JP2017048808A - Friction roller type speed reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction roller type speed reducer capable of avoiding the rolling contact faces of rollers from being excessively pushed against each other by an increase in the pressure of lubricating oil with centrifugal force when driven to be rotated in a particularly high speed, without complicating its structure, and of suppressing the occurrence of wear and damage, while maintaining an appropriate traction state all the time to actualize high power transmission efficiency.SOLUTION: A ring roller 17 of a friction roller type speed reducer 100 has a pair of roller elements 31, 33. A loading cam mechanism 23 moves one roller element 33 in the axial direction. Between one roller element 33 and a cam ring 41, hydraulic chamber 47 is formed to be filled with lubricating oil. Axial force is loaded on one roller element 33 by centrifugal hydraulic pressure generated in the hydraulic chamber 47. The cam ring 41 has a through-hole communicating the inside of the hydraulic chamber 47 with the outside. In the through-hole, a valve 39 is provided which is opened only when the hydraulic pressure in the hydraulic chamber exceeds a predetermined pressure.SELECTED DRAWING: Figure 1

Description

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

  Incorporated into a drive device for an electric vehicle such as an electric vehicle, a hybrid vehicle, or an electric four-wheel drive vehicle or a drive device for an industrial machine, the rotational drive force of a drive unit such as an electric motor is reduced and transmitted to the driven unit. A friction roller type speed reducer has been proposed (see, for example, Patent Document 1). In this type of friction roller type speed reducer, a sun roller and a ring roller are arranged coaxially, and a plurality of intermediate rollers are arranged between the sun roller and the ring roller so as to be rotatable at equal intervals in the circumferential direction. In addition, a loading cam mechanism is installed on the sun roller side, and a pressing force necessary to transmit power by a traction drive at the contact point of each roller is generated in proportion to the torque transmitted to the transmission. The rotation from the input shaft is decelerated via the sun roller, intermediate roller, and ring roller and transmitted to the output shaft.

  In the loading cam mechanism, rolling elements made of balls or rollers roll on an inclined cam surface, and generate axial thrust according to input torque. In the mechanical loading cam mechanism, the thrust is determined according to the cam angle and the input torque under any conditions, and the traction coefficient is constant. However, the limit traction coefficient μ that becomes the slip limit varies depending on the oil temperature of the lubricating oil, the peripheral speed at the contact point, the magnitude of the load, and the like. As shown in FIG. 17, the limit traction coefficient μ is lower at high power than at low power. Therefore, if the design is based on the limit traction coefficient μ at the time of high power, each roller is excessively pressed at the time of low power and causes a reduction in power transmission efficiency. Therefore, a loading cam mechanism that can change the limit traction coefficient in accordance with the operating state of the transmission is desired, and such a loading cam mechanism is proposed in Patent Document 1.

JP 2014-190537 A

In the friction roller type reduction gear of Patent Document 1, lubricating oil is guided to a mechanical loading cam and an oil chamber provided in the cam, and the loading force is assisted using centrifugal hydraulic pressure. According to this configuration, each roller can be brought close to the ideal limit traction coefficient μ. However, particularly in the high-speed rotation range in and during power transmission in the low torque (region indicated by a region A ₃ in FIG. 5), the input shaft is driven at a very high rotational speeds, formed in the input shaft outer diameter side The hydraulic pressure in the hydraulic chamber is increased due to centrifugal force. Then, the sun roller is strongly driven in the axial direction by the excessively high hydraulic pressure, and there is a concern that the rolling contact surface of each roller is excessively pressed and power transmission efficiency is lowered.

  The present invention has been made in view of the above-described matters, and its purpose is to make the rolling contact of each roller by increasing the lubricating oil pressure due to the centrifugal force when it is rotationally driven at a high speed without complicating the structure. An object of the present invention is to provide a friction roller type speed reducer that can avoid an excessive pressing state of a surface, is always in an appropriate traction state, has high power transmission efficiency, and can suppress the occurrence of wear and damage.

The present invention has the following configuration.
A sun roller disposed concentrically with the input shaft and having a rolling contact surface on the outer peripheral surface; a ring roller disposed concentrically with the sun roller around the sun roller and having a rolling contact surface on the inner peripheral surface; and the sun roller and the ring roller A plurality of intermediate rollers that are rotatably supported between the ring roller and the rolling contact surfaces of the sun roller and the ring roller, a connecting portion that connects the ring roller and the output shaft, and the rolling contact surface A friction roller type speed reducer comprising a loading cam mechanism for changing a contact surface pressure in
The ring roller has a pair of roller elements arranged side by side in the axial direction of the input shaft, and the rolling contact surface of the roller element is from the opposite end face where the pair of roller elements face each other to the opposite end face. Toward the outer end face on the opposite side in the axial direction of the intermediate roller is a sloped surface that reduces the distance to the rotation axis center line of the intermediate roller,
The loading cam mechanism has a cam ring arranged in parallel on the outer end face side of one of the pair of roller elements, and the cam ring and the one of the roller elements are related to an axial direction. Cam surfaces whose depths gradually change in the circumferential direction are formed to face each other, and rolling elements are sandwiched between the cam surface on the cam ring side and the cam surface on the one roller element side, respectively. The rotational movement around the input shaft transmitted from the input shaft to the cam ring is converted into axial movement of the one roller element by the cam surface,
A hydraulic chamber filled with lubricating oil is formed between the one roller element and the cam ring, and an axial force is applied to the one roller element by centrifugal hydraulic pressure generated in the hydraulic chamber,
The cam ring has a through-hole communicating with the inside and outside of the hydraulic chamber, and a valve that opens only when the hydraulic pressure in the hydraulic chamber exceeds a predetermined pressure is provided in the through-hole. Friction roller speed reducer.

  According to the present invention, without complicating the structure of the friction roller type speed reducer, it is possible to avoid an excessive pressing state of each roller due to an increase in lubricating oil pressure caused by centrifugal force when driven at high speed. As a result, the power transmission efficiency is always high in an appropriate traction state, and the occurrence of wear and damage can be suppressed.

It is a figure for demonstrating embodiment of this invention, and is a partial cross section perspective view of the friction roller type reduction gear of the 1st structural example. It is a principal part expanded sectional view of a friction roller type reduction gear. It is a top view of the movable roller element which shows the cam surface of a loading cam mechanism. 4A and 4B are cross-sectional views taken along line AA of FIG. 3, in which FIG. 3A is a cross-sectional view illustrating a state where torque is not applied to the loading cam mechanism, and FIG. It is a NT (output-torque) characteristic diagram of a friction roller type speed reducer. It is explanatory drawing which shows the NT characteristic diagram shown in FIG. 5, and the relationship between the spring force which the valve body of a relief valve has, and rotational speed. It is a graph which shows the relationship between the rotational speed and the pressing force to the movable roller element by the loading cam mechanism and the centrifugal hydraulic pressure in the rotational speed region where the generated input torque is constant. It is principal part sectional drawing of the friction roller type reduction gear in the state where the centrifugal hydraulic pressure is not acting in the rotation speed area | region shown in FIG. FIG. 5 is a graph showing the relationship between the rotational speed and the pressing force against the movable roller element by the loading cam mechanism and centrifugal hydraulic pressure in the region indicated by T2 in FIG. 5 (rotational speed: 0 to 17000 min ⁻¹ ). FIG. 10 is a cross-sectional view of the main part of the friction roller type speed reducer in a state where the centrifugal hydraulic pressure is applied with the relief valve closed in the rotational speed region shown in FIG. 9. It is principal part sectional drawing of the friction roller type reduction gear of the state by which the centrifugal hydraulic pressure is released in the valve opening state of a relief valve. FIG. 6 is a graph showing the relationship between the rotational speed and the pressing force to the movable roller by the loading cam mechanism and centrifugal hydraulic pressure in the region indicated by T3 in FIG. It is a partial cross section perspective view of the friction roller type reduction gear of the 2nd example of composition. It is principal part sectional drawing of the friction roller type reduction gear shown in FIG. It is explanatory drawing which shows the mode of generation | occurrence | production of an axial direction thrust. It is principal part sectional drawing which shows the modification of the friction roller type reduction gear of a 2nd structural example. It is a graph which shows the relationship between the conventionally known power and the limit traction coefficient.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First Configuration Example 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. 2 is an enlarged cross-sectional view of a main part of the friction roller type speed reducer. As shown in FIG. 1, in the friction roller type speed reducer 100, the input shaft 11 and the output shaft 13 are arranged concentrically, and the rotation input from the input shaft 11 is decelerated and transmitted to the output shaft 13. The friction roller type speed reducer 100 includes a sun roller 15 concentrically arranged with the input shaft 11, a ring roller 17, a plurality of (three in this configuration at equal intervals in the circumferential direction) intermediate rollers 19, a ring roller 17 and a loading cam mechanism 23 are provided.

  Further, the friction roller type speed reducer 100 of this configuration is provided on each of the plurality of intermediate rollers 19, and includes an intermediate roller holder 27 that rotatably supports a support shaft (spinning shaft) 25 of the intermediate roller 19, and the intermediate roller holder 27. And a carrier 29 supporting the above.

  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 roller elements arranged side by side in the axial direction, and includes a fixed roller element 31 fixed in the axial direction and a rotational direction, and a movable roller element 33 movable in the axial direction. These roller elements 31 and 33 are arranged concentrically with the sun roller 15 on the outer peripheral side of the sun roller 15 in the connecting portion 21 formed in a bottomed cylindrical shape.

  As shown in FIG. 2, the inner peripheral surfaces 31 a and 33 a of the fixed roller element 31 and the movable roller element 33 are annular inclined surfaces in which the outer edge shape of the shaft cross section is linear. These inclined surfaces are distances from the opposite end surfaces 31b and 33b of the fixed roller element 31 and the movable roller element 33 to the outer end surfaces 31c and 33c on the opposite side in the axial direction to the rotation axis center Lc of the intermediate roller 19. Is an inclined surface that becomes shorter. These inclined surfaces become rolling contact surfaces on which the intermediate roller 19 rolls. The inner peripheral surfaces 31a and 33a 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 disposed in an annular space between the outer peripheral surface 15 a of the sun roller 15 and the inner peripheral surfaces 31 a and 33 a of the ring roller 17. The outer peripheral surface 19a of the intermediate roller 19 is a convex curved surface in which the outer edge shape of the axial section is a single circular arc convex curve. The outer peripheral surface 19a serves as a traction surface that 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.

  The connecting portion 21 has a base end portion 21A and a roller holding portion 21B. 21 A of base end parts are formed in a substantially disc shape, and a center part is connected with the output shaft 13 (refer FIG. 1). The roller holding portion 21B extends in the axial direction from the outer peripheral edge of the base end portion 21A, and is formed in a cylindrical shape in which the ring roller 17 and the like are held on the inner diameter side.

  On the inner diameter side of the roller holding portion 21B, as shown in FIG. 2, in order from the base end portion 21A side, a corrugated preload spring 37 and a relief valve 39, a cam ring 41, a ball 43 as a rolling element, a movable roller element 33, a fixed roller element 31, and a retaining ring 45 are arranged. A hydraulic chamber 47 is formed between the cam ring 41 and the movable roller element 33. Details of the hydraulic chamber 47 and the relief valve 39 will be described later.

  The cam ring 41 is formed with a notch 41a in which a part of the outer diameter surface is notched in an annular shape. A preload spring 37 for pressing the cam ring 41 in the axial direction is attached to the notch 41a.

  A ring groove (not shown) extending in the circumferential direction is formed on the inner peripheral surface of the end portion on the end opposite to the base end portion 21A of the roller holding portion 21B, and a retaining ring 45 is fitted into the ring groove. The The retaining ring 45 fixes the fixed ring roller element 31 to the roller holding portion 21B in a state where the axial position is restricted.

<Loading cam mechanism>
Next, the loading cam mechanism 23 will be described.
The movable roller element 33, the cam ring 41, and the ball 43 constitute a loading cam mechanism 23. 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. Further, the friction roller type speed reducer 100 of this configuration is provided with a hydraulic chamber 47 between the ring roller 17 and the cam ring 41 in order to assist the loading force for changing the contact surface pressure.

  FIG. 3 is a plan view of the movable roller element 33 showing the cam surface of the loading cam mechanism 23. Note that the shape and arrangement of the cam surface shown in FIG. In the following description, the same members or the same parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  A plurality of (three in the illustrated example) first cam surfaces 51 are formed on the outer end surface 33c of the movable roller element 33 along the circumferential direction. Similarly, with respect to the end surface of the cam ring 41 facing the movable roller element 33, a plurality of the circumferential surfaces of the cam ring 41 corresponding to the first cam surface 51 of the movable roller element 33 face the first cam surface 51. Second cam surfaces 53 (see FIG. 2) are formed (three locations in the illustrated example). Balls 43 are sandwiched between the first cam surface 51 and the second cam surface 53, respectively. In place of the balls 43, rollers may be used.

  The axial groove depths of the first cam surface 51 and the second cam surface 53 are the deepest in the central portion with respect to the circumferential direction, and gradually change along the circumferential direction. It becomes shallower toward the direction end.

  4 is a cross-sectional view taken along the line A-A in FIG. 3 and shows a state (A) in which no torque is applied to the loading cam mechanism 23 and a state (B) in which torque is applied. In a state where no torque is applied to the input shaft 11, as shown in FIG. 4A, the balls 43 are arranged at the deepest portions of the cam surfaces 51 and 53. In this state, the cam ring 41 is pressed toward the movable roller element 33 by the elastic force of the preload spring 37 (see FIG. 2).

  When torque is applied to the input shaft 11, each ball 43 moves to a shallow portion of each cam surface 51, 53 as shown in FIG. As a result, an axial thrust F1 that presses the movable roller element 33 toward the fixed roller element 31 is generated.

  The movable roller element 33 is loaded with an axial thrust F1 generated by the loading cam mechanism 23 and an axial thrust F2 generated by lubricating oil pressure in a hydraulic chamber 47 described later. Then, the movable roller element 33 shown in FIG. 2 moves to the fixed roller element 31 side, and the interval between the fixed roller element 31 and the movable roller element 33 is reduced. Then, the contact position between the inclined surfaces of the inner peripheral surfaces 31a and 33a of the ring roller 17 and the outer peripheral surface 19a of the intermediate roller 19 changes, and the contact at the rolling contact surfaces of the ring roller 17, the intermediate roller 19 and the sun roller 15 changes. Each contact pressure increases. As a result, as the transmission torque between the input shaft 11 and the output shaft 13 increases, the contact surface pressure of the plurality of rolling contact surfaces existing between the input shaft 11 and the output shaft 13 increases.

  According to the friction roller type speed reducer 100 configured as described above, the rotational torque of the input shaft 11 is transmitted to the ring roller 17 via the intermediate roller 19. The movable roller element 33 of the ring roller 17 is displaced in the axial direction by the loading cam mechanism 23 to change the contact surface pressure on the rolling contact surface of each roller. Then, the rotational torque transmitted to the ring roller 17 is transmitted to the output shaft 13 via the connecting portion 21. In this way, the rotation of the input shaft 11 is transmitted to the output shaft 13 at a reduced speed while suppressing the occurrence of slip between the rollers.

<Configuration of hydraulic chamber and its action>
Next, the hydraulic chamber 47 and the relief valve 39 will be described.
The hydraulic chamber 47 is formed in an annular space in a region W surrounded by a dotted line between the movable roller element 33 and the cam ring 41 shown in FIG. The cam ring 41 includes an outer diameter side annular portion 55 that extends from the outer diameter portion of the end surface 41b where the second cam surface 53 is formed toward the ring roller 17 along the axial direction. The outer diameter side annular portion 55 is disposed so as to cover the outer peripheral surface of the movable roller element 33.

  An annular groove 57 is formed on the outer peripheral surface of the movable roller element 33, and an annular oil seal 59 is loaded in the groove 57. The oil seal 59 contacts the inner peripheral surface of the outer diameter side annular portion 55 and the outer peripheral surface of the movable roller element 33 and seals the outer diameter side of the hydraulic chamber 47 in a liquid-tight manner.

  Tapered surfaces 33d and 41c are formed on the inner peripheral surface end portions of the movable roller element 33 and the cam ring 41 facing each other so that the axial interval of the hydraulic chamber 47 becomes narrower radially outward.

  In the cam ring 41, a through hole 61 that penetrates the cam ring 41 in the axial direction is formed in the outer diameter portion of the end surface 41 b facing the movable roller element 33. A relief valve 39 is provided in the outer opening of the through hole 61. The relief valve 39 is fixed to the cam ring 41 with one end opening of the outer casing 39 a communicating with the through-hole 61. Further, the proximal end side of the inner valve body 39 b is fixed to the proximal end portion 21 </ b> A of the connecting portion 21. The valve body 39b is pressed against the valve opening in the casing 39a and elastically deforms with a predetermined spring force. Thereby, the casing 39a and the valve body 39b function as a relief valve.

  When the friction roller type speed reducer 100 is rotationally driven, the lubricating oil supplied into the connecting portion 21 flows into the gap between the movable roller element 33 and the cam ring 41. At this time, the tapered surfaces 33d and 41c formed on the movable roller element 33 and the cam ring 41 direct the adhering liquid droplets of the lubricating oil scattered by the centrifugal force from the intermediate roller 19 or the like toward the hydraulic chamber 47 and take in the lubricating oil. Improves efficiency.

  As a result, the hydraulic chamber 47 is filled with the lubricating oil. As the rotational speed of the input shaft 11 increases, the rotational speed of the movable roller element 33 and the cam ring 41 also increases, and the hydraulic pressure in the hydraulic chamber 47 is increased by the centrifugal force. The hydraulic pressure in the hydraulic chamber 47 increased by the centrifugal force acts on the outer end surface of the movable roller element 33 to cause the movable roller element 33 to generate an axial thrust F2 toward the fixed roller element 31.

  The axial thrust F2 and the axial thrust F1 of the loading cam mechanism 23 described above act on the movable roller element 33. Therefore, the higher the rotational speed, the stronger the assist of the axial thrust F2, and the contact pressure on the rolling contact surface of each roller increases. Further, as the rotational speed becomes lower, the centrifugal force becomes weaker and the assist by the axial thrust F2 becomes weaker. As a result, the contact pressure on the rolling contact surface at a low rotational speed does not become excessive, and the limit traction coefficient of the friction roller type reduction gear 100 can be optimally maintained in a speed range from low speed to high speed. Thereby, power transmission efficiency improves.

  FIG. 5 is an NT (output-torque) characteristic diagram of the friction roller type reduction gear 100. In the high rotational speed and low torque region A3 in this NT characteristic diagram, the ring roller 17 and the cam ring 41 rotate at a high speed, so that the hydraulic pressure in the hydraulic chamber 47 is greatly increased by the centrifugal force. For this reason, there is a possibility that an excessive axial force acts on the movable roller element 33 to excessively increase the contact pressure on the rolling contact surface of each roller.

  However, according to the friction roller type speed reducer 100 of this configuration, the relief valve 39 is connected to the hydraulic chamber 47, and the relief valve 39 releases the hydraulic pressure that has become excessive due to centrifugal force to the outside of the hydraulic chamber 47. To do. Thereby, especially in the region A3 that is driven to rotate at a high speed, the contact pressure on the rolling contact surface of each roller can be set to an appropriate level to prevent excessive pressure.

  That is, the relief valve 39 can prevent the rolling contact surface of each roller from being excessively pressed by switching from the closed state to the open state when the outer opening of the through hole 61 reaches a predetermined pressure. . The valve opening value of the relief valve 39 is set using the rotational speed of the input shaft 11 instead of the pressure value for convenience.

  FIG. 6 is an explanatory diagram showing the relationship between the NT characteristic diagram and the spring force and the rotational speed of the valve body 39b of the relief valve 39. The spring force of the valve body 39b of the relief valve 39 is set so as to increase as the rotational speed increases in the range up to the maximum rotational speed va in the maximum power region. On the other hand, in a range exceeding the maximum rotational speed va, the spring force is set to a constant magnitude regardless of the rotational speed. As a result, even if the rotational speed becomes particularly high, further increase in the hydraulic pressure due to centrifugal force is prevented in the hydraulic chamber 47, and the hydraulic pressure is kept constant.

<Specific example of drive and description of state of hydraulic chamber>
Next, an example of driving the friction roller type speed reducer 100 configured as described above and the state of the hydraulic chamber 47 will be sequentially described.
As an example, a description will be given of a case where a friction roller speed reducer having the characteristics that the maximum rotational speed is 30000 min ⁻¹ and the maximum rotational speed at the maximum torque is 10000 min ⁻¹ shown in the NT characteristic diagram of FIG.

FIG. 7 is a graph showing the relationship between the rotational speed and the pressing force to the movable roller element 33 by the loading cam mechanism 23 and the centrifugal hydraulic pressure in the rotational speed region where the generated input torque is constant. FIG. 7 shows the relationship in the maximum input torque region (rotational speed: 0 to 10000 min ⁻¹ ) indicated by T1 in FIG. FIG. 8 is a cross-sectional view of a main part of the friction roller type speed reducer 100 in a state where hydraulic pressure (centrifugal pressure) due to centrifugal force is not applied in the rotation speed region shown in FIG.

Since the loading cam mechanism 23 in this case has a constant input torque, the generated axial thrust F1 is constant regardless of the rotational speed. Further, since the hydraulic pressure in the hydraulic chamber 47 is lower than a predetermined value, the relief valve 39 is closed. Therefore, in the hydraulic chamber 47, the centrifugal hydraulic pressure increases as the rotational speed increases. Therefore, the axial thrust F2 generated by the hydraulic pressure increases as the rotational speed increases. Further, since the maximum rotation speed is 10,000 min ⁻¹ , the valve opening value (rotation speed) at which the relief valve 39 opens is set to 10000 min ⁻¹ .

FIG. 9 is a graph showing the relationship between the rotational speed and the pressing force to the movable roller element 33 by the loading cam mechanism 23 and the centrifugal hydraulic pressure in the region indicated by T2 in FIG. 5 (rotational speed: 0 to 17000 min ⁻¹ ). . FIG. 10 is a cross-sectional view of the main part of the friction roller type speed reducer 100 in the rotational speed region shown in FIG.

In this case, the loading cam mechanism 23 is filled with lubricating oil in the hydraulic chamber 47 and the through hole 61, and the hydraulic pressure in the hydraulic chamber 47 increases as the rotational speed increases. When the rotational speed reaches 10,000 min ⁻¹ , the relief valve 39 is opened.

FIG. 11 is a cross-sectional view of a main part of the friction roller type speed reducer 100 in a state where the centrifugal hydraulic pressure is released with the relief valve 39 opened. When the relief valve 39 is in the open state, the lubricating oil in the hydraulic chamber 47 flows from the relief valve 39 to the outside of the hydraulic chamber 47 through the through hole 61, and an increase in the hydraulic pressure in the hydraulic chamber 47 is prevented from becoming excessive. . Accordingly, when the rotational speed is 10,000 min ⁻¹ or more, the centrifugal hydraulic pressure is constant, and the pressing force against the movable roller element 33 is constant. Thereby, an excessive contact pressure does not arise in the rolling contact surface of each roller.

  FIG. 12 is a graph showing the relationship between the rotational speed and the pressing force to the movable roller element 33 by the loading cam mechanism 23 and the centrifugal hydraulic pressure in the region indicated by T3 in FIG.

The loading cam mechanism 23 in this case, the rotational speed but power is maximized at 30000Min ^-1, relief valve 39 when the rotational speed reaches 10000 min ^-1 is opened. Therefore, when the rotational speed is 1000 min ⁻¹ or more, the centrifugal hydraulic pressure is constant. As a result, as described above, the pressing force to the movable roller element 33 is constant, and excessive contact pressure does not occur on the rolling contact surface of each roller.

  As described above, according to the friction roller type speed reducer 100 of this configuration, in the low rotation range of the input shaft 11, the pressing force proportional to the input torque by the centrifugal hydraulic pressure is added to the constant pressing force by the loading cam mechanism 23. Is added to assist the pressing to the movable roller element 33. When the input shaft 11 reaches a rotational speed that is equal to or higher than the set rotational speed, the relief valve 39 is opened and the hydraulic pressure in the hydraulic chamber 47 is kept constant. Thereby, it can prevent that the contact surface pressure in the rolling contact surface of each roller is raised excessively, and the limit traction coefficient at the time of operation can be optimized. As a result, the power transmission efficiency of the reduction gear can be improved.

  Further, the hydraulic pressure in the hydraulic chamber 47 is increased by the centrifugal force between the movable roller element 33 and the cam ring 41, as the rotation of the input shaft 11 is transmitted to the ring roller 17 via the sun roller 15 and the intermediate roller 19. Therefore, it is not necessary to arrange a pump for supplying lubricating oil to the hydraulic chamber 47 and a pressure adjusting mechanism, and the configuration of the speed reducer is not complicated. Further, the hydraulic chamber for generating the centrifugal hydraulic pressure of this configuration is disposed inside the loading cam mechanism 23. As a result, the axial length is not unnecessarily increased as compared with the case where it is separately provided in a portion different from the hydraulic chamber 47 in the illustrated example, and a more compact configuration can be achieved. Further, the lubricating oil can be stably supplied to the first and second cam surfaces 51 and 53 (see FIG. 2), and damage due to fretting wear or the like can be prevented.

<Second Example of Friction Roller Reducer>
Next, a second configuration example of the friction roller type speed reducer will be described.
FIG. 13 is a partial cross-sectional perspective view of the friction roller type speed reducer configured as described above, and FIG. 14 is a cross-sectional view of the main part of the friction roller type speed reducer shown in FIG. The friction roller type speed reducer 200 generates an axial thrust force applied to the movable roller element 33 by hydraulic pressure.

  As shown in FIGS. 13 and 14, the friction roller type speed reducer 200 of this configuration has the input shaft 11 and the output shaft 13 arranged concentrically, and decelerates the rotation input from the input shaft 11 to the output shaft 13. Communicate. The friction roller type speed reducer 200 includes a sun roller 15 (see FIG. 14) disposed concentrically with the input shaft 11, a ring roller 17, and a plurality of (three in the present configuration at equal intervals in the circumferential direction) intermediate rollers. 19, a connecting portion 21 that connects the ring roller 17 and the output shaft 13, and a loading drive portion 71.

  The friction roller type speed reducer 200 includes a loading drive unit 71 instead of the loading cam mechanism 23 and the hydraulic chamber 47 that generate an axial thrust force applied to the movable roller element 33 of the friction roller type speed reducer 100 described above. . Other than that, it is the same structure as the above-mentioned friction roller type reduction gear 200. FIG.

  In the loading drive unit 71 of this configuration, an annular piston member 73 is disposed between the movable roller element 33 and the connecting unit 21. The piston member 73 includes a cylindrical outer diameter portion 73a and an annular piston portion 73b that extends radially inward from one axial end of the outer diameter portion 73a.

  Splines are formed on the outer peripheral surface of the outer diameter portion 73 a of the piston member 73 and the inner peripheral surface of the roller holding portion 21 </ b> B of the connecting portion 21. Splines are formed on the inner peripheral surface of the outer diameter portion 73a of the piston member 73 and the outer peripheral surface of the centrifugal hydraulic canceller 13a that is integrally extended from the output shaft 13 toward the radially outer side. When these splines are fitted to each other, torque transmission with the ring roller 17 is performed. Since the spline can move in the axial direction and is always lubricated, the friction in the axial direction is reduced and stabilized, and fretting wear can be suppressed.

  Further, a hydraulic chamber 75 is formed between the piston portion 73b and the base end portion 21A of the connecting portion 21, and the piston portion 73b and the centrifugal hydraulic canceller 13a are disposed on the opposite side of the piston portion 73b from the side surface of the centrifugal hydraulic canceller 13a. A hydraulic cancel chamber 77 is formed.

  The hydraulic chamber 75 and the hydraulic cancel chamber 77 are arranged between the outer diameter portion 73a of the piston member 73 and the roller holding portion 21B of the coupling portion 21 and the piston member so that the lubricating oil supplied to the inside of each chamber does not leak. 73 between the outer diameter portion 73a of the output shaft 13 and the centrifugal hydraulic canceller 13a of the output shaft 13, between the inner peripheral end of the base end portion 21A of the connecting portion 21 and the output shaft 13, and the inner peripheral end of the piston member 73 and the output shaft. An oil seal S is disposed between each of them.

  The piston member 73 is disposed so as to be movable in the axial direction. In the output shaft 13, a lubricating oil passage 79 for supplying lubricating oil to the hydraulic chamber 75 is formed, and the lubricating oil is introduced into the hydraulic chamber 75 through the lubricating oil passage 79. The lubricating oil filled in the hydraulic chamber 75 generates axial thrust that presses the piston member 73 toward the ring roller 17.

  FIG. 15 shows how the axial thrust is generated. When each roller rotates, the piston member 73 moves to the movable roller element 33 side and an axial thrust is applied to the movable roller element 33. Thereby, the contact surface pressure in the rolling contact surface of each roller can be increased.

  On the other hand, in the oil pressure cancellation chamber 77, lubricating oil flowing along the output shaft 13 from the intermediate roller 19 side is introduced. That is, a through hole 81 is formed in the centrifugal hydraulic canceller 13 a, and the lubricating oil flows into the hydraulic pressure cancel chamber 77 through the through hole 81.

  Centrifugal force acts on the lubricating oil in the hydraulic chamber 75 due to the rotation of the piston member 73 and the surrounding connecting portion 21 and the output shaft 13, and the hydraulic pressure in the hydraulic chamber 75 increases. Due to the increase in the hydraulic pressure, the piston member 73 tries to increase the axial thrust applied to the movable roller element 33 in combination with the hydraulic pressure supplied from the lubricating oil passage 79. However, also in the hydraulic pressure cancellation chamber 77, the hydraulic pressure in the hydraulic pressure cancellation chamber 77 increases due to the centrifugal force. The increased hydraulic pressure in the hydraulic pressure canceling chamber 77 cancels the increased hydraulic pressure in the hydraulic chamber 75, and the generated centrifugal hydraulic pressure is offset.

  When the centrifugal hydraulic pressure is offset as described above, the influence of centrifugal force is extremely reduced. Therefore, it is possible to adjust the axial thrust (loading force) of the movable roller element 33 only by considering only the axial force generated in the piston member 73 by the lubricating oil pressure supplied from the lubricating oil passage.

  A preload spring 37 that urges the piston member 73 in the axial direction toward the movable roller element 33 is disposed between the piston member 73 and the base end portion 21 </ b> A of the connecting portion 21. The preload spring 37 generates a preload when the speed reducer is stopped, in which no hydraulic pressure is generated, and prevents a gloss slip from occurring in each roller at the time of activation.

  Further, the piston member 73 has a larger surface area of the piston member 73 facing the hydraulic chamber 75 than the surface area of the piston member 73 facing the hydraulic cancel chamber 77. For this reason, the axial thrust generated on the hydraulic chamber 75 side is larger than the axial thrust generated on the hydraulic cancel chamber 77, and the piston member 73 is prevented from being driven away from the movable roller element 33.

  According to the loading drive unit 71 configured as described above, a necessary and sufficient axial thrust can be generated in the movable roller element 33 even when the lubricating oil pressure is about 0.5 MPa, for example. For this reason, it is not necessary to separately add a hydraulic pump, the entire apparatus can be reduced in size, and the apparatus cost can be reduced.

<Modification>
FIG. 16 is a cross-sectional view of an essential part showing a modification of the friction roller type speed reducer of the second configuration example.
The friction roller type speed reducer according to the present modified example has a connecting portion instead of the spline-fitting configuration of the outer diameter portion 73a of the piston member 73, the roller holding portion 21B of the connecting portion 21 and the centrifugal hydraulic canceller 13a. Spline 83 is formed in the inner diameter part of 21 base end part 21A and the outer-diameter surface of the output shaft 13, respectively. With this spline 83, torque transmission with the ring roller 17 can be performed at one place.

  Since this spline 83 is capable of axial movement between the base end portion 21A and the output shaft 13 and is always lubricated, axial friction is reduced and stabilized, and fretting wear can be suppressed.

  As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can make changes and applications based on combinations of the configurations of the embodiments, descriptions in the specification, and well-known techniques. This is also the scope of the present invention, and is included in the scope of seeking protection.

As described above, the following items are disclosed in this specification.
(1) a sun roller disposed concentrically with the input shaft and having a rolling contact surface on an outer peripheral surface; a ring roller disposed concentrically with the sun roller around the sun roller and having a rolling contact surface on an inner peripheral surface; and the sun roller; A plurality of intermediate rollers that are rotatably supported between the ring roller and are in rolling contact with the rolling contact surfaces of the sun roller and the ring roller, respectively, 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 a contact surface pressure on a rolling contact surface,
The ring roller has a pair of roller elements arranged side by side in the axial direction of the input shaft, and the rolling contact surface of the roller element is from the opposite end face where the pair of roller elements face each other to the opposite end face. Toward the outer end face on the opposite side in the axial direction of the intermediate roller is a sloped surface that reduces the distance to the rotation axis center line of the intermediate roller,
The loading cam mechanism has a cam ring arranged in parallel on the outer end face side of one of the pair of roller elements, and the cam ring and the one of the roller elements are related to an axial direction. Cam surfaces whose depths gradually change in the circumferential direction are formed to face each other, and rolling elements are sandwiched between the cam surface on the cam ring side and the cam surface on the one roller element side, respectively. The rotational movement around the input shaft transmitted from the input shaft to the cam ring is converted into axial movement of the one roller element by the cam surface,
A hydraulic chamber filled with lubricating oil is formed between the one roller element and the cam ring, and an axial force is applied to the one roller element by centrifugal hydraulic pressure generated in the hydraulic chamber,
The cam ring has a through-hole communicating with the inside and outside of the hydraulic chamber, and a valve that opens only when the hydraulic pressure in the hydraulic chamber exceeds a predetermined pressure is provided in the through-hole. Friction roller speed reducer.
According to this friction roller type speed reducer, when the hydraulic pressure in the hydraulic chamber exceeds a predetermined pressure, the valve opens to prevent the contact surface pressure on the rolling contact surface of each roller from being excessively increased, The critical traction coefficient during operation can be optimized. As a result, the power transmission efficiency of the reduction gear can be improved.
(2) a sun roller disposed concentrically with the input shaft and having a rolling contact surface on an outer peripheral surface; a ring roller disposed concentrically with the sun roller around the sun roller and having a rolling contact surface on an inner peripheral surface; and the sun roller; A plurality of intermediate rollers that are rotatably supported between the ring roller and are in rolling contact with the rolling contact surfaces of the sun roller and the ring roller, respectively, and a connecting portion that connects the ring roller and the output shaft; A friction roller type speed reducer comprising: a loading drive unit that changes a contact surface pressure in a rolling contact surface;
The ring roller has a pair of roller elements arranged side by side in the axial direction of the input shaft, and the rolling contact surface of the roller element is from the opposite end face where the pair of roller elements face each other to the opposite end face. Toward the outer end face on the opposite side in the axial direction of the intermediate roller is a sloped surface that reduces the distance to the rotation axis center line of the intermediate roller,
The loading drive unit includes:
A piston member that has a pressing portion that axially presses an outer end portion of any one of the pair of roller elements in an axial direction, and is disposed between the one roller element and the coupling portion;
A hydraulic chamber that is formed between the piston member and the connecting portion, and that generates the axial thrust according to the hydraulic pressure and centrifugal hydraulic pressure supplied according to the axial thrust applied to the one roller element;
A hydraulic cancel chamber formed on the opposite side of the hydraulic chamber of the piston member, and generating an axial thrust opposite to the axial thrust by the centrifugal hydraulic pressure generated in the hydraulic chamber;
Have
The friction roller type speed reducer according to claim 1, wherein a surface area of the piston member facing the hydraulic chamber is larger than a surface area of the piston member facing the hydraulic cancel chamber.
According to this friction roller type speed reducer, the centrifugal hydraulic pressure generated in the hydraulic chamber can be canceled by the centrifugal hydraulic pressure generated in the hydraulic cancel chamber. Therefore, since the loading force according to the operating conditions can be variably adjusted by the hydraulic pressure applied to the hydraulic chamber, the friction roller type speed reducer can be operated with the optimum traction coefficient. As a result, power transmission efficiency can be improved.
(3) The friction roller type speed reducer according to (2), further comprising a preload portion that urges the piston member in the axial direction toward the one roller element.
According to this friction roller type speed reducer, even when no torque acts on the input shaft, one roller element can be pressed against the other roller element, and the contact at the rolling contact surface of each roller Surface pressure can be secured.

DESCRIPTION OF SYMBOLS 11 Input shaft 13 Output shaft 15 Sun roller 17 Ring roller 19 Intermediate roller 21 Connecting part 23 Loading cam mechanism 25 Support shaft (spinning shaft)
31 Fixed roller element (roller element)
31a Inner peripheral surface 31b Opposite side end surface 31c Outer end surface 33 Movable roller element (roller element)
33a Inner peripheral surface 33b Opposite side end surface 33c Outer end surface 37 Preload spring 39 Relief valve (valve)
41 cam ring 43 ball (rolling element)
47 Hydraulic chamber 51 First cam surface 53 Second cam surface 100 Friction roller type speed reducer

Claims (1)

A sun roller disposed concentrically with the input shaft and having a rolling contact surface on the outer peripheral surface; a ring roller disposed concentrically with the sun roller around the sun roller and having a rolling contact surface on the inner peripheral surface; and the sun roller and the ring roller A plurality of intermediate rollers that are rotatably supported between the ring roller and the rolling contact surfaces of the sun roller and the ring roller, a connecting portion that connects the ring roller and the output shaft, and the rolling contact surface A friction roller type speed reducer comprising a loading cam mechanism for changing a contact surface pressure in
The ring roller has a pair of roller elements arranged side by side in the axial direction of the input shaft, and the rolling contact surface of the roller element is from the opposite end face where the pair of roller elements face each other to the opposite end face. Toward the outer end face on the opposite side in the axial direction of the intermediate roller is a sloped surface that reduces the distance to the rotation axis center line of the intermediate roller,
The loading cam mechanism has a cam ring arranged in parallel on the outer end face side of one of the pair of roller elements, and the cam ring and the one of the roller elements are related to an axial direction. Cam surfaces whose depths gradually change in the circumferential direction are formed to face each other, and rolling elements are sandwiched between the cam surface on the cam ring side and the cam surface on the one roller element side, respectively. The rotational movement around the input shaft transmitted from the input shaft to the cam ring is converted into axial movement of the one roller element by the cam surface,
A hydraulic chamber filled with lubricating oil is formed between the one roller element and the cam ring, and an axial force is applied to the one roller element by centrifugal hydraulic pressure generated in the hydraulic chamber,
The cam ring has a through-hole communicating with the inside and outside of the hydraulic chamber, and a valve that opens only when the hydraulic pressure in the hydraulic chamber exceeds a predetermined pressure is provided in the through-hole. Friction roller speed reducer.

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