JP2995924B2 - Valve system for 4-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve system for a four-stroke engine capable of changing a valve lift, a valve opening timing, etc. of an intake / exhaust valve according to an operating condition.
In particular, the present invention relates to a valve system for a four-stroke engine that prevents a cam switching sound from being generated when an ignition switch or the like that starts and stops the engine is turned on and off.

[0002]

2. Description of the Related Art Generally, in a four-cycle engine mounted on a vehicle such as an automobile and a motorcycle, intake and exhaust valves are disposed above a combustion chamber, and these valves are driven by a valve train. That is, the valve train includes a camshaft linked to the crankshaft of the engine, and the cam formed on the camshaft moves the intake and exhaust valves up and down at a predetermined timing.

[0003]

By the way, the above-mentioned four-stroke engine is required to obtain a high output within a wide rotation speed range from a low rotation speed range to a middle and high rotation speed range, that is, to have a wide power band. Is desirable.

However, in the conventional valve gear, since the valve opening / closing timing and the lift amount are fixed, only an output characteristic having a peak value in a specific engine speed range is obtained. A choice must be made between emphasizing output characteristics or emphasis on output characteristics in the middle and high speed ranges.

The present invention has been made in consideration of the above circumstances, and can improve the engine output within a wide rotation speed range, and can also be used to turn on or off an ignition switch or the like for operating and stopping the engine. It is an object of the present invention to provide a valve train for a four-cycle engine that can prevent the generation of the switching noise.

According to a first aspect of the present invention, a low speed rocker arm which is directly fitted to a rocker shaft and is operated by a low speed cam, and which is fitted to an eccentric large diameter portion of the rocker shaft and is operated by a middle / high speed cam. A rocker that switches the flow direction of hydraulic oil by operating a low-speed rocker arm and a solenoid valve to rotate the rocker shaft in the forward and reverse directions, and selectively switches the operation between the low-speed cam and the middle-high speed cam. A shaft drive mechanism; and an igniter for controlling ON / OFF operation of a solenoid of the solenoid valve based on an engine speed.
One end of the solenoid coil is connected to a battery plus terminal regardless of the ON / OFF operation of an ignition switch, and the other end of the solenoid coil is provided in the igniter. A time constant circuit is installed in the connection to the igniter, and the igniter raises the engine speed once to the middle and high speed range even if the engine speed is in the low speed range when the middle and high speed cam is activated. Then, when the rotational speed falls to a low speed range, the solenoid is turned ON to control the low speed cam to operate.

A second invention is a low-speed rocker arm which is directly fitted on a rocker shaft and is operated by a low-speed cam, and which is mounted on an eccentric large-diameter portion of the rocker shaft and is operated by a medium-high speed cam. The low-speed rocker arm and the solenoid valve actuate to switch the flow direction of hydraulic oil to rotate the rocker shaft in the forward and reverse directions, thereby selectively operating the low-speed cam and the medium-high speed cam. A rocker shaft drive mechanism for switching, and an igniter for controlling the ON / OFF operation of the solenoid of the solenoid valve based on the engine speed. Both ends of the low-speed and medium-high speed rocker arms are suction / exhaust valves. The solenoid and the igniter are provided with a battery and an igniter. A voltage is applied to both the alternator via a delay timer relay via an operation switch and a delay circuit for controlling ON / OFF of the relay of the delay timer relay includes an ON / OFF operation of the ignition switch. Regardless, the voltage is applied from the alternator.

[0008]

Therefore, according to the valve gears of the four-stroke engine according to the first and second aspects of the present invention, the rocker shaft is rotated by a predetermined angle to rotate the eccentric large-diameter portion. Of the cam floor surface of the low-speed rocker arm relative to the cam floor surface in the vertical direction. When the cam floor surface of the medium / high speed rocker arm is moved downward with respect to the cam floor surface of the low speed rocker arm, the contact between the medium / high speed rocker arm and the medium / high speed cam is released, and the low speed rocker arm and the low speed cam are disengaged. In contact therewith, the valve of the four-stroke engine is driven by this low speed cam.

When the cam floor surface of the middle / high speed rocker arm is changed to a position substantially above or at the same position with respect to the cam floor surface of the low speed rocker arm, the contact between the low speed rocker arm and the low speed cam is released. The high-speed rocker arm and the medium-high speed cam abut
The valve of the cycle engine is operated by the medium speed cam. Thus, by selecting the cam by rotating the rocker shaft, the engine output can be improved over a wide rotation speed range.

Further, according to the first invention, the ignition switch is turned off when the engine is in a low speed range.
Even if the solenoid is operated, the solenoid is turned off after a predetermined time has passed by the time constant circuit in the igniter. When this solenoid is turned off, the engine has already been stopped by turning off the ignition switch, and therefore the oil pressure of the hydraulic oil has also dropped significantly. The rocker shaft does not rotate and is not switched to the middle / high speed cam, thereby preventing the generation of uncomfortable cam switching noise.

Further, in the first aspect of the invention, even if the ignition switch and the like are turned off at the time of middle and high engine rotation, and then the ignition switch and the like are again turned on and the engine is started, the igniter operates in the middle and high engine speed range of the engine speed. The solenoid valve is turned off for the first time when the engine speed rises to the low speed range, and the high-speed cam is switched to the low-speed cam. At the time of this switching, since the hydraulic pressure of the working oil is sufficiently ensured, no unpleasant cam switching noise is generated when switching to the low speed cam.

According to the second aspect, when the ignition switch or the like is turned off at the time of low engine rotation,
The delay circuit of the delay timer relay keeps the timer relay on for a predetermined time, during which the current from the battery activates the igniter and the solenoid, and the solenoid maintains the ON state. Even if the solenoid is turned off when the timer relay is turned off after the elapse of the predetermined time, the engine has already stopped at this time and the hydraulic pressure of the hydraulic oil of the rocker shaft drive mechanism has dropped significantly. Switching to cam for medium and high speed is not done,
No unpleasant cam switching noise is generated.

Further, when the ignition switch is turned off at the time of high engine rotation, the solenoid and the igniter continue to operate by the action of the delay timer relay. During this time, the igniter turns off the solenoid when the engine reaches the low speed range. Then, the rocker shaft drive mechanism is operated to switch to the low speed cam. This solenoid OF
At the time of the F operation, the engine speed is high and the hydraulic pressure of the working oil is sufficiently secured, so that unpleasant switching noise is not generated at the time of cam switching.

[0014] Even if the timer relay of the delay timer relay is turned off and the solenoid is turned off when a predetermined time has elapsed after the engine rotation has stopped, the engine has already stopped at this point and the hydraulic oil pressure of the working oil is extremely low. No cam switching is performed, and no unpleasant cam switching noise is generated. Thereafter, even if the engine is started by turning on the ignition switch again, the cam is not switched because the low speed cam is already in operation, and no unpleasant cam switching noise is generated.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a perspective view showing one embodiment of the valve train of the four-stroke engine according to the first invention.

The valve train is disposed on the intake side and the exhaust side of one cylinder of the engine. Therefore, the valves 1 and 2 shown in FIGS. 4 to 6 are arranged for intake or exhaust.

In this embodiment, a camshaft 6 (FIG. 5) having a low-speed cam 3 and medium-high speed cams 4 and cams 5 disposed on one side and the other side of the low-speed cam 3, respectively. , FIG. 6), a low-speed rocker arm 7, a medium-high speed rocker arm 8 and 9 positioned below each of the cams 3, 4 and 5, and supports 7a, 8a and 9a of these rocker arms 7, 8 and 9. And a rocker shaft 11 rotatably supported by a rocker shaft bearing of the cylinder head.
Rocker shaft drive mechanism 13 for rotating 1 (FIG. 7)
And is provided.

The distal end of the low-speed rocker arm 7 branches in two directions, and both branch distal ends 7b are in contact with the stem heads of the valves 1 and 2 for opening and closing the combustion chamber of the engine (not shown). In addition, the low-speed rocker arm 7
Is directly inserted into the rocker shaft 11 and is rotatably provided.

The respective supporting portions 8a and 9a of the medium and high speed rocker arms 8 and 9 are connected to the rocker shaft 1 via an eccentric bush 12 having a larger diameter than the rocker shaft 11.
1 is rotatably fitted with respect to 1. This eccentric bush 12
As shown in FIG. 5, the shaft center is eccentric from the center of the rocker shaft 11, and is detachably fixed to the rocker shaft 11 by the positioning fixing pin 10. Therefore,
The eccentric bush 12 functions as an eccentric large diameter portion of the rocker shaft 11.

The lower surfaces of the distal ends 8a and 9a of the medium and high speed rocker arms 8 and 9 are in contact with one and the other branch distal ends 7b of the low speed rocker arm 7 via shims 14a, respectively. Therefore, as shown in FIG. 5, when the low-speed cam 3 presses down on the cam floor surface 7c of the low-speed rocker arm 7 and lowers its tip portion 7b (when the low-speed cam 3 is operated), the rocker arm 3 moves downward. The respective tips 8b and 9b of 8 and 9 do not come down together with the branch tip 7b. On the other hand, as shown in FIG. 6, the middle and high speed cams 4 and 5 are
When the cam floor surfaces 8c and 9c of the rocker arms 8 and 9 are depressed (when the middle and high speed cams 8 and 9 are actuated), the tip portions 8b and 9b of these rocker arms 8 and 9 respectively.
Presses down each branch tip 7b of the low-speed rocker arm 7, the branch tip 7b is forcibly lowered.

The valve stem heads of the valves 1 and 2 are covered with a covered cylindrical shim 14b, and the lower surface of the branch tip 7b of the low-speed rocker arm 7 abuts the shim 14b. These shims 14a and 14b are used for adjusting the tappet clearance of the valves 1 and 2.

Among the cams 3, 4 and 5, the middle and high speed cams 4 and 5 have the same cam profile, and the low speed cam 3 has a different cam profile from those of the middle and high speed cams 4 and 5. Has a cam profile. That is, the cam profile of the low-speed cam 3 is set such that a valve lift amount and an opening / closing valve timing that are appropriate when the engine is operated in a low rotation speed range.
The cam profiles for the middle and high speed cams 4 and 5 are set so that a suitable valve lift amount and opening / closing valve timing are obtained when the engine is operated in a middle / high speed range.

The rocker shaft drive mechanism 13
Has a hydraulic actuator 15 that operates using engine oil as hydraulic oil, and an oil switching solenoid valve 16 that switches the flow of engine oil supplied to the hydraulic actuator 15, as shown in FIGS. Be composed.

The hydraulic actuator 15 has a piston 19 opposed to a cylinder 18 of an actuator body 17. The actuator body 17 has a medium- and high-speed oil passage 21 which communicates with a center position of the cylinder 18 in the axial direction.
And a low-speed oil passage 20 communicated with both ends of the cylinder 18.
Are formed. A rack 22 is integrally formed at the tip of the piston 19, and the rack 22 meshes with a pinion 23 formed at an end of the rocker shaft 11.

On the other hand, the oil switching solenoid valve 16
In the figure, a spool valve 25 is provided in a valve body 24, and the spool valve 25 is slid by exciting and demagnetizing an electromagnet 26. Valve body 24
The oil supply port 27 through which the engine oil flows in, the low-speed oil supply port 29 communicated with the low-speed oil passage 20 of the hydraulic actuator 15 through the low-speed hydraulic pipe 28, and the hydraulic actuator 15 medium / high speed oil supply port 31 communicated with the medium / high speed oil passage 21
And a relief port 32 are respectively formed. Excitation and demagnetization of the electromagnet 26 are controlled by an igniter 34 described later based on the engine speed and the like.

When the electromagnet 26 is excited, the spool valve 25 moves from the position shown in FIG. 7 in the direction of the arrow Q, the oil supply port 27 communicates with the low-speed oil supply port 29, and the medium-speed oil supply port 31 becomes a relief port. 32.
For this reason, the hydraulic oil is introduced from the oil supply port 27 to the low-speed oil passage 20 of the hydraulic actuator 15 through the low-speed oil supply port 29 and the low-speed hydraulic pipe 28, and the piston 19 is pushed back in the arrow M direction shown in FIG. , The pinion 23 rotates in the direction of the arrow O. Thereby, as shown in FIG.
The thick top portion 12a of the eccentric bush 12 moves diagonally forward, and the low-speed cam 3 operates the low-speed rocker arm 7 to drive the valves 1 and 2.

When the electromagnet 26 is demagnetized, the spool valve 28 is moved to the position shown in FIG. 7 by the urging force of the solenoid return spring 33. As a result, the oil supply port 27 and the medium / high speed oil supply port 31 communicate with each other. In addition, the low-speed refueling port 29 and the relief port 32 communicate with each other. For this reason, the hydraulic oil is introduced from the air supply port 27 to the medium / high speed oil passage 21 via the medium / high speed oil supply port 31 and the medium / high speed hydraulic pipe 30, and the piston 19 is pushed out in the direction of arrow N shown in FIG. , The pinion 23 rotates in the direction of the arrow P. As a result, as shown in FIG. 6, the thick top portion 12a of the eccentric bush 12 moves diagonally rearward, the cams 4 and 5 for medium and high speed actuate the rocker arms 8 and 9 for medium and high speed, and the valves 1 and 2 are operated. Drive.

As shown in FIG. 1, the igniter 34 includes an ignition transistor 36 for interrupting a current flowing to an ignition coil 35, a solenoid switching transistor 38 for interrupting a current flowing to a solenoid 37 of the electromagnet 26, and a solenoid switching transistor 38. Time constant circuit 39 connected to the base terminal of the transistor for ignition 38, and a CPU (central process) for controlling the current to the base terminal of the ignition transistor 36 and the current to the time constant circuit 39.
sing unit) 40.

In the electric circuit of the ignition / charging system of the motorcycle shown in FIG. 1, the alternating current generated by the alternator 41 is rectified by the regulating rectifier 51, and the voltage is controlled. Through the battery 43 and the ignition switch 4
4, through the fuse 45, the side stand relay 46, and the kill switch 47, are supplied to the ignition coil 35 and the CPU 40 of the igniter 34. The solenoid 37 of the oil switching solenoid valve 16 is connected to the upstream side of the ignition switch 44 and the downstream side of the regulate rectifier 51 via a fuse 48, and turns ON / OFF of the ignition switch 44 and the kill switch 47. Installed independently of OFF.

Further, the solenoid 37 is connected to a collector terminal of a solenoid switching transistor 38. Further, the CPU 40 of the igniter 34 receives an engine speed signal from the pickup coil 49 and a cam determination signal from the operating cam determination switch 50 (FIG. 4). Here, the operation cam determination switch 50 detects the rotation position of the rocker shaft 11 and
Alternatively, the operation state of one of the middle and high speed cams 4 and 5 is determined.

Reference numeral 52 denotes a detection line for detecting the voltage on the downstream side of the ignition switch 44 and controlling the regulating rectifier 51 to a constant voltage (for example, 12 V) DC. Reference numeral 53 denotes a detection line. 2 shows a spark plug.

The CPU 40 of the igniter 34 operates the ignition transistor 36 based on the engine speed signal from the pickup coil 49, controls the current flowing to the primary coil of the ignition coil 35, and controls the ignition timing. Further, the CPU 40 controls the pickup coil 4
9 and the cam determination signal from the operation cam determination switch 50, and the time constant circuit 39
To control the current flowing to the base terminal of the solenoid switching transistor 38 via the
・ Turn OFF.

That is, when the engine speed increases, the CPU 40 supplies power to the solenoid switching transistor 38 at a speed of about 9500 rpm or less, turns on the solenoid 37 to excite the electromagnet 26, and controls the spool valve 25 and the hydraulic actuator 15. , The power supply to the solenoid switching transistor 38 is cut off at a rotation speed of about 9500 rpm or more, the solenoid 37 is turned off, the electromagnet 26 is demagnetized, and the medium-high speed rocker arm 4 and Activate 5 In addition, when the engine speed decreases, the CPU 40 operates at a rotational speed of about 9000 rpm or more.
Is turned off to demagnetize the electromagnet 26 and operate the middle and high speed cams 4 and 5, while the solenoid 37 is turned on at a rotation speed of about 9000 rpm or less to excite the electromagnet 26 and operate the low speed cam 3 Let it.

Further, the CPU 40 inputs a cam judgment signal from the operation cam judgment switch 50, and
When the power is switched to the medium- and high-speed cams 4 and 5 at the time when the power is supplied to the
Unless it rises to the operation range of the middle and high speed cams 4 and 5 at or above 00 rpm, the solenoid switching transistor 38 is not supplied with power, and the solenoid 37 is kept OFF to maintain the operation state of the middle and high speed cams 4 and 5. . Further, since the time constant circuit 39 includes a resistor and a transistor, the current from the CPU 40 is supplied to the base terminal of the solenoid switching transistor 38 with a certain time delay while the CPU 4
Even when the current supply from 0 is stopped, the current supply to the base terminal is stopped with a certain time delay.

Incidentally, an igniter 54 shown in FIG. 12 may be used instead of the CPU 40 shown in FIG. In the igniter 54, the time constant circuit 39 does not exist, and the cam determination signal from the operation cam determination switch 50 is also supplied to the CPU.
40, and the input side of the solenoid 37 is
Downstream of the fuse 45 and the side stand relay 46
Connected to the upstream side. Other configurations are the same as those of the electric circuit such as the igniter 34, and are denoted by the same reference numerals.

According to the igniter 54, when the engine is running at an idling speed (about 1300 rpm), the CPU 40 of the igniter 54 supplies power to the base terminal of the solenoid switching transistor 38 to turn on the solenoid 37 ( 13 (upper column in FIG. 13), in a state where the electromagnet 26 is excited to operate the low-speed cam 3 (lower column in FIG. 13). At this time, when the ignition switch 44 or the kill switch 47 is turned off, the power supply to the ignition coil 35 is cut off, the ignition is cut, and the engine is stopped.
Is also cut off, and the solenoid 37 is turned off instantaneously. However, at this point, the engine has just stopped, and the oil pressure of the engine oil supplied to the hydraulic actuator 15 is in the process of decreasing as shown in the middle column of FIG. It becomes incomplete and unpleasant switching sounds are generated.

On the other hand, when the engine is rotating at about 9500 rpm or more, the solenoid 40 is turned off because the CPU 40 of the igniter 54 is not supplying power to the solenoid switching transistor 38 (upper column in FIG. 14). And the middle and high speed cams 4 and 5 are in operation (lower column in FIG. 14). If the ignition switch 44 or the kill switch 47 is turned off in this state, the engine stops and the oil pressure of the engine oil drops rapidly (the middle column in FIG. 14), but the solenoid 37 is turned off.
The engine is stopped while the F state is maintained and the middle and high speed cams 4 and 5 are operating.

When the engine is started by turning on the ignition switch 44 and the kill switch 47 in this state, the engine speed is low, and the CPU 40 of the igniter 54 immediately supplies power to the solenoid switching transistor 38 to supply the solenoid 37 Is turned on (upper column in FIG. 14). However, at this point, since the engine speed is low and the oil pressure of the engine oil is also low (the middle column in FIG. 14), the switching of the cams from the middle and high speed cams 4 and 5 to the low speed cam 3 is incomplete (see FIG. 14). 14 lower column) An unpleasant switching sound is generated. In this case, the low-speed cam 3
The switching to is performed several seconds (about 0.2 seconds) after the oil pressure of the engine oil exceeds the level of the cam switchable oil pressure 55.

In contrast to the operation of the igniter 54 described above, FIG.
In the igniter 34 shown in (1), the cam is switched as described below.

When the engine is rotating at about 5000 rpm, the CPU 40 of the igniter 34 supplies power to the solenoid switching transistor 38 and turns on the solenoid 37 (upper column in FIG. 2). In operation (bottom row of FIG. 2).

At this time, when the ignition switch 44 or the kill switch 47 is turned off, the power supply to the ignition coil 35 is cut off, the engine is stopped, and the power supply to the CPU 40 is also cut off. However, since the igniter 34 has the time constant circuit 39,
As shown in the uppermost column of FIG. 2, the voltage at the point B decreases with a time constant from the time when the ignition switch 44 or the kill switch 47 is turned off. When the voltage at the point B reaches a base terminal voltage equal to or lower than the minimum level (switching level) 56 that makes the collector terminal and the emitter terminal of the solenoid switching transistor 38 conductive, the solenoid 37 is turned off and the electromagnet 2 is turned on.
6 is demagnetized, and the spool valve 25 switches the flow of the engine oil to the middle and high speed cams 4 and 5. However,
Ignition switch 44 or kill switch 47
Is turned off, there is a time delay of about 1 to 2 seconds until the voltage at the point B falls below the switching level 56 and the solenoid 37 is turned off (upper column in FIG. 2). On the other hand, after the ignition switch 44 or the kill switch 47 is turned off, the oil pressure of the engine oil becomes about 0.
It becomes 0Kp in about 5 seconds (lower column in FIG. 2). Therefore,
When the solenoid 37 is turned off, the spool valve 2 is turned off.
Even if 5 switches the flow of the engine oil to the middle and high speed cams 4 and 5, the hydraulic actuator 15 does not operate because the oil pressure of the engine oil is 0 Kp, and the cam maintains the state of the low speed cam 3. (Lower column in FIG. 3), no unpleasant cam switching sound is generated.

When the engine is rotating at about 10000 rpm, power is not supplied from the CPU 40 of FIG. 1 to the solenoid switching transistor 38, and the solenoid 37 is turned off (upper column of FIG. 3). The cams 4 and 5 are in the operating state (the lowermost column in FIG. 3). At this time, when the ignition switch 44 or the kill switch 47 in FIG. 1 is turned off, the power supply to the ignition coil 35 is cut off, the engine is stopped, and the power supply to the CPU 40 of the igniter 34 is also cut off. When the engine stops, the oil pressure of the engine oil decreases as shown in the lower column of FIG. On the other hand, even if the power supply to the CPU 40 is cut off, since no current flows to the solenoid switching transistor 38 at a time before that, the solenoid 37 remains in the OFF state (upper column in FIG. 3), and the cam is in the middle. While the state of the high-speed cams 4 and 5 is maintained (the lowermost column in FIG. 3), no uncomfortable cam switching sound is generated.

Thereafter, when the ignition switch 44 and the kill switch 47 are turned on to start the engine, the oil pressure of the engine oil rises as shown in the lower section of FIG. When the ignition switch 44 or the kill switch 47 is turned on, the CPU of the igniter 34 is turned on.
Power is supplied to the CPU 40 from the operating cam determination switch 50 at this time.
5 is in the operating state (at the bottom of FIG. 3). Therefore, the CPU 40 of the igniter 34
Starts the power supply to the solenoid switching transistor 38 only when the engine speed reaches the operation range of the cams 4 and 5 for medium and high speeds of about 9500 rpm or more and then drops to about 9000 rpm or less. At this time, the voltage at the point B gradually rises as shown in the uppermost column of FIG. 3 due to the presence of the time constant circuit 39, and when the switching level reaches or exceeds the switching level 56, the solenoid 37 is turned on (upper column of FIG. 3). When the solenoid 37 is turned on, the engine oil pressure is equal to or higher than the cam switchable oil pressure 55 as shown in the lower section of FIG.
As described above, even when the ignition switch 44 and the kill switch 47 are turned on, the cams do not switch from the medium-speed and high-speed cams 4 and 5 to the low-speed cam 3 in the idling state of the engine. Since the cam is switched at a certain point, the generation of an unpleasant cam switching sound can be prevented.

FIG. 8 is a diagram showing an electric circuit of an ignition / charging system in the first embodiment of the valve train of the four-stroke engine according to the second invention. In the first embodiment, the same parts as those in the first embodiment of the present invention are denoted by the same reference numerals, and description thereof will be omitted.

In the ignition / charging system according to the first embodiment of the second invention, the battery 43 is connected to the ignition switch 44 via the fuse 42, and the downstream side of the regulating rectifier 51 and the ignition switch 44. A delay timer relay 61 is connected to the upstream side,
Further, the solenoid 37 and the igniter 62 of the electromagnet 26 of the oil switching solenoid valve 16 are connected to the delay timer relay 61. That is, the delay timer relay 61 includes the delay circuit 63, the transistor 64, and the relay 65, and the delay circuit 63 is connected to the base terminal of the transistor 64. Also, the relay 65
Is connected to the collector terminal of the transistor 64, and one terminal of the switch 67 of the relay 65 is connected between the ignition switch 44 and the fuse 42. The other terminal of the switch 67 is connected to the CP of the igniter 62.
Connected to U40 and solenoid 37, these C
PU 40 and solenoid 37 are delay timer relay 61
The power is supplied via the relay 65.

When the ignition switch 44 is turned on, power is supplied from the regulating rectifier 51 or the battery 43 to the delay circuit 63 of the delay timer relay 61, and when the collector terminal and the emitter terminal of the transistor 64 are energized, the relay 65 is turned on. Switch 67
Is turned ON. When the switch 67 is turned on, the CPU 40 and the solenoid 37 of the igniter 62 are operated.
Power is supplied from the regulating rectifier 51 or the battery 43. In the first embodiment, cam switching is performed as described below.

When the engine is rotating at, for example, about 5000 rpm, power is supplied from the regulating rectifier 51 and the battery 43 to the delay timer relay 61, the solenoid 37, and the igniter 62. At this time, the voltage at the point C is 12 V (upper column in FIG. 9), and the switch 67 of the relay 65 is turned on. FIG.
As shown in the middle column, the point D voltage is also 12 V, and at this engine speed, the CPU 40 of the igniter 62 supplies power to the solenoid switching transistor 38, so that the solenoid 37 is also turned ON (FIG. 9). Middle column). At this time, the oil pressure of the engine oil is equal to or higher than the cam switchable oil pressure 55 (lower column in FIG. 9).
The low speed cam 3 is operated based on the ON operation of the solenoid 37 (the lowermost column in FIG. 9).

In this state, the ignition switch 44
Is turned off, the delay timer 6 is turned off as shown in FIG.
1 to the delay circuit 63 is a regulated rectifier 5
1, the relay 65, the transistor 64, the solenoid 37, and the CPU 40 of the igniter 62 are supplied from the battery 43. Further, when the ignition switch 44 is turned off, the voltage detected by the detection line 52 becomes 0 V, so that the voltage at the point C sharply increases as shown in the upper section of FIG. 9 (upper column in FIG. 9). The capacitor starts discharging when the voltage at the point C decreases to the discharge starting voltage 68 of the capacitor in the delay circuit 63, and after the discharge time (about 5 seconds) elapses, the voltage between the collector terminal and the emitter terminal of the transistor 64 is reduced. When the power is turned off, the coil 66 of the relay 65 is demagnetized and the switch 67 is turned off. As a result, the voltage at the point D sharply decreases as shown in the middle column of FIG. 9, the power supply to the CPU 40 and the solenoid 37 is cut off, and the solenoid 37 is turned off.
FF operation is performed. On the other hand, the oil pressure of the engine oil gradually decreases as the engine speed decreases (lower column in FIG. 9).
It falls below. Therefore, the solenoid 37 is turned off.
At the time of operation, since the engine oil pressure is already 0 Kp, the switching to the middle and high speed cams 4 and 5 is not performed, and the operable state of the low speed cam 3 is maintained.

When the engine is rotating at about 10,000 rpm, the voltage at the point C is 12 V (FIG. 10).
, The switch 67 of the relay 65 is turned ON,
Although the voltage at point D indicates 12 V (upper middle column in FIG. 10), since the engine speed is in the high speed region and the CPU 40 has stopped supplying power to the solenoid switching transistor 38, the solenoid 37 is turned off. The middle and high speed cams 4 and 5 are operating (the bottom row in FIG. 10).

When the ignition switch 44 is turned OFF in this state, as shown in FIG.
Is supplied from the regulated rectifier 51,
Power is supplied from the battery 43 to the relay 65, the transistor 64, the solenoid 37, and the igniter 62. When the ignition switch 44 is turned off, the engine speed gradually decreases as shown in the uppermost column of FIG. 10, but the voltage at the point C sharply increases because the detection line 52 becomes 0 V, and then the engine speed increases. Accordingly, it gradually decreases (upper column in FIG. 10). The CPU 40 of the igniter 62 starts to supply power to the solenoid switching transistor 38 when the engine speed drops to about 9000 rpm, turns on the solenoid 37 (the middle lower column in FIG. 10), , 5 is switched to the low speed cam 3 (lower column in FIG. 10). At this time, since the engine is rotating at about 9000 rpm,
The oil pressure of the engine oil is sufficiently ensured (Fig. 10
(Lower column), the switching to the low-speed cam 3 is quickly performed without generating an unpleasant switching sound.

Thereafter, as in the case of FIG. 9, when the voltage at the point C decreases to the capacitor discharge start voltage 68 in the delay circuit 63, after about 5 seconds have passed due to the action of the delay circuit 63, the relay 65 The switch 67 is turned off (middle upper column in FIG. 10). When the switch 67 is turned off, the CPU 40 of the igniter 62 and the solenoid 3
The power supply to the power supply 7 is lost, and the solenoid 37 is turned off (middle and lower column in FIG. 10). However, at this point, the engine is already stopped, and the oil pressure of the engine oil is 0 Kp
10 (lower column in FIG. 10), the cam is not switched from the low-speed cam 3 to the middle-high speed cams 4 and 5, and the operable state of the low-speed cam 3 is maintained (bottom of FIG. 10). Field).

In this state, when the ignition switch 44 shown in FIG. 8 is turned ON, power is initially supplied from the battery 43 to the delay timer relay 61, the solenoid 37, and the igniter 42, and the CPU 40 of the igniter 62 supplies power to the solenoid switching transistor 38. To turn on the solenoid 37, but the cam is already
In this case, no uncomfortable cam switching sound is generated.

Further, in the first embodiment, for example, FIG.
When the engine is stopped by operating the engine brake after turning off the ignition switch 44, it takes a long time from the time when the ignition switch 44 is turned off to the time the engine stops, as indicated by the dashed line in the uppermost column. In the meantime, the oil pressure of the engine oil can be maintained at a level higher than the cam switchable oil pressure 55 for a long time (the dashed line in the lower section of FIG. 9). However, if the time from when the ignition switch 44 is turned OFF to when the engine stops is extended, the voltage at the point C is also reduced by the delay circuit 63.
Since the potential equal to or higher than the discharge start voltage 68 of the internal capacitor can be maintained for a long time (the dashed line in the upper section of FIG. 9), the point at which the solenoid 37 is turned off by the action of the delay circuit 63 is also postponed (the middle section of FIG. 9). Chain line). Therefore, also in this case, since the oil pressure of the engine oil is already 0 Kp when the solenoid 37 is turned off, the operating state of the low speed cam 3 is maintained, and the generation of uncomfortable cam switching noise can be prevented.

In the first embodiment of the second invention, the case where the detection line 52 of the regulated rectifier 51 is an external detection type in which the detection line 52 is connected between the ignition switch 44 and the fuse 45 as shown in FIG. But the second
In the second embodiment of the present invention, a regulated rectifier 51 of an internal detection type is used. When the internal detection type regulated rectifier 51 is used, after the ignition switch 44 is turned off, C
Since the point voltage has a pulse shape as shown in FIG. 11, the constant such as the resistance and the capacitor constituting the delay circuit 63 of the delay timer relay 61 is changed, and the voltage at the point C becomes the discharge starting voltage of the capacitor in the delay circuit 63. It is necessary to maintain the ON state of the timer transistor 64 for about 5 seconds from the point when the voltage drops to 68.

[0056]

According to the first aspect of the present invention, a low speed rocker arm which is directly fitted on a rocker shaft and is operated by a low speed cam, and which is mounted on an eccentric large diameter portion of the rocker shaft and is operated by a medium / high speed cam. The low-speed rocker arm and the solenoid valve actuate to switch the flow direction of hydraulic oil to rotate the rocker shaft in the forward and reverse directions, thereby selectively operating the low-speed cam and the medium-high speed cam. A rocker shaft drive mechanism for switching, and an igniter for controlling ON / OFF operation of a solenoid of the solenoid valve based on an engine speed.
Both ends of the low-speed and middle-high-speed rocker arms are disposed so as to overlap on the extension of the axis of the intake / exhaust valve, and one end of the solenoid coil has a battery positive terminal regardless of the ON / OFF operation of the ignition switch. And a time constant circuit is installed in the igniter for connection to the other end of the solenoid coil. Further, the igniter operates when the engine speed is in the low speed range when the middle / high speed cam is operated. However, when the engine speed once rises to the middle and high speed range and then drops to the low speed range, control is performed such that the solenoid is turned ON to operate the low speed cam only for the first time. .

According to a second aspect of the present invention, a low speed rocker arm which is directly fitted to a rocker shaft and is operated by a low speed cam, and which is fitted to an eccentric large diameter portion of the rocker shaft and is operated by a middle / high speed cam. The flow direction of hydraulic oil is switched by operating a low-speed rocker arm and a solenoid valve to rotate the rocker shaft in the forward and reverse directions, thereby selectively switching the operation between the low-speed cam and the middle-high speed cam. A rocker shaft drive mechanism; and an igniter for controlling the ON / OFF operation of the solenoid of the solenoid valve based on the engine speed. Both ends of the low-speed and medium-high speed rocker arms are provided with intake / exhaust valves. The solenoid and the igniter are provided with a battery and an igniter. A voltage is applied to both of the alternator via a delay timer relay via a delay switch, and a delay circuit for controlling ON / OFF of the relay of the delay timer relay includes ON / OFF operation of the ignition switch. Regardless, the voltage is applied from the alternator.

Therefore, according to the first and second aspects of the present invention, by switching between the low speed cam and the middle / high speed cam according to the engine speed, it is possible to improve the engine output within a wide speed range. , Such as an ignition switch for starting / stopping the engine while preventing the cam from being switched due to insufficient hydraulic oil.
It is possible to prevent the occurrence of the cam switching sound at the time of N · OFF.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electric circuit of an ignition / charging system in an embodiment of a valve apparatus of a four-cycle engine according to the first invention.

FIG. 2 is a state diagram showing changes in potentials and cam positions of a valve train controlled when an ignition switch or the like is turned off at low engine speed in the electric circuit of FIG. 1;

FIG. 3 is a state diagram showing changes in each potential and cam position of a valve train controlled when an ignition switch or the like is turned off and then turned on at the time of high engine rotation in the electric circuit of FIG. 1;

FIG. 4 is a perspective view showing a valve train in one embodiment of the first invention.

FIG. 5 is a side view showing an operation state of a low speed cam in the valve train of FIG. 4;

FIG. 6 is a side view showing an operation state of a middle and high speed cam in the valve train of FIG. 4;

FIG. 7 is a sectional view showing a rocker shaft drive mechanism in the valve train of FIG. 4;

FIG. 8 is a diagram showing an electric circuit of an ignition / charging system in the first embodiment of the valve train of the four-stroke engine according to the second invention.

FIG. 9 is a state diagram showing changes in each potential and cam position of a valve train controlled when an ignition switch or the like is turned off at low engine speed in the ignition / charging system of FIG. 8;

10 is a state diagram showing changes in potentials and cam positions of a valve train controlled when an ignition switch or the like is turned off at the time of high engine rotation in the ignition / charging system of FIG. 8;

FIG. 11 is a state diagram showing a change in a point C voltage in a second embodiment of the valve train of a four-stroke engine according to the second invention.

FIG. 12 is a diagram showing an electric circuit of an ignition / charging system which is compared with FIG. 1;

13 is a state diagram showing changes in the positions of a solenoid and a cam that are controlled when an ignition switch or the like is turned off during idling in the ignition / charging system of FIG. 12;

14 is a state diagram showing changes in the positions of a solenoid and a cam which are controlled when an ignition switch or the like is turned OFF and then turned ON at the time of high engine rotation in the ignition / charging system of FIG. 12;

[Description of Signs] 1, 2 Intake / exhaust valve 3 Low-speed cam 4, 5 Medium-high speed cam 7 Low-speed rocker arm 8, 9 Medium-high speed rocker arm 11 Rocker shaft 12 Eccentric bush 13 Rocker shaft drive mechanism 16 Oil switching solenoid valve 34 igniter 37 solenoid 39 time constant circuit 41 alternator 43 battery 44 ignition switch 47 kill switch 49 pickup coil 50 operating cam judgment switch 61 delay timer relay 62 igniter 63 delay circuit 65 relay

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 13/02 F01L 13/00 F02D 17/00 F02D 45/00

Claims (2)

(57) [Claims] A low-speed rocker arm directly fitted to the rocker shaft and operated by a low-speed cam; a low-speed rocker arm fitted to an eccentric large-diameter portion of the rocker shaft and operated by a medium-high-speed cam. A rocker shaft drive mechanism that switches the flow direction of hydraulic oil by operating a solenoid valve to rotate the rocker shaft in the forward and reverse directions, and selectively switches operation between the low-speed cam and the medium-high speed cam. An igniter for controlling the ON / OFF operation of the solenoid of the solenoid valve based on the engine speed. Both ends of the low-speed and medium-high speed rocker arms extend along the axis of the intake / exhaust valve. One end of the solenoid coil is placed ON / OFF of the ignition switch.
Regardless of the F operation, it is connected to the battery plus terminal, a time constant circuit is installed in the igniter for connection to the other end of the solenoid coil, and the igniter is
Even when the engine speed is in the low speed range when the above-mentioned medium / high speed cam is activated, the solenoid is turned ON only when the engine speed once rises to the medium / high speed range and then drops to the low speed range. A valve operating device for a four-stroke engine, which controls the low-speed cam to operate. 2. A low-speed rocker arm fitted directly to the rocker shaft and operated by a low-speed cam, and a low-speed rocker arm fitted to an eccentric large-diameter portion of the rocker shaft and operated by a medium-high-speed cam. A rocker shaft drive mechanism that switches the flow direction of hydraulic oil by operating a solenoid valve to rotate the rocker shaft in the forward and reverse directions, and selectively switches operation between the low-speed cam and the medium-high speed cam. An igniter for controlling the ON / OFF operation of the solenoid of the solenoid valve based on the engine speed. Both ends of the low-speed and medium-high speed rocker arms extend along the axis of the intake / exhaust valve. The solenoid and the igniter are placed one on top of the other via a battery and an ignition switch. Both voltage via the relay delay timer relay is provided to be applied from the alternator, the delay circuit further controls the ON · OFF of the relay of the delay timer relay, ON of the ignition switch
A valve train for a four-stroke engine, wherein a voltage is applied from an alternator irrespective of an OFF operation.