DE19737568C1 - Bicycle with auxiliary electric motor - Google Patents

Abstract

The bicycle has a pedal mechanism and a chain or belt drive for rotation of the wheels and an auxiliary electric motor (6) coupled to an electronic control (7), acting on the wheels via a separate drive coupling. A movement sensor (10) in the pedal mechanism drive coupling provides a signal for the electronic control, for controlling the electric motor output.

Description

The invention relates to a vehicle, in particular a Bicycle, with one through muscle power via pedals or hand cranks operable chain or belt drive and with an electric Auxiliary drive, which has a drive-supporting electric motor as well has an associated control electronics or electronics (DE 25 03 720 A1). In such bicycles with auxiliary drive, the bicycle character should largely preserved. There is a requirement that the drive is only supported by the electric motor, if the user of the bike biomechanically at least the drive supported. It is also essential that a simple Retrofitting bicycles with such auxiliary drives may be possible should and that the costs for such a retrofit kit if possible are low.

To recognize whether a muscle force or biomechanical force transmission by the Users are relatively complicated, expensive, prone to failure and not easily retrofittable torque or force sensors directions known (see, for example, DE 32 08 345 A1). With With the help of these torque or force sensor devices biomechanical use of force measured by the user and proportional the driving force of the motor is adapted to this measurand. This requires a comparatively complex mechanism and control.  

A vehicle of the type mentioned with an electric Auxiliary drive is already known from DE 25 03 720 A1. With this The vehicle's electric auxiliary drive is activated when those transmitted from a main muscle power drive to the vehicle Forces reach a certain value.

For recording the driving forces transmitted by muscle power a feeler sprocket measuring the chain tension is provided, which is adjustable against a restoring force and from one certain deflection caused by increased chain tension actuated a switch to switch on the additional drive.

The driving sprocket of the additional drive is in the upper one Chain center and thus in the pull section of the chain between the Feeler sprocket and the pedal sprocket.

Via the feeler sprocket, it can only be powered by muscle power generated and independent of the auxiliary drive chain tension not detected become. With this drive concept, the muscle Power transmission and the engine power transmission through a common Drive chain, so that drive elements even when the engine is switched off of the auxiliary drive must be moved.

From DE 43 02 838 A1 it is known to calculate the required Drive power in a vehicle of the type mentioned in the introduction to provide a whole range of measuring devices. So are dynamic pressure gauges to measure the flow velocity, an inclinometer around the Determine degree of incline or descent and one on the bike mounted revolution counter for calculating the current driving speed provided. None of this results in one insignificant effort of retrofitting a muscular strength operated vehicle problematic.

In addition, here, too, by detecting the driving speed are not differentiated between muscle or motor performance resulting speed or driving speed.

The object of the present invention is in a generic Vehicle to an auxiliary drive  create a simple, cheap, reliable link of biomechanical drive and auxiliary drive support is available.

To solve this problem, a vehicle is proposed in which the muscle-powered drive and the auxiliary drive separate, have independent power transmission devices, a movement only in the powertrain Sensor is arranged in which the motor control electronics the signal of the motion sensor a value for the circulation speed of the chain or belt of the muscle-powered drive forms, the setpoint of the engine speed proportional to the Orbital speed is specified.

Due to the separate, independent power transmission from Muscle strength and auxiliary drive is a clear dependency of the Motion sensor output signals given only by the muscle power drive. This means that the auxiliary drive is only activated even while driving switched on when driving force is also required. this will signaled by the drive movement of the chain, whereby a Adjustment of the additional service by the speed of the circulation Chain is done.

It is also advantageous that the motion detection with can realize much simpler means than a torque detection, so that this alone reduces the effort. In addition, the evaluation of those supplied by a motion sensor Measured variable easier to carry out. After all, there are motion sensors also insensitive to faults and therefore reliable.

A motion sensor is expediently provided, which is a directional signal generated. This prevents the electric motor when moving the biomechanical backwards Drivetrain engages. Linking the biomechanical The drive with the auxiliary drive support is only used for Intended direction of movement and intended Presence of the biomechanical drive train.  

By interaction of the motion sensor with the biomechanical In contrast to other conceivable power transmission devices Prevents possibilities of recording the biomechanical movement, that the electric motor over the biomechanical force carrying device, for example when jumping off the chain, switches on.

A preferred embodiment provides that the motion sensor one preferably driven by the chain or belt Has sensor role on the at least two pulse generator elements arranged circumferentially to one another in a position deviating from 180 ° are and that the sensor role at least one pickup is assigned, which is electrical with a motor control electronics connected is. Preferably used as pulse generator elements Magnets and as a pickup at least one Hall probe or reed contacts used if necessary.

Such a motion sensor can be done with little effort realize high operational reliability at the same time. Through the Arrangement of the pulse generator elements in a different from 180 ° Position arise in the two directions of rotation of the sensor roller different pulse patterns that easily the Show the direction of movement of the biomechanical drive. For a quick response both when switching on and when Switching off the electric motor, it is advantageous if four, if necessary, six pulse generator elements are provided.

It is useful if the motor is controlled by the Control electronics in a low speed range biomechanical power transmission with a steep increase in engine Target speed and above this low speed range with a flatter increase in the target engine speed.

Effective starting support is obtained in particular then also on gradients and during driving the drive support by the electric motor after the Speed of biomechanical power transmission, d. H. that with increasing speed, for example, the pedal crank also  Motor support increases. With a biomechanically advantageous The speed of the power transmission device is then a Motor power limitation at a given maximum value, the can be, for example, 250 W.  

Additional embodiments of the invention are in the others Subclaims listed. The following is the invention with their essential details with reference to an embodiment explained.

It shows:

Fig. 1 is an overall view of a drive with an electric assist bicycle equipped,

Fig. 2 is a detailed view in the region of a motion sensor,

Fig. 3 is a timing diagram and

Fig. 4 is an engine control diagram.

An example shown in Fig. 1 Bicycle 1 comprises a drive 2 with a biomechanical actuated by pedals chain drive 3, wherein the force is transmitted to the rear wheel 4. The bicycle 1 has an electric auxiliary drive, which has an electric motor 6 installed in the execution example in the front wheel 5 , which is designed here as a hub motor. The electric motor 6 is connected to control electronics 7 and a drive battery 9 via cables 14 . The control electronics 7 are accommodated in the area of the luggage rack within a container 8 , which also contains the drive batteries 9 . A motion sensor 10 is also electrically connected to the control electronics 7 via cable 15 , with which the motion of the biomechanical drive 2 is detected.

In the exemplary embodiment, the movement sensor is arranged in the region of the lower chain run and detects the movement of the chain. For this purpose, the motion sensor 10 has, in the exemplary embodiment, a sensor roller 11 driven by the chain, which can be seen more clearly in FIG. 2. The sensor roller 11 is provided with pulse elements 12, 12 a and adjacent to the sensor roller 13 is disposed a pickup, which gives a pulse edge to the control electronics 7 as they pass a pulse element.

A contactless sensor arrangement is preferably provided, which in particular works with magnets and a magnetic field-dependent impulse pickup 13 . The pickup 13 is expediently formed by a Hall element.

The pulse generator elements are formed by permanent magnets arranged in a heteropolar manner, four such magnets being provided in the exemplary embodiment. These are each arranged so that the north and south poles alternately run past the pickup 13 when the sensor roller 11 rotates. The pulse generator elements with effective north poles are labeled 12 and the pulse generator elements with effective south poles are labeled 12 a and are distinguished on the one hand by "N" and on the other hand by "S". It can also be clearly seen in FIG. 2 that the same-pole magnets 12 and 12 a are arranged diametrically opposite each other and that the equipolar pole pairs are offset by 60 and 120 ° to one another. When the sensor roller 11 rotates, a very specific pulse pattern is generated, which is shown in the diagram according to FIG. 3.

The angle of rotation of the sensor roller 11 is plotted on the abscissa and the pulse amplitude on the ordinate. Due to the differently polarized pulse generator elements 12 , 12 a, the rising edge of a pulse is generated, for example, when the pulse pickup 13 is influenced by a south pole, while a north pole forms a falling edge. With the selected arrangement of the pulse generator elements with an angular offset of 60 or 120 °, this results in pulses whose pulse width extends over an angle of rotation of 60 ° and where the pulse pauses correspond to an angle of rotation of 120 °. The arrangement of four pulse generator elements means that the control electronics or the electric motor responds very quickly. If necessary, more than four, for example six, pulse generator elements can also be provided.

If no pulses are supplied to the control electronics 7 from the pickup 13 , the electric motor 6 is switched off. The "asymmetrical" arrangement of the pulse generator elements 12 , 12 a also ensures that the motor is not activated when the chain 3 moves counter to the drive direction, which is possible, for example, with derailleurs with freewheeling. In this direction of movement, a pulse pattern that deviates significantly from the pulse diagram shown in FIG. 3 would result, the pulse pauses occurring in the forward drive direction forming the pulses and thus extending over 120 °. This can be easily evaluated and distinguished within the control electronics 7 .

FIG. 4 also shows an engine control diagram in which the pedal crank speed n _T and thus the muscle movement actuated drive movement are plotted on the abscissa and the motor speed n _{M is} plotted on the ordinate.

After a short response delay, which is determined by the distances between the intended pulse generator elements 12 , 12 a, the engine speed rises steeply in a low pedal crank speed range and thus a quick and effective starting aid. The target speed of the motor can be approximately half the maximum speed in this range of the low pedal crank speed. From this lower speed range of the biomechanical power transmission, there is a flatter increase in the engine speed n _M with increasing pedal crank speed n _T , until finally the maximum speed of the engine is set at a biomechanically advantageous speed of the power transmission device in the range of approximately 40-70 crank revolutions per minute.

In order to adapt to a biomechanically advantageous drive movement, which, as already mentioned, is usually in a range from approximately 40 to 70 crank revolutions per minute, the biomechanical drive can have a gear shift, in particular a hub shift or a derailleur shift. This ensures that, for example, on the mountain, where the driving speed decreases accordingly, by switching to a lower gear with a lower gear ratio the crank speed and thus the chain speed can be increased such that the motor support increases according to the diagram shown in FIG. 4. If there is no circuit, the user would have to introduce more biomechanical drive power in order to achieve increased motor support. The power limitation of the drive motor to, for example, 250 W is preferably carried out without an additional measuring device for the mechanical variables motor speed and motor torque by measuring and linking the electrical motor variables alone, taking into account the motor losses or, in the simplest case, by limiting the operating current. The control electronics 7 is also designed so that a soft start takes place when the motor is switched on and thus there is a practically jerk-free starting and starting of the drive support.

Claims (14)

1. Vehicle ( 1 ), in particular a bicycle, with:

• - a chain or belt drive that can be actuated by muscle power via pedals or hand cranks,
• - An electrical auxiliary drive, which has a drive-supporting electric motor and an associated control electronics or electronics, characterized by the following features:
• - The muscle-powered drive ( 2 ) and the auxiliary drive have separate, independent power transmission devices,
• - A motion sensor ( 10 ) is only arranged in the power train actuated by muscle power,
• - The motor control electronics ( 7 ) forms a value for the rotational speed of the chain or belt of the muscle-powered drive ( 2 ) from the signal of the motion sensor ( 10 ), wherein
• - The setpoint of the engine speed proportional to the rotational speed is specified.

2. Vehicle according to claim 1, characterized in that the motion sensor ( 10 ) generates a direction-dependent signal. 3. Vehicle according to claim 1 or 2, characterized in that the movement sensor ( 10 ) has a preferably driven by the chain ( 3 ) or the belt sensor roller ( 11 ) on the at least two pulse generator elements ( 12 , 12 a) in one of 180 ° different position are circumferentially arranged and that the sensor roller ( 11 ) is assigned at least one pickup ( 13 ) which is electrically connected to the motor control electronics ( 7 ). 4. Vehicle according to claim 3, characterized in that as pulse generator elements ( 12 , 12 a) magnets and as a pulse pick-up ( 13 ) at least one Hall probe or optionally reed contacts are provided. 5. Vehicle according to one of claims 1 to 4, characterized in that the motor control electronics ( 7 ) for evaluating the speed of the sensor roller ( 11 ) or the pulse frequency of the pickup ( 13 ) is formed. 6. Vehicle according to one of claims 1 to 5, characterized in that the control of the motor by the control electronics ( 7 ) in a low speed range of the biomechanical power transmission with a steep increase in the target engine speed (n _M ) and above this low Speed range with a flatter increase in the target engine speed (n _M ). 7. Vehicle according to one of claims 1 to 6, characterized in that the pulse generator elements ( 12 , 12 a) are heteropolar arranged permanent magnets. 8. Vehicle according to one of claims 1 to 7, characterized records that as pulse generator elements equipolar magnets by 360 ° / p and heteropolar magnets by unequal 360 ° / 2p with p-pole pairs are offset from one another. 9. Vehicle according to one of claims 1 to 8, characterized records that the pulse generator device with the pulse generator elements 4-pole, possibly 6-pole. 10. Vehicle according to one of claims 1 to 9, characterized in that the control electronics ( 7 ) has a device for limiting the power of the motor. 11. Vehicle according to one of claims 1 to 10, characterized in that the control electronics ( 7 ) has a power limitation of the motor preferably by means of a measuring device alone electrical motor sizes. 12. Vehicle according to one of claims 1 to 11, characterized in that the control electronics ( 7 ) has a power limitation of the motor via a limitation of the battery current. 13. Vehicle according to one of claims 1 to 12, characterized in that the control electronics ( 7 ) has a device for soft start and thus for smooth control of the motor. 14. Vehicle according to one of claims 1 to 13, characterized in that the biomechanical drive ( 2 ) has a gear shift, in particular a hub gear or a derailleur gear to adapt to a biomechanically advantageous drive movement.