Gear shifting mechanism and middle transmission

Abstract

The utility model relates to the technical field of transmissions, and provides a gear shifting mechanism and a middle transmission. The gear shifting mechanism comprises a pawl, an elastic piece, a sliding piece, a screw rod, a nut and a first fixing piece. The screw rod is used for rotating under the driving of external force, the nut is mounted on the screw rod, and the first fixing piece is used for circumferentially limiting the nut; the nut is used for driving the sliding piece to move in the axial direction, and the sliding piece can rotate on the nut in the circumferential direction. A gear shifting groove is formed in the sliding piece, and the axial width of the gear shifting groove is smaller than or equal to the sum of the widths of any two adjacent pawls; the elastic piece is used for abutting against one end of the pawl to enter the gear shifting groove when the sliding piece slides to the position above the gear shifting groove, so that the other end of the pawl tilts up to lock the shaft and the gear. The sliding piece is used for jacking one end of the pawl when sliding to the position where the pawl is away from the gear shifting groove, so that the other end of the pawl is reset to separate the gear from the shaft. And through soft connection gear engaging and hard connection gear retreating, the gear shifting reliability is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of transmissions, in particular to a gear shift mechanism and a mid-mounted transmission. Background Art

[0002] In a mid-mounted transmission, the first gear and shaft are locked and released by a shift mechanism to enable shifting in and out of gears. When multiple first gears are mounted on the shaft, different first gears correspond to different gear positions, allowing the transmission to shift between different gears. Existing shift mechanisms suffer from poor reliability during gear shifting. Utility Model Content

[0003] The purpose of the utility model is to provide a gear shift mechanism and a mid-mounted transmission, aiming to solve the problem of poor reliability of the gear shift mechanism during gear shifting in the prior art.

[0004] In a first aspect, the present application provides a shift mechanism for controlling the locking and separation of a shaft and one or more gears mounted on the shaft; the shift mechanism comprises a pawl, an elastic member, a sliding member, a screw, a nut and a first fixing member; the screw is used to rotate under the drive of an external force, the nut is mounted on the screw, and the first fixing member is used to circumferentially limit the nut; the sliding member is axially slidably mounted in the shaft, and the shaft circumferentially limits the sliding member; the nut is used to drive the sliding member to move axially, and the sliding member is circumferentially rotatable on the nut; The pawl and the elastic member are installed in the shaft and are located on the outside of the sliding member; a shift groove is provided on the sliding member, and the axial width of the shift groove is less than or equal to the sum of the widths of any two adjacent pawls; the elastic member is used to press one end of the pawl into the shift groove when the sliding member slides to the point where the pawl is located above the shift groove, so that the other end of the pawl is tilted to lock the shaft and the gear; the sliding member is used to lift one end of the pawl when it slides to the point where the pawl is away from the shift groove, so that the other end of the pawl is reset to separate the gear and the shaft.

[0005] In one embodiment, the shift mechanism further includes a bearing installed between the sliding member and the nut.

[0006] In one embodiment, the number of the bearings is 2, and the shift mechanism further includes an axial positioning member disposed between the two bearings.

[0007] In one embodiment, at least one end of the screw extends outside the first shaft to connect to a driving assembly of the screw.

[0008] In one embodiment, the sliding member includes a sliding member body and a boss protruding from the sliding member body, and the boss is axially slidably installed in the shaft.

[0009] In one embodiment, the shift mechanism further includes retaining springs provided at both ends of the nut, and the retaining springs are used to limit the axial movement of the sliding member on the nut.

[0010] In one embodiment, the first fixing member includes a plurality of fixing rods, and both ends of the fixing rods are mounted on the housing where the shift mechanism is located.

[0011] In one embodiment, a plurality of the fixing rods are passed through the nut.

[0012] In one embodiment, the number of the shift slots on the sliding member is 2.

[0013] In second aspect, the present application provides a mid-mounted transmission, comprising a first shaft, a plurality of first gears circumferentially rotatably mounted on the first shaft, a second shaft parallel to the first shaft, a plurality of second gears mounted on the second shaft, and a shifting mechanism as described in the first aspect above, each first gear being engaged with a corresponding second gear; the shifting mechanism being used to be installed in the first shaft to control the locking and separation of the first shaft and any one or more of the first gears; the first gear locked with the first shaft being used to rotate under the drive of the first shaft, so as to drive the second shaft to rotate through the second gear engaged with the first gear.

[0014] The shift mechanism provided by the present invention has the following beneficial effects: the shift mechanism includes a pawl, an elastic member, a sliding member, a screw, a nut, and a first fixing member. The nut is mounted on the screw, and the first fixing member circumferentially fixes the nut. Therefore, when the screw is rotated, the nut moves axially, thereby driving the sliding member to move axially. The pawl and the elastic member are located outside the sliding member. The sliding member is provided with a shift groove. When the sliding member slides until the pawl is above the shift groove, the elastic member presses one end of the pawl into the shift groove, and the other end of the pawl tilts up, locking the shaft and gear. When the sliding member slides until the pawl is away from the shift groove, the sliding member lifts one end of the pawl, returning the other end to its original position, thereby separating the gear and shaft. Therefore, shifting can be achieved by axially moving the shift member. The pawl locks the shaft and gear (i.e., engages a gear) under the force of the elastic member, and disengages the shaft and gear (i.e., de-gears) under the force of the sliding member. This achieves a flexible engagement and a hard engagement, thereby improving shifting reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0016] Figure 1 A diagram showing the shifting principle of the shifting mechanism provided in an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of the assembly of the shift mechanism on a shaft provided by an embodiment of the present invention;

[0018] Figure 3 A schematic diagram of a shift mechanism provided in an embodiment of the present invention;

[0019] Figure 4 A partially exploded view of a shift mechanism provided by an embodiment of the present invention;

[0020] Figure 5 A schematic diagram of a mid-mounted transmission provided in an embodiment of the present invention.

[0021] Among them, the reference numerals in the figures are:

[0022] 10. Shift mechanism; 12. Ratchet; 13. Sliding member; 131. Shift groove; 132. Sliding member body; 133. Boss; 14. Elastic member; 15. Screw; 16. Nut; 161. Bearing; 162. Axial positioning member; 163. Retaining spring; 17. First fixing member; 171. Fixing rod; 18. Second fixing member; 20. Shaft; 21. First shaft; 22. Second shaft; 23. Limiting hole; 30. Gear; 31. First gear; 32. Second gear. DETAILED DESCRIPTION

[0023] The following describes in detail embodiments of the present invention, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, when the phrases "in one embodiment" or "in some embodiments" appear in various places throughout this specification, not all references are to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0025] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0027] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0028] Please refer to Figure 1-4 Now, the shift mechanism in the embodiment of the present invention is described.

[0029] The shift mechanism 10 is designed to be installed in a mid-mounted transmission and controls the locking and disengagement of a shaft 20 and one or more gears 30 mounted on the shaft 20. The mid-mounted transmission comprises two parallel shafts, one of which is connected to a bicycle disc. The shift mechanism 10 can be installed on either shaft. The shift mechanism 10 includes a pawl 12, a sliding member 13, an elastic member 14, a screw 15, a nut 16, and a first fixing member 17. The screw 15 is used to rotate under the drive of external force, the nut 16 is installed on the screw 15, and the first fixing member 17 is used to circumferentially limit the nut 16; the sliding member 13 is axially slidably installed in the shaft 20, and the shaft 20 circumferentially limits the sliding member 13; the nut 16 is used to drive the sliding member 13 to move axially, and the sliding member 13 is circumferentially rotatable on the nut 16; the pawl 12 and the elastic member 14 are installed in the shaft 20 and are located on the outside of the sliding member 13; a shift groove 131 is provided on the sliding member 13, and the axial width of the shift groove 131 is less than or equal to the sum of the widths of any two adjacent pawls 12, so that one or two pawls 12 enter the shift groove 131. The elastic member 14 is used to press one end of the pawl 12 into the shift groove 131 when the sliding member 13 slides to the point where the pawl 12 is located above the shift groove 131, so that the other end of the pawl 12 is tilted to lock the shaft 20 and the gear 30; the sliding member 13 is used to lift one end of the pawl 12 when the pawl 12 slides to the point where the pawl 12 is away from the shift groove 131, so that the other end of the pawl 12 is reset to separate the gear 30 and the shaft 20.

[0030] Specifically, the shaft 20 circumferentially constrains the slider 13, allowing it to rotate synchronously with the shaft 20. During gear shifting, the screw 15 rotates under the drive of an external force. Since the nut 16 is mounted on the screw 15 and the first fixing member 17 circumferentially constrains the nut 16, the nut 16, driven by the screw 15, moves axially, thereby driving the slider 13 axially, causing the relative position of the slider 13 and the pawl 12 to change. Since the slider 13 is provided with a shift groove 131, the relative position of the shift groove 131 and the pawl 12 also changes. The two ends of the elastic member 14 respectively contact the pawl 12 and the shaft 20. For example, the shaft 20 is provided with a positioning member, and the elastic member 14 is mounted on the positioning member and its two ends contact the pawl 12 and the shaft 20 respectively. The elastic member 14 applies a force to one end of the pawl 12 toward the slider 13. During the axial movement of the slider 13, when one end of the pawl 12 is located above the shift slot 131, the elastic member 14 presses against the one end of the pawl 12, causing it to enter the shift slot 131. This causes the other end of the pawl 12 to tilt and protrude beyond the shaft 20, thereby engaging the other end of the pawl 12 within the gear 30, thereby locking the gear 30 and the shaft 20, thereby enabling gear engagement. When one end of the pawl 12 moves away from the shift slot 131, one end of the pawl 12 contacts the slider 13, causing the slider 13 to lift one end of the pawl 12, returning the other end of the pawl 12 to its original position, thereby disengaging the pawl 12 from the gear 30 and separating the gear 30 from the shaft 20, thereby enabling gear downshifting.

[0031] Through this structural design, the pawl 12 engages a gear under the elastic force of the elastic member 14 and disengages a gear under the thrust of the slider 13, thus achieving soft engagement and hard disengagement, improving shifting reliability. Furthermore, because the slider 13 exerts a greater force on the pawl 12 when rotating, shifting can be achieved while the pawl 12 is loaded. Furthermore, by changing the clutch state of the pawl 12 by moving the slider 13, the control accuracy of the pawl 12 can be improved, thereby enhancing the reliability of the shifting mechanism 10.

[0032] It can be understood that when multiple gears 30 are installed on the shaft 20, the shift mechanism 10 includes multiple pawls 12, each pawl 12 corresponds to an elastic member 14, and each pawl 12 corresponds to a gear 30, for controlling the locking and separation of the corresponding gear 30 and the shaft 20.

[0033] It can be understood that the axial length of the sliding member 13 is greater than the axial length of the shift groove 131. The parts of the sliding member 13 located at both ends of the shift groove 131 are used to support the pawl 12 that does not need to lock the gear 30. That is, the pawl 12 that is not shifting contacts the sliding member 13 and is in a reset state.

[0034] In one embodiment, the edge of the shift groove 131 is provided with an axial slope, so as to increase the exit speed of the pawl 12 from the shift groove 131 and thereby increase the shift-down speed.

[0035] In one embodiment, the sliding member 13 is rotatably sleeved on the nut 16 in the circumferential direction, so that the sliding member 13 rotates synchronously with the shaft 20 while the screw 15 and the nut 16 do not rotate with the shaft 20 .

[0036] In one embodiment, the shift mechanism 10 further includes a bearing 161 installed between the sliding member 13 and the nut 16 , so as to reduce the friction force exerted on the sliding member 13 and the nut 16 when the sliding member 13 and the nut 16 rotate relative to each other.

[0037] In one embodiment, the number of the bearings 161 is two, and the two bearings 161 are respectively disposed at both ends of the nut 16 . The shift mechanism 10 further includes an axial positioning member 162 disposed between the two bearings 161 to position the two bearings 161 in the axial direction.

[0038] In another embodiment, the nut 16 may also be located at one end of the sliding member 13 and abut against the sliding member 13 to push the sliding member 13 to move axially.

[0039] In one embodiment, at least one end of the screw rod 15 extends outside the shaft 20 to connect to a drive assembly of the screw rod 15 so that the drive assembly drives the screw rod 15 to rotate. The drive assembly can be a gear or a chain.

[0040] In one embodiment, the slider 13 includes a slider body 132 and a boss 133 protruding from the slider body 132. The boss 133 is axially slidably mounted within the shaft 20. For example, the shaft 20 may be provided with an axially extending groove, and the boss 133 may be mounted within the groove. This allows the slider 13 to rotate synchronously with the shaft 20 while being able to move axially under the push of the nut 16 to achieve load shifting.

[0041] In one embodiment, the sliding member 13 includes two bosses 133 protruding from both ends of the sliding member body 132. The two bosses 133 are respectively installed in two grooves of the shaft 20, thereby improving the stability of the sliding member 13 during sliding, and further improving the stability of the shift mechanism 10 during shifting.

[0042] In another embodiment, a boss is provided on the shaft 20 and a groove matching the boss is provided on the sliding member 13, so that the shaft 20 can also limit the rotation of the sliding member 13 in the circumferential direction.

[0043] In one embodiment, the shift mechanism 10 further includes retaining springs 163 disposed at both ends of the nut 16 . The retaining springs 163 are used to limit the axial movement of the sliding member 13 on the nut 16 , thereby improving the stability of the sliding member 13 during movement.

[0044] In one embodiment, the first fixing member 17 includes multiple fixing rods 171, each of which is mounted on the housing housing the shift mechanism. For example, the housing is a mid-mounted transmission housing the shift mechanism 10. Both sides of the housing are provided with mounting slots equal in number to the number of fixing rods 171, and the fixing rods 171 are mounted within these slots. Thus, by attaching the fixing rods 171 to the housing, the multiple fixing rods 171 can circumferentially secure the nut 16.

[0045] In one embodiment, a plurality of fixing rods 171 are passed through the nut 16 , thereby eliminating the space occupied by the first fixing member 17 in the circumferential direction.

[0046] In one embodiment, there are two shift slots 131, and each gear 30 corresponds to two pawls 12. The two pawls 12 are respectively disposed on either side of the slider 13 and adapted to fit within the two shift slots 131. Accordingly, each pawl 12 corresponds to an elastic member 14. When the slider 13 moves and the two corresponding pawls 12 are positioned above the two shift slots 131, the two pawls 12 rotate under the force of the corresponding elastic member 14, with one end entering the shift slot and the other end tilting upward. The two pawls 12 engage with two grooves on the inner side of the gear 30, thereby locking the gear 30 and the shaft 20. When the slider 13 moves, moving the two corresponding pawls 12 away from the shift slots 131, the two pawls 12 simultaneously return to their original positions under the force of the slider 13, disengaging from the gear 30 and separating the gear 30 from the shaft 20. By providing two shifting grooves 131 and two pawls 12 corresponding to each gear 30 , the locking strength between the pawl 12 and the gear 30 can be improved, thereby improving the reliability of the shifting mechanism 10 .

[0047] In one embodiment, the shift mechanism 10 further includes a second fixing member 18, which is located outside the sliding member 13. The pawl 12 is rotatably mounted on the second fixing member 18. The second fixing member 18 can be fixed to the shaft 20, so that the pawl 12 can rotate synchronously with the shaft 20 and rotate around the second fixing member 18 to achieve gear shifting.

[0048] In one embodiment, a limiting hole 23 is provided on the shaft 20, and the position of the limiting hole 23 is consistent with the position of the gear 30 on the shaft. The pawl 12 and the elastic member 14 are both provided in the limiting hole 23, so that the movement of the pawl 12 and the elastic member 14 can be limited in the axial direction to achieve locking of the gear 30.

[0049] In one embodiment, a mounting hole for mounting the second fixing member 18 is provided on the shaft 20 , and the second fixing member 18 is passed through the mounting hole, thereby fixing the second fixing member 18 in the axial direction, and further fixing the pawl 12 in the limiting hole.

[0050] The embodiment of the present invention also provides a mid-mounted transmission. Figure 5 As shown, the mid-mounted transmission includes a first shaft 21, a plurality of first gears 31 rotatably mounted on the first shaft 21, a second shaft 22 parallel to the first shaft 21, a plurality of second gears 32 mounted on the second shaft 22, and the aforementioned shift mechanism 10. Each first gear 31 meshes with a corresponding second gear 32. The shift mechanism 10 is mounted within the first shaft 21 to control the locking and release of the first shaft 21 from any one or more first gears 31. The first gear 31 locked with the first shaft 21 is driven to rotate by the first shaft 21, thereby driving the second shaft 22 to rotate via the second gear 32 meshing with the first gear 31. For example, a bicycle frisbee is mounted on the second shaft 22, and the rotation of the second shaft 22 provides the bicycle with forward power.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gear shift mechanism for controlling the locking and disengagement of a shaft and one or more gears mounted on the shaft; characterized in that: The shift mechanism includes a pawl, an elastic member, a sliding member, a screw, a nut and a first fixing member; the screw is used to rotate under the drive of an external force, the nut is mounted on the screw, and the first fixing member is used to circumferentially limit the nut; the sliding member is axially slidably mounted in the shaft, and the shaft circumferentially limits the sliding member; the nut is used to drive the sliding member to move axially, and the sliding member is circumferentially rotatable on the nut; the pawl and the elastic member are mounted in the shaft and located outside the sliding member; a shift groove is provided on the sliding member, the axial width of the shift groove is less than or equal to the sum of the widths of any two adjacent pawls; the elastic member is used to press one end of the pawl into the shift groove when the sliding member slides to the pawl being above the shift groove, so that the other end of the pawl is tilted to lock the shaft and the gear; the sliding member is used to lift one end of the pawl when the pawl slides to the point where the pawl is away from the shift groove, so that the other end of the pawl is reset to separate the gear and the shaft.

2. The shift mechanism according to claim 1, wherein: The shift mechanism further includes a bearing installed between the sliding member and the nut.

3. The shift mechanism according to claim 2, characterized in that: The number of the bearings is 2, and the shift mechanism further includes an axial positioning member arranged between the two bearings.

4. The shift mechanism according to claim 1, wherein: At least one end of the screw extends outside the shaft to connect with a driving assembly of the screw.

5. The shift mechanism according to claim 1, characterized in that: The sliding member includes a sliding member body and a boss protruding from the sliding member body, and the boss is axially slidably installed in the shaft.

6. The shift mechanism according to claim 1, wherein: The shift mechanism further includes retaining springs provided at both ends of the nut, and the retaining springs are used to limit the axial movement of the sliding member on the nut.

7. The shift mechanism according to claim 1, wherein: The first fixing member includes a plurality of fixing rods, and both ends of the fixing rods are mounted on the housing where the shift mechanism is located.

8. The shift mechanism according to claim 7, characterized in that: A plurality of fixing rods are passed through the nuts.

9. The shift mechanism according to claim 1, characterized in that: The number of the shift grooves on the sliding member is 2.

10. A mid-mounted transmission, characterized in that: The shift mechanism comprises a first shaft, a plurality of first gears rotatably mounted on the first shaft, a second shaft parallel to the first shaft, a plurality of second gears mounted on the second shaft, and a shift mechanism according to any one of claims 1 to 9, wherein each first gear is engaged with a corresponding second gear; the shift mechanism is configured to be mounted in the first shaft to control the locking and release of the first shaft and any one or more of the first gears; The first gear locked with the first shaft is used to rotate under the drive of the first shaft, so as to drive the second shaft to rotate through the second gear meshing with the first gear.

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