Traction drive for assisting in the movement of loads

Abstract

The invention relates to a traction drive which is connected to a transport device that measures the rolling friction force acting during movement and influences it, in particular partially or completely compensates it, by changing the drive torque.

Description

[0001] Drive to support the movement of loads

[0002] Description:

[0003] Areas of application for the drive system according to the invention include transport equipment of all kinds – both for commercial and private purposes. For example, full shopping carts in particular require considerable force for maneuvering – by using the innovative drive system, this force can be significantly reduced without the need to significantly modify or expand the vehicle's structure.

[0004] Drive systems have been in use for years, particularly in transport systems for logistical purposes, but also in sports equipment. These systems measure the force exerted by the operator and adjust it to a comfortable level. The force measurement sensors are usually connected to the drives via cables that must be properly installed within the vehicle. Typically, an energy storage unit is also included, which must be charged at regular intervals, either inside or outside the vehicle.

[0005] A corresponding transport device intended for movement by muscle power is known from EP 2 941 379 B1. Using a sensor, the muscle power acting on the transport device can be determined, and on this basis, suitable assistance can then be provided by an electric machine. For example, the sensor can be housed in a handlebar to determine the pushing and pulling forces acting on it. The sensor is then connected to a control device, which evaluates the sensor signal and controls the electric machine accordingly. This provides an overall system with spatially distributed components that treats and manipulates the transport device as a single unit. DE 10 2015 104 513 A1 also assumes the introduced pushing force as the central variable.

[0006] The present invention is based on the object of providing a simplified design of a travel drive and a transport device provided therewith.

[0007] The subject matter of the invention and the solution to the problem are a travel drive according to patent claim 1 and a transport arrangement according to patent claim 8.

[0008] According to the invention, the rolling friction force acting during movement is determined directly on the drive itself using suitable means. For example, if the drive has a drive wheel or a drive roller, the forces acting on a bearing and / or suspension of the drive wheel or drive roller can be determined using a sensor.

[0009] In the case of an inherently uniform movement, the frictional force leads to a force acting on the suspension and bearings that is opposite to the movement and can then be detected.

[0010] It is also possible to subject the recorded signals to a numerical analysis and, in particular, to consider the changes over time.

[0011] To enable a reliable determination of the rolling friction force in all cases, the values ​​determined with the previously described sensor can also be correlated with the measured values ​​of an acceleration sensor and / or a position sensor. If, for example, the rolling friction spontaneously increases when the surface changes, forces act between the transport device and the drive, for example on the suspension or bearing, which, depending on the detection method, cannot be easily distinguished from a spontaneous change in the pushing forces. By comparing them with an acceleration sensor and / or a position sensor, it is also possible to distinguish the changing rolling friction from a downhill force, as well as the introduction of an additional pushing force, or the like.

[0012] Another parameter to be evaluated is the rotational speed, a rotational angle, or a change in the rotational angle of the drive wheel, which can be determined and correlated with other measured parameters. A change in the rotational angle can be directly converted into a travel along the circumference of the drive roller with high accuracy.

[0013] According to the invention, the drive can be used as a standalone device because data acquisition and processing can take place locally. It is then not absolutely necessary to use additional components remote from the drive itself, such as a sensor in a push bar. Wireless or wired networking and / or connections between multiple drive units and / or a controller and / or additional sensors are not excluded within the scope of the invention, although the fundamental advantages of the invention can already be realized by one drive unit alone or by multiple drive units individually.

[0014] In particular, within the scope of the invention, it is possible for the drive system to comprise exactly one drive wheel or a type of twin wheel and at least one motor. Such a drive system can then, for example, be modularly replaced with a previously provided, non-driven drive wheel in a transport device.

[0015] Against this background, the drive can also be retrofitted to previously non-driven or non-supported transport equipment or offered as an optional accessory.

[0016] As explained further below, the transport device can have several, for example four, support points, each of which has a wheel arrangement with at least one wheel. A travel drive according to the invention can then be arranged at at least some of the support points, and preferably at all of the support points. The effective rolling friction force can then be influenced, in particular partially or completely compensated, for each travel drive.

[0017] In particular, the drive system can be used within the scope of the invention in such a way that operation by a user is simpler and safer, while the active interventions of the drive system are not perceived by the user himself.

[0018] The drive according to the invention only requires a mechanical connection to the vehicle and, if necessary, an electrical connection. If the drive can collect and buffer the energy required for its function during appropriate operating phases, an electrical connection to the vehicle and external charging are no longer necessary. Without such a connection, trailing, freely rotatable drive rollers can then be easily implemented. A good example is a shopping cart, which buffers energy under favorable rolling conditions, thus providing support during difficult movement phases—for example, when changing direction by pivoting over an unfavorable lever arm.A significant buffer, which can cause considerable costs, is no longer necessary if actuators acting as generators produce the energy required by supporting actuators - this is often possible in more complex movement sequences involving multiple drives.

[0019] The drive according to the invention consists of one or more wheels, associated motors, and a measuring device for the forces acting between the vehicle and the drive, as well as a control unit that regulates the torque of the motors based on the determined forces. If the force acting parallel to the ground is determined during operation on a nearly level surface, complete or partial compensation of the rolling friction can be achieved, even with varying loads. If all wheels of a vehicle incorporate such a drive, all rolling friction forces are compensated accordingly – trailing rollers retain their full steering characteristics. Only the forces required to overcome mass inertia are not compensated, which can, however, be advantageous for safe handling. In addition to the shopping carts mentioned, there are a multitude of very similar applications, such as hospital beds, industrial trucks, etc.- Transport equipment that is moved predominantly or exclusively on level ground. Transport equipment in the broader sense also includes movable furniture or parts thereof.

[0020] If all forces acting on the drive system are captured, downhill and rolling friction forces can also be compensated. Drive systems with these characteristics can be used much more widely—for example, in strollers, bicycles, walkers, wheelchairs, wheelbarrows, shelf trolleys, industrial trucks, etc.

[0021] Another particularly suitable application is hospital and nursing beds.

[0022] Figure 1 schematically shows part of a transport device with an attached drive system on a slope. The total mass - possibly modified by a holding force - creates a downhill force and a contact force on the ground. If, for example, the center of gravity of the entire device is to the right of the support point (wheel), in addition to the total mass, there is also the holding force, which in this example acts downwards. If the center of gravity is to the left of the wheel, the holding force must act upwards and reduces the effect of the mass. Additional wheels represent supports and reduce the mass acting on the wheel in question - the same applies to the tractive forces. Each drive wheel is therefore only responsible for the "mass" it supports.

[0023] The contact force can be measured either directly at the wheel or at the attachment – ​​although this is reduced by the effect of the weight of the drive itself. The rolling friction force resulting from the contact force occurs when moving against the direction of travel. It could also be measured at the wheel axle or – without the need for correction – at the attachment. Using acceleration sensors, the spatial position of the drive and the transport device firmly connected to it can be determined, and the total mass acting can be deduced from the contact force. In reality, the effect of the third dimension, not discussed here, must also be taken into account. Thus, all acting forces are known and can be influenced and, in particular, compensated for within the scope of the available drive force – knowledge of the acting tensile and holding forces is not required.

[0024] A particularly interesting example is a rollator. The drive system according to the invention can detect the load, which varies depending on the user's support behavior while walking, and take this into account so that the rollator doesn't roll away even on slopes. A pulling or pushing force applied parallel to the ground alone then causes a friction-compensated movement.

[0025] With regard to the further design of the traction drive, a wide variety of design options arise. For example, an accumulator or a capacitor can be provided as the energy storage device. Especially if energy recovery and storage are provided according to a preferred embodiment of the invention, even comparatively small amounts of energy can be sufficient to enable advantageous use of the traction drive. For example, based on a typical, desired sliding resistance, it can also be provided that short-term compensation is only provided in certain situations. During normal ferry operation with comparatively low rolling friction, the motor can be operated as a generator to charge the energy storage device.

[0026] A supercapacitor, or supercap for short, is particularly suitable as a capacitor.

[0027] The braking effect that occurs when the device is operated as a generator can, in principle, also be used as a safety function. If, for example, the transport device is moved along a gradient, a beneficial braking effect can be achieved by operating it as a generator. This type of braking effect is particularly advantageous when the transport device is designed as a walker, hospital or nursing bed, wheelchair or similar. In transport devices with an additional mechanical brake, the load can be relieved, and an overall improved braking effect can be achieved. In transport devices without an additional mechanical brake, on the other hand, a braking effect can be achieved at all, for example to keep pushing or holding forces for an operator within reasonable limits.

[0028] It goes without saying that the braking effect should preferably be available even when the energy storage device is fully charged. It is then possible to convert the braking energy into heat, for which purpose, appropriate heat generation can be provided both in the windings and leads of the motor and in a separate load resistor. Heat sinks can also be provided in a known manner for improved heat transfer. Additionally or alternatively, a fan can also be used to improve heat transfer.

[0029] As previously described, the drive system can also have more than one drive wheel. For example, in a dual-wheel configuration with two wheels, the forces acting on both wheels and / or rotational speeds or changes in angle of rotation can be determined. This also allows, for example, the transport device's cornering to be detected, allowing for appropriate compensation of the rolling friction force or other adjustment of the drive torque.

[0030] In principle, additional or alternative measures are also conceivable to detect cornering and / or redirection of the transport device

[0031] If, for example, the drive is attached to the transport device around a vertical axis and can pivot around it during a deflection, a sensor can also be provided there to detect the angle of rotation with regard to the pivoting movement.

Claims

Patent claims:

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

2. Drive system according to claim 1, which additionally determines the slope force by measuring the contact force acting on the ground and measuring and taking into account the spatial position and influences this by changing the drive torque, in particular compensating it completely or partially.

3. A travel drive according to claim 1 or 2, which is mechanically and electrically connected to the transport device so as to be rotatable about a vertical axis horizontally offset from the center of a wheel.

4. A drive according to claim 1 or 2, which is mechanically connected to the transport device so as to be rotatable about a vertical axis horizontally offset from the center of a wheel and has its own energy storage device which is removable for the purpose of charging and / or is recharged by regenerative braking during favorable movement phases.

5. Drive according to claim 4, which is provided for exchanging energy with other drives of the transport device.

6. A drive system according to one of claims 1 to 5, comprising a drive wheel, wherein a sensor is arranged on a suspension and / or bearing of the drive wheel.

7. Drive system according to one of claims 1 to 6, comprising at least one acceleration sensor.

8. Transport arrangement with a transport device at least one travel drive, preferably several travel drives according to one of the claims 1 to 7.

9. Transport arrangement according to claim 8, wherein the transport device is selected from the group of strollers, walkers, wheelchairs, wheelbarrows, trolleys, hospital beds and nursing beds.

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