Friction gear

Abstract

The present application provides a kind of friction gear (100), it has the contact between the friction transmission body (20) of the output component (30) and multiple friction transmission mechanism (10) by taking out output rotation and transmits power, and the contact surface of output component (30) is inclined relative to axial, the friction gear has the output component (78) for transmitting output rotation to driven device and the shaft coupling (70) of linking output component (30) and output component (78).Shaft coupling (70) is configured to be more easily deformed relative to the load on the axis than output component (30) and output component (78), and has the function of absorbing the misalignment of the shaft center between output component (30) and output component (78) and the function of transmitting torque to the output component (30) side after converting the torque acting on the output component (78) into axial force.

Description

Technical Field

[0001] This invention relates to a friction transmission device. Background Technology

[0002] Patent Document 1 describes an automatic transmission comprising: a transmission mechanism having a rolling element disposed between an input-side transmission member and an output-side transmission member; and an output-side transmission mechanism disposed between the output-side transmission member and an output shaft. The transmission mechanism is configured such that the rolling element rotates on its own axis and revolves around a central axis based on a rotational force from the input-side transmission member, and transmits the rotational component of the rolling element to the output-side transmission member. The output-side transmission mechanism comprises an engagement recess formed in the output-side transmission member, an engagement recess formed in the output shaft, and a plurality of engagement balls existing between these engagement recesses. The rotation transmitted to the output-side transmission member is transmitted to the output shaft via the plurality of engagement balls.

[0003] Previous technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 63-251656 Summary of the Invention

[0006] The technical problem to be solved by the invention

[0007] In friction transmission devices, if external loads such as tilting torque, radial load, and axial load are applied to the output section, the posture of the output-side components of the transmission mechanism will change, which will lead to changes in the transmission characteristics of the transmission mechanism. From the viewpoint of obtaining stable transmission characteristics, it is desirable to reduce the influence of external loads on the transmission mechanism. However, the automatic transmission described in Patent Document 1 cannot adequately address this viewpoint.

[0008] The present invention was made in view of such a problem, and its object is to provide a friction transmission device that can reduce the influence of external loads.

[0009] means for solving technical problems

[0010] To address the aforementioned issues, one embodiment of the present invention provides a friction drive mechanism that transmits power through contact between a take-up component that outputs rotation and a plurality of friction drive bodies. The contact surface of the take-up component is inclined relative to the axial direction. The friction drive mechanism includes an output component for transmitting output rotation to a driven device and a coupling connecting the take-up component and the output component. The coupling is configured to deform more readily than the take-up component and the output component under axial loads, and has the function of absorbing misalignment of the axes between the take-up component and the output component, and of converting the torque acting on the output component into an axial force and transmitting it to the take-up component side.

[0011] Furthermore, any combination of the above-mentioned constituent elements, or any substitution of the constituent elements or expressions of the present invention among methods, systems, etc., is also valid as a way of the present invention.

[0012] Invention Effects

[0013] According to the present invention, a friction transmission device capable of reducing the influence of external loads is provided. Attached Figure Description

[0014] Figure 1 This is a front view that schematically shows an example of a friction drive device according to an embodiment.

[0015] Figure 2 It means Figure 1 A cross-sectional view of the friction drive device taken along line AA.

[0016] Figure 3 It is a general representation Figure 1 The main view of the output side mechanism.

[0017] Figure 4 It means Figure 3 A sectional view of the output side mechanism along line BB.

[0018] Figure 5 It means Figure 3 A cross-sectional view of the output side mechanism along the CC line.

[0019] Figure 6 It means Figure 1 A diagram illustrating the absorption action of shaft misalignment in the output-side mechanism.

[0020] Figure 7 It means Figure 1 A diagram illustrating the absorption action of shaft misalignment in the output-side mechanism.

[0021] Figure 8 It is a schematic representation Figure 1 A schematic diagram of the fitting recess and fitting components of the output side mechanism.

[0022] Figure 9 It is used for explanation Figure 1 A diagram illustrating the operation of a friction drive mechanism.

[0023] Figure 10 It is used for explanation Figure 1 A diagram illustrating the vector at the contact point of the friction drive. Detailed Implementation

[0024] The present invention will now be described in summary. The inventors have studied friction transmission devices and obtained the following insights. A friction transmission device can be considered that includes: a friction transmission mechanism having a contact surface inclined relative to the axial direction, and a take-out member for taking out output rotation through contact between the contact surface and a plurality of friction transmission bodies; an output member for transmitting output rotation to a driven device; and a coupling connecting the take-out member and the output member. The inventors have found that in this friction transmission device, the magnitude of the external load acting on the output member and the transmitted torque affects the characteristics of the friction transmission mechanism.

[0025] First, the influence of external loads is explained. External loads such as tilting moment, radial load, and axial load can be considered to act on the output component connected to the extraction component. If these external loads act on the output component, it will cause displacement or deformation, resulting in misalignment of the extraction component connected to it. If the extraction component misaligns, the contact load borne by each of the multiple friction transmission elements will become uneven. In areas where the contact load between the friction transmission element and each raceway is too large, metal fatigue will increase, leading to a shortened lifespan. Furthermore, in areas where the contact load is too small, idling will occur, causing uneven transmission characteristics of the friction drive mechanism.

[0026] From the perspective of reducing misalignment of the extraction component, it is important that the coupling is configured to deform more easily with respect to axial loads than the extraction and output components. By making the coupling easily deformable, when a tilting moment acts on the output component, the effect of the tilting moment is absorbed by elastic deformation such as deflection of the coupling, thus reducing the impact on the extraction component.

[0027] Furthermore, from the same perspective, it is important that the coupling has the function of absorbing the misalignment of the shafts between the take-up component and the output component (hereinafter referred to as "shaft misalignment absorption function"). At this time, since the shaft misalignment between the take-up component and the output component is absorbed by the coupling, the impact of shaft misalignment on the take-up component can be reduced.

[0028] Next, the influence of the magnitude of the transmitted torque will be explained. The magnitude of the pressure load applied between the friction transmission body and the extraction component has the following effects on the efficiency, torque capacity, lifespan, and other characteristics of the friction drive device.

[0029] (1) If the pressure load is large, the upper limit of the transmitted torque will increase, but the transmission efficiency will decrease and the lifespan will be shortened.

[0030] (2) If the pressure load is small, the upper limit of the transmitted torque will be smaller, but the transmission efficiency will be higher and the lifespan will be increased.

[0031] From the perspective of ensuring transmission efficiency and lifespan, it is preferable to appropriately set the pressure load according to the magnitude of the transmitted torque. However, the adjustment of the pressure load is usually performed with the same precision as rolling bearings, down to the micrometer level, making it difficult to fine-tune the pressure load to the desired load. Furthermore, in applications where the transmitted torque varies over a wide range, it is advisable to set the pressure load based on the maximum value of the transmitted torque. In this case, if operation is carried out with a low transmitted torque, efficiency and lifespan will decrease compared to the case where a pressure load suitable for a low torque is applied.

[0032] Therefore, in order to automatically adjust the pressure load according to the magnitude of the transmitted torque, it is important that the coupling has the function of converting the torque acting on the output component into an axial force and then transmitting it to the take-out component (hereinafter referred to as the "torque-pressure conversion function"). At this time, since the transmitted torque acting on the output component is converted into an axial force by the coupling and transmitted to the take-out component, when the transmitted torque is small, the contact load (pressure load) between the friction drive and the take-out component decreases, thereby suppressing the decline in efficiency and lifespan. Furthermore, when the transmitted torque is large, the contact load (pressure load) between the friction drive and the take-out component increases, thereby compensating for insufficient transmitted torque capacity.

[0033] The aforementioned shaft misalignment absorption function or torque compression conversion function can be implemented through various structures. Hereinafter, an example structure will be described in detail with reference to an embodiment.

[0034] Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments and variations, the same or equivalent constituent elements and components are labeled with the same symbols, and repeated descriptions are omitted where appropriate. Furthermore, in each drawing, the dimensions of the components are appropriately enlarged or reduced for ease of understanding. Also, in each drawing, parts of components that are not important to the description of the embodiments are omitted.

[0035] Furthermore, terms containing designations such as first and second are used to describe various constituent elements, but these terms are only used to distinguish one constituent element from other constituent elements and are not used to limit the constituent elements.

[0036] [Implementation Method]

[0037] refer to Figure 1 and Figure 2 The structure of the friction transmission device 100 according to the embodiments of the present invention will be described. Figure 1 This is a front view that schematically shows an example of the friction transmission device 100 according to this embodiment. Figure 2This is a schematic cross-sectional view of the friction drive device 100. Figure 2 Indicates along Figure 1 The cross section cut by line AA.

[0038] The friction drive device 100 of this embodiment includes a friction drive mechanism 10 and an output side mechanism 80. The friction drive mechanism 10 transmits the input power through the contact of multiple friction drive bodies and the take-up member. The output side mechanism 80 transmits the output rotation from the take-up member to the driven device (not shown). In particular, the output side mechanism 80 includes the take-up member, the output member, and the coupling connecting them, thereby reducing the influence of external loads acting on the output member from the driven device on the take-up member. First, the friction drive mechanism 10 will be described, and the output side mechanism 80 will be described later.

[0039] (Friction transmission mechanism)

[0040] In the friction drive mechanism 10, the take-out component has a friction surface (also known as a track surface) of the friction drive body. This friction surface is not necessarily a cylindrical surface; any surface inclined relative to the central axis is acceptable. The friction drive mechanism 10 of this embodiment is a mechanism that transmits the rotation input from the motor 50 to the output side mechanism 80 after speed change. Specifically, the friction drive mechanism 10 is configured such that rotating the input ring causes the friction drive body to rotate and revolve, and outputs the resulting rotational component to the take-out component.

[0041] The friction transmission mechanism 10 mainly includes an input shaft 12, an input sleeve 14, an input shaft bearing 18, a friction transmission body 20, a first support sleeve 26, a second support sleeve 28, and a take-out component 30. Hereinafter, the direction along the central axis La of the input shaft 12 will be referred to as the "axial direction," and the circumferential and radial directions of the circle centered on this central axis La will be referred to as the "circumferential direction" and "radial direction," respectively. Furthermore, for ease of explanation, the side along the axial direction (right side in the figure) will be referred to as the input side, and the other side along the axial direction (left side in the figure) will be referred to as the opposite input side.

[0042] If the motor 50 provides rotational input, the input shaft 12 rotates around its central axis La. In this embodiment, the input shaft 12 is a cylindrical component extending axially. An input ring 14 is fixed to the outer circumference of the input shaft 12, allowing it to rotate integrally. The input side of the input shaft 12 is connected to the inner ring of the input shaft bearing 18. The outer ring of the input shaft bearing 18 supports a first support ring 26. The first support ring 26 surrounds the input shaft 12 with a gap. The input shaft 12 and the first support ring 26 are configured to rotate relative to each other.

[0043] The input end of the input shaft 12 is connected to the relative position changing mechanism 60, which will be described later. The input shaft 12 is axially moved by the relative position changing mechanism 60. The rotor 52 of the motor 50 surrounds the outer periphery of the input side of the input shaft 12. The input shaft 12 is axially movably supported on the rotor 52. The spline groove 12s provided on the outer peripheral surface of the input shaft 12 and the spline groove 51s provided on the inner peripheral surface of the rotor 52 engage with each other with a gap between them.

[0044] In this embodiment, the friction drive 20 functions as a planetary rolling element that transmits rotation while performing planetary motion between the input ring 14 and the output member 30. The input ring 14 rotates integrally with the input shaft 12 about the central axis La. The input ring 14 contacts the friction drive 20, and the friction drive 20 rotates and revolves as the input ring 14 rotates. The input ring 14 may also be formed separately from the input shaft 12, but in this example, the input ring 14 is formed integrally with the input shaft 12. The input ring 14 is a generally disk-shaped component and has a rolling surface 14h on its input-opposite side. The rolling surface 14h is the surface on which the friction drive 20 rolls, and it is in substantially point contact with the friction drive 20. The rolling surface 14h is inclined relative to the axial and radial directions. The rolling surface 14h includes a tapered surface that tapers towards the input-opposite side. The rolling surface 14h may also be a convex or concave surface, but in this example, it is a flat surface.

[0045] An input shaft bearing 18 is disposed between the input end of the input shaft 12 on the opposite side of the input and the first support ring 26. The type of bearing is not particularly limited, but in this embodiment, the input shaft bearing 18 is a rolling bearing with spherical rolling elements. The input shaft bearing 18 has an inner ring mounted on the input shaft 12 and an outer ring fixed to the first support ring 26.

[0046] The first support ring 26 and the second support ring 28 maintain the posture and position of the friction drive body 20 within a certain range. The first support ring 26 and the second support ring 28 are configured to be separately arranged and opposite each other, separated by the friction drive body 20. The first support ring 26 is located on the opposite side of the input of the second support ring 28 and radially inward.

[0047] The first support ring 26 has an annular shape surrounding the input shaft 12 with a gap. The first support ring 26 has a rolling surface 26h on the input side. The rolling surface 26h is the surface for the friction drive body 20 to roll, and it is in substantial point contact with the friction drive body 20. The rolling surface 26h is inclined relative to the axial and radial directions. The rolling surface 26h includes a tapered surface that tapers towards the input side. The rolling surface 26h can also be a convex or concave surface, but in this example it is a flat surface. The first support ring 26 is free to rotate relative to the input shaft 12 and the friction drive body 20, and is sometimes referred to as a free-spinning ring.

[0048] The second support ring 28 has an annular shape surrounding the input shaft 12 and the friction drive body 20. The second support ring 28 has a rolling surface 28h on the opposite side of the input. The rolling surface 28h is the surface for the friction drive body 20 to roll, and it is in substantial point contact with the friction drive body 20. The rolling surface 28h is inclined relative to the axial and radial directions. The rolling surface 28h includes a tapered surface that tapers towards the input side. The rolling surface 28h can also be a convex or concave surface, but in this example it is a flat surface. The rolling surface 28h of the second support ring 28 is substantially opposite to the rolling surface 26h of the first support ring 26, and the friction drive body 20 is sandwiched between the rolling surface 28h of the second support ring 28 and the rolling surface 26h of the first support ring 26.

[0049] The second support collar 28 is fixed to the inner circumferential side of the second housing 42, which will be described later. The second support collar 28 may also be formed separately from the second housing 42, but in this example, it is formed integrally with the second housing 42.

[0050] The extraction component 30 contacts the friction drive 20 and rotates about its central axis as the friction drive 20 rotates. In this example, the axis of rotation of the extraction component 30 coincides with the central axis La, therefore the extraction component 30 rotates about the central axis La. The extraction component 30 is connected to the output component 78 via a coupling 70, and both the coupling 70 and the output component 78 rotate as the extraction component 30 rotates.

[0051] The extraction component 30 has an annular shape surrounding the input shaft 12 and the friction drive 20. The extraction component 30 has a rolling surface 30h on the input side, thus functioning as an output ring. The rolling surface 30h is the surface from which the friction drive 20 rolls, and it makes substantial point contact with the friction drive 20. The rolling surface 30h is inclined relative to the axial and radial directions. The rolling surface 30h includes a tapered surface that tapers towards the opposite side of the input. The rolling surface 30h can also be a convex or concave surface, but in this example it is a flat surface. The rolling surface 30h of the extraction component 30 is substantially opposite to the rolling surface 14h of the input ring 14, and the friction drive 20 is sandwiched between the rolling surface 30h of the extraction component 30 and the rolling surface 14h of the input ring 14.

[0052] Multiple friction drive elements 20 are arranged circumferentially at predetermined intervals (e.g., 6). A cage could be provided to hold the multiple friction drive elements 20 in a desired position, but in this embodiment, no cage is provided. The structure without a cage is advantageous in terms of manufacturing cost, device size, and device weight. Furthermore, the number of friction drive elements 20 is not particularly limited; it can be less than 6 or more than 6, preferably 6 to 12.

[0053] Hereinafter, the rolling surface 30h of the take-out component 30, the rolling surface 14h of the input sleeve 14, the rolling surface 26h of the first support sleeve 26, and the rolling surface 28h of the second support sleeve 28 will be collectively referred to as "rolling surface".

[0054] The friction drive body 20 is in contact with four rolling surfaces, thus restricting its axial position, radial position, and orientation. The shape of the friction drive body 20 can be any shape, as long as it contacts the four rolling surfaces, thus determining its orientation and enabling simultaneous rolling with all four rolling surfaces. In this embodiment, the friction drive body 20 is a body of revolution (hereinafter referred to as a "long sphere") obtained by rotating an ellipse or a long circle around its minor axis. Furthermore, in this specification, the circle formed by the intersection of a plane passing through the center of the minor axis of the friction drive body 20 and orthogonal to the rotation axis Lb with the outer peripheral surface of the friction drive body 20 is called the "equator." In this example, the equator is a great circle formed by the intersection of a plane orthogonal to the rotation axis Lb and the outer peripheral surface of the friction drive body 20.

[0055] The inclination of the rotation shaft Lb of the friction drive 20 relative to the central axis La varies depending on the relative positions of the four rolling surfaces. That is, the rotation shaft Lb can be parallel to the central axis La or inclined relative to the central axis La.

[0056] The ratio Ra (axial dimension / radial dimension) of the friction drive 20 when its rotation axis Lb is parallel to the central axis La will be explained. If the ratio Ra is large, the friction drive 20 may rotate around a simulated rotation axis orthogonal to the original rotation axis Lb. From the viewpoint of suppressing this phenomenon, the ratio Ra is preferably 1 or less, more preferably 0.8 or less, and even more preferably 0.6 or less. The ratio Ra can be set to 0.1 or more.

[0057] (Output side mechanism)

[0058] refer to Figures 3-5 The output-side mechanism 80 will be described below. Figure 3 This is a general front view showing the output-side mechanism 80. Figure 4 It means along Figure 3 A sectional view of the output side mechanism 80 cut by the BB line. Figure 5 It means along Figure 3 A cross-sectional view of the output-side mechanism 80, cut along the CC line. The output-side mechanism 80 has an output component 78 for transmitting output rotation to the driven device, and a coupling 70 connecting the take-out component 30 and the output component 78.

[0059] Next, the output component 78 will be described. The output component 78 is connected to the take-out component 30 via a coupling 70 and rotates as the take-out component 30 rotates. The output component 78 is sometimes referred to as an output flange. In this example, the output component 78 has a generally disc-shaped shape and is rotatably supported on the first housing 40 via a main bearing 34, described later. A driven device is connected to the input side of the output component 78.

[0060] Next, the coupling 70 will be described. The coupling of this embodiment has the following structure: the take-out member 30 can be moved along a first direction orthogonal to the axial direction, and the output member 78 can be moved along a direction orthogonal to the axial direction but different from the first direction.

[0061] The coupling 70 of this embodiment includes a coupling body 72, a first coupling recess 74d, a second coupling recess 76d, a first fitting member 74, and a second fitting member 76. In this example, the coupling body 72 is a disc-shaped component. The first coupling recess 74d is provided on the input side of the coupling body 72, and the second coupling recess 76d is provided on the opposite side of the input of the coupling body 72. The first fitting member 74 is fitted into the first coupling recess 74d and the extraction member recess 30d provided on the opposite side of the input of the extraction member 30, and has a gap between itself and the first coupling recess 74d and the extraction member recess 30d in a first direction. The second fitting member 76 is fitted into the second coupling recess 76d and the output member recess 78d provided on the input side of the output member 78, and has a gap between itself and the second coupling recess 76d and the output member recess 78d in a second direction.

[0062] Hereinafter, the first fitting component 74 and the second fitting component 76 will be collectively referred to as "fitting components". Furthermore, the first coupling recess 74d, the second coupling recess 76d, the take-out component recess 30d, and the output component recess 78d will be collectively referred to as "fitting recesses".

[0063] Next, the deformability of the coupling 70 will be explained. The coupling body 72 is configured to easily flex axially, thus absorbing axial misalignment. As an example, the coupling body 72 can be made of a material with a lower Young's modulus than that of the take-up member 30 and the output member 78 to facilitate flexure. For example, if the take-up member 30 and the output member 78 are made of ferrous metals, the coupling body 72 can be made of a metal such as aluminum or a resin material with a lower Young's modulus than that of ferrous metals. In this embodiment, the coupling body 72 is formed so that its axial dimension is smaller than that of the take-up member 30 and the output member 78 to facilitate flexure. Regarding the comparison of the axial dimensions between the components, for example, the maximum value of the axial dimension can be compared, or the minimum value can be compared, or both can be compared. Furthermore, the average value or intermediate value of the axial dimension can also be compared. The axial dimension of the coupling body 72 can be set according to the desired deformability through simulation tests or experiments.

[0064] Furthermore, since the coupling body 72 is configured to easily flex axially, it functions as a spring that flexes axially. By using the coupling body 72 as a spring, the pressure load acting on the removal component 30 can be adjusted. At this time, pressure changes caused by the thermal expansion of each component can be mitigated.

[0065] Next, the axial misalignment absorption function of this embodiment will be described. Multiple first fitting members 74 are provided at positions offset from the central axis La and spaced at predetermined intervals. In this embodiment, two first fitting members 74 are separately arranged in a first direction orthogonal to the axial direction and symmetrically arranged with respect to the central axis La. The two first fitting members 74 are rollers having a cylindrical surface with its center along the first direction.

[0066] The second fitting members 76 are disposed at positions offset from the central axis La and are arranged in multiples at predetermined intervals. In this embodiment, the two second fitting members 76 are arranged separately in a second direction orthogonal to the axial direction and are symmetrically arranged with respect to the central axis La. The two second fitting members 76 are rollers having a cylindrical surface centered along the second direction. When viewed from the axial direction, the first direction and the second direction intersect each other, and in this example, they are orthogonal to each other.

[0067] The first fitting member 74 fits into the first coupling recess 74d and the extraction member recess 30d and has a gap between it and the first coupling recess 74d and the extraction member recess 30d in a first direction. As an example, regarding the dimension in the first direction, the first fitting member 74 is configured to be smaller than the first coupling recess 74d and the extraction member recess 30d by an amount corresponding to the gap.

[0068] The second fitting member 76 fits into the second coupling recess 76d and the output member recess 78d and has a gap between it and the second coupling recess 76d and the output member recess 78d in the second direction. As an example, regarding the dimension in the second direction, the second fitting member 76 is configured to be smaller than the second coupling recess 76d and the output member recess 78d by an amount corresponding to the gap.

[0069] refer to Figure 6 and Figure 7 The shaft misalignment absorption action of the output side mechanism 80 is explained. Figure 6 and Figure 7 This is an explanatory diagram used to illustrate the operation of the output-side mechanism 80. Figure 6 This indicates the absorption action of shaft misalignment in the first direction of the output-side mechanism 80. Figure 7 This indicates the absorption action of axial misalignment in the second direction of the output side mechanism 80. Figure 6 In (a), it indicates that the center Lc of the coupling body 72 is misaligned relative to the central axis La of the take-out component 30 in the first direction toward the direction of the hollow arrow. Figure 6In diagram (b), the center Lc of the coupling body 72 is misaligned relative to the central axis La in the first direction toward the hollow arrow. Thus, since there is a gap in the first direction between the first fitting member 74 and the first coupling recess 74d and the extraction member recess 30d, the misalignment in the first direction can be absorbed by utilizing the gap between them.

[0070] Figure 7 In (a), it indicates that the center Lp of the output component 78 is misaligned relative to the center Lc of the coupling body 72 in the second direction toward the direction of the hollow arrow. Figure 7 In diagram (b), the center Lp of the output component 78 is misaligned relative to the center Lc in the second direction toward the hollow arrow. Thus, since there is a gap in the second direction between the second fitting component 76 and the second coupling recess 76d and the output component recess 78d, the misalignment in the second direction can be absorbed using this gap. Because the misalignment can be absorbed in the intersecting first and second directions, the coupling 70 can absorb misalignment between the output component 78 and the take-off component 30. The amount of gap in the first and second directions can be set according to the desired amount of misalignment absorption through simulation or experimentation.

[0071] refer to Figure 8 The torque-pressure conversion function of the output-side mechanism 80 is explained. Figure 8 This is an explanatory diagram schematically showing the fitting recess and fitting component when viewed radially. In this explanation, as an example of a fitting recess, the first coupling recess 74d and the take-out component recess 30d are shown, and as an example of a fitting component, the first fitting component 74 is shown, but this explanation is equally applicable to other fitting recesses and fitting components.

[0072] like Figure 8 As shown, the first coupling recess 74d and the take-out component recess 30d are recessed last in the circumferential direction at their central points, forming a V-shaped groove when viewed radially. That is, these fitting recesses have a first inclined surface 70p and a second inclined surface 70s connected to each other at their central points in the circumferential direction. The first inclined surface 70p and the second inclined surface 70s are surfaces inclined relative to a surface orthogonal to the axial direction. The cylindrical surface 74e of the first fitting component 74 contacts the first inclined surface 70p and the second inclined surface 70s. When referring collectively to the first inclined surface 70p and the second inclined surface 70s, they are sometimes simply referred to as inclined surfaces.

[0073] For example, when the transmitted torque T acts on the extraction component 30, causing the first inclined surface 70p to abut against the cylindrical surface 74e, the first inclined surface 70p applies a force to the cylindrical surface 74e in the rotational direction based on the transmitted torque T. At this time, the cylindrical surface 74e applies a force Fa in the opposite rotational direction to the first inclined surface 70p as a reaction force. Based on the force Fa in the opposite rotational direction, an axial component force Fb is generated on the first inclined surface 70p. The axial component force Fb is a force that pushes the extraction component 30 towards the friction drive body 20, which increases their pressure load.

[0074] Furthermore, between the first fitting member 74 and the first coupling recess 74d, a force in the direction of increasing pressure load also acts on the first fitting member 74 based on the reaction force of the transmitted torque T. It can be considered that the axial component force Fb is proportional to the transmitted torque T; therefore, the axial component force Fb increases as the transmitted torque T increases and decreases as the transmitted torque T decreases. Thus, the pressure load can be well adjusted according to the transmitted torque T. The inclination angles of the first inclined surface 70p and the second inclined surface 70s relative to the surface orthogonal to the axial direction can be set according to the desired torque-pressure conversion characteristics through simulation or experimentation.

[0075] Furthermore, the external torque acting on the output component 78 from the outside applies a force in the opposite direction of rotation to the first inclined surface 70p via the second fitting component 76, the coupling body 72, and the first fitting component 74. Since this force overlaps with the force Fa and its component Fb in the opposite direction of rotation, the force pushing the extraction component 30 towards the friction drive body 20 can be increased. That is, when an external torque is applied, the pressure load also increases.

[0076] In the example above, a first coupling recess 74d and a second coupling recess 76d are shown on the coupling body 72, but it is not necessary to have these recesses. For example, one or both of the first fitting member 74 and the second fitting member 76 can be integrally formed with the coupling body 72. In this case, the flexibility of the coupling 70 can be ensured while achieving the functions of shaft misalignment absorption and torque compression conversion.

[0077] Next, refer to Figure 2 The other structures of the friction drive device 100 will be described below. The friction drive device 100 also includes a main bearing 34, an oil seal 36, and first and second housings 40 and 42.

[0078] (Main bearing)

[0079] like Figure 2As shown, the main bearing 34 is disposed between the output component 78 and the first housing 40, supporting the output component 78 so that it can rotate relative to the first housing 40. The type of bearing is not particularly limited, but in this embodiment, the main bearing 34 is a crossed roller bearing with cylindrical rollers as rolling elements. The inner ring of the main bearing 34 is integrally formed with the output component 78, and the outer ring of the main bearing 34 is integrally formed with the first housing 40.

[0080] (Oil seal)

[0081] like Figure 2 As shown, the oil seal 36 is disposed on the opposite side of the input of the main bearing 34 between the output component 78 and the first housing 40. The oil seal 36 suppresses leakage of lubricant from the main bearing 34 and reduces the intrusion of foreign matter into the main bearing 34.

[0082] (shell)

[0083] like Figure 2 As shown, the first and second housings 40 and 42 are hollow, generally cylindrical components and function as the housings of the friction drive device 100. The first and second housings 40 and 42 include: a first housing 40 mainly surrounding the output component 78; and a second housing 42 connected to the input side of the first housing 40 and mainly surrounding the coupling 70 and the friction drive mechanism 10. The first housing 40 is connected to the second housing 42 by bolt B2. A second support ring 28 is provided on the inner circumference of the second housing 42. A flange 42f is provided on the outer circumference of the second housing 42. The flange 42f is connected to the motor housing 54 (described later) by bolt B1, thereby connecting the second housing 42 to the motor 50.

[0084] (motor)

[0085] Next, refer to Figure 2 The motor 50 will now be described. The type of motor 50 is not particularly limited, but in this embodiment, the motor 50 is an internal rotor type brushless motor with a motor shaft 51. The motor 50 mainly includes a motor shaft 51, a rotor 52, a stator 53, a motor housing 54, a first housing portion 56, a second housing portion 57, and a pair of motor bearings 58. The motor shaft 51 is a hollow shaft having a hollow portion 51c for advancing and retracting the linear motion shaft 66 (described later). The motor shaft 51 is supported by a pair of axially separated motor bearings 58 on the first housing portion 56 and the second housing portion 57. The rotor 52 has a main body portion 52b integrally formed on the outer periphery of the motor shaft 51 and a cylindrical magnet 52m fixed to the outer periphery of the main body portion 52b and having predetermined magnetic poles.

[0086] The stator 53 has a stator core 53s opposite to the magnet 52m and separated from the magnet 52m by a magnetic gap, and an armature winding 53c disposed on the stator core 53s. The motor housing 54 is a cylindrical component fixed to the outer periphery of the stator core 53s. The first cover portion 56 is a disc-shaped component that closes the input-opposite side of the motor housing 54. The second cover portion 57 is a disc-shaped component that closes the input side of the motor housing 54. The first cover portion 56, the motor housing 54, and the second cover portion 57 are integrated by bolt B1 and connected to the flange portion 42f.

[0087] (Relative position changing mechanism)

[0088] Next, refer to Figure 2 The relative position changing mechanism 60 will be described below. The friction drive device 100 of this embodiment also includes a relative position changing mechanism 60. The relative position changing mechanism 60 is a mechanism for changing the relative positions of the input collar 14, the extraction component 30, the first support collar 26, and the second support collar 28. The relative position changing mechanism 60 only needs to be able to change the relative position between one or more of these four collars and the remaining collars. The relative position changing mechanism 60 of this embodiment includes a moving mechanism 62 that causes the input collar 14 and the first support collar 26 to move axially relative to each other integrally.

[0089] The moving mechanism 62 is a linear actuator, which has a linear motion shaft 66 that moves back and forth within the hollow portion 51c of the motor shaft 51 and an actuator body 64 that generates an axial driving force on the linear motion shaft 66. The linear motion shaft 66 has a circular rod shape that extends axially. A portion of the actuator body 64 is housed within the hollow portion 51c of the motor shaft 51. The structure of the moving mechanism 62 is not particularly limited as long as it can drive the linear motion shaft 66 forward and backward. For example, the linear motion shaft 66 can be driven by a stepper motor or moved axially rather than rotated by a voice coil motor or the like. In this embodiment, the moving mechanism 62 uses a ball screw mechanism to convert rotational motion into linear motion, thereby driving the linear motion shaft 66 to move axially.

[0090] An extension 62f is provided on the actuator body 64, extending radially outward. The extension 62f is fixed to the second cover portion 57 by bolt B3, thereby connecting the actuator body 64 and the motor 50 together.

[0091] A connecting hole 12h, recessed towards the opposite side of the input shaft 12, is provided at the end of the input side. The front end of the linear motion shaft 66 is accommodated in the connecting hole 12h. A connecting bearing 68 is provided between the linear motion shaft 66 and the connecting hole 12h. The outer ring of the connecting bearing 68 is fixed to the connecting hole 12h, and the inner ring of the connecting bearing 68 is fixed to the front end of the linear motion shaft 66. With this structure, the input shaft 12 and the linear motion shaft 66 are connected together in a rotatable manner. Alternatively, when the linear motion shaft 66 moves in a non-rotating state, the linear motion shaft 66 and the input shaft 12 can be connected together without using the connecting bearing 68.

[0092] If the linear motion shaft 66 moves axially, the input shaft 12 also moves axially. Consequently, the input sleeve 14 and the first support sleeve 26 move toward the input side or the opposite side, changing their relative relationship with the take-off component 30 and the second support sleeve 28. By changing their relative relationship, the gear ratio Rs of the friction transmission mechanism 10 is changed. Thus, in this embodiment, the gear ratio Rs can be changed using a simple structure that allows the input shaft 12 to move axially. Furthermore, since the linear motion shaft 66 is disposed in the hollow portion 51c of the motor shaft 51, miniaturization of the device is possible.

[0093] refer to Figure 9 The operation of the friction transmission mechanism 10 will be explained. Figure 9 This is an explanatory diagram illustrating the operation of the friction drive mechanism 10. In this diagram, each rolling surface is depicted as curved; however, the contact area where each rolling surface contacts the friction drive body 20 is flat. When the input ring 14 rotates, the friction drive body 20 rotates around its rotation axis Lb and revolves around its revolution axis. In this example, the revolution axis of the friction drive body 20 coincides with the central axis La; therefore, the central axis La will be used as the revolution axis in the following explanation.

[0094] The contact points between the friction drive body 20 and the input sleeve 14, the first support sleeve 26, the second support sleeve 28, and the take-out component 30 are respectively designated as input contact point 14c, first support contact point 26c, second support contact point 28c, and output contact point 30c. For example... Figure 9 As shown, the rotation radii of contact points 14c, 26c, 28c, and 30c are set as Rbg, Rbh, Rbm, and Rbn, respectively, and the revolution radii of contact points 14c, 26c, 28c, and 30c are set as Rg, Rh, Rm, and Rn, respectively.

[0095] When the first support ring 26 rotates freely while the second support ring 28 remains stationary without rotating, the ratio of the rotational speed ω2 of the take-off component 30 to the rotational speed ω1 of the input ring 14 (hereinafter referred to as the "gear ratio Rs") is shown in Equation 1 below.

[0096] [Formula 1]

[0097]

[0098] exist Figure 9 In its current state, the friction drive 20 has an orientation where the input side of the rotation shaft Lb is close to the central axis La. If the relative position changing mechanism 60 changes the position of the input collar 14 and the first support collar 26 toward the input side, the orientation of the friction drive 20 changes so that the input side of the rotation shaft Lb is close to the central axis La. As a result, the rotation radius and revolution radius of each contact point change, and the gear ratio Rs also changes. Thus, by changing the relative position of each collar, the orientation of the friction drive 20 can be changed, thereby changing the gear ratio Rs of the friction drive mechanism 10. Conversely, if the orientation of the friction drive 20 is kept constant, the gear ratio Rs will remain constant.

[0099] To suppress posture changes of the friction drive body 20, one example is a structure in which a shaft component is provided on the friction drive body 20 along its rotation axis Lb, and the shaft component is supported by a bearing. In this case, the friction drive body 20 is supported by the shaft component. In this embodiment, the friction drive body 20 is not supported by the shaft component, but is supported by the input collar 14, the extraction component 30, the first support collar 26, and the second support collar 28.

[0100] refer to Figure 10 The structure of the friction transmission body 20 supported by each ring will be explained. Figure 10 This is an explanatory diagram illustrating the structure of the friction drive body 20 supported by the various raceways. The diagram shows the extensions of vectors on a plane including the central axis La and the rotation axis Lb. (As shown...) Figure 10 As shown, in this embodiment, the extension of the normal vector at the contact point between the friction drive body and each raceway forms a quadrilateral. Depending on the shape of the friction drive body 20, a quadrilateral based on the extension vector will not be formed, and the posture of the friction drive body 20 will become unstable.

[0101] like Figure 10As shown, the extensions 14m, 26m, 28m, and 30m of the normal vectors at the input contact point 14c, the first support contact point 26c, the second support contact point 28c, and the output contact point 30c intersect each other to form a quadrilateral 20s. According to this structure, the posture of the friction drive body 20 is uniquely determined, and the posture of the friction drive body 20 is maintained without being supported by a shaft component. Furthermore, if the quadrilateral 20s is a convex quadrilateral (a quadrilateral without an interior angle greater than 180 degrees), the stability of the posture is further improved.

[0102] Depending on the shape of the friction drive body 20, the area of ​​the quadrilateral 20s may sometimes become too small. If the area of ​​the quadrilateral 20s becomes too small, the posture of the friction drive body 20 may become unstable. From the viewpoint of stabilizing the posture, the area of ​​the quadrilateral 20s is preferably 4% or more of the cross-sectional area of ​​the friction drive body 20, more preferably 25% or more, and even more preferably 60% or more. The area of ​​the quadrilateral 20s can be set to 15% or more of the cross-sectional area of ​​the friction drive body 20.

[0103] Depending on the shape of the friction drive body 20, the orientation of the normal vectors of the opposite sides of the quadrilateral 20s may sometimes be the same. If the orientation of the normal vectors of the opposite sides of the quadrilateral 20s is the same, the posture of the friction drive body 20 may become unstable. Therefore, in this embodiment, the normal vectors of the opposite sides of the quadrilateral are configured to be in opposite directions. Specifically, normal vector 14v and normal vector 30v are in opposite directions, and normal vector 26v and normal vector 28v are in opposite directions. At this time, since the position and orientation of the friction drive body 20 are restricted by each ring, the posture of the friction drive body 20 becomes more stable. Furthermore, if the normal vectors of two adjacent sides of the quadrilateral 20s are both directed towards the corner or both directed away from the corner, the posture becomes even more stable.

[0104] If the contact surfaces of each race and the friction drive body 20 are all flat, the contact area will increase, leading to increased mechanical losses. If the contact surfaces are all curved, the manufacturing time will increase. Therefore, in this embodiment, regarding the contact surfaces of the input contact point 14c, the first support contact point 26c, the second support contact point 28c, and the output contact point 30c, each race is a flat surface, and the surface of the friction drive body 20 opposite to each race is a curved surface. In this case, the increase in mechanical losses can be suppressed, and the manufacturing of the component becomes easier. The curved surface of the friction drive body 20 is not particularly limited, but in this example, the curved surface has an involute curve profile.

[0105] Next, the operation of the friction drive device 100 with the above-described structure will be explained. If rotational power is transmitted from the motor shaft 51 to the input shaft 12, the input ring 14 rotates around the central axis La. Through the rotation of the input ring 14, the friction drive body 20 generates rotation and revolution. The rotation of the friction drive body 20 is transmitted to the extraction member 30, which rotates at the aforementioned speed ratio Rs. The rotation of the extraction member 30 is output to the output member 78 via the coupling 70. If the relative position changing mechanism 60 changes the positions of the input ring 14 and the first support ring 26, the speed ratio Rs changes.

[0106] Next, the features of the friction drive 100 will be described. The coupling 70 of the friction drive 100 is configured to deform more easily than the extraction member 30 and the output member 78 relative to axial loads, and has the function of absorbing misalignment of the axes between the extraction member 30 and the output member 78, and of converting the torque acting on the output member 78 into an axial force and transmitting it to the extraction member side. According to this structure, it can absorb axial misalignment between the extraction member and the output member while compensating for insufficient torque transmission capacity, thus suppressing a decrease in the efficiency or lifespan of the friction drive.

[0107] Furthermore, the friction drive device 100 is configured such that the extension of the normal vector at the contact point between the friction drive body 20 and each race forms a quadrilateral. Therefore, compared to the case where the extension does not form a quadrilateral, the posture of the friction drive body 20 becomes more stable. Since the structure used to maintain the posture of the friction drive body 20 becomes simpler, manufacturing costs can be reduced.

[0108] In the friction drive device 100, the friction drive body 20 is not supported by the shaft component but by the input sleeve 14, the take-out component 30, the first support sleeve 26 and the second support sleeve 28, thus reducing the manufacturing cost of the shaft component and its supporting components.

[0109] The embodiments of the present invention have been described in detail above. These embodiments are merely specific examples for implementing the present invention. The descriptions of these embodiments are not intended to limit the technical scope of the present invention; various design changes, such as alterations, additions, and deletions of constituent elements, are possible without departing from the inventive concept defined in the technical solution. In the above embodiments, the content enabling such design changes is described using phrases such as "in the embodiment" or "in the embodiment," but this does not mean that the absence of such phrases precludes design changes. Furthermore, the shaded lines marked on the cross-sections of the accompanying drawings are not intended to limit the material of the objects marked with shaded lines.

[0110] The following describes modified examples. In the accompanying drawings and descriptions of the modified examples, the same or equivalent components and parts are labeled with the same symbols as those in the embodiment. Descriptions that are repeated in the embodiment are omitted where appropriate, and the focus is on describing structures that differ from the embodiment.

[0111] [Variation Example]

[0112] In the embodiments shown, examples are illustrated where the first coupling recess 74d, the second coupling recess 76d, the take-out component recess 30d, and the output component recess 78d have a first inclined surface 70p and a second inclined surface 70s, but the invention is not limited thereto. For example, the inclined surfaces may not be provided on some or all of these recesses.

[0113] In this embodiment, an example is shown where the first fitting member 74 and the second fitting member 76 are rollers with cylindrical surfaces, but the invention is not limited thereto. These fitting members may also be, for example, polyhedra such as cubes, cuboids, or spheres, and members of different shapes may be used in combination.

[0114] In this embodiment, an example is shown where the first fitting member 74 and the second fitting member 76 are movably supported in the fitting recess, but the invention is not limited thereto. For example, some or all of these fitting members may also be fixed. For example, some or all of these fitting members may also be integrally formed with the output member, coupling body, take-out member, or other components.

[0115] In the embodiments shown, examples are illustrated of the first coupling recess 74d, the second coupling recess 76d, the take-out component recess 30d, and the output component recess 78d having shaft misalignment absorption and torque-pressure conversion functions, but the invention is not limited thereto. Some of these fitting recesses may not have the shaft misalignment absorption function, and some of these fitting recesses may not have the torque-pressure conversion function. One of the shaft misalignment absorption and torque-pressure conversion functions may also be implemented by a mechanism different from these fitting recesses.

[0116] In the embodiment, an example with two support rings 26, 28 is shown, but the invention is not limited to this and may also include three or more support rings.

[0117] In this embodiment, an example is shown where the first support ring 26 rotates freely while the second support ring 28 remains stationary; however, the invention is not limited to this. It is also possible to keep the first support ring 26 stationary while allowing the second support ring 28 to rotate freely.

[0118] In one embodiment, the input collar 14 is arranged radially inward relative to the rotation axis of the friction drive body 20, and the extraction member 30 is arranged radially outward relative to the rotation axis of the friction drive body 20. However, this is not a limitation; the input collar 14 may be arranged on the outer side and the extraction member 30 on the inner side, or both may be arranged on the inner side or both on the outer side. The structure of the friction drive device is not limited to the structure of this embodiment. As long as it has a friction drive mechanism that transmits power through contact between the extraction member (which rotates upon extraction) and multiple friction drive bodies, and has a structure in which the contact surface of the extraction member is inclined relative to the axial direction, the present invention can be widely applied.

[0119] The above-described variations also have the same function and effect as the implementation method.

[0120] Any combination of the constituent elements and variations of the above embodiments is also effective as an embodiment of the present invention. New embodiments resulting from such combinations possess the effects of each of the combined embodiments and variations.

[0121] Industrial availability

[0122] This invention can be used as a friction transmission device.

[0123] Symbol Explanation

[0124] 10-Friction transmission mechanism, 20-Friction transmission body, 30-Removal component, 30d-Removal component recess, 70-Coupling, 70p-First inclined surface, 70s-Second inclined surface, 72-Coupling body, 74-First mating component, 74d-First coupling recess, 76-Second mating component, 76d-Second coupling recess, 78-Output component, 78d-Output component recess, 80-Output side mechanism, 100-Friction transmission device.

Claims

1. A friction transmission device having a friction transmission mechanism that transmits power by contact between a take-out member that takes out an output rotation and a plurality of friction transmission bodies, and a contact surface of the take-out member is inclined with respect to an axial direction, the friction transmission device characterized by comprising: an output member that transmits the output rotation to a driven device; and a coupling that links the take-out member and the output member, the coupling being configured to deform more easily than the take-out member and the output member with respect to a load in the axial direction, and having a function of absorbing misalignment of an axial center between the take-out member and the output member and a function of transmitting torque acting on the output member to the take-out member side after converting the torque into an axial force, the output member having a recessed portion having an inclined surface inclined with respect to the axial direction, the coupling having an abutting member that abuts against the inclined surface.

2. A friction transmission device having a friction transmission mechanism that transmits power by contact between a take-out member that takes out an output rotation and a plurality of friction transmission bodies, and a contact surface of the take-out member is inclined with respect to an axial direction, the friction transmission device characterized by comprising: an output member that transmits the output rotation to a driven device; and a coupling that links the take-out member and the output member, the coupling being configured to deform more easily than the take-out member and the output member with respect to a load in the axial direction, and having a function of absorbing misalignment of an axial center between the take-out member and the output member and a function of transmitting torque acting on the output member to the take-out member side after converting the torque into an axial force, the coupling being capable of moving the take-out member in a first direction orthogonal to the axial direction and capable of moving the output member in a second direction orthogonal to the axial direction and different from the first direction.

3. A friction transmission device having a friction transmission mechanism that transmits power by contact between a take-out member that takes out an output rotation and a plurality of friction transmission bodies, and a contact surface of the take-out member is inclined with respect to an axial direction, the friction transmission device characterized by comprising: an output member that transmits the output rotation to a driven device; and a coupling that links the take-out member and the output member, the coupling being configured to deform more easily than the take-out member and the output member with respect to a load in the axial direction, and having a function of absorbing misalignment of an axial center between the take-out member and the output member and a function of transmitting torque acting on the output member to the take-out member side after converting the torque into an axial force, the friction transmission mechanism having: an input race; planetary rolling bodies disposed around a rotation axis of the input race and in contact with the input race; and a first support race and a second support race in contact with the planetary rolling bodies, the planetary rolling bodies being disposed in contact with the take-out member, the friction transmission device being configured such that an extension line of normal vectors at contact points between the planetary rolling bodies and the races forms a quadrangle.

4. The friction transmission device according to any one of claims 1 to 3, characterized in that ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The coupling has a coupling main body disposed between the extraction member and the output member, the coupling main body being made of a material having a smaller axial length or a smaller Young's modulus than those of the extraction member and the output member.

5. The friction gear device according to any one of claims 1 to 3, characterized in that The coupling has: a coupling main body; first and second coupling recesses provided on the coupling main body; a first fitting member fitted to the first coupling recess and an extraction member recess provided on the extraction member and having a gap between the first coupling recess and the extraction member recess in the first direction; and a second fitting member fitted to the second coupling recess and an output member recess provided on the output member and having a gap between the second coupling recess and the output member recess in the second direction.

6. The friction gear device according to claim 5, characterized in that At least one of the first and second coupling recesses has an inclined surface inclined with respect to the axial direction, At least one of the first and second fitting members abuts against the inclined surface.

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