Cage free wheel

Abstract

To provide a cage free wheel with a sprag cage, which is installed in a clamp gap between a shaft and a hub in a driving portion of an electric automobile especially.SOLUTION: A cage free wheel is provided with sprags that continue in a circumferential direction in a first embodiment and are rotatably disposed in a sprag case, and each sprag is elastically energized in a clutch-in direction. A raceway disc is provided adjacent in an axial direction of the sprag case. In a second embodiment, not only bearing rollers (4), but also sprags (5) are provided in a cage ring so as to continue in a circumferential direction. This invention relates to a shaft hub structure, and a driving portion of an electric automobile with a cage free wheel having the above mentioned features.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates in particular to a cage - free wheel for installation in a clamping gap between a shaft and a hub in the drive unit of an electric bicycle. The cage - free wheel has a sprag cage, and the sprag cage is provided with sprags that are rotatably arranged in the sprag cage continuously in the circumferential direction, and each sprag is elastically biased in the clutch - in direction.

Background Art

[0002] Cage - free wheels are known in a number of embodiments. See, for example, German Patent Application Publication No. 102009030614 and German Patent Application Publication No. 102011108413 by the same applicant. A cage ring having each of the features described at the beginning has become known from German Patent Application Publication No. 102019218785.

[0003] Basically, a free wheel requires external radial and axial support because its function can only be ensured by the exact alignment of each sprag. To support the shaft without tilt relative to the hub, it is necessary to support the shaft and the hub against each other at two fulcrums. When a cage - free wheel is installed in the clamping gap between the shaft and the hub, in order to ensure the reliable function of the free wheel, slide bearings or roller bearings have conventionally been arranged on both sides of the cage - free wheel. This leads to relatively large axial structural dimensions depending on the load design of each component. In addition, three separate components, namely two bearings and one free wheel, are required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] During the development of the drive system for electric bicycles, it was found that conventional freewheels and the external roller or sliding bearings required for support necessitate considerable installation space. This is undesirable because it increases the distance between pedals or the axial installation space of the drive system housing compared to conventional bicycles. Based on this, the present invention is based on the challenge of developing a sprag-cage freewheel that enables the most compact shaft / hub connection possible in the axial direction.

[0006] This problem is solved in the present invention by arranging a raceway adjacent to the sprag cage in the cage freewheel of the type described at the beginning. Here, the outer and inner diameters of the raceway correspond to the nominal dimension of the bearing gap minus the bearing tolerance, so the raceway functions as a sliding bearing between the shaft component and the hub component. This makes it possible to configure the cage freewheel so that the raceway has support separate from the freewheel on only one side in the shaft / hub connection, preferably because the raceway, which is positioned on the side opposite to the external roller bearing of the freewheel, forms a second fulcrum, preventing the shaft from tilting relative to the hub even though only one roller bearing is used. Therefore, by omitting the second roller bearing, it is possible to design the shaft / hub connection to be more compact in the axial direction, and furthermore, it leads to an inexpensive and robust structure. [Means for solving the problem]

[0007] In the first embodiment, an annular sprag cage is provided with sprags arranged circumferentially, with each sprag being inserted into a corresponding recess or pocket of the sprag cage. This represents a different approach from, for example, German Patent Application Publication No. 102019218785, which proposes using a freewheel in the drive unit of an electric bicycle where circumferentially arranged sprags and bearing rollers are combined with a roller bearing. Because the circumferential arrangement of sprags according to the present invention provides a larger total sprag surface area, the freewheel can be designed to handle higher loads, or to have smaller dimensions, for the same load design, compared to a freewheel with combined, circumferentially arranged bearing rollers and sprags.

[0008] The raceway, in combination with a separate roller bearing positioned on one side of the freewheel, increases the rigidity of the freewheel against tilting forces that occur when a helical gear, commonly used in the drivetrain of an electric bicycle, is supported as the hub, by widening the contact surface between the shaft and the hub.

[0009] In an advantageous embodiment, the raceway plate is connected to the sprag cage via engaging joints that interlock with each other at least partially in a complementary manner. This allows the raceway plate and sprag cage to be manufactured separately and easily connected via engaging joints. The advantage of this embodiment is that the raceway plate and sprag cage can be manufactured separately using materials best suited to their respective functions, for example, the cage using elastic plastics such as polyamide or polyethylene ether ketone (PEEK), and the raceway plate using a suitable metal such as brass or hardened steel.

[0010] In another advantageous embodiment, the raceway is fixed axially but rotatable relative to the sprag cage. This is particularly advantageous because, when each sprag is positioned upright relative to the fixing direction, the freewheel cage performs relative rotation against the rotational movement of each sprag relative to the contact surfaces fixed to each other. Therefore, since relative rotation is not transmitted to the raceway by the raceway which is rotatable relative to the freewheel cage, it is possible to hold the raceway in a rotationally immobile position relative to one of the contact surfaces.

[0011] For those skilled in the art, there are various possibilities for forming the structure of the engagement joint between the sprag cage and the raceway plate, which interlock with each other in a partially complementary manner. For example, the engagement joint may have an engagement profile that extends circumferentially in a swallowtail, hook, or mushroom shape.

[0012] It is structurally advantageous if the engagement profile is formed as a concentric, continuous ring or a partially interrupted ring. Similarly, it is structurally advantageous if the engagement joint has recesses formed in the raceway that are formed to be continuous or circumferentially divided along the circumferential direction of the raceway. For example, the recesses can have three portions, each 60 degrees apart, distributed on the circumference of the raceway.

[0013] Basically, it is preferable that the engagement profile is formed in the sprag cage and engages with the recess of the raceway from the radially inward to the outward direction.

[0014] The axial fixation of the raceway can be carried out at the shaft or hub, for example in the form of a sliding bearing or with the interposition of a roller bearing, thereby allowing the raceway to rotate freely relative to the other part.

[0015] Similarly, it is generally preferable to form the raceway using sliding bearings, particularly radial sliding bearings, and preferably a combination of radial and axial sliding bearings.

[0016] Each sprag is preferably positioned in a sprag cage so as not to be detached, with elastic retaining elements interposed as needed. This provides the user with an assembly that can be easily inserted into the ring gap between the shaft and the hub. Axial fixation of the raceway can be achieved by press-fitting or screw connection to the shaft or hub.

[0017] The present invention further relates to a shaft-hub structure, the shaft-hub structure comprising a hub, a shaft rotatable relative to the hub, and a cage freewheel of the aforementioned type positioned in a clamp gap between the shaft and the hub, wherein a roller bearing formed as a radial bearing is positioned adjacent to one side of the cage freewheel, and the shaft and the hub are supported by each other via the roller bearing. Due to the structure of such a shaft-hub structure, the overall axial length of the shaft-hub structure is shorter compared to a structure in which roller bearings are provided on both sides of the freewheel, and consequently, it becomes possible to form the crankset or drive unit housing axially narrower, especially in the case of electric bicycles.

[0018] It is structurally particularly advantageous for the freewheel cage to preferably be in axial contact with the roller bearing on the side opposite to its raceway. However, an arrangement in which the raceway is in axial contact with the roller bearing is also possible.

[0019] Similarly, the positions of both bearings can be clipped and fixed to the cage in a complementary engagement manner.

[0020] Similarly, a structurally particularly advantageous feature of the cage-free wheel is that the raceway is fixed to either the shaft or the hub, and each is rotatable relative to the other.

[0021] In the second embodiment, in the form of a cage ring, the freewheel cage of the cage-free wheel is provided not only with each sprag but also with each bearing roller in the circumferential direction. As a result, a roller bearing is incorporated into the sprag freewheel, making it possible to omit an additional roller bearing in the ring gap between the shaft portion and the hub portion. The sprag freewheel in which each sprag and each bearing roller are alternately arranged in the circumferential direction in a common freewheel cage is known from German Patent Application Publication No. 102019218785 and German Patent Application Publication No. 102006004491.

[0022] According to the present invention, the freewheel cage according to the second embodiment has at least one axially projecting projection, and the projection is in complementary engagement with a track plate that is axially adjacent and axially fixed, and is rotatable with respect to the track plate but axially fixed. Thus, the freewheel cage is freely relatively rotatable with respect to the track plate.

[0023] This ensures accurate support of the machine parts fixed to itself while having a high output density, that is, it is possible to absorb the generated radial force, axial force and tilting force, and particularly solves the problem of developing a sprag cage-free wheel with a compact structure. Furthermore, the novel structure is characterized by high operating safety and advantageous manufacturing costs.

[0024] Therefore, the present invention no longer requires further axial fixation of the cage-free wheel in order to combine a cage provided with each sprag and each bearing roller with a radial / axial sliding bearing. This makes it possible to significantly reduce the installation space.

[0025] The track plate not only axially fixes the cage-free wheel with respect to the clamping gap between the shaft portion and the hub portion, but also increases the rigidity of the free wheel against the tilting force that occurs when, for example, a helical gear-shaped gear commonly used in the drive unit of an electric bicycle is supported as the hub portion by widening the contact surface between the shaft portion and the hub portion.

[0026] There are various possibilities for those skilled in the art regarding the formation of the axially projecting structure of the free wheel cage. Thus, for example, the projection may have a cross-section in the shape of a swallowtail, a hook, or a mushroom, and engages radially with a corresponding recess in the track plate according to the cross-section. Similarly, the kinematic inversion of the projection and the track plate is also within the scope of the present invention. For example, the track plate has projections and engages with recesses in the free wheel cage.

[0027] It is particularly advantageous in terms of structure that at least one axially projecting structure of the free wheel cage is formed as a concentrically continuous ring or a partially interrupted ring, for example a slotted ring. The engaged recess provided with an undercut in the track plate can be formed continuously in the circumferential direction (i.e., without interruption). However, for manufacturing reasons, especially when the track plate is manufactured as a sintered part or an injection-molded part, it may be advantageous if the recesses in the track plate are similarly divided. For example, the recesses can each have three 60-degree portions distributed on the circumference of the track plate. Forming it in this way makes it easier to remove each region provided with an undercut from the manufacturing tool.

[0028] Basically, it is preferable that the axial projections of the freewheel cage engage with each recess in the raceway from the radially inward to the radially outward direction. This makes it easier to achieve engagement by elastic snapping, especially when the freewheel cage is made of plastic or formed as an open ring. Similarly, in alternative modifications included in the present invention, the axial projections of the freewheel cage engage with each recess in the raceway from the radially outward to the radially inward direction, i.e., the portion of the projection that fits into the recess faces outward. This can provide various manufacturing advantages.

[0029] The raceway can be fixed axially at either the shaft or hub portion, and the raceway can be freely rotated relative to the other portion, for example, by interposing a sliding bearing or a roller bearing.

[0030] Regarding the spring load of each sprag in the clutch-in direction, it has been found to be particularly advantageous to use elastic spring rings arranged concentrically with respect to the freewheel cage, and the spring rings bias each sprag in the clutch-in direction via each elastic spring tongue.

[0031] Each sprag and each bearing roller is preferably supported in a non-removable manner in the freewheel cage, together with a raceway plate that preferably functions as axial support, with the interposition of elastic retaining elements as necessary. This allows the user to obtain an assembly that can be easily inserted into the ring gap between the shaft and the hub. The axial fixation of the raceway plate can be achieved by press-fitting or screw connection to the shaft or hub.

[0032] Finally, within the scope of the present invention, the freewheel cage has concentric support rings that further contribute to the support of each sprag and each bearing roller. Thus, the freewheel cage and support rings form a two-piece freewheel cage. The two-piece cage prevents each sprag from bending when the spring rings, which are spring-biased and preferably formed as sheet metal press parts, are open, i.e., not connected to the joint in the circumferential direction. On the other hand, the two-piece cage is advantageous when each sprag clutches in, especially when the freewheel cage and support rings are not mechanically fixed to each other. In this case, the cage rings and support rings, both of which are movable relative to each other, result in the synchronization of the clutch-in operation of each sprag.

[0033] Furthermore, the present invention relates to a drive unit for an electric bicycle, the drive unit comprising a drive shaft having a crankset, a sprocket, and a bottom bracket, the drive shaft being connected to a gear via a freewheel, the gear itself being connected to an electric motor via a reduction gear, the freewheel having a freewheel cage, the freewheel cage being provided with not only bearing rollers but also sprags continuously in the circumferential direction, elastically biasing each sprag in the winding direction, the freewheel cage having at least one projection protruding in the axial direction, the projection complementary engaging with a raceway plate that is adjacent in the axial direction and fixed in the axial direction, and while rotatable relative to the raceway plate, it is fixed in the axial direction. Due to this structure of the freewheel cage, the overall length in the axial direction is shortened, making it possible to form the crankset to be narrower in the axial direction accordingly. [Brief explanation of the drawing]

[0034] Further details and features of the present invention will become apparent from the following descriptions of each of the four embodiments with reference to the drawings.

[0035] [Figure 1] This is a radial cross-sectional view of a shaft-hub structure having a cage freewheel installed in the clamp gap between the shaft and the hub, and a roller bearing on one side. [Figure 2] This is a perspective view of a first embodiment of a cage-free wheel having a complementary engagement raceway plate with radial bearing specifications. [Figure 3] Figure 2 is a radial cross-sectional view of the cage-free wheel. [Figure 4] This is a perspective view of a second embodiment of a cage-free wheel having complementary engagement raceway discs for radial bearing / axial bearing specifications. [Figure 5] Figure 4 is a radial cross-sectional view of the cage-free wheel. [Figure 6] This is a perspective view of a third embodiment of a cage-free wheel having a complementary engagement raceway plate with radial bearing specifications. [Figure 7] Figure 6 is a radial cross-sectional view of the cage-free wheel. [Figure 8] This is a perspective view of a fourth embodiment of a cage-free wheel having complementary engagement raceway plates for radial bearing / axial bearing specifications. [Figure 9] Figure 8 is a radial cross-sectional view of the cage-free wheel. [Figure 10] This is a first modification of a cage-free wheel according to a second embodiment, in which each sprag and each bearing roller are arranged in a continuous manner, and each of its components is individually illustrated in a perspective view. [Figure 11] Figure 10 shows radial cross-sectional views of the same component. [Figure 12] The assembled cage ring in the shaft / hub connection is shown in Figures 10 and 11. [Figure 13] This is a second modified example of the cage-free wheel according to the second embodiment, in which each of its components is individually illustrated in a perspective view. [Figure 14] Figure 13 shows radial cross-sectional views of the same component. [Figure 15] The assembled cage ring in the shaft / hub connection is shown in Figures 13 and 14. [Figure 16]This is a third modified example of the cage-free wheel according to the second embodiment, in which each of its components is individually illustrated in a perspective view. [Figure 17] This is a radial cross-sectional view of the same component in Figure 16. [Figure 18] The assembled cage ring in the shaft / hub connection is shown in Figures 16 and 17. [Figure 19] A fourth modified example of the cage-free wheel according to the second embodiment, in which each of its components is individually shown in the perspective view, and which has protrusions formed by division in the cage ring. [Figure 20] Figure 19 shows radial cross-sectional views of the same component. [Figure 21] The assembled cage rings in the shaft / hub connection are shown in Figures 19 and 20. [Figure 22] This is another embodiment of the fourth modification, in which the raceway plate has divided recesses. [Figure 23] This is a further embodiment of the fourth modification, in which not only the protrusions in the cage ring but also the recesses in the raceway plate are formed by dividing them. [Figure 24] Figures 10 to 23 show the drive unit of an electric bicycle equipped with a cage-free wheel. [Modes for carrying out the invention]

[0036] Figure 1 illustrates a shaft-hub structure having a hub 2, a shaft 1 rotatable relative to the hub, and a cage-free wheel 3 positioned in a clamp gap between the shaft and the hub (see Figures 5 and 6). A raceway plate 7, rotatable relative to the cage-free wheel 3 but axially fixed to the hub 2, is fitted into a corresponding recess in the hub 2 and is slidably supported relative to the shaft. Furthermore, the raceway plate in this example enables axial support of the cage-free wheel, thereby preventing tilting of the sprag cage by axial fixing. In this embodiment, radial support is formed by the cooperation of the roller bearing 4 and the raceway plate 7. Thus, bilateral support of the cage-free wheel is achieved via the roller bearing 4 and the raceway plate 7, even though only one roller bearing 4 is used.

[0037] Figure 2 shows a cage-free wheel, which has a sprag cage 3 in the shape of a flat cylindrical ring with multiple circumferentially continuous pockets. The cage-free wheel is positioned between the shaft portion and the hub portion (not shown in this figure). Each sprag 5 is inserted into each pocket of the sprag cage 3. Each sprag 5 can generate torque transmission between the shaft portion and the hub portion in the fixed direction by performing a slight tilting motion in its own pocket in a manner known to itself. To transmit high torque, as many sprags 5 as possible are provided in the sprag cage 3.

[0038] Each sprag 5 of a sprag freewheel, often also called a sprag, is manufactured to be non-circular in shape, and therefore has one long and one short lateral extension. In its long lateral extension, each sprag is formed to be sandwiched in a ring gap formed by the outer surface of the shaft portion and the inner sliding surface of the hub portion when the clutch is engaged.

[0039] To ensure that each sprag 5 is reliably clutched, each sprag is biased or prestressed in the clutch-in direction by a ring-shaped spring ring 6, which is in the form of a spiral spring provided circumferentially around the row of sprags. Therefore, each sprag has a groove surrounding its outer contact surface into which the spring ring 6 is inserted.

[0040] The present invention can also be realized using other cage structures, such as individual sprag sections that are spring-biased or spring-biased by surrounding sheet metal springs.

[0041] The sprag cage 3 has a first fitting element 3a having a hook-shaped profile that protrudes axially and radially at one side edge (see Figure 3). The first fitting element 3a partially corresponds to a second fitting element 7a in the raceway 7, the second fitting element forming a recess or undercut, the first fitting element 3a being able to fit behind the undercut and engage with the undercut from the outside in. Thus, the two corresponding fitting elements 3a and 7a are able to engage with each other, forming a complementary, interlocking engagement joint between the raceway 7 and the sprag cage 3.

[0042] Here, the mating element 3a is divided, that is, it is formed with sections interrupted in the circumferential direction. This makes it possible to elastically snap the mating element 3a to the mating element 7a of the raceway plate 7.

[0043] Here, the mating element 3a is formed as an engaging hook having a projection. This engaging hook is lightly pressed inward until it engages with a mating element 7a, which is similarly formed as an engaging hook, when the raceway board 7 is installed. This embodiment of the engaging joint between the sprag cage 3 and the raceway board 7 is easy to install, which is advantageous for many applications.

[0044] The raceway plate forms a sliding surface on its outer circumference relative to the hub portion. This enables it to function as a radial bearing. Within the scope of this invention, kinematic reversal of the bearing function, i.e., sliding support relative to the shaft portion, is also possible.

[0045] Figures 4 through 9 illustrate each modified embodiment. To avoid repetition, only the essential differences from the embodiment shown in Figure 2 will be described below. Identical or corresponding elements are denoted by the same reference numerals.

[0046] Figure 4 illustrates another embodiment of the cage-free wheel. It can be seen that the raceway has a flange-like region 7b that extends radially (see Figure 5). The raceway 7 can be connected to the shaft portion via the flange region 7b so that it is axially displaceable and, preferably, more rotationally immobile. Therefore, in this embodiment, the raceway 7 provides not only radial support but also axial support.

[0047] The engagement joint between the sprag cage 3 and the raceway plate 7 is complementary in the axial direction but rotatable in the circumferential direction. This provides effective fixation of the cage ring and has the advantage of eliminating the need for further axial support.

[0048] Figure 6 illustrates another embodiment of a cage-free wheel in which the raceway 7 functions as a radial bearing. Important to this embodiment is that the raceway 7 has a surrounding fitting element 3a that protrudes axially and radially at one side edge (see Figure 6). The fitting element 7a partially corresponds to the fitting element 3a of the sprag cage 3 and engages with the fitting element from the inside out. This forms a complementary, interlocking mating connection between the raceway 7 and the sprag cage 3.

[0049] Even in this case, the mating element 3a is divided in the sprag cage 3, that is, it is formed in sections. This makes it easier for the projection 7a to elastically snap to the mating element 3a of the sprag cage 3.

[0050] Here, the mating element 7a is formed as an engaging hook having a projection. The engaging hook lightly presses the divided mating element 3a of the sprag cage inward until the mating element 7a engages with the mating element 3a, which is similarly formed as an engaging hook when attached to the sprag cage 3. This embodiment of the engaging joint between the sprag cage 3 and the raceway board 7 is easy to install, which is advantageous for many applications. In this example, the raceway board has an additional chamfer for the purpose of further facilitating installation.

[0051] Figure 8 illustrates another embodiment of the cage freewheel. It can be seen that the raceway has a region 7b with an enlarged outer diameter relative to the freewheel cage, extending radially (see Figure 9). By receiving the enlarged diameter region of the raceway 7 into a corresponding recess in the hub, the raceway 7 can be connected to the hub portion in a displacement-immobile, preferably more rotationally-immobile manner. This provides the raceway 7 with axial support in addition to radial sliding support. The raceway 7 also has an additional chamfer for easy mounting, as can be seen in the embodiment in Figure 6.

[0052] Here, the fitting element 3a of the sprag cage is again divided, that is, interrupted in sections. This makes it easier for the projection 3a to elastically snap to the fitting element 3a of the raceway plate 7.

[0053] The mating element 3a has an engaging hook with a projection, similar to that seen in the embodiment shown in Figure 6. The engaging hook is lightly pressed inward during the installation of the raceway board until it engages with the mating element 7a, which is similarly formed as an engaging hook in the raceway board 7, and engages with the mating element from the inside out. This embodiment of the engaging joint between the sprag cage 3 and the raceway board 7 is easy to install, which is advantageous for many applications.

[0054] Each embodiment is characterized by minimal installation space because, by complementary engagement between the cage ring and the raceway plate, and by forming the raceway plate 7 as a radial or, optionally, axial sliding bearing, it is possible to omit the second roller bearing for supporting the shaft and hub.

[0055] In the second embodiment shown in Figure 10, an inner shaft portion 1 and an outer hub portion 2 are visible, with a cage-free wheel incorporated between them. The cage-free wheel consists of an actual cage ring 3 in the form of a flat cylindrical ring having a plurality of circumferentially continuous windows 3a. It is possible to insert cylindrical bearing rollers 4 or sprags 5 into each window 3a. While each bearing roller 4 functions as a roller bearing, each sprag 5 can generate torque transmission between the shaft portion 1 and the hub portion 2 by performing a slight tilting motion in its own window in a manner known to itself. As many sprags 5 as possible are provided in the ring 3 to transmit high torque, whereas in the case of each bearing roller 4, a minimum of three bearing rollers is often sufficient.

[0056] For each sprag 5 to reliably engage in the clutch, each sprag is biased in the clutch-in direction by a spring. In this embodiment, this is achieved by a spring ring 6 that surrounds the sprag in a ring shape, and each spring ring has a spring tongue 6a in the region of each sprag 5.

[0057] Each sprag 5 in a sprag freewheel, often also called a sprag, is manufactured to be non-circular and therefore has one long and one short lateral extension. In its long lateral extension, each sprag is slightly wider than the diameter of each bearing roller 4, so each sprag is sandwiched in the ring gap formed by the outer surface of the shaft portion 1 and the inner sliding surface of the hub portion 2 when the clutch engages. In its short lateral extension, each sprag 5 is slightly narrower than the diameter of each bearing roller 4, so each sprag is elastically biased in the clutch-engagement direction and slides along each sliding surface of the ring gap.

[0058] The key feature here is that the cage ring 3 has a surrounding ring 3b that protrudes axially and radially at one of its side edges (see Figure 11). This protruding ring 3b corresponds to a recess 7a in the form of an undercut in the axially adjacent raceway plate 7. The raceway plate 7 is connected to the hub portion 2 in a displacement-immobile manner in the axial direction, and preferably also in a rotation-immobile manner. On its inner circumferential surface, the raceway plate forms a sliding surface with respect to the shaft portion 1.

[0059] Figure 12 illustrates the cage ring in its assembled state. In particular, it can be seen that the axial projection 3b of the cage ring, which causes the undercut, is positioned almost on the outer circumference of the cage ring so that the spring ring 6 extends inside the cage ring 3.

[0060] The complementary engagement between the projections 3b of the cage ring 3, which engage axially complementary with the recess 7a of the axially fixed raceway plate 7, but are movable in the circumferential direction, has the advantage of providing effective fixing of the cage ring in both axial directions, i.e., eliminating the need for additional axial support on the opposite side of the cage ring.

[0061] Figures 13 to 15 illustrate a second alternative embodiment of the cage ring. This alternative embodiment consists of substantially the same parts, except that the cage ring 13 and the recess 17a in the raceway plate 17 have slightly smaller diameters than in the first alternative embodiment. As a result, the cage ring 13 extends on the inside of the spring ring 6 rather than the outside; see Figure 15.

[0062] The inner position of the spring ring 13 is suitable when it should rotate with the shaft 1 rather than the hub 2. In this case, the raceway plate 17 can be fixed to the shaft, while the raceway plate can rotate relative to the hub 5 on its outer circumference.

[0063] Furthermore, in the second embodiment, the complementary engagement between the projection 13b and the recess 17a is formed in a hook shape rather than a swallowtail shape as in the first embodiment. Therefore, the projection 13b has an outer sliding surface that extends in a conical shape, and this sliding surface causes the projection to slide along the corresponding sliding surface on the inner circumference of the recess 17a when engaged. At that time, the projection 13b, which is formed in the shape of an engaging hook, is lightly pressed inward until it engages after the undercut formed by the recess 17a. This embodiment of the engaging joint between the cage ring 13 and the raceway plate 17 is easier to install and more difficult to remove than the connection in the first embodiment, which is advantageous for many applications.

[0064] Figures 16 to 18 and 19 to 21 illustrate third and fourth alternative embodiments of the cage ring structure. These alternative embodiments differ from the aforementioned examples only in that they use an additional support ring 23 or 33 rather than a single cage ring 3 or 13. The support ring 23 or 33 is formed similarly to the cage ring 3 or 13 and thus has windows 23a or 33a necessary to accommodate each bearing roller and each sprag. The support ring supports the non-removable retaining means for each sprag 5 and each bearing roller 4 in the cage ring 3 or 13 and synchronizes the clutch-in operation of each sprag 5.

[0065] In the structures shown in Figures 16 to 18, the support ring 23 is located on the outside of the cage ring 3, whereas in the structures shown in Figures 19 to 21, the support ring 33 is located on the inside of the cage ring 13; see Figures 18 to 21 in particular.

[0066] In both cases, the spring ring 6 was positioned between the cage ring 3 or 13 and the support ring 23 or 33.

[0067] The cage ring 3 or 13, the spring ring 6, and the support ring 23 or 33 may be made of metal or plastic.

[0068] Furthermore, using open, radially elastic rings instead of closed rings is also within the scope of the present invention.

[0069] As can be seen in Figure 19, in the embodiment shown in Figure 19, the projection 3b is divided in the cage ring 3, that is, it is formed as a ring that is interrupted in sections. This makes it easier for the projection 3b to elastically snap into the recess 17a in the raceway plate 17.

[0070] In the modified example shown in Figure 22, a recess 17a or undercut is formed in the raceway 17 instead of the projection 3b in the cage ring 3, and the protruding edge of the raceway 17 is divided, i.e., interrupted in sections, whereas the projection 3b is configured as a continuous ring as in Figure 10. The divided and undercut recess 17a has manufacturing advantages as described above when the raceway 17 is manufactured as a sintered or injection-molded part.

[0071] Finally, Figure 23 shows a modified example of the combined components, in which not only the projection 3b in the cage ring 3 but also the recess 17a in the raceway plate 17 are formed in separate sections.

[0072] All embodiments feature minimal installation space because the complementary engagement connection between the cage ring and the raceway does not require further axial support of the freewheel.

[0073] Figure 24 illustrates the drive unit of an electric bicycle with the housing removed. A drive shaft 1, often also called a bottom bracket shaft, is visible, and the drive shaft is fixed to a bottom bracket set 41 consisting of a sprocket 40 and two terminal cranks, each containing a pedal.

[0074] Furthermore, a bottom bracket 42 is visible, and the drive shaft is supported by the bicycle frame via this bottom bracket.

[0075] Furthermore, the bottom bracket shaft 1 can be driven by an electric motor 45 via a helical gear-shaped gear 43 and a reduction gear 44.

[0076] Therefore, the gear 43 is connected to the hub portion 2 in Figures 10 to 12, and together with the hub portion 2, surrounds the cage free wheel 3 as described in Figures 10 to 12. The raceway plate 7, which is rotatable relative to the cage free wheel 3 but fixed in the axial direction, is press-fitted into a corresponding recess in the hub portion 2 and is slidably supported relative to the bottom bracket shaft 1.

Claims

1. A cage-free wheel for installation in a clamp gap between a shaft and a hub, particularly in a drive unit of an electric bicycle, having a sprag cage (3), wherein the sprag cage is provided with sprags (5) rotatably arranged circumferentially therein, and the sprags (5) are elastically biased in the clutch engagement direction in the cage-free wheel. A cage-free wheel, characterized in that an orbiting ring (7) is arranged axially adjacent to the sprag cage (3).

2. The cage-free wheel according to claim 1, characterized in that the sprag cage (3) is provided with sprags (5) rotatably arranged circumferentially and continuously therein.

3. The cage-free wheel according to claim 2, characterized in that the orbiting ring (7) and the sprag cage (3) are connected via a snap fit that at least partially interlocks with a form-fit connection.

4. The cage-free wheel according to claim 3, characterized in that the orbiting ring (7) is rotatable relative to the sprag cage (3) but axially fixed.

5. The cage-free wheel according to claim 3 or 4, characterized in that the snap fit has a dovetail-shaped, hook-shaped, or mushroom-shaped engagement profile with an engagement profile extending circumferentially.

6. The cage-free wheel according to claim 5, characterized in that the engagement profile is formed as a concentrically continuous ring or a partially interrupted ring.

7. The cage-free wheel according to claim 5, characterized in that the snap fit has recesses formed in the orbiting ring (7) that are formed to be continuous or circumferentially segmented in the circumferential direction of the orbiting ring (7).

8. The cage-free wheel according to claim 5, characterized in that the engagement profile is formed on the sprag cage (3) and engages rearwardly from the inside to the outside in the radial direction in the recess of the orbiting ring (7).

9. The cage-free wheel according to any one of claims 2 to 4, characterized in that the orbiting ring (7) is fixed to one of the shaft and the hub and rotatable relative to the other.

10. The cage-free wheel according to any one of claims 2 to 4, characterized in that the track plate (7) is formed as a sliding bearing, in particular a radial sliding bearing, preferably a combination of a radial sliding bearing and an axial sliding bearing.

11. The cage-free wheel according to any one of claims 2 to 4, characterized in that the sprag (5) is arranged in the sprag cage (3) so as not to fall out of the sprag cage (3).

12. A shaft-hub structure having a hub (2), a shaft (1) rotatable relative to the hub (2), and the cage-free wheel according to any one of claims 1 to 4 arranged in a clamping gap between the shaft and the hub, wherein a roller bearing or a sliding bearing formed as a radial bearing is arranged adjacent to one side of the cage-free wheel, and the shaft (1) and the hub (2) are supported relative to each other via the roller bearing or the sliding bearing.

13. The shaft-hub structure according to claim 12, characterized in that the track plate (7) of the cage-free wheel is fixed to one of the shaft (1) and the hub (2) and is rotatable relative to the other.

14. The cage-free wheel according to claim 1, characterized in that the sprag cage (3, 13) is provided with not only bearing rollers (4) but also sprags (5) continuously in the circumferential direction, and the sprags (5) are elastically biased in the clutch-engaging direction.

15. The cage-free wheel according to claim 14, characterized in that the sprag cage (3, 13) has at least one axially projecting projection (3b, 13b), and the projection is in form-fitting engagement with the track plate (7, 17) which is axially adjacent and axially fixed, and is rotatable relative to the track plate (7, 17) while being axially fixed.

16. The cage-free wheel according to claim 15, characterized in that the at least one axially projecting projection (3b, 13b) of the sprag cage (3, 13) has a dovetail-shaped, hook-shaped, or mushroom-shaped cross-section and engages rearward in the radial direction with a corresponding recess (7a, 17a) in the track plate (7, 17).

17. The at least one axially projecting projection (3b, 13b) of the sprag cage (3, 13) is formed as a concentrically continuous ring or a partially interrupted ring, the cage-free wheel according to claim 16.

18. The recesses (7a, 17a) in the raceways (7, 17) are formed so as to be continuous in the circumferential direction or divided in the circumferential direction, the cage-free wheel according to claim 16 or 17.

19. The at least one axially projecting projection (3b, 13b) of the sprag cage (3, 13) rear-engages from the inside to the outside in the radial direction with the recesses (7a, 17a) in the raceways (7, 17), the cage-free wheel according to claim 16 or 17.

20. The raceway (7, 17) is fixed to one of the adjacent shaft (1) and hub (2) and is rotatable relative to the other (2 or 1), the cage-free wheel according to any one of claims 15 to 17.

21. The raceway (7, 17) is formed as a sliding bearing, the cage-free wheel according to any one of claims 15 to 17.

22. The raceway (7, 17) is rotatably supported relative to the shaft (1) or the hub (2) via a roller bearing, the cage-free wheel according to any one of claims 15 to 17.

23. The elastic biasing of the sprag (5) is carried out by a spring ring (6) arranged concentrically with respect to the sprag cage (3, 13), and the spring ring (6) biases the sprag (5) in the clutch-engaging direction via an elastic spring tongue (6a), the cage-free wheel according to any one of claims 14 to 17.

24. The bearing roller (4) and the sprag (5) are supported, preferably together with the raceway (7, 17), in the sprag cage (3, 13) so as not to fall out of the sprag cage (3, 13), with an elastic retaining element interposed if necessary, the cage-free wheel according to any one of claims 14 to 17.

25. The cage-free freewheel according to any one of claims 14 to 17, wherein the sprag cage (3, 13) has concentric support rings (23, 33) that additionally contribute to the support of the sprag (5) and the bearing roller (4).

26. A drive unit of an electric bicycle, comprising a crankset (41), a sprocket (40), a bottom bracket (42) and a drive shaft (1), wherein the drive shaft (1) is connected to a gear (43) via a freewheel, the gear (43) is connected to an electric motor (45) via a reduction gear (44), the freewheel has a sprag cage (3), the sprag cage (3) is provided with not only bearing rollers (4) but also sprags (5) continuously in the circumferential direction, and the sprags are elastically biased in the clutch-engaging direction. The drive unit of an electric bicycle, wherein the sprag cage (3) has at least one axially projecting protrusion (3b), and the protrusion (3b) is in form-fitting engagement with an axially adjacent raceway plate (7) that is axially fixed, and is rotatable with respect to the raceway plate (7) but axially fixed.

27. The drive unit of an electric bicycle according to claim 26, having the cage-free freewheel according to claim 16 or 17.

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