Rotation transmission device

Abstract

A rotation transmission device (100) equipped with: a fix member (110) that is fixed to a predetermined member; a shaft member (120) to which torque is input; a sliding member (130) that is disposed on the radially outer side of the shaft member (120), rotates integrally with the shaft member (120), is movable relative to the shaft member (120) in the axial direction, and is capable of contacting the fix member (110) in the axial direction; a flange member (140) that is disposed opposite to the fix member (110) with respect to the sliding member (130) in the axial direction and on the radially outer side of the shaft member (120), and that cannot move relative to the shaft member (120) in the axial direction; and a biasing member (150) that is disposed between the flange member (140) and the sliding member (130) and that biases the sliding member (130) in a direction in which the sliding member (130) is pressed against the fix member (110).

Description

Rotation Transmission Device

[0001] The present invention relates to a rotation transmission device equipped with a torque blocking mechanism that prevents torque input from an output shaft from being transmitted to an input shaft. Hereinafter, torque input to the output shaft may be referred to as "reverse torque," and torque input to the input shaft may be referred to as "positive torque."

[0002] When a reverse torque occurs, various mechanisms exist as torque blocking mechanisms that prevent the reverse torque from being transmitted to the input shaft side.

[0003] For example, Patent Document 1 describes a mechanism in which, when reverse torque is input, an engaging element engages between the output shaft and a fixed outer ring, thereby locking the rotation of the output shaft through frictional force and preventing the transmission of reverse torque to the input shaft.

[0004] Furthermore, Patent Document 2 describes a mechanism in which, when a reverse torque is input, a ball engages with a wedge-shaped space, thereby preventing the reverse torque from being transmitted to the input shaft.

[0005] Furthermore, Patent Document 3 describes a mechanism in which, when stationary, an intermediate member is pressed against a stationary member by a spring, generating a frictional force, and when reverse torque is input, the constraint between the intermediate member and the stationary member is not released, preventing the reverse torque from being transmitted to the input shaft.

[0006] JP 2017-20612 A JP 2004-176779 A JP 2000-346099 A

[0007] However, in conventional torque blocking mechanisms, when a positive torque input to the input shaft is transmitted to the output shaft, if a reverse torque occurs in the same rotational direction as the positive torque, there is a risk of an unstable state occurring, such as two or more components repeatedly separating and contacting each other.

[0008] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a rotation transmission device that can suppress unstable behavior when a reverse torque is input.

[0009] In order to achieve the above object, one aspect of the present invention provides a rotation transmission device comprising: a fixed member fixed to a predetermined member; a shaft member to which torque is input; a sliding member arranged radially outside the shaft member, rotating integrally with the shaft member, movable axially relative to the shaft member, and capable of contacting the fixed member in the axial direction; a flange member arranged axially on the opposite side of the sliding member from the fixed member and radially outside the shaft member, unable to move axially relative to the shaft member; and a biasing member arranged between the flange member and the sliding member, biasing the sliding member in a direction pressing the sliding member against the fixed member.

[0010] According to the present invention, for example, when no positive torque is input to the shaft member, even if a reverse torque smaller than the friction force generated between the fixed member and the sliding portion is input, the shaft member will not rotate, and it is possible to prevent the reverse torque from being transmitted to the input side regardless of the direction of the reverse torque. Furthermore, even when a positive torque or a reverse torque in the same direction as the positive torque is input, contact between the fixed member and the sliding member is maintained, so an unstable state such as repeated contact and separation between two or more members as described above does not occur.

[0011] Fig. 1 is a cross-sectional view showing a rotation transmission device according to an embodiment; Fig. 2 is a diagram schematically showing a steering device provided with a rotation transmission device; Fig. 3 is a cross-sectional view showing a rotation transmission device according to an embodiment; Fig. 4 is a perspective view showing an exploded view of a torque limiter; Fig. 5 is a cross-sectional view showing another example 1 of the rotation transmission device; Fig. 6 is a cross-sectional view showing another example 2 of the rotation transmission device; Fig. 7 is a cross-sectional view showing a rotation transmission device of a first mode;

[0012] Hereinafter, embodiments of a rotation transmission device according to the present invention will be described with reference to the drawings. Note that the following embodiments are presented as examples for the purpose of explaining the present invention and are not intended to limit the present invention. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, mathematical formulas, the content of each step in a method, and the order of each step shown in the following embodiments are merely examples and may include content not described below. Furthermore, while geometric expressions such as parallel and orthogonal may be used, these expressions do not imply mathematical precision and include substantially acceptable errors, deviations, and the like. Furthermore, expressions such as simultaneous and identical also include substantially acceptable ranges.

[0013] The drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions is appropriately made for the purpose of explaining the present invention, and differ from the actual shapes, positional relationships, and proportions. The X-axis, Y-axis, and Z-axis shown in the drawings represent Cartesian coordinates arbitrarily set for the purpose of explaining the drawings. In other words, the Z-axis is not necessarily an axis along the vertical direction, and the X-axis and Y-axis are not necessarily located within a horizontal plane.

[0014] In addition, in the following, multiple inventions may be collectively described as one embodiment, and some of the contents described below may be described as optional components related to the present invention.

[0015] Fig. 1 is a diagram that schematically shows a steering device 200 that includes a rotation transmission device 100. Note that in Fig. 1, rotation transmission device 100 is shown in an abstract state. Steering device 200 employs a so-called linkless SBW (Steer By Wire) system in which two steerable wheels 210 are not mechanically connected by mechanical elements such as links or gears, and the steering angles of the two steerable wheels 210 can be set independently. Steering device 200 includes a steering drive device 220, a steering device 230, a steering control device 240, and rotation transmission device 100.

[0016] In the present embodiment, a vehicle equipped with steering device 200 has four wheels on the front, rear, left and right sides of the vehicle body, and the front left and right wheels are steered wheels 210 that can turn around a vertical axis. A traveling drive device 250, which is called an in-wheel motor or the like, is attached to the inside of steered wheels 210 via wheels 211. In other words, steered wheels 210 also function as drive wheels.

[0017] The vehicle may be an automobile, bus, truck, construction machine, agricultural machine, or other vehicle that may be operated by a driver, or an unmanned vehicle that is steered without a human on board, such as an autonomous guided vehicle or an autonomously traveling robot. The traveling drive device 250 may be attached to the steered wheels 210 via a power train. The steered wheels 210 may be driven wheels to which the traveling drive device 250 is not connected.

[0018] The steering drive device 220 is a so-called actuator that independently steers each of the steered wheels 210 provided on the left and right sides of the vehicle body. In the present embodiment, the steering drive device 220 includes an electric motor such as a servo motor and a reducer, and the torque generated by the electric motor is increased by the reducer.

[0019] Steering device 230 is a device that outputs a command steering angle, which is information related to the steering angle, which is the turning angle of steered wheels 210. In the present embodiment, steering device 230 includes an operation member 231, which is called a steering wheel or the like, that is operated by a driver who is in the vehicle body, and a steering angle sensor 232 that outputs the steering angle of operation member 231 as a command steering angle in a manual driving mode in which the driver steers operation member 231.

[0020] The steering control device 240 is a computer equipped with a processor called an ECU (Electronic Control Unit) or the like that controls the steering drive device 220, and performs processing related to steering by having the processor execute a program. For example, the steering control device 240 obtains from the steering device 230 a command steering angle generated when the driver operates the operating member 231, and controls the left and right steering drive devices 220 independently based on the obtained command steering angle. In the case of autonomous driving, the left and right steering drive devices 220 are controlled independently based on a command steering angle output by another ECU or the like.

[0021] 2 is a cross-sectional view showing a rotation transmission device 100 according to an embodiment of the present invention. As shown in the figure, rotation transmission device 100 includes a fixed member 110, a shaft member 120, a sliding member 130, a flange member 140, and a biasing member 150 including a first biasing member 151 and a second biasing member 152. In the present embodiment, rotation transmission device 100 also includes a torque limiter 160. The location where rotation transmission device 100 is applied is not particularly limited. In the present embodiment, rotation transmission device 100 is applied to a steering device 200 that steers steered wheels 210 of a vehicle using the driving force of a steering drive device 220 including a motor or the like.

[0022] The fixed member 110 is a structural member fixed to a predetermined member. The fixed member 110 is cylindrical, and the shaft member 120 is inserted into the interior thereof. The sliding member 130, the flange member 140, the first biasing member 151, and the second biasing member 152 are housed inside the fixed member 110. In the axial direction (the Z-axis direction in the figure), the fixed member 110 includes a lid portion 111 that covers a portion of the opening at one end, and a bottom portion 112 that covers a portion of the opening at the other end and has a central insertion hole 115. At least one of the lid portion 111 and the bottom portion 112 (the bottom portion 112 in this embodiment) is detachably attached to a peripheral wall portion 113 of the fixed member 110. The shape of the fixed member 110 is not limited, and in this embodiment, a cylindrical shape is adopted as the shape of the fixed member 110.

[0023] The predetermined member to which fixed member 110 is fixedly attached is not limited to, but may be, for example, a vehicle body, etc. In the case of this embodiment, fixed member 110 is connected interposed between steering drive device 220 fixed to the vehicle body and turning means 260 that turns steered wheels 210, and fixed member 110 is fixed to the vehicle body via a housing of steering drive device 220.

[0024] The shaft member 120 is a shaft-shaped member that can input torque around its axis (θ in the figure) and output the input torque. In this embodiment, the shaft member 120 is divided into a first shaft member 121 and a second shaft member 122. The first shaft member 121 is restricted from moving in the axial direction (Z-axis direction in the figure) relative to the fixed member 110, and is held by a first bearing 114 attached to the center of the cover portion 111 of the fixed member 110 so as to be rotatable in the circumferential direction (θ direction in the figure). The first shaft member 121 is connected to the output shaft of the steering drive device 220, and the second shaft member 122 is connected to the turning means 260. The first shaft member 121 and the second shaft member 122 are arranged coaxially. The second shaft member 122 is arranged in a state where it is inserted into an insertion hole 115 of the fixed member 110.

[0025] The sliding member 130 is a plate-shaped member that is disposed radially outward of the shaft member 120, rotates integrally with the shaft member 120, and is movable in the axial direction relative to the shaft member 120. The sliding member 130 is also capable of contacting the fixed member 110 in the axial direction. The shape of the sliding member 130 is not limited, but in the present embodiment, the sliding member 130 is disk-shaped and has a hole in the center that penetrates in the thickness direction and through which the second shaft member 122 is inserted. The sliding member 130 and the second shaft member 122 are fitted together in a state that engages with each other in the circumferential direction but does not engage with each other in the axial direction, allowing them to move relative to each other. Specifically, examples include a case where the second shaft member 122 is a polygonal rod and the hole provided in the sliding member 130 is a polygon corresponding to the cross-sectional shape of the second shaft member 122, a case where the second shaft member 122 and the sliding member 130 are serrated fitted, a case where the second shaft member 122 and the sliding member 130 are spline fitted, and a case where the second shaft member 122 and the sliding member 130 are connected by a key structure which is a fitting structure of a key and a key groove.

[0026] The flange member 140 is a member that is arranged on the opposite side of the contact portion between the sliding member 130 and the fixed member 110 in the axial direction and radially outward of the shaft member 120. In the present embodiment, the flange member 140 includes a first flange member 141 fixed to the first shaft member 121 and a second flange member 142 fixed to the second shaft member 122. The shapes of the first flange member 141 and the second flange member 142 are not limited, but in the present embodiment, each is disk-shaped. The first flange member 141 and the second flange member 142 are fixed to the ends of the first shaft member 121 and the second shaft member 122, respectively. The first flange member 141 and the second flange member 142 also constitute a part of a torque limiter 160, which will be described later. The first flange member 141 and the second flange member 142 may have holes formed in their central portions that penetrate in the thickness direction (the Z-axis direction in the figure) and through which the first shaft member 121 and the second shaft member 122 are inserted, respectively. The first flange member 141 and the first shaft member 121, and the second flange member 142 and the second shaft member 122 are fitted together so as not to move relative to each other at least in the axial direction.

[0027] The first biasing member 151 is disposed between the second flange member 142 and the sliding member 130, and biases the sliding member 130 in a direction pressing the sliding member 130 against the fixed member 110. The first biasing member 151 also biases the second flange member 142 in a direction away from the bottom 112 of the fixed member 110, thereby biasing the first flange member 141 and the second flange member 142 in a direction moving closer to each other. The type of first biasing member 151 is not limited, but in this embodiment, a coil spring is used. The first biasing member 151 is disposed with the second shaft member 122 inserted therethrough.

[0028] The second biasing member 152 is disposed between the second flange member 142 and the sliding member 130, and biases the first flange member 141 and the second flange member 142 in a direction that brings them closer together. The type of second biasing member 152 is not limited, but in the present embodiment, a coil spring is used as the second biasing member 152. In the present embodiment, an annular connecting member 153, through which the second shaft member 122 is inserted, is disposed between the first biasing member 151 and the second biasing member 152. The detailed relationship between the first biasing member 151 and the second biasing member 152 will be described later.

[0029] The torque limiter 160 is disposed between the first shaft member 121 and the second shaft member 122, and is a mechanism that allows relative rotation between the first shaft member 121 and the second shaft member 122 when the torsional couple generated between the first shaft member 121 and the second shaft member 122 exceeds an activation threshold. In other words, as long as the torsional couple generated between the first shaft member 121 and the second shaft member 122 does not exceed the activation threshold, the torque limiter 160 can maintain the integral rotation of the first shaft member 121 and the second shaft member 122.

[0030] FIG. 3 is an exploded perspective view of the torque limiter 160. The torque limiter 160 includes a first flange member 141 and a second flange member 142 that constitute the flange member 140, and a ball member 165 disposed between them. The first biasing member 151 and the second biasing member 152 also function as part of the torque limiter 160. The second flange member 142 includes a second recess 164 on a second opposing surface 162 that faces the first flange member 141, and a ball groove 166 that communicates with the second recess 164. In this embodiment, the second recess 164 is provided at four locations evenly spaced circumferentially, and the ball groove 166 is arranged in an annular shape so as to communicate with all four second recesses 164. Similar to the second flange member 142, the first flange member 141 includes a first recess 163 on a first opposing surface 161 that faces the second flange member 142, and a ball groove (not shown) that communicates with the first recess 163. In this embodiment, four first recesses 163 are provided at equal intervals in the circumferential direction so as to face the second recesses 164, and together with the second recesses 164, form accommodation spaces that accommodate ball members 165. A ball member 165 is accommodated in each of the four accommodation spaces. The ball grooves provided in the first opposing surface 161 communicate with all four first recesses 163 and are arranged in an annular shape so as to face the ball grooves 166 in the second opposing surface 162. The depth of the ball grooves 166 is shallower than that of the second recesses 164, and the depth of the ball grooves provided in the first opposing surface 161 is shallower than that of the first recesses 163.

[0031] When the torsional couple applied to the shaft member 120 is less than the activation threshold, the first flange member 141 and the second flange member 142 are arranged to maintain a predetermined distance by the first biasing member 151 and the second biasing member 152 with the ball members 165 housed in the first recess 163 and the second recess 164. In this state, the torque limiter 160 causes the first recess 163 and the second recess 164 to engage with the ball members 165 due to a torsional couple less than the activation threshold, and the first flange member 141 and the second flange member 142 rotate together. In other words, torque is transmitted between the first shaft member 121 and the second shaft member 122. When the torsional couple applied to the shaft member 120 is excessively large to the extent that it exceeds the activation threshold, the ball members 165 housed in the housing space against the biasing forces of the first biasing member 151 and the second biasing member 152 retreat into the retreat space formed by the ball grooves 166, and roll or slide in the ball grooves 166, causing the first flange member 141 and the second flange member 142 to rotate relative to each other, thereby blocking the transmission of torque. In other words, torque is not transmitted between the first shaft member 121 and the second shaft member 122.

[0032] In this embodiment, the first biasing member 151 and the second biasing member 152 are arranged in series so that their respective biasing directions coincide in the axial direction. The first biasing member 151 has a smaller spring constant than the second biasing member 152. In a normal state (a state in which a torsional couple exceeding the activation threshold is not input to the shaft member 120), when the first biasing member 151 and the second biasing member 152 are arranged in series between the second flange member 142 and the sliding member 130, the first biasing member 151 enters a wire-to-wire contact state due to the second biasing member 152 being in a non-wire-to-wire contact state. Here, the wire-to-wire contact state refers to a state in which a coil spring is fully compressed. Specifically, the wire-to-wire contact state occurs when a strong force is applied to the first biasing member 151, which is a coil spring, causing adjacent wires to come into close contact with each other with almost no gaps and no further compression.

[0033] Next, a description will be given of the operation of the rotation transmission device 100 applied to the steering device 200. In the case of the steering device 200, the state of torque input to the rotation transmission device 100 can be exemplified as follows.

[0034] (1) In a state where power is not supplied to the steering drive device 220, for example, when power is not supplied to the steering drive device 220 because the vehicle is stopped, no positive torque is input to the first shaft member 121, and the first shaft member 121 is in a free state where it can rotate freely in the rotational direction. In this state, if the vehicle is stopped at an angle relative to an incline, for example, a reverse torque is input to the second shaft member 122. In this case, because the input reverse torque is relatively small, the reverse torque does not exceed the first static friction force generated when the sliding member 130 is pressed against the inner surface of the bottom part 112 of the fixed member by the biasing forces of the first biasing member 151 and the second biasing member 152, and the rotation of the second shaft member 122 is restricted by the fixed member 110 via the sliding member 130, and the reverse torque is not transmitted to the first shaft member 121.

[0035] (2) In a state in which the vehicle is traveling straight, a so-called straight-ahead steering state, power is supplied to the steering drive device 220, and the second shaft member 122 is held without rotation by the positive torque input to the first shaft member 121. In this case, the first shaft member 121 is held by the steering drive device 220 so as not to rotate. The rotation of the second shaft member 122 is fixed by the holding force of the steering drive device 220 transmitted via the torque limiter 160 and the first static friction force between the fixed member 110 and the sliding member 130, and the fixed state of rotation is maintained even if a reverse torque is input.

[0036] (3) When changing the traveling direction of the vehicle, while steered wheels 210 are turning, positive torque is input from steering drive device 220 to first shaft member 121, and reverse torque is input from steered wheels 210 to second shaft member 122. In this case, the torsional couple generated between first shaft member 121 and second shaft member 122 is less than the activation threshold value and exceeds the first static friction force. As a result, second shaft member 122 rotates together with first shaft member 121, and steered wheels 210. Note that in this case, the positive torque input from steering drive device 220 is greater than the sum of the first static friction force and the reverse torque.

[0037] (4) In a state in which the vehicle is traveling around a certain curve, a so-called curve steering holding state, power is supplied to steering drive device 220, and shaft member 120 is held without rotation by positive torque input to first shaft member 121, and reverse torque is input from steered wheels 210 to second shaft member 122. In this case, the torsional couple generated between first shaft member 121 and second shaft member 122 is less than the activation threshold and is below the first static friction force. First shaft member 121 is held by steering drive device 220 so as not to rotate. Rotation of second shaft member 122 is fixed by the holding force of steering drive device 220 transmitted via torque limiter 160 and the first static friction force, and the curve steering holding state is maintained.

[0038] On the other hand, in the above states (2), (3), and (4), if the torsional couple suddenly generated between the first shaft member 121 and the second shaft member 122 exceeds the activation threshold value, for example, because the steered wheel 210 runs over a stone, the ball members 165 will retract from the first recessed portion 163 and the second recessed portion 164 into the retraction space formed by the ball grooves 166 against the biasing forces of the first biasing member 151 and the second biasing member 152. This releases the connection between the first flange member 141 and the second flange member 142 in the rotational direction, causing the first shaft member 121 and the second shaft member 122 to rotate relative to each other. Therefore, the counter torque is no longer transmitted to the first shaft member 121, and the counter torque is prevented from affecting the turning drive device 220. Furthermore, when the torsional couple generated between the first shaft member 121 and the second shaft member 122 falls below the activation threshold, the ball member 165 rolls or slides due to the relative rotation of the first flange member 141 and the second flange member 142, and is again accommodated in the accommodation space formed by the first recess 163 and the second recess 164, and the connection state between the first shaft member 121 and the second shaft member 122 in the rotational direction is re-established.

[0039] The present invention is not limited to the above-described embodiments. For example, the present invention may be embodied in another embodiment by arbitrarily combining the components described in this specification or by excluding some of the components. Furthermore, the present invention also includes various modifications that would occur to a person skilled in the art without departing from the spirit of the present invention, i.e., the meaning of the wording of the claims.

[0040] For example, as shown in FIG. 4, the torque limiter 160 may include a cylindrical first opposing surface 161 provided on the first shaft member 121, a cylindrical second opposing surface 162 provided on the second shaft member 122, arranged concentrically with the first opposing surface 161 and radially opposing the first opposing surface 161, and a radial spring 167 arranged between the first opposing surface 161 and the second opposing surface 162, which connects the first shaft member 121 and the second shaft member 122 with a second static friction force that is a predetermined static friction force.

[0041] In this case, the biasing member 150 may be a spring with a spring constant that can generate the first static friction force. The second static friction force is stronger than the first static friction force and is a force that allows relative rotation between the first shaft member 121 and the second shaft member 122 when the torsional couple generated in the first shaft member 121 and the second shaft member 122 exceeds an activation threshold.

[0042] Furthermore, the cover portion 111 of the fixed member 110 may function as the flange member 140 that supports the first biasing member 151. Furthermore, a second bearing 116 may be disposed between the flange member 140 and the first biasing member 151 so as to allow the first biasing member 151 to rotate together with the sliding member 130.

[0043] Furthermore, as shown in FIG. 5, the sliding member 130 and the fixed member 110 may each have a tapered surface, and the tapered surface of the sliding member 130 may be pressed against the tapered surface of the fixed member 110 .

[0044] Furthermore, the axial positional relationship between the first biasing member 151 and the second biasing member 152 shown in FIG. 1 may be reversed.

[0045] Furthermore, the first biasing member 151 and the second biasing member 152 may be directly connected to each other without the intermediary of the connecting member 153. Furthermore, the first biasing member 151 and the second biasing member 152 may be integral with each other.

[0046] Furthermore, the torque limiter 160 may be configured by arranging the first shaft member 121 and the second shaft member 122 coaxially and forming recesses or ball grooves that form spaces for accommodating balls on the opposing surfaces of each shaft member.

[0047] (Summary) As shown in FIG. 6 , the rotation transmission device 100 of the first aspect includes: a fixed member 110 fixed to a predetermined member; a shaft member 120 to which torque is input; a sliding member 130 arranged radially outside the shaft member 120, rotating integrally with the shaft member 120, movable axially relative to the shaft member 120, and capable of coming into contact with the fixed member 110 in the axial direction; a flange member 140 arranged axially on the opposite side of the sliding member 130 from the fixed member 110 and radially outside the shaft member 120, unable to move axially relative to the shaft member 120; and a biasing member 150 arranged between the flange member 140 and the sliding member 130, which biases the sliding member 130 in a direction pressing the sliding member 130 against the fixed member 110.

[0048] According to this configuration, the first biasing member 151 biases the sliding member 130 in the axial direction so that the fixed member 110 and the sliding member 130 are always in contact with each other, so that even if a torque smaller than the first static friction force generated between the fixed member 110 and the sliding member 130 is input, the shaft member 120 is locked and no torque is transmitted in the shaft member 120. For example, if the reverse torque applied to the shaft member 120 is smaller than the positive torque, the first static friction force can be set by adjusting the spring constant of the biasing member 150 so that only the positive torque is transmitted.

[0049] Furthermore, even if a reverse torque occurs while the shaft member 120 is rotating due to a positive torque exceeding the first static friction force, the contact state between the sliding member 130 and the fixed member 110 is always maintained. Therefore, the input of a reverse torque does not cause the sliding member 130 to flutter, such as coming into contact with or separating from the fixed member 110, and unstable operation does not occur.

[0050] The second aspect of the rotation transmission device 100 includes the first aspect, and the shaft member 120 has a first shaft member 121 and a second shaft member 122, and a torque limiter 160 is provided between the first shaft member 121 and the second shaft member 122.

[0051] According to the second aspect, by adjusting the spring constant of the biasing member 150 and the release torque of the torque limiter 160 so that the first static friction force is smaller than the set torque of the torque limiter 160, even if a torsional couple less than the first frictional force is applied to the shaft member 120, the shaft member 120 will not rotate and no torque will be transmitted; when a torsional couple greater than the first frictional force but less than the set torque of the torque limiter 160 is applied to the shaft member 120, the first shaft member 121 and the second shaft member 122 will rotate together and torque will be transmitted; and when a torsional couple greater than the set torque of the torque limiter 160 is applied to the shaft member 120, the torque limiter 160 will function to block the transmission of torque.

[0052] The rotation transmission device 100 of the third aspect includes the first aspect and the second aspect, and the torque limiter 160 includes a first opposing surface 161 provided on the first shaft member 121, a second opposing surface 162 provided on the second shaft member 122 and opposing the first opposing surface 161 in the axial direction, a first recess 163 formed on the first opposing surface 161, a second recess 164 formed on the second opposing surface 162, a ball member 165 accommodated in an accommodation space formed between the first recess 163 and the second recess 164, and a torque limiter 160 provided on the first opposing surface 161 and the second opposing surface 162. and a ball groove 166 formed circumferentially on at least one of the first opposing surface 161 and the second opposing surface 162 and communicating with either the first recess 163 or the second recess 164. When the torsional couple applied to the shaft member 120 is excessive, the first shaft member 121 and the second shaft member 122 rotate relative to each other, causing the ball member 165 accommodated in the accommodation space to retreat into the retreat space formed by the ball groove 166 against the urging forces of the first urging member 151 and the second urging member 152.

[0053] According to this, if a reverse torque is suddenly input, the axial component force generated at the contact point between the first recess 163 or the second recess 164 and the ball member 165 also becomes excessive, causing the biasing member 150 to contract, causing the first shaft member 121 and the second shaft member 122 to move away from each other in the axial direction and begin to rotate relative to each other. The ball member 165 retreats from the accommodation space, but moves within the retreat space formed by the ball groove 166 and returns to the accommodation space, making it possible to transmit torque again.

[0054] A fourth aspect of the rotation transmission device 100 includes the third aspect, and the biasing member 150 biases the first opposing surface 161 and the second opposing surface 162 in a direction toward each other, and includes a first biasing member 151 and a second biasing member 152 that are arranged in series so that their respective biasing directions coincide in the axial direction, and the first biasing member 151 has a smaller spring constant than the second biasing member 152, and when the ball member is accommodated in the accommodation space, the ball member is in a state of wire-to-wire contact.

[0055] With this, for example, when first biasing member 151 and second biasing member 152 are placed inside fixed member 110 and bottom portion 112 is assembled, even if there is a component tolerance or assembly error in fixed member 110, the component tolerance or assembly error is absorbed by first biasing member 151, which has a small spring constant. Furthermore, when assembly is complete, first biasing member 151 is in a nearly line-to-line contact state and behaves like a rigid body in the direction in which bottom portion 112 of fixed member 110 and second opposing surface 162 widen. This suppresses fluctuations in the biasing force of biasing member 150 as a whole that functions as torque limiter 160, and makes it possible to prevent the torque limiter from being activated by a force smaller than intended, which occurs when first biasing member 151 is not in a line-to-line contact state.

[0056] The fifth aspect of the rotation transmission device 100 includes the second aspect, and the torque limiter 160 includes a first opposing surface 161 provided on the first shaft member 121, a second opposing surface 162 provided on the second shaft member 122 and radially opposing the first opposing surface 161, the first opposing surface 161 and the second opposing surface 162 which are opposing surfaces of the first shaft member 121 and the second shaft member 122 that are radially opposing each other, and a radial spring 167 arranged between the first opposing surface 161 and the second opposing surface 162 and connecting the first shaft member 121 and the second shaft member 122 with a predetermined static friction force.

[0057] According to the rotation transmission device 100 of the fifth aspect, when the sum of the positive torque and the reverse torque is applied to the shaft member 120, the frictional force generated by the radial spring 167, which is a so-called tolerance ring, is exceeded, causing the first shaft member 121 and the second shaft member 122 to slip and preventing the transmission of rotation. In other words, the radial spring 167 functions as the torque limiter 160. This allows at least a portion of the radial spring 167 to be disposed inside the biasing member 150, thereby shortening the length of the rotation transmission device 100 in the axial direction.

[0058] The present invention is applicable not only to the steering device 200 but also to parts that transmit torque, such as a power train.

[0059] 100...Rotation transmission device, 110...Fixed member, 111...Cover portion, 112...Bottom portion, 113...Peripheral wall portion, 114...First bearing, 115...Insertion hole, 116...Second bearing, 120...Shaft member, 121...First shaft member, 122...Second shaft member, 130...Sliding member, 140...Flange member, 141...First flange member, 142...Second flange member, 150...Using member, 151...First urging member, 152...Second urging member, 153...Connecting member, 160...torque limiter, 161...first opposing surface, 162...second opposing surface, 163...first recess, 164...second recess, 165...ball member, 166...ball groove, 167...radial spring, 200...steering device, 210...steered wheel, 211...wheel, 220...steering drive device, 230...steering device, 231...operation member, 232...steering angle sensor, 240...steering control device, 250...traveling drive device, 260...turning means

Claims

1. A rotation transmission device comprising: a fixed member fixed to a specified member; a shaft member to which torque is input; a sliding member arranged radially outward of said shaft member and rotating integrally with said shaft member, movable axially relative to said shaft member and capable of contacting said fixed member in the axial direction; a flange member arranged axially on the opposite side of said sliding member to said fixed member and radially outward of said shaft member, which cannot move axially relative to said shaft member; and a biasing member arranged between said flange member and said sliding member and biasing said sliding member in a direction pressing said sliding member against the fixed member.

2. A rotation transmission device as set forth in claim 1, wherein the shaft member comprises a first shaft member and a second shaft member, and a torque limiter is provided between the first shaft member and the second shaft member.

3. A rotation transmission device as described in claim 2, wherein the torque limiter comprises: a first opposing surface provided on the first shaft member; a second opposing surface provided on the second shaft member and axially opposing the first opposing surface; a first recess formed on the first opposing surface; a second recess formed on the second opposing surface; a ball member accommodated in an accommodating space formed between the first recess and the second recess; and a ball groove formed in the circumferential direction on at least one of the first opposing surface and the second opposing surface and communicating with at least one of the first recess and the second recess; and when a torsional couple generated in the shaft member is excessive, the first shaft member and the second shaft member rotate relative to each other, causing the ball member accommodated in the accommodating space to retract against the biasing force of the biasing member into a retraction space formed by the ball groove.

4. The rotation transmission device according to claim 3, wherein the biasing member comprises a first biasing member and a second biasing member which bias the first opposing surface and the second opposing surface in a direction toward each other and are arranged in series so that their respective biasing directions coincide in the axial direction, and the first biasing member has a smaller spring constant than the second biasing member, and is in a state of wire-to-wire contact when the ball member is accommodated in the accommodating space.

5. A rotation transmission device as described in claim 2, wherein the torque limiter comprises: a first opposing surface provided on the first shaft member; a second opposing surface provided on the second shaft member radially opposing the first opposing surface; and a radial spring disposed between the first opposing surface and the second opposing surface, connecting the first shaft member and the second shaft member with a predetermined static friction force.

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