JPH11223256A - Friction transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure wherein no backlash occurs, a large transmission ratio is provided, a size is small and good transmission efficiency is provided. SOLUTION: Input and output shafts 6 and 7 are arranged such that the center axes α and β of both intersect each other. The input friction surface 15 of an input disk 14 concentrically fixed to the input shaft 6 is engaged by friction with the output friction surface 31 of an output disk 17 concentrically supported to the output shaft 7. A diametric ratio of the input and output friction surfaces 15 and 31 is set large to realize a large transmission ratio. Also, by using a plate spring 27 to apply pressure, good transmission efficiency is provided immediately after the start of transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A friction transmission according to the present invention is incorporated in a power transmission section of various mechanical devices, for example, to reduce a rotational motion inputted from an electric motor and increase a torque, or to increase a rotational speed. After raising it, send it to the output unit.

[0002]

2. Description of the Related Art Various types of mechanical devices use transmissions that convert the rotation speed and send the rotation backward. Conventionally, as such a transmission, a friction type speed reducer has been used in addition to a gear type speed reducer including a worm speed reducer, a planetary gear speed reducer, and the like. Of these, a general gear type speed reducer requires a combination of gears in a double row or a large diameter gear in order to obtain a large speed ratio (reduction ratio or speed increase ratio). Occurs. For this reason, it is difficult to realize a gear type speed reducer which is small and can obtain a large speed ratio. Also, in the case of a gear type transmission, since it is necessary to set a backlash, it is inevitable that some rattling occurs in the transmission portion, and this rattling may cause a problem depending on the application. There are cases. In the case of a worm transmission, a relatively small size and a large reduction ratio can be obtained, but a small size and a large speed increase ratio cannot be obtained. In addition, in the case of a worm transmission, as in the case of a general gear type transmission, it is inevitable that rattling occurs, and it is difficult to obtain high efficiency.

On the other hand, in the case of a friction type transmission,
There is no need to set backlash as in the case of a gear type transmission, and no rattling occurs. Conventionally, such a friction transmission is disclosed in Japanese Patent Application Laid-Open No. 6-288453. The friction type transmission described in this publication is formed by frictionally engaging an outer peripheral surface of a tapered small-diameter roller concentric with an input shaft and a large-diameter taper roller concentric with an output shaft. . However, in the case of the friction type transmission described in this publication, the contact pressure between the outer peripheral surfaces of the tapered rollers cannot be stabilized from the initial stage of power transmission, and if the transmission efficiency deteriorates in this initial stage. There's the problem I said. SUMMARY OF THE INVENTION In view of such circumstances, the present invention has been devised in order to realize a friction-type transmission that is small and can obtain a large gear ratio and that can obtain good transmission efficiency from the beginning of power transmission.

[0004]

SUMMARY OF THE INVENTION A friction transmission according to the present invention comprises:
First and second rotating shafts arranged in a direction to cross each other's central axes, a first disk supported concentrically with the first rotating shaft and rotating with the first rotating shaft, A first friction surface provided on one disk and concentric with the first rotation axis, a second disk supported concentrically with the second rotation axis and rotating together with the second rotation axis, And a second friction surface provided concentrically with the second rotating shaft. The second friction surface and the first friction surface are frictionally engaged. In addition, loading between at least one of the first and second disks and the rotating shaft supporting the disk, during operation, for pressing the friction surface of the disk toward the friction surface of the other disk. A cam device is provided. Further, a third disk concentric with the second disk is provided around the second rotating shaft, and the first disk is sandwiched between the second and third disks. This third disk is an angular type. In a state where displacement in a direction away from the second disk is prevented around the second rotating shaft by a ball bearing, the bearing is rotatably supported relative to the second rotating shaft and the second disk. Furthermore,
A preload spring for elastically pressing the first and second friction surfaces together is provided.

[0005]

The gear ratio obtained by the friction transmission of the present invention as described above is the ratio of the diameter of the first friction surface to the diameter of the second friction surface. In the case of the friction transmission of the present invention, the first and second rotating shafts are arranged in a direction in which the central axes of these two rotating shafts intersect with each other. The diameter of the friction surface can be set freely. In particular, since it is possible to considerably reduce the diameter of any of the friction surfaces, the ratio between the diameter of the first friction surface and the diameter of the second friction surface is increased to achieve a small and large gear ratio. The obtained friction type transmission can be realized.
Furthermore, since the first disk is sandwiched between the second and third disks and the loading cam device and the preload spring are provided, the power transmission between the first disk and the second disk is greatly increased from the beginning. The operation can be stably performed until a steady operation state in which large power is transmitted.

[0006]

FIG. 1 shows a first embodiment of the present invention. The friction transmission 1 has a casing 2. The casing 2 includes a main portion 3 and a pair of covers 5 and 5 which are fixedly connected to both ends of the main portion 3 by bolts 4 and 4 to close both ends of the main portion 3. . In such a casing 2, an input shaft 6 corresponding to the first rotating shaft and an output shaft 7 also corresponding to the second rotating shaft are arranged in a direction in which their central axes are orthogonal to each other. And rotatably supported.

First, in order to support the input shaft 6, a thick mounting portion 8 is provided in a part of the main portion 3, and a first mounting hole 9 is formed in the mounting portion 8 in a diametrical direction of the main portion 3. It is formed over. The input shaft 6 is inserted into the first mounting hole 9.
It is rotatably supported by a pair of rolling bearings 10a and 10b. These two rolling bearings 10a and 10b are those which can support not only a radial load but also a thrust load, such as a deep groove type or angular type ball bearing. The input shaft 6 is supported inside the first mounting hole 9 only for rotation (displacement in the axial direction is impossible).

Further, in order to support the output shaft 7, second mounting holes 11, 11 are formed concentrically with each other at the center of the pair of end plates 5, 5. And these two second mounting holes 1
A portion near both ends of the intermediate portion of the output shaft 7 is rotatably supported by a pair of rolling bearings 12 inside the insides 1 and 11. These two rolling bearings 12 and 12 use a bearing capable of supporting not only a radial load but also a thrust load, such as a deep groove type or an angular type ball bearing. However, the two rolling bearings 12 do not necessarily need to have a structure capable of supporting a thrust load. The output shaft 7 is supported inside the second mounting holes 11 and 11 only for rotation (displacement in the axial direction is impossible). While the input shaft 6 and the output shaft 7 are supported by the casing 2 in this manner, the center axis α of the input shaft 6
And the central axis β of the output shaft 7 intersect at a point O on the central axis β of the output shaft 7.

A spline portion 13 is provided at the base end (upper end in FIG. 1) of the input shaft 6 and protrudes diametrically outward from the outer surface of the main portion 3. The input shaft 6 is freely rotatable. An input disk 14 corresponding to the first disk described in the claims is attached to a portion of the input shaft 6 which is exposed on the inner surface side of the main part 3 at a tip end portion (lower end portion in FIG. 1) of the input shaft 6. 6 and integrally fixed. The input disk 14 and the input shaft 6 may be integrated. This input disk 14
Is formed in the shape of a tapered truncated cone whose outer diameter becomes smaller toward the distal end, and is provided concentrically with the input shaft 6,
It rotates with this input shaft 6. The conical convex surface concentric with the input shaft 6 constituting the outer peripheral surface of the input disk 14 is defined as an input friction surface 15 corresponding to a first friction surface described in claims. This input friction surface 1
5 is a point O on the central axis β of the output shaft 7.
Intersect at parts.

On the other hand, around an intermediate portion of the output shaft 7 and a portion located inside the casing 2, an output disk 17 corresponding to a second disk is provided via a cylindrical sleeve 16. Loading cam device 18,
An idler disk 19 corresponding to the third disk described in the claims is provided. The sleeve 16 is formed in a cylindrical shape as a whole, and has an inner peripheral surface at one end (right end in FIG. 1) on an outer peripheral surface at an intermediate portion of the output shaft 7,
(See the upper part of FIG. 1) or the ball spline 21 (see the lower part of FIG. 1). In the drawings, the spline 20 and the ball spline 2
1 are illustrated, but only one of them is provided between the inner peripheral surface of one end of the sleeve 16 and the outer peripheral surface of the intermediate portion of the output shaft 7 in practice. The sleeve 16
Between the inner peripheral surface of the other end (left end in FIG. 1) and the outer peripheral surface of the intermediate portion of the output shaft 7, only a radial load such as a sliding bearing or a radial needle bearing is supported (supports a thrust load). No) A bearing 22 is provided. Therefore, the sleeve 16 is supported around the output shaft 7 so as to rotate in synchronization with the output shaft 7 and to be displaceable in the axial direction of the output shaft 7. The spline 20 or the ball spline 21 may be provided instead of the bearing 22.

On the outer peripheral surface of one end of the sleeve 16 as described above, a cam plate 23 for constituting the loading cam device 18 is provided in an outward flange shape integral with the sleeve 16. A loading nut 24 is screwed and fixed to the outer peripheral surface of the other end of the sleeve 16. Further, between the loading nut 24 and the cam plate portion 23, rollers 25, 25 for constituting the loading cam device 18, the output disk 17, the holder 26, and a preload spring according to claim And a plate spring 27 corresponding to are arranged in series in the axial direction of the sleeve 16 in order from the cam plate portion 23 side.

The output disk 17 is connected to the sleeve 16
Is supported concentrically with the sleeve 16 by a bearing 28, such as a sliding bearing or a radial needle bearing, which supports only a radial load. One side (the right side in FIG. 1) of the output disk 17 and the one side (the left side in FIG. 1) of the cam plate 23 have cam surfaces 29a and 29b which are irregularities extending in the circumferential direction. Is provided. The rollers 25, 25 are rolled between the cam surfaces 29a, 29b so that their respective central axes coincide with the diametrical directions of the cam plate portion 23 and the output disk 17, and can be rolled by the retainer 30. In the state of being held. With this configuration, the loading cam device 18 is configured to transmit the rotational force between the sleeve 16 and the output disk 17 while pressing the output disk 17 in a direction away from the cam plate 23. I have.

The shape of the cam surfaces 29a and 29b is determined according to the direction of the torque to be transmitted. That is, when transmitting rotation in both directions, the cam surfaces 29a,
When the shape of 9b is made symmetrical in the circumferential direction and only rotation in one direction is transmitted, it is made asymmetric as shown in FIG.
The cam is configured to run idle while being located at the most depressed portion of the cam surface. That is, when transmitting rotation in only one direction,
The shape of the cam surface 29a (29b) is such that an inclined portion is provided only in one rotational direction from the most concave portion. If the cam surfaces 29a and 29b having such a shape are adopted, the roller 2
When the cam surface 29a (29b) is displaced to the left in FIG. 7, the transmission of power is performed, and when the cam surface 29 is moved rightward, the transmission of power is interrupted. Can be provided.

An output friction surface 31 corresponding to the second friction surface described above is formed on the other surface (left surface in FIG. 1) of the output disk 17 near the outer diameter. The output friction surface 31 is a conical convex surface whose contact portion with the input friction surface 15 is parallel to the input friction surface 15, and the generatrix of the friction surfaces 31, 15 extends over substantially the entire length of the generatrix. , So that they abut each other evenly. It should be noted that the extension of the generatrix of the input friction surface 15 intersects with the point O on the central axis β of the output shaft 7 as described above.
It is most preferable to set the spin at the contact portions 1 and 15 to 0. It is preferable that they intersect at least near the central axis β. The cross-sectional shape (generating line shape) of the friction surfaces 31, 15 is such that one is a straight line and the other is a convex curved surface having a large radius of curvature. This is preferable from the viewpoint of realizing a stable contact state without causing an edge load.

The holder 26 is supported concentrically with the sleeve 16 around an intermediate portion of the sleeve 16 by a bearing 32 that supports only a radial load, such as a sliding bearing and a radial needle bearing. The above holder 26
Has a substantially L-shaped cross section having a ring portion 33 and a cylindrical portion 34, and is formed in an annular shape as a whole.
4 with the loading nut 24 facing the loading nut 24,
It is arranged around the middle part of the sleeve 16. An annular protrusion 35 is formed at a portion of the loading nut 24 near the outer diameter and opposite to the ring portion 34. The disc spring 27 is provided between the loading nut 24 and the ring portion 34 at a portion on the inner diameter side of the protrusion 35. The height of the projection 35 is smaller than the thickness of the disc spring 27 in the free state, but is larger than the thickness of the disc spring 27 in the fully compressed state.

Further, the idler disk 19 is provided around the holder 26 by an angular ball bearing 36 so as to be concentric with the sleeve 16 and the holder 26, and
The rotation relative to the sleeve 16 and the holder 26 is freely supported. Therefore, the idler disk 19
Is rotatably supported with respect to the holder 26 while ensuring sufficient thrust rigidity and radial rigidity.
A backup surface 37 is formed on one side (right side in FIG. 1) of the idler disk 19 near the outer diameter. The backup surface 37 is a conical convex surface parallel to the input friction surface 15, and abuts on the input friction surface 15 at a portion opposite to the output friction surface 31 uniformly over substantially the entire length of the bus. I have to.

On one surface of the output disk 17 and the other surface of the idler disk 19, that is, on the surface opposite to the surface on which the output friction surface 31 and the backup surface 37 are formed, respectively, reinforcing ribs 38a extending in the diameter direction are provided. 38b. These reinforcing ribs 38a and 38b increase the bending rigidity of the output disk 17 and the idler disk 19, respectively, so that the power can be transmitted by the friction transmission.
The input friction surface 15 and the output friction surface 31 and the backup surface 37 play a role of uniformly abutting over substantially the entire length of the generatrix of the input friction surface 15.

The friction transmission of the present invention configured as described above transmits torque from the input shaft 6 to the output shaft 7 by the following functions. When the input shaft 6 and the input disk 14 are rotated by a drive shaft (not shown), the output disk 17 is rotated based on the frictional engagement between the input friction surface 15 and the output friction surface 31. The rotation of the output disk 17 is transmitted to the sleeve 16 via the loading cam device 18, and the rotation of the sleeve 16 is transmitted to the output shaft 7 via the spline 20 or the ball spline 21. The input friction surface 15 and the output friction surface 31 are based on the elasticity of the disc spring 27,
It has been in contact with a certain contact pressure from the beginning. Therefore, the transmission of the rotational force from the input shaft 6 to the output shaft 7 can be efficiently performed without slipping from the beginning.

When transmitting the rotational force from the input shaft 6 to the output shaft 7 as described above, the loading cam device 18 transmits the rotational force and simultaneously presses the output disk 17 toward the input disk 14. . As described above, the load pressing the output disk 17 toward the input disk 14 increases as the torque transmitted from the input shaft 6 to the output shaft 7 increases. Therefore, each of the cam surfaces 29a, 29b constituting the loading cam device 18
If the shape is devised, the contact pressure between the input friction surface 15 and the output friction surface 31 can be set to an appropriate value, and the torque can be efficiently transmitted from the input shaft 6 to the output shaft 7. . Further, as described above, since the extension of the generatrix of the input friction surface 15 intersects at or near the point O on the central axis β of the output shaft 7, the input friction surface 15 and the output friction surface 31 are crossed. It is possible to transmit the torque efficiently without causing a slip at the contact portion with the shaft.

Further, a part of the input friction surface 15 provided on the outer peripheral surface of the input disk 14 diametrically opposite to the contact portion with the output friction surface 31 is brought into contact with the backup surface 37. Let me. Therefore, even if the loading cam device 18 presses the output disk 17 against the input disk 14, the input disk 14 does not retreat from the output disk 17. Therefore, the contact pressure between the input friction surface 15 and the output friction surface 31 by the loading cam device 18 can be reliably ensured. The idler disk 19 rotates at the same speed as the output disk 17 in a direction opposite to the output disk 17 during operation of the transmission.

The speed ratio (reduction ratio in the above description) that can be realized by the friction transmission of the present invention as described above is the ratio of the diameter of the input friction surface 15 to the diameter of the output friction surface 31. In the case of the friction transmission of the present invention, the input shaft 6 and the output shaft 7
Are arranged in a direction in which the central axes of these two shafts 6 and 7 cross each other, so that the diameter of the input friction surface 15 and the diameter of the output friction surface 31 can be set freely. In particular, for example, as shown, the diameter of the input friction surface 15 can be considerably reduced. Therefore, it is possible to increase the ratio of the diameter of the input friction surface 15 to the diameter of the output friction surface 31, thereby realizing a small friction type transmission capable of obtaining a large gear ratio. In the above description, the transmission according to the present invention is used as a speed reducer. However, the transmission according to the present invention can be used as a gearbox with the same configuration. That is, if the input shaft and the output shaft are reversed, the shaft functions as it is.

Next, FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the first example described above, the output shaft 7 is projected from both sides of the casing 2 so that the output can be taken out from both sides of the casing 2. On the other hand, in the case of this example, the output shaft 7 is connected to one side of the casing 2 (the left side in FIG. 2).
And the output is taken out only from one side of the casing 2. For this reason, in the case of this example, a bottomed cylindrical support portion 39 is provided at the center of one end plate 5a (right side in FIG. 2), and one end portion of the output shaft 7 (right end portion in FIG. 2). )
Is rotatably supported inside the support portion 39.
The other configurations and operations are the same as those of the first example described above, and therefore, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 3 shows a third embodiment of the present invention.
An example is shown. In the first example described above, the central axis α of the input shaft 6 and the central axis β of the output shaft 7 intersect at a right angle, whereas in the case of this example, the central axis α of the input shaft 6 is The central axis β of the output shaft 7 intersects in an inclined state. An extension of the generatrix of the input friction surface 15 intersects with the central axis α of the input shaft 6 at a point O on the central axis β of the output shaft 7. Since it is the same as in the case of one example, the same parts are denoted by the same reference numerals,
A duplicate description will be omitted.

FIG. 4 shows a fourth embodiment of the present invention.
An example is shown. In the case of this example, the output shaft 7 is protruded only to one side (the left side in FIG. 4) of the casing 2 so that the output is taken out from only one side of the casing 2. For this reason, in the case of this example, a bottomed cylindrical support portion 39 is provided at the center of one end plate 5a (right side in FIG. 4), and the output shaft 7 is provided.
Is rotatably supported inside the support portion 39. Other configurations and operations are the same as those of the above-described third example, and therefore, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

Next, FIG. 5 shows a fifth embodiment of the present invention.
An example is shown. In each of the above-described examples, the loading cam device 18 is provided between the output shaft 7 and the output disk 17. On the other hand, in the case of the present example, a loading cam device 18 is provided between the input shaft 6 and the input disk 14. When the loading cam device 18 is provided between the input shaft 6 and the input disk 14 as described above, the input disk 14
Penetrates between the output disk 17 and the idler disk 19 in a wedge shape. Therefore, the input friction surface 15 and the output friction surface 31 can be generated without particularly increasing the thrust (the pressing force in the axial direction) generated by the loading cam device 18.
Contact pressure can be secured. As a result, the loading cam device 18 and the friction transmission incorporating the loading cam device 18 can be reduced in size and weight. Other configurations and operations are the same as those in the first example described above, and therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted.

Next, FIG. 6 shows a sixth embodiment of the present invention.
An example is shown. In the case of this example, the input disk 14 is provided at a portion opposite to the input disk 14 with respect to the output shaft 7.
An idler disk 40 having the same shape as that of the idler disk 40 is provided. And this idler disk 40, which is the fourth disk,
While being arranged substantially concentrically with the input disk 14 and being sandwiched between the output friction surface 31 and the backup surface 37,
It is rotatably supported inside the casing 2. Output disk 17 and idler disk 1 during operation of friction transmission
9 sandwiches the input disk 14 and the idler disk 40 that are located at diametrically opposite positions. Because of this,
The operating state of the friction transmission can be stabilized by making the distribution of the stress acting on the output disk 17 in the circumferential direction nearly uniform. Other configurations and operations are the same as those in the first example described above, and therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted.

[0027]

Since the present invention is constructed and operates as described above, a friction transmission having a large gear ratio and no rattling can be constructed in a small size. For this reason, various mechanical devices incorporating the transmission can be reduced in size and improved in performance.
Further, from the initial state immediately after the start of the transmission of the rotational driving force, good transmission efficiency can be obtained without sliding the friction surfaces.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view showing the second example.

FIG. 3 is a sectional view showing a third example.

FIG. 4 is a sectional view showing a fourth example.

FIG. 5 is a sectional view showing the fifth example.

FIG. 6 is a sectional view showing a sixth example.

FIG. 7 is a developed view showing an example of a cam surface for regulating a rotation direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Friction transmission 2 Casing 3 Main part 4 Bolt 5, 5a Cover 6 Input shaft 7 Output shaft 8 Mounting part 9 First mounting hole 10a, 10b Rolling bearing 11 Second mounting hole 12 Rolling bearing 13 Spline part 14 Input disk 15 Input Friction surface 16 Sleeve 17 Output disk 18 Loading cam device 19 Idler disk 20 Spline 21 Ball spline 22 Bearing 23 Cam plate portion 24 Loading nut 25 Roller 26 Holder 27 Disc spring 28 Bearing 29a, 29b Cam surface 30 Cage 31 Output friction surface 32 Bearing 33 Ring section 34 Cylindrical section 35 Projection 36 Ball bearing 37 Backup surface 38a, 38b Reinforcement rib 39 Support section 40 Idler disk

Claims (1)

[Claims] A first and a second rotating shaft arranged in a direction in which their central axes intersect each other, and a first rotating shaft supported concentrically with the first rotating shaft and rotating together with the first rotating shaft. A disk, provided on the first disk, a first friction surface concentric with the first rotation axis, a second disk supported concentrically with the second rotation axis and rotating with the second rotation axis, The second disk is provided with a second friction surface concentric with the second rotating shaft, and the second friction surface is frictionally engaged with the first friction surface. A loading cam device is provided between at least one of the two disks and the rotating shaft that supports the disk, and a friction surface of the disk is pressed toward the friction surface of the other disk during operation. Around the second rotation axis, the second disk A concentric third disk is provided, and the first disk is sandwiched between the second and third disks. The third disk is wound around the second rotating shaft by an angular type ball bearing around the second rotating shaft. In a state where displacement in the direction away from the second disc is prevented, these are supported rotatably relative to the second rotating shaft and the second disk.
A friction transmission having a preload spring for elastically pressing the second friction surfaces against each other.