Throttles

Details Throttles Throttles

2001-04-25

2002-12-03

Hirsch, Paul J. (Department: 3747)

Internal-combustion engines

Engine speed regulator

Open loop condition responsive

C123S361000

Reexamination Certificate

active

06488009

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to throttles for a vehicle engine, such as an internal combustion engine, and more particularly, to throttle valve control devices for controlling a throttle valve disposed within the throttle.
2. Description of the Related Art
A known throttle valve control device is disclosed in Japanese Laid-Open Patent Publication No. 3-271528 and is reproduced in
FIGS. 9
to
14
. As shown in
FIG. 9
, a throttle body
101
rotatably supports a throttle shaft
102
. A throttle valve (not shown) is attached to throttle shaft
102
. As shown in
FIG. 11
, a throttle gear
105
is mounted on the end of throttle shaft
102
. Further, a relief lever
109
is pivotally mounted on throttle shaft
102
between throttle body
101
and throttle gear
105
.
A clearance is provided between relief lever
109
and throttle shaft
102
so as to permit relief lever
109
to pivot. Further, clearances are also provided between relief lever
109
and throttle body
101
and between relief lever
109
and throttle gear
105
. Therefore, as shown in
FIGS. 11 and 13
, relief lever
109
may tilt with respect to throttle shaft
102
. As shown in
FIG. 11
, a return spring
111
is disposed around throttle body
101
and one end
111
a
of return spring
111
engages relief lever
109
. Return spring
111
urges relief lever
109
in the valve closing direction with respect to throttle body
101
. Further, a relief spring
110
is disposed within relief lever
109
and is connected to throttle gear
105
. Relief spring
110
urges throttle gear
105
in the valve opening direction with respect to relief lever
109
.
As shown in
FIG. 9
, first contact members (first contact means)
120
b
are provided on throttle gear
105
and relief lever
109
. First contact members
120
b
contact each other when throttle gear
105
pivots to a predetermined pivot position in the valve opening direction. Further, second contact members (second contact means)
120
a
are provided on throttle body
101
and relief lever
109
. Second contact members
120
a
contact each other when relief lever
109
pivots to a predetermined pivot position in the valve closing direction.
During operation, the position of the throttle valve within throttle body
101
is determined by the amount of torque supplied by a throttle valve controlling motor (not shown) to the throttle shaft
102
, which torque acts against return spring
109
. On the other hand, when the engine is not operated, the throttle valve control motor does not supply any torque to adjust the position of the throttle valve as shown in FIG.
9
. In this state, return spring
111
urges throttle shaft
102
towards an initial or standby open position in which first contact members
120
b
contact each other at contact position
120
B and second contact members
120
a
contact each other at contact position
120
A. In the initial or standby open position, the throttle valve is slightly opened in order to permit airflow through an intake air passage in the throttle body
101
. Thus, even if the throttle valve and/or throttle shaft
102
freezes in a cold environment, or adhesive materials, such as combustion products, deposit in the throttle and cause the throttle valve to be locked or stuck in the initial or standby position, airflow is still supplied to the engine. Therefore, the engine will reliably start even under these conditions.
When the throttle valve rotates in the valve opening direction from the initial or standby open position, first contact members
120
b
will continue contact each other at contact position
120
B, as shown in FIG.
10
. However, throttle gear
105
and relief lever
109
will pivot about rotational axis L of throttle shaft
102
. When the throttle valve rotates from the initial or standby open position in the valve closing direction, second contact members
120
a
prevent rotation of relief lever
109
, as shown in FIG.
12
. Thus, in this state, only the throttle gear
105
will pivot about rotational axis L.
Additional description concerning Japanese Laid-Open Patent Publication No. 3-271528 can be found, for example, in the background sections of U.S. Pat. Nos. 5,735,243 and 6,164,623.
PROBLEM OF THE RELATED ART
As a result of research performed by the inventors, the known throttle exhibits hysteresis around the initial or standby open position, which is believed to be caused for the following reasons. As shown in
FIG. 9
, contact position
120
B of first contact members
120
b
and contact position
120
A of second contact members
120
a
are located in separate positions that are on opposite sides of a plane P that is perpendicular to rotational axis L. Plane P includes position
120
C at which the urging force of return spring
111
acts on relief lever
109
. Specifically, contact position
120
B of first contact members
120
b
is located on one side of plane P, i.e. below plane P as viewed in FIG.
9
. Contact position
120
A of second contact members
120
a
is located on the other side of plane P, i.e. above plane P as viewed in FIG.
9
. As a result, relief lever
109
will tilt or pivot with respect to plane P when relief lever
109
moves from a first position (FIG.
10
), in which the first contact members
120
b
contact each other and throttle gear
105
and relief lever
109
pivot, to a second position (FIG.
12
), in which second contact members
120
a
prevent further rotation of relief lever
109
and only the throttle gear
105
can pivot.
Specifically, when the throttle valve rotates to the pivot position shown in
FIG. 10
, first contact members
120
b
contact each other on one side of plane P and relief lever
109
tilts downward to the right. On the other hand, when the throttle valve rotates to the pivot position shown in
FIG. 12
, second contact members
120
a
contact each other on the other side of plane P and relief lever
109
tilts downward to the left.
FIG. 14
shows a graph that relates the operating torque required by the throttle valve control motor to move the throttle valve to the various pivot positions within the working range of the known throttle described in Japanese Laid-open Patent Publication 3-271528. The abscissa represents the pivot position of the throttle valve (throttle opening position) and the ordinate represents the operating torque required by the throttle valve control motor to move the throttle valve to the respective pivot positions. As shown by
FIG. 14
, the operating torque is zero at the initial or standby open position B. Moreover, in the known throttle, the operating torque is also zero in a range between valve position A and valve position C, which is hysteresis with respect to the initial or standby open position. If the throttle exhibits a relatively large hysteresis, the initial or standby open position will vary during operation and thus, the amount of airflow into the throttle in the initial or standby mode will vary. However, the amount of airflow should be precisely controlled in the initial or standby open position. Thus, the known throttle exhibits a disadvantage, which is believed to be caused by the fact that the relief lever
109
pivots with respect to plane P when the throttle valve moves to the initial or standby open position B.
SUMMARY OF THE INVENTION
It is, accordingly, one object of the present teachings to provide improved throttles and more particularly, devices for controlling the position of a throttle valve disposed within the throttle.
In one aspect of the present teachings, a relief lever is preferably prevented from tilting with respect to plane P during operation, which plane P is perpendicular, or substantially perpendicular, to the rotational axis L of a throttle shaft. Therefore, the position of the throttle valve can be controlled more precisely.
In one embodiment of the present teachings, first contact members are provided on the throttle gear and the relief lever and second contact members are provided on the throttle body and the relief lever. Both the firs

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