In-wheel working device

An in-wheel working device may include a motor part configured to generate power, a first speed reduction part including a sun gear connected to a driving shaft of the motor part and configured to rotate with the driving shaft, a planetary gear configured to rotate along a circumference of the sun gear, and a carrier configured to rotate with the planetary gear, a second speed reduction part installed in series to the first speed reduction part, and configured to perform speed reduction through a gear ratio while rotating with the carrier axially connected to the second speed reduction part, a hub part spline-coupled to the second speed reduction part, and configured to rotate with the second speed reduction part, and a wheel member connected to the hub part, and configured to rotate with the hub part.

CROSS-REFERENCES TO RELATED APPLICATION

This application claims priority from and the benefit of Korean Patent Application No. 10-2016-0144660, filed on Nov. 1, 2016, which is hereby incorporated by reference for all purposes as if set forth herein.

BACKGROUND

Field

Exemplary embodiments relate to an in-wheel working device. More particularly, exemplary embodiments relate to an in-wheel working device which is capable of implementing a compact two-stage speed reduction device, thereby reducing the size of a motor while doubling a driving force.

Discussion of the Background

The exhaustion of fossil fuels has promoted development of electric vehicles which are propelled by a motor using electric energy stored in a battery, instead of engines using the fossil fuels such as gasoline and diesel.

The electric vehicles are divided into a pure electric vehicle that is propelled by motor using only electric energy stored in a rechargeable battery, a solar cell vehicle that is propelled by a motor using a photoelectric cell, a fuel cell vehicle that is propelled by a motor using a fuel cell using hydrogen fuel, and a hybrid vehicle that is propelled by an engine and motor by driving the engine using fossil fuel and driving the motor using electricity.

In general, an in-wheel working device is a technique used for a vehicle, such as an electric vehicle that uses electricity as a power source. Unlike a system that rotationally drives a wheel using power transfer through an engine, transmission, and drive shaft of a gasoline or diesel vehicle, the in-wheel working device directly transfers power to the wheels using motors disposed in the drive wheel.

The conventional in-wheel working device has a large motor diameter to increase a drive torque without a speed reducer. Thus, the wheel size is inevitably increased. Therefore, there is a demand for a structure capable of solving the problem.

SUMMARY

Exemplary embodiments of the present invention provide an in-wheel working device which is capable of implementing a compact two-stage speed reduction device, thereby reducing the size of a motor while multiplying a driving force.

In an embodiment, an in-wheel working device may include a motor part configured to generate power, a first speed reduction part including a sun gear connected to a driving shaft of the motor part and configured to rotate with the driving shaft, a planetary gear configured to rotate along a circumference of the sun gear, and a carrier configured to rotate with the planetary gear, a second speed reduction part installed in series to the first speed reduction part, and configured to perform speed reduction through a gear ratio while rotating with the carrier axially connected to the second speed reduction part, a hub part spline-coupled to the second speed reduction part, and configured to rotate with the second speed reduction part, and a wheel member connected to the hub part, and configured to rotate with the hub part.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Various advantages and features of the present invention and methods accomplishing thereof will become apparent from the following description of embodiments with reference to the accompanying drawings. However, the present invention is not be limited to the embodiments set forth herein but may be implemented in many different forms. The present embodiments may be provided so that the disclosure of the present invention will be complete, and will fully convey the scope of the invention to those skilled in the art and therefore the present invention will be defined within the scope of claims.

Unless defined otherwise, it is to be understood that all the terms (including technical and scientific terms) used in the specification has the same meaning as those that are understood by those who skilled in the art. Further, the terms defined by the dictionary generally used should not be ideally or excessively formally defined unless clearly defined specifically. It will be understood that for purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). Unless particularly described to the contrary, the term “comprise,” “configure,” “have,” or the like, which are described herein, will be understood to imply the inclusion of the stated components, and therefore should be construed as including other components, and not the exclusion of any other elements.

Embodiments of the invention will hereinafter be described in detail with reference to the accompanying drawings. It should be noted that the drawings are not to precise scale and may be exaggerated in thickness of lines or sizes of components for descriptive convenience and clarity only.

Furthermore, the terms as used herein are defined by taking functions of the invention into account and can be changed according to the custom or intention of users or operators. Therefore, definition of the terms should be made according to the overall disclosures set forth herein.

FIG. 1is a schematic front view of an in-wheel working device in accordance with an embodiment of the present invention,FIG. 2is a schematic cross-sectional view of the in-wheel working device, taken along the line A-A ofFIG. 1,FIG. 3is an exploded perspective view of main parts of the in-wheel working device in accordance with the embodiment of the present invention,FIG. 4is a cross-sectional view illustrating that a sun gear in accordance with an embodiment of the present invention is installed, andFIG. 5is a cross-sectional view illustrating that a sun gear in accordance with another embodiment of the present invention is installed.

As illustrated inFIGS. 1-5, the in-wheel working device1in accordance with the embodiment of the present invention may include a motor part10, a housing part20, a first speed reduction part30, a second speed reduction part40, a hub part50, a wheel member60, a braking disk70, a bearing part80, a resolver90and a speed reducer cover100.

The motor part10may include various types of driving devices as long as they can generate power to rotate the wheel member60.

The center axis of the motor part10may be set at a position separated by a preset distance from the rotational center axis66of the wheel member60. Therefore, the position of the motor part10may secure the maximum size of the motor part10while avoiding an interference with a chassis part during driving. As illustrated inFIG. 1, the motor part10may be located at the front top of the wheel member60, which makes it possible to increase the degree of freedom when a suspension such as a lower arm62is disposed at the bottom of the wheel member60.

Furthermore, a caliper part for restricting rotation of the braking disk70may be installed at the opposite side of the motor part10in the wheel member60. Therefore, when the in-wheel working device1in accordance with the present embodiment is seen from the inside of the vehicle, the center of the motor part10may be set at a position separated by a preset distance from the rotational center axis66of the wheel member60toward the front side (left side inFIG. 1). Thus, the caliper part may be located at the upper portion of the rear side (right side inFIG. 1) of the wheel member60. Furthermore, an upper arm63and the like may be installed at the top of the rotational center axis66corresponding to the axle center, and a lower arm62and the like may be installed at the bottom of the rotational center axis66.

The motor part10in accordance with the present embodiment may include a motor housing11, a motor cover12, a stator core13, a stator coil14, a rotor core15, and a driving shaft16.

The motor housing11protruding to the outside of the housing part20may be installed in a shape protruding in the lateral direction of the wheel member60. The motor housing11may have a hole formed in the center thereof, and the motor cover12may open/close the hole formed in the motor housing11.

In the motor housing11, the stator core13, the stator coil14, the rotor core15and the driving shaft16may be installed. The stator core13may be fixed along the inner sidewall of the motor housing11, and the stator coil14may be installed outside the stator core13. The stator core13may be installed in the circumferential direction along the motor housing11, and the rotor core15may be installed in the stator core13.

The rotor core15may be rotated by a power supply, and the driving shaft16may be connected to the inside of the rotor core15, and rotated with the rotor core15.

When the motor part10is a three-phase motor, the stator coil14may include a U-phase coil, a V-phase coil, and a W-phase coil. The rotor core15may be disposed at the inner circumference of the stator core13and the stator coil14, and supported by a double ball bearing81so as to rotate relative to the motor housing11.

The resolver90may be mounted behind the double ball bearing81, and transmit location information for motor control to an inverter serving as a control unit.

A rotation output of the rotor core15may be transferred to the wheel member60through the driving shaft16, the first speed reduction part30, the second speed reduction part40, and the hub part50. Since a speed reduction device used in the in-wheel working device1includes the first speed reduction part30serving as a planetary gear speed reducer and the second speed reduction part40serving as a counter gear, two-stage speed reduction may be performed.

The driving shaft16installed in the rotor core15may be rotated with the rotor core15, and the rotation of the driving shaft16may be measured by the resolver90while one side (left side inFIG. 2) of the driving shaft16is supported by the double ball bearing81. The other side (right side inFIG. 2) of the driving shaft16may be connected to a sun gear31of the first speed reduction part30and rotate the sun gear31.

The motor housing11of the motor part10may be fixed to a side surface of the housing part20fixed to the vehicle body. The housing part20may be formed in a plate shape, and installed in a shape surrounding the side of the first speed reduction part30.

The first speed reduction part30may include the sun gear31, a planetary gear35, a carrier37, and a ring gear36. The sun gear31may be rotated in connection with the driving shaft16of the motor part10, the planetary gear35may be rotated along the circumference of the sun gear31, the carrier37may be rotated with the planetary gear35while rotatably supporting the planetary gear35, and the ring gear36may be installed outside the planetary gear35.

As illustrated inFIG. 2, the first speed reduction part30including a planetary gear set may be disposed closer to the outside of the vehicle (right side inFIG. 2) than the motor part10. The rotational center of the first speed reduction part30including a planetary gear set may be disposed on the same axis line as the driving shaft16of the motor part10.

The sun gear31may be spline-coupled to the driving shaft16, and the ring gear36may be inserted into the housing part20and restricted from rotating. The ring gear36may have a plurality of grooves or protrusions formed at the outside thereof, and the housing part20facing the ring gear36may have protrusions or grooves corresponding to those of the ring gear36. Thus, the ring gear36may be coupled to the housing part20and restricted from rotating. Furthermore, since a snap ring may be installed at the other side of the ring gear36, an axial motion of the ring gear36may be restricted. Therefore, since the sun gear31may be rotated in connection with the motor part10while the ring gear36may be fixed, the carrier37may be rotated while the speed thereof may be reduced.

Since one side of the carrier37(left side inFIG. 2) may be supported by a first bearing82of the bearing part80, a frictional force generated during the rotation of the carrier37may be reduced. The first bearing82may be installed between the driving shaft16and the carrier37, and the driving shaft16may be fastened to the center of the sun gear31, such that the sun gear31may be rotated with the driving shaft16.

The planetary gear35may be engaged with the outside of the sun gear31so as to revolve and rotate, and the carrier37which rotatably supports the planetary gear35may be rotated with the planetary gear35.

The ring gear36may be located outside the planetary gear35, fixed to the housing part20which may be coupled to the motor part10while surrounding the outside of the first speed reduction part30, and restricted from rotating.

The second speed reduction part40may be installed in series to the first speed reduction part30, and include various types of speed reduction devices as long as the second speed reduction part40can perform speed reduction through a gear ratio while rotated with the carrier37axially-connected thereto. The second speed reduction part40in accordance with the present embodiment may include a small-diameter gear shaft41, a small-diameter gear42, and a large-diameter gear43. The small-diameter gear shaft41may be axially coupled to the carrier37, the small-diameter gear42may be installed in a ring shape outside the small-diameter gear shaft41and rotated with the small-diameter gear shaft41, and the large-diameter gear43may be engaged and rotated with the small-diameter gear42and have a larger diameter than the small-diameter gear42.

The second speed reduction part40including a counter gear set may be disposed closer to the outside of the vehicle (right side inFIG. 2) than the first speed reduction part30using the planetary gear35, and include the small-diameter gear42coupled to the small-diameter gear shaft41and the large-diameter gear43engaged with a hub inner race52. The small-diameter gear shaft41may be coupled to the carrier37of the first speed reduction part30so as to receive power. One side of the small-diameter gear shaft41may be supported by a second bearing83, and the other side of the small-diameter gear shaft41may be supported by a third bearing84. The second bearing83may be located between the housing part20and the small-diameter gear shaft41, and the third bearing84may be located between the small-diameter gear shaft41and a speed reducer cover100coupled to the housing part20.

The carrier37and the small-diameter gear shaft41may be coupled to each other in the radial inside of the second bearing83. Such a structure may increase the space utilization, thereby improving the flexibility of design in the in-wheel working device1.

The carrier37and the small-diameter gear shaft41may be formed as separate members, and connected through various shaft connection methods as long as the carrier37and the small-diameter gear shaft41can be axially connected through spline coupling to transfer power.

Since the carrier37and the small-diameter gear shaft41may be formed as separate members and spline-coupled to each other, a load transferred in the axial direction of the small-diameter gear shaft41can be prevented from being transferred to the carrier37. Therefore, such a structure can not only prevent a deformation of the carrier37by a load generated through the second speed reduction part40, but also prevent an abnormal gear meshing which may be caused by an axial misalignment of the planetary gear35supported by the carrier37. Furthermore, the structure may prevent a reduction in durability of the first speed reduction part30while reducing operation noise of the planetary gear35.

When the small-diameter gear shaft41may be deformed by an external load, the carrier37spline-coupled to the small-diameter gear shaft41may be minimally influenced by the deformation of the small-diameter gear shaft41, and thus improve the operation reliability and durability of the first speed reduction part30.

The small-diameter gear42may be installed outside the small-diameter gear shaft41, and the large-diameter gear43engaged with the small-diameter gear42may implement a speed reduction output through a gear ratio. Between the large-diameter gear43and the housing part20, a fourth bearing85may be installed to perform a function of guiding a regular position when the large-diameter gear43may be assembled. One side of the large-diameter gear43may be supported by the fourth bearing85, and the other side of the large-diameter gear43may be spline-coupled to the hub inner race52of the hub part50, and then fixed by a fixing nut54.

When power is transferred from the motor part10, the first speed reduction part30including the planetary gear35may increase a primary torque, and the power may be transferred to the second speed reduction part40through the carrier37so as to increase a secondary torque. At this time, when the small-diameter gear shaft41is deformed by a force generated while the small-diameter gear42is engaged and rotated with the large-diameter gear43, an influence on the carrier37by the deformation of the small-diameter gear shaft41can be reduced because the small-diameter gear shaft41and the carrier37are not formed as one body but detachably connected to each other. Furthermore, while the axial stiffness of the small-diameter gear shaft41is secured to reduce an influence on the carrier37by the small-diameter gear shaft41, a tooth modification may be applied to smoothly perform gear meshing, when the small-diameter gear42and the large-diameter gear43are designed.

The hub part50may be spline-coupled to the second speed reduction part40, and formed in various shapes as long as the hub part50can rotate the wheel member60while being rotated with the second speed reduction part40. The hub part50in accordance with the present embodiment may include a hub outer race51, a hub inner race52, and a hub bearing53. The hub outer race51may be fixed to the housing part20and restricted from rotating, the hub inner race52may be spline-coupled to the large-diameter gear43so as to receive rotation power, and connected to the wheel member60so as to rotate with the wheel member60, and the hub bearing53may be located between the hub outer race51and the hub inner race52.

The hub outer race51may be formed in a pipe shape, and fixed to the housing part20. The hub bearing53may be installed in the hub outer race51, and the hub inner race52may be rotatably installed in the hub bearing53. The hub inner race52may be spline-coupled to the large-diameter gear43so as to receive rotation power. The large-diameter gear43spline-coupled to the hub inner race52may be fastened to the fixing nut54at the other side of the hub inner race52.

The hub part50may receive a torque which may be increased while the hub inner race52is spline-coupled to the large-diameter gear43of the second speed reduction part40including the counter gear and secondarily decelerated, and transfer the received torque to the wheel member60. The hub outer race51may be installed in a shape surrounding the hub inner race52, and fixed to the housing part20through a bolt so as to rotatably support the hub inner race52. Between the large-diameter gear43and the housing part20, a seal may be installed to block an oil leakage.

The hub inner race52and the wheel member60may be fixed through a hub bolt55. Thus, when the hub inner race52is rotated, the wheel member60may be rotated together.

A tire61may be installed along the outer circumference of the wheel member60which may be connected to the hub inner race52and rotated with the hub inner race52. The lower arm62may be installed at the bottom of the rotational center axis66of the wheel member60, and the upper arm63may be installed at the top of the rotational center axis66. Furthermore, a buffer spring64may be installed at the top of a damper65which may be installed in a vertical direction at a side surface of the wheel member60, and absorb a shock generated during driving.

The braking disk70may be connected to the hub inner race52and rotated with the hub inner race52, and the caliper part75may be installed in the housing part20and generate a braking force while coming in contact with the braking disk70. Therefore, the disk-type braking device can be installed in the in-wheel working device1without a design change of front-wheel and rear-wheel suspensions.

The bearing part80may include various types of bearings as long as they can reduce friction when the motor part10and the first and second speed reduction parts30and40are rotated. The bearing part80in accordance with the present embodiment may include the double ball bearing81, the first bearing82, the second bearing83, the third bearing84, and the fourth bearing85.

The first bearing82may be located between the driving shaft16and the carrier37, and reduce friction between the driving shaft16and the carrier37. The first bearing82may serve to guide the motor part10and the first speed reduction part30including the planetary gear35, such that the motor part10and the first speed reduction part30are coaxially maintained.

The second and third bearings83and84may be support the small-diameter gear shaft41. The second bearing83may be installed at one side of the small-diameter gear shaft41, and the third bearing84may be installed at the other side of the small-diameter gear shaft41.

The fourth bearing85may be installed between the large-diameter gear43and the housing part20, and guide the rotation of the large-diameter gear43.

The resolver installed on the driving shaft16of the motor part10may serve as a sensor for measuring the position of the rotor core15corresponding to a rotor of the motor part10. Since the resolver90may have higher mechanical strength and durability than an encoder, the resolver90may be used as a position sensor of the motor part10in various fields such as an electric vehicle, robot, airplane and military device, which require high performance and high precision.

The speed reducer cover100may be coupled to the housing part20so as to support the third bearing84, and a rotating seal may be mounted to prevent an oil leakage in the second speed reduction part40.

As illustrated inFIG. 5, a sun gear32in accordance with another embodiment of the present invention may include a sun gear body33and an extension protrusion34. The sun gear body33may be located between the driving shaft16and the planetary gear35, and the extension protrusion34may be extended from the sun gear body33and located between the driving shaft16and the first bearing82.

The extension protrusion34of the sun gear32may be located in an empty space between the carrier and the driving shaft16, and the first bearing82may be then installed between the extension protrusion34and the carrier. Therefore, since an axial force generated by the sun gear32is not transferred to the double ball bearing81of the motor part10(seeFIG. 2), the lifetime of the double ball bearing81can be extended, and stress transferred to the driving shaft16can be distributed to improve the durability of the driving shaft16.

Hereafter, the operation of the in-wheel working device1in accordance with the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

When a current is applied to the inverter, the current may be transferred to the stator coil to form a magnetic field. The magnetic field may rotate the rotor core15, and the torque of the rotor core15may be transferred to the sun gear31of the first speed reduction part30along the driving shaft16.

Since the driving shaft16may be supported by the double ball bearing81and the driving shaft16and the sun gear31are spline-coupled to each other, the durability may be improved, and the disassembling operation may be simplified to reduce the maintenance cost.

Since the sun gear31may be rotated and the ring gear36may be fixed, deceleration rotation through the carrier37may be performed. Since the carrier37may be supported by the first bearing82, a power loss may be reduced. Since the carrier37and the small-diameter gear shaft41may be axially coupled, the rotation power of the carrier37may be transferred to the small-diameter gear shaft41.

While the small-diameter gear42is rotated with the small-diameter gear shaft41, the large-diameter gear43may also be rotated. When the large-diameter gear43is rotated while being decelerated by the gear ratio, the hub inner race52spline-coupled to the large-diameter gear43may be rotated to rotate the wheel member60.

Hereafter, a process in which a load generated from the road is transferred to the vehicle body through the in-wheel working device1will be described.

A load generated while the vehicle travels on the road may be transferred to the wheel member60. The load transferred to the wheel member60may be transferred to the hub inner race52, and then transferred to the housing part20through the hub bearing53and the hub outer race51. The load transferred to the housing part20may be transferred to the vehicle body, after vibration or the like is attenuated by the lower arm62and the upper arm63.

The in-wheel working device1in accordance with the embodiment of the present invention may be assembled in the following order.

The stator core13and the stator coil14may be fixed to the motor housing11, and the double ball bearing81may be then installed. At the same time, the rotor core15may be fixed to the outside of the driving shaft16, and the resolver90may be then installed at the outside of the driving shaft16. Furthermore, the driving shaft16to which the resolver90is fastened may be installed in the motor housing11so as to assemble the module of the motor part10.

The motor part10may be fixed to the side surface of the housing part20, and then connected to the first speed reduction part30including the planetary gear35. The carrier37of the first speed reduction part30and the small-diameter gear shaft41of the second speed reduction part40may be connected to each other, and the large-diameter gear43may be then connected to the small-diameter gear42.

After the large-diameter gear43is coupled, the speed reducer cover100may be connected to the housing part20so as to stably support the small-diameter gear shaft41.

After the hub part50connected to the large-diameter gear43is installed, the braking disk70and the wheel member60may be connected to the hub inner race52such that the braking disk70and the wheel member60are rotated with the hub inner race52. The in-wheel working device1may be disassembled in the reverse order of the assembling process.

In accordance with the present embodiment, the first speed reduction part30connected to the motor part10may perform speed reduction, and the second speed reduction part40may then perform speed reduction. Thus, since a compact two-stage speed reduction device can be implemented, the size of the motor can be reduced while the driving force thereof may be doubled, which makes it possible to improve the flexibility of design. Furthermore, since the carrier37of the first speed reduction part30and the small-diameter gear shaft41of the second speed reduction part40are detachably installed, the stiffness can be secured while an axial deformation is reduced.

Furthermore, the in-wheel working device1in accordance with the present embodiment may constitute a compact two-stage speed reduction device, and thus reduce the size of the motor part10while doubling the driving force. Furthermore, the motor part10may be eccentrically disposed at the upper portion of the front side of the vehicle, and mounted on a double wishbone or MacPherson strut, and an existing disk brake can be used. The size reduction of the in-wheel working device1can improve the flexibility of design of the vehicle, and facilitate the maintenance operation. Furthermore, since a compact design can be achieved in the wheel member60, the compatibility with existing chassis parts can be improved to facilitate the assembling process.

Furthermore, since the speed reduction may be primarily and secondarily performed, the selection range of a speed reduction ratio can be widened. Thus, the weight of the in-wheel working device1can be reduced through the optimal design.

Furthermore, since the motor part10and the first speed reduction part30including the planetary gear35are located at the top of the rotational center axis66of the wheel member60, an interference with a chassis part can be reduced. Since the first speed reduction part30performing the primary speed reduction may be disposed in the motor part10, a separate housing for the first speed reduction part30may not be required to reduce the weight and size of the in-wheel working device1.

Furthermore, since the second speed reduction part40used for the secondary speed reduction may be connected to the hub part50like an existing drive shaft of a front wheel, the hub part50can be used without a change of the hub bolt55. Thus, the existing wheel member60can be just used to reduce the manufacturing cost.

Although exemplary embodiments of the present disclosure have been shown and described hereinabove, the present disclosure is not limited to specific exemplary embodiments described above, but may be various modified by those skilled in the art to which the present disclosure pertains without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims. In addition, such modifications should also be understood to fall within the scope and spirit of the present disclosure.