JP2005147357A - Friction roller type transmission and motor-driven power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent biting into first and second rollers by separating a third roller and a fourth roller from each other without any increase in manufacturing cost. <P>SOLUTION: A holder 20 mounts the third and fourth rollers 3, 4 around a bearing 22 and also surrounds the periphery thereof. A coiled spring 32 is set on the holder 20, and presses through a washer 33 by a bolt 34 to adjust the range of applying pressing force thereto. A coiled spring 41 having lower load than the pressing force is set on two holders 20 to apply separating force smaller than the pressing force in the opposite direction to that of the pressing force. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a friction roller transmission that transmits torque while shifting with a friction roller, and an electric power steering apparatus including the friction roller transmission.

In the friction roller transmission disclosed in Patent Document 1 filed prior to the present application by the present inventor, a first roller and a second roller centered on each axis are respectively connected to two shafts spaced in parallel to each other. Arrange so that it does not touch,
The third roller and the fourth roller that are in contact with both the first and second rollers are placed between the first roller and the second roller and on the opposite side of the line connecting the centers of the first roller and the second roller. Place and
The angle formed between the tangent line of the first roller and the third roller (or the fourth roller) and the tangent line of the second roller and the third roller (or the fourth roller) is between the rollers. It is characterized in that it is set to be not more than twice the friction angle obtained from the friction coefficient.

  As a result, the transmission path of the first roller → the third roller → the second roller and the transmission path of the first roller → the fourth roller → the second roller can be configured. In the friction roller type transmission without backlash , Enabling forward / reverse rotation, and generating roller pressing force according to the transmission torque, minimizing the increase in operating torque, especially in the low transmission torque area In addition, since a roller for power transmission is provided for each rotation direction and is always in contact with the rotation direction, torque transmission can be performed without causing a delay or hitting sound even when the rotation direction is reversed. it can.

  Specifically, the first roller will be described as an input.

  When the first roller is rotated clockwise (CW direction), the tangent line between the third roller and the first roller and the tangent line between the third roller and the second roller are less than twice the friction angle. Each contact angle is equal to or less than the friction angle, and the third roller and the first roller do not slide relative to each other at the contact portion. Therefore, the third roller is in the direction of bringing the third roller close to the first roller. Thus, the counterclockwise (CCW direction) rotational force is transmitted.

  Even in the contact portion between the third roller and the second roller, the tangent line between the third roller and the first roller and the tangent line between the third roller and the second roller are less than twice the friction angle. Each contact angle is equal to or less than the friction angle, and the third roller and the second roller do not slide relative to each other at the contact portion. Therefore, a tangential force is applied to the second roller from the third roller, and a rotational force in the CW rotation direction is transmitted. As a reaction, the third roller generates a tangential force opposite to the third roller. This tangential force is a direction in which the third roller is brought close to the second roller.

Since the tangential force acting on the third roller is a direction in which the third roller is pressed against the first and second rollers, a tangential force to be transmitted, that is, a pressing force corresponding to the torque can be obtained. It should be noted that the fourth roller is omitted because the operation is the same except that the rotation direction is different.
JP 2003-28251 A

  The friction roller type transmission has a purpose of maintaining the contact state between the rollers in the non-torque transmission state in order to generate the pressing force to the first and second rollers generated by the transmission torque on the third and fourth rollers. 3. A mechanism for pressing the fourth and fourth rollers against the first and second rollers was necessary.

  However, simply applying a pressing force will cause the non-transmission side roller to bite when the transmission side roller bites in, and the two rollers that have bite in will not be separated even when the motor is reversed. However, there is a problem in that a load is applied to the bearing supporting the input / output roller, and the operating torque increases.

  Therefore, in Patent Document 1, a stopper is provided between the two holders that rotatably hold the third and fourth rollers, and the relative distance between the third and fourth rollers is regulated to prevent the rollers from biting in. It was.

  Since the two rollers bite in until the stopper surfaces provided on the two holders that are rotatably held contact each other, the loss of that amount is unavoidable.

  However, by setting the position of the stopper provided on the holder to an appropriate value, it is possible to reduce the loss due to the biting of the roller to a target value or less.

  However, the appropriate position of the stoppers provided on the two holders varies greatly depending on the distance between the centers of the input / output rollers, the dimensions of each roller, the radial rigidity of the bearings, backlash, etc. in order to set the contact angle of the rollers to a predetermined value. End up. In a holder in which the stopper position cannot be adjusted, in order to reduce the operating torque loss to a target value or less, there is a problem that the accuracy of each used part must be increased and the cost is increased.

  The present invention has been made in view of the above-described circumstances, and the third and fourth rollers are separated from each other without causing an increase in manufacturing cost, and the first and second rollers are bitten. An object of the present invention is to provide a friction roller type transmission that can be prevented.

In order to achieve the above object, a friction roller transmission according to a first aspect of the present invention includes a first roller and a second roller centered on each axis on two shafts spaced in parallel to each other. Arrange them so that they do not touch each other,
The third roller and the fourth roller that are in contact with both the first and second rollers are on the opposite side of the line connecting the first roller and the second roller and the center of the first roller and the second roller. Place and
The angle formed by the tangent line between the first roller and the third or fourth roller and the tangent line between the second roller and the third or fourth roller is a friction angle obtained from the friction coefficient between the rollers. In friction roller type transmission set to be less than double,
The holder for rotatably holding the third and fourth rollers respectively applies a pressing force toward the first and second rollers within a predetermined range of movement. To do.

  The friction roller transmission according to claim 2 of the present invention is characterized in that the range of the predetermined movement amount is adjustable.

  The friction roller transmission according to claim 3 of the present invention is characterized in that a separation force smaller than a pressing force in a direction opposite to the pressing force is applied to the holder.

  The friction roller transmission according to claim 4 of the present invention is characterized in that a frictional resistance force smaller than a pressing force is applied to the holder.

  The friction roller transmission according to claim 5 of the present invention is characterized in that a movement amount regulating means for preventing movement of the holder is provided so that the movement amount of the holder does not exceed an upper limit value.

  The friction roller type transmission according to claim 6 of the present invention is characterized in that the movement amount regulating means can be adjusted.

  An electric power steering apparatus according to a seventh aspect of the present invention includes the friction roller transmission according to any one of the first to sixth aspects.

  As described above, according to the present invention, the holders that rotatably hold the third and fourth rollers are respectively pressed toward the first and second rollers within a predetermined range of movement. As a result of the application, the tangential force acts on the transmission side roller during torque transmission, so that even if the pressing force is lost, the transmission side roller bites in. On the other hand, the non-transmission side roller is in contact with the first and second rollers within a range of a predetermined movement amount, but since the pressing force is lost outside the predetermined range, the non-transmission side roller is separated from the first and second rollers. It was made a structure that couldn't bite in.

  Further, since the range of the predetermined movement amount can be adjusted, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

  Further, by applying a separation force smaller than the pressing force in the direction opposite to the pressing force to the holder, or applying a friction resistance force smaller than the pressing force, the first outside the predetermined range due to the non-transmission side roller's own weight. The contact with the second roller was prevented and the biting of the roller was prevented.

  Further, by providing a movement amount regulating means for preventing the movement of the holder, the movement amount of the holder is prevented from exceeding the upper limit value, and the loss torque of the bearing due to overcoming the roller and excessive biting of the roller is reduced.

  Hereinafter, a friction roller transmission and an electric power steering apparatus according to embodiments of the present invention will be described with reference to the drawings.

(Basic structure)
FIG. 1A is a side view of a friction roller type transmission (reduction gear) according to the basic structure of the present invention, and FIG. 1B is a schematic view of the friction roller type transmission shown in FIG. It is a perspective view. FIG. 2A is a side view of the friction roller transmission according to the basic structure of the present invention (a diagram showing a transmission path of the first roller → the fourth roller → the second roller), and FIG. ) Is a side view of the same (showing the transmission path of the first roller → the third roller → the second roller).

In this basic structure, in the friction roller type transmission (reduction gear), as shown in FIG. 1 and FIG. Two rollers 2 are arranged so as not to contact each other,
The third roller 3 and the fourth roller 4 that are in contact with both the first and second rollers are placed between the first roller 1 and the second roller 2 and in the center of the first roller 1 and the second roller 2. Place it on the opposite side of the connecting line,
The angle formed by the tangent line between the first roller 1 and the third roller 3 (or the fourth roller 4) and the tangent line between the second roller 2 and the third roller 3 (or the fourth roller 4) is: The friction angle is determined to be not more than twice the friction angle obtained from the friction coefficient between the rollers, and the friction part is outside the roller.

In other words, if the center of each roller is P1 to P4,
The sum of the angle formed by the line P1P2 and the line P1P3 (α1: ∠P2P1P3) and the angle formed by the line P1P2 and the line P2P3 (α2: ∠P1P2P3);
The angle between the line P1P2 and the line P1P4 (α3: ∠P2P1P4) and the sum of the angle between the line P1P2 and the line P2P4 (α4: ∠P1P2P4)
The friction angle (θ = tan ⁻¹ μ) is set to be twice or less.

  When this arrangement is adopted, the friction angle is small, and thus the third and fourth rollers 3 and 4 have to be in positions that overlap in the axial direction.

  With the above configuration, a pressing force according to the transmission torque can be obtained. Therefore, there is no need for the pressing force necessary to transmit the friction (the third and fourth rollers 3 and 4 are pressed against the first and second rollers 1 and 2). However, it is better to apply a slight pressing force that ensures an initial contact state in a non-rotating state. Each roller is composed of one each, but a plurality of rollers may be used.

  The operation will be described below with the first roller as an input.

  As shown in FIGS. 1B and 2B, when the first roller 1 is rotated clockwise (CW direction), the tangent line between the third roller 3 and the first roller 1, the third roller 3, Since the tangent line of the second roller 2 is an angle that is not more than twice the friction angle, each contact angle is equal to or less than the friction angle, and the third roller 3 and the first roller 1 are relatively slipped at the contact portion. Since this does not occur, a tangential force is applied to the third roller 3 from the first roller 1. The tangential force is a direction in which the third roller 3 is brought close to the first roller 1, and the counterclockwise (CCW direction) rotational force is transmitted to the third roller 3 by the tangential force.

  Also in the contact portion between the third roller 3 and the second roller 2, the tangent line of the third roller 3 and the first roller 1 and the tangent line of the third roller 3 and the second roller 2 are less than twice the friction angle. Since the contact angle is an angle, each contact angle is equal to or less than the friction angle, and the third roller 3 and the second roller 2 do not slide relative to each other at the contact portion. Therefore, the second roller 2 receives a tangential force from the third roller 3 and transmits the rotational force in the CW rotation direction. As a reaction, the third roller 3 generates a tangential force opposite to that. This tangential force is a direction in which the third roller 3 is brought close to the second roller 2.

  Since the tangential force acting on the third roller 3 is a direction in which the third roller 3 is pressed against the first and second rollers 2, a tangential force to be transmitted, that is, a pressing force corresponding to the torque can be obtained. .

  At this time, as shown in FIG. 2 (a), the fourth roller 4 also has a tangential force from the first and second rollers 1 and 2 because relative slip does not occur at the contact portion. However, since the direction is a direction in which the fourth roller 4 is separated from the first and second rollers 1 and 2, the fourth roller 4 rolls while being in contact with the first roller 1 and the second roller 2. Just doing.

  Next, as shown in FIGS. 1B and 2A, when the first roller 1 rotates in the reverse direction in the CCW direction, the action of the fourth roller 4 and the third roller 3 is switched. However, since the fourth roller 4 is already in contact with the first roller 1 and the second roller 2, the power transmission direction can be smoothly changed when the rotation direction is reversed.

  In order to transmit torque, the third and fourth rollers 3 and 4 may be in contact with the first and second rollers 1 and 2. In order to secure the contact state, the third and fourth rollers 3 and 4 may obtain a slight pressing force on the first and second rollers 1 and 2.

  Thus, according to this basic structure, the transmission path of the first roller 1 → the third roller 3 → the second roller 2 and the transmission path of the first roller 1 → the fourth roller 4 → the second roller 2 are configured. In a backlash-less friction roller type transmission (reduction gear), forward and reverse rotation can be enabled, and a roller pressing force corresponding to the transmission torque is generated to increase the operating torque. Can be reduced as much as possible, especially in the area of low transmission torque, and because a roller for power transmission is provided for each rotation direction and is always in contact, the rotation direction is reversed. In addition, torque transmission can be performed without causing a delay or hitting sound.

(First embodiment of the present invention)
A first embodiment of the present invention in which the present invention is applied to an electric power steering device for a vehicle will be described with reference to FIGS. This embodiment corresponds to claims 1, 2, 3, 5, and 7.

  FIG. 3 is a longitudinal sectional view of the electric power steering apparatus including the friction roller transmission according to the first embodiment of the present invention.

  In FIG. 3, the 1st roller 1 is being fixed to the output rotating shaft 12 on the same axis line of the output rotating shaft of the electric motor 10 which is an electric motor unit.

  The second roller 2 is fitted and fixed to a nut-shaped ball screw nut 13 or formed integrally therewith. The ball screw nut 13 is rotatably supported with respect to the housing 7 via a bearing 15, and is provided by fitting the rack shaft 11 therein, that is, surrounding the rack shaft 11.

  The rack shaft 11 is formed with a thread groove 11 b that is indirectly engaged with the thread groove 13 a of the ball screw nut 13 via the ball 14. That is, the ball screw nut 13 and the rack shaft 11 are indirectly engaged with each other via a large number of spherical balls 14 that are rotatably fitted in the valleys of the thread groove 13a and the thread groove 11b. The ball screw nut 13 is externally fitted to a part of the axial direction of the thread groove 11b. The ball screw nut 13 and the ball 14 constitute a known so-called ball screw or ball screw.

  Thus, in this embodiment, the transmission path of the first roller 1 → the third roller 3 → the second roller 2 and the transmission path of the first roller 1 → the fourth roller 4 → the second roller 2 are configured. In a friction roller type transmission (reduction gear) with no backlash, it is possible to rotate forward and reverse, and by generating a roller pressing force according to the transmission torque, the operating torque can be increased. It can be made as small as possible, especially in the region of low transmission torque, and a roller for power transmission is provided for each rotation direction so that it is always in contact. However, torque transmission can be performed without causing a delay or hitting sound.

  In the case of this embodiment, the electric motor 10 is disposed in an axial direction substantially parallel to the rack shaft 11. The electric motor 10 may be disposed with an appropriate inclination according to the installation space. One end of the rack shaft 11 is connected to a tie rod (not shown) via a ball joint (not shown).

  In the drawing of the rack shaft 11, a rack (not shown) is formed at a side portion (tip portion) of the thread groove 11 b. The rack is externally fixed to a pinion shaft (not shown) connected to a lower end portion of a steering shaft (not shown) connected to a handle (not shown) and is built in a pinion gear box (not shown). It meshes with a pinion gear (not shown). The steering shaft and pinion shaft constitute a rotating shaft means, and the rack and pinion gear constitute rack and pinion means. The rack and pinion means itself is a well-known one for drivingly connecting the rotary shaft means and the rack shaft 11.

  The operation in the above configuration will be briefly described. The electric motor 10 is controlled on the basis of information such as torque applied to the steering wheel or vehicle speed by the driver, but a detailed description of the control circuit is omitted because it is not directly related to the present invention. The control device controls the output of the electric motor 10 so as to obtain an appropriate auxiliary force according to the detected torque and vehicle speed.

  The rotating shaft of the electric motor 10 and the output rotating shaft 12 of the first roller 1 are coupled. In this case, the rotation of the first roller 1 is transmitted to the ball screw nut 13 via the third roller 3, the fourth roller 4 and the second roller 2 to rotate the ball screw nut 13, and this rotation causes the rack shaft 11 to rotate. Steering wheels are steered by being driven in either direction of arrow D. The torque of the steering shaft and the vehicle speed corresponding to the load received by the rack shaft 11 at this time are detected, and the output of the electric motor 10 is controlled according to these detected values, so that the electric assist force is added to the manual steering force. Add as appropriate.

  4A is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 4B is a cross-sectional view taken along the line bb in FIG. 4A.

  5A is an enlarged view of the main part of FIG. 4A, and FIG. 5B is an enlarged view of the main part of FIG. 4B.

  In FIG. 4, two box-shaped holders 20, 20 that rotatably hold the third and fourth rollers 3, 4 are provided in housings 5, 6, respectively.

  The bearing 22 is press-fitted into the rollers 3 and 4, and the holders 20 and 20 hold the rollers 3 and 4 equipped with the bearing 22 via the pins 21 so as to be rotatable.

  In FIG. 5, a coil spring 32 is set in a hole 31 provided in the holder 20 and is pressed by a bolt 34 via a washer 33.

  The coil spring 32 is given a set load by being stopped by a wire ring 35 (or a snap ring) in a state of giving an elastic force. The amount of pressing the washer 33 can be adjusted with the bolt 34 and locked with the nut 36. Thereby, the range which gives pressing force can be set, ie, it can adjust.

  In addition, coil springs 41 and 41 having a lower load than the pressing force are set in the holes 42 formed in the two holders 20 and 20 in order to apply a separation force smaller than the pressing force in the direction opposite to the pressing force. It is.

  Then, when the end surfaces of the housings 5 and 6 and the end surfaces of the holders 20 and 20 come into contact with each other, the amount of movement of the holders 20 and 20 is regulated so that the amount of movement does not exceed the upper limit value.

  As described above in detail, in the present embodiment, the holders 20 that respectively hold the third and fourth rollers 3 and 4 so as to be rotatable are directed toward the first and second rollers 1 and 2, respectively. By applying the pressing force within the range of the movement amount, the transmission side roller bites in even if the pressing force is lost because the tangential force works during torque transmission.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

  Further, by applying a separating force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the contact with the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller. And the biting of the third and fourth rollers 3 and 4 can be prevented.

(Second embodiment of the present invention)
A second embodiment of the present invention will be described with reference to FIGS. This embodiment corresponds to claims 1 and 2.

  6A is a cross-sectional view of a friction roller transmission according to a second embodiment of the present invention, and FIG. 6B is a cross-sectional view taken along the line bb in FIG. 6A. It is.

  FIG. 7A is an enlarged view of the main part of FIG. 6A, and FIG. 7B is an enlarged view of the main part of FIG. 6B.

  A coil spring 32 is set in a hole 31 provided in the holder 20 and is pressed by a bolt 34 via a lid member 51.

  The coil spring 32 is given a set load by being stopped by the pin 52 in a state where the coil spring 32 is given an elastic force. The amount by which the lid member 51 is pressed can be adjusted by the bolt 34 and can be locked by the nut 36, whereby the range for applying the pressing force can be set, that is, can be adjusted.

  As described above, in the present embodiment, the holder 20 that rotatably holds the third and fourth rollers 3 and 4 is directed toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

  Further, by applying a separating force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the contact with the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller. And the biting of the third and fourth rollers 3 and 4 can be prevented.

(Third embodiment of the present invention)
A third embodiment of the present invention will be described with reference to FIGS. This embodiment corresponds to claims 1 and 2.

  FIG. 8A is a cross-sectional view of a friction roller transmission according to a third embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along the line bb of FIG. 8A. It is.

  FIG. 9A is an enlarged view showing the main part of FIG. 8A, and FIG. 9B is an enlarged view showing the main part of FIG. 8B.

  A coil spring 32 is in contact with the holder 20 and is pressed by the bolt 34 through a hole 34 a in the bolt 34.

  The coil spring 32 is given a set load by stopping at the bolt hole 34a in a state where the coil spring 32 is given an elastic force. The amount to be pushed by the bolt hole 34a can be adjusted by the bolt 34, and can be locked by the nut 36, whereby the range in which the pressing force is applied can be set, that is, can be adjusted.

  In other words, the coil spring 32 may be an elastic member, and may be a resin, a rubber member, or the like. The third and fourth rollers 3 and 4 are pressed by bending the elastic member. Since the range in which the pressing force is applied is the amount of bending of the elastic member, the range in which the pressing force is applied can be set by changing the amount of bending by the bolt 34.

  As described above, in the present embodiment, the holder 20 that rotatably holds the third and fourth rollers 3 and 4 is directed toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

  Further, by applying a separating force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the contact with the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller. And the biting of the third and fourth rollers 3 and 4 can be prevented.

(Fourth embodiment of the present invention)
A fourth embodiment of the present invention will be described with reference to FIGS. This embodiment corresponds to claim 4.

  FIG. 10A is a cross-sectional view of a friction roller transmission according to a fourth embodiment of the present invention, and FIG. 10B is a cross-sectional view taken along the line bb of FIG. 10A. It is.

  FIG. 11 is an enlarged view showing the main part of FIG.

  A coil spring 32 is set in a hole 31 provided in the holder 20 and is pressed by a bolt 34 via a washer 33.

  The coil spring 32 is given a set load by being stopped by a wire ring 35 (or a snap ring) in a state of giving an elastic force. The amount by which the washer 33 is pushed can be adjusted by the bolt 34 and can be locked by the nut 36, whereby the range in which the pressing force is applied can be set, that is, can be adjusted.

  In the housings 5 and 6, a backup bearing 60 is provided.

  In this backup bearing 60, a coil spring 62 is set between the convex head 63a of the shaft member 63 in the hole of the shaft 61 to be supported.

  The holder 20 is pressed against the side surfaces of the housings 5 and 6 by the biasing force of the coil spring 62.

  Accordingly, by applying a frictional resistance force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller are applied. Contact can be prevented, and biting of the third and fourth rollers 3 and 4 can be prevented.

  Further, in the present embodiment, the holder 20 that holds the third and fourth rollers 3 and 4 in a rotatable manner is moved toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

(Fifth embodiment of the present invention)
A fifth embodiment of the present invention will be described with reference to FIGS. This embodiment corresponds to claim 4.

  12A is a cross-sectional view of a friction roller transmission according to a fifth embodiment of the present invention, and FIG. 12B is a cross-sectional view taken along the line bb of FIG. 12A. It is.

  FIG. 13 is an enlarged view showing the main part of FIG.

  A coil spring 32 is set in a hole 31 provided in the holder 20 and is pressed by a bolt 34 via a washer 33.

  The coil spring 32 is given a set load by being stopped by a wire ring 35 (or a snap ring) in a state of giving an elastic force. The amount by which the washer 33 is pushed can be adjusted by the bolt 34 and can be locked by the nut 36, whereby the range in which the pressing force is applied can be set, that is, can be adjusted.

  Coil springs 71 and 71 are set in the holes 72 and 72 of the two holders 20 and 20 in order to give the holder 20 a frictional resistance smaller than the pressing force.

  The two holders 20 are pressed against the side surfaces of the housings 5 and 6 by the biasing force of the coil spring 71.

  Accordingly, by applying a frictional resistance force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller are applied. Contact can be prevented, and biting of the third and fourth rollers 3 and 4 can be prevented.

  Further, in the present embodiment, the holder 20 that holds the third and fourth rollers 3 and 4 in a rotatable manner is moved toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

(Sixth embodiment of the present invention)
A sixth embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to claim 4.

  FIG. 14A is a cross-sectional view of a friction roller transmission according to a sixth embodiment of the present invention, and FIG. 14B is a cross-sectional view taken along the line bb of FIG. 14A. It is.

  In order to give the holder 20 a frictional resistance smaller than the pressing force, a magnet 80 (magnet) is provided on the holder 20 or the housings 5 and 6, and the frictional resistance between the holder 20 and the housings 5 and 6 is provided. Is given.

  Accordingly, by applying a frictional resistance force smaller than the pressing force in the direction opposite to the pressing force to the holder 20, the first and second rollers 1 and 2 outside the predetermined range due to the weight of the non-transmission side roller are applied. Contact can be prevented, and biting of the third and fourth rollers 3 and 4 can be prevented.

  Further, in the present embodiment, the holder 20 that holds the third and fourth rollers 3 and 4 in a rotatable manner is moved toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

(Seventh embodiment of the present invention)
The seventh embodiment of the present invention will be described with reference to FIGS. This embodiment corresponds to claim 6.

  FIG. 15A is a cross-sectional view of a friction roller transmission according to a seventh embodiment of the present invention, and FIG. 15B is a cross-sectional view taken along the line bb of FIG. 15A. It is.

  16 (a) is an enlarged view showing the main part of FIG. 15 (a), and FIG. 16 (b) is an enlarged view showing the main part of FIG. 15 (b).

  On the side where the third and fourth rollers 3 and 4 are separated from each other, a bolt 91 is screwed into the housings 5 and 6, and the position of the bolt 91 can be adjusted and locked by a nut 92.

  A coil spring 94 is interposed between the hole 93 formed at the tip of the bolt 91 and the housing 20.

  Thereby, the movement amount of the holder 20 is prevented from exceeding the upper limit value between the end face of the bolt 91 on which the coil spring 94 is set and the end face of the holder 20. Accordingly, the maximum movement amount of the holder 20 can be adjusted by adjusting the bolt 91.

  Therefore, by providing a movement amount restricting means for preventing the movement of the holder 20, the movement amount of the holder 20 is prevented from exceeding the upper limit value, and the third and fourth rollers 3 and 4 are overtaken and excessive third and fourth. The loss torque of the bearing due to the biting of the fourth rollers 3 and 4 can be reduced.

  Further, in the present embodiment, the holder 20 that holds the third and fourth rollers 3 and 4 in a rotatable manner is moved toward the first and second rollers 1 and 2, respectively, within a predetermined range of movement. By applying the pressing force, the tangential force acts on the transmission-side roller during torque transmission, so that even if the pressing force is lost, the transmission-side roller bites in.

  On the other hand, the non-transmission side roller is in contact with the first and second rollers 1 and 2 within a predetermined range of movement, but the pressing force disappears outside the predetermined range. It was made the structure which does not bite in by separating from 1 and 2. Further, the spring 94 can prevent the rollers 3 and 4 from contacting due to their own weight.

  In addition, since the range of the predetermined movement amount is adjustable, it is not necessary to increase the accuracy of each used component, and the cost can be reduced.

(Eighth embodiment)
FIG. 17 is an input / output characteristic diagram according to the present invention and the related art. FIG. 18 is an input / output characteristic diagram in which the main part (near input torque 0) in FIG. 17 is enlarged.

  In the initial set state, when the input torque is 0, the output torque (= loss torque) is 0.

  However, once the torque is input, even if the input torque is set to 0, the third and fourth rollers 3 and 4 are bitten and a loss torque is generated.

  Conventionally, since the amount of biting of the third and fourth rollers 3 and 4 cannot be adjusted, the loss torque is larger than a specified value.

  On the other hand, according to the present invention, the amount of biting of the third and fourth rollers 3 and 4 can be adjusted, so that the loss torque can be set to a specified value or less.

  Needless to say, the present invention can be variously modified without being limited to the above-described embodiments and drawings as long as the friction roller transmission according to the present invention operates.

FIG. 1A is a side view of a friction roller type transmission (reduction gear) according to the basic structure of the present invention, and FIG. 1B is a schematic perspective view of the friction roller type transmission shown in FIG. It is. FIG. 2A is a side view of a friction roller type transmission according to the basic structure of the present invention (a diagram showing a transmission path of the first roller → the fourth roller → the second roller), and FIG. FIG. 3 is a side view of the same (a diagram illustrating a transmission path of the first roller → the third roller → the second roller). 1 is a longitudinal sectional view of an electric power steering apparatus provided with a friction roller transmission according to a first embodiment of the present invention. (A) is sectional drawing along the AA line of FIG. 3, FIG.4 (b) is sectional drawing along the bb line | wire of Fig.4 (a). (A) is a figure which expands and shows the principal part of (a) of FIG. 4, FIG.5 (b) is a figure which expands and shows the principal part of (b) of FIG. (A) is sectional drawing of the friction roller type transmission which concerns on 2nd Embodiment of this invention, FIG.6 (b) is sectional drawing along the bb line of Fig.6 (a). . (A) is a figure which expands and shows the principal part of (a) of FIG. 6, FIG.7 (b) is a figure which expands and shows the principal part of (b) of FIG. (A) is sectional drawing of the friction roller type transmission which concerns on 3rd Embodiment of this invention, FIG.8 (b) is sectional drawing along the bb line of Fig.8 (a). . (A) is a figure which expands and shows the principal part of (a) of FIG. 8, FIG.9 (b) is a figure which expands and shows the principal part of (b) of FIG. (A) is sectional drawing of the friction roller type transmission which concerns on 4th Embodiment of this invention, FIG.10 (b) is sectional drawing along the bb line of Fig.10 (a). . It is a figure which expands and shows the principal part of (b) of FIG. (A) is sectional drawing of the friction roller type transmission which concerns on 5th Embodiment of this invention, FIG.12 (b) is sectional drawing along the bb line of Fig.12 (a). . It is a figure which expands and shows the principal part of (b) of FIG. (A) is sectional drawing of the friction roller type transmission which concerns on 6th Embodiment of this invention, FIG.14 (b) is sectional drawing along the bb line of Fig.14 (a). . (A) is sectional drawing of the friction roller type transmission which concerns on 7th Embodiment of this invention, FIG.15 (b) is sectional drawing along the bb line of Fig.15 (a). . (A) is a figure which expands and shows the principal part of (a) of FIG. 15, FIG.16 (b) is a figure which expands and shows the principal part of (b) of FIG. It is an input / output characteristic diagram according to the present invention and the related art. FIG. 18 is an input / output characteristic diagram in which a main part (near input torque 0) in FIG. 17 is enlarged.

Explanation of symbols

a input shaft b output shaft 1 first roller 2 second roller 3 third roller 4 fourth roller 5, 6, 7 housing 10 electric motor 11 rack shaft 11b screw groove 12 output rotating shaft 13 ball screw nut 13a screw groove 14 Ball 15 Bearing 20 Holder 21 Pivot 22 Bearing 31 Hole 32 Coil Spring 33 Washer 34 Bolt 34a Hole 35 Wiring (or Snap Ring)
36 Nut 41 Coil spring 42 Hole 51 Lid member 52 Pin 60 Backup bearing 61 Shaft 62 Coil spring 63 Shaft member 63a Convex head 71 Coil spring 72 Hole 80 Magnet 91 Bolt 92 Nut 93 Hole 94 Coil spring

Claims (7)

The first roller and the second roller centered on each axis are arranged so as not to contact each other on two axes spaced apart in parallel with each other,
The third roller and the fourth roller that are in contact with both the first and second rollers are on the opposite side of the line connecting the first roller and the second roller and the center of the first roller and the second roller. Place and
The angle formed by the tangent line between the first roller and the third or fourth roller and the tangent line between the second roller and the third or fourth roller is a friction angle obtained from the friction coefficient between the rollers. In friction roller type transmission set to be less than double,
A holder for rotatably holding the third and fourth rollers respectively applies a pressing force within a predetermined range of movement toward the first and second rollers, respectively. Friction roller type transmission.   2. The friction roller transmission according to claim 1, wherein the range of the predetermined movement amount is adjustable.   The friction roller transmission according to claim 1 or 2, wherein a separation force smaller than a pressing force in a direction opposite to the pressing force is applied to the holder.   The friction roller transmission according to claim 1 or 2, wherein a frictional resistance force smaller than a pressing force is applied to the holder.   5. The friction roller type shift according to claim 1, further comprising movement amount regulating means for preventing movement of the holder so that the movement amount of the holder does not exceed an upper limit value. 6. Machine.   6. The friction roller transmission according to claim 5, wherein the movement amount regulating means is adjustable.   An electric power steering apparatus comprising the friction roller transmission according to any one of claims 1 to 6.

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