JPS59153974A - Contactless ignition device - Google Patents

Abstract

PURPOSE:To prevent a power loss in the low speed range of an engine, by controlling transistors with no addition to an input signal at a speed of the engine below a prescribed level while performing closed angle control at its high speed rotation. CONSTITUTION:A comparator 100 is provided in a control circuit, comparing the electric potential of a capacitor 69 relating to a rotary speed with the preset value by resistors 101, 102, and when the rotary speed exceeds a specified value, a transistor 104 is turned off, controlling a closed angle control circuit by a comparator 77 so as to function. When the rotary speed is below the specified value, the comparator 100 and the transistor 104 are turned on, and a transistor 61 is turned off whether or not an output is generated from the comparator 77, controlling output transistors 85, 84 only by inversion of an input signal. In this way, the closed angle control with less power loss can be performed in the wide speed range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a contactless ignition device for an internal combustion engine, and is designed to prevent a drop in engine energy, especially in a high speed range.

Conventionally, ignition systems for internal combustion engines such as automobiles have been equipped with mechanical contacts (contact points) in the distribeater that open and close in synchronization with the rotation of the engine, which control the primary current of the ignition coil. Those in which the secondary coil generates high-voltage pulses were widely used.

However, in recent years, hot contact type ignition devices that use non-contact electromagnetic pickup coils instead of contact points have come into practical use in order to prevent pollution and reduce fuel consumption. Requirements for accuracy are becoming increasingly high.

[Prior art and its problems]

As an example of this type of conventional contactless ignition device, FIG. 1 shows a circuit layout of a closed angle control method using a forward bias method. This device utilizes the fact that the magnitude of the output signal of the electromagnetic pickup coil 11 (see Fig. 2) is proportional to the engine speed, and connects the capacitor 1 through the diode 12.
The output signal of the coil 11 is accumulated in the transistor 14.
supplies a forward bias to the control circuit 15, and accordingly the control circuit 15 controls the current flowing through the primary coil of the ignition coil 17 by changing the conduction period of the output transistor 16, and applies a high voltage pulse to the secondary coil. occurs. This ignition device is mainly used for four-wheeled vehicles, but if it is applied to two-wheeled vehicles, it has the following drawbacks. That is, the output waveform of the timing signal generated by the electromagnetic pickup coil 11 for two-wheeled vehicles has an interference voltage, as shown in FIG. This is called the closing angle) and the closing angle is 160°.
(Duty 44%) or higher, it becomes more likely that ignition will occur.

(2) The output voltage of the electromagnetic pickup coil 11 varies due to mechanical installation errors, and the maximum output voltage reaches three times the minimum output voltage, so variations in the closing angle characteristics inevitably increase. .

Conventional technology for eliminating such drawbacks includes an electromagnetic pickup coil that generates a timing signal that is synchronized with the rotation of the engine and has at least a first period and a second period, and an electromagnetic pickup coil that generates a timing signal that is synchronized with the rotation of the engine and has at least a first period and a second period. an output transistor that supplies current to the ignition coil; a capacitor circuit that charges during the first period of the timing signal and discharges during the second period of the timing signal; Japanese Patent Laid-Open No. 57-99268 discloses a non-contact ignition device which outputs a capacitor circuit to initialize the capacitor circuit and is equipped with a control circuit for controlling the operation of the above-mentioned output transistor.

The operation of this conventional device will be described later in connection with the detailed explanation of the present invention, but if the circuit elements are determined so that opening angle control can be performed smoothly at high rotational speeds, it is possible to control the opening angle at low rotational speeds due to constraints such as circuit constants. This results in a large closing angle, which has the disadvantage of increasing power loss.

[Purpose of the invention]

It is an object of the present invention to provide a non-contact ignition device that can take advantage of the advantages of the conventional device in the high rotation speed range and further reduce power loss in the low rotation speed range.

[Key points of the invention]

The present invention detects a predetermined engine speed, and when the engine speed is below the predetermined speed, the output transistor is controlled on and off without any special processing on the input signal, and when the engine speed is above the predetermined speed, the opening angle control function of the conventional device is performed. It is characterized by the fact that it can be utilized as is.

[Embodiments of the invention]

FIG. 4 is a circuit diagram of an embodiment of the present invention, in which the circuit composed of circuit elements with two-digit numbers is described in Japanese Patent Laid-Open No. 57-9
This is a circuit disclosed in No. 9268, and a circuit (circuit surrounded by a dotted line) made up of circuit elements with three-digit numbers is a circuit added according to the present invention.

This ignition device includes an electromagnetic pickup coil circuit 41. which generates a timing signal synchronized with engine rotation. Ignition coil 42 that generates high voltage pulses. This ignition coil 42
Output transistor circuit 43. supplies primary current to output transistor circuit 43. It consists of a closing angle control capacitor circuit 45 and a power source 46 that control the closing angle of this output transistor circuit 43. The electromagnetic pickup coil circuit 41 has a series circuit of a resistor 51 and a Zener diode 52.
A constant voltage generated at both ends of 0 is supplied to the control circuit 44.

In addition, a resistor 53 is connected to both ends of this Zener diode 52.
A series circuit consisting of a diode 54 having the illustrated polarity is connected, and one end of an electromagnetic pickup coil 55 is connected to the connection point between the resistor 53 and the diode M. The other end of the electromagnetic pickup coil 55 is connected to the transistor circuit board of the control circuit 44 via a resistor 56. This electromagnetic pickup carp/1155 is synchronized with the rotation of the engine as shown in Fig. 5 (
As shown in A), an output voltage i having a waveform that increases from approximately zero in the positive direction is generated in the first period tl, increases from a negative voltage toward zero in the second period t2, and t1
Generates an output voltage with a waveform different from that of the output voltage.

The control circuit 44 includes a plurality of switching transistors 58
, 59, 60, 61, 62 and a comparator 77. Now, if a timing signal is supplied to the transistor 58 and it exceeds a predetermined level in the first period tl, the transistor Nagi becomes conductive as shown in FIG. is nonconductive, transistor 60 is conductive, and transistor 6
2 becomes non-conductive, the Darlington-connected transistors 84 and 85 in the output transistor circuit 43 are turned off.
The primary current is supplied to the ignition coil 42. However, when the timing signal reaches the second period t2, the transistor 58 becomes non-conductive as shown in FIG. 5(B), so the transistor 59 becomes conductive and the transistor mark becomes non-conductive. During this period t2, the transistor 62 becomes conductive or non-conductive depending on the state of the preceding transistor 61. The control circuit 44 further includes switching transistors 66, 76, and 74. The transistors 66 and 76 are conductive when the transistor mark is non-conductive (i.e., during the second period t2 of the timing signal), the transistors 66 control the start of discharge of the capacitor circuit 45, and the transistors 76 In addition, the constant of the comparator 770 reference voltage circuit is set.

The comparator 77 compares the reference voltage with the voltage of the capacitor circuit 45, and outputs a high-level voltage when a predetermined condition is satisfied as described later, and feeds this back to the capacitor circuit 45 via the resistor 78. The capacitor circuit 45 is brought to an initial state, and the conduction of the transistor 61 is controlled via the resistor 79. The capacitor circuit 45 includes a charging circuit consisting of a resistor 65 and a diode 67, and a discharging resistor 6.
8, a resistor 70, and a transistor 71. During the first period of the timing signal, the transistor 66 becomes non-conductive, so a charging current is supplied to the capacitor 69 via the resistor 65 and the diode 67, and the capacitor 69 is charged as shown in FIG. 5(C). Then, it is gradually charged to a constant voltage by the Zener diode 52. However, in the second period t2, the transistor 66 becomes conductive, and the diode 67 becomes inverted and becomes non-conductive, so that the capacitor 69 starts discharging via the resistor. At this time, in the control circuit 44, the transistor 76 becomes conductive, the transistor 74 becomes non-conductive, and the voltage obtained by dividing the above-mentioned constant voltage by the resistors 72 and 73 is inputted to the comparator 77 as a reference voltage. . Comparator 77 compares this reference voltage Vr with capacitor 69.
By comparing the terminal voltage VC (see Fig. 5(C)) of Vc
When ≧Vr, a low level voltage is output, and when Vc>Vr, a high level voltage H is output (Figure 5 (D)
reference). Therefore, when the terminal voltage Vc of the capacitor 69 decreases to Vc < Vr, the comparator 77 supplies the high level voltage H to the transistors 71.61 through the resistors 78 and 79, respectively, so that the transistors 71.61 become conductive. do. Therefore, capacitor 69 is connected to resistor 70. Through the transistor 71, it quickly becomes absent-minded and returns to its initial state.

Furthermore, when the transistor 61 becomes conductive, the transistor 61 becomes conductive.
2 becomes non-conductive and the output transistors 85 and 84 become conductive, so that the primary current IC flows through the ignition coil 42 during the second period t2 as well, and the ignition energy is compensated. Figure 5 (E).

(F) and (G) are transistors 61.6 and 61.6, respectively.
2 is a waveform diagram showing the relationship between the operation of No. 2 and the primary current Ic. FIG.

Next, regarding the operation of the non-contact ignition device configured as described above, further details are shown in FIGS. 5(A) to (G) and FIG. 6(A).
This will be explained with reference to the waveform diagrams of (C) to (C).

As shown in FIG. 5(A), the electromagnetic pickup coil 55 generates a timing signal in synchronization with the rotation of the engine, and during the first period 1. In the transistor 58
becomes conductive (FIG. 5(B)), so the transistor 60
, 85 and 84 are conductive, but the current transistors 59 and 84 are conductive.
62 becomes non-conductive. When the transistors 85 and 84 conduct, a primary current 1c (Fig. 5 (G
)) flows, and ignition energy is accumulated. At this time, the transistor 66 becomes non-conductive, so the capacitor 69 is replaced by the resistor 65. Charging is started with the current supplied through diode 67, and this charging continues for period 1. (Fig. 5(C)). Further, since the transistor 76 is non-conductive and the transistor 74 is conductive, the reference voltage of the comparator 770 becomes an extremely low voltage, and the comparator 77 outputs a low level L output voltage (FIG. 5(D)) to the transistor 61.
, 71, and thus the transistors 61 and 71 are non-conductive during period t1.

Then, in the second period t2 of the timing signal,
A negative voltage is provided to transistor 58 and transistor 5
8 becomes non-conductive, so the transistor 60°85, 8
4 is non-conductive, and transistors 59 and 62 are conductive.

The primary current of the ignition coil 12 is then interrupted and the energy stored in the ignition coil 42 during the period t1 is released, so that a high voltage, e.g.
kV 711'' - rises, and a spark discharge occurs in the spark plug. Also, during this period t2, the transistor 6G
, 76 become conductive, the capacitor 69 starts to lose its center via the resistor, and as the transistor 74 becomes non-conductive, the comparator 77 is supplied with the voltage Vr. is gradual, but when the terminal voltage ■c becomes lower than the reference voltage ■ (Vc<V
r), the comparator 77 outputs an output voltage of level l((Fig. 5(
■))) and feeds it back to the transistor 71, this transistor 71 becomes conductive and the capacitor 6
9, as shown in Figure 5(C), rapidly discharges and returns to the river (initial state). The output voltage of comparator 77 at level 14 is also supplied to transistor 61, so transistor 61 is conductive and transistor 62 is non-conductive (Fig. 5(E)).
), the C1 output transistor 85.84 conducts,
(See FIG. 5(F)), the primary current I in the ignition coil 42
c (Figure 5 (G)) begins to flow. In this way, the timing at which the 42nd ignition primary current IC starts to conduct can be advanced, and the closing angle can be widened.

Therefore, as the engine speed increases, as shown in FIG. 6(A), although there is no substantial change in the output waveform of the electromagnetic pickup coil 55 itself, the periods t1 and t2 become shorter, as shown in FIG. As shown by the dotted line in (B), the charging pressure of the capacitor 69 decreases. Therefore, the capacitor (jG
The terminal voltage of 2 gradually decreases by several boxes during the period t2VL2, but the voltage reaches the strict standard ■r at high speed rotation than at low speed rotation, which is shown in dots in Fig. 6(C). As such, the closing angle of the primary current IC increases during high-speed rotation, making it possible to compensate for the decrease in ignition energy.

By the way, the circuit explained so far has a function of charging the capacitor 69,
'j! Since the circuit is based on l irr, in order to smoothly control the opening angle in the high rotation range, the capacitor charging iK time constant must be made small.
For this reason, the closing angle becomes too large in the low rotation region,
The drawback is that the output transistor continues to waste current for a long time, resulting in large losses.

Therefore, in the iJ to be developed, a comparator 100 is newly installed, and this comparator 100 calculates the set value by the resistors] 01 and 102 (the set value corresponding to the predetermined rotational speed N), and the amount of electricity related to the rotational speed. and the potential of the capacitor 69, and if the rotation speed exceeds N, the transistor 104 is turned off.
The conventional opening angle control circuit using FF and comparator 77 functions.
3.

When the number of revolutions is below N, the pattern 100
Since the transistor 104 is turned on, the transistor 61 is turned off regardless of the output of the comparator 77, and the transistor 62 turns on the transistor 60.
0) It becomes OFF" and ON in the opposite relationship to 'F. In other words, the output transistors 85 and 84 can be controlled by 1" only by inverting and non-inverting the input signal.7! Ru. t; resistor 105, 'resistor 106 is transistor 60 (7)
This is added in order to prevent the control by the comparator 100 from working when the signal is "OFli".

(Then, when the rotation speed is low, the waveform produced by IJ is as shown in Figure 7. In Figure 7, (A) is the voltage of the pickup coil 55, and (B) is the output of the transistor 58. , (C) shows the weight of the capacitor 690, (D) shows the operating state of the transistor 104, (E) shows the output of the transistor 62, (F) shows the primary current of the ignition coil A-42, and (G) shows the main current of the ignition coil 42. The secondary voltage waveform is shown.

〔Effect of the invention〕

As described above, according to the present invention, by simply adding a simple circuit to the conventional circuit, it is possible to perform closing angle control with little loss over a wide range of rotational speeds.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional non-contact ignition system, Figures 2 and 3 are waveform diagrams of timing signals from the electromagnetic pickup coil in Figure 1, and Figure 4 is a non-contact ignition system according to the present invention. A circuit diagram showing one embodiment of the type ignition device, Figure 5 (A
) to (G) are waveform diagrams of each part, Fig. 6 (A) to (C)
7A to 7G are waveform diagrams for explaining the closing angle control during high-speed rotation, and FIGS. 7(A) to 7(G) are waveform diagrams for explaining the closing angle control according to the present invention during low-speed rotation. 41... Electromagnetic pickup coil circuit, 42... Ignition coil, 43... Output transistor circuit, 44...
・Closing angle control circuit, 6... Capacitor circuit, 46...
- Power supply, 100... Comparator, 104... Transistor. Fuji Electric Research Institute Co., Ltd. Patent Applicant 'Fuji Electric Manufacturing Co., Ltd. - T 5 Figure 6 Procedural Amendment Form) June 30, 1981 Special ¥ I Office 11 Government Mr. Kazuo Wakasugi 1, Indication of Case Relationship with the applicant's case Applicant 4, Agent Address: Kawasaki-ku, Kawasaki City [1l, '71 New [111]
No. 1 No. 8, Contents of the amendment As shown in the attached sheet, the contents of the amendment (2), "(Δ) to (G)" in the 9th line of page 15 of the specification are deleted. 2. Delete "1(A)-(C)" in line 10 of the same page. 3. Delete "(A) to (G)" in line 11 of the same page.

Claims (1)

[Claims] 1) Synchronized with the rotation of the engine, at least the first and fJ
! an electromagnetic pickup coil that generates a timing signal having a period of J2; an output transistor that responds to the timing signal and supplies current to the ignition coil during the first period; A capacitor circuit discharges during the second period, and when the output voltage of the capacitor circuit reaches a predetermined level, a control signal is output to bring the capacitor circuit into an initial state and control the operation of the output transistor. a second control circuit that makes the output transistor conductive during the first period of the timing signal and makes the output transistor non-conductive during the second period of the timing signal; A circuit detects a predetermined rotational speed of the engine, and when the rotational speed is below the specified rotational speed, there is no output from the second control circuit, and when the rotational speed is above the specified rotational speed, the output from the first control circuit is supplied to the output transistor. A non-contact ignition device characterized by being provided with a detection switching circuit. 2. A contactless ignition device according to claim 1, characterized in that the terminal voltage of the capacitor circuit is used as the rotation speed detection input of the rotation speed detection switching circuit.