WO2017050158A1

WO2017050158A1 - Differential, power transmission system and vehicle

Info

Publication number: WO2017050158A1
Application number: PCT/CN2016/098895
Authority: WO
Inventors: Heping Ling; Zhen ZHAI; Feng Zheng; Youbin XU
Original assignee: Byd Company Limited
Priority date: 2015-09-25
Filing date: 2016-09-13
Publication date: 2017-03-30
Also published as: CN106555845A; CN106555845B

Abstract

A differential (100), a power transmission system and a vehicle are provided. The differential includes a first planetary carrier (11); a first gear ring (13); a first planetary gear (12) disposed on the first planetary carrier, and meshed with the first gear ring; a second planetary carrier (21); a second gear ring (23); and a second planetary gear (22) disposed on the second planetary carrier and meshed with the second gear ring as well as the first planetary gear, in which the first gear ring and the second gear ring are configured as two power output ends of the differential, the first planetary carrier and the second planetary carrier are configured as power input ends of the differential.

Description

DIFFERENTIAL, POWER TRANSMISSION SYSTEM AND VEHICLE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefits of Chinese Patent Application No. 201510623387.0, filed with the State Intellectual Property Office of P.R. China on September 25, 2015. The entire content of the above-identified applications is incorporated herein by reference.

FIELD

Embodiments of the present disclosure relates to a differential, a power transmission system having the differential, and a vehicle having the power transmission system.

BACKGROUND

In a differential technology, a differential includes a driven gear of a final drive, a planetary gear, a center gear, and the like. The planetary gear is mounted on a secondary plate of the driven gear through a square shaft and a shaft sleeve and is meshed with the center gear, so as to implement revolution and moving functions thereof by a turning pair and a planar sliding pair. The center gear is connected to two half shafts, namely left and right half shafts, through an angular alignment pin and a cylindrical pair or through a spline to achieve an objective of outputting torque. Original components, such as left and right housings and a planetary gear shaft of the differential, are omitted from such a differential, and instead, the planetary gear is directly mounted on the secondary plate of the driven gear of the final drive by using the square shaft and the shaft sleeve, thereby effectively reducing a number of parts of the differential, simplifying the structure thereof, and reducing the weight thereof.

However, such a differential implements an inter-wheel speed differential by using a symmetrical angle gear structure, which is only a partial innovation for a conventional symmetrical angle gear differential and cannot really overcome disadvantages thereof. For example, an axial dimension of the differential structure is excessively large, masses of the housing andthe angle gear therein are heavy, and reliability thereof is relatively poor.

SUMMARY

Embodiments of the present disclosure aims at solving at least one of the foregoing technical problems in the prior art to some extent.

Therefore, embodiments of the present disclosure provide a differential, which implements a speed differential function by using a planetary differential principle, has a compact and simple structure, and can at least reduce an axial dimension thereof.

Embodiments of the present disclosure further provide a power transmission system having the differential acording to above embodiments of the present dislcosure.

Embodiments of the present disclosure further provide a vehicle having the power transmission system acording to above embodiments of the present dislcosure.

A differential according to an embodiment of the present disclosure includes: a first planetary carrier； a first gear ring； a first planetary gear disposed on the first planetary carrier, and meshed with the first gear ring； a second planetary carrier； a second gear ring； and a second planetary gear disposed on the second planetary carrier and meshed with the second gear ring as well as the first planetary gear, in which the first gear ring and the second gear ring are configured as two power output ends of the differential, the first planetary carrier and the second planetary carrier are configured as power input ends of the differential.

The differential according to embodiments of the present disclosure implements a speed differential function by using a planetary differential principle, has a high space utilization ratio in terms of structure and connection form, provides a small axial dimension, and also have much advantages in production and assembly.

A power transmission system according to embodiments of the present disclosure includes the differential according to the foregoing embodiments.

A vehicle according to embodiments of the present disclosure includes the power transmission system according to the foregoing embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the drawings, in which:

FIG. 1 is an exploded view of a differential according to an embodiment of the present disclosure from a perspective；

FIG. 2 is a front view of a differential according to an embodiment of the present disclosure；

FIG. 3 is a planar schematic diagram showing a principle of a differential according to an embodiment of the present disclosure；

FIG. 4 is a partial perspective view of a differential according to an embodiment of the present disclosure, in which a first gear ring and a first plantery carrier are not shown；

FIG. 5 is a partial front view of a differential according to an embodiment of the present disclosure, which mainly shows a first plantery carrier and a first plantery gear as well as a second plantery carrier and a second plantery gear；

FIG. 6 is a schematic view illustrating a meshing principle between a first planetary gear and a second planetary gear according to an embodiment of the present disclosure；

FIG. 7 is a brief diagram illustrating a meshing principle between a first planetary gear and a second planetary gear according to an embodiment of the present disclosure；

FIG. 8 is a schematic view of a first gear ring or a second gear ring according to another embodiment of the present disclosure；

FIG. 9 is a schematic view of a first gear ring or a second gear ring according to still another embodiment of the present disclosure；

FIG. 10 is a schematic diagram of a power transmission system according to an embodiment of the present disclosure； and

FIG. 11 is a schematic diagram of a vehicle according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present disclosure. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions.

In the description of the present disclosure, it should be understood that, location or position relationships indicated by the terms, such as "center" , "longitude" , "transverse" , "length" , "width" , "thickness" , "up" , "down" , "front" , "rear" , "left" , "right" , "vertical" , "horizon" , "top" , "bottom" , "inside" , "outside" , "clockwise" , and "counterclockwise" , are location or position relationships based on illustration of the accompanying drawings, are merely used for describing the present disclosure and simplifying the description instead of indicating or implying the indicated apparatuses or elements should have specified locations or be constructed and operated according to specified locations, and therefore, should not be intercepted as limitations to the present disclosure.

In addition, the terms such as "first" and "second" are used merely for the purpose of description, but shall not be construed as indicating or implying relative importance or implicitly indicating a number of the indicated technical feature. Hence, the feature defined with "first" and "second" may explicitly or implicitly include one or more of features. In the description of the present disclosure, unless otherwise explicitly specifically defined, "a plurality of" means at least two, for example, two or three.

In the present disclosure, unless otherwise explicitly specified or defined, the terms such as "mount" , "connect" , "connection" , and "fix" should be interpreted in a broad sense. For example, a connection may be a fixed connection, or may be a detachable connection or an integral connection； a connection may be a mechanical connection, or may be an electrical connection； a connection may be a mechanical connection, or may be an electrical connection, or may be used for intercommunication； a connection may be a direct connection, or may be an indirect connection via an intermediate medium, or may be communication between interiors of two elements or an interaction relationship between two elements. It may be appreciated by those of ordinary skill in the art that the specific meanings of the aforementioned terms in the present disclosure can be understood depending on specific situations.

In the present disclosure, unless otherwise explicitly specified or defined, a first feature being "above" or "under" a second feature may include that the first and second features are in direct contact and may also include that the first and second features are not in direct contact but are in contact by means of another feature therebetween. In addition, the first feature being "over" , "above" or "on the top of" a second feature may include that the first feature is over or above the second feature or merely indicates that the horizontal height of the firs feature is higher than that of the second feature. The first feature being "underneath" , "below" or "on the bottom of" a second feature may include that the first feature is underneath or below the second feature or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

A differential 100 according to an embodiment of the present disclosure is described in detail by referring to FIG. 1 to FIG. 11, the differential 100 may be used for an inter-wheel speed differential or an inter-shaft speed differential. Taking the inter-wheel speed differential as an example, the differential 100 can enable left and right driving wheels to roll at different angular velocities when a vehicle is turning or traveling on an uneven road, so as to ensure pure rolling movements between the driving wheels on two sides and the ground.

As shown in FIG. 1, the differential 100 according to some embodiments of the present disclosure may include a first planetary carrier 11, a first planetary gear 12, and a first gear ring 13 as well as a second planetary carrier 21, a second planetary gear 22, and a second gear ring 23.

With reference to embodiments of FIG. 1 and FIG. 5, both the first planetary carrier 11 and the second planetary carrier 21 can be configured as circular plate-shaped structures, so as to reduce an axial dimension of the differential 100 to some extent. In some embodiments, the first planetary carrier 11 and the second planetary carrier 21 may be configured as separated structures, i.e., the first planetary carrier 11 and the second planetary carrier 21 are separated from each other. Because it is relatively easy to mold an individual small component, so separately and individually machining the first planetary carrier 11 and the second planetary carrier 21 can simplify a corresponding manufacturing process and improve machining precision thereof.

As shown in FIG. 1, FIG. 3 and FIG. 5 in combination with FIG. 6-FIG. 7, the first planetary gear 12 is disposed on the first planetary carrier 11. For example, each first planetary gear 12 is provided with a first planetary gear shaft 14, two ends of the first planetary gear shaft 14 may be rotatably carried on the first planetary carrier 11 and the second planetary carrier 21 respectively. In an embodiment, the two ends of the first planetary gear shaft 14 may be rotatably carried in shaft holes corresponding to each other in the first planetary carrier 11 and the second planetary carrier 21 by means of bearings, and the first planetary gear 12 may be fixed to the corresponding first planetary gear shaft 14. In some embodiments, the two ends of the first planetary gear shaft 14 may be fixedly connected to the first planetary carrier 11 and the second planetary carrier 22. For example, the two ends of the first planetary gear shaft 14 are respectively welded and fixed to the shaft holes corresponding to each other in the first planetary carrier 11 and the second planetary carrier 22, and the first planetary gear 12 is rotatably fitted over the corresponding first planetary gear shaft 14. For example, the first planetary gear 12 is rotatably fitted over the first planetary gear shaft 14 by means of a bearing. Hence, an objective of connecting the first planetary carrier 11 with the second planetary carrier 21 may be implemented by the first planetary gear shaft 14, so as to enable the first planetary carrier 11 and the second planetary carrier 21 to move at a same speed and in a same direction (that is, a linkage between the first planetary carrier 11 and the second planetary carrier 21 is carried out) . In addition, by means of this connection manner, the first planetary carrier 11 and the second planetary carrier 21 can favorably carry or fix the first planetary gear shaft 14, so as to prevent the differential 100 from being failed due to a disconnection between the first planetary gear shaft 14 and an individual planetary carrier.

As shown in FIG. 3, the first planetary gear 12 is meshed with the first gear ring 13, specifically in an internal meshing form. That is, the first planetary gear 12 is located at an inner side of the first gear ring 13 and is meshed with teeth on the first gear ring 13. In some embodiments, a plutality of first planetary gears 12 are provided, and distributed at the inner side of the first gear ring 13 at equal angle intervals along a circumferential direction. For example, in an embodiment, three first planetary gears 12 may be provided and an interval angle between any two adjacent first planetary gears 12 is 120°.

Similarly, as shown in FIG. 1, FIG. 3 and FIG. 5 in combination with FIG. 6-FIG. 7, the second planetary gear 22 is disposed on the second planetary carrier 21. For example, each second planetary gear 22 is provided with a second planetary gear shaft 24, two ends of the second planetary gear shaft 24 may be rotatably carried in shaft holes corresponding to each other in the first planetary carrier 11 and the second planetary carrier 21 by means of bearings, and the second planetary gear 22 may be fixed to the corresponding second planetary gear shaft 24. Certainly, the two ends of the second planetary gear shaft 24 may also be fixedly connected to the first planetary carrier 11 and the second planetary carrier 21. For example, the two ends of the second planetary gear shaft 24 are respectively welded and fixed to the shaft holes corresponding to each other in the first planetary carrier 11 and the second planetary carrier 21, and the first planetary gear 22 is rotatably fitted over the corresponding second planetary gear shaft 24. For example, the second planetary gear 22 is rotatably fitted over the second planetary gear shaft 24 by means of a bearing. Hence, the objective of connecting the first planetary carrier 11 and the second planetary carrier 21 may be implemented by the second planetary gear shaft 24, so as to enable the first planetary carrier 11 and the second planetary carrier 21 to move at a same speed and in a same direction. In addition, by means of this connection manner, the first planetary carrier 11 and the second planetary carrier 21 can favorably carry or fix the second planetary gear shaft 24, so as to prevent the differential 100 from being failed due to a disconnedtion between the second planetary gear shaft 24 and an individual planetary carrier.

In addition, in some other embodiments of the present disclosure, in order to enable the first planetary carrier 11 and the second planetary carrier 21 to move at a same speed and in a same direction, the first planetary carrier 11 may also be directly and fixedly connected to the second planetary carrier 21 by means of an intermediate component. That is, movements of the first planetary carrier 11 and the second planetary carrier 21 at a same speed and in a same direction in the foregoing embodiment are implemented by using the first planetary gear shaft 14 and the second planetary gear shaft 24. However, in this embodiment, the movements of the first planetary carrier 11 and the second planetary carrier 21 at a same speed and in a same direction may be implemented directly by disposing the intermediate component. For example, the intermediate component may be located between the first planetary carrier 11 and the second planetary carrier 21 and be welded and fixed to the first planetary carrier 11 and the second planetary carrier 21 respectively.

As shown in FIG. 3, the second planetary gear 22 is meshed with the second gear ring 23, specifically in an internal meshing form. That is, the second planetary gear 22 is located at an inner side of the second gear ring 23 and is meshed with teeth on the second gear ring 23. In some embodiments, a plutality of second planetary gears 22 are provided, and distributed at the inner side of the second gear ring 23 at equal angle intervals along a circumferential direction. For example, in an embodiment, three second planetary gears 22 may be provided and an interval angle between any two adjacent second planetary gears 22 is 120°.

It should be noted that FIG. 3 is a planar schematic diagram showing a principle of a differential 100 according to an embodiment of the present disclosure, in which a meshing relationship between the first planetary gear 12 and the second planetary gear 22 and the meshing relationships between the first planetary gear 12 and the first gear ring 13 and between the second planetary gear 22 and the second gear ring 23 are illustratively shown. Because FIG. 3 is a planar diagram and shows the foregoing three meshing relationships at the same time, the relative position relationships among components are merely illustrative and do not indicate or imply positions of the components in an actual spatial disposition.

In an embodiment in which the plutality of first planetary gears 12 and the plutality of second planetary gears 22 are provided, the plutality of first planetary gears 12 are correspondingly meshed with the plutality of second planetary gears 22 respectively. For example, as shown in FIG. 1 and FIG. 4, three first planetary gears 12 and three second planetary gears 22 are provided, the first one of the three first planetary gears 12 may be meshed with the corresponding first one of the three second planetary gears 22, the second one of the three first planetary gears 12 may be meshed with the corresponding second one of the three second planetary gears 22, and the third one of the three first planetary gears 12 may be meshed with the corresponding third one of the three second planetary gears 22. In this way, multiple groups of the first planetary gear 12 and the second planetary gear 22 meshed with each other are provided. When the differential 100 transmits power, transmission of the power among the multiple groups of the first planetary gear 12 and the second planetary gear 22 meshed with each other is more stable and reliable.

In addition, in another embodiment in which the plutality of first planetary gears 12 and the plurality of second planetary gears 22 are provided, the plutality of first planetary gears 12 and the plurality of second planetary gears 22 are alternately disposed along a circumferential direction, and the first planetary gear 12 is meshed with the second planetary gear 22 adjacent thereto. That is, in this embodiment, the plutality of first planetary gears 12 and the plutality of second planetary gears 22 are alternately disposed along the circumferential direction to form a ring, each first planetary gear 12 is meshed with two second planetary gears 22 adjacent thereto, and similarly, each second planetary gear 22 is meshed with two first planetary gears 12 adjacent thereto.

With reference to the embodiment of FIG. 3, a revolution axis of the first planetary gear 12 conincides with a revolution axis of the second planetary gear 22, i.e., the first planetary gear 12 and the second planetary gear 22 have a same revolution axis O, and a revolution radius (that is, a distance between an central axis of the first planetary gear 12 and the revolution axis O) of the first planetary gear 12 is the same with a revolution radius (that is, a distance between an central axis of the second planetary gear 22 and the revolution axis O) of the second planetary gear 22.

In an embodiment, as shown in FIG. 1 to FIG. 2 and FIG. 4 to FIG. 7, the first planetary gear 12 is meshed with and fitted with the second planetary gear 22. In other words, the first planetary gear 12 is meshed with the first gear ring 13 and also is meshed with the second planetary gear 22 at the same time, and the second planetary gear 22 is meshed with the second gear ring 23 and also is meshed with the first planetary gear 12 at the same time.

As shown in FIG. 3, the first gear ring 13 and the second gear ring 23 may be configured as two power output ends of the differential 100, and the first planetary carrier 11 and the second planetary carrier 21 correspondingly may be configured as power input ends of the differential 100 (for example, at this time, the first planetary carrier 11 and the second planetary carrier 21 may be rigidly connected together) . In this way, power output from an external power source may be input through the first planetary carrier 11 and the second planetary carrier 21 and may be output through the first gear ring 13 and the second gear ring 23 after a speed differential action of the differential 100. In this way, in an alternative implementation manner, the first planetary carrier 11 and the second planetary carrier 21 may be connected to a power source such as an engine or a motor, and the first gear ring 13 and the second gear ring 23 may be connected to corresponding half shafts through gear transmission structures, and the half shafts are further connected to corresponding wheels, which, however, is not limited to this.

A working principle of the differential 100 is briefly described by taking the following example that the differential 100 is applied to the inter-wheel speed differential, the first gear ring 13 and the second gear ring 23 are configured as the two power output ends of the differential 100, and the first planetary carrier 11 and the second planetary carrier 21 are configured as the power input ends of the differential 100, in which, at this time, the first gear ring 13 may be connected to a left half shaft through, for example, a gear transmission structure, and the left half shaft may be connected to a left-side wheel, the second gear ring 23 may be connected to a right half shaft through, for example, a gear transmission structure, and the right half shaft may be connected to a right-side wheel, and the power output by a power source, such as an engine and/or a motor, may be output to the first planetary carrier 11 and the second planetary carrier 21 after a deceleration action of a final drive. If the vehicle travels on an even road and does not turn, the left-side wheel and the right-side wheel theoretically have a same rotation speed, and at this time, the differential 100 does not perform the speed differential action, such that the first planetary carrier 11 and the second planetary carrier 21 rotate at a same speed and in a same direction, and the first gear ring 13 and the second gear ring 23 rotate at a same speed and in a same direction, i.e., the first planetary gear 12 and the second planetary gear 22 only revolve and do not rotate. If the vehicle is traveling on an uneven road or is turning, the left-side wheel and the right-side wheel theoretically have different rotation speeds, and the first gear ring 13 and the second gear ring 23 also have different rotation speeds, that is, a rotation speed difference exists, and thus, at this time, the first planetary gear 12 and the second planetary gear 22 rotate while revolving. Rotation of the first planetary gear 12 and the second planetary gear 22 may accelerate one of the first gear ring 13 and the second gear ring 23 and decelerate the other one of the first gear ring 13 and the second gear ring 23, and a rotation speed difference between the accelerated gear ring and the decelerated gear ring is a rotation speed difference between the left and right wheels, thereby implementing the speed differential action.

Hence, the differential 100 according to the embodiments of the present disclosure utilizes a planetary differential principle, has a high space utilization ratio in terms of the structure and connection form, provides a small axial dimension, and has much advantages in production and assembly. Such a structural form can avoid dimension defects of an angle gear in axial and radial direction thereof, and also can additionally utilize a hollow space inside a driven gear of a final drive preferably, thereby achieving the high space utilization ratio, greatly facilitating the entire vehicle arrangement in which the differential 100 is assembled and meating limitation requirements to the weight and size. Meanwhile, the differential 100 according to embodiments of the present disclosure has high reliability and preferable transmission efficiency, which is beneficial to improving reliability of a power transmission chain and smoothness of power output during turning, and thus is more practical with respect to a symmetrical angle gear differential.

The meshing relationships between the first planetary gear 12 and the second planetary gear 22 are described in detail with reference to specific embodiments as follows.

As shown in FIG. 3, and FIG. 5 to FIG. 7, the first planetary gear 12 and the second planetary gear 22 are partially overlaped in the axial direction (referring to a left-right direction in FIG. 7) . That is, part of the first planetary gear 12 and part of the second planetary gear 22 are overlaped, and rest of the first planetary gear 12 is staggered from rest of the second planetary gear 2. The overlaped parts of the first planetary gear 12 and the second planetary gear 22 may be meshed with each other, and the staggerd parts thereof may be meshed with the corresponding gear rings respectively.

In some embodiments, as shown in FIGS. 6 and 7, the first planetary gear 12 may include a first tooth portion 151 and a second tooth portion 152 (divided by a dashed line K2 in FIG. 7) , and the second planetary gear 22 may include a third tooth portion 153 and a fourth tooth portion 154 (divided by a dashed line K1 in FIG. 7) . The second tooth portion 152 and the third tooth portion 153 are configured as the overlapped parts, that is, the second tooth portion 152 and the third tooth portion 153 are overlaped and meshed with each other in the axial direction. The first tooth portion 151 and the fourth tooth portion 154 are staggered from each other in the axial direction and meshed with the corresponding gear rings respectively. That is, the first tooth portion 151 is meshed with the first gear ring 13, and the fourth gear tooth portion 154 is meshed with the second gear ring 23. It should be noted that, positions of the dashed lines K1 and K2 may be adjusted according to a practical situation, which is not limited herein.

Hence, the differential 100 has a compact axial dimension and a small volume, which is in favor of the installation and arrangement of the differential 100.

The power output end and the power input end of the differential 100 are described in detail with reference to the specific embodiments as follows.

As shown in FIG. 3, the differential 100 further includes

input shafts

31, 32 and

output shafts

41, 42, and the

input shafts

31, 32 are respectively connected to the first planetary carrier 11 and the second planetary carrier 21. As shown in the example of FIG. 3, a left side of the first planetary carrier 11 is connected to the input shaft 31 and a right side of the second planetary carrier 21 is connected to the input shaft 32. The

output shafts

41, 42 are respectively connected to the first gear ring 13 and the second gear ring 23. As shown in the example of FIG. 3, a left side of the first gear ring 13 is connected to the output shaft 41, and a right side of the second gear ring 23 is connected to the output shaft 42. The

input shafts

31, 32, the

output shafts

41, 42, the first gear ring 13, and the second gear ring 23 may be coaxially disposed.

Further, as shown in FIG. 3, the input shaft includes a first input shaft 31 and a second input shaft 32, the first input shaft 31 is connected to the first planetary carrier 11, and the second input shaft 32 is connected to the second planetary carrier 21； the output shaft may include a first output shaft 41 and a second output shaft 42, the first output shaft 41 is connected to the first gear ring 13, and the second output shaft 42 is connected to the second gear ring 23； the first input shaft 31 and the second input shaft 32 as well as the first output shaft 41 and the second output shaft 42 all may be hollow shaft structures. In an embodiment, the first output shaft 41 is coaxially fitted over the first input shaft 31, and the second output shaft 42 is coaxially fitted over the second input shaft 32. Hence, the differential 100 has a compact structure and has a small volume.

In some embodiments, the number of teeth of the first gear ring 13 may be the same with the number of teeth of the second gear ring 23, and the number of teeth of the first planetary gear 12 may be the same with the number of teeth of the second planetary gear 22.

According to some embodiments of the present disclosure, both the first planetary gear 12 and the second planetary gear 22 are cylindrical gears. As compared with the conventional symmetrical angle gear differential, the differential 100 using cylindrical gears has a more compact structure. Specifically, the differential 100 using cylindrical gears has a higher space utilization ratio in terms of the structure and connection form, provides a smaller axial dimension, and has more advantages inproduction and assembly.

In the following, the detailed structures of the first gear ring 13 and the second gear ring 23 may be specifically described below with reference to the specific embodiments.

In some embodiments of the present disclosure, the first gear ring 13 and the second gear ring 23 are symmetrical structures. In other words, the first gear ring 13 and the second gear ring 23 are symmetrically disposed, thereby increasing universality of the gear rings and reducing costs thereof.

In some embodiments, as shown in FIG. 1 in combination with FIG. 3, each of the first gear ring 13 and the second gear ring 23 may include a main flat plate portion 161 and an annular sidewall portion 162 disposed at a peripheral edge of the main flat plate portion 161. The main flat plate portion 161 and the annular sidewall portion 162 may be configured as integrally molded components. A plurality of gear teeth are disposed on an inner wall surface of the annular sidewall portion 162, a cavity A1 or A2 (referring to FIG. 3) is defined between the main flat plate portion 161 and the annular sidewall portion 162. That is, a cavity A1 is defined between the main flat plate portion 161 and the annular sidewall portion 162 of the first gear ring 13； and a cavity A2 is defined between the main flat plate portion 161 and the annular sidewall portion 162 of the second gear ring 23.The cavity A1 defined in the first gear ring 13 and the cavity A2 defined in the second gear ring 23 face each other to form a mounting space A (referring to FIG. 3) . The first planetary carrier 11 and the first planetary gear 12 as well as the second carrier 21 and the second planetary gear 22 are accommodated inside the mounting space A, such that the differential 100 is relatively compact in structure, occupies a small space, and is easy to be arranged. Meanwhile, the first gear ring 13 and the second gear ring 23 act as an outer housing to protect the planetary carriers and the planetary gears housed therein so as to improve lifes thereof. Further, the mounting space A defined by the first gear ring 13 and the second gear ring 23 is relatively closed to stop the outside impurities from entering the the mounting space A and affecting the moving parts therein, thus ensuring a stable operation of the differential 100.

With reference to FIG. 2, a gap D is provided between the first gear ring 13 and the second gear ring 23 along the axial direction. That is, the first gear ring 13 and the second gear ring 23 are axially spaced from each other, instead of closely adhering to each other. To persons skilled in the art, since a width of a meshed portion between the first planetary gear 12 and the second planetary gear 22 determines a size of the gap D, i.e. the width of the meshed portion between the first planetary gear 12 and the second planetary gear 22 may be equal to a minimum size of the gap D, and thus by controlling the width of the meshed portion width between the first planetary gear 12 and the second planetary gear 22, the size of the gap D may be controlled indirectly. On the premise that the first planetary gear 12 and the second planetary gear 22 can stably transmit power and the using lifes of the first planetary gear 12 and the second planetary gear 22 are ensured, it is possible for those skilled in the related art to set the width of the meshed portion width between the first planetary gear 12 and the second planetary gear 22 to be relatively narrow, so that the gap D can be effectively reduced, and thereby the axial dimension of the differential 100 may be relatively small and compact, and the differential 100 is easy to be arranged.

It should be noted that, with reference to the embodiments of FIG. 1, FIG. 2 and FIG. 3, both of the first gear ring 13 and the second gear ring 23 include the main flat plate portion 161 and the annular sidewall portion 162, and the foregoing gap D in FIG. 2 (in combination with FIG. 1 and FIG. 3) refers to a distance between an annular sidewall portion 162 of the first gear ring 13 and an annular sidewall portion 162 of the second gear ring 23.

Moreover, in some other embodiments of the present disclosure, for example, with reference to the embodiments of FIG. 8 and FIG. 9, each of the first gear ring 13 and the second gear ring 23 further includes an annular flange portion 163, and the annular flange portion 163 extends from an end surface of the annular sidewall portion 162 in a direction of departing from the main flat plate portion 161. In the embodiment of FIG. 8, an inside diameter of the annular flange portion 163 may be approximately equal to an outside diameter of the annular sidewall portion 162, which is equivalent to that the annular flange portion 163 protrudes radially outwards beyond the annular sidewall portion 162 (i.e., a peripheral surface of the first gear ring 13 or the second gear ring 23) . Further, in the embodiment of FIG. 9, the outside diameter of the annular flange portion 163 may be approximately equal to the outside diameter of the annular sidewall portion 162, and the inside diameter of the annular flange portion 163 may be larger than the inside diameter of the annular sidewall portion 162, that is, a thickness of the annular flange portion 163 is smaller than a thickness of the annular sidewall portion 162.

However, it should be noted that in the gear ring structure in the embodiments of FIG. 1 to FIG. 3, the gap D between the two gear rings refers to a gap between the annular sidewall portions 162 of the two gear rings. Moreover, in the gear ring structure in the embodiments of FIG. 8 and FIG. 9, the gap D between the two gear rings refers to a gap between the annular flange portions 163 of the two gear rings.

Moreover, in some other embodiments of the present disclosure, for example, with reference to the embodiments of FIG. 8 and FIG. 9, since the first gear ring 13 and/or the second gear ring 23 may further include the annular flange portion 163, when the gear ring having the annular flange portion 163 is used, compared with the gear ring without the annular flange portion 163, the above mentioned gap D can be further reduced at least to a certain extent. In an embodiment, the gap D may be reduced to zero. For example, each of the first gear ring 13 and the second gear ring 23 may be configured as the structure shown in FIG. 8, and an end face of the annular flange portion 163 of the first gear ring 13 may substantially adhere to an end face of the annular flange portion 163 of the second gear ring 23, so that the gap D is allowed to be zero. In this way, the mounting space A is relatively closed to fully stop the outside impurities from entering the mounting space A and affecting the moving parts therein, thus ensuring the stable operation of the differential 100. Of course, it should be understood that the descriptions herein are illustrative only and shall not be construed as a limitation to the protection scope of the present disclosure, and those skilled in the art can select and combine various types of gear rings flexibly after reading the foregoing content and understanding the technical concept that the gap D may be further reduced or even reduced to zero by providing the annular flange portion 163. For example, it is ensured that at least one gear ring has the annular flange portion 163, so that the gap D can be further reduced or even reduced to zero, thus allowing the mounting space A to be more enclosed.

In an embodiment, a radial dimension of the first gear ring 13 is equal to a radial dimension of the second gear ring 23, and each of the first gear ring 13 and the second gear ring 23 may be configured as an integrally molded component.

In addition, in a case that the technical solutions and/or the technical features described in the foregoing embodiments are not in conflict with each other or in contradiction with each other, those skilled in the art can combine the technical solutions and/or the technical features in the foregoing embodiments with each other. The combined technical solution may be a superposition of two or more technical solutions, a superposition of two or more technical features, or a superposition of two or more technical solutions and technical features. Hence, the technical solutions and/or the technical features can interact with and support each other in terms of function, and the combined solution has better technical effects.

In some embodiments, one skilled in the art may combine the solution that the first planetary gear 12 and the second planetary gear 22 are partially overlapped with the solution that the first planetary carrier 11 and the second planetary carrier 21 are configured as plate-shaped structures, and thus the axial dimension of the differential 100 may be reduced effectively, so that the differential 100 has a small volume.

In some embodiments, one skilled in the art may combine the solution that the first planetary gear 12 and the second planetary gear 22 are partially overlapped with the solution that the planetary gears and the planetary carriers are received in the mounting space, so that an axial dimension of the differential 100 may be effectively reduced, and also the planetary gears and the planetary carriers are enclosed in the mounting space to avoid damage thereon from outside, thereby increasing the service life and reducing the maintenance cost.

In some embodiments, one skilled in the art may combine the solution that the revolution axis of the first planetary gear 12 conincides with the revolution axis of the second planetary gear 22 with the solution that the revolution radius of the first planetary gear 12 is the same with the revolution radius of the second planetary gear 22, so that he differential 100 has a compact structure ands a small volume, and is easy to be arranged.

Certainly, it should be understood that the foregoing examples are merely illustrative. With regard to the combination of the technical solutions and/or the technical features, those skilled in the art can make a free combination in the case of no conflict, and the combined solution has better technical effects. The present disclosure merely briefly describes the forgoing multiple examples, and the examples are not listed exhaustively one by one herein.

In addition, it could be understood that the combined technical solution also falls within the protection scope of the present disclosure.

Generally, the differential 100 according to embodiments of the present disclosure can effectively save space and reduce weight. In an embodiment, as compared with the conventional angle gear differential, the planetary gear differential 100 can reduce the weight by approximately 30％, and meanwhile reduce the axial dimension by approximately 70％, so as to reduce the friction of the bearing, and also to implement the torque distribution between the left and right wheels, so that the load distribution of the differential 100 is more proper and the rigidity of the differential 100 is better. In addition, because the cylindrical gear is used, the transmission efficiency is also improved to some extent. For example, the transmission efficiency of a conventional angle gear of 6-level precision or 7-level precision is approximately 0.97 to 0.98, and the transmission efficiency of the cylindrical gear of 6-level precision or 7-level precision is approximately 0.98 to 0.99. In addition, the use of the cylindrical gear also reduces working noise of the differential 100 and meanwhile reduces heat generation, thereby greatly prolonging the service life of the differential 100. Briefly, the differential 100 according to the embodiments of the present disclosure has many advantages such as a light weight, a small dimension, low costs, high transmission efficiency, low noise, less heat generation, and a long service life.

Meanwhile, a sun gear is omitted from the differential 100 according to the embodiments of the present disclosure, and omission of the sun gear has the following advantages.

In terms of mechanical analysis, the sun gear shall be omitted, and the speed differential shall be implemented by using a gear ring. Because as compared with the sun gear, the gear ring may be provided with more teeth, and meanwhile, has a larger pitch circle (the pitch circle refers to a pair of circles that are tangent to each other at a pitch point during the meshing transmission of gears) , such that the load may be distributed more evenly and also the torque may be carried more evenly, which is beneficial to prolonging the service life of the differential 100. Meanwhile, in the absence of the sun gear, the differential 100 may be lubricated and cooled more favorably. That is, because the sun gear is omitted, a cavity may be formed inside the gear ring, the meshing between the gear ring and the planetary gear is an internal meshing (however, the meshing between the sun gear and the planetary gear is an external meshing) , and thus lubricating oil may be stored inside the gear ring, so that the cooling and lubricating effects are greatly improved. In addition, because the sun gear is omitted, the number of parts is decreased, and the mass and cost of the differential 100 are reduced, so that the differential 100 is much smaller and lighter.

A power transmission system 100 according to an embodiment of the present disclosure is briefly described as follows. The power transmission system 100 includes the differential 100 according to the foregoing embodiments of the present disclosure. As shown in FIG. 10, the power transmission system 1000 includes the differential 100, a transmission 200 and a power source 300. The power output from the power source 300 is output to the differential 100 after the speed changing action of the transmission 200 and then is distributed by the differential 100 to the driving wheels on two sides. It could be understood that the power transmission system 1000 shown in FIG. 10 is merely an example, instead of a limitation to the protection scope of the present disclosure. In addition, it should be understood that other structures, such as the engine and transmission, of the power transmission system according to the embodiment of the present disclosure all belong to the prior art and are well known to those skilled in the art, and therefore, are not described again herein one by one.

As shown in FIG. 11, a vehicle 10000 according to embodiments of the present disclosure is briefly described as follows. The vehicle 10000 includes the power transmission system 1000 according to the foregoing embodiment of the present dislcosure. The power transmission system 1000 may be used for a front wheel drive, and certainly, may also be used for a rear wheel drive, which is not specifically defined and limited by the present disclosure herein. It should be understood that other structures, such as a braking system, a traveling system, and a steering system, of the vehicle according to the embodiment of the present disclosure all belong ot the prior art and are well known to those skilled in the art, and therefore, are not described again herein one by one.

In the descriptions of this specification, a description of a reference term such as "an embodiment" , "some embodiments" , "exemplary embodiments" , "examples" , "specific examples" , or "some examples" means that a specific feature, structure, material, or characteristic that is described with reference to the embodiment or the example is included in at least one embodiment or example of the present disclosure. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to a same embodiment or example. In addition, the described specific feature, structure, material, or characteristic may be combined in a proper manner in any one or more embodiments or examples. Moreover, those skilled in the art can joint and combine different embodiments or examples described in the present description.

Although the embodiments of the present disclosure have been shown and described, a person of ordinary skill in the art can understand that multiple changes, modifications, replacements, and variations may be made to these embodiments without departing from the principle and purpose of the present disclosure.

Claims

A differential, comprising:

a first planetary carrier；

a first gear ring；

a first planetary gear disposed on the first planetary carrier, and meshed with the first gear ring；

a second planetary carrier；

a second gear ring； and

a second planetary gear disposed on the second planetary carrier and meshed with the second gear ring as well as the first planetary gear,

wherein the first gear ring and the second gear ring are configured as two power output ends of the differential, the first planetary carrier and the second planetary carrier are configured as power input ends of the differential.
The differential according to claim 1, wherein the first planetary gear and the second planetary gear are partially overlaped in an axial direction.
The differential according to claim 2, wherein the first planetary gear comprises a first tooth portion and a second tooth portion, the second planetary gear comprises a third tooth portion and a fourth tooth portion, and the first tooth portion is meshed with the first gear ring, the second tooth portion and the third tooth portion are overlaped and meshed with each other, and the fourth gear tooth portion is meshed with the second gear ring.
The differential according to any one of claims 1-3, further comprising:

an input shaft connected to the first planetary carrier and the second planetary carrier respectively； and

an output shaft connected to the first gear ring and the second gear ring respectively,

wherein the input shaft and the output shaft are disposed coaxially.
The differential according to claim 4, wherein the input shaft comprises:

a first input shaft connected to the first planetary carrier； and

a second input shaft connected to the second planetary carrier,

wherein the output shaft comprises:

a first output shaft connected to the first gear ring and coaxially fitted over the first input shaft； and

a second output shaft connected to the second gear ring and coaxially fitted over the second input shaft.
The differential according to any one of claims 1-5, wherein both the first planetary carrier and the second planetary carrier are configured as circular plate-shaped structures, and the first planetary carrier and the second planetary carrier are configured as separated structures.
The differential according to any one of claims 1-6, wherein the first planetary gear and the second planetary gear both are configured as cylindrical gears.
The differential according to any one of claims 1-7, wherein the first gear ring and the second gear ring are symmetrically disposed.
The differential according to claim 8, wherein each of the first gear ring and the second gear ring comprises:

a main flat plate portion； and

an annular sidewall portion disposed at a peripheral edge of the main flat plate portion,

wherein a plurality of teeth are disposed on an inner wall surface of the annular sidewall portion, a cavity is defined between the main flat plate portion and the annular sidewall portion, and a cavity of the first gear ring and a cavity of the second gear ring face each other to form a mounting space.
The differential according to claim 9, wherein the first planetary carrier and the first planetary gear as well as the second planetary carrier and the second planetary gear are accommodated inside the mounting space.
The differential according to any one of claims 1-10, wherein a gap is defined between the first gear ring and the second gear ring along an axial direction.
The differential according to any one of claims 1-11, wherein each first planetary gear is provided with a first planetary gear shaft, two ends of the first planetary gear shaft are connected to the first planetary carrier and the second planetary carrier respectively, each second planetary gear is provided with a second planetary gear shaft, and two ends of the second planetary gear shaft are connected to the first planetary carrier and the second planetary carrier respectively.
The differential according to any one of claims 1-12, wherein a revolution axis of the first planetary gear conincides with a revolution axis of the second planetary gear.
The differential according to any one of claims 1-13, wherein a revolution radius of the first planetary gear is equal to a revolution radius of the second planetary gear.
The differential according to any one of claims 1-14, wherein a plurality of first planetary gears are provided and distributed at intervals along a circumferential direction, a plurality of second planetary gears are provided and distributed at intervals along the circumferential direction, and the plurality of first planetary gears are correspondingly meshed with the plurality of second planetary gears respectively.
The differential according to any one of claims 1-14, wherein a plurality of first planetary gears and a plurality of second planetary gears are provided, the plurality of first planetary gears and the plurality of second planetary gears are disposed alternately along a circumferential direction, and the first planetary gear is meshed with the second planetary gear adjacent thereto.
A power transmission system, comprising a differential according to any one of claims 1 to 16.
A vehicle, comprising a power transmission system according to claim 17.