JP2018189206A - Friction roller type reduction gear and reduction gear unit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction roller type reduction gear that can obtain high power transmission efficiency without being influenced by centrifugal oil pressure, can reduce the axial length of the reduction gear itself, and never lowers mountability on a vehicle, and a reduction gear unit using the same.SOLUTION: A friction roller type reduction gear comprises a sun roller 15 consisting of a movable sun roller element 35 and a fixed sun roller element 37, a ring roller 17, a plurality of intermediate rollers 19, and a loading disk 24. Rolling contact surfaces of the sun roller 15 and intermediate roller 19 are inclined surfaces increasing in radius distance to an input shaft 11 from opposite-side end faces 41, 43 to outside end faces 45, 47 of the sun roller element. A main oil chamber 89 is formed between the movable sun roller element 35 and loading disk, and a canceller oil chamber 91 which generates axial force for reducing the centrifugal oil pressure is formed between the movable sun roller element 35 and fixed sun roller element 37.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a friction roller type speed reducer and a speed reducer unit using the same.

  There is known a friction roller type speed reducer that is connected to an output shaft of an electric motor serving as a drive source of an electric vehicle, and that reduces the rotation of the motor output shaft and transmits it to drive wheels (for example, Patent Documents 1 and 2). As shown in FIGS. 10A and 10B as an example, this friction roller type speed reducer is in contact with the sun roller 303 attached to the input shaft 301 connected to the motor output shaft and the outer peripheral surface of the sun roller 303. A plurality of intermediate rollers 305, a ring roller 307 arranged concentrically with the sun roller 303 and in contact with the inner roller 305, and a loading cam mechanism 309. The ring roller 307 is connected to the output shaft of the speed reducer. In the friction roller type speed reducer configured as described above, the sun roller 303 transmits the rotational torque from the electric motor to the ring roller 307 via the intermediate roller 305. The rotational torque of the ring roller 307 is taken out from the output shaft of the speed reducer.

  The illustrated sun roller 303 includes a pair of sun roller elements 311 and 313. One sun roller element 311 is fixed to the input shaft 301. The other sun roller element 313 is fixed to the input shaft 301 in the rotational direction and is supported so as to be movable in the axial direction. A loading disk 315 is disposed on the back surface of the sun roller element 313 opposite to the sun roller element 311. The loading disk 315 is fixed to the input shaft 301. Cam grooves 317 and 319 are formed on the back surface of the sun roller element 313 and one end surface of the loading disk 315 facing the back surface, and a ball 321 is disposed between the cam grooves 317 and 319. As the rotational torque from the input shaft 301 increases, the loading cam mechanism 309 increases the normal force in the traction surface normal direction to the intermediate roller 305 as the sun roller element 313 moves in the axial direction.

  The loading cam mechanism 309 is disposed only on one side of the sun roller 303 in the axial direction. However, as shown in FIG. 11, the loading cam mechanism 309A is disposed facing the sun roller element 314 in which the cam groove 317 is formed. Also, a configuration in which the loading cam mechanism 309B is disposed facing the sun roller element 313, that is, a structure in which the loading cam mechanisms 309A and 309B are disposed on both sides in the axial direction of the sun roller 303A including the sun roller elements 313 and 314 can be adopted.

JP 2012-207778 A JP 2014-190537 A

As a mechanism for applying an axial force to the sun roller element, a torque sensitive type mechanism such as the loading cam mechanism shown in FIGS. 10A and 10B and FIG. 11 or a fixed pressing type mechanism using a spring is often employed. Is done. In the case of the loading cam mechanism, in order to ensure the minimum axial force in the low torque region of the transmission torque, there are many types that use a combination of a spring and a loading cam.
This loading cam mechanism is highly robust because it generates an axial force proportional to the passing torque based on the traction coefficient determined at the time of design under any operating condition. However, a mechanical loading device such as a loading cam mechanism has a disadvantage that the traction coefficient cannot be changed in accordance with changes in operating conditions such as operating temperature and passing torque.
In the friction roller type reduction gears for automobiles, the operating conditions such as operating temperature and passing torque are constantly changing, and the limit traction coefficient that is the limit of occurrence of gross slip on the traction surface is always changing. When the traction coefficient exceeds the limit traction coefficient, gloss slip occurs on the traction surface, and damage such as seizure may occur particularly under conditions where the passing power is severe.
Therefore, in the mechanical loading device described above, the design traction coefficient is determined in consideration of a considerable margin so that the traction coefficient during operation does not exceed the constantly changing limit traction coefficient.

  In general, in the traction curve of traction oil (characteristic curve with the horizontal axis being creep and the vertical axis being the traction coefficient), the design traction coefficient is often determined within a region where the traction curve is in a proportional relationship. In this proportional region, the higher the traction coefficient, the more the axial force decreases, so that power transmission efficiency is improved. For this reason, in the torque-sensitive mechanical loading device, it is necessary to allow a sufficient margin with respect to the gross slip generation limit as described above, so there is room for improvement in improving the power transmission efficiency.

In addition, in order to improve power transmission efficiency, a hydraulic type that can arbitrarily adjust the axial force according to the operating conditions, considering not only the transmission torque but also the temperature of the traction oil during operation and other factors Is preferably adopted.
However, when a hydraulic loading device is employed, centrifugal hydraulic pressure depending on the rotation speed is generated. This centrifugal hydraulic pressure generates an axial force proportional to the square of the rotational speed and proportional to the mass of the traction oil. As a result, particularly in the low torque and high rotation speed regions, the centrifugal hydraulic pressure acts more than the pressing force required on the traction surface, and the power transmission efficiency may be reduced due to excessive pressing force.
In order to eliminate such an influence, a caser oil chamber that cancels centrifugal force acting on the main oil chamber may be provided at a position adjacent to the main oil chamber. In that case, the main oil chamber is usually arranged outside in the axial direction between the two sun roller elements. However, if the canceller oil chamber is further provided after the main oil chamber is provided, it is inevitable that the axial length of the friction roller type speed reducer becomes large. As a result, the degree of freedom of the layout of the friction roller type speed reducer is impaired, and the mountability on the vehicle may be reduced.

  Therefore, the present invention can achieve high power transmission efficiency without being affected by centrifugal hydraulic pressure even when a hydraulic loading device is adopted, and can reduce the axial length of the reducer itself, thereby reducing the mountability to a vehicle. It is an object of the present invention to provide a friction roller type speed reducer that does not occur and a speed reducer unit using the same.

The present invention has the following configuration.
(1) A sun roller disposed concentrically with the input shaft, a ring roller disposed concentrically with the sun roller on the outer peripheral side of the sun roller and coupled to the output shaft, an outer peripheral surface of the sun roller, and an inner periphery of the ring roller A plurality of intermediate rollers in rolling contact with a surface, and a friction roller type speed reducer comprising:
The sun roller has a pair of sun roller elements arranged in parallel in the axial direction of the input shaft,
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller have a longer radial distance from the opposite end surface of the sun roller elements toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. An inclined surface,
One of the sun roller elements is a movable sun roller element that is axially movable with respect to the input shaft and is supported so as not to rotate.
The other sun roller element is a fixed sun roller element that is supported so as not to move and rotate in the axial direction with respect to the input shaft,
The movable sun roller element is disposed to face the axially outer end surface opposite to the fixed sun roller element side, transmits the rotation of the input shaft to the movable sun roller element, and the outer peripheral surface of the movable sun roller element and the input shaft Has a slidable loading disc on the outer peripheral surface of
An axial direction in which the movable sun roller element is brought closer to the fixed sun roller element by supplying traction oil between an axially outer end face of the movable sun roller element and one end face of the loading disk facing the axial outer end face. A main oil chamber that generates force is formed,
A canceller oil chamber is formed between the movable sun roller element and the fixed sun roller element, and traction oil is supplied to generate an axial force that reduces centrifugal hydraulic pressure generated in the main oil chamber by rotation of the input shaft. Friction roller type reducer.
(2) the friction roller type speed reducer,
A hydraulic pressure supply unit that individually supplies traction oil to each of the main oil chamber and the canceller oil chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure control unit for increasing or decreasing the oil pressure of the main oil chamber according to the detected operating condition;
Reducer unit with.

  In the present invention, even when a hydraulic loading device is employed, high power transmission efficiency can be obtained without being affected by centrifugal hydraulic pressure, and the axial length of the speed reducer itself can be shortened, so that mounting on a vehicle is reduced. There is nothing.

It is a partial cross section perspective view of the friction roller type reduction gear of this invention. It is a principal part enlarged view of the friction roller type reduction gear shown in FIG. It is sectional drawing of the AA line shown in FIG. It is principal part sectional drawing of the sun roller element supported by an input shaft, and a loading disk. It is a partial expanded sectional view of a main oil chamber and a canceller oil chamber. (A), (B) is explanatory drawing which shows a mode that the axial direction position of a sun roller element is changed with the oil_pressure | hydraulic of a main oil chamber. It is explanatory drawing which shows the relationship between the normal force and tangential force which act on a drive roller and a driven roller. It is a graph which shows the characteristic curve of the traction coefficient with respect to the temperature of traction oil. It is a schematic block block diagram of a reduction gear unit. (A), (B) is typical operation explanatory drawing of the conventional loading cam mechanism. It is typical operation explanatory drawing of the other conventional loading cam mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<Basic configuration of friction roller reducer>
FIG. 1 is a partially sectional perspective view of a friction roller type speed reducer according to the present invention, and FIG. 2 is an enlarged view of a main part of the friction roller type speed reducer shown in FIG.
In the friction roller type speed reducer 100, an input shaft 11 connected to a motor (not shown) that generates power and an output shaft 13 are arranged concentrically, and rotational power input from the input shaft 11 is applied to the output shaft 13. Transmit while decelerating. The friction roller type speed reducer 100 includes a sun roller 15 disposed coaxially with the input shaft 11, a ring roller 17, a plurality of (three as an example in the present configuration) intermediate rollers 19, and a loading disk 24. . The ring roller 17 is connected to the output shaft 13 by a ring roller holder 21. The intermediate roller 19 is in rolling contact with the outer peripheral surface of the sun roller 15 and the inner peripheral surface of the ring roller 17, and is supported by the housing 20 via the swing holder 25 and the carrier 27.

  In the intermediate roller 19, both end portions of a support shaft 22 extending on the central axis of the intermediate roller 19 are supported by a swing holder 25 via a rolling bearing 23. The swing holder 25 is supported by the carrier 27 so as to be movable in the axial direction in a state where the support shaft 22 is parallel to the input shaft 11. The carrier 27 supports the plurality of swinging holders 25 that support the intermediate roller 19 having the above-described configuration at equidistant positions along the circumferential direction.

  The ring roller 17 is fixed with respect to the housing 20 in the axial direction. The intermediate roller 19 is supported so as to be movable in the axial direction by the axial movement of the carrier 27 and the swing holder 25.

  The loading disk 24 is formed in a substantially cylindrical shape, with one end 24 a in the axial direction of the cylinder covering the outer peripheral surface on the outer side in the axial direction of the sun roller element 35, and the other end 24 b in the axial direction of the cylinder. It arrange | positions covering the diameter part 11a. In addition, an annular flange portion 24c that protrudes radially inward is formed at the axial center of the cylinder. One end surface in the axial direction of the flange portion 24 c faces the outer end surface 45 of the sun roller element 35.

<Details of each part of friction roller reducer>
Next, the structure of each part of the friction roller type reduction gear 100 is demonstrated sequentially.
As shown in FIG. 2, the sun roller 15 includes a pair of sun roller elements 35 and 37 arranged in parallel in a direction along the center line Ax of the input shaft 11 (hereinafter also referred to as an axial direction). The sun roller elements 35 and 37 are arranged concentrically with the input shaft 11 in a state where a gap is provided between the opposed side end faces 41 and 43 facing each other in the axial direction.

  The rolling contact surfaces 35a and 37a of the sun roller elements 35 and 37 extend from the opposing side end surfaces 41 and 43 of the sun roller elements to the outer end surfaces 45 and 47 on the opposite side in the axial direction to the center line Ax of the input shaft 11. The inclined surface has a long radial distance. Similarly, the rolling contact surface 19a of the intermediate roller 19 with the sun roller elements 35 and 37 has a curved surface shape in which the radial distance increases from the axial center to the axial end.

3 is a cross-sectional view taken along line AA shown in FIG.
The sun roller element 35 has a spline groove on the inner peripheral surface 35 b outside in the axial direction, and the input shaft 11 has a spline groove on the outer peripheral surface 51 facing the inner peripheral surface 35 b of the sun roller element 35. The sun roller element 35 is a movable sun roller element that is fixed in the rotational direction by the engagement of these spline grooves and supported by the input shaft 11 in a state in which it can move in the axial direction. On the other hand, the sun roller element 37 is rotated in the rotational direction by the engagement of the spline groove of the inner peripheral surface 37b on the outer side in the axial direction and the spline groove of the outer peripheral surface 53 of the input shaft 11 facing the inner peripheral surface 37b of the sun roller element 37. This is a fixed sun roller element supported by the input shaft 11 in a fixed state.

  A retaining ring 48 is fixed to the outer periphery of the input shaft 11 outside the sun roller element 37 in the axial direction. The cotter 52 is fixed to the input shaft 11 in contact with the outer end surface 47 of the sun roller element 37. The cotter 52 is held by a cotter cover 54 on the radially outer side. The retaining ring 48 restricts the cotter cover 54 in the axial direction. Therefore, the axial movement of the sun roller element 37 is restricted by the cotter 52 and the retaining ring 48.

  The loading disk 24 has a spline groove on the inner peripheral surface 26 of the axial one end 24a, and the sun roller element 35 has a spline groove formed on the outer peripheral surface on the outer side in the axial direction. The loading disk 24 is fixed in the rotational direction by the engagement of these spline grooves, and can be moved relative to the sun roller element 35 in the axial direction.

  The loading disk 24 also has a spline groove on the inner peripheral surface of the other axial end portion 24b, and engages with a spline groove formed in the proximal-end large-diameter portion 11a of the input shaft 11.

  With the above configuration, the rotational torque from the input shaft 11 is transmitted to the sun roller elements 35 and 37 through the spline grooves. Further, the inner peripheral surface on the inner side in the axial direction of the sun roller elements 35 and 37 has a wax portion where a concave portion and a convex portion (not shown) are engaged. The spline groove and the wax portion cooperate to ensure a highly accurate coaxial relationship between the sun roller elements 35 and 37 and the input shaft 11.

  In this configuration, the rotational torque from the input shaft 11 flows divided into two sun roller elements 35 and 37 and is transmitted to one ring roller 17 through three intermediate rollers 19. That is, there are two power transmission paths from the input shaft 11 to the intermediate roller 19. The first path is transmitted from the input shaft 11 to the loading disk 24 via the spline groove, transmitted from the loading disk 24 to the sun roller element 35 via the spline groove, and from the rolling contact surface 35a of the sun roller element 35 to the intermediate roller 19. It is a route transmitted to. The second path is a path that is transmitted from the input shaft 11 to the sun roller element 37 via the spline groove and is transmitted from the rolling contact surface 37 a of the sun roller element 37 to the intermediate roller 19.

  In the friction roller type speed reducer 100, one element is fixed in the axial direction and three elements are axially fixed among the four elements of the sun roller 15, the ring roller 17, the intermediate roller 19, and the loading disk 24 that directly bear power transmission. It is preferable that it is movably installed. When two or more elements are constrained in the axial direction, the axial force generated in the main oil chamber 89 (FIG. 4) is constrained by any one of the support members of the four elements, so that the traction surface of the ring roller 17 Normal force is not sufficiently applied to That is, in the traction surface, the axial force is converted into a normal force with respect to the traction surface, and the axial force generated in the main oil chamber 89 acts as a normal force on the traction surface of the ring roller 17. It is.

  In the friction roller type speed reducer 100 of this configuration, the ring roller 17 is fixed in the axial direction, the intermediate roller 19 is movable in the axial direction, one sun roller element 35 of the sun roller 15 is movable in the axial direction, and the other sun roller element 37 is The loading disc 24 is fixed in the axial direction and is movably installed in the axial direction. That is, the two elements of the ring roller 17 and the sun roller element 37 are fixed in the axial direction. However, the ring roller 17 is formed such that the traction surfaces of the ring roller 17 and the intermediate roller 19 can move in the axial direction of two parts. Therefore, from the viewpoint of restraint in the axial direction, the ring roller 17 can be regarded as movable in the axial direction. Therefore, in this configuration, the axial force is not restricted except for the sun roller element 37.

  As shown in FIG. 4, the sun roller element 37 is formed with an inner cylindrical portion 55 that protrudes in the axial direction from the outer peripheral portion of the opposed side end face 43 toward the sun roller element 35. The outer peripheral surface 57 on the opposite end surface 41 side of the sun roller element 35 is fitted inside. The inner peripheral surface 55a of the inner cylindrical portion 55 and the outer peripheral surface 57 of the sun roller element 35 are each formed of a smooth cylindrical surface, and can be smoothly moved relative to the axial method.

  An annular gap defined between the outer end surface 45 of the sun roller element 35 and the flange portion 24c of the loading disk 24 has a main oil chamber 89 that generates an axial force that causes the sun roller element 35 to approach the sun roller element 37. Become. Further, an annular gap between the opposed side end surface 41 of the sun roller element 35 and the opposed side end surface 43 of the sun roller element 37 serves as a canceller oil chamber 91.

  As shown in FIG. 1, the input shaft 11 is provided with a first oil passage 93 that communicates with the main oil chamber 89 and a second oil passage 95 that communicates with the canceller oil chamber 91. The first oil passage 93 is formed on the base end side which is the housing 20 side (left side in FIG. 1) of the input shaft 11, and the first oil pressure supply portion 97 is connected to the first oil passage 93. The second oil passage 95 is formed on the distal end side (right side in FIG. 1) of the input shaft 11, and the second oil passage 95 is formed with an output shaft oil passage 94 (FIG. 2) formed in the shaft center of the output shaft 13. Connected. A second hydraulic pressure supply unit 99 is connected to the output shaft oil passage 94. The first oil passage 93 is connected to the main oil chamber 89 via a branch oil passage 93 a extending in the radial direction from the oil passage along the input shaft 11. The second oil passage 95 is connected to the canceller oil chamber 91 via a branch oil passage 95 a extending in the radial direction from the oil passage along the input shaft 11.

  The second oil passage 95 is provided at the tip of the output shaft 13, and is also connected to a branch oil passage 113 (FIG. 2) that supplies traction oil to a needle bearing 111 (FIG. 2) that supports the tip of the input shaft 11. . That is, the second oil passage 95 is formed in common with an oil passage for supplying lubricating oil, and simplifies the oil passage structure.

  The first hydraulic pressure supply unit 97 and the second hydraulic pressure supply unit 99 are each configured by a hydraulic pump or the like. The hydraulic pump may be an electric type, or may be a mechanical type in which the pump shaft and any rotating shaft of the drive unit are mechanically coupled to the friction roller type speed reducer 100 of this configuration. The first hydraulic pressure supply unit 97 adjusts the hydraulic pressure of the main oil chamber 89 by supplying traction oil to the main oil chamber 89 through the first oil passage 93. The second hydraulic pressure supply unit 99 adjusts the hydraulic pressure of the canceller oil chamber 91 through the second oil passage 95.

  The main oil chamber 89 and the canceller oil chamber 91 are separated from the outside by a seal member 61 such as an oil seal. Therefore, the traction oil does not leak when the oil pressure is applied to the main oil chamber 89. Similarly, the traction oil does not leak from the canceller oil chamber 91.

FIG. 5 is a partially enlarged sectional view of the main oil chamber 89 and the canceller oil chamber 91.
Centrifugal hydraulic pressure CF depending on the rotational speed of the input shaft 11 is generated in the traction oil filled in the main oil chamber 89. The centrifugal hydraulic pressure CF increases toward the outer side in the radial direction. The centrifugal hydraulic pressure CF generated in the main oil chamber 89 imparts an axial force that is more than necessary to the sun roller element 35, and causes a reduction in power transmission efficiency.

  In the planetary roller type speed reducer of this configuration, similarly to the main oil chamber 89, a canceller oil chamber 91 that is filled with traction oil and generates centrifugal hydraulic pressure CF is provided. The traction oil in the canceller oil chamber 91 generates a centrifugal oil pressure by the rotation of the input shaft 11 and cancels the centrifugal oil pressure generated from the main oil chamber 89. Thereby, although not perfect, the centrifugal oil pressure of the main oil chamber 89 is brought to a state close to zero (cancelled). The main oil chamber 89 and the canceller oil chamber 91 are annular spaces defined outside the input shaft 11 in the radial direction. Since the main oil chamber 89 and the canceller oil chamber 91 are spaces that are continuous in the circumferential direction, the axial force can be generated in a well-balanced manner, and a larger axial force can be obtained than when distributed in the circumferential direction.

  Oil pressure is applied to the main oil chamber 89 through the first oil passage 93 from the first oil pressure supply unit 97 shown in FIG. The canceller oil chamber 91 is given hydraulic pressure through the second oil passage 95 from the second hydraulic pressure supply unit 99. In the first oil passage 93, hydraulic pressure is applied to the main oil chamber 89 through the branch oil passage 93a. The second oil passage 95 communicates with the canceller oil chamber 91 through the branch oil passage 95a.

  The axial force applied to the sun roller elements 35 and 37 causes the oil pressure in the main oil chamber 89 to be greater than the oil pressure in the canceller oil chamber 91, thereby causing a difference between the oil pressure in the main oil chamber 89 and the oil pressure in the canceller oil chamber 91. Is granted. That is, an axial force is applied to the sun roller element 35 from the main oil chamber 89 to the outer end face 45. Further, the centrifugal hydraulic pressure generated in the canceller oil chamber 91 applies an axial force to the opposing end surface 41 of the sun roller element 35.

  The axial force acting on the sun roller element 35 due to the centrifugal oil pressure in the main oil chamber 89 and the axial force due to the centrifugal oil pressure in the canceller oil chamber 91 are opposite forces. Therefore, the centrifugal oil pressure generated in the main oil chamber 89 is canceled by the centrifugal oil pressure generated in the canceller oil chamber 91.

FIGS. 6A and 6B are explanatory views showing a state in which the axial position of the sun roller element 35 is changed by the oil pressure of the main oil chamber 89.
As shown in FIG. 6A, when the oil pressure in the main oil chamber 89 is low, the necessary minimum axial force acts on the sun roller element 35 in the direction away from the loading disk 24. Therefore, the normal force acting on the rolling contact surfaces 35a and 37a of the sun roller elements 35 and 37 and the rolling contact surface 19a of the intermediate roller 19 makes the traction oil existing between the rolling contact surfaces equal to or higher than the glass transition pressure. Minimized power.

  In other words, the oil pressure in the main oil chamber 89 in this case gives the sun roller element 35 the minimum force necessary for the surface pressure of the traction surface described later to exceed the glass transition pressure. Here, the glass transition pressure is a pressure at which the shear stress of the pressurized fluid suddenly increases. In order to transmit the power between the pair of rollers on the traction surface, the pressure of the traction oil existing between the rollers needs to be equal to or higher than the glass transition pressure. In general, the glass transition pressure is an average pressure at the contact point between the rollers, and is approximately 0.8 GPa or more.

  On the other hand, as shown in FIG. 6B, when the first oil pressure supply unit 97 (see FIG. 1) increases the oil pressure in the main oil chamber 89 through the first oil passage 93, the sun roller element 35 is pivoted from the loading disk 24 to the shaft. An axial force F that separates in the direction is generated. By this axial force F, the sun roller 15, the intermediate roller 19, and the ring roller 17 (see FIG. 1) are elastically deformed, and the sun roller element 35 moves in the axial direction.

  That is, in this state, the contact surface of the rolling contact surface 19a made of an inclined surface and the rolling contact surfaces 35a and 37a moves outward in the axial direction of the intermediate roller 19, that is, radially outward of the input shaft 11, The normal force on the rolling contact surfaces 19a, 35a, 37a is increased.

  In this case, the sun roller 15, the intermediate roller 19, and the ring roller 17 are elastically deformed according to the hydraulic pressure in the main oil chamber 89. Then, the two sun roller elements 35 and 37 are displaced in a direction close to each other, that is, a direction in which the main oil chamber 89 expands in order to follow the elastic deformation.

  Further, the traction oil corresponding to the volume change of the canceller oil chamber 91 is adjusted by driving the second hydraulic pressure supply unit 99 in accordance with the axial displacement of the sun roller element 35. By this adjustment, the static hydraulic pressure in the canceller oil chamber 91 is maintained constant.

  Here, since the canceller oil chamber 91 rotates together with the main oil chamber 89, centrifugal oil pressure similar to that of the main oil chamber 89 is generated in the canceller oil chamber 91.

  The axial force generated by the centrifugal hydraulic pressure generated in the canceller oil chamber 91 is transmitted to the sun roller element 35. Thus, the centrifugal hydraulic pressure acting on the canceller oil chamber 91 cancels most of the centrifugal hydraulic pressure acting on the main oil chamber 89. Therefore, the sun roller element 35 is accurately positioned in the axial direction without being affected by the centrifugal oil pressure generated in the main oil chamber 89.

  When the hydraulic pressure in the main oil chamber 89 is reduced by the first hydraulic pressure supply unit 97, the sun roller elements 35 are displaced toward the loading disk 24 toward each other as shown in FIG. The normal force of the contact surfaces 19a, 35a, 37a is reduced.

  By adjusting the hydraulic pressure of the main oil chamber 89, the normal force of each rolling contact surface 19a, 35a, 37a increases / decreases, so that the traction coefficient at each rolling contact surface 19a, 35a, 37a is further limited to the traction. It can be close to the coefficient.

  According to the friction roller type reduction gear 100 configured as described above, the hydraulic pressure supplied to the main oil chamber 89 is transmitted from a motor (not shown) that generates power, the transmission torque transmitted by the friction roller type reduction gear 100, It can be appropriately adjusted according to various operating conditions such as the rotational speed of the shaft and the temperature of the traction oil. For this reason, the traction coefficient of each roller can be brought close to the limit traction coefficient dynamically. As a result, it is difficult for excessive normal force to be generated in each roller, and power transmission efficiency and durability can be improved.

  In the friction roller type speed reducer 100 having the above-described configuration, the pair of sun roller elements 35 and 37 approach each other in the axial direction when the pressure of the traction oil is supplied from the first hydraulic pressure supply unit 97 to the main oil chamber 89. An axial force in the direction is generated. The centrifugal oil pressure generated in the main oil chamber 89 is canceled by the axial force from the canceller oil chamber 91. In other words, by generating the axial force that causes the sun roller elements 35 and 37 to approach each other while canceling the influence of the centrifugal oil pressure generated in the main oil chamber 89, an appropriate normal force can be generated in the sun roller elements 35 and 37. it can. Furthermore, the loading cam mechanism which has been conventionally used as shown in FIGS. 10A and 10B and FIG. 11 can be eliminated.

  According to the friction roller type speed reducer 100 of this configuration, the loading cam mechanism is not used, and the gap between the sun roller elements 35 and 37 is used as the canceller oil chamber 91 without being affected by the centrifugal hydraulic pressure. An axial force is generated. As a result, the friction roller type speed reducer 100 can be configured to have high power transmission efficiency, and the axial size can be shortened compared to the conventional configuration, resulting in a more compact and lightweight configuration.

<Configuration and operation of reduction gear unit>
Next, the sun roller element 35 having the above configuration is driven by the axial force from the main oil chamber 89, and the normal force in the normal direction of the traction surface is proportional to the transmission torque without being affected by the centrifugal hydraulic pressure. The configuration and operation of the reduction gear unit to be increased or decreased will be described.

  In general, in a traction drive such as the friction roller type speed reducer 100 of this configuration, it is necessary to avoid the occurrence of gloss slip on the traction surface because the power transmission surface is damaged. The magnitude of torque that can be transmitted to the traction oil used in the traction drive is determined depending on the temperature of the power transmission point, the transmission torque, and the like.

  Here, the maximum torque that can be transmitted is expressed by the following equation (1) when considered as a tangential force that does not depend on the radial distance to the torque application point.

Ftmax: Maximum tangential force that can be transmitted Fc: Normal force μmax: Limit traction coefficient

FIG. 7 is an explanatory diagram showing the relationship between normal force and tangential force acting on the driving roller and the driven roller.
The normal force Fa applied from the driving roller 71 to the driven roller 73 generates a normal force Fc from the driven roller 73 as the reaction force. The tangential force Ft of the traction surface according to the normal force Fc is obtained as a product of the traction coefficient μ and the normal force Fc. Therefore, when each roller is driven and controlled, the normal force Fc is adjusted so that the traction coefficient μ during operation does not exceed the limit traction coefficient μmax with respect to the torque (tangential force Ft) to be transmitted. However, as described above, the limit traction coefficient μmax varies depending on operating conditions such as the temperature of the power transmission point and the transmission torque.

  FIG. 8 is a graph showing a characteristic curve of the traction coefficient with respect to the temperature of the traction oil. As indicated by the solid line in the figure, the limit traction coefficient increases or decreases according to the temperature of the traction oil. In a mechanical loading device such as a conventional loading cam mechanism, the traction coefficient is always a constant value. Therefore, even if the temperature of the traction oil changes, the design traction coefficient is set so as not to exceed the limit traction coefficient. (See dashed line). However, depending on the temperature of the traction oil, there is a region where the difference Δμ between the design traction coefficient and the limit traction coefficient is particularly large. When the difference Δμ is large, the normal force Fc is excessively generated, leading to a decrease in power transmission efficiency and a decrease in durability life.

  Therefore, the friction roller type speed reducer 100 of this configuration generates an axial force from the main oil chamber 89 to the sun roller element 35 in accordance with fluctuations in operating conditions, thereby enabling the normal force Fc to be increased or decreased. Therefore, as shown by the one-dot chain line, the traction coefficient after adjustment (after correction) can always be set close to the limit traction coefficient μmax, which can contribute to improvement of power transmission efficiency and improvement of durability life.

  More specifically, the friction roller type speed reducer 100 of the present configuration provides a minimum necessary pressing force at a normal temperature (for example, in the range of 0 ° C. to 100 ° C.) to obtain a constant traction coefficient μc, and at a high temperature ( For example, at a temperature exceeding 100 ° C. and at a low temperature (for example, a temperature below 0 ° C.), an axial force is generated from the main oil chamber 89 to the sun roller element 35 to reduce the traction coefficient (the reduced traction coefficient is μ1). , Μ2), and suppresses the occurrence of gross slip, and at the same time, improves the efficiency particularly in the normal temperature region. Each temperature at the normal temperature limit (high temperature, low temperature) may be determined in advance according to the type of oil, operating conditions, and apparatus configuration.

  The friction roller type speed reducer 100 of this configuration generates an axial force from the main oil chamber 89 to the sun roller element 35 in accordance with fluctuations in operating conditions, thereby enabling the normal force Fc to be increased or decreased. Therefore, the traction coefficient μ can always be set close to the limit traction coefficient μmax, which can contribute to improvement of power transmission efficiency and durability.

Next, the configuration and operation of a specific speed reducer unit that controls the oil pressure in the main oil chamber 89 will be described.
FIG. 9 is a schematic block diagram of the reduction gear unit.
The reduction gear unit 200 includes a friction roller type reduction gear 100 including the first hydraulic pressure supply unit 97 and the second hydraulic pressure supply unit 99, an oil temperature sensor 75 that detects the temperature of the traction oil, a controller 79, and a storage unit. 81.

  The first hydraulic pressure supply unit 97 and the second hydraulic pressure supply unit 99 supply traction oil to the first oil path 93 and the second oil path 95 formed in the input shaft 11 shown in FIG. 1 based on a command from the controller 79. Supply. As a result, the hydraulic pressure in the main oil chamber 89 is increased or decreased, and the centrifugal hydraulic pressure generated in the main oil chamber 89 is canceled by the centrifugal hydraulic pressure generated in the canceller oil chamber 91.

  Although not shown, the oil temperature sensor 75 is disposed in the vicinity of the sun roller 15 shown in FIG. 1 and detects the temperature of the traction oil in the vicinity of the traction surface. The oil temperature sensor 75 is preferably disposed on the outer surface close to the rolling contact surfaces 35a, 37a of the sun roller elements 35, 37. Further, the oil temperature sensor 75 may be disposed on the intermediate roller 19 side.

  An output signal from the oil temperature sensor 75 is input to the controller 79. The controller 79 also transmits a transmission torque of a signal (for example, a rotational speed signal, a driving signal indicating a motor driving current or a motor driving voltage) indicating a driving state of a motor (not shown) connected to the friction roller type reduction gear 100. Information may be entered. The oil temperature sensor 75 and information output means for outputting various types of transmission torque information function as an operating condition detection unit that detects the operating conditions of the friction roller type speed reducer 100.

  The surface pressure of the traction surface can be estimated from an appropriate oil pressure measuring means for measuring the oil pressure of the traction oil, and the estimated surface pressure of the traction surface can be handled as one of the above operating conditions. .

  The storage unit 81 connected to the controller 79 stores a drive table in which the hydraulic pressure setting value of the main oil chamber 89 corresponding to the detected operating condition is registered. The controller 79 refers to the drive table of the storage unit 81 based on the input operating conditions, and obtains a hydraulic pressure set value that provides a traction coefficient close to the limit traction coefficient. The controller 79 outputs a drive signal for driving the sun roller element 35 in the axial direction to the first hydraulic pressure supply unit 97 so that the hydraulic pressure of the main oil chamber 89 becomes the determined hydraulic pressure set value.

  The first hydraulic pressure supply unit 97 drives a hydraulic motor (not shown) based on a drive signal from the controller 79 to supply traction oil to the main oil chamber 89. As a result, the hydraulic pressure in the main oil chamber 89 is adjusted to a desired pressure, and the normal force Fc on the traction surface is not excessive and is set in a range that does not exceed the limit traction coefficient. As described above, the first hydraulic pressure supply unit 97 and the controller 79 function as a pressure control unit that increases or decreases the hydraulic pressure in the main oil chamber 89. Further, the centrifugal oil pressure generated in the main oil chamber 89 is canceled by the centrifugal oil pressure generated in the canceller oil chamber 91.

  According to the speed reducer unit 200 of this configuration, the hydraulic pressure of the main oil chamber 89 is set so as not to exceed the limit traction coefficient and to be as close as possible to the limit traction coefficient according to the operating condition that varies with time. Is adjusted. The oil pressure in the main oil chamber 89 is not affected by the centrifugal oil pressure. Thereby, the power transmission efficiency of a friction roller type reduction gear can be improved, and size reduction and weight reduction can be achieved.

The present invention is not limited to the above-described embodiments, and the configurations of the embodiments may be combined with each other, or may be modified or applied by those skilled in the art based on the description of the specification and well-known techniques. The invention is intended and is within the scope of seeking protection.
For example, the power transmission means between the sun roller and the input shaft can transmit power while securing the coaxial of the input shaft and the sun roller, such as a key and a key groove, in addition to the square spline, ball spline, and involute spline. Any means can be applied as long as the relative movement in the axial direction is not hindered.

As described above, the following items are disclosed in this specification.
(1) A sun roller disposed concentrically with the input shaft, a ring roller disposed concentrically with the sun roller on the outer peripheral side of the sun roller and coupled to the output shaft, an outer peripheral surface of the sun roller, and an inner periphery of the ring roller A plurality of intermediate rollers in rolling contact with a surface, and a friction roller type speed reducer comprising:
The sun roller has a pair of sun roller elements arranged in parallel in the axial direction of the input shaft,
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller have a longer radial distance from the opposite end surface of the sun roller elements toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. An inclined surface,
One of the sun roller elements is a movable sun roller element that is axially movable with respect to the input shaft and is supported so as not to rotate.
The other sun roller element is a fixed sun roller element that is supported so as not to move and rotate in the axial direction with respect to the input shaft,
The movable sun roller element is disposed to face the axially outer end surface opposite to the fixed sun roller element side, transmits the rotation of the input shaft to the movable sun roller element, and the outer peripheral surface of the movable sun roller element and the input shaft Has a slidable loading disc on the outer peripheral surface of
An axial direction in which the movable sun roller element is brought closer to the fixed sun roller element by supplying traction oil between an axially outer end face of the movable sun roller element and one end face of the loading disk facing the axial outer end face. A main oil chamber that generates force is formed,
A canceller oil chamber is formed between the movable sun roller element and the fixed sun roller element, and traction oil is supplied to generate an axial force that reduces centrifugal hydraulic pressure generated in the main oil chamber by rotation of the input shaft. Friction roller type reducer.
According to this friction roller type speed reducer, when the axial force to the movable sun roller element is increased or decreased by increasing or decreasing the oil pressure of the main oil chamber, the main oil chamber is caused by the centrifugal oil pressure generated in the canceller oil chamber between the pair of sun roller elements. Is reduced. As a result, the normal force acting on the rolling contact surfaces of the sun roller element, intermediate roller, and ring roller can be changed without being affected by centrifugal hydraulic pressure, and the traction coefficient during operation can be brought close to the limit traction coefficient accurately. it can.

(2) The friction roller type speed reducer according to (1), wherein the main oil chamber and the canceller oil chamber are annular spaces defined radially outside the input shaft.
According to this friction roller type speed reducer, the main oil chamber and the canceller oil chamber are spaces that are continuous in the circumferential direction, so that axial force can be generated in a well-balanced manner, compared to a case where they are distributed in the circumferential direction. Large axial force is obtained.

(3) The input shaft is provided with a first oil passage communicating with the main oil chamber and a second oil passage communicating with the canceller oil chamber, respectively, according to (1) or (2). Friction roller speed reducer.
According to this friction roller type speed reducer, oil pressure is applied to the main oil chamber and the canceller oil chamber through the input shaft, so that the oil passage for supplying the oil pressure does not become complicated. Further, since the first oil passage and the second oil passage are provided separately, the oil pressure of the canceller oil chamber can be adjusted regardless of the oil pressure of the first oil passage.

(4) One of the pair of sun roller elements is formed such that a cylindrical outer diameter side cylindrical portion protrudes in an axial direction from the outer peripheral portion of the opposed side end surface toward the other sun roller element,
The canceller oil chamber is defined by any one of (1) to (3) defined by an inner peripheral surface of the outer diameter side cylindrical portion and an outer peripheral surface of the other sun roller element. Friction roller speed reducer.
According to this friction roller type speed reducer, since the canceller oil chamber is defined between the sun roller elements, the space efficiency can be increased and the axial length can be shortened.

(5) The friction roller type speed reducer according to any one of (1) to (4),
A hydraulic pressure supply unit that individually supplies traction oil to each of the main oil chamber and the canceller oil chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure control unit for increasing or decreasing the oil pressure of the main oil chamber according to the detected operating condition;
Reducer unit with.
According to this reduction gear unit, the influence of centrifugal hydraulic pressure on the axial movement of the roller can be prevented, and even if the limit traction coefficient changes depending on the operating conditions, the traction coefficient during operation is added to this limit traction coefficient. You can get closer. Thereby, both power transmission efficiency and durable life can be improved.

(6) The reduction gear unit according to (5), wherein the operation condition includes any one of a temperature of traction oil on the rolling contact surface and a transmission torque passing through the friction roller reduction gear.
According to this reduction gear unit, it can always be adjusted to an appropriate traction coefficient in accordance with the temperature of the traction oil and the fluctuation of the transmission torque.

DESCRIPTION OF SYMBOLS 11 Input shaft 13 Output shaft 15 Sun roller 17 Ring roller 19 Intermediate roller 19a Rolling contact surface 24 Loading disk 35 Sun roller element (movable sun roller element)
35a Rolling contact surface 37 Sun roller element (fixed sun roller element)
37a Rolling contact surface 41, 43 Opposite side end surface 55 Inner cylindrical portion 55a Inner circumferential surface 75 Oil temperature sensor 89 Main oil chamber 91 Canceller oil chamber 93 First oil passage 95 Second oil passage 97 First hydraulic pressure supply portion 99 Second hydraulic pressure Supply unit 100 Friction roller type reduction gear 200 Reduction gear unit

Claims (6)

Rolls to a sun roller arranged concentrically with the input shaft, a ring roller arranged concentrically with the sun roller on the outer peripheral side of the sun roller and connected to the output shaft, an outer peripheral surface of the sun roller, and an inner peripheral surface of the ring roller A friction roller type speed reducer comprising a plurality of intermediate rollers in contact with each other,
The sun roller has a pair of sun roller elements arranged in parallel in the axial direction of the input shaft,
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller have a longer radial distance from the opposite end surface of the sun roller elements toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. An inclined surface,
One of the sun roller elements is a movable sun roller element that is axially movable with respect to the input shaft and is supported so as not to rotate.
The other sun roller element is a fixed sun roller element that is supported so as not to move and rotate in the axial direction with respect to the input shaft,
The movable sun roller element is disposed to face the axially outer end surface opposite to the fixed sun roller element side, transmits the rotation of the input shaft to the movable sun roller element, and the outer peripheral surface of the movable sun roller element and the input shaft Has a slidable loading disc on the outer peripheral surface of
An axial direction in which the movable sun roller element is brought closer to the fixed sun roller element by supplying traction oil between an axially outer end face of the movable sun roller element and one end face of the loading disk facing the axial outer end face. A main oil chamber that generates force is formed,
A canceller oil chamber is formed between the movable sun roller element and the fixed sun roller element, and traction oil is supplied to generate an axial force that reduces centrifugal hydraulic pressure generated in the main oil chamber by rotation of the input shaft. Friction roller type reducer.   2. The friction roller type speed reducer according to claim 1, wherein the main oil chamber and the canceller oil chamber are annular spaces defined radially outside the input shaft.   The friction roller type according to claim 1 or 2, wherein the input shaft is provided with a first oil passage communicating with the main oil chamber and a second oil passage communicating with the canceller oil chamber. Decelerator. One of the pair of sun roller elements is formed such that a cylindrical outer diameter side cylindrical portion protrudes in the axial direction from the outer peripheral portion of the opposed side end surface toward the other sun roller element,
The said canceller oil chamber is an inner peripheral surface of the said outer diameter side cylindrical part, and the outer peripheral surface of the other said sun roller element was internally fitted, and was defined. Friction roller speed reducer. A friction roller type speed reducer according to any one of claims 1 to 4,
A hydraulic pressure supply unit that individually supplies traction oil to each of the main oil chamber and the canceller oil chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure control unit for increasing or decreasing the oil pressure of the main oil chamber according to the detected operating condition;
Reducer unit with. The speed reducer unit according to claim 5, wherein the operating condition includes any one of a temperature of traction oil on the rolling contact surface and a transmission torque passing through the friction roller type speed reducer.

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