Patent Application
20100319666
The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2009-144187 filed on Jun. 17, 2009 the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a reverse rotation preventive device for an engine of a motorcycle, and particularly to a reverse rotation preventive device for an engine of a motorcycle which is compatible with various operating conditions and is highly convenient to use.
2. Description of Background Art
It is known that when the rotating speed of a crankshaft is insufficient for starting an engine through cranking by use of a kick starter, a phenomenon of “reverse rotation” may occur in which the crankshaft is rotated in the reverse direction due to an explosion force attendant on ignition and the kick pedal is thereby pushed back.
Japanese Patent No. 3945645 discloses a reverse rotation preventive device for an engine in which, when the rotating speed of a crankshaft after its start of rotation is lowered to or below a predetermined value, the ignition at an ignition device is inhibited and the ignition inhibited condition is maintained until a new cranking operation is conducted.
Meanwhile, during the operation of a motorcycle, there is a situation in which even upon momentary locking of the rear wheel due to a braking operation during operation, the braking operation is immediately canceled to thereby continue the operation. In relation to such a situation, in the case of the reverse rotation preventive device for an engine described in Japanese Patent No. 3945645, when the rotating speed of the crankshaft is lowered to or below a predetermined value attendant on the locking of the rear wheel, a reverse rotation preventive function operates to inhibit ignition. Then, even if the brake is released in this condition and the rear wheel is rotated by the inertia of the vehicle body to thereby rotate the crankshaft, it may be impossible to restart the engine because the ignition inhibited condition is maintained. Therefore, when the engine is stopped due to the operation of the reverse rotation preventive function during operation, it is necessary to once stop the vehicle for the purpose of carrying out a new cranking operation.
In addition, particularly in a batteryless vehicle, the application of a system in which a reverse rotation preventive function is canceled by turning off the power supply for an ECU has the following problem. When the rotation of the crankshaft is recovered by releasing the brake immediately after the operation of the reverse rotation preventive function attendant on the locking of the rear wheel, the supply of electric power by a generator is restarted before the ECU voltage is lowered below a predetermined reset voltage. This may results in that the reverse rotation preventive function is not canceled. Thus, the engine cannot be restarted.
Accordingly, it is an object of an embodiment of the present invention to provide a reverse rotation preventive device for an engine of a motorcycle by which the above-mentioned problems involved in the prior art can be solved. More specifically, the engine can be restarted and operation can be continued, without once stopping the vehicle, even in the case where the reverse rotation preventive function is operated due to a momentary locking of the rear wheel.
In order to attain the above object, according to an embodiment of the present invention, a reverse rotation preventive device (30) for an engine of a motorcycle (1) including a crank pulse rotor (50) which is provided with a plurality of reluctors (52) and which is rotated synchronously with a crankshaft (45) of an engine (9), and pulse generators (PC1, PC2) for outputting a pulse signal corresponding to an interval at which the reluctors (52) are arranged, wherein the reverse rotation preventive device (30) has reverse rotation preventive means (302) for inhibiting ignition at an ignition device (35a) by operating a reverse rotation preventive function when the interpulse time of the pulse signal exceeds a predetermined time (T), and the reverse rotation preventive means (302) cancels the inhibition of the ignition when it is detected that the crankshaft (45) is in normal rotation after the ignition is inhibited by the operation of the reverse rotation preventive function.
In addition, according to an embodiment of the present invention, the reverse rotation preventive device further includes a stage deciding unit (301) for allocating one revolution of the crankshaft (45) to a plurality of stages on the basis of the crank pulse signal and measuring means (303) for measuring the interpulse time of the crank pulse signal wherein the reverse rotation preventive means (302) includes interpulse time discriminating means (306) for discriminating a plurality of the interpulse times in a predetermined period before passage of a compression top dead center, and crank stage discriminating means (307) for discriminating that a predetermined crank stage (#6) has come after the passage of the compression top dead center.
According to an embodiment of the present invention, the reluctors (52) of the crank pulse rotor (50) are arranged at regular intervals, exclusive of a toothless part (H) at one location, the stage deciding unit (301) makes definite a reference position of the crank pulse rotor (50) on the basis of a crank pulse signal corresponding to the passage of the toothless part (H) and the reverse rotation preventive means (302) cancels the operation of the reverse rotation preventive function so as to permit the ignition when the reference position is made definite and it is decided that the crankshaft (45) is in a normal rotation after the ignition at the ignition device (35a) is inhibited by the operation of the reverse rotation preventive function.
In addition, according to an embodiment of the present invention, as the predetermined time (T), two kinds of predetermined times (T1, T2) are selectively applied according to a time elapsed after arrival of a supply voltage for the reverse rotation preventive device (30) for the engine at a predetermined value, and a first predetermined time (T1) is applied until the elapsed time reaches a predetermined value, whereas a second predetermined time (T2) shorter than the first predetermined time (T1) is applied after the elapsed time reaches the predetermined value.
According to an embodiment of the present invention, the motorcycle is a batteryless vehicle which does not have an onboard battery, and the operation of the reverse rotation preventive function is canceled so as to permit the ignition when a supply voltage for the reverse rotation preventive device (30) for the engine is lowered to or below a predetermined reset voltage.
Furthermore, according to an embodiment of the present invention, the conditions of passage of the plurality of reluctors (52) are detected by at least two pulse generators (PC1, PC2), and the at least two pulse generators (PC1, PC2) are arranged so as to detect the passage of a same reluctor at different timings.
According to an embodiment of the present invention, the reverse rotation preventive device has reverse rotation preventive means for inhibiting ignition at an ignition device by operating a reverse rotation preventive function when the interpulse time of the pulse signal exceeds a predetermined time, and the reverse rotation preventive means cancels the inhibition of the ignition when it is detected that the crankshaft is in normal rotation after the ignition is inhibited by the operation of the reverse rotation preventive function. Therefore, at the time of starting the engine by use of a kick starter, ignition is inhibited upon detection of a condition in which the interpulse time detected by the pulse generators has become longer, that is, a condition in which the rotating speed of the crankshaft has been lowered to or below a preset speed making it possible to go over a compression top dead center. Consequently, the generation of reverse rotation at the time of starting the engine by use of the kick starter can be prevented. In addition, even in the case where the reverse rotation preventive function is operated in response to locking of the rear wheel during operation due to a braking operation, the inhibition of ignition is canceled owing to detection of normal rotation of the crankshaft. Therefore, it is possible to restart the engine through driving the rear wheel by the inertia of the vehicle body. As a result, it is unnecessary to stop the vehicle for the purpose of restarting the engine, and smooth operation can be continued.
According to an embodiment of the present invention, the reverse rotation preventive device further includes a stage deciding unit for allocating one revolution of the crankshaft to a plurality of stages on the basis of the crank pulse signal, and measuring means for measuring the interpulse time of the crank pulse signal, and the reverse rotation preventive means includes interpulse time discriminating means for discriminating a plurality of interpulse times in a predetermined period before passage of a compression top dead center, and crank stage discriminating means for discriminating that a predetermined crank stage has come after the passage of the compression top dead center. Therefore, it is possible to accurately detect a lowering in the rotating speed of the crankshaft, and to accurately discriminate the normal rotation state of the crankshaft.
According to an embodiment of the present invention, the reluctors of the crank pulse rotor are arranged at regular intervals, exclusive of a toothless part at one location, the stage deciding unit makes definite a reference position of the crank pulse rotor on the basis of a crank pulse signal corresponding to passage of the toothless part and the reverse rotation preventive means cancels the operation of the reverse rotation preventive function so as to permit the ignition when the reference position is made definite and it is decided that the crankshaft is in normal rotation after the ignition at the ignition device is inhibited by the operation of the reverse rotation preventive function. Therefore, in the case where normal rotation of the crankshaft is started after the ignition is inhibited by the operation of the reverse rotation preventive function, the reverse rotation preventive function can be canceled before one revolution of the crankshaft is performed after the reference position is made definite. Accordingly, it is possible to swiftly restart the engine by the inertia of the vehicle body and to smoothly continue the operation, even in the case where the reverse rotation preventive function is operated in response to locking of the rear wheel due to a braking operation during operation.
According to an embodiment of the present invention, as the predetermined time, two kinds of predetermined times are selectively applied according to a time elapsed after arrival of a supply voltage for the reverse rotation preventive device for the engine at a predetermined value, and a first predetermined time is applied until the elapsed time reaches a predetermined value, whereas a second predetermined time shorter than the first predetermined time is applied after the elapsed time reaches the predetermined value. Therefore, it is possible to make a setting such that the reverse rotation preventive function is not operated unless the rotating speed is lowered greatly, in the beginning stage of a kick starter operation. It is also possible to operate the reverse rotation preventive function even if the degree of lowering in the rotating speed is low, in the middle and late stages of a kick starter operation. Consequently, it is possible to optimize the operating conditions and to enhance startability.
According to an embodiment of the present invention, the motorcycle is a batteryless vehicle which does not have an onboard battery, and the operation of the reverse rotation preventive function is canceled so as to permit the ignition when a supply voltage for the reverse rotation preventive device for the engine is lowered to or below a predetermined reset voltage. Therefore, even in the case where ignition is inhibited by the operation of the reverse rotation preventive function at the time of starting the engine by use of the kick starter, the operation of the reverse rotation preventive function is canceled in response to a condition in which the rotating speed of the crankshaft is lowered and the voltage in the ECU as a reverse rotation preventive device for the engine is lowered to or below the reset voltage, which makes it possible to perform a kick starter operation in the condition where the ignition is allowed. Consequently, it is possible to obtain a reverse rotation preventive device for an engine in which no trouble is generated even when the reverse rotation preventive function is operated at the time of starting the engine by use of the kick starter or during operation, and which is highly convenient to use.
According to an embodiment of the present invention, the conditions of passage of the plurality of reluctors are detected by at least two pulse generators, and the at least two pulse generators are arranged so as to detect the passage of a same reluctor at different timings. Therefore, whether the crankshaft is in a normal rotation or in reverse rotation can be detected before one revolution of the crankshaft is performed. Accordingly, in the case of restarting the engine after the operation of the reverse rotation preventive function during operation, the ignition inhibited condition can be canceled through detecting the normal rotation of the crankshaft before one revolution is performed after the restart of rotation of the crankshaft, so that the engine can be restarted swiftly.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Now, a preferred embodiment of the present invention will be described in detail below referring to the drawings.
To a down frame 5 connected to the head pipe 6 and extending downward, a left-right pair of lower frames 4 are connected. The engine 8 is supported by mount portions 11, 12 of the lower frames 4. A cylinder 9 and a cylinder head 10 are fixed to an upper portion of the engine 8, and an exhaust pipe 13 attached to the cylinder 9 extends toward the rear side of the vehicle body, to be connected to a muffler 29. In addition, a throttle body 18 including a fuel injection device 36 (see
To a rear lower side of the main frames 2, a left-right pair of center frames 3 are joined. On a swing arm pivot 22 provided on the center frames 3, a swing arm 21 suspended from the main frames 2 by a rear shock absorber 20 is swingably supported. On a rear end portion of the swing arm 21, a rear wheel WR is turnably borne. Rotational driving force generated by the engine 8 is transmitted to a driven sprocket 25 secured to the rear wheel WR, through a drive chain 24 wrapped around a drive sprocket 23.
A fuel tank 17 is disposed on the upper side of the cylinder head 10 and between the left-right pair of main frames 2. Seat rails 27 and rear frames 26 are connected to rear portions of the main frames 2. A seat 28 is attached to upper portions of the seat rails 27, and an ECU 30 as a reverse rotation preventive device for an engine inclusive of reverse rotation preventive means is disposed under the seat 28.
The ECU 30 is supplied with output signals from an intake pressure sensor (PB sensor) 37 for detecting a manifold air pressure generated in an intake pipe of the engine 8, a throttle sensor 38 for detecting the position (opening) of a throttle valve (not shown) disposed inside the throttle body 18, an intake temperature sensor 39 for detecting the intake temperature, and a water temperature sensor 40 for detecting the cooling water temperature at the engine 8. In addition, a crank pulse rotor 50 with a plurality of reluctor attached thereto is mounted onto the crankshaft 45 of the engine 8. The ECU 30 can detect the rotational position and the rotating speed of the crankshaft 45 by a system in which the condition of passage of the reluctors is detected as a pulse signal by magnetic pick-up type pulse generators PC1 and PC2. The ECU 30 is provided also with an engine stop switch which, when operated by the driver, can inhibit the operation of the ignition device.
The “cycle stage” in the table relates to a total of twenty-two stages #0 to #21 into which two revolutions of the crankshaft are divided based on the detection results of the “crank stage,” variations in the intake pressure detected by the intake pressure sensor 37, and the like. The “cycle stage” is assigned a tentative number until a stroke discriminating process based on the variations in the intake pressure and the like is completed and it is made clear whether the crankshaft is currently in the first revolution or the second revolution in one cycle (two revolutions: 720 degrees).
This table shows the conditions of passage of the reluctors during normal operation in the condition where discrimination of the engine stroke has been completed, starting the description from the position before the reluctor #A passes the first pulse generator PC1. First, when the reluctor #A has passed the first pulse generator PC1, it is detected that the crank stage #10 has been started. Then, following to detection of the reluctor #4 by the second pulse generator PC2, the passage of the reluctor #0 is detected by the first pulse generator PC1, whereon it is ascertained that the process has proceeded to the next crank stage.
Subsequently, the second pulse generator PC2 detects the passage of the reluctor #5. In the next place, however, due to the presence of the toothless part (H) over an interval of 60 degrees amid the array of the reluctors, the second pulse generator PC2 detects the passage of the reluctor #6 before the first pulse generator PC1 detects the passage of any reluctor. As a result, the presence of the toothless part (H) is confirmed, and it is made clear that the current crank stage is #0. Accordingly, a reference position of the crankshaft is made definite (B). With the reference position thus made definite, the ECU 30 becomes able to discriminate the numbers of the reluctors which will pass by subsequently. The ECU 30 performs the confirmation of the reference position of the crankshaft every one revolution of the crankshaft (B, D). In addition, in the case where the discrimination of the engine stroke is completed in making the reference position definite (B), the crank stage proves to be #0 and, simultaneously, the cycle stage proves to be #11.
When the crank stage #6 as a previously set “predetermined crank stage” is detected after the reference position of the crankshaft is made definite, the result of a stage judgment is OK (C), that is, it is judged that there is no error in the process of making definite the reference position of the crankshaft and that the crankshaft is rotating normally, whereby a normal rotation state of the crankshaft is detected. Thus, discrimination of whether or not the predetermined crank stage (#6) has come after the passage of the compression top dead center is executed by stage discriminating means (see
The pulse generators PC1 and PC2 can only detect the passage of each reluctor, and the discrimination of the reluctor is carried out by counting the number of the reluctors passing by. Therefore, in the case where the rotating state of a crank pulse rotor 50 as shown in
Referring to the bottom part of the table shown in
The ignition coil 35 and the spark plug 35a are connected to the ignition circuit 41. The ignition coil 35 is supplied with electric power generated by the generator 31 and rectified by the regulator-rectifier 32. Now, the procedures of operating the reverse rotation preventive function and canceling the operation will be described in detail below, referring to
In this flow chart, the flow in starting the engine 8 by use of the kick starter is assumed. First, in step S10, the rotating speed of the crankshaft 45 rises after the operation of the kick starter is started, and the electric power from the generator exceeds a starting voltage for the ECU 30, whereby the ECU 30 is started. In the subsequent step S11, measurement of the interpulse time of the crank pulse signal by the timer 303 is started. The measurement of the interpulse time is carried out by interpulse time discriminating means 306 (see
When the result of decision in step S12 is affirmative (Y), that is, when it is detected that the interpulse time has become longer and the rotating speed of the crankshaft has been lowered below a preset speed making it possible to go beyond the compression top dead center without trouble, it is judged that reverse rotation may possibly be generated, and the control proceeds to step S13.
Here, as the predetermined time T used in step S12, two kinds of predetermined times are selectively applied, according to the time elapsed after the start of the ECU 30. As shown in
According to such settings of the predetermined time T, it is ensured that in the beginning stage of the kick starter operation, the reverse rotation preventive function does not operate unless the crankshaft rotating speed is lowered greatly. It is also ensured that in the middle and later stages of the kick starter operation, the reverse rotation preventive function is permitted to operate even if the degree of lowering in the rotating speed is small. As a result, it becomes possible to optimize the operating conditions and to enhance startability. In addition, the settings of the predetermined time T may be arbitrarily modified according to engine specifications or the like.
Returning to the flow chart shown in
On the other hand, when the result of decision in step S14 is negative (N), that is, when it is decided that electric power in excess of the predetermined reset voltage is being supplied, a series of control actions is finished while maintaining the condition where the ignition is inhibited. The case where the result of decision in step S14 is negative (N) corresponds to the case where the reverse rotation preventive function is operated in response to momentary locking of the rear wheel by a braking operation during operation, then the brake operation is immediately canceled and the power supply by the generator 31 is restarted, and, as a result, the voltage on the ECU 30 is recovered without being lowered to or below the reset voltage. Such a situation is said to be liable to occur, for example, in the case where a batteryless vehicle having a fuel injection device is provided in its electric circuitry with a capacitor of a large capacity for stably operating the fuel injection device.
The ECU 30 pertaining to this embodiment is so set that, during normal ignition control, preparation for ignition is started at the time of start of crank stage #6, and ignition is performed at the time of start of crank stage #9. At time t1, the preparation for ignition is started, based on this setting for normal ignition control. In the next crank stage #7, however, due to the locking of the rear wheel attendant on a braking operation during operation, the interpulse time is made longer, and the decision condition for operating the reverse rotation preventive function (for example, the condition that the crankshaft rotating speed is at or below 500 rpm) is therefore satisfied notwithstanding the vehicle is operating. As a result, at time t2, the reverse rotation preventive function operates, to inhibit the ignition by the ignition device.
In this embodiment, the control system is set so as to execute a soft off control for driving a switching element so that a primary current for the ignition coil is cut off at a predetermined gradient, at the time of inhibiting the ignition by the reverse rotation preventive function. In the example shown in
Subsequently, at time t4, the rotating speed of the crankshaft has returned to the state before the locking of the rear wheel. This corresponds to a condition in which the driver cancels the brake operation and engages the clutch, trying to restart the engine through rotating the rear wheel by the inertia of the vehicle body. However, in the process of starting the operation of the reverse rotation preventive function described in the flow chart in
To cope with such a problem, in the reverse rotation preventive device for an engine pertaining to the present invention, a configuration is adopted in which after an ignition inhibited state is established by the reverse rotation preventive function, the ignition inhibited state is canceled upon detection of a normal rotation state of the crankshaft, even if the voltage on the ECU 30 is not lowered below the reset voltage. This makes it possible to restart the engine through rotating the rear wheel by the inertia of the vehicle body, and to continue operation. Now, the process of canceling the operation of the reverse rotation preventive function will be described below, referring to
When the result of decision in step S22 is affirmative (Y), that is, when it is decided that the crankshaft is in the normal rotation state, the control proceeds to step S23, in which the reverse rotation preventive function is canceled, whereby the ignition inhibited state is canceled. In addition, when the result of decision in any of steps S20, S21 and S22 is negative (N), a series of control actions is finished, without canceling the reverse rotation preventive function.
Returning to the time chart in
Subsequently, at time t5, the start of crank stage #6 is detected normally, which results in that the normal rotation state of the crankshaft is recognized by the ECU 30. In this embodiment, the timing of recognition of the normal rotation state and the timing of starting the preparation for ignition coincide with each other on the crank stage; therefore, at time t5, the inhibition of ignition is canceled and, simultaneously, the preparation for ignition is started. According to such a setting for canceling the inhibition of ignition, the inhibition of ignition is canceled within one revolution of the crankshaft from the time when the reference position is made definite, even in the case where the reverse rotation preventive function is operated during operation. Therefore, it is possible to swiftly restart the engine before the inertia of the vehicle body is lowered, and to continue operation.
In addition, the ECU 30 is so set as to reset the results of engine stroke discrimination, attendant on the operation of the reverse rotation preventive function, even in the case where the supply voltage on the ECU 30 is not lowered below the predetermined reset voltage. This results in that the stroke discriminating process must again be executed at the time of restarting the engine. At time t6, the stroke discriminating process has not yet been completed. Therefore, preparation for ignition by waste ignition at the exhaust top dead center (360-degrees ignition) which is deviated by one crankshaft revolution (360 degrees) from the original ignition timing is started. Thereafter, when the stroke discriminating process is completed, an ignition control at a predetermined timing ahead of the compression top dead center is carried out by the normal ignition control unit 305.
As above-mentioned, according to the reverse rotation preventive device for an engine pertaining to the present invention, even in the case where ignition is inhibited by an operation of the reverse rotation preventive function during operation, the inhibition of ignition is canceled in response to detection of normal rotation of the crankshaft, so that the engine can be restarted through driving the rear wheel by the inertia of the vehicle body. This eliminates the need to stop the vehicle for restarting the engine, and makes it possible to smoothly continue the operation. In addition, after ignition is inhibited by the operation of the reverse rotation preventive function during operation, the ignition inhibited state is continued unless a normal rotation state of the crankshaft is detected. This prevents ignition from being carried out in the condition where the crankshaft is in reverse rotation. Consequently, an appropriate ignition control can be performed.
In addition, it should be noted that the shapes and layout of the crank pulse rotor and the reluctors, the number and shape of the pulse generators, the method of detecting the normal rotation of the crankshaft, the setting of the interpulse time for operating the reverse rotation preventive function, etc. are not limited to those in the embodiment described above, and various modifications of them are possible. The reverse rotation preventive device for an engine according to the present invention is applicable to various vehicles of the batteryless type in which an engine is started by use of a kick starter.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-144187 | Jun 2009 | JP | national |
