Motor vehicles – Steered by walking attendant – Handle movement controls vehicle drive
Reexamination Certificate
2000-01-12
2001-08-21
Swann, J. J. (Department: 3611)
Motor vehicles
Steered by walking attendant
Handle movement controls vehicle drive
C180S006500, C180S019100, C180S065510, C280S047340
Reexamination Certificate
active
06276471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a delivery cart which includes a chassis formed of longitudinal and cross beams, at least one castor pivotable about a vertical axis and two support wheels for supporting the chassis on a ground, a displacement stirrup attached to the chassis and towering above the chassis, gearless, load-actuated reversible electric motor means associated with at least one castor or two support wheels and formed integrally with the castor or two support wheels, a power source for the electric motor means, and control means for controlling power supply to the electric motor means and including sensor means for sensing a displacement force and/or a steering force applied to the cart, and a control unit for controlling power supply to the electric motor means in accordance with the displacement force and/or a steering force.
2. Description of the Prior-Art.
German Publication DE-OS 195 05 309 describes a motor-driven delivery cart for delivering or distribution of large quantity of goods to a plurality of receiving stations, which permits to deliver a large quantity of different materials with a minimum of manual efforts on the part of a deliverer. Such a delivery cart spares the delivery person from expenditure of substantial physical efforts for moving the cart. In this cart, the power supply to the drive motor is controlled in accordance with a push or pulling force applied to the stirrup by the cart user. Such control not only insures matching of the driving power with the speed intended by the cart operator, independent from the area of the load, i.e., instantaneous total weight of the cart, and independent from whether the cart track rises or falls but also results in a reduced energy consumption. In the known delivery cart, the stirrup is formed as a motor vehicle steering wheel which is connected with the chassis by a single beam or bar, and the cart is provided with sensors for sensing the direction and the magnitude of the beam deformation for controlling the power supply to the electric motors. The use of sensors for sensing the pressure, displacement and deformation forces and for generating appropriate control signals for controlling the power supply to the electric motors is connected with substantial expenditures and considerably limits the possibilities of a correct determination of the drive actuation threshold.
Further, the auxiliary drive and its control, which are used in known delivery carts with an auxiliary power assist, are characterized by an unchangeable construction designed for a specific delivery cart and, therefore, can be used only with newly produced carts. In view of the durability of the carts and in the interest of the economical use of the auxiliary power assist means for a delivery cart, it is desirable to standardize the necessary components so that they can also be used with the already produced carts.
Accordingly, an object of the present invention is an auxiliary drive for a motor-driven delivery cart of the above described type which can be produced with as small as possible technical expenditures and with small as possible costs.
Another object of the present invention is to provide control means which can be used with difference types of the delivery carts, including already operational carts.
A further object of the present invention is to provide a delivery cart with power assist means and which would insure its ergonomically favorable handling and which is optimally maneuverable and operationally reliable.
SUMMARY OF THE INVENTION
This and other objects of the present invention, which will become apparent hereinafter, are achieved by forming the control unit, which controls the power supply to the electric motors, as a free programmable electronic unit. The free programmable control unit, in comparison with control units with an invariable program, has an advantage which consists in that it can be used with different types of delivery carts and can be programmed in accordance with the type of the cart and its intended use, which makes possible the use of the free programmable control unit in the already available carts. The free programmable control units permit to adapt the delivery carts to changing operational conditions. Further, such a control unit can be formed of standardized components.
The delivery cart and the control unit according to the present invention can be so formed that under all practically occurring operational conditions, the cart with a small load is freely movable along a flat track which does not have an increased rolling resistance, and the auxiliary drive is only then actuated when a displacement force applied by the cart operator and/or a braking force exceed a certain threshold.
According to a preferred embodiment of the delivery cart according to the present invention, control unit comprises an electronic computer and a free programmable memory. The electric motor means comprises two electric motors associated with the two support wheels, and the sensor means includes at least two sensors, with the computer having a separate input for each of the two sensors and a separate output for each of the two electric motors. The free programmable memory stores data used for actuating the electric motor means and for controlling power supply thereto and including an allowable force to be applied by the user and variably predetermined operational characteristics of the cart.
In this way, by an appropriate programming, the auxiliary drive operation can be adapted to predetermined and desirable drive characteristics of the cart, independent from the use conditions of the cart, the cart load, track characteristics and the like.
To insure that the cart would have the predetermined and desirable drive characteristics, the program of the control unit can envisage that the drive motors, which are usually formed as gearless electric motors formed integrally with respective running wheels, are actuated simply upon being fed with current and only then when the push or pulling force applied by the cart operator exceeds a predetermined threshold. Usually, when the cart running wheel encounters no rolling resistance, the electric motors remain still.
The free programmable memory can be formed in different ways. When the free programmable memory is formed integrally with the computer, the computer can be provided with additional input formed as an interface for programming the memory from outside with, e.g., a personal computer equipped with an appropriate software.
The free Programmable memory can be formed as a replaceable insert formed as a pin-on or plug-in data carrier connected with a corresponding interface of the computer.
In a delivery cart having one front castor and two rear support wheels, the displacement stirrup is formed as a shaft pole provided with a single handle, and the sensors are mounted in the stirrup handle and includes a first pair of force meters for sensing displacement forces applied to the shaft pole in a longitudinal direction of the cart, and a second pair of force meters for sensing steering forces applied to the shaft pole in a direction transverse to the longitudinal direction of the cart. Each of the force meters is formed of strips of a foil material an electrical resistance of which changes dependent on a pressure force applied to a horizontal surface thereof. The handle has a grip bar having a vertically extending square-shaped member, and the force meters of the first pair of force meters and the force meters of the second pair of the force meters are arranged opposite each other in a respective direction on the square-shaped member. Mounting of the sensors in the stirrup grip bar permits to reduce the dimensions of the control block. The control unit is also mounted on the handle and is connected with the two electric motors.
In accordance with a modified embodiment of the delivery cart according to the present invention, the displacement stirrup can be provided with two, spaced from each other in a transverse directio
Kratzenberg Wolfgang
Stein Siegfried
Austin Sidley
Brown & Wood LLP
Expresso Deutschland Transpotgeräte GmbH
McClellan James S.
Swann J. J.
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