JP2013170669A - Planetary reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of buckling of contact surfaces between connecting members which connect a pair of carrier bodies and the carrier bodies in a planetary reduction gear.SOLUTION: A reduction gear 10 includes first and second carrier bodies 34, 38 disposed on both axial sides of external gears (planetary gears) 24, 26 and a plurality of carrier pins 42, which are inserted through carrier pin holes 24B, 26B formed in the external gears 24, 26 to connect the carrier bodies 34, 38. Each of the carrier pins 42 has a contact part 42C in contact with the axial inside surface of the carrier body 34. The diameter of the contact part 42C is made larger than other parts of the carrier pin 42, and a counterbore 34B is formed in the carrier body 34 in a portion in contact with the contact part 42C.

Description

  The present invention generally relates to a reduction gear, and more particularly to a planetary reduction gear using a planetary gear mechanism.

  A pair of carrier bodies arranged on both sides in the axial direction of the oscillating external gear, a plurality of internal pins arranged between the two carrier bodies through pin holes formed in the external gear, and the internal gear 2. Description of the Related Art A swinging intermeshing type planetary speed reducer having meshing internal gears is known. In this speed reducer, the external gear functions as a so-called planetary gear, and the relative rotation between the external gear and the internal gear is extracted as a deceleration output. Patent Document 1 discloses a railway vehicle drive unit in which such a planetary speed reducer is incorporated.

JP 2010-169247 A

  In the technique described in Patent Document 1, an inner pin that connects a pair of carrier bodies has a central large-diameter portion and small-diameter portions at both ends in the axial direction, and a male screw formed on the outer peripheral surface of the small-shaped portion is a carrier. Fastened to the body. And the level | step-difference part diameter-reduced from a large diameter part to a small diameter part is contact | abutted with the surface of a carrier body. In this structure, axial compressive stress due to fastening and bending stress due to vehicle weight act on the inner pin. Therefore, high compressive stress may act on the contact surface of the carrier body, and the contact surface may be buckled.

  The present invention has been made in view of such a situation, and an object of the present invention is to reduce the possibility of buckling of the contact surface between the connecting member and the carrier body for connecting the pair of carrier bodies in the planetary speed reducer. It is to provide.

  A planetary speed reducer according to an aspect of the present invention includes a pair of carrier bodies arranged on both sides in the axial direction of the planetary gear, and a plurality of connecting members that couple the pair of carrier bodies. The connecting member has an abutting portion that abuts against the inner side surface of the carrier body in the axial direction, and the abutting portion has a diameter larger than the portions on both sides in the axial direction adjacent to the corresponding contacting portion.

  According to this aspect, the contact surface area of the carrier body that comes into contact with the connecting member can be increased by providing the contact portion that is expanded in diameter in the connecting member that connects the pair of carrier bodies. The compressive load per unit area applied to the surface decreases, and the possibility that the seating surface buckles can be reduced.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, in the planetary reduction gear, it is possible to reduce the possibility that the contact surface between the connecting member that connects the pair of carrier bodies and the carrier body buckles.

It is sectional drawing which shows the structure of the wheel drive device of the forklift with which the reduction gear concerning one Embodiment of this invention was integrated. It is sectional drawing of the reduction gear along the DD line | wire of FIG. It is an expanded sectional view near the carrier pin of the reduction gear according to the prior art. It is an expanded sectional view of the carrier pin vicinity of the reduction gear shown in FIG.

  FIG. 1 shows a configuration of a wheel drive device 100 for a forklift incorporating a reduction gear 10 according to an embodiment of the present invention. FIG. 1 is a cross-sectional view of the wheel drive device 100 taken along a vertical plane including the wheels, the motor, and the central axis of the speed reducer.

  The speed reducer 10 is a kind of planetary gear speed reducer called an eccentric swing meshing type.

  The output shaft 12A of the motor 12 is connected to the input shaft 16 of the speed reducer 10 via the spline 14. The input shaft 16 is disposed at the center in the radial direction of external gears 24 and 26 described later. The input shaft 16 is integrally formed with two eccentric bodies 18 and 20 that are offset from the input shaft 16. The two eccentric bodies 18 and 20 are eccentric with a phase difference of 180 degrees from each other. The eccentric bodies 18 and 20 may be configured separately from the input shaft 16 and fixed to the input shaft with a key or the like.

  Two external gears 24 and 26 are fitted on the outer circumferences of the eccentric bodies 18 and 20 via roller bearings 21 and 23 so as to be swingable. The external gears 24 and 26 are in mesh with the internal gear 28, respectively.

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

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

  A first carrier body 34 fixed to a vehicle body frame (not shown) is disposed on the side of the external gears 24 and 26 in the axial direction of the vehicle body, and a carrier bolt 36 and a carrier pin 42 are provided on the opposite side of the vehicle body in the axial direction. A second carrier body 38 integrated with the first carrier body 34 is disposed. An inner pin 40 is formed integrally with the second carrier body 38.

  FIG. 2 is a cross-sectional view of the speed reducer along the line DD in FIG. As shown in the drawing, in the external gear 24 (not shown, the external gear 26 is also the same), twelve through holes having the same diameter are formed at equal intervals at positions offset from the axis. Among them, the carrier pin 42 is inserted into three holes arranged at equal intervals of 120 degrees, and the inner pin 40 is inserted into the remaining nine holes. Therefore, the former is called the carrier pin hole 24B and the latter is called the inner pin hole 24A, but there is no difference in the shape and radial position. Corrugated teeth are formed on the outer periphery of the external gear 24, and these teeth move while in contact with the internal gear pins 28 </ b> A of the internal gear 28, so that the external teeth are externally moved in a plane whose normal is the central axis. The toothed gear 24 can swing. Although not shown, the external gear 26 is the same except that there is a phase difference of 180 degrees with respect to the external gear 24.

  Returning to FIG. 1, the inner pin 40 is inserted into the inner pin holes 24 </ b> A and 26 </ b> A penetratingly formed in the external gears 24 and 26 with a gap, and the tip thereof is inserted into the recess 34 </ b> A of the first carrier body 34. Has been. The inner pin 40 is in contact with a part of the inner pin holes 24A, 26A formed in the outer gears 24, 26 via the sliding promotion member 44, and restrains the rotation of the outer gears 24, 26 to Only swinging is allowed.

  The inner pin 40 is only press-fitted into the recess 34A, and is not fixed with a bolt or the like. It can be said that the inner pin is a connecting member that contributes to the transmission of power between the first and second carrier bodies 34 and 38 and the external gears 24 and 26.

  The carrier pin 42 is inserted in a state where there is a gap in the carrier pin holes 24B and 26B formed through the external gears 24 and 26, and a contact portion 42C having an enlarged diameter is formed on the side of the first carrier body 34 opposite to the vehicle body. It is in contact. The carrier pin 42 and the first carrier body 34 are fastened by a carrier bolt 36. The first carrier body 34 is formed with a through hole 34C for inserting the carrier bolt 36 and a counterbore portion 34B, and a screw hole 42E for screwing the carrier bolt 36 is formed on the axial end surface of the carrier pin 42. Is formed. The second carrier body 38 has a female screw hole 38 </ b> A, and is fastened to the male screw at the tip of the carrier pin 42 on the side opposite to the vehicle body to connect the carrier pin 42 and the second carrier body 38.

  The carrier pin 42 is not in contact with the carrier pin holes 24B and 26B of the external gears 24 and 26, and does not contribute to restraining the rotation of the external gears 24 and 26. It can be said that the carrier pin 42 is a connecting member that contributes only to the connection between the first carrier body 34 and the second carrier body 38.

  The casing 30 of the speed reducer 10 is rotatably supported by a first carrier body 34 and a second carrier body 38 fixed to the vehicle body frame via a pair of main bearings 46 and 47. A wheel member 48 is connected to the end surface of the casing 30 on the side opposite to the vehicle body in the axial direction by bolts 49, and a tire 50 of a forklift (not shown) is attached to the wheel member 48. The speed reducer 10 is accommodated in the axial range of the tire 50 (within the range of the two-dot chain line in FIG. 1).

  A bearing nut 56 is screwed into a screw hole formed in the outer peripheral surface of the second carrier body 38, and when the second carrier body 38, the casing 30, and the main bearings 46 and 47 are assembled, By changing the push-in amount, the pressure applied to the main bearings 46 and 47 can be adjusted.

  The input shaft 16 as an input member of the speed reducer 10 is rotatably supported by the first carrier body 34 and the second carrier body 38 via a pair of angular ball bearings 52 and 54 that are arranged face to face. The angular ball bearings 52 and 54 have rolling elements 52A and 54A and outer rings 52B and 54B, respectively, but do not have an inner ring. Instead, rolling surfaces 52C and 54C are formed on the input shaft 16, and these function as inner rings of the angular ball bearings. In addition, it is not restricted to this structure, You may arrange | position a separate inner ring | wheel.

  A bearing nut 39 is screwed into a screw hole formed in the inner peripheral surface of the second carrier body 38, and when the first carrier body 34, the second carrier body 38 and the angular ball bearings 52, 54 are assembled, The pressure applied to the angular ball bearings 52 and 54 can be adjusted by changing the pushing amount of the bearing nut 39.

  The axial ball bearing 52 on the vehicle body side is restrained in the axial direction by the recess 34 </ b> D of the first carrier body 34 and the rolling surface 52 </ b> C of the input shaft 16. The angular ball bearing 54 on the side opposite to the vehicle body is constrained in the axial direction by the step 39A of the bearing nut 39 screwed into the second carrier body 38 and the rolling surface 54C of the input shaft 16. Therefore, the input shaft 16 is positioned in the axial direction without play by the first carrier body 34 and the bearing nut 39 so that the axial movement is restricted in any direction.

  Then, the effect | action of the wheel drive device 100 is demonstrated.

  The rotation of the output shaft 12 </ b> A of the motor 12 is transmitted to the input shaft 16 of the speed reducer 10 through the spline 14. When the input shaft 16 rotates, the outer circumferences of the eccentric bodies 18 and 20 perform an eccentric motion, and the external gears 24 and 26 swing through the roller bearings 21 and 23. This swinging causes a phenomenon in which the meshing positions of the external teeth of the external gears 24 and 26 and the internal tooth pins 28A and 28B of 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 the first carrier body 34 fixed to the body frame. It is restrained by the fixed inner pin 40. For this reason, every 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. As the casing 30 rotates, the forklift tire 50 rotates through a wheel member 48 fixed to the casing 30 by bolts 49.

  Then, the problem of the structure of the reduction gear based on a prior art is demonstrated.

  3 is an enlarged cross-sectional view of the vicinity of the carrier pin of the speed reducer 10 ′ according to the prior art, and FIG. 4 is an enlarged cross-sectional view of the vicinity of the carrier pin of the speed reducer 10 shown in FIG. 1. Although the prior art reduction gear is not shown in its entirety, the configuration other than the vicinity of the carrier pin shown in FIG. 3 is the same as that of the reduction gear 10 of FIG.

  Referring to FIG. 3, the carrier pin 42 ′ of the speed reducer 10 ′ according to the prior art includes a large diameter portion 42 </ b> B ′ inserted through the external gears 24, 26 and a small portion inserted into the first carrier body 34 ′. A step portion 42C ′ is formed between the first carrier body 34 ′ and the seat surface 34B ′ on the side opposite to the vehicle body. Since the diameters of the carrier pin holes 24B ′ and 26B ′ formed in the external gears 24 and 26 cannot be easily increased in order to secure the transmission torque between the inner pin and the external gear, the carrier pin 42 ′ The diameter of the large diameter portion 42B ′ is also limited. For this reason, the contact area between the carrier pin 42 ′ and the seating surface 34 </ b> B ′ of the first carrier body 34 ′ is very small.

  Since the carrier pin 42 'is fastened to both carrier bodies 34' and 38 'by bolts 36', axial compressive stress is always applied. Further, in the forklift in which the speed reducer 10 ′ is incorporated, the weight of the load is added in addition to the vehicle weight, so that a large bending load is applied to the carrier pin 42 ′. Since this bending load and the above-described compressive stress act on the carrier pin 42 ', a high compressive stress acts on the seat surface 34B' of the first carrier body 34 'contacting the stepped portion 42C', and the seat surface is seated. There was a risk of bending.

  Once buckling occurs, the motor shaft and the input shaft of the speed reducer are misaligned. Further, when the seating surface 34B 'is recessed due to buckling, the pressure applied to the angular ball bearings supported by the first carrier body 34' or the second carrier body 38 'decreases or becomes zero. As a result, the rigidity of the wheel drive device decreases, and problems such as uneven wear of the tire due to shaft misalignment or an increase in the camper angle of the tire occur.

  In order to prevent such buckling of the bearing surface, in this embodiment, as shown in FIG. 4, contact portions 42 </ b> C whose diameters are larger than the cylindrical portions 42 </ b> B and 42 </ b> D adjacent to both sides are formed on the carrier pin 42. Is formed. According to this shape, the seat surface area of the first carrier body 34 that comes into contact with the carrier pin 42 is larger than before, so the compressive load per unit area is reduced and the possibility that the seat surface buckles is greatly reduced. Can do.

  As can be seen from FIG. 4, the diameter of the abutting portion 42C is the same as that of the cylindrical portion 42B by linearly decreasing toward the second carrier body 38 and having the maximum diameter on the flat surface on the first carrier body 34 side. It becomes the diameter. Therefore, the first carrier body 34 side of the contact portion 42C is larger than the carrier pin holes 24B and 26B of the external gears 24 and 26 through which the carrier pins 42 are inserted. Therefore, by forming the counterbore part 34B in the first carrier body 34, a space for accommodating the contact part 42C of the carrier pin 42 whose diameter has been expanded is created.

  In FIG. 4, the contact portion 42 </ b> C is formed on the first carrier body 34 side of the carrier pin 42, and the contact portion having an enlarged diameter is not formed on the second carrier body 38 side. The reason is that the first carrier body 34 is molded by casting, whereas the second carrier body 38 is molded by forging. Therefore, the compressive strength of the material of the first carrier body 34 is higher than that of the second carrier body 38. This is because inferior buckling tends to occur. However, a contact portion having an enlarged diameter may also be formed on the second carrier body 38 side. Note that the present embodiment can be similarly applied as long as the first carrier body 34 and the second carrier body 38 are formed of materials having different compressive strengths, not limited to casting and forging.

  As described above, according to the present embodiment, the seating area of the carrier body that comes into contact with the carrier pin that couples the pair of carrier bodies can be increased as compared with the conventional case, so the compression per unit area applied to the seating surface is reduced. The possibility that the load decreases and the seating surface buckles can be reduced.

  The embodiment of the present invention has been described above. It is to be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective components, and such modifications are within the scope of the present invention.

  The terms input shaft and output shaft in this specification focus only on the power input / output destination, and are not limited to shaft shapes.

  In the embodiment, the eccentric oscillating mesh type planetary gear reducer of the type in which the input shaft (eccentric body shaft) 16 is disposed at the center of the internal gear 28 has been described as an example. However, the present invention can be applied not only to this type of reduction gear but also to a planetary gear reduction gear of a type in which a plurality of eccentric body shafts are arranged at a position offset from the center of the internal gear.

  In the embodiment, the configuration in which the first carrier body 34 and the second carrier body 38 are fixed and the rotation is output from the casing 30 has been described. However, the casing 30 may be fixed and rotation may be output from the first carrier body 34 and the second carrier body 38. In this case, the rotation components of the external gears 24 and 26 are transmitted to the first carrier body 34 and the second carrier body 38 via the inner pin 40.

  In the embodiment, the inner pin that is a connecting member that contributes to the transmission of power between the pair of carrier bodies and the external gear and the carrier pin that is a connecting member that contributes only to the connection between the carrier bodies are separated. It has been described that the compressive stress in the seating surface of the carrier body that is in configuration and abuts against the abutment portion of the carrier pin is reduced. However, there is also an eccentric oscillating planetary speed reducer having a structure in which the carrier pin is not provided and the inner pin has both roles of transmitting power and connecting the carrier body. In such a planetary speed reducer, the present invention can be applied by forming an enlarged contact portion on the inner pin.

  Further, in the embodiment, the description has been given by taking the eccentric swing mesh type planetary gear speed reducer as an example. The present invention can also be applied to the contact portion with the carrier body seat surface.

  The speed reducer according to the present invention is not limited to a forklift wheel drive device, and can be incorporated into various devices that require the output shaft to decelerate the input shaft.

  DESCRIPTION OF SYMBOLS 10 Reduction gear, 12 Motor, 16 Input shaft, 24, 26 External gear, 24A, 26A Inner pin hole, 24B, 26B Carrier pin hole, 28 Internal gear, 30 Casing, 34 1st carrier body, 34B Counterbore part , 38 second carrier body, 40 inner pin, 42 carrier pin, 42C contact part, 46, 47 main bearing, 52, 54 angular contact ball bearing, 100 wheel drive device.

Claims (5)

A pair of carrier bodies arranged on both sides of the planetary gear in the axial direction;
A plurality of connecting members for connecting the pair of carrier bodies,
The connecting member has an abutting portion that abuts against the inner side surface in the axial direction of the carrier body,
The planetary speed reducer characterized in that the abutment portion has a larger diameter than portions on both axial sides adjacent to the contact portion.   2. The planetary reduction gear according to claim 1, wherein a counterbore is formed in a portion of the inner side surface in the axial direction of the carrier body where the contact portion of the connecting member contacts.   3. The pair of carrier bodies support a bearing that rotatably supports an input shaft or an output shaft of the speed reducer, and the bearings are bearings that need to be adjusted in pressure. Planetary reducer as described in   The pair of carrier bodies are formed of different materials, and the diameter of the contact portion of the connecting member located on the side of contact with the carrier body formed of a material having a low compressive strength is increased. The planetary reduction gear according to any one of claims 1 to 3. The plurality of connecting members are respectively inserted into through holes formed in the planetary gear, and a first connecting member that contributes to transmission of power between the carrier body and the planetary gear, and a pair of carrier bodies A second connecting member that contributes to the connection of
The at least one end of the first connecting member is press-fitted into a hole formed on an inner side surface in the axial direction of the carrier body, and the abutting portion is provided on the second connecting member. The planetary speed reducer in any one of thru | or 4.

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