AU2018253640A1 - Method and apparatus for driving actuators with capacitive properties - Google Patents

Abstract

Abstract The present invention relates to an apparatus and method for intercepting and modifying a drive pulse to an actuator with the property of a capacitive load. The apparatus comprises an interceptor control unit for intercepting an original drive pulse, a dummy load with similar electrical properties as the actuator, to expose to the drive pulse, and a separate electronic drive circuit for driving the actuator. Lr El- Figure 1

Description

COMPLETE SPECIFICATION

STANDARD PATENT

Invention title: METHOD AND APPARATUS FOR DRIVING ACTUATORS WITH CAPACITIVE PROPERTIES

The following statement is a full description of this invention, including the best method of performing it known to us:

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-2METHOD AND APPARATUS FOR DRIVING ACTUATORS WITH CAPACITIVE PROPERTIES

Field

This invention relates to a method and apparatus for driving actuators with capacitive properties. The invention provides a method and associated hardware solution for modifying a preconfigured performance of actuators, for example piezoelectric actuators, which electrically display a behaviour resembling a capacitive load. Signals in and out of a given electronic control unit (ECU) are intercepted; then processed in a dedicated interceptor control unit (ICU) which in turn drives the actuators.

A common use case for this is for modifying the performance of fuel injection valves to enhance torque and power on a combustion engine.

While the invention is applicable for capacitive actuators in general, for convenience, the invention will be described with reference to its use in an automotive environment for injection modification to modify engine performance.

Background

Methods to modify engine performance that do not require hardware modifications encompass various forms of re-programming the existing ECU. However, this requires intimate knowledge of the internal memory and program structure of the ECU, plus the tools to modify these. Because of complex interactions between the ECU's subsystems it is also a complex task to make sure any code modification does not have a negative impact in other functional areas. This is compounded by the fact that modern ECUs have complex layers of diagnostic capabilities to detect any abnormal behaviour.

Methods involving additional hardware exist in various forms. Some devices intercept raw input signals like air mass flow, manifold pressure or engine speed and modify them before passing them to the ECU. That way the ECU adjusts its output not to the existing but to the emulated conditions. A disadvantage of this method is again that modern ECUs have complex layers of diagnostic capabilities to detect any abnormal behaviour, which includes checking if input signals match internal

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-3criteria or compare sufficiently close to expected behaviour determined from modelling in the ECU.

Other devices intercept the output signals of the ECU and modify these. Such a piggyback solution for injectors connects wires from the device to the injector ground circuits and/or voltage supply. This allows for extending pulses, or generating extra pulses, by driving the injector terminal(s) when the existing ECU is no longer driving the injectors..

Various applications exist that combine the above mentioned methods. However, all have in common that they rely on the ECU to provide fuel signals.

Additional complexity exists when the injection valves use piezoelectric or inductive actuators. These types of injection valves, used for example in direct injection Diesel and spark ignition engines, require sophisticated management of the drive voltage and current. Additionally the ECU controls said voltage and current, which requires feedback and interaction dependent on the electrical properties of the injection drive. Common piggyback methods cannot be applied for such systems, as extending pulses by the ICU will result in the ECU recognising a mismatch between its output and the electrical reaction of the injector driver. Usually some diagnostic reaction ensues, for example the ECU can reduce the whole engine operation to a limp home mode.

A method to overcome this problem is presented in EP 2 020 044 B1. The ECU is connected to the piezo actuator, at the same time the ICU is connected to a capacitive equivalent load. Both actuator and load get charged, and at the time the ECU triggers a discharge (which controls the end of the injection pulse), the ICU activates a change-over switch to disconnect the piezo actuator from the ECU and connect the ECU to the capacitive equivalent load. Said load is then discharged, resulting in the ECU monitoring the expected discharge current and voltage. Using a separate switch, the ICU can then discharge the piezo actuator after a predefined delay of the injection pulse. Finally the change-over switch is brought back in its initial position prior to the next drive actuation.

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-4Disadvantages of the solution presented in EP 2 020 044 B1 are the expenses for the additional switches. Also this solution depends on the ECU to charge the piezo actuator, with no means to modify the charge time or voltage/current waveform.

It is an object of the invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art or at least provide a useful alternative.

Summary

The inventive accomplishment allows for full control of the capacitive actuator by the ICU. This is achieved by separating the actuator drive outputs of the ECU from the actuator and connecting them to a dummy load with similar electrical properties as the actuator. That way the ECU can charge and discharge the dummy load without realising that it is not connected to the actuator.

The ICU then implements the actuator control using its own dedicated drive circuit. The ICU uses a dedicated control logic to determine actuator control and pulse timing. In its most common form the ICU monitors the current or voltage of the ECU to establish when pulses are triggered and ended. Based on that information the ICU drives the actuator with its own circuit, where the electrical properties of that circuit might be different from the ECU circuit. Also the ICO control logic can include additional information, for example other intercepted input and output signals from the ECU or additional sensors.

In an aspect of the invention, there is provided a method for intercepting and modifying a drive pulse to an actuator with the property of a capacitive load, comprising:

intercepting an original drive pulse;

exposing said drive pulse to a dummy load with similar electrical properties as the actuator; and driving the actuator using a separate electronic drive circuit.

In another aspect of the invention, there is provided an apparatus for intercepting and modifying a drive pulse to an actuator with the property of a capacitive load, comprising:

an interceptor control unit for intercepting an original drive pulse;

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-5a dummy load with similar electrical properties as the actuator, to expose to the drive pulse; and a separate electronic drive circuit for driving the actuator.

A detailed description of one or more embodiments of the invention is provided below, along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, io modifications and equivalents.

For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. The present invention may be practiced according to the claims without some or all of these specific details. For the purposes of clarity, technical material that is known is in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.

Brief Description of the Drawings

Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein:

Figure 1 is a schematic diagram of apparatus according to an embodiment of the present invention, depicting a candidate profile.

Detailed Description

Figure 1 depicts a typical setup, in accordance with an embodiment of the invention, with the following components:

1 ECU

ICU

Capacitive dummy load

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Monitor for monitoring the ECU voltage/current

Separate ICU control circuit

Capacitive actuator

Additional inputs

The apparatus of the invention is configured to intercept and modify a drive pulse to an actuator with the property of a capacitive load. Initially, a monitor 4 intercepts the original drive pulse. The pulse is then exposed to a dummy load 3 with similar electrical properties as the actuator 6. A The ICU control circuit 5 includes a separate electronic drive circuit which is capable of driving the actuator 6, by means of controlling the voltage and/or current to the actuator 6.

Preferably, the original drive pulse circuit (part of ECU 1) and the separate electronic drive circuit (part of ICU control circuit 5) are not connected.

The actuator pulses of the separate electronic drive circuit are timed and controlled by a dedicated control unit, contained within ICU control circuit 5. The dedicated control unit preferably processes additional input information 7, as shown in Figure 1, which can then be used to determine the actuator control. Options for the additional input information 7 are described in more detail below.

In particular, the additionally used input information 7 may include a sensor signal intercepted between the sensor and the control unit controlling the original drive pulse. The additionally used information 7 may also include:

the original drive pulse signal;

a signal represents a throttle position or other representation of a load request;

a signal representing a fuel pressure; or a signal that is intercepted is modified in the dedicated control unit before reaching the control unit controlling the original drive pulse.

As a result, the voltage/current control of the separate electronic control unit may have different values than the original drive pulse circuit.

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-7The additional inputs 7 may also be fed back to the ECU 1 in some embodiments, although this variation is not shown in the diagram of Figure 1.

In the embodiment shown in Figure 1, the dummy load 3 is a capacitor. However, in other embodiments, the dummy load 3 may be a capacitive load generated by an 5 electric circuit consisting of multiple elements with implemented control logic;

enabling said capacitive load to assume different values.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or io group of integers or steps, but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication 15 (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims (15)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

   1. A method for intercepting and modifying a drive pulse to an actuator with the property of a capacitive load, comprising:

   intercepting an original drive pulse;

   exposing said drive pulse to a dummy load with similar electrical properties as the actuator; and driving the actuator using a separate electronic drive circuit.
2. 2. Apparatus for intercepting and modifying a drive pulse to an actuator with the property of a capacitive load, comprising:

   an interceptor control unit for intercepting an original drive pulse;

   a dummy load with similar electrical properties as the actuator, to expose to the drive pulse; and a separate electronic drive circuit for driving the actuator.
3. 3. A method or apparatus as claimed in claim 1 or 2, characterised in that the original drive pulse circuit and the separate electronic drive circuit are not connected.
4. 4. A method or apparatus as claimed in claim 1 or 2, characterised in that the actuator pulses of the separate electronic drive circuit are timed and controlled by a dedicated control unit.
5. 5. A method or apparatus as claimed in claim 4, characterised in that the dedicated control unit processes additional input information.
6. 6. A method or apparatus as claimed in claim 5, characterised in that at least one of the additionally used input information is a sensor signal intercepted between the sensor and a control unit controlling the original drive pulse.
7. 7. A method or apparatus as claimed in claim 5, characterised in that the dedicated control unit uses additional input signals to determine the actuator control.

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8. 8. A method or apparatus as claimed in claim 7, characterised in that one of the additionally used signals is the original drive pulse signal.
9. 9. A method or apparatus as claimed in claim 5, characterised in that one of the additionally used signals represents a throttle position or other representation of a load request.
10. 10. A method or apparatus as claimed in claim 5, characterised in that one of the additionally used signals represents a fuel pressure.
11. 11. A method or apparatus as claimed in claim 6, characterised in that one of the additionally used signals is a signal that is intercepted is modified in the dedicated control unit before reaching the control unit controlling the original drive pulse.
12. 12. A method or apparatus as claimed in claim 4, characterised in that the separate electronic control circuit is controlling voltage and/or current to the actuator.
13. 13. A method or apparatus as claimed in claim 12, characterised in that the voltage/current control of the separate electronic control unit uses different values than the original drive pulse circuit.
14. 14. A method or apparatus as claimed in claim 1 or 2, characterised in that the dummy load is a capacitor.
15. 15. A method or apparatus as claimed in claim 1 or 2, characterised in that the dummy load is a capacitive load generated by an electric circuit consisting of multiple elements with implemented control logic; enabling said capacitive load to assume different values.