Ignition coil

Abstract

A first outer peripheral iron core (36o) of a first coil group (10) and a second outer peripheral iron core (50o) of a second coil group (20) of an ignition coil (2) of one embodiment have a common portion (58). A direction of a magnetic flux generated in the common portion (58) when a current flows through a first primary coil (32) of the first coil group (10) is opposite to a direction of a magnetic flux generated in the common portion (58) when a current flows through a second primary coil (46) of the second coil group (20). The direction of the induced current generated in the first secondary coil (34) at the output port (28) is the same as the direction of the induced current generated in the second secondary coil (48) at the output port (28).

Description

[0001] This application claims priority to and the benefit of patent application No. 2024-45931 filed in JAPAN on March 22, 2024. The entire disclosure of these Japanese patent applications is incorporated herein by reference. Technical Field

[0002] This specification discloses an ignition coil. Background Art

[0003] Internal combustion engines use ignition coils to activate the spark plugs installed in the combustion chamber. Typically, an ignition coil consists of an iron core, a primary coil, a secondary coil, and a switch that switches the current flowing through the primary coil on and off. By shutting off the current flowing through the primary coil, a high induced electromotive force is generated in the secondary coil. This high voltage is applied to the spark plug, generating a spark discharge and igniting the fuel.

[0004] In recent years, internal combustion engines that use lean fuel and flame-retardant fuels such as ammonia have become available. These engines require greater energy to ignite and maintain combustion than ever before. To meet this demand, ignition coils comprising two sets of "iron core, primary coil, and secondary coil" (referred to as coil assemblies) have been developed and put into practical use. For example, the ignition coil disclosed in Japanese Patent Application Laid-Open No. 2015-129464 prolongs the duration of discharge by alternating the operation of the two coil sets.

[0005] In internal combustion engines, such as engines, each cylinder is equipped with an ignition coil. Furthermore, in multi-point ignition engines, multiple ignition coils are used in each cylinder. Because ignition coils with two coil assemblies occupy a large space, they can become a major obstacle to miniaturization of internal combustion engines. There is a need for an ignition coil that achieves excellent ignition performance while minimizing size.

[0006] The present inventors intend to provide an ignition coil that achieves excellent ignition performance while suppressing an increase in size. Summary of the Invention

[0007] An ignition coil according to one embodiment includes: a first coil assembly having a first primary coil and a first secondary coil, a first central core extending through the first primary coil and the first secondary coil, and a first outer core surrounding the first primary coil and the first secondary coil; a second coil assembly having a second primary coil and a second secondary coil, a second central core extending through the second primary coil and the second secondary coil, and a second outer core surrounding the second primary coil and the second secondary coil; and an output port connected to the first and second secondary coils. The first and second outer cores have a common portion. When current flows in a first direction through the first primary coil, the direction of magnetic flux generated in the common portion is opposite to the direction of magnetic flux generated in the common portion when current flows in a second direction through the second primary coil. When current flowing in the first direction through the first primary coil is interrupted, the direction of the induced current at the output port is the same as the direction of the induced current generated in the second secondary coil when current flowing in the second direction through the second primary coil is interrupted.

[0008] In this ignition coil, the directions of the induced currents at the output ports of the first and second coil groups are the same, while the directions of the magnetic fluxes in the common portion of the first and second peripheral iron cores are opposite. Since the directions of the induced currents output by the first and second coil groups are the same, the sum of these induced currents can be provided to the spark plug. This contributes to excellent ignition performance. Since the directions of the magnetic fluxes in the common portion of the first and second coil groups are opposite, the magnetic fluxes of the first and second coil groups cancel each other out in the common portion. As a result, magnetic saturation of the common portion is prevented, and the cross-sectional area of ​​the common portion can be reduced. This suppresses the increase in the volume of the ignition coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a circuit diagram of an ignition system including an ignition coil according to one embodiment.

[0010] Figure 2 Yes Figure 1 A cross-sectional view of the two coil groups of the ignition coil.

[0011] Figure 3 Yes Figure 2 A three-dimensional diagram of the iron core and magnets of the two sets of coil assemblies.

[0012] Figure 4 yes Figure 2 Magnetic circuit diagram of two sets of coil groups.

[0013] Figure 5 yes Figure 1 An example of a timing diagram in the simultaneous ignition coil energization mode, where (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the current of the first primary coil, (d) represents the current of the second primary coil, and (e) represents the output current of the ignition coil.

[0014] Figure 6 yes Figure 5 An example of a timing diagram in the mode, (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the magnetic flux of the first central iron core, (d) represents the magnetic flux of the second central iron core, and (e) represents the magnetic flux of the common part.

[0015] Figure 7 yes Figure 1 An example of a timing diagram in the alternating energization mode of the ignition coil, (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the current of the first primary coil, (d) represents the current of the second primary coil, and (e) represents the output current of the ignition coil.

[0016] Figure 8 yes Figure 7 An example of a timing diagram in the mode, (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the magnetic flux of the first central iron core, (d) represents the magnetic flux of the second central iron core, and (e) represents the magnetic flux of the common part.

[0017] Figure 9 yes Figure 1 An example of a timing diagram of the ignition coil in the composite energization mode, where (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the current of the first primary coil, (d) represents the current of the second primary coil, and (e) represents the output current of the ignition coil.

[0018] Figure 10 yes Figure 9 An example of a timing diagram in the mode, (a) represents the input signal to the first coil group, (b) represents the input signal to the second coil group, (c) represents the magnetic flux of the first central iron core, (d) represents the magnetic flux of the second central iron core, and (e) represents the magnetic flux of the common part. DETAILED DESCRIPTION

[0019] Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings as appropriate.

[0020] Figure 1This is a circuit diagram of an ignition system 4 including an ignition coil 2 according to one embodiment. In addition to the ignition coil 2, the ignition system 4 includes a controller 6 and a spark plug 8. The spark plug 8 is located in the combustion chamber of a combustion device such as an engine. In the case of an automotive ignition system 4, the controller 6 is implemented by an ECU, for example.

[0021] The ignition coil 2 includes a first coil group 10 , a first switch 12 , a first diode 14 , a first control port 16 , a second coil group 20 , a second switch 22 , a second diode 24 , a second control port 26 , an output port 28 , a power port 18 , and a ground port 30 . Figure 2 1 is a cross-sectional view showing the first coil group 10 and the second coil group 20 among these. Figure 3 It is a perspective view showing only the cores of the first coil group 10 and the second coil group 20 .

[0022] like Figure 1 As shown, the first coil group 10 includes a first primary coil 32, a first secondary coil 34 and a first core 36. Figure 2 and Figure 3 As shown, the first coil assembly 10 further includes a first magnet 38, and the first core 36 includes a first central core 36c and a first peripheral core 36o. The first primary coil 32 is formed by winding a conductive wire around the periphery of the first central core 36c. The first secondary coil 34 is formed by winding a conductive wire around the periphery of the first central core 36c. These conductive wires are typically made of copper (Cu). In this embodiment, the first secondary coil 34 is formed outside the first primary coil 32. The number of turns of conductive wire in the first secondary coil 34 is much greater than the number of turns of conductive wire in the first primary coil 32.

[0023] The first central core 36c is columnar. In this embodiment, the first central core 36c is a quadrangular prism. The first central core 36c passes through the center of the first primary coil 32 and the first secondary coil 34. The first peripheral core 36o extends from one end of the first central core 36c around the outside of the first primary coil 32 and the first secondary coil 34 and to the other end of the first central core 36c. The first peripheral core 36o includes a lower column 40 at one end of the first central core 36c facing its bottom surface, an upper column 42 at the other end of the first central core 36c contacting its side surface, and a beam 44 located between the lower column 40 and the upper column 42. The beam 44 extends parallel to the first central core 36c. The first magnet 38 is located adjacent to one end of the first central core 36c. The first magnet 38 is located between the bottom surface of the first central core 36c and the lower column 40 at one end of the first peripheral core 36o. The first central core 36c and the first peripheral core 36o are made of magnetic material. Preferred magnetic materials include ferrite, dust, and silicon steel.

[0024] In this embodiment, the second coil group 20 has the same structure as the first coil group 10. That is, the second coil group 20 includes a second primary coil 46, a second secondary coil 48, and a second core 50. The second coil group 20 also includes a second magnet 52, and the second core 50 includes a second central core 50c and a second peripheral core 50o. The second primary coil 46 is formed by winding a conductive wire around the outer periphery of the second central core 50c. The second secondary coil 48 is formed by winding a conductive wire around the outer periphery of the second central core 50c. These conductive wires are typically made of copper. In this embodiment, the second secondary coil 48 is formed outside the second primary coil 46. The number of turns of conductive wire in the second secondary coil 48 is much greater than the number of turns of conductive wire in the second primary coil 46.

[0025] The second central core 50c is columnar. In this embodiment, the second central core 50c is a quadrangular prism. The second central core 50c passes through the center of the second primary coil 46 and the second secondary coil 48. The second peripheral core 50o extends from one end of the second central core 50c around the outside of the second primary coil 46 and the second secondary coil 48 to the other end of the second central core 50c. The second peripheral core 50o includes a lower column 53 at one end of the second central core 50c facing its bottom surface, an upper column 54 at the other end of the second central core 50c contacting its side surface, and a beam 56 located between the lower column 53 and the upper column 54. The beam 56 extends parallel to the second central core 50c. The second magnet 52 is located adjacent to one end of the second central core 50c. The second magnet 52 is located between the bottom surface of the second central core 50c and the lower column 53 at one end of the second central core 50c. The second central core 50c and the second peripheral core 50o are made of a magnetic material. Preferred magnetic materials include ferrite, dust, and silicon steel.

[0026] like Figure 2 and Figure 3As shown, the first outer core 36o and the second outer core 50o have a common portion 58. In this embodiment, the beam portion 44 of the first outer core 36o and the beam portion 56 of the second outer core 50o constitute the common portion 58. In this embodiment, the width of the common portion 58 is narrower than the width of the other portions of the first core 36 and the second core 50. In other words, the cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the portions other than the common portion 58 between the first central core 36c and the first outer core 36o. In other words, the cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the portions other than the common portion 58 between the second central core 50c and the second outer core 50o. Here, each cross-sectional area is measured in a cross section perpendicular to the direction of the magnetic flux generated within the first core 36 and the second core 50, which will be described later. When the cross-sectional area of ​​the parts other than the common part 58 of the first central iron core 36c and the first peripheral iron core 36o, and the parts other than the common part 58 of the second central iron core 50c and the second peripheral iron core 50o, and the common part 58 are not fixed due to different positions, their respective cross-sectional areas are measured at the position where the cross-sectional area is the smallest.

[0027] The first switch 12 is located between the first primary coil 32 and the ground terminal 30. The first control terminal 16 is connected to the first switch 12. The first switch 12 switches between electrical conduction (on) and electrical conduction (off) between the first primary coil 32 and the ground terminal 30 based on a signal from the first control terminal 16. In this embodiment, the first switch 12 is an IGBT (insulated gate bipolar transistor). The first switch 12 can be implemented by other devices. For example, the first switch 12 can be implemented by a MOSFET.

[0028] The second switch 22 is located between the second primary coil 46 and the ground terminal 30. The second control terminal 26 is connected to the second switch 22. The second switch 22 switches between the second primary coil 46 and the ground terminal 30 in accordance with a signal from the second control terminal 26. In this embodiment, the second switch 22 is an IGBT. The second switch 22 can be implemented by other devices. For example, the second switch 22 can be implemented by a MOSFET.

[0029] The first diode 14 is located between the first primary winding 34 and the output port 28. The first diode 14 restricts the direction of current flow in the first primary winding 34. The second diode 24 is located between the second secondary winding 48 and the output port 28. The second diode 24 restricts the direction of current flow in the second secondary winding 48.

[0030] The power port 18 is connected to the first primary coil 32 and the second primary coil 46. When the first switch 12 is in the on state, current flows from the power port 18 to the first primary coil 32. When the second switch 22 is in the on state, current flows from the power port 18 to the second primary coil 46. Figure 2 Arrow φ cA The arrow φ represents the magnetic flux generated by the current flowing through the first primary coil 32. cB represents the magnetic flux generated by the current flowing through the second primary coil 46. Figure 2 As shown, in the common portion 58, the magnetic flux φ cA The direction of the magnetic flux φ cB In other words, the winding directions of the wires of the first primary coil 32 and the second primary coil 46 are determined so that when current flows from the power supply port 18 to the first primary coil 32 and the second primary coil 46, the magnetic flux φ in the common portion 58 is cA The direction of the magnetic flux φ cB in the opposite direction.

[0031] exist Figure 1 In the embodiment, one power port 18 is connected to the first primary coil 32 and the second primary coil 46. A power port 18 connected to the first primary coil 32 and a power port 18 connected to the second primary coil 46 may also exist separately. A ground port 30 connected to the first switch 12 and a ground port 30 connected to the second switch 22 may also exist separately.

[0032] Figure 2 Arrow φ mA Represents the magnetic flux of the first magnet 38. Figure 2 As shown, the magnetic flux φ mA The direction of the magnetic flux φ cA On the contrary. Arrow φ mB represents the magnetic flux of the second magnet 52. Magnetic flux φ mB The direction of the magnetic flux φ cB On the contrary. In other words, using the magnetic flux φ mA The direction of the magnetic flux φ cA The direction of the magnetic flux is opposite to mB The direction of the magnetic flux φ cB The first magnet 38 and the second magnet 52 are in opposite directions.

[0033] Output port 28 is connected to first primary coil 34 and second secondary coil 48. When the current flowing through first primary coil 32 is cut off, an induced electromotive force is generated in first secondary coil 34. The induced current flows from first secondary coil 34 to spark plug 8 via output port 28. Similarly, when the current flowing through second primary coil 46 is cut off, the induced current flows from second secondary coil 48 to spark plug 8 via output port 28. At output port 28, the direction of the induced current in first secondary coil 34 is the same as the direction of the induced current in second secondary coil 48. In other words, the winding direction of the wires of first secondary coil 34 and second secondary coil 48 is determined so that the direction of the induced current in first secondary coil 34 generated when the current in first primary coil 32 is cut off is the same as the direction of the induced current in second secondary coil 48 generated when the current in second primary coil 46 is cut off.

[0034] Figure 4 : is a magnetic circuit diagram of the first coil group 10 and the second coil group 20. In the figure, the symbol FA represents the magnetomotive force of the first coil group 10 generated by the first primary coil 32, the first secondary coil 34 and the first magnet 38. The reference symbol FB represents the magnetomotive force of the second coil group 20 by the second primary coil 46, the second secondary coil 48 and the second magnet 52. The symbol RAB represents the magnetic resistance of each of the first coil group 10 and the second coil group 20, excluding the common portion 58. In this embodiment, the magnetic resistance is the same in the first coil group 10 and the second coil group 20. The symbol φ A is the magnetic flux passing through the first coil group 10 outside the common portion 58, φ A =φ cA -φ mA The symbol φ B is the magnetic flux passing through the second coil group 20 outside the common portion 58, φ B =φ cB -φ mB Symbol RS represents the magnetic resistance of the common portion 58 .

[0035] exist Figure 4 In the symbol φ S is the magnetic flux passing through the common portion 58 and is expressed by the following equation. φ S =φ A -φ B =(F A -F B ) / (R AB +2R S ) If the structures of the first coil group 10 and the second coil group 20 are made the same and the currents flowing through the first coil group 10 and the second coil group 20 are made the same, then F A =FB In this case, it can be understood that the magnetic flux φ S Becomes zero.

[0036] The controller 6 controls the action of the ignition coil 2. Figure 1 As shown, the controller 6 has a first control signal CNT1 connected to the first control port 16, and a second control signal CNT2 connected to the second control port 26. The controller 6 switches the first switch 12 on and off based on the signal CNT1, and switches the second switch 22 on and off based on the signal CNT2. In this embodiment, the power supply terminal VDD of the controller 6 is connected to the power supply port 18 of the ignition coil 2. Current is supplied from the controller 6 to the first coil assembly 10 and the second coil assembly 20.

[0037] In this embodiment, the controller 6 can operate the ignition coil 2 in the following modes. (1) Simultaneous power-on mode The first coil group 10 and the second coil group 20 are energized simultaneously. (2) Alternating power mode The first coil group 10 and the second coil group 20 are energized alternately. (3) Composite power-on mode A mode that combines the simultaneous power-on mode and the alternating power-on mode. These modes are described below.

[0038] [Simultaneous power mode] Figure 5 is a timing diagram showing the simultaneous power-on mode. Figure 5 In all of (a) to (e), the horizontal axis represents time (t). Figure 5 (a) represents the first control signal CNT1 input to the first switch 12, Figure 5 (b) shows the second control signal CNT2 input to the second switch 22. In these figures, "on" indicates that the first control signal CNT1 and the second control signal CNT2 are at values ​​that respectively turn on the first switch 12 and the second switch 22. "off" indicates that the first control signal CNT1 and the second control signal CNT2 are at values ​​that respectively turn off the first switch 12 and the second switch 22.

[0039] Figure 5 (c) represents the current I of the first primary coil 32 1-A By turning the first control signal CNT1 on, the first switch 12 is turned on, and the current I 1-A Afterwards, by turning the first control signal CNT1 to “off”, the first switch 12 is turned off, and the current I 1-A was cut off. Figure 5(d) represents the current I of the second primary coil 46 1-B By turning the second control signal CNT2 on, the second switch 22 is turned on, and the current I 1-B Then, by turning the second control signal CNT2 to “off”, the second switch 22 is turned off, and the current I 1-B is cut off. Current I 1-A and current I 1-B They start flowing at the same time and are cut off at the same time.

[0040] Figure 5 (e) represents the output current I of the ignition coil 2 2-∑ .exist Figure 5 The dotted box in (e) indicates the current I 1-A The current I of the first secondary coil 34 generated when the 2-A and the current I 1-B The current I of the second secondary coil 48 generated when the 2-B Current I 2-A and current I 2-B Generated at the same time, they are in the same direction at the output port 28, so the output current I 2-∑ Becomes current I 2-A and current I 2-B The sum (I 2-∑ =I 2-A +I 2-B ).

[0041] Figure 6 Yes Figure 5 The timing diagram of magnetic flux in the operation mode shown is shown. Figure 6 (a) and (b) represent the first control signal CNT1 and the second control signal CNT2, respectively. Figure 5 (a) and (b) are the same. Figure 6 (c) represents the magnetic flux φ A , Figure 6 (d) represents the magnetic flux φ B In these figures, the direction of the magnetic flux is represented by positive and negative signs. The magnetic flux φ generated by the current flowing through the first primary coil 32 cA The direction of is positive. Figure 8 and Figure 10 The same is true in . Figure 6 In (c) and (d), max AB and (-max AB ) represents the threshold value of magnetic flux at which the core reaches magnetic saturation in the portion other than the common portion 58 (referred to as the maximum magnetic flux in this specification). In this embodiment, the maximum magnetic flux in the portion other than the common portion 58 is the same in the first coil group 10 and the second coil group 20.

[0042] like Figure 6 As shown in (c), before the first control signal CNT1 is turned on, the magnetic flux φ A (-max AB ). This is the magnetic flux generated by the first magnet 38. In this embodiment, the magnetic flux φ is used. mA The magnitude (absolute value) and the maximum magnetic flux max AB When the first control signal CNT1 is “ON”, the current I 1-A flow, magnetic flux φ A In this embodiment, due to the current I 1-A , magnetic flux φ A Rise to the maximum magnetic flux max AB When the first control signal CNT1 is “off”, the current I 1-A is cut off, the current I 2-A flow, so the magnetic flux φ A decline. Figure 6 (d) shows the magnetic flux φ B Also with the magnetic flux φ A The same principle is used to change. B The direction of the magnetic flux φ A On the contrary, the magnetic flux φ B The curve of magnetic flux φ A The polarity of the curve is reversed. In this embodiment, the magnetic flux φ is used mB The size and maximum magnetic flux max AB An identical second magnet 52 .

[0043] Figure 6 (e) represents the magnetic flux φ S .exist Figure 6 In (e), the magnetic flux φ A and magnetic flux φ B Also indicated by dotted lines. A and magnetic flux φ B The polarity is opposite, so the magnetic flux φ S Almost zero. Figure 6 In (e), max S It represents the maximum magnetic flux in the common part 58. Since the cross-sectional area of ​​the common part 58 is smaller than the cross-sectional area of ​​other parts, the maximum magnetic flux max S Ratio to maximum magnetic flux max AB It can be understood that even if the cross-sectional area of ​​the common portion 58 is smaller than that of other portions, the magnetic flux φ S Nor does it exceed the maximum magnetic flux max S .

[0044] [Alternate power mode] Figure 7 This is a timing diagram showing the alternating energization mode. Figure 7 (a) represents the first control signal CNT1, Figure 7 (b) shows the second control signal CNT2. The controller 6 outputs trigger signals that alternately switch the first control signal CNT1 on and off, and the second control signal CNT2 on and off, one or more times. In this embodiment, when the first control signal CNT1 is on, the second control signal CNT2 is off, and when the second control signal CNT2 is on, the first control signal CNT1 is off. The periods during which the first control signal CNT1 is on and the second control signal CNT2 is on may partially overlap.

[0045] Figure 7 (c) represents the current I of the first primary coil 32 1-A When the first control signal CNT1 is “on”, the current I 1-A When the first control signal CNT1 is “off”, the current I 1-A In this embodiment, the current I 1-A Flow through 3 times. Figure 7 As shown in (c), in this embodiment, the current I 1-A The magnitude of the peak value is such that the later the current flows, the greater the peak value. Figure 7 (d) represents the current I of the second primary coil 46 1-B When the second control signal CNT2 is “on”, the current I 1-B When the second control signal CNT2 is “off”, the current I 1-B In this embodiment, the current I 1-B The peak value of the current I is greater the later the current flows. 1-A and current I 1-B Alternate flow, alternate cutoff.

[0046] Figure 7 (e) represents the output current I of the ignition coil 2 2-∑ .exist Figure 7 The dotted box in (e) indicates the current I 1-A The current I of the first secondary coil 34 generated when the 2-A and the current I 1-B The current I of the second secondary coil 48 generated when the 2-B Current I 2-A At the current I 1-A When it is cut off, the current I 2-B At the current I 1-Bis cut off, so the current I 2-A and current I 2-B In this embodiment, the current I 2-A and current I 2-Bg The magnitude of each peak value is such that the later the current flows, the larger the peak value. Output current I 2-∑ Becomes current I 2-A and current I 2-B It can be seen that the current I 2-∑ From the initial current I 2-A Start to flow to the last I 2-B The flow continues until the flow is stopped.

[0047] Figure 8 Yes Figure 7 The timing diagram of magnetic flux during operation is shown. Figure 8 (a) and (b) represent the first control signal CNT1 and the second control signal CNT2, respectively. Figure 7 (a) and (b) are the same. Figure 8 (c) represents the magnetic flux φ A , Figure 8 (d) represents the magnetic flux φ B .

[0048] like Figure 8 As shown in (c), when the first control signal CNT1 is “on”, the magnetic flux φ A When the first control signal CNT1 is “off”, the magnetic flux φ A Fall. In this embodiment, this rise and fall is repeated three times. The rate of change of the magnetic flux (the absolute value of the slope of the magnetic flux curve) when the first control signal CNT1 is "on" is greater than the rate of change of the magnetic flux when the first control signal CNT1 is "off". The peak value of the magnetic flux during the period when the first control signal CNT1 is "on" becomes larger as the "on" period progresses. This is why Figure 7 In (c), the current I 1-A The magnitude of the peak value is because the later the current flows, the larger the peak value.

[0049] like Figure 8 As shown in (d), the magnetic flux φ B Also with the magnetic flux φ A The same principle changes, but the direction of the magnetic flux is different from the magnetic flux φ A On the contrary, the magnetic flux φ B The polarity of the curve and the magnetic flux φ AThe polarity of the curve is opposite. In this embodiment, the decrease and increase of magnetic flux φB are repeated three times. The rate of change of the magnetic flux when the second control signal CNT2 is "on" is greater than the rate of change of the magnetic flux when the second control signal CNT2 is "off." The peak value (downward peak value) of the magnetic flux during the "on" period of the second control signal CNT2 increases as the "on" period progresses.

[0050] The rate of change of the magnetic flux when the first control signal CNT1 and the second control signal CNT2 are "on" is made greater than the rate of change of the magnetic flux when they are "off", for example, by the controller 6 controlling the voltage of the power supply terminal VDD to be sufficiently large relative to the load of the spark plug 8.

[0051] Figure 8 (e) represents the magnetic flux φ S .exist Figure 8 In (e), the magnetic flux φ A and magnetic flux φ B Also indicated by dotted lines. A and magnetic flux φ B The polarities are opposite and cancel each other out, so the magnetic flux φ S The peak value (absolute value) is greater than the magnetic flux φ A The peak value and magnetic flux φ B The peak value of is smaller. In this embodiment, the magnetic flux φ S Not exceeding the maximum magnetic flux max S In other words, the controller 6 controls the current I 1-A and current I 1-B The size of the current I 1-A and current I 1-B The energizing time and disconnecting time and the number of repetitions of energizing and disconnecting make the magnetic flux φ S Not exceeding the maximum magnetic flux max S .

[0052] [Compound Power-On Mode] Figure 9 This is a timing diagram showing the composite energization mode. Figure 9 (a) represents the first control signal CNT1, Figure 9 (b) shows the second control signal CNT2. Similar to the simultaneous energizing mode, the controller 6 simultaneously turns the first control signal CNT1 and the second control signal CNT2 "on," and then simultaneously turns them "off." Then, similar to the alternating energizing mode, the controller 6 outputs trigger signals that alternately repeat the "on" and "off" cycles of the first control signal CNT1 and the "on" and "off" cycles of the second control signal CNT2 one or more times.

[0053] Figure 9 (c) represents the current I 1-A, Figure 9 (d) represents the current I 1-B First, the current I 1-A and current I 1-B At the same time, the current I 1-A and current I 1-B Start to flow alternately and be cut off alternately. 1-A and current I 1-B When the current flows alternately, I 1-A The peak value and current I 1-B The magnitude of the peak value is such that the later the current flows, the larger the peak value is.

[0054] Figure 9 (e) represents the output current I of the ignition coil 2 2-∑ .exist Figure 9 The dashed box in (e) represents the current I 2-A and current I 2-B Current I 2-A and current I 2-B First they flow simultaneously, then they flow alternately. In this embodiment, the current I 2-A and current I 2-B The peak value of the current flowing later is larger. Output current I 2-∑ Becomes current I 2-A and current I 2-B The sum of current I 2-∑ At the current I 2-A and current I 2-B When flowing simultaneously, it becomes a large value, and then flows continuously until the last I 2-B The flow ends.

[0055] Figure 10 Yes Figure 9 The timing diagram of magnetic flux during operation is shown. Figure 10 (a) and (b) represent the first control signal CNT1 and the second control signal CNT2, respectively. Figure 9 (a) and (b) are the same. Figure 10 (c) represents the magnetic flux φ A , Figure 10 (d) represents the magnetic flux φ B .

[0056] like Figure 10 As shown in (c), the magnetic flux φ A During the initial ON period of the first control signal CNT1, the AB ) rises to max AB , and then decreases during the subsequent “off” period. Then, during the period when the first control signal CNT1 is triggered, the magnetic flux φ AThe rate of change of the magnetic flux when the first control signal CNT1 is "on" is greater than the rate of change of the magnetic flux when the first control signal CNT1 is "off".

[0057] like Figure 10 As shown in (d), the magnetic flux φ B Also with the magnetic flux φ A The same principle changes, but the direction of the magnetic flux is different from the magnetic flux φ A On the contrary, the magnetic flux φ B The polarity of the curve and the magnetic flux φ A The polarity of the curve is opposite. That is, the magnetic flux φ B During the initial ON period of the second control signal CNT2, the maximum AB Down to (-max AB ), and then rises during the subsequent “off” period. Then, during the period when the second control signal CNT2 is triggered, the magnetic flux φ B The rate of change of the magnetic flux when the second control signal CNT2 is "on" is greater than the rate of change of the magnetic flux when the second control signal CNT2 is "off".

[0058] Figure 10 (e) represents the magnetic flux φ S .exist Figure 10 In (e), the magnetic flux φ A and magnetic flux φ B Also indicated by dotted lines. A and magnetic flux φ B The polarities are opposite and cancel each other out, so the magnetic flux φ S The peak value (absolute value) is greater than the magnetic flux φ A The peak value and magnetic flux φ B The peak value of is smaller. In this embodiment, the magnetic flux φ S Not exceeding the maximum magnetic flux max S In other words, the controller 6 controls the current I 1-A and current I 1-B The size of the current I 1-A and current I 1-B The energizing time and disconnecting time and the number of repetitions of energizing and disconnecting make the magnetic flux φ S Not exceeding the maximum magnetic flux max S .

[0059] The following describes the effects of this embodiment.

[0060] In this ignition coil 2, the induced currents at output port 28 of first and second coil assemblies 10 and 20 are directed in the same direction, while the magnetic fluxes at common portion 58 of first and second outer cores 36o and 50o are directed in opposite directions. Because the induced currents output by first and second coil assemblies 10 and 20 are directed in the same direction, the sum of these induced currents can be supplied as output current to spark plug 8. This allows for high ignition energy to be provided to spark plug 8, contributing to excellent ignition and combustion maintenance performance.

[0061] In this ignition coil 2, the directions of the magnetic flux in the common portion 58 between the first coil assembly 10 and the second coil assembly 20 are opposite. Therefore, the magnetic flux of the first coil assembly 10 and the magnetic flux of the second coil assembly 20 cancel each other out in the common portion 58. This prevents magnetic saturation in the common portion 58 and reduces the cross-sectional area of ​​the common portion 58. For example, even when the first coil assembly 10 and the second coil assembly 20 are energized simultaneously, magnetic saturation in the common portion 58 can be prevented. Even if the peak value of the primary current of each coil assembly 10 and the second coil assembly 20 is increased at a later energization time during alternating energization, magnetic saturation in the common portion 58 can be prevented.

[0062] The direction of the current flowing through the first primary coil 32 and the second primary coil 46 and the winding direction of these coils are not limited to Figure 1 When current flows through the first primary coil 32 and the second primary coil 46, the directions of the magnetic fluxes in the common portion 58 in the first coil group 10 and the second coil group 20 only need to be opposite. Furthermore, assuming the direction of the current flowing through the first primary coil 32 at this time is the first direction and the direction of the current flowing through the second primary coil 46 is the second direction, the directions of the first secondary coil 34 and the second secondary coil 48 are determined so that the direction of the induced current generated in the first secondary coil 34 when the current flowing in the first primary coil 32 is cut off and the direction of the induced current generated in the second secondary coil 48 when the current flowing in the second primary coil 46 is cut off are the same at the output port 28.

[0063] In this embodiment, the cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the first iron core 36 excluding the common portion 58 and the cross-sectional area of ​​the second iron core 50 excluding the common portion 58. When the cross-sectional area of ​​the common portion 58 is represented by Ss and the minimum value of the cross-sectional area of ​​the first iron core 36 excluding the common portion 58 and the cross-sectional area of ​​the second iron core 50 excluding the common portion 58 is represented by Sab, the ratio (Ss / Sab) is preferably 70% or less, and more preferably 60% or less, from the perspective of suppressing the increase in the volume of the ignition coil 2. From the perspective of easily controlling the magnetic flux φ of the common portion 58, S Not exceeding the maximum magnetic flux max SFrom the viewpoint of the ratio (Ss / Sab), the ratio (Ss / Sab) is preferably 30% or more, more preferably 40% or more.

[0064] The first coil assembly 10 preferably has a first magnet 38. As described above, the first magnet 38 causes the first core 36 to generate a magnetic flux in a direction opposite to the magnetic flux generated in the first core 36 when current flows through the first primary coil 32. Figure 6 As shown in (c), by doing so, the magnetic flux φ when no current flows in the first primary coil 32 can be A Set to a negative value. Figure 6 In the example (c), the magnetic flux is (-max AB By passing current through the first primary coil 32, the magnetic flux can be increased to the maximum magnetic flux max AB That is, in Figure 6 In the example (c), the magnetic flux φ generated by flowing current through the first primary coil 32 A The maximum value of the change is from (-max AB ) to max AB (2×max AB ). On the other hand, when the first magnet 38 is not provided, the magnetic flux φ A The maximum value of the change is from 0 to max AB Max AB It can be understood that by providing the first magnet 38, the magnetic flux φ can be increased without causing magnetic flux saturation, compared to the case where the first magnet 38 is not provided. A By increasing the magnetic flux φ A The change in the current I of the first secondary coil 34 can be increased. 2-A This contributes to excellent ignition and combustion maintenance performance. For the same reason, the second set of coils 20 preferably includes a second magnet 52.

[0065] In this embodiment, the controller 6 can operate the ignition coil 2 in the simultaneous energization mode. In the simultaneous energization mode, since current is outputted from the first coil group 10 and the second coil group 20 to the output port 28 at the same time, Figure 5 As shown in (e), it is possible to increase the amount of current output from the ignition coil 2. This contributes to excellent ignition performance.

[0066] In this embodiment, the controller 6 can operate the ignition coil 2 in the alternating energizing mode. In the alternating energizing mode, current is alternately output from the first coil group 10 and the second coil group 20 to the output port 28. Figure 7 As shown in (e), it is possible to extend the output period of the output current of the ignition coil 2. This contributes to excellent ignition performance and combustion maintenance performance.

[0067] In this embodiment, the rate of change of the magnetic flux when the first control signal CNT1 is "on" is greater than the rate of change of the magnetic flux when the first control signal CNT1 is "off". Figure 8 As shown in (c), the peak value of the magnetic flux φA in each "on" period becomes larger as the "on" period progresses. Similarly, the rate of change of the magnetic flux when the second control signal CNT2 is "on" is greater than the rate of change of the magnetic flux when the second control signal CNT2 is "off". Figure 8 As shown in (d), the magnetic flux φ during each “on” period B The peak value of becomes larger as the “on” period increases. Figure 7 As shown in (e), the output current of the ignition coil 2 has some differences, but can be gradually increased as a whole.

[0068] In this embodiment, the controller 6 can operate the ignition coil 2 in the composite energization mode. In the composite energization mode, first, current is outputted from the first coil group 10 and the second coil group 20 simultaneously to the output port 28, and then current is outputted from the first coil group 10 and the second coil group 20 alternately to the output port 28. Figure 9 As shown in (e), it is possible to output a large current first and then continue to output the current. This contributes to excellent ignition and combustion maintenance performance.

[0069] In this embodiment, in the alternating energization mode and the composite energization mode, in order to make the magnetic flux φ S Not exceeding the maximum magnetic flux max S , controller 6 controls the current I 1-A and current I 1-B The size of the current I 1-A and current I 1-B The energization time and the cut-off time and the number of repetitions of energization and cut-off are controlled. Thus, magnetic saturation at the common portion 58 can be prevented.

[0070] The combination method of simultaneous energization and alternating energization of the first coil group 10 and the second coil group 20 in the composite energization mode is not limited to Figure 9 Other combination methods of having large current output performance with simultaneous energization and long current output performance with alternating energization can be envisioned.

[0071] As described above, according to this embodiment, it is possible to provide an ignition coil that achieves excellent ignition performance while suppressing an increase in size.

[0072] [Public Project] The following items are disclosures of preferred embodiments.

[0073] [Project 1] An ignition coil, comprising: a first coil group including a first primary coil and a first secondary coil, a first central iron core passing through the first primary coil and the first secondary coil, and a first peripheral iron core surrounding the first primary coil and the first secondary coil; a second coil group including a second primary coil and a second secondary coil, a second central iron core passing through the second primary coil and the second secondary coil, and a second peripheral iron core surrounding the second primary coil and the second secondary coil; and an output port connected to the first secondary coil and the second secondary coil, The first peripheral iron core and the second peripheral iron core have a common portion, The direction of the magnetic flux generated in the common portion when current flows in a first direction in the first primary coil is opposite to the direction of the magnetic flux generated in the common portion when current flows in a second direction in the second primary coil. The induced current generated in the first secondary coil when the current of the first primary coil flowing in the first direction is cut off is in the same direction as the induced current generated in the second secondary coil when the current of the second primary coil flowing in the second direction is cut off.

[0074] [Project 2] According to the ignition coil described in item 1, the cross-sectional area of ​​the common portion is smaller than the cross-sectional area of ​​the first central iron core and the cross-sectional area of ​​the portion other than the common portion of the first peripheral iron core, and the cross-sectional area of ​​the second central iron core and the cross-sectional area of ​​the portion other than the common portion of the second peripheral iron core.

[0075] [Item 3] The ignition coil according to item 1 or 2 further comprises a first magnet located adjacent to one end of the first center core and a second magnet located adjacent to one end of the second center core. When current flows in the first direction in the first primary coil, the direction of the magnetic flux generated in the first central core is opposite to the direction of the magnetic flux generated in the first central core by the first magnet. When current flows in the second primary coil in the second direction, a direction of magnetic flux generated in the second center core is opposite to a direction of magnetic flux generated in the second center core by the second magnet.

[0076] [Item 4] A control method, which is the control method of an ignition coil according to any one of items 1 to 3, The current of the first primary coil is turned on and off, and the current of the second primary coil is turned on and off simultaneously.

[0077] [Item 5] A control method, which is the control method of an ignition coil according to any one of items 1 to 3, The conduction and interruption of the current of the first primary coil and the conduction and interruption of the current of the second primary coil are repeated alternately one or more times.

[0078] [Item 6] According to the control method described in item 5, the rate of change of the magnetic flux during the energization period of the first primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the first primary coil is disconnected after energization. The rate of change of the magnetic flux during the energization period of the second primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the second primary coil is disconnected after energization.

[0079] [Item 7] According to the control method described in item 5 or 6, the current magnitude, energization time, disconnection time, and number of repetitions of the first primary coil and the second primary coil are controlled respectively so that the common portion does not undergo magnetic saturation.

[0080] [Item 8] According to any one of items 5 to 7, the control method includes simultaneously performing the conduction and interruption of the current of the first primary coil and the conduction and interruption of the current of the second primary coil. Next, the conduction and interruption of the current to the first primary coil and the conduction and interruption of the current to the second primary coil are repeated alternately one or more times.

[0081] [Item 9] An ignition system comprising: the ignition coil according to any one of items 1 to 3, a controller for controlling the conduction and interruption of current in the first primary coil and the second primary coil, and a spark plug connected to the output port. The controller simultaneously turns on and off the current of the first primary coil and turns on and off the current of the second primary coil.

[0082] [Item 10] An ignition system comprising: the ignition coil according to any one of items 1 to 3, a controller for controlling the conduction and interruption of current in the first primary coil and the second primary coil, and a spark plug connected to the output port. The controller alternately repeats turning on and off the current of the first primary coil and turning on and off the current of the second primary coil one or more times.

[0083] [Item 11] According to the ignition system of item 10, the rate of change of the magnetic flux during the energization period of the first primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the first primary coil is disconnected after energization. The rate of change of the magnetic flux during the energization period of the second primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the second primary coil is disconnected after energization.

[0084] [Item 12] According to the ignition system of item 10 or 11, the controller controls the current magnitude, energization time, disconnection time, and number of repetitions of the first primary coil and the second primary coil respectively so that the common portion does not undergo magnetic saturation.

[0085] [Item 13] According to the ignition system of any one of items 10 to 12, the controller simultaneously turns on and off the current of the first primary coil and turns on and off the current of the second primary coil. Next, the conduction and interruption of the current to the first primary coil and the conduction and interruption of the current to the second primary coil are repeated alternately one or more times.

[0086] The ignition device described above is used for ignition of various combustion devices.

[0087] The above description is merely an example, and various modifications can be made without departing from the essence of the present invention.

Claims

1. An ignition coil, characterized in that: have: a first coil group including a first primary coil and a first secondary coil, a first central iron core passing through the first primary coil and the first secondary coil, and a first peripheral iron core surrounding the first primary coil and the first secondary coil; a second coil group comprising a second primary coil and a second secondary coil, a second central iron core passing through the second primary coil and the second secondary coil, and a second peripheral iron core surrounding the second primary coil and the second secondary coil; as well as an output port connected to the first secondary coil and the second secondary coil, The first peripheral iron core and the second peripheral iron core have a common portion, The direction of the magnetic flux generated in the common portion when current flows in a first direction in the first primary coil is opposite to the direction of the magnetic flux generated in the common portion when current flows in a second direction in the second primary coil. The induced current generated in the first secondary coil when the current of the first primary coil flowing in the first direction is cut off is in the same direction as the induced current generated in the second secondary coil when the current of the second primary coil flowing in the second direction is cut off.

2. The ignition coil according to claim 1, characterized in that The cross-sectional area of ​​the common portion is smaller than the cross-sectional area of ​​the first central iron core and the portion of the first peripheral iron core other than the common portion, and the cross-sectional area of ​​the second central iron core and the portion of the second peripheral iron core other than the common portion.

3. The ignition coil according to claim 1 or 2, characterized in that: further comprising a first magnet located adjacent to an end portion of the first central core and a second magnet located adjacent to an end portion of the second central core, When current flows in the first direction in the first primary coil, the direction of the magnetic flux generated in the first central core is opposite to the direction of the magnetic flux generated in the first central core by the first magnet. The direction of the magnetic flux generated in the second center core when current flows in the second primary coil in the second direction is opposite to the direction of the magnetic flux generated in the second center core by the second magnet.

4. A control method, characterized in that: This is the control method of the ignition coil according to claim 1 or 2, The current of the first primary coil is turned on and off, and the current of the second primary coil is turned on and off simultaneously.

5. A control method, characterized in that: This is the control method of the ignition coil according to claim 1 or 2, The conduction and interruption of the current of the first primary coil and the conduction and interruption of the current of the second primary coil are repeated alternately one or more times.

6. The control method according to claim 5, characterized in that: The rate of change of the magnetic flux during the energization period of the first primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the first primary coil is energized and then disconnected. The rate of change of the magnetic flux during the energization period of the second primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the second primary coil is disconnected after energization.

7. The control method according to claim 5, characterized in that: The current magnitude, energization time, disconnection time, and number of repetitions of the first primary coil and the second primary coil are controlled respectively in such a manner that the common portion does not undergo magnetic saturation.

8. The control method according to claim 5, characterized in that: The current of the first primary coil is turned on and off, and the current of the second primary coil is turned on and off simultaneously. Next, the current flow through the first primary coil and the current flow through the second primary coil are alternately repeated one or more times.

9. An ignition system, characterized in that: have: The ignition coil according to claim 1 or 2, a controller for controlling the conduction and cutoff of current in the first primary coil and the second primary coil, and a spark plug connected to the output port, The controller simultaneously turns on and off the current of the first primary coil and turns on and off the current of the second primary coil.

10. An ignition system, characterized in that: have: The ignition coil according to claim 1 or 2, a controller for controlling the conduction and cutoff of current in the first primary coil and the second primary coil, and a spark plug connected to the output port, The controller alternately repeats turning on and off the current of the first primary coil and turning on and off the current of the second primary coil one or more times.

11. The ignition system according to claim 10, characterized in that The rate of change of the magnetic flux during the energization period of the first primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the first primary coil is energized and then disconnected. The rate of change of the magnetic flux during the energization period of the second primary coil is greater than the rate of change of the magnetic flux during the disconnection period when the second primary coil is disconnected after energization.

12. The ignition system according to claim 10, characterized in that The controller controls the current magnitude, power-on time, power-off time, and number of repetitions of the first primary coil and the second primary coil respectively so that the common portion does not undergo magnetic saturation.

13. The ignition system according to claim 10, characterized in that The controller simultaneously turns on and off the current of the first primary coil and turns on and off the current of the second primary coil. Next, the current flow through the first primary coil and the current flow through the second primary coil are alternately repeated one or more times.

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