DE29921874U1 - Electromagnetic machine for a vehicle, especially a bicycle - Google Patents

Description

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G 49169 S

Electromagnetic machine for a vehicle, in particular a

Bicycle

The present invention relates to an electromagnetic machine for a vehicle, in particular for a bicycle, according to the preamble of claim 1.

As is well known, motor vehicles use alternators that are driven by a V-belt to generate energy. These alternators are supplied with a control current via collectors to build up the excitation field so that the voltage remains constant at low or high speeds. However, this structure is subject to high levels of wear and tear and has losses caused by friction.

So-called dynamos are common on bicycles. These are attached to the bicycle tire, e.g. with a roller head, which transfers the rotation of the wheel to a generator in the dynamo. Using such a dynamo requires a lot of extra effort from the cyclist, as the dynamo's head wheel, which is pressed against the wheel by a strong spring, must also be turned. Using the dynamo also leads to tire wear. In bad weather conditions, such as rain or snow, where a functioning dynamo is particularly important, it can also happen that the dynamo's head wheel loses mechanical contact with the tire. This means that the head wheel just slides along the tire instead of rotating. This causes the bike's lights to fail.

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Hub and roller dynamos are also available on the market.

Another problem is that the output voltage is not regulated, which means that it fluctuates greatly depending on the slow or fast rotation of the head wheel. This can lead to the power supply of the lighting system becoming so high that individual lamps burn out.

The present invention is therefore based on the object of creating an electromagnetic machine for a vehicle, in particular for a bicycle, in which the transmission of the rotary motion between a rotating part, in particular a vehicle wheel, and a fixed part of the machine is improved.

This problem is solved by an electromechanical machine having the features of claim 1.

The main advantage of the present invention is that the transmission of the rotary motion between a rotating part of a vehicle, in particular a vehicle wheel, and a stationary part of the machine is improved. The machine can act as both a generator and a motor. Advantageously, the control of the output voltage is improved in generator mode and the torque is improved in motor mode. A particular advantage is also that a control field for generating a constant voltage can be generated without wear.

The invention and its embodiments are explained in more detail below in conjunction with the figures. They show:

Figure 1

a coil unit of the electromechanical machine according to the invention;

Figure 2

the coil unit of Figure 1 associated with a gear ring in the open state;

Figure 3

the coil unit of Figure 1 associated with the gear ring in the closed state;

Figure 4

a representation to explain the main magnetic flux resulting from the electromagnetic machine according to the invention and the arrangement of the control field coils;

Figure 5 or 6

Representations to explain the weakening or strengthening of the main flow;

Figures 7 to 9

Block diagrams for explaining the control circuit of the electromagnetic machine according to the invention;

Figure 10

the top view of the machine according to the invention;

a gear ring of the electromagnetic

Figure 11

a side view of the gear ring of Figure 10;

Figure 12

an embodiment of the electromagnetic machine according to the invention with several

customers;

Figure 13 shows a gear ring which is constructed in such a way that

the magnetic fluxes are segmented and

Figures 14 to 17 further developments of the invention.

The present invention relates to a contactless electromagnetic machine that operates according to the principle of electromagnetic induction. The machine has at least one coil unit that is attached to the frame or the like of a vehicle, in particular a bicycle, and at least one magnetically highly conductive return ring that has subdivisions and is attached to a rotating part of the vehicle, in particular to a wheel of a bicycle.

Explanation of generator operation.

The electromagnetic machine according to the invention consists of a coil unit 1, which is shown in Figure 1, and a gear ring 3, which is shown for example in Figure 2. The coil unit 1 contains a permanent magnet 5 and induction coils 7, 9 with core, whereby the permanent magnet 5 is arranged at an angle of 90° to the induction coils 7, 9. This angular position ensures that the magnetic stray field of the induction coils 7, 9 is perpendicularly penetrated, so that the resulting flux φ is very small. There is no overlap state.

Figure 2 shows the coil unit 1 arranged on a return ring 3 in the open state, whereby the magnetic flux

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φ is very small and is determined by air gaps in the magnetic circuit. In the open state, the air gap, which determines the magnetic flux, is relatively large compared to the magnetically highly conductive return ring. It offers resistance to the excitation field, which keeps the magnetic flux φ small. The teeth arranged in the circumferential direction of the return ring 3 and evenly spaced from one another are designated 11.

In the closed state shown in Figure 3, the return ring 3 is aligned with a pair of teeth 11, 11 to the coils 7, 9 of the coil unit 1 (overlap), which is why the magnetic circuit is closed. The magnetic flux φ is now only determined by the two small air gaps between the teeth 11, 11, which form the said pair of teeth, and the coils 7, 9 of the coil unit 1, which serves as the pickup unit in generator operation.

The continuous changes in state also result in a change in magnetic flux. Due to this change in flux, which also passes through the coils 7, 9, an induction is caused in the coils 7, 9, which counteracts the magnetic force. Electrical energy can therefore be tapped from the coils 7, 9. Due to high speeds or high flux densities (induction density measured in Tesla of the permanent magnets), the energy generation can fluctuate greatly. Both factors are proportional to the power generated.

Since high voltages are generated at high speeds and vice versa, this can be a disadvantage for a consumer connected to the coil unit 1. An additional excitation field is therefore connected to the magnetic circuit. This excitation field is generated by control field coils as shown in Figure 4.

13, 15, which are arranged on the permanent magnet 5. The excitation field can counteract the excitation field of the permanent magnet 5 or weaken it if the control field coils 13, 15 connected in series are controlled accordingly, or can strengthen it if the said excitation fields work together. The excitation field of the control field coils 13, 15 is generated with the help of a control circuit, which will be explained in more detail later in connection with Figures 7 to 9.

According to Figure 5, a weakening of the excitation field of the permanent magnet is achieved because the current flow in the control field coils 13 and 15 connected in series is controlled by the control circuit in such a way that the field generated in them acts opposite to the field of the permanent magnet. The field of the permanent magnet is designated in Figure 5 with (j>Magn. The control coil field generated by the control field coils 13 and 15 is designated with φ _&Xgr;ρ . Both fields <j> _Ma gn. and <j>sp together produce a resulting main flux (J> _res . , which is responsible for the voltage generated in the induction coils 7, 9. The induced voltage is relatively small due to the conditions described.

In contrast to this, according to Figure 6, the current flow through the control field coils 13 and 15 is controlled by the control circuit in such a way that the resulting excitation field φ _3ρ of the control field coils 13 and 15 is aligned with the permanent magnetic field <t>Magn. The resulting main flux (j) _re s. is therefore larger than that of Figure 5. The voltage induced in the coils 7, 9 is relatively large.

The control circuit 20 used to control the control field coils 13 and 15 is explained below in connection with Figures 7 to 9. The control circuit 20 essentially consists of a comparator 21 and a

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this downstream actuator 23. A reference variable w is fed to the comparator 21 by a circuit 25. The voltage X of an induction coil 7, 9 is present at the input of the comparator 21. The current for the control field coils 13, 15 is tapped at the output of the actuator 23.

The control current I of the actuator can be set via the reference variable w of the circuit 25. For example, the circuit 25 has the form of a variable resistor. Since the control variable y can have both a positive and a negative value, the actuator 23 should be a push-pull stage that is able to allow the current to flow in both directions. The magnetic field and the direction in which it should act are determined based on the direction of flow of the current in the control field coils 13 and 15.

If the voltage X at the induction coil 7 or 9 increases as a result of a high speed of the return ring 3, the value y at the output of the comparator 21 assumes a positive state (Fig. 8) due to the comparison: y = χ - w. This state or this value is determined from the difference between the value X (generated voltage) and the value w (setpoint voltage), y now serves as the control variable with which the actuator 23 is controlled. In the case described, the direction of current flow of the actuator 23 will be such that the connected control field coils 13, 15 generate an opposing field and in fact as strong as determined by the value y. The resulting magnetic flux φ _ΓΘΩ . is weakened. The induced voltage at the induction coils 7, 9 drops.

If, on the other hand, the voltage at the induction coils 7, 9 falls below the value w, the value of y assumes a negative state (Fig. 9). The actuator 23 is now negatively controlled, which results in the current flow through the control field coils 13 and 15 being reduced with respect to its

direction is changed. The control field thus created interacts with the field of the permanent magnet 5, which is why the resulting magnetic flux φ _Γβ3 increases and the voltage induced at the induction coils 7 and 9 increases.

Figures 10 and 11 show the structure of a return ring 3. This essentially has the shape of a ring from which individual teeth 11, which are evenly spaced from one another along the circumference of the ring, protrude to one side. In order to be able to achieve a frequency increase without increasing the rotational frequency of the return ring 3, the division into the individual segments can be made smaller. This means that the width of the teeth 11 and the spaces between two teeth 11 becomes smaller.

If more power is required, several coil units 1 (acceptance units) can be connected together as shown in Figure 12. Care should be taken to ensure that the individual permanent magnets 5 are set with the same poles, i.e. that the south poles of two adjacent magnets and the north poles of two adjacent magnets are adjacent to each other, otherwise the resulting magnetic field would not run through the induction coils 7, 9, but would be directed outwards. In this case, only the two outer induction coils 7, 9 would contribute to the induction.

The induction coils 7, 9 of the individual coil units 1 can be connected either in series or in parallel. The same applies to the control field coils 13, 15 of the individual coil units 1. The induction coils 7, 9 located on the outside have a core cross-section that is 2 times smaller than a tooth cross-section, since only the magnetic flux of one

magnets and not two magnetic fluxes as with the other induction coils 7/9.

When the induction coils 7, 9 are connected in series, the magnetic field of the permanent magnets 5 and the field of the control field coils 13, 15 are pushed outwards, which is why only the two outer induction coils contribute to the electrical induction.

A mixed parallel or series connection of the induction coils is also conceivable. The same applies to the control field coils.

According to Figure 13, an increase in the induced voltage can be achieved if the gear ring 3' is constructed in such a way that individual U-shaped tooth segment pairs 33 are arranged next to one another in the circumferential direction on a non-magnetic base plate 31, in such a way that the legs of the U follow one another in the circumferential direction and the cross parts connecting the legs are fastened to the non-magnetic base plate 31. There is an air gap 35 between each two tooth segment parts of two adjacent tooth segment pairs 33 that face one another. This design ensures that the flow of flux is interrupted more quickly. Due to this faster interruption, the induced voltage is increased. The magnetic flux can therefore no longer pass into other paths, but is held back by the individual air gaps 35 in the tooth segment parts. This results in greater effectiveness.

Figure 14 shows another embodiment of the coil unit 71, in which two permanent magnets 51 and 52 are arranged perpendicular to a yoke part 53. The magnetic stray fields of the permanent magnets 51, 52 pass through the coils 7, 9 with core horizontally, since the permanent magnets 51, 52 are each

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Axis of the coils 51 and 52 are arranged coaxially, whereas in the coil unit 1 of Figure 1 the permanent magnet 5 is aligned perpendicular to the axes of the coils 7, 9.

Figures 15 to 17 show an embodiment in which the yoke ring 30 is designed in such a way that it does not cause a yoke in the circumferential direction as in Figure 10, but in the radial direction. This means that the individual yoke teeth 110 are arranged on a carrier part 310 in such a way that they run in the radial direction and have a length that is so great that, according to Figures 16 and 17, the coil units 1 and 71 can be completely covered by the yoke teeth 110 when the yoke ring 30 rotates. The individual coil units, which can be provided in any number, are also aligned radially. The yoke ring 30 is relatively simple and inexpensive to produce in terms of construction and material.

Claims (12)

1. Electromagnetic machine for a vehicle, in particular a bicycle, characterized by at least one coil unit ( 1 ; 71 ) to be fastened to a vehicle frame of the vehicle and a return part ( 3 ; 30 ) to be fastened to a rotating part of the vehicle, which allows the magnetic flux in the coil unit ( 1 ; 71 ) to change during its rotation. 2. Electromagnetic machine according to claim 1, characterized in that the coil unit ( 1 ) has a rod-shaped permanent magnet ( 5 ), at the end regions of which a coil ( 7 , 9 ) with a core is arranged in such a way that the axis of the coil ( 7 , 9 ) runs perpendicular to the longitudinal extension of the permanent magnet ( 5 ). 3. Electromagnetic machine according to claim 1, characterized in that the coil unit ( 71 ) has two permanent magnets ( 51 , 52 ) which are spaced apart from one another and whose one end is bridged by a yoke part ( 53 ), and that at the other ends of the permanent magnets ( 51 , 52 ) a coil ( 7 , 9 ) with a core is arranged in such a way that the axes of the coils ( 7 , 9 ) and the permanent magnets ( 51 , 52 ) are aligned coaxially with one another. 4. Electromagnetic machine according to one of claims 1 to 3, characterized in that the return part ( 3 ) has the shape of a toothed ring which has teeth ( 11 ) evenly spaced from one another in the circumferential direction, and that at least one coil unit ( 1 ) is arranged on an axially offset line of the same circumference. 5. Electromagnetic machine according to claim 4, characterized in that the distance between two adjacent teeth ( 11 ) of the return part ( 3 ) is equal to the distance between two coils ( 7 , 9 ) of the coil unit ( 1 ). 6. Electromagnetic machine according to one of claims 1 to 3, characterized in that the yoke part ( 30 ) has yoke teeth ( 110 ) which follow one another in the circumferential direction and are evenly spaced from one another and are dimensioned so long in the radial direction that they can cover the coils ( 7 , 9 ) of at least one radially aligned coil unit ( 1 ; 71 ). 7. Electromagnetic machine according to one of claims 1 to 6, characterized in that at least one control field coil ( 13 , 15 ) is arranged on a permanent magnet ( 5 ) of the coil unit ( 1 ), to which a field which is aligned in the same direction as or opposite to the magnetic field of the permanent magnet ( 5 ) can be applied in order to regulate the induction voltage at the coils ( 7 , 9 ). 8. Electromagnetic machine according to claim 8, characterized in that two control field coils ( 13 , 15 ) spaced apart from one another and connected in series are arranged on the permanent magnet ( 5 ). 9. Electromagnetic machine according to claim 8 or 9, characterized in that a control loop circuit ( 20 ) is provided which has a comparator ( 21 ) which generates a control variable (y) corresponding to a difference between the voltage at the coils ( 7 , 9 ) and a reference value (w) of an actuator ( 25 ) at an actuator ( 23 ) which, depending on the sign of the control variable (y) of the at least one control field coil ( 13 , 15 ), generates a magnetic flux which is in the same direction as or opposite to the magnetic flux of the permanent magnet ( 5 ). 10. Electromagnetic machine according to one of claims 1 to 10, characterized in that the return part ( 3 ; 30 ) on a non-magnetic base plate ( 31 ) comprises individual U-shaped tooth segment pairs ( 33 ) next to one another in the circumferential direction, between each of which an air gap ( 35 ) is arranged. 11. Electromagnetic machine according to one of claims 1 to 11, characterized in that in the circumferential direction of the yoke part ( 3 ) several coil units ( 1 ) are arranged one behind the other in such a way that the same poles of the permanent magnets ( 5 ) are arranged next to each other and that the outer end regions of the outer permanent magnets ( 5 ) are each assigned a coil ( 7 , 9 ) whose core has half the width of a tooth ( 11 ), and that between the outer coils ( 7 , 9 ) the mutually facing end regions of two adjacent permanent magnets ( 5 ) are each assigned a common coil ( 7/9 ) with a core whose width corresponds to the width of a tooth ( 11 ). 12. Electromagnetic machine according to one of claims 1 to 11, characterized in that the coils ( 7 , 9 ; 51 , 52 ) are connected in series or in parallel.