Electrically controlled travel drive control system for steerable vehicles, particularly fork lift trucks
First Claim
1. In an electrically controlled travel drive control system for a steerable vehicle comprisinga steerable axle assembly having swivelled first road wheel means,a second axle assembly spaced from said steerable axle assembly in the longitudinal direction of the vehicle and having second road wheel means,one of said road wheel means comprising two road wheels disposed on opposite sides of said vehicle, andtravel drive motor means operatively connected to at least one of said road wheel means,the improvement residing in thattwo speed sensors are associated with said two road wheels and operable to generate speed signals which are representative of the speeds of the respective road wheels,a comparator is arranged to receive said speed signals and to generate an output which depends on the difference between said speed signals,additional input means are provided and adapted to receive an additional input signal,a switching system is provided, which is adapted to generate a travel drive control signal for controlling said travel drive motor means in dependence on the difference between said speed signals and on said additional input signal,said steerable axle assembly comprises an angularly movable bogie and two road wheels mounted in said bogie and disposed on opposite sides of said vehicle,said travel drive motor means comprise two travel drive motors,one of said road wheel means comprises two road wheels disposed on opposite sides of said vehicle and operatively connected to respective ones of said travel drive motors,a proximity sensor is associated with said steerable axle assembly and adapted to deliver an output signal which depends on the angular position of said bogie, andsaid switching system is adapted to control said travel drive motors in dependence on the output signal of said proximity sensor.
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Accused Products
Abstract
The invention relates generally to steerable vehicles, particularly fork lift trucks, which include one or more travel drive motors adapted to be controlled in a predetermined manner, and a steerable swivelled wheel assembly. To increase the safety of such vehicle in operation, an electrically controlled drive control system is provided which is simple and free from elements that are susceptible to wear. For this purpose, two speed sensors are provided on opposite sides of the vehicle and cooperate with respective coaxial road wheels and are connected by a comparator to a switching system for controlling the travel drive, e.g., to a travel control signal generator. Elements for applying at least one additional speed-influencing input signal are associated with the comparator.
37 Citations
18 Claims
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1. In an electrically controlled travel drive control system for a steerable vehicle comprising
a steerable axle assembly having swivelled first road wheel means, a second axle assembly spaced from said steerable axle assembly in the longitudinal direction of the vehicle and having second road wheel means, one of said road wheel means comprising two road wheels disposed on opposite sides of said vehicle, and travel drive motor means operatively connected to at least one of said road wheel means, the improvement residing in that two speed sensors are associated with said two road wheels and operable to generate speed signals which are representative of the speeds of the respective road wheels, a comparator is arranged to receive said speed signals and to generate an output which depends on the difference between said speed signals, additional input means are provided and adapted to receive an additional input signal, a switching system is provided, which is adapted to generate a travel drive control signal for controlling said travel drive motor means in dependence on the difference between said speed signals and on said additional input signal, said steerable axle assembly comprises an angularly movable bogie and two road wheels mounted in said bogie and disposed on opposite sides of said vehicle, said travel drive motor means comprise two travel drive motors, one of said road wheel means comprises two road wheels disposed on opposite sides of said vehicle and operatively connected to respective ones of said travel drive motors, a proximity sensor is associated with said steerable axle assembly and adapted to deliver an output signal which depends on the angular position of said bogie, and said switching system is adapted to control said travel drive motors in dependence on the output signal of said proximity sensor.
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14. In an electrically controlled travel drive control system for a steerable vehicle comprising
a steerable axle assembly having swivelled first road wheel means, a second axle assembly spaced from said steerable axle assembly in the longitudinal direction of the vehicle and having second road wheel means, one of said road wheel means comprising two road wheels disposed on opposite sides of said vehicle, and travel drive motor means operatively connected to at least one of said road wheel means, the improvement residing in that two speed sensors are associated with said two road wheels and operable to generate speed signals which are representative of the speeds of the respective road wheels, a comparator is arranged to receive said speed signals and to generate an output which depends on the difference between said speed signals, additional input means are provided and adapted to receive an additional input signal, a switching system is provided, which is adapted to generate a travel drive control signal for controlling said travel drive motor means in dependence on the difference between said speed signals and on said additional input signal, a memory for storing data which are specific to the vehicle is associated with the comparator, switching means are provided which are operable in response to the output of said comparator in dependence on data stored in said memory, said switching system is adapted to control said travel drive motor means in dependence on the state of said switching means, said switching system is adapted to limit the speed of said travel drive motor means to a preselected maximum, reduced maximum speed data defining a lower speed below said preselected maximum are stored in said memory, said switch means are operable to supply said reduced maximum speed data from said memory to said switching system when said output of said computer amounts at least to a preselected value, and said switching system is arranged to limit the speed to said travel drive motor means to said lower speed when said reduced maximum speed data have been supplied from said memory to said switching system.
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15. In an electrically controlled travel drive control system for a steerable vehicle comprising
a steerable axle assembly having swivelled first road wheel means, a second axle assembly spaced from said steerable axle assembly in the longitudinal direction of the vehicle and having second road wheel means, one of said road wheel means comprising two road wheels disposed on opposite sides of said vehicle, and travel drive motor means operatively connected to at least one of said road wheel means, the improvement residing in that two speed sensors are associated with said two road wheels and operable to generate speed signals which are representative of the speeds of the respective road wheels, a comparator is arranged to receive said speed signals and to generate an output which depends on the difference between said speed signals, additional input means are provided and adapted to receive an additional input signal, a switching system is provided, which is adapted to generate a travel drive control signal for controlling said travel drive motor means in dependence on the difference between said speed signals and on said additional input signal, a memory for storing data which are specific to the vehicle is associated with the comparator, said travel drive motor means comprise two travel drive motors, one of said road wheel means comprise two road wheels operatively connected to respective ones of said travel drive motors, data representing a predetermined value for the difference between said speed signals are stored in said memory and an on-off switch is adapted to control the energization of said travel drive motors independently of each other in dependence on whether the difference between said speed signals exceeds or is lower than said predetermined value.
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16. In an electrically controlled travel drive control system for a steerable vehicle comprising
a steerable axle assembly having swivelled first road wheel means, a second axle assembly spaced from said steerable axle assembly in the longitudinal direction of the vehicle and having second road wheel means, one of said road wheel means comprising two road wheels disposed on opposite sides of said vehicle, and travel drive motor means operatively connected to at least one of said road wheel means, the improvement residing in that two speed sensors are associated with said two road wheels and operable to generate speed signals which are representative of the speeds of the respective road wheels, a comparator is arranged to receive said speed signals and to generate an output which depends on the difference between said speed signals, additional input means are provided and adapted to receive an additional input signal, a switching system is provided, which is adapted to generate a travel drive control signal for controlling said travel drive motor means in dependence on the difference between said speed signals and on said additional input signal, said travel drive motor means comprise two travel drive motors and one of said road wheel means comprise two road wheels operatively connected to respective ones of said travel drive motors.
Specification