Igniter detection circuit based on electromagnetic induction

Abstract

An electromagnetic induction based igniter detection circuit includes an induction coil, a bidirectional clamping circuit, an amplification unit and an indication unit. One end of the induction coil is grounded, and the other end serves as a signal output end; the bidirectional clamping circuit is composed of two diodes connected in parallel in opposite directions and is connected between the signal output end and the ground, for limiting and protecting the induction signal; the amplification unit is composed of two-stage triodes connected in series, the base of triode Q1 receives the induction signal, the emitter of triode Q1 is connected to the base of triode Q2, the emitter of triode Q2 is grounded, and the collectors of the two triodes are commonly connected to the cathode of a light-emitting diode; the anode of the light-emitting diode is connected to the positive pole of a power supply through a current-limiting resistor, constituting the indication unit. The induction coil induces the change of the external magnetic field to generate an induction voltage, which drives the light-emitting diode to light up after clamping protection and amplification processing, realizing visual indication of the electromagnetic energy state of the ignition system, and having the characteristics of simple structure, sensitive response and strong stability.

Description

Technical Field

[0001] This utility model relates to the field of automotive detection circuit technology, specifically to an ignition detection circuit based on electromagnetic induction. Background Technology

[0002] In internal combustion engine vehicles, the ignition coil, as the core component of the ignition system, is responsible for converting the low voltage supplied by the vehicle's power supply into a high voltage that can drive the spark plugs to discharge, thereby igniting the combustible mixture in the engine cylinders. To ensure normal engine starting and efficient combustion, the ignition coil output must have sufficient ignition energy.

[0003] However, under prolonged use or conditions such as high temperature, aging, or poor contact, the ignition coil and related components are prone to malfunctions such as weakened ignition energy and intermittent sparks, which can lead to a series of problems such as difficulty starting, insufficient power, increased fuel consumption, and excessive emissions.

[0004] Most widely used ignition systems currently lack effective online testing methods. Common testing methods mainly include vehicle malfunction indicator lamp (MIL) warnings and oscilloscope measurements. These traditional methods have significant shortcomings: First, they typically only measure the presence or absence of voltage, failing to provide a direct assessment of whether ignition energy is adequate or to capture minute changes during the ignition process. Second, there is a delay in feedback; users often only notice problems after engine performance deteriorates or a malfunction occurs, lacking real-time warning capabilities. Third, operation is complex; traditional testing relies on specialized instruments or technicians, making it difficult for general users to complete independently, lacking visualization and ease of use.

[0005] Therefore, in order to solve the problems of the above-mentioned unintuitive indication method, an ignition detection circuit based on electromagnetic induction is needed. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by proposing an ignition detection circuit based on electromagnetic induction. The specific technical solution is as follows:

[0007] An ignition detection circuit based on electromagnetic induction, characterized in that:

[0008] It includes an induction coil L1, a bidirectional clamping circuit, an amplification unit, and an indication unit;

[0009] One end of the induction coil L1 is connected to the ground terminal GND, and the other end serves as the signal output terminal.

[0010] The bidirectional clamping circuit includes diodes D1 and D2, with diodes D1 and D2 having opposite directions and connected in parallel between the signal output terminal and the ground terminal GND, for voltage clamping protection of the signal;

[0011] The amplification unit includes transistors Q1 and Q2. The base of transistor Q1 is connected to the signal output terminal, and the emitter is connected to the base of transistor Q2. The emitter of transistor Q2 is connected to the ground terminal GND. The collectors of transistors Q1 and Q2 are connected in parallel.

[0012] The indicator unit includes a light-emitting diode D3 and a current-limiting resistor R2. The anode of the light-emitting diode D3 is connected to the positive terminal of the power supply BT through the current-limiting resistor R2, and the cathode of the light-emitting diode D3 is connected to the parallel connection of the collectors of transistors Q1 and Q2.

[0013] The induction coil L1 is used to sense changes in the external magnetic field and generate an induced voltage signal. This induced voltage signal is protected by the bidirectional clamping circuit, amplified by the amplification unit, and then drives the light-emitting diode D3 to indicate the change in the external electromagnetic signal.

[0014] To better realize this utility model, it can be further made as follows:

[0015] It also includes a filtering network, which includes a resistor R3 and a capacitor C1. The capacitor C1 and the resistor R3 are connected in parallel between the signal output terminal and the ground terminal GND to filter out high-frequency interference signals.

[0016] Furthermore: the negative terminal of the power supply BT is connected to the first terminal of the switch S1, and the second terminal of the switch S1 is connected to the ground terminal GND.

[0017] Furthermore, an electrolytic capacitor C2 is connected across the negative terminal of the power supply BT and the second terminal of the switch S1.

[0018] Furthermore, a coupling capacitor C3 is connected in series between the signal output terminal of the induction coil L1 and the transistor Q1 to isolate the DC bias signal.

[0019] The beneficial effects of this utility model are as follows:

[0020] First, by setting up the structure of the induction coil L1 and the bidirectional clamping circuit, the instantaneous pulse magnetic field of the ignition coil can be accurately sensed and protected, avoiding the problem of poor adaptability of traditional voltage acquisition methods to high-voltage environments. This improves the reliability and detection accuracy of signal acquisition, effectively identifies the strength changes of ignition energy, and realizes non-invasive magnetic field detection without direct contact.

[0021] Secondly, the amplification unit adopts a Darlington transistor structure, which is formed by connecting transistors Q1 and Q2 in series to form a high-current gain path. This can effectively amplify the weak voltage signal generated by the induction coil and drive the subsequent light-emitting diode D3 to emit light, forming a clear visual indication effect. Compared with the traditional single-transistor amplification scheme, it has higher sensitivity and more stable response output, ensuring that changes in ignition status can be fed back in a timely manner.

[0022] Third, the indicator unit uses a light-emitting diode D3 and a current-limiting resistor R2 to form a simple and intuitive ignition status display mechanism. The "on / off" state reflects the ignition magnetic field strength, allowing users to determine whether the ignition system is normal without any professional knowledge. At the same time, this structure does not rely on a microcontroller or programming device, which simplifies system design, reduces costs, and improves the overall anti-interference capability, making it suitable for long-term use in the complex environment of the engine compartment. Attached Figure Description

[0023] Figure 1 This is a circuit structure diagram of the present invention. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0025] In the description of this utility model, it should be noted that the terms "vertical," "upper," "lower," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] like Figure 1 As shown:

[0027] An ignition detection circuit based on electromagnetic induction includes an induction coil L1, a bidirectional clamping circuit, a filter network, an amplification unit, an indicator unit, a power supply BT, and a switch S1.

[0028] Specifically, the bidirectional clamping circuit includes diodes D1 and D2, the filter network includes resistor R3 and capacitor C1, and the amplification unit includes transistors Q1 and Q2, resistor R1, and coupling capacitor C3.

[0029] The indicator unit includes a light-emitting diode D3 and a current-limiting resistor R2. The negative terminal of the power supply BT is connected to the first terminal of the switch S1, and an electrolytic capacitor C2 is connected in parallel between the second terminal of the switch S1 and the ground terminal GND.

[0030] The induction coil L1 is made of enameled copper wire and has a hollow structure. The first end of the induction coil L1 is connected to the ground terminal GND, and the second end serves as the signal output terminal A, which is used to sense the induced voltage signal generated by the change of the external magnetic field.

[0031] The induction coil L1 is fixedly installed inside a non-magnetic housing, positioned by a slot and fixed at the end with epoxy resin to prevent vibration from interfering with measurement accuracy.

[0032] The signal output terminal A of the induction coil L1 is connected to the bidirectional clamping circuit, which is composed of two diodes D1 and D2 of type 1N4148. The anode of diode D1 is connected to the signal output terminal A, and the cathode of diode D1 is connected to the ground terminal GND. The cathode of diode D2 is connected to the signal output terminal A, and the anode of diode D2 is grounded.

[0033] The two diodes connected in parallel with opposite directions form a bidirectional clamping structure to prevent instantaneous high voltage from breaking down the base of the subsequent transistor Q1.

[0034] A filter network is connected in parallel between the signal output terminal A and the ground terminal GND. This filter network is used to filter out high-frequency interference signals. The filter network consists of a resistor R3 and a capacitor C1, where the capacitor C1 is a ceramic capacitor. The resistor R3 and the capacitor C1 form an RC low-pass filter structure, which is used to filter out unnecessary high-frequency components in the induced signal and improve the circuit stability.

[0035] A coupling capacitor C3 is connected in series between the signal output terminal A and the base of transistor Q1. The capacitor C3 is a 10nF ceramic capacitor used to isolate the DC bias signal and allow only the AC component to enter the subsequent amplifier circuit, so as to ensure that the base voltage of transistor Q1 is stable in the normal operating state.

[0036] Specifically, the amplification unit includes transistors Q1 and Q2, both of which are NPN low-power transistors of type S9013, connected in series to form a Darlington amplification structure.

[0037] The base of transistor Q1 is connected to the signal output terminal of induction coil L1 through coupling capacitor C3. The emitter of transistor Q1 is connected to the base of transistor Q2, and the emitter of transistor Q2 is connected to ground GND. The collectors of transistors Q1 and Q2 are connected in parallel.

[0038] The indicator unit consists of a light-emitting diode (LED) D3 and a current-limiting resistor R2. The LED D3 is a standard red LED device. The anode of the LED D3 is connected to the positive terminal of the power supply BT through the current-limiting resistor R2, and the cathode is connected to the collector terminals of transistors Q1 and Q2 connected in parallel.

[0039] Resistor R2 is used to limit the LED's operating current, ensuring stable light emission without burning out.

[0040] The power supply BT is a DC power supply. The negative terminal of the power supply BT is connected to the first terminal of switch S1, and the second terminal of switch S1 is connected to the ground terminal GND to realize manual power-off control.

[0041] A capacitor C2 is connected between the positive terminal of the power supply BT and the second terminal of the switch S1 to provide transient voltage response and current buffer for the power supply circuit, thereby stabilizing the overall working state of the machine.

[0042] The induction coil L1 adopts a hollow winding structure. The first end of the induction coil L1 is grounded, and the second end is used as the signal output end.

[0043] Induction coil L1 is used to sense the strong pulsed magnetic field generated by the ignition coil during high-voltage discharge, outputting an alternating positive and negative induced voltage signal. The induced signal first enters the clamping protection network, where a bidirectional clamping circuit composed of diodes D1 and D2 provides amplitude limiting protection. The anode of diode D1 is connected to the signal output terminal, and the cathode is connected to the ground terminal GND. Diode D2 is connected in the opposite direction, forming a back-to-back parallel structure to prevent high-amplitude voltage spikes from damaging the subsequent transistor Q1.

[0044] The limited induced signal further enters a filter network, consisting of resistor R3 and capacitor C1 connected in parallel. This RC network is connected between the signal output terminal and ground, forming a first-order low-pass filter to suppress high-frequency noise interference and retain only the main frequency response signal. Subsequently, it is coupled to the base of transistor Q1 via coupling capacitor C3. Capacitor C3 is used to isolate DC bias, ensuring that the subsequent amplifier circuit only responds to changes in the alternating signal.

[0045] In the amplification unit, the forward voltage of the induced signal drives the base potential of transistor Q1 to rise, forming a forward bias. After transistor Q1 turns on, the emitter output current of transistor Q1 further drives the base of transistor Q2, causing transistor Q2 to turn on synchronously, thus forming a Darlington amplification. This Darlington structure has high overall current gain, which can effectively amplify weak induced signals to drive light-emitting diodes.

[0046] When the external ignition magnetic field increases, causing the induced voltage amplitude of the induction coil L1 to be sufficient to drive the Darlington structure to conduct, transistors Q1 and Q2 conduct, and their parallel collector potential decreases, forming a current path. The current flows sequentially through the positive terminal of the power supply BT, the current-limiting resistor R2, the LED D3, the collectors of transistors Q1 and Q2, and then to the ground terminal GND, thus lighting up LED D3. If the external magnetic field changes weakly or there is no ignition signal, the induced voltage is insufficient to turn on transistors Q1 and Q2, and LED D3 does not light up.

[0047] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An ignition detection circuit based on electromagnetic induction, characterized in that: It includes an induction coil L1, a bidirectional clamping circuit, an amplification unit, and an indication unit; One end of the induction coil L1 is connected to the ground terminal GND, and the other end serves as the signal output terminal. The bidirectional clamping circuit includes diodes D1 and D2, with diodes D1 and D2 having opposite directions and connected in parallel between the signal output terminal and the ground terminal GND, for voltage clamping protection of the signal; The amplification unit includes transistors Q1 and Q2. The base of transistor Q1 is connected to the signal output terminal, and the emitter is connected to the base of transistor Q2. The emitter of transistor Q2 is connected to the ground terminal GND. The collectors of transistors Q1 and Q2 are connected in parallel. The indicator unit includes a light-emitting diode D3 and a current-limiting resistor R2. The anode of the light-emitting diode D3 is connected to the positive terminal of the power supply BT through the current-limiting resistor R2, and the cathode of the light-emitting diode D3 is connected to the parallel connection of the collectors of transistors Q1 and Q2. The induction coil L1 is used to sense changes in the external magnetic field and generate an induced voltage signal. This induced voltage signal is protected by the bidirectional clamping circuit, amplified by the amplification unit, and then drives the light-emitting diode D3 to indicate the change in the external electromagnetic signal.

2. The ignition detection circuit based on electromagnetic induction according to claim 1, characterized in that: It also includes a filtering network, which includes a resistor R3 and a capacitor C1. The capacitor C1 and the resistor R3 are connected in parallel between the signal output terminal and the ground terminal GND to filter out high-frequency interference signals.

3. The ignition detection circuit based on electromagnetic induction according to claim 2, characterized in that: The negative terminal of the power supply BT is connected to the first terminal of the switch S1, and the second terminal of the switch S1 is connected to the ground terminal GND.

4. The ignition detection circuit based on electromagnetic induction according to claim 3, characterized in that: An electrolytic capacitor C2 is connected between the negative terminal of the power supply BT and the second terminal of the switch S1.

5. The ignition detection circuit based on electromagnetic induction according to claim 4, characterized in that: A coupling capacitor C3 is connected in series between the signal output terminal of the induction coil L1 and the transistor Q1 to isolate the DC bias signal.

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