Elevator – industrial lift truck – or stationary lift for vehicle – Industrial lift truck or required component thereof
Reissue Patent
1999-07-23
2001-06-12
Olszewski, Robert P. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Industrial lift truck or required component thereof
C414S642000, C701S050000, C340S429000
Reissue Patent
active
RE037215
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a remote viewing method and apparatus for use on fork lift trucks. This invention has particular application to those fork lift trucks where the forks can be raised above the head of the operator causing the operator difficulty in visually aligning the forks to a load or a load on the fork to an opening in a storage rack.
In many materials handling vehicles, such as a rider-reach truck or a three- or four-wheel counterbalanced truck, a pair of movable, load carrying forks are mounted on a carriage for vertical movement on the mast of the truck. A camera has sometimes been mounted near the heel of the forks to view the scene in front of the forks, and to display that scene on a monitor mounted in view of the operator. Such an arrangement is helpful, provided the camera is properly positioned so that its view is properly aligned with the forks; however, the view of a camera in this location will be blocked when a pallet is placed on the forks. With a load on the forks, the best position for the camera is below the bottom of the load for use in operator viewing under-clearance or viewing alignment with a target below the load; however, in this position, the camera is subject to damage when the forks are lowered near the floor on which the truck is operating. If the camera is fixed positioned to be clear of the floor when the forks are fully lowered, then its view will be too high to be effective for viewing below the forks and load.
The operator view problem is exacerbated on double reach trucks, that is, trucks with scissors mechanisms that permit the forks to be doubly extended, and thus pick up and deposit loads twice the storage depth distance of a single pallet. The operator's view of the double deep load position in the rack is not visible from this position.
Some lift trucks provide a fork tilt indicator, however, these indicators measure fork tilt relative to the truck's mast, not relative to a horizontal plane. Further, monitoring fork tilt either by sensing the vertical component of the fork or at the heel of the fork will not take into consideration the deflection of the fork away from the mast due to the weight of a load.
SUMMARY OF THE INVENTION
The present invention includes a fork level sensor located in the forks, away from the vertical mast of a lift truck, which sensor detects the true level of the forks, with and without a load on the forks.
This invention also includes a camera, which is equipped with a horizontal plane reticle and mounted on a vertically movable carriage assembly and which is protected from damage and contact with the floor when the forks are in their lowermost position. The camera is lowered to a first predetermined position below the forks and load when the forks are raised, which provides the camera with a view that is optimum for viewing a target for vertical height position of the forks or load. When used on a double reach truck with the forks extended, the camera is placed at a second predetermined location relative to the forks, which is above the first predetermined position and which provides the camera with a view above the load support beam or rail of a rack near which the truck is usually placed when operating in this mode. A second camera at a different height may also be used and switching means provided to allow the operator to obtain a view above the load support beam.
A video monitor is provided for use by the operator which, in addition to providing a horizontal plane reticle and a picture of the view observed by the camera, also provides a fork level indicator, and an indicator showing the truck functions selected by the operator. As used herein, the reticle includes a single horizontal line extending across the face of the monitor and a single vertical line at the center of view. This unique presentation aids the operator in controlling the operation of the truck, including the vertical, horizontal and level position of the forks, by reference to that monitor.
It is therefore an object of this invention to provide a level sensor for the forks of a fork lift truck which provides an operator with a true indication of the plane of the forks, with and without load, relative to a horizontal plane.
It is another object of this invention to provide a fork lift truck with a camera which is aligned to define a horizontal plane a predetermined distance below the forks and a visual monitor which includes a representation of the horizontal plane to aid an operator in positioning the forks vertically relative to a pallet or storage rack, particularly when the forks are raised above the operators head.
It is also an object of this invention to provide a vision system for a fork lift truck whereby an operator, by reference to a video monitor, can ascertain and adjust the level position of the forks and the horizontal elevation of the forks relative to a storage rack.
It is a further object of this invention to provide a fork lift truck including a pair of forks for supporting a load, means for raising and lowering the forks, means for tilting the forks relative to the body of the truck, a level sensor mounted on at least one of the forks for providing an indication of the level of the forks with respect to a horizontal plane, a display terminal mounted for viewing by an operator, and means responsive to the level sensor for displaying an indication of the level position of the forks with respect to a horizontal plane on the display terminal thereby to assist the operator in adjusting the level of the forks prior to loading, moving or unloading a load from the forks. Further, the level sensor may be mounted approximately midway the length of the fork.
It is another object of this invention to provide a fork lift truck with a vision system that provides useful images to an operator regarding the elevation of the forks or load for position to a storage rack. It is also an object of this invention to provide the operator with a view of the forks or load while at the same time providing information regarding which function of the truck controls has been selected.
It is a still further object of this invention to provide a lift truck with multiple views, either from a single, movable camera, or from multiple cameras.
It is a yet another object of this invention to provide a fork lift truck including a mast assembly, a carriage assembly mounted for vertical movement in the mast assembly, a pair of forks extending from the carriage assembly for supporting a load, means for raising and lowering the carriage assembly, a camera mounted below the plane of the bottom of the load, the camera having a horizontal plane reticle and lens for viewing the scene immediately in front of the forks, means for positioning the lens of the camera a first predetermined location below the forks when the forks are in a raised position and for raising the camera to a protected position when the forks are in their lowermost position, and a display terminal for presenting to an operator the image of the scene viewed by the camera.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
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Dammeyer Ned E.
Fullenkamp Todd M.
Stammen Harold A.
Crown Equipment Corporation
King & Schickli PLLC
Olszewski Robert P.
Tran Thuy V.
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