JP4993214B2 - Ignition device for vehicle - Google Patents

Description

The present invention relates to an igniter built in an ignition device for a vehicle engine and an overheat protection circuit for the igniter.

  The overheat protection circuit of the igniter built in the ignition device of the vehicle prevents the power element that energizes and shuts off the primary current flowing through the primary coil of the ignition device from overheating and destroying due to abnormal primary current. There is a thermal method. In the thermal method, the temperature of the power element is monitored by a temperature-sensitive element built in the power element, and when the preset temperature is reached, the gate signal of the power element is forcibly turned off to cut off the energization of the primary coil (hereinafter, referred to as “thermal element”). This is called thermal shut-off). This prevents the power element from being overheated to a predetermined temperature or being destroyed.

  FIG. 6 is a block diagram of the main part of a conventional igniter thermal overheat protection circuit. FIG. 7 is a time chart of the thermal shut-off operation of the overheat protection circuit of FIG.

  As shown in FIG. 6, the power element unit 102 includes a temperature-sensitive element 122 that detects the temperature of the power element 121. The control IC unit 103 includes an overheat detection circuit 131 and a gate voltage cutoff circuit 133 that control the gate voltage of the power element 121 based on the temperature data sent from the temperature sensing element 122. The power element unit 102 and the control IC unit 103 are configured separately.

  In FIG. 7, the horizontal axis is a time axis, and the vertical axis (A) is a power element drive signal that controls the ignition coil, and (B) the primary current is primary and current controlled by the power element drive signal. This is the primary current flowing through the coil. (C) The temperature-sensitive element temperature signal output represents the state in the power element unit 102 with the temperature signal output from the temperature-sensitive element 122. (D) Temperature sensor temperature signal input represents the state of the temperature signal when input to the overheat detection circuit 131. (E) The determination output is an output of the overheat detection circuit 131 and is generated based on the temperature sensitive element temperature signal input of (D). (F) The power element gate control signal is an output of the gate voltage cut-off circuit 133, and when it is Hi, the power element 121 is turned on, and the primary current is energized. When the power element gate control signal is Lo, the power element 121 is turned off and the primary current is cut off.

  Here, when the control IC unit and the power element unit are configured separately, noise is added to the temperature signal transmitted from the temperature sensing element 122 to the control IC unit 103 when the primary current is interrupted by the power element drive signal. Sometimes. In FIG. 7, n1 and n2 of the temperature-sensitive element temperature signal input are fluctuations of the temperature signal due to the noise. Since the fluctuations n1 and n2 due to the noise exceed the threshold level (Vref), the overheat detection circuit 131 erroneously determines that the power element 121 is abnormal (overheat), and outputs the determination output of (E) as Hi ( The output as the overheat determination output) is sent to the gate voltage cutoff circuit 133. The gate voltage cut-off circuit 133 stops energization of the power element 121 via the drive circuit 134 based on the overheat determination of the determination output Hi (corresponding to n1) (position t1 in FIG. 7). That is, as shown in the temperature-sensitive element temperature signal output of (C), the thermal shut-off for cutting off the primary current flowing through the primary coil is started even though the power element 121 is not overheated. When the thermal shut-off cancellation condition is configured by a power-on reset logic, this primary current interruption state continues until the ignition device power is turned off (until t2 in FIG. 7). That is, during the period when the primary current is cut off and the ignition device is not operating, the vehicle user is keyed off as shown by the solid line in the primary current of (B) (the dotted line indicates the case where the primary current is energized). (Until the period of t1-t2). Then, at t3 in FIG. 7, the key shut-on releases the thermal shut-off, the thermal shut-off related circuits are in the initial state, and the ignition operation of the ignition device is restarted.

  As described above, the conventional overheat protection circuit of the igniter shuts down the ignition device by shutting down the primary current even though the power element is not overheated due to malfunction due to noise on the temperature signal of the temperature sensing element. Moreover, there is a problem that the operation stop of the ignition device is not released until the ignition device is turned off.

  The present invention has been made in view of the above problems. Therefore, in the igniter in which the power element unit and the control IC unit are configured separately, and the release condition of the thermal shut-off of the overheat protection circuit is configured by the power-on reset logic, the power element when the primary current is interrupted There is a power element overheat protection circuit that prevents malfunction caused by thermal shut-off operation even though the power element is lower than the set temperature due to noise induced by the temperature signal of the temperature sensing element built in the unit. The object is to provide an ignition device for a vehicle.

(1) In order to solve the above-described problems, a vehicle ignition device according to the present invention includes a power element for energizing and controlling a primary current flowing through a primary coil of an ignition coil, a built-in power element, and A power sensing element that includes a temperature sensing element for detecting temperature;
A control IC unit provided separately from the power element unit and instructing energization and shut-off operation of the power element;
Wire bonding for transmitting instructions of the energization and shut-off operations from the control IC unit to the power element unit, and wire bonding for transmitting a temperature signal detected by the temperature sensing element to the control IC unit from the power element unit. A plurality of wire bondings that electrically connect the control IC unit and the power element unit,
In an ignition device for a vehicle including an igniter having the control IC unit, the power element unit, and a mold resin that seals the plurality of wire bondings, the control IC unit includes the control IC unit when the power element is overheated. A gate voltage cutoff circuit for forcibly turning off the gate signal of the power element to stop the primary current, and further, the power due to noise induced by the temperature signal output by the temperature sensing element when the primary current is interrupted A malfunction prevention circuit for preventing the thermal shutoff operation of the element is provided ,
The malfunction prevention circuit receives the temperature signal output from the temperature sensing element, and an overheat detection unit that performs an overheat determination of the power element based on the temperature signal outputs a determination that is input to the malfunction prevention circuit. A latch circuit that latches the output and sends the determination output to the gate voltage cutoff circuit;
The latch circuit outputs an overheat determination output indicating that the power element is overheated. When the power element drive signal supplied from the ECU to the ignition device is energized, the latch circuit outputs the overheat determination output. When the determination output is the overheat determination output and the power element drive signal is cut off, the overheat determination output is not latched .

  That is, in an igniter in which a power element unit incorporating a temperature sensing element and a control IC part for controlling the power element are formed separately, noise is added to the temperature signal sent from the temperature sensing element to the control IC part, The overheat detection circuit provided in the control IC unit erroneously determines that the temperature of the power element is overheated even though the detected temperature of the power element is smaller than the set value. As a result, in the conventional ignition device configuration, the power element performs a thermal shut-off operation. Further, this thermal shut-off continues until the ignition device is keyed off.

  The ignition device of the present invention prevents the malfunction of the power element performing a thermal shut-off operation due to the noise induced by the temperature signal, and ensures that the thermal shut-off is performed only when the power element is overheated. It is. In the present invention, a malfunction prevention circuit for preventing the primary current of the power element from being interrupted based on an erroneous determination result due to noise is provided as an input method for the gate voltage cutoff circuit.

  With this configuration, the malfunction prevention circuit eliminates sending the control signal based on the erroneous determination due to the noise to the gate voltage cutoff circuit, and the control signal is only sent to the gate voltage cutoff circuit when the power element is truly overheated. To activate the gate voltage cutoff circuit. That is, the power element is thermally shut off by noise induced by the temperature signal, preventing the ignition operation from being stopped unnecessarily for a long time, and if the power element is overheated, the primary current can be cut off reliably. it can.

  Note that the power element unit and the control IC unit of the present invention are formed separately, as shown in FIGS. 1B and 2, the power element unit 2 and the control IC unit 3. Means a state of being formed on different metal frames and on different substrates. Therefore, exchange of signals between the power element unit 2 and the control IC unit 3 is performed through wire bonding.

  The reason why noise is added to the temperature signal that has been elucidated by the present inventor is as follows. In the cross-sectional view of FIG. 2, the power element unit 2 and the control IC unit 3 are fixed to separate metal frames 51 and 52, respectively. The power element unit 2 and the control IC unit 3 are connected by wire bonding 41, 42, 43. These wire bondings include a transmission path for transmitting the temperature signal of the temperature sensitive element 22 (see FIG. 3) from the power element unit 2 to the control IC unit 3. Further, the power element unit 2, the control IC unit 3, and the metal frames 51 and 52 are sealed with the mold resin 4 together with the wire bondings 41, 42, and 43. Therefore, the wire bondings 41, 42, 43 and the metal frame 51 form a kind of capacitor with the mold resin 4 sandwiched therebetween. Here, the metal frame 51 is a collector of the power element 21 (see FIG. 3). Therefore, a sudden voltage change in the collector when the primary current is interrupted causes noise in wire bonding, which is a temperature signal path. Then, noise is applied to the temperature signal passing through the wire bonding from the power element unit 2 to the control IC unit 3.

The malfunction prevention circuit receives the temperature signal output from the temperature sensing element, and an overheat detection unit that performs an overheat determination of the power element based on the temperature signal outputs and inputs the temperature signal to the malfunction prevention circuit. A latch circuit that latches the determination output and sends the determination output to the gate voltage cut-off circuit. The latch circuit is an overheat determination output indicating that the input of the determination output indicates overheating of the power element. Yes, when the power element drive signal supplied from the ECU to the ignition device is energized, the overheat determination output is latched, the determination output is the overheat determination output, and the power element drive signal is When it is shut off, the overheat determination output is not latched. According to this configuration, even if the noise induced in the temperature signal exceeds the overheat determination threshold level, the overheat detection unit erroneously determines that the power element is overheated and outputs the overheat determination output (Hi). Even if it is sent, the overheat determination output (Hi) is not latched when the power element drive signal is cut off (Lo) in the latch circuit at the next stage, so the latch circuit output becomes Lo output. Therefore, the primary current of the primary coil is not cut off by turning off the gate terminal of the power element. Thereby, the thermal shut-off malfunction of the power element due to the noise can be prevented.

  On the other hand, the overheat detection unit determines that the power element is overheated, the overheat determination output (Hi) is input to the latch circuit, and the power element drive signal input to the latch circuit at the same time is energization (Hi). When this happens, the latch circuit latches the input overheat determination output and sends out the overheat determination output (Hi). The overheat determination output (Hi) output from the latch circuit normally performs a thermal shut-off operation that shuts off the primary current of the primary coil by turning off the gate terminal of the power element via the gate voltage cutoff circuit (see FIG. 3).

  Further, when the overheat detection unit determines that the power element is not overheated and the Lo output is input as the determination output to the latch circuit, even if the power element drive signal is energized (Hi) or cut off ( Even in the case of Lo), since the latch circuit sends out the Lo output, the power element does not cut off the primary current of the primary coil.

  According to the present invention, in the igniter in which the power element and the control IC unit are configured separately and the thermal shut-off cancellation condition is configured by the power-on reset logic, the off-period of the primary current of the ignition coil drive signal Due to the noise induced in the temperature signal of the temperature sensing element built into the power element, the thermal shut-off operation is set even though the temperature of the power element is lower than the set temperature, and the unnecessary thermal shut-off is prolonged. It is possible to provide a vehicle ignition device including a power element overheat protection circuit that is prevented from being continued.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1A is a perspective view showing an appearance of an igniter 1 to which the present embodiment is applied. FIG. 1B is a plan view showing the internal configuration of the igniter 1 of FIG. 1A, and shows a state where the mold resin 4 is removed. FIG. 2 is a cross-sectional view taken along the line II of FIG. However, FIG. 2 shows a state sealed with mold resin for convenience of explanation. FIG. 3 is a block diagram (equivalent circuit) showing the ignition device of the present embodiment.

  The igniter 1 constitutes a part of the ignition device for a vehicle according to the present invention, and includes a power element unit for energizing and interrupting a primary current of the ignition coil, and a control IC unit for controlling the power element. The igniter 1 of the present embodiment includes a power element unit 2, a control IC unit 3, and metal frames 51 to 56, as shown in FIGS. The power element unit 2 is formed on the metal frame 51, and the control IC unit 3 is formed on the metal frame 52. The metal frame 51 and the metal frame 52 are not electrically connected, and the power element unit 2 and the control IC unit 3 are formed separately. The power element unit 2 and the control IC unit 3 are electrically connected by wire bonding 41, 42, 43. In these wire bondings 41 to 43, a temperature sensing diode (corresponding to the temperature sensing element of the present invention) for detecting the temperature of the IGBT (insulated gate bipolar transistor: corresponding to the power element of the present invention) of the power element unit 2 is included. Wire bonding as a transmission path for transmitting the temperature signal from the power element unit 2 to the control IC unit 3 is also included. Further, on the metal frame 51 and the metal frame 56, other components 5a, 5b, and 5c constituting the igniter are formed. The power element unit 2, the control IC unit 3, the wire bondings 41 to 43, and the other component parts 5a to 5c configured as described above are sealed with the mold resin 4 together with the metal frames 51 to 56, and FIG. It has the shape shown in The metal frame 51 is an IGBT collector terminal.

  FIG. 3 is a block diagram showing an equivalent circuit of the ignition device of the present embodiment including the power element unit 2 of the igniter 1, the control IC unit 3, the primary coil driven by the igniter 1, the secondary coil, and the like arranged as described above. It is a diamond. As shown in FIG. 3, the ignition device includes an igniter 1 and an ignition coil 60. The igniter 1 includes a power element unit 2, a control IC unit 3, and a current detection resistor 23. The power element unit 2 includes an IGBT 21 that controls energization and cutoff of the primary current of the primary coil, and a temperature-sensitive diode 22 that detects the temperature of the IGBT 21.

  The control IC unit 3 receives a temperature signal from the temperature sensing diode 22 to determine whether the IGBT 21 is overheated or non-overheated, and outputs an overheat detection circuit 31 and an overheat detection circuit 31 that output the result as a determination output. The latch circuit 32 for determining whether or not to latch the determination output outputted from the gate, and the gate voltage cutoff circuit 33 for instructing the thermal shut-off operation for turning off the gate voltage of the IGBT 21 based on the determination output input from the latch circuit 32 The gate voltage of the IGBT 21 is turned on. A drive circuit 34 for controlling off, a current limiting circuit 35 for controlling the gate voltage to limit the primary current to a set value, and an igniter 1 circuit for an input signal from the outside provided in an input stage of an IGBT drive signal input from the ECU An input circuit 36 for the purpose of protection, a constant voltage circuit 38 for controlling the DC voltage from the battery power source (+ B) to a constant voltage, and a diagnosis signal generation circuit 37 for sending a diagnosis signal to the ECU. .

  The operation of the latch circuit 32 of the present invention will be described with reference to FIGS.

  As shown in FIG. 2, the wire bondings 41 to 43 and the metal frame 51 are a kind of capacitor filled with a mold resin 4 as an insulator. Since the dielectric constant of the mold resin 4 is high, the energy stored between the wire bonding and the metal frame is higher than that of air (vacuum) (the stray capacitance is increased). Here, since the metal frame 51 is a collector of the IGBT 21, a large current of about 10 A at the maximum flows. Therefore, noise is generated in the temperature signal, which is an electrical signal for transmitting wire bonding, due to a rapid change in the collector voltage when the collector current of the IGBT 21 is cut off, and the voltage value of the temperature signal varies.

  The operation of the ignition device of this embodiment based on this phenomenon will be described with reference to FIG. FIG. 4 is a waveform diagram of the primary current flowing through the primary coil of the ignition device of the present embodiment, the secondary current flowing through the secondary coil, and the temperature-sensitive diode output. In FIG. 4, the IGBT drive signal shown in (1) is a signal instructing energization / cutoff control of the IGBT sent from the ECU to the ignition device, and when the signal is Hi, the IGBT is turned on and a primary current flows through the primary coil. When Lo, the IGBT is turned off and the primary current is cut off. (2) represents the magnitude of the primary current at that time. (3) to (6) expands the horizontal axis (time axis) when the primary current is interrupted, temperature sensitive diode output (Vf), primary current flowing through the primary coil, voltage generated in the secondary coil, overheat detection The determination output which the circuit 31 outputs is represented. The temperature-sensitive diode output (Vf) in (3) indicates a state when the output sent from the temperature-sensitive diode 22 reaches the overheat detection circuit 31 (see FIG. 3) via wire bonding. . Here, the interval (horizontal axis) between Hi level and Hi level in (1) is about 10 msec, while the horizontal axis in (3) to (6) is 5 μsec / div.

  When the primary current is cut off and the primary current decreases rapidly as shown in (4), the temperature sensitive diode output (Vf) in (3) has A, B, and C in wire bonding for the above reasons. Noise as shown. Since this noise part exceeds the overheat determination threshold level (Vref), the overheat detection circuit 31 (see FIG. 3) to which the temperature sensitive diode output (Vf) is input outputs the determination output shown in (6). To do. That is, the Hi portion of the determination output is an overheat determination output (Hi) that the IGBT is overheated in the noise A, B, and C portions even though the IGBT is not overheated.

  In the present embodiment, a latch circuit is further provided as a malfunction prevention circuit for this determination output. The effect of the latch circuit of the present invention will be described based on the block diagram of FIG. 3 and the waveform diagram of FIG. In FIG. 5, the IGBT drive signal in (a) corresponds to (1) in FIG. The primary current (b) corresponds to (2) in FIG. The temperature-sensitive diode output (Vf) in (c) corresponds to (3) in FIG. The determination output in (d) corresponds to (6) in FIG. The latch circuit output of (e) is the output of the latch circuit 32, and Hi represents the overheat determination of the IGBT and Lo represents the non-overheat determination of the IGBT. The gate output of (f) is the output of the gate voltage cut-off circuit 33. When it is Hi, the IGBT can be energized, and when it is Lo, the IGBT is turned off.

  In the waveform of the temperature sensitive diode output (Vf) in (c), P, Q, R, and S are noises that are caused by the temperature sensitive diode output when the primary current is interrupted. And in the position of the noise of P, Q, R, and S, all the temperature-sensitive diode outputs exceed the overheat detection determination threshold level (Vref). In addition to the P, Q, R, and S noises, the temperature sensitive diode output (Vf) decreases from the position of Z1 (dashed line) beyond the overheat detection determination threshold level (Vref) ( Z1-Z2 section). The decrease in the temperature sensitive diode output (Vf) in the section of Z1-Z2 is due to overheating of the IGBT 21.

  Therefore, the determination output of the overheat detection circuit 31 (see FIG. 3) is Hi, which represents overheating at positions corresponding to the P, Q, and Z1-Z2 sections (including R and S) as shown in FIG. 5 (d). Become. Therefore, when the gate voltage of the IGBT is controlled based on this judgment output as in the prior art, the primary current is cut off by turning off the gate voltage of the IGBT at the position P even though the IGBT is not overheated. In addition, the primary current interruption state continues until the ignition device is turned off.

  On the other hand, in the present invention, as shown in FIG. 3, a latch circuit 32 is provided for the determination output of the overheat detection circuit 31, and the output of the latch circuit 32 is input to the gate voltage cutoff circuit 33. The latch circuit 32 sends a Hi output (IGBT gate voltage off command) only when the determination output input from the overheat detection circuit 31 is Hi (overheat determination output) and the IGBT drive signal is Hi (energization). When the IGBT drive signal is Lo (shutoff), the Lo output is sent to the gate voltage shutoff circuit 33 even if the judgment output from the overheat detection circuit 31 is Hi (overheat judgment output). At the positions X and Y in FIG. 5, the latch circuit output of (e) is Lo (dotted line portion). That is, it is possible to prevent a malfunction in which the gate voltage of the IGBT is turned off due to P and Q noise on the temperature signal of the temperature sensitive diode in the bonding wire.

  Then, at the position of Z1 where the IGBT drive signal of (a) is Hi and the determination output of (d) is Hi (overheat determination output) due to overheating of the IGBT, the latch circuit output of (e) is Hi ( Overheating). Therefore, in response to Hi (overheating) of the latch circuit output, the gate output of (f) becomes Lo, and a thermal shut-off that interrupts the primary current is set (lock prevention operation). As a result, the present invention prevents malfunctions that shut off the primary current by turning off the gate voltage of the IGBT even though the IGBT is not overheated due to noise on the temperature signal of the temperature sensitive diode in the bonding wire. At the same time, it is possible to accurately detect the overheating of the IGBT and operate the overheat protection circuit accurately. Further, it is possible to avoid stopping the primary current unnecessarily long due to a malfunction.

(A) is a perspective view which shows the external appearance of the igniter 1 with which embodiment of this invention is applied. FIG. 2B is a plan view showing the inside of the igniter 1. It is II sectional drawing of FIG.1 (b). It is a block diagram (equivalent circuit) of the ignition device of an embodiment. It is a wave form diagram of a latch output of a primary current of an ignition device of an embodiment, a secondary voltage, a temperature sensing diode, and a latch circuit. It is a waveform diagram of the primary output of the ignition device of the embodiment, the temperature sensitive diode, and the latch output of the latch circuit. It is a block diagram of the main part of the thermal type overheat protection circuit in the conventional ignition device. 7 is a time chart of a thermal shut-off operation of the overheat protection circuit of FIG. 6.

Explanation of symbols

1: Igniter
2, 102: Power element part 21, 121: IGBT (power element)
22, 122: Temperature-sensitive diode 23, 123: Current detection resistor
3, 103: Control IC section 31, 131: Overheat detection circuit 32: Malfunction prevention circuit (latch circuit) 33, 133: Gate voltage cutoff circuit
34, 134: drive circuit 35, 135: current limiting circuit 36: input circuit 37: diagnostic signal generation circuit 38: constant voltage circuit 4: mold resin 41, 42, 43: wire bonding 51, 52, 53, 54, 55, 56: Metal frame 60: Ignition coil

Claims (1)

A power element unit including a power element for energizing and controlling the primary current flowing through the primary coil of the ignition coil, and a temperature sensing element built in the power element for detecting the temperature of the power element;
A control IC unit provided separately from the power element unit and instructing energization and shut-off operation of the power element;
Wire bonding for transmitting instructions of the energization and shut-off operations from the control IC unit to the power element unit, and wire bonding for transmitting a temperature signal detected by the temperature sensing element to the control IC unit from the power element unit. A plurality of wire bondings that electrically connect the control IC unit and the power element unit,
In an ignition device for a vehicle including an igniter having the control IC unit, the power element unit, and a mold resin that seals the plurality of wire bondings, the control IC unit includes the control IC unit when the power element is overheated. A gate voltage cutoff circuit for forcibly turning off the gate signal of the power element to stop the primary current, and further, the power due to noise induced by the temperature signal output by the temperature sensing element when the primary current is interrupted A malfunction prevention circuit for preventing the thermal shutoff operation of the element is provided ,
The malfunction prevention circuit receives the temperature signal output from the temperature sensing element, and an overheat detection unit that performs an overheat determination of the power element based on the temperature signal outputs a determination that is input to the malfunction prevention circuit. A latch circuit that latches the output and sends the determination output to the gate voltage cutoff circuit;
The latch circuit outputs an overheat determination output indicating that the power element is overheated. When the power element drive signal supplied from the ECU to the ignition device is energized, the latch circuit outputs the overheat determination output. An ignition device for a vehicle , wherein latching is performed, and when the determination output is the overheat determination output and the power element drive signal is cut off, the overheat determination output is not latched .

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