JP2001152905A - Ignition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive ignition system with small number of items and processing steps which enables normal and reverse rotation of an engine. SOLUTION: A rotational body 10 is attached to a crankshaft. The rotational body 10 is provided with teeth 20, 21, 22, 23, 24, 25 projected outward in a diameter direction. The tooth 20 is longer than the other in a rotational direction. The teeth 20 and 21 are arranged across a top dead center between a compression process and an explosion process of a first cylinder, the teeth 22 and 23 across a top dead center between the compression process and the explosion process of the second cylinder, the teeth 24 and 25 across a top dead center between the compression process and the explosion process of the third cylinder, respectively separated from the top dead centers by the same angles in a rotational direction. A timing sensor 30 outputs positive and negative signals in rear and front sides of a rotational direction of each tooth. In a control circuit of a control unit 31, a rotational front signal G and a rotational rear signal G2 are generated as pulse signals from the signals output from the timing sensor 30. A rotational direction of an engine can be determined from the generation intervals of the signals G1 and G2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition system for an internal combustion engine (hereinafter, referred to as an "internal combustion engine") rotatable in forward and reverse directions.

[0002]

2. Description of the Related Art Conventionally, small vehicles, such as scooters and snowmobiles, sometimes do not include a gear for moving backward in order to realize a reduction in size and weight. As described above, a vehicle disclosed in European Patent Application Publication No. 750113A2 is known as an engine ignition system that realizes reverse driving by rotating the engine in reverse in a vehicle in which reverse cannot be selected by switching gears. ing. In the ignition system described in this publication, two sensors detect a tooth as a position detection unit provided on a rotating body for each cylinder, and the engine detects a phase difference between signals detected by the two sensors. Is determined to be normal rotation or reverse rotation.

[0003]

However, in the ignition system described in the above-mentioned specification, the number of parts increases because two sensors are used to detect the rotation direction of the engine. Further, as the number of electrical connection points of the sensor increases, the number of assembling steps increases, so that the manufacturing cost increases. An object of the present invention is to provide an inexpensive ignition system that enables normal rotation and reverse rotation of an engine, has a small number of parts and a small number of assembly steps.

[0004]

According to the ignition system according to the first or third aspect of the present invention, the angular position of the top dead center located between the compression stroke and the explosion stroke of each cylinder is rotated in the longitudinal direction. And a pair of position detectors are arranged on the outer peripheral side for each cylinder. In addition, at least one pair of the position detection units has a different length in the rotation direction. The timing of the detection signal of the position detection unit detected in a cylinder having a different length of the position detection unit in the rotation direction and the timing of the detection signal of the position detection unit detected in another cylinder are determined by the rotation direction of the engine. Can be shifted. By comparing the timings of the detection signals, the forward rotation direction or the reverse rotation direction of the engine can be determined by one sensor, and the number of components is reduced. Further, since the number of steps for assembling the sensor and the number of electrical connection points are reduced, the manufacturing cost is reduced.

According to the ignition system of the second aspect of the present invention, the pair of position detectors are separated from the angular position of the top dead center by substantially the same angle. If this angle is made to coincide with the ignition timing of the ignition device, the ignition device can be ignited at the same timing before or after the top dead center in both the forward rotation direction and the reverse rotation direction of the engine. Therefore, the engine can be operated under the same conditions in both the forward rotation direction and the reverse rotation direction.

According to the ignition system of the fourth aspect of the present invention, the interval ratio between the rotation front signals and the interval ratio between the rotation rear signals are calculated. Therefore, even if the rotation of the engine fluctuates, the rotation direction of the engine can be determined based on either the forward rotation signal or the backward rotation signal.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 1 shows an ignition system according to an embodiment of the present invention. The ignition system 1 controls the ignition timing of a three-cylinder two-cycle engine that rotates a crankshaft by reciprocating a piston housed in a cylinder (not shown). The ignition system 1 has a rotating body 10, a timing sensor 30, and a control unit 31.

The rotating body 10 rotates together with a crankshaft (not shown), and makes one rotation in the same manner as the crankshaft makes one rotation. The rotating body 10 includes a disk-shaped rotating body 11.
And teeth 20, 21, 22, 23, 2 as position detecting portions provided on the outer periphery of the rotating main body 11 and protruding radially outward.
4 and 25. The teeth 20 are longer in the rotation direction than the other teeth except the teeth 20. When the engine is running forward, the teeth 25
2 is approximately halfway between the rotation front side of the tooth 21 and the rotation front side of the tooth 21.
The length of the teeth 20 is set such that the 0 rotation front side is located. The teeth 20 and 21 are the first cylinder, the teeth 22 and 23 are the second cylinder, and the teeth 24 and 25 are the top dead center (hereinafter, “top dead center”) located between the compression stroke and the explosion stroke of the third cylinder. "
Is referred to as TDC), and is disposed at the same X °, for example, 5 ° away from TDC before and after in the rotation direction. The # 1 TDC 12 of the first cylinder, the # 2 TDC 13 of the second cylinder, and the # 3 TDC 14 of the third cylinder are arranged on the rotary body 11 at equal angular intervals of 120 °.

The timing sensor 30 uses a magnet pickup, and outputs a sensor signal as a detection signal on the rotation front side and the rotation rear side of each tooth as shown in FIGS. As the timing sensor 30, a Hall element, an MRE element, or the like may be used. The control unit 31 as a control unit has a CPU, a ROM, a RAM, a control circuit, and the like, and is supplied with power from a power supply 32.
There are a total of three ignition devices 35 for each cylinder, and each of them has an ignition coil 36 and a spark plug 37. A switching signal is sent from the control unit 31 to the ignition coil 36 at the ignition timing of each cylinder, and a spark is generated at the ignition plug 37 by the electromotive force generated by the ignition coil 36.

Next, detection of the rotation direction of the engine and switching control of the rotation direction will be described. FIG. 2 shows a time chart at the time of normal rotation, and FIG. 3 shows a time chart at the time of reverse rotation. 2 and 3, the left direction is the advance direction, that is, the rotation front side, the right direction is the retard direction,
That is, it is the rotation rear side. FIGS. 2 and 3 show the timing sensor 30 on the rotation rear side and the rotation front side of each tooth.
The positive and negative signals are output as shown in FIG. Control unit 31
The control circuit generates a rotation front signal G1 and a rotation rear signal G2 as pulse signals from the signal output from the timing sensor 30.

When reversing the direction of rotation of the engine from forward to reverse or from reverse to forward while the engine is running, for example, a reverse switch is pressed. However, the direction of rotation of the engine cannot be reversed until the engine runs at low speed. In the switch determination program shown in FIG. 4, it is determined in step 100 whether or not the inversion switch is pressed, and if the switch is pressed, the inversion flag is turned on in step 101. The determination program shown in FIG. 4 is periodically executed in the main routine. The routine shown in FIG. 5 is an interrupt routine that is started every time the G1 signal and the G2 signal are generated.

At step 110, the engine rotation
It is determined whether the direction has been determined. If not, step 11
At 1, the direction of rotation of the engine is determined. engine
The method for determining the rotation direction of the above will be described below. G1 signal and
And G2 signals occur twice and one time before, respectively.
The interval is T _n-1, The occurrence interval between the previous and current times is T_nage,
(1) T_n-1<T_nNara (T_n-1+ T_n) / T_n-1｝ ≧ K
(2) T_n-1> T_nNara (T_n-1+ T_n) / T_n｝ ≧
Find K. The value of K depends on the length of each tooth. machine
Retain strength and detectable by timing sensor 30
If the length of the other teeth except the tooth 20 in the rotation direction is shortened,
T in G1 and G2 signals_n-1And T_nLarge difference
Therefore, the value of K can be increased. The value of K is large
Between the G1 signal and the G2 signal due to rotation fluctuation.
Even if the distance fluctuates, either of the above conditions (1) or (2)
The probability that the direction of engine rotation can be determined
You.

If either the condition (1) or the condition (2) is satisfied four times in succession by the G2 signal, it is determined that the rotation direction is the normal rotation direction, and at step 112, the normal rotation flag is turned on. Condition (1) or condition (2) for 4 consecutive times with G1 signal
If either of the conditions is satisfied, it is determined that the rotation direction is the reverse rotation direction, and the reverse rotation flag is turned on in step 113.
If the rotation direction cannot be determined four times in succession, the control circuit fixedly ignites the ignition plug 37 at a timing of 5 ° before and after TDC every time the G2 signal is generated in step 114. This routine is terminated.

When the forward rotation flag or the reverse rotation flag is turned on, the engine speed is determined at step 115. If the rotational speed is equal to or greater than the set value 1, a mask signal for canceling the G2 signal is generated in order to prohibit the ignition plug 37 from igniting fixedly every time the G2 signal is generated. Next, in step 117, it is determined whether the forward rotation flag and the reverse rotation flag are on or off, and a counter value that defines the ignition timing in accordance with the engine operating state is determined in step 11
8 or 119. 2 and 3,
When the calculated ignition signal is turned off, that is, when the counter becomes 0, another interrupt routine is started and the ignition plug 37 is ignited.

In step 115, the rotational speed is set to 1
If it is determined that it is lower than the threshold, it is determined in step 120 whether or not the reversing switch has been pressed. If the inversion switch has not been pressed, fixed ignition is performed in step 114. If the reverse switch has been pressed, the engine speed is compared with the set value 2 in step 121. If the rotation speed is equal to or greater than the set value 2, it is determined that the engine rotation speed is too high. Then, in step 122, the ignition plug of the corresponding cylinder is not ignited in order to reduce the engine speed.

If the rotational speed is lower than the set value 2, it is determined that the engine can be reversed. If the engine is rotating forward, an over-advanced ignition for forward rotation is performed, and if the engine is rotating backward, ignition for over-advancing angle is performed in step 124 or 125. The setting value 2 is a value lower than the setting value 1.
By igniting the ignition plug 37 at a position advanced from the normal ignition timing, the piston is pushed back before the piston reaches TDC, and the rotation of the engine is reversed. Then, in step 126, the reverse flag is cleared, and in step 127, the normal rotation flag, the reverse rotation flag, the engine speed, and the like are cleared.

When the engine is started, the control unit 31
Is not operating, the ignition plug 37 is fixedly ignited every G2 signal. 2 and 3, the ignition plug 37 is ignited before and after the TDC of each cylinder. However, even if the ignition plug 37 is ignited on the more retarded side than the TDC, the fuel already burns. Because
Does not hinder engine rotation.

In the above-described embodiment showing the embodiment of the present invention, a pair of teeth is provided for each cylinder, and only one tooth 20 of the first cylinder is made longer in the rotation direction than the other tooth 21. ing. Therefore, by comparing the generation intervals of the G1 signal and the G2 signal by a ratio, the rotation direction of the engine can be detected by one timing sensor 30. Therefore, the number of parts is reduced. In addition, since the number of steps for assembling the sensor is reduced, the manufacturing cost can be reduced. In addition, since the teeth are arranged at an equal angle before and after the TDC of each cylinder in the rotational direction, the ignition plug can be ignited under the same conditions in the normal rotation direction and the reverse rotation direction. In the present embodiment, the fixed ignition position at the time of normal rotation and the time of reverse rotation are set to the same 5 °, but need not be at the same angle, for example, 7 ° and 4 °.
It can be set as needed.

In this embodiment, the present invention is applied to a three-cylinder two-cycle engine. However, the present invention is not limited to a three-cylinder engine but can be applied to any number of cylinder engines as long as teeth can be installed. . In addition to the two-cycle engine,
The present invention can be applied to a cycle engine. In that case,
Rotating body 1 on a rotating shaft that makes one revolution while the engine makes two revolutions
0 may be attached.

In this embodiment, as the position detecting section, teeth protruding radially outward of the rotating body 11 are formed. However, a concave section may be formed in the rotating body to serve as the position detecting section. If the engine rotation fluctuation is small, the G1 signal or G1
The rotation direction of the engine can be determined by only one of the two signals. In addition, it is desirable to apply the present invention not only to a vehicle and the like but also to an apparatus that requires stable engine rotation in the forward rotation direction and the reverse rotation direction, for example, an engine ignition system used for a belt conveyor or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an ignition system according to an embodiment of the present invention.

FIG. 2 is a time chart showing a sensor detection signal and an ignition signal during forward rotation according to the embodiment.

FIG. 3 is a time chart showing a sensor detection signal and an ignition signal at the time of reverse rotation according to the embodiment.

FIG. 4 is a program for determining whether an inversion switch is on or off in the embodiment.

FIG. 5 is a control routine for controlling the ignition system of the present embodiment.

[Explanation of symbols]

Reference Signs List 10 rotating body 11 rotating body 12, 13, 14 TDC (top dead center) 20, 21, 22, 23, 24, 25 teeth (position detecting unit) 30 timing sensor 31 control unit 33 ignition device 36 ignition coil (ignition device) 37 Spark plug (ignition device)

Continued on the front page F term (reference) 3G019 AA03 AA05 AA10 AB01 BA09 CA05 GA02 HA15 3G022 AA00 AA02 AA03 CA00 DA01 DA02 FB19 GA02 3G084 AA00 BA16 DA13 FA00 FA38

Claims (4)

[Claims] 1. An ignition system for use in an internal combustion engine having at least one cylinder and rotatable in a forward rotation direction and a reverse rotation direction, wherein the rotating body rotates in synchronization with the internal combustion engine, and a compression stroke of each cylinder is provided. And a pair of position detection units disposed on the outer peripheral side of the cylinder and disposed apart from each other in the rotational direction with respect to the angular position of the top dead center located between the cylinder and the explosion stroke. A rotating body having different lengths of position detection units in the rotation direction in the unit, one sensor for detecting the position detection unit, and control means for controlling the ignition timing of the ignition device based on a detection signal sent from the sensor. An ignition system, comprising: 2. The ignition system according to claim 1, wherein each of the pair of position detection units is separated from the angular position of the top dead center by substantially the same angle. 3. The ignition system according to claim 1, wherein the control means generates a rotation front signal and a rotation rear signal of each position detection unit from a detection signal of the sensor. 4. The engine control apparatus according to claim 3, wherein said control means determines an engine rotation direction by calculating an interval ratio between said rotational front signals and an interval ratio between said rotational rear signals. Ignition system.