JP5750329B2 - Wheel drive device - Google Patents

Description

  The present invention relates to a wheel drive device that drives wheels of a vehicle.

  For example, Patent Document 1 discloses a power transmission device that drives a wheel of a forklift. The forklift disclosed in Patent Document 1 includes a motor and a speed reducer that decelerates rotation of the motor as a wheel driving device for driving the wheel.

  The speed reduction device has a speed reduction mechanism including a single-stage parallel shaft speed reduction mechanism and a simple planetary gear speed reduction mechanism. Among these, a part of the simple planetary gear speed reduction mechanism is disposed at a position entering the inner side in the radial direction of the wheel.

JP 2010-159794 A (FIG. 1)

  Forklifts have a large battery, and many accessories such as hydraulic pumps and tanks for raising and lowering the load on the fork. Therefore, if the limited space is not used effectively, the forklift will become unnecessarily large. End up. For this reason, there is a strong demand for a device for driving a wheel to be contained in a small space (close to the wheel) as much as possible.

  On the other hand, in the case of a forklift, since there is a fork for raising and lowering the load in front of the front wheels, a counter balance (counter weight) is arranged behind the center of gravity of the forklift. In order to reduce the size of the counter balance, the center of gravity of the fork and the load loaded on the fork must be as close as possible to the ground contact position of the front wheel. In this respect, the smaller the diameter of the forklift wheel, the better.

  Nevertheless, in order to support the heavy weight of the load mounted on the fork, the wheel tire (rubber part) itself must have a large volume. Therefore, the actual situation is that the space inside the wheel in the radial direction is very small.

  Against this backdrop, when trying to place the speed reducer in a position that is further intruded to the opposite side of the wheel, since the speed reducer has not so far reached the opposite side of the wheel, There has been a new problem that it becomes difficult to dispose the tube for injecting air (injection passage member for medium injected into the wheel), which has never been a problem.

  The present invention has been made to solve such a problem, and in a wheel drive device, a medium injected into a wheel while disposing a speed reducer on the side opposite to the vehicle body on the radially inner side of the wheel as much as possible. The problem is to rationally arrange the injection passage members.

The present invention is a wheel drive device that drives the wheel by an output rotation of a reduction gear disposed radially inside the wheel, wherein the reduction gear includes an output member coupled to the wheel, and the output member. and a pair of bearings for supporting, the pair of bearings, the side opposite to the vehicle body in bearings of which, smaller outer diameter than the body side of the bearing, radially outside the front SL side opposite to the vehicle body of the bearing, the The above-mentioned problem is solved by arranging a medium injection passage member for a medium injected into the wheel and having a contact angle smaller than that of the bearing on the vehicle body side .

  In the present invention, out of the pair of bearings supporting the output member of the reduction gear connected to the wheel, the outer diameter of the bearing on the anti-vehicle body side is made smaller than the outer diameter of the bearing on the vehicle body side. The space on the outer side in the radial direction of the bearing on the side opposite to the vehicle body is secured as a space for arranging the medium injection passage member.

  For this reason, this space can be utilized to draw out the medium injection passage member from the inside in the radial direction of the tire and guide it toward the side opposite to the vehicle body.

  According to the present invention, in the wheel drive device, it is possible to rationally arrange the injection passage member for the medium injected into the wheel while disposing the speed reducer on the side opposite to the vehicle body on the radially inner side of the wheel as much as possible.

Sectional drawing which shows the principal part which shows the structural example by which the reduction gear device which concerns on an example of embodiment of this invention is applied to the wheel drive device of a forklift Overall cross-sectional view of FIG. Side view of FIG. 2 is an overall cross-sectional view corresponding to FIG. 2 showing an example of another embodiment of the present invention. Side view of FIG. Sectional drawing equivalent to FIG. 1 showing an example of still another embodiment of the present invention

  Hereinafter, an example of an embodiment of the present invention will be described in detail based on the drawings.

  FIG. 1 is a cross-sectional view of an essential part showing a configuration example in which a reduction gear according to an example of an embodiment of the present invention is applied to a wheel drive device of a forklift, FIG. 2 is an overall cross-sectional view thereof, and FIG. FIG.

  The output shaft 12A of the motor 12 is connected to the input shaft 16 of the reduction gear G1 through the spline 14. The input shaft 16 is integrally formed with two eccentric bodies 18 and 20 that are offset from the input shaft 16.

  External gears 24 and 26 are fitted on the outer circumferences of the eccentric bodies 18 and 20 via bearings 21 and 23. The external gears 24 and 26 are in mesh with the internal gear 28.

  The internal gear 28 includes cylindrical internal teeth pins 28A and 28B constituting internal teeth, a holding pin 28C that passes through the internal teeth pins 28A and 28B and rotatably holds the pins, and the holding pins 28C. The internal gear main body 28D that is rotatably supported and integrated with the casing 30 is mainly configured.

  The number of internal teeth of the internal gear 28 (the number of internal pins 28A, 28B) is slightly larger (only 1 in this embodiment) than the number of external teeth of the external gears 24, 26.

  A flange body 34 fixed to the vehicle body frame 32 is disposed on the side of the external gears 24 and 26 in the axial direction, and the flange body 34 is disposed on the side opposite to the axial direction of the vehicle body via a carrier bolt 36 and a carrier pin 42. And a carrier body 38 integrated with each other. An inner pin 40 is formed integrally with the carrier body 38.

  The inner pin 40, together with the sliding promotion member 44, passes through the inner pin holes 24 </ b> A and 26 </ b> A formed through the external gears 24 and 26 with a gap, and is fitted in the recess 34 </ b> A of the flange body 34. The inner pin 40 is in contact with a part of the inner pin holes 24A, 26A of the external gears 24, 26 via the sliding promotion member 44, and restrains the rotation of the external gears 24, 26 ( Only swinging is allowed).

  The carrier pin 42 passes through the carrier pin holes 24B and 26B formed through the external gears 24 and 26 with a gap, and is in contact with the axial end of the flange body 34. However, the carrier pin 42 is not in contact with the carrier pin holes 24B, 26B of the external gears 24, 26 at all, and does not contribute to restraining the rotation of the external gears 24, 26.

  The input shaft 16 as an input member of the reduction gear G1 is rotatably supported by the flange body 34 and the carrier body 38 via a pair of angular ball bearings 52 and 54.

  The casing 30 which is an output member of the reduction gear G1 is connected to the vehicle body via a pair of main bearings (an outer bearing 46 positioned on the axially outer side (on the opposite side of the vehicle body) and an inner bearing 48 positioned on the axially inner side (the side of the vehicle body)). A flange body 34 and a carrier body 38 fixed to the frame 32 are rotatably supported. A wheel member 49 is connected to the end surface of the casing 30 on the side opposite to the vehicle body in the axial direction by bolts 47, and a wheel (tire) 50 of a forklift (not shown) 51 is mounted via the wheel member 49.

  In the present embodiment, the outer diameter d1 of the outer bearing 46 is smaller than the outer diameter d2 of the inner bearing 48. Here, the “outer diameter” refers to the outer diameter of the outer ring when there is an outer ring, and from the shaft center to the outermost periphery of the rolling element (the innermost diameter of the rolling surface) when the outer ring is integrally formed with the casing. Say the dimensions. An air injection tube (injection passage member for medium injected into the wheel) 60 is arranged in a space SP1 radially outside the outer bearing 46 formed with a small outer diameter d1.

  Hereinafter, this configuration will be described in detail.

  The outer bearing 46 is configured by a tapered roller bearing and includes an inner ring 46A, rolling elements 46B, and an outer ring 46C. The inner bearing 48 is an angular ball bearing, and includes an inner ring 48A, rolling elements 48B, and an outer ring 48C.

  In the present embodiment, as described above, the outer diameter d1 of the outer bearing 46 is smaller than the outer diameter d2 of the inner bearing 48. Further, the dimension L1 from the action point 46C1 of the outer bearing 46 to the axial center 50C1 of the wheel 50 is smaller than the dimension L2 from the action point 48C1 of the inner bearing 48 to the axial center 50C1 of the wheel (tire) 50 (L1). <L2). Here, the “action point” means the intersection of the action line (a straight line connecting the contact points of the rolling elements with the inner ring and the outer ring) and the axis line (a line passing through the axis and parallel to the axial direction). ing.

  For this reason, the outer bearing 46 is under a severer condition (receives a larger load) than the inner bearing 48. The outer diameter d1 of the outer bearing 46 is smaller than the outer diameter d2 of the inner bearing 48. For this reason, the types of the rolling elements 46B and 48B are different between the outer bearing 46 and the inner bearing 48, such that the rolling element 46B of the outer bearing is “conical roller” and the rolling element 48B of the inner bearing 48 is “ball”. Yes. Specifically, the outer bearing 46 having a severe load condition and a small diameter is a conical roller having a large rated load by line contact, and the inner bearing 48 having a severe load condition and a large diameter is a “ball” having a point contact and a small loss. It is said. This is because the intended load of the outer bearing 46 is larger than the rated load of the inner bearing 48 (although the outer diameter d1 of the outer bearing 46 is smaller than the outer diameter d2 of the inner bearing 48). is there. The “rated load” includes a basic static load rating and a basic dynamic load rating. In the present embodiment, the basic dynamic load rating is particularly larger for the outer bearing 46 than for the inner bearing 48. It is valid.

  In the present embodiment, by changing the types of the rolling elements 46B of the outer bearing 46 and the rolling elements 48B of the inner bearing 48, it is possible to suppress the outer bearing 46 from becoming extremely large. The space SP1 radially outside 46 can be more effectively secured. Note that “different types” as used herein does not simply mean that the sizes are different (not congruent but similar), but “the rolling elements themselves have different shapes”. .

  Further, the contact angle θ1 of the outer bearing 46 (the angle that the action line has in the radial direction) θ1 is set to be smaller than the contact angle θ2 of the inner bearing 48.

  The air injection tube (injection passage member for medium injected into the wheel) 60 is arranged in the space SP1 secured outside in the radial direction of the outer bearing 46 having the outer diameter d1 thus reduced. Yes.

  The “medium to be injected into the wheel” is usually “air”, but depending on the vehicle model, it may be “nitrogen” or a liquid or semi-solid medium so as not to puncture. Sometimes.

  In the present embodiment, the lead-out portion P1 from which the air injection tube 60 is pulled out from the inside of the wheel 50 is more axial than the connecting portion P2 between the casing 30 that is the output member of the reduction gear G1 and the wheel member 49 of the wheel 50. Located on the side.

  Therefore, in order to secure a wider space SP1 in which the tube 60 is disposed, a notch (groove) 30A in which the tube 60 is disposed is formed in the casing 30 of the reduction gear G1 along the axial direction. The wheel member 49 is formed with a hole 49A through which the tube 60 is inserted at a position corresponding to the notch 30A of the casing 30 (position facing the axial end of the notch 30A in the axial direction). The tube 60 drawn out from the lead-out portion P1 is bent toward the outside of the vehicle body, is stored in the notch 30A of the casing 30, and is drawn out of the wheel 50 through the hole 49A of the wheel member 49. Thereby, an air filling operation (medium injection operation) can be easily performed.

  Hereinafter, the operation of the reduction gear G1 according to this embodiment will be described.

  The rotation of the output shaft 12A of the motor 12 is transmitted to the input shaft 16 of the reduction gear G1 through the spline 14. When the input shaft 16 rotates, the eccentric bodies 18 and 20 (outer peripheries thereof) perform an eccentric motion, and the external gears 24 and 26 swing through the bearings 21 and 23. This swinging causes a phenomenon in which the meshing positions of the external gears 24 and 26 and the internal gear 28 are sequentially shifted.

  The difference in the number of teeth between the external gears 24 and 26 and the internal gear 28 is set to 1, and the rotation of each external gear 24 and 26 is caused by an internal pin 40 fixed to the body frame 32 side. It is restrained. For this reason, each time the input shaft 16 rotates once, the internal gear 28 rotates (rotates) by an amount corresponding to the difference in the number of teeth with respect to the external gears 24 and 26 whose rotation is restricted. . As a result, the casing 30 integrated with the internal gear main body 28 </ b> D rotates at a rotational speed reduced to 1 / (the number of teeth of the internal gear) by the rotation of the input shaft 16. The rotation of the casing 30 causes the wheels (tires) 50 of the forklift 51 to rotate through the wheel member 49 fixed to the casing 30 (by the bolt 47).

  Here, in this embodiment, the outer diameter d1 of the outer diameter of the outer bearing 46 out of the pair of outer bearing 46 and inner bearing 48 that supports the casing 30 that is the output member is larger than the outer diameter d2 of the inner bearing 48. It is formed small. And the tube 60 for air injection is arrange | positioned in space SP1 of the outer side of the radial direction of the outer side bearing 46 ensured by this.

  For this reason, in the present embodiment, a wide space SP1 in which the tube 60 is disposed can be secured while allowing the entire length of the reduction gear G1 in the axial direction to enter the inside of the wheel 50 in the radial direction. In other words, the air injection tube 60 can be reasonably disposed while disposing the speed reduction device G1 on the side opposite to the vehicle body on the radially inner side of the wheel 50 as much as possible.

  In the present embodiment, since the output member is the casing 30 of the reduction gear G1 (because it is a so-called frame rotation reduction gear), the casing 30, the wheel member 49, and the wheel (tire) 50 rotate relative to each other. There is no rotation. Therefore, the rotation phase does not shift between the three parties 30, 49, 50. Therefore, in the area A1 in FIG. 1 (the region on the vehicle body side of the plane perpendicular to the axis of the wheel member 49), the cutout 30A is formed only in the portion where the air injection tube 60 is disposed on the outer periphery of the casing 30. In addition, a hole 49 </ b> A is formed in the wheel member 49. Thereby, the strength of the casing 30 and the wheel member 49 is further improved (for example, as compared with a configuration method in which the entire circumference on the side opposite to the vehicle body is cut away from the step 230C as in the embodiment of FIG. 6 described later). ing. Note that, in the area A2 (the area on the side opposite to the vehicle body from the area A1), the casing 30 has a small diameter over the entire circumference, and a space for arranging the bolts 47 is secured.

  In the present embodiment, the dimension L1 from the action point 46C1 of the outer bearing 46 to the axial center 50C1 of the wheel (tire) 50 is from the action point 48C1 of the inner bearing 48 to the axial center 50C1 of the wheel 50. It is smaller than the dimension L2 (L1 <L2). Therefore, this arrangement is a severe arrangement for the outer bearing 46 coupled with the small outer diameter d1 of the outer bearing 46.

  However, in the present embodiment, since the outer bearing 46 has a larger rated load than the inner bearing 48, the load from the wheel 50 side is supported in a stable state (although the outer diameter d1 of the outer bearing 46 is small). can do.

  In addition, in this embodiment, since the types of the rolling elements 46B and 48B are changed between the outer bearing 46 and the inner bearing 48 (conical rollers and balls), the rolling element 46B of the outer bearing 46 is particularly enlarged. No (that is, while ensuring a large space SP1 radially outside the outer bearing 46), the rated load of the outer bearing 46 can be increased.

  Note that the rated load of the bearing on the side opposite to the vehicle body can be made larger than the rated load of the bearing on the vehicle body side without changing the type of rolling element of the bearing. For example, both types of bearings are the same (for example, both are angular ball bearings, or both are tapered roller bearings), and the diameter and roller length of the rolling element of the bearing on the opposite body side are set to the diameter and roller length of the bearing on the body side. You may employ | adopt the method made larger than. Further, by changing the contact angles θ1 and θ2 between the outer bearing 46 and the inner bearing 48, the balance between the radial load and the thrust load can be adjusted. The load can be increased.

  4 and 5 show an example of another embodiment of the present invention.

  Also in this embodiment, the outer diameter d101 of the outer bearing 146 is smaller than the outer diameter d102 of the inner bearing 148 among the pair of main bearings supporting the casing 130 as the output member (d101 and d102 are the previous ones). Same as embodiment d1 and d2). An air injection tube 160 is arranged in a space SP101 radially outside the outer bearing 146 in which the outer diameter d101 is kept small.

  However, in the previous embodiment, the lead portion P1 from the wheel 50 of the tube 60 for injecting air is positioned closer to the vehicle body side in the axial direction than the connecting portion P2 between the casing 30 of the reduction gear G1 and the wheel member 49 of the wheel 50. However, in the present embodiment, the lead-out portion P101 of the tube 160 from the wheel 150 is positioned closer to the vehicle body side in the axial direction than the connecting portion P102 between the casing 130 as the output member and the wheel member 149. Yes.

  In this configuration, the center position in the axial direction of the wheel 150 is slightly closer to the vehicle body side than in the previous embodiment (in this embodiment, only a part of the total axial length of the speed reducer is the wheel 150. However, there is a tendency that a slight dead space is formed inside the wheel 150 in the radial direction, but a notch (groove) is formed in the casing 130 to avoid interference with the air injection tube 160. It is not necessary to form a hole for inserting the tube 160 in the surface orthogonal to the axial direction of the wheel member, the structure is simpler, and the manufacturing cost can be reduced as compared with the previous embodiment. it can.

  Since this embodiment is the same as the previous embodiment except for the structure around the casing 130 and the wheel member 149, the same or similar members as those of the previous embodiment in the figure are compared with the previous embodiment and the lower 2. Only the same reference numerals are assigned to the digits, and the duplicate description is omitted.

  FIG. 6 shows an example of still another embodiment of the present invention.

  In both of the above-described embodiments, a so-called frame rotation speed reduction mechanism (a speed reduction mechanism in which the casings 30 and 130 serve as output members) is employed. However, in the present embodiment, the casing 230 includes the body frame 232. It is fixed to. A flange body 234 synchronized with the rotation of the external gears 224 and 226, a carrier body 238 integrated with the flange body 234, and a cover body 282 integrated with the carrier body 238 via the spline 280. The entirety constitutes a hub block 284 as an output member.

  The hub block 284 is supported by a pair of main bearings, that is, an outer bearing 246 positioned on the opposite side of the vehicle body in the axial direction and an inner bearing 248 positioned on the side of the vehicle body in the axial direction. Also in this embodiment, the outer diameter d201 of the outer bearing 246 is smaller than the outer diameter d202 of the inner bearing 248, and the air injection tube is placed in the space SP201 radially outside the outer bearing 246 having a smaller outer diameter d202. 260 is arranged.

  Since the wheel 250, the tube 260, and the wheel member 249 move integrally (not relatively rotated), the tube 260 is pulled out from a hole 249A formed in the wheel member 249. On the other hand, since the casing 230, the wheel 250, the tube 260, and the wheel member 249 rotate with each other, a configuration is provided in which a cutout is provided only in a portion of the casing 230 where the air injection tube 260 is disposed. It cannot be adopted. Therefore, in this embodiment, a step 230 </ b> C is formed over the entire circumference of the casing 230 in a substantially axially half region of the casing 230 (so that the tube 260 and the casing 230 do not interfere with each other).

  In the present embodiment, the pair of main bearings (supporting the output member) are the outer bearing 246 and the inner bearing 248, both of which are angular ball bearings, and the rolling elements 246B and 248B are the same. Consists of types of “balls”. The inner ring of the outer bearing 246 is also used by the cover body 282, and the inner ring of the inner bearing 248 is also used by the flange body 234.

  Further, in this embodiment, the rolling elements 246B of the outer bearing 246 and the rolling elements 248B of the inner bearing 248 have the same diameter d203, d204, and the contact angles θ201, θ202 of both bearings 246, 248 are also the same. Yes.

  In this embodiment, the dimension L201 from the action point 246C1 of the outer bearing 246 to the axial center 250C1 of the wheel 250 is equal to the dimension L202 from the action point 248C1 of the inner bearing 248 to the axial center 250C1 of the wheel 250; Even if the angular ball bearings according to the same rolling elements 246B and 248B are used (although the inner bearing 248 is slightly excessive in quality), there is no particular problem because it is not so different as in the above embodiment. This is based on the reason. By using angular ball bearings having the same type of rolling elements 246B and 248B of low cost as the outer bearing 246 and the inner bearing 248, the cost can be further reduced. Further, the transmission loss is small as compared with the case of using a conical roller.

  Thus, in the present invention, the types of rolling elements of the pair of bearings that support the output member are not necessarily changed. In particular, when the dimension from the bearing point of the bearing on the opposite side of the vehicle to the center of the wheel in the axial direction is larger than the dimension from the point of bearing of the bearing on the side of the vehicle to the center of the wheel in the axial direction, Since the load is relatively light, the same type of rolling element may be used.

  Of course, for example, in the embodiment of FIG. 6 as well, an angular ball bearing having a rolling element having a larger diameter (by the same type of ball) is used as the outer bearing, or a tapered structure having a rolling element by a different type of conical roller. It is free to increase the rated load of the outer bearing by using a roller bearing.

  Other configurations are the same as those in the previous embodiment. Therefore, the same or similar members as those in the previous embodiment are designated by the same reference numerals in the last two digits as in the previous embodiment. Omitted.

  In the above-described embodiments, the eccentric oscillating planetary gear mechanism having an eccentric body on the input shaft arranged at the center of the external gear is employed as the speed reduction mechanism. However, in the present invention, the speed reduction mechanism The structure of the mechanism is not particularly limited. For example, an eccentric oscillating planetary gear mechanism in which the external gear oscillates by simultaneously rotating a plurality of eccentric body shafts at a position offset from the center of the external gear may be used. Moreover, a simple planetary gear reduction mechanism, a parallel axis reduction mechanism, an orthogonal axis reduction mechanism, or the like may be used, or a combination thereof.

  Moreover, in the said embodiment, although the example which applied the wheel drive device which concerns on this invention to the forklift was shown, the wheel drive device which concerns on this invention can apply widely also to vehicles other than a forklift. it can.

  Moreover, in the said embodiment, although the notch 30A was formed along the axial direction, it is not limited to this, For example, you may form diagonally with respect to the axial direction.

DESCRIPTION OF SYMBOLS 16 ... Input shaft 18, 20 ... Eccentric body 21, 23 ... Bearing 24, 26 ... External gear 28 ... Internal gear 30 ... Casing 34 ... Flange body 38 ... Carrier body 46 ... Outer bearing 48 ... Inner bearing 49 ... Wheel member 50 ... wheel

Claims (6)

A wheel driving device for driving the wheel by output rotation of a reduction gear disposed radially inside the wheel,
The speed reducer includes an output member coupled to the wheel, and a pair of bearings that support the output member,
Among the pair of bearings, a bearing on the side opposite to the vehicle body has a smaller outer diameter than a bearing on the vehicle body side ,
An injection passage member for a medium injected into the wheel is arranged on a radially outer side of the bearing on the side opposite to the vehicle body , and
The wheel drive device according to claim 1, wherein the bearing on the side opposite to the vehicle body has a smaller contact angle than the bearing on the vehicle body side . In claim 1,
The wheel drive device according to claim 1, wherein the rolling element of the bearing on the opposite side of the vehicle body is different from the type of rolling element of the bearing on the vehicle body side. In claim 1 or 2,
The dimension from the working point of the bearing on the vehicle body side to the axial center of the wheel is not less than the dimension from the working point of the bearing on the vehicle body side to the axial center of the wheel,
The wheel drive device according to claim 1, wherein the bearing on the side opposite to the vehicle body has a larger rated load than the bearing on the vehicle body side. In any one of Claims 1-3 ,
The wheel drive device according to claim 1, wherein a lead-out portion of the injection passage member from the wheel is closer to an axial vehicle body than a connection portion between the output member of the reduction gear and the wheel member of the wheel. In any one of Claims 1-4 ,
The wheel drive device according to claim 1, wherein the output member is a casing of the speed reduction device, and a notch in which the injection passage member is disposed is formed on an outer periphery of the casing. In claim 5 ,
A wheel drive device, wherein a hole for inserting the injection passage member is formed in a position corresponding to the notch of the casing in a wheel member of the wheel connected to the casing.

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