JP6362375B2 - Ignition coil for internal combustion engines - Google Patents

Description

  The present invention relates to an ignition coil for an internal combustion engine, and more particularly to a small and high performance ignition coil capable of multiple ignition.

  In recent internal combustion engines, lean combustion control that controls the air-fuel ratio lean is employed for the purpose of improving fuel efficiency. In this case, since the ignition characteristic of the air-fuel mixture deteriorates as much as the fuel is lean, a multiple ignition system in which the spark plug is driven repeatedly as many times as necessary in one ignition cycle may be employed. Therefore, the applicant has also proposed an internal combustion engine ignition system that realizes a multiple ignition operation by complementary ON / OFF control of the first and second ignition transformers (Patent Document 1).

  FIG. 4 illustrates this circuit. In order to quickly charge the primary coil with the required ignition energy, the battery voltage Vb is boosted to ensure a power supply voltage Vout of 40 to 50 V. By performing ON / OFF control of the second switching elements IGTa and IGTb complementarily a predetermined number of times, the ignition current of the spark plug is continued for a predetermined time to achieve a desired ignition performance.

  In addition, this type of ignition coil generally includes a first connector having a signal terminal for receiving a first ignition signal Siga, a power supply terminal for receiving a boosted power supply voltage Vout, and a ground terminal GND. In addition to the one connector, a second connector having a signal terminal for receiving the second ignition signal Sigb, a power supply terminal for receiving the boosted power supply voltage Vout, and a ground terminal GND is provided (for example, see Patent Document 2). ).

JP2012-167665A JP 2013-243239 A

  In the circuit configuration described in the cited document 1, since the secondary coils of the first and second ignition transformers are connected in parallel, a closed circuit is formed by the secondary coils of the two ignition transformers. Therefore, it is necessary to dispose a diode that restricts the secondary current of each ignition transformer from flowing in the reverse discharge direction so that a short-circuit current does not flow in the closed circuit. As the diode, it is necessary to select an element that can withstand this, considering that the induced voltage during ignition discharge of the secondary coil is several tens of kV and the ignition discharge current is instantaneously large. There is.

  By the way, as a recent market demand, it is desired to improve the performance of an ignition coil without increasing the manufacturing cost, to ensure normal operation during lean combustion, and to reduce the size of the ignition coil. Therefore, the use of the highest rank diode having a high current capacity and excellent withstand voltage performance is contrary to the above requirement. On the other hand, if a plurality of diodes are connected in series and arranged below the ignition transformer (see Patent Document 2), an insulation distance exceeding the outer diameter of the diode is required to ensure insulation with the ignition transformer. The case increases in size in the height direction.

  The present invention has been made in view of the above problems, and an object thereof is to provide a small and high-performance ignition coil without increasing the manufacturing cost.

To achieve the above object, the present invention provides a first ignition transformer in which a primary coil and a secondary coil are electromagnetically coupled, a first switching element that controls ON / OFF of a primary current of the first ignition transformer, a primary A case main body housing a second ignition transformer in which a coil and a secondary coil are electromagnetically coupled, and a second switching element for controlling ON / OFF of a primary current of the second ignition transformer, and an ignition plug from the case main body An ignition coil configured to protrude toward the first , the first switching element and the second switching element at the same ignition timing, the first and second ignition having different phases after performing the oN operation continues for a predetermined time upon receiving a pulse, is configured to perform oN / OFF operation required number complementary, secondary current of the first ignition transformer flows in opposite discharge direction A plurality of first regulating element for regulating the No matter, the second and the plurality of second regulating element ignition transformer secondary current is regulated so as not to flow in the reverse discharge direction, leading to an ignition plug of said case axis It arrange | positions inside a part, It is characterized by the above-mentioned.

  Here, the first and second regulating elements typically mean a diode, but an electronic element that functions in the same manner as the diode is sufficient.

  Preferably, each of the first restriction element and the second restriction element is an electronic element in which a discharge current is allowed from the first terminal toward the second terminal, and each of the second terminals is the first and second terminals. While being connected to the secondary coil of the second ignition transformer, the first restriction element and the first terminal of the second restriction element are connected to each other to supply a discharge voltage to the spark plug.

  Further, the first restriction element and the second restriction element are each typically configured by connecting a plurality of elements in series, or each of the plurality of elements being connected in parallel. .

In the case body, a first signal terminal to which a first ignition signal for driving the first switching element is supplied, a second signal terminal to which a second ignition signal for driving the second switching element is supplied, A single connector is disposed to receive a battery terminal supplied with a DC voltage of a battery mounted on a movable body driven by an internal combustion engine and a power supply terminal supplied with a power supply voltage obtained by boosting the battery voltage. It is suitable.

  Also, a regulation main body portion that holds the first regulation element and the second regulation element in a fixed manner, a conductor distal end portion that is disposed on the distal end side of the regulation main body portion and can elastically contact the spark plug, and a proximal end of the regulation main body portion An assembly that is integrally formed in a substantially T-shape as a whole is pre-manufactured with a conductor base end that is disposed on the side and contacts the high-voltage side terminals of the two secondary coils. It is preferable that the base end portion is disposed on the case main body portion while the other part of the assembly is disposed on the case shaft portion so as to be in a completed state.

In the present invention , the first switching element and the second switching element receive the first and second ignition pulses having different phases at the same ignition timing and perform an ON operation that continues for a predetermined time, and then the ON / OFF operation. In a configuration that performs the required number of times in a complementary manner, a plurality of first restricting elements and a plurality of second restricting elements are arranged inside the case shaft portion leading to one spark plug, so that the highest level diode Since the case shaft portion is effectively used, a small and high performance ignition coil can be realized without increasing the manufacturing cost.

1 is a diagram illustrating a circuit configuration of an ignition coil according to an embodiment. The internal structure of the ignition coil which concerns on an Example is illustrated. The internal structure of the ignition coil which concerns on a modification is illustrated. 1 is a view showing an ignition coil according to the prior art.

  Hereinafter, the present invention will be described in more detail based on examples. FIG. 1A is a block diagram showing a circuit configuration of the ignition coil CL, which includes two igniter modules IGa and IGb, two ignition transformers Ta and Tb, and a diode module Di. ing. Here, the ignition transformers Ta and Tb are configured such that the primary coil L1 and the secondary coil L2 are electromagnetically coupled via the central iron core Co and the outer iron core Co '.

  During ignition discharge in which the primary current of the primary coil L1 is interrupted, an ignition voltage of several tens of kV is generated between the plus terminal (+) and the minus terminal (−) of the secondary coil L2. The plus terminal (+) of the coil L2 is connected to the power line Vcc of the primary coil L1 in any of the ignition transformers Ta and Tb. Therefore, the two secondary coils L2 and L2 form a closed circuit via the power supply line Vcc. However, since the diode module Di is disposed, no short-circuit current flows in any direction.

  The diode module Di is roughly divided into a plurality of diodes Da for the ignition transformer Ta and a plurality of diodes Db for the ignition transformer Tb. In the illustrated example, the three diodes Da and the three diodes Db are reversed as a whole. Connected in the direction. A connection point (anode terminal) between the three diodes Da and the three diodes Db is connected to the high-voltage output terminal To.

  The connection connector TR of the ignition coil CL includes a battery terminal T1 that receives a battery voltage VB of about 12V from a battery mounted on the automobile, and a first signal that receives a first ignition pulse SGa from an ECU (Engine Control Unit). A terminal T2, a power supply terminal T3 that receives the power supply voltage Vcc boosted to about 43V by the DC-DC converter COV, a second signal terminal T4 that receives the second ignition pulse SGb from the ECU, and a ground that shares the ground line GND And a terminal T5. The high voltage outputs of the ignition transformers Ta and Tb are output to the high voltage output terminal To via the diode module Di and supplied to the ignition plug PG.

  Each igniter module IGa and IGb limits switching current by detecting switching elements Qa and Qb such as IGBT (Insulated Gate Bipolar Transistor) and overcurrent or overheating state when the switching elements Qa and Qb are turned on. Control units CTLa and CTLb are built in. Each of the control units CTLa and CTLb functions by using the battery voltage VB as a power supply voltage, and performs appropriate logical operations based on the ignition pulses SGa and SGb received from the EUC, thereby causing the gate terminals of the switching elements Qa and Qb. Is controlling.

  As illustrated, the emitter terminals of the switching elements Qa and Qb are connected to the ground line GND, and the collector terminal is connected to the primary coil L1. The switching elements Qa and Qb are configured to be turned on by receiving an H level control voltage at their gate terminals, so that a charging current flows through the primary coil L1.

  The control voltage supplied to the gate terminals of the switching elements Qa and Qb has basically the same logic level as the ignition pulses SGa and SGb. In this embodiment, multiple ignition operations are realized by receiving ignition pulses SGa and SGb as shown in FIG. 1D from the ECU in each ignition cycle.

  Specifically, when the ignition pulses SGa and SGb are at the H level, the primary current flows through the primary coil L1, and then the secondary coil L2 at the moment when the ignition pulses SGa and SGb transition to the L level. An ignition voltage of several tens of kV is induced in. Here, in the ignition cycle, the ignition pulse SGa and the ignition pulse SGb are provided with an appropriate phase delay, and the logic levels of the ignition pulse SGa and the ignition pulse SGb are inverted except for the first H level period.

  Therefore, the switching elements Qa and Qb repeat ON / OFF operations in a complementary manner except for the first H level period of the ignition pulses SGa and SGb. Therefore, in the ignition coil CL, a high voltage is induced in a complementary manner in the two secondary coils L2 and L2 based on the magnetic energy accumulated in the first H level period of the ignition pulses SGa and SGb.

  Moreover, since the power supply voltage Vcc boosted to about 43 V is supplied to the primary coil L1, the current of the primary coil L1 quickly reaches the target value level, and the switching elements Qa and Qb are turned on / off at high speed. Even with the OFF control, a high voltage of a level required from the internal combustion engine can be repeatedly generated. Therefore, the spark plug PG realizes multiple ignition discharges (see t1, t2,..., Tn + 1 in FIG. 1 (d)), and an ignition error occurs even in a lean air-fuel mixture. Does not occur.

  FIG. 2 is a schematic diagram (FIGS. 2A to 2G) of the ignition coil CL and drawings (FIGS. 2H to 2J) illustrating the diode module Di.

  As shown in FIG. 2E, the ignition coil CL has a large case main body 1 formed in a box shape and a case shaft 2 protruding from the case main body 1 toward the ignition plug PG. Separated. A substantially T-shaped diode module Di is accommodated from the bottom of the case body 1 to the case shaft 2. In addition, the case axial part 2 has the protrusion length of about 90-100 mm, for example.

  More specifically, the case body 1 is as shown in FIG. 2 (d), and on its side, a battery terminal T1, a first signal terminal T2, a power supply terminal T3, and a second signal terminal T4 are provided. The connection connector TR having the ground terminal T5 is fixed. In this embodiment, although the ignition transformers Ta and Tb and two circuits related to the ignition transformers Ta and Tb are provided, the connection connector TR is single and shared, so (1) the number of terminals And (2) reduction of wiring cables, and (3) reduction of the volume of the connector part.

  As shown in the plan view of FIG. 2A and the AA cross-sectional view of FIG. 2B, the case main body 1 contains the primary coil L1 containing the central iron core Co and the primary coil L1. Two sets of secondary coils L2 are accommodated to form ignition transformers Ta and Tb. Two annular outer cores Co 'are arranged so as to go around the outer sides of the two sets of secondary coils L2, L2. In the arrangement state, the central iron core Co and the outer iron core Co ′ are in contact with each other, and a magnetic path without leakage magnetic flux is formed.

  Since the igniter modules IGa and IGb are arranged above the ignition transformers Ta and Tb configured as described above, the case main body 1 is reduced in size in the plane direction. However, it is not limited at all. For example, two igniter modules IGa and IGb may be provided upright in the vicinity of the connection connector TR. In this case, the case main body 1 can be downsized in the height direction.

  As shown in FIG. 2H, the diode module Di includes an element main body 10 that extends in the axial direction of the case shaft 2, and a base end 11 that extends perpendicular to the axial direction at the base end of the element main body 10. And is formed in a substantially T-shape as a whole. The base end portion 11 has connection terminals Dt1 and Dt2 respectively connected to the minus terminal (−) of the secondary coil L2 of the ignition transformer Ta and the minus terminal (−) of the secondary coil L2 of the ignition transformer Tb. Is provided.

  On the other hand, in the element main body 10, three diodes Da are connected in series and connected to the connection terminal Dt3, and another three diodes Db are connected in series and connected to the connection terminal Dt3. An equivalent circuit of the diode module Di is as shown in FIG. For example, when a diode having a reverse breakdown voltage of about 15 kV is used, the reverse breakdown voltage of the three diodes as a whole is about 45 kV, and normal operation of the ignition circuit is ensured even if the ignition voltage and the power supply voltage Vcc are set higher. . That is, since the reverse voltage is distributed by a plurality of diodes, a desired reverse breakdown voltage can be ensured as the entire diode module Di without using an expensive diode having a high reverse breakdown voltage.

  As shown in FIG. 2 (h) and FIG. 2 (j), the connection terminal Dt3 is formed by bending a metal flat plate, has a predetermined elasticity, and is in contact with the high-voltage output terminal To. A noise prevention resistor may be arranged between the high voltage output terminal To and the connection terminal Dt3.

  In any case, in this embodiment, the diode module Di formed in a substantially T shape is manufactured in advance, and when the ignition coil CL is manufactured, the element main body 10 of the diode module Di is attached to the case shaft portion 2. Inserting and disposing the base end portion 11 of the diode module Di at the bottom of the case body 1 can simplify the assembly process of the ignition coil CL. Further, the conventional ignition coil has an advantage that the case shaft portion 2 in which only the conductor spring is disposed as a high-voltage output conduction path can be effectively used. That is, the conductor spring can be omitted and the dead space can be eliminated.

  In addition, since a sufficient insulation distance can be secured between the diodes Da and Db and the secondary coil L2, there is no need to provide an extra insulation distance at the bottom of the case body 1 and the height of the case body 1 is increased. It is possible to achieve downsizing.

  Incidentally, in the diode module Di of FIG. 2H, each of the three diodes Da ..., Db ... extends linearly in the axial direction, but there is no limitation. FIG. 3 is a diagram showing another diode module Di, which is suitably applied to an ignition coil having a protruding length of the case shaft portion 2 of about 50 to 60 mm. The equivalent circuit in this case is also as shown in FIG. 1B, and three diodes Da..., Db. Even in this circuit configuration, the reverse voltage is divided into three by the three diodes, so that the diode module Di as a whole can secure a desired reverse breakdown voltage without using an expensive diode having a high reverse breakdown voltage. it can.

  Incidentally, in the ignition circuit of the embodiment, not only the reverse breakdown voltage of the diodes Da and Db but also the ignition current may be a problem. For example, as shown in FIG. 1D, in the multiple ignition method, in one ignition cycle, the secondary current of the secondary coil L2 repeatedly becomes a large level and flows to the diodes Da and Db. Specifically, a large current flows through the diode Da at timings t1, t3,... Tn, and a large current flows through the diode Db at timings t2, t4,. An ignition current of a predetermined level or more continues in the spark plug PG.

  Therefore, when a large current at the time of transition of the ignition pulse becomes a problem, for example, it is preferable to adopt the circuit configuration of FIG. In this case, since the ignition current is distributed to the three diodes, a diode inferior to the absolute maximum rating of the forward current can be used. Note that this current distribution type circuit configuration can be applied not only to the diode module Di shown in FIG. 3E but also to the diode module Di shown in FIG.

  Although the embodiments of the present invention have been specifically described above, the specific description is not particularly intended to limit the present invention and can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 Case main-body part 2 Case axial part CL Ignition coil Da 1st control element Db 2nd control element Ta 1st ignition transformer Tb 2nd ignition transformer Qa 1st switching element Qb 2nd switching element

Claims (6)

A first ignition transformer in which the primary coil and the secondary coil are electromagnetically coupled, a first switching element for controlling ON / OFF of the primary current of the first ignition transformer, and a first coil in which the primary coil and the secondary coil are electromagnetically coupled. A case main body that houses the second ignition transformer and a second switching element that controls ON / OFF of the primary current of the second ignition transformer;
A case shaft that protrudes from the case body toward the ignition plug, and an ignition coil configured to have
The first switching element and the second switching element receive the first and second ignition pulses having different phases at the same ignition timing and perform an ON operation that continues for a predetermined time, and then complement the ON / OFF operation as many times as necessary. Configured to run automatically,
A plurality of restricting to a plurality of first regulating element a secondary current of the first ignition transformer to regulate so as not to flow in the reverse discharge direction, the secondary current of the second ignition transformer does not flow in the reverse discharge direction first An ignition coil for an internal combustion engine, wherein two restriction elements are arranged inside the case shaft portion that reaches one ignition plug . Each of the first regulating element and the second regulating element is an electronic element in which a discharge current is allowed from the first terminal toward the second terminal,
Each second terminal is connected to the secondary coil of the first and second ignition transformers, while the first terminals of the first restriction element and the second restriction element are connected to each other, and a discharge voltage is applied to the spark plug. The ignition coil according to claim 1, wherein the ignition coil is supplied.   The ignition coil according to claim 1, wherein each of the first restriction element and the second restriction element is configured by connecting a plurality of elements in series.   The ignition coil according to claim 1 or 2, wherein each of the first restriction element and the second restriction element is configured by connecting a plurality of elements in parallel. In the case body, a first signal terminal to which a first ignition signal for driving the first switching element is supplied, a second signal terminal to which a second ignition signal for driving the second switching element is supplied, A single connector is disposed to receive a battery terminal supplied with a DC voltage of a battery mounted on a movable body driven by an internal combustion engine and a power supply terminal supplied with a power supply voltage obtained by boosting the battery voltage. The ignition coil according to any one of claims 1 to 4.   A regulation main body that holds the first regulation element and the second regulation element in a fixed manner, a conductor distal end that is disposed on the distal end side of the regulation main body and elastically contacts the ignition plug, and a proximal end of the regulation main body An assembly that is arranged and configured integrally in a substantially T shape as a whole with a conductor base end portion that is disposed and contacts the high-voltage side terminals of the two secondary coils is manufactured in advance, and the conductor base end of this assembly The ignition coil according to any one of claims 1 to 5, wherein a portion is disposed on the case main body portion, and another portion of the assembly is disposed on the case shaft portion to be in a completed state.