Middle shaft transmission and middle motor

Abstract

The invention belongs to the technical field of transmissions, and particularly relates to a center shaft transmission and a middle motor. A center shaft transmission and a center motor according to the present invention comprise: a center shaft which is rotatably supported by a vehicle frame and from which torque is input; the transmission mechanism comprises a planet carrier fixedly connected with the middle shaft, the torque passes through the planet carrier, and the transmission mechanism has at least two transmission ratios; the gear shifting mechanism is linked with the transmission mechanism and is used for changing the transmission ratio of the transmission mechanism; the driving device is connected with the gear shifting mechanism; the output piece is fixed on the transmission mechanism and outputs the torque; the torque sensor is used for measuring the torque of the planet carrier passing through the transmission mechanism, the torque sensor comprises the force sensitive element, the force sensitive element is integrated, embedded or pasted on the planet carrier, rectangular teeth do not need to be machined on the planet carrier, and the manufacturing cost can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of transmissions, and particularly relates to a mid-axis transmission and a mid-mounted motor. Background Art

[0002] Chinese Patent Document CN117262093A discloses a continuously variable mid-mounted motor. Its mid-axis includes a left half-axis and a right half-axis. The left half-axis is connected to a torque sensor through a first one-way clutch, and the torque sensor is connected to a first planet carrier through rectangular teeth. During operation, the rider pedals the foot pedal to drive the mid-axis to rotate. The left half-axis of the mid-axis transmits power to the torque sensor through the end ratchet teeth of the mid-axis and the ratchet teeth of the torque sensor end (the first one-way clutch), and the power is then transmitted to the first planet carrier. The controller collects signals such as the pedaling torque signal, the pedaling frequency signal, the motor speed, and the generator speed to achieve the purpose of adjusting the speed ratio of the output shaft of the chainring.

[0003] However, realizing the acquisition of the pedaling torque signal requires two independent parts, namely a torque sensor and a first planet carrier. The torque sensor is axially provided with rectangular teeth on its end face and is key-connected to the rectangular teeth on the end face of the first planet carrier. The process of machining the rectangular teeth is complex and the manufacturing cost is relatively high. Therefore, the existing technology needs to be improved and developed. Summary of the Invention

[0004] The purpose of the present application is to provide a mid-axis transmission and a mid-mounted motor, which can reduce the manufacturing cost.

[0005] To solve the above technical problems, a mid-axis transmission provided by the present application includes: A mid-axis, which is rotatably supported on the frame, and torque is input from the mid-axis; A transmission mechanism, which includes a planet carrier connected to the mid-axis, and torque passes through the planet carrier. The transmission mechanism has at least two transmission ratios; A shifting mechanism, which is linked with the transmission mechanism and is used to change the transmission ratio of the transmission mechanism; A driving device, which is connected to the shifting mechanism; An output member, which is connected to the transmission mechanism and outputs torque; A torque sensor, which is used to measure the torque passing through the planet carrier of the transmission mechanism. The torque sensor includes a force-sensitive element, and the force-sensitive element is integrated, embedded or pasted onto the planet carrier.

[0006] Furthermore, at least one of a pedal frequency sensor and a rotation angle sensor is further provided on one side of the torque sensor.

[0007] Further, the planet carrier is a split type, and the planet carrier includes a planet carrier main body and a connecting arm connected to each other, and the force-sensitive element is integrated, embedded or pasted onto the connecting arm.

[0008] Further, the torque sensor further includes a first circuit module connected to the force-sensitive element, and a second circuit module wirelessly connected to the first circuit module, and the first circuit module rotates synchronously with the central shaft.

[0009] Further, the central shaft is hollow, a cable is arranged inside the central shaft, the central shaft is provided with a first hole and a second hole, one end of the cable passes through the first hole and is connected to the force-sensitive element, and the other end of the cable passes through the second hole and is connected to the first circuit module.

[0010] Further, the planet carrier is provided with a third hole, a cable passes through the third hole, and both ends of the cable are respectively connected to the force-sensitive element and the first circuit module.

[0011] Further, the second circuit module is located radially outside the first circuit module.

[0012] Further, the first circuit module and the second circuit module are arranged on one side of the shift mechanism, and the force-sensitive element is arranged on the other side of the shift mechanism.

[0013] Further, the torque sensor further includes a first box body and a second box body, the first box body is fixed to the central shaft, the second box body is fixed to the housing, the first box body and the second box body respectively form a sealed cavity, the first circuit module is arranged inside the first box body, and the second circuit module is arranged inside the second box body.

[0014] Further, the force-sensitive element is a strain gauge.

[0015] Further, the shift mechanism includes at least two pawls, at least two locking members, an elastic member and a rotation control member, the pawls are rotatably mounted on the housing, one end of the elastic member abuts against the housing, the other end of the elastic member abuts against the pawls, a control groove is arranged on the outer peripheral surface of the rotation control member, the pawls are arranged between the locking members and the rotation control member, and the locking members are fixedly connected to the sun gear of the transmission mechanism; When the rotation control member rotates to a specific angle, one end of the pawl falls into the control groove, so that the pawl is locked with the locking member to change the transmission ratio.

[0016] Further, the locking member is of a disc structure, and a locking groove is arranged on the outer peripheral surface of the locking member.

[0017] Further, the locking member and the sun gear are connected by a bushing.

[0018] Further, a rolling bearing is provided between two adjacent bushings.

[0019] Further, the transmission mechanism includes a planetary gear, a sun gear, and a ring gear. The planetary gear is rotatably supported on the planet carrier. The planetary gear is externally meshed with the sun gear, and the ring gear is internally meshed with the planetary gear.

[0020] Further, a first clutch assembly is provided between the planet carrier and the ring gear.

[0021] The present application also provides a mid-mounted motor, which includes the above-mentioned mid-axis transmission and also includes an assist motor. The assist motor is connected to the mid-axis or the transmission mechanism.

[0022] Further, the assist motor is connected to the ring gear of the transmission mechanism, and a second clutch assembly is provided between the assist motor and the ring gear.

[0023] Further, the assist motor is arranged along an axis parallel to the mid-axis.

[0024] Further, the assist motor is connected to the mid-axis or the transmission mechanism by any one of chain drive, belt drive, and gear drive.

[0025] As can be seen from the above, the mid-axis transmission and the mid-mounted motor of the present application include a torque sensor. The torque sensor is used to measure the torque passing through the planet carrier of the transmission mechanism. The torque sensor includes a force-sensitive element, and the force-sensitive element is integrated, embedded, or pasted onto the planet carrier. There is no need to machine rectangular teeth on the planet carrier, which can reduce the manufacturing cost.

[0026] Other features and advantages of the present application will be described in the subsequent specification. And, some of them will become obvious from the specification, or can be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the structures specifically pointed out in the written specification, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a perspective view of the mid-axis transmission.

[0028] Figure 2 is a perspective view of the mid-axis transmission (with the housing, output member, and crank hidden).

[0029] Figure 3 is a perspective view of the mid-axis transmission (with the housing, output member, and crank hidden) from another angle.

[0030] Figure 4It is a structural schematic diagram of a midshaft transmission.

[0031] Figure 5 It is a sectional view of the shifting process of the shifting mechanism.

[0032] Figure 6 It is an isometric view before the assembly of the locking part, bushing and sun gear.

[0033] Figure 7 It is an isometric view after the assembly of the locking part, bushing and sun gear.

[0034] Figure 8 It is an isometric view of the shifting mechanism in the first gear position.

[0035] Figure 9 It is an isometric view of the shifting mechanism in the second gear position.

[0036] Figure 10 It is an isometric view of the shifting mechanism in the third gear position.

[0037] Figure 11 It is an isometric view of the shifting mechanism in the fourth gear position.

[0038] Figure 12 It is a power transmission path diagram of the midshaft transmission in the first gear position.

[0039] Figure 13 It is a power transmission path diagram of the midshaft transmission in the second gear position.

[0040] Figure 14 It is a power transmission path diagram of the midshaft transmission in the third gear position.

[0041] Figure 15 It is a power transmission path diagram of the midshaft transmission in the fourth gear position.

[0042] Figure 16 It is an isometric view of the mid-mounted motor (with the housing, output part and crank removed).

[0043] Figure 17 It is an isometric view of the mid-mounted motor (with the housing, output part and crank removed) from another angle.

[0044] Figure 18 It is a structural schematic diagram of the mid-mounted motor.

[0045] Figure 19 It is an isometric view before the assembly of the midshaft and planet carrier.

[0046] Figure 20 It is an isometric view after the assembly of the midshaft and planet carrier.

[0047] Figure 21 It is an isometric view before the assembly of the midshaft and planet carrier in other embodiments.

[0048] Figure 22 Stereogram of the planet carrier for other embodiments. Reference numerals description: 1 - housing, 2 - central axis, 21 - first hole, 22 - second hole, 3 - input component, 31 - left crank, 32 - right crank, 4 - output member, 5 - transmission mechanism, 51 - planet carrier, 511 - planet carrier body, 5111 - groove, 512 - connecting arm, 513 - third hole, 52 - sun gear, 521 - first sun gear, 522 - second sun gear, 523 - third sun gear, 53 - planet gear, 531 - first planet gear, 532 - second planet gear, 533 - third planet gear, 54 - ring gear, 55 - first clutch assembly, 56 - second clutch assembly, 6 - shifting mechanism, 61 - pawl, 611 - first pawl, 612 - second pawl, 613 - third pawl, 61A - locking portion, 61B - control portion, 61C - rotating shaft portion, 62 - rotation control member, 621 - control groove, 622 - teeth, 63 - locking member, 631 - first locking member, 632 - second locking member, 633 - third locking member, 63A - locking groove, 64 - bushing, 641 - first bushing, 642 - second bushing, 643 - third bushing, 7 - driving device, 8 - first reduction mechanism, 9 - torque sensor, 91 - force - sensitive element, 92 - first circuit module, 93 - second circuit module, 94 - first housing, 95 - second housing, 96 - cable, 10 - assist motor, 11 - second reduction mechanism. Detailed implementation manners

[0049] The following details the implementation manners of the present invention. Examples of the implementation manners are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0050] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0051] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0053] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and in itself does not indicate the relationship between various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0054] Figure 1 It is a perspective view of a mid-axis transmission. Figure 2 It is a perspective view of the mid-axis transmission (with the housing 1, output member 4, and crank removed). Figure 3 It is a perspective view of the mid-axis transmission (with the housing 1, output member 4, and crank removed) from another angle. The mid-axis transmission of the present application is fixedly installed at the bottom in the middle of the vehicle frame. The mid-axis transmission includes a housing 1, a mid-axis 2, a transmission mechanism 5, a shifting mechanism 6, a driving device 7, and an output member 4. The housing 1 is fixed to the vehicle frame. Except for the output member 4 being exposed, other parts are hidden inside the housing 1. Both ends of the mid-axis 2 extend out of the housing 1 and are rotatably supported on the vehicle frame. Both ends of the mid-axis 2 are respectively fixedly connected to an input assembly 3. The input assembly 3 includes a left crank 31 and a right crank 32. The crank is rotatably connected to the pedal. The rider transmits the torque generated by stepping on the pedal to the mid-axis 2, and then the mid-axis 2 inputs it to the transmission mechanism 5. The transmission mechanism 5 is used to adjust the transmission ratio and output speed, and realizes the switching of different gears by changing the meshing relationship of different planetary gears. The output member 4 is fixed on the transmission mechanism 5 and is used to output torque. The output member 4 then inputs the torque to the flywheel through chain drive, belt drive, or shaft drive to drive the rear wheel of the vehicle to rotate.

[0055] This device can be used in vehicles such as bicycles, folding bicycles, Ebikes, electric-assisted bicycles, electric vehicles, electric motorcycles, freight electric vehicles, tricycles, scooters, and electric scooters.

[0056] Planetary gear transmission has a smaller volume and lower height, and can achieve large torque transmission in a limited space, especially suitable for occasions that require high torque and a compact design. Bicycles have high requirements for the space utilization rate of parts. A larger part volume will affect the operability of the rider. Therefore, using a planetary gear mechanism can reduce the overall external dimensions of the mid-axis transmission.

[0057] In this embodiment, the transmission mechanism 5 is a planetary gear mechanism, including a planet carrier 51, planetary gears 53, a sun gear 52, and a ring gear 54. The planetary gears 53 are rotatably supported on the planet carrier 51. The planetary gears 53 are externally meshed with the sun gear 52, and the ring gear 54 is internally meshed with the planetary gears 53. A plurality of planetary gears 53 and sun gears 52 are provided. The more the number, the more gear positions the transmission mechanism 5 has. In order to enable the central shaft transmission to obtain four gear positions, as Figure 4 shown, the transmission mechanism 5 specifically includes a planet carrier 51, a first sun gear 521, a second sun gear 522, a third sun gear 523, a ring gear 54, a first planetary gear 531, a second planetary gear 532, and a third planetary gear 533. The connection relationships and meshing relationships of the parts of the planetary gear mechanism are as follows: The first planetary gear 531, the second planetary gear 532, and the third planetary gear 533 are fixedly connected and rotatably supported on the planet carrier 51. The first sun gear 521, the second sun gear 522, and the third sun gear 523 are all rotatably supported on the central shaft 2, and the planet carrier 51 is fixedly connected to the central shaft 2. The first planetary gear 531 is externally meshed with the first sun gear 521, the second planetary gear 532 is externally meshed with the second sun gear 522, the third planetary gear 533 is externally meshed with the third sun gear 523, the ring gear 54 is internally meshed with the third planetary gear 533, and the ring gear 54 is fixedly connected to the output member 4.

[0058] A first clutch assembly 55 is provided between the planet carrier 51 and the ring gear 54. The first clutch assembly 55 is configured to engage when the rotational speed of the ring gear 54 is lower than or equal to the rotational speed of the planet carrier 51, so that the ring gear 54 rotates synchronously with the planet carrier 51, and to disengage when the rotational speed of the ring gear 54 is higher than the rotational speed of the planet carrier 51, and the planet carrier 51 does not rotate following the ring gear 54. The first clutch assembly 55 can adopt a roller clutch, a wedge clutch, a ratchet clutch, a friction clutch, an electromagnetic clutch, etc.

[0059] In order to achieve gear shifting, it is realized by locking or releasing the sun gear 52 of the planetary gear mechanism through the shifting mechanism 6. As Figure 5 shown, the shifting mechanism 6 includes at least two pawls 61, at least two rotation control members 62, an elastic member (not shown), and a locking member 63. The rotation control member 62 has a cylindrical structure, a control groove 621 is provided on the outer peripheral surface, and a locking member 63 is installed inside. The locking member 63 has a disc-shaped structure, a locking groove 63A is provided on the outer peripheral surface of the locking member 63, a pawl 61 is installed between the locking member 63 and the rotation control member 62, and the pawl 61 is rotatably installed on the housing 1.

[0060] Specifically, each pawl 61 has a locking portion 61A, a control portion 61B, and a rotating shaft portion 61C. The rotating shaft portion 61C is a circular through hole, which is sleeved on the rotating shaft so that the pawl 61 can rotate around the shaft. Both the control portion 61B and the locking portion 61A of the pawl 61 protrude along the thickness direction of the pawl 61. The control portion 61B is located on the opposite side of the locking portion 61A. The locking portion 61A is used to lock or release with the locking groove 63A of the locking member 63.

[0061] By arranging an elastic member on the rotating shaft, the control portion 61B of the pawl 61 can be kept in contact with the inner wall of the rotation control member 62. The elastic member can be a torsion spring. One end of the torsion spring abuts against one end of the pawl 61, and the other end of the torsion spring abuts against the housing 1. The torsion spring applies a torque towards the rotation control member 62 to the pawl 61.

[0062] In order to realize the rotation of the rotation control member 62, in this embodiment, an electric shift mechanism is adopted for driving. The electric shift mechanism includes a driving device 7. The driving device 7 is an encoder motor. The encoder motor can obtain information such as the position, speed, and angle of the motor movement in real time through the encoder, and has high measurement accuracy and accuracy, and is suitable for application scenarios with high precision requirements for position, speed, and angle, etc.

[0063] The output end of the driving device 7 is connected with a first reduction mechanism 8. The first reduction mechanism 8 can be a multi-stage gear reducer. Through the first reduction mechanism 8, the rotation speed of the driving device 7 is reduced and the torque is increased, which is convenient for overcoming the resistance of the pawl 61 to drive the rotation control member 62 to rotate. Gear teeth 622 are also arranged on the outer peripheral surface of the rotation control member 62. The first reduction mechanism 8 meshes with the gear teeth 622 of the rotation control member 62 to realize transmission.

[0064] It should be noted that in addition to the electric shift mechanism, a manual shift mechanism can also be adopted to drive the rotation control member 62 to shift gears.

[0065] Since there are three sun gears 52, there are also three pawls 61, which respectively include a first pawl 611, a second pawl 612, and a third pawl 613. The first pawl 611 is close to the output member 4, and the third pawl 613 is far from the output member 4. The first pawl 611, the second pawl 612, and the third pawl 613 are arranged staggered in the circumferential direction. When the rotation control member 62 rotates to a certain angle, only one end of a pawl 61 falls into the control groove 621 and bounces up, and the other pawls 61 all remain retracted.

[0066] The number of the locking members 63 corresponds to the number of the sun gears 52. There are also three locking members 63, which respectively include a first locking member 631, a second locking member 632 and a third locking member 633. The outer diameters of the first locking member 631, the second locking member 632 and the third locking member 633 are the same, and the inner diameters decrease in sequence.

[0067] The locking member 63 is fixedly connected to the sun gear 52 of the transmission mechanism 5. For the convenience of part assembly, as Figure 6 and Figure 7 shown, a bushing 64 is arranged between the locking member 63 and the sun gear 52. The bushing 64 is a hollow shaft part, and its number corresponds to that of the locking member 63. The bushing 64 specifically includes a first bushing 641, a second bushing 642 and a third bushing 643. The lengths of the first bushing 641, the second bushing 642 and the third bushing 643 increase in sequence, and the outer diameters decrease in sequence. The three bushings 64 can rotate relative to each other, and rolling bearings can be arranged between two adjacent bushings 64 to reduce the rolling resistance and ensure the load-carrying capacity.

[0068] The bushing 64 can be integrally formed with the sun gear 52 or the locking member 63. In this embodiment, the bushing 64 is integrally formed with the sun gear 52, which can ensure the strength of the sun gear 52. The bushing 64 and the locking member 63 are fixed by a spline connection method, that is, a spline groove is arranged on the inner side of the locking member 63, and a spline is arranged at the end of the bushing 64, and the two are assembled with each other. The bushing 64 and the locking member 63 can also be fixed by other methods, such as square hole connection, threaded connection, etc.

[0069] The assembly process of the three bushings 64 and the three locking members 63 is as follows: Step 1: Sleeve the second bushing 642 on the third bushing 643 and install a rolling bearing, and sleeve the first bushing 641 on the second bushing 642 and install a rolling bearing; Step 2: Assemble the first locking member 631 to the first bushing 641, assemble the second locking member 632 to the second bushing 642, and assemble the third locking member 633 to the third bushing 643. Through this assembly method, the compactness of the structure can be ensured. The rolling bearing can be a needle bearing with a compact radial structure.

[0070] The state of the shifting mechanism 6 during the shifting process is as follows: In the initial position, the shifting mechanism 6 is in the first gear position. As Figure 8 shown, the first pawl 611, the second pawl 612 and the third pawl 613 do not fall into the control groove 621; the driving device 7 drives the first reduction mechanism 8 to drive the rotation control member 62 of the shifting mechanism 6 to rotate counterclockwise, and the shifting mechanism 6 is in the second gear position. As Figure 9As shown, the first pawl 611 and the second pawl 612 do not fall into the control groove 621, and only the third pawl 613 falls into the control groove 621; the rotation control member 62 continues to rotate counterclockwise by a certain angle, and the shift mechanism 6 is in the third gear position, as Figure 10 shown, the first pawl 611 and the third pawl 613 do not fall into the control groove 621, and only the second pawl 612 falls into the control groove 621; the rotation control member 62 continues to rotate counterclockwise by a certain angle, and the shift mechanism 6 is in the fourth gear position, as Figure 11 shown, the second pawl 612 and the third pawl 613 do not fall into the control groove 621, and only the first pawl 611 falls into the control groove 621. The above process is the upshift process, and for the downshift process, the rotation control member 62 rotates in the reverse direction.

[0071] Figures 12 - 15 In , the rectangular frame of the first clutch assembly 55 in

[0072] is blackened to indicate the engaged state, and vice versa for the disengaged state; the rectangular frame of the pawl 61 is blackened to indicate the locked state, and vice versa for the released state.

[0072] Figure 12 shows the power transmission path diagram of the first gear position of the center shaft transmission.

[0073] As shown in the figure, the shift mechanism 6 does not lock the sun gear 52, and the first sun gear 521, the second sun gear 522, and the third sun gear 523 can all rotate. The rotational speeds of the planet carrier 51 and the ring gear 54 are the same. The first clutch assembly 55 is engaged, and the torque sequentially passes through the center shaft 2, the planet carrier 51, the first clutch assembly 55, the ring gear 54, and the output member 4. At this time, the transmission ratio of the transmission mechanism 5 is 1.

[0074] Figure 13 shows the power transmission path diagram of the second gear position of the center shaft transmission.

[0075] As shown in the figure, the shift mechanism 6 only locks the third sun gear 523. The first sun gear 521 and the second sun gear 522 can both rotate. The planet carrier 51 is the driving member, the first sun gear 521 is fixed, and the ring gear 54 is the driven member. At this time, it is a speed-increasing transmission, and the transmission ratio is less than 1. The rotational speed of the ring gear 54 is higher than that of the planet carrier 51, and the first clutch assembly 55 is disengaged. The torque sequentially passes through the center shaft 2, the planet carrier 51, the third planet gear 533, the third sun gear 523, the ring gear 54, and the output member 4.

[0076] Figure 14 shows the power transmission path diagram of the third gear position of the center shaft transmission.

[0077] As shown in the figure, the shift mechanism 6 only locks the second sun gear 522. The first sun gear 521 and the third sun gear 523 can both rotate. The planet carrier 51 is active, the second sun gear 522 is fixed, and the ring gear 54 is driven. At this time, it is a speed-increasing transmission. The transmission ratio of the third gear is less than that of the second gear. The rotational speed of the ring gear 54 is higher than that of the planet carrier 51, and the first clutch assembly 55 is disengaged. The torque sequentially passes through the middle shaft 2, the planet carrier 51, the second planet gear 532, the second sun gear 522, the third planet gear 533, the ring gear 54, and the output member 4.

[0078] Figure 15 The power transmission path diagram of the fourth gear of the middle shaft transmission is shown.

[0079] As shown in the figure, the shift mechanism 6 only locks the first sun gear 521. The second sun gear 522 and the third sun gear 523 can both rotate. The planet carrier 51 is active, the first sun gear 521 is fixed, and the ring gear 54 is driven. At this time, it is a speed-increasing transmission. The transmission ratio of the fourth gear is less than that of the third gear. The rotational speed of the ring gear 54 is higher than that of the planet carrier 51, and the first clutch assembly 55 is disengaged. The torque sequentially passes through the middle shaft 2, the planet carrier 51, the first planet gear 531, the first sun gear 521, the third planet gear 533, the ring gear 54, and the output member 4.

[0080] As can be seen from the above, the torque of each gear will pass through the planet carrier 51 every time. Therefore, a force-sensitive element 91 of the torque sensor 9 can be set at the planet carrier 51 to collect and measure the torque generated by the rider's pedaling. The obtained torque can be applied to statistical rider data or to optimize the shifting method.

[0081] The torque sensor 9 includes a force-sensitive element 91. The force-sensitive element 91 is a sensor element that can sense and respond to external force changes and can convert mechanical forces (such as pressure, tension, pressure difference, etc.) into electrical signals. The force-sensitive element 91 includes strain gauges, piezoelectric sensors, piezoresistive sensors, force-sensitive resistors, capacitive sensors, etc. In this embodiment, the force-sensitive element 91 is selected as a strain gauge. The strain gauge has high precision, small volume, and low cost, and can be pasted on or embedded in the planet carrier 51. Compared with the prior art, it can reduce the manufacturing cost.

[0082] In other embodiments, the force-sensitive element 91 can be integrated on the planet carrier 51. The integration can be prepared by a photolithography process. The specific steps include: Step 1: Form a first insulating layer at the position of the planet carrier 51 where the force-sensitive element 91 is to be integrated. The first insulating layer can be formed by a process of coating green oil; Step 2: Form a substrate. Drop the substrate material glue on the surface of the planet carrier 51 and let it dry naturally and cure.

[0083] Step 3: Form a metal foil layer on the substrate. Press a thin metal layer on the substrate by lamination.

[0084] Step 4: Form a sensitive grid layer. Convert the metal film layer into a sensitive grid layer by photolithography and etching; Step 5: Form a second insulating layer on the surface of the sensitive grid layer. Similar to Step 1, it can be formed by the process of coating green oil.

[0085] As the force-sensitive element 91 is pasted on the planet carrier 51, with the increase of the service time, the bonding material ages, and situations such as warping and falling off may occur. However, by integrating it on the planet carrier 51 through the photolithography process, no bonding material is required, and the integrity is higher, while the detection accuracy is also higher.

[0086] When the torque passes through the planet carrier 51, the sensitive grid of the strain gauge will generate a small deformation, thereby causing a change in its resistance value. In order to obtain the resistance value change and supply power to the force-sensitive element 91, the torque sensor 9 further includes a first circuit module 92 connected to the force-sensitive element 91, and a second circuit module 93 wirelessly connected to the first circuit module 92. The second circuit module 93 is used to wirelessly supply power to the first circuit module 92, and the first circuit module 92 is used to wirelessly transmit data to the first circuit module 92. The structures of the first circuit module 92 and the second circuit module 93 are the same as those in the patent application CN202422083293.6 of the applicant, and will not be elaborated here. The first circuit module 92 and the second circuit module 93 are respectively installed in a first box body 94 and a second box body 95 with a sealed cavity. Both the first box body 94 and the second box body 95 are circular plastic box bodies. Among them, the second box body 95 is fixed on the housing 1 and remains stationary, and the first circuit module 92 and the first box body 94 are fixed on the outer peripheral surface of the central axis 2 and rotate with the central axis 2. A gap allowing relative rotation between the two is left between the first box body 94 and the second box body 95, and the first box body 94 and the second box body 95 serve to isolate the lubricating fluid of the transmission mechanism 5.

[0087] Since both the sun gear 52 and the ring gear 54 on both sides of the planet carrier 51 are rotating parts and there is no fixed position to place the first circuit module 92 and the second circuit module 93, therefore, as Figure 4As shown in the figure, the first circuit module 92 and the second circuit module 93 are arranged at the left end of the central axis 2, which is convenient for assembly and maintenance. The second circuit module 93 is located radially outside the first circuit module 92, and the radial space of the central axis 2 can be utilized to avoid excessive axial width. The first circuit module 92 is connected to the force-sensitive element 91 through a cable 96. Therefore, the central axis 2 is set to be hollow, and the cable 96 is arranged inside the central axis 2 and fixed to the inner wall of the central axis 2 by using a buckle or glue, without occupying the space outside the central axis 2, and the structure is more compact. The central axis 2 is provided with a first hole 21 on the side close to the planet carrier 51 and a second hole 22 on the side close to the first box body 94. One end of the cable 96 passes through the first hole 21 and is connected to the force-sensitive element 91, and the other end of the cable 96 passes through the second hole 22 and is connected to the first circuit module 92.

[0088] After the torque sensor 9 is assembled, the first circuit module 92 and the second circuit module 93 are arranged on one side of the shift mechanism 6, and the force-sensitive element 91 is arranged on the other side of the shift mechanism 6. The middle part of the central axis 2 directly supports the third shaft sleeve 643, the second shaft sleeve 642 and the first shaft sleeve 641, the structure is more reasonable, the force on the central axis 2 is more uniform, and the space utilization rate is higher.

[0089] When applied to counting rider data or optimizing the shifting method, in addition to torque data, there are also cadence, crank angle, etc. Therefore, at least one of a cadence sensor and a rotation angle sensor can be arranged on one side of the torque sensor 9 to improve the integration of electronic components. The cadence sensor can be realized by installing a magnet in the first box body 94 and a Hall sensor in the second box body 95. When the magnet passes by the Hall sensor, the Hall sensor will detect the change of the magnetic field and generate a voltage pulse. By counting these pulses, the rotation speed of the crank can be calculated, and then the cadence can be calculated. The rotation angle sensor can be realized by installing another magnet in the first box body 94 and a magnetic rotary encoder in the second box body 95. When the magnet rotates, the magnetic rotary encoder detects the change of the magnetic field and converts it into an electrical signal. By analyzing these signals, the rotation angle can be calculated.

[0090] Figure 19 It is a three-dimensional view before the assembly of the central axis 2 and the planet carrier 51. Figure 20 It is a three-dimensional view after the assembly of the central axis 2 and the planet carrier 51. As shown in the figure, the central axis 2 is provided with splines, and the planet carrier 51 is provided with spline grooves. The two cooperate with each other to fixedly connect the central axis 2 and the planet carrier 51.

[0091] In other embodiments, such as Figure 21As shown, the planet carrier 51 is split-type. The planet carrier 51 includes a planet carrier main body 511 and connecting arms 512 that are connected to each other. The connecting arms 512 are four cantilever arms. The planet carrier main body 511 is provided with a groove 5111. The four cantilever arms of the connecting arms 512 are snapped into the groove 5111 of the planet carrier main body 511 to achieve connection. The planet carrier main body 511 and the connecting arms 512 can be made of different materials. The split-type planet carrier 51 is beneficial to reducing the manufacturing cost. The force-sensitive element 91 is embedded or pasted onto the connecting arms 512.

[0092] In other embodiments, as Figure 22 shown, the cable 96 can pass through the planet carrier 51. The planet carrier 51 is provided with a third hole 513. The cable 96 passes through the third hole 513. The two ends of the cable 96 are respectively connected to the force-sensitive element 91 and the first circuit module 92.

[0093] The present application also provides a mid-drive motor, including the above-mentioned mid-axis transmission, so that the mid-drive motor has both a shifting function and an electric assist function. As Figures 16 - 18 shown, the difference from the mid-axis transmission is that an assist motor 10 and a second reduction mechanism 11 are added. The assist motor 10 can be connected to the mid-axis 2 or the transmission mechanism 5. The connection method can be any one of chain drive, belt drive, and gear drive. In this embodiment, the assist motor 10 is connected to the transmission mechanism 5 by gear drive. Specifically, the axis of the output shaft of the assist motor 10 is parallel to the axis of the mid-axis 2. The parallel arrangement has a simple structure and is easy to assemble and maintain. The assist motor 10 can be directly connected to the transmission mechanism 5 or connected to the gear ring 54 of the transmission mechanism 5 through the second reduction mechanism 11. The second reduction mechanism 11 can be a planetary gear reduction mechanism.

[0094] A second clutch assembly 56 is provided between the assist motor 10 and the gear ring 54. The assist motor 10 is connected to the second reduction mechanism 11. The second clutch assembly 56 can be arranged between the second reduction mechanism 11 and the gear ring 54. The second clutch assembly 56 is configured to engage when the rotational speed of the gear ring 54 is lower than or equal to the rotational speed of the second reduction mechanism 11, so that the gear ring 54 rotates synchronously with the second reduction mechanism 11, and disengage when the rotational speed of the gear ring 54 is higher than the rotational speed of the second reduction mechanism 11, and the second reduction mechanism 11 does not rotate following the gear ring 54. The function of the second clutch assembly 56 is that when the battery power supply for the assist motor 10 is exhausted, the assist motor 10 does not work, the rotational speed of the second reduction mechanism 11 is zero, the second clutch assembly 56 disengages, and the rider's pedaling only drives the transmission mechanism 5 to rotate without driving the assist motor 10 and the second reduction mechanism 11 to rotate, reducing the riding resistance.

[0095] When the assisting motor 10 is working, in addition to the torque generated by the rider's pedaling, there is also the torque generated by the assisting motor 10. After the two torques are superimposed, they are output to the output member 4, enabling the rider to obtain a higher riding speed or a longer riding distance in a labor-saving riding manner.

[0096] For a mid-mounted motor with a shifting function, compared with a rear-mounted motor (hub motor) with a shifting function, since the speed-changing structure is not on the rear wheel but on the frame, when impacted on a rough road surface, the impact will not be directly transmitted to the hub through the rim and spokes, but also needs to pass through the frame. The frame has a certain role in absorbing vibrations, greatly reducing the impact force. Relatively speaking, it is not easily affected by external forces and is not easily bumped, making the mid-mounted motor more durable.

[0097] The weight of the rear-mounted motor is concentrated on the rear wheel, which is not conducive to the vehicle's takeoff and jumping. While the weight of the mid-mounted motor is concentrated at a position below the center of gravity of the frame, which has a relatively small impact on the balance of the whole vehicle and can greatly improve the handling performance.

[0098] The vehicle equipped with a mid-mounted transmission also has a speed feedback device. For example, by adding a GPS chip to obtain positioning information and calculating to obtain the vehicle speed. In the automatic mode, the rider does not need to perform any operations, and the mid-mounted transmission performs shifting operations according to the vehicle speed. For example, when the vehicle speed reaches ten kilometers per hour, it automatically shifts from the first gear to the second gear; and when the vehicle speed drops below ten kilometers per hour, it automatically shifts from the second gear to the first gear. The rider can either switch to the manual mode to freely change gears according to the actual road conditions to improve the riding flexibility, or switch to the free mode to automatically change gears to improve the riding comfort.

[0099] In the description of this specification, the description with reference to terms such as "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0100] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A mid-shaft transmission, characterized in that: include: A middle shaft (2), the middle shaft (2) being rotatably supported on the frame, and the torque being input from the middle shaft (2); A transmission mechanism (5), the transmission mechanism (5) comprising a planet carrier (51) connected to the central shaft (2), the torque passing through the planet carrier (51), the transmission mechanism (5) having at least two transmission ratios; A gear shift mechanism (6) is linked with the transmission mechanism (5) and is used to change the transmission ratio of the transmission mechanism (5); A driving device (7) connected to the gear shifting mechanism (6); An output member (4) is connected to the transmission mechanism (5) to output torque; A torque sensor (9) is used to measure the torque of the planet carrier (51) passing through the transmission mechanism (5), wherein the torque sensor (9) comprises a force-sensitive element (91), wherein the force-sensitive element (91) is integrated, embedded or adhered to the planet carrier (51).

2. The mid-shaft transmission according to claim 1, characterized in that: At least one of a cadence sensor and a rotation angle sensor is also arranged on one side of the torque sensor (9).

3. The mid-shaft transmission according to claim 1, characterized in that: The planet carrier (51) is of a split type, and comprises a planet carrier body (511) and a connecting arm (512) which are connected to each other, and the force sensitive element (91) is integrated, embedded or adhered to the connecting arm (512).

4. The mid-shaft transmission according to claim 1, characterized in that: The torque sensor (9) further comprises a first circuit module (92) connected to the force sensitive element (91), and a second circuit module (93) wirelessly connected to the first circuit module (92), wherein the first circuit module (92) rotates synchronously with the central axis (2).

5. The mid-shaft transmission according to claim 4, characterized in that: The central axis (2) is hollow, a cable (96) is arranged inside the central axis (2), and the central axis (2) is provided with a first hole (21) and a second hole (22), one end of the cable (96) passes through the first hole (21) to be connected to the force sensitive element (91), and the other end of the cable (96) passes through the second hole (22) to be connected to the first circuit module (92).

6. The mid-shaft transmission according to claim 4, characterized in that: The planet carrier (51) is provided with a third hole (513), a cable (96) is passed through the third hole (513), and two ends of the cable (96) are respectively connected to the force sensitive element (91) and the first circuit module (92).

7. The mid-shaft transmission according to claim 4, characterized in that: The second circuit module (93) is located radially outside the first circuit module (92).

8. The mid-shaft transmission according to claim 4, characterized in that: The first circuit module (92) and the second circuit module (93) are arranged on one side of the gear shift mechanism (6), and the force sensitive element (91) is arranged on the other side of the gear shift mechanism (6).

9. The mid-shaft transmission according to claim 4, characterized in that: The torque sensor (9) further comprises a first box body (94) and a second box body (95), wherein the first box body (94) is fixed to the central axis (2), and the second box body (95) is fixed to the housing (1), and the first box body (94) and the second box body (95) respectively form a sealed cavity, and the first circuit module (92) is arranged in the first box body (94), and the second circuit module (93) is arranged in the second box body (95).

10. The mid-shaft transmission according to claim 1, characterized in that: The force sensitive element (91) is a strain gauge.

11. The mid-shaft transmission according to claim 1, characterized in that: The shift mechanism (6) comprises at least two ratchets (61), at least two locking members (63), an elastic member and a rotation control member (62); the ratchets (61) are rotatably mounted on the housing (1); one end of the elastic member abuts against the housing (1); the other end of the elastic member abuts against the ratchets (61); a control groove (621) is provided on the outer peripheral surface of the rotation control member (62); the ratchets (61) are arranged between the locking members (63) and the rotation control member (62); and the locking members (63) are fixedly connected to the sun gear (52) of the transmission mechanism (5); When the rotating control member (62) rotates to a specific angle, one end of the ratchet (61) falls into the control groove (621), so that the ratchet (61) is locked with the locking member (63) to change the transmission ratio.

12. The mid-shaft transmission according to claim 11, characterized in that: The locking member (63) is a disc structure, and a locking groove (63A) is provided on the outer peripheral surface of the locking member (63).

13. The mid-shaft transmission according to claim 11, characterized in that: The locking member (63) is connected to the sun gear (52) via a shaft sleeve (64).

14. The mid-shaft transmission according to claim 13, characterized in that: A rolling bearing is arranged between two adjacent shaft sleeves (64).

15. The mid-shaft transmission according to claim 1, characterized in that: The transmission mechanism (5) comprises a planetary gear (53), a sun gear (52) and a ring gear (54); the planetary gear (53) is rotatably supported on the planet carrier (51); the planetary gear (53) is externally meshed with the sun gear (52); and the ring gear (54) is internally meshed with the planetary gear (53).

16. The mid-shaft transmission according to claim 15, characterized in that: A first clutch assembly (55) is arranged between the planet carrier (51) and the ring gear (54).

17. A mid-mounted motor, comprising the mid-shaft transmission according to any one of claims 1 to 16, characterized in that: It also comprises a booster motor (10), wherein the booster motor (10) is connected to the central shaft (2) or the transmission mechanism (5).

18. The mid-mounted motor according to claim 17, characterized in that: The booster motor (10) is connected to the gear ring (54) of the transmission mechanism (5), and a second clutch assembly (56) is provided between the booster motor (10) and the gear ring (54).

19. The mid-mounted motor according to claim 17, characterized in that: The booster motor (10) and the central axis (2) are arranged with axes parallel to each other.

20. The mid-mounted motor according to claim 17, characterized in that: The power-assisting motor (10) is connected to the central shaft (2) or the transmission mechanism (5) via any one of chain drive, belt drive and gear drive.

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