WO2012128583A2

WO2012128583A2 - Transmission and in-wheel driving system for motor vehicle with the same

Info

Publication number: WO2012128583A2
Application number: PCT/KR2012/002103
Authority: WO
Inventors: Youngjun Kim; Takhyun KIM; Jungin Lee
Original assignee: Central Corp
Current assignee: Central Corp
Priority date: 2011-03-23
Filing date: 2012-03-23
Publication date: 2012-09-27
Anticipated expiration: 2013-09-23
Also published as: WO2012128583A3

Abstract

There is disclosed a transmission and an in-wheel driving system for a vehicle with the same, the transmission including a drive shaft rotated by a rotational torque; a clutch co-rotated with the drive shaft, the clutch held in axially slidable connection with the drive shaft and having a driving force transmitting mechanism formed at at least one face thereof; and a push rod connected to the clutch, the push rod moving the clutch in an axial direction.

Description

TRANSMISSION AND IN-WHEEL DRIVING SYSTEM FOR MOTOR VEHICLE WITH THE SAME

Embodiments of the invention relates to a transmission and an in-wheel driving system for a motor vehicle with the same.

In general, an electric vehicle driven by a battery powered motor is smaller than a conventional fossil-fuel vehicle or a natural gas vehicle by the weight as well as the size.

As requirements of electric vehicle development there have been under progress studies on the decrease of the vehicle weight and size and development of an appropriate transmission for such an electric vehicle, together with improvement of the running speed and fuel efficiency, improvement of a charging method and a battery life.

A transmission for the conventional fossil-fuel vehicle or the natural gas vehicle can have a variety of structures. The transmission is typically constructed with a clutch engaged with a number of gears. Conventional structures for linearly transporting the clutch between the gears are complicated. Such structures necessarily result in a heavy weight and large volume, and large gear shifting shocks.

The conventional transmission consumes much energy because of the heavy weight and large volume and it is not appropriate for the electric vehicle accordingly. Also, the conventional transmission has a major disadvantage of gear shifting shocks.

As a result, there are demands for a transmission capable of reducing the weight and volume as much as possible and an in-wheel driving system for a vehicle with the same.

In an embodiment, a transmission may include a drive shaft rotated by a rotational torque.

Also, the transmission may include a clutch co-rotated with the drive shaft, the clutch held in axially slidable connection with the drive shaft.

The transmission may include a push rod connected to the clutch, the push rod moving the clutch in an axial direction.

In this instance, the power source of the roatational torque may be a motor. In this instance, the drive shaft may be connected with the motor to receive the rotational force therefrom.

The drive shaft may pass through the clutch.

A driving force transmitting mechanism may be formed at a face or the other opposite face of the clutch. The face and the other opposite face may be disk faces of the clutch arranged in both sides with respect to a circumferential surface of the clutch.

Also, the drive shaft may include a hollow section and the push rod may be inserted in the hollow section. The predetermined portion of the push rod inserted in the hollow section of the drive shaft may be connected with the clutch.

The push rod may be connected with the clutch in rotational non-restricting relation. In other words, the push rod may not affect the rotation of the clutch at all. One example of the connecting relation may be a connecting relation generated by a bolt joint.

For the connection between the push rod and the clutch, a plurality of through-holes may be longitudinally formed in the hollow section of the drive shaft in an axial direction. A plurality of spokes extended outside the hollow section of the drive shaft via the plurality of the through-holes may be further provided to be coupled to the clutch. In this instance, the spokes may be connected with the push rod in a rotational non-restricting relation.

An input gear may be provided adjacent to a side or the other opposite side of the clutch, with being selectively connected with the driving force transmission mechanism, to receive the driving force as the clutch is sliding along an axial direction. A through hole may be formed in the center of the input gear to pass the drive shaft there through. The through-hole may have a sufficient size enough not to affect the rotation of the drive shaft.

Such the input gear may include a gear mechanism having a plurality of gears.

In other words, velocity variation of the gear mechanism may be enabled by the operation of the clutch and the varied rotational number may be output as a predetermined deceleration ratio.

In this instance, the input gear of the gear mechanism may include a first input gear coaxially arranged adjacent to the side of the clutch, the first input gear selectively connected to a firts driving force transmitting mechanism formed in one face of the clutch to receive a driving force. The input gear may further include a second input gear formed in a hollow shape to pass the push rod there through. The second input gear may be coaxially arranged adjacent to the other opposite side of the clutch to be selectively connected to a second driving force transmitting mechanism formed in the other opposite face of the clutch to receive the driving force. The second input gear may have a different number of gear teeth from a number of gear teeth formed in the first input gear.

The gear mechanism may include a third gear to engage with the first input gear, and a fourth gear connected to co-rotate with the third gear. The fourth gear may engage with the second input gear and have a different number of gear teeth from a number of gear teeth formed in the third gear.

A plurality of the third gears and a plurality of the fourth gears may be provided to surround the first input gear and the second input gear, respectively. In other words, the first input gear and the second input gear may be sun gears. The third and fourth gears may be arranged around the first input gear and the second input gear, respectively. In this instance, the first input gear and the second input gear may a sun gear. However, in this embodiment, the third gears and the fourth gears may not revolve around the first input gear and the second input gear.

Meanwhile, the gear mechanism may further include a fifth gear coaxially arranged with respect to the input gear to receive a rotational force from the input gear. The fifth gear may be formed in a hollow shape to pass the push rod there through.

The fifth gear may be directly connected with the second input gear of the input gear in an axial direction.

Meanwhile, the gear mechanism may include a sixth gear to engage with the fifth gear; and a seventh gear connected to co-rotate with the sixth gear, with a different number of gear teeth from a number of gear teeth formed in the sixth gear. The sixth gear and the seventh gear may be a compound gear.

A plurality of the sixth gears may be provided to surround the fifth gear. In other words, the sixth gears may be connected with the fifth gear that is employed as a sun gear. However, the sixth gear may not revolve around the fifth gear and it may be supported by a bearing supporting structure of a housing to rotate on its axis at a fixed position.

Also, the gear mechanism may include a ring gear having an inner circumference to engage with the plurality of the seventh gears.

Such the ring gear may be connected with a wheel of a vehicle. Accordingly, the rotation of the ring gear may rotate the wheel of the vehicle. Alternatively, the seventh gear may be directly connected with the wheel of the vehicle. In this instance, a compound gear composed of the seventh gear and the sixth gear may be a planet gear to revolve around the fifth gear.

Meanwhile, the driving force transmitting mechanism may be a projection projected from a face or the other opposite face of the clutch. A corresponding recess may be formed in the input gear to allow the projection therein.

The projection may be a ball insertedly provided in the face or the other opposite face of the clutch. The ball may be elastically suspended by a washer spring provided in the clutch.

Meanwhile, in an embodiment of the invention, an in-wheel driving system for a vehicle may include the transmission mentioned above. The drive shaft of the transmission may be connected with a driving motor. The transmission may be connected with a vehicle wheel to transmit a rotational force. Accordingly, the rotational force of the driving motor may be transmitted to the vehicle wheel via the transmission.

The embodiments have following advantageous effects. The transmission mentioned above may have an effect of a simple structure, a smaller volume and a smaller weight.

Such a compact structure may consume less energy and it may be applicable to an electric vehicle.

Furthermore, the structure may be compact-sized to be fitted to a small-sized vehicle.

Arrangements and embodiments may be described in detail with reference to the following drawings in which like reference numerals refer to like elements and wherein:

FIG. 1 is a perspective view partially illustrating a transmission according to an embodiment of the invention;

FIG. 2 is a sectional view illustrating a coupling state of the transmission shown in FIG. 1;

FIG. 3 is a sectional view illustrating a coupling state among a hollow drive shaft, a push rod and a clutch shown in FIG. 1;

FIG. 4 is a sectional view illustrating a detailed connectional relation of a first clutch ball shown in FIG. 2;

FIGS. 5 and 6 are diagrams illustrating embodiments of a connectional structure between the push rod and a spoke (or a clutch); and

FIG. 7 is a diagram illustrating an in-wheel driving system for a vehicle according to an embodiment of the invention.

As follows, embodiments will be described in detail to be embodied by those skilled in the art to which the embodiments pertain to, in reference to the accompanying drawings. A transmission according to embodiments of the invention will be described in detail as follows and a transmission which will be described as follows may be used for a vehicle.

FIG. 1 is a perspective view partially illustrating a transmission according to an embodiment of the invention. FIG. 2 is a sectional view illustrating a connecting state of the transmission shown in FIG. 1.

The transmission is rotated by a driving motor 1 and it may include a hollow drive shaft 10 having a splines 10 formed in an outer surface thereof along a longitudinal direction.

The transmission may include a push rod 20 inserted in the hollow drive shaft 10, with being movable along the longitudinal direction of the hollow drive shaft 10 by a stepping motor 100. For the longitudinal movement of the push rod 20, the push rod 20 may have a thread engaged with the stepping motor 100. The thread of the push rod 20 may be engaged with a housing or a shaft of the motor 100 such that the push rod 20 longitudinally moves as the motor 100 rotates.

In addition, there may be further provided a clutch 30 engaged with a splines 11 of the hollow drive shaft 10 to co-rotate with the hollow drive shaft 10. The clutch 30 may be also coupled to the push rod 20 via an opening 12 provided in a predetermined portion of the hollow drive shaft 10 to be movable along the longitudinal direction with respect to the hollow drive shaft 10. In this instance, the opening 12 is a through hole longitudinally formed along an axial direction and the plurality of the openings 12 may be formed along a circumferential direction.

A plurality of first clutch balls 31 may be provided in a face of the clutch 30 with spaced apart the same distance from a rotational center of the hollow drive shaft 10.

In addition, a plurality of second clutch balls 32 may be provided in the other opposite face of the clutch 30 with spaced farther from the rotational center of the hollow drive shaft 10 than the first clutch balls 31.

A first input gear 40 is located adjacent to a side of the clutch 30 and the hollow drive shaft 10 passes through a center of the first input gear 40. Also, the first clutch ball 31 is inserted in the first input gear 40 as the clutch 30 moves toward the first input gear 40. The first input gear 40 is rotated by the rotational force transmitted from the hollow drive shaft 10 via the first clutch ball 31. A second input gear 50 is located adjacent to the other opposite side of the clutch 30 and the hollow drive shaft 10 passes through a center of the second input gear 40. The second clutch ball 32 is inserted in the second input gear 50 as the clutch 30 moves toward the second input gear 50. The second input gear 50 is rotated by a rotational force transmitted from the hollow drive shaft 10 via the second clutch ball 32. The second input gear 50 has a larger diameter and a larger number of gear teeth than the first input gear 40.

A third gear 61 and a fourth gear 62 to engage with the first input gear 40 and the second input gear 50, respectively, may compose a first compound gear 60. A rotational number of the first compound gear 60 may be variable according to a gear ratio with the first input gear 40 or the second input gear 50. Although FIG. 1 shows a single first compound gear 60, three first compound gears 60 may be arranged at intervals of 120 degrees. The first input gear 40 and the second input gear 50 may a sun gear. However, in this embodiment, the first compound gear 60 may not revolve around the first input gear 40 and the second input gear 50, and it may rotate on its axis at a fixed position supported by a bearing structure of a housing.

The third gear 61 has a larger diameter and a larger number of gear teeth than the fourth gear 62. Also, the third gear 61 has a smaller number of gear teeth than the second input gear 50 and the third gear 61 has the same number of gear teeth as the first input gear 40.

A fifth gear 70 is axially connected to the second input gear 50 and an axial connecting part 71 is formed in the fifth gear 70 for the axial connection. A corresponding portion of the second input gear 50 is inserted in the axial connecting part 70 for the axial connection. The fifth gear 70 has a hollow section 73. Accordingly, the push rod 20 passes through the fifth gear 70 to be connected to a stepping motor 100. The fifth gear 70 is supported at the axial connecting part 71 and an end 74 located in opposite to the axial connecting part 71 by the bearing supporting structure of the housing.

In this instance, the fifth gear 70 has a smaller number of gear teeth than the second input gear 50.

A sixth gear 82 engages with a gear 72 formed in outer circumference of the fifth gear 70. The sixth gear 82 may form a second compound gear 80, together with a seventh gear 83. The second compound gear 80 is supported at both ends 81 and 84 thereof by a bearing supporting structure of the housing. Three second compound gears 80 are arranged at intervals of 120 degrees, with surrounding the gear 72 of the fifth gear 70.

The sixth gear 82 has a larger diameter and a larger number of gear teeth than the seventh gear 83, and it has a larger number of gear teeth than the fifth gear 70.

The fifth gear 70 and the second compound gear 80 have a relation that is similar to a relation between a sun gear and a planet gear. However, the second compound gear 80 may only rotate on its axis and it may not revolve around the fifth gear 70.

Meanwhile, the seventh gear 83 engages with a ring gear 90. The seventh gear 83 engages with a gear 91 formed in an inner circumference of the ring gear 90. An outer circumferential surface of the ring gear 90 may be supported by a bearing supporting structure of a housing.

When such the transmission mentioned above is applied to an in-wheel drive system for a vehicle, the ring gear 90 may be connected to a vehicle wheel. Accordingly, the ring gear 90 may co-rotate with the vehicle wheel.

The configuration and operation of the transmission will be described in detail as follows.

A driving force of the driving motor 1 is transmitted to the hollow drive shaft 10, to rotate the hollow drive shaft 10.

The hollow drive shaft 10 may be pipe-shaped, with a plurality of spliness 11 projected from an outer face thereof in a longitudinal direction. Also, a plurality of openings 12 having a predetermined longitudinal length may be formed in another surface of the hollow drive shaft 10, with no splines 11 formed therein.

FIG. 3 is a sectional view illustrating a coupling state among a hollow drive shaft, a push rod and a clutch shown in FIG. 1.

In reference to FIGS. 1, 2 and 3, a push rod 20 is inserted in the hollow drive shaft 10 and the push rod 20 performs linear reciprocating movement at a predetermined interval along a longitudinal direction within the hollow drive shaft 10 by the operation of a stepping motor 100 generating an auxiliary driving force. The stepping motor 100 may be fixed to the housing.

In this instance, a hydraulic cylinder may substitute for the stepping motor 100. Spokes 21 is coupled to an end of the push rod 20 and the spokes 21 are projected outwardly via the openings 21 of the hollow drive shaft 10. Also, the spokes 21 are fixedly inserted in a recess provided in a face of the clutch 30. The spokes 21 may be connected with the push rod 20 in a rotational non-restricting relation. For example, the push rod 20 and the spokes 21 may be connected with each other by a rolling bearing 22 as shown in FIG. 5 or by a ball joint 22 as shown in FIG. 6. Alternatively, the spokes 21 may be connected with the push rod 20 in a rotational restricting relation in a case where a thread of the push rod 20 is engaged with a corresponding thread of a shaft of the motor 100.

The clutch 30 has inner splines to engage with the spliness 11 of the hollow drive shaft 10.

Accordingly, the clutch 30 engaging with the spliness 11 rotates as the hollow drive shaft 10 rotates. The clutch 30 may be reciprocated along the longitudinal direction of the hollow drive shaft 10 by the axial movement of the push rod 20 during the rotation of the clutch 30.

In this instance, the splines 11 may be employed to transmit the rotational force and to guide the linear movement of the clutch 30 simultaneously.

The first input gear 40 may be located adjacent to a left side of the clutch 30 and the second input gear 50 may be located adjacent to a right side of the clutch 30. The hollow drive shaft 10 passes through the center of the first input gear 40 and it is inserted in the center of the second input gear 50. However, the hollow drive shaft 10 is spaced apart a predetermine distance from the first input gear 40 and the second input gear 50, not to directly transmit the rotational force of the hollow drive shaft 10 to them.

When the clutch 30 is located between the first input gear 40 and the second input gear 50 in this state, the rotational force of the hollow drive shaft 10 is in a neutral condition configured to transmit the rotational force of the hollow drive shaft 10 to neither of the first input gear 40 and the second input gear 50.

When the push rod 20 is moving left, the clutch 30 is moving toward the first input gear 40 and the first clutch balls 31 of the clutch 30 are inserted in the recesses 41 provided in the first input gear 40, to transmit the rotational force of the clutch 30 to the first input gear 40.

A vehicle in the neutral condition may be stationary. Accordingly, the first input gear 40 may be coupled to the clutch 30 in the stationary state and gear-shifting shocks will not be generated because there is no difference in the relative rotational speed.

When the driving at a small gear ratio is required by a predetermined speed reached by the hollow drive shaft 10, the push rod 20 is retreating to move the clutch 30 to a position corresponding to the neutral condition that is adjacent to the second input gear 50. After that, the rotational speed of the hollow drive shaft 10 is fitted to that of the second input gear 50 based on information of each speed sensor and then the clutch 30 is pushed slowly, to seat the second clutch balls 32 in the recesses 51 of the second input gear 50 in a state of little gear-shifting shocks. The clutch 30 may rotate the second input gear 50 without decelerating the driving speed of the hollow drive shaft 10 through the deceleration ratios between the first input gear 40 and the third gear 61 and between the second input gear 50 and the fourth input gear 62.

Meanwhile, when a high deceleration ratio is required, the push rod 20 is advancing to move the clutch 30 to a position corresponding to a neutral condition that is adjacent to the first input gear 40. After that, the speed of the hollow drive shaft 10 is fitted to information of each speed sensor and the clutch 30 is pushed slowly, to seat the first clutch balls 31 in the recesses 41 of the first input gear in a state of little gear-shifting shocks. Accordingly, the clutch 30 may rotate the second input gear 50, with decelerating the driving force of the hollow drive shaft 10 according to a value gained by multiplying a deceleration ratio between the first input gear 40 and the third gear 61 by a deceleration ratio between the fourth gear 62 and the second input gear 50.

The rotation of the second input gear 50 may be transmitted to the ring gear 92 via the fifth gear 70 and the second compound gear 80. In this instance, the rotational force may be additionally decelerated via the fifth gear 70 and the second compound gear 80.

FIG. 4 is a sectional view partially illustrating the clutch 30 having the first clutch ball 31 inserted therein.

In reference to FIG. 4, the first clutch ball 31 is inserted in the recess 33 provided in the clutch 30. a washer spring 34 may be provided on a bottom surface of the recess 33 to elastically reduce a shock and noise, when the first clutch ball 31 contacts with a lateral surface of the first input gear 40, not being inserted in the recess 410 of the first input gear 40. Accordingly, wear and tear of the first input gear 40 or the first clutch balls 31 may be reduced.

The first clutch ball 31 may be fixed by a ring cage 35 coupled to a lateral surface of the recess 33.

The second clutch ball 32 may be also inserted in the recess and a washer spring provided in the recess may perform elastic suspending, like the connecting of the first clutch ball 31 mentioned above.

In this instance, each of the gears mentioned above may be a spur gear or a helical gear. Such a helical gear has a good action ratio, compared with such a spur gear. Accordingly, the helical gear has smooth and quiet rotation and it is used for the transmission.

The embodiment of the invention may provide the transmission that is proper to the electric vehicle because of the reduced weight and volume thereof by simplifying the structure.

Meanwhile, FIG. 7 shows an in-wheel driving system having the transmission described above applied thereto.

The transmission used for the in-wheel driving system shown in FIG. 7 may be a little bit different from the transmission described above. Especially, gears provided in the transmission used for the in-wheel driving system of FIG. 7 may be helical gears.

First of all, a driving motor 1 is directly connected with a drive shaft 10 of the transmission. In other words, a motor shaft of the driving motor 1 is directly connected with the drive shaft 10. A ring gear 90 of the transmission is connected with a vehicle wheel 4. Accordingly, the ring gear 90 is co-rotated with the vehicle wheel 4 and a tire 3 is coupled to an outer circumference of the vehicle wheel 4.

The ring gear is fastened to a wheel disk of the vehicle wheel 4 by a bolt.

The rotational torque of the driving motor 1 is transmitted to the transmission via the drive shaft 10 and to the vehicle wheel 4 via the ring gear 90 after that.

In this instance, as shown in FIG. 7, the driving motor 1 may be located outer to an internal space of the vehicle wheel 4. Two thirds or more of the transmission is located in the internal space of the vehicle wheel 4 and a predetermined portion of the transmission is projected inwardly along a width direction of the vehicle, to be located outer to the internal space of the vehicle wheel 4. Meanwhile, different from what is shown in FIG. 7, the transmission may be received in the internal space of the vehicle wheel 4.

The driving motor 1 and the transmission may be fitted to the vehicle wheel compactly. Accordingly, the compact in-wheel driving system may be achieved.

The embodiment of the invention relates to the transmission and the in-wheel driving system for the vehicle with the same. Such the compact structure can consume less energy and it may be applicable to an electric vehicle. Also, the structure may be compact-sized to be fitted to a small-sized vehicle.

Claims

A transmission comprising:

a drive shaft rotated by a rotational torque;

a clutch connected to receive a rotational force from the drive shaft;

a first input gear arranged at a side of a rotational axis of the clutch;

a second input gear arranged at the other opposite side of the rotational axis of the clutch; and

a push rod connected to the clutch to move the clutch in an axial direction to engage the clutch with the first input gear or the second input gear, the push rod passing through the second input gear.
The transmission according to claim 1, wherein the drive shaft passes through the clutch and the clutch is slidable along the drive shaft.
The transmission according to claim 1, wherein the drive shaft passes through the first input gear to be connected to the clutch.
The transmission according to claim 1, wherein the push rod is inserted in a hollow section of the drive shaft to be connected to the clutch.
The transmission according to claim 1, wherein the first input gear, the second input gear, the drive shaft and the clutch are arranged coaxially.
The transmission according to claim 1, further comprising:

a plurality of third gears to surroundingly engage with the first input gear;

a plurality of fourth gears to surroundingly engage with the second input gear, each of the fourth gears connected to co-rotate with each of the plurality of the third gears and having a different number of gear teeth from a number of gear teeth formed in each of the third gears.
The transmission according to claim 6, further comprising:

a fifth gear formed in a hollow shape to pass the push rod there through, the fifth gear axially connected with the second input gear, with a gear formed in an outer circumferential thereof.
The transmission according to claim 6, further comprising:

a plurality of sixth gears to surroundingly engage with the fifth gear; and

a plurality of seventh gears connected to co-rotate with the plurality of the six gears, respectively, each of the seventh gears having a different number of gear teeth from a number of gear teeth formed in each of the sixth gears.
The transmission according to claim 8, further comprising:

a ring gear having an inner circumference engaged with the plurality of the seventh gears.
An in-wheel driving system for a vehicle comprising:

the transmission according to one of claims 1 to 9;

a wheel driving motor connected with the drive shaft of the transmission; and

a vehicle wheel connected to the transmission to receive a rotational force.