Detection circuit and spark plug

Abstract

The application relates to a detection circuit and a spark plug. The detection circuit comprises a driving module connected with an ignition coil to drive the spark plug to ignite according to a driving enable signal; an ignition energy storage module connected with the ignition coil and an ignition electrode respectively to store ignition energy of the ignition coil; a spark current detection module connected with the ignition energy storage module to detect a spark current during ignition and output a spark current end identification signal according to the detected spark current; an ion current detection module connected with the ignition energy storage module and the spark current detection module respectively to detect an ion current during ignition according to the spark current end identification signal; and a control module connected with the driving module and the ion current detection module respectively to provide the driving enable signal, receive an ion current signal output by the ion current detection module, and determine a state of the ignition electrode according to the ion current signal. The state of the ignition electrode is accurately determined.

Description

Technical Field

[0001] This application relates to the field of spark plug technology, and in particular to a detection circuit and a spark plug. Background Technology

[0002] Spark plugs are typically used to ignite combustion in internal combustion engines, and their performance largely determines the engine's overall performance. If the spark plug electrodes deteriorate during use, it will severely impact the engine's combustion performance. Therefore, accurately detecting the condition of the spark plug electrodes is a pressing problem that needs to be solved. Summary of the Invention

[0003] Therefore, it is necessary to provide a detection circuit and spark plug that can accurately detect the state of spark plug electrodes to address the above-mentioned technical problems.

[0004] Firstly, this application provides a detection circuit. The detection circuit is used to detect the state of a spark plug, wherein the spark plug includes an ignition coil and an ignition electrode, the ignition coil being connected to the ignition electrode, and the detection circuit includes:

[0005] The drive module is connected to the ignition coil and is used to drive the spark plug to ignite according to the drive enable signal;

[0006] An ignition energy storage module is connected to the ignition coil and the ignition electrode respectively, and is used to store the ignition energy of the ignition coil.

[0007] A spark current detection module is connected to the ignition energy storage module and is used to detect the spark current during ignition and output a spark current end indicator signal based on the detected spark current.

[0008] An ion current detection module is connected to both the ignition energy storage module and the spark current detection module, and is used to detect the ion current during ignition based on the spark current end indicator signal.

[0009] The control module is connected to the drive module and the ion current detection module respectively, and is used to provide the drive enable signal, receive the ion current signal output by the ion current detection module, and determine the state of the ignition electrode based on the ion current signal.

[0010] In one embodiment, the ignition energy storage module includes:

[0011] An energy storage unit is provided, wherein the input terminal of the energy storage unit is connected to the ignition coil, and the second output terminal of the energy storage unit is connected to the second input terminal of the spark current detection module. The energy storage unit is used to store the ignition energy of the ignition coil.

[0012] A spark current unit, wherein the input terminal of the spark current unit is connected to the first output terminal of the energy storage unit, the first output terminal of the spark current unit is connected to the first input terminal of the spark current detection module, and the second output terminal of the spark current unit is connected to a first reference signal. The spark current unit is used to form a spark current loop with the ignition electrode and the ignition coil based on the ignition energy stored in the energy storage unit.

[0013] An ion current unit is provided, wherein its first input terminal is connected to the ignition electrode, its second input terminal is connected to a first reference signal, its first output terminal is connected to the first input terminal of the ion current detection module, its second output terminal is connected to the second input terminal of the ion current detection module, and its third output terminal is connected to the first output terminal of the energy storage unit. The ion current unit is used to form an ion current loop with the ignition electrode and the ignition coil based on the ignition energy stored in the energy storage unit; wherein the current flow direction of the spark current loop is opposite to that of the ion current loop.

[0014] In one embodiment, the energy storage unit includes a capacitor assembly and a first diode; wherein the input terminal of the capacitor assembly is connected to the ignition coil, the cathode of the first diode is connected to the input terminal of the capacitor assembly, the anode of the first diode is connected to the output terminal of the capacitor assembly, and the anode of the first diode is connected to the second input terminal of the spark current detection module.

[0015] The spark current unit includes: a first resistor and a second diode; wherein, the first end of the first resistor is connected to the output end of the capacitor assembly, the anode of the second diode is connected to the second end of the first resistor, the anode of the second diode is connected to the first input end of the spark current detection module, and the cathode of the second diode is connected to a first reference signal.

[0016] The ion current unit includes a second resistor and a third diode; wherein, the first end of the second resistor is connected to the output end of the capacitor assembly, the first end of the second resistor is connected to the first input end of the ion current detection module, the cathode of the third diode is connected to the second end of the second resistor, the cathode of the third diode is connected to the second input end of the ion current detection module, the anode of the third diode is connected to the ignition electrode, and the anode of the third diode is connected to a first reference signal.

[0017] In one embodiment, the spark current detection module includes:

[0018] An amplification unit is provided, wherein a first input terminal of the amplification unit is connected to a first output terminal of the ignition energy storage module, and a second input terminal of the amplification unit is connected to a second output terminal of the ignition energy storage module. The amplification unit is used to detect the spark current during ignition.

[0019] The comparison unit has its input terminal connected to the output terminal of the amplification unit, and its output terminal connected to the third input terminal of the ion current detection module. The comparison unit is used to output a spark current end indicator signal based on the spark current detected by the amplification unit.

[0020] In one embodiment, the amplification unit includes: a first amplifier and a third resistor;

[0021] The negative input terminal of the first amplifier is connected to the first output terminal of the ignition energy storage module, the positive input terminal of the first amplifier is connected to the second output terminal of the ignition energy storage module, the first terminal of the third resistor is connected to the negative input terminal of the first amplifier, and the second terminal of the third resistor is connected to the output terminal of the first amplifier.

[0022] In one embodiment, the comparison unit includes: a first comparator, a second comparator, a fourth resistor, and a fifth resistor;

[0023] The negative input terminal of the first comparator is connected to the output terminal of the first amplifier, the positive input terminal of the first comparator is connected to the second reference signal, the first terminal of the fourth resistor is connected to the negative input terminal of the first comparator, the second terminal of the fourth resistor is connected to the second reference signal, the first terminal of the fifth resistor is connected to the negative input terminal of the first comparator, and the second terminal of the fifth resistor is connected to the third reference signal.

[0024] The negative input terminal of the second comparator is connected to the negative input terminal of the first comparator, the positive input terminal of the second comparator is connected to the second reference signal, and the output terminal of the second comparator is connected to the output terminal of the first comparator.

[0025] In one embodiment, the ion current detection module includes:

[0026] An inverting isolation unit is provided, wherein the first input terminal of the inverting isolation unit is connected to the output terminal of the spark current detection module, and the second input terminal of the inverting isolation unit is connected to the third output terminal of the ignition energy storage module. The inverting isolation unit is used to release the ignition energy corresponding to the spark current according to the spark current end indicator signal.

[0027] The operational amplifier feedback unit has its first input terminal connected to the output terminal of the inverting isolation unit, its second input terminal connected to the fourth output terminal of the ignition energy storage module, and its output terminal connected to the control module. The operational amplifier feedback unit is used to detect the ion current during ignition.

[0028] In one embodiment, the phase-inverting isolation unit includes: an inverter, a first optocoupler isolation component, and a second optocoupler isolation component; wherein, the input terminal of the inverter is connected to the output terminal of the spark current detection module, the first input terminal of the first optocoupler isolation component is connected to the output terminal of the inverter, the first output terminal of the first optocoupler isolation component is connected to a third reference signal, the second input terminal of the first optocoupler isolation component is connected to the third output terminal of the ignition energy storage module, the second output terminal of the first optocoupler isolation component is connected to a first reference signal, the first input terminal of the second optocoupler isolation component is connected to the input terminal of the inverter, the first output terminal of the second optocoupler isolation component is connected to the third reference signal, and the second input terminal of the second optocoupler isolation component is connected to the second input terminal of the first optocoupler isolation component;

[0029] The operational amplifier feedback unit includes a second amplifier and a sixth resistor; wherein, the negative input terminal of the second amplifier is connected to the second output terminal of the second optocoupler isolation component, the positive input terminal of the second amplifier is connected to the fourth output terminal of the ignition energy storage module, the output terminal of the second amplifier is connected to the control module, the first terminal of the sixth resistor is connected to the negative input terminal of the second amplifier, and the second terminal of the sixth resistor is connected to the output terminal of the second amplifier.

[0030] In one embodiment, the spark current detection module is further configured to output an ignition event based on the detected spark current, wherein the detection circuit further includes:

[0031] A latching module, connected to both the control module and the spark current detection module, is used to count the ignition events;

[0032] The control module is also used to determine the received ion current signal as an invalid signal if the number of counts exceeds a preset threshold; wherein the number of counts is the number of ignition events counted by the latch module within a preset time.

[0033] Secondly, this application also provides a spark plug. The spark plug includes: an ignition coil, an ignition electrode, and a detection circuit as described in the first aspect; wherein the driving module is connected to the primary coil of the ignition coil, and the ignition energy storage module and the ignition electrode are respectively connected to the secondary coil of the ignition coil.

[0034] The aforementioned detection circuit and spark plug include a drive module, an ignition energy storage module, a spark current detection module, an ion current detection module, and a control module. The drive module is connected to the ignition coil to drive the spark plug to ignite according to a drive enable signal; for example, the drive module can achieve one drive for spark plug ignition based on a single drive enable signal. The ignition energy storage module is connected to both the ignition coil and the ignition electrode to store the ignition energy of the ignition coil during ignition. The spark current detection module is connected to the ignition energy storage module to detect the spark current during ignition and outputs a spark current end indicator signal based on the detected spark current. The ion current detection module is connected to both the ignition energy storage module and the spark current detection module to detect the ion current during ignition based on the spark current end indicator signal. The control module is connected to both the drive module and the ion current detection module to provide a drive enable signal to the drive module and receive the ion current signal output by the ion current detection module to determine the state of the ignition electrode based on the ion current signal. In this embodiment, the ignition energy of the ignition coil is stored during ignition, and the spark current during ignition is detected. The ion current during ignition is then detected based on the spark current end indicator signal. That is, the ion current is detected after the spark current ends during ignition, thereby eliminating the interference of the spark current on the ion current detection and achieving accurate detection of the ion current. Based on the accurately measured ion current, the state of the ignition electrode can be accurately determined. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the detection circuit in one embodiment;

[0036] Figure 2 This is a schematic diagram of the ignition current during the period of driving a spark plug ignition in one embodiment;

[0037] Figure 3 This is a schematic diagram of the detection circuit in one embodiment;

[0038] Figure 4 This is a schematic diagram of a spark current circuit in one embodiment;

[0039] Figure 5 This is a schematic diagram of the ion current loop in one embodiment;

[0040] Figure 6 This is a schematic diagram of the detection circuit in one embodiment;

[0041] Figure 7 This is a schematic diagram of the detection circuit in one embodiment;

[0042] Figure 8 This is a schematic diagram of the detection circuit in one embodiment. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] The detection circuit provided in this application embodiment can be applied to detect the state of spark plugs in an internal combustion engine. Spark plugs are used to initiate combustion in an internal combustion engine; wherein, a spark plug may include an ignition coil T and an ignition electrode, the ignition coil T delivering a pulsed high-voltage current to the ignition electrode to generate an electric spark at the ignition electrode, igniting the gas-fuel mixture in the cylinder; the detection circuit specifically detects the state of the ignition electrode.

[0045] In one embodiment, such as Figure 1 As shown, a detection circuit is provided, including: a driving module 20, an ignition energy storage module 30, a spark current detection module 40, an ion current detection module 50, and a control module 10.

[0046] The drive module 20 is connected to the ignition coil T and is used to drive the spark plug to ignite according to the drive enable signal.

[0047] The ignition coil T may include a primary coil and a secondary coil. The primary coil may be connected to the drive module 20, and the secondary coil may be connected to the ignition electrode. The drive module 20 may be composed of multiple interconnected basic hardware electronic components. The drive module 20 triggers the ignition coil T according to a drive enable signal. The magnetic flux of the primary coil of the ignition coil T changes, causing the secondary coil to generate an extremely high induced electromotive force. This induced electromotive force is applied to the ignition electrode, generating an electric spark at the ignition electrode, thus igniting the spark plug. For example, the drive module 20 can perform one drive for spark plug ignition based on a single drive enable signal.

[0048] The ignition energy storage module 30 is connected to the ignition coil T and the ignition electrode respectively, and is used to store the ignition energy of the ignition coil T.

[0049] The ignition energy storage module 30 can be connected to the secondary coil of the ignition coil T. The ignition energy storage module 30 can store the ignition energy output by the secondary coil during a single spark plug ignition. The period of single spark plug ignition includes the time period for generating the spark current and the time period for generating the ion current; the ignition energy includes both the energy used to generate the spark current and the energy used to generate the ion current.

[0050] The spark current detection module 40 is connected to the ignition energy storage module 30 and is used to detect the spark current during ignition and output a spark current end indicator signal based on the detected spark current. The ion current detection module 50 is connected to both the ignition energy storage module 30 and the spark current detection module 40 and is used to detect the ion current during ignition based on the spark current end indicator signal.

[0051] Among them, reference Figure 2 During the period of spark plug ignition, there are two time periods: time t1 during which spark current is generated and time t2 during which ion current is generated. That is, spark current and ion current are generated in separate time periods, and time period t1 is before time period t2. In other words, spark current is generated before ion current. Only spark current is generated in time period t1, and ion current has not yet been generated. In time period t2, spark current ends and ion current is generated.

[0052] Both the spark current detection module 40 and the ion current detection module 50 can be constructed by interconnecting multiple basic hardware electronic components. The spark current detection module 40 detects the spark current during a single spark plug ignition and outputs a spark current end indicator signal when the spark current is detected to have ended. The ion current detection module 50 only begins detecting the ion current during a single spark plug ignition when it receives the spark current end indicator signal. That is, during a single spark plug ignition, the ion current detection module 50 only performs ion current detection after the spark current has ended (after time period t1 ends), thus eliminating the interference of the spark current on ion current detection and achieving accurate ion current detection. For example, the spark current detection module 40 can determine whether the spark current has ended based on the magnitude and / or direction of the detected spark current.

[0053] The control module 10 is connected to the drive module 20 and the ion current detection module 50 respectively. It is used to provide a drive enable signal to the drive module 20, receive the ion current signal output by the ion current detection module 50, and determine the state of the ignition electrode based on the ion current signal.

[0054] The control module 10 can be composed of devices such as a microprocessor (MCU, Microcontroller Unit). Based on the precise ion current measured by the ion current detection module 50, the control module 10 can accurately determine the state of the ignition electrode. For example, the control module 10 can determine the current degradation coefficient of the ignition electrode based on the comparison result between the ion current and a preset ion current threshold, and then determine whether the ignition electrode is currently in a "smoldering" state based on the current degradation coefficient. The "smoldering" state can be understood as a slow burning state without a flame.

[0055] In this embodiment, the ignition energy storage module 30 stores the ignition energy of the ignition coil T during ignition, and the spark current detection module 40 detects the spark current during ignition to ensure that the ion current detection module 50 detects the ion current during ignition according to the spark current end indicator signal. That is, the ion current detection module 50 detects the ion current after the spark current ends during ignition, thereby eliminating the interference of the spark current on the ion current detection and realizing accurate detection of the ion current. Based on the accurately measured ion current, the control module 10 can accurately determine the state of the ignition electrode.

[0056] In one embodiment, reference Figure 3 The ignition energy storage module 30 includes: an energy storage unit 310, a spark current unit 320, and an ion current unit 330.

[0057] The input terminal of the energy storage unit 310 is connected to the ignition coil T, and the second output terminal of the energy storage unit 310 is connected to the second input terminal of the spark current detection module 40. The energy storage unit 310 is used to store the ignition energy of the ignition coil T.

[0058] The energy storage unit 310 can be connected to the secondary coil of the ignition coil T. The energy storage unit 310 can store the ignition energy output by the secondary coil during a single spark plug ignition. The single spark plug ignition period includes the time period for generating the spark current and the time period for generating the ion current; the ignition energy includes both the energy used to generate the spark current and the energy used to generate the ion current.

[0059] The input terminal of the spark current unit 320 is connected to the first output terminal of the energy storage unit 310, the first output terminal of the spark current unit 320 is connected to the first input terminal of the spark current detection module 40, and the second output terminal of the spark current unit 320 is connected to the first reference signal. The spark current unit 320 is used to form a spark current circuit with the ignition electrode and the ignition coil T according to the ignition energy stored in the energy storage unit 310.

[0060] The drive module 20 triggers the ignition coil T according to the drive enable signal. The magnetic flux of the primary coil of the ignition coil T changes, causing the secondary coil to generate an extremely high induced electromotive force. This induced electromotive force is applied to the ignition electrode, forming a spark current that breaks down the ignition electrode to realize the circuit. That is, the spark current unit 320, the ignition electrode, and the ignition coil T form a spark current circuit. At this time, the current of the secondary coil charges the energy storage unit 310, and the energy storage unit 310 stores ignition energy.

[0061] The first input terminal of the ion current unit 330 is connected to the ignition electrode, the second input terminal of the ion current unit 330 is connected to the first reference signal, the first output terminal of the ion current unit 330 is connected to the first input terminal of the ion current detection module 50, the second output terminal of the ion current unit 330 is connected to the second input terminal of the ion current detection module 50, and the third output terminal of the ion current unit 330 is connected to the first output terminal of the energy storage unit 310. The ion current unit 330 is used to form an ion current loop with the ignition electrode and the ignition coil T based on the ignition energy stored in the energy storage unit 310; wherein, the current flow direction of the spark current loop and the ion current loop is opposite.

[0062] The spark current is extremely short and unstable. As the air-fuel mixture in the internal combustion engine cylinder gradually burns, the spark current ends and the ion current is formed. During the energy storage process of the energy storage unit 310, there is a reverse process from the spark current breaking down the ignition electrode to the energy storage unit 310 participating in the discharge to form the ion current during the combustion process. Therefore, the ion current circuit formed by the ion current unit 330 based on the ignition energy stored in the energy storage unit 310, the ignition electrode, and the ignition coil T has the opposite current flow direction to the spark current circuit formed by the spark current unit 320 based on the ignition energy stored in the energy storage unit 310, the ignition electrode, and the ignition coil T.

[0063] In one embodiment, reference Figure 3 The energy storage unit 310 includes a capacitor assembly and a first diode D1.

[0064] The input terminal of the capacitor assembly is connected to the ignition coil T, the cathode of the first diode D1 is connected to the input terminal of the capacitor assembly, the anode of the first diode D1 is connected to the output terminal of the capacitor assembly, and the anode of the first diode D1 is connected to the second input terminal of the spark current detection module 40.

[0065] The voltage on the secondary coil of the ignition coil T is typically very high. The first diode D1 clamps the voltage supplied to the energy storage unit 310 within a safe voltage range; that is, the first diode D1 acts as a voltage regulator. For example, the first diode D1 is a Schottky diode. For example, the capacitor assembly includes a capacitor C1, with its first terminal connected to the secondary coil of the ignition coil T and its second terminal connected to the anode of the first diode D1.

[0066] In one embodiment, reference Figure 3 The spark current unit 320 includes: a first resistor R1 and a second diode D2.

[0067] The first end of the first resistor R1 is connected to the output end of the capacitor assembly, the anode of the second diode D2 is connected to the second end of the first resistor R1, the anode of the second diode D2 is connected to the first input end of the spark current detection module 40, and the cathode of the second diode D2 is connected to the first reference signal.

[0068] The first resistor R1 can be understood as the spark current sampling resistor. For example, the second diode D2 is a Schottky diode. For example, the spark current loop in the spark current unit 320 is as follows: Figure 4 As shown, the spark current flows counterclockwise; the energy of the secondary coil can be stored by capacitor C1. Due to the presence of the first diode D1, the ignition energy voltage is clamped within a safe voltage range. The ignition energy includes the energy of the initial spark current and part of the energy of the ion current caused by the subsequent combustion. The current in the secondary coil is charged through capacitor C1, flows through the first resistor R1 and the second diode D2 into the reference power ground, and then returns to the high end of the secondary coil through the ignition electrode, forming a spark current loop. Figure 4 In this diagram, L represents the secondary coil, and R represents the dielectric resistance formed after the combustion of the gas mixture.

[0069] In one embodiment, reference Figure 3 The ion current unit 330 includes: a second resistor R2 and a third diode D3.

[0070] The first end of the second resistor R2 is connected to the output end of the capacitor assembly. The first end of the second resistor R2 is connected to the first input end of the ion current detection module 50. The cathode of the third diode D3 is connected to the second end of the second resistor R2. The cathode of the third diode is connected to the second input end of the ion current detection module 50. The anode of the third diode D3 is connected to the ignition electrode. The anode of the third diode D3 is connected to the first reference signal.

[0071] For example, during energy storage, when the spark current breaks down the electrode to participate in the discharge of capacitor C1 and forms the ion current during combustion, the current direction will reverse. Figure 5 As shown, the ion current flows clockwise, passing sequentially through the electrode, the third diode D3, and the second resistor R2 into the low end of the secondary coil, forming an ion current loop. The spark current sampling resistor, being floating, has zero voltage difference across it. Figure 5 In this diagram, L represents the secondary coil, and R represents the dielectric resistance formed after the combustion of the gas mixture.

[0072] In one embodiment, reference Figure 6 The spark current detection module 40 includes an amplification unit 410 and a comparison unit 420.

[0073] The first input terminal of the amplification unit 410 is connected to the first output terminal of the ignition energy storage module 30, and the second input terminal of the amplification unit 410 is connected to the second output terminal of the ignition energy storage module 30. The amplification unit 410 is used to detect the spark current during ignition.

[0074] In this process, after the spark current loop is formed, the amplification unit 410 detects the spark current in the spark current loop.

[0075] The input terminal of the comparison unit 420 is connected to the output terminal of the amplification unit 410, and the output terminal of the comparison unit 420 is connected to the third input terminal of the ion current detection module 50. The comparison unit 420 is used to output a spark current end indicator signal based on the spark current detected by the amplification unit 410.

[0076] For example, the comparison unit 420 can determine whether the spark current has ended based on the magnitude and / or direction of the detected spark current, and output a spark current end indicator signal when the spark current is determined to have ended.

[0077] In one embodiment, reference Figure 6 The amplification unit 410 includes: a first amplifier U1A and a third resistor R3.

[0078] The negative input terminal of the first amplifier U1A is connected to the first output terminal of the ignition energy storage module 30, the positive input terminal of the first amplifier U1A is connected to the second output terminal of the ignition energy storage module 30, the first terminal of the third resistor R3 is connected to the negative input terminal of the first amplifier U1A, and the second terminal of the third resistor R3 is connected to the output terminal of the first amplifier U1A.

[0079] Among them, the differential amplifier based on operational amplifier U1A can detect the current value of the current loop of the spark current, that is, detect the spark current.

[0080] In one embodiment, reference Figure 6 The comparison unit 420 includes: a first comparator U1C1, a second comparator U1C2, a fourth resistor R4, and a fifth resistor R5.

[0081] The negative input terminal of the first comparator U1C1 is connected to the output terminal of the first amplifier U1A. The positive input terminal of the first comparator U1C1 is connected to the second reference signal VREF. The first terminal of the fourth resistor R4 is connected to the negative input terminal of the first comparator U1C1, and the second terminal of the fourth resistor R4 is connected to the second reference signal VREF. The first terminal of the fifth resistor R5 is connected to the negative input terminal of the first comparator U1C1, and the second terminal of the fifth resistor R5 is connected to the third reference signal. The negative input terminal of the second comparator U1C2 is connected to the negative input terminal of the first comparator U1C1. The positive input terminal of the second comparator U1C2 is connected to the second reference signal VREF, and the output terminal of the second comparator U1C2 is connected to the output terminal of the first comparator U1C1.

[0082] The spark current sample is amplified by the third resistor R3 and coupled with the bias voltage VREF obtained by voltage division by the fourth resistor R4 and the fifth resistor R5. It is then compared with the reference voltage VREF of the first comparator U1C1 and the second comparator U1C2, and a spark current end indicator signal is output based on the comparison result.

[0083] For example, when the ignition current is the spark current, the direction of the ignition current is counterclockwise. At this time, the op-amp U1A outputs a positive voltage, triggering the positive threshold of U1C1. When the spark current ends, the direction of the ignition current is clockwise. Since the op-amp U1A is configured as "rail-to-rail", it can output a negative voltage. At this time, the negative threshold of U1C2 is triggered. After the positive and negative voltage thresholds are flipped, a spark current end indicator signal is generated.

[0084] In one embodiment, reference Figure 7 The ion current detection module 50 includes: an inverting isolation unit 510 and an operational amplifier feedback unit 520.

[0085] The first input terminal of the inverting isolation unit 510 is connected to the output terminal of the spark current detection module 40, and the second input terminal of the inverting isolation unit 510 is connected to the third output terminal of the ignition energy storage module 30. The inverting isolation unit 510 is used to release the ignition energy corresponding to the spark current according to the spark current end indicator signal.

[0086] After the spark current ends, the ignition energy corresponding to the spark current during time period t1 is discharged through the inverting isolation unit 510. The first input terminal of the operational amplifier feedback unit 520 is connected to the output terminal of the inverting isolation unit 510, the second input terminal of the operational amplifier feedback unit 520 is connected to the fourth output terminal of the ignition energy storage module 30, and the output terminal of the operational amplifier feedback unit 520 is connected to the control module 10. The operational amplifier feedback unit 520 is used to detect the ion current during ignition.

[0087] In one embodiment, reference Figure 7 The inverting isolation unit 510 includes: an inverter U1D, a first optocoupler isolation component ISO1, and a second optocoupler isolation component ISO2.

[0088] The input terminal of inverter U1D is connected to the output terminal of spark current detection module 40. The first input terminal of first optocoupler isolation component ISO1 is connected to the output terminal of inverter U1D. The first output terminal of first optocoupler isolation component ISO1 is connected to the third reference signal. The second input terminal of first optocoupler isolation component ISO1 is connected to the third output terminal of ignition energy storage module 30. The second output terminal of first optocoupler isolation component ISO1 is connected to the first reference signal. The first input terminal of second optocoupler isolation component ISO2 is connected to the input terminal of inverter U1D. The first output terminal of second optocoupler isolation component ISO2 is connected to the third reference signal. The second input terminal of second optocoupler isolation component ISO2 is connected to the second input terminal of first optocoupler isolation component ISO1.

[0089] Among them, the spark current end indicator signal is output to the optocoupler and other isolation devices through the inverter U1D to perform the input switching of the ion current detection circuit; when spark current is detected, the ion current detection circuit is activated to the reference ground; when spark current ends, the ion current detection circuit is activated to remove the energy influence of spark current in the energy storage of capacitor C1.

[0090] In one embodiment, reference Figure 7 The operational amplifier feedback unit 520 includes: a second amplifier U1B and a sixth resistor R6.

[0091] The negative input terminal of the second amplifier U1B is connected to the second output terminal of the second optocoupler isolation component ISO2, the positive input terminal of the second amplifier U1B is connected to the fourth output terminal of the ignition energy storage module 30, the output terminal of the second amplifier U1B is connected to the control module 10, the first terminal of the sixth resistor R6 is connected to the negative input terminal of the second amplifier U1B, and the second terminal of the sixth resistor R6 is connected to the output terminal of the second amplifier U1B.

[0092] In this embodiment, after the spark current ends, the ion current detection is activated. That is, after the ion current loop is formed and the spark current ends, the ion current detection module 50 detects the ion current in the ion current loop. At this time, the ion current sampling loop forms a sampling loop through the isolation device, and the charge detection of the ion current is realized through the feedback loop composed of operational amplifier U1B.

[0093] Currently, in the application of technologies such as ultra-lean combustion or exhaust gas recirculation (EGR), it is necessary to ensure that the lean mixture is uniformly mixed and diffused within the cylinder to improve the utilization rate of ignition energy. However, this may create air turbulence within the cylinder. This turbulence can extinguish the spark discharge between the electrodes during the T-discharge phase of the ignition coil. Many ignition systems with hardware self-feedback in related technologies achieve over-ignition based on the current sampling of the secondary coil. This abnormal and frequent over-ignition not only greatly reduces the quality and lifespan of the spark plugs but also causes significant interference with ion current detection.

[0094] In response to this, in one embodiment of this application, reference is made to Figure 8 The detection circuit also includes a latch module 60.

[0095] The latch module 60 is connected to both the control module 10 and the spark current detection module 40. The latch module 60 may include a latch. For example, the latch module 60 may include a D flip-flop.

[0096] The spark current detection module 40 is also used to output an ignition event based on the detected spark current; the latch module 60 is used to count the ignition events; the control module 10 is also used to determine the received ion current signal as an invalid signal if the number of counts exceeds a preset threshold; wherein, the number of counts is the number of ignition events counted by the latch module 60 within a preset time.

[0097] For example, the spark current detection module 40 can output an electrical signal corresponding to an ignition event based on the magnitude and / or direction of the detected spark current. The latching module 60 counts ignition events based on this electrical signal, with one electrical signal counting as one ignition event. The control module 10 obtains the count count from the latching module 60; when the control module 10 determines that the count count exceeds a preset threshold within a preset time, it determines that a superignition has occurred. At this time, the detected ion current is not accurate enough, so the control module 10 determines the received ion current signal as an invalid signal and does not determine the state of the ignition electrode. The preset time is, for example, the time required to drive one spark plug ignition; that is, if multiple ignition events are counted during the period of driving one spark plug ignition, a superignition is determined to have occurred.

[0098] For example, when the ignition current is the spark current, the direction of the ignition current is counterclockwise. At this time, the operational amplifier U1A outputs a positive voltage, triggering the positive threshold of U1C1, thus triggering the ignition event and outputting the electrical signal corresponding to the ignition event. When the spark current ends, the direction of the ignition current is clockwise. Since the operational amplifier U1A is configured as a rail-to-rail amplifier, it can output a negative voltage. At this time, the negative threshold of U1C2 is triggered. After the positive and negative voltage thresholds are flipped, a spark current end indicator signal is generated.

[0099] Based on the same inventive concept, this application also provides a spark plug. The spark plug includes an ignition coil T, an ignition electrode, and a detection circuit provided in any of the above embodiments; wherein, the drive module 20 is connected to the primary coil of the ignition coil T, and the ignition energy storage module 30 and the ignition electrode are respectively connected to the secondary coil of the ignition coil T. The spark plug provided in this application provides a solution to the problem similar to the solution described in the detection circuit above. The spark plug and the detection circuit can solve the same technical problem and achieve the same technical effect; therefore, repeated details will not be elaborated here.

[0100] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A spark plug condition detection circuit, characterized in that, The spark plug includes an ignition coil and an ignition electrode, the ignition coil being connected to the ignition electrode, and the detection circuit including: The drive module is connected to the ignition coil and is used to drive the spark plug to ignite according to the drive enable signal; An ignition energy storage module is connected to the ignition coil and the ignition electrode respectively, and is used to store the ignition energy of the ignition coil. The spark current detection module is connected to the ignition energy storage module and is used to detect the spark current during ignition, output a spark current end indicator signal based on the detected spark current, and output an ignition event based on the detected spark current. A latching module, connected to the spark current detection module, is used to count the ignition events; An ion current detection module is connected to both the ignition energy storage module and the spark current detection module, and is used to detect the ion current during ignition based on the spark current end indicator signal. The control module is connected to the drive module, the latch module and the ion current detection module respectively, and is used to provide the drive enable signal, receive the ion current signal output by the ion current detection module, and determine the state of the ignition electrode according to the ion current signal. The control module is further configured to determine the received ion current signal as an invalid signal if the number of counts exceeds a preset threshold; wherein the number of counts is the number of ignition events counted by the latching module within a preset time; and the preset time is the time required to drive a spark plug to ignite once.

2. The spark plug condition detection circuit according to claim 1, characterized in that, The ignition energy storage module includes: An energy storage unit is provided, wherein the input terminal of the energy storage unit is connected to the ignition coil, and the second output terminal of the energy storage unit is connected to the second input terminal of the spark current detection module. The energy storage unit is used to store the ignition energy of the ignition coil. A spark current unit, wherein the input terminal of the spark current unit is connected to the first output terminal of the energy storage unit, the first output terminal of the spark current unit is connected to the first input terminal of the spark current detection module, and the second output terminal of the spark current unit is connected to a first reference signal. The spark current unit is used to form a spark current loop with the ignition electrode and the ignition coil based on the ignition energy stored in the energy storage unit. An ion current unit is provided, wherein its first input terminal is connected to the ignition electrode, its second input terminal is connected to a first reference signal, its first output terminal is connected to the first input terminal of the ion current detection module, its second output terminal is connected to the second input terminal of the ion current detection module, and its third output terminal is connected to the first output terminal of the energy storage unit. The ion current unit is used to form an ion current loop with the ignition electrode and the ignition coil based on the ignition energy stored in the energy storage unit; wherein the current flow direction of the spark current loop is opposite to that of the ion current loop.

3. The spark plug condition detection circuit according to claim 2, characterized in that, The energy storage unit includes a capacitor assembly and a first diode; wherein, the input terminal of the capacitor assembly is connected to the ignition coil, the cathode of the first diode is connected to the input terminal of the capacitor assembly, the anode of the first diode is connected to the output terminal of the capacitor assembly, and the anode of the first diode is connected to the second input terminal of the spark current detection module. The spark current unit includes: a first resistor and a second diode; wherein, the first end of the first resistor is connected to the output end of the capacitor assembly, the anode of the second diode is connected to the second end of the first resistor, the anode of the second diode is connected to the first input end of the spark current detection module, and the cathode of the second diode is connected to a first reference signal. The ion current unit includes a second resistor and a third diode; wherein, the first end of the second resistor is connected to the output end of the capacitor assembly, the first end of the second resistor is connected to the first input end of the ion current detection module, the cathode of the third diode is connected to the second end of the second resistor, the cathode of the third diode is connected to the second input end of the ion current detection module, the anode of the third diode is connected to the ignition electrode, and the anode of the third diode is connected to a first reference signal.

4. The spark plug condition detection circuit according to claim 1, characterized in that, The spark current detection module includes: An amplification unit is provided, wherein a first input terminal of the amplification unit is connected to a first output terminal of the ignition energy storage module, and a second input terminal of the amplification unit is connected to a second output terminal of the ignition energy storage module. The amplification unit is used to detect the spark current during ignition. The comparison unit has its input terminal connected to the output terminal of the amplification unit, and its output terminal connected to the third input terminal of the ion current detection module. The comparison unit is used to output a spark current end indicator signal based on the spark current detected by the amplification unit.

5. The spark plug condition detection circuit according to claim 4, characterized in that, The amplification unit includes: a first amplifier and a third resistor; The negative input terminal of the first amplifier is connected to the first output terminal of the ignition energy storage module, the positive input terminal of the first amplifier is connected to the second output terminal of the ignition energy storage module, the first terminal of the third resistor is connected to the negative input terminal of the first amplifier, and the second terminal of the third resistor is connected to the output terminal of the first amplifier.

6. The spark plug condition detection circuit according to claim 5, characterized in that, The comparison unit includes: a first comparator, a second comparator, a fourth resistor, and a fifth resistor; The negative input terminal of the first comparator is connected to the output terminal of the first amplifier, the positive input terminal of the first comparator is connected to the second reference signal, the first terminal of the fourth resistor is connected to the negative input terminal of the first comparator, the second terminal of the fourth resistor is connected to the second reference signal, the first terminal of the fifth resistor is connected to the negative input terminal of the first comparator, and the second terminal of the fifth resistor is connected to the third reference signal. The negative input terminal of the second comparator is connected to the negative input terminal of the first comparator, the positive input terminal of the second comparator is connected to the second reference signal, and the output terminal of the second comparator is connected to the output terminal of the first comparator.

7. The spark plug condition detection circuit according to claim 1, characterized in that, The ion current detection module includes: An inverting isolation unit is provided, wherein the first input terminal of the inverting isolation unit is connected to the output terminal of the spark current detection module, and the second input terminal of the inverting isolation unit is connected to the third output terminal of the ignition energy storage module. The inverting isolation unit is used to release the ignition energy corresponding to the spark current according to the spark current end indicator signal. The operational amplifier feedback unit has its first input terminal connected to the output terminal of the inverting isolation unit, its second input terminal connected to the fourth output terminal of the ignition energy storage module, and its output terminal connected to the control module. The operational amplifier feedback unit is used to detect the ion current during ignition.

8. The spark plug condition detection circuit according to claim 7, characterized in that, The phase-inverting isolation unit includes: an inverter, a first optocoupler isolation component, and a second optocoupler isolation component; wherein, the input terminal of the inverter is connected to the output terminal of the spark current detection module, the first input terminal of the first optocoupler isolation component is connected to the output terminal of the inverter, the first output terminal of the first optocoupler isolation component is connected to a third reference signal, the second input terminal of the first optocoupler isolation component is connected to the third output terminal of the ignition energy storage module, the second output terminal of the first optocoupler isolation component is connected to a first reference signal, the first input terminal of the second optocoupler isolation component is connected to the input terminal of the inverter, the first output terminal of the second optocoupler isolation component is connected to the third reference signal, and the second input terminal of the second optocoupler isolation component is connected to the second input terminal of the first optocoupler isolation component; The operational amplifier feedback unit includes a second amplifier and a sixth resistor; wherein, the negative input terminal of the second amplifier is connected to the second output terminal of the second optocoupler isolation component, the positive input terminal of the second amplifier is connected to the fourth output terminal of the ignition energy storage module, the output terminal of the second amplifier is connected to the control module, the first terminal of the sixth resistor is connected to the negative input terminal of the second amplifier, and the second terminal of the sixth resistor is connected to the output terminal of the second amplifier.

9. A spark plug, characterized in that, It includes an ignition coil, an ignition electrode, and a spark plug condition detection circuit as described in any one of claims 1-8; wherein the driving module is connected to the primary coil of the ignition coil, and the ignition energy storage module and the ignition electrode are respectively connected to the secondary coil of the ignition coil.

Images