Ignition coil of internal combustion engine

Abstract

The ignition coil of the internal combustion engine comprises a primary coil and a secondary coil, the primary coil is connected with a switch element and used for receiving ignition signals, the secondary coil is provided with an output end in coupling connection with a spark plug gap, and a high-voltage input end is further connected between the spark plug gap and the secondary coil in parallel. According to the ignition coil of the internal combustion engine, the high-voltage output end of the secondary coil is connected with the high-voltage input end in parallel. After the secondary coil discharges to establish breakdown voltage, the high-voltage input end can be used as a continuous ignition energy input end to provide continuous ignition energy and continuous supply current for the spark plug gap, so that the continuous supply current can be controlled according to control requirements in an extremely short time, and the ignition efficiency is remarkably improved.

Description

Technical Field

[0001] The utility model relates to the field of internal combustion engine ignition control, and particularly relates to an ignition coil for an internal combustion engine. Background Technique

[0002] To further improve the efficiency of spark-ignition engines, intake dilution and in-cylinder strong flow technologies are widely adopted. However, under such operating conditions, the stable ignition of the combustible mixture is particularly important for maintaining the stable operation of the engine. Increasing the ignition duration and the ignition current intensity are considered effective methods for achieving lean mixtures. However, a high discharge current level and a long discharge duration will lead to an increase in the power consumption of the ignition system. More importantly, it will accelerate the electro-corrosion of the spark plug electrodes, resulting in a reduction in the durability of the spark plug electrodes.

[0003] During the engine ignition process, the plasma channel elongated due to in-cylinder flow increases the ignition volume, which is beneficial to generating a more stable initial fire kernel. However, the elongation of the plasma will also cause situations such as the ignition channel being interrupted and blown out, making the initial fire kernel dispersed, thus causing misfires. By timely adjusting the impedance of the ignition plasma channel, the probability of the plasma channel being blown off can be effectively avoided.

[0004] The impedance of the plasma channel is mainly determined by the plasma length, the background density and temperature, and the discharge current. The change of the discharge current can control the ionization degree of the plasma channel, and it is also the most effective method for controlling the plasma impedance. By quickly and adaptively adjusting the discharge current at the microsecond level, it can effectively ensure that the plasma continuously discharges for 2 to 3 milliseconds during the ignition process, thereby ensuring the ignition effect. Therefore, it is necessary to provide an ignition coil that can respond quickly to provide a fast and adaptive discharge current for the spark plug gap.

[0005] At present, there are many publicly available ignition systems with the function of extending the ignition duration. The most influential among them is the dual-coil offset ignition system. Different companies and research groups have applied for a number of patents regarding the structure, settings, and control methods of the dual-coil system, mainly to optimize the working process of the dual-coil ignition system, such as controlling the discharge current intensity and real-time detection of the situation where the plasma is blown out. For example, the US patent publication document with the publication number "US20120160222A1" and the name "DUAL COIL IGNITION". It discloses an improved automotive dual-cycle ignition system. However, due to the lack of fast hardware control and control logic, it is impossible to provide appropriate ignition energy and power in real time according to the engine requirements in this patent. Another example is the Chinese patent publication document with the publication number "CN113217249A" and the name "Ignition Control System, Engine, Ignition Control Method, and Storage Medium". It discloses an ignition control system, an engine, an ignition control method, and a storage medium. The ignition control system includes a logic calculation drive control module, a constant current power output module, an ignition coil drive module, an ignition coil module, and an energy storage capacitor. The logic calculation drive control module can receive an ignition control instruction and obtain ignition control parameter information including ignition charging parameter information and ignition discharge parameter information. The discharge current of the dual-coil ignition strategy adopted in the disclosed patent is relatively low, and it is impossible to prevent the plasma from being blown out by increasing the discharge current. Therefore, it is of great significance to propose an internal combustion engine ignition coil with a faster response speed in this field. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present utility model provides an internal combustion engine ignition coil, which includes a primary coil and a secondary coil. The primary coil is connected to a switching element for receiving an ignition signal. The secondary coil has an output end coupled to the spark plug gap, and a high-voltage input end is also connected in parallel between the spark plug gap and the secondary coil.

[0007] Further, a unidirectional circuit two is connected between the high-voltage input end and the output end of the secondary coil.

[0008] Further, it also includes a discharge voltage monitoring circuit for collecting the plasma voltage signal in the engine cylinder.

[0009] Further, the turns ratio range of the secondary coil to the primary coil is between 70:1 and 120:1.

[0010] Further, one end of the secondary coil is a plasma current detection end for detecting the ignition current.

[0011] Further, a unidirectional circuit one is also connected between the secondary coil and the spark plug gap.

[0012] Further, it further includes a discharge voltage monitoring circuit.

[0013] Further, the discharge voltage monitoring circuit includes a first voltage dividing element and a second voltage dividing element connected to the secondary coil.

[0014] Further, a filter circuit is also connected across the second voltage dividing element.

[0015] Further, the filter circuit includes a high-pass filter circuit and a low-pass filter circuit.

[0016] Further, the ignition energy control unit includes a plurality of auxiliary ignition coils arranged in parallel, and each auxiliary ignition coil is connected to the high-voltage input terminal of the secondary coil after being connected to a high-voltage diode.

[0017] Further, the ignition energy control unit includes a DC step-up transformer, an energy storage capacitor, and a field-effect diode. One side of the DC step-up transformer is connected to a power supply, the other side is connected to the energy storage capacitor, and is connected to the high-voltage input terminal of the secondary coil after passing through the field-effect diode.

[0018] Compared with the prior art, the technical solution of the present application has the following beneficial effects: The ignition coil of the internal combustion engine proposed by the present utility model has a high-voltage input terminal connected in parallel at the high-voltage output terminal of its secondary coil. After the secondary coil discharges to establish a breakdown voltage, the high-voltage input terminal can be used as a continuous ignition energy input terminal to provide continuous ignition energy to the spark plug gap and provide a continuous supply current, so that the continuous supply current can be controlled according to the control requirements within a very short time, significantly improving the ignition efficiency. The present utility model has a wide range of application scenarios, including high-speed vehicle engines, low-speed marine engines, fixed internal combustion engine power generation systems, and gas turbine systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : Schematic diagram of the exclusive ignition coil circuit structure;

[0020] Figure 2 : Schematic diagram of the discharge voltage monitoring circuit principle;

[0021] Figure 3 : Filter circuit principle Figure 1 ;

[0022] Figure 4 : Filter circuit principle Figure 2 ;

[0023] Figure 5 : Principle of the ignition energy control unit Figure 1 ;

[0024] Figure 6 : Principle of the ignition energy control unit Figure 2 .

[0025] Reference Signs:

[0026] 11. Primary coil; 12. Secondary coil; 13. Switching element; 14. High-voltage input terminal; 15. Plasma current detection terminal; 16. Unidirectional circuit one; 17. Unidirectional circuit two; 18. Discharge voltage monitoring circuit; 2. Ignition energy control unit; 21. Auxiliary ignition coil; 22. DC boost transformer; 23. Field-effect diode. Detailed Embodiment

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] The ignition coil provided by the present invention functions to establish a breakdown voltage, thereby establishing a plasma channel, so that the high-voltage input terminal 14 of the ignition coil can discharge to the spark gap; in addition, the ignition coil is also provided with a plasma channel voltage detection circuit and a combustion diagnosis circuit. The high-voltage input terminal 14 can be externally connected to an ignition energy supply unit, whose function is to provide a continuous supply current to the spark gap during the continuous discharge stage, and the amplitude and duration of this current can be much higher than the discharge capacity of the secondary coil 12 itself, so the ignition efficiency can be significantly improved.

[0029] The ignition coil includes a primary coil 11 and a secondary coil 12. The primary coil 11 is connected to a switching element 13 for receiving an ignition signal, and the secondary coil 12 has an output terminal coupled to the spark plug gap; the high-voltage output terminal of the ignition energy control unit 2 is coupled to the spark plug gap.

[0030] As Figure 1The hardware circuit structure of an exclusive ignition coil is shown. The ignition coil includes a primary coil 11 and a secondary coil 12. The primary coil 11 is connected to a switching element 13 for receiving an ignition signal, and the secondary coil 12 has a high-voltage input terminal 14 for providing a continuous ignition current. This ignition coil needs to have a high step-up ratio to generate a high breakdown voltage (40 - 60 kV) to produce a stable breakdown process under different engine operating conditions. Different from traditional ignition coils, in the present utility model, the ignition energy is mainly provided by the high-voltage input terminal 14 rather than the ignition coil itself. Therefore, the inductances of the primary and secondary coils 12 of this ignition coil can be much lower than those of traditional coils, thus enabling a fast charge and discharge process. The energy stored in the primary coil 11 of this ignition coil is mainly determined by the parasitic capacitance of the ignition system and the required breakdown voltage, and only the minimum energy required to reach the breakdown voltage is needed. In this way, the charging duration of this ignition coil can be as low as 20 - 100 microseconds. Such a fast charging process can form a breakdown process again within 1°CA of the engine, thus effectively curbing the negative impact on the combustion phase due to the slow after-fire process. The lower secondary inductance can also reduce the power loss during the discharge process, thereby reducing the power consumption of the ignition coil. In this embodiment, the turns ratio of the secondary coil 12 to the primary coil 11 ranges from 70:1 to 120:1.

[0031] In a more preferred embodiment, one end of the secondary coil 12 is a plasma current detection terminal 15 for detecting the continuous ignition current. A discharge voltage monitoring circuit 18 is connected between the secondary coil 12 and the primary coil 11. Its purpose is to detect the impedance of the spark plasma. Both the discharge voltage and the discharge current can be used to diagnose the plasma impedance.

[0032] In a more preferred embodiment, a one-way circuit 16 is connected to the plasma current detection terminal 15 of the secondary coil 12. The one-way circuit 16 can be a high-voltage diode D1 connected to the plasma current detection terminal 15, which is used to prevent the high voltage generated during the charging process of the ignition coil from being transmitted along the high-voltage wire to the plasma current detection terminal 15, and at the same time, it can also prevent mis-breakdown from occurring in the spark gap during the charging process.

[0033] In a more preferred embodiment, a one-way circuit 17 is connected to the high-voltage input terminal 14 of the secondary coil 12. The one-way circuit 17 can be a high-voltage diode D3 connected in series with the high-voltage input terminal 14, with the same direction as the high-voltage diode D1, which is used to prevent the high voltage generated by this ignition coil from propagating in the reverse direction along the high-voltage connection wire, thereby isolating the interference between the engine cylinders 4 during the ignition process.

[0034] In a more preferred embodiment, the ignition coil includes a discharge voltage monitoring circuit 18 for collecting the plasma voltage signal in the engine cylinder and providing it to an external control unit.

[0035] The discharge voltage monitoring circuit 18 includes a first voltage dividing element and a second voltage dividing element connected to the secondary coil 12, and a discharge voltage monitoring terminal is connected between the first voltage dividing element and the second voltage dividing element. Figure 6 A circuit diagram of such an ignition coil for measuring the discharge voltage is shown. The ignition coil includes a primary coil 11 and a secondary coil 12. One end of the primary coil 11 is connected to a power source, and the other end is connected in series with a transistor. The transistor serves as a switching element 13 to control the charging and discharging process of the ignition coil. One end (output end) of the secondary coil 12 is directly connected to the spark plug 5 to transmit the high voltage generated by the secondary to the spark gap, thereby causing a breakdown phenomenon. A first high-voltage diode D1 is connected in series between the output end of the secondary coil 12 and the spark plug 5. The other pole of the secondary coil 12 is left floating for use in detecting the ion current. In the secondary circuit, a first resistor R1 and a second resistor R2 are provided, and the first resistor R1 and the second resistor R2 are connected in series. The other end of the first resistor R1 is connected to the secondary output circuit, arranged downstream of the first high-voltage diode D1 and upstream of the spark gap. The other end of the second resistor R2 is grounded. The detection point of the plasma voltage is at the first resistor R1 and the second resistor R2, and the ratio of the resistance values of the first resistor R1 and the second resistor R2 determines the ratio of the detected voltage to the actual secondary output voltage. For example, if the resistance value of the first resistor R1 is 1000 times that of the second resistor R2, then the measured plasma voltage signal is one-thousandth of the actual plasma voltage. A noise reduction circuit including a pair of oppositely connected Zener diodes and a capacitor is also arranged between the detection terminal and the ground wire to reduce the detection noise. By detecting the plasma voltage in real time, possible plasma blowout and re-breakdown phenomena can be predicted.

[0036] As Figure 2 Another embodiment of the discharge voltage monitoring circuit 18 is shown. For the discharge voltage detection circuit based on capacitive voltage division, capacitors C1 and C2 connected in series are provided in the circuit. The connection manner of the components in the circuit is similar to that of the circuit based on resistive voltage division. One end of the capacitor C1 is connected to the secondary output, and one end of the capacitor C2 is connected to the ground. The detection point of the plasma voltage is set between C1 and C2, so the ratio of the capacitance values of C1 and C2 determines the attenuation multiple of the detected voltage relative to the actual secondary discharge voltage. To ensure the instantaneous response speed of the detected voltage, the capacitance values of the capacitors C1 and C2 cannot be too large. For example, to ensure that the response time of the detected voltage is in the order of microseconds, the capacitance values of the capacitors C1 and C2 need to be set below the microfarad order.

[0037] In a more preferred embodiment, a filter circuit is also connected across the second voltage dividing element. Specifically, it can be adopted such as Figure 3 and Figure 4As shown. By connecting a resistor Rs in series and a capacitor Cs in parallel with the detection terminal in the detection circuit, low-pass filtering can be achieved. Low-pass filtering can eliminate the high-frequency components in the actual secondary voltage, including high-frequency electrical noise and instantaneous discharge voltage, which is more conducive to the ignition diagnosis in the arc discharge stage. By detecting the plasma voltage in real time, possible plasma blowout and re-breakdown phenomena can be predicted. By connecting a capacitor Cs in series and a resistor Rs in parallel with the detection terminal, high-pass filtering can be achieved. High-pass filtering will retain high-frequency signals and instantaneous discharge voltage, which is beneficial to the analysis and diagnosis of the breakdown stage. The cut-off frequencies of low-pass filtering and high-pass filtering are related to the resistor Rs and the capacitor Cs.

[0038] In a more preferred embodiment, the turn ratio of the secondary coil 12 to the primary coil 11 ranges from 70:1 to 120:1.

[0039] In a more preferred embodiment, as Figure 5 shown, a hardware circuit structure of an ignition energy control unit is presented. The ignition energy control module can be integrated and packaged with the ignition coil as a whole, and its output terminal is connected to the high-voltage input terminal 14 of the secondary coil 12 of the ignition coil as the supply terminal of the high-voltage continuous ignition current for continuous ignition. The ignition energy control unit 2 includes a plurality of auxiliary ignition coils 21 arranged in parallel. Each auxiliary ignition coil 21 is connected to a high-voltage diode and then connected to the high-voltage output terminal. The ignition energy control unit 2 is used to provide ignition energy to the spark gap. This module can flexibly adjust the ignition current intensity and ignition duration to quickly control the plasma impedance, thereby strengthening the ignition ability while avoiding the plasma channel being blown out or re-breakdown occurring during the spark discharge process. A high-voltage diode is arranged downstream of the secondary output terminal of each auxiliary ignition coil 21 to isolate the discharge processes between the auxiliary ignition coils 21. The turn ratio of the auxiliary ignition coil 21 ranges from 25:1 to 40:1, so that the discharge current in the stable discharge stage can be increased to 2 to 3 times that of the dedicated coil to enhance the ignition effect. However, such a design significantly reduces the achievable discharge voltage and cannot complete the breakdown process independently. Therefore, it is necessary to rely on the dedicated ignition coil 1 to first establish the ignition channel and then release high current to the channel. During the discharge process, the transient discharge current can be increased or decreased within microseconds by changing the duty cycle and operating frequency of the charge and discharge signals of the auxiliary coil group, thereby achieving rapid control of the plasma impedance.

[0040] Another embodiment of the ignition energy control unit can be as Figure 6As shown. The ignition energy control unit 2 includes a DC boost transformer 22 and a field effect diode 23. One side of the DC boost transformer 22 is connected to a power supply, and the other side is connected to the field effect diode 23 and then connected to a high-voltage output terminal and finally connected to the high-voltage input terminal 14 of the secondary coil 12 of the dedicated ignition coil 1. The ignition energy is stored in a capacitor at a higher voltage after passing through the high-frequency DC boost transformer 22, and the release of the current is controlled by the field effect diode 23. The intensity of the discharge current can be controlled by adjusting the voltage, and the field effect diode 23 can control the moment and duration of the discharge current.

[0041] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0042] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An internal combustion engine ignition coil, comprising a primary coil and a secondary coil, wherein the primary coil is connected to a switch element for receiving an ignition signal, and the secondary coil has an output end coupled to a spark plug gap, characterized in that: A high voltage input terminal is also connected in parallel between the spark plug gap and the secondary coil.

2. The internal combustion engine ignition coil according to claim 1, characterized in that: A unidirectional circuit 2 is connected between the high voltage input terminal and the output terminal of the secondary coil.

3. The internal combustion engine ignition coil according to claim 2, characterized in that: It also includes a discharge voltage monitoring circuit for collecting plasma voltage signals in the engine cylinder.

4. The internal combustion engine ignition coil according to claim 3, characterized in that: One end of the secondary coil is a plasma current detection end, which is used to detect the ignition current.

5. The internal combustion engine ignition coil according to claim 4, characterized in that: A one-way circuit 1 is also connected between the secondary coil and the spark plug gap.

6. The internal combustion engine ignition coil according to claim 5, characterized in that: It also includes a discharge voltage monitoring circuit, which includes a first voltage dividing element and a second voltage dividing element connected to the secondary coil.

7. The internal combustion engine ignition coil according to any one of claims 1 to 6, characterized in that: The high voltage input end of the ignition coil is connected to the ignition energy control unit.

8. The internal combustion engine ignition coil according to claim 7, characterized in that: The ignition energy control unit comprises a plurality of auxiliary ignition coils arranged in parallel, each of which is connected to a high-voltage diode and then to a high-voltage input end of a secondary coil.

9. The internal combustion engine ignition coil according to claim 8, characterized in that: The turns ratio of the auxiliary ignition coil ranges from 25:1 to 40:

1.

10. The internal combustion engine ignition coil according to claim 7, characterized in that: The ignition energy control unit includes a DC boost transformer, an energy storage capacitor and a field effect diode. One side of the DC boost transformer is connected to the power supply, and the other side is connected to the energy storage capacitor and connected to the high voltage input end of the secondary coil through the field effect diode.

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