Material or article handling – Vehicle attached auxiliary carriers – For rim – tire – or wheel
Reexamination Certificate
2000-06-06
2002-06-25
Krizek, Janice L. (Department: 3652)
Material or article handling
Vehicle attached auxiliary carriers
For rim, tire, or wheel
C254S323000
Reexamination Certificate
active
06409454
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mechanism of preventing breakage of a member for suspending a spare wheel in an apparatus for holding a spare wheel to a motor vehicle.
2. Prior Art
1) A spare wheel holding apparatus is provided with a wheel support member for supporting a spare wheel, and a winding device of large reduction ratio for winding up the wheel support member. The wheel support member is connected to the falling end of a suspending member such as a chain or a wire rope of the winding device.
In a large transportation vehicle such as a truck or a middle or small passenger car such as a wagon, as shown in
FIG. 3
, a winding device of a spare wheel holding apparatus is installed at the lower side of a car body V, and a spare wheel T is wound up and held to the lower surface of the car body V.
In the case that the spare wheel T is held to the lower surface of the car body V, being different from the case that the spare wheel is stored in the car body, when the motor vehicle collides, large forces may be applied to the spare wheel and a large winding-off force may be applied to the suspending member of the winding device.
When the large winding-off force is applied to the suspending member of the winding device, since the winding device has large reduction ratio, the suspending member is not wound off and is broken. If the suspending member is broken, the spare wheel and the wheel support member are separated from the car body and run with inertia on a road and may collide with a walker, other motor vehicle or the like, resulting in dangerous state.
2) The present inventor has invented a spare wheel holding apparatus for preventing breakage of a suspending member of a winding device, as disclosed in JP-B 2768661.
In the spare wheel holding apparatus, a winding device is constituted by a case having vertical cross-section in nearly portal shape, and a main shaft is supported to a front side plate and a rear side plate of the case, and a winding drum on which a suspending member is to be wound is fitted rotatable to the main shaft, and a planetary gear mechanism having large reduction ratio is provided.
The planetary gear mechanism is constituted in that an internal gear is provided concentrically to the side surface of the winding drum, an eccentric cam is provided on the main shaft, an external gear is fitted rotatable to the eccentric cam, the internal gear and the external gear are meshed with each other in relation of the inside and the outside, and a rotation restricting plate is fixed to the side surface of the external gear so that the left end or the right end of the rotation restricting plate abuts on the top plate of the case thereby the rotation is restricted. When the winding-off force is applied to the suspending member, the right end of the rotation restricting plate abuts on the top plate of the case.
The right end of the rotation restricting plate is made desired weak strength. If the winding-off force applied to the suspending member is larger than that during normal use, the weak right end of the rotation restricting plate is broken, and the winding drum is rotated reversely and the suspending member is wound off thereby the breakage of the suspending member is prevented.
In such a spare wheel holding apparatus where breakage of a suspending member of a winding device is prevented, on the occasion that large winding-off force is applied to the suspending member by the collision of a motor vehicle and a rotation restricting plate is broken at the weak right end and a winding drum is rotated reversely and the winding member is wound off, when the winding drum is rotated reversely by turn of about three-fourths, the strong left end of the rotation restricting plate abuts on the top plate of the case, and the reverse rotation of the winding drum is stopped and the suspending member is no more wound off.
If the large winding-off force is applied to the suspending member even after the strong left end of the rotation restricting plate abuts on the top plate of the case and the reverse rotation of the winding drum is stopped, the suspending member is not wound off and will be broken. In the case that large winding-off force is applied to the suspending member continuously or intermittently for a long time, it is difficult to prevent the breakage of the suspending member securely.
In the weak right end of the rotation restricting plate, in order to set the strength to a desired value, thickness or shape is adjusted. However, when the thickness of the rotation restricting plate is adjusted, the range of increasing or decreasing the thickness is narrow. Also when the shape of the rotation restricting plate is adjusted, in order to correct a punch and a die for blanking the rotation restricting plate much labor is required.
Setting of the strength in the weak right end of the rotation restricting plate is not easy. Setting of the winding-off force for the suspending member of the winding device to start the winding-off is difficult.
Even if the winding-off force applied to the suspending member is the same, the weak right end of the rotation restricting plate may be broken or may not be broken depending on the position of the eccentric cam. In other words, the winding-off force of the suspending member that the weak right end of the rotation restricting plate is broken is different depending on the position of the eccentric cam. Consequently it is very difficult that the weak right end of the rotation restricting plate is always broken and the winding drum is rotated reversely when the winding-off force applied to the suspending member becomes a definite value or more.
In order to clarify the reason, the state that the winding-off force is applied to the suspending member will be considered from the standpoint of mechanics.
As shown in FIG.
6
(
a
), if winding-off force W is applied to a suspending member
8
, winding-off, moment W·a will be generated about the rotation center axis of the main shaft
3
, where “a” is a definite value and means distance between the winding-off force W and the rotation center axis of the main shaft
3
, i.e., the length of the arm of the winding-off moment.
In FIG.
6
(
a
), by the winding-off moment W·a in the counterclockwise direction, a winding drum
6
and an internal gear as one body, an external gear and a rotation restricting plate
31
as one body, and a main shaft
3
and an eccentric cam
9
as one body are subjected to the rotational force in the counterclockwise direction, and the weak right end
32
of the rotation restricting plate
31
abuts on a top plate of the case
2
. The right end
32
of the rotation restricting plate
31
is subjected to reaction force from the contact point position of the top plate of the case
2
with the right end
32
. Then by the reaction force, moment in the clockwise direction about the rotation center axis of the main shaft
3
is generated in the external gear and the rotation restricting plate
31
as one body, the winding drum
6
and the internal gear as one body, and the main shaft
3
and the eccentric cam
9
as one body. The moment in the clockwise direction by the reaction force balances with the winding-off moment W·a in the counterclockwise direction.
As shown in FIG.
6
(
a
), when the center of the eccentric cam
9
is positioned at the right upper side of the rotation center axis of the main shaft
3
and gets near the contact point of the right end of the rotation restricting plate
31
with the top plate of the case
2
, the distance between the contact point and the rotation center axis of the main shaft
3
becomes L
1
. The distance L
1
is the length of the arm of the clockwise moment by the reaction force R
1
. The clockwise moment R
1
·L
1
by the reaction force R
1
balances with the counterclockwise winding-off moment W·a.
On the contrary, as shown in FIG.
6
(
b
), when the center of the eccentric cam
9
is positioned at the left lower side of the rotation center axis of the main shaft
3
and gets aw
Krizek Janice L.
McDermott & Will & Emery
Sankokiki Kabushiki Kaisha
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