Patent Application
20210107595
In accordance with the generic term of the main claim, the invention relates to a multi-speed transmission, in particular for a two-wheeler, which is mounted on a central axle, has a hollow shaft on the input side and a hub sleeve on the output side, between which two at least two-stage planetary gears are inserted, which are each connected to one another by sun gears and associated webs, and each of which can be shifted with a ring gear either into a block revolution or one of several transmission or reduction modes.
A similar multi-speed transmission is known from EP 0915 800 B1. This comprises an axle which can be mounted non-rotatably on a bicycle frame, a driver rotatably mounted on the axle, a sleeve rotatably mounted on the axle, a gear shift mechanism provided with a first and a second planetary gearbox arranged in the sleeve and coupled to the driver and the sleeve to provide multiple gear ratios between the driver and the sleeve, the planetary gearboxes comprising at least two sun gears coaxial with the axle, have at least one planet carrier with correspondingly stepped planet gears engaging with the two sun gears and at least one ring gear engaging with the planet gears as well as a shifting device for selecting the transmission ratios by selectively connecting the sun gears to the axle, for which purpose the shifting device has means for selectively connecting the ring gear or the planet carrier of the first and/or second planetary gearbox to a sun gear of the same planetary gearbox. This preferably results in a 7×2=14-speed gearbox, in which a seven-speed gearbox, consisting of a direct gear and two two-stage manual gearboxes, is coupled in series with another gearbox, which has a direct gear and a shiftable planetary arrangement. The gears are shifted with 4 pawls, 3 axial clutches and 6 planetary sets, which are arranged to form three two-stage planetary arrangements. The disadvantage of this arrangement is the low input torque, which results in a preferred chain or belt gear ratio of preferably 2.5. The sun gears are axially fixed with pawls, which requires an internal gearing of the same, which is loaded asymmetrically by the pawls—for space reasons only one per sun gear—and only on one internal tooth. A further disadvantage is that no thru axle can be used.
A further multi-speed transmission is known from EP 2 028 096 A1, in which only 5 planetary sets, formed by a double and a triple stepped planet, but 12 clutches are provided.
The disadvantage of this arrangement is that six of the clutches are pawls which serve to fix the axes of the 4 sun gears. Other clutches, which act axially, have approximately ring gear diameters. In addition, the ring gears must be supported on their large diameters. The shifting mechanism of the transmission is very complex and costly to manufacture. In addition, the stepped planets cannot be supported by roller bearings, since some planets have a small number of teeth (14 or 15 teeth). A 12 mm thru axle is also not realizable. The input gear, consisting of two sun gears, two hollow gears and three triple stepped planets, provides three fast gear ratios in addition to the direct gear. The first gear of this transmission is the direct gear, which is formed by the coupling of planet carrier and ring gear. In the second and third gear, the transmission forms two sub-transmissions, but these are different for each of the two gears. The fourth gear is a simple planetary gearbox driven by the planet carrier with a double-step planet. The overall design results in a high number of different complex parts and a total mass that is significantly higher than the mass of the gearbox known from EP 0 915 800 B1. Furthermore, multi-speed hub gears with three or four planetary sets are known from U.S. Pat. No. 9,279,480 B2, which can be coupled in various ways by nine clutches.
The clutches are actuated by a camshaft which actuates radial shifting means.
The disadvantages here are the low input torque that can be tolerated and the large number of different, complex production parts.
In the state of the art, transmissions of this type are shifted with pawls, which are supported in apertures in a transmission axle, controlled by cams on a shift shaft, and folded out or in (cf. EP 2028 096 A1; DE 10 2010 051.727 A1). If a gear wheel is to be fixed to the axle, the pawl folds out and engages in an internal toothing of the gear wheel to be fixed. On the one hand, the internal gearing has a notch effect, and on the other hand, the gear wheel is subjected to punctual internal loading. The wall of the hollow axle must be relatively thick-walled due to the high forces and thus have a relatively large diameter. It is known that pawls are difficult to collapse under load. A further switching type is shown in the U.S. Pat. No. 9,279,480 B2, where radial cams actuate the switching means.
Common to all these well-known hubs is that the drive pinion mounted on a hollow shaft has about half—or considerably less—the number of teeth than a pedal crank output blade usually has, because the input forces that can be tolerated are relatively low.
The toothed belts that are now widely used as a means of transmitting power to the rear wheel require a significantly larger number of teeth on the rear wheel because of their rigidity. The e-bikes that have been on the market for several years now enable higher average speeds, which in turn require a high transmission ratio bandwidth. Meanwhile, the 5 mm quick-release axle, which is used to clamp a hub in the rear triangle or fork, is increasingly being replaced by thru axles. In the rear wheel a diameter of 12 mm is common. The thru axle is mostly a long screw with a short 12 mm thread. The thru axle is inserted from one side through a suitable hole, passed through the hollow hub axle and then screwed into the thread of the opposite drop out. When tightening, the connection is preloaded.
The invention is based on the task of designing the multi-speed transmission in such a way that a wide range of transmission ratios can be achieved with low weight, high efficiency, simple manufacture, a transmission ratio suitable for toothed belts and under load, with simple control, particularly good shifting and can be mounted in the dropouts of the rear end by means of a thru axle.
The solution is indicated in the identification of the main claim. Advantageous designs are indicated in the sub and secondary claims.
The invention is explained in the following with reference to
A preferred design is a nine-gear transmission with constant gear steps of approx. 24% at a transmission ratio range of approx. 560%. The input transmission ratio is selected in such a way that with the secondary transmission ratio of the chain or belt drive with e.g. 40 teeth at the front and a rider with e.g. approx. 36 teeth at the transmission hub, a total transmission ratio i_ges for the first gear of approx. i_ges.=1.7 results. For the ninth gear this results in a transmission ratio of 0.30.
This is achieved by coupling two three-speed planetary gears.
A first transmission is happy to exist.
A first preferred design of a second gear consists of two identical planetary gearboxes, mirrored to each other, each consisting of a ring gear, a sun gear and double stepped planets, which are coupled by means of bridges that are connected to each other in a rotationally fixed manner (not shown). The first subgear of this add-on set is a reduction gear with approx. i_4=10.24{circumflex over ( )}3=1.91 and the second subgear is a transmission gear with i_6−I/i_4=0.5245. The direct gear with i_5=1 is achieved when both subgears rotate as a block.
A second preferred version of a second transmission according to
The following table shows that in the case of gears G1, G5, G6, G7, only one planetary gear set is involved in the power transmission and in the case of gears G2, G3, G8 and G9 only their two. This stands for a good efficiency of the gear hub. Gear G4 does not require any rolling motion of the gears.
According to the invention, the multi-speed transmission is shifted with axial clutches. A clutch is formed by two opposing discs, which can be operated by means of intermediate elements, with axially acting ratchet teeth acting in one direction, mounted on a circular ring perpendicular to the axis of rotation. In the following, a coupling that triggers the block rotation, “block lock”, which prevents the sun gear from rotating when driven by the web, “tracking lock” and which prevents the sun gear from rotating backwards when driven by the ring gear, “backstop”. In this case, the same direction of rotation as the driving belt or sprocket wheel is meant. If torque is to be transmitted with the same direction of rotation, the term “driver” is used.
In the following table the symbols used in the figures are listed with their meaning. In
b)
b)
b)
b)
The preferred rear wheel hub,
The second NSG gear unit,
The coupling components are numbered in the sequence in which they follow each other on axis 6a from the drive side in steps of ten, each starting with 20 to 90;
Clutch 20 switches the block rotation of the first gear unit G1 by connecting or disconnecting the sun gear 9c to the drive 4a and thus to the web 8.
Clutch 20 shifts the gears 1, 4, 7. The travel stop 21a engages the counterpart 21b, which is firmly connected to the sun, and prevents the sun gear from overrunning the web 8.
The other components are a return spring 22, which is supported in the actuator 4a, a slide 23a with a cylindrical pin 23b, which is controlled by the groove 24.
The clutch 30 shifts the second gear of the first transmission by shifting the sun wheel 9c is set fixed to the axis. The clutch 30 shifts the gears 2, 5, 7 of the overall transmission.
Clutch 40 shifts the third gear of the first transmission by setting the sun gear 9d to fixed position. Clutch 40 shifts gears 3, 6, 9 of the overall transmission.
The sun gear 9d is designed as a ring with internal gearing in which the clutch part 41a (
The clutches 50, 70, 80 shift the first gear of the second gear G2 by connecting clutch parts 51a (with cylindrical pin 51c) and 51b non-rotatably connecting the ring gear with the driver 4b, clutch parts 81b and 81a (with cylindrical pin 81c) non-rotatably connecting the web with the output sleeve 4d, and clutch parts 71a (
If this configuration is shifted, the gears 1, 2 and 3 are obtained together with the first gear.
The other components of the clutch 50 are a return spring 52 supported on the side wall 7b, a groove ring 53 with inner collar, a slider 55a with a cylindrical pin 55b controlled by the groove 54.
The clutch 70 is designed as a bidirectional clutch, since the direction of the torque is reversed when the input is switched from the ring gear to the bar. The other components of the clutch 70 are, a return spring 72, which is supported on the outer collar of the slider 63a, a slider 73a with a cylindrical pin 73b, which is controlled by the groove 74.
The other components of the clutch 80 are a return spring 82, which is supported on the outer collar of the slider 94a, and a slider 83a with a cylindrical pin 83b, which is guided in the groove 84.
The couplings 50 and 90,
The following options are available for block rotation, whereby the sun wheel can always rotate freely by opening clutch 70.
Variant 1: Clutches 50, 60, 90 closed, clutch 70 open.
Variant 2: Clutches 50, 80, 90 closed, clutch 70 open.
Variant 3: Clutches 50, 60, 80, 90 closed, clutch 70 open.
Variant 4: Couplings 60, 80, 90 closed, coupling 70 open.
Variant 5: Couplings 50, 60, 90 closed, coupling 70 open.
Variant 4: Couplings 50, 60, 80 closed, coupling 70 open.
Some of the possibilities are used as examples in the suggested switching sequence. In this configuration the second gear of the second transmission is realized. Gears 4, 5 and 6 can then be shifted.
Clutches 60, 70, and 90 shift the third gear of the second transmission by connecting clutch parts 61a and 61b to the web 202 with the driver 4b in a rotationally fixed manner, clutch parts 91b and 91a (with cylindrical pin 91c) to connect the ring gear 200 with the output sleeve 4d in a rotationally fixed manner, and clutch parts 71a and 71b to set the sun gear 204 in an axially fixed manner.
In this configuration, the third gear of the second gear is realized. Gears 7, 8 and 9 can then be shifted.
The solution of the task underlying the invention allows the use of needle bearings for the bearing of all planets. Due to the high load capacity of the manual transmission, ratios of up to i=1 can be used between bottom bracket chainring and hub drive pinion. The exclusive use of axial clutches allows particularly good opening even under load. In most shifting operations, the clutches change to freewheel mode before they are opened, so that they can be opened without load. The number of different production parts is noticeably smaller than with the state of the art. The same applies to the total mass of the manual transmission. Due to the transmission structure, only a few gears are in mesh at any one time, which ensures high efficiency in the individual gears.
b: Switching sequence table with associated legend
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2018 010 274.3 | Mar 2018 | DE | national |
| 10 2018 007 326.3 | Sep 2018 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2019/000079 | 3/24/2019 | WO | 00 |
