Cancel excitation current, and that the control circuit controls the switching means (Sl, S2) during a complete open-hold-close cycle (t0-t6) of the valve (1) so that

in a first phase (tO-tl) an initial charging process takes place with the valve closed, both switching means (Sl, S2) being closed when the holding circuit (Sl / 1) is inactive, and a relatively slow increase in both

Magnetic coils flowing current (ISP1, ISP2) takes place in a second phase (tl-t3), which is an opening phase of the valve, the current (ISP2) through the second magnet coil (SP2) is quickly switched off by opening the second switching means (S2), while the first switching means

(Sl) closed and the hold circuit (Sl / 1) remains inactive,

during a third phase, a holding phase (t3-t5), the holding circuit (Sl / 1) is activated and thus the current (ISP1) through the first solenoid coil (SPl) is reduced to a holding current (ISP1-H), and

- in a fourth phase (t5-t6), the one

Closing phase, at least the holding circuit (Sl / l) is deactivated and the first switching means (Sl) is opened to close the valve.

2. Injector according to claim 1, characterized in that the control circuit adjusts the currents flowing through the two coils (SPl, SP2) in the first phase (tO- tl) by determining the closing time of the two switching means (Sl, S2).

3. Injection valve according to claim 1, characterized in that the control circuit (2, 3) flowing through the magnet coils (SPl, SP2)

Current strength in the first phase (tO-tl) is set by regulating the current flowing through both solenoids.

4. Injection valve according to one of claims 1-3, characterized in that the first switching means (Sl) first extinguishing means (ZDl) are connected in parallel, which increase the current gradient when switching off the current through the first switching means (Sl).

5. Injection valve according to one of claims 1-4, characterized in that the second switching means (S2), second extinguishing means (ZD2) are connected in parallel, which increase the current gradient when the current is switched off by the second switching means (S2) and thus the valve opening Accelerate the start of the second phase (tl-t3).

6. Injection valve according to claim 4 or 5, characterized in that the extinguishing means each have a Zener diode (ZD).

7. Injector according to one of the preceding

Claims, characterized in that a current measuring element (R _sens ) is provided in the circuit of the first magnet coil (SPl) and the control circuit (2, 3) has a current regulator (4) which is connected to the current measuring element (R- _sens ), at least to regulate the im

Circuit of the first magnetic coil (SPl) flowing current (ISP1).

8. Injection valve according to claim 7, characterized in that the current measuring element (R _sens ) an in

Series to the first switching means (Sl) is switched resistance.

9. Injection valve according to claim 7 or 8, characterized in that the current controller (4) of the control circuit (2, 3) regulates the current (ISP1) flowing through the magnetic circuit of the first magnet coil (SPl) in the second phase (tl-t3) .

10. Injection valve according to one of claims 7-9, characterized in that the current controller (4) of the control circuit (2, 3) the current flowing through the magnetic circuit of the first magnet coil (SPl) during the

Hold phase (t3-t5) by intermittent activation - deactivation of the hold circuit (Sl / 1) when the first switching means (Sl) is closed regulates between a minimum and maximum holding current (ISPl-H-min., ISP1-H-max.).

11. Injection valve according to one of the preceding claims, characterized in that the control circuit (2, 3) at the beginning of the fourth phase (t5-t6) briefly closes the second switching means (S2) when the first switching means (Sl) is opened.