Gear shifting mechanism and middle transmission

Abstract

The gear shifting mechanism comprises a sleeve, a gear shifting pawl and an elastic piece, a gear shifting groove is formed in the sleeve, and the gear shifting pawl comprises a first inclined face; the elastic piece is used for driving one end of the gear shifting pawl to enter the gear shifting groove when one end of the gear shifting pawl is located above the gear shifting groove, and the other end of the gear shifting pawl tilts up so as to lock a gear located on the outer side of the sleeve. The first slope is used for abutting against the edge of the gear shifting groove and sliding when one end of the gear shifting pawl enters the gear shifting groove. The edge shape of the gear shifting groove is a spiral face around the center shaft of the sleeve, the included angle between the tangent line of a spiral line around the center shaft in the spiral face at a first contact point and the first inclined face is smaller than 10 degrees, and the first contact point is the contact point of the first inclined face and the spiral line. When interaction force exists between the first inclined face and the spiral face, the contact area of the spiral face and the first inclined face is larger, the contact area of the pawls and the sleeve is increased, the local stress of the pawls is reduced, and the situation that the pawls are abraded is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to transmission technical field especially relates to a shift mechanism and middle transmission. BACKGROUND

[0002] In a bicycle or an electrically assisted bicycle, different gears are switched through a transmission, which can change the ratio between input speed and output speed to bring different riding experiences to users. In the prior art, the shift mechanism of the transmission can lock the corresponding gear on the shaft for gear shifting by changing the state of the pawl, so the pawl needs to be driven to rotate or move to change the state of the pawl during gear shifting. When the pawl is driven to rotate or move under a load, a relatively large force is applied to the pawl, which is likely to cause wear of the pawl, affecting the service life of the pawl and further affecting the stability of the transmission. SUMMARY

[0003] The utility model aims at providing a shift mechanism and middle transmission, which aims to solve the problem of the pawl being subjected to a relatively large force during gear shifting in the prior art, which is likely to cause wear of the pawl.

[0004] In a first aspect, the present application provides a shift mechanism, which comprises a sleeve, a shift pawl and an elastic member. The sleeve is provided with a shift groove. The shift pawl comprises a first inclined surface. The elastic member is used to drive one end of the shift pawl into the shift groove and the other end of the shift pawl to be raised when the one end of the shift pawl is located above the shift groove, so as to lock a gear located outside the sleeve. The first inclined surface is used to abut against the edge of the shift groove and slide when the one end of the shift pawl enters the shift groove. The edge of the shift groove is in the shape of a helical surface around the central axis of the sleeve. The included angle between the tangent of the helical line around the central axis in the helical surface and the first inclined surface at a first contact point is less than 10 degrees. The first contact point is the contact point between the first inclined surface and the helical line.

[0005] In an embodiment, the elastic member is located at one end of the shift pawl and is used to press the one end of the shift pawl when the one end of the shift pawl is located above the shift groove, so as to drive the one end of the shift pawl into the shift groove.

[0006] In an embodiment, the elastic member is located at the other end of the shift pawl and is used to lift the other end of the shift pawl when the one end of the shift pawl is located above the shift groove.

[0007] In an embodiment, the included angle between the line connecting a point on the first axis and the first inclined surface and the first inclined surface is less than 60 degrees, and the shift pawl rotates around the first axis.

[0008] In an embodiment, the gear shifting mechanism further comprises a first fixed shaft outside the sleeve, the first fixed shaft penetrating the gear shifting pawl, and the first axis line penetrating the first fixed shaft.

[0009] In an embodiment, the gear shifting pawl further comprises a second inclined surface, the second inclined surface being used to abut against the edge of the gear shifting groove and slide when the gear shifting pawl leaves the gear shifting groove, and the included angle between the tangent line of the helical line of the helical surface around the central axis at a second contact point and the second inclined surface is less than 10 degrees, the second contact point being the contact point of the second inclined surface and the helical line.

[0010] In an embodiment, the sleeve is provided with two gear shifting grooves of the same helical form, and each of the gear shifting grooves corresponds to a group of gear shifting pawls.

[0011] In an embodiment, the gear shifting mechanism further comprises a driving assembly for driving the sleeve to rotate.

[0012] In an embodiment, the driving assembly comprises a sliding piece penetrating the gear shifting groove and used to move along the axial direction of the sleeve to drive the sleeve to rotate.

[0013] In a second aspect, the application provides a central transmission comprising the gear shifting mechanism as described in the first aspect.

[0014] The gear shifting mechanism comprises a sleeve, a gear shifting pawl and an elastic piece, the sleeve is provided with a gear shifting groove, and the gear shifting pawl comprises a first inclined surface; the elastic piece is used to drive one end of the gear shifting pawl to enter the gear shifting groove and the other end to be raised to lock a gear outside the sleeve when the one end of the gear shifting pawl is above the gear shifting groove; the first inclined surface is used to abut against the edge of the gear shifting groove and slide when one end of the gear shifting pawl enters the gear shifting groove; the edge of the gear shifting groove is in the shape of a helical surface around the central axis of the sleeve, and the included angle between the tangent line of the helical line of the helical surface around the central axis at a first contact point and the first inclined surface is less than 10 degrees, the first contact point being the contact point of the first inclined surface and the helical line. When there is an interaction force between the first inclined surface and the helical surface, the helical surface and the first inclined surface are deformed. Since the included angle between the tangent line of the helical line at the first contact point and the first inclined surface is small, the contact area of the helical surface and the first inclined surface is larger. Therefore, during gear shifting, the contact area of the gear shifting pawl and the sleeve is increased, the local stress of the gear shifting pawl is reduced, and the abrasion of the gear shifting pawl is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described in the following are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0016] Figure 1 Part structure schematic diagram of the centrally mounted transmission provided by the embodiments of the present application is shown in the figure.

[0017] Figure 2 Part structure schematic diagram of the centrally mounted transmission provided by the embodiments of the present application is shown in the figure.

[0018] Figure 3 Schematic diagram of the shift mechanism provided by the embodiments of the present application is shown in the figure.

[0019] Figure 4 Schematic diagram of the shift mechanism provided by the embodiments of the present application is shown in the figure.

[0020] Figure 5 Schematic diagram of the shift mechanism provided by the embodiments of the present application is shown in the figure.

[0021] Figure 6 Angle relationship diagram between the first axis and the first inclined surface in the shift mechanism provided by the embodiments of the present application and the first inclined surface is shown in the figure.

[0022] Figure 7 Schematic diagram of the first inclined surface and the second inclined surface in the shift mechanism provided by the embodiments of the present application is shown in the figure.

[0023] In the figure, various reference signs are as follows:

[0024] 10, shift mechanism; 11, sleeve; 111, shift groove; 12, shift pawl; 121, first inclined surface; 122, second inclined surface; 13, elastic member; 14, first fixed shaft; 15, second fixed shaft; 20, transmission shaft; 30, gear. DETAILED DESCRIPTION

[0025] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0026] 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 application. Thus, the appearances of the phrases "in one embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0027] In the description of the present application, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0028] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or a specific number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0029] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] The application provides a kind of middle transmission, middle transmission includes shift mechanism, two transmission shafts and the multiple gear respectively installed on each transmission shaft, shift mechanism is installed on any one transmission shaft.For example, one transmission shaft that installs shift mechanism, as shown in Figure 1 And Figure 2As shown, the central transmission at least includes a shift mechanism 10, a transmission shaft 20 and a plurality of gears 30 (only two gears are shown in the figure), the plurality of gears 30 are rotatably installed on the transmission shaft 20, and each gear 30 has different sizes. For each gear 30, the inside of the gear 30 is provided with an engagement groove matched with the shift mechanism 10, and the shift mechanism 10 is used to lock with the engagement groove, so that the transmission shaft 20 is locked with the corresponding gear 30, and then the transmission shaft 20 is synchronously rotated with the corresponding gear 30. Different gears 30 correspond to different transmission paths, and different transmission paths correspond to different ratios of input speed and output speed of the central transmission. The shift mechanism 10 can make the transmission shaft 20 synchronously rotate with different gears 30 by switching different gears 30, so as to change the transmission path of the central transmission and realize the gear shifting of the central transmission. The gear shifting is the gear shifting, and the state that the transmission shaft 20 is locked with the gear 30 is the gear engagement state, and the state that the transmission shaft 20 is separated from the gear 30 is the gear disengagement state.

[0031] As Figures 2 to 7 shown, the shift mechanism 10 in the embodiment of the utility model will be described.

[0032] The shift mechanism 10 includes a sleeve 11, a shift pawl 12 and an elastic member 13, the sleeve 11 is provided with a shift groove 111, the shift pawl 12 includes a first inclined surface 121, the elastic member 13 is used to drive one end of the shift pawl 12 to enter the shift groove 111 when the one end of the shift pawl 12 is located above the shift groove 111, and the other end is raised to lock the gear 30 located outside the sleeve 11, the first inclined surface 121 is used to abut against the edge of the shift groove 111 and slide when one end of the shift pawl 12 enters the shift groove 111, the edge of the shift groove 111 is shaped as a spiral surface around the central axis of the sleeve 11, the included angle between the tangent of the spiral line around the central axis in the spiral surface and the first inclined surface 121 at a first contact point is less than 10 degrees, and the first contact point is the contact point of the first inclined surface 121 and the spiral line.

[0033] Specifically, the sleeve 11 and the shift pawl 12 move relative to each other, when one end of the shift pawl 12 is above the shift groove 111, the first inclined surface 121 is above the edge of the shift groove 111 and in contact with the edge of the shift groove 111. The elastic member 13 exerts a force on one end of the shift pawl 12, when the sleeve 11 and the shift pawl 12 continue to move relative to each other, the first inclined surface 121 abuts against the edge of the shift groove 111 and slides, when the first inclined surface 121 is disengaged from the edge of the shift groove 111, one end of the shift pawl 12 enters the shift groove 111, while the other end is lifted. When the sleeve 11 and the shift pawl 12 move relative to each other, there is an interaction force between the sleeve 11 and the shift pawl 12, the force point of the force exerted by the sleeve 11 on the shift pawl 12 is the contact point between the sleeve 11 and the first inclined surface 121. The first inclined surface 121 is composed of a plurality of helical lines, different helical lines correspond to different directions of curvature, when the helical line around the central axis is in contact with the first inclined surface 121, the contact point is the first contact point, when the tangent of the helical line around the central axis at the first contact point is less than 10 degrees with the first inclined surface 121, the tangent of the helical line around the central axis at the first contact point is close to parallel with the first inclined surface 121, and the helical surface is close to parallel with the first inclined surface 121. Preferably, the tangent of the helical line around the central axis at the first contact point is less than 5 degrees with the first inclined surface 121. Under the condition that there is an interaction force between the sleeve 11 and the shift pawl 12, the sleeve 11 or the shift pawl 12 will deform to a certain extent, so that the sleeve 11 and the shift pawl 12 have surface contact, if the tangent of the helical line around the central axis at the first contact point is close to parallel with the first inclined surface 121, it will make the contact area larger when the sleeve 11 and the shift pawl 12 deform, so as to reduce the local stress of the shift pawl 12, reduce the wear of the shift pawl 12, and thus improve the stability of the mid-mounted transmission.

[0034] In an embodiment, the elastic member 13 is located at one end of the shift pawl 12, that is, the elastic member 13 and the first inclined surface 121 are located at the same end of the shift pawl 12. The elastic member 13 exerts a force on the shift pawl 12 towards the sleeve 11, when one end of the shift pawl 12 is above the shift groove 111, the elastic member 13 presses one end of the shift pawl 12, so that one end of the shift pawl 12 enters the shift groove 111, and the other end is lifted to be engaged on the gear 30. Designing the elastic member 13 to press downward on the shift pawl 12 can save the occupied space of the shift mechanism 10, and thus the volume of the mid-mounted transmission can be reduced.

[0035] In an embodiment, the elastic member 13 is located at the other end of the shift pawl 12, i.e. the elastic member 13 and the first inclined surface 121 are located at the two ends of the shift pawl 12 respectively. The elastic member 13 applies a force to the shift pawl 12 away from the sleeve 11. When the shift pawl 12 is located above the shift groove 111 at one end, the elastic member 13 and the shift groove 111 cooperate to lift the other end of the shift pawl 12, while the one end of the shift pawl 12 enters the shift groove 111, thereby achieving the locking of the gear 30.

[0036] In an embodiment, the shift pawl 12 rotates around the first axis, and the angle between the line connecting the point on the first axis and the first inclined surface 121 and the first inclined surface 121 is less than 60 degrees. For example, the angle A between the line connecting any point on the first axis and any point on the first inclined surface 121 and the first inclined surface 121 is less than 60 degrees. In the case where the first inclined surface 121 and the edge of the shift groove 111 are in contact, the force arm length of any point on the first inclined surface 121 is the vertical distance between the point and the first axis, therefore, the smaller the angle A is, the longer the corresponding force arm is, and the greater the torque of the sleeve 11 acting on the shift pawl 12 is. Therefore, when the mid-mounted transmission performs load shifting, the same shifting requirement with the same force requires smaller force between the sleeve 11 and the shift pawl 12, thereby further reducing the wear degree of the sleeve 11 and the shift pawl 12 during shifting.

[0037] In an embodiment, the shift mechanism 10 further comprises a first fixed shaft 14 located outside the sleeve 11, the first fixed shaft 14 penetrates the shift pawl 12, and the first axis passes through the first fixed shaft 14. For example, the first axis is the central axis of the first fixed shaft 14, and the shift pawl 12 rotates around the fixed shaft 14, thereby improving the stability of the shift pawl 12 during rotation.

[0038] In an embodiment, the shift mechanism 10 further comprises a second fixed shaft 15 located outside the sleeve 11, and the elastic member 13 is installed on the second fixed shaft 15, thereby improving the stability of the elastic member 13, and further improving the reliability of the shifting process.

[0039] In an embodiment, the shift dog 12 further comprises a second inclined surface 122, which is configured to abut against and slide along the edge of the shift groove 111 when the shift dog 12 moves out of the shift groove 111. The angle between the tangent of the helical line of the helical surface around the central axis at the second contact point and the second inclined surface 122 is less than 10 degrees, and the second contact point is the contact point between the second inclined surface 122 and the helical line. Preferably, the angle between the tangent of the helical line of the helical surface around the central axis at the second contact point and the second inclined surface 122 is less than 5 degrees. Specifically, the first inclined surface 121 and the second inclined surface 122 are located at the same end of the shift dog 12. During the relative rotation between the sleeve 11 and the shift dog 12, the first inclined surface 121 abuts against and slides into the shift groove 111 along the edge of the shift groove 111, so that the end of the shift dog 12 enters the shift groove 111, and the gear is engaged. During the continuous relative rotation between the sleeve 11 and the shift dog 12, the second inclined surface 122 abuts against and slides away from the shift groove 111 along the edge of the shift groove 111, so that the end of the shift dog 12 moves out of the shift groove 111, and the gear is disengaged. Therefore, during the engagement and disengagement of the gear, the shift dog 12 and the sleeve 11 can have a large contact area, the local stress of the shift dog 12 and the sleeve 11 is reduced, and the wear of the shift dog 12 and the sleeve 11 is reduced.

[0040] In an embodiment, the sleeve 11 is provided with two shift grooves 111 having the same helical shape, and each shift groove 111 corresponds to a group of shift dogs 12. Each gear 30 corresponds to two shift dogs 12. When the gear is engaged, the two shift dogs 12 simultaneously enter the shift groove 111 at one end and are clamped on the gear 30 at the other end, so that the gear 30 is locked from both ends, and the stability of the transmission after the gear is engaged is improved.

[0041] In an embodiment, the shift mechanism 10 further comprises a driving assembly 16 configured to drive the sleeve 11 to rotate, so that the relative position between the shift groove 111 and the shift dog 12 is changed by rotating the sleeve 11, and the gear position is switched, and the volume of the transmission is reduced.

[0042] In an embodiment, the driving assembly comprises a sliding member, which is arranged in the shift groove 111 and is configured to move along the axial direction of the sleeve 11 to drive the sleeve 11 to rotate. The axial movement of the sliding member is converted into the rotation of the sleeve 11, so that the movement space of the shift mechanism 10 during the gear shifting is further reduced, and the volume of the transmission is further reduced. For example, a driving mechanism configured to drive the sliding member to move along the axial direction can be arranged in the sleeve 11 to drive the sleeve 11 to rotate.

[0043] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A shift mechanism, characterized in that: The gear shifting mechanism comprises a sleeve, a gear shifting pawl and an elastic member, the sleeve is provided with a gear shifting groove, the gear shifting pawl comprises a first slope, the elastic member is arranged at one end of the gear shifting pawl and is used to drive the one end of the gear shifting pawl into the gear shifting groove and to make the other end of the gear shifting pawl be raised when the one end of the gear shifting pawl is above the gear shifting groove, the first slope is used to abut against the edge of the gear shifting groove and slide when the one end of the gear shifting pawl enters the gear shifting groove, the edge of the gear shifting groove is shaped as a helical surface around the central axis of the sleeve, the included angle between the tangent of the helical line around the central axis in the helical surface and the first slope at the first contact point is less than 10 degrees, and the first contact point is the contact point between the first slope and the helical line.

2. The shift mechanism of claim 1, wherein, The elastic member is arranged at one end of the gear shifting pawl and is used to abut against the one end of the gear shifting pawl when the one end of the gear shifting pawl is above the gear shifting groove, so as to drive the one end of the gear shifting pawl to enter the gear shifting groove.

3. The shift mechanism of claim 1, wherein, The elastic member is arranged at the other end of the gear shifting pawl and is used to lift the other end of the gear shifting pawl when the one end of the gear shifting pawl is above the gear shifting groove.

4. The shift mechanism of claim 1, wherein, The included angle between the line connecting the point on the first axis and the first slope and the first slope is less than 60 degrees, and the gear shifting pawl rotates around the first axis.

5. The shift mechanism of claim 4, wherein, The gear shifting mechanism further comprises a first fixed shaft arranged outside the sleeve, the first fixed shaft is arranged through the gear shifting pawl, and the first axis passes through the first fixed shaft.

6. The shift mechanism of claim 1, wherein, The gear shifting pawl further comprises a second slope, the second slope is used to abut against the edge of the gear shifting groove and slide when the gear shifting pawl leaves the gear shifting groove, and the included angle between the tangent of the helical line around the central axis in the helical surface at the second contact point and the second slope is less than 10 degrees, and the second contact point is the contact point between the second slope and the helical line.

7. The shift mechanism of claim 1, wherein, The sleeve is provided with two gear shifting grooves with the same helical shape, and each gear shifting groove corresponds to a group of gear shifting pawls.

8. The shift mechanism according to any one of claims 1 to 7, characterized in that The gear shifting mechanism further comprises a driving assembly used to drive the sleeve to rotate.

9. The shift mechanism of claim 8, wherein, The driving assembly comprises a sliding member arranged through the gear shifting groove and used to move along the axial direction of the sleeve so as to drive the sleeve to rotate.

10. A mid-transmission characterized by, The gear shifting mechanism as claimed in any one of claims 1 to 9. The gear shifting mechanism as claimed in any one of claims 1 to 9.

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