Reverse input–blocking clutch–equipped motor and steering device

Abstract

Provided are a reverse input–blocking clutch–equipped motor that makes it possible for a lubricant to exhibit favorable performance even in low-temperature environments and a steering device that comprises the reverse input–blocking clutch–equipped motor. A controller 4 has a warm-up operation function that, when a prescribed condition is met, raises the temperature of a lubricant that provides lubrication between a stationary member 7 and an engagement element 10 on the basis of rotational torque being inputted from a motor output shaft 6 to an input member 8.

Description

Motor with reverse input cutoff clutch and steering device

[0001] The present disclosure relates to a motor with a reverse input cutoff clutch that cuts off rotational torque reversely input to an output member while transmitting rotational torque input to an input member to the output member, and to a steering device including the motor with a reverse input cutoff clutch.

[0002] A reverse input cutoff clutch transmits rotational torque input to an input member connected to an input-side mechanism such as a drive source like a motor to an output member connected to an output-side mechanism such as a speed reduction mechanism, and has a function of either completely blocking rotational torque reversely input to the output member so as not to transmit it to the input member, or transmitting only a part of the rotational torque reversely input to the output member to the input member while blocking the remaining part. Reverse input cutoff clutches are incorporated into various mechanical devices including mechanical devices constituting automobiles such as steering devices, enable size reduction and energy saving of various mechanical devices, and further bring high safety to various mechanical devices through their reverse input cutoff function.

[0003] Reverse input cutoff clutches are broadly classified, depending on the difference in the mechanism for cutting off rotational torque reversely input to the output member, into lock-type reverse input cutoff clutches provided with a mechanism that prevents rotation of the output member when rotational torque is reversely input to the output member, and free-type reverse input cutoff clutches provided with a mechanism that allows the output member to idle when rotational torque is input to the output member. Whether to use a lock-type reverse input cutoff clutch or a free-type reverse input cutoff clutch is appropriately determined depending on the application of the device in which the reverse input cutoff clutch is incorporated.

[0004] Japanese Unexamined Patent Application Publication No. 2007-232095 and International Publication No. WO 2019 / 026794 disclose lock-type reverse input cutoff clutches.

[0005] The reverse input blocking clutch described in Japanese Patent Publication No. 2007-232095 is configured to prevent the rotation of the output member by moving an engaging element, which is a cylindrical roller positioned in a wedge-shaped space between the output member and the stationary member, to the narrower side of the wedge-shaped space in the radial direction when rotational torque is input in reverse to the output member, thereby creating tension between the output member and the stationary member. This reverse input blocking clutch has the problem of having a large number of parts because a large number of engaging elements are used. In addition, there is a possibility that the engaging element may remain engaged in the narrower part of the wedge-shaped space in the radial direction, preventing the lock from being released.

[0006] In the reverse input blocking clutch described in International Publication No. 2019 / 026794, when rotational torque is input to the input member from the drive source, the input-side engaging portion of the input member engages with the input-side engaged portion of the engaging element, causing the engaging element to move away from the pressed surface of the stationary member, and the output-side engaged portion of the engaging element engages with the output-side engaging portion of the output member, thereby transmitting the rotational torque input to the input member to the output member. On the other hand, when rotational torque is input in reverse to the output member, the output-side engaging portion engages with the output-side engaged portion, causing the engaging element to move towards the pressed surface, pressing the pressing surface of the engaging element against the pressed surface, and thus frictionally engaging the pressing surface with the pressed surface.

[0007] In the reverse input blocking clutch described in International Publication No. 2019 / 026794, the engaging element has both the function of transmitting the rotational torque input to the input member to the output member and the function of locking the output member. As a result, the number of parts in the reverse input blocking clutch can be reduced, and the operation can be made more stable compared to cases where the function of transmitting rotational torque and the function of locking are each provided by separate members.

[0008] Japanese Patent Publication No. 2007-232095, International Publication No. 2019 / 026794

[0009] A lubricant such as traction grease is applied to the area between the engaging element and the stationary member of the reverse input blocking clutch to prevent wear.

[0010] It is known that lubricants increase in viscosity or decrease in friction coefficient as their temperature decreases. This increase in viscosity or decrease in friction coefficient can make it difficult for the lubricant to perform as intended.

[0011] For example, in the reverse input blocking clutch described in International Publication No. 2019 / 026794, the pressing surface of the engaging element may become slippery against the pressed surface of the stationary member, potentially preventing the output member from being reliably locked or partially locked when rotational torque is applied in reverse to the output member. This phenomenon tends to be more pronounced, for example, in low-temperature environments below 0°C.

[0012] The present disclosure aims to provide a motor with a reverse input blocking clutch that can ensure good performance of the lubricant even in low-temperature environments, and a steering device equipped with the motor with the reverse input blocking clutch.

[0013] A motor with a reverse input blocking clutch according to one aspect of the present disclosure comprises a motor, a controller, and a reverse input blocking clutch.

[0014] The motor has a motor output shaft.

[0015] The controller controls the rotation of the motor output shaft.

[0016] The reverse input blocking clutch comprises a stationary member that does not rotate during use, an input member that is rotationally driven by the motor output shaft, an output member connected to an output mechanism so as to transmit rotational torque, an engaging element, and a lubricant for lubricating the space between the stationary member and the engaging element. When rotational torque is input from the motor output shaft to the input member, the clutch transmits the rotational torque input to the input member to the output member. Conversely, when rotational torque is reverse-input to the output member from the output mechanism, the clutch engages the engaging element with the stationary member, thereby locking or partially locking the rotation of the output member.

[0017] The controller has a warm-up function that, when predetermined conditions are met, increases the temperature of the lubricant based on inputting rotational torque from the motor output shaft to the input member.

[0018] A motor with a reverse input blocking clutch according to one aspect of the present disclosure comprises a space in which the reverse input blocking clutch is arranged, a thermometer for measuring the temperature of at least one of the stationary member and the lubricant, wherein the predetermined condition includes that the temperature measured by the thermometer is less than or equal to a predetermined threshold.

[0019] In a motor with a reverse input blocking clutch according to one aspect of the present disclosure, the thermometer is installed on the stationary member.

[0020] In a motor with a reverse input blocking clutch according to one aspect of the present disclosure, the controller rotates the motor output shaft back and forth within a predetermined angular range while the warm-up function is being performed.

[0021] In a motor with a reverse input blocking clutch according to one aspect of the present disclosure, the stationary member has a pressed surface on its inner circumferential surface, the input member has an input-side engaging portion arranged radially inward from the pressed surface and is arranged coaxially with the pressed surface, the output member has an output-side engaging portion arranged radially inward from the input-side engaging portion and is arranged coaxially with the pressed surface, and the engaging element has a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and is arranged to be movable radially.

[0022] The engaging element is configured such that when rotational torque is input to the input member, the input-side engaging portion engages with the input-side engaged portion and moves radially away from the pressed surface, causing the output-side engaged portion to engage with the output-side engaging portion. When rotational torque is input in reverse to the output member, the output-side engaging portion engages with the output-side engaged portion, pressing the pressing surface against the pressed surface and causing the pressing surface to frictionally engage with the pressed surface. The lubricant lubricates the space between the pressed surface and the pressing surface.

[0023] A steering device according to one aspect of the present disclosure comprises a motor with a reverse input blocking clutch having an output member, and a linear motion mechanism having a rod connected to the steering wheel, which is supported to enable linear motion in the axial direction of the motor and which changes the direction of the steering wheel in accordance with the linear motion, and which converts the rotational motion of the output member into linear motion in the axial direction of the rod.

[0024] In particular, in a steering device according to one aspect of the present disclosure, the motor with reverse input blocking clutch is configured with a motor with reverse input blocking clutch according to any aspect of the present disclosure.

[0025] In a steering device according to one aspect of the present disclosure, the steering wheel is a rear wheel.

[0026] According to a motor with a reverse input blocking clutch and a steering device according to one aspect of the present disclosure, the performance of the lubricant can be effectively utilized even in low-temperature environments.

[0027] Figure 1 is a schematic diagram showing a motor with a reverse input blocking clutch and steering device according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view showing the reverse input blocking clutch removed from the motor with the reverse input blocking clutch. Figure 3 is a cross-sectional view taken along line I-I in Figure 2. Figure 4 is a cross-sectional view taken along line I-I in Figure 2 showing the state in which rotational torque is input to the input member, with the holding member and biasing member omitted. Figure 5 is a cross-sectional view taken along line I-I in Figure 2 showing the state in which rotational torque is input in reverse to the output member, with the holding member and biasing member omitted. Figure 6 is a front view showing the engaging element removed.

[0028] A motor 1 with a reverse input blocking clutch and a steering device 2 according to one embodiment of the present disclosure will be described with reference to Figures 1 to 6.

[0029] [Motor with reverse input blocking clutch] The motor with reverse input blocking clutch 1 in this example comprises a motor 3, a controller 4, and a reverse input blocking clutch 5. The motor with reverse input blocking clutch 1 is supported by a structural element that does not rotate even during use, among the various mechanical devices into which the motor with reverse input blocking clutch 1 is incorporated.

[0030] <Motor> Motor 3 rotates the input member 8 of the reverse input blocking clutch 5. Motor 3 has a motor output shaft 6. Motor 3 is not limited to this, but can be made up of, for example, a servo motor, a stepping motor, etc.

[0031] <Controller> Controller 4 controls the rotation of the motor output shaft 6. Specifically, controller 4 is configured to control the rotation direction, rotation speed, and rotation amount of the motor output shaft 6 based on external inputs such as the amount of steering wheel operation by the driver. Controller 4 is not limited to this, but can be configured with a microcontroller such as an ECU (Electronic Control Unit).

[0032] <Reverse Input Blocking Clutch> The reverse input blocking clutch 5 comprises a stationary member 7 that does not rotate during use, an input member 8 that is rotationally driven by the motor output shaft 6, an output member 9 that is connected to an output-side mechanism such as a reduction gear so as to be able to transmit torque, an engaging element 10, and a lubricant that lubricates the space between the stationary member 7 and the engaging element 10. Note that the illustration of the lubricant is omitted. When rotational torque is input from the motor output shaft 6 to the input member 8, the reverse input blocking clutch 5 transmits the rotational torque input to the input member 8 to the output member 9. Conversely, when rotational torque is input in reverse from the output-side mechanism to the output member 9, the engaging element 10 engages with the stationary member 7, thereby locking or partially locking the rotation of the output member 9.

[0033] As long as it has such a function, the structure of the reverse input blocking clutch 5 is arbitrary, and a reverse input blocking clutch of known structure, including the reverse input blocking clutch described in Japanese Patent Application Publication No. 2007-232095 and International Publication No. 2019 / 026794, can be adopted.

[0034] In this example, the motor 1 with a reverse input blocking clutch transmits the rotational torque input to the input member 8 to the output member 9 through the reverse input blocking function of the reverse input blocking clutch 5, while the rotational torque input in reverse to the output member 9 is completely blocked and not transmitted to the input member 8, or only a portion of it is transmitted to the input member 8 and the rest is blocked. The motor 1 with a reverse input blocking clutch can be suitably applied as a drive motor for various mechanical devices, including mechanical devices that constitute an automobile, such as the steering device 2. In the following description, although not limited to this, we will refer to an example in which the motor 1 with a reverse input blocking clutch is applied to the drive motor of the rear wheel steering device 2 shown in Figure 1.

[0035] [Controller Warm-up Function] The motor 1 with reverse input cutoff clutch in this example is characterized in that the controller 4 has a warm-up function. This warm-up function raises the temperature of the lubricant based on inputting rotational torque from the motor output shaft 6 of the motor 3 to the input member 8 when predetermined conditions are met. Although not limited to these, for example, it is possible to raise the temperature of the lubricant by generating shear heat in the lubricant based on rotational driving of the input member 8 by the motor 3, or by transferring heat from the motor 3 to the lubricant via the motor output shaft 6, input member 8, and engaging element 10.

[0036] When the temperature of the environment in which the motor 1 with reverse input blocking clutch is used decreases, the temperature of the lubricant interposed between the stationary member 7 and the engaging element 10 also decreases. This can lead to an increase in the viscosity of the lubricant and a decrease in its coefficient of friction, potentially preventing the lubricant from performing as desired. In particular, when traction grease is used as the lubricant, as in this example, a decrease in temperature can cause a significant increase in viscosity and a decrease in the coefficient of friction. As a result, the engaging element 10 may become more prone to slipping against the stationary member 7, potentially preventing reliable locking or partial locking of the output member 9 when rotational torque is applied in reverse to it.

[0037] In the motor 1 with a reverse input blocking clutch, the warm-up function of the controller 4 can raise the temperature of the lubricant, allowing the lubricant to perform well even in low-temperature environments. As in this example, even when traction grease is used as the lubricant, both an increase in viscosity and a decrease in the coefficient of friction can be effectively prevented.

[0038] The direction and angle of the rotational torque input from the motor output shaft 6 to the input member 8 are not particularly limited. For example, the controller 4 can cause the motor output shaft 6 to reciprocate within a predetermined angular range while the warm-up function is running. This predetermined angular range is preferably such that it does not cause discomfort to the user of the machine incorporating the motor 1 with reverse input blocking clutch, and is appropriately determined according to the output mechanism connected to the output member 9 in a torque-transmitting manner.

[0039] In the motor 1 with reverse input blocking clutch in this example, the controller 4 raises the temperature of the lubricant by reciprocating the motor output shaft 6 within a predetermined angular range when predetermined conditions are met.

[0040] The predetermined conditions, that is, the conditions that serve as the criteria for deciding whether or not to perform the warm-up function, can be appropriately determined so that the temperature of the lubricant is at a temperature at which it can perform well, and at a temperature that does not interfere with the operation of the mechanical device incorporating the motor 1 with reverse input blocking clutch.

[0041] The motor 1 with a reverse input blocking clutch may include a thermometer 67 for measuring the temperature of at least one of the following: the space in which the reverse input blocking clutch 5 is located, the stationary member 7, and the lubricant. In this case, the predetermined condition may include that the temperature measured by the thermometer 67 is below a predetermined threshold.

[0042] The thermometer 67 is not limited in type and can be configured using a contact-type temperature sensor or a non-contact temperature sensor that uses infrared radiation, depending on the object to be measured and the installation location.

[0043] In consideration of the handleability of the thermometer 67, the thermometer 67 is preferably installed at a location that does not rotate even during use. Although not limited thereto, for example, the thermometer 67 can be installed on a part of the reverse input blocking clutch 5, for example, the stationary member 7, installed on the aforementioned structural element, or built into the motor 3. Further, an on-vehicle outside air temperature sensor can also be used as the thermometer 67.

[0044] The temperature measurement target is appropriately selected from among the space where the reverse input blocking clutch 5 is disposed, the stationary member 7, and the lubricant according to the installation location of the thermometer 67. In this example, the thermometer 67 is configured by a contact-type temperature sensor and installed on the stationary member 7. Specifically, the thermometer 67 is fixed to a portion of the inner peripheral surface of the stationary member 7 that is near the engagement element 10 and does not interfere with the engagement element 10 by adhesion or the like. In this case, the thermometer 67 can measure the temperature of any measurement target, but in this example, it measures the temperature of the stationary member 7. Additionally or alternatively, the thermometer 67 can be installed on an axial end surface or an outer peripheral surface of the stationary member 7.

[0045] The predetermined threshold can be appropriately determined according to the type of lubricant. For example, for traction grease, although not limited thereto, the predetermined threshold can be set to any temperature within a range of 0°C or higher.

[0046] The predetermined condition is not limited to temperature, and additionally or alternatively, it can include that a mechanical device incorporating the motor 1 with a reverse input blocking clutch is in an idle state, that is, a standby state that can immediately respond to movement. For example, when the motor 1 with a reverse input blocking clutch is incorporated in a mechanical device constituting an automobile such as a steering device 2, the condition can be that it is immediately after the ignition switch is turned on, or that the shift lever is selected to the P range. Additionally or alternatively, the configuration can also be such that whether to execute the warm-up operation function can be switched by a switch operation performed by a user, a driver, or the like.

[0047] Any of the above conditions can be employed as the predetermined condition. However, from the perspective of appropriately exerting the warm-up operation function, it is preferable to execute the warm-up operation function on the condition that any combination of these conditions, for example but not limited to, both the temperature of a space where the reverse input blocking clutch 5 is disposed, the stationary member 7, the lubricant, and the like, and the fact that the mechanical device incorporating the motor 1 with the reverse input blocking clutch is in an idle state are satisfied.

[0048] Execution of the warm-up operation function can be terminated when an arbitrarily set termination condition is satisfied. For example, execution of the warm-up operation function can be terminated when the temperature measured by the thermometer 67 reaches a target temperature after the warm-up operation function is started. As the target temperature, for example, the aforementioned threshold value, or a temperature obtained by adding a predetermined temperature to the aforementioned threshold value, or the like can be employed.

[0049] Alternatively, execution of the warm-up operation function can be terminated when a predetermined period of time has elapsed after the start, or when the number of times the motor output shaft 6 is reciprocally rotated within a predetermined angular range reaches a predetermined number of times. In this case, the predetermined period of time or the predetermined number of times can also be changed in accordance with the temperature measured by the thermometer 67 at the start of execution of the warm-up operation function. For example, the predetermined period of time or the predetermined number of times can also be set so as to stepwise or continuously increase as the temperature becomes lower.

[0050] In the present example, the predetermined condition is that the temperature measured by the thermometer 67 is equal to or lower than a predetermined threshold, and the mechanical device incorporating the motor 1 with the reverse input blocking clutch is in an idle state. Furthermore, execution of the warm-up operation function is configured to be terminated when the temperature measured by the thermometer 67 reaches the target temperature after the start.

[0051] [Specific Structure of Reverse Input Blocking Clutch] In the motor 1 with reverse input blocking clutch of the present example, as described above, the structure of the reverse input blocking clutch 5 is arbitrary and is not limited by the structure thereof. Hereinafter, a specific structure of the reverse input blocking clutch 5 that is suitably applied to the motor 1 with reverse input blocking clutch of the present example will be described in detail.

[0052] In the following description, unless otherwise specified, the axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the pressed surface 11 of the stationary member 7 of the reverse input shutoff clutch 5. The axial, radial, and circumferential directions of the pressed surface 11 coincide with the axial, radial, and circumferential directions of the input member 8, and also coincide with the axial, radial, and circumferential directions of the output member 9. Furthermore, one axial side refers to the input member 8 side (right side in Figures 1 and 2), and the other axial side refers to the output member 9 side (left side in Figures 1 and 2).

[0053] The direction of the pressing surface 36 of the engaging element 10 relative to the pressed surface 11 is defined as the first direction (up and down direction in Figures 3 to 6), and the direction perpendicular to both the axial direction of the pressed surface 11 and the first direction is defined as the second direction (left and right direction in Figures 3 to 6). With respect to the engaging element 10, the direction coinciding with the first direction is defined as its radial direction (direction indicated by arrow A in Figure 4), and the direction coinciding with the second direction is defined as its width direction (direction indicated by arrow B in Figure 4). Furthermore, with respect to the width direction of the engaging element 10, the inside refers to the center side of the engaging element 10 in the width direction, and the outside refers to both sides of the engaging element 10 in the width direction.

[0054] (Standing member) The standing member 7 has a pressing surface 11 on its inner circumferential surface.

[0055] The stationary member 7 is supported and fixed to the structural element, or is provided integrally with the structural element, so that its rotation is restrained even during use.

[0056] The pressed surface 11 constitutes the surface that contacts the pressing surface 36 of the engaging element 10 when the engaging element 10 moves radially outward, which is the direction towards the pressed surface 11. The shape of the stationary member 7 is not limited as long as it is configured to have the pressed surface 11 on its inner circumferential surface. The pressed surface 11 is annular when viewed from the axial direction. In addition, although not limited to this, the pressed surface 11 has a cylindrical shape in which the inner diameter does not change with respect to the axial direction.

[0057] The input-side engaging portion 18 of the input member 8 and the output-side engaging portion 24 of the output member 9 are positioned radially inward of the pressed surface 11. The input-side engaging portion 18, the output-side engaging portion 24, and the engaging element 10 are rotatable radially inward of the pressed surface 11.

[0058] When the stationary member 7 is supported and fixed to the structural element, known means can be used. As in this example, the stationary member 7 may include a housing element 12 as any element supported and fixed to the structural element.

[0059] The housing element 12 has a stepped cylindrical inner surface, which is formed by connecting a large-diameter cylindrical surface portion 13 on one axial side and a small-diameter cylindrical surface portion 14 on the other axial side with a connecting surface portion 15 facing one axial side. The large-diameter cylindrical surface portion 13 constitutes the pressed surface 11.

[0060] The housing element 12 has an inwardly projecting flange portion 16 at the axial end of the small-diameter cylindrical surface portion 14, projecting radially inward, and has screw holes 17 opening at multiple locations in the circumferential direction on the side surface on the axial side. The stationary member 7 is supported and fixed to the structural element by screwing bolts, which are inserted through holes provided in the structural element, into the screw holes 17.

[0061] The stationary member 7 may also include another housing element that closes the opening on one axial side of the housing element 12. In this case, the stationary member 7 is constructed by fitting the other housing element to the axial end of the housing element 12 without any play (spigot fitting), thereby positioning the housing element 12 and the other housing element radially, and then connecting the housing element 12 and the other housing element with a connecting member such as a bolt.

[0062] (Input Member) The input member 8 has an input-side engaging portion 18 located radially inward of the pressed surface 11 and is arranged coaxially with the pressed surface 11. Specifically, the input member 8 can be fixed to the motor output shaft 6 as in this example, or it can be made up of the motor output shaft 6. Alternatively, the input member 8 can be connected to the motor output shaft 6 via a reduction gear so as to be able to transmit torque.

[0063] The input-side engaging portion 18 is provided on a part of the input member 8 that is radially outward from the center of rotation and has a portion that contacts and engages with the input-side engaged portion 37 of the engaging element 10. The input-side engaging portion 18 is configured so that, as the input member 8 or the engaging element 10 rotates, its radially inner surface 19 contacts and engages with the radially inner surface of the input-side engaged portion 37.

[0064] The outer circumferential surface of the input-side engaging portion 18 can have any configuration as long as it has a portion that engages with the input-side engaged portion 37. For example, it can have an end face shape such as a substantially fan-shaped, substantially trapezoidal, or arched shape, where the circumferential width increases towards the radially outward direction when viewed from the axial direction. From the standpoint of reducing the manufacturing cost of the input member 8, it is preferable, as in this example, that the outer circumferential surface of the input-side engaging portion 18 has an arched end face shape, consisting only of a flat radially inward surface 19 and a partially cylindrical radially outward surface 20 centered on the central axis of the input member 8.

[0065] In the reverse input blocking clutch 5 of this example, the radial inner surface 19 and the radial outer surface 20 are connected by a pointed ridge 21. Therefore, when manufacturing the input member 8 having the input-side engaging portion 18, it is not necessary to perform machining on the connection between the radial inner surface 19 and the radial outer surface 20 of the input-side engaging portion 18. For example, the input member 8 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. However, the input member 8 can also be manufactured by machining a metal material, including cutting. Furthermore, the radial inner surface 19 and the radial outer surface 20 can also be connected by chamfered portions such as corner chamfers and rounded chamfers.

[0066] In this example, the input member 8 has, in addition to the input-side engaging portion 18, an input shaft portion 22 and an input flange portion 23.

[0067] The input shaft portion 22 has a cylindrical or columnar shape depending on the shape of the motor output shaft 6. In this example, the input shaft portion 22 has a cylindrical shape and is fixed to the motor output shaft 6.

[0068] The input flange portion 23 is an element for positioning the input-side engaging portion 18 at a location radially outward from the rotation center of the input member 8. The input flange portion 23 can be fixed to the output shaft of the input-side mechanism or to the input shaft portion 22, or it can be integrally formed with it. In this example, the input flange portion 23 protrudes radially outward from the outer circumferential surface of the other axial end of the input shaft portion 22 over its entire circumference.

[0069] The input-side engaging portion 18 protrudes axially toward the other side from the side surface of the input flange portion 23 that is radially outward from the center of rotation.

[0070] The number of input-side engaging portions 18 is determined according to the number of engaging elements 10. If the engaging element 10 is composed of multiple engaging elements 10, the input-side engaging portions 18 are also composed of multiple input-side engaging portions 18. In the reverse input shut-off clutch 5 of this example, the engaging element 10 is composed of two engaging elements 10. Therefore, the input-side engaging portions 18 are also composed of two input-side engaging portions 18. The two input-side engaging portions 18 are positioned at two radially opposite locations on the other axial side of the input flange portion 23, and are spaced apart from each other with respect to the radial direction of the input member 8.

[0071] The input member 8 can be rotatably supported by the stationary member 7 or the structural element. In this example, the input shaft portion 22 of the input member 8 is fixed to the motor output shaft 6, and the motor output shaft 6 is rotatably supported by the structural element via a radial bearing (not shown) and a motor housing.

[0072] (Output Member) The output member 9 has an output-side engaging portion 24 that is located radially inward from the input-side engaging portion 18, and is arranged coaxially with the pressed surface 11. In other words, the output member 9 is also arranged coaxially with the input member 8.

[0073] The output member 9 is connected to an output-side mechanism such as a reduction gear mechanism, and is configured to output rotational torque to the output-side mechanism as it rotates. Specifically, the output member 9 can be formed from the input shaft of the output-side mechanism, or it can be formed as a separate component from the input shaft and fixed coaxially to the input shaft.

[0074] The output-side engaging portion 24 has a portion that engages with the output-side engaged portion 38 of the engaging element 10. This engaging portion is located radially inward from the input-side engaging portion 18 and radially outward from the central axis of the output member 9, and is positioned to engage with the output-side engaged portion 38 of the engaging element 10. The output-side engaging portion 24 is configured such that its outer circumferential surface contacts and engages with the output-side engaged portion 38 as the output member 9 or the engaging element 10 rotates. In this example, the axial width of the output-side engaging portion 24 is greater than the axial width of the engaging element 10.

[0075] The output-side engaging portion 24 has a cam function. The distance from the rotational center axis of the output member 9 to the outer circumferential surface of the output-side engaging portion 24, which is the part that engages with the output-side engaged portion 38, is not constant in the circumferential direction. As a result, when rotational torque is input in reverse to the output member 9, the output-side engaging portion 24 can press the engaging element 10 in the radial direction of the engaging element 10, which is the first direction, as the output member 9 rotates.

[0076] The number of parts of the output-side engaging portion 24 that engage with the output-side engaged portion 38 is determined according to the number of engaging elements 10. When the engaging element 10 is composed of multiple engaging elements 10, the output-side engaging portion 24 is also configured to have multiple engaging parts. In this example, the output-side engaging portion 24 is configured to have two parts that engage with the output-side engaged portion 38, corresponding to the number of engaging elements 10. However, even when there is only one engaging element 10, it is possible to adopt a structure similar to this example.

[0077] The outer circumferential surface of the output-side engaging portion 24 can adopt any configuration as long as the output-side engaging portion 24 has a cam function, and its shape is appropriately set according to the number of portions of the output-side engaging portion 24 that engage with the output-side engaged portion 38. When there are portions that engage with two output-side engaged portions 38, the output-side engaging portion 24 can be, for example, roughly rectangular, roughly oval, parallelogram, or trapezoidal in shape. However, from the viewpoint of reducing the manufacturing cost of the output member 9, it is preferable that the outer circumferential surface of the output member 9 has a flat surface portion 25 in the portion that engages with the output-side engaged portion 38, and it is even more preferable that it is composed of a flat surface portion 25 and a partially cylindrical surface portion 26 centered on the central axis of the output member 9. In this example, the portion of the flat surface portion 25 located in the axial middle and widthwise middle constitutes the portion that engages with the output-side engaged portion 38.

[0078] In this example, the outer circumferential surface of the output-side engaging portion 24 is composed of two parallel flat surfaces 25 and two partially cylindrical surfaces 26. The output-side engaging portion 24 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 9 and is perpendicular to the two flat surfaces 25. Furthermore, the output-side engaging portion 24 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 9 and is parallel to the two flat surfaces 25. In other words, the output-side engaging portion 24 has a shape that is symmetrical twice with respect to the central axis of the output member 9.

[0079] The flat surface portion 25 and the partially cylindrical surface portion 26 are connected by a pointed edge portion 66. Therefore, when manufacturing the output member 9 having the output-side engaging portion 24, it is not necessary to perform machining on the portion of the output-side engaging portion 24 that engages with the output-side engaged portion 38. For example, the output member 9 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. However, the output member 9 can also be manufactured by machining a metal material, including cutting. Furthermore, the flat surface portion 25 and the partially cylindrical surface portion 26 can also be connected by chamfered portions such as C-chamfers and R-chamfers.

[0080] The output-side engaging portion 24 is positioned radially inward of the input-side engaging portion 18. When the engaging element 10 consists of two engaging elements 10, the output-side engaging portion 24 is positioned between the output-side engaged portions 38 of the two engaging elements 10.

[0081] The output member 9 can be rotatably supported by the stationary member 7 or the structural element via a rolling bearing or the like.

[0082] In this example, the output member 9 has, in addition to the output-side engaging portion 24, an output shaft portion 27, an output flange portion 28, and a small-diameter shaft portion 29.

[0083] The output shaft portion 27 is formed by the input shaft of the output mechanism, or, as in this example, if the output member 9 is configured as a separate component from the input shaft, it can be fixed coaxially to the input shaft, etc. In this example, the output shaft portion 27 has a stepped cylindrical shape.

[0084] The output flange portion 28 protrudes radially outward from the outer circumferential surface of one axial end of the output shaft portion 27 over its entire circumference. The output flange portion 28 is an element for attaching the output member 9 to the stationary member 7 or the structural element so that it can rotate and cannot be displaced in the axial direction.

[0085] The output-side engaging portion 24 protrudes from the center of the end face on one axial side of the output shaft portion 27 toward the axial side.

[0086] The small-diameter shaft portion 29 has a cylindrical shape and protrudes from the center of the axial end face of the output-side engaging portion 24 toward the axial direction toward the axial direction. The small-diameter shaft portion 29 is an element that ensures the coaxiality of the output member 9 with respect to the input member 8. The small-diameter shaft portion 29 is freely supported in relative rotation with respect to the input member 8 by a sliding bearing (sleeve) 35 inside the input member 8.

[0087] In this example, the output member 9 is rotatably supported radially inward of the housing element 12 of the stationary member 7 by a radial rolling bearing 30. The outer ring 31 of the radial rolling bearing 30 is fitted snugly into the small-diameter cylindrical surface portion 14 of the housing element 12 and is axially clamped between the side surface on one axial side of the inward flange portion 16 and a retaining ring 32a that is locked to the axial end of the small-diameter cylindrical surface portion 14. The inner ring 33 of the radial rolling bearing 30 is fitted snugly onto the axial end of the output shaft portion 27 and is axially clamped between the side surface on the other axial side of the output flange portion 28 and a retaining ring 32b that is locked to the outer circumferential surface of the axial intermediate portion of the output shaft portion 27.

[0088] The radial rolling bearing 30 can be constructed as a ball bearing using balls as rolling elements 34, as in this example, or as a tapered roller bearing using tapered rollers or a roller bearing using cylindrical rollers.

[0089] (Engaging element) The engaging element 10 has a pressing surface 36 facing the pressed surface 11, an input-side engaged portion 37 that can engage with the input-side engaging portion 18, and an output-side engaged portion 38 that can engage with the output-side engaging portion 24, and is arranged to allow radial movement of the engaging element 10.

[0090] As shown in Figures 4 and 5, the engaging element 10 is configured such that when rotational torque is input to the input member 8, the input-side engaging portion 18 engages with the input-side engaged portion 37, moves radially away from the pressed surface 11, and engages the output-side engaged portion 38 with the output-side engaging portion 24. When rotational torque is input in reverse to the output member 9, the output-side engaging portion 24 engages with the output-side engaged portion 38, pressing the pressing surface 36 against the pressed surface 11, causing the pressing surface 36 to frictionally engage with the pressed surface 11. The shape and dimensions of the engaging element 10 are restricted so that these functions can be achieved. Note that in Figures 4 and 5, the radial gap between the input member 8 and the output member 9 and the engaging element 10 is exaggerated.

[0091] The pressing surface 36 is provided on the radially outer surface of the engaging element 10 facing the pressed surface 11. In this example, the pressing surface 36 is composed of two pressing surfaces 36 provided at two positions on the radially outer surface of the engaging element 10 that are spaced apart from each other in the circumferential direction. Each pressing surface 36 is composed of a partially cylindrical convex curved surface having a radius of curvature smaller than the radius of curvature of the pressed surface 11.

[0092] Of the radially outer surface of the engaging element 10, the portion that is circumferentially away from the two pressing surfaces 36 is located radially inward from a virtual circle that is centered on the central axis of the input member 8 and tangent to the two pressing surfaces 36, when viewed from the axial direction. In other words, when the two pressing surfaces 36 are in contact with the surface to be pressed 11, the portion that is circumferentially away from the two pressing surfaces 36 does not come into contact with the surface to be pressed 11.

[0093] The pressing surface 36 preferably has a surface property that results in a higher coefficient of friction with respect to the pressed surface 11 than the other parts of the engaging element 10. Furthermore, the pressing surface 36 can be integrally formed with the other parts of the engaging element 10, or it can be formed from the surface of a friction material fixed to the other parts of the engaging element 10 by adhesive or bonding.

[0094] The input-side engaged portion 37 has a shape and size that allows the input-side engaged portion 18 to be loosely inserted. The input-side engaged portion 37 can be formed by a through hole that penetrates the engaging element 10 axially, located in the radially intermediate portion of the widthwise center of the engaging element 10, a recess that opens on the other axial side of the engaging element 10, or a recess that opens on the radially outer surface of the engaging element 10. More specifically, a part of the radially inner surface 41 of the input-side engaged portion 37 contacts and engages with the radially inner surface 19 of the input-side engaged portion 18 as the input member 8 or the engaging element 10 rotates.

[0095] In this example, although not limited thereto, the input-side engaged portion 37 has a substantially arc-shaped opening when viewed from the axial direction and is composed of a through hole that penetrates the radially intermediate portion of the central position in the width direction of the engaging element 10 in the axial direction.

[0096] The input-side engaged portion 37 is sized to allow the input-side engaged portion 18 to be loosely inserted. Therefore, when the input-side engaged portion 18 is inserted inside the input-side engaged portion 37, there are gaps between the input-side engaged portion 18 and the inner surface of the input-side engaged portion 37 in the width direction and radial direction of the engaging element 10. As a result, the input-side engaged portion 18 can be displaced relative to the input-side engaged portion 37 in the rotational direction of the input member 8, and the input-side engaged portion 37 can be displaced relative to the input-side engaged portion 18 in the radial direction of the engaging element 10.

[0097] The shape of the radially outer surface 43 facing radially inward on the inner surface of the input-side engaged portion 37 is arbitrary, but in this example, the radially outer surface 43 is composed of a curved surface having a substantially arc-shaped contour when viewed from the axial direction, or a composite surface having a substantially V-shaped contour. The circumferential surface 45 connecting the radially inner surface 41 and the radially outer surface 43 is composed of a partially cylindrical concave curved surface.

[0098] The output-side engaged portion 38 is provided at the center of the width direction on the radially inner surface of the engaging element 10. The shape of the output-side engaged portion 38 is not limited as long as it is configured to engage with the output-side engaged portion 24. In this example, the output-side engaged portion 38 is provided at the center of the width direction on the radially inner surface of the engaging element 10 so as to protrude radially inward from the portions adjacent to it on both sides in the width direction.

[0099] The engaging element 10 can be composed of one engaging element 10 or two or more engaging elements 10, as long as it has the configuration described above. In this example, the engaging element 10 is composed of two engaging elements 10. Each engaging element 10 has the function of an engaging element 10.

[0100] The engaging element 10 can be manufactured by any method. For example, the engaging element 10 can be manufactured by pressing, sintering, forging, casting, or machining. From the standpoint of reducing the manufacturing cost of the engaging element 10, it is preferable that the engaging element 10 is a press-formed product of a metal sheet manufactured by pressing, as in this example.

[0101] The shape of the engaging element 10 is arbitrary as long as it has a pressing surface 36, an input-side engaged portion 37, and an output-side engaged portion 38, and can achieve the above-described function. In this example, since the engaging element 10 is composed of two engaging elements 10, each engaging element 10 has a substantially semicircular end face shape when viewed from the axial direction and has a shape that is symmetrical with respect to the width direction.

[0102] The engaging element 10 may optionally have convex curved surfaces 39 and 40 on at least one of the parts of the input-side engaged portion 37 that engages with the input-side engaging portion 18, and the output-side engaged portion 38 that engages with the output-side engaging portion 24. In this case, when the reverse input blocking clutch 5 is operated, it is possible to bring the convex curved surface 39 of the input-side engaged portion 37 into contact with the radially inner surface 19 of the input-side engaged portion 18, or to bring the convex curved surface 40 of the output-side engaged portion 38 into contact with the flat surface 25 of the output-side engaging portion 24. This makes it possible to keep the contact pressure between the input member 8 or output member 9 and the engaging element 10 low.

[0103] The convex curved surface portion 39 is provided on the radially inner surface 41 of the inner surface of the input-side engaged portion 37 that faces radially outward, specifically on the portion that engages with the input-side engaged portion 18, and more precisely, on the portion that engages with the radially inner surface 19, so as to be convex toward the input-side engaged portion 18. The convex curved surface portion 39 is provided at two locations on the radially inner surface 41: the portion that engages with the input-side engaged portion 18 when the input member 8 rotates to one side relative to the engaged element 10, and the portion that engages with the input-side engaged portion 18 when the input member 8 rotates to the other side relative to the engaged element 10.

[0104] Specifically, the radial inner surface 41 of the input-side engaged portion 37 is provided with a convex portion 42 that protrudes radially outward from the adjacent portions on both sides in the second direction, and convex curved surface portions 39 are provided at two locations in the second direction of the convex portion 42. The convex portion 42 has a connecting surface portion 44 formed by a flat surface perpendicular to the first direction in the second direction intermediate portion between the two convex curved surface portions 39.

[0105] The shape and radius of curvature of the convex curved surface portion 39 as viewed from the axial direction are not particularly limited, as long as it is possible to prevent the contact pressure at the contact point with the input-side engaging portion 18 from becoming excessive. For example, the shape of the convex curved surface portion 39 as viewed from the axial direction can be a roughly circular arc, a roughly elliptical arc, etc. The shape and radius of curvature of the convex curved surface portion 39 as viewed from the axial direction can be determined by experiment, simulation, etc.

[0106] The convex curved portion 40 is provided so as to be convex toward the output-side engaging portion 24 at two locations: the portion of the output-side engaging portion 38 that engages with the output-side engaging portion 24 when the output member 9 rotates to one side relative to the engaging element 10, specifically the portion that engages with the flat surface portion 25, and the portion of the output-side engaging portion 38 that engages with the output-side engaging portion 24 when the output member 9 rotates to the other side relative to the engaging element 10. The output-side engaging portion 38 has a connecting surface portion 46 formed by a flat surface perpendicular to the radial direction in the widthwise intermediate portion between the two convex curved portions 40.

[0107] The shape and radius of curvature of the convex curved surface portion 40 as viewed from the axial direction are not particularly limited, as long as it is possible to prevent the contact pressure at the contact point with the output side engaging portion 24 from becoming excessive. For example, the shape of the convex curved surface portion 40 as viewed from the axial direction can be a roughly circular arc, a roughly elliptical arc, etc. The shape and radius of curvature of the convex curved surface portion 40 as viewed from the axial direction can be determined by experiment, simulation, etc.

[0108] In this example, the engaging element 10 has convex curved surfaces 39 and 40 on both the portion of the input-side engaged portion 37 that engages with the input-side engaging portion 18, and the portion of the output-side engaged portion 38 that engages with the output-side engaging portion 24.

[0109] In this example, the engaging element 10 is provided with convex curved surfaces 39 and 40 to reduce the contact pressure at the contact points between the input member 8 and the output member 9 and the engaging element 10. Therefore, compared to the case where the convex curved surfaces are provided by machining the contact points of the input member 8 and the output member 9 with the engaging element 10, manufacturing costs can be reduced.

[0110] Furthermore, in this example, the engaging element 10, which has convex curved surfaces 39 and 40 at the contact points with the input member 8 and the output member to reduce contact pressure, is manufactured by press stamping. This also helps to reduce manufacturing costs.

[0111] In this example, the lubricant lubricates the space between the pressed surface 11 of the stationary member 7 and the pressed surface 36 of the engaging element 10.

[0112] (Biasing member and holding member) The reverse input blocking clutch 5 in this example may further include a biasing member 47 and a holding member 48 as optional components.

[0113] The biasing member 47 elastically biases the engaging element 10 toward the pressed surface 11. The biasing member 47 can be made of a spring such as a leaf spring, coil spring, or disc spring, or an elastic material such as rubber, elastomer, or synthetic resin. The number of biasing members 47 is not particularly limited and is appropriately determined according to the number of engaging elements 10.

[0114] In this example, the biasing member 47 is composed of two biasing members 47 positioned at two locations in the width direction between the radially inner surfaces of the two engaging elements 10, and each biasing member 47 is composed of a compression coil spring. Each biasing member 47 is fitted and held in the holding hole 49 of the holding member 48, thereby preventing it from falling out from the portion between the two engaging elements 10.

[0115] The two biasing members 47 elastically bias the two engaging elements 10 toward the pressed surface 11 by the force that attempts to restore them elastically. As a result, in a neutral state where no torque is applied to either the input member 8 or the output member 9, the pressing surfaces 36 of the two engaging elements 10 come into contact with the pressed surface 11.

[0116] The retaining member 48 comprises a first spacer portion 50 and a second spacer portion 51 arranged spaced apart in the axial direction, and two connecting portions 52 arranged on both sides of the first spacer portion 50 and the second spacer portion 51 with respect to a second direction, each connecting the first spacer portion 50 and the second spacer portion 51, and each having a retaining hole 49 extending in the first direction.

[0117] The retaining member 48 is attached to the output member 9 with the engaging element 10 positioned between the first spacer portion 50 and the second spacer portion 51 in the axial direction, thereby restricting the axial movement of the engaging element 10 relative to the output member 9. Specifically, the retaining ring 53, which is locked to the small-diameter shaft portion 29 of the output member 9, restricts the movement of the retaining member 48 to one side in the axial direction, and the other side of the second spacer portion 51 is brought into contact with or close to the end face of the output shaft portion 27 on one side in the axial direction, thereby restricting the movement of the retaining member 48 to the other side in the axial direction.

[0118] <Explanation of the operation of the reverse input blocking clutch> When rotational torque is input to the input member 8, the engaging element 10 moves away from the pressed surface 11, regardless of the rotation direction of the input member 8 (counterclockwise in the example of Figure 4).

[0119] More specifically, as shown in Figure 4, the input-side engaging portion 18 rotates inside the input-side engaged portion 37 in the rotational direction of the input member 8 (counterclockwise in the example of Figure 4). As a result, the gap between the radial inner surface 19 of the input-side engaging portion 18 and the radial inner surface 41 of the input-side engaged portion 37 decreases, and the radial inner surface 19 of the input-side engaging portion 18 comes into contact with the radial inner surface 41 of the input-side engaged portion 37. In this example, the radial inner surface 19 of the input-side engaging portion 18 comes into contact with one of the two convex curved surfaces 39 provided on the input-side engaged portion 37.

[0120] From this state, as the input member 8 rotates further, the radially inner surface 19 of the input-side engaging portion 18 presses one of the convex curved portions 39 radially inward, causing the engaging element 10 to move away from the pressed surface 11, and bringing the output-side engaged portion 38 into contact with the output-side engaging portion 24. In this example, the two engaging elements 10 move radially inward, moving closer to each other, and the output-side engaged portions 38 of the two engaging elements 10 clamp the output-side engaging portion 24 of the output member 9 from both radial sides.

[0121] Furthermore, the output member 9 is rotated so that the flat surface portion 25 of the output-side engaging portion 24 is parallel to the connecting surface portion 46 of the output-side engaged portion 38, thereby engaging the output-side engaging portion 24 and the output-side engaged portion 38 without any rattle.

[0122] When rotational torque is input in reverse to the output member 9, the engaging element 10 moves toward the pressed surface 11, regardless of the rotation direction of the output member 9 (clockwise in the example of Figure 5). Specifically, as shown in Figure 5, the output-side engaging portion 24 rotates in the rotation direction of the output member 9 (clockwise in the example of Figure 5). The output-side engaging portion 24 then presses the output-side engaged portion 38 radially outward. In this example, the flat surface portion 25 of the outer circumferential surface of the output-side engaging portion 24 presses one of the two convex curved surface portions 40 provided on the output-side engaged portion 38 radially outward. As a result, the pressing surface 36 is pressed against the pressed surface 11.

[0123] In this example, the two engaging elements 10 move radially outward, away from each other, based on their engagement with the output member 9, so that the pressing surfaces 36 of the two engaging elements 10 are pressed against the pressed surface 11 and frictionally engage with the pressed surface 11.

[0124] Locking or semi-locking the rotation of the output member 9 is switched according to the state of the engaging element in the frictional engagement state between the pressing surface 36 and the pressed surface 11. That is, when the engaging element 10 is braced between the output-side engaging part 24 and the stationary member 7 so that the pressing surface 36 does not slide against the pressed surface 11, the relative rotation of the engaging element 10 with respect to the stationary member 7 is prevented, and the output member 9 is locked. On the other hand, when the engaging element 10 is braced between the output-side engaging part 24 and the stationary member 7 so that the pressing surface 36 can slide against the pressed surface 11, the relative rotation of the engaging element 10 with respect to the stationary member 7 is permitted, and the output member 9 is semi-locked.

[0125] In the reverse input blocking clutch 5 of this example, the size of the gaps between each component is adjusted so that the above operation is possible. In particular, when the pressing surfaces 36 of the two engaging elements 10 are in contact with the pressed surface 11, a gap exists between the radially inner surface 19 of the input-side engaging portion 18 and the protrusion 42 of the input-side engaged portion 37.

[0126] This prevents the radially outward movement of the engaging element 10 from being blocked by the input-side engaging portion 18 when rotational torque is input in reverse to the output member 9, and also ensures that even after the pressing surface 36 contacts the pressed surface 11, the surface pressure acting on the contact portion between the pressing surface 36 and the pressed surface 11 changes according to the magnitude of the rotational torque input in reverse to the output member 9, thereby ensuring that the output member 9 is properly locked or partially locked.

[0127] [Steering Device] As described above, the motor 1 with reverse input blocking clutch in this example can be suitably applied as a drive device for various mechanical devices such as the steering device 2. When the motor 1 with reverse input blocking clutch in this example is applied to the steering device 2, it may be applied to either the drive motor for the rear wheel steering device or the drive device for the front wheel steering motor.

[0128] The steering device 2 to which the motor 1 with reverse input blocking clutch of this example is applied will be described below, using a steering device for the rear wheels as an example. The steering device 2 is equipped with a motor 1 with a reverse input blocking clutch as a drive motor, which enables the steering wheel 54 to be given a steering angle according to the amount of steering wheel operation, and prevents the transmission of shock torque due to the steering wheel 54 riding up on a curb, vibrations from the road surface, etc., to the motor 3.

[0129] The steering device 2 includes a motor 1 with a reverse input blocking clutch, as well as a linear motion mechanism 55.

[0130] The linear motion mechanism 55 has a rod 56 that converts the rotational motion of the output member 9 into linear motion in the axial direction of the rod 56. The rod 56 is supported so as to enable its linear motion in the axial direction and is connected to the steering wheel 54 such that the orientation of the steering wheel 54 changes in accordance with the linear motion. The rod 56 is usually positioned with its axial direction in the width direction of the vehicle body.

[0131] The base end of a tie rod 57 is connected to the axial end of a rod 56 via a spherical joint (not shown), and the base end of a knuckle arm 58 is pivotably supported at the tip of the tie rod 57. The knuckle, which constitutes the suspension system, is supported at the tip of the knuckle arm 58 so as to be able to pivot around a kingpin. The steering wheel 54 is rotatably supported on the knuckle via a hub unit bearing.

[0132] The steering wheels 54 are composed of a pair of left and right steering wheels 54. As in this example, a configuration can be adopted in which the pair of left and right steering wheels 54 are connected to both axial ends of the rod 56. Alternatively, two steering devices can be assembled to the vehicle such that the axial end of the rod 56 of one steering device 2 is connected to the left steering wheel 54 of the pair of left and right steering wheels 54, and the axial end of the rod 56 of the other steering device 2 is connected to the right steering wheel 54.

[0133] The linear motion mechanism 55 can employ any structure as long as it can convert the rotational motion of the output member 9 into linear motion in the axial direction of the rod 56.

[0134] For example, the linear motion mechanism 55 can be configured to include a sliding screw type or a ball type lead screw mechanism 59. When the linear motion mechanism 55 is configured to include a sliding screw type lead screw mechanism, the lead screw mechanism 59 is configured by screwing together an internal screw groove formed on the inner circumferential surface of a nut, which is rotationally driven by the output member 9, and an external screw groove formed on the outer circumferential surface of a rod 56, so as to be in sliding contact. When the linear motion mechanism 55 is configured to include a ball type lead screw mechanism, the lead screw mechanism 59 is configured by arranging a plurality of balls 61 so as to be able to roll between an internal ball screw groove formed on the inner circumferential surface of a ball nut 60, which is rotationally driven by the output member 9, and an external ball screw groove formed on the outer circumferential surface of a rod 56.

[0135] When the linear motion mechanism 55 is configured to include a lead screw mechanism 59, it is preferable to use a ball-type lead screw mechanism as the lead screw mechanism 59, as in this example, because it has higher torque transmission efficiency and makes it easier to miniaturize the motor 3 compared to a sliding screw type lead screw mechanism.

[0136] In this example, the ball-type feed screw mechanism 59 includes a rod 56, a ball nut 60, and a plurality of balls 61.

[0137] The rod 56 has a helical male ball screw groove on its outer surface.

[0138] The ball nut 60 has a helical female ball screw groove on its inner circumferential surface and is supported around the rod 56 so that it can only rotate. The ball nut 60 is rotationally driven by the output member 9 of the motor 1 with a reverse input blocking clutch.

[0139] The ball nut 60 is rotationally driven by the output member 9 via the torque transmission mechanism 62. In other words, the steering device 2 in this example includes a torque transmission mechanism 62 that transmits the rotational motion, or in other words the torque, of the output member 9 of the motor 1 with reverse input blocking clutch to the ball nut 60, which is the torque input part of the linear motion mechanism 55.

[0140] The torque transmission mechanism 62 includes a drive gear 63 fitted and fixed to the output shaft portion 27 of the output member 9, an intermediate gear 64 that meshes with the drive gear 63, and a driven gear 65 provided around the ball nut 60 and that meshes with the intermediate gear 64. In other words, in this example, the torque transmission mechanism 62 is composed of a gear-type reduction gear.

[0141] Alternatively, the drive gear 63 provided on the output member 9 of the motor 1 with reverse input blocking clutch and the driven gear 65 provided on the ball nut 60 can be directly meshed, or two or more intermediate gears 64 can be provided. Or, the torque transmission mechanism for transmitting the rotational motion of the output member 9 to the ball nut 60 can be configured with a reduction gear using a belt or chain, or with a worm gear reduction gear.

[0142] Multiple balls 61 are arranged to roll freely in a load path consisting of a male ball screw groove in the rod 56 and a female ball screw groove in the ball nut 60. The start and end points of the load path are connected by a circulation path provided on the outer surface of the rod 56, on the inner surface of the ball nut 60, or on a circulation component fixed to the ball nut 60.

[0143] In this example, when the steering device 2 applies a steering angle to the steering wheel 54, sensors detect the amount and speed of rotation of the steering wheel of a steering device (not shown), the vehicle speed, and the surrounding conditions. Based on this sensor information, the controller 4 controls the amount and direction of current supplied to the motor 3. As a result, when the input member 8 is rotated, the lock of the reverse input blocking clutch 5 is released, as shown in Figure 4, and the rotation of the input member 8 is transmitted to the output member 9.

[0144] The rotation of the output member 9 is transmitted to the ball nut 60 by the torque transmission mechanism 62, and as the ball nut 60 rotates, the rod 56 moves linearly in the axial direction, pushing and pulling the tie rod 57 and applying a steering angle to the steering wheel 54.

[0145] When the steering wheel 54 hits a curb or experiences other impactful loads, or when vibrations from the road surface are transmitted to the steering wheel 54 during off-road driving, a rotational torque is reverse-input from the linear motion mechanism 55 to the output member 9 via the torque transmission mechanism 62. As shown in Figure 5, this locks the output member 9. This prevents the axial linear motion of the rod 56. As a result, even when an impactful load is applied to the steering wheel 54, no steering angle is applied to the steering wheel 54, preventing the vehicle's behavior from becoming unstable.

[0146] In the steering device 2 of this example, the controller 4 of the motor 1 with reverse input blocking clutch performs a warm-up function to raise the temperature of the lubricant by reciprocating the motor output shaft 6 within a predetermined angular range when predetermined conditions are met, that is, in this example, when the temperature obtained by the thermometer 67 installed on the stationary member 7 is below a predetermined threshold and the vehicle is in an idle state. For this reason, while the warm-up function is being performed, the steering angle of the steering wheel 54 changes from left to right without the steering wheel 54 rotating. In this example, in order to prevent wear on the tires constituting the steering wheel 54 and to prevent discomfort to the driver and other occupants, the steering angle of the steering wheel 54 is kept to a minimum while the warm-up function is being performed. That is, the predetermined angular range is set after considering the reduction ratio between the output member 9 and the ball nut 60 and the lead of the male ball screw groove of the rod 56, so that the steering angle of the steering wheel 54 can be kept to a minimum.

[0147] The steering device 2 in this example can also be equipped with a system to inform the driver that the warm-up function is in operation, or a system that prevents the vehicle from starting while the warm-up function is in operation.

[0148] 1 Motor with reverse input blocking clutch 2 Steering device 3 Motor 4 Controller 5 Reverse input blocking clutch 6 Motor output shaft 7 Stationary member 8 Input member 9 Output member 10 Engaging element 11 Pressed surface 12 Housing element 13 Large diameter cylindrical surface 14 Small diameter cylindrical surface 15 Connecting surface 16 Inward flange 17 Screw hole 18 Input side engaging part 19 Radial inner surface 20 Radial outer surface 21 Ridge 22 Input shaft 23 Input flange 24 Output side engaging part 25 Flat surface 26 Partial cylindrical surface 27 Output shaft 28 Output flange 29 Small diameter shaft 30 Radial rolling bearing 31 Outer ring 32a, 32b Retaining ring 33 Inner ring 34 Rolling element 35 Sliding bearing 36 Pressing surface 37 Input side engaged portion 38 Output side engaged portion 39 Convex curved surface portion 40 Convex curved surface portion 41 Radially inner surface portion 42 Convex portion 43 Radially outer surface portion 44 Connecting surface portion 45 Circumferential surface portion 46 Connecting surface portion 47 Biasing member 48 Holding member 49 Holding hole 50 First spacer portion 51 Second spacer portion 52 Connecting portion 53 Retaining ring 54 Steering wheel 55 Linear motion mechanism 56 Rod 57 Tie rod 58 Knuckle arm 59 Lead screw mechanism 60 Ball nut 61 Ball 62 Torque transmission mechanism 63 Drive gear 64 Intermediate gear 65 Driven gear 66 Ridge portion 67 Thermometer

Claims

1. A motor with a reverse input blocking clutch comprising: a motor having a motor output shaft; a controller for controlling the rotation of the motor output shaft; a stationary member that does not rotate during use; an input member that is rotationally driven by the motor output shaft; an output member connected to an output mechanism so as to be able to transmit torque; an engaging element; and a lubricant for lubricating the space between the stationary member and the engaging element, wherein when rotational torque is input from the motor output shaft to the input member, the controller transmits the rotational torque input to the input member to the output member, while when rotational torque is input in reverse from the output mechanism to the output member, the reverse input blocking clutch engages the engaging element with the stationary member to lock or partially lock the rotation of the output member, and the controller has a warm-up function that, when predetermined conditions are met, raises the temperature of the lubricant based on the input of rotational torque from the motor output shaft to the input member.

2. The motor with a reverse input blocking clutch according to claim 1, comprising a thermometer for measuring the temperature of at least one of the space in which the reverse input blocking clutch is located, the stationary member, and the lubricant, wherein the predetermined condition includes that the temperature measured by the thermometer is below a predetermined threshold.

3. The motor with reverse input blocking clutch according to claim 2, wherein the thermometer is installed on the stationary member.

4. The motor with a reverse input blocking clutch according to any one of claims 1 to 3, wherein the controller rotates the motor output shaft back and forth within a predetermined angular range while the warm-up function is being performed.

5. The stationary member has a pressure-receiving surface on its inner circumferential surface, the input member has an input-side engaging portion located radially inward from the pressure-receiving surface and is arranged coaxially with the pressure-receiving surface, and the output member has an output-side engaging portion located radially inward from the input-side engaging portion and is arranged coaxially with the pressure-receiving surface. The engaging element has a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and is arranged to be movable in the radial direction, and when rotational torque is input to the input member, the input-side engaging portion engages with the input-side engaged portion and moves radially away from the pressed surface, engaging the output-side engaged portion with the output-side engaging portion, and when rotational torque is input in reverse to the output member, the output-side engaging portion engages with the output-side engaged portion, pressing the pressing surface against the pressed surface and frictionally engaging the pressing surface with the pressed surface, and the lubricant lubricates the space between the pressed surface and the pressing surface, the motor with reverse input blocking clutch according to any one of claims 1 to 4.

6. A steering device comprising: a motor with a reverse input blocking clutch having an output member; and a linear motion mechanism having a rod connected to the steering wheel, which is supported to enable linear motion in the axial direction of the motor and which changes the direction of the steering wheel in accordance with the linear motion, and which converts the rotational motion of the output member into linear motion in the axial direction of the rod, wherein the motor with a reverse input blocking clutch is configured as a motor with a reverse input blocking clutch according to any one of claims 1 to 5.

7. The steering device according to claim 6, wherein the steering wheel is a rear wheel.

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