A hub drive structure

Abstract

The application relates to the technical field of transmission devices and discloses a hub driving structure which comprises a half box body, a transparent cover and an NGW type planetary gear train, one end of an inner gear ring is sealingly and fixedly connected with the half box body, the other end is sealingly and fixedly connected with the transparent cover, a total input shaft is rotationally connected to the half box body, the total input shaft transmits power to a sun gear, a planet carrier has an output shaft end, the output shaft end is exposed to the transparent cover and is spline-connected with an inner spline sleeve, the output shaft end is bolt-connected with a hub, the inner spline sleeve and the hub are bolt-connected, a first bearing is sleeved outside the inner gear ring, a wheel core is sleeved outside the first bearing, the wheel core and the hub are bolt-connected, a second bearing is coaxially sleeved with a part extending outward from the hub, the second bearing is installed in a supporting seat, and the supporting seat is connected with the half box body. The application has the advantages of simple and compact structure, formation of a two-end supporting structure, improvement of the stability of the planetary gear train, and reduction of the abrasion between the inner gear ring and the planetary gear.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission devices, and more particularly to a wheel hub drive structure. Background Art

[0002] In relatively closed areas like large factories, construction vehicles like in-plant tractors are often used. To meet the requirements of small, low-speed, heavy-load operation, these vehicles typically use batteries as a power source and utilize a hub drive system. In a hub drive system, the output shaft of a wheel-mounted reducer drives the wheel hub, which in turn drives the tire.

[0003] Prior art hub drive structures typically utilize the inner ring gear of a planetary gear train as the output component to drive the hub. This structure typically involves fitting a tire around the outer circumference of the hub, with the hub and inner ring gear rigidly connected. The force transmission distance between the tire and inner ring gear is very short, and there are few parts between the tire and inner ring gear. As the vehicle moves, shock and vibration experienced by the tire are quickly transmitted to the gear pair formed by the inner ring gear, which also rotates. This can cause significant instability in the entire planetary gear train. Furthermore, the impact and vibration experienced by the rotating inner ring gear can accelerate wear between it and the planetary gears.

[0004] In addition, under the same parameters, compared with using the planetary carrier as the output part, using the inner ring gear as the output part will lead to a lower transmission ratio of the planetary gear system, and using the inner ring gear as the output part will cause the sun gear and the inner ring gear in the same planetary gear system to rotate in opposite directions, that is, the input and output rotation directions of the planetary gear system are opposite. To solve this problem, the existing technology generally adopts a two-stage planetary gear system, and in order to reduce the occupied space and achieve the purpose of miniaturizing engineering vehicles, the two-stage planetary gear system is usually connected with an inner and outer sleeve transmission. This will undoubtedly increase the complexity of the structure and bring great inconvenience to the design work. In addition, for mechanical structures, generally speaking, the more complex the structure, the worse the stability and the more inconvenient the repair and maintenance.

[0005] In existing hub drive structures, the hub is typically the outermost component along the axis of rotation. This means there's no rotational support structure on the outer side of the hub. The hub is rigidly connected to the output end of the planetary gear train, which also lacks rotational support due to space and structural limitations. This creates a one-sided cantilever support structure for the planetary gear train. This structure increases the instability and wear of the planetary gear train's rotating components.

[0006] Existing planetary gear reducers typically use a planetary carrier as the output component, resulting in a design with a solid output shaft. The diameter of the planetary carrier's output shaft is typically small, sufficient to meet strength requirements and facilitate passage through the planetary gear reducer's housing or cover for sealed rotation. It also facilitates transmission connection with the load's input shaft, such as via a coupling. The hub is typically required to be easily removable for replacement, repair, and maintenance. This limits the connection options available between the hub and the planetary carrier's output shaft, typically requiring bolts. The relatively small diameter of the planetary carrier's output shaft accommodates a limited number of bolts, which are typically concentrated near the axis of rotation. This results in high torque on the bolts or the hub near the axis of rotation, which can easily lead to bolt breakage or damage to the hub. Changing the structure of the planetary carrier's output shaft, such as increasing its diameter, would increase the carrier's mass and volume while hindering sealed rotation between the hub and the housing or cover. Summary of the Invention

[0007] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a wheel hub drive structure.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0009] A hub drive structure includes a half housing, a transparent cover and an NGW type planetary gear train, wherein the NGW type planetary gear train includes an inner ring gear, a sun gear, a planet carrier and a plurality of planetary gears, the sun gear and all the planetary gears are externally meshed, and all the planetary gears are internally meshed with the inner ring gear, one end of the inner ring gear is sealed and fixedly connected to the half housing, and the other end of the inner ring gear is sealed and fixedly connected to the transparent cover, the half housing, the inner ring gear and the transparent cover form a reducer cavity, the half housing is rotatably connected to a total input shaft, the total input shaft transmits power to the sun gear through a reduction transmission mechanism, and the planet carrier has an output shaft end The output shaft end of the planetary carrier is exposed on the transparent cover, and the part of the output shaft end of the planetary carrier exposed on the transparent cover is splined with an inner spline sleeve. The end face of the output shaft end of the planetary carrier is fixedly connected to the hub by bolts, and the exposed end face of the inner spline sleeve and the hub are also fixedly connected by bolts. A first bearing is sleeved on the outside of the inner gear ring, and a wheel core is sleeved on the outside of the first bearing. The end face of the wheel core close to the hub and the hub are also fixedly connected by bolts. The part of the hub extending outward along the rotation axis is coaxially sleeved with a second bearing, and the second bearing is installed in the support seat, and the support seat and the half box are fixedly connected.

[0010] The NGW type planetary gear train in this solution is a common type of planetary gear train in the field of speed reducers. Other transparent covers can also be fixed on the half-box to seal and rotate the main input shaft. Rolling bearings and the like will be installed in the half-box to achieve smooth rotation of the main input shaft and other transmission shafts. These are common structures for those skilled in the art, so they are not described in detail in this solution and are omitted. The main input shaft in this solution is usually connected to a motor to provide power. The outer side of the wheel core in this solution is used to fit the tire. The tire is to run close to the ground, so at least part of the tire is exposed on the support seat. This is determined by the use of the hub drive structure. Of course, the wheel core and / or hub can also be partially exposed on the support seat.

[0011] The tire in this solution is fixed on the outside of the wheel core, and there is a first bearing between the wheel core and the inner ring gear, and the inner ring gear is fixed. The wheel hub is used to drive the wheel core to rotate. Although the wheel hub and the planetary carrier are rigidly connected, the force transmission distance between the tire and the planetary carrier is relatively long, and there are usually bearings between the planetary carrier and the planetary gear. The aforementioned bearings all have a certain buffering effect. The action distance between the tire and the gear pair in the planetary gear system is relatively long, and there are many parts between them and there are bearings. Therefore, the impact and vibration borne by the tire are not easily transmitted to the gear pair in the planetary gear system. Compared with the structure with inner ring gear output, this solution is more conducive to improving the stability of the planetary gear system, and can also reduce the wear of the gears in the planetary gear system.

[0012] Under the condition of the same parameters, among various forms of planetary gear trains, this solution can make the planetary gear train produce the maximum transmission ratio. The rotation direction of the sun gear and the planet carrier is the same, that is, the rotation direction of the input and output of the planetary gear train is the same. This makes the design work more convenient. Even the existing model of NGW planetary gear reducer can be directly selected. It only needs to modify the inner ring gear to use it. Therefore, this solution has a simpler structure, better stability, and convenient maintenance.

[0013] This solution incorporates an internal splined sleeve at the output shaft end of the planetary carrier. The planetary carrier's output torque is transmitted to the wheel hub via a splined fit, bolts securing the wheel hub to the output shaft end of the planetary carrier, and bolts securing the wheel hub to the internal splined sleeve. This allows the use of the commonly used planetary carrier output structure in the prior art, facilitating sealed rotation between the planetary carrier's output shaft end and the transparent cover, while also facilitating hub removal. Furthermore, the number of bolts can be increased and their distribution spread widened, improving torque tolerance and making bolts less susceptible to breakage and wheel hub damage.

[0014] More importantly, this solution adds a support structure, namely a support seat, on the outside of the hub's rotation axis direction. A second bearing is installed in the support seat to rotate and support the hub, forming a two-end support structure for the planetary gear train and also for the tire, which can further improve the stability of the planetary gear train and the hub drive structure.

[0015] As the optimized structure form, the sun gear has an input shaft end, a semi-box body, an inner ring gear and a cover forming a reducer cavity, a second rotating shaft and a third rotating shaft are rotatably connected in the reducer cavity, a first bevel gear is arranged on the total input shaft, a second bevel gear and a first cylindrical gear are arranged on the second rotating shaft, the first bevel gear and the second bevel gear are engaged, a second cylindrical gear is arranged on the third rotating shaft, the first cylindrical gear and the second cylindrical gear are engaged, and the third rotating shaft and the input shaft end of the sun gear are in transmission connection. The structure form makes the reduction part of the hub driving structure more compact, and realizes the turning in the limited space, that is, the shaft center of the total input shaft and the rotating shaft center of the hub are perpendicular, the parallel shaft transmission can better control the center distance and the transmission ratio at the design level, especially under the conditions of the given tire inner diameter, rotating speed, center position and the like, the limited space can be reasonably and fully utilized, the design work is facilitated, and the compactness of the structure is ensured.

[0016] As the optimized structure form, the first bearing is a bearing without a bearing inner ring, and the inner ring gear is taken as the bearing inner ring of the first bearing. That is, the first bearing takes the inner ring gear as the bearing inner ring, so that the space occupied by the first bearing in the radial direction can be further reduced, more space is left for the planetary gear train, and the design or selection of the planetary gear train is facilitated.

[0017] Compared with the prior art, the present application has the following beneficial effects: simple and compact structure, the bevel gear transmission, parallel shaft transmission and planetary transmission are integrated in the limited space, the high transmission ratio is realized in the small space, the two-end support structure is formed, the stability of the planetary gear train is improved, the action distance between the tire and the gear pair in the planetary gear train is far, there are more parts and bearings between them, the impact and vibration borne by the tire are not easily transmitted to the gear pair in the planetary gear train, the stability of the planetary gear train is further improved, the wear of the gears in the planetary gear train is reduced, the output shaft end of the planet carrier and the cover are easily sealed and rotated, the hub is easy to disassemble, the number of bolts can be increased and the distribution range of the bolts can be increased, the torque bearing capacity is improved, the bolts are not easy to break, and the hub is not easy to be damaged. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a simple structure schematic diagram of the embodiment of the present application.

[0019] Figure 2 The figure is a partial cross-sectional structure schematic diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0020] The present application will be further described below in combination with the drawings. The drawings are only used for illustrative description, and cannot be understood as limiting the patent.

[0021] To more concisely illustrate this embodiment, certain components well known to those skilled in the art but not relevant to the main content of the present invention may be omitted from the drawings or descriptions. Furthermore, for ease of presentation, certain components may be omitted, enlarged, or reduced in size in the drawings, but do not represent the dimensions or entire structure of the actual product.

[0022] Example:

[0023] like Figure 1 and Figure 2 As shown, a hub drive structure includes a housing half 1, a transparent cover 2, and an NGW-type planetary gear train 3. The NGW-type planetary gear train 3 includes an inner ring gear 31, a sun gear 32, a planet carrier 33, and four planetary gears 34. The sun gear 32 and the four planetary gears 34 are externally meshed with each other, and the four planetary gears 34 are internally meshed with the inner ring gear 31. One end of the inner ring gear 31 is sealed and fixedly connected to the housing half 1, and the other end of the inner ring gear 31 is sealed and fixedly connected to the transparent cover 2. The housing half 1, the inner ring gear 31, and the transparent cover 2 form the reducer cavity.

[0024] The main input shaft 11 is rotatably connected to the housing half 1, and the sun gear 32 has an input shaft end. The secondary and tertiary shafts 12 and 13 are rotatably connected within the reducer cavity formed by the housing half 1, the internal gear ring 31, and the transparent cover 2. A first bevel gear 14 is provided on the main input shaft 11, and a second bevel gear 15 and a first cylindrical gear 16 are coaxially provided on the secondary shaft 12. The first bevel gear 14 and the second bevel gear 15 mesh with each other. A second cylindrical gear 17 is provided on the tertiary shaft 13. The first cylindrical gear 16 and the second cylindrical gear 17 mesh with each other. In practice, the main input shaft 11, the secondary shaft 12, the tertiary shaft 13, and the gears thereon are mostly located within the housing half 1. The tertiary shaft 13 is in transmission connection with the input shaft end of the sun gear 32. In this embodiment, the transmission connection between the tertiary shaft 13 and the input shaft end of the sun gear 32 is achieved via a spline sleeve. In other embodiments, the transmission connection can also be achieved via a coupling or flange. The transmission mechanism between the main input shaft 11 and the sun gear 32 forms a reduction gear mechanism, through which the main input shaft 11 transmits power to the sun gear 32. This structural form makes the reduction gear portion of the hub drive structure more compact and achieves steering within a limited space. Specifically, the axis of the main input shaft 11 and the rotational axis of the wheel hub 44 are perpendicular. The parallel shaft transmission allows for better control of the center distance and transmission ratio at the design level. Especially under given tire inner diameters, rotational speeds, and center positions, it can rationally and fully utilize limited space, facilitate design work, and ensure a compact structure.

[0025] A first bearing 41 is mounted on the outer side of the inner ring gear 31, and a gear core 42 is mounted on the outer side of the first bearing 41. In this embodiment, the first bearing 41 is a bearing without its inner ring, with the inner ring gear 31 serving as the inner ring of the first bearing 41. This means that the inner ring gear 31 takes on the function of the inner ring of the first bearing 41, leaving more space for the planetary gear train and facilitating its design and selection. To ensure that the inner ring gear 31 meets the performance requirements of a bearing inner ring, the outer cylindrical surface of the inner ring gear 31 is typically surface hardened. For example, the outer cylindrical surface of the inner ring gear 31 is quenched to a hardened layer depth greater than 2 mm, achieving a surface hardness of 56-60 HRC or even higher.

[0026] The planet carrier 33 has an output shaft end 331, which is exposed from the transparent cover 2. The portion of the output shaft end 331 of the planet carrier 33 exposed from the transparent cover 2 is splinedly connected to an internal spline sleeve 43. Threaded holes are uniformly distributed axially around the axis of the output shaft end 331 of the planet carrier 33 on the end face. Through holes are arranged on the hub 44 corresponding to the threaded holes on the end face of the output shaft end 331. Bolts are passed through the through holes on the hub 44 and locked into the threaded holes on the end face of the output shaft end 331, thereby fixing the hub 44 and the output shaft end 331 of the planet carrier 33 to each other via bolts.

[0027] The exposed end surface of the internal spline sleeve 43 is provided with axial threaded holes evenly distributed around its axis, and the wheel hub 44 is provided with through holes corresponding to the threaded holes on the internal spline sleeve 43. Bolts are passed through the through holes on the wheel hub 44 and locked into the threaded holes on the internal spline sleeve 43, thereby fixing the wheel hub 44 and the internal spline sleeve 43 together by bolts.

[0028] Axial threaded holes are evenly distributed around the axis of the wheel core 42 on the end face of the wheel core 42 close to the wheel hub 44, and through holes are arranged on the wheel hub 44 corresponding to the threaded holes on the wheel core 42. Bolts are passed through the through holes on the wheel hub 44 and locked into the threaded holes on the wheel core 42, so that the wheel hub 44 and the wheel core 42 are fixedly connected by bolts.

[0029] The wheel hub 44 extends outwardly from a cylindrical boss along the rotation axis, and the cylindrical boss is coaxial with the rotation axis of the wheel hub 44. A second bearing 45 is mounted on the cylindrical boss, that is, the second bearing 45 is coaxial with the rotation axis of the wheel hub 44. The second bearing 45 is installed in the support seat 46, and the support seat 46 and the half box 1 are fixedly connected by bolts.

[0030] In this embodiment, the outer side of the wheel core 42 is used to fit the tire a. Tire a is to be ground-mounted for running, so the support base 46 is designed to be L-shaped. In other embodiments, it can also be designed to be a straddle type, so that the wheel core 42, wheel hub 44, and tire a are partially exposed below the support base 46. In other embodiments, only the tire a can be partially exposed from the support base 46.

[0031] The tire a in this embodiment is fixed to the outside of the wheel core 42, and there is a first bearing 41 between the wheel core 42 and the inner ring gear 31. The inner ring gear 31 is fixed, and the wheel hub 44 is used to drive the wheel core 42 to rotate. Although the wheel hub 44 and the planetary carrier 33 are rigidly connected, the force transmission distance between the tire a and the planetary carrier 33 is relatively long, and there are bearings between the planetary carrier 33 and the planetary gear 34. The aforementioned bearings have a certain buffering effect. Generally speaking, the action distance between the tire a and the gear pair in the planetary gear system is relatively long, and there are many parts between them and there are bearings. Therefore, the impact and vibration borne by the tire a are not easily transmitted to the gear pair in the planetary gear system. Compared with the structure with the output of the inner ring gear, this embodiment is more conducive to improving the stability of the planetary gear system, and can also reduce the wear of the gears in the planetary gear system.

[0032] Under the condition of the same parameters, among various types of planetary gear trains, this embodiment can make the planetary gear train produce the maximum transmission ratio. The rotation directions of the sun gear 32 and the planet carrier 33 are the same, that is, the rotation directions of the input and output of the planetary gear train are the same. This makes the design work more convenient, and even the existing model of NGW planetary gear reducer can be directly selected. It only needs to modify the inner ring gear to use it. Therefore, this embodiment has a simpler structure, better stability, and convenient maintenance.

[0033] In this embodiment, an internal splined sleeve 43 is provided on the output shaft end 331 of the planet carrier 33. The output torque of the planet carrier 33 is transmitted to the hub 44 through a splined fit, bolts securing the hub 44 to the output shaft end 331 of the planet carrier 33, and bolts securing the hub 44 to the internal splined sleeve 43. This not only maintains the commonly used planet carrier output structure in the prior art, facilitating sealed rotation between the output shaft end 331 of the planet carrier 33 and the transparent cover 2, but also facilitates removal of the hub 44. Furthermore, the number of bolts can be increased and their distribution spread is widened, improving torque bearing capacity, making bolts less likely to break, and the hub 44 less susceptible to damage.

[0034] More importantly, this embodiment adds a support structure, namely a support seat 46, on the outside of the rotation axis direction of the hub 44. A second bearing 45 is installed in the support seat 46 to rotate and support the hub 44, forming a two-end support structure for the planetary gear train and also forming a two-end support structure for the tire a, which can further improve the stability of the planetary gear train and the hub drive structure.

[0035] The above is only a specific embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using the design concept of the present invention fall within the scope of protection of the present invention.

Claims

1. A wheel hub drive structure, characterized in that: The NGW planetary gear system includes a half-box, a transparent cover and an NGW planetary gear system, wherein the NGW planetary gear system includes an inner ring gear, a sun gear, a planetary carrier and several planetary gears, the sun gear and all the planetary gears are externally meshed, and all the planetary gears are internally meshed with the inner ring gear, one end of the inner ring gear is sealed and fixedly connected to the half-box, and the other end of the inner ring gear is sealed and fixedly connected to the transparent cover, the half-box, the inner ring gear and the transparent cover form a reducer cavity, the half-box is rotatably connected to the total input shaft, the total input shaft transmits power to the sun gear through the reduction transmission mechanism, the planetary carrier has an output shaft end, the output shaft end of the planetary carrier is exposed to the transparent cover, the part of the output shaft end of the planetary carrier exposed to the transparent cover is splined with an inner spline sleeve, the end face of the output shaft end of the planetary carrier is fixedly connected to the hub by bolts, and the exposed end face of the inner spline sleeve The wheel hub is also fixedly connected by bolts, and a first bearing is mounted on the outside of the inner gear ring, and a wheel core is mounted on the outside of the first bearing. The end face of the wheel core close to the wheel hub is also fixedly connected to the wheel hub by bolts, and the part of the wheel hub extending outward along the rotating axis is coaxially mounted with a second bearing, and the second bearing is installed in the support seat, and the support seat and the half-box are fixedly connected; the sun gear has an input shaft end, and a secondary rotating shaft and a tertiary rotating shaft are rotatably connected in the reducer cavity formed by the half-box, the inner gear ring and the transparent cover, a first bevel gear is provided on the total input shaft, a second bevel gear and a first cylindrical gear are provided on the secondary rotating shaft, the first bevel gear and the second bevel gear are meshed, a second cylindrical gear is provided on the third rotating shaft, the first cylindrical gear and the second cylindrical gear are meshed, and the third rotating shaft and the input shaft end of the sun gear are transmission connected.

2. The wheel hub drive structure according to claim 1, characterized in that: The first bearing is a bearing with its inner ring removed, and the inner gear ring serves as the inner ring of the first bearing.

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