TECHNICAL FIELD

[0001] The present invention relates generally to an ignition system, method and circuit.

[0002] Although the present invention will be described with particular reference to a system, method and circuit for igniting fuel in an internal combustion engine powering a motorcycle having a "kick start" ignition or starting procedure, it will be appreciated that it may be used for providing ignition in other types of engines and devices.

BACKGROUND ART

[0003] In a conventional inductive ignjtion system, energy is stored in a magnetic circuit of an ignition coil before being discharged in a secondary electrical circuit where it forms an electrical spark across a spark plug gap to ignite fuel in a combustion chamber of an engine. Unwanted or undesirable combustion events can however occur under certain circumstances during ignition or starting of the engine if this discharge of energy occurs when the engine is not in a suitable operating state or configuration.

[0004] For example, some types of vehicles, commonly motorcycles and scooters, require a user or rider to perform a "kick start" engine ignition or starting procedure that includes a step of performing an ignition action that comprises pushing down on or otherwise operating a ratcheting lever or kick starter of the vehicle. Similar comments also apply in respect of other manual starting arrangements that may be employed on a vehicle or other small engine application.

[0005] If the engine is not in a suitable operating state or configuration when the ignition action is performed, a "kickback" problem may occur, in which, for example, the engine may endeavour to cycle in a direction opposite to its normal or expected direction of rotation. This may result in an unexpected shock that may catch the rider unawares or injure the rider, and which in some cases may also cause damage to the engine.

[0006] Such a situation may arise in circumstances where one or more delivery events have already occurred and an ignitable mixture has been established in a combustion chamber to support starting and subsequent operation of an engine. If other factors however dictate that engine firing is not to be effected during a corresponding starting sequence, this mixture may remain in the combustion chamber unburned. Should any energy stored in the ignition means then simply be discharged by generating a spark across the spark plug gap, this mixture would be ignited resulting in an unexpected or undesirable combustion event in the engine cylinder. Depending on the angular position of the piston within a corresponding engine cylinder, this combustion event may cause the piston and hence engine to rotate in a direction opposite to its normal or expected direction of rotation leading to the unwanted problems as highlighted above.

[0007] It is against this background that the present invention has been developed. SUMMARY OF INVENTION

[0008] It is an object of the present invention to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above, or to provide the consumer with a useful or commercial choice.

[0009] Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, a preferred embodiment of the present invention is disclosed.

[0010] According to a first broad aspect of the present invention, there is provided an ignition system for an engine, the ignition system comprising: a first circuit comprising an energy storage device; a second circuit for delivering energy to an electrostatic discharger, the second circuit operably coupled to the first circuit to receive energy therefrom; and a controller operable to transition the system between a first state and a second state by switching one or more components of a third circuit out of or in to the first circuit, wherein on an ignition action when the system is in the first state, an amount of energy is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger so as to produce an electrostatic discharge therefrom sufficient to ignite a combustible mixture in a corresponding combustion chamber, and on an ignition action when the system is in the second state, energy of the first circuit is decreased so that no energy is transferred from the first circuit to the second circuit or any energy that is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger is such that any electrostatic discharge produced therefrom is insufficient to ignite the combustible mixture in the combustion chamber.

[0011] In a preferred embodiment of the invention, on an ignition action when the system is in the second state, the energy decrease occurs via dissipation of energy from the first circuit.

[0012] Energy is preferably dissipated from the first circuit and the one or more components of the third circuit, the first circuit dissipating a majority of the energy and the one or more components of the third circuit dissipating a minority of the energy.

[0013] In embodiments of the invention, a single component of the first circuit dissipates the majority of the energy.

[0014] Preferably, no electrostatic discharge occurs from the electrostatic discharger.

[0015] According to a second broad aspect of the present invention, there is provided an ignition system for an engine, the ignition system comprising: a first circuit comprising an energy storage device; a second circuit for delivering energy to an electrostatic discharger, the second circuit operably coupled to the first circuit to receive energy therefrom; and a controller operable to control operation of the system in a first state and a second state, wherein on an ignition action when the system is in the first state, an amount of energy is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger so as to produce an electrostatic discharge therefrom sufficient to ignite a combustible mixture in a corresponding combustion chamber, and on an ignition action when the system is in the second state, an amount of energy is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger that is insufficient to produce an electrostatic discharge therefrom. [0016] In a preferred embodiment of the invention, to facilitate the amount of energy being transferred from the first circuit to the second circuit and delivered to the electrostatic discharger being insufficient to produce an electrostatic discharge on an ignition action when the system is in the second state, an amount of energy is dissipated from the first circuit so that no electrostatic discharge occurs from the electrostatic discharger.

[0017] Preferably, the combustion chamber is provided in a spark ignition internal combustion engine. In such a case, the electrostatic discharge from the electrostatic discharger comprises an electric spark and, preferably, the electrostatic discharger comprises a spark plug.

[0018] Preferably, the controller is operable to transition the system between the first state and the second state by switching one or more components out of or in to the first circuit. More preferably, the one or more components comprise a feedback circuit or path in the first circuit.

[0019] Preferably, the first circuit comprises at least one semiconductor device, such as a power transistor. The at least one semiconductor device may comprise an insulated gate bipolar transistor (IGBT) comprising three terminals, being a Collector terminal, a Gate terminal and an Emitter terminal. In such an embodiment, the feedback path may be provided between the Gate and Collector terminals of the IGBT. To transition to and put the system in the first state, the controller is operable to disable or disconnect the feedback circuit from the first circuit. To transition to and put the system in the second state, the controller is operable to enable or connect the feedback circuit into the first circuit.

[0020] Preferably, the first circuit and the second circuit are operably coupled via an ignition coil, induction coil or transformer.

[0021] Preferably, the ignition system comprises one or more sensors operable to sense data relating to or associated with the ignition system and/or the engine and to communicate the sensed data to the controller.

[0022] Preferably, the data relates to or is associated with a present or current operating state of the system and/or a present or current operating condition of the engine. [0023] The operating condition may comprise whether a state of the engine corresponds to an optimum or desired ignition or starting state, in which case the controller is operable to transition the system into the first state.

[0024] The operating condition may comprise whether a state of the engine corresponds to a state in which the engine should not be started or the combustible mixture ignited. This may be because, for example, doing so would result in an unexpected or undesirable event, or circumstances are such that an ignition should be aborted. In such a case, the controller is operable to transition the system into the second state.

[0025] Preferably, the controller comprises a computer operably coupled to control operation of the ignition system.

[0026] Preferably, the computer is operable to process sensed data received from the one or more sensors and to control operation of the ignition system on the basts of the processing.

[0027] The ignition action may be any action performed or undertaken with the intention of igniting a combustible mixture in a combustion chamber of, or otherwise starting, the engine and may vary according to the type of engine and its application. In the case of an engine having a manual or kick start starting procedure, the ignition action may comprise manually actuating, pushing down on or otherwise operating a kick starter. In the case of an engine having a recoil starting procedure, the ignition action may comprise pulling or otherwise operating a starter cord or rope.

[0028] According to a third broad aspect of the present invention, there is provided an ignition system for an engine, the ignition system comprising: a first circuit comprising an energy storage device; a second circuit for delivering energy to an electrostatic discharger, the second circuit operably coupled to the first circuit to receive energy therefrom; and a controller operable to control operation of the system in a first state and a second state, wherein on an ignition action when the system is in the first state, an amount of energy is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger so as to produce an electrostatic discharge therefrom sufficient to ignite a combustible mixture in a corresponding combustion chamber, and on an ignition action when the system is in the second state, an amount of energy is dissipated from the first circuit so that no electrostatic discharge occurs from the electrostatic discharger.

[0029] According to a fourth broad aspect of the present invention, there is provided a method for igniting a combustible mixture in a combustion chamber of an engine, the method comprising: in a first stage, transferring an amount of energy from a first circuit to a second circuit and delivery to an electrostatic discharger of a sufficient amount of energy to produce an electrostatic discharge therefrom to ignite the combustible mixture, and in a second stage, decreasing energy of the first circuit so that no energy is transferred from the first circuit to the second circuit or any energy that is transferred from the first circuit to the second circuit and delivered to the electrostatic discharger is such that any electrostatic discharge produced therefrom is insufficient to ignite the combustible mixture.

[0030] In preferred embodiments of the invention, in the second stage, decreasing the energy comprises dissipating energy from the first circuit.

[0031] Preferably, energy is dissipated from the first circuit and one or more components of a third circuit, the first circuit dissipating a majority of the energy and the one or more components of the third circuit dissipating a minority of the energy.

[0032] It is further preferred that a single component of the first circuit dissipates the majority of the energy.

[0033] In embodiments of the invention, no electrostatic discharge occurs from the electrostatic discharger.

[0034] According to a fifth broad aspect of the present invention, there is provided a method for igniting a combustible mixture in a combustion chamber of an engine, the method comprising: in a first stage, transferring an amount of energy from a first circuit to a second circuit and delivery to an electrostatic discharger of a sufficient amount of energy to produce an electrostatic discharge therefrom to ignite the combustible mixture, and in a second stage, transferring an amount of energy from the first circuit to the second circuit and delivery to the electrostatic discharger of an amount of energy that is insufficient to produce an electrostatic discharge therefrom.

[0035] According to a sixth broad aspect of the present invention, there is provided a method for igniting a combustible mixture in a combustion chamber of an engine, the method comprising: in a first stage, transferring an amount of energy from a first circuit to a second circuit and delivery to an electrostatic discharger of a sufficient amount of energy to produce an electrostatic discharge therefrom to ignite the combustible mixture, and in a second stage, dissipating an amount of energy from the first circuit so that no electrostatic discharge occurs from the electrostatic discharger.

[0036] According to a seventh broad aspect of the present invention, there is provided first and/or second circuits for use in a system according to the first, second, or third broad aspects of the present invention as hereinbefore described, or a method according to the fourth, fifth or sixth broad aspects of the present invention as hereinbefore described.

[0037] According to an eighth broad aspect of the present invention, there is provided a computer-readable storage medium on which is stored instructions that, when executed by a computing means, causes the computing means to perform the method according to the fourth, fifth or sixth broad aspects of the present invention as hereinbefore described.

[0038] According to a ninth broad aspect of the present invention, there is provided a computing means programmed to carry out the method according to the fourth, fifth or sixth broad aspects of the present invention as hereinbefore described. [0039] According to a tenth broad aspect of the present invention, there is provided a data signal including at least one instruction being capable of being received and interpreted by a computing system, wherein the instruction implements the method according to the fourth, fifth or sixth broad aspects of the present invention as hereinbefore described.

[0040] According to an eleventh broad aspect of the present invention, there is provided an ignition circuit for an engine, the ignition circuit comprising: an energy storage device; and switching means operable to switch the circuit between a first state and a second state, wherein on an ignition action when the circuit is in the first state, an amount of energy is transferred from the energy storage device and delivered to an electrostatic discharger that is sufficient to produce an electrostatic discharge therefrom to ignite a combustible mixture in a combustion chamber of the engine, and on an ignition action when the circuit is in the second state, energy of the first circuit is decreased so that no energy is transferred from the energy storage device to the electrostatic discharger or any energy that is transferred from the energy storage device and delivered to the electrostatic discharger is insufficient to ignite the combustible mixture.

[0041] In a preferred embodiment of the invention, on an ignition action when the circuit is in the second state, the energy decrease occurs via dissipation of energy from the circuit.

[0042] According to a twelfth broad aspect of the present invention, there is provided an ignition circuit for an engine, the ignition circuit comprising: an energy storage device; and switching means operable to switch the circuit between a first state and a second state, wherein on an ignition action when the circuit is in the first state, an amount of energy is transferred from the energy storage device and delivered to an electrostatic discharger that is sufficient to produce an electrostatic discharge therefrom to ignite a combustible mixture in a combustion chamber of the engine, and on an ignition action when the circuit is in the second state, an amount of energy is transferred from the energy storage device and delivered to the electrostatic discharger that is insufficient to produce an electrostatic discharge therefrom.

[0043] According to a thirteenth broad aspect of the present invention, there is provided an ignition circuit for an engine, the ignition circuit comprising: an energy storage device; and switching means operable to switch the circuit between a first state and a second state, wherein on an ignition action when the circuit is in the first state, an amount of energy is transferred from the energy storage device and delivered to an electrostatic discharger that is sufficient to produce an electrostatic discharge therefrom to ignite a combustible mixture in a combustion chamber of the engine, and on an ignition action when the circuit is in the second state, an amount of energy is dissipated from the circuit so that no electrostatic discharge occurs from the electrostatic discharger.

[0044] In can be appreciated that embodiments of the invention address the specific problem discussed in the Background Art, to at least some extent. In circumstances where a schedule of events have happened resulting in a combustible mixture being established or present in a combustion chamber of an engine, embodiments of the invention seek to ensure that this combustible mixture is not ignited when doing so would result in an unexpected or undesirable event. Embodiments of the invention achieve this by operating in the second state and seeing that the amount of energy transferred from the first circuit to the second circuit and delivered to the electrostatic discharger is insufficient to produce an electrostatic discharge therefrom. In particularly preferred embodiments, an amount of energy is dissipated or discharged from the circuit by operating in the second state so that no electrostatic discharge occurs from the electrostatic discharger.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order that the invention may be more fully understood and put into practice, preferred embodiments thereof will now be described with reference to the accompanying drawings, in which:

Figure 1 depicts a circuit diagram of an embodiment of an ignition system for an engine in accordance with an aspect of the present invention;

Figure 2 depicts a simplified circuit diagram of a first circuit of the system of Figure 1 when in a first state or Ignition Enable mode of operation of the system;

Figure 3 depicts a simplified circuit diagram of a first circuit of the system of Figure 1 when in a second state or Soft Kill Enable mode of operation of the system;

Figure 4 depicts a first graph of Dwell Signal, Drain Current, and Drain Voltage parameters over time in the circuit when an ignition action is performed during the Ignition Enable mode of operation;

Figure 5 depicts a second graph of Dwell Signal, Drain Current, and Drain Voltage parameters over time in the circuit when an ignition action is performed during the Ignition Enable mode of operation;

Figure 6 depicts a first graph of Dwell Signal, Drain Current, and Drain Voltage parameters over time in the circuit when an ignition action is performed during the Soft Kill Enable mode of operation;

Figure 7 depicts a second graph of Dwell Signal, Drain Current, and Drain Voltage parameters over time in the circuit when an ignition action is performed during the Soft Kill Enable mode of operation;

Figure 8 depicts a first graph comparing Drain Current, Drain Voltage and Spark Threshold parameters over time in the circuit when the system is operating in the Ignition Enable and Soft Kill Enable modes of operation;

Figure 9 depicts a second graph comparing Drain Current, Drain Voltage and Spark Threshold parameters over time in the circuit when the system is operating in the Ignition Enable and Soft Kill Enable modes of operation; and

Figure 10 depicts timing of signals in the circuit when the system is operating in the Ignition Enable and Soft Kill Enable modes of operation. DESCRIPTION OF EMBODIMENTS

[0046] In the drawings, like features have been referenced with like reference numbers.

[0047] In Figure 1 , there is depicted a circuit diagram of an embodiment of an ignition system 10 in accordance with an aspect of the present invention.

[0048] In the embodiment described, the system 10 is for use with an internal combustion engine of a motorcycle (not shown) and is operable to ignite fuel in the engine. The motorcycle is of the type having a "kick start" starting procedure that includes a step of the user or rider performing an ignition action that comprises pushing down on or otherwise operating a ratcheting lever or kick starter of the motorcycle.

[0049] In alternative embodiments of the invention, the system 10 may be used with other types of engines, powering the same or other types of vehicles or devices, and is not limited in this regard. For example, the system 10 can be used with engines powering other vehicles such as mopeds, scooters, jet skis, snow mobiles, ultra-light aircraft, and all-terrain vehicles (ATVs), and devices, including chainsaws, lawnmowers, generators, and outboard motors.

[0050] The ignition action may be any action performed or undertaken with the intention of igniting fuel in a combustion chamber of, or otherwise starting, the engine and may vary according to the type of engine and its application. In the case of an engine powering a chainsaw or lawnmower having a recoil start, for example, the ignition action may comprise the user or operator pulling or otherwise operating a starter cord or rope.

[0051] The system 10 comprises a first, or primary, circuit 12. A second, or secondary, circuit 14 is operably coupled to the first circuit 12 to receive energy therefrom and to deliver energy to an electrostatic discharger 16.

[0052] Circuits of the system 10, such as the first circuit 12 and the second circuit 14, may be constructed using any known techniques appropriate for the application of the invention, including discrete components connected by individual pieces of wire, printed circuit board (PCB) and integrated circuit techniques or a combination thereof. The circuits may be analogue circuits, digital circuits, or a combination thereof, and may comprise any combination and type of components required to enable the described operations to be performed. [0053] In the embodiment described the engine is a spark ignition engine and the electrostatic discharger 16 comprises a spark plug operable to provide an electrostatic discharge in the form of an electric spark.

[0054] The first circuit 12 is coupled to the second circuit 14 via an inductive ignition coil 18, which may also be referred to as an induction coil or transformer.

[0055] As will be described in further detail below, the first circuit 12 functions as an ignition driver circuit, or ignitor, for the ignition coil 18. Unlike conventional ignitors, this circuit in the embodiment described is operable to perform soft discharging of the inductive ignition coil 18. When soft discharge is engaged, energy stored in a magnetic circuit of the ignition coil 18 is discharged or dissipated without an electric spark being generated across a spark plug gap of the spark plug. In this regard, it should be appreciated that it is not essential that no electric spark is generated across a spark plug gap of the spark plug. It is enough that any electrostatic discharge that may occur is insufficient to to ignite the fuel in the combustion chamber.

[0056] The ignition coil 18 has a first, or primary, winding 20 electrically connected so as to form part of the first circuit 12. Particularly, a first terminal 22 of the first winding 20 is electrically connected to an energy storage device 24 of the first circuit 12, and a second terminal 26 of the first winding 20 is electrically connected to other components of the first circuit 12, described in further detail below. In the embodiment described, the energy storage device 24 comprises a battery.

[0057] Additionally, the ignition coil 18 has a second, or secondary, winding 28 electrically connected to the second circuit 14 to deliver energy to the electrostatic discharger 16.

[0058] The system 10 also comprises a controller 30 operable to control operation of the system 10 in a first state or mode of operation, which may be referred to as an Ignition Enable or standard mode, and in a second state or mode of operation, which may be referred to as a Soft Kill Enable mode.

[0059] On performance of an ignition action by a user when the system 10 is in the first state, an amount of energy is transferred from the first circuit 12 to the second circuit 14 and delivered to the electrostatic discharger 16 so as to produce an electrostatic discharge therefrom sufficient to ignite fuel (i.e. the combustible mixture) in the combustion chamber of the engine. [0060] On performance of an ignition action by a user when the system 10 is in the second state, energy of the first circuit 12 is decreased so that no energy is transferred from the first circuit 12 to the second circuit 14 or any energy that is transferred from the first circuit 12 to the second circuit 14 and delivered to the electrostatic discharger 16 is such that any electrostatic discharge produced therefrom is insufficient to ignite the combustible mixture in the combustion chamber.

[0061] In preferred embodiments of the invention, on performance of an ignition action by a user when the system 10 is in the second state, an amount of energy is dissipated or discharged from the first circuit 12 so that no electrostatic discharge occurs from the electrostatic discharger 16 (i.e. no spark results at the spark plug gap).

[0062] The objective of this operation is primarily to make sure that the amount of energy that is/may be discharged in the second circuit is insufficient to ignite any fuel/air mixture which may be present within the combustion chamber. As will be described in further detail, to function effectively, the embodiment of the invention just needs to dissipate the bulk of the energy in the first circuit 12 (when in the "second mode of operation") so that little or no energy goes towards generating a spark.

[0063] In the embodiment described, the controller 30 has the form of a computer. In combination with other components, the controller 30 functions as a switching means or switch to change between the first and second operating states,

[0064] Software is stored and run on the computer. The software, or any set of instructions or programs for the computer, can be written in any suitable language, as are well known to persons skilled in the art. Furthermore, the software may comprise a set of software code and can be provided as stand-alone application(s) or via a network, depending on the system requirements.

[0065] In alternative embodiments of the invention, the software may comprise one or more modules, and may be implemented in hardware. In such a case, for example, the modules may be implemented with any one or a combination of the following technologies, which are each well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA) and the like. [0066] The software comprises logic such that the computer is operable, under control of the software, to perform actions as herein described.

[0067] The computer can be of any suitable type, including: a programmable logic controller (PLC); digital signal processor (DSP); microcontroller; personal, notebook or tablet computer, or a dedicated server or networked servers.

[0068] In embodiments of the invention, the computer may include display means in the form of a monitor or visual display, a container such as a box for housing various, operably. connected components of the computer such as a motherboard, processing means, disk drives and power supply of the computer, and control means such as a keyboard, keypad or touchscreen and other suitable peripheral devices such as a mouse (not depicted). Together, the display, keyboard and other peripheral devices provide a user interface or Human or Man Machine Interface (HMI) to enable a human user or operator to interact with the software via a Graphical User Interface (GUI).

[0069] Processing means of the computer includes a central processor. The computer also includes a storage means, device or medium such as a memory device for the storage and running of software, including the abovementioned software. The processor is operable to perform .actions under control of the software, as will be described in further detail below, including processing/executing instructions and managing the flow of data and information through the computer. For example, the processor can be any custom made or commercially available processor, a central processing unit (CPU), a data signal processor (DSP) or an auxiliary processor among several processors associated with the computer. In embodiments of the invention, the processing means may be a semiconductor based microprocessor (in the form of a microchip) or a macroprocessor, for example.

[0070] In embodiments of the invention, the storage means, device or medium can include any one or combination of volatile memory elements (e.g., random access memory (RAM) such as dynamic random access memory (DRAM), static random access memory (SRAM)) and non-volatile memory elements (e.g., read only memory (ROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), programmable read only memory (PROM), tape, compact disc read only memory (CD-ROM), etc.). The storage medium may incorporate electronic, magnetic, optical and/or other types of storage media. Furthermore, the storage medium can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processing means. For example, the ROM may store various instructions, programs, software, or applications to be executed by the processing means to control the operation of the reader and the RAM may temporarily store variables or results of the operations.

[0071] The use and operation of electronic and electrical circuits, computers using software, HMIs and GUIs, is well-known to persons skilled in the art and need not be described in any further detail herein except as is relevant to the present invention.

[0072] Furthermore, any suitable communication protocol can be used to facilitate communication between any subsystems or components of the system 10, and the system 10 and other devices, including wired and wireless, as are well known to persons skilled in the art and need not be described in any further detail herein except as is relevant to the present invention.

[0073] Where the word "store" is used in the context of the present invention, it is to be understood as including reference to the retaining or holding of data or information both permanently and/or temporarily in the storage means, device or medium for later retrieval, and momentarily or instantaneously, for example as part of a processing operation being performed.

[0074] Additionally, where the terms "system" and "device" are used in the context of the present invention, they are to be understood as including reference to any group of functionally related or interacting, interrelated, interdependent or associated components or elements that may be located in proximity to, separate from, integrated with, or discrete from each other.

[0075] Furthermore, in embodiments of the invention, the word "determining" is understood to include receiving or accessing the relevant data or information.

[0076] It should also be noted that where the word "fuel" is used in the context of the present invention, it is to be understood as referring to any material, substance, mixture, or combination that stores energy that can later be extracted to perform mechanical work in a controlled manner.

[0077] The controller 30 is operably coupled to at least one sensor or detector 32, and/or a timer. In embodiments of the invention, the system 10 may comprise a set of one or more sensors or detectors and/or timers. The at ieast one sensor 32 (or individual sensors within the set of sensors, where provided) is operable to sense and gather sensor data or information relating to or associated with properties and/or parameters of the system 10, components or subsystems of the system 10, and/or elements or devices coupled thereto, such as the engine, and to input or otherwise communicate the sensed or detected data or information to the controller 30 for processing.

[0078] One application of the system 10 according to an embodiment of the invention is to effect a time-out if a dwell signal is held on for a period of time, which may be a prescribed period of time determined to be excessive and likely to result in over-dwelling of the coil 18. In such an embodiment, the system 10 is operable to switch to the second state or mode of operation when it is determined that the dwell signal has been held on for the period of time (via input from a timer). In this manner, the system 10 is operable to prevent over-dwelling of the coil 18 by discharging or dissipating the ignition energy safely.

[0079] In the embodiment described, the sensed data or information relates to:

• a present or current operating state of the system 0 (i.e. whether it is in the first state (Ignition Enable mode) or the second state (Soft Kill Enable mode)); and

• an operating condition of the engine. Particularly, an operating condition comprising whether a present or current state of the engine corresponds to an optimum or desired ignition or starting state, or a state in which the engine should not be started or the fuel ignited.

[0080] In embodiments of the invention, individual sensors in the set of sensors, and the properties and parameters sensed, include: crank and/or cam position sensors, which may be of variable reluctance, hall-effect, or optical type, for example; a temperature sensor; and a timer.

[0081] The computer is operably coupled to the sensor(s) 32 to receive the sensor data and to control individual sensors and their operation.

[0082] The computer is also operably connected to control the operation of the system 10 in response to processing or analysis of received sensor data and information. [0083] Particularly, on the basis of the processing and analysis, the computer is operable to determine whether a present or current state of the engine corresponds to an optimum or desired ignition or starting state, or to a state in which ignition would result in an unexpected or undesirable combustion event and should not occur, and to transition the system 10 between the first state and the second state, as appropriate, by switching one or more components forming a third circuit in the form of a feedback circuit or path 34, which may also be referred to as a soft-kill circuit, into or out of the first circuit 12.

[0084] The first circuit 12 generally comprises a first semiconductor device in the form of an insulated gate bipolar transistor (IGBT) 36. The IGBT 36 comprises three terminals, being a Collector terminal 36A, a Gate terminal 36B, and an Emitter terminal 36C.

[0085] The Collector terminal 36A of the IGBT 36 is electrically connected to the second terminal 26 of the first winding 20 of the ignition coil 18. The Gate terminal 36B of the IGBT 36 is electrically connected to an Ignition Enable terminal 30A of the controller 30, via appropriate resistive elements or resistors 38, and a transistor 40 (connected at its Collector terminal 40A via a pull-up resistor 41 to a further energy storage device 43 comprising a battery, to facilitate turning on of the driver), to receive an Ignition Enable signal therefrom.

[0086] The feedback circuit 34 is provided between the Gate terminal 36B and the Collector terminal 36A of the IGBT 36.

[0087] To transition to and put the system 10 in the first state, the controller 30 is operable to disable or disconnect the feedback circuit 34. To transition to and put the system 10 in the second state, the controller 30 is operable to enable or connect the feedback circuit 34.

[0088] The feedback circuit 34 comprises a zener diode 42, electrically connected to the second terminal 26 of the first winding 20 of the ignition coil 18 (and hence the Collector terminal 36A of the IGBT 36) and a Collector terminal 44A of a first feedback transistor 44, which may also be referred to as a zener-switching transistor. An Emitter terminal 44B of the first feedback transistor 44 is electrically connected to the Gate terminal 36B of the IGBT 36. A Base terminal 44C of the first feedback transistor 44 is electrically connected to a Soft Kill Enable terminal 30B of the controller 30 to receive a Soft Kill Enable signal therefrom, via a second feedback transistor 46 and appropriate feedback resistive elements or resistors 48 and a further energy storage device 50 comprising a battery.

[0089] In embodiments of the invention, the arrangement of peripheral components in the circuitry, including small signal transistors such as the second feedback transistor 46, is somewhat arbitrary in that they are used to set up the conditions for the zener switching or first feedback transistor 44 to switch on and off when desired or required to enable the system 10 to operate as herein described. Accordingly, in other embodiments of the invention, alternative arrangements of the same, additional, or alternative components may be used.

[0090] In the embodiment, the IGBT 36 is a high power device. The IGBT 36 acts as the primary switching device when it turns fully on (from a dwell signal), and is the component that dissipates energy in the circuit comprising zener diode 42, the first feedback transistor 44 and it (i.e. the IGBT 36) when a soft discharge is activated.

[0091] The zener diode 42 sets the voltage that the flyback spike is clipped at, but the energy is dissipated in the IGBT 36. There is no single voltage limiting component, it is a circuit of the zener diode 42, the first feedback" transistor 44 and the IGBT 36, but the energy is only dissipated in the IGBT 36, which is already a high-power component.

[0092] Advantageously, the embodiment of the invention does not require that the zener diode 42, or equivalent component(s) in alternative embodiments, be a high power device, as it is only used in the feedback circuit 34 to affect the required voltage limit.

[0093] This highlights a further advantage of the embodiment in that the primary switching device and voltage limiting components are provided in the same single component, the IGBT 36, in the ignition circuit, allowing for both associated printed circuit board (PCB) size and valuable cost reductions to be realised.

[0094] Figure 2 depicts a simplified circuit diagram of the first circuit 12 when the system 10 is in the first state or Ignition Enable mode of operation.

[0095] Figure 3 depicts a simplified circuit diagram of the first circuit 12 when the system 10 is in the second state or Soft Kill Enable mode of operation.

[0096] The above and other features and advantages of the embodiment _ of the invention will now be further described with reference to the system 10 in use. [0097] The operating condition of the engine, and/or controller 30 in embodiments where the system 10 is used to affect a time-out as described above or to prevent an over-temperature condition, is continuously monitored and determined by the system 10 via the sensor(s) 32.

[0098] In the embodiment described, the system 10 is usually or by default in the first (Ignition Enable mode) state of operation. In this state the controller 30 generates and provides an Ignition Enable signal to the first circuit 12 via the Ignition Enable terminal 30A.

[0099] When the rider pushes down on the kick starter of the motorcycle to perform the igniting action, the dwell (gate drive) is started or enabled (only after the beginning of the kick-start action). Energy is transferred to the ignition coil 18.

[00100] When it is determined that the present or current state of the engine does not correspond to a state in which it should not be started, the ignition proceeds. The IGBT 36 turns off immediately when the gate drive is disabled, resulting in a high first or primary voltage across the first winding 20 of the ignition coil 18. As a consequence of a transformer winding ratio of the ignition coil 18, the high primary voltage across the first winding 20 results in an even higher second, or secondary, voltage across the second winding 28 of the ignition coil 18, which results in sufficient energy being delivered to the spark plug to produce an electrical spark, igniting the combustible mixture of the fuel and starting the motorcycle.

[00101] Figures 4 and 5 of the drawings depict graphs showing example values for Dwell Signal (V), Drain Current (A), and Drain Voltage (Vright) parameters over time in the first circuit 12 when an ignition action is performed during the Ignition Enable mode of operation.

[00102] When it is determined that the present or current state of the engine does not correspond to an optimum or desired ignition or starting state, that is, it corresponds to a state in which it should not be started because, for example, doing so would result in an unexpected or undesirable event, the controller 30 (under control of the software) operates to connect or engage the feedback circuit 34 with the first circuit 12 to place the system 10 in the second (Soft Kill Enable mode) state of operation. In the embodiment described, the feedback circuit 34 is only connected or engaged when the ignition has already been dwelled, but no ignition is desired. That is, the feedback circuit 34 is only required after some energy has already been transferred to the ignition coil 18. This is initiated by the controller 30 generating and providing a Soft Kill Enable signal to the first circuit 12 via the Soft Kill Enable terminal 30B.

[00103] In this mode, when the rider pushes down on the kick starter of the motorcycle to perform the igniting action, the IGBT 36 will not switch off completely when the gate drive is disabled. Instead, the IGBT 36 will continue to operate in a saturation region of operation. Energy stored in the first winding 20 of the ignition coil 18 is discharged or dissipated in the first circuit 12. The driver IGBT 36 in the first circuit 12 absorbs the stored energy, which is then dissipated as heat. Primary current in the first circuit 12, and the first winding 20 of the ignition coil 18 will decay over time, and the first or primary voltage across the first winding 20 will remain relatively low. By keeping the primary voltage low, the second or secondary voltage across the second winding 28 of the ignition coil 18 also stays low, and does not exceed the threshold required for an electrical spark to form across the spark plug gap.

[00104] In embodiments of the invention, the system 10 is operable to engage the feedback circuit 34 and enter the second state or mode of operation additionally or alternatively at any other time that an ignition is desired to be aborted. For example, if this is used when a kill switch is engaged, one less ignition event may occur, resulting in faster power-down.

[00105] Advantageously, a part or component that already exists in the first circuit 12 - the ignitor IGBT 36 - is used to dissipate a majority of the energy stored in the inductor (ignition coil 18) when soft kill is engaged with one or more components of the third (i.e. feedback) circuit 34 dissipating a minority of the energy. No extra power components have been added to the first circuit 12 to implement the soft-kill functionality. This provides benefits as it is desirable to keep the number of power components to a minimum because they tend to be expensive and consume considerable space.

[00106] Figures 6 and 7 of the drawings depict graphs showing example values for Dwell Signal (V), Drain Current (A), and Drain Voltage (Vright) parameters over time in the first circuit 12 when an ignition action is performed during the Ignition Enable mode of operation. [00107] Figures 8 and 9 of the drawings depict graphs comparing example values for Drain Current (V), Drain Voltage (V) and Spark Threshold (Vright) parameters over time in the first circuit 12 when the system 10 is operating in the Ignition Enable and Soft Kill Enable modes of operation.

[00108] Figure 10 depicts example values of timing of the Ignition Enable and Soft Kill Enable signals relative to a synchronization signal and current in the ignition coil 18 in the system 10.

[00109] In this way, the engine will not start when it is in an undesirable ignition or starting state, avoiding unwanted or undesirable ignition events or problems that may occur if it was to be started is such a state, such as a kickback situation resulting in mechanical or other shock and potentially damaging the engine and injuring the rider.

[00110] The embodiment of the invention has the ability to provide selective abortion of already dwelled ignition events, particularly in respect of manual start engines for lower cost vehicles such as motorcycles or scooters where it is wanted to ensure that a combustion event does not occur when it may cause harm to the rider or engine.

[00111] It will be appreciated that the invention is not limited to applications involving inductive discharge systems, and in alternative embodiments can modified as may be required to be implemented in capacitive discharge systems, for example. In the embodiment described, the soft kill circuit for the inductive discharge system (which accumulates energy in an inductor in the form of a magnetic field) operates by discharging the energy stored in the inductor. In an alternative embodiment, using appropriate alternative circuitry and components, a soft-kill circuit for a capacitive discharge system (which accumulates energy in a capacitor in the form of an electric field) operates by discharging the energy stored in the capacitor.

[00112] It will be appreciated by those skilled in the art that variations and modifications to the invention described herein will be apparent without departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall Within the broad scope and ambit of the invention as herein set forth.

[00113] Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00114] Throughout the specification and claims, unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

[00115] It will be clearly understood that, if a prior art publication is referred to herein, that reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.