Drive to support the movement of loads

Abstract

Travel drive which is connected to a transport device which measures the rolling friction force acting during movement and influences it by changing the drive torque, in particular partially or completely compensating it.

Description

Areas of application of the propulsion system according to the invention are transport devices of any kind--both for commercial and private purposes. For example, in particular full shopping carriages require considerable forces for maneuvering--by using the novel drive, these can be reduced considerably without the structure of the vehicle having to be changed or extended substantially.In particular in transport devices for logistic purposes, but also in sports equipment, drive systems have been used for years, in which the force applied by the operator is detected, which is adjusted to a comfortable value by the drive system. The sensor system for force measurement is usually connected to the drives via cables which have to be suitably laid in the vehicle. As a rule, an energy store is also present, which must be charged at certain intervals in the vehicle or else outside.The drive according to the invention only requires the mechanical connection to the vehicle and, if appropriate, an electrical connection. If the drive can collect and buffer the energy necessary for its function in correspondingly favorable operating phases, no electrical connection to the vehicle and no external charging are necessary any longer. Without such a connection, any rotating drive rollers that follow can then also be easily realized. A good example is a shopping trolley which buffers energy under favourable rolling conditions, so that it is supported in difficult movement phases-for example when changing direction by pivoting over an unfavourable lever arm. A substantial buffer, which can indeed cause considerable costs, is no longer necessary if actuators acting as generators generate the energy which actuators currently require supporting actuators-this is not rarely possible in the case of more complex movement sequences involving a plurality of drives.The drive according to the invention consists of one or more running wheels, associated motors and a measuring device for the forces acting between the vehicle and the drive, as well as a control unit which regulates the torque of the motors on the basis of the forces determined. If the force acting parallel to the ground is determined during operation on a nearly planar ground, a complete or partial compensation of the rolling friction can also be carried out at varying loads. If all wheels of a vehicle contain such a drive, all rolling friction forces are compensated accordingly--trailing rollers retain their steering properties completely. Only the forces required to overcome the inertia are not compensated, which can be advantageous for safe handling, however. In addition to the shopping cart mentioned, there are a large number of quite similar applications such as hospital beds, industrial truck, etc.-transport devices which are moved predominantly or exclusively in the plane. Transport devices in the broader sense are, however, also movable furniture or parts thereof.If all forces acting on the traction drive are detected, slope-driven and rolling friction forces can also be compensated. Drives with these properties can be used even more widely - for example in baby carriages, bicycles, scooters, wheelchairs, etc.FIG. 1 schematically shows a part of a transport device with a travel drive fastened thereto in a slope situation. The total mass, optionally modified by a holding force, brings about a slope-driven force and a contact force on the underlying surface. If, for example, the center of gravity of the entire device is to the right of the support point (wheel), the holding force acting downward in this example acts in addition to the total mass-if the center of gravity is to the left of the wheel, the holding force must act upward and reduces the effect of the mass. Further wheels constitute supports and reduce the mass acting on the wheel under consideration--the same applies to the tensile forces. Each drive wheel is thus responsible only for the "mass" supported by it.The contact pressure can either be measured directly on the wheel or in the fastening--however reduced there by the effect of the weight of the drive itself. The rolling friction force resulting from the contact pressure occurs when moved against the running direction. It could also be measured on the axle of the wheel or, without the need for correction, also in the fixture. With the aid of acceleration sensors, the spatial position of the travel drive and of the transport device firmly connected thereto can be determined and thus the total mass acting on it can be deduced from the contact pressure, wherein in reality the effect of the third dimension not discussed here must still be taken into account. Thus, all acting forces are known and can be influenced and in particular compensated within the scope of the available driving force-a knowledge of the acting tensile and holding forces is not necessary.A particularly interesting example is a rollator. By means of the drive according to the invention, the load which varies as a result of the user's support behavior during walking can be detected and taken into account in such a way that the rollator does not roll away even on the slope-merely a tensile or thrust force which is carried out parallel to the ground brings about a movement which is then compensated for rolling friction.

Claims

A traction drive which is connected to a transport device which measures rolling friction force acting during movement and which, in particular, partially or completely compensates for said rolling friction force by changing the drive torque.Traction drive according to Claim 1, which additionally determines the slope-off force by measuring the contact pressure force acting on the underlying surface and measuring and taking into account the spatial position and influences this force, in particular completely or partially compensates it, by changing the drive torque.A traction drive according to claim 1 or 2, mechanically and electrically connected to the transport means for rotation about a vertical axis offset horizontally with respect to the centre of the wheel.Traction drive according to Claim 1 or 2, which is mechanically connected to the transport device rotatably about a vertical axis offset horizontally with respect to the centre of the wheel and has its own energy store, which can be removed for the purpose of charging and / or is recharged in favorable movement phases by means of generator braking.Travel drive according to claim 3, which is provided for exchanging energy with other drives of the transport device.

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