Drive device for a bicycle driven by an electric motor

Abstract

What is disclosed is a drive device for a bicycle driven by an electric motor, having a main frame having a swing arm bearing, and a rear linkage element arranged at the swing arm bearing. The drive device has a pedal crank as a first drive for providing a first drive force, having a first drive shaft, a center electric motor as a second drive for providing a second drive force, and an output element having an output shaft, configured to receive the first and/or second drive forces and transfer same to the bicycle wheel to be driven. The center axis of the output shaft is radially distanced from the center axis of the first drive shaft and the output shaft is arranged relative to the swing arm bearing such that a radial distance between the center axis of the swing arm bearing and the center axis of the output shaft is smaller than a radial distance between the center axis of the swing arm bearing and the center axis of the first drive shaft.

Claims

1. A drive device for a bicycle driven by an electric motor, comprising a main frame comprising a swing arm bearing, and a rear linkage element arranged at the swing arm bearing, the drive device comprising: a pedal crank as a first drive for providing a first drive force, the first drive comprising a first drive shaft, a center electric motor as a second drive for providing a second drive force, and an output element comprising an output shaft, the output element being configured to receive the first and/or second drive forces and transfer the same to the wheel of the bicycle to be driven, wherein the center axis of the output shaft is radially distanced from the center axis of the first drive shaft and the output shaft is arranged relative to the swing arm bearing such that a radial distance between the center axis of the swing arm bearing and the center axis of the output shaft is smaller than a radial distance between the center axis of the swing arm bearing and the center axis of the first drive shaft, and wherein the swing arm bearing is positioned at the main frame such that the bicycle comprises a suspension oblique angle of 5 to 30, or 10 to 20, or 15 if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

2. The drive device in accordance with claim 1, wherein the radial distance between the center axis of the first drive shaft and the center axis of the output shaft is 200 mm to 300 mm, or 100 mm to 200 mm.

3. The drive device in accordance with claim 1, wherein the radial distance between the center axis of the swing arm bearing and the center axis of the output shaft is less than 200 mm, or less than 100 mm, or less than 50 mm.

4. The drive device in accordance with claim 1, wherein the center axis of the swing arm bearing, relative to a plane parallel to the road surface, is arranged above the center axis of the output element.

5. The drive device in accordance with claim 1, wherein the center axis of the swing arm bearing, relative to a plane parallel to the road surface, is arranged below the center axis of the output element.

6. The drive device in accordance with claim 1, wherein the radial distance between the center axis of the output shaft and the center axis of the swing arm bearing equals zero so that the center axis of the output shaft and the center axis of the swing arm bearing are arranged concentrically.

7. The drive device in accordance with claim 1, wherein the output element and the center electric motor are arranged relative to each other such that the center axis of the output element and the center axis of an output shaft of the center electric motor are arranged concentrically.

8. The drive device in accordance with claim 1, wherein the output element transfers the drive force to the wheel of the bicycle to be driven by means of a force transmission element and the force transmission element is arranged between the output element and the wheel such that a force is applied to a rear axis by means of applying a pull force to a tight side of the force transmission element, wherein a force action line of the force is located below the center axis of the swing arm bearing or below the instant center if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

9. The drive device in accordance with claim 1, the drive device being arranged at the main frame to be immobile.

10. A bicycle driven by an electric motor, comprising a drive device in accordance with claim 1.

11. A bicycle frame comprising a main frame comprising a swing arm bearing, a rear linkage part arranged at the swing arm bearing, and a drive device in accordance with claim 1.

12. A drive device for a bicycle driven by an electric motor, comprising a main frame comprising a swing arm bearing, and a rear linkage element arranged at the swing arm bearing, the drive device comprising: a pedal crank as a first drive for providing a first drive force, the first drive comprising a first drive shaft, a center electric motor as a second drive for providing a second drive force, and an output element comprising an output shaft, the output element being configured to receive the first and/or second drive forces and transfer the same to the wheel of the bicycle to be driven, wherein the center axis of the output shaft is radially distanced from the center axis of the first drive shaft and the output shaft is arranged relative to the swing arm bearing such that a radial distance between the center axis of the swing arm bearing and the center axis of the output shaft is smaller than a radial distance between the center axis of the swing arm bearing and the center axis of the first drive shaft, wherein the rear linkage element is implemented as a multi pivot, comprising an instant center as an instantaneous center of rotation, and the rear linkage element is positioned at the main frame such that the bicycle comprises a suspension oblique angle of 5 to 30, or 10 to 20, or 15 if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are illustrated in the drawings and will be discussed below, in which:

(2) FIG. 1 shows a schematic drawing of a full-suspension bicycle comprising a rear linkage element implemented as a multi pivot;

(3) FIG. 2 shows a side view of a bicycle driven by an electric motor, comprising an inventive drive device;

(4) FIG. 3 shows a side view of an inventive drive device;

(5) FIG. 4 shows a side view of a bicycle driven by an electric motor, comprising a rear linkage element implemented as a single pivot, and an inventive drive device;

(6) FIG. 5 shows a side view of a bicycle driven by an electric motor, comprising a rear linkage element implemented as a multi pivot, and an inventive drive device;

(7) FIG. 6 shows an enlarged section of a bicycle driven by an electric motor, comprising an inventive drive device in a side view;

(8) FIG. 7 shows a side view of an inventive drive device;

(9) FIG. 8 shows a front perspective view of a bicycle driven by an electric motor, comprising an inventive drive device, without illustrating the front wheel and the suspension fork;

(10) FIG. 9 shows a side view of a bicycle driven by an electric motor, comprising an inventive drive device having a chain drive;

(11) FIG. 10 shows a side view of a bicycle driven by an electric motor, comprising an inventive drive device having a cog belt drive;

(12) FIG. 11 shows a side view of an inventive drive device;

(13) FIG. 12 shows a schematic drawing of an inventive drive device in a side view;

(14) FIG. 13 shows a side view of a conventional prior-art full-suspension bicycle;

(15) FIG. 14 shows another side view of a conventional prior-art full-suspension bicycle; and

(16) FIG. 15 shows a schematic drawing of a full-suspension bicycle for discussing determining the instant center.

DETAILED DESCRIPTION OF THE INVENTION

(17) So-called e-bikes are generally meant by the term bicycles driven by an electric motor. Among these types of e-bikes which, for defining the present disclosure, fall under the term bicycle driven by an electric motor, are both bicycles driven by an electric motor which may be driven exclusively by the drive force of an electric motor, and bicycles supported by an electric motor which can switch in a drive force of an electric motor in support of the pedaling force.

(18) The shaft of the first drive, the shaft of the output element and an output shaft of the electric motor comprise a direction of extension along their longitudinal axis. A radial distance in the sense of the present disclosure relates to this longitudinal axis passing in the direction of extension of the respective shaft, which means that radial means a radial direction when starting from the longitudinal axis. The direction of extension of the longitudinal axis is usually roughly orthogonal to a vertical central plane of the bicycle extending between the rear wheel and the front wheel.

(19) The invention is, among other things, based on having recognized that a starting torque pitch support may be realized by means of varying the kinematics of the rear linkage element. The technical background is to be discussed below briefly making reference to FIG. 1.

(20) FIG. 1 shows a full-suspension mountain bike 100 with a person 101 sitting thereon. The mountain bike 100 comprises a main frame 102 and a rear linkage element swingingly arranged at the main frame 102. The rear swing element 103 is designed to be a multi-pivot element having an additional point of rotation 104 in the region of the chain stay 105.

(21) An instant center M.sub.1 which is considered to be the instantaneous point of rotation at a time t.sub.1 can be designed for this multi-pivot element. The instant center M.sub.1 is the point of intersection of a first straight 107 and a second straight 108. The first straight 107 passes through the additional point of rotation 104 in the region of the chain stay 105 and through the swing arm bearing 106. The second straight 108 passes through the pivot point 109 between the seat stay 110 and the rocker 111 and through the pivot point 113 between the seat tube 114 and the rocker 111.

(22) Another straight 112 may be defined through the instant center M.sub.1 and the rear axis 115. This straight 112 defines the suspension oblique angle of the bicycle 100. As has been mentioned above, conventional bicycles are designed such that they comprise a suspension oblique angle of =0. However, the present invention makes use of, among other things, the realization that a starting torque pitch support may be realized by suitably selecting the suspension oblique angle .

(23) The suspension oblique angle generates a support effect which in certain riding situations of high torque, for example when accelerating, starting or riding uphill, prevents the rear wheel suspension from being compressed by the dynamic wheel load shifting. In particular in e-bikes, due to the greater drive power and the stronger ability to accelerate, an effective starting torque pitch support is desirable.

(24) In an electrically driven mountain bike, for example, a suspension oblique angle of about 15 in a state of static compression is very good. This state of static compression is also referred to as SAG. The SAG results if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection. This means that, if the rider 101 sits or stands on the bike 100 and does not move, he or she will apply a static load to the bike 100 by his or her weight alone, the load having a weight force G. Both the suspension fork 116 arranged in the front and the damper 117 arranged in the back are compressed here.

(25) Ideally, the fork 116 and the damper 117 are to be compressed by about 10% to 35% of their respective total spring deflection. This range is also referred to as SAG or negative spring deflection. Thus, the spring elements 116, 117 comprise a sufficient range in order to be both compressed and decompressed while riding the bike. The bike 100 illustrated in FIG. 1 is shown in the SAG, i.e. the bike is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

(26) The theory behind the chassis-kinematically realizeable starting torque pitch support is that, starting from the front wheel axis 118, a perpendicular 119 to the horizontal 120 of the center of gravity 121 (bicycle 100 and rider 101 form a center of gravity 121 over the road 122) is generated. The point of intersection between these two lines will produce a construction point S.sub.1.

(27) An oblique rising straight 124 can be drawn between this point of intersection S.sub.1 and the rear wheel contact point 123. This straight 124 is the so-called squat line.

(28) If the suspension oblique angle and the squat line 124 are parallel to each other, this is referred to as a 100% anti-squat bike chassis. In this case, the bike chassis does not react to accelerations, which means that it is neither compressed nor decompressed. If the suspension oblique angle is below the squat line 124, the rear linkage element will compress when accelerating, starting etc. If the suspension oblique angle is above the squat line 124, the rear linkage element will decompress when accelerating, starting etc.

(29) If, for example, the wheel base is increased or the height of the center of gravity 121 above the road 122 is reduced, consequently smaller a suspension oblique angle will be used in order to keep the starting torque pitch support to the same extent.

(30) As has already been discussed before referring to FIG. 13, the direction of the force F.sub.A applied to the rear wheel axis depends, among other things, on the chain pull direction F.sub.C. When having a closer look at the bicycle 100 in FIG. 1 under this aspect, it can be realized that the force F.sub.A applied to the rear wheel axis 115 is on a force action line 125 which is located relatively far below the swing arm bearing 106. The result of this is an excessive decompression of the rear linkage element when accelerating, starting or riding uphill etc.

(31) When compared to bicycles driven by muscle power, e-bikes provide greater a torque, i.e. the chain pull force F.sub.C and also the force F.sub.A applied to the rear wheel axis 115 are considerably greater. This provides for stronger a decompression of the rear linkage element in e-bikes. In the end, what follows from what has been mentioned above is that a suspension oblique angle of >0 in e-bikes will result in an undesired and much too strong decompression of the rear linkage element, due to the increased torque.

(32) This is why conventional bikes, also e-bikes, nowadays comprise a suspension oblique angle in the SAG of =0 and the starting torque pitch support is regulated via the chain pull. However, the present invention realizes a starting torque pitch support both by means of the chain pull and by means of the bike chassis kinematics.

(33) FIG. 2 shows a bicycle 10 driven by an electric motor, comprising an inventive drive device 1. The bicycle 10 driven by an electric motor may also be referred to as e-bike. This may be a classic e-bike where the motor power can be regulated by means of a twist handle or the like and the e-bike may be driven solely by the electric motor. However, this may also be a so-called pedelec where the rider is supported when pedaling by switching in the electric motor in a way regulated by load.

(34) The bicycle 10 driven by an electric motor comprises a main frame 3. Usually, the main frame 10 consists of a top tube 21, a head tube 22, a down tube 23 and a seat tube 24. The bicycle 10 driven by an electric motor is a full-suspension bicycle, a so-called fully bike.

(35) The main frame 2 additionally comprises a swing arm bearing 3 and a rear linkage element 4 arranged at the swing arm bearing 3. The rear linkage element 4 is arranged at the swing arm bearing 3 and thus connected to the main frame 2 in a hinged manner. The rear linkage element 4 usually comprises a chain stay 26 and a seat stay 25. As can be recognized in FIG. 2, the chain stay 26 may exemplarily be arranged at the swing arm bearing 3. The rear linkage element may be implemented as a single pivot or a multi pivot.

(36) The drive device 1 comprises a pedal crank 5. The pedal crank 5 serves as a first drive for providing a first drive force. The pedal crank 5, or first drive, comprises a first drive shaft 6. The drive shaft 6 may be an axis or shaft of the pedal crank 5 connected to a crank arm.

(37) In addition, the drive device 1 comprises a center electric motor 7. The center electric motor 7 serves as a second drive for providing a second drive force. As can be recognized from FIG. 2, the center electric motor 7 is arranged about in the center, i.e. between the front wheel and the rear wheel of the bicycle 10. More precisely, the center motor 7 is arranged between the down tube 34 and the seat tube 24. This embodiment of a center motor 7 is to be differentiated from other drive concepts, like wheel hub motors.

(38) Additionally, the drive device 1 comprises an output element 8 having an output shaft 9. The output element 8 is configured to receive the first and/or second drive forces and transfer same to the wheel 11 of the bike 10 to be driven.

(39) FIG. 3 shows an enlarged illustration of the drive device 1. The first drive shaft 6 and the electric motor 7 can be recognized. Additionally, the output element 8 can be recognized. The output element 8 is exemplarily illustrated as an output shaft 9 having a gear 12 arranged thereon. The center axis 13 of the output shaft 9 is radially distanced (R.sub.1) from the center axis 14 of the first drive shaft 6.

(40) In addition, FIG. 3 shows a swing arm bearing 3 arranged at the main frame 2. The swing arm bearing 3 is arranged at the seat tube 24 illustrated. A swing arm or the rear linkage element 4 is arranged at the swing arm bearing 3 and thus connected to the main frame 2. The rear linkage element 4, however, is not illustrated in FIG. 3 for reasons of clarity.

(41) In accordance with the invention, the output shaft 9 is arranged relative to the swing arm bearing 3 such that a radial distance R.sub.2 between the center axis 16 of the swing arm bearing 3 and the center axis 13 of the output shaft 9 is smaller than a radial distance R.sub.3 between the center axis 16 of the swing arm bearing 3 and the center axis 14 of the first drive shaft 6.

(42) In accordance with an embodiment, the radial distance R.sub.1 between the center axis 14 of the first drive shaft 6 and the center axis 13 of the output shaft 9 is about 200 mm to 300 mm and advantageously about 100 mm to 200 mm.

(43) In accordance with an embodiment, the radial distance R.sub.2 between the center axis 16 of the swing arm bearing 3 and the center axis 13 of the output shaft 9 is less than 200 mm, advantageously less than 100 mm and even more advantageously less than 50 mm.

(44) The position of the swing arm bearing 3 is illustrated only exemplarily in FIG. 3. The swing arm bearing 3 may also be arranged at different locations, like directly at the drive device 1. In FIG. 3, the swing arm bearing 3 is arranged above the output shaft 9. However, it is also conceivable for the swing arm bearing 3 to be arranged below the output shaft 9.

(45) In accordance with the invention, the swing arm bearing 3 is arranged close to the output shaft 9. More precisely, the swing arm bearing 3 is arranged closer to the output shaft 9 than to the first drive shaft 6. This means that, in accordance with the invention, the radial distance R2 between the output shaft 9 and the swing arm bearing 3 is smaller than the radial distance R3 between the output shaft 9 and the first drive shaft 6.

(46) FIG. 4 shows a bicycle 10 comprising an inventive drive device 1, wherein the swing arm bearing 3 is positioned at the main frame 2 such that the bicycle 10 will comprise a suspension oblique angle of 5 to 30 if the bicycle 10 is subjected to a static load resulting in a negative spring deflection between 15% and 35% of the total spring deflection.

(47) In other words, in the state illustrated in FIG. 4, the bicycle 10 is in the SAG, which means that the spring elements 116, 117 and, in particular, the damper 117 arranged in the back are compressed by about 15% to 35% of their total spring deflection.

(48) The bicycle 10 illustrated, or the rear linkage element 4 of the bicycle 10, is designed as a single pivot. Consequently, the straight 30 passing through the rear axis 115 and through the swing arm bearing 3 defines the suspension oblique angle relative to the road surface 122.

(49) It can be recognized from FIG. 4 that the suspension oblique angle may be influenced by suitably positioning the swing arm bearing 3 at the main frame 2. In accordance with the invention, the swing arm bearing 3 is positioned at the main frame 2 such that the bicycle will comprise a suspension oblique angle of 5 to 30, advantageously 10 to 20 and even more advantageously of about 15 if the bicycle 10 is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

(50) FIG. 5 shows another embodiment of a bicycle 10 comprising an inventive drive device 1. In contrast to the embodiment discussed referring to FIG. 4, in this case the rear linkage element 4 is designed a multi pivot, i.e. the rear linkage element 4 comprises an additional hinge 104. The additional hinge 104 is arranged in the region of the chain stay 105. However, it is also conceivable for the additional hinge 104 to be arranged in the region of the seat stay 110.

(51) The bicycle 10 illustrated in FIG. 5 is in the SAG, i.e. is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection of the damper 117.

(52) In the multi pivot shown in FIG. 5, an instant center M.sub.1 can be designed for the state illustrated. A first straight 107 intersects the additional hinge 104 and the swing arm bearing 3. A second straight 108 passes through the hinge 109 between the seat stay 110 and the rocker 111 and through the hinge 113 between the rocker 111 and the main frame 2 or seat tube 24. The point of intersection of the two straights 107, 108 results in the instant center M.sub.1.

(53) A straight 31 passes through this instant center M.sub.1 and the rear axis 115. This straight 31 defines the suspension oblique angle relative to the road surface 122 in a multi pivot, as is exemplarily illustrated in FIG. 5.

(54) It is to be mentioned that the designed instant center M.sub.1 applies only for the illustrated state of the bike 10. As soon as the bicycle 10 is compressed or decompressed, the position of the straights 107, 108 relative to each other changes and the instant center is shifted to a different position. The instant center is the state-dependent instantaneous point of rotation of the rear linkage element 4 by which the rear axis 115 pivots in the state illustrated.

(55) The rear linkage element 4 illustrated in FIG. 5 consequently is designed as a multi pivot having an instant center M.sub.1 as an instantaneous point of rotation. In accordance with the invention, the rear linkage element 4 is positioned at the main frame 2 such that the bicycle 10 will comprise a suspension oblique angle of 5 to 30, advantageously 10 to 20 and even more advantageously of about 15 if the bicycle 10 is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

(56) FIG. 6 shows an enlarged section of a bicycle 10 comprising an inventive drive device 1.

(57) The road surface 122 and a plane 60 in parallel thereto can be recognized. The plane 60 parallel to the road surface passes through the center axis 13 of the output element 8. The swing arm bearing 3 may be arranged at the main frame 2 such that the center axis of the swing arm bearing 3 is arranged above this plane 60. In this case, a force F.sub.A applied to the rear wheel axis 115 by means of chain pull results in decompression of the rear linkage element 4.

(58) In an alternative embodiment, the swing arm bearing 3 may be arranged at the main frame 2 such that the center axis of the swing arm bearing 3 is arranged below the plane 60. In this case, a force F.sub.A acting on the rear wheel axis 115 by means of the chain pull results in compression of the rear linkage element 4.

(59) FIG. 7 shows the enlarged illustration of the inventive drive device 1, as has already been shown in FIG. 3, again. The center axis 13 of the output element 8 can be recognized. In addition, the plane 60 parallel to the road surface 122 is shown.

(60) The swing arm bearing 3 may thus be arranged relative to the center axis 13 of the output element 8 such that the center axis of the swing arm bearing 3 is arranged either above or below the plane 60, depending on which behavior (compression or decompression) of the rear linkage element is desired.

(61) Exemplarily, a circle of a radius R.sub.2 around the center axis 13 of the output element 8 is shown. The radius R.sub.2 exemplarily describes a region where the center axis of the swing arm bearing 3 may be arranged. The swing arm bearing 3 may exemplarily be arranged around the center axis 13 of the output element 8 such that the center axis of the swing arm bearing 3 is distanced radially, like by a value R.sub.2, from the center axis 13 of the output element 8.

(62) In FIG. 7, such a potential point of attachment 70 is shown purely exemplarily. In accordance with the invention, the swing arm bearing 3 may be arranged around the output element 8 such that the center axis of the swing arm bearing 3 comprises any radial distance to the center axis 13 of the output element 8, but while keeping the inventive condition that the radial distance R.sub.2 between the center axis of the swing arm bearing 3 and the center axis 13 of the output shaft 9 be smaller than the radial distance R.sub.3 between the center axis of the swing arm bearing 3 and the center axis 14 of the first drive shaft 6.

(63) The swing arm bearing 3 consequently is to be arranged close to the output element 8 and advantageously closer to the output element 8 than to the drive shaft 6.

(64) In an advantageous implementation of the invention, the radial distance R.sub.2 between the center axis 13 of the output shaft 9 and the center axis of the swing arm bearing 3 equals zero (R.sub.2=0). This means that the center axis 13 of the output shaft 9 and the center axis of the swing arm bearing 3 are concentric or coaxial.

(65) This can be recognized clearly in FIG. 8. FIG. 8 shows a front perspective view of a bicycle comprising an inventive drive device 1. For improved clarity, the suspension fork and the front wheel are not illustrated.

(66) It can be recognized here that the swing arm bearing 3 and the output element 8 are arranged to be coaxial to each other. The center axis 13 of the output element 8 and the center axis 16 of the swing arm bearing 3 are thus located on a common axis 81. This means that the axis 81 is the common center axis of the output element 8 and the swing arm bearing 3.

(67) Additionally, the center axis 14 of the first drive, i.e. the pedal crank 5, is shown. The center axis 14 of the first drive 5 is in parallel to the common center axis 81 of the swing arm bearing 3 and the output element 8. Additionally, it can be recognized that the output element 8 and the swing arm bearing 3 are arranged to be radially distanced from the first drive 5. More precisely, the radial distance R.sub.1 between the center axis 14 of the first drive 5 and the center axis 13 of the output element 8 can be seen. Since the output element 8 and the swing arm bearing 3 are arranged coaxially, the radial distance R.sub.3 between the center axis of the first drive 5 and the center axis 16 of the swing arm bearing 3 equals the radial distance R.sub.1 between the center axis 14 of the first drive 5 and the center axis 13 of the output element 8 (R.sub.1=R.sub.3).

(68) FIG. 9 shows a side view of a bicycle 10 comprising an inventive drive device 1. Again, the bicycle 10 is shown in the SAG, i.e. in a static load state where a static force acts on the bicycle 10, which causes compression of the damper 117 by 10% to 35% of the total spring deflection of the damper 117.

(69) As has already been mentioned before, the direction of the force F.sub.A applied to the rear axis 115 is determined by the pull direction of the force transmission means between the output element 8 and the rear wheel 96.

(70) In the embodiment shown in FIG. 9, a conventional bicycle chain 90 is illustrated as force transmission means. The bicycle chain 90 comprises a slack side 91 and a tight side 92. The output element 8 comprises a pinion 93 around which the bicycle chain 9 is wound.

(71) When applying a pull force to the tight side 92 of the bicycle chain 90, the result will be a chain pull force F.sub.C acting along the force action line 94. The resulting force F.sub.A acting on the rear wheel axis 115 is directed to be parallel to the chain pull force F.sub.C. The force F.sub.A acting on the rear wheel axis 115 acts along the force action line 95.

(72) The output element 8 transmits a drive force F.sub.C to the rear wheel 96 of the bicycle 10 to be driven by means of the bicycle chain 90. Thus, the bicycle chain 90 is arranged between the output element 8 and the rear wheel 96 such that a force F.sub.A is applied to the rear axis 115 by means of applying a pull force to the bicycle chain 90, wherein the force action line 95 of the force F.sub.A is located below the center axis 16 of the swing arm bearing 3. This is particularly true for rear linkage elements 4 designed as single pivots. The result will be decompression of the rear linkage element 4 when accelerating, starting, riding uphill etc.

(73) When the rear linkage element 4 is a multi pivot, in accordance with the invention, the same will be designed such that the force action line 95 of the force F.sub.A acting on the rear wheel axis 115 is located below the instant center if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

(74) FIG. 10 shows another embodiment of a bicycle 10 comprising an inventive drive device 1. Here, the force transmission means is implemented as a cog belt 99. Correspondingly, the output element 8 comprises a gear 98 around which the cog belt 99 is wound. The cog belt 99 comprises a tight side 92 and a slack side 91.

(75) When applying a pull force to the tight side 92 of the cog belt 99, the result will be a pull force F.sub.C acting along the force action line 94. The resulting force F.sub.A acting on the rear wheel axis 115 is directed to be parallel to the pull force F.sub.C. The force F.sub.A acting on the rear wheel axis 115 acts along the force action line 95.

(76) This means that the output element 8 transmits a drive force F.sub.C to the rear wheel 96 of the bicycle 10 to be driven by means of the cog belt 99. Thus, the cog belt 99 is arranged between the output element 8 and the rear wheel 96 such that a force F.sub.A is applied to the rear axis 115 by means of applying a pull force to the cog belt 99, wherein the force action line 95 of the force F.sub.A is located below the center axis 16 of the swing arm bearing 3. This particularly applies to rear linkage elements 4 designed as single pivots. The result is decompression of the rear linkage element 4 when accelerating, starting, riding uphill etc.

(77) When the rear linkage element 4 is a multi pivot, in accordance with the invention, it is designed such that the force action line 95 of the force F.sub.A acting on the rear wheel axis 115 is located below the instant center if the bicycle is subjected to a static load resulting in a negative spring deflection between 10% and 35% of the total spring deflection.

(78) This means that the invention provides a starting torque pitch support which may be realized both by means of the kinematics of the rear linkage element 4 and by means of applying a pull force to the respective force transmission means 90, 99.

(79) FIG. 11 shows an enlarged side view of an inventive drive device 1 again. The drive device 1 comprises several components, among others drive and output elements of different gear ratios.

(80) The first drive 5 comprises a first drive shaft 6. The drive shaft 6 may be the bottom bracket shaft of the pedal crank. A gear 41 is arranged at the first drive shaft 6.

(81) The output element 8 comprises an output shaft 9. A gear 12 is arranged at the output shaft 9. The gear 12 arranged at the output shaft 9 is coupled to the gear 41 arranged at the drive shaft 6 of the first drive 5 by means of a cog belt 46.

(82) The gear 12 arranged at the output shaft 9 comprises fewer teeth or smaller a diameter than the gear 41 arranged at the drive shaft 6 of the first drive 5. This means that a speeding gear ratio from the first drive 5 to the output element 8 results, wherein the gear ratio is 3:1 or advantageously 2:1.

(83) Another gear 42 is arranged at the output shaft 9. The second gear 42 is coupled to a gear 43 arranged at an output shaft 44 of the electric motor 7 by means of a cog belt 45.

(84) The gear 42 arranged at the output shaft 9 comprises more teeth or greater a diameter than the gear 43 arranged at the output shaft 43 of the electric motor 7. Thus, a gear ration to slow down results from the drive (electric motor 7) to the output element 8, wherein the gear ration is 1:2 or advantageously 1:3.

(85) The cog belts 45, 46 illustrated may be replaced by drive chains. In this case, the gears 12, 41, 42, 43 would advantageously be implemented as pinions. The cog belts 45, 46 illustrated, however, may also be replaced by V-belts. In this case, the gears 12, 41, 42, 43 would advantageously be implemented to be profile rolls. Direct engagement of at least one pair of gears between the electric motors 7 and the output element 8 and/or between the first drive 5 and the output element 8 would also be conceivable.

(86) The drive device 1 may comprise a casing 47 where the first drive 5, the electric motor 7 and the output element 8 are arranged. The electric motor 7 may be mounted to the casing 47, wherein cooling fins may be provided in the casing 47 at the location of mounting in order to cool down the motor 7. The electric motor 7 may be implemented to be an external rotor motor and, advantageously, a torque motor.

(87) In FIG. 11, a straight 48 can be recognized, passing through the center axis 14 of the first drive 5. This straight 48 is perpendicular to the road surface 122 (not illustrated here). The center axis 13 of the output element 8 and the center axis 49 of the output shaft 44 of the electric motor 7 are arranged, in a forward riding direction, in front of the perpendicular 48 and, thus, in front of the center axis 14 of the first drive 5.

(88) However, it is also conceivable for the output element 8 to be arranged such that its center axis 13, in the forward riding direction, is arranged behind the perpendicular 48 and, thus, behind the center axis 14 of the first drive 5. Thus, the chain stay of the rear linkage element can be kept short, in case the center axis 13 of the output element 8 is arranged coaxially to the swing arm bearing 3.

(89) In accordance with an embodiment (not illustrated here in greater detail), the electric motor 7 may be arranged relative to the output element 8 such that the center axis 13 of the output element 8 is coaxial to the center axis 49 of the output shaft 44 of the electric 7.

(90) Thus, the output element 8 would be coupled directly to the output shaft 44 of the electric motor 7. In other words, the electric motor 7 and the output element 8 share a common shaft. In this case, the connective cog belt 45 illustrated in FIG. 11 and the gear 43 arranged at the output shaft 44 and the output-side gear 42 may consequently be omitted.

(91) As has been mentioned before, the arrangement, presently described, of the individual components within the drive device 1 comprises a certain gear ratio. In the case just described according to which the center axis 13 of the output element 8 is arranged to be coaxial to the center axis 49 of the motor output shaft 44, the electric motor 7 may comprise an internal transmission for realizing the desired gear ratio, i.e. for outputting a desired rotational speed or desired torque directly at the output shaft 40.

(92) In this case, the inventive drive device 1 would comprise two shafts, i.e. shaft 6 of the first drive 5 and the output shaft 44 shared by the electric motor 7 and the output element 8, the center axis 49 of which is arranged to be coaxial to the center axis 13 of the output element 8. In the case of such a two-shaft operation, it would also be feasible for the first drive 5 to be coupled to the common output shaft 44 at a gear ratio of 1:3 or advantageously 1:2.

(93) The electric motor 7 comprises an internal transmission with a gear ratio of 2:1 or, advantageously, 3:1. Via the output shaft 44, the electric motor 7 transfers the desired torque or the desired rotational speed to a chain ring, pinion, gear 55 (FIG. 6) or the like arranged at the output shaft 44. The gear 55 is coupled to the force transmission means used for driving, like a chain 90 or a cog belt or the like. The pinion 55 may be arranged outside the casing 47 of the drive device 1 (FIG. 6). The pinion 55 may also be arranged within the casing 47. Corresponding recesses in the casing 47 for performing the force transmission means 90 would be used here.

(94) Apart from the two-shaft operation just mentioned, a three-shaft operation is also possible using the inventive drive device 1. This is illustrated schematically in FIG. 12.

(95) FIG. 12 shows the drive shaft 6 of the first drive 5 where the pedal crank is arranged. This schematically illustrated drive device 1 additionally comprises a first additional shaft 1201 and a second additional shaft 1202. The shafts 6, 1201, 1202 may be connected among one another in the following three configurations as shown in tables 1 to 3 below.

(96) TABLE-US-00001 TABLE 1 CONFIGURATION 1 first drive 5 first additional second additional rear wheel (pedal crank) .fwdarw. shaft 1201 .fwdarw. shaft 1202 .fwdarw. axis 115 motor reduction transmission gearing (like hub, derailleur)

(97) TABLE-US-00002 TABLE 2 CONFIGURATION 2 first drive 5 first additional second additional rear wheel (pedal crank) .fwdarw. shaft 1201 .fwdarw. shaft 1202 .fwdarw. axis 115 transmission motor increase gearing

(98) TABLE-US-00003 TABLE 3 CONFIGURATION 3 first drive 5 first additional second additional rear wheel (pedal crank) .fwdarw. shaft 1201 .fwdarw. shaft 1202 .fwdarw. axis 115 motor transmission increase gearing

(99) In order to ensure a reliable functioning of the drive device 1, at least two freewheels are to be provided. Freewheels may generally be provided at every shaft, i.e. both at the first drive shaft 6, the output shaft 9, the motor output shaft 44 and the rear axis shaft 115. An advantageous implementation provides for one freewheel to be provided at the rear axis shaft 115 and one freewheel at the pedal crank shaft (first drive shaft) 6.

(100) While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which will be apparent to others skilled in the art and which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.