Planetary gearing

Abstract

Planetary gearing mounted on a central axle (6a), having a drive-side hollow shaft (4a) and an output-side hub sleeve (1) with a planetary-gear system NSG arranged coaxially therebetween, the latter comprising a sun gear and planetary gears, which are connected to one another via an associated planet carrier, and also a ring gear, which can be switched by respective clutches, with alternating switchover of the drive and output, either so as to revolve as a block or into a step-up or step-down mode, wherein the planetary-gear system NSG, with its sun gear (SR) permanently axially fixed, is switched by just four clutches (K50, K60, K80, K90), with the alternating switchover of the drive and output, respectively into a slow mode, a quick mode or a direct mode.

Description

[0001] planetary gearbox

[0002] The invention relates to a planetary gearbox which is mounted on a central axis and has a hollow shaft on the input side and a hub sleeve on the output side, between which a planetary gear is arranged coaxially, which consists of a sun gear and planetary gears connected to one another via a planet carrier, as well as a ring gear, and which can be switched by means of clutches with alternating switching of the input and output either into a block circuit or an increase or decrease mode.

[0003] The planetary gearbox is particularly designed for single- or multi-track, pedal-driven vehicles, being mounted on a central axle and having a hollow shaft on the input side and a hub sleeve on the output side, between which a multi-stage gearbox is arranged.

[0004] Such a transmission is known as a partial transmission of a nine-speed transmission from WO 2019 192 634 A1, as shown in Fig. 3. A first transmission, shown on the left in Figure 3, consists of a carrier with double-stage planets and a ring gear with a side wall and two sun gears that mesh with the corresponding planets. Its carrier is driven by a driver on which a pinion is rotatably mounted. The output of the first transmission is via the ring gear. If the transmission is operated in block circulation, the direct gear is obtained with i_1 = 1 . The gear ratio with i_2 = 1 / 1 .24 = 0.8065 is obtained when the smaller of the two sun gears is fixed to the axle. The gear ratio with i_3 = 1 / 1 .537 = 0.65 is obtained when the larger of the two sun gears is fixed. The transmission thus translates into high speed.The second gear is a planetary gear with a gear step of 91% consisting of a ring gear, a multiple planetary gear with different numbers of teeth and a sun gear which meshes with the smaller of the two planets. The sun gear is engaged and released using a bidirectional clutch. A bidirectional clutch is provided because the reaction torque is reversed when the input and output change. The slow gear ratio is achieved by driving the ring gear and the output via the carrier. The direct gear, for example, is achieved by closing the two ring gear clutches which are connected by their side walls in a rotationally and axially fixed manner. The sun gear is released by opening the sun gear clutch. The fast gear ratio is achieved by driving the carrier and the output via the ring gear.Three axial clutches are used to shift the first gearbox and five axial clutches are used to shift the second sub-gearbox.

[0005] A disadvantage of this design in the nine-speed transmission is that the control of this gear stage is not symmetrical, which requires a large number of different, sometimes complex, components. The bidirectional sun gear clutch requires a relatively large axial installation space. Due to space constraints, the clutch springs cannot be designed independently of neighboring clutches, meaning the springs must travel twice the shift stroke of a clutch, resulting in relatively large force changes. The closing forces are at their lowest precisely when the clutches are intended to be kept closed.

[0006] Furthermore, from WO 2019 086 064 A1, a drive train is known whose first transmission is a bottom bracket shift transmission and whose second transmission is the rear-mounted transmission, which provides three gears and is housed in the rear wheel hub. This second transmission, the rear-mounted transmission, consists, according to Table 1 therein, of two identical planetary gears arranged in a mirror image to one another, each consisting of a ring gear, a sun gear and double-stage planetary gears, which are coupled via non-rotatably connected webs. The first sub-transmission of this rear-mounted transmission is a reduction gear with approximately i_4 = 1.24 to the power of 3 = 1.91 and the second sub-transmission is a reduction gear with i_6 = 1 / i_4 = 0.5245. The direct gear with i_5 = 1 is achieved when both sub-transmissions rotate as a block.

[0007] The disadvantage of this drivetrain design is that two identical gears are used in the rear hub gear, which results in twice the number of gear components, correspondingly high costs, and a large mass, which is problematic in the bicycle sector.

[0008] The object of the present invention is to significantly simplify the aforementioned transmissions while maintaining approximately the same gear ratios, thereby reducing weight, costs, and overall width. A further object of the present invention is to disclose advantageous arrangements of the novel transmission with various primary gears.

[0009] The problem is solved according to the features of independent claim 1. Further advantageous embodiments of the solution can be found in the respective dependent claims.

[0010] The solution according to independent claim 1 consists in that the planetary gear, with permanent axis fixing of its single sun gear, is switched with only four of the clutches, which are arranged symmetrically to this sun gear, in each case in a slow, a fast or a direct mode when switching the input and output respectively.

[0011] This switched reversal of the planetary gear system eliminates the need for a second sun gear with its associated carrier, planetary gears with their axles and bearings, and a ring gear, its control, and thus also the support of its clutch spring on a further clutch spring of a planetary carrier clutch, compared to the prior art version. Comparing the design of the previously known nine-speed arrangement according to Figure 3 with that according to Figure 2, which includes the transmission according to Figure 1, the nine gears are again shifted with a total of only seven clutches, in that on the single axially fixed sun gear of the novel transmission, any clutch with its control means—namely, a clutch disc with control fingers, a clutch disc with external spline teeth, which would be axially movable and non-rotatably arranged in the sun gear, an associated control groove in a control cylinder, and a pressure spring—are omitted.The four clutches of the second gear unit, with their control means and the two associated input and output sleeves, are designed symmetrically to the planetary gear unit and are therefore inexpensive to manufacture as repeat parts. This symmetry also applies to the clutch compression springs. Advantageously, the two springs of the planet carrier clutches are supported on the axle-fixed sun gear, as the movable part of the web clutches K60 and K80 is now located in the web. A further advantage is that the springs are now designed independently of one another, meaning that only the clutch stroke of one clutch needs to be performed by the springs instead of two.

[0012] The invention is described with reference to Figs. 1 and 2, wherein the reference numerals of the components are used analogously to their function according to that in Fig. 3, which is taken from the prior art WO 2019 192 634 A1.

[0013] A hub gear shown in Figure 1 comprises a hub sleeve 1, which is mounted on a driver 4a and another on an axle 6a by means of a rolling bearing. A drive pinion 2 for a belt or chain drive is located on the driver 4a, connected to it in a rotationally fixed but detachable manner. Another rolling bearing supports the driver 4a on the axle 6a. The driver 4a is alternately connected to a ring gear HR or a planet carrier 8 by couplings K50 and K60. Output-side couplings K80, K90 alternately connect a carrier 8 or the ring gear HR to a driver sleeve 4d and thus to the hub sleeve 1.

[0014] Fig. 2 shows the arrangement of the novel planetary gear unit NSG with an input or pre-gear unit EG in the same hub. It comprises a hub sleeve 1, which is mounted on the driver 4a by means of a rolling bearing and another rolling bearing on the axle 6a. A drive pinion 2 for a belt or chain drive is located on the driver 4a, non-rotatably but detachably connected to it.

[0015] The driver 4a is connected to the carrier of a three-stage input gearbox EG, which is controlled by three clutches K20, K30, and K40. The output-side ring gear HR is connected to a driver sleeve 4b, which controls a three-stage secondary gearbox NSG via two clutches K50 and K60. Within the axis 6a is a shift drum 6b, on which there are grooves 24, 34, 44, 54, 64, 84, and 94, into which the shift fingers engage. These are each directly or indirectly connected to one of the clutches K20, K30, K40, K50, K60, K80, and K90, and they engage the grooves 24, 34, 44, 54, 64, 84, and 94 through axially leading slots in the axis 6a.The grooves 24, 34, 44, 54, 64, 84, 94 are designed in such a way that the intended movements of the shift fingers for switching the clutches K20, K30, K40, K50, K60, K80, K90 for setting the individual gears are carried out when the shift drum 6b is rotated into one of the nine gear positions, in that selected shift fingers open the associated clutches K20, K30, K40, K50, K60, K80, K90 against a closing force, in particular a spring.

[0016] Two complete control structures are provided in each of the grooves 24, 34, 44, 54, 64, 84, 94, each at 180° of the circumference of the shift drum, so that two opposing shift fingers control the clutch discs in parallel, thus preventing shifting interference caused by tilting of the clutch. The newly designed NSG secondary transmission comprises a driver sleeve 4b with internal and external toothing and, for each clutch K50, K60, K80, K90, two or three elongated holes 4c offset by 180° or 120°. A driver sleeve 4d has a similar structure with toothing and elongated holes.

[0017] The following tables show application examples for the innovative rear-mounted transmission. Tables 2, 3, and 4 illustrate that bottom bracket transmissions or pre-mounted transmissions with different gear numbers and gear steps can be combined with the same rear-mounted transmission. The bottom bracket transmission offers the option of feeding or coupling a motor drive.

[0018] The following Table 1 shows the number of teeth of the gear wheels HR, PR, SR, the corresponding gear ratios i and the gear steps s as well as the clutches K20, ... K90 engaged in the gears Gn, n = 1 ...9, for a nine-speed gearbox.

[0019] Table 2 shows a configuration for WO 2019 086 064 A1, also for a nine-speed drivetrain, with the input gear shifted towards the bottom bracket.

[0020] Table 3 shows another configuration for WO 2019 086 064 A1 for a twelve-speed drivetrain, where the four-speed bottom bracket gearbox only provides high-speed transmission.

[0021] Table 4 shows another configuration for WO 2019 086 064 A1 for a fifteen-speed drive train, where the five-speed bottom bracket gearbox only slows down in one gear with only about 13.7% and thus only insignificantly increases the tensile forces on the traction device compared to the direct gear.

[0022]

[0023] The following symbols are used for illustration purposes in the figures. Symbol list:

[0024] The nine-speed hub transmission is preferably operated exclusively with axial clutches. A clutch is formed by two opposing discs, actuated by the intermediate links described, with unidirectional, axially acting locking teeth mounted on a circular ring perpendicular to the axis of rotation. In the following, a clutch that initiates block rotation is referred to as a "block lock." A clutch that prevents the sun gear from rotating when driven by the planet carrier is referred to as a "follow-up lock." A clutch that prevents the sun gear from reversing when driven by the ring gear is referred to as a "backstop." "Backstop" then means the same direction of rotation as the driving belt or sprocket. If torque is to be transmitted in the same direction of rotation, the term "driver" is used. Accordingly, clutches K50, K60, K80, and K90 are drivers, clutches K30 and K40 are backstops, and clutch K20 is a block lock.The clutch parts are numbered in the order in which they follow one another on the axis 6a from the drive side, in increments of ten, each starting with 20. The input gear EG corresponds to that shown in Fig. 3, which is state of the art.

[0025] The clutch K20 switches the block circuit of the input gearbox EG by connecting or releasing the sun gear with the driver 4a and thus the planet carrier in a rotationally fixed manner.

[0026] The K20 clutch shifts gears 1, 4, and 7. The block lock engages with the counterpart firmly connected to the sun gear and prevents the sun gear from overrunning the planet carrier. The other components are a closing spring, which is supported by the driver, and a sliding ring with a shift finger controlled by the corresponding groove 24.

[0027] Clutch K30 is a follow-on lock and engages the second gear of the input gearbox EG by locking the smaller sun gear to the axle. Clutch K30 engages gears 2, 5, and 8 of the entire transmission.

[0028] The K40 clutch is a follower lock and engages the third gear of the input gearbox EG by setting the larger sun gear fixed to the axle. It engages gears 3, 6, and 9 of the entire gearbox. The sun gear is designed as a ring with internal teeth, in which the follower lock clutch part is guided in a rotationally fixed but axially movable manner. The counterpart has internal teeth that connect it to axle 6a in a rotationally fixed manner. Retaining rings prevent axial movement. A sliding ring with a shift finger is controlled by groove 44. The closing spring is supported by a retaining ring embedded in axle 6a.

[0029] The innovative NSG rear-mounted transmission features three shift combinations: Clutches K50 and K80 are engaged; the rear ring gear (HR) is driven, the rear sun gear (SR) is locked, and the planet carrier 8 is connected to the output side of the output sleeve 4d via clutch K80. This results in a gear ratio of 1.912 at low speed.

[0030] Clutches K50 and K90 are closed, with the drive continuously connected to the output sleeve 4d. The transmission runs in neutral.

[0031] Clutches K60 and K90 are engaged. The drive is connected to the planet carrier 8 and is transmitted from the planet gear PR through the ring gear HR with the output sleeve 4d to the hub sleeve 1. The gear ratio is 0.523.

[0032] In fourth gear, there is no lossy rolling friction between the gears under load, and in gears 1, 5, and 7, only one gear set meshes at a time. The transmission thus operates with high efficiency. Furthermore, it is narrower and lighter than the previously described transmission shown in Fig. 2, and it is more material-efficient and cost-effective to manufacture thanks to the elimination of a clutch assembly on the sun gear SR.

[0033] Further embodiments are shown in Fig. 4 and Fig. 5. Identical components have the same reference numerals. The NSG rear-mounted transmission shown in Fig. 4 and 5 has the following changes and differences compared to the embodiment according to Fig. 1. In the embodiments in Fig. 4 and 5, two sliding rings, two shift fingers and two grooves in the shift drum are omitted. Two grooves can be omitted because the clutches of clutch pairs K50 / K60 and K80 / K90 move synchronously. For example, when clutch K50 opens, clutch K60 closes and vice versa. This results in parallel control groove pairs. Consequently, the movement of clutch pairs K50 / K60 and K80 / K90 can each take place via a sliding ring through a control groove.Thus, the four clutches of the rear-mounted gearbox are controlled by means of just two sliding rings, each of which is guided by two shift fingers that engage in the respective assigned control groove.

[0034] This advantageously provides expanded axial installation space. This design allows the springs of the K60 and K80 clutches to be positioned inward, close to the axis, directly against the sliding rings. Frictional forces that occur against the collar of the gate 53, 93 can be eliminated or removed by the design of the sliding rings 64a, 84a with the aid of the support rings 56, 96.

[0035] The sliding ring-side support rings 56, 96, which are supported on the sliding rings 64a, 84a, together with the sliding rings offset on the outer diameter, form a groove which enables the free rotation of the link 53, 93, which engages in this groove with the inner collar.

[0036] A link is understood here as an annular component which has an annular contact surface on the inside and a circumferential groove or bores on the outside into which the shift fingers of the movable part of the outer clutches such as K50 or K90 engage.

[0037] For example, when using four clutches, only two sliding rings may be required as actuators.

[0038] In one embodiment, a nine-speed hub can be provided with seven clutches, whereby only five sliding rings are required as actuators.

[0039] In the previously known patent application WO 2019 192 634 A1 described above, as well as in the documents cited therein regarding other known hub gears with different clutches, none was shown with only seven clutches. This reduction also led to simplifications and further savings through the use of similarly controlled clutches. The now-removed, bidirectional sun gear clutch was evidently considered essential, as its function was addressed for six shift combinations. However, the possibility of dispensing with it entirely was completely disregarded.

[0040] List of reference symbols

[0041] Hub shell

[0042] 2 pinions

[0043] 4a Driver

[0044] 4b Driver sleeve

[0045] 4c Long holes in 4b

[0046] 4d Abortion sleeve

[0047] 4e long holes in 4d

[0048] 6a axis

[0049] 6b Shift drum

[0050] 8 planet carriers in NSG

[0051] K20, K30, ... K90 couplings

[0052] 24, 34, ... 94 grooves in 6b

[0053] EC input gearbox

[0054] NSG rear-mounted gearbox

[0055] HR ring gear

[0056] PR planetary gears

[0057] SR sun gears i gear ratio s gear step

[0058] S switching range

[0059] W rolling bearing unit

[0060] 51c, 91c, 64b, 84b shift finger

[0061] 52, 92 spring

[0062] 53, 93 backdrop

[0063] 64a, 84a sliding ring

[0064] 56, 96 support discs

Claims

Patent claims Planetary gearbox mounted on a central axis (6a) with a hollow shaft (4a) on the input side and a hub sleeve (1) on the output side with a planetary gear (NSG) arranged coaxially therebetween, which comprises a sun gear (SR) and planet gears connected to one another via an associated planet carrier (8) as well as a ring gear (HR), which can be switched in each case by means of clutches with alternating switching of the input and output either into a block circuit or a transmission mode or a reduction mode, characterized in that the planetary gear (NSG) with permanent axis fixing of its sun gear (SR) is switched with only four clutches (K50, K60, K80, K90 in each case either into a slow, a fast or a direct mode with the alternating switching of the input and output.Planetary transmission according to claim 1, characterized in that the clutches (K50, K90; K60, K80), which connect the ring gear (HR) and the planet carrier (8) with planet gears (PR) respectively to the input or to the output, or which directly connect the input and the output, are arranged symmetrically to the axially fixed sun gear (SR). Planetary transmission according to claim 1 or 2, characterized in that coupling-loaded, radially extending clutch rings of a respective gear stage are released by sliding rings guided in spiral circular grooves (54, ...94) in a coaxial shift drum (6b) and in radial slots oriented parallel to the rotational axis of the transmission in a hollow shaft (6a) enclosing them, each actuating the associated clutch rings in a switching manner.

4. Planetary gearbox according to claim 2 and 3, characterized in that the ring gear clutches (K50, K90) and the planet carrier clutches (K60, K80) are each symmetrically equipped with closing springs.

5. Planetary gearbox according to claim 4, characterized in that the closing springs of the planet carrier clutches (K60, K80) are supported opposite one another on the sun gear (SR).

6. Arrangement of a planetary gearbox according to one of the preceding claims, characterized in that it is coupled as a rear-mounted gearbox (NSG) with at least one multi-stage front-mounted gearbox as a unitary gearbox, which is designed as a bottom bracket gearbox, an intermediate gearbox, a chain gearbox or an input gearbox (EG) in the rear wheel hub, wherein the gear steps of the overall arrangement of the gearboxes (EG, NSG) are approximately the same and the gear steps of the front-mounted gearbox(es) are within the gradation of the rear-mounted gearbox (NSG).

7. Arrangement of a planetary gear transmission according to claim 6, characterized in that the input gear (EG) in the rear wheel hub is a ratchet gear transmission.

8. Arrangement of a planetary gearbox according to claim 6, characterized in that the input gear (EG) is arranged in the rear wheel hub as a multi-stage planetary gear in the hub sleeve (1 ) and its output-side ring gear is connected to the downstream planetary gear (NSG) and its planet carrier is connected to the drive and is switched by means of clutches (K20, K30, K40) optionally into the block circuit or by fixing individual sun gears in different gear ratio stages. A planetary transmission arrangement according to claim 8, characterized in that the input gear (EG) is two-stage and the arrangement is a nine-speed transmission whose clutches (K20, ... K90) are designed to be axially shifting throughout. A planetary transmission arrangement according to claim 9, wherein the nine-speed transmission has gear steps between 1.238 and 1.242.

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