JPS5847157A - Ignition circuit for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an ignition circuit reduced of power loss without increasing the number of parts, by connecting a switching element made of a combined field-effect transistor, to both the terminals of the primary winding of an ignition coil. CONSTITUTION:A combined element 31 manufactured by producing a P-region 33 in the collector layer 32 of an NPN transistor is provided. The electrode 34 of the P-layer 33 is connected to the emitter electrode of a main transistor Tr2 coupled between both the primary termainals A, C of an ignition coil 1. The electrode 35 of an N-layer 32 is connected to the base of the transistor Tr2. When the potential on the terminal A rises, a current flows from the collector electrode 36 of the combined element 31 to the base of the transistor Tr2through the N-layer 32 and the electrode 35 to turn on the transistor. When electric conduction is caused between the collector and base electrodes 36, 39 of the element 31 by applying a forward bias to the P-N juction between the base and emitter regions 37, 38 of the element through its base and emitter electrodes 39, 40, the transistor Tr2 is turned off to produce sparks on a spark plug 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an internal combustion engine in which a short-circuit current is passed through a transistor in the primary winding of an ignition coil, and a high voltage is induced in the secondary winding to cause 19 sparks to ignite in one spark plug. Regarding the ignition circuit.

Two commonly known circuits of this type are those shown in Figures 1 and 2. In Fig. 1, an alternating current voltage is induced in the primary side IHIll of the ignition coil 1, - in a permanent magnet that is attached to and rotates on a wheel 79 of the crankshaft of an internal combustion engine (not shown). When terminal A is in a positive state with respect to terminal CK, resistance Rtk
The main transistor 2 becomes conductive first because a Sumi current is supplied through the main transistor 2.

The voltage between terminals A and C is divided by the resistor holes, R, and applied to the base of the sub-transistor 3. When the potential of the terminal A and C rises to a predetermined value, the sub-transistor 3 Continuity. Then, the potential at point %B decreases and the main transistor 2 is interrupted, a large voltage is induced in the secondary winding 12 of the ignition coil l, a spark flies to the spark plug 4, and the internal combustion engine ignites. will be held.

In Fig. 2, a thyristor 5 is connected as a switching element in place of the sub-transistor 2 in Fig. 1111, and the voltage between the nine terminals A and C is divided by the resistor and is connected to the gate of the thyristor 5 and the voltage between the terminals A and C. Since it is applied as a forward bias, when the potential at the terminal rises to a predetermined value, the thyristor 4 becomes conductive (L4n), and the thyristor 2 is interrupted and the spark plug 4
Sparks fly.

In these cases, if the resistance value 1 is small, the base current of the main transistor 20 can be large, and even if the amplification factor of the transistor 2 is small, a large collector current can be obtained.
Resistance Rxt - It is desirable to make it small, but when the secondary transistor 2 or thyristor 5 conducts and the main transistor 2 is interrupted and the point A becomes high potential, the resistance R
Since a large amount of current flows through the sub-transistor 3 or the thyristor 5, it is necessary to increase the current capacity of the thyristor 5 for the transistor 3, which increases the price and increases the power loss. Therefore, the resistance R1tTo
It cannot be made smaller. Therefore, when the internal combustion engine rotates at low speed, the induced voltage and voltage are low and the current flowing through the main transistor 2 is small.
Spark energy decreases. On the other hand, it is also possible to use a main transistor with a large amplification factor, but this type of transistor usually has a low withstand voltage between the emitter and collector, and the electromotive force of the ninth and negative windings 11 [needs to be kept small]. Therefore, it is not a good idea to use a main transistor 2 with an amplification factor larger than a certain level.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks and to limit the current flowing when the switching element connected in parallel to the main transistor that conducts the short-circuit current of the primary winding of the ignition coil is conductive.

Purpose #i: A switching board consisting of three or more adjacent layers of alternately different conductivity types, with the first layer having another region of the same conductivity type as the second layer.

The first layer of the switching coil is connected to both ends of the primary winding of the ignition coil in parallel with the main transistor, and the first layer of the switching coil is connected to the pace of the main transistor so that when the voltage of the primary side IIkIli of the ignition coil is below a predetermined value, The main transistor is made conductive by the inflowing base current, and when it exceeds a predetermined value, the Hiro switching element is made conductive and the main transistor is cut off, and the voltage in the primary winding that occurs when the main transistor is cut off. This is achieved by applying a reverse bias depending on the magnitude of the switching element between the first layer of the switching element and another region within the first layer, thereby forming a 7-air layer extending within the first layer. be done. The present invention@0 embodiment will be explained using the following figures. In FIG. 3, a composite element 31 connected in place of the sub-transistor 3 of FIG. 1 forms a collector layer 32t and a CP region 33t of an NPN transistor, and corresponds to 7t%. A hollow electrode 34 provided on the two layers 33 is connected to the emitter electrode of the main transistor 2. On the other hand, an electrode 35 provided on the N layer 32 is connected to the base electrode of the main transistor 20. When the terminal A is in a positive state with respect to the terminal CK, the collector electrode 36 of the composite element 31 to the 8th layer 3
2. Current flows to the base of the main transistor 2 via the electrode 35', and the main transistor 2 becomes conductive.

As the potential of the terminal further increases, the voltage across the voltage divider resistor R increases, and the PNN junction between the pace region 37 and the emitter region 38 of the composite element 31 passes through the penis electrode 39 and the emitter electrode 40 to the forward I (The collector electrode 36 and the emitter electrode 39 are electrically connected. Therefore, the base current of the main transistor 20 disappears, and the main transistor 2 is interrupted.

At this time, a large voltage is generated on the primary side 11 of the ignition coil 1, and the secondary voltage is further increased to $112, causing a spark to fly to the spark plug 4. When the potential of terminal A further increases, 2
The reverse bias applied to the PN junction between the layer 33 and the 8th layer 32 also increases further, and the depletion layer that spreads from the 2nd layer 33 is affected by the 8
The carrier passageway in layer 32 is curtailed. Therefore, the current flowing through the composite element 31 is limited, and the power loss is suppressed to less than a few tenths of that in the case where there is no restriction. Specifically, the composite element 31 is configured as shown in FIG. 4. . An N+ layer is provided on the lower surface of the N-type silicon plate forming the N layer 321, and the electrode 35 is in ohmic contact with this layer. On the upper surface of the plate, a dish-shaped OP area 7, an N area 38, and a ring-shaped P area 33 are formed by selective diffusion treatment. Electrodes 34, 36, 38>! in each of these areas and in the 8 layers. Although not shown, the electrodes 40 and 40 are ohmically attached, and are protected by being covered with an oxide film, excluding the surface electrode portions of the silicon plate.

The magnitude of the current flowing from the electrode 36 is limited by the depletion layer formed around the annular P region 38 when a reverse bias voltage is applied thereto.

In FIG. 5, an element 51 which is a combination of the thyristor 50's 9 of FIG. 3 and a field effect transistor is connected. That is, in this composite element 51, a P emitter layer 52KN region 53 of the thyristor is formed,
It is connected to the other end of the series resistor R1 of the element 51. An electrode 55 provided on the P layer 52 is connected to the base ta of the main transistor 20. In this case, even if the resistance R1 is zero, if the terminal is in a positive state with respect to the terminal CK.

resistor R1 and anode electrode 56 of element 51. P layer 52
When the base voltage current of the main transistor 2 flows through the electrode 55t and the main transistor 2Fi conductor A, the voltage on the terminal A side rises, and the voltage across the voltage resistor island rises, the P emitter layer 52. N base layer 57. P<-s layer 58
．． P base layer 5 of thyristor consisting of N emitter layer 59
8 and the N emitter layer 590 is the gate electrode 60.
．． It is forward biased through the cathode electrode 61, and the composite element 51 (D thyristor conducts) to act as the main transistor.

+ Refusal, resulting in ignition. At this time, a resistor R is connected to the high potential generated on the terminal A side to connect the composite element 5.
From the anode electrode 56 to the cathode electrode 6 of the thyristor No. 1
1, but since the PN junction consisting of the P layer 52 and the 9N region 54 formed therein is in a reverse bias state, a depletion layer spreads in the KPP layer 2. The carrier path through the P layer 5.2 is narrowed. Therefore, the electric current R flowing through the composite element 51 is limited, and power loss is reduced.

The composite element 51 is actually configured as shown in FIG. jII6, for example. That is, N area 57? A JjP layer is laminated by, for example, an epitaxial method on the N-type silicon plate to be formed, and the P layer is separated into two P regions 53 and 58 by an N- region. A dish-shaped r region 59 is formed in the region 58, and an annular resistance region 53 is formed in the region 53 by, for example, a diffusion method, and electrodes 54 to 56 and electrodes 60, 61t are provided in each region (0). However, the surface area excluding each electrode part is oxidized, a
Set up t.

Protect from external atmosphere. The current flowing into the electrode 56 is limited in magnitude by the depletion layer widened by the Kll-like breakdown region 53 during reverse bias.

FIG. 7 shows yet another embodiment. In this case, the composite element 71 is a combination of an N-gate thyristor and a field effect transistor, and the voltage dividing resistors 8 and 8 are omitted. Similar to the element 51 in FIG. 6, the composite element 71 has an N region 7"3 formed in the P emitter layer 72 of the thyristor, and an electrode 74 provided in the N region 73 of ?- is the same as the element 51 in FIG.
It is connected to the other end of one series resistor R1. (In this case, R1 may be zero.) The P emitter layer 72 and the adjacent N base layer 75 are provided with electrodes 76 and 77, respectively, and a resistor hole and a capacitor CI are connected in parallel between the two electrodes. There is. Either one of R4 and C1 may be used. Electrode 77 is also connected to the main transistor 20- source electrode. In this circuit, when the terminal is in a positive state with respect to the terminal CK, the resistor R1 and the anode electrode 78
．． 2-layer 72° electrode 76 to resistor hole, t or capacitor C
Current flows through I to the main transistor 20, causing the main transistor to conduct. Next, when the potential of the terminal further increases, the voltage across the resistor R4 or the capacitor CI increases by 1, and the PN between the P emitter layer 72 and the N pace layer 750 increases.
The layer 7 of the composite stamp 71 should be made so as to bias the joining.
The thyristor consisting of 2.75, the N base layer 79, and the P emitter layer 80 becomes conductive, and current flows from the anode electrode 78 to the cathode electrode 8X, and the main transistor 2 is cut off to perform ignition. Due to the high voltage between the terminals A and C generated at this time, the PN junction between the first layer 72 and the N region 73 of the element 71 is reverse biased, and as a result, the depletion layer spread within the first layer 72] Current limitation is performed in the same way as in the previous embodiment. In this circuit, the voltage dividing resistor Rs −
Not only can Ra t' be omitted, but also electrode 77 and electrode 81 can be omitted.
The voltage between electrodes 55 and 61 in the case of FIG. 5 can also be made smaller, which has the effect of making it easier to interrupt the main transistor 2tL. t capacitor C, Fi,
terminal person.

It has the effect of delaying the ignition timing of the thyristor when the voltage between 0 and 0 rises abnormally and adjusting the ignition timing so that the 1 ignition timing does not become too early.

As explained above, by using the internal combustion engine ignition circuit Fi according to the present invention and a switching element that is a combination of field effect transistors, the magnitude of the current flowing through the switching element when the main transistor is interrupted is limited. This has the effect of reducing power loss without increasing the number of parts.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 d are respectively diagrams of different conventional examples of internal combustion engine ignition circuits, Fig. 3 is a circuit diagram of an embodiment of the ignition circuit according to the present invention, and Fig. 4 shows a part of the composite element used therein. The cutaway perspective view, FIG. 5, is a circuit diagram of another embodiment, Volume 6.
The figure is a partially cutaway perspective view of the composite element used in it.
FIG. 7 is a circuit diagram of a further different embodiment. 1...Ignition coil, 2...Main transistor. 31.51.71...Composite switching element, Figure 1, Figure 3

Claims (1)

[Claims] l) A switching element having another region of the same conductivity type as the second layer is in parallel with the main transistor. Both ends KII of the primary winding of
The first layer of the switching element is connected to the base Kml'alt of the main transistor and the ignition voltage Vx'<
: When the voltage of the primary winding of the I coil is below a predetermined value, the inflowing base current causes the P main transistor to conduct, and when it exceeds a predetermined value, the switching element conducts and the main transistor is cut off. Similarly, depending on the magnitude of the voltage in the primary winding that occurs when the main transistor is interrupted, the voltage is applied between the switching element OW+ layer and the other region in the first layer. An internal combustion engine ignition circuit characterized in that a depletion layer is formed that spreads within the first layer.