Electric propulsion system for a vehicle, particularly a battery-powered e-bike, S-Pedelac, e-bike with control in different modes

Abstract

The invention relates to a drive system for a vehicle, having a drive or electromotor, a crankshaft and a transmission, in particular a hub transmission. It is provided according to the invention that the transmission (10) is arranged in the central region of the vehicle, in particular the region of the crankshaft (1) and in particular is integrated and the crankshaft rotational speed is transmitted.

Claims

1. A drive system for a vehicle, the drive system including: a drive motor, a first, continuously variable, transmission, wherein the first transmission and the drive motor are configured to be arranged in a central region of the vehicle, and wherein the first transmission includes an output shaft, a central shaft, a second transmission configured to couple the drive motor to the central shaft, wherein the central shaft is connected to an input of the first transmission, either directly or via a third transmission, or forms an input shaft of the first transmission, and a fourth transmission configured to connect the output shaft of the first transmission to a rear wheel shaft of the vehicle, wherein a rotational speed of the output shaft of the first transmission is transferred to a driven wheel, with a ratio, n.sub.o/n.sub.w, between a rotational speed, n.sub.o, of the output shaft of the first transmission and of a rotational speed, n.sub.w, of the driven wheel of n.sub.o/n.sub.w>1, via the fourth transmission, with a belt or chain.

2. The drive system according to claim 1, wherein the second transmission is a single or multi-stage transmission, comprising a fixed gear wheel transmission or a toothed belt transmission.

3. The drive system according to claim 1, wherein a crankshaft is configured to be coupled to the central shaft via a fifth transmission.

4. The drive system according to claim 3, (a) wherein a drive motor output shaft, the central shaft and the crankshaft are formed by separate axles, which are mounted separately; or (b) wherein the drive system is constructed to be modular; or wherein both (a) the drive motor output shaft, the central shaft and the crankshaft are formed by separate axles that are mounted separately, and (b) the drive system is constructed to be modular.

5. The drive system according to claim 3, wherein the second transmission is configured to transfer force or torque of the drive motor to the central shaft, and the fifth transmission is configured to transfer force or torque of the crankshaft to the central shaft.

6. The drive system according to claim 3, further including: (a) a freewheel arranged between the crankshaft and the central shaft, in such a way that no torque is transferred from the central shaft to the crankshaft; or (b) a freewheel/clutch element arranged between the output shaft of the drive motor and the central shaft; or both (a) and (b).

7. The drive system according to claim 3, wherein a rotational speed of the crankshaft acts via the fifth transmission with a ratio of <0.4 to the central shaft or via an intermediate shaft to the input shaft of the first transmission.

8. The drive system according to claim 3, wherein the fifth transmission comprises a toothed belt or gear wheel transmission.

9. The drive system according to claim 1, wherein the second transmission is configured to transmit rotational speed, n.sub.mot, of the drive motor with a ratio n.sub.mot/n.sub.cs>3 to the central shaft, wherein n.sub.cs represents rotational speed of the central shaft.

10. The drive system according to claim 1, wherein the third transmission is configured to transmit rotational speed of the central shaft to the input shaft of the first transmission with a ratio of >1.

11. The drive system according to claim 1, wherein the drive system forms a separate unit having a drive module housing which is able to be integrated into a vehicle, wherein the drive motor, as well as the first transmission, the second transmission and the third transmission, are arranged in the drive module housing.

12. The drive system according to claim 11, wherein the drive module housing has two side plates that are connected by means of connection elements, wherein the connection elements are tube inserts that connect the side plates to one another.

13. The drive system according to claim 1, wherein elements of the drive system are configured to be arranged in or on a frame of the vehicle in a triangle arrangement, wherein the drive motor is arranged in front in a drive direction and the first transmission behind in the drive direction, and wherein the crankshaft is arranged underneath the first transmission and the drive motor.

14. The drive system according to claim 1, wherein the drive motor is configured to be plugged via a key shaft or shaft with spline, wherein: (a) a drive gear wheel of the drive motor is mounted in or on a frame of the vehicle, (b) the drive motor includes a housing comprising two plates and connection elements that connect the plates to one another in sandwich construction, or both (a) and (b), and wherein the drive motor is connected to a main tube of the vehicle.

15. The drive system according to claim 1, wherein the first transmission is a manual transmission having several speeds, wherein the first transmission is able to be switched manually, automatically or by a control computer, wherein the crankshaft is fixed and not rotatable, or both, and wherein pedals are arranged on the crankshaft.

16. A vehicle, including: a rear wheel; and the drive system according to claim 1, and configured to be coupled to the rear wheel via the rear wheel shaft.

17. The vehicle according to claim 16, wherein the vehicle is a Pedelec or e-bike.

18. The drive system according to claim 1, wherein the central shaft is configured to transmit power from the drive motor and from pedals to the first transmission.

Description

DESCRIPTION OF THE FIGURES

(1) Exemplary embodiments of the invention and their embodiments are described in more detail in the following description of the figures with reference to the drawing.

(2) Here are shown:

(3) FIG. 1: the basic structure of the drive system having a sensor system for Pedelec operation;

(4) FIG. 1a: the basic structure of the drive system having a sensor system for e-bike operation;

(5) FIG. 2: an alternative structure of the drive system having an intermediate shaft;

(6) FIG. 2a: the alternative structure of the drive system having an intermediate shaft for e-bike operation;

(7) FIG. 3: depicts the constructive implementation of the drive system integrated into the vehicle frame in a 3D depiction;

(8) FIG. 4: depicts the cooling of the drive in a longitudinal cut through the drive system;

(9) FIG. 5a: the basic support mode BSMode1; and

(10) FIG. 5b: describes the further basic support modes BSMode2 and BSMode3.

(11) FIG. 1 shows a first embodiment of the drive system. A crankshaft 1 having pedals 2 is stepped up to a shaft 6 via a chain or belt 4 and two pinions 3a and 3b, forming a further transmission 3 (i.e. i.sub.CS.fwdarw.CeS=n.sub.3a/n.sub.3b<1, where i.sub.CS.fwdarw.CeS is a ratio of rotational speeds between the crankshaft 1 and the shaft 6, defined here by the ratio n.sub.3a/n.sub.3b). One or two sensors (preferably composed in an assembly) detect rotational speed 7a and torque 7a of the crankshaft. Rotational speed and torque are preferably determined without contact by evaluation of the magnetic field of a magnetised crankshaft. The crankshaft is magnetised in the region of the sensors. A freewheel 5 on the crankshaft is integrated between the crankshaft 1 and the central shaft 6. An electromotor 8 having engine control electronics (motor ECU) 8a, rotational speed sensor 8b having a drive shaft 8c is reduced via a gear stage having two gear wheels 9a and 9b, forming another transmission 9 (i.e. i.sub.MS.fwdarw.CeS=n.sub.9a/n.sub.9b<1, where i.sub.MS.fwdarw.CeS is a ratio of rotational speeds between the motor shaft and the central shaft 6, defined here as n.sub.9a/n.sub.9b, wherein n.sub.9a and n.sub.9b are the rotational speeds of the shafts). The ratio i between the input shaft and its output shaft of first transmission 10 is greater than 1 in the sense of the invention if the input shaft rotates more quickly than the output shaft of the first transmission 10. The motor gear wheel 9a is expediently made from metal, the second gear wheel on the central shaft from light metal (aluminium, magnesium or high-strength plastic (also plastic/carbon)). The gear wheels are made from light metal, preferably helically cut, in particular for one embodiment of the gear wheel 9b for reasons of noise emissions. The ratio i.sub.CS.fwdarw.CeS of the rotational speeds between the crankshaft and the central shaft 6 is smaller than 0.4 (typical value: 0.2-0.3), the ratio i.sub.MS.fwdarw.CeS of the rotational speeds between the motor shaft and the central shaft 6 is greater than 3 (typical value: 4-5). A further freewheel 16 is integrated between the motor shaft 8c and the motor gear wheel 9a or alternatively a switchable clutch. The freewheel can also be omitted. The central shaft 6 acts on first transmission 10 which is implemented preferably to be continuously variable. A further sensor system 7d (optional) measures the rotational speed of the central shaft. The drive shaft 6a of the first transmission 10 is connected to a pinion 10a that is connected to the wheel shaft 13 via a wheel pinion 10b via a belt 11, forming yet a further transmission 36. The ratio is reduced, i.e. i.sub.DR=n.sub.10a/n.sub.10b>1 (typically a ratio of i n.sub.10b/n.sub.10a of approx. 2 is usual for vehicles up to 45 km/h and 27 inch wheels). The rotational speed of the wheel pinion 10b is detected via a further rotational speed sensor 7e. The sensor is preferably implemented to be contactless and scans the flanks of the pinion. A further freewheel element 14 is integrated into the rear wheel shaft 13. This freewheel element enables a roll out with a high degree of efficiency as the drive system can be still. The drive unit composed as a mechanical unit is depicted with a dashed line 17.

(12) If all drive elements are implemented as belts and the gear wheels between the motor and the shaft are implemented in a combination of plastic/metal, the drive system is completely maintenance-free.

(13) The drive system additionally has a central control 12 having a gyro sensor 7f. The road gradient is evaluated via the gyro sensor and the different operating modes BSMode2 and BSMode3, which are described in FIG. 5b, are used for the control.

(14) The construction of the drive system therefore enables a plurality of vehicle operating types in a vehicle (operation as a Pedelec and operation as a pure e-bike, or as a piece of sports equipment) and therefore universal application possibilities. In a Pedelec operating mode, the vehicle may legally be driven on cycle paths, in the e-bike operating mode on the road according to the German L1E authorisation regulation.

(15) If the freewheel 16 is replaced by a clutch, the motor can be switched on and therefore a recovery of the braking energy can be enabled. The same is able to be implemented by leaving out the motor freewheel having the disadvantage that the motor must be rotated with a corresponding drag torque. This can be compensated for by corresponding current regulation of the motor (drag torque compensation), such that it is not detectable by the driver. This requires, however, a higher standby current and causes loss of efficiency.

(16) By corresponding evaluation of the wheel rotational speed sensor 7e and the motor rotational speed 7c, the gear ratio can be determined and displayed to the driver.

(17) During use of the sensor 7d, it can be omitted and a more accurate determination is possible, even if the vehicle rolls at a standstill of the motor/the crankshaft. If the degree of efficiency of the motor and the first transmission 10 are known, a recommendation of how the degree of efficiency and the range can be increased can be provided to the driver by a corresponding evaluation of the signals.

(18) FIG. 1a shows the modification of the drive system for a pure e-bike. Therein the pedals 2 are replaced by foot rests and the crankshaft 1a is clamped to be fixed, not rotatable. The sensors on the crankshaft and the ratio to the central shaft are omitted. The drive system otherwise remains unchanged in its structure (as described in FIG. 1).

(19) FIG. 2 shows an alternative embodiment of the drive module having an intermediate shaft 20, via which the motor rotational speed and the crankshaft rotational speed are combined and are guided via a further ratio to the input shaft 6 of the first transmission 10 with a belt or chain 19 having 2 pinions 18a and 18b, forming a further transmission 18. The additional intermediate shaft is required if standard components (e.g. NuVinci transmissions) are used which only allow an input or higher overall gear ratios are implemented for higher vehicle final speeds or higher wheel rotational speeds for smaller wheel diameters. Furthermore, it can be required that due to 5 of the geometric arrangement of the drive elements, an intermediate shaft allows a better, narrower arrangement of the overall drive system. This is useful in particular in the sense of a very slim construction of the drive system which is desired in particular for Pedelecs.

(20) FIG. 2a shows the modification of the drive system of FIG. 2 for a pure e-bike. Therein the pedals 2 are replaced by foot rests and the crankshaft 1a is clamped to be fixed, not rotatable. The sensors on the crankshaft and the ratio to the central shaft are omitted. The drive system otherwise remains unchanged in its structure (as described in FIG. 2).

(21) FIG. 3 shows the constructive embodiment of the drive module, the spatial arrangement of the vehicle elements and the integration into the vehicle frame. The main frame of the vehicle consists of a drive module housing 22, a main tube 23 having a seat attachment 24. The drive module housing is composed of two plates 22a and 22b as well as diverse connection elements of the plates for 4 axles (drive axle A1, intermediate shaft axle A2, crankshaft axle A3, transmission axle A4). The plates are connected to one another via different parts/assemblies which receive the construction elements of the axles. The connection parts comprise a tube for the transmission 25a, a receiving assembly 25b for the electromotor and tube inserts for the crankshaft 25c and the intermediate shaft 25d and the rear wheel swing fixing 25e. The drive module housing is formed via the connection elements and the plates by positive connection of the connection elements to the plates. The drive module housing also contains a recess 25f in which the plug for a removable battery can be fitted. The drive module housing is connected to the main tube positively, for example via welding, riveting, screwing, gluing.

(22) The first axle A1 comprises the electromotor 26 which has a drive shaft 26a having a key 26b and a flange 26c. The electromotor is plugged into a receiver 25b and screwed onto the plate 22b.

(23) The receiver 25b contains a gear wheel 26e having a separate bearing 26d. The shaft of the drive motor is therefore free of radial forces.

(24) In the second axle A3 are the crankshaft 27a, pedal crank 27c, crankshaft sensor 27b which are received by the connection element 25c. A crankshaft pinion 27d which is arranged between the housing plates in the assembled state is on the crankshaft axle. The axle A3 is mounted in the side plates.

(25) The intermediate shaft 28a is arranged in a third axle A2. On the intermediate shaft are arranged the pinion for the crankshaft ratio 28d, gear wheel of the motor ratio 28b and drive pinion 28c for the transmission as well as mounting elements. Alternatively to the drive pinion, a belt gear wheel can be used. The axle A4 is mounted in the side plates.

(26) The transmission 29 is arranged in the fourth axle A4. The axle comprises a transmission having a gear input pinion 29a and a gear output pinion 29b as well as a gear spider 29c which receives the transmission and connects to the frame and centres the axle A4. A second gear spider 29d is arranged on the rear side. Alternatively to the gear input pinion, a belt gear wheel can be used. The transmission and the intermediate shaft and gear input are connected to a chain or belt.

(27) FIG. 4 shows the cooling of the drive system. A cross-section of the drive module between the plates is depicted. A baffle 30 is inserted between the plates that passes the vehicle air flow over the input 31a at the main tube on the housing 25b of the electromotor. The air exits below in the region 31b. The motor 26 which is implemented as an external rotor motor, rotates in the housing 25b and transfers the heat to the housing which is cooled efficiently via the air flow. Drive elements in the drying room 32 are additionally protected by this from the effect of dirt. Dirt which collects in the channel can simply be washed out via a steam jet.

(28) FIG. 5a describes the basic support mode BSMode1. In the basic support mode, the drive loss of the drive is determined offline for the vehicle in a loss characteristic diagram 33 depending on the gear ratio i.sub.CVT and the motor rotational speed n.sub.mot. During the driving operation, the power loss P.sub.I,drive is determined from the real rotational speed of the motor n.sub.mot. The motor torque M.sub.mot which is required for the compensation of the losses can be calculated according to the overall gear ratio i.sub.ov and the motor rotational speed n.sub.mot. Using this basic control, the vehicle is very easy to operate and compensates as far as possible for the higher weight of the vehicle having a drive system and battery. The operating mode is also possible in a reserve operation if the battery is operated close to the operating voltage lower limit and the mechanical operation is only still possible with lower power. The loading during driving without a battery is therefore reduced.

(29) In addition to the loss compensation, it is useful to calculate and to compensate for the rolling resistance losses P.sub.rolling friction. The rolling resistance loss can be determined with 34 from the vehicle-specific values of the rolling friction coefficient cr and vehicle weight m.sub.VEH. This operating mode increases the ease of operation with increasing speed. The resistance increase due to increasing vehicle speed (air resistance increases quadratically with respect to speed) is therefore reduced and enables the driver an increased vehicle final speed with muscle power.

(30) A variety of the BSMode1 is the rest and drag loss compensation of the electromotor in addition to the compensation of the drive losses. This is used with omission of the freewheel 16 between the motor shaft and the central shaft and also enables an ease of operation of the vehicle and an active recovery of braking energy for a fixedly coupled motor.

(31) FIG. 5b describes a further basic support mode BSMode2 in which the overall losses of the vehicle are determined via a vehicle model 35. Input values for the vehicle model are gradient a.sub.gyro sensor (determined with gyro sensor 7f), v.sub.VEH, m.sub.VEH, cr and air resistance coefficient cwA and the drive losses P.sub.I,drive (see description FIG. 5a).

(32) The overall losses are added up and can be converted into a support torque of the motor M.sub.mot corresponding to the overall support i.sub.ov and the motor rotational speed.

(33) Additionally it is also possible to set a target support P.sub.target,human in a further operating mode BSMode3 in order to reduce the support torque of the motor M.sub.mot. This operating mode allows a sport operation having constant power adjustment. A support is therefore ensured independently of the road and the vehicle speed and the setting of a constant pulse rate of the driver is more or less ensured. This is known to promote good health and reduced peak loading (e.g. for extreme mountain driving). BSMode3 enables the operation of the vehicle as a mobile fitness device.

LIST OF REFERENCE NUMERALS

(34) 1, 1a Crankshaft 2 Pedal 3a Crankshaft pinion 3b Gear shaft pinion 3 Transmission 4 Belt 5 Freewheel 6 Central shaft 6a Gear output shaft 7a Rotational speed sensor for crankshaft 7b Torque sensor for crankshaft 7c Rotational speed sensor electromotor 7d Rotational speed sensor central shaft 7e Rotational speed sensor rear wheel pinion 7f Gyro sensor 8 Drive or electromotor 8a Control electronics electromotor 8b Rotational speed sensor electromotor 8c Output shaft electromotor 9a Motor shaft gear wheel 9b Central shaft gear wheel 9 Transmission 10 Transmission 10a Pinion of the gear output shaft 10b Wheel pinion 11 Belt/chain to the rear wheel 11 Drive belt/drive chain 12 Central control 13 Rear wheel shaft 14 Wheel freewheel 15 Rear wheel 16 Freewheel electromotor 17 Drive system unit 18a Pinion intermediate shaft 18b Pinion gear input shaft 18 Transmission 19 Belt/chain between intermediate shaft and gear shaft 20 Intermediate shaft 21 Foot rests 22 Drive module housing 22a Drive module plate 22b Drive module plate 23 Main tube 24 Seat attachment 25a Tube for transmission 25b Receiving assembly for electromotor 25c Tube insert for crankshaft 25d Tube insert for intermediate shaft 25e Insert for fastening the rear wheel swing arm 25f Recess for battery plug 26 Electromotor 26a Shaft of the electromotor 26b Key 26c Motor flange 26d Motor receiver with bearing 26e Motor drive gear wheel 27a Crankshaft 27b Crankshaft sensor 27c Pedal crank 27d Crankshaft pinion 28a Intermediate shaft 28b Gear wheel for motor ratio 28c Drive pinion, drive belt wheel 29 Transmission 29a Gear input pinion 29b Gear output pinion 29c Gear spider 29d Second gear spider 30 Baffle 31a Input of the air flow 31b Output of the air flow 32 Drying room between the side plates for arrangement of sensors and drive elements 33 Loss characteristic diagram 34 Calculation of rolling resistance lost power 35 Vehicle model 36 Transmission i.sub.DR Gear ratio drive/gear output shaft to rear wheel i.sub.MS.fwdarw.CeS Gear ratio motor shaft to central shaft i.sub.CS.fwdarw.CeS Gear ratio crankshaft to central shaft i.sub.CVT Gear ratio of a continuously variable transmission i.sub.ov Overall gear ratio cr Rolling resistance coefficient cwA Air resistance coefficient m.sub.VEH Vehicle weight v.sub.VEH Vehicle speed n.sub.mot Motor rotational speed P.sub.I,drive Drive loss of drive P.sub.rolling friction Rolling resistance lost power M.sub.mot Motor torque dP Power difference a.sub.gyro sensor Gradient determined from gyro sensor P.sub.target,human Desired constant power human A1 Motor drive axle A2 Intermediate shaft axle A3 Crankshaft axle A4 Transmission axle