EP0945609B1 - Method and apparatus for switching an inductive load - Google Patents

Description

State of the art

The invention relates to a method and a device for switching an inductive load according to the preambles of the independent claims.

Such a method and such a device for switching an inductive load are known from DE 37 02 680 A1. This document describes a method and a circuit for controlling electromagnetic consumers. The first terminal of the consumer is connected via a switching means to ground. The second connection of the consumer is connected to the supply voltage. Furthermore, a second consumer is provided with appropriate circuitry. In each case the first terminal of a consumer is connected via a diode with a capacitor. The capacitor can be connected by means of a switching means to the second terminal of the other consumer.

From JP-A-56061106 an apparatus for switching an inductive load is known. The first terminal of the consumer is connected via a first switching means to ground. The second connection of the consumer is connected to the supply voltage. The first terminal several consumers are connected via second switching means to ground. The second terminals of the inductors are connected to the supply voltage. In each case, the first terminals of the inductors are connected via diodes to the second terminal of the consumer.

WO 95 14162 A1, DE 195 39 071 A1 and EP 366 622 A1 each show a device for switching an inductive load having the features of the preamble of claim 1. Here, too, the first connection of a consumer is in each case via a Diode connected to a capacitor. This capacitor can be connected via a switching means to the second terminal of the consumer. In this device, the released when switching off a consumer Energy cached in a capacitor and used again in a subsequent power-up.

Object of the invention

The invention has for its object to provide in a method and apparatus for driving an inductive load as simple as possible a device in which accelerates the switch-on and the total energy consumption is minimized.

Advantages of the invention

With the procedure according to the invention, a simply constructed device is provided in which the switch-on process is accelerated and the total energy consumption is minimized.

Advantageous and expedient refinements and developments of the invention are characterized in the subclaims.

drawing

The invention will be explained below with reference to the embodiments shown in the drawing.

FIG. 1 shows a first embodiment, FIG. 2 shows various signals applied over time t, FIG. 3 shows an embodiment with an additional inductance, FIG. 4 shows an embodiment with a storage capacitor, FIG. 5 shows an embodiment with a bridge circuit and FIG. The embodiments illustrated in FIGS. 3 to 6 are not exemplary embodiments of the invention.

Description of the embodiments

Solenoid valves are often used to control the amount of fuel to be injected. To ensure accurate fuel injection, the solenoid valves must switch quickly. Fast switching in solenoid valves can be achieved by applying an increased voltage at the beginning of the drive.

When used in motor vehicles, such increased voltage is only conditionally available.

According to the invention, it is provided that the voltage peak occurring when switching off an inductance is used to accelerate the switching on of the load. In Figure 1, the essential elements of such control are shown as a block diagram.

A controller is designated 100. This processes the output signals of various sensors 110. Based on these sensor signals, it controls the fuel injection by controlling various solenoid valves. Solenoid valves, also referred to as inductive loads, are designated EV1, EV2, EV3 and EV4. In the illustrated embodiment, it is an internal combustion engine with four cylinders. However, the procedure according to the invention is also applicable to internal combustion engines with different numbers of cylinders, in which case a corresponding number of consumers EVN is to be provided.

The first consumer EV 1 is connected to a supply voltage Ubat for a forward-biased diode D1. Accordingly, the consumer EV2 is connected via a diode D2, the consumer EV3 via a diode D3 and the consumer EV4 via a diode D4 with the supply voltage Ubat in combination. In each case, the anodes of the diodes D1 to D4 are in contact with the supply voltage and the cathodes are in contact with the first terminal of the consumers EV1 to EV4. In each case a capacitor C1, C2, C3 and C4 is connected in parallel with the diodes D1 to D4.

The second terminal of the consumers EV1 to EV4 is in each case via a switching means T1, T2, T3 and T4 in contact with a ground terminal. In the illustrated embodiment, the switching means are formed as transistors. The control terminals of the switching means are acted upon by the controller 100 with drive signals.

Furthermore, the second terminals of the consumers are in each case connected via at least one diode to the first terminal of a further consumer. Thus, the second terminal of the consumer EV1 is connected via a diode D12 to the first terminal of the consumer EV2. Likewise, the second terminal of the consumer EV1 is in contact with the first terminal of the third consumer EV3 via a diode D13.

Accordingly, the second terminal of the second consumer EV2 via the diodes D23 and D24 with the first terminal of the third and the fourth consumer in contact. The second terminal of the third consumer EV3 is connected via diodes D31 and D34 to the first terminal of the first consumer EV 1 and the fourth consumer EV4 in contact. The second terminal of the fourth consumer EV4 is connected via diodes DV and DV2 with the first terminal of the first and the second consumer in contact.

The diodes D12, D13, D24, D23, D31, D34, D41 and D42 are each connected so that their anode is connected to the second terminal of a consumer and the cathode to the first terminal of another consumer.

In the illustrated embodiment, each of the second terminal of a consumer via two diodes in contact with the first terminal of two other consumers. It can also be provided that the second terminal of each consumer is connected via diodes to the first terminals of all other consumers.

In FIG. 2, various signals are plotted over time t. In subfigure 2a) the drive signal for the transistor T1, in the second subfigure 2b) is the current I1 flowing through the first consumer EV1, in subfigure 3c) is the drive signal for the switch T2 and in subfigure 2d) that through the second consumer flowing current 12 applied.

In the following, the mode of operation of the embodiment shown in FIG. 1 will be clarified with reference to FIG. For the sake of simplicity, it is envisaged that the consumers will only be connected to another consumer via one diode.

In the illustrated embodiment, the consumer EV2 is to be controlled at the time t2. For this purpose, at time t1, which is shortly before time t2, the first consumer EV 1 is energized. This means that the switching means T1 between the times t1 and t2 is controlled such that a current I1 via the diode D1, the first consumer EV1 and the switching means T1 flows. The period t1 to t2 is selected so that the current 11 flowing through the consumer EV1 is insufficient to change the state of the consumer EV1. In a first phase, which is defined by the times t1 and t2, the first consumer is energized.

At time t2, at which the consumer EV2 is to be controlled, the switching means T2 is controlled so that it releases the current flow and the switching means T1 so that it blocks the flow of current. This has the consequence that the energy stored in the consumer EV1 changes over from the consumer EV1 to the consumer EV2, that is to say the current 11 causes an induction voltage, which is conducted via the diode D 12 into the consumer EV2.

The consequence of this is that the current 12 rises very rapidly from the time t2 and the consumer EV2 very quickly goes into its new state. In a second phase, which is defined by the times t2 and t3, the energy stored in the first consumer EV1 is transferred to the second consumer EV2.

At time t3, the usual current regulation is then transferred or, as in the illustrated embodiment, the current is lowered to the holding current. In a third phase, which begins at time t3, only the second consumer EV2 is energized. In this phase, the current flows through the diode D2, the consumer EV2 and the switching means T2 to ground. The consumer EV1 no longer flows electricity.

At time t4, the drive for the switching means T2 is withdrawn, this means that the current 12 drops to 0. The consumer EV2 returns to its original state.

At time t5, the consumer EV2 takes over the energy storage for the fourth consumer EV4. At time t6, the next consumer, in particular EV4, is then switched on. It is particularly advantageous that by means of a suitable cascading of the output stages, in each case several consumers take over the energy storage for the other.

In this embodiment shown in Figure 1 each serve several consumers as energy storage for another consumer.

The embodiments described in the following figures are not exemplary embodiments of the invention. In Figure 3 is an embodiment shown, in which an additional inductance is provided, which serves as an energy storage.

Already described in Figure 1 elements are designated by corresponding reference numerals. The individual consumers EV1 to EV4 are connected via a respective switching means T1 to T4 to ground. The first terminals of the consumers EV1 to EV4 are connected to the cathode of a diode D11 and a second terminal of a capacitor C11 in combination. The anode of the diode D11 and the first terminal of the capacitor C11 are in contact with a supply voltage Ubat.

The supply voltage Ubat is connected via an inductance I10 and a switching means T10 to ground. The switching means T10 is also controlled by the controller 100. The connection point between the switching means T10 and the inductor I10 is connected via a diode D10 to the common terminal of all consumers EV1 to EV4 and the diode D11 and the capacitor C11 in contact.

The inductance I10 is designed so that it can store very quickly, for example within a millisecond, sufficient energy to enable a rapid switching operation of a consumer.

It is particularly advantageous if the diode D10, D11 and the capacitor C11 together with the inductance I10 and the switching means T10 are combined to form a memory module, which is identified by a dashed line.

The mode of operation essentially corresponds to the mode of operation of FIG. 1. The inductance 110 assumes the function of the element to be energized before the injection Consumer. In the example shown in FIG. 2, this means that the switching means T10 are driven in the same way as switching means T1.

Before one of the consumers is to be controlled, the switching means T10 is closed, so that in the inductance I10, the current increases and is stored in energy. At the time when the consumer is to be turned on, the switching means T10 is transferred to its locked state and the energy from the inductor I10 commutated to the capacitor C11 and increases the supply voltage for a short time, so that the consumer opens faster. Since only one consumer at a time must be controlled, a memory module can supply all consumers.

Before driving a consumer, the inductance I10 is briefly energized and reloaded when switching off energy into the respective consumer.

It is particularly advantageous that the load I10 can be energized for a longer period of time and thereby absorbs more energy than a load in the embodiment according to FIG. 1.

An advantage of this embodiment is that no current limit must be such that when charging the energy storage of the corresponding consumer does not respond. The design of the energy storage module can be done so that a fast energy storage is possible. By combining different elements in a memory module, which is located near the consumer, the amount of wiring is reduced. Furthermore, the number of components is reduced.

In both embodiments, it is provided that a first terminal of the consumer via a first switching means is connected to ground. A second terminal of the consumer is connected to a supply voltage. A first terminal of an inductance can be connected to ground via a second switching means. A second terminal of the inductor is connected to the supply voltage. The first terminal of the inductor is connected via a diode to the second terminal of the consumer in connection. The controller controls the switching means in such a way that the energy released by the inductance when the current flow is interrupted is used to switch the load.

The two embodiments differ essentially in that in the embodiment of Figure 1 more consumers are used as inductors. In the embodiment according to FIG. 3, an additional inductance is provided.

FIG. 4 shows a further circuit for fast, accurate control of output stages. The spools of injectors are again labeled EV1, EV2 and EV3. In the illustrated embodiments, only three consumers are shown. However, the procedure according to the invention can be used with any number of consumers. The second terminals of the consumer are each connected via a switching means T1, T2 and T3 to ground. The switching means T1, T2 and T3 are acted upon by control 100 in accordance with control signals, as in FIG.

The first terminal of the consumer EV1, EV2 and EV3 is connected via a common diode DB with battery voltage Ubat in Connection. In this case, the anode terminal is connected to the battery voltage and the cathode terminal of the diode DB to the first terminals of the consumer.

The connection point between the consumer EV1 and the first switching means T1 is connected via a diode D2C to a first terminal of a capacitor C1 in connection whose second terminal is connected to ground. The first terminal of the capacitor C1 is connected via a switching means TB with the first terminal of the consumer EV1 in contact.

Accordingly, the consumer EV2 is also connected to the capacitor C1 via a diode D3C. The consumer EV3 is also connected to the capacitor C1 via a diode D3C.

Between the first terminal of the capacitor C1 and ground, a voltage divider consisting of the resistors R10 and R11 is connected. The connection point of the two resistors is in contact with the controller 100 which also drives the switching means TB.

The switching means are shown in the illustrated embodiment as transistors. Instead of the transistors but also other switching elements, in particular field effect transistors or thyristors can be used.

In contrast to the embodiment according to FIG. 1, an intermediate store in the form of a capacitor is provided, in which the energy released when switching off is stored and supplied to the consumer at the beginning of the activation via a switching means.

This facility works as follows. As long as the consumers EV1 to EV3 are not controlled, these are clocked at high frequency on and off. The cut-off energy from the consumers EV1 to EV3 passes through the diodes D1C, D2C and D3C in the capacitor C1. The voltage at the first terminal of the capacitor C1 is detected by means of the voltage divider consisting of the resistors R10 and R1 and controlled by the controller to a predetermined value.

That is, the voltage across the capacitor C1 exceeds a predetermined value, there is no clocking of the consumer. If the voltage across the capacitor C1 falls below a predetermined value, the consumer is clocked. The specified voltage is much higher than the supply voltage Ubat. In the example shown, the load voltage is 12 volts and the voltage across the capacitor C1 is about 80 volts.

If, for example, the consumer EV1 is to be actuated, the switching means T1 and the switching means TB are initially transferred to the closed state. This has the consequence that a voltage of 80 volts is applied to the consumer EV1. This leads to a very rapid current increase and thus to a fast switching operation of the consumer.

If the consumer has reached its new end position, the switching means TB is opened. A current then flows via the diode DB from the supply voltage via the load and the switching means T1 to ground.

It is particularly advantageous if the switching means TB is opened when the current flowing through the consumer exceeds a certain value or the Voltage across the capacitor C1 has fallen below a certain value. As a result, the buffer C1 is not completely discharged.

The starting current and / or the holding current can be regulated to predetermined values by actuating the switching means T1.

In the control of the other consumers EV2 and EV3 will proceed accordingly. It is particularly advantageous if, as in the example shown, only one switching means TB and one diode DB are provided. But it can also be provided that a switching means TB and a diode DB is provided for each consumer.

It is particularly advantageous that a rapid current drop and thus a fast switching time is achieved when switching the consumer. Furthermore, only one capacitor is necessary.

The problem is the charging of the capacitor C1. The current that is applied to the loads must be high enough to allow a fast charging process. On the other hand, the current must not exceed a certain value, because otherwise the consumer changes its switching state.

If a consumer is used whose switching state depends on the current direction flowing through the load, then a circuit arrangement according to FIG. 5 is particularly advantageous. Such an arrangement is commonly referred to as an H-bridge circuit. In the illustrated embodiment, only one consumer EV1 is shown.

If a current I1 flows in the direction indicated by an arrow, the consumer opens. If a current flows in the direction indicated by the arrow i3, the consumer closes. If a current flows in the direction indicated by the arrow il, the consumer opens.

The consumer is connected with its first terminal via a switching means T15 to a first terminal of a capacitor C1. Further, the first terminal of the consumer EV1 is connected to ground via a switching means T45. The second terminal of the consumer EV1 is connected to ground via a switching means T25 and to a supply voltage Ubat via a switching means T35.

The supply voltage Ubat is further connected via a diode D1B with the capacitor C1 in contact. Likewise, the first terminal of the consumer EV1 is connected to the capacitor via a diode D1C. The cathodes of the diodes D1B and D1C are respectively connected to the first terminal of the capacitor C1. The second terminal of the capacitor C1 is in contact with ground.

The switching means T115, T125, T35 and T45 are acted upon by a controller 100 with drive signals. To open the consumer, the switching means T15 and T25 are driven so that they release the flow of current in the direction i1. Due to this current flow opens the consumer. The switching means T25 corresponds according to its function to the switching means T1 in the embodiment according to FIG. 4. The switching means T15 corresponds according to its function to the switching means TB in the embodiment according to FIG.

By driving the switching means T35 and T45, a current flow direction 13 is effected, which closes the load. The switching means T45 corresponds according to its function to the switching means T1 in the embodiment according to FIG.

It is particularly advantageous that the increased voltage which is applied to the capacitor C1 is used to open the load. If the voltage across the capacitor C1 falls below the battery voltage, then the supply of the load from the supply voltage Ubat.

The act of recharging the capacitor C1 is by means of the switching means D35 and T45 which induce a current flow which closes the load. As a result, a much higher current can be used because there is no danger that the consumer opens uncontrollably.

A particularly advantageous embodiment is obtained when the diode D1B is arranged as shown in Figure 4 between the supply voltage and the first terminal of the consumer. In this case, a shared memory can be used for all consumers.

FIG. 6 shows a further embodiment in which the clocking takes place in such a way that a current flows which results in a closing of the load. In FIG. 6a, a solenoid valve with two windings W1 and W2 and the magnet valve needle 666 is shown schematically. If the winding W1 is energized, the consumer opens, the winding W2 is energized, then closes the consumer.

FIG. 6b shows the essential elements of the control circuit necessary for this purpose. The two coils are connected together with the supply voltage Ubat. About each switch T11 or T12, the coils with Mass connected. The switching means are controlled by a controller 100. These switching means correspond to the switching means T1 in the embodiment of Figure 4. The other elements, in particular the capacitor C1 and the diodes are not shown in Figure 6.

It is particularly advantageous if this arrangement is realized in accordance with FIG. 4, that is to say the switching means T11 corresponds to the switching means T1 and the consumer EV1 corresponds to the turn W1. In this case, by controlling the switching means T12 night records achieved. It is also particularly advantageous in this device that when loading the capacitor, the closing function of the consumer is used. The flow of current is released in such a way that the consumer remains in its safe state.

In injection systems, which are used for example in self-igniting internal combustion engines, an injection takes place when the controlling solenoid valve is closed. In this case, the night action is such that the valve remains in its open position or moves to its open position. This means that night-time clocking takes place so that the flow of current transfers the consumer to a safe state.

The current flow through the load is repeatedly released and interrupted in times when it is so controlled that it is in a safe state, wherein the energy released when the current flow is interrupted is stored in a capacitor. The flow of current is released so that the consumer remains in its safe state. This means that the drive is so short that it is not sufficient for switching, or the Electricity flows in a direction that keeps the consumer in its safe position.

Claims (4)

1. Apparatus for switching at least one inductive load, in which a first connection of the load can be connected to earth via a first switching means and a second connection of the load is connected to a supply voltage, a respective first connection of a plurality of further inductive loads being able to be connected to earth via a second switching means and a respective second connection of the inductance being connected to the supply voltage, characterized in that the first connections of the plurality of further loads are directly connected to the second connection of the load via diodes, and provision is made of means which drive the switching means in such a manner that the energy which is released when the flow of current through the further loads is interrupted is directly used, without buffering, to switch the load.
2. Apparatus according to one of the preceding claims, characterized in that a further diode is connected between the supply voltage and the second connection of the load.
3. Apparatus according to Claim 2, characterized in that a capacitor is connected in parallel with the further diode.
4. Method for switching at least one inductive load, a first connection of the load being able to be connected to earth via a first switching means and a second connection of the load being connected to a supply voltage, a first connection of a plurality of further inductive loads being able to be respectively connected to earth via a second switching means and a respective second connection of the further loads being connected to the supply voltage, characterized in that the first connections of a plurality of further loads are directly connected to the second connection of the load via diodes, and the switching means are driven in such a manner that the energy which is released when the flow of current through the inductances is interrupted is directly used, without buffering, to switch the load.

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