JP2018119620A - 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 which can obtain high power transmission efficiency, and is reducible in a size by shortening an axial length of the reduction gear itself, and a reduction gear unit using the same.SOLUTION: In a friction roller type reduction gear 100, a sun roller 15 has a pair of sun roller elements 35, 37 which are arranged in parallel with an input shaft 11 in an axial direction. Rolling contact faces 37a, 37a of the sun roller elements 35, 37 and rolling contact faces 19a, 19b of an intermediate roller 19 are inclined faces whose radial distances up to a center line Ax of the input shaft 11 become short toward outside end faces 45, 47 at a side opposite to the axial direction from opposing-side end faces 41, 43 in which the sun roller elements oppose each other. A pressure chamber 63 for generating an axial force for separating the sun roller elements from each other in the axial direction by charged traction oil is formed between the opposing-side end faces 41, 43 of the sun roller elements 35, 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 (Patent Documents 1 and 2). As shown in FIGS. 8A and 8B 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. 9, the loading cam mechanism 309A is disposed facing the sun roller element 314 on which the cam shaft 317 is formed. A configuration in which the loading cam mechanism 309B is disposed so as to face 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 elements 313 and 314, there are many torque-sensitive mechanisms such as the loading cam mechanism shown in FIGS. 8A and 8B and FIG. 9, and a fixed pressing mechanism using a spring. Adopted. 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, a loading device including not only a mechanical type but also a hydraulic type is generally configured to be disposed outside in the axial direction between two sun roller elements. Therefore, the axial length of the friction roller type reduction gear is inevitably increased, and there is room for improvement in reducing the size and weight.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a friction roller type speed reducer that can achieve high power transmission efficiency, and that can reduce the axial length of the speed reducer itself, thereby reducing the size and weight, 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 juxtaposed in the axial direction of the input shaft, and the sun roller element is movable in the axial direction of the input shaft and fixed in the rotational direction. Each supported by
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller are a radial distance from the opposite end surface where the sun roller elements face each other toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. Is an inclined surface that becomes shorter,
Friction roller type in which a pressure chamber is formed between the opposing end surfaces of the sun roller elements and generates an axial force that separates the sun roller elements in the axial direction by the pressure of the traction oil filled. Decelerator.
(2) The friction roller type speed reducer according to (1),
A hydraulic pressure supply section for supplying traction oil to the pressure chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure controller that increases or decreases the hydraulic pressure in the pressure chamber according to the detected operating condition;
Reducer unit with.

  According to the present invention, high power transmission efficiency can be obtained, and the axial length of the speed reducer itself can be shortened to reduce the size and weight.

It is a partial cross section perspective view of the friction roller type reduction gear of this invention. It is a principal part expanded sectional view of a friction roller type reduction gear. It is the sectional view on the AA line of the sun roller element of FIG. (A), (B) is explanatory drawing which shows a mode that the axial direction position of a sun roller element is changed with the hydraulic pressure in a pressure 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 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 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 sectional view of a main part of the friction roller type speed reducer. As shown in FIGS. 1 and 2, the friction roller type speed reducer 100 includes an input shaft 11 connected to a motor (not shown) that generates power and an output shaft 13 that are concentrically arranged. The input rotational power is transmitted to the output shaft 13 while being decelerated. The friction roller type speed reducer 100 includes a sun roller 15 that is arranged coaxially with the input shaft 11, a ring roller 17, and a plurality of intermediate rollers 19. 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 and the inner peripheral surface of the ring roller, 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. Although the detailed description is omitted, the swing holder 25 is supported by the carrier 27 with the support shaft 22 parallel to the input shaft 11. The carrier 27 supports the plurality of swing holders 25 that support the intermediate roller 19 having the above-described configuration along the circumferential direction. That is, the ring roller 17 and the plurality of intermediate rollers 19 are supported so as not to move in the axial direction.

  The input shaft 11 is formed with an oil passage 31 along which the traction oil is supplied. A hydraulic pressure supply unit 33 is connected to one end side of the input shaft 11 on the housing 20 side. The hydraulic pressure supply unit 33 supplies traction oil into the oil passage 31. Further, the oil passage 31 is closed by a plug 34 on the other end side of the input shaft 11 on the output shaft 13 side.

  The ring roller 17 is supported so as not to move relative to the ring roller holder 21 in the axial direction (a slight gap is allowed, and no adjustment means or member for the axial dimension is required to make the relative movement impossible). Similarly, the intermediate roller 19 is also supported by the swinging holder 25 so as not to move relative to the axial direction (a slight gap is allowed and no adjustment means or member for the axial dimension is required to prevent relative movement). . On the other hand, since the rolling contact surface 17a of the ring roller has a cylindrical surface shape parallel to the axial direction, the mutual axial positions of the ring roller 17 and the intermediate roller 19 are not restricted and have a degree of freedom. Therefore, there is no need for adjusting means for adjusting the relative axial positions of the ring roller 17 and the intermediate roller 19.

<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 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 opposite end surfaces 41 and 43 where the sun roller elements face each other toward the outer end surface 45.47 on the opposite side in the axial direction to the center line Ax of the input shaft 11. The slant surface has a short radial distance. Further, the rolling contact surface of the intermediate roller 19 with the sun roller elements 35 and 37 has the same shape.

  A first rolling contact surface 19a, a second rolling contact surface 19b, and a third rolling contact surface 19c are formed on the outer peripheral surface of the intermediate roller 19. The first rolling contact surface 19 a is in rolling contact with the rolling contact surface 35 a of one sun roller element 35, and the second rolling contact surface 19 b is in rolling contact with the rolling contact surface 37 a of the other sun roller element 37. The third rolling contact surface 19c is formed between the first rolling contact surface 19a and the second rolling contact surface 19b, and is in rolling contact with the rolling contact surface 17a (see FIG. 1) of the ring roller 17. The above-mentioned third rolling contact surface 19c and the rolling contact surface 17a of the ring roller 17 are both cylindrical surface shapes parallel to the axial direction.

  Here, FIG. 3 shows a cross-sectional view of the sun roller element 35 of FIG. 3 is the same as the cross-sectional view of the sun roller element 37 in FIG. 2 taken along the line B-B, the sun roller elements 35 and 37 will be described together here.

  The sun roller elements 35 and 37 have spline grooves on the inner peripheral surfaces 35b and 37b on the outer side in the axial direction, and the input shaft 11 has spline grooves on the outer peripheral surfaces 51 and 53 facing the inner peripheral surfaces 35b and 37b. The sun roller elements 35 and 37 are supported by the input shaft 11 while being fixed in the rotational direction by the engagement of the spline grooves. Thereby, the rotational torque from the input shaft 11 is transmitted to the sun roller elements 35 and 37 through the spline grooves. Further, the outer peripheral surfaces 52 and 54 on the inner side in the axial direction of the sun roller elements 35 and 37 have enameled portions that engage with concave portions and convex portions (not shown). 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.

  As shown in FIG. 2, the input shaft 11 has a stepped portion 49 formed on the outer side in the axial direction of the sun roller element 35. The outer side of the stepped portion 49 in the axial direction is larger in diameter than the spline groove of the outer peripheral surface 51 that supports the sun roller element 35.

  Further, the input shaft 11 is formed with an annular groove 50 that engages the retaining ring 48 on the outer side in the axial direction of the sun roller element 37. The retaining ring 48 protrudes radially outward from the spline groove on the outer peripheral surface 53 that supports the sun roller element 37. The cut-off portion 49 and the retaining ring 48 function as a retaining mechanism for the sun roller elements 35 and 37.

  The sun roller element 37 is formed with a protruding cylindrical portion 55 that protrudes in the axial direction from the outer peripheral portion of the opposing side end surface 43. An outer peripheral surface 57 on the opposite end surface 41 side of the sun roller element 35 is fitted into the inner peripheral surface 55 a of the protruding cylindrical portion 55. The inner peripheral surface 55a of the projecting 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 in the axial direction.

  The outer peripheral surface 55b of the protruding cylindrical portion 55 is a cylindrical surface having a diameter smaller than the maximum diameter portion 39 of the rolling contact surface 37a of the sun roller element 37, and is always in non-contact with the third rolling contact surface 19c of the intermediate roller 19. .

  The opposed side end surface 41 of the sun roller element 35, the opposed side end surface 43 of the sun roller element 37, the inner peripheral surface 55a of the protruding cylindrical portion 55, the opposed side end surfaces 41 and 43 of the sun roller elements 35 and 37, and the input shaft 11 An annular space surrounded by the outer peripheral surface 61 serves as a pressure chamber 63 that generates an axial force that separates the sun roller elements 35 and 37 in the axial direction.

  A disc spring 65 as an elastic member is disposed inside the pressure chamber 63. The disc spring 65 biases the sun roller elements 35 and 37 in the direction in which they are separated from each other in the axial direction. The disc spring 65 applies to the sun roller elements 35 and 37 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.

  The input shaft 11 is formed with a branch oil passage 67 that communicates between the pressure chamber 63 and the oil passage 31 of the input shaft 11.

  The pressure chamber 63 is filled with traction oil supplied from the hydraulic pressure supply unit 33 shown in FIG. 1 through the branch oil passage 67 so that the hydraulic pressure in the pressure chamber 63 can be increased or decreased. The pressure chamber 63 is partitioned from the outside of the pressure chamber by a seal member 69 such as an oil seal, so that leakage of traction oil is prevented when pressure is applied.

FIGS. 4A and 4B are explanatory views showing a state in which the axial positions of the sun roller elements 35 and 37 are changed by the hydraulic pressure in the pressure chamber 63.
As shown in FIG. 4A, when the pressure of the traction oil filled in the pressure chamber 63 is low, an axial force mainly due to the elastic force of the disc spring 65 acts on the sun roller elements 35 and 37. . Therefore, normal forces acting on the rolling contact surfaces 35a, 37a of the sun roller elements 35, 37 and the first rolling contact surface 19a and the second rolling contact surface 19b of the intermediate roller 19 exist between the rolling contact surfaces. The minimum pressure is set so that the traction oil is not less than the glass transition pressure.

  On the other hand, as shown in FIG. 4B, when the oil pressure supply unit 33 (see FIG. 1) increases the oil pressure in the pressure chamber 63 through the oil passage 31 and the branch oil passage 67, the sun roller elements 35 and 37 are pivoted. An axial force F that separates in the direction is generated. The sun roller 15, the intermediate roller 19, and the ring roller 17 are elastically deformed by the axial force F, and the sun roller elements 35 and 37 are moved away from each other.

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

  That is, according to the magnitude of the oil pressure, the sun roller 15, the intermediate roller 19, and the ring roller 17 are elastically deformed, and the two sun roller elements 35 and 37 are separated from each other in order to follow the elastic deformation. That is, the pressure chamber 63 is displaced in the expanding direction.

  Further, when the hydraulic pressure in the pressure chamber 63 is reduced by the hydraulic pressure supply unit 33, the sun roller elements 35 and 37 are displaced in the axial direction again as shown in FIG. 4A, and the rolling contact surfaces 19a, 19a, The normal force of 19b, 35a, 37a decreases.

  By adjusting the hydraulic pressure in the pressure chamber 63 to increase or decrease, the normal force of each rolling contact surface 19a, 19b, 35a, 37a increases or decreases, and thereby the traction coefficient at each rolling contact surface 19a, 19b, 35a, 37a. Can be made closer to the limit traction coefficient.

  According to the friction roller type speed reducer 100 configured as described above, the hydraulic pressure supplied to the pressure chamber 63 is transmitted from a motor (not shown) that generates power, the transmission torque transmitted by the friction roller type speed reducer 100, the shaft The rotational speed of the traction oil, the temperature of the traction oil, etc. can be appropriately adjusted according to various operating conditions. 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.

  Further, the friction roller type speed reducer 100 configured as described above has shafts in a direction in which the pair of sun roller elements 35 and 37 are separated from each other in the axial direction when the pressure of the traction oil is supplied from the hydraulic pressure supply unit 33 to the pressure chamber 63. Directional force is generated. That is, by generating an axial force that separates the sun roller elements 35 and 37 from the pressure chamber 63, the loading cam mechanism used in the past shown in FIGS. 8A and 8B and FIG. 9 becomes unnecessary. .

  As shown in FIGS. 8A, 8B, and 9, the loading cam mechanism is normally disposed outside the sun roller 15 of the input shaft 11, and thus increases the axial size of the friction roller type speed reducer. However, 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 that has existed in the past is used as the pressure chamber 63. An axial force is generated. As a result, the friction roller type reduction gear 100 can be reduced in size in the axial direction than before, and can be configured to be more compact and lightweight.

<Configuration and operation of reduction gear unit>
Next, the sun roller elements 35 and 37 configured as described above are driven in the axial direction by the normal force from the pressure chamber 63, and the normal force in the normal direction of the traction surface is increased or decreased in proportion to the transmission torque. The structure and operation of the unit 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: Maximum traction coefficient

FIG. 5 is an explanatory diagram showing the relationship between the normal force and the 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. 6 is a graph showing a characteristic curve of the traction coefficient with respect to the temperature of the traction oil. As shown 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. . 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.

  In view of this, the friction roller type speed reducer 100 of this configuration generates an axial force from the pressure chamber 63 to the sun roller elements 35 and 37 in accordance with fluctuations in operating conditions, thereby enabling an increase / decrease adjustment of the normal force Fc. . 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 reduction gear unit that controls the hydraulic pressure in the pressure chamber 63 will be described.
FIG. 7 is a schematic block diagram of the reduction gear unit.
The reducer unit 200 includes the friction roller type reducer 100 including the hydraulic pressure supply unit 33 described above, an oil temperature sensor 75 that detects the temperature of the traction oil, a controller 79, and a storage unit 81.

  The hydraulic pressure supply unit 33 is connected to a hydraulic pump (not shown) and supplies traction oil to the oil passage 31 formed in the input shaft 11 shown in FIG. 1 based on a command from the controller 79. As a result, the hydraulic pressure in the pressure chamber 63 is increased or decreased. Note that the hydraulic pump may be an electric type, or may be a mechanical type in which the pump shaft and any one of the rotation shafts of the friction roller type speed reducer 100 are mechanically coupled.

  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 speed reducer 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 set values in the pressure chamber 63 (see FIG. 2) corresponding to the detected operating conditions are 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 elements 35 and 37 in the axial direction to the hydraulic pressure supply unit 33 so that the hydraulic pressure in the pressure chamber 63 becomes the determined hydraulic pressure set value.

  The hydraulic pressure supply unit 33 drives a hydraulic motor (not shown) based on a drive signal from the controller 79 to supply traction oil to the pressure chamber 63. As a result, the hydraulic pressure in the pressure chamber 63 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. The hydraulic pressure supply unit 33 and the controller 79 function as a pressure control unit that increases or decreases the hydraulic pressure in the pressure chamber 63.

  According to the speed reducer unit 200 of this configuration, the hydraulic pressure in the pressure chamber 63 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. Adjust. Thereby, the power transmission efficiency of a friction roller type reduction gear can be improved, and size reduction and weight reduction can be achieved.

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 for which protection is sought.
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.
Moreover, the elastic member arrange | positioned in a pressure chamber is applicable if it is a means which can give a pre-pressure to an axial direction other than a disc spring, such as a coil spring. In addition, since an input shaft rotates at high speed, it is preferable not to deteriorate a dynamic balance by arrangement | positioning of an elastic member. For example, in the case of a disc spring, the inner diameter portion of the disc spring may function as a guide portion for the input shaft.

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 juxtaposed in the axial direction of the input shaft, and the sun roller element is movable in the axial direction of the input shaft and fixed in the rotational direction. Each supported by
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller are a radial distance from the opposite end surface where the sun roller elements face each other toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. Is an inclined surface that becomes shorter,
Friction roller type in which a pressure chamber is formed between the opposing end surfaces of the sun roller elements and generates an axial force that separates the sun roller elements in the axial direction by the pressure of the traction oil filled. Decelerator.
According to this friction roller type speed reducer, the axial force on the pair of sun roller elements can be increased or decreased by increasing or decreasing the hydraulic pressure in the pressure chamber formed between the pair of sun roller elements. Thereby, the normal force acting on each rolling contact surface of the sun roller element, the intermediate roller, and the ring roller can be changed, and the traction coefficient during operation can be brought close to the limit traction coefficient.

(2) The friction roller type speed reducer according to (1), wherein the pressure chamber is provided with an elastic member that urges the sun roller elements in a direction in which the sun roller elements are separated in the axial direction.
According to this friction roller type speed reducer, the minimum force necessary for the surface pressure of the rolling contact surface to exceed the glass transition pressure can be applied.

(3) The intermediate roller has a first rolling contact surface that is in rolling contact with one of the pair of sun roller elements, a second rolling contact surface that is in rolling contact with the other, the first rolling contact surface, and the second rolling contact. The friction roller type speed reducer according to (1) or (2), further including a second rolling contact surface formed between the surface and the rolling contact with the ring roller.
According to this friction roller type speed reducer, the first rolling contact surface and the second rolling contact surface are in rolling contact with the sun roller, and the third rolling contact surface is in rolling contact with the rolling contact surface of the ring roller.

(4) The friction roller type speed reducer according to any one of (1) to (3), wherein the input shaft includes an oil passage that applies hydraulic pressure in the pressure chamber.
According to this friction roller type speed reducer, since the hydraulic pressure is applied to the pressure chamber through the input shaft, the oil passage for supplying the oil pressure does not become complicated.

(5) One of the sun roller elements is formed with a protruding cylindrical portion that protrudes in the axial direction from the outer peripheral portion of the opposite-side end surface,
The friction chamber according to any one of (1) to (4), wherein the pressure chamber is formed such that an inner peripheral surface of the projecting cylindrical portion is fitted in one of the other outer peripheral surfaces of the sun roller element. Type reducer.
According to this friction roller type speed reducer, since the pressure chamber is defined by the sun roller element itself, the number of parts can be reduced.

(6) The friction roller type speed reducer according to any one of (1) to (5),
A hydraulic pressure supply section for supplying traction oil to the pressure chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure controller that increases or decreases the hydraulic pressure in the pressure chamber according to the detected operating condition;
Reducer unit with.
According to this reduction gear unit, even if the limit traction coefficient changes depending on the driving conditions, the traction coefficient during driving can be brought close to the limit traction coefficient. Thereby, both power transmission efficiency and durable life can be improved.

(7) The reduction gear unit according to (6), 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 19b Rolling contact surface 19c Rolling contact surface 31 Oil path 33 Hydraulic supply part 35 Sun roller element 35a Rolling contact surface 37 Sun roller element 37a Rolling contact surface 41 Opposite side End surface 43 Opposite side end surface 55 Projecting cylindrical portion 63 Pressure chamber 75 Oil temperature sensor 100 Friction roller type reduction gear 200 Reduction gear unit

Claims (7)

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 juxtaposed in the axial direction of the input shaft, and the sun roller element is movable in the axial direction of the input shaft and fixed in the rotational direction. Each supported by
The rolling contact surface of the sun roller element and the rolling contact surface of the intermediate roller are a radial distance from the opposite end surface where the sun roller elements face each other toward the outer end surface on the opposite side in the axial direction to the center line of the input shaft. Is an inclined surface that becomes shorter,
Friction roller type in which a pressure chamber is formed between the opposing end surfaces of the sun roller elements and generates an axial force that separates the sun roller elements in the axial direction by the pressure of the traction oil filled. Decelerator.   The friction roller type speed reducer according to claim 1, wherein the pressure chamber is provided with an elastic member that urges the sun roller elements in a direction to separate the sun roller elements in the axial direction.   The intermediate roller includes a first rolling contact surface that is in rolling contact with one of the pair of sun roller elements, a second rolling contact surface that is in rolling contact with the other, and the first rolling contact surface and the second rolling contact surface. The friction roller type speed reducer according to claim 1, further comprising a second rolling contact surface that is formed in between and is in rolling contact with the ring roller.   The friction roller type speed reducer according to any one of claims 1 to 3, wherein the input shaft has an oil passage for applying a hydraulic pressure in the pressure chamber. Either one of the sun roller elements is formed with a protruding cylindrical portion that protrudes in the axial direction from the outer peripheral portion of the opposite side end surface,
5. The friction roller according to claim 1, wherein the pressure chamber is formed such that an inner peripheral surface of the protruding cylindrical portion is fitted into one of the outer peripheral surfaces of the sun roller element. Type reducer. The friction roller type speed reducer according to any one of claims 1 to 5,
A hydraulic pressure supply section for supplying traction oil to the pressure chamber;
An operating condition detector for detecting operating conditions of the friction roller type speed reducer;
A pressure controller that increases or decreases the hydraulic pressure in the pressure chamber according to the detected operating condition;
Reducer unit with.   The speed reducer unit according to claim 6, 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.

Images