Fire escape – ladder – or scaffold – Having transpositioning base and erecting means
Reexamination Certificate
1999-11-29
2001-12-18
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Having transpositioning base and erecting means
C182S018000
Reexamination Certificate
active
06330933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a microprocessor-based control system for a scissor type aerial work platform. More particularly, the invention relates to the use of a microprocessor-based control system for a scissor type aerial work platform which allows a reduction in the number of components required in the control function. The invention also relates to a multiplexing device which reduces the number of conductors required in the control system.
2. Description of the Related Art
Work Platforms are utilized for a variety of different uses, such as: a) loading and unloading of items in a warehouse, and b) repairing components located at a particular elevation, such as repairing a broken ceiling light in a gymnasium.
FIG. 1
a
shows a conventional work platform which can be used at a warehouse, for example. The work platform, which in this case is shown as a scissor type aerial work platform
10
, can be used to move large boxes from one location to another, or it can be used to move a worker to a particular location as the work platform
10
is raised or lowered to a particular height. The work platform
10
includes a base portion
20
and a vertically movable platform portion
30
(also called “aerial work platform”).
One important aspect of aerial work platforms is the control of the movement of the movable platform
30
with respect to the base portion
20
. Typically, this is done by monitoring inputs made by an operator, and by raising or lowering the movable platform
30
, extending or retracting a deck on the movable platform
30
, or driving the work platform
10
based on the particular operator input.
FIG. 1
b
shows the same work platform
10
as in
FIG. 1
a
, but with a deck
40
extended on the movable platform
30
, thereby allowing an operator on the movable platform
30
greater range of movement.
U. S. Pat. No. 5,274,331, invented by Littlejohn et al., shows a system in which network communication concepts are applied to a motor and/or motion control system. Specifically, a wheelchair control is shown in the Littlejohn et al. reference, in which three modules are interconnected by an RS-485 bus. The modules are: a) a user command module, b) a motherboard controller module, and c) a drive motor controller module. In the Littlejohn et al. system, commands entered at the command module are transmitted to the motherboard controller through the bus. The motherboard controller communicates with the motor controller through the bus.
U.S. Pat. No. 4,519,042, invented by Minamida et al., shows a method for checking the operation of a combinatorial weight measuring apparatus to determine whether weighing machines and a microcomputer which determines the optimum combination of objects are operating properly. Also shown in Minamida's system is a multiplexer which is used for communicating information from a plurality of controlled elements, i.e., weighing machines, to a microcomputer.
U.S. Pat. No. 4,691,805, invented by Kiski, shows a lifting apparatus in which a number of functions are controlled bat software. These functions include the extension of a stretchable boom, inclination of the stretchable boom, and the orientation of a work platform at the end of the boom.
U.S. Pat. No. 5,011,358, invented by Andersen et al., shows a controller for a forklift, which compares programmed store and retrieve heights for various shelves in a warehouse with the current height of the fork. The Andersen et al. system also displays to the operator an indication when the fork is at or within a predetermined range of the store or retrieve height of the shelf.
None of the above systems show a device which can accommodate both analog and digital inputs to control an aerial type work platform in an expedient manner, nor do they show a device that can receive various sensor inputs as well as platform and ground select inputs to control a plurality of valves to actuate a particular work platform function.
Further, each of the above-mentioned systems uses external relays and diodes to provide the needed control of the work platform. The various control devices are not centrally located, and do not use solid-state components for the control function of the work platform.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a solid-state system for controlling a scissor type aerial work platform.
It is a further object of the invention to provide a means for operating the work platform in a safe mode of operation based on various sensed inputs obtained from the work platform.
It is still another object of the invention to provide a means for operating the work platform using momentary membrane push buttons and a joystick, to effect at least one of a drive mode, a lift mode, and a deck mode.
These and other objects are accomplished by a controller for a work platform having a base section and a movable platform section. The controller includes means for receiving a plurality of sensed inputs of a state of the work platform, the state including at least one of a load on the work platform, a height of the movable platform section, and an angular position of the work platform. The controller also includes means for allowing operator inputs to operate the work platform from one of a ground control station located on the base section and a platform control station located on the movable platform section. The controller further includes means, responsive to the received sensed inputs and the operator inputs, for operating the work platform in one of a plurality of predetermined conditions, whereby any of the predetermined conditions allow safe operation of the work platform.
These objects are also accomplished by a platform control station on a movable platform section of a work platform which also includes a base section. The platform control station includes a joystick operable in a single-axis direction, with the joystick positioned in a central position when not operated by an operator. The platform control station also includes means for providing a first signal when the joystick is moved in a first direction along the single-axis direction, and for providing a second signal when the joystick is moved in a second direction along the single-axis direction, the second direction being opposite the first direction. The platform control station further includes a drive select push button, a lift select push button, and a deck select push button. The platform control station even still further includes a rocker switch positioned on a top portion of the joystick, with the rocker switch positioned in one of a first state and a second state when operated by the operator, and with the rocker switch positioned in a third state indicating a non-operational condition when not operated by the operator. With the above-described platform control station, when one of the drive select push button, lift select push button, and deck select push button are selected by the operator, the operator has a predetermined amount of time in order to engage the joystick in order to effect movement of the work platform.
These and other objects are also accomplished by using a method for controlling movement of a work platform having a movable platform section with a retractable deck:. The method includes a step of receiving operator inputs on a platform control station housed at the movable platform section to request one of drive movement, lift movement and deck movement of the work platform. The platform further includes a step of receiving sensed inputs on a plurality of locational conditions of the work platform, including height of the movable platform section. Lastly, based on the received sensed inputs, the method includes a step of either allowing, disallowing, or allowing in a cut back state the request based on the received operator inputs.
REFERENCES:
patent: 3854610 (1974-12-01), Carder
patent: 3920096 (1975-11-01), Fisher
patent: 4252213 (1981-02-01), Ekman
patent: 4456093 (1984-06-01), Finley
patent: 4501939 (1985-02-01), Hyltin et al.
Boeckman Brian M.
Mellott Lex A.
Chin-Shue Alvin
JLG Industries Inc.
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