JP2016048112A - Friction roller type reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction roller type reduction gear which can reduce the number of part items while maintaining the necessary rigidity of the reduction gear, can easily perform assembling work, and can assure performance at a reduction gear unit body.SOLUTION: A friction roller type reduction gear 100 comprises a sun roller 15, a ring roller 17, a plurality of intermediate rollers 19, a connecting part 21, and a loading cam mechanism 23. Either of the sun roller 15 and the ring roller 17 is composed of a first roller element 27 and a second roller element 29 which are aligned in an axial direction in parallel with each other, and their rolling contact faces are formed into inclined faces. The loading cam mechanism is arranged at only a single side in the axial direction of either of the first and second roller elements. The intermediate rollers are rotatably supported to a revolving shaft via a needle bearing 22, and also supported to a holder 32 for supporting both end parts of the revolving shaft while having a clearance which is movable to the axial direction between end faces of the intermediate rollers and the holder.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a friction roller type speed reducer.

  In order to improve the convenience of electric vehicles that have begun to spread in recent years, there is a strong demand for improving the efficiency of electric motors in order to increase the travelable distance per charge. In order to improve the efficiency of the electric motor, it is desirable to use a small electric motor that rotates at high speed and to reduce the rotation of the motor output shaft before transmitting it to the drive wheels of the vehicle. In this case, the speed reducer connected to the motor output shaft has a very high operating speed and is likely to generate vibration and noise. Therefore, in order to suppress vibration and noise during operation, it is considered to use a friction roller type speed reducer. As a conventional friction roller type speed reducer, for example, one described in Patent Document 1 is known.

  As shown in FIG. 13, a friction roller type speed reducer 200 described in Patent Document 1 includes an input shaft 211, an output shaft 213, a sun roller 217, a ring roller 219, a plurality of intermediate rollers 221, and a pair. Loading cam mechanisms 223A and 223B and a connecting portion 225. The sun roller 217 has a pair of sun roller elements 227A and 227B divided in the axial direction. The outer peripheral portion of the ring roller 219 is connected to the output shaft 213 via a connecting portion 225. Each of the plurality of intermediate rollers 221 is rotatably supported by a support shaft 229, and the outer peripheral surface thereof is in rolling contact with the outer peripheral surface of the sun roller 217 and the inner peripheral surface of the ring roller 219.

  The loading cam mechanisms 223A and 223B include a first cam ring 231A and a second cam ring 231B fixed to the input shaft 211, balls 233A and 233B, and sun roller elements 227A and 227B. Cam grooves 235 and 237 are formed along the circumferential direction on the opposing surfaces of the sun roller element 227A and the cam ring 231A, and a ball 235A is sandwiched between the cam grooves 235 and 237. Each cam groove 235, 237 has a groove depth in the axial direction that changes along the circumferential direction, and is shallower toward the groove end. The sun roller element 227B and the cam ring 231B are also formed with the same cam groove and the ball 233B is sandwiched therebetween. When rotational torque is applied to the input shaft 211, the balls 233A and 233B ride on the shallow cam groove region according to the rotational torque, and the sun roller element 227A and the sun roller element 227B approach each other along the axial direction. . Thereby, the surface pressure of the traction part which rolls and contacts the outer peripheral surface of the intermediate roller 221 increases. That is, the loading cam mechanisms 223A and 223B operate so that the surface pressure of the traction portion increases as the torque transmitted between the input shaft 211 and the output shaft 213 increases.

JP2013-104545A

  In the above configuration, since the pair of loading cam mechanisms 223A and 223B are provided to make the pair of sun roller elements 227A and 227B approach or separate from each other, the center position in the axial direction of the intermediate roller 221 is kept constant. However, a configuration in which the loading cam mechanism is provided only on one side is also adopted from the viewpoint of reducing the number of parts of the reduction gear, miniaturization, and improving assemblability. In that case, one of the pair of sun roller elements is a fixed side and the other is a movable side, and only the movable sun roller element moves in the axial direction. When only the movable sun roller element moves in the axial direction, an axial force acts on the intermediate roller 221 which is in rolling contact with each sun roller element. However, since the intermediate roller 221 is generally supported by a shaft without assuming axial movement, an extra frictional force is generated in the traction portion of the intermediate roller 221. This frictional force causes wear on the traction part. This applies not only to the sun roller but also to the case where the ring roller 219 has a pair of ring roller elements divided in the axial direction.

  Further, the intermediate roller 221 is a member that is driven to rotate at high speed and indispensable for oil supply. However, if the intermediate roller 221 moves in the axial direction due to the action of the axial force, the oil supply position may be shifted, and a necessary and sufficient oil supply amount may not be ensured. In order to reliably supply oil to the intermediate roller 221, an oil supply passage to the intermediate roller 221 may be provided. However, the oil passage structure for accommodating axial movement becomes complicated, and the manufacturing cost and maintenance of the apparatus itself are increased. This leads to an increase in cost.

  The present invention has been made in view of the above matters, and an object of the present invention is to provide a loading cam mechanism only on one axial side of the first roller element and the second roller element of the sun roller or the ring roller. A friction roller type speed reducer that can suppress the occurrence of friction and wear without hindering the displacement of the roller due to loading even with the provided configuration, and can supply the lubricating oil to the intermediate roller satisfactorily. It is to provide.

The present invention has the following configuration.
A sun roller disposed concentrically with the input shaft; a ring roller disposed concentrically with the sun roller on an outer peripheral side of the sun roller; and the input shaft between an outer peripheral surface of the sun roller and an inner peripheral surface of the ring roller. A plurality of intermediate rollers that are rotatably supported around a rotation axis parallel to the outer periphery of the sun roller and that are in rolling contact with the outer peripheral surface of the sun roller and the inner peripheral surface of the ring roller, and a connecting portion that connects the ring roller and the output shaft. A friction roller type speed reducer comprising a loading cam mechanism for changing the contact surface pressure of the rolling contact surface of each roller,
One of the sun roller and the ring roller is composed of a first roller element and a second roller element arranged in parallel in the axial direction of the input shaft, and the respective rolling contact surfaces are the first and second roller elements. From the opposing side end surfaces facing each other toward the outer side end surface opposite to the opposing side end surface, the distance to the center of rotation of the intermediate roller is reduced,
The loading cam mechanism is disposed only on one of the first and second roller elements on one side in the axial direction, and controls one of the first and second roller elements according to the rotational torque of the input shaft. To displace towards the other,
The intermediate roller is rotatably supported on the rotation shaft via a needle bearing, and is moved in the axial direction between the end surface of the intermediate roller and the holder by a holder that supports both ends of the rotation shaft. A friction roller type speed reducer characterized by being supported with a possible clearance.

  According to the present invention, even if the loading cam mechanism is provided only on one axial side of the first roller element and the second roller element of the sun roller or ring roller, The occurrence of friction and wear can be suppressed without hindering the displacement. In addition, it is possible to satisfactorily supply the lubricating oil to the intermediate roller.

It is a figure for demonstrating embodiment of this invention, and is a partial cross section perspective view of a friction roller type reduction gear. It is a principal part expanded sectional view of the friction roller type reduction gear shown in FIG. It is a top view of the cam ring which shows the cam groove of a loading cam mechanism. FIG. 4 is a cross-sectional view taken along line AA of FIG. 3, showing a state (A) in which the loading cam mechanism does not generate thrust and a state (B) in which thrust is generated. It is a perspective view of the rocking | holding holder which supports an intermediate | middle roller. It is a disassembled perspective view of a carrier. It is a principal part expanded sectional view of the friction roller type reduction gear for demonstrating the displacement of the intermediate roller by a loading cam mechanism. It is a partial cross section figure of a rocking | fluctuation holder and an intermediate | middle roller. It is the partial cross section perspective view which cut | disconnected the carrier by the surface containing the central axis of a rocking | fluctuation axis | shaft. It is the partial cross section perspective view which cut | disconnected the rocking | fluctuation holder by the surface containing the central axis of a support shaft. It is a perspective view of the rocking | swiveling holder which was thinned in the arm width direction. It is a perspective view of the rocking | swiveling holder which was thinned in the arm height direction. It is principal part sectional drawing of the conventional friction roller type reduction gear.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<Configuration of friction roller reducer>
FIG. 1 is a view for explaining an embodiment of the present invention, and is a partial cross-sectional perspective view of a friction roller type speed reducer, and FIG. As shown in FIGS. 1 and 2, the friction roller type speed reducer 100 includes a sun roller 15, a ring roller 17, a plurality of intermediate rollers 19, a ring roller 17, and an output shaft 13 that are arranged concentrically with the input shaft 11. And a loading cam mechanism 23.

  The sun roller 15 is a solid structure roller integrally formed with the input shaft 11 at one end of the input shaft 11 shown in FIG. The outer peripheral surface 15a of the sun roller 15 is formed in a concave curved surface in which the outer edge shape of the axial section is a single circular arc-shaped concave curve.

  The ring roller 17 is a pair of ring roller elements arranged in parallel in the axial direction, and includes a fixed ring roller element (first roller element) 27 and a movable ring roller element (second roller element) movable in the axial direction. 29. These ring roller elements 27 and 29 are arranged concentrically with the sun roller 15 on the outer peripheral side of the sun roller 15 in a state of being accommodated inside the cup-shaped connecting portion 21.

  The inner peripheral surfaces 27a and 29a of the fixed ring roller element 27 and the movable ring roller element 29 are formed from the opposite end faces 24 and 24 where the ring roller elements 27 and 29 face each other to the outer end faces 26 and 26 on the opposite side in the axial direction. It becomes the cyclic | annular inclined surface inclined so that an internal diameter may become small as it goes. That is, the intermediate roller 19 has an inclined surface that shortens the distance to the center of the rotation axis. These inclined surfaces become rolling contact surfaces on which the intermediate roller 19 rolls. The inner peripheral surfaces 27a and 29a are not limited to the inclined surfaces, but may be concave curved surfaces in which the outer edge shape of the axial cross section is a single arc-shaped concave curve.

  The plurality of intermediate rollers 19 are supported by a support shaft (spinning shaft) 31 via a needle bearing 22 so as to be rotatable and displaceable in the axial direction, and the outer peripheral surface 15 a of the sun roller 15 and the inner peripheral surface 17 a of the ring roller 17. It is arranged between. Both ends of the support shaft 31 are supported by the swing holder 32. The swing holder 32 is supported by the carrier 33 so that the intermediate roller 19 can move (swing) in the radial direction of the input shaft 11. The carrier 33 is fixed to a motor body (not shown) by a fastening member.

  The support shaft 31 is selected optimally for the material and heat treatment to be used in order to support the intermediate roller 19 rotating around the input shaft 11 while rotating around the input shaft 11 with high strength. Details of the material of the support shaft 31 and the heat treatment will be described later.

  The outer peripheral surface 19a of the intermediate roller 19 is a convex curved surface whose outer edge shape in the axial section is a single arc-shaped convex curve, and is in rolling contact with the outer peripheral surface 15a of the sun roller 15 and the inner peripheral surface 17a of the ring roller 17, respectively.

  As will be described in detail later, the needle bearing 22 is a cage and roller having a needle roller 113 and a cage 115. At both ends of the needle bearing 22, crown-shaped grooved collars 117 are interposed, and the needle bearing 22 attached to the support shaft 31 is supported between the swing holders 32 at both ends of the support shaft 31.

  The connecting portion 21 is formed in a substantially disc shape and has a base end portion 37 whose central portion is connected to the output shaft 13, and extends in the axial direction from the outer peripheral edge of the base end portion 37. And a cylindrical roller holding portion 39 to be held.

  Inside the roller holding portion 39, a corrugated preload spring 67, a cam ring 49, a ball 51 as a rolling element, a movable ring roller element 29, a fixed ring roller element 27, and a retaining ring 47 are provided from the base end portion 37 side. These members are inserted in this order, and these members are assembled to the roller holding portion 39.

  A plurality of concave grooves 43 are formed in the inner peripheral portion of the roller holding portion 39 along the axial direction, and a ring groove 45 (see FIG. 1) is formed.

  The concave groove 43 accommodates the protrusions 28 formed in a plurality of locations on the outer peripheral portion of the fixed ring roller element 27 and projecting in the radial direction. The protrusion 28 engages with the concave groove 43 of the roller holding portion 39 in a state where there is no rattling in the rotation direction, and enables transmission of rotational torque between the roller holding portion 39 and the ring roller 17.

  A retaining ring 47 is inserted into the ring groove 45. The retaining ring 47 restricts the axial position of the fixed ring roller element 27 and fixes the fixed ring roller element 27 to the roller holding portion 39.

  For example, the base end portion 37 of the connecting portion 21 is formed by cutting such as lathe processing, and the roller holding portion 39 is formed by plastic processing such as press molding. The base end portion 37 and the roller holding portion 39 are formed as a single unit, and then joined together, so that the shaft cores can be made to coincide with each other at a low cost with high accuracy. Further, the base end portion 37 and the roller holding portion 39 are joined by beam welding. As a result, it is possible to perform heat bonding with a narrow bead and in a short time, and it is possible to suppress the occurrence of misalignment by minimizing thermal distortion.

  The cam ring 49 has a plurality of protrusions 61 that protrude radially outward from the outer peripheral portion thereof. The protrusion 61 of the cam ring 49 and the protrusion 28 of the fixed ring roller element 27 engage with the groove 43 of the roller holding portion 39, respectively.

  The cam ring 49 has a notch 63 formed on the outer end surface on the output shaft 13 side, in which a part on the outer diameter side is notched in an annular shape, and a preload spring 67 is attached to the notch 63.

  Since the sun roller 15 rotates at a high speed, there is a possibility that it becomes a vibration source of abnormal vibration if there is a slight deviation of the center of gravity. However, since the sun roller 15 of this configuration is integrally formed with the input shaft 11, the balance can be easily corrected and the occurrence of vibration can be reduced. Moreover, since the sun roller 15 has high rigidity and a high resonance frequency, occurrence of abnormal vibration due to resonance is reduced. Furthermore, the sun roller 15 having a solid structure reduces the amount of elastic deformation of the sun roller 15 when a radial load is applied. Thereby, the axial displacement amount of the intermediate roller 19 and the ring roller 17 becomes small, and the contact state of the rolling contact surface can be maintained in a good state as designed.

<Loading cam mechanism>
Next, the loading cam mechanism will be described.
The movable ring roller element 29, the cam ring 49, and the ball 51, which is a rolling element, constitute the loading cam mechanism 23 shown in FIG. The loading cam mechanism 23 changes the contact surface pressure of each rolling contact surface of the sun roller 15, the ring roller 17, and the intermediate roller 19.

  As shown in FIGS. 3 and 4, a plurality of (three in the illustrated example) first cam grooves 53 are formed on the outer end surface 26 of the movable ring roller element 29 along the circumferential direction. Similarly, a second cam groove 55 is formed for the cam ring 49. That is, the cam ring 49 is disposed facing the first cam groove 53, and a plurality of (three in the illustrated example) second cam grooves 55 are formed at circumferential positions corresponding to the first cam grooves 53. The balls 51 are sandwiched between the first cam groove 53 and the second cam groove 55, respectively.

  The axial groove depths of the first cam groove 53 and the second cam groove 55 are deepest in the central portion with respect to the circumferential direction, and gradually change along the circumferential direction, so that the circumferential direction of the cam grooves 53 and 55 is increased. It becomes shallower toward the end.

  In a state where the input shaft 11 is stopped, as shown in FIG. 4A, each ball 51 is located at the deepest part of each cam groove. In this state, the cam ring 49 is pressed toward the movable ring roller element 29 by the elastic force of the preload spring 67.

  When the input shaft 11 is driven to rotate, each ball 51 moves to a shallow portion of each cam groove 53, 55 as shown in FIG. This generates an axial thrust that presses the movable ring roller element 29 toward the other fixed ring roller element 27. When the interval between the fixed ring roller element 27 and the movable ring roller element 29 is reduced by the axial thrust generated by the loading cam mechanism 23, the inner peripheral surface 17a of the ring roller 17 and the outer peripheral surface 19a of each intermediate roller 19 are reduced. As the surface pressure at the rolling contact portion increases, the surface pressure at the rolling contact portion between the outer peripheral surface 19a of each intermediate roller 19 and the outer peripheral surface 15a of the sun roller 15 also increases. As a result, the surface pressure of the plurality of rolling contact portions existing between the input shaft 11 and the output shaft 13 increases as the torque transmitted between the input shaft 11 and the output shaft 13 increases.

  Further, when the loading cam mechanism 23 generates axial thrust, the intermediate roller 19 is caused by the displacement of the movable ring roller element 29 in the axial direction due to elastic deformation of the traction components such as the ring roller 17 and elastic deformation of each contact point. It is displaced in the axial direction toward the fixed ring roller element 27 side. The axial displacement of the intermediate roller 19 will be described in detail later.

<Structure that aligns the axis of each member>
As shown in FIG. 2, an annular first stepped portion 41 having an inner peripheral surface parallel to the output shaft 13 is formed on the inner surface of the base end portion 37 of the connecting portion 21 on the input shaft 11 side. Yes.

  An outer peripheral surface of the cam ring 49 that is formed concentrically with the central axis of the cam ring 49 and that fits along the axial direction with the first stepped portion 41 at the base end portion 37 of the connecting portion 21. A second stepped portion 65 having a protrusion is formed protruding in the axial direction.

  The cam ring 49 and the connecting portion 21 are aligned with each other with high accuracy by fitting the first stepped portion 41 and the second stepped portion 65 together. Thereby, the movable ring roller element 29 is also in a state in which the axial center position is accurately aligned via the cam ring 49. The fixed ring roller element 27 is positioned in the radial direction by the intermediate roller 19. Since the intermediate roller 19 is positioned in the radial direction by the sun roller 15 concentric with the input shaft 11 and the input shaft 11 and the output shaft 13 are disposed concentrically, the sun roller 15, the ring roller 17, and the cam ring 49 are The axial center is in the state which matched exactly.

  In addition, the cam ring 49 is urged to the axially opposite side from the base end portion 37 by the preload spring 67, and the second stepped portion 65 is fitted to the first stepped portion 41 of the base end portion 37. . This fitting length is longer than the elastic deformation allowance of the preload spring 67. Accordingly, when the cam ring 49 is assembled to the base end portion 37, the preload spring 67 is prevented from being detached from between the cam ring 49 and the base end portion 37, and the assemblability of the speed reducer is improved.

<Supporting form of intermediate roller to carrier>
Next, the support form of the intermediate roller 19 in the friction roller type speed reducer 100 configured as described above will be described in more detail.
FIG. 5 is a perspective view of the swing holder 32 that supports the intermediate roller. The intermediate roller 19 is supported by the swing holder 32 at both ends of a support shaft 31 that is a rotating shaft. The same number of swing holders 32 as the intermediate rollers 19 are provided, and one intermediate roller 19 is supported by each swing holder 32. The swing holder 32 includes a pair of arm portions 71a and 71b that support both ends of the support shaft 31, and a base portion 75 that connects the arm portions 71a and 71b. A rocking shaft 73 parallel to the support shaft 31 is inserted through the base 75.

  FIG. 6 is an exploded perspective view of the carrier 33. The carrier 33 includes an annular bottom 77, a carrier body 81 having pillars 79 standing on plural sides (three in the illustrated example) that are equidistant in the circumferential direction on one side of the bottom 77, and a pillar And an annular connection plate 83 fixed to the tip 79a of the portion 79.

  A bolt insertion hole 85 for fixing the carrier 33 to the motor body is formed in the column portion 79 of the carrier body 81 along the axial direction. In the illustrated example, a total of three places are formed in each column portion 79, one place.

  A swing holder 32 that supports the intermediate roller 19 is disposed between the column portions 79 arranged in the circumferential direction. The swing holder 32 swings on the carrier 33 by inserting a swing shaft 73 into a swing shaft hole 91 formed in the connecting plate 83 and a swing shaft hole (not shown) formed in the bottom 77. It is supported freely.

  A bolt fastening hole 87 is formed in the connecting plate 83 at a position corresponding to each bolt insertion hole 85 of the column portion 79, and a swing shaft hole 91 is formed at a position corresponding to the swing shaft 73 of the swing holder 32. Is formed.

  The swinging holder 32 swings about the swinging shaft 73 with respect to the carrier 33, so that the intermediate roller 19 can protrude and retract in the radial direction of the carrier 33.

  The carrier body 81 and the connecting plate 83 are positioned relative to each other by pin fitting. That is, a pin hole 95 into which the pin 93 is inserted is formed in the tip end portion 79 a of the column portion 79 of the carrier body 81, and the pin 93 is located at a position corresponding to the pin hole 95 on the carrier body 81 side of the connecting plate 83. A pin hole (not shown) for inserting and inserting is formed.

  The carrier body 81 and the connecting plate 83 are pressed against each other in the axial direction with the pins 93 disposed between the corresponding pin holes 95, so that the pins 93 are press-fitted into the pin holes 95, and both are in the design position. Temporarily fixed. The bolt fastening hole 87 has an inner diameter that allows a bolt to be inserted to be inserted with a clearance.

<Axial displacement of intermediate roller>
Next, the axial displacement of the intermediate roller 19 will be described in detail.
FIG. 7 shows an enlarged cross-sectional view of a main part of a friction roller type speed reducer for explaining the displacement of the intermediate roller 19 by the loading cam mechanism 23. In the friction roller type speed reducer 100 of this configuration, the loading cam mechanism 23 is disposed only on one axial side of the pair of ring roller elements. That is, of the fixed ring roller element 27 and the movable ring roller element 29, the loading cam mechanism 23 is disposed only on one side of the movable ring roller element 29 in the axial direction.

  The loading cam mechanism 23 displaces the movable ring roller element 29 toward the fixed ring roller element 27 in accordance with the rotational torque from the input shaft 11.

  The intermediate roller 19 is supported by the input shaft 11 via a needle bearing 22, and this needle bearing 22 does not hinder the axial displacement of the intermediate roller 19, and realizes a smooth axial sliding operation with low resistance. . Thereby, even if the intermediate roller 19 receives an axial force from the loading cam mechanism 23, the intermediate roller 19 moves smoothly in the axial direction, and the occurrence of wear and friction is suppressed.

  The intermediate roller 19 and the ring roller 17 are in rolling contact with each other at an inclination angle α with respect to the axial direction. In this case, when the movable ring roller element 29 receives an axial force by the loading cam mechanism 23 and is displaced in the axial direction, the movable ring roller element 29 and the fixed ring roller element 27 are elastically deformed in the radial direction.

  Elastic deformation also occurs in the sun roller 15, the ring roller 17, and the intermediate roller 19 in addition to the ring roller 17, and in particular, elastic deformation due to tensile stress in the outer diameter direction generated in the ring roller 17 is maximized.

  The relationship between the amount of elastic deformation (radius change) δ in the radial direction of the ring roller 17 and the amount of movement Δ in the axial direction is expressed by the following equation (1).

  Δ = δ / tan α (1)

  Further, the axial displacement amount of the intermediate roller 19 is half of the movement amount Δ of the movable ring roller element 29. In order to prevent interference between the intermediate roller 19 and other members such as the swing holder 32 when the intermediate roller 19 moves in the axial direction, it is necessary to provide predetermined gaps at both ends in the axial direction of the intermediate roller 19 in advance. There is.

  Therefore, as shown in FIG. 8, the total clearance 2S between the end surface 19b of the intermediate roller 19 and the arm portions 71a and 71b of the swing holder 32 is set to a relationship expressed by the following equation (2).

  2S ≧ Δmax / 2 = δmax / tan α / 2 (2)

  The needle bearing 22 having this configuration includes needle rollers 113 arranged in two rows in the axial direction, and cages 115 that respectively hold the needle rollers 113. Further, grooved collars 117 are interposed at both ends of the needle bearing 22, respectively. The grooved collar 117 has a crown shape having a cylindrical peripheral side wall 117a and a collar portion 117b obtained by bending one end of the peripheral side wall 117a outward in the radial direction, and a plurality of notches are formed at the other end of the peripheral side wall 117a. 119 is formed. The outer diameter of the peripheral side wall is made smaller than the inner diameter of the intermediate roller 19.

  In the case of the configuration of the needle bearing 22, the clearance 2 </ b> S in the expression (2) is provided on the intermediate roller 19 facing the surface from the surface facing the peripheral side wall 117 a of the collar portion 117 b of the collar 117 at the axial end. Means the sum 2S of the one end distance S to the end face 19b and the same one end distance S at the other end in the axial direction.

  By providing clearances with the sum total of 2S at both ends of the intermediate roller 19, even if the ring roller 17 moves in the axial direction with the maximum movement amount Δmax, the intermediate roller 19 does not interfere with surrounding members. . That is, when the rotational torque is transmitted from the input shaft 11, the intermediate roller 19 moves to the arm portion 71a side by a half of the movement amount Δ shown by the equation (1). Even in such a case, since the clearance 2S exists in the axial direction of the intermediate roller 19, the end surface 19b of the intermediate roller 19 is displaced in the axial direction without interfering with members such as the arm portion 71a and the flange portion 117b of the grooved collar 117. Is acceptable.

  The width W of the intermediate roller 19 (distance between the end surfaces 19b and 19b) is preferably greater than or equal to the sum of the width L of the needle bearing 22 and the clearance 2S. As a result, even if the intermediate roller 19 is displaced in the axial direction, the end surface 19b of the intermediate roller 19 does not enter the axial direction region of the needle bearing 22, and edge load due to the end surface 19b can be prevented.

Next, the radial clearance of the needle bearing 22 that supports the intermediate roller 19 will be described.
The support shaft 31, the needle bearing 22, and the intermediate roller 19 are configured to have a dimensional relationship in which a radial internal clearance exists in the needle bearing 22 in a state where no normal force acts. Since the needle bearing 22 has an internal clearance in the radial direction, the parts can be easily assembled.

  However, if the needle bearing 22 has an internal clearance in the radial direction, the intermediate roller 19 is inclined by an amount corresponding to the internal clearance, causing slippage on the traction surface. The slip generated on the traction surface affects the force transmission effect in the rolling contact, and reduces the power transmission efficiency of the entire speed reducer. Therefore, it is necessary to reduce the internal clearance in the radial direction of the needle bearing 22 to make it difficult for slippage.

  Specifically, the radial internal clearance of the needle bearing 22 is set small as follows. That is, a preload is applied to each roller in the assembling process of the speed reducer. Then, a normal force acts between each of the sun roller 15, the ring roller 17, and the intermediate roller 19. The intermediate roller 19 is reduced in diameter in the normal direction by the normal force.

  At this time, the radial internal clearance δa of the needle bearing 22 is set to be smaller than the diameter reduction amount δb of the intermediate roller 19. As a result, there is always no radial internal clearance of the needle bearing 22 after assembly. In other words, the internal clearance in the radial direction of the needle bearing 22 is negative (a state in which there is no rattling in the radial direction (radial direction) between the inner and outer raceway surfaces of the needle bearing 22 and the rolling surfaces of the rollers). It becomes.

  When the preload is applied after the reduction gear assembly, the radial internal clearance of the needle bearing 22 is set to a negative clearance, so that the support rigidity of the intermediate roller 19 becomes higher than that before the preload is applied, and the posture of the intermediate roller 19 is increased. Is stable. Thereby, the occurrence of skew of the intermediate roller 19 is suppressed, and slipping of the traction surface during driving is reduced. Therefore, the power transmission efficiency of the reduction gear is improved.

  The above is an example in which the internal clearance in the radial direction of the needle bearing 22 is changed to a negative clearance due to the deformation of the intermediate roller 19 due to the preload, but when the high torque is transmitted by the loading cam mechanism 23 to generate a normal force, the needle The dimensional relationship may be such that the radial internal clearance of the bearing 22 is a negative clearance.

  When low torque transmission (when normal force is generated by the preload mechanism), if the radial internal clearance of the needle bearing 22 has a large negative clearance, the effect of bearing friction on the power transmission efficiency of the reducer increases. Reducer efficiency may be reduced. Therefore, by setting the radial internal clearance of the needle bearing 22 to the above dimensional relationship, the bearing friction is small when transmitting low torque, and the radial internal clearance of the needle bearing 22 becomes negative when transmitting high torque, and the intermediate roller The support rigidity of 19 can be increased.

<Oil supply path to intermediate roller>
Next, an oil supply path for supplying lubricating oil to the intermediate roller 19 will be described.
Since the intermediate roller 19 rotates at a high speed when power is transmitted to the input shaft 11, lubricating oil is always supplied. The friction roller type speed reducer 100 of this configuration supplies lubricating oil with an appropriate amount of oil to an appropriate supply position without complicating the lubricating oil supply oil path even when the intermediate roller 19 moves in the axial direction. It is possible.

  Below, the structure of a specific supply oil path is demonstrated. 9 is a partially sectional perspective view in which the carrier 33 is cut along a plane including the central axis of the swing shaft 73, and FIG. 10 is a partial sectional perspective view in which the swing holder 32 is cut along a plane including the central axis of the support shaft 31. It is.

  As shown in FIG. 9, the swing holder 32 is pivotally supported on the carrier 33 by a swing shaft 73. The carrier 33 is fastened and fixed to a housing (not shown) by fixing bolts. A lubricating oil supply path is formed in the housing, and a lubricating oil supply port through which the lubricating oil is discharged is connected to a drilled hole 123 that opens at one end 121 of the swing shaft 73. The perforated hole 123 is formed from the one end 121 of the swing shaft 73 along the swing shaft 73, and lubricating oil is supplied from the housing side.

  As shown in FIG. 10, communication holes 125 and 127 communicating with the drill hole 123 are formed in the swing shaft 73. The communication hole 125 opens in the annular groove 129 of the swing shaft 73, and the communication hole 127 opens in the annular groove 131 of the swing shaft 73. Shaft holes 133 and 135 for supporting the support shaft 31 of the intermediate roller 19 are formed in the arm portions 71a and 71b of the swing holder 32, and an annular groove 129 and a shaft hole 133 are connected to the arm portion 71a. A communication hole 137 is formed. Further, the base 75 is formed with first injection supply holes 139 and 139 that communicate with the radially outer side facing the outer peripheral surface of the intermediate roller 19 from the annular groove 131.

  On the other hand, a drill hole 141 is formed in the support shaft 31 along the support shaft 31, and second injection supply holes 143 and 143 that communicate with the intermediate portion of the support shaft 31 from the center of the drill hole 141 in the radial direction outside. Is formed. Further, a communication hole 145 is formed at a position corresponding to the communication hole 137 of the support shaft 31, and the communication hole 137 and the drilled hole 141 are communicated with each other. The opening end of the hole 141 is closed with a plug (not shown).

  With the above configuration, the lubricating oil supplied from the housing side to the drilling hole 123 of the swing shaft 73 is filled into the annular groove 129 through the communication hole 125, and further, the support shaft 31 is drilled through the communication hole 137 and the communication hole 145. It is supplied to the hole 141. The lubricating oil supplied to the drill hole 141 is supplied to the needle bearing 22 from the second injection supply holes 143 and 143. The lubricating oil supplied to the needle bearing 22 passes through the clearance of the cage 115 shown in FIG. 8 and is discharged around the intermediate roller 19 through the notch 119 of the grooved collar 117 at both ends of the needle bearing 22.

  Further, the lubricating oil is filled in the annular groove 131 from the hole 123 of the swing shaft 73 shown in FIG. 10 through the communication hole 127, and further injected to the outer peripheral surface 19a of the intermediate roller 19 through the first injection supply holes 139 and 139. Supplied.

  Here, even if the intermediate roller 19 moves in the axial direction, the lubricating oil can be stably supplied from the first injection supply holes 139 and 139 and the second injection supply holes 143 and 143. In particular, when the lubricating oil is supplied to the needle bearing 22 from the outside of the intermediate roller 19, the axial position of the intermediate roller 19 changes, so that an adjustment mechanism for changing the oil supply destination is required, and the oil path configuration becomes complicated. .

  However, according to this configuration, the lubricating oil can be supplied without complicating the oil path configuration. That is, the lubricating oil is supplied from the swinging shaft 73 that does not move in the axial direction, the lubricating oil is guided to the support shaft 31 via the swinging holder 32, and the lubricating oil is supplied from the inside of the support shaft 31 to the needle bearing 22. And As a result, the necessary and sufficient amount of lubricating oil can be stably supplied to the intermediate roller 19 that is displaced in the axial direction without any complicated oil passage.

  Further, the swing shaft 73 has a high rigidity for supporting the swing holder 32 and is supported by the carrier 33 so as not to move in the axial direction. Even if the oil passage is formed, the swing holder 32 is not inclined, and the posture of the intermediate roller 19 can be kept stable.

<Modification of support structure for intermediate roller>
Next, a modified example of the support structure for the intermediate roller 19 will be described in detail.
In the arm portion 71a of the swing holder 32 shown in FIG. 10 described above, a communication hole 137 and a tip hole 147 coaxial with the communication hole 137 are formed. The communication hole 137 and the tip hole 147 are formed by a method such as cutting or electric discharge machining, and the swing shaft on which the swing shaft 73 is supported from the tip on the shaft hole 133 side where the support shaft 31 of the arm portion 71a is supported. The support holes 149 are penetrated.

  A spring pin (not shown) for fixing the support shaft 31 is inserted into the tip hole 147 formed at the tip of the arm portion 71a.

  With the above structure, when the friction roller type reduction gear transmits power, the reaction force of torque transmission of each intermediate roller 19 acts on the support shaft 31. The direction in which the reaction force acts is the direction of a line connecting the axes of the support shaft 31 and the swing shaft 73 in the vertical plane of the support shaft 31 and the swing shaft 73.

  When a reaction force in the tensile direction acts on the arm portion 71a, stress concentration may occur at the hole mouth of the tip hole 147 into which the spring pin is inserted, and the hole mouth portion may be damaged. Moreover, since the arm part 71a is formed with an oil passage like the communication hole 137, the rigidity tends to be lower than that of the arm part 71b. Therefore, the elastic deformation amount of the tip hole 147 is larger than the elastic deformation amount of the arm tip of the arm portion 71b.

  If the elastic deformation amounts of the pair of arm portions 71a and 71b are different, the support shaft 31 is inclined due to the difference, and a slight skew is generated in the intermediate roller 19. If skew occurs in the intermediate roller 19, slippage occurs on the roller contact surface, and the power transmission efficiency of the speed reducer decreases.

  Therefore, in this modification, in order to eliminate the inclination of the support shaft 31, the rigidity balance of the arm portions 71a and 71b of the swing holder 32A is made uniform. FIG. 11 shows a perspective view of the swing holder 32A.

  The swing holder 32A according to the present modification has an arm width Wa in the axial direction of the arm portion 71a in which the communication hole 137 serving as an oil passage is formed among the pair of arm portions 71a and 71b. It is larger than the width Wb of the part 71b.

  With the above configuration, the arm portion 71a in which the tip hole 147 into which the spring pin is inserted is formed to have an arm width Wa wider than Wb. Therefore, the load stress is reduced as the arm sectional area is increased. Therefore, even if the stress distribution due to the tip hole 147 occurs, the absolute value of the stress is reduced, and the stress concentration at the hole mouth is relaxed. Thereby, even if a reaction force acts on the arm portion 71a, it is difficult for damage to occur.

  Further, the arm portions 71a and 71b have the same amount of elastic deformation at the end of the arm caused by the reaction force. As a result, the posture of the intermediate roller 19 is stabilized and the power transmission efficiency of the speed reducer can be prevented from being lowered.

  Further, the arm portion 71 a having the communication hole 137 serving as an oil passage desirably has a constricted portion 151 at a part between the swing shaft 73 and the support shaft 31. The constricted part 151 is a thin part in which the arm width is reduced from Wa to Wc (Wc <Wa) in the axial direction. By providing the constricted portion 151 on the arm portion 71a having the large arm width Wa, the rigidity balance between the arm portions 71a and 71b becomes more uniform. As a result, the amount of elastic deformation when the reaction force acts on each arm 71a, 71b becomes equal. For this reason, the attitude | position of the intermediate | middle roller 19 is stabilized more and the fall of the power transmission efficiency of a reduction gear can be prevented further.

  Further, the constricted portion 151 may be thinned in the arm height direction orthogonal to the arm width direction. FIG. 12 shows a perspective view of the swing holder 32B. Each of the arm portions 71a and 71b of the swing holder 32B has an overall arm height of Ha. The arm portion 71a having the communication hole 137 serving as an oil passage has a constricted portion 153 having an arm height of Hb (Ha> Hb) in a part between the swing shaft 73 and the support shaft 31.

  The rigidity of the arm portion 71a is reduced by the constricted portion 153, and the rigidity balance with the arm portion 71b can be made uniform. As a result, the same effect as that obtained when the constricted portion 151 is provided can be obtained.

<Support shaft material and heat treatment>
Next, the material and heat treatment of the support shaft 31 of the intermediate roller 19 will be described in detail.
For the support shaft 31, JIS steel types SUJ2, SK5, SK85, etc. can be used. The support shaft 31 has a residual austenite amount of at least the outermost surface layer of the raceway surface (contact surface with the needle bearing 22) of 15 volume% or more and 40 volume% or less, and an average residual austenite from the surface to the center. The Vickers hardness in the surface layer from the surface to the depth of 2% Da (Da: roller diameter of the needle bearing 22) is set to Hv650 or more.
As a result, it is possible to provide the support shaft 31 that is less likely to change with time even when used under high temperatures, high speeds, and high loads, and can have a long service life.

  The support shaft 31 whose end is fixed by crimping to the swing holder 32 is annealed after performing any one of a carburizing process, a carbonitriding process and a nitriding process as a curing heat treatment, and The raceway surface is induction hardened. Depending on the case, special heat treatment such as carburization may be performed. Further, the nitrogen concentration of the outermost surface layer of the raceway surface is 0.05% by weight or more, and the Vickers hardness of the end surface of the support shaft 31 is Hv200 or more and Hv300 or less. In addition, when the end part of the support shaft 31 is not caulked and fixed, it is baked.

  Table 1 shows materials A to K that can be used for the support shaft 31.

The support shaft 31 is manufactured by processing the alloy steel materials A to K shown in Table 1 into predetermined dimensions by forging, turning, grinding, etc., then performing a curing heat treatment, and further performing a finishing process by grinding or the like. it can.
The curing heat treatment can be performed, for example, under the following conditions.
A: Carbonitriding → Annealing → Induction quenching → Tempering b: Carbonitriding → Induction quenching → Tempering c: Nitriding treatment → Induction quenching → Tempering d: Carbonitriding → Submerged quenching → Tempering o: Carburizing → Annealing → Induction quenching → Tempering: Carburization → Subsequent quenching → Tempering

However,
Carbonitriding: 1 to 5 hours at 820 to 920 ° C. Rx gas + enriched gas + ammonia gas atmosphere treatment and then left to cool

Nitriding treatment: ammonia gas atmosphere at 550-570 ° C. for 2-20 hours

Carburization: 1 to 5 hours at 820 to 880 ° C., after cooling to atmosphere of enriched gas + ammonia gas

Annealing: 1 to 5 hours at 600 to 720 ° C

Induction hardening: frequency 100 kHz, voltage 3 to 6 kV, current 2.5 to 5.5 A, shaft moving speed 2 to 20 mm / s
Coolant: Water-soluble coolant

Submerged quenching: 0.5-1 hour at 820-870 ° C

Tempering: 1-3 hours at 160-500 ° C

  The details of the material of the support shaft 31 and the conditions for the heat treatment are described in Japanese Patent No. 4380217, and should be referred to as necessary.

  As described above, the present invention is not limited to the above-described embodiments, but can be modified by those skilled in the art based on combinations of the configurations of the embodiments, descriptions in the specification, and well-known techniques. Application is also within the scope of the present invention and is within the scope of protection.

  In the friction roller type speed reducer 100 configured as described above, the ring roller 17 is constituted by a pair of ring roller elements, and one ring roller element is moved in the axial direction by a loading cam mechanism. 15 may be configured by a pair of sun roller elements, and one of the sun roller elements may be moved in the axial direction by a loading cam mechanism.

DESCRIPTION OF SYMBOLS 11 Input shaft 13 Output shaft 15 Sun roller 17 Ring roller 19 Intermediate roller 21 Connection part 22 Needle bearing 23 Loading cam mechanism 27 Fixed ring roller element (1st roller element)
29 Movable ring roller element (second roller element)
31 Support shaft (spindle shaft)
32 Swing holder (holder)
100 Friction roller reducer

Claims (1)

A sun roller disposed concentrically with the input shaft; a ring roller disposed concentrically with the sun roller on an outer peripheral side of the sun roller; and the input shaft between an outer peripheral surface of the sun roller and an inner peripheral surface of the ring roller. A plurality of intermediate rollers that are rotatably supported around a rotation axis parallel to the outer periphery of the sun roller and that are in rolling contact with the outer peripheral surface of the sun roller and the inner peripheral surface of the ring roller, and a connecting portion that connects the ring roller and the output shaft. A friction roller type speed reducer comprising a loading cam mechanism for changing the contact surface pressure of the rolling contact surface of each roller,
One of the sun roller and the ring roller is composed of a first roller element and a second roller element arranged in parallel in the axial direction of the input shaft, and the respective rolling contact surfaces are the first and second roller elements. From the opposing side end surfaces facing each other toward the outer side end surface opposite to the opposing side end surface, the distance to the center of rotation of the intermediate roller is reduced,
The loading cam mechanism is disposed only on one of the first and second roller elements on one side in the axial direction, and controls one of the first and second roller elements according to the rotational torque of the input shaft. To displace towards the other,
The intermediate roller is rotatably supported on the rotation shaft via a needle bearing, and is moved in the axial direction between the end surface of the intermediate roller and the holder by a holder that supports both ends of the rotation shaft. A friction roller type speed reducer characterized by being supported with a possible clearance.

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