WO2013033789A1

WO2013033789A1 - A method and system for monitoring, control and/or diagnosis of a solenoid

Info

Publication number: WO2013033789A1
Application number: PCT/AU2012/001075
Authority: WO
Inventors: Marc Alexander; Mark Adrian GEARING
Original assignee: Techlynx Holdings Pty Ltd
Priority date: 2011-09-09
Filing date: 2012-09-10
Publication date: 2013-03-14

Abstract

The present invention relates to the field of the control, monitoring and performance analysis of a solenoid. In one particular form, the present invention relates to electromechanical solenoids, such as fuel injectors, which are used to deliver metered amounts of fuel to an engine. In another form, the present invention relates to solenoid valves, such as pneumatic or hydraulic actuators which are used in control of hydraulic or pneumatic systems. In yet another form, the present invention relates to rotary solenoids, which are used to rotate an actuator. In still another form, the present invention relates to solenoid contactors, which are used in relays and electrical power switching. In still another form, the present invention relates to electromagnetic propulsion, such as solenoid and coil propulsion systems which deflect a ferromagnetic core or projectile.

Description

A METHOD AND SYSTEM FOR MONITORING, CONTROL AND/OR

DIAGNOSIS OF A SOLENOID

FIELD OF INVENTION

The present invention relates to the field of control, monitoring, diagnosis and performance analysis of a solenoid.

In one particular form, the present invention relates to electromechanical solenoids, such as fuel injectors, which are used to deliver metered amounts of fuel to an engine.

In another form, the present invention relates to solenoid valves, such as pneumatic or hydraulic actuators which are used in control of hydraulic or pneumatic systems.

In yet another form, the present invention relates to rotary solenoids, which are used to rotate an actuator.

In still another form, the present invention relates to solenoid contactors, which are used in relays and electrical power switching.

In still another form, the present invention relates to electromagnetic propulsion, such as solenoid and coil propulsion systems which deflect a ferromagnetic core or projectile.

As wiil become apparent, the present invention has broad application and thus the particular forms noted above are given only by way of example, and the scope of invention should not be limited to only these forms.

It will be convenient to hereinafter describe the invention in relation to electromechanical solenoids, such as fuel injectors, however it should be appreciated that the present invention is not limited to that use only.

BACKGROUND ART

Throughout this specification the use of the word "inventor" in singular form may be taken as reference to one (singular) inventor or more than one (plural) inventor of the present invention.

It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor's knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein.

To operate a solenoid, for example an electromechanical fuel injector solenoid, a voltage is presented across the solenoid to begin the actuation and movement of the solenoid device. The magnetic field then grows until its strength is able to produce physical movement of the solenoid actuator or mechanical part.

One type of solenoid is an inductive electromagnetic device which has some rise time delay after it is energised and before the current builds up to a sufficient level for the solenoid actuator to move. Often this solenoid current is measured and compared to reference values in a simple on/off fashion by discrete comparator circuitry, to provide peak, hold detection and basic diagnostic functions.

Solenoid coils are generally driven in one of two modes:

Saturated:

The output driver is on 100% and the solenoid coil resistance is high enough to not require limiting or control of the solenoid current. This has advantages in the simplicity of the driving circuit but disadvantages in the slower time taken for the solenoid actuator to open. In some applications the saturated method cannot be used as the solenoid will not operate against higher force or pressures without a higher peak current being provided. If protection and diagnostics are required then a rudimentary current comparator and optional voltage sensing is typically used for short circuit and open circuit detection. Figure 1 illustrates example waveforms associated with saturated mode operation of a solenoid.

Peak and Hold:

The output driver is on 100% until a measured peak current is reached, then a reduced hold current is selected by the control logic to maintain the solenoid energised state with a reduced energy level. Figure 2 illustrates example waveforms associated with peak and hold linear current control mode operation of a solenoid, and reference is made particularly to the current waveform illustrated. The peak and hold solenoid coil resistance is often significantly lower than the saturated coil type, permitting hig peak currents to be used initially then requiring a smaller hold current to be used to prevent the solenoid overheating for extended durations activated. Peak and Hold mode has advantages in the speed, consistency and reliability of the actuator opening or moving but disadvantages in the complexity and parts count of the drive and control circuitry.

Some lower cost designs remdve the current sensing entirely and rely on pre-calibrated peak and hold drive pulses at the sacrifice of adaptability and diagnostic functions. Figure 3 illustrates example waveforms associated with peak and hold, pulse width modulation current control mode operation of a solenoid and 31 represents clamp released, where a voltage limit circuit clips the de-energising spike.

Unless a fixed pre-programmed peak and hold pulse timing is used, current sensing is required for the peak and hold comparator detection circuitry to operate. A detection circuit and logic is often used for simple protection against and reporting of short circuit and open circuit faults.

For example, a common peak and hold fuel injector driver circuit consists of 4 to 8 channels of identical circuits containing driver transistors, damp and feedback diodes and components, current sensing element and amplifier, 2 comparators for peak and hold detection, 2 adjustable or set voltage levels into the comparators, and a supervisory and control circuit for control of the solenoid peak and hold currents and diagnosis of faults.

The diagnostic functions of prior art typically consist of Boolean flags for fault reporting of open and short circuit electrical events, and, if an analog to digital converter is in use, it provides only a single electrical current reading. Performance data and the current and voltage waveforms of the actual solenoid driving and control events as shown above are not monitored or provided by conventional prior art solenoid driver circuits.

In AU 2009245861 a method of detecting where the tell-tale movement event is disclosed, but it does not address the problem of the location in time of the solenoid movement, which is considered an important diagnostic tool. The present inventor(s) has also realised that:

prior art solenoid control circuits, while being satisfactory in a basic method of operation in prior art, lack significant ability in controlling and monitoring the performance of the solenoid actuation;

the measurement of solenoid current used in conventional solenoid driver circuits which often use discrete amplifier and/or comparator devices lack the ability to measure waveforms accurately enough;

prior art solenoid driver circuits lack the ability to capture and present for display the solenoid current and voltage waveforms readily discernable by an operator;

Prior art driver circuits operate, in general, on preset timing and signal driving based on 'factory induced' settings.

prior art solenoid driver circuits which use amplifier and/or comparator devices have a relatively high parts count and cost due to the components used by the many discrete current/voltage comparator and voltage reference circuits in conventional solenoid drivers;

diagnosis of the correct functioning of certain parts of a solenoid driver circuit is difficult or even not possible in prior art solenoid driver circuits; prior art solenoid driver circuits are primarily designed for on-off logical switching or linear current control operations and have a limited range of adjustment and diagnostic ability or fixed timing control from up to two current sense comparator levels;

prior art solenoid driver circuits utilising the saturated method of control have limitations to their functionality, requiring current sensing only for open and short circuit detection logic without the ability to measure or act upon current waveforms while the solenoid is energised;

prior art solenoid driver circuits utilising the peak and hold method of control have limitations to their functionality, requiring current sensing only for peak and hold current tripped and open and short circuit detection logic without the ability to measure or act upon current waveforms while the solenoid is energised. • prior art circuits are unable to dynamically adapt to changing electrical or environmental conditions that may affect the operational characteristics of the solenoid controlled.

The present inventor(s) has also realised that other problems exist with prior art solenoid control and/or monitoring systems, such as:

• the monitoring of a fuel injector or solenoid's electrical and physical performance whilst in operation;

• monitoring stuck, sticky or faulty fuel injector or solenoid actuator movements;

• diagnosis of a subset of electrical faults in fuel injectors or solenoids, which go undetected by sim le short/open circuit tests;

• a general lack of visibility and monitoring of the true 'opening^* event of a fuel injector or solenoid actuator; (expand here with reference to the extremely accurate metering/delivery based on the knowledge of the actual time of the opening event)

• diagnosis of a faulty solenoid clamp circuit which go undetected by prior art. If this part of the solenoid drive circuit is faulty and stuck-on, then the solenoid may stay open longer, for example delivering more fuel than desired in the operation of a fuel injector, or if the solenoid flyback clamp circuit is faulty and stuck-off, the rest of the circuit may be damaged by the possibility of higher voltage pulses;

• diagnosis of faulty voltage limit components of the solenoid drive circuit which go undetected by prior art; and

• diagnosis of shorted coil turns, weak coils, open circuit and / or closed circuit conditions of the solenoid.

SUMMARY OF INVENTION

An object of the present invention is to provide an improved diagnostic and/or display apparatus and/or method associated with the operation of a transducer(s).

It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems. In a first aspect of embodiments described herein there is provided a method of and/or apparatus for providing electrical waveforms associated with at least one transducer, comprising monitoring electrical signals associated with the transducer, and via an Analog to Digital Converter (ADC) to provide a first representation of a waveform in real-time; storing the first representation of the at least one waveform in memory and providing the first representation for further analysis.

In another aspect of embodiments described herein there is provided a method of and/or apparatus for diagnosing the operation of a transducer, comprising performing any combination of the method disclosed herein, and adjusting the operation of the transducer based on an analysis of the aforementioned method performed.

In yet a further aspect of embodiments described herein there is provided a method for and/or transducer control system, comprising transducer driving means adapted to provide as an output, a signal for controlling operation of a transducer, in response to an input signal and an Analogue to Digital Converter, which in response to a transducer sensing signal, provides as an output, waveform(s) representing the real-time operation of the transducer.

Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.

In essence, embodiments of the present invention stem from the realization that a relatively high speed analog-to-digital converter (ADC) can be ' used in association with various coil and solenoid systems and or drivers to directly measure the solenoid current (and optionally voltage) at a speed sufficient to enable capture and act upon the signals directly by a programmable digital device, thus replacing prior art sensing, reference and comparator components, reducing the circuit component count and providing new features.

To this end, prior art driver circuits operate in general on preset timing and signal driving based on factory induced' settings. In the present invention, through the use of ADC, the performance of a coil and/or solenoid may be quicker, and the digital information of the ADC may be stored in suitable memory, and this can then be recalled/displayed to show monitoring/display information of the coil and/or solenoid performance. Advantages provided by the present invention comprise the following: enabbs ADC measurements directly for solenoid control strategies including peak and hold current control methods, thus replacing many components and discrete comparator circuits that are traditionally used in solenoid control;

storage and review of high-speed ADC conversions allows enhanced diagnostic and monitoring in both real-time and historical timeframes reduced analog component count, compared to equivalent prior art circuits Analysis of the solenoid current and/or voltage waveforms for telltale markers relating to faulty solenoid operation, time of actuator movement and time to reach current trip events. Thus, providing new solenoid monitoring and reporting ability;

Store in memory the captured current and/or voltage waveform in real time. Thus, permitting capture and display of one or more solenoid performance waveforms to a controller or operator;

Communicate to a controlling module or operator the diagnostic status and captured waveforms taken from one or more channels of solenoid driver, for example to overlay multiple solenoid waveforms for comparison or inspection by an operator or module communicating with the invention; Provide the traditional solenoid driver functionality of open, grounded and short circuit detection, and flagging of these faults for a controlling device to use;

High speed measurement of the solenoid current and voltage by a connected circuit for decision, control and analysis;

monitoring capability of the physical movement of the injector/solenoid's actuator by analysis of solenoid electrical signals;

comparison of the physical movement event of Ihe actuator to reference values or other identical solenoids connected;

monitoring of the electrical properties of the injector/solenoid's connection and driving coil; Displaying or analysing in real time the injector/solenoid current trace, and analysing the trace for telltale markers of actuator movement, movement location in time, and time taken to reach peak current;

Previously unseen diagnosis of mechanical actuator movements by the controlling ECU or electronic device;

Relatively instant troubleshooting and identification of faulty injectors, solenoids, issues with the fuel fluid feeding system, and any fault that may change or reduce mechanical movement of the actuator, such as, a smaller angle or longer to reach a set current level demonstrates that the coil or the connection to it is a high impedance; coil or wiring failure is expected. A higher angle or shorter time to reach a set current level demonstrates that the coil or the connection to it is a low impedance; shorted turns within the coil is expected;

Examination of the injector/solenoid cunrent trace (with or without a voltage trace) for the telltale markers of the angle of current rise, or time taken to reach a set current level;

Detection of injector or solenoid faults that previously would go undetected and for example; would previously prompt replacement of all injectors in a vehicle or other parts swapping procedures to try and rectify without visibility;

Immediate feedback of the true physical 'dead time' of the actuator, which directly affects the actual fuel volume delivered and physical time with the actuator open;

An enhancement of the telltale physical opening event of the injector/solenoid actuator is detected and displayed or recorded as a time after electrical turn-on;

Truly accurate monitoring and adaption to the physical opening of the actuator, which allows feedback and adjustments to be made for example, to the physical fuel flow value desired out of a fuel injector, including compensations for wear, drift and temperature factors; Calibration of injector/solenoid offset or dead time values that are usually compensated for by a variety of fixed, estimated tables within the ECU or controller;

Displaying or analysing in real time the injector/solenoid voltage trace, and analysing the trace for telltale markers of correct activation and release of the clamp circuit during the injector/solenoid opening and closing event; Automatic diagnosis or display of less common faults in the injector/solenoid drive circuitry;

Normally this examination would be done by an experienced electronics technician with an oscilloscope and a full understanding of the electronic components in the drive circuitry. The addition of this invention's features allow both the ECU/device itself, or any operator with suitable software connected to the ECU/device to have a 'virtual' oscilloscope on the current and voltage traces of each injector channel, comparing them to each other and instantly examining them for problems. Usually this part of the drive circuitry is tested once only at the ECU's end of production line test, and not tested afterwards or in operation in the field.

examination of the voltage trace for the highest voltage reached at telltale locations, if the voltage limit is exceeded then the voltage limit components in that driver channel are faulty;

Very high speed analysis of short circuits and reaction function within the controller, to remove the output signal if the measured current 'spikes' up to a set level within a very short (programmable) timeframe;

Fault tolerance and reporting of injector/solenoid output shorts substantially without damage to any components;

Measurement and reporting of the 'tripped' state above a set current level at a given (programmable) time after the injector/solenoid output channel is turned on, and with a minimum time limit to ensure no false detections are reported with short duration pulses;

Reporting of open circuit fault(s) in the injector/solenoid output channels; A reduction in circuit parts count, cost and complexity whilst providing these new feature advantages. • Relatively large reduction in solenoid control tolerance (drift), ensuring more accurate solenoid opening and closing response (has accuracy advantages in metered injector fuel flow for example)

• Relative cost reduction in component count

· Relatively smaller, more efficient pcb size and layout through removal of many discrete components, comparators and voltage references

• Adaptability of solenoid current control strategies to new data, current profiles and voltage profiles that prior art designs do not see.

Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description.

Throughout the specification, 'solenoid' refers to a variety of transducer device(s) that converts energy into movement (for example, linear motion) such as, without limitation, solenoid coil or a electromechanical solenoid, pneumatic or hydraulic actuator, rotary solenoid, and/or electromagnetic propulsion, such as solenoid and coil propulsion system which deflect a ferromagnetic core or projectile.

BRIEF DESCRIPTION OF THE DRAWINGS

Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:

Figure 1 illustrates saturated mode simulated waveforms (if viewed with an oscilloscope) as associated with the prior art;

Figure 2 illustrates Peak and Hold mode simulated waveforms (If viewed with an oscilloscope) and Current control being Linear as associated with the prior art; Figure 3 illustrates Peak and Hold mode simulated waveforms {if viewed with an oscilloscope) and Current control being PWM as associated with the prior art;

Figure 4 illustrates an overall system schematic of an embodiment of the present invention;

Figure 5A illustrates two solenoid waveform in accordance with an embodiment of the present invention;

Figure 5B illustrates two solenoid waveforms in accordance with an embodiment of the present invention, by in which one waveform illustrates a st icking solenoid ;

Figure 5C illustrates two solenoid waveforms in accordance with an embodiment of the present invention, by in which one waveform illustrates a slow or sticking solenoid;

Figure 6 illustrates solenoid waveform markers in accordance with an embodiment of the present invention;

Figure 7 illustrates operation of a clamp flyback recirculation circui associated with the prior art;

Figure 8 illustrates operation of a clamp flyback recirculation circuit associated with an embodiment of the present invention;

Figure 9 illustrates operation of a voltage limit circuit associated with the prior art;

Figure 10 illustrates operation of a voltage limit circuit associated with an embodiment of the present invention;

Figure 11 illustrates a solenoid waveforms in accordance with an embodiment of the present invention;

Figure 2 illustrates a comparison of the number of components used in a prior art design and an embodiment of the present invention;

Figure 13 illustrates an example of the display associated with an embodiment of the present invention;

Figure 14 illustrates an example of the display associated with the mixing of the current and voltage waveforms in accordance with an embodiment of the present invention, and Figure 15 illustrates a flowchart associated with an operational description of an embodiment of the present invention.

DETAILED DESCRIPTION

With reference to Figure 4, this invention serves to replace conventional sensing and control components and circuitry with a modern high speed analog to digital converter (ADC) directly connected to the solenoid sensing signals and feeding a programmable digital device which provides control and monitoring functions in its program (eg. a microcontroller or FPGA) from the high speed ADC readings. The speed of the analog to digital converter and digital device is sufficient to replace the sensing, switching and comparator functions that were previously done with discrete devices or fixed operation controllers.

Furthermore, the current and voltage waveforms that are now measured and captured digitally at a high speed are used to provide a number of new features.

Prior art solenoid control and monitoring circuits that measure current typically have a current sensing element connected in series with the solenoid coil. Usually this sensing element is a resistor connected in series with the solenoid coil. In these prior art circuits, the voltage across the resistor, which is proportional to the solenoid current, is conditioned and connected to one or more voltage comparators or an analog to digital converter. Solenoid current monitoring circuits of this type typically monitor or report the solenoid current as a single current value or comparator states without any information or waveforms of the solenoid energising and de-energising process.

By converting signals at high speed directly into the digital domain the present inventors have realised that many previous component parts including linear comparator IC's, reference voltage generators and amplifiers are now replaced with a reduced parts count, programmable digital solution fed by the signal data.

In Figure 4, 41 represents Control Signal(s), 42 a Voltage Signal, 43 high speed digital current and voltage readings and 44 a Current Signal.

The real time control program running in the programmable device (eg. a microcontroller or FPGA) provides adjustable solenoid control strategies whilst also permitting in depth analysis, comparison and display of the profile of the solenoid current and voltage waveforms, and records the timing of control strategy events.

The analysis and display of the solenoid waveforms provides advantages in the diagnostics and troubleshooting of solenoid operation, for example in the automotive industry for troubleshooting fuel injector solenoid faults on multiple channels that previously required service mechanic experience and physical attention.

In the domain of the current waveform, the captured location in time of the solenoid movement can also be utilised in a feedback system to a controlling device that is accounting for solenoid 'dead time', the physical delay in actuator movement which for example, affects total fuel flow out of a fuel injector when it is energised. This permits more accurate fuel metering to an engine in real time, from real solenoid performance data instead of pre-programmed fuel injector dead time or offset lookup tables.

Tell-tale markers of the time of solenoid movement, time to reach hold current, time to reach peak current, and voltage waveforms are now utilised to show numerical and graphical data on solenoid performance. The markers indicating angle of the current rise waveform can be utilised to also detect and report on solenoid coil faults of low or high impedance windings and shorted turns. Figure 5A illustrates typical operation waveforms of a solenoid, in which 51 represents live and offline comparisons of multiple solenoid waveforms, tm(channel): Time from energising to movement of solenoid, and tp(channel): Time from energising to peak current reached In saturated mode the time to an expected target current instead of a peak or hold current is used. In this embodiment, solenoid (A) is a slightly lower impedance than (B) though it would be expected to be within solenoid waveform tolerance limits here.

Analysis of the waveforms automatically or by operator viewing can now be utilised to show that the clamp and voltage limit components are operating correctly and are not faulty. In conventional circuits there are a number of possible component faults in the clamp or voltage limit circuits that are undetectable without manual inspection of waveforms by an operator with an oscilloscope. In the application of fuel injector control and other multi-channel solenoid applications where a plurality of channels are in use the invention provides a live comparison of all operating solenoid current and voltage waveforms against each other (Like a live on-screen multi-channel oscilloscope), allowing diagnostics and performance comparison of solenoids in operation in the field, replacing the need for mechanics to perform physical isolation tests and inspection to detect faulty solenoids.

In single channel solenoid applications the captured waveforms are compared against a stored reference waveform and known performance values to provide monitoring and diagnostic functions without the need for comparison channels.

Diagnostic and troubleshooting advantages for faulty or stuck solenoids

Analysis and display of the solenoid current and voltage waveforms is an advantage as it provides diagnostics and review that would previously have been done at an electrical engineer level and have required an oscilloscope or other specialised test equipment to inspect.

For example, a common fault of fuel injectors is that they become stuck or sticky,, often caused by unwanted particles or contaminants in the fuel. The symptoms of the engine would be that it is 'running roughly' and not running on all cylinders. Conventional engine control units that have fuel injector solenoid drivers do not detect or display any kind of error related to this solenoid fault. The vehicle is required to be physically inspected by a mechanic to determine these type of faults. Automotive mechanics have to rely on their troubleshooting experience and systematically disconnect one fuel injector connector at a time, to discover which fuel injector(s) disconnected results in no change to the engine's running and performance. When they identify these injectors they now know which one(s) are faulty, stuck or slow and replacement or repair can commence. The present invention, by saving, analysing and/or displaying solenoid performance waveforms not usually inspected, is now able to provide new reports and fault codes related to the electrical and physical performance of the solenoid against reference values and/or waveforms of other solenoids in the common multi-channel applications. Figure 5B illustrates a 'stuck' solenoid. The waveform of solenoid 'Α' shows the initial movement at time lm(A), whereas the waveform of solenoid 'B' does not show a change in waveform shape, similar to solenoid Ά'. tm(channel) shows time from energising to movement of solenoid , and tp(channel) illustrates time from energising to peak current reached. Solenoid (B) is missing the tell-tale shape of solenoid movement and reaches peak current sooner.

Figure 5C illustrates a 'sticky' solenoid in which tm(channel) illustrates time from energising to movement of solenoid and tp(channel): Time from energising to peak current reached. The tell-tale shape of movement of Solenoid (B) is significantly delayed. The waveform of solenoid A' shows the initial movement at time tm(A), whereas the waveform of solenoid 'B' shows the initial movement occurring at a later time tm(B), thus indicating the possibility of a sticking solenoid.

Figure 6 illustrates solenoid waveform markers in accordance with an embodiment of the present invention. Figure 6 illustrates the areas of the waveform and what tell-tale areas will be involved in the different failure possibilities, namely 61 - Failure of voltage limit circuit will show voltage rise above limit, 62 - Failure of clamp circuit will show voltage rise above the supply voltage level when in hold mode, tm(channel): Time from energising to movement of solenoid and tp(channel): Time from energising to peak current reached.

Solenoid (B) is missing the tell-tale shape of movement and reaches peak current sooner

Diagnostic and troubleshooting advantages for solenoid driver circuit section failures

Whilst many conventional solenoid driver circuits use rudimentary current measurement to report failure of the solenoid coil or wiring connection for short and open circuit faults, there are two significant sections of most solenoid driver circuits which are not traditionally able to be checked or inspected without specialised equipment, intervention and inspection by an electrical engineer.

Clamp (flyback recirculation) section:

With reference to Figure 7, in PWM current control of prior art arrangements, the repeated release of Ihe voltage presented across the coil gives an immediate flyback voltage response which is utilised by a switchable clamp circuit to feedback this current into the solenoid coil, thus preventing its rapid closure on the brief voltage removal. In this manner an average modulated hold current is able to be managed in the solenoid coil by an efficient transistor switching device. Low on resistance and hard on-off PWM transitions prevent linear current control heat and heat related design issues. Numeral 71 illustrates clamp released, voltage limit circuit clips the de-energising spike

With reference to Figure 8, numeral 82 illustrates a situation where the Clamp (flyback recirculation) circuit has failed, repeated high energy spikes are now dissipating into the voltage limit circuit instead of recirculating in the solenoid. Numeral 83 refers to clamp released, voltage limit circuit clips the de-energising spike. After failure of the clamp circuit, the solenoid may close early instead of stay open as expected in this hold phase, more electrical noise may be generated, and the voltage limit circuit may fail from excess power dissipation of the extra high voltage spikes. The present invention sees this failure mode that is considered undetected in conventional or prior art circuits.

If the clamp circuit section has failed, the symptoms may also be that a solenoid may rapidly open and close when in the hold phase, deliver a significantly shorter opening/deflection period 81, deliver high voltage spikes 82 and electrical noise in the solenoid wiring, and possible long term overload failure of the voltage limit section.

Voltage limit section:

With reference to Figure 9, numeral 91 refers to clamp released, voltage limit circuit clips the de-energising spike. Upon final release of the voltage across a solenoid to return the solenoid to its de-energised state, conventionally the clamp circuit is disabled by the controller to allow the solenoid current and magnetic field to return to an inert state as fast as possible. The voltage spike generated by an inductor (coil) upon release can be significant, for example 200- 400 volts and generating significant electrical noise and component dv/dt and overvoltage breakdown risk. For these reasons a permanent voltage limit circuit or device is typically present in solenoid driver circuits. Typically this is a power zener diode, transient suppressor or an active voltage limitation circuit utilising the solenoid driver transistor.

With reference to Figure 10, in which numeral 101 illustrates Voltage limit circuit has failed, high voltage spikes from solenoid current removal are no longer being limited and are now reaching component damage or excessive dv/dt levels in the driver circuit. If this voltage limit circuit section has failed, the symptoms would be a solenoid that closes faster than the controller is expecting from lower recirculated current duration (for example delivering less metered fuel from a fuel injector), deliver very high voltage spikes and electrical noise in the solenoid wiring, overvoltage breakdown and future failure of the solenoid driver element and begin either a short term or long term overvoltage failure of the solenoid driver transistor and other components present on the output node.

The present inventor considers this failure mode is undetected in conventional or prior art circuits.

The present invention, by saving, analysing and/or displaying solenoid performance and waveforms not usually utilised, is now able to provide new reports and fault codes related to the failure of these previously untested sections of the solenoid driver circuit, against reference values and/or waveforms of other solenoids in the common multi-channel applications.

Solenoid or fuel injector dead-time/offset measurement and compensation

Part of the metered fluid, air or material delivery system of many solenoid operations relies upon an understanding and often pre-loaded tables in the controller for compensation of what is commonly called the 'dead-time' or 'offset¹ of a solenoid.

The dead-time is approximately the sum of the physical opening minus the closing delay time of the solenoid. When a solenoid is energised typically there is a delay before the electromagnetic field increases to a strength sufficient to move the actuator. When a solenoid is de-energised typically there is a delay before the electromagnetic field decays to a strength sufficient to release the actuator. These aspects plus physical movement time of the actuator and possible effects of a return spring or device are generally represented as a dead-time or offset value.

These compensation values are typically previously tested, calculated and stored within the controller as lookup tables or formulas approximating the solenoid response. Common lookup tables in use are indexed by solenoid operation voltage, pressure or vacuum behind the solenoid actuator, and pressure or vacuum in front of the solenoid actuator. If a solenoid is energised for less than this dead-time, no physical movement is likely to occur in the solenoid actuator.

The present invention, by saving, analysing and/or displaying solenoid performance timing and waveforms (such as illustrated in Figure 5A and Figure 11), is now able to provide real time analysis and compensation offset for the true operational dead-time/offset of the solenoid's response, thus delivering metering of solenoid controlled fluid, air or material at a level of accuracy and adaptability above conventional designs. In Figure 11 , tm represents time from energising to movement of solenoid, and td: (not shown) Time from solenoid de-energising to end of voltage limit circuit effect. In this embodiment, measuring and using tm (or deita_tm from a reference value), optionally with td, permits both real time analysis and compensation for the delay in the solenoid's movement response. This is especially useful in solenoid applications where the solenoid is a metering device and the solenoid controller or system must compensate for this delay in movement effect.

The feature can also be used to assist in the initial calibration, inspection of the movement event timing and loading of the compensation lookup tables data as described above.

Replacement of many discrete components used in conventional prior art solenoid drivers

By applying a high speed ADC and programmable device (eg. microcontroller, FPGA) to the application of direct solenoid control, many discrete and fixed function parts conventionally used are removed and replaced with a programmable solution that operates primarily in the digital domain. An example is illustrated in Figure 12. This solution seeks to use an appropriate ADC and circuit to translate the control signals into the digital domain and operate on them at high speed without any loss in control or response speed and functionality compared to conventional circuits. The processing, memory and inspection ability of the digital device is thus utilised to provide new features as demonstrated, that conventional circuits do not offer.

Storing the solenoid current and/or voltage waveforms in real time

Now that the solenoid current waveforms are measured at sufficient speed and frequency in the digital domain (in one embodiment being around 100KHz per channel), the benefits of storing these waveforms in memory include the performance analysis of the waveforms in real time, saving of the waveforms for later reference or troubleshooting, communicating the waveforms to a controlling device or operator for viewing as a single trace display or overlapping comparative waveforms especially if more than one solenoid driver channel is in operation (for exampte a 6 cylinder engine with 6 identical fuel injector solenoids). Figure 3 illustrates an example of the display associated with an embodiment of the present invention. Numeral 131 refers to communication of waveforms and/or timing, events, status to controlling device, operator, display, logging device, etc, 122 - Voltage Signal and 23 - Hig speed digital current and voltage readings.

Advantages of the current invention in using high speed ADC and digital programmable device (MCU, FPGA, etc) for direct solenoid current sensing:

• Large reduction in solenoid control tolerance (drift), ensuring more accurate solenoid opening and closing response (has accuracy advantages in metered injector fuel flow for example);

• Cost reduction in component count;

• Smaller, more efficient pcb size and layout through removal of many discrete components, comparators and voltage references;

• Adaptability of solenoid current control strategies to new data, current profiles and voltage profiles that prior art designs do not see;

• Ability to deliver all the solenoid monitoring, performance data, opening time, diagnostics and other advantages all listed in the other documents written to accompany this.

In conventional solenoid driver circuits that measure current and operate in Peak & Hold or various holding current modes, a method of sensing the current through the solenoid is used. In the important Peak & Hold methods, the current is often sensed by a low-ohm shunt resistor in the solenoid connection pathway. This current sensor has a certain tolerance in its output vs. the true current being sensed. Often this current sensor has a 1% tolerance.

In prior art discrete circuits, the current sensing element then feeds:

• An optional amplifier with usually qty 2 of 1% tolerance resistors in its gain selection. Total of 2% tolerance in operation from this section. • A method of comparing the current sense signal to two reference levels for the Peak and Hold current settings. Usually 2 comparators being fed by a device/controller fed signal, with qty 3 of 1% tolerance resistors in its Peak level setting, qty 3 of 1 % tolerance resistors in its Hold level setting. If a digital reference or digital potentiometer is used they often have 20% tolerance. If a digital-to-analog converter is used for the voltage reference instead, they are significantly more expensive and often have a combined tolerance of 3% including the reference output amplifier resistors and bit- accuracy. Total of between 3% to 20% tolerance in operation from this section.

• If an ADC is used in prior art circuits it is used to read the static current of the solenoid after it is energised, and not used for dynamic high-speed control of the solenoid's current and opening management strategy.

The present invention, by directly connecting a high-speed analog-to- digital converter (ADC) to the current sensing element with a method of low cost voltage and current sensing mixing circuit, in combination with a decoding and control strategy, eliminates 5% to 22% of the solenoid control tolerance from prior art circuits. Only the 1% current sensing element tolerance remains, along with the common 1-bit movement in the ADC reading which at 10 bits which equates to -0.1%.

The choice and selection of a very high speed ADC in combination with the current invention's monitoring, control and performance advantages forms a package of advantages in materials, size, component count, solenoid control tolerance and drift, plus the major monitoring and diagnostic advantages listed and detailed.

Mixing of the current and voltage waveforms into a single AOC signal per channel

Because the digital device controls or sees the control signals to the solenoid driver, it is possible to use a novel method of mixing the voltage signal from the solenoid with the current signal from the current sensing element into a single ADC signal, saving extra hardware and complexity. Figure 14 illustrates an example of the display associated with the mixing of the current and voltage waveforms in accordance with an embodiment of the present invention, in which 131 refers to [A] Control Signal, 132 - [B] Mixed voltage and current reading and 133 - Mixed voltage and current signal.

If the solenoid driver element/transistor is off. then the voltage present at the ADC is proportionally representative of the voltage at the solenoid driver pin, and the ADC readings can be used to construct that time section of the voltage trace waveform, whilst that time section of current waveform is generally saved as zero.

If the solenoid driver element transistor is on, then the voltage present at the ADC is proportionally representative of both the current and voltage at the solenoid driver pin, and the ADC readings can be used to construct that time section of the current waveform and voltage waveform directly.

Example operational diagram and description

With reference to Figure 15, starting with a Solenoid Control Signal input from 206, the Waveform Memory Controller 126 is triggered, and the Real Time

Control Process 128 initiates the energising of the Solenoid 100 by the Solenoid

Driver Hardware 102.

The Solenoid 100 energising process begins, and the energised monitoring procedure of the device commences.

Current Sensing 104 and Voltage Sensing 106 sections pass their respective monitoring signals to the Mixer 108, which in this example mixes both the current and voltage signals into a single signal presented to the High Speed

ADC 110.

Use of the Solenoid Control Signal 206 throughout the invention and embedded in the Waveform Memory 112 values permits modules to extract separate current and voltage signals from the mixed High Speed ADC 1 0 data.

For real time control management of the solenoid current and current modulation strategy (eg. Peak & Hold, Saturated), the high frequency per- conversion data immediately from the High Speed ADC 110 is passed directly to the Real Time Control Process 128. The trigger levels for current modulation are sensed and reported to the Real Time Control Process 128 by the Digital Data Comparators 132. Solenoid Driver Modulation Control 130 can stretch or shrink the overall energising duration in response to the Solenoid Dead Time Compensation 116 value, adapting immediately to solenoid metering and/or dead time changes.

For host side solenoid waveform analysis and diagnosis, the data from the High Speed ADC is passed to the Waveform Memory 112. The waveform memory is accessed by the Host Computer or Controlling Device 200, which in turn is utilised for display, overlay, diagnostics and status results by 202 Display, Waveform Display and 204 Diagnostic and status results.

For internal solenoid and waveform diagnosis, the captured current and voltage data presented to the Waveform Memory 112 is utilised by the Time of Solenoid Movement Analyser 114 to report the time after energising that the solenoid moved. A combination of comparative waveform data and the location in time of movement is passed onto Solenoid Dead Time Compensation 116. The solenoid dead time shift in relation to a reference waveform or time location is · passed back to Solenoid Driver Modulation Control 130, which it can utilise for stretching or shrinking the solenoid's energised duration in real time, providing new and precise sofenoid metering accuracy automatically.

Information from waveform analysis, time and event capturing by Sofenoid Metering Duration Feedback 118, Stuck, Slow, Sticky Solenoid Movement thresholds 120, Circuit Fault Detection 122 and Event Marker Detection for selected current, time and voltage trip events 124 are communicated to the Host Computer or Controlling Device 200.

The Host Computer or Controlling Device 200 uses the information provided to it above, in addition to its regular solenoid pulse and duration control method to generate and initiate a new Solenoid Control Signal 206 as required.

In this manner with a single ADC channel per solenoid and reduced parts and hardware requirements, both the voltage and current traces that would normally be seen by an electrical engineer with an oscilloscope on exposed circuit connections can be constructed and utilised by this invention to provide a variety of related functions and features.

While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.

As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive. _;

Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures.

It should be noted that where the terms "server", "secure server" or similar terms are used herein, a communication device is described that may be used in a communication system, unless the context otherwise requires, and should not be construed to limit the present invention to any particular communication device type. Thus, a communication device may include, without limitation, a bridge, router, bridge-router (router), switch, node, or other communication device, which may or may not be secure.

It should also be noted that where a flowchart is used herein to demonstrate various aspects of the invention, it should not be construed to limit the present invention to any particular logic flow or logic implementation. The described logic may be partitioned into different logic blocks (e.g., programs, modules, functions, or subroutines) without changing the overall results or otherwise departing from the true scope of the invention. Often, logic elements may be added, modified, omitted, performed in a different order, or implemented using different logic constructs (e.g., logic gates, looping primitives, conditional logic, and other logic constructs) without changing the overall results or otherwise departing from the true scope of the invention.

Various embodiments of the invention may be embodied in many different forms, including computer program logic for use with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general purpose computer and for that matter, any commercial processor may be used to implement the embodiments of the invention either as a single processor, serial or parallel set of processors in the system and, as such, examples of commercial processors include, but are not limited to Merced™, Pentium™, Pentium II™, Xeon™, Celeron™, Pentium Pro™, Efficeon™, Athlon™, AMD™ and the like), programmable logic for use with a programmable logic device (e.g., a Field Programmable Gate Array (FPGA) or other PLD), discrete components, integrated circuitry (e.g., an Application Specific Integrated Circuit (ASIC)), or any other means including any combination thereof. In an exemplary embodiment of the present invention, predominantly all of the communication between users and the server is implemented as a set of computer program instructions that is converted into a computer executable form, stored as such in a computer readable medium, and executed by a microprocessor under the control of an operating system.

Computer program logic implementing all or part of the functionality where described herein may be embodied in various forms, including a source code form, a computer executable form, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator). Source code may include a series of computer program instructions implemented in any of various programming languages (e.g., an object code, an assembly language, or a high- level language such as Fortran, C, C++, JAVA, or HTML. Moreover, there are hundreds of available computer languages that may be used to implement embodiments of the invention, among the more common being Ada; Algol; APL; awk; Basic; C; C++; Conol; Delphi; Eiffel; Euphoria; Forth; Fortran; HTML; Icon; Java; Javascript; Lisp; Logo; Mathematical MatLab; Miranda; Modula-2; Oberon; Pascal; Perl; PL/I; Prolog; Python; Rexx; SAS; Scheme; sed; Simula; Smalltalk; Snobol; SQL; Visual Basic; Visual C++; Linux and XML.) for use with various operating systems or operating environments. The source code may define and use various data structures and communication messages. The source code may be in a computer executable form (e.g., via an interpreter), or the source code may be converted (e.g., via a translator, assembler, or compiler) into a computer executable form.

The computer program may be fixed in any form (e.g., source code form, computer executable form, or an intermediate form) either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g, a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), a PC card (e.g. , PCMCIA card), or other memory device. The computer program may be fixed in any form in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and inter-networking technologies. The computer program may be distributed in any form as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web). ^'

Hardware logic (including programmable logic for use with a programmable logic device) implementing all or part of the functionality where described herein may be designed using traditional manual methods, or may be designed, captured, simulated, or documented electronically using various tools, such as Computer Aided Design (CAD), a hardware description language (e.g., Verilog; VHDL or AHDL), or a PLD programming language (e.g., PALASM, ABEL, or CUPL). Hardware logic may also be incorporated into display screens for implementing embodiments of the invention and which ma be segmented display screens, analogue display screens, digital display screens, CRTs, LED screens, Plasma screens, liquid crystal diode screen, and the like.

Programmable logic may be fixed either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), or other memory device. The programmable logic may be fixed in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and internetworking technologies. The programmable logic may be distributed as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web).

"Comprises/comprising" and "includes/including" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', 'includes', 'including' and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Claims

1. A method of providing electrical waveforms associated with at least one transducer, the method comprising the steps of:

Monitoring electrical signals associated with the transducer, and via a ADC to provide a first representation of a waveform in real-time;

Storing the first representation of the at least one waveform in memory providing the first representation for further analysis.

2. A method as claimed in claim 1, wherein a display is provided for each waveform associated with a transducer.

3. A method as claimed in claim 1, wherein the ADC is associated with control strategy of the transducer.

4. A method as claimed in claim 1, wherein the ADC is associated with diagnostic strategy associated with the transducer and the stored waveform(s).

5. A method as claimed in claim 4, wherein the waveform(s) are concurrently displayed or displayed with reference to other stored waveform(s) .

6. A method as claimed in claim 1 , wherein the display provides a ready indication of status, time of actuator movement and/or apparent faults associated with at least one transducer.

7. A method as claimed in claim 5, wherein the display provides an indication of the time of actuator movement and/or time to reach current trip levels

8. A method as claimed in claim 1 , further comprising the step of providing additional waveform(s) as an indication of the operation of circuitry associated with the transducer.

9. A method of diagnosing the operation of a transducer, the method comprising:

performing any combination of the method claimed in any one of claims 1 to 7, and

adjusting the operation of the transducer based on an analysis of the aforementioned method performed.

10. A method as claimed in claim 1 or 9, wherein the further analysis is by a user.

11. A method as claimed in claim 1 or 9, wherein the further analysis is by associated software and/or hardware.

12. A transducer control system, comprising

Transducer driving means adapted to provide as an output, a signal for controlling operation of a transducer, in response to an input signal

An Analogue to Digital Converter, which in response to a transducer sensing signal, provides as an output, waveform(s) representing the real-time operation of the transducer.

13. A system as claimed in claim 12, wherein the ADC is associated with control strategy of the transducer.

14. A system as claimed in claim 12, wherein the ADC is associated with diagnostic strategy associated with the transducer and the stored waveform(s).

15. A control system as claimed in claim 12, wherein the sensing signal is current and/or voltage.

16. A control system as claimed in claim 12, wherein the input signal is provided by an associated logic means.

17. A control system as claimed in claim 12, wherein the ADC, in its application to a fuel injector for an internal combustion engine, is adapted to operate at a per channel frequency of around 100KHz.

18. A control system as claimed in any one of claims 12 to 17, wherein the transducer is a fuel injector for an internal combustion engine.

19. A control system as claimed in claim 12, further comprising the provision of current and/or voltage signals as an input to the ADC.

20. A control system as claimed in claim 19, wherein the input is a mixed voltage and current signal(s).

21. Apparatus adapted to providing electrical waveforms associated with at least one transducer, said apparatus including:

processor means adapted to operate in accordance with a predetermined instruction set,

said apparatus, in conjunction with said instruction set, being adapted to perform the method as claimed in any one of claims 1 to 11.

22. A computer program product including:

a computer usable medium having computer readable program code and computer readable system code embodied on said medium for providing electrical waveforms associated with at least one transducer in association with a data processing system, said computer program product in operation being adapted to enable the method as claimed in any one of claims 1 to 11.

23. A method as herein disclosed.

24. An apparatus and/or device as herein disclosed.