Device at tiller truck

Details Device at tiller truck Device at tiller truck

1999-12-29

2001-08-21

Rice, Kenneth R. (Department: 3611)

Motor vehicles

Manually actuated controlling devices

With tiller-type handle

Reexamination Certificate

active

06276485

ABSTRACT:

Tiller trucks are today provided with more and more functions and possibilities, which in many cases mean additional controls arranged in the tiller handle. This means that an increasing number of cables run from the handle via the hinged and pivotable tiller to the truck itself. Since this is a comparatively long distance there is a risk that signals and pulses in one lead induce pulses in other leads, that may be sufficiently powerful to give faulty signals to the truck. This is of course not acceptable and the separate leads are therefor shielded or encapsulated in order partly to prevent internal influences and partly to prevent influence from other sources, as for instance from leads to motor and battery, that due to the large currents can result in powerful magnetic induction fields.
Shielded leads means in turn increased costs and the resulting thick cable is further more difficult to guide from the moveable arm to the truck itself, which may mean an increased risk of damages to the cable and partial function drop outs and security risks. In view of the above problems a first object of the invention is to eliminate the above drawbacks so that a safer and to a lower cost manufacturable truck is obtained.
The above object is solved by the use of digital serial communication between the handle and the truck itself. Preferably the digital communication is arranged in the shape of a serial cable. In order to handle the transfer digital circuits are arranged in the handle, for instance for the transfer of given control orders from the controls to signals that are then transferred to another digital unit in the truck itself that interpret the delivered digital signals and deliver corresponding commands to for instance thyristors and hydraulic valves.
At a first look the solution according to the invention seem to result in an unnecessarily increased complexity and probable increase in cost, in reality however it is an essential simplification and cost reduction.
The communication can preferably be by means of a cable but one can also consider wireless transfer via radio or optically, which in itself may provide additional supervising possibilities if so desired.
If one further as, is suggested in accordance with a further development of the inventive thought, locate the logic unit in the tiller handle and let it take care of other digital functions of the truck also additional advantages may be achieved. For instance means for authority verification may be located in the handle, and furthermore contact free sensors that are practically impossible to wear out may be used for the controls of the handle.
The arranging of logic circuits in the handle further allows an entirely digital speed control consisting of separate contact-free sensors instead of a potentiometer or the like. In this way the wear resistance and invariability during the time of use can be improved further, at the same time as the controls more optimally may be adapted to the digital logic.
The logic unit in the truck itself need only to have a communication function. The communication may further be bi-directional to allow sensors in the truck itself to send its information to the logic unit in the handle.
An additional advantage achieved with the locating of the logic in the handle is that the shocks and vibrations, including for circuit cards harmful microvibrations that are easily transferred to the truck from its comparatively small and hard wheels do not get the same possibility to reach the logic circuits.
The logic unit may further together with buttons and controls constitute a unit that is removable from the handle with a connection for the cable that connects the unit with the truck. Since this cable can be arranged inside a beam constituting the tiller it becomes comparatively well protected and since it is not a multiconductor cable it will be simpler to arrange.
For the shielding of the logic unit from sources of disturbances the handle may include a shielded space for the logic circuits.
In the cases when a display is desired this can be mounted more or less directly at the logic unit or even appended to this, that can be constituted of a separate unit in the shape of a circuit card.
Even a possible set of buttons or a keyboard for authority verification may be arranged in direct proximity at the logic unit or as a part thereof at for instance the bottom of the handle.
At trucks, for instance tiller trucks, today generally a more or less electronic drive or travel control is used to control travel direction and speed. The driving force is controlled by means of a potentiometer coupled to the control electronics. This brings the advantage of small control currents and good precision in the control. A drawback is however that potentiometers with necessity are worn reducing the precision and even bad contact may occur, resulting in a jerky increase or travel and the risk of dropping the load. To this comes of course the work with changing potentiometer including mounting and dismounting electrically as well as mechanically. There is also a risk that the potentiometer is subjected to moisture impairing its function and reducing it life, this in particular as many trucks of this kind alternatingly are indoors and outdoors with the consequent risk of condensation, not to mention the risk of rain.
In view of the above problems a second object of the invention is to provide a drive control that do not have the above drawbacks. In accordance with the invention the problem is solved with a drive control that includes a number of after each other activatable contact free sensors or switches, that are successively activated in order to via a control circuit feed a varying driving current to the driving motor. Initially this may seem as a step backward. Since with modern technique the switches or sensors can be made contact free and thereby wear free and uninfluenceable it is however a step forward and an essential difference relative the known technique.
Since the sensors are contact-free the mechanical manoeuvering part of the control can be contactwise or mechanically entirely free from the sensor part that therefor can be substituted without the mechanical maneuvering part having to be dismounted and vice versa.
Since the drive control also is to take care of the direction of travel this is at the invention simply solved by different series of sensors controlling travel forwards respectively backwards. This simple solution also minimizes the risk of errors.
An advantageous way to shape the drive control in accordance with the invention is to mount a magnet in the movable part of the control that at the turning or pushing movement of the control is brought past a number of Hall-elements that are used as sensors. By arranging a sufficient number of Hall-elements the control movement can be divided into the required number of steps that are required to make the adjustment of the speed sufficiently adaptable to the travel speed of the operator. If so is desired the number of sensors can be reduced or smaller steps be achieved by using both the front and rear slope of the sensor signals.
In relation to the normal use of potentiometers for the defining of the driving force at the invention a signal also at the 0-position can be obtained as a receipt if so desired.
If a stepless increase for the driving force is desired so that this will not be experienced as jerky this can surprisingly enough be achieved despite the use of discrete elements. The electronics can achieve a ramped or successive increase. By adapting the ramping to the speed between the sensors no delay is felt at rapid increases nor surprising increase jerks at slow movements. The ramping can also be used to bridge jerk free faulty separate sensors. When the position of the control change from a position it has had for a long time it can be difficult to know the speed of the control movement and then a standard value may be used instead, while when later an additional sensor is passed the electronics has the possibility to register the time and p

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