Ignition coil

Abstract

To provide an ignition coil in which an increase in size is suppressed while excellent ignitability is realized.SOLUTION: In an ignition coil 2 according to an embodiment, a first outer peripheral iron core 36o of a first coil set 10 and a second outer peripheral iron core 50o of a second coil set 20 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 set 10 is opposite to a direction of the magnetic flux generated in the common portion 58 when the current flows through a second primary coil 46 of the second coil set 20 in a second direction. The direction of an induced current generated in a first secondary coil 34 when the current of the first primary coil 32 is cut off at an output port 28 is the same as the direction of the induced current generated in a second secondary coil 48 when the current of the second primary coil 46 is cut off at the output port 28.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present specification relates to an ignition coil. [Background technology]

[0002] In internal combustion engines, ignition coils are used to operate the spark plugs located in the combustion chamber. Generally, ignition coils include an iron core, a primary coil, a secondary coil, and a switch that turns on and off the current in the primary coil. When the current flowing through the primary coil is cut off, a high induced electromotive force is generated in the secondary coil. This high voltage is applied to the spark plug to generate a spark discharge, igniting the fuel.

[0003] In recent years, internal combustion engines using lean fuels or low-flammability fuels such as ammonia have been realized. These internal combustion engines require greater energy than conventional engines to ignite and maintain combustion. To meet this demand, ignition coils with two sets of "iron core, primary coil, and secondary coil" (referred to as coil sets) have been studied and put into practical use. For example, the ignition coil disclosed in JP 2015-129464 A extends the duration of discharge by alternately operating each of the two coil sets. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-129464 A Summary of the Invention [Problem to be solved by the invention]

[0005] In internal combustion engines, such as engines, an ignition coil is installed for each cylinder. In multi-point ignition engines, multiple ignition coils are used for each cylinder. Ignition coils with two coil sets are large in volume, which can be a factor in preventing the downsizing of internal combustion engines. There is a demand for ignition coils that achieve excellent ignition performance while minimizing their size.

[0006] The present inventors have intended to provide an ignition coil that achieves excellent ignition performance while suppressing an increase in size. [Means for solving the problem]

[0007] An ignition coil according to one embodiment includes: a first coil set including a first primary coil and a first secondary coil, a first central core penetrating the first primary coil and the first secondary coil, and a first outer core wound around the first primary coil and the first secondary coil; a second coil set including a second primary coil and a second secondary coil, a second central core penetrating the second primary coil and the second secondary coil, and a second outer core wound around 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 outer core and the second outer core have a common portion. When a current flows through the first primary coil in a first direction, the direction of magnetic flux generated in the common portion is opposite to the direction of magnetic flux generated in the common portion when a current flows through the second primary coil in a second direction. The direction at the output port of the induced current generated in the first secondary coil when the current flowing in the first direction in the first primary coil is interrupted is the same as the direction at the output port of the induced current generated in the second secondary coil when the current flowing in the second direction in the second primary coil is interrupted. [Effects of the Invention]

[0008] In this ignition coil, the direction of the induced current at the output port is the same for the first coil set and the second coil set, but the direction of the magnetic flux at the common portion between the first and second outer cores is opposite. Because the direction of the induced current output from the first coil set and the second coil set is the same, the sum of these induced currents can be supplied to the spark plug. This contributes to excellent ignition performance. Because the direction of the magnetic flux at the common portion between the first coil set and the second coil set is opposite, the magnetic flux of the first coil set and the magnetic flux of the second coil set cancel each other out in the common portion. This allows the cross-sectional area of ​​the common portion to be reduced without causing magnetic saturation in the common portion. This suppresses an increase in the volume of the ignition coil. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram of an ignition system including an ignition coil according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing two coil sets of the ignition coil of FIG. [Figure 3] FIG. 3 is a perspective view showing the iron cores and magnets of the two coil sets of FIG. [Figure 4] FIG. 4 is a magnetic circuit diagram of the two coil sets of FIG. [Figure 5] FIG. 5 is an example of a timing chart in the simultaneous energization mode of the ignition coils of FIG. 1, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the current in the first primary coil, (d) represents the current in the second primary coil, and (e) represents the output current of the ignition coil. [Figure 6] FIG. 6 is an example of a timing chart for the mode of FIG. 5, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the magnetic flux at the first central core, (d) represents the magnetic flux at the second central core, and (e) represents the magnetic flux at the common part. [Figure 7]FIG. 7 is an example of a timing chart in the alternating current mode of the ignition coil of FIG. 1, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the current in the first primary coil, (d) represents the current in the second primary coil, and (e) represents the output current of the ignition coil. [Figure 8] FIG. 8 is an example of a timing chart for the mode of FIG. 7, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the magnetic flux at the first central core, (d) represents the magnetic flux at the second central core, and (e) represents the magnetic flux at the common part. [Figure 9] FIG. 9 is an example of a timing chart in the combined current conduction mode of the ignition coil of FIG. 1, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the current in the first primary coil, (d) represents the current in the second primary coil, and (e) represents the output current of the ignition coil. [Figure 10] FIG. 10 is an example of a timing chart for the mode of FIG. 9, where (a) represents the input signal to the first coil set, (b) represents the input signal to the second coil set, (c) represents the magnetic flux at the first central core, (d) represents the magnetic flux at the second central core, and (e) represents the magnetic flux at the common part. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.

[0011] 1 is a circuit diagram showing an ignition system 4 including an ignition coil 2 according to one embodiment. In addition to the ignition coil 2, the ignition system 4 also includes a controller 6 and a spark plug 8. The spark plug 8 is located in a combustion chamber of a combustion device such as an engine. In the ignition system 4 for an automobile, for example, the controller 6 is realized by an ECU.

[0012] The ignition coil 2 includes a first coil set 10, a first switch 12, a first diode 14, a first control port 16, a second coil set 20, a second switch 22, a second diode 24, a second control port 26, an output port 28, a power supply port 18, and a ground port 30. Fig. 2 is a cross-sectional view showing the first coil set 10 and the second coil set 20. Fig. 3 is a perspective view showing only the iron cores of the first coil set 10 and the second coil set 20.

[0013] As shown in FIG. 1 , the first coil set 10 includes a first primary coil 32, a first secondary coil 34, and a first iron core 36. As shown in FIGS. 2 and 3 , the first coil set 10 further includes a first magnet 38, and the first iron core 36 includes a first central iron core 36c and a first outer iron core 36o. The first primary coil 32 is formed by winding a wire around the outer periphery of the first central iron core 36c. The first secondary coil 34 is formed by winding a wire around the outer periphery of the first central iron core 36c. A typical material for these wires is copper (Cu). In this embodiment, the first secondary coil 34 is formed outside the first primary coil 32. The number of turns of the wire in the first secondary coil 34 is significantly greater than the number of turns of the wire in the first primary coil 32.

[0014] The first central core 36c has a columnar shape. In this embodiment, the first central core 36c has a rectangular columnar shape. The first central core 36c passes through the centers of the first primary coil 32 and the first secondary coil 34. The first outer 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 outer peripheral core 36o includes a lower pillar portion 40 facing the bottom surface of the first central core 36c at one end, an upper pillar portion 42 contacting the side surface of the first central core 36c at the other end, and a beam portion 44 located between the lower pillar portion 40 and the upper pillar portion 42. The beam portion 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 at one end of the first center core 36c, between its bottom surface and the lower pillar portion 40. The first center core 36c and the first outer peripheral core 36o are made of a magnetic material. Preferred examples of the magnetic material include ferrite, dust, and silicon steel.

[0015] In this embodiment, the second coil set 20 has a structure similar to that of the first coil set 10. That is, the second coil set 20 includes a second primary coil 46, a second secondary coil 48, and a second iron core 50. The second coil set 20 further includes a second magnet 52, and the second iron core 50 includes a second central iron core 50c and a second outer iron core 50o. The second primary coil 46 is formed by winding a wire around the second central iron core 50c. The second secondary coil 48 is formed by winding a wire around the second central iron core 50c. A typical material for these wires is copper. In this embodiment, the second secondary coil 48 is formed outside the second primary coil 46. The number of wire turns of the second secondary coil 48 is significantly greater than the number of wire turns of the second primary coil 46.

[0016] The second central core 50c has a columnar shape. In this embodiment, the second central core 50c has a rectangular columnar shape. The second central core 50c passes through the centers of the second primary coil 46 and the second secondary coil 48. The second outer 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, and to the other end of the second central core 50c. The second outer peripheral core 50o includes a lower pillar portion 53 facing the bottom surface of the second central core 50c at one end, an upper pillar portion 54 contacting the side surface of the second central core 50c at the other end, and a beam portion 56 located between the lower pillar portion 53 and the upper pillar portion 54. The beam portion 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 at one end of the second center core 50c, between its bottom surface and the lower pillar portion 53. The second center core 50c and the second outer peripheral core 50o are made of a magnetic material. Preferred examples of the magnetic material include ferrite, dust, and silicon steel.

[0017] As shown in FIGS. 2 and 3 , the first outer periphery iron core 36o and the second outer periphery iron core 50o have a common portion 58. In this embodiment, the beam portion 44 of the first outer periphery iron core 36o and the beam portion 56 of the second outer periphery iron core 50o form the common portion 58. In this embodiment, the width of the common portion 58 is narrower than the width of other portions of the first iron core 36 and the second iron core 50. That is, the cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the portions of the first center iron core 36c and the first outer periphery iron core 36o other than the common portion 58. The cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the portions of the second center iron core 50c and the second outer periphery iron core 50o other than the common portion 58. Here, each cross-sectional area is measured in a cross section perpendicular to the direction of magnetic flux generated inside the first iron core 36 and the second iron core 50, which will be described later. When the cross-sectional areas of the first central iron core 36c, the first outer peripheral iron core 36o other than the common portion 58, the second central iron core 50c, the second outer peripheral iron core 50o other than the common portion 58, and the common portion 58 are not constant depending on the position, the cross-sectional area of ​​each is measured at the position where it is smallest.

[0018] The first switch 12 is located between the first primary coil 32 and the ground port 30. A first control port 16 is connected to the first switch 12. The first switch 12 switches between electrical conduction (ON) and interruption (OFF) between the first primary coil 32 and the ground port 30 in response to a signal from the first control port 16. In this embodiment, the first switch 12 is an IGBT (insulated gate bipolar transistor). The first switch 12 may be realized by other devices. For example, the first switch 12 may be realized by a MOSFET.

[0019] The second switch 22 is located between the second primary coil 46 and the ground port 30. A second control port 26 is connected to the second switch 22. The second switch 22 switches between conduction and cut-off between the second primary coil 46 and the ground port 30 in response to a signal from the second control port 26. In this embodiment, the second switch 22 is an IGBT. The second switch 22 may be realized by other devices. For example, the second switch 22 may be realized by a MOSFET.

[0020] The first diode 14 is located between the first secondary coil 34 and the output port 28. The first diode 14 limits the direction of current flow in the first secondary coil 34. The second diode 24 is located between the second secondary coil 48 and the output port 28. The second diode 24 limits the direction of current flow in the second secondary coil 48.

[0021] The power supply port 18 is connected to the first primary coil 32 and the second primary coil 46. When the first switch 12 is in a conductive state, current flows from the power supply port 18 to the first primary coil 32. When the second switch 22 is in a conductive state, current flows from the power supply port 18 to the second primary coil 46. The arrow φ in FIG. cA represents the magnetic flux generated by the current flowing through the first primary coil 32, and the arrow φ cB represents the magnetic flux generated by the current flowing through the second primary coil 46. As shown in FIG. 2, the magnetic flux φcA The direction of the magnetic flux φ cB In other words, when a current flows from the power supply port 18 to the first primary coil 32 and the second primary coil 46, a magnetic flux φ cA The direction of the magnetic flux φ cB The winding directions of the wires of the first primary coil 32 and the second primary coil 46 are determined so as to be opposite to the winding direction of the wires of the first primary coil 32 and the second primary coil 46.

[0022] 1, one power port 18 is connected to the first primary coil 32 and the second primary coil 46. There may be another power port 18 connected to the first primary coil 32 and another power port 18 connected to the second primary coil 46. There may be another ground port 30 connected to the first switch 12 and another ground port 30 connected to the second switch 22.

[0023] Arrow φ in Figure 2 mA represents the magnetic flux due to the first magnet 38. As shown in FIG. mA The direction of the magnetic flux φ cA The arrow φ mB represents the magnetic flux due to the second magnet 52. mB The direction of the magnetic flux φ cB In other words, the magnetic flux φ mA The direction of the magnetic flux φ cA The direction of the magnetic flux φ mB The direction of the magnetic flux φ cB In this case, a first magnet 38 and a second magnet 52 are used so that the orientation of the magnets is opposite to that of the first magnet 38 and the second magnet 52.

[0024] The output port 28 is connected to the first secondary coil 34 and the second secondary coil 48. When the current flowing through the first primary coil 32 is interrupted, an induced electromotive force is generated in the first secondary coil 34. An induced current flows from the first secondary coil 34 to the spark plug 8 via the output port 28. Similarly, when the current flowing through the second primary coil 46 is interrupted, an induced current flows from the second secondary coil 48 to the spark plug 8 via the output port 28. The direction of the induced current by the first secondary coil 34 and the direction of the induced current by the second secondary coil 48 at the output port 28 are the same. In other words, the winding directions of the wires of the first secondary coil 34 and the second secondary coil 48 are determined so that the direction of the induced current at the output port 28 in the first secondary coil 34 generated when the current in the first primary coil 32 is interrupted is the same as the direction of the induced current at the output port 28 in the second secondary coil 48 generated when the current in the second primary coil 46 is interrupted.

[0025] 4 is a magnetic circuit diagram of the first coil set 10 and the second coil set 20. In the figure, the symbol F A represents the magnetomotive force of the first coil set 10 due to the first primary coil 32, the first secondary coil 34, and the first magnet 38. B represents the magnetomotive force of the second coil set 20 due to the second primary coil 46, the second secondary coil 48, and the second magnet 52. AB is the magnetic resistance of each of the first coil set 10 and the second coil set 20 excluding the common portion 58, and in this embodiment, the magnetic resistance is the same for the first coil set 10 and the second coil set 20. A is the flux passing through the first coil set 10 other than the common portion 58, and φ A =φ cA -φ mA Symbol φ B is the flux passing through the second coil set 20 other than the common portion 58, and φ B =φ cB -φ mB Symbol R S is the reluctance of the common part 58.

[0026] In FIG. 4, the symbol φ S is the flux passing through the common part 58 and is expressed by the following equation: φ S =φ A -φ B =(F A -F B ) / (R AB +2R S ) If the first coil set 10 and the second coil set 20 have the same structure and the same current flows through the first coil set 10 and the second coil set 20, F A =F B In this case, the magnetic flux φ S It can be seen that becomes zero.

[0027] The controller 6 controls the operation of the ignition coil 2. As shown in FIG. 1 , a first control signal CNT1 of the controller 6 is connected to a first control port 16, and a second control signal CNT2 is connected to a second control port 26. The controller 6 switches the first switch 12 between conductive and non-conductive states using the signal CNT1, and switches the second switch 22 between conductive and non-conductive states using the signal CNT2. In this embodiment, a power supply terminal VDD of the controller 6 is connected to a power supply port 18 of the ignition coil 2. Current is supplied to the first coil set 10 and the second coil set 20 by the controller 6.

[0028] In this embodiment, the controller 6 can operate the ignition coil 2 in the following modes: (1) Simultaneous energization mode The first coil set 10 and the second coil set 20 are energized simultaneously. (2) Alternating current mode The first coil set 10 and the second coil set 20 are alternately energized. (3) Combined current mode A mode that combines simultaneous current conduction mode and alternating current conduction mode. These modes are described below.

[0029] [Simultaneous power supply mode] FIG. 5 is a timing chart showing the simultaneous conduction mode. In each of FIGS. 5(a) to 5(e), the horizontal axis represents time (t). FIG. 5(a) shows the first control signal CNT1 input to the first switch 12, and FIG. 5(b) shows the second control signal CNT2 input to the second switch 22. In these figures, "ON" means that the first control signal CNT1 and the second control signal CNT2 are values ​​that respectively put the first switch 12 and the second switch 22 into a conductive state. "OFF" means that the first control signal CNT1 and the second control signal CNT2 are values ​​that respectively put the first switch 12 and the second switch 22 into a non-conductive state.

[0030] FIG. 5(c) shows the current I 1-A When the first control signal CNT1 is turned “ON”, the first switch 12 is turned on, and the current I 1-A Thereafter, the first control signal CNT1 turns “OFF”, turning off the first switch 12, and the current I 1-A is cut off. Figure 5(d) shows the current I 1-B When the second control signal CNT2 is turned “ON”, the second switch 22 is turned on, and the current I 1-B Thereafter, the second control signal CNT2 turns “OFF”, turning the second switch 22 off and causing the current I 1-B is interrupted. Current I 1-A and current I 1-B It starts flowing and is cut off at the same time.

[0031] Figure 5(e) shows the output current I of the ignition coil 2. 2-Σ The dotted line box in Figure 5(e) shows the current I 1-A The current I in the first secondary coil 34 is generated when the 2-A , and current I 1-B The current I in the second secondary coil 48 occurs when 2-B is shown. Current I 2-A and current I 1-B and occur at the same time and in the same direction at output port 28, so the output current I 2-Σis the current I 2-A and current I 2-B The harmony of 2-Σ =I 2-A +I 2-B )

[0032] Fig. 6 is a timing chart showing the magnetic flux in the operation mode shown in Fig. 5. Fig. 6(a) and (b) show the first control signal CNT1 and the second control signal CNT2, respectively, which are the same as Fig. 5(a) and (b). Fig. 6(c) shows the magnetic flux φ A and Fig. 6(d) shows the magnetic flux φ B In these figures, the direction of the magnetic flux is indicated by a positive or negative sign. The magnetic flux φ generated by the current flowing through the first primary coil 32 is cA The direction of max is shown as positive. This also applies to the following Figures 8 and 10. In Figures 6(c) and (d), max AB and (-max AB ) represents the threshold of the magnetic flux amount (referred to as the maximum magnetic flux amount in this specification) at which the iron core becomes magnetically saturated in the portion other than the common portion 58. In this embodiment, the maximum magnetic flux amount in the portion other than the common portion 58 is the same for the first coil set 10 and the second coil set 20.

[0033] As shown in FIG. 6(c), before the first control signal CNT1 is turned "ON", the magnetic flux φ A is (-max AB ) which is the magnetic flux due to the first magnet 38. In this embodiment, the magnetic flux φ mA The magnitude (absolute value) of the maximum magnetic flux amount max AB When the first control signal CNT1 is turned "ON", the current I 1-A flows, and magnetic flux φ A In this embodiment, the current I 1-A The magnetic flux φ A is the maximum magnetic flux amount max AB When the first control signal CNT1 turns "OFF", the current I 1-A is cut off and the current I 2-A flows, so the magnetic flux φ A The magnetic flux φ shown in Figure 6(d)B Also, magnetic flux φ A It fluctuates according to the same principle as the magnetic flux φ B The direction of the magnetic flux φ A Since it is the opposite of B The graph of magnetic flux φ A In this embodiment, the magnetic flux φ mB The maximum magnetic flux amount is max AB A second magnet 52 equal to

[0034] Figure 6(e) shows the magnetic flux φ S In Fig. 6(e), the magnetic flux φ A and magnetic flux φ B The magnetic flux φ is also shown by a dotted line. A and magnetic flux φ B Since the polarity is opposite to that of the magnetic flux φ S is almost zero. In Fig. 6(e), max S represents the maximum amount of magnetic flux in the common portion 58. Since the cross-sectional area of ​​the common portion 58 is smaller than the cross-sectional area of ​​the other portions, the maximum amount of magnetic flux max S is the maximum magnetic flux amount max AB Even if the cross-sectional area of ​​the common portion 58 is made smaller than the cross-sectional area of ​​the other portions, the magnetic flux φ S is the maximum magnetic flux amount max S It is clear that this does not exceed the

[0035] [Alternating current mode] FIG. 7 is a timing chart showing the alternating current mode. FIG. 7(a) shows the first control signal CNT1, and FIG. 7(b) shows the second control signal CNT2. The controller 6 outputs the first control signal CNT1 "ON" and "OFF" and the second control signal CNT2 "ON" and "OFF" as a toggle signal that alternately repeats once or multiple 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." There may be some overlap between the period when the first control signal CNT1 is "ON" and the period when the second control signal CNT2 is "ON."

[0036] FIG. 7(c) shows the current I 1-A When the first control signal CNT1 is "ON", the current I 1-A flows, and when the first control signal CNT1 is "OFF", the current I 1-A In this embodiment, the current I 1-A As shown in FIG. 7(c), in this embodiment, the current I 1-A The magnitude of the peak of the current I becomes larger as it flows later. 1-B When the second control signal CNT2 is "ON", the current I 1-B flows, and when the second control signal CNT2 is "OFF", the current I 1-B In this embodiment, the current I 1-B The magnitude of the peak of the current I becomes larger as it flows later. 1-A and current I 1-B alternately flowing and alternately being blocked.

[0037] Figure 7(e) shows the output current I of the ignition coil 2. 2-Σ The dotted line box in Figure 7(e) shows the current I 1-A The current I in the first secondary coil 34 is generated when the 2-A , and current I 1-B The current I in the second secondary coil 48 occurs when 2-B is shown. Current I 2-A is the current I 1-A When the current is interrupted, the current I 2-B is the current I 1-B flows when the current is cut off, so the current I 2-A and current I 2-B In this embodiment, each current I 2-A and current I 2-B The magnitude of the peak of the output current I becomes larger as it flows later. 2-Σ is the current I 2-A and current I 1-B It is the sum of the current I 2-Σ is the initial current I 2-A The last I 1-BYou can see that it continues to flow until it finishes.

[0038] 8 is a timing chart showing the magnetic flux during the operation shown in FIG. 7. FIGS. 8(a) and 8(b) respectively show the first control signal CNT1 and the second control signal CNT2, which are the same as FIGS. 7(a) and 7(b). FIG. 8(c) shows the magnetic flux φ A and Fig. 8(d) shows the magnetic flux φ B Represents.

[0039] As shown in FIG. 8(c), when the first control signal CNT1 is turned "ON", the magnetic flux φ A rises, and when the first control signal CNT1 turns "OFF", the magnetic flux φ A In this embodiment, this rise and fall is repeated three times. In each case, the rate of change of the magnetic flux (the absolute value of the gradient of the magnetic flux graph) 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 of the magnetic flux during the "ON" period of the first control signal CNT1 becomes larger in the later "ON" period. In FIG. 7(c), the current I 1-A This is why the magnitude of the peak becomes larger the later it flows.

[0040] As shown in Figure 8(d), the magnetic flux φ B Also, magnetic flux φ A It fluctuates on the same principle as the magnetic flux φ A Since it is the opposite of B The polarity of the graph is the magnetic flux φ A In this embodiment, the polarity of the magnetic flux φ B The fall and rise of the magnetic flux is repeated three times. In each case, 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 peaks (downward peaks) of the magnetic flux during the "ON" period of the second control signal CNT2 become larger in the later "ON" periods.

[0041] The rate of change of the magnetic flux when the first control signal CNT1 and the second control signal CNT2 are "ON" can be made larger 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.

[0042] Figure 8(e) shows the magnetic flux φ S In Fig. 8(e), the magnetic flux φ A and magnetic flux φ B The magnetic flux φ is also shown by a dotted line. A and magnetic flux φ B and have opposite polarities and cancel each other out, so the magnetic flux φ S The magnitude (absolute value) of the peak is the magnetic flux φ A The magnitude of the peak and the magnetic flux φ B In this embodiment, the magnitude of the peak of the magnetic flux φ S is the maximum magnetic flux amount max S In other words, the controller 6 determines whether the magnetic flux φ S is the maximum magnetic flux amount max S The current I 1-A and current I 1-B The magnitude of the current I 1-A and current I 1-B The power-on and power-off times, as well as the number of times the power is turned on and off, are controlled.

[0043] [Composite energization mode] FIG. 9 is a timing chart showing the combined energization mode. FIG. 9(a) shows the first control signal CNT1, and FIG. 9(b) shows the second control signal CNT2. As in the simultaneous energization 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, as in the alternating energization mode, the controller 6 outputs toggle signals that alternate between "ON" and "OFF" for the first control signal CNT1 and "ON" and "OFF" for the second control signal CNT2 one or more times.

[0044] Figure 9(c) shows the current I 1-A and Fig. 9(d) shows the current I 1-B First, the current I 1-Aand current I 1-B The current I starts to flow and is cut off at the same time. 1-A and current I 1-B The current I alternately starts and stops flowing. 1-A and current I 1-B When and flow alternately, the current I 1-A The peak magnitude of the current I 1-B The magnitude of the peaks increases in the later flow.

[0045] Figure 9(e) shows the output current I of the ignition coil 2. 2-Σ The dotted line box in Figure 9(e) shows the current I 2-A and current I 2-B is shown. Current I 2-A and current I 2-B First, the currents I 2-A and current I 2-B The magnitude of the peak of the output current I becomes larger as it flows later. 2-Σ is the current I 2-A and current I 1-B It is the sum of the current I 2-Σ is the current I 2-A and current I 2-B When both flow simultaneously, the value becomes large, and then the last I 1-B It continues to flow until it finishes.

[0046] 10 is a timing chart showing the magnetic flux during the operation shown in FIG. 9. FIGS. 10(a) and 10(b) respectively show the first control signal CNT1 and the second control signal CNT2, which are the same as FIGS. 9(a) and 9(b). FIG. 10(c) shows the magnetic flux φ A and Fig. 10(d) shows the magnetic flux φ B Represents.

[0047] As shown in Figure 10(c), the magnetic flux φ A is the "ON" period of the first control signal CNT1, (-max AB ) to max AB During the subsequent "ON" period, the magnetic flux φA 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".

[0048] As shown in Figure 10(d), the magnetic flux φ B Also, magnetic flux φ A It fluctuates on the same principle as the magnetic flux φ A Since it is the opposite of B The polarity of the graph is the magnetic flux φ A The polarity of the graph is reversed. That is, the magnetic flux φ B is the "ON" period of the first second control signal CNT2, max AB to (-max AB ), and then rises during the subsequent "OFF" period. During the subsequent period in which the second control signal CNT2 toggles, 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".

[0049] Figure 10(e) shows the magnetic flux φ S In Fig. 10(e), the magnetic flux φ A and magnetic flux φ B The magnetic flux φ is also shown by a dotted line. A and magnetic flux φ B and have opposite polarities and cancel each other out, so the magnetic flux φ S The magnitude (absolute value) of the peak is the magnetic flux φ A The magnitude of the peak and the magnetic flux φ B In this embodiment, the magnitude of the peak of the magnetic flux φ S is the maximum magnetic flux amount max S In other words, the controller 6 determines whether the magnetic flux φ S is the maximum magnetic flux amount max S The current I 1-A and current I 1-B The magnitude of the current I 1-A and current I 1-B The power-on and power-off times, as well as the number of times the power is turned on and off, are controlled.

[0050] The effects of this embodiment will be described below.

[0051] In this ignition coil 2, the direction of the induced current at the output port 28 is the same for the first coil set 10 and the second coil set 20, but the direction of the magnetic flux at the common portion 58 between the first outer core 36o and the second outer core 50o is opposite. Because the direction of the induced current output from the first coil set 10 and the second coil set 20 is the same, the sum of these induced currents can be supplied as output current to the spark plug 8. This makes it possible to supply high ignition energy to the spark plug 8. This contributes to excellent ignition performance and combustion maintenance performance.

[0052] In this ignition coil 2, the magnetic flux directions in the common portion 58 of the first coil set 10 and the second coil set 20 are opposite to each other, so the magnetic flux of the first coil set 10 and the magnetic flux of the second coil set 20 cancel each other out in the common portion 58. This allows the cross-sectional area of ​​the common portion 58 to be reduced without causing magnetic saturation in the common portion 58. For example, even if the first coil set 10 and the second coil set 20 are energized simultaneously, magnetic saturation in the shared portion can be prevented. When the first coil set 10 and the second coil set 20 are alternately energized, magnetic saturation in the common portion 58 can also be prevented by making the peak of each primary current larger in the later energization.

[0053] 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 the embodiment shown in Fig. 1. It is sufficient that the magnetic flux directions in the common portion 58 of the first coil set 10 and the second coil set 20 are opposite when current flows through the first primary coil 32 and the second primary coil 46. Furthermore, when the direction of the current flowing through the first primary coil 32 is defined as a first direction and the direction of the current flowing through the second primary coil 46 is defined as a second direction, it is sufficient that 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 direction through the first primary coil 32 is interrupted is the same as the direction of the induced current generated in the second secondary coil 48 when the current flowing in the second direction through the second primary coil 46 is interrupted at the output port 28.

[0054] 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 other than the common portion 58 and the cross-sectional area of ​​the second iron core 50 other than the common portion 58. When the cross-sectional area of ​​the common portion 58 is Ss and the minimum value of the cross-sectional area of ​​the first iron core 36 other than the common portion 58 and the cross-sectional area of ​​the second iron core 50 other than the common portion 58 is Sab, from the viewpoint of suppressing an increase in the volume of the ignition coil 2, the ratio (Ss / Sab) is preferably 70% or less, and more preferably 60% or less. The magnetic flux φ of the common portion 58 S is the maximum magnetic flux amount max S From the viewpoint of facilitating control so as not to exceed this value, the ratio (Ss / Sab) is preferably 30% or more, and more preferably 40% or more.

[0055] The first coil set 10 preferably includes a first magnet 38. As described above, the first magnet 38 generates a magnetic flux in the first iron core 36 in the opposite direction to the magnetic flux generated in the first iron core 36 when a current is passed through the first primary coil 32. In this way, as shown in FIG. 6(c), for example, the magnetic flux φ A can be made a negative value. In the example of Figure 6(c), the magnetic flux is (-max AB) When a current flows through the first primary coil 32, the magnetic flux reaches a maximum magnetic flux amount max AB That is, in the example of FIG. 6(c), the magnetic flux φ A The maximum change in is (-max AB ) to max AB Up to (2 × max AB On the other hand, when the first magnet 38 is not provided, the magnetic flux φ A The maximum change in is from 0 to max AB up to max AB By providing the first magnet 38, the magnetic flux φ can be reduced without causing magnetic flux saturation, compared to when the first magnet 38 is not provided. A It can be seen that the amount of change in magnetic flux φ can be increased. A By increasing the amount of change in the current I 2-A This contributes to excellent ignition and combustion maintenance performance. For the same reason, the second coil set 20 preferably includes the second magnet 52.

[0056] In this embodiment, the controller 6 can operate the ignition coil 2 in a simultaneous conduction mode. In the simultaneous conduction mode, currents are simultaneously output from the first coil set 10 and the second coil set 20 to the output port 28, so that the amount of current output from the ignition coil 2 can be increased, as shown in FIG. 5(e). This contributes to excellent ignition performance.

[0057] In this embodiment, the controller 6 can operate the ignition coil 2 in an alternating current mode. In the alternating current mode, current is alternately output from the first coil set 10 and the second coil set 20 to the output port 28, so that the output period of the output current of the ignition coil 2 can be extended, as shown in Fig. 7(e). This contributes to excellent ignition performance and combustion maintenance performance.

[0058] In this embodiment, the rate of change of the magnetic flux when the first control signal CNT1 is "ON" is larger than the rate of change of the magnetic flux when the first control signal CNT1 is "OFF." As a result, as shown in FIG. 8(c), the magnetic flux φ A The peak of the magnetic flux φ becomes larger in the later "ON" period. Similarly, the rate of change of the magnetic flux when the second control signal CNT2 is "ON" is larger than the rate of change of the magnetic flux when the second control signal CNT2 is "OFF". As a result, as shown in FIG. 8(d), the magnetic flux φ B The peak of the current increases in the later "ON" period. By doing this, as shown in Figure 7(e), the output current of the ignition coil 2 can be gradually increased overall, although there are some steps.

[0059] In this embodiment, the controller 6 can operate the ignition coil 2 in a combined current mode. In the combined current mode, current is first output from the first coil set 10 and the second coil set 20 simultaneously to the output port 28, and then current is output from the first coil set 10 and the second coil set 20 alternately to the output port 28. In this manner, as shown in FIG. 9(e), a large current can be output initially, and then current can be output continuously. This contributes to excellent ignition performance and combustion maintenance performance.

[0060] In this embodiment, in the alternating current mode and the combined current mode, the controller 6 controls the magnetic flux φ S is the maximum magnetic flux amount max S The current I 1-A and current I 1-B The magnitude of the current I 1-A and current I 1-B The current-on time and current-off time of the common portion 58 and the number of times the current is turned on and off are controlled. In this way, magnetic saturation in the common portion 58 can be prevented.

[0061] The combination of simultaneous and alternating currents for the first coil set 10 and the second coil set 20 in the combined current supply mode is not limited to that shown in Fig. 9. Other combinations that provide the large current output performance of simultaneous current supply and the long current output performance of alternating current supply are possible.

[0062] 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. From this, the superiority of this embodiment is clear.

[0063] [Disclosure items] The following items are disclosures of preferred embodiments.

[0064] [Item 1] a first coil set including a first primary coil, a first secondary coil, a first central iron core passing through the first primary coil and the first secondary coil, and a first outer peripheral iron core surrounding the first primary coil and the first secondary coil; a second coil set including a second primary coil, a second secondary coil, a second central core passing through the second primary coil and the second secondary coil, and a second outer peripheral core surrounding the second primary coil and the second secondary coil; an output port connected to the first secondary coil and the second secondary coil; Equipped with The first outer circumferential iron core and the second outer circumferential iron core have a common portion, a direction of magnetic flux generated in the common portion when a current flows in a first direction through the first primary coil is opposite to a direction of magnetic flux generated in the common portion when a current flows in a second direction through the second primary coil; An ignition coil in which the direction at the output port of the induced current generated in the first secondary coil when the current flowing in the first direction in the first primary coil is interrupted is the same as the direction at the output port of the induced current generated in the second secondary coil when the current flowing in the second direction in the second primary coil is interrupted.

[0065] [Item 2] 2. An ignition coil according to item 1, wherein the cross-sectional area of ​​the common portion is smaller than the cross-sectional area of ​​the first center iron core and the cross-sectional area of ​​the portion of the first outer peripheral iron core other than the common portion, and the cross-sectional area of ​​the second center iron core and the cross-sectional area of ​​the portion of the second outer peripheral iron core other than the common portion.

[0066] [Item 3] further comprising a first magnet located adjacent an end of the first central core and a second magnet located adjacent an end of the second central core; a direction of magnetic flux generated in the first central iron core when a current flows in the first direction through the first primary coil is opposite to a direction of magnetic flux generated in the first central iron core by the first magnet; 3. The ignition coil according to item 1 or 2, wherein a direction of magnetic flux generated in the second central iron core when a current flows in the second direction through the second primary coil is opposite to a direction of magnetic flux generated in the second central iron core by the second magnet.

[0067] [Item 4] 4. The method for controlling an ignition coil according to any one of items 1 to 3, A control method in which current is simultaneously conducted and cut off in the first primary coil and current is simultaneously conducted and cut off in the second primary coil.

[0068] [Item 5] 4. The method for controlling an ignition coil according to any one of items 1 to 3, A control method in which the conduction and interruption of current through the first primary coil and the conduction and interruption of current through the second primary coil are alternately repeated one or more times.

[0069] [Item 6] a rate of change of magnetic flux during a period when the first primary coil is energized is greater than a rate of change of magnetic flux during a period when the first primary coil is deenergized after being energized, 6. The control method according to item 5, wherein a rate of change of magnetic flux during a period when the second primary coil is energized is greater than a rate of change of magnetic flux during a period when the second primary coil is deenergized after being energized.

[0070] [Item 7] 7. The control method according to item 5 or 6, wherein the magnitude of the current, the energization time, the interruption time, and the number of repetitions of the current of each of the first primary coil and the second primary coil are controlled so that the common portion does not become magnetically saturated.

[0071] [Item 8] Conducting and interrupting the current through the first primary coil and conducting and interrupting the current through the second primary coil simultaneously, Subsequently, the control method according to any one of items 5 to 7, wherein the conduction and interruption of the current in the first primary coil and the conduction and interruption of the current in the second primary coil are alternately repeated one or more times.

[0072] [Item 9] an ignition coil according to any one of items 1 to 3, a controller for controlling current conduction and cutoff in the first primary coil and the second primary coil, and an ignition plug connected to the output port; An ignition system in which the controller simultaneously conducts and cuts off current to the first primary coil and simultaneously conducts and cuts off current to the second primary coil.

[0073] [Item 10] an ignition coil according to any one of items 1 to 3, a controller for controlling current conduction and cutoff in the first primary coil and the second primary coil, and an ignition plug connected to the output port; An ignition system in which the controller alternately repeats one or more times the conduction and interruption of current through the first primary coil and the conduction and interruption of current through the second primary coil.

[0074] [Item 11] a rate of change of magnetic flux during a period when the first primary coil is energized is greater than a rate of change of magnetic flux during a period when the first primary coil is deenergized after being energized, Item 11. The ignition system according to item 10, wherein a rate of change of magnetic flux during a period when the second primary coil is energized is greater than a rate of change of magnetic flux during a period when the second primary coil is de-energized after being energized.

[0075] [Item 12] 12. The ignition system according to item 10 or 11, wherein the controller controls the magnitude of current, current-on time, current-off time, and number of repetitions of current in each of the first primary coil and the second primary coil so as to prevent magnetic saturation in the common portion.

[0076] [Item 13] the controller simultaneously conducts and cuts off the current in the first primary coil and simultaneously conducts and cuts off the current in the second primary coil, 13. The ignition system according to any one of items 10 to 12, wherein the current conduction and interruption of the first primary coil and the current conduction and interruption of the second primary coil are alternately repeated one or more times. [Industrial Applicability]

[0077] The ignition device described above can be used to ignite a variety of combustion devices. [Explanation of symbols]

[0078] 2. Ignition coil 4. Ignition system 6. Controller 8. Spark plug 10. First coil set 12. First switch 14. First diode 16. First control port 18. Power port 20 Second coil set 22 Second switch 24 Second diode 26 Second control port 28 Output port 30. Grand Port 32 First primary coil 34...First secondary coil 36...first iron core 36c...First central iron core 36o...First outer iron core 38...first magnet 40, 53...Lower column part 42, 54...Upper column 44, 56...beam section 46 Second primary coil 48...Second secondary coil 50...Second iron core 50c...Second central iron core 50o...Second outer iron core 52...Second magnet

Claims

1. a first coil set including a first primary coil, a first secondary coil, a first central iron core passing through the first primary coil and the first secondary coil, and a first outer peripheral iron core surrounding the first primary coil and the first secondary coil; a second coil set including a second primary coil, a second secondary coil, a second central core passing through the second primary coil and the second secondary coil, and a second outer peripheral core surrounding the second primary coil and the second secondary coil; an output port connected to the first secondary coil and the second secondary coil; Equipped with The first outer circumferential iron core and the second outer circumferential iron core have a common portion, a direction of magnetic flux generated in the common portion when a current flows in a first direction through the first primary coil is opposite to a direction of magnetic flux generated in the common portion when a current flows in a second direction through the second primary coil; An ignition coil in which the direction at the output port of the induced current generated in the first secondary coil when the current flowing in the first direction in the first primary coil is interrupted is the same as the direction at the output port of the induced current generated in the second secondary coil when the current flowing in the second direction in the second primary coil is interrupted.

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

3. further comprising a first magnet located adjacent an end of the first central core and a second magnet located adjacent an end of the second central core; a direction of magnetic flux generated in the first central iron core when a current flows in the first direction through the first primary coil is opposite to a direction of magnetic flux generated in the first central iron core by the first magnet; 3. The ignition coil according to claim 1, wherein the direction of magnetic flux generated in the second central iron core when a current flows in the second direction through the second primary coil is opposite to the direction of magnetic flux generated in the second central iron core by the second magnet.

4. 3. The ignition coil control method according to claim 1, further comprising: A control method in which current is simultaneously conducted and cut off in the first primary coil and current is simultaneously conducted and cut off in the second primary coil.

5. 3. The ignition coil control method according to claim 1, further comprising: A control method in which the conduction and interruption of current through the first primary coil and the conduction and interruption of current through the second primary coil are alternately repeated one or more times.

6. a rate of change of magnetic flux during a period when the first primary coil is energized is greater than a rate of change of magnetic flux during a period when the first primary coil is deenergized after being energized, 6. The control method according to claim 5, wherein a rate of change of magnetic flux of the second primary coil during a period when the second primary coil is energized is greater than a rate of change of magnetic flux of the second primary coil during a period when the second primary coil is de-energized after being energized.

7. 6. The control method according to claim 5, wherein the magnitude of the current, the energization time, the interruption time, and the number of repetitions of the current in each of the first primary coil and the second primary coil are controlled so as to prevent magnetic saturation in the common portion.

8. Conducting and interrupting the current through the first primary coil and conducting and interrupting the current through the second primary coil simultaneously, The control method according to claim 5 , further comprising: repeating the conduction and interruption of the current through the first primary coil and the conduction and interruption of the current through the second primary coil alternately one or more times.

9. an ignition coil according to claim 1 or 2, a controller that controls current conduction and cutoff in the first primary coil and the second primary coil, and an ignition plug connected to the output port; An ignition system in which the controller simultaneously conducts and cuts off current to the first primary coil and simultaneously conducts and cuts off current to the second primary coil.

10. an ignition coil according to claim 1 or 2, a controller that controls current conduction and cutoff in the first primary coil and the second primary coil, and an ignition plug connected to the output port; An ignition system in which the controller alternately repeats one or more times the conduction and interruption of current through the first primary coil and the conduction and interruption of current through the second primary coil.

11. a rate of change of magnetic flux during a period when the first primary coil is energized is greater than a rate of change of magnetic flux during a period when the first primary coil is deenergized after being energized, 11. The ignition system according to claim 10, wherein a rate of change of magnetic flux of the second primary coil during a period when the second primary coil is energized is greater than a rate of change of magnetic flux during a period when the second primary coil is de-energized after being energized.

12. 11. The ignition system of claim 10, wherein the controller controls the magnitude, conduction time, cut-off time, and number of repetitions of current in each of the first primary coil and the second primary coil so as to prevent magnetic saturation in the common portion.

13. the controller simultaneously conducts and cuts off the current in the first primary coil and simultaneously conducts and cuts off the current in the second primary coil, The ignition system according to claim 10, wherein the current conduction and interruption of the first primary coil and the current conduction and interruption of the second primary coil are alternately repeated one or more times.

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