Internal-combustion engines – Cooling – With jacketed head and/or cylinder
Reexamination Certificate
1999-08-12
2001-05-22
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Cooling
With jacketed head and/or cylinder
C123S04100E
Reexamination Certificate
active
06234119
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention pertains to a process for controlling a change-over of a rotative direction of a two cycle internal combustion engine which is used for driving a travelling machine and a system used for practicing the aforementioned process.
BACKGROUND OF THE INVENTION
In order to drive a travelling machine such as a scooter, a snowmobile, a buggy car or the like which makes much of simplicity, there has been used a small-sized two cycle internal combustion engine as a drive power and a centrifugal clutch type continuously variable transmission as a transmission to transmit an output power of the internal combustion engine to drive wheels of the travelling machine. Many travelling machines have no reverse gear assembled in the continuously variable transmission from a requirement of important items of small-size, lightness and inexpensiveness.
Since vehicles having no reverse gear assembled in the transmission cannot move in a backward direction, they have to change their direction by lifting the whole vehicles when their travelling direction should be reversed, which causes them to have a poor manipulation.
In order to enable reversion of the travelling direction of the travelling machine having no reverse gear provided therein, the rotative direction of the internal combustion engine has to be reversed, as required.
The two cycle internal combustion engine can rotate in both of forward and reverse directions and can be normally driven either in the forward direction and in the reverse direction.
More particularly, as an ignition position (an angular position of a rotary shaft of the two cycle internal combustion engine as it is ignited) of the engine is advanced to an over spark advance position (a position further advancing beyond the optimum maximum spark advance position on its normal operation), a piston moving toward a top dead center thereof is forced back far away from the top dead center so that the rotative direction of the engine is reversed. After the reversion of the rotative direction of the engine is checked, the ignition position is returned to the optimum ignition position where the rotative direction of the engine reverse to the former direction can be maintained. Thus, the two cycle internal combustion engine can continue to rotate in the condition in which the rotative direction is reversed.
There has been well known a process in which the rotative direction of the two cycle internal combustion engine is reversed by controlling its reversion while the ignition position of the engine is advanced to the over spark advance position necessary for reversing the rotative direction of the engine when a reversion instruction is given instructing the reversion of the engine.
FIG. 9
illustrates an algorithm of interruption routine which is conducted by a microcomputer as a reversion instruction is generated by a driver when a rotative direction instruction switch is operated in a prior art process for controlling the change-over of the rotative direction of the engine.
With this algorithm followed, when the reversion instruction is given, a step
1
of
FIG. 9
is conducted wherein it is confirmed whether the rotative direction of the engine being now driven is identical to that instructed by the driver.
As a result of the confirmation of the step
1
, when it is confirmed that the rotative direction of the engine being now driven is not identical to that instructed by the driver, the process is moved to a step
2
of
FIG. 9
wherein the reversion control is made. In this reversion control, the ignition position of the engine is advanced to the over spark advance position necessary for reversing the rotative direction of the engine and the over spark advance condition of the ignition position is maintained until the reversion of the rotative direction of the engine is confirmed.
In the reversion control of the step
2
, as the reversion of the rotative direction of the engine is confirmed, the process is moved to a step
3
of
FIG. 9
wherein the ignition control is moved to the normal ignition position while the rotative direction is maintained in the reverse condition. Thus, the engine continues to be driven in the condition of reversion of the rotative direction of the engine.
With the algorithm of
FIG. 9
followed, if the driver unintentionally operates the rotative direction instruction switch during travelling, or if a reversion instruction generator means such as a rotative direction instruction switch breaks down, then the travelling machine will quickly move back because the engine abruptly rotates in the reverse direction.
If the throttle valve is in the state of being opened even though the travelling machine is at a stop when the driver operates the rotative direction instruction switch, the travelling machine will disadvantageously travel in an abrupt manner because the engine is quickly accelerated as soon as the rotative direction of the engine is reversed.
These undesirable conditions should be avoided in order to make a practical use of the travelling machine having a system of reversing its travelling direction by reversing the rotative direction of the engine mounted thereon.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the invention to provide a process of controlling a change-over of a rotative direction of a two cycle internal combustion engine adapted to avoid reversion of the rotative direction of the engine when a reversion instruction is erroneously generated due to an unintentional operation by the driver or due to a reversion instruction generator broken down in the conditions of the undesirable reversion of the engine.
It is another object of the invention to provide a system of controlling a change-over of a rotative direction of a two cycle internal combustion engine adapted to avoid reversion of the rotative direction of the engine when a reversion instruction is erroneously generated due to an unintentional operation by the driver or due to a reversion instruction generator broken down in the conditions of the undesirable reversion of the engine.
In accordance with one aspect of the present invention, there is provided a process of controlling a change-over of a rotative direction of a two cycle internal combustion engine used for driving a travelling machine comprising the steps of controlling the change-over of the rotative direction of the engine by advancing an ignition position of the engine to an over spark advance position necessary for reversing the rotative direction of the engine when a reversion instruction is given instructing the reversion of the rotative direction of the engine; confirming whether reversion allowance conditions are satisfied which are required for reversing the rotative direction of the engine while the travelling machine is driven with safety maintained before the step of controlling the change-over of the rotative direction of the engine whereby the step of controlling the change-over is allowed to start when it is confirmed by the step of confirming the reversion allowance conditions that the reversion allowance conditions are satisfied, but the step of controlling the change-over is prohibited from starting when it is confirmed that at least one of the reversion allowance conditions is dissatisfied.
In the step of confirming the reversion allowance conditions, they preferably include a revolution of the internal combustion engine being equal to or less than a set value and an opening degree of the throttle valve for adjusting an intake amount of the internal combustion engine being equal to or less than a set value.
More particularly, in the step of confirming the reversion allowance conditions before the step of controlling the reversion starts, the satisfaction of the reversion allowance conditions is confirmed when the revolution of the internal combustion engine is equal to or less than the set value, which means that the revolution of the engine is sufficiently lower for never providing any undesirable situation to the driver when the ro
Sasaki Kouji
Tsukada Yoshikazu
Harris Katrina B.
Kokusan Denki Co. Ltd.
Pearne & Gordon LLP
Wolfe Willis R.
LandOfFree
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