Engine controller

Details Engine controller Engine controller

2000-06-21

2002-04-09

Mohanty, Bibhu (Department: 3747)

Internal-combustion engines

Engine speed regulator

Engine speed reduction by partial or complete omission of...

C123S333000

Reexamination Certificate

active

06367445

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine controller and more particularly to an engine controller which controls an engine revolution by operating a throttle lever linked to a throttle valve.
2. Description of the Related Art
An engine that has conventionally been used as a motor for vehicles such as snowmobiles has a throttle lever to adjust the engine revolution. The throttle lever is connected through a throttle wire to a throttle valve installed in an air intake passage. An oscillating action of the throttle lever causes the throttle valve to rotate to increase or reduce an open area in the intake passage, adjusting the amount of air intake into the engine and therefore the engine revolution.
The engine with the above construction has a possibility of a so-called throttle valve recovery failure, a trouble caused by snow which, after adhering to a throttle shaft and others supporting the throttle valve, freezes to hold the throttle valve immovable in an open state while the snowmobile is traveling over snow. Once the throttle valve recovery failure occurs, the engine revolution remains high and cannot be lowered by the operation of the throttle lever, making normal traveling impossible.
To prevent this, conventional practice takes advantage of the fact that releasing the throttle lever when the throttle valve fails to recover causes the throttle wire to slacken. This slack of the throttle wire is checked. When the throttle wire is detected to be slack, it is decided that the throttle valve recovery failure occurs and a control is performed to stop the engine.
In recent years, snowmobiles for child use are being manufactured. Child snowmobiles have a governor in the engine to limit the maximum engine revolution and therefore the maximum speed to a moderate level.
FIG. 3
is a side view of an engine equipped with a governor. An engine
1
has a governor (not shown) in a crankcase and a governor shaft
2
of the governor projects from the side of the engine
1
.
The governor shaft
2
can rotate through a predetermined range of angle, and a governor mechanism narrows the rotatable range of angle as the engine revolution increases. The governor shaft
2
is securely attached with a base end of a governor lever
3
. The governor lever
3
extends vertically along the side surface of the engine
1
. As the governor shaft
2
pivots, the front end of the governor lever
3
oscillates left and right, with its oscillation range being narrowed in a direction away from a carburetor
11
described later (toward left in
FIG. 3
) as the engine revolution rises.
The governor lever
3
is connected through a governor spring
6
to a speed control lever
5
provided on an extension of the governor lever oscillation direction. The governor spring
6
urges the governor lever
3
and the speed control lever
5
toward each other.
The speed control lever
5
is rotatably mounted on the engine
1
so that it can oscillate the governor lever
3
. The speed control lever
5
is attached with one end of the throttle wire
7
so that it can be oscillated.
The other end of the throttle wire
7
is secured to a throttle lever not shown, which is structured to be able to pull the throttle wire by its oscillation operation.
Hence, the oscillation operation of the throttle lever pulls the throttle wire
7
, which oscillates the speed control lever
5
to pull the governor spring
6
causing the governor lever
3
to oscillate toward the carburetor
11
.
The governor lever
3
is connected through a governor rod
10
to the carburetor
11
installed below the speed control lever
5
. The governor rod
10
extends parallel to the governor spring
6
, with one end thereof connected to the governor lever
3
and the other end to a throttle arm
15
of the carburetor
11
.
The throttle arm
15
is secured to the upper end of a throttle shaft
13
pivotally supported on the carburetor
11
. The throttle arm
15
is connected with the governor rod
10
at a point offset from the axis center of the throttle shaft
13
. The throttle shaft
13
is securely attached with a throttle valve
12
and is urged at all times by an urging means not shown to pivot in a direction that will reduce the opening area of an intake passage
14
.
When the governor lever
3
is oscillated toward the carburetor
11
by the oscillating action of the speed control lever
5
, the governor rod
10
pivots the throttle arm
15
in a direction that will cause the throttle valve
12
to expand the opening area of the intake passage
14
. When the governor lever
3
is oscillated away from the carburetor
11
, the governor rod
10
pivots the throttle arm
15
in a direction that will cause the throttle valve
12
to reduce the opening area of the intake passage
14
.
Hence, as the governor lever
3
is oscillated toward the carburetor
11
by the oscillating action of the throttle lever, the throttle arm
15
is pivoted causing the throttle valve
12
to rotate in a direction that will expand the opening area of the intake passage
14
.
When the throttle lever is rendered unoperated, the throttle wire
7
is returned, eliminating the force that has rotated the throttle valve
12
against the urging force of the urging means of the throttle shaft
13
, with the result that the throttle valve
12
is pivoted in a direction that will reduce the opening area. This in turn pivots the throttle arm
15
, oscillating the governor lever
3
away from the carburetor
11
.
The range of oscillation of the governor lever
3
is narrowed by the governor in a direction away from the carburetor
11
as the engine revolution increases, so that the pivoting motion of the throttle valve
12
in a direction that increases the opening area is limited as the engine revolution speed increases.
If an attempt is made to oscillate the throttle lever to cause the governor lever
3
to oscillate out of the narrowed oscillation range toward the carburetor
11
, the governor spring
6
is extended elongating the distance between the governor lever
3
and the speed control lever
5
.
Hence, the governor lever
3
is prevented from being oscillated out of the narrowed oscillation range toward the carburetor
11
, with only the throttle lever and the speed control lever
5
oscillated. Thus, the throttle valve
12
increases or reduces the opening area within the narrowed oscillation range of the governor lever
3
.
In the case described above, because the governor spring
6
is disposed between the speed control lever
5
and the governor lever
3
and pulls the throttle wire
7
at all times, the throttle wire
7
will not slacken if the throttle valve
12
fails to recover.
Hence, the conventional method of detecting the slack of the throttle wire cannot detect the throttle valve recovery failure. There is a possibility therefore that the engine revolution may be kept high even when the throttle lever is rendered unoperated, making normal traveling impossible.
SUMMARY OF THE INVENTION
The present invention has been accomplished to overcome the above-described problem and to provide an engine controller that prevents the engine operation from continuing due to the throttle valve recovery failure.
To solve the problem described above, the engine controller of the invention according to a first aspect is characterized in that when a throttle lever is in an unoperated state and an engine revolution higher than a set revolution has been maintained for a set period of time, the engine controller decides that a throttle valve recovery failure has occurred and performs a control to stop the operation of the engine.
With this invention, when the throttle lever is not operated and the engine revolution higher than a set revolution has been maintained for a set period of time, it is decided that a throttle valve recovery failure has occurred for some reason and the operation of the engine is stopped.
Hence it is possible to prevent the operation of the engine from being continued against the will of the operator and, when

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