JP3722982B2 - Friction type power transmission device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a frictional power transmission device. In particular, the present invention relates to a planetary ball that revolves around a sun roller.
[0002]
[Prior art]
For example, a frictional power transmission device having planetary balls is inscribed in a sun roller as an input member, a plurality of planetary balls that revolve while rolling on the outer peripheral groove of the sun roller, and the plurality of planetary balls. It has a circumscribed member as a fixing member and a carrier as an output member that rotatably supports a plurality of planetary balls. The planetary ball is interposed between the sun roller and the circumscribing member so that there is no play between them and the sun roller and the circumscribing member are reliably in contact with each other with a pressure applied in the radial direction. The driving force is transmitted from the sun roller to the carrier while rolling. Further, the carrier may be fixed and the circumscribed member may be used as the output member.
[0003]
Regardless of what the output member is, a dedicated bearing that rotatably supports the output member is provided in order to receive an axial or radial load applied to the output member.
[0004]
[Problems to be solved by the invention]
However, if the output member is supported by a dedicated bearing, the structure of the frictional power transmission device becomes complicated.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a frictional power transmission device that can simplify the structure and has stable power transmission.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the planetary ball of the frictional power transmission device also serves as a bearing function. In other words, the frictional power transmission device according to the first aspect of the present invention includes a sun roller, a plurality of planetary balls circumscribing the outer periphery of the sun roller, a carrier that holds these planetary balls in a rollable manner, and a planetary ball. In the frictional power transmission device having a rotatable ring-shaped circumscribed member that is inscribed in, one of the sun roller and the circumscribed member moves the other of the sun roller and the circumscribed member in the axial direction via a plurality of planetary balls. The planetary ball includes a first planetary ball group and a second planetary ball group, and the sun roller has a pair of inner orbits composed of conical surfaces inclined in opposite directions along the axial direction. Each inner orbit is in contact with the corresponding planetary ball group, and the circumscribed member includes a pair of elastically deformable annular inclined plates inclined in opposite directions, and the inner peripheral surfaces of the pair of annular inclined plates Is Comprise respectively conical surface, the conical surface of the pair of inclined annular plate, corresponding to a pair of outer raceway of respectively opposite the inner raceway of the corresponding sides of the planetary ball groups, circumscribing member includes a pair of outer It is characterized by having elasticity that causes an elastic restoring force to bring the tracks closer to each other.
[0007]
According to this configuration, the following effects are exhibited. For example, it can be used as a power transmission device in which a sun roller is fixed to a rotating shaft such as a motor as an input member and a circumscribed member is an output member. At this time, since the sun roller can support the circumscribed member in the radial direction and the axial direction via the planetary ball, a dedicated bearing for supporting the circumscribed member in the axial direction, a member for holding the bearing, etc. It can be omitted. The circumscribed member may support the sun roller via the planetary ball.
[0008]
In addition, since it is supported through the planetary ball in the axial direction, the load in the axial direction can be converted into the applied pressure of the planetary ball for power transmission, and power transmission can be stabilized.
[0010]
In addition, the pair of inner orbits of the sun roller and the pair of outer orbits of the circumscribed member can receive loads opposite to each other in the axial direction via each planetary ball group, and can balance them with each other. As a result, it is possible to achieve stable power transmission.
According to a second aspect of the present invention, there is provided the frictional power transmission device according to the first aspect, wherein the circumscribed member extends from the pair of annular inclined plates and is abutted against each other and fixed. It is characterized by including a pair of contact plates.
According to a third aspect of the present invention, there is provided the frictional power transmission device according to the second aspect, wherein the circumscribed member includes one contact plate and one annular inclined plate as a single member. And the other plate material in which the other abutment plate and the other annular inclined plate are integrally formed with a single member.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a planetary ball transmission that is a frictional power transmission device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 is a sectional view of a planetary ball type transmission according to an embodiment of the present invention.
[0013]
The planetary ball type transmission 1 is attached to a motor 2 as a drive source. A sun roller 31 as an input member of the planetary ball type transmission 1 is fitted to the rotating shaft 22 of the motor 2, and a circumscribed member 33 surrounding the periphery is provided as an output member. Thus, the motor 2 and the planetary ball type transmission 1 constitute an integral unit.
[0014]
The motor 2 includes a housing 21 as a fixed member and the above-described rotating shaft 22 protruding from the housing 21. The rotating shaft 22 is a stepped shaft whose portion near the housing 21 is thick, and is supported by a bearing (not shown) provided in the housing 21 so that the position of the rotating shaft 22 is rotatable in the axial direction.
[0015]
The planetary ball type transmission 1 includes the above-described cylindrical sun roller 31 that rotates integrally with the rotating shaft 22, a plurality of planetary balls 32 that roll on the outer peripheral surface of the sun roller 31, and the planetary balls 32 are inscribed. A circumscribed member 33 that rolls and a carrier 34 that rotatably holds a plurality of planetary balls 32 are provided. The carrier 34 is fixed to the housing 21 of the motor 2. The circumscribed member 33 and the rotation axis of the sun roller 31 are arranged concentrically. The plurality of planetary balls 32 between the sun roller 31 and the circumscribed member 33 are urged with a predetermined pressure without play, and the inner track of the sun roller 31 and the circumscribed member 33 The outer track can be rolled reliably.
[0016]
In the planetary ball type transmission 1 of the present embodiment, the planetary ball 32 described above has a direction in which the rotating shaft 22 extends (hereinafter referred to as “axial direction”) and a direction orthogonal to the axial direction (hereinafter referred to as “radial direction”). It also has a bearing function. That is, the circumscribed member 33 is supported by the sun roller 31 via the planetary ball 32.
[0017]
This will be described in detail below.
[0018]
The sun roller 31 is held in the axial direction by a retaining ring 23 and a step 22 a at a small diameter portion of the rotating shaft 22. The sun roller 31 has an inner peripheral surface that is fitted to the rotating shaft 22 of the motor 2. Moreover, the outer peripheral surface of the sun roller 31 is inclined so that both end portions have a small diameter so as to have the maximum outer diameter at the central portion along the axial direction. A pair of inner tracks 31a and 31b on which the planetary ball 32 rolls while circumscribing are provided on the outer peripheral surface. That is, the first inner track 31a near the base of the rotating shaft 22 of the motor 2 and the second inner track 31b on the tip side of the rotating shaft 22 of the motor 2 are provided with a distance in the axial direction. The conical surfaces are inclined at opposite angles to each other at the same angle with respect to the axial direction.
[0019]
A plurality of, for example, eight planetary balls 32 are provided. These planetary balls 32 include a first planetary ball group 32A (first group) rolling on the first inner orbit 31a and a second planetary ball group 32B (second group) rolling on the second inner orbit 31b. ). Each planetary ball 32 of the first group and the second group is held by a carrier 34 at a predetermined axial position and at equal intervals on a circumference of a predetermined radial position around the rotation shaft 22. .
[0020]
The carrier 34 is formed in an annular shape and has a plurality of ball accommodating portions 34a that support the planetary ball 32 in a rotatable manner. The ball accommodating portions 34a are openings into which the planetary balls 32 are fitted, and are provided at two locations in the axial direction corresponding to the planetary balls 32 and at eight locations in total in the circumferential direction. The carrier 34 also functions as a cage when this planetary ball type transmission is functioned as a bearing. A circumscribed member 33 is disposed on the outer side of the carrier 34 and the planetary ball 32.
[0021]
Enclosing member 33 includes a main portion 36 a disk-shaped as one plate member arranged at the base side of the rotary shaft 22, the abutment plate to each other is fixed by Oite plurality of rivets 38 in the center of the main body portion 36 And a sub-portion 37 as the other plate member that rotates integrally. The main part 36 and the sub part 37 are each formed of a plate material having a constant thickness.
[0022]
The main body part 36 is a radially outer disk-shaped disk part 36a as an output member and a contact plate , and an annular inclined plate extending in the inner periphery of the disk part 36a and inclined in the axial direction. And an inclined portion 36b. A conical surface is formed on the inner diameter side surface of the inclined portion 36b. A first outer orbit 33a on which each planetary ball 32 of the first group rolls inscribed is set on the inner peripheral surface of the conical surface. The first inner track 31a and the first outer track 33a are arranged to face each other while holding the planetary balls 32 of the first group. Note that a portion near the inner diameter of the inclined portion 36b, which is the central portion of the main body portion 36, is open, and the carrier 34 is disposed.
[0023]
The sub-part 37 has an inclined part 37a as an annular inclined plate formed substantially the same as the inclined part 36b of the main part 36, and a disk part 37b extending from the inner periphery to the center of the inclined part 37a. are doing. On the inner peripheral surface of the inclined portion 37a of the sub-part 37, a second outer orbit 33b is set, in which the second group planetary balls 32 are inscribed and rolled. The second inner track 31b and the second outer track 33b are arranged to face each other while sandwiching the planetary balls 32 of the second group. As described above, the outer tracks 33a and 33b are inclined at substantially the same angle as the first inner track 31a and the second inner track 31b with respect to the axial direction.
[0024]
Further, the circumscribed member 33 divides a chamber by both inclined portions of the sub portion 37 and the main portion 36, and the planetary ball 32 held by the carrier 34 is accommodated in the chamber. For example, when the tip of the rotating shaft 22 is disposed downward, the disc portion 37b can reliably prevent the grease or the like that lubricates the planetary ball 32 from dropping from the inside of the chamber. it can.
[0025]
Further, both the inclined portion of the main body portion 36 and the secondary portion 37 of the circumscribing member 33 is made of metal plate material to form a conical surface, circumscribing member 33 has elasticity. The circumscribed member 33 is in contact with the planetary balls 32 of each group in a state in which the restoring force due to the elasticity acts so that the inner peripheral surfaces of both inclined portions are brought closer to each other. Note that the configuration for obtaining elasticity is not limited to the above-described structure. For example, an elastic member that gives elastic force to each planetary ball 32 may be provided separately from the circumscribed member 33.
[0026]
Each part of the circumscribed member 33, for example, the inclination angle of the inclined part, the plate thickness, and the like are set so that a predetermined pressure is obtained. That is, the planetary ball 32 is sandwiched between the circumscribed member 33 and the sun roller 31 while receiving the restoring force by the circumscribed member 33 as described above. In a state where no axial load is applied to the circumscribed member 33, the applied pressures act on the planetary balls 32 of the first group and the second group in a balanced manner, and accordingly, the relative relationship between the circumscribed member 33 and the sun roller 31 is increased. The position becomes a neutral position, and at this time, a predetermined amount of applied pressure is obtained.
[0027]
Next, the operation of the planetary ball type transmission 1 will be described.
[0028]
The planetary ball type transmission 1 can be used as a power transmission device in which the sun roller 31 is fixed to the rotating shaft 22 of the motor 2 and the circumscribed member 33 is an output member. When the motor 2 is driven, the sun roller 31 rotates, and a plurality of planetary balls 32 roll on the inner tracks 31a and 31b. At this time, the carrier 34 does not rotate, and the circumscribed member 33 that circumscribes the planetary ball 32 rotates.
[0029]
The sun roller 31 can support the circumscribed member 33 in the radial direction and the axial direction via the planetary ball 32.
[0030]
In this state, when no axial load is applied to the circumscribed member 33, an appropriate pressure is applied to each planetary ball 32 as described above.
[0031]
Further, when an axial load is applied to the circumscribed member 33 in a direction from the root of the rotating shaft 22 to the distal end (direction of the distal end in the axial direction), the first outer track 33 a and the first group of the first group It is received by the bearing of the motor 2 through the planetary ball 32 and the first inner track 31a. This load acts so as to widen the inner diameter portion of the inclined portion 36b of the main body 36, and the elastic restoring force accompanying this acts to move the circumscribed member 33 in the direction opposite to the load. Further, the pair of inner tracks is formed on the sun roller 31 and the pair of outer tracks is formed on the circumscribed member 33, and the relative positions of the inner tracks and the outer tracks are regulated. Further, the pressure applied to the planetary balls 32 of the first group and the second group is balanced with each other. As a result, even if a load is applied toward the tip in the axial direction, and a relative position shift between the circumscribed member 33 and the sun roller 31 occurs, a force for returning the shift is generated, thereby preventing the relative position shift. . Therefore, the applied pressure applied to each planetary ball 32 of the first group and the applied pressure applied to each planetary ball 32 of the second group can be kept substantially constant, and an appropriate applied pressure can be obtained to achieve stable power. Communication can be realized.
[0032]
Further, when the load is in the direction opposite to the tip end in the axial direction (toward the root), the motor 2 is connected via the second outer track 33b, each planetary ball 32 of the second group, and the second inner track 31b. It is received by a bearing. At this time, the load directed toward the root acts to widen the portion closer to the inner diameter of the inclined portion 37a of the sub portion 37, and accordingly, the elastic restoring force of the inclined portion 37a moves the circumscribed member 33 in the direction opposite to the load. It works to let you. As a result, as in the case where a load directed to the tip is applied, the displacement of the relative position between the circumscribed member 33 and the sun roller 31 is prevented, and a pressure is appropriately applied to the planetary balls 32 of each group to stabilize the group. Power transmission can be realized.
[0033]
Further, when an excessive load is applied in the axial direction, the carrier 34 functions as a cage, so that the planetary ball 32 is prevented from being excessively displaced in the axial direction.
[0034]
As described above, according to the present embodiment, since the sun roller 31 supports the circumscribed member 33 in the radial direction and the axial direction via the plurality of planetary balls 32, the planetary ball type transmission 1 as a power transmission device is used. The bearing function can be combined. For example, a dedicated bearing for supporting the circumscribed member 33 in the axial direction, a member for holding the bearing, and the like can be omitted, and the structure of the planetary ball type transmission 1 can be simplified.
[0035]
Further, the circumscribed member 33 may support the sun roller 31 in the radial direction and the axial direction via the plurality of planetary balls 32. In this way, one of the sun roller 31 and the circumscribed member 33 can support the other in the radial direction and the axial direction through the plurality of planetary balls 32, and the power transmission device can have a bearing function. Can be simplified.
[0036]
Further, since it is supported through the planetary ball 32 in the axial direction, the load in the axial direction can be converted into a pressure applied to the planetary ball 32 for power transmission, and the pressure applied is reduced due to the load in the axial direction. Therefore, it is possible to prevent the power transmission from being hindered and to stabilize the power transmission. In particular, since the inner track and the outer track are inclined surfaces, an axial load can be reliably converted into a pressure.
[0037]
In addition, the pair of inner tracks of the sun roller 31 and the pair of outer tracks of the circumscribed member 33 are opposed to each other and incline in opposite directions and receive loads in opposite directions in the axial direction via the planetary ball groups. At the same time, since the axial loads in any direction can be balanced with each other by the first group and the second group of planetary balls 32, the relative position between the circumscribed member 33 and the sun roller 31 can be set at a predetermined pressure. Can be maintained at a position where the pressure can be obtained, and a stable pressure can always be obtained. As a result, stable power transmission can be achieved.
[0038]
Moreover, the circumscribing member 33, since the elastic member for applying pressure given to the inclined portions 36b, 37a Tona Ri each planetary ball 32 to form a conical surface, its elastic restoring force, the circumscribing member 33 An appropriate pressure is obtained by acting on the circumscribed member 33 so that the relative position to the sun roller 31 is an appropriate position. As described above, a constant pressure can be obtained by the elasticity of the circumscribed member 33, so that more stable power transmission can be realized. Further, it is not necessary to separately provide an elastic member for applying a pressure, and the structure can be further simplified.
[0039]
In the above-described embodiment, the circumscribed member 33 has elasticity, but may be configured by a rigid body. In this case, when the planetary ball 32 is sandwiched between the circumscribed member 33 and the sun roller 31 at a predetermined position, a predetermined pressurizing force is obtained in a state where the planetary ball 32 is pressurized at a fixed position.
[0040]
Moreover, in the above-mentioned embodiment, although the carrier 34 was fixed, it is not limited to this. For example, the sun roller 31 or the circumscribed member 33 may be fixed, the carrier 34 may be configured to be rotatable, and the carrier 34 may be used for input / output.
[0041]
In the above-described embodiment, the axial load is received by the bearing built in the motor 2, but the present invention is not limited to this. For example, you may receive with the bearing provided in the apparatus to which this planetary ball type transmission is applied.
[0042]
Further, in the above-described embodiment, the planetary ball type transmission 1 is configured by the motor 2 and the unit, but is not limited to this. As the planetary ball type transmission, it is sufficient if the sun roller 31, the planetary ball 32, the carrier 34, and the circumscribed member 33 are provided.
[0043]
In addition, various design changes can be made without changing the gist of the present invention.
[0044]
【The invention's effect】
According to the first aspect of the present invention, since one of the sun roller and the circumscribed member supports the other in the axial direction via a plurality of planetary balls, the power transmission device can also have a bearing function. It can be omitted and the structure can be simplified. In addition, power transmission can be stabilized using an axial load.
[0045]
In addition, each of the planetary ball groups is subjected to loads opposite to each other in the axial direction, and a stable applied pressure is always obtained to achieve stable power transmission.
[Brief description of the drawings]
FIG. 1 is a front sectional view of a planetary ball type transmission according to an embodiment of the present invention.
[Explanation of symbols]
1 Planetary ball type transmission (friction type power transmission device)
2 Motor 22 Rotating shaft 31 Sun rollers 31a, 31b Inner track 32 Planetary ball 32A First planetary ball group 32B Second planetary ball group 33 Outer member 33a, 33b Outer track 34 Carrier
36 Main part (one plate, single member)
36a Disc part (contact plate)
36b Inclined part (annular inclined plate)
37 Sub-portion (the other plate, single member)
37a Inclined part (annular inclined plate)

Claims (3)

A friction type having a sun roller, a plurality of planetary balls circumscribing the outer periphery of the sun roller, a carrier for holding the planetary balls in a rollable manner, and a rotatable ring-shaped circumscribed member in which the planetary balls are inscribed In the power transmission device,
One of the sun roller and the circumscribed member supports the other of the sun roller and the circumscribed member in the axial direction via a plurality of planetary balls,
The planetary ball includes a first planetary ball group and a second planetary ball group,
The sun roller has a pair of inner orbits composed of conical surfaces inclined in opposite directions along the axial direction, and each inner orbit comes into contact with a corresponding planetary ball group,
The circumscribed member includes a pair of elastically deformable annular inclined plates inclined in opposite directions to each other,
The inner peripheral surfaces of the pair of annular inclined plates each include a conical surface, and the conical surfaces of the pair of annular inclined plates form a pair of outer orbits respectively opposed to the corresponding inner orbits across the corresponding planetary ball group. ,
The circumscribed member has a resilience that causes an elastic restoring force to act so as to bring the pair of outer tracks closer to each other. In the friction type power transmission device according to claim 1,
The friction-type power transmission device, wherein the circumscribed member includes a pair of contact plates that extend from the pair of annular inclined plates and are abutted and fixed to each other. In the friction type power transmission device according to claim 2,
The circumscribed member is formed by integrally forming one contact plate and one annular inclined plate with a single member, and the other contact plate and the other annular inclined plate with a single member. A friction type power transmission device comprising a combination with the other plate member formed.

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