Land vehicles – Suspension modification enacted during travel – Riding or suspension height
Reexamination Certificate
1998-11-13
2001-10-30
Dickson, Paul N. (Department: 3618)
Land vehicles
Suspension modification enacted during travel
Riding or suspension height
C280S006157, C073S866100
Reexamination Certificate
active
06308962
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an industrial vehicle and an axle pivot angle detecting apparatus for an industrial vehicle having a pivotal axle.
In a typical industrial vehicle such as a forklift, an axle for supporting the rear wheels pivots relative to a body frame for stabilizing the body frame. However, if such a forklift is steered to change directions, lateral force generated by centrifugal force acts on the vehicle and tilts the forklift. The tilting may incline the body frame and thus destabilize the vehicle.
Japanese Unexamined Patent Publication No. 58-211903 describes a forklift that has a detecting apparatus for detecting centrifugal force. If the detected centrifugal force exceeds a predetermined value when the vehicle changes directions, a locking mechanism locks the axle to the body frame to minimize tilting of the body frame. The forklift thus turns in a stable manner.
Japanese Unexamined Patent Publication No. 58-167215 describes a forklift that has a detecting apparatus for detecting the weight of a load on forks and the height of the forks. If the detected load weight and the fork height exceed predetermined threshold values, a locking mechanism locks the axle.
Japanese Unexamined Patent Publication No. 9-315125, which was filed by the present assignee, describes an axle locking apparatus illustrated in FIG.
12
. Rear wheels
91
are supported by a rear axle
92
. The rear axle
92
is pivotally supported on a frame
93
by a center pin
94
. A hydraulic damper
95
is located between the rear axle
92
and the frame
93
. An electromagnetic valve
96
is located on the damper
95
. A controller (not shown) excites or de-excites a solenoid of the valve
96
thereby locking or unlocking the damper
95
. Specifically, the controller causes the damper
95
to lock the rear axle
92
when the fork height and the cargo weight are greater than predetermined threshold values. The damper
95
functions as a device for locking the rear axle
92
as well as a shock absorber. The use of the damper
95
thus reduces the number of the parts in the apparatus and simplifies the construction.
Since the threshold values are set only for the fork height and the cargo weight, the rear axle
92
may be locked while tilted relative to the frame
93
. For example, the rear axle
92
may be locked even if one of the rear wheels
91
is on a step or a bump. When the forklift moves to a flat road surface thereafter, the raised rear wheel
91
loses contact with the road surface. That is, since the center of gravity is relatively close to the front wheels when the forklift carries a relatively heavy load at a relatively high position, the rear wheel
91
that was lifted by a bump remains raised. As a result, the vehicle is supported only by three wheels, or by the front wheels and the other rear wheel
91
. This destabilizes the vehicle.
Further, unlocking the rear axle
92
while one of the rear wheels
91
is raised causes the raised wheel
91
to fall on the ground, which results in a great shock. This may cause cargo on a pallet carried by the forks to shift. Particularly, when the rear axle is locked, the fork height and the cargo weight are greater than the threshold values, that is, the carried cargo is heavy and is held at a high position. In this state, unlocking the rear axle
92
may shift the cargo and disrupt the operation.
The locking mechanism according to the Publication No. 58-167215 locks the axle by inserting two blocks between the body frame and the axle. However, the blocks cannot be inserted when the axle is pivoted since pivoting of the axle narrows the space between the axle and the body frame. In other words, when raised, the axle cannot be locked. Therefore, there is no subsequent shock caused by a falling wheel.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide an axle pivot angle detecting apparatus for industrial vehicles that detects the pivot angle of an axle supporting wheels and controls locking of the axle in accordance with the pivot angle of the axle.
To achieve and foregoing and other objectives and in accordance with the purpose of the present invention an axle pivot angle detecting apparatus for an industrial vehicle is provided. The vehicle has an axle that supports a wheel and is pivotally supported on a frame about a pivot axis. The apparatus includes a detector for detecting the pivot angle of the axle and a converter for converting pivot motion of the axle into rotational or linear motion. The detector is located on the frame or the axle. The converter actuates the detector in accordance with the converted motion and is spaced from the pivot axis.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 4838574 (1989-06-01), Baraszu
patent: 5947516 (1999-09-01), Ishikawa
patent: 6015155 (2000-01-01), Brookes et al.
patent: 6056501 (2000-05-01), Ishikawa et al.
patent: 6082742 (2000-07-01), Ishikawa
patent: 2230439Y (1996-07-01), None
patent: 58-167216 (1983-10-01), None
patent: 58-167215 (1983-10-01), None
patent: 58-211903 (1983-12-01), None
patent: 59-050804 (1984-03-01), None
patent: 9-286218 (1997-11-01), None
patent: 9-315125 (1997-12-01), None
Fujimori Hiroyuki
Ishikawa Kazuo
Komori Kazuo
Ogawa Takaki
Suzuki Masakatsu
Dickson Paul N.
Fleming Faye M.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
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