EP0408962A2 - Actuators control process - Google Patents

Abstract

A method for controlling actuators in displacement machines, in particular injection pumps, valves or flat slide valves in internal-combustion engines, which are operated sequentially by being electromagnetically energised or de-energised, is improved in such a manner that it is implemented at a lower equipment cost, despite costly energy-optimised output stages. This is achieved in that the energising current is supplied to each actuator from a common output stage or a switching element which in each case selects the actuator to be operated. <IMAGE>

Description

The invention relates to a method for actuating actuators in displacement machines, in particular injection pumps, valves or flat slide valves in internal combustion engines, which are actuated sequentially by electromagnetic excitation or de-excitation.

In the case of displacement machines, an adaptable control for the inflow and outflow of the working medium is required in order to be able to optimally influence the working process in accordance with the aspects required in each case. The course of the control has a great influence on various parameters, for example the states of the working medium before, in and after the working area, the working frequency and the processes in the working area. The need for adaptable control is particularly given in internal combustion engines, since they operate unsteadily in very different operating states and a correspondingly variable positive control of the gas exchange valves is advantageous.

So far, camshafts have essentially been used to control the gas exchange valves in internal combustion engines. Variable control is only possible with very high technical effort. In addition, electromagnetic controls of gas exchange valves on internal combustion engines have become known in which the closing force is applied to the gas exchange valve by a spring, while the opening forces are generated by a correspondingly controlled electromagnet, as described, for example, in DE-OS 20 63 158.

In machines of this type, circuit arrangements for controlling a plurality of actuators of the same type are required can be controlled one after the other in time with the combustion cycles of the individual cylinders. In conventional circuits, signals are only passed on on the small signal side with the aid of multiplex technology; a separate output stage is used for each actuator after a demultiplexing process. In the case of elaborately designed output stages with current control devices, timing controls and impact detection of magnet armatures, however, the effort increases in orders of magnitude which is no longer economical with a larger number of actuators.

Each of these actuators is usually controlled by a separate circuit. However, as soon as it is ensured that several actuators do not control more than one at the same time, a common control circuit can be used for these actuators. This is desirable because it can significantly reduce the overall component effort.

The object of the invention is to provide a method for actuating actuators in displacement machines, which manages with less equipment in spite of complex energy-optimal output stages and is therefore also inexpensive.

This is achieved in a method of the type described in the introduction in that the excitation current is supplied to each actuator from an output stage via a switching element which in each case selects the actuator to be actuated.

This means that the problem of controlling the correct actuator in each case is solved in that each actuator is assigned a switching element by means of which the selection of a specific actuator is possible.

According to a preferred embodiment, it is provided that the current is supplied to the actuators via a thyristor assigned to each actuator, it being possible for only one thyristor to be switched through at a time.

According to a further preferred embodiment, it is provided that, in the presence of several output stages and a plurality of switching elements in the event of a failure of one output stage, the control is also taken over by another output stage.

• Fig. 1 zeigt im Diagramm den Stromverlauf für vier Stellglieder in Abhängigkeit von der Zeit.
• Fig. 2 zeigt eine Schaltung zur Durchführung des Verfahrens gemäß der Erfindung.
• Fig. 3 zeigt eine Schaltungsanordnung, welche eine Redundanz in der Ansteuerung der Stellglieder ermöglicht.

Embodiments of the invention are explained in more detail with reference to the drawings.

• Fig. 1 shows in the diagram the current profile for four actuators as a function of time.
• Fig. 2 shows a circuit for performing the method according to the invention.
• Fig. 3 shows a circuit arrangement which enables redundancy in the control of the actuators.

In Fig. 1 it is shown how four actuators are controlled or acted upon in succession depending on the time t with the currents I1, I2, I3 and I4, where I5 represents the total current over time.

2 shows a circuit in which four electromagnetic consumers 1, 2, 3 and 4, for example switching magnets for one actuator each, are actuated at different times via a common circuit 12 which influences the current flow and is referred to below as the output stage . The type of circuit is symbolically indicated by a transistor 5. The regulation of the current flowing to the consumers 1-4 takes place in the final stage 12, the type of regulation being irrelevant.

The distribution of the current flow to the consumers 1-4 takes place in a multiplexer 11, which has switching elements 6, 7, 8 and 9, which are controlled by a control circuit 10 in accordance with the working cycle of the internal combustion engine. It ver it goes without saying that the arrangement of transistor and thyristor with actuator can also be interchanged.

If several of the circuits shown in FIG. 2 are present, redundancy can also be achieved by means of a suitable combination, so that if one of the transistors fails, the other transistor or transistors take over its task.

A circuit arrangement of this type is shown in FIG. 3. There are two output stages 31 and 32 here, to which multiplexers 33, 34, 35 and 36 are assigned. In the normal case, output stage 31 controls consumer group 37 via multiplexer 33, while output stage 32 controls consumer group 38 via multiplexer 36.

In the event of a fault in output stage 31, output stage 32 takes over the function of output stage 31 via multiplexer 34 and, in addition to consumer group 37, also controls consumer group 38. There is a shorter period of time available for every consumer. However, this is not a problem in most cases, since unrestricted operation is no longer possible, but e.g. good emergency running properties can still be achieved in the case of the control of injection valves of motor vehicle engines.

Also in the case of circuit arrangements of the type shown in FIG. 3, there is a considerable cost advantage over the use of eight separate output stages, which would be necessary to achieve redundancy in a conventional manner.

Claims (4)

1. A method for actuating actuators in displacement machines, in particular injection pumps, valves or slide valves in internal combustion engines, which are actuated sequentially by electromagnetic excitation or de-excitation, characterized in that each actuator is supplied with the excitation current from a common output stage via a switching element, which in each case selects the actuator to be operated. 2. The method according to claim 1, characterized in that the supply of the current to the actuators takes place via a thyristor assigned to each actuator. 3. The method according to claim 2, characterized in that only one thyristor is switched through. 4. The method according to any one of claims 1-3, characterized in that in the presence of several output stages and a plurality of switching elements in the event of failure of an output stage, the control is also taken over by another output stage.

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