JP4214499B2 - Ignition system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition system for an internal combustion engine (hereinafter referred to as an “internal combustion engine”) that can rotate in a forward rotation direction and a reverse rotation direction.
[0002]
[Prior art]
Conventionally, a small vehicle such as a scooter or a snowmobile may not be provided with a gear for moving backward in order to achieve a reduction in size and weight. As described above, in a vehicle in which reverse cannot be selected by switching gears, an engine ignition system that realizes reverse by rotating the engine backward is known as disclosed in European Patent Application Publication No. 750113A2. ing.
In the ignition system described in this published specification, teeth are detected by two sensors as a position detection unit provided in a rotating body for each cylinder, and an engine is detected based on a phase difference between signals detected by the sensors. The forward or reverse rotation is judged.
[0003]
[Problems to be solved by the invention]
However, in the ignition system described in the above-described specification, the number of parts increases because two sensors are used to detect the rotational direction of the engine. Furthermore, since the number of assembling steps increases due to an increase in the number of electrical connection points of the sensor, 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, and has a small number of parts and assembly steps.
[0004]
[Means for Solving the Problems]
According to the ignition system of the first or second aspect of the present invention, the pair of position detectors are separated from each other in the rotational direction by sandwiching the angular position of the top dead center located between the compression stroke and the explosion stroke of each cylinder. It arrange | positions for every cylinder on the outer periphery. And the length of the rotation direction of one position detection part and the other position detection part of at least one pair of position detection part differs. The timing of the detection signal of the position detection unit detected in the cylinder in which the length in the rotation direction of one position detection unit and the other position detection unit is different, and the detection signal of the position detection unit detected in the other cylinder The timing can be shifted depending on the rotation direction of the engine. By comparing the timings of the detection signals, the forward rotation direction or the reverse rotation direction of the engine can be determined with one sensor, and the number of parts is reduced. Furthermore, since the number of steps for assembling the sensor is reduced and the number of electrical connections is reduced, the manufacturing cost is reduced.
Further, 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 either the forward rotation direction or the reverse rotation direction of the engine. Therefore, the engine can be operated under the same conditions in both the forward direction and the reverse direction.
[0006]
According to the ignition system of the third aspect of the present invention, the generation interval between the two times before and one time before the rotation front signal, the ratio between the generation time before the rotation front signal and this time, and the rotation The generation interval between the two times before and one time before the rear signal and the ratio between the generation time between the first time before the rotation rear signal and this time are calculated. Therefore, even if engine rotation fluctuation occurs, the engine rotation direction can be determined from either the rotation front signal or the rotation rear signal.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, examples showing embodiments of the present invention will be described with reference to the drawings.
An ignition system according to one embodiment of the present invention is shown in FIG.
The ignition system 1 controls ignition timing of a three-cylinder two-cycle engine that rotates a crankshaft when a piston accommodated in a cylinder (not shown) reciprocates. The ignition system 1 includes a rotating body 10, a timing sensor 30, and a control unit 31.
[0008]
The rotating body 10 rotates together with a crankshaft (not shown), and rotates once in the same manner as the crankshaft rotates once. The rotating body 10 includes a disk-shaped rotating body 11 and teeth 20, 21, 22, 23, 24, and 25 that are provided on the outer periphery of the rotating body 11 and that project outward in the radial direction. The teeth 20 are longer in the rotational direction than the other teeth except the teeth 20. During the forward rotation of the engine, the length of the teeth 20 is set so that the rotation front side of the teeth 20 is located approximately in the middle between the rotation front side of the teeth 25 and the rotation front side of the teeth 21. The teeth 20, 21 are the first cylinder, the teeth 22, 23 are the second cylinder, and the teeth 24, 25 are the top dead center (hereinafter referred to as "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 ° apart from the TDC before and after 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 rotating body 11 at equal angular intervals of 120 °.
[0009]
The timing sensor 30 uses a magnet pickup, and outputs sensor signals as detection signals on the rotation front side and the rotation rear side of each tooth as shown in FIGS. 2 and 3. As the timing sensor 30, a Hall element, an MRE element, or the like may be used.
A control unit 31 serving as a control unit includes 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 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 sparks are generated in the spark plug 37 by the electromotive force generated in the ignition coil 36.
[0010]
Next, detection of the rotational direction of the engine and switching control of the rotational direction will be described. FIG. 2 shows a time chart during forward rotation, and FIG. 3 shows a time chart during reverse rotation. 2 and 3, the left direction is the advance direction, that is, the rotation front side, and the right direction is the retard angle direction, that is, the rotation rear side.
The timing sensor 30 outputs positive and negative signals as shown in FIGS. 2 and 3 on the rotation rear side and the rotation front side of each tooth. The control circuit of the control unit 31 generates a rotation front signal G1 and a rotation rear signal G2 as pulse signals from the signal output from the timing sensor 30.
[0011]
In order to reverse the rotational direction of the engine from forward to reverse or reverse to forward during engine operation, for example, a reverse switch is pressed. However, the rotational direction of the engine cannot be reversed until the engine becomes low. In the switch determination program shown in FIG. 4, it is determined in step 100 whether or not the reverse switch is pressed. If the switch is pressed, the reverse 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.
[0012]
In step 110, it is determined whether the engine rotation direction has been determined. If it has not been determined, in step 111, the engine rotation direction is determined. A method for determining the engine rotation direction will be described below.
In the G1 signal and the G2 signal, the generation interval between the previous time and the previous time is T _n-1 , and the generation interval between the previous time and the current time is T _n , respectively. (1) If T _n-1 <T _n {(T _n-1 + T _n ) / T _n-1 } ≧ K is obtained, and if (2) T _n-1 > T _n, {(T _n-1 + T _n ) / T _n } ≧ K is obtained. The value of K is determined by the length of each tooth. If the length of the rotation direction of the other teeth excluding the teeth 20 is shortened to such an extent that the mechanical strength is maintained and the timing sensor 30 can detect, the difference between T _n-1 and T _n becomes large in the G1 signal and the G2 signal. Therefore, the value of K can be increased. If the value of K increases, the probability that the engine rotation direction can be determined by either of the above-mentioned conditions (1) or (2) increases even if the generation interval of the G1 signal and the G2 signal varies due to rotational fluctuation. .
[0013]
If either condition (1) or condition (2) is satisfied four consecutive times with the G2 signal, it is determined that the rotation direction is the normal rotation direction, and the normal rotation flag is turned on in step 112. If either condition (1) or condition (2) is satisfied four times consecutively with the G1 signal, it is determined that the rotational direction is the reverse direction, and the reverse flag is turned on in step 113. If the rotation direction cannot be determined because it has not been established four times in succession, each time the G2 signal is generated in step 114, the spark plug 37 is fixedly ignited by the control circuit at a timing of 5 ° before and after the TDC. This routine is terminated.
[0014]
If the forward rotation flag or the reverse rotation flag is turned on, the engine speed is determined in 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 being fixedly ignited 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 is set in step 118 or 119 according to the engine operating state. 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 spark plug 37 is ignited.
[0015]
If it is determined in step 115 that the rotational speed is lower than the set value 1, it is determined in step 120 whether or not the reversing switch is pressed. If the reverse switch has not been pressed, fixed ignition is performed in step 114. If the reversing switch has been pressed, the engine speed is compared with the set value 2 in step 121. If the rotational speed is greater than or equal to the set value 2, it is determined that the engine rotational speed is too high. In order to reduce the engine speed, the ignition plug of the corresponding cylinder is not ignited in step 122.
[0016]
When the rotational speed is lower than the set value 2, it is determined that the engine can be reversed. If the forward rotation is being performed, the forward advance ignition is performed in step 124 or 125 for the forward rotation, and if the reverse rotation is being performed, the reverse rotation. The set value 2 is a value lower than the set value 1. By igniting the spark 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. In step 126, the reverse flag is cleared. In step 127, the forward rotation flag, the reverse rotation flag, the engine speed, and the like are cleared.
[0017]
When the program of the control unit 31 is not operating when the engine is started, the spark plug 37 is fixedly ignited for each G2 signal. 2 and 3, the ignition plug 37 is ignited before and after the TDC of each cylinder, but the fuel has already burned even if ignited on the retard side from the TDC. Because it does not interfere with the rotation of the engine.
[0018]
In the above embodiment showing the embodiment of the present invention described above, a pair of teeth is provided for each cylinder, and only one tooth 20 of the first cylinder is longer than the other tooth 21 in the rotational direction. Therefore, the engine rotation direction can be detected by one timing sensor 30 by comparing the generation intervals in the ratios of the G1 signal and the G2 signal. Therefore, the number of parts is reduced. Further, since the number of steps for assembling the sensor is reduced, the manufacturing cost can be reduced.
Further, since the teeth are arranged at equal angles away from the front and rear in the rotational direction from the TDC of each cylinder, the spark plug can be ignited under the same conditions in the forward rotation direction and the reverse rotation direction .
[0019]
In the present embodiment, the present invention is applied to a three-cylinder two-cycle engine. However, the present invention is not limited to three cylinders, and can be applied to any number of cylinder engines as long as teeth can be installed. Further, the present invention can be applied not only to a 2-cycle engine but also to a 4-cycle engine. In that case, the rotating body 10 may be attached to a rotating shaft that rotates once while the engine rotates twice.
[0020]
In the present embodiment, teeth protruding outward in the radial direction of the rotary body 11 are formed as the position detector, but a recess may be formed in the rotary body to serve as the position detector. Further, if the engine rotational fluctuation is small, the engine rotational direction can be determined only by either the G1 signal or the G2 signal.
Moreover, it is desirable to apply the present invention not only to a vehicle or the like but also to an ignition system for an engine used for a device that requires stable engine rotation in the forward rotation direction and the reverse rotation direction, such as a belt conveyor.
[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 sensor detection signals and ignition signals during normal rotation according to the present embodiment.
FIG. 3 is a time chart showing sensor detection signals and ignition signals during reverse rotation according to the present embodiment.
FIG. 4 is a program for determining ON / OFF of an inverting switch in the present embodiment.
FIG. 5 is a control routine for controlling the ignition system of the present embodiment.
[Explanation of symbols]
10 Rotating body 11 Rotating body 12, 13, 14 TDC (Top Dead Center)
20, 21, 22, 23, 24, 25 Teeth (position detector)
30 Timing sensor 31 Control unit 33 Ignition device 36 Ignition coil (ignition device)
37 Spark plug (ignition device)

Claims (3)

In an ignition system used for an internal combustion engine having at least one cylinder and capable of rotating in a forward direction and a reverse direction,
A pair of position detectors that rotate in synchronization with the internal combustion engine and that are spaced apart from each other in the rotational direction across the angular position of the top dead center located between the compression stroke and the explosion stroke of each cylinder A rotating body having a portion for each cylinder on the outer periphery , and having different lengths in the rotational direction of one position detection unit and the other position detection unit of at least one of the pair of position detection units;
One sensor for detecting the position detection unit;
Control means for controlling the ignition timing of the ignition device by a detection signal sent from the sensor;
Equipped with a,
Each of the pair of position detectors is separated from the angular position of the top dead center by an approximately equal angle . The sensor outputs positive and negative signals on the rotation rear side and the rotation front side of the position detection unit,
The control means is based on the positive and negative signals output from the sensor, the rotation front signal of each position detection unit that is a pulse corresponding to the negative signal, and each position detection unit that is a pulse corresponding to the positive signal The ignition system according to claim 1, further comprising: The control means includes a generation interval between the two times before and one time before the rotation front signal, a ratio of a generation interval between the one time before and one time before the rotation front signal, and a time interval between two times before and one after the rotation rear signal. The ignition system according to claim 2, wherein the engine rotation direction is determined by calculating a generation interval before the rotation and a ratio between the generation interval before the rotation backward signal and the generation interval before the current rotation.

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