High power density planetary traction drive

Abstract

This invention discloses a high-power-density planetary traction drive. A loading wedge space and a balancing space are formed on both sides of the radial distance circumference between the planetary rollers and the outer ring. A loading roller is located within the wedge-shaped loading space and rolls in contact with the planetary rollers and the outer ring. A balancing idler wheel is provided in the balancing space. The planetary rollers, balancing idler wheel, and loading rollers are all floating, with the loading rollers abutting against the planetary carrier. The torque or counter-torque transmitted by this invention can directly act on the loading rollers, achieving adaptive loading and making the loading process faster and more flexible. Optimization of the load in the contact area also improves the service life of the traction drive. The superposition of contact forces generates a larger clamping force, thereby ensuring sufficient tangential force in each contact area to transmit power. Furthermore, the planetary traction drive provided by this invention can achieve high-load transmission under the load-sharing effect of multiple rollers. The zero-spin design based on cylindrical rollers also minimizes power loss, resulting in high power density and improved transmission accuracy and efficiency.

Description

Technical Field

[0001] This invention relates to the field of traction planetary transmissions, specifically a high power density planetary traction drive. Background Technology

[0002] With the trend of electrification and the development of new motor technologies, the trend towards higher-speed motors is becoming increasingly apparent. Maximizing the efficiency of energy-consuming equipment and improving motor drive systems hold immense potential for energy conservation. Compared to traditional motors, high-speed motors, combined with compact and efficient mechanical transmission devices, can achieve miniaturization, weight reduction, and high power density in power systems, lowering costs and reducing the motor's dependence on rare earth resources, thus showing broad prospects. However, in the high-speed, heavy-load field, traditional gear transmissions pose significant challenges to manufacturing costs, gear fatigue life, and NVH suppression, presenting new boundaries and constraints for electrification development. Traction drives, on the other hand, utilize the shear force of oil film between adjacent components or the frictional force generated by direct contact to transmit power.

[0003] Since the rollers do not make direct contact with each other under high-speed conditions, traction drives have certain inherent advantages over gears, including high efficiency, zero backlash, low vibration, small angular velocity fluctuation, simple design and manufacturing, and great potential for high and ultra-high speeds. Furthermore, they can solve the NVH problem of high-speed gear transmission in principle, and therefore are expected to become an ideal choice for more new demands and applications.

[0004] Therefore, patent CN111868413A (Ultimate Transmissions) discloses a planetary traction scheme that adopts a loading roller structure. Two loading rollers are symmetrically distributed on both sides of each planetary roller, which can realize bidirectional transmission. The planetary carrier contacts the bearings on both sides of the planetary roller. During operation, the tangential force at the contact point between the planetary roller and the outer ring causes the loading roller to enter the wedge-shaped space, thereby wedging and loading. However, this structure still does not change the structure of the planetary roller transmitting load. The wedging process of the loading roller is not directly coupled with the load, and the passive wedging loading also reduces the responsiveness of the system. It is not direct or flexible in its adaptation to speed, load, and load.

[0005] Therefore, in order to meet the requirements of high-speed heavy-duty drives, a planetary traction drive is needed that can achieve high efficiency, high load, zero spin transmission, and direct and flexible adaptability of the loading roller wedging process relative to the load. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to overcome the defects in the existing design and provide a high power density planetary traction drive that can achieve high efficiency, high load, zero spin transmission, and the wedging process of the loading roller can be directly and flexibly adaptive relative to the load.

[0007] The high power density planetary traction drive of the present invention includes a sun gear, an outer ring, a planet carrier, and planetary rollers evenly distributed circumferentially between the sun gear and the outer ring; the planetary rollers are in rolling contact with the sun gear and have a radial distance between them and the outer ring, thereby forming a loading wedge space and a balance space on both sides of the radial distance circumferential direction between the planetary rollers and the outer ring, respectively.

[0008] It also includes a loading mechanism, which includes a loading roller located within a wedge-shaped loading space and in rolling contact with the planetary roller and the outer ring, the loading roller being provided with an initial preload toward the radial pitch;

[0009] The balancing space is equipped with a balancing idler wheel, which makes rolling contact with the planetary rollers and the outer ring.

[0010] The planetary rollers, balancing idler wheels, and loading rollers are all floating, and the loading rollers abut against the planetary carrier in the circumferential direction in a direction away from the radial distance.

[0011] Furthermore, the loading wedge space and balancing space of adjacent planetary rollers are set in opposite directions.

[0012] Furthermore, the planetary carrier rotates coaxially with the outer ring, and the loading roller abuts against the planetary carrier in the circumferential direction in a direction opposite to the radial distance.

[0013] Furthermore, the loading mechanism also includes a preload application component;

[0014] The preload application assembly is fixed to or directly formed on the planetary carrier and applies the preload to the loading roller, which abuts against the planetary carrier in the circumferential direction away from the radial spacing via the preload application assembly.

[0015] Furthermore, one of the aforementioned balancing idler wheels simultaneously rolls into contact with two adjacent planetary rollers.

[0016] Furthermore, the preload application assembly includes a fixing part fixed to the planet carrier or directly formed on the planet carrier and a preload part that applies the preload to the loading roller based on the fixing part;

[0017] The loading rollers sequentially pass through the preload and fixing parts and abut against the planetary carrier in the circumferential direction in a direction away from the radial distance.

[0018] Furthermore, the pre-tightening part is a pre-tightening roller;

[0019] The preload roller can be adjusted to move radially based on the fixed part, and rolls into contact with the two loading rollers of the adjacent planetary rollers respectively, thereby applying the preload force to the loading rollers of the adjacent planetary rollers;

[0020] Alternatively, the loading rollers of adjacent planetary rollers may each roll into contact with a preload roller, and the two preload rollers may be adjusted based on a fixed part to apply the preload force to the corresponding loading roller in the circumferential direction.

[0021] Furthermore, the preload part is a threaded pair, a beveled pair, or an interference fit structure, which acts on the two loading rollers of the adjacent planetary rollers at both ends in the circumferential direction, thereby applying the preload force;

[0022] Alternatively, the preload application component may be a floating threaded pair, inclined pair, interference fit structure, or spring, which acts on the two loading rollers of the adjacent planetary rollers at both ends in the circumferential direction, thereby applying the preload to the loading rollers of the adjacent planetary rollers respectively.

[0023] Furthermore, the sun gear and the outer ring are coaxial;

[0024] Alternatively, the sun gear and the outer ring are eccentrically positioned, and the diameters of the planetary rollers differ to accommodate the eccentric structure between the sun gear and the outer ring.

[0025] Furthermore, the planetary rollers are a single-layer planetary roller structure arranged along the circumference;

[0026] Alternatively, the planetary rollers are in multiple groups, and the multiple groups of planetary rollers are arranged to form a multi-layered planetary roller structure along the radial direction. Rolling contact is formed between different groups of planetary rollers, and the balancing idler wheel and the loading roller are located between the outermost planetary roller group and the outer ring.

[0027] Alternatively, the planetary rollers can be an axial stepped structure and consist of multiple groups. The multiple groups of planetary rollers are arranged to form a radial multi-layer planetary roller structure. The minor and major diameters of the planetary rollers in different groups form rolling contact in the radial direction. The balancing idler wheel and the loading roller are located between the planetary rollers of the outermost planetary roller group and the outer ring.

[0028] The beneficial effects of this invention are as follows: The high-power-density planetary traction drive of this invention has a loading roller between the outer ring and the planetary rollers. The loading roller transmits torque or counter-torque, which acts directly on the loading roller. This causes the loading roller to actively wedge under the combined action of the tangential force at the contact point between the planetary rollers and the outer ring, and the contact force at the inner wall of the planetary carrier slot. This generates a clamping force related to the load, achieving adaptive loading and making the loading process faster and more flexible. The optimization of the load in the contact area can also improve the service life of the traction drive. The superposition of the contact forces can generate a larger clamping force, thereby enabling each contact area to generate sufficient tangential force to transmit power. In addition, the planetary traction drive provided by this invention can achieve high-load transmission under the load-sharing effect of multiple rollers.

[0029] In this invention, each planetary gear contacts only one loading roller. The size of the loading roller is not limited by the other loading roller, allowing for a larger loading roller diameter, which greatly improves load-bearing capacity and service life, while also enabling adaptive loading. Furthermore, the planetary traction drive provided by this invention, while meeting high-load transmission requirements, also minimizes power loss and improves transmission accuracy and efficiency through its zero-spin design.

[0030] This invention enables high-efficiency, high-load, zero-spin transmission. While meeting the high load requirements, zero spin also minimizes power loss, resulting in high power density, improved transmission accuracy and efficiency, and reduced vibration and assembly precision requirements. The contact area adopts a line contact method, which reduces contact stress compared to point contact and significantly improves the load-bearing capacity of the reducer. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] Figure 1 This is a schematic diagram of the structure of the present invention;

[0033] Figure 2 This is a cross-sectional structural diagram of the present invention (the pre-tightening part adopts an interference fit structure);

[0034] Figure 3 This is a schematic diagram of a structure where the preload is tightened by interference fit.

[0035] Figure 4 This is a schematic diagram of a structure where the preload is a spring;

[0036] Figure 5 This is a schematic diagram of a pre-tightening section with an inclined surface substructure.

[0037] Figure 6 This is a schematic diagram of a threaded joint structure for the preload section; Detailed Implementation

[0038] As shown in the figure, the high power density planetary traction drive of this embodiment includes a sun gear 1, an outer ring 7, a planet carrier, and planetary rollers 2 evenly distributed circumferentially between the sun gear 1 and the outer ring 7; the planetary rollers 2 are in rolling contact with the sun gear 1 and have a radial distance between them and the outer ring 7, thereby forming a loading wedge space and a balance space on both sides of the radial distance circumferential direction between the planetary rollers and the outer ring.

[0039] It also includes a loading mechanism, which includes a loading roller 3 located within a wedge-shaped loading space and in rolling contact with the planetary roller 2 and the outer ring 7, the loading roller 3 being provided with an initial preload toward the radial spacing;

[0040] The balance space is provided with a balance idler wheel 4, which is in rolling contact with the planetary roller 2 and the outer ring 7.

[0041] The planetary roller 2, the balance idler wheel 4, and the loading roller 3 are all floating, and the loading roller 3 abuts against the planet carrier in the circumferential direction in a direction away from the radial distance.

[0042] In this structure, "mutual resistance" refers to the fact that the two components are restricted in their degrees of freedom in that direction, which will not be elaborated further here. As shown in the figure, the direction away from the radial distance refers to the side of the loading roller 3 that is far from the radial distance in the circumferential direction, which will not be elaborated further here. In this structure, when the outer ring 7 is relatively fixed and the power is transmitted from the loading roller to the planetary carrier, the load on the planetary carrier acts directly on the loading roller (the planetary carrier is fixed, and the load principle of the outer ring is the same), avoiding the problem of the loading roller not directly responding to the load in patent CN111868413A. The initial preload can be an elastic element. The preload pressure formed can also be the initial preload directly formed, causing the loading roller 3 to move towards the radial distance; of course, the structure of the present invention has the general properties of planetary transmission, that is, during transmission, when the planet carrier 5 is fixed, the power is input by the sun gear 1 connected to the input shaft and drives the planetary roller 2, and the power is transmitted to the outer ring 7 through the rolling of the loading roller 3 to form rotational output power; when the outer ring 7 is fixed, the power drives the planetary roller 2 through the sun gear 1, the loading roller 3 rotates and revolves, and drives the planet carrier 5 to rotate and output power through the loading roller 3;

[0043] Floating refers to an installation state where, apart from necessary driving rolling and load transmission, there are no special restrictions on degrees of freedom. For example, planetary roller 2 is simply positioned between the sun gear, the balance idler gear 4, and the loading roller, without any other installation restrictions. The balance idler gear 4 is simply positioned between planetary roller 2 and the outer ring 7, without any other installation restrictions. The loading roller 3 is simply positioned in rolling contact between the planetary roller and the outer ring, and is subjected to an initial preload to counteract the planetary carrier in a set direction, without any other installation restrictions. All of these are considered floating installations. The loading roller is simply positioned in contact with the planetary roller. The load roller is positioned between the planetary rollers and the outer ring. Apart from being subjected to an initial preload and needing to drive the planetary carrier to rotate, there are no other installation restrictions. Rolling refers to rotating around its own axis while potentially revolving around the planetary carrier, which will not be elaborated here. In addition, unless otherwise specified, the circumferential direction of this invention refers to the circumferential direction of the outer ring, which will not be elaborated here. The way in which the load rollers abut against the planetary carrier can limit the load rollers in the driven direction during installation, thus driving the planetary carrier when it is driven to revolve around the planetary rollers or driving the outer ring when the planetary carrier is fixed, which will not be elaborated here.

[0044] like Figure 1 As shown, the sun gear 1, planetary rollers 2, and outer ring 7 form a traction planetary transmission gear system, arranged in the existing planetary transmission structure, which will not be described in detail here. A loading roller 3 is set between the planetary rollers 2 and the outer ring 7, that is, the loading roller participates in the formation of the planetary traction transmission gear system. The planetary rollers 2 are evenly distributed along the circumference, contacting the sun gear 1 and the loading rollers 3 and realizing their rotation and revolution. The loading rollers 3 are limited by the loading mechanism to move within a wedge-shaped space formed by the planetary rollers 2 and the outer ring 7, and simultaneously contact the planetary rollers 2 and the outer ring 7, thereby forming different contact normal forces under different loads. The balancing idler wheel 4 is located on the other side of the planetary rollers 2 opposite to the loading rollers 3, and is used to balance the component of the normal force of the loading rollers 3 along the circumference, maintaining the stable operation of the planetary rollers, thereby ensuring the smooth and stable operation of the entire motion system.

[0045] The sun gear 1, planetary rollers 2, balancing idler gear 4, and loading roller 3 are all designed with axial limits to prevent axial movement. Furthermore, the planetary rollers 2, balancing idler gear 4, and loading roller 3 are all floating, thereby achieving uniform loading across all contact areas. In this embodiment, the sun gear 1 and outer ring 4 are coaxial and rotate freely around the central axis. During operation, the loading roller 3 wedges into the convergent gap between the planetary rollers 2 and outer ring 4 to generate a suitable normal load, thereby ensuring sufficient tangential force in each contact area to transmit power.

[0046] In the above structure, rolling contact pairs are formed between the sun gear 1 and the planetary roller 2, between the planetary roller 2 and the loading roller 3, and between the loading roller 3 and the outer ring 7. The rolling contact pairs can be formed by direct contact between adjacent components to form a friction transmission fit, or by adding traction oil so that adjacent components form a traction transmission fit through oil film shear force. The loading roller 3 is interference-fitted through a loading mechanism to generate the initial positive pressure required for start-up or low load. When the load increases, the loading roller 3 wedges into the wedge space to automatically adjust the contact pressure, ensuring that a suitable and sufficient clamping force can be generated in the contact area during transmission to prevent slippage, thereby improving transmission efficiency and service life.

[0047] In this embodiment, the loading wedge space and the balance space of adjacent planetary rollers 2 are set in opposite directions. In this structure, since the loading wedge space of adjacent planetary rollers is in opposite directions, the driver can perform bidirectional transmission to meet different transmission requirements; that is, the loading roller of one planetary roller is used for forward transmission, and the loading roller of the other planetary roller is used for reverse transmission, forming forward and reverse loading transmission.

[0048] In this embodiment, the planetary carrier and the outer ring 7 are coaxially rotated together, and the loading roller 3 abuts against the planetary carrier in the circumferential direction in a direction away from the radial distance. In this structure, the loading roller is set on the planetary carrier through a loading roller shaft and transmits power to the planetary carrier, thereby pushing the planetary carrier to rotate (or abutting, generally through a bearing to reduce friction) in the selected transmission direction. That is, the loading roller shaft is floatingly set on the planetary carrier, and the planetary carrier directly loads to form the preload (the planetary carrier forms a mounting groove, and the groove wall directly applies the preload), and drives the planetary carrier in the transmission direction. Alternatively, a dedicated loading mechanism can be used, but the loading mechanism needs to be fixedly set on the planetary carrier, thereby transmitting power to the planetary carrier to overcome the preload and form a power transmission chain.

[0049] The planetary carrier is generally rotatably engaged with the outer ring via bearings, and the outer ring is fixed to the drive housing. This is a typical mechanical structure and will not be described in detail here. As shown in the figure, the planetary carrier includes a left end plate 8a and a right end plate 8. The left end plate 8a and the right end plate 8 are respectively rotatably engaged with the outer ring 7 via bearings. The planetary roller 3, the balance idler wheel 4, and the loading roller 3 are floating between the left end plate 8a and the right end plate 8. Of course, the floating setting of the loading roller 3 is different, and it needs to abut against the left end plate 8a and the right end plate 8 in a direction away from the wedge-shaped space.

[0050] For the present invention, it can be used as a speed reduction transmission, a speed increase transmission, and can also form a differential transmission in a power system. These rotational states can be used in mechanical transmission systems.

[0051] Of course, the planet carrier can also be fixed, with power input or output from the sun gear or the outer ring; that is, the outer ring can remain stationary while the sun gear 1 and the planet carrier 5 rotate; or the planet carrier 5 can remain stationary while the sun gear 1 and the outer ring 4 rotate; or the sun gear 1, the outer ring 7, and the planet carrier can all rotate; these will not be elaborated further here.

[0052] When using a power distribution strategy in the design, these rotational states can be coupled with other gear trains or transmissions to have additional sub-states.

[0053] In this embodiment, the loading mechanism further includes a preload application component;

[0054] The preload application component is fixed to the planet carrier or directly formed on the planet carrier and applies the preload to the loading roller. The loading roller 3 abuts against the planet carrier in the circumferential direction in a direction away from the radial distance through the preload application component, that is, it transmits power to the planet carrier. Alternatively, the planet carrier is fixed and the power is input or output by the sun gear or the outer ring.

[0055] The preload application assembly is any mechanical structure capable of applying the preload to the loading roller. When the loading roller transmits load between the planetary carrier and the planetary carrier, the preload application assembly should be fixed on the planetary carrier to apply the preload to the loading roller and participate in the load transmission.

[0056] In this embodiment, one of the balancing idler wheels simultaneously rolls in contact with the adjacent planetary rollers, resulting in a relatively simple structure. As shown in the figure, a balancing idler wheel 4 with a set diameter is placed between two planetary rollers 2, making rolling contact with both of them, thereby balancing the two planetary rollers simultaneously. In bidirectional transmission, it can simultaneously balance the two loading rollers.

[0057] In this embodiment, the preload application component includes a fixing part fixed to the planetary carrier or directly formed on the planetary carrier, and a preload part that applies the preload to the loading roller based on the fixing part. The fixing part is the part fixed to the planetary carrier and serves as the basis for transmitting the load (planetary carrier or outer ring). The preload part is located on the fixing part and can be any mechanical structure that can apply the preload to the loading roller by pressing against it, such as an elastic layer, spring, or interference fit structure. The fixing part can be integrally formed on the planetary carrier, for example, by opening a groove on the planetary carrier and using the side wall of the groove (the side wall is the preload part, and the back can be regarded as the fixing part) to apply the preload to the loading roller shaft and transmit it to the loading roller 3. This will not be elaborated further here. The fixing part can also be a mechanical structure that is fixed to the planetary carrier by mechanical means. This will not be elaborated further here.

[0058] The loading roller 3 abuts against the planetary carrier in the circumferential direction away from the radial distance via the pre-tightening part and the fixing part in sequence, that is, the power is transmitted to the planetary carrier; or, the planetary carrier is fixed and the power is input or output by the sun gear or the outer ring.

[0059] In this embodiment, the pre-tightening part is a pre-tightening roller 5;

[0060] The preload roller 5 is adjustable and moves radially based on the fixed part 6, rolling into contact with the two loading rollers 3 of the adjacent planetary rollers 2, thereby applying the preload force to the loading rollers 3 of the adjacent planetary rollers 2. As shown in the figure, the fixed part 6 is fixed to the planetary carrier and is not structurally limited. The preload roller 5 is rotatably mounted on the fixed part 6 via a preload roller shaft. The preload roller shaft is mounted on the fixed part via an adjustable mechanical structure, such as a screw threaded to the fixed part. The end of the screw is connected to the preload roller shaft (the two are rotatably fitted). By rotating the screw, the preload roller is driven to reciprocate radially, thereby realizing the reciprocating movement of the preload roller 5. The preload force is applied and adjusted by using the preload roller to contact the loading rollers at different positions in the radial direction. In this invention, unless otherwise specified, radial refers to the radial direction of the driver, with the radial direction of the outer ring as the reference.

[0061] Alternatively, the loading rollers 3 of adjacent planetary rollers 2 can roll into contact with a preload roller. The two preload rollers, based on a fixed part, can be adjusted circumferentially to apply the preload force to the corresponding loading roller. As shown in the figure, the length of the preload part in the circumferential direction is adjustable. For example, two screws can extend to both sides in the circumferential direction and drive a preload roller shaft and a preload roller respectively to apply the preload force to the corresponding loading roller. Of course, the screws need to be mounted on a mounting base to achieve the technical effect of the loading roller abutting against the planetary carrier, which will not be elaborated here.

[0062] Of course, in addition to the aforementioned preload roller structure, the preload part can also be a threaded pair, a beveled pair, or an interference fit structure, acting on the two loading rollers 3 of the adjacent planetary rollers at both ends in the circumferential direction, thereby applying the preload force; such as Figure 6 As shown, the moving end of the threaded pair 5d can directly act on the loading roller shaft to apply the preload force to the loading roller. Simultaneously, the threaded pair, including the screw and the clamping parts at both ends, can be adjusted by the threaded engagement of the clamping parts with the screw; this will not be elaborated further. Of course, the screw needs to be fixed to the planetary carrier; the fixing method can use existing mechanical structures, which will not be elaborated further. Similarly, as... Figure 5As shown, the inclined plane pair 5c consists of two wedge-shaped blocks with inclined surfaces. The inclined surfaces of the two wedge-shaped blocks engage, and changing their relative engagement position alters the overall length. External force drives the two wedge-shaped blocks to move laterally, applying the preload force, thus achieving preload force application at different positions. The position between the wedge-shaped blocks can be achieved through a reciprocating mechanical structure (such as a screw, with a mounting base fixed on a planetary carrier, the screw threaded into the mounting base, and the reciprocating movement of the screw relative to the mounting base applying or releasing pressure to the wedge-shaped blocks, thereby changing the engagement position) that applies pressure laterally (towards the inclined surface). Figure 3 As shown, interference structure 5a refers to directly utilizing a block with interference to act on the loading roller shafts at both ends. For example, the ends of the block have an elastic structure, such as a hard spring or hard rubber, to form the preload force, which will not be elaborated further here; of course, there are also... Figure 4 The structure shown is that the spring 5b applies a preload. The spring is a hard spring and is fixed to the planetary carrier. The transmission function is achieved by the hard springs resisting each other. This will not be described in detail here. Figures 1 to 6 Various structures of the present invention are illustrated herein, and are all schematic diagrams used only to illustrate the structural principles, and do not represent the actual structures. Those skilled in the art can clearly understand the general structure of rotational fit and the use of bearings and other structures to reduce friction based on the schematic diagrams and textual descriptions, combined with existing mechanical principles, and will not be elaborated here.

[0063] In this embodiment, the sun gear 1 and the outer ring 4 are coaxial; this is a general structure of planetary transmission.

[0064] Alternatively, the sun gear and the outer ring may be eccentrically positioned, and the diameters of the planetary rollers may differ to accommodate the eccentric structure between the sun gear and the outer ring; this will not be elaborated further here.

[0065] In this embodiment, the planetary rollers are a single-layer planetary roller structure arranged along the circumference.

[0066] Alternatively, the planetary rollers can be in multiple sets, arranged to form a multi-layered planetary roller structure along the radial direction. Different sets of planetary rollers form rolling contact in the radial direction. The loading roller is located between the outermost planetary roller set and the outer ring, as shown in the figure, between the planetary roller of the outermost planetary roller set and the outer ring, which will not be elaborated further here. The arrangement of multiple sets of planetary rollers is beneficial for fitting the transmission ratio as needed and for improving the load capacity.

[0067] Alternatively, the planetary rollers can have a stepped structure and be in multiple sets; the planetary rollers can be axially stepped and in multiple sets, with multiple sets of planetary rollers arranged to form a radially multi-layered planetary roller structure. The minor and major diameters of different sets of planetary rollers form a rolling contact in the radial direction. The loading roller is located between the planetary rollers of the outermost planetary roller set and the outer ring. In the designed stepped structure, the planetary rollers of different sets can be mutually restrained axially; for example, two sets of planetary rollers can be used, where the first set of planetary rollers is located radially inner and rolls in contact with the sun gear, and the second set of planetary rollers is located radially outer and rolls in contact with the loading roller 3. The two sets of planetary rollers form a rolling contact, and the second set... The first set of planetary rollers has an annular groove structure with a central annular depression, while the second set of planetary rollers has an annular protrusion in the center and annular necks at both ends. The annular protrusion makes rolling contact with the annular groove of the second set of planetary rollers, while the annular necks at both ends make rolling contact with the groove edge of the annular groove of the second set of planetary rollers. The planetary rollers with stepped shaft structures of different diameters cooperate with each other. After rolling cooperation of different diameters, sliding friction may occur, but the mutual support makes the structure more stable. The groove and protrusion cooperation structure can ensure the stability of the axial structure, while ensuring the compactness of the radial structure, thereby increasing the load capacity and achieving the effect of increasing the transmission ratio. It has good flexibility in installation and use.

[0068] In this embodiment, the sun gear 1 is typically mounted in the mounting holes of the left end plate 8a and the right end plate 8 forming the planetary carrier via bearings, and rotates around its own axis. A sealing ring is provided between the sun gear 1 and the mounting holes of the left end plate 8a and the right end plate 8, with an appropriate gap. The left end plate 8a and the right end plate 8 are fastened to other components of the planetary carrier (or the left end plate 8a and the right end plate 8 are directly bolted together to form the planetary carrier) by bolts. Other mounting structures used in this structure, such as those mounted on the housing, are conventional mechanical structure settings and will not be described in detail here.

[0069] This planetary traction drive is a miniaturized, high-speed, lightweight, and integrated drive solution with advantages such as high speed ratio, high rigidity, high efficiency, zero spin, high load capacity, and high-precision transmission. It is suitable for high-speed power transmission, especially in the electric vehicle field. Thanks to the high-speed and smooth performance of the traction drive, a high-speed motor can be used to reduce motor size and increase system power density, thereby achieving miniaturized electrical design. Furthermore, this drive does not require complex specialized machining equipment; the simple shapes of the parts and their self-centering properties make it insensitive to installation errors, resulting in good manufacturability, low cost, high product consistency, and relatively simple engineering implementation, facilitating mass production on assembly lines.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high power density planetary traction drive characterized by: It includes a sun gear, an outer ring, a planet carrier, and planetary rollers evenly distributed circumferentially between the sun gear and the outer ring; the planetary rollers are in rolling contact with the sun gear and have a radial distance between them and the outer ring, thereby forming a loading wedge space and a balance space on both sides of the radial distance circumferential direction between the planetary rollers and the outer ring, respectively. It also includes a loading mechanism, which includes a loading roller located within a wedge-shaped loading space and in rolling contact with the planetary roller and the outer ring, the loading roller being provided with an initial preload toward the radial pitch; The balancing space is equipped with a balancing idler wheel, which makes rolling contact with the planetary rollers and the outer ring. The planetary rollers, balancing idler wheels, and loading rollers are all floating, and the loading rollers abut against the planetary carrier in the circumferential direction in a direction away from the radial distance.

2. The high power density planetary traction drive according to claim 1, characterized in that: The loading wedge space and balancing space of the adjacent planetary rollers are set in opposite directions.

3. The high power density planetary traction drive according to claim 1, characterized in that: The planetary carrier rotates coaxially with the outer ring, and the loading roller abuts against the planetary carrier in the circumferential direction in a direction away from the radial distance.

4. The high power density planetary traction drive according to claim 3, characterized in that: The loading mechanism also includes a preload application component; The preload application assembly is fixed to or directly formed on the planetary carrier and applies the preload to the loading roller, which abuts against the planetary carrier in the circumferential direction away from the radial spacing via the preload application assembly.

5. The high power density planetary traction drive according to claim 3, characterized in that: One of the balancing idler wheels is in rolling contact with two adjacent planetary rollers simultaneously.

6. The high power density planetary traction drive according to claim 4, characterized in that: The preload application assembly includes a fixing part fixed to the planet carrier or directly formed on the planet carrier and a preload part that applies the preload to the loading roller based on the fixing part; The loading rollers sequentially pass through the preload and fixing parts and abut against the planetary carrier in the circumferential direction in a direction away from the radial distance.

7. The high power density planetary traction drive according to claim 6, characterized in that: The pre-tightening part is a pre-tightening roller; The preload roller can be adjusted to move radially based on the fixed part, and rolls into contact with the two loading rollers of the adjacent planetary rollers respectively, thereby applying the preload force to the loading rollers of the adjacent planetary rollers; Alternatively, the loading rollers of adjacent planetary rollers may each roll into contact with a preload roller, and the two preload rollers may be adjusted based on a fixed part to apply the preload force to the corresponding loading roller in the circumferential direction.

8. The high power density planetary traction drive according to claim 6, characterized in that: The preload part is a threaded pair, a beveled pair, or an interference fit structure, which acts on the two loading rollers of the adjacent planetary rollers at both ends in the circumferential direction, thereby applying the preload force. Alternatively, the preload application component may be a floating threaded pair, inclined pair, interference fit structure, or spring, which acts on the two loading rollers of the adjacent planetary rollers at both ends in the circumferential direction, thereby applying the preload to the loading rollers of the adjacent planetary rollers respectively.

9. The high power density planetary traction drive according to claim 1, characterized in that: The sun gear is coaxial with the outer ring; Alternatively, the sun gear and the outer ring are eccentrically positioned, and the diameters of the planetary rollers differ to accommodate the eccentric structure between the sun gear and the outer ring.

10. The high power density planetary traction drive according to claim 1, characterized in that: The planetary rollers are a single-layer planetary roller structure arranged along the circumference. Alternatively, the planetary rollers are in multiple groups, and the multiple groups of planetary rollers are arranged to form a multi-layered planetary roller structure along the radial direction. Rolling contact is formed between different groups of planetary rollers, and the balancing idler wheel and the loading roller are located between the outermost planetary roller group and the outer ring. Alternatively, the planetary rollers may have an axial stepped structure and be in multiple groups. The multiple groups of planetary rollers are arranged to form a multi-layered planetary roller structure along the radial direction. The minor and major diameters of the planetary rollers in different groups form rolling contact in the radial direction. The balancing idler wheel and the loading roller are located between the planetary rollers of the outermost planetary roller group and the outer ring.

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