JP4535276B2 - Steering ratio change actuator - Google Patents

Description

  The present invention is provided between a first steering force transmission shaft extending obliquely downward from the center of the handle and a second steering force transmission shaft extending on a downward extension line of the first steering force transmission shaft. The present invention relates to a steering ratio change actuator that changes a transmission ratio of rotation between first and second steering force transmission shafts according to driving conditions.

Conventionally, as this type of steering ratio changing actuator, an actuator housing in which a motor and a differential reduction gear are housed is fixed to a vehicle body (see, for example, Patent Document 1).
JP 2004-175336 A (paragraph [0051], FIG. 1)

  However, in the conventional steering ratio changing actuator described above, foreign matter is caught between the connecting member connected to the output rotation portion of the differential reduction gear and the inner peripheral surface of the actuator housing, and the steering resistance of the steering wheel is reduced. There was a risk that it would be abnormally high.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering ratio changing actuator capable of suppressing an increase in steering resistance due to the biting of foreign matter.

  In order to achieve the above object, a steering ratio changing actuator according to the first aspect of the present invention includes a motor and a differential reduction gear housed in an actuator housing fixed to a vehicle body, and the differential reduction gear device is provided. A first steering force transmission shaft extending from the handle is connected to one of the pair of differential rotating portions, and a second steering force transmission shaft extending on a downward extension line of the first steering force transmission shaft is connected to the first steering force transmission shaft. The transmission ratio of rotation between the first and second steering force transmission shafts is changed by being connected to the other of the pair of differential rotation parts and driving the differential reduction gear by a motor according to the driving situation. An actuator capable of changing a steering ratio, wherein the actuator housing includes a connecting member for connecting the first or second steering force transmission shaft and the differential rotating portion in the actuator housing. Having characterized in that the loosely fitted a movable ring on the outside of the rotatably fitted and the connecting member provided on the inner peripheral surface of the chromatography data housing.

  According to a second aspect of the present invention, in the steering ratio changing actuator according to the first aspect, the disk wall is extended inward from one end of the movable ring, and the end surface of the connecting member is covered with the disk wall.

  The invention according to claim 3 is characterized in that in the steering ratio changing actuator according to claim 1 or 2, the movable ring is made of a synthetic resin.

  The invention of claim 4 is characterized in that in the steering ratio change actuator according to claim 1 or 2, the movable ring is made of a sintered material or metal having a hardness equal to or higher than that of the actuator housing.

[Invention of Claim 1]
According to the first aspect of the present invention, since the movable ring is provided between the inner peripheral surface of the actuator housing and the outer peripheral surface of the connecting member, when a foreign object is caught, the actuator housing and the connecting member It occurs between the movable ring and the connecting member, not between them. Since the movable ring is rotatably fitted to the inner peripheral surface of the actuator housing, the movable ring rotates with respect to the actuator housing, and an increase in steering resistance can be suppressed.

[Invention of claim 2]
According to the second aspect of the present invention, the disk wall is extended inward from one end of the movable ring, and the end surface of the connecting member is covered by the disk wall, so that the foreign matter is not caught between the end surface of the connecting member and the actuator housing. be able to.

[Invention of claim 3]
According to the structure of Claim 3, since the movable ring was comprised with the synthetic resin, the improvement of the slidability between a movable ring and an actuator housing is achieved. Here, the synthetic resin is preferably tetrafluoroethylene resin or nylon.

[Invention of claim 4]
According to the structure of Claim 4, since the movable ring was comprised with the sintered material or metal with high hardness, generation | occurrence | production of the biting phenomenon itself can be prevented.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS. 1 and 2.
A rack 12 is provided between a pair of front wheels 11, 11 in the vehicle 10 shown in FIG. 1, and both ends of the rack 12 are connected to the front wheels 11, 11 via tie rods 13, 13. . The rack 12 is covered with a cylindrical rack case 12 </ b> C, and the rack case 12 </ b> C is fixed to the vehicle main body 14. Further, a pinion 15 is engaged with the rack 12, and the pinion 15 is rotatably supported by the rack case 12C. The pinion 15 and the handle 17 are connected by a steering force transmission shaft 18, and a steering ratio changing actuator 20 (hereinafter simply referred to as “actuator 20”) is provided in the middle of the steering force transmission shaft 18. Yes. Specifically, the steering force transmission shaft 18 includes a first steering force transmission shaft 18A extending downward from the center of the handle 17, and a second extension extending on a downward extension line of the first steering force transmission shaft 18A. The steering force transmission shaft 18B, and the actuator 20 is connected between the first and second steering force transmission shafts 18A and 18B. A universal joint 18J is provided at each intermediate portion of the first and second steering force transmission shafts 18A and 18B.

  As shown in FIG. 2, the actuator 20 includes an actuator housing 21 having a substantially cylindrical shape. The actuator housing 21 is fixed to the vehicle main body 14 (see FIG. 1) with bolts (not shown), and the differential reduction gear 30 and the motor 40 are accommodated in the actuator housing 21.

  The motor 40 includes a motor housing 41 fitted and fixed in the actuator housing 21, and bearings 42 and 42 are held at both ends of the motor housing 41. A stator core 43 is fixed to the inner surface of the motor housing 41, and a plurality of electromagnetic coils 44 are attached to the stator core 43.

  A rotor 45 is rotatably supported inside the bearings 42 and 42. The rotor 45 has a circular tube structure as a whole, and a magnet fixing portion 46 is provided in a portion of the rotor 45 sandwiched between the bearings 42 and 42. A permanent magnet 47 is fixed to the outer peripheral surface of the magnet fixing portion 46. Thereby, when the electromagnetic coil 44 is excited, the rotor 45 rotates.

  A cylindrical portion 41A is provided on the upper end surface of the motor housing 41, and a rotational position sensor 50 (for example, a resolver) is provided inside the cylindrical portion 41A. The rotational position of the rotor 45 can be detected by the rotational position sensor 50. A lock ring 51 is fitted and fixed outside the upper end of the rotor 45. A lock arm 52 is pivotally supported on the upper surface of the motor housing 41, and the lock arm 52 can be rotated between a lock position and a lock release position by a solenoid (not shown) and a torsion spring 52S. When the lock arm 52 moves to the lock position, the leading end of the lock arm 52 engages with the outer peripheral surface of the lock ring 51 to lock the rotor 45, and when the lock arm 52 moves to the lock release position, the lock arm 52 moves. The tip of the rotor 45 is separated from the outer peripheral surface of the lock ring 51 and the rotation of the rotor 45 is allowed.

  The differential reduction gear 30 is housed below the motor 40 in the actuator housing 21. The differential reduction gear 30 corresponds to an input rotation ring 31 corresponding to “one of a pair of differential rotation portions” according to the present invention and “the other of a pair of differential rotation portions” according to the present invention. The output rotation ring 32 is arranged on the same axis. The input rotation ring 31 is disposed below the output rotation ring 32 and has an outer diameter slightly smaller than that of the output rotation ring 32. A plurality of fine teeth are formed on the inner peripheral surfaces of the input rotation ring 31 and the output rotation ring 32. For example, the number of teeth of the input rotation ring 31 is 2n teeth (hereinafter, less than the number of teeth of the output rotation ring 32). , “N” is an integer greater than or equal to 1). A flexible ring 33 is fitted inside the input rotation ring 31 and the output rotation ring 32 in common. A plurality of fine teeth that can mesh with the teeth of the input rotation ring 31 and the output rotation ring 32 are provided on the outer peripheral surface of the flexible ring 33.

  A motor input board 34 is disposed inside the flexible ring 33, and a plurality of balls 35 are accommodated between the motor input board 34 and the flexible ring 33. The outer peripheral shape of the motor input board 34 is substantially elliptical, whereby the flexible ring 33 is elastically deformed into a substantially elliptical shape corresponding to the motor input board 34, and the teeth of the flexible ring 33 and the input rotating ring 31 and The teeth of the output rotating ring 32 are engaged at two locations in the circumferential direction.

  A through hole is formed in the central portion of the motor input board 34, and the lower end portion of the rotor 45 is spline engaged therewith. When the motor input board 34 is rotated by driving the motor 40, the meshing position of the flexible ring 33, the input rotation ring 31, and the output rotation ring 32 moves in the circumferential direction, and output to the input rotation ring 31. The rotating ring 32 rotates more by the number of teeth (2n teeth). That is, the output rotation ring 32 is differential with respect to the input rotation ring 31.

  An input shaft coupling board 56 is disposed below the input rotation ring 31. The input shaft connecting board 56 has a structure in which a cylindrical protrusion 56T protrudes from the center of the lower surface of the disc body and a through hole is provided in the center. The outer diameter of the input shaft connection board 56 is slightly smaller than that of the input rotation ring 31, and the input shaft connection board 56 is connected to the input rotation ring 31 so as to be integrally rotatable. The input shaft 55 is spline-engaged with the center through hole of the input shaft coupling board 56. The input shaft 55 is loosely fitted at the center of the rotor 45, and the upper end of the input shaft 55 protrudes upward from the actuator housing 21 and is connected to the first steering force transmission shaft 18A. The input shaft 55 is rotatably supported at the upper end portion of the actuator housing 21 via a bearing 55B.

  An output shaft 80 is rotatably supported at the lower end portion of the actuator housing 21 via a bearing 80B. A portion of the output shaft 80 housed in the actuator housing 21 is provided with a disk portion 81. The disc part 81 has substantially the same diameter as the output rotation ring 32 and faces the input shaft coupling board 56 from below. A concave portion 82 that accommodates the projection 56T of the input shaft coupling board 56 is formed at the center of the disc portion 81, and a bearing 56B is provided between the inner peripheral surface of the concave portion 82 and the outer peripheral surface of the projection 56T. It has been.

  The disc part 81 of the output shaft 80 and the output rotating ring 32 of the differential reduction gear 30 are connected by a connecting member 83 according to the present invention. Specifically, the connecting member 83 has a cylindrical shape, and the lower end portion of the connecting member 83 is fitted and fixed to the outer peripheral surface of the disc portion 81, while the upper end portion of the connecting member 83 is the output rotating ring 32. The outer peripheral surface is fitted and fixed. Note that the input rotation ring 31 and the input shaft coupling board 56 are loosely fitted inside the coupling member 83.

  A movable ring 70 is accommodated in the lower end portion of the actuator housing 21. The movable ring 70 is made of, for example, a synthetic resin such as tetrafluoroethylene resin or nylon, has a cylindrical shape as a whole, and a disk wall 71 projects from the lower end of the movable ring 70 toward the inside. . Corresponding to the movable ring 70, a ring housing portion 21S is formed on the inner peripheral surface of the actuator housing 21 by slightly expanding the inner diameter of the lower end portion in a stepped manner. The movable ring 70 is accommodated in the ring accommodating portion 21S, and the inner peripheral surface of the movable ring 70 and the inner peripheral surface of the actuator housing 21 above the ring accommodating portion 21S are substantially flush with each other. The fitting between the movable ring 70 and the ring housing portion 21 </ b> S is such that the movable ring 70 can rotate with respect to the actuator housing 21. The upper end portion of the movable ring 70 is abutted against the step surface of the upper end portion of the ring accommodating portion 21 </ b> S, while the disc wall 71 is laid on the inner lower end surface of the actuator housing 21. Thereby, the movement of the movable ring 70 is restricted in the axial direction. The movable ring 70 covers the entire outside of the connecting member 83, and a gap is provided between the outer peripheral surface of the connecting member 83 and the inner peripheral surface of the movable ring 70. That is, the movable ring 70 is loosely fitted outside the output shaft 80. Further, a gap is also provided between the disk wall 71 of the movable ring 70 and the connecting member 83 and the disk part 81.

Next, the operation of the present embodiment configured as described above will be described.
When the ignition key of the vehicle 10 is turned on, the lock arm 52 enters the unlock position. When the vehicle 10 travels, the ECU 60 drives and controls the actuator 20 according to the driving condition, and changes the transmission ratio of the rotation transmitted between the first and second steering force transmission shafts 18A and 18B. Specifically, a ROM 61 (see FIG. 1) provided in the ECU 60 stores a map (not shown) in which vehicle speed and transmission ratio are associated with each other. The ECU 60 determines the transmission ratio based on the detection result of the vehicle speed sensor 62 (see FIG. 1) and this map. Then, the target rotation angle of the second steering force transmission shaft 18B is calculated from the steering angle of the handle 17 detected by the steering angle sensor 63 and the transmission ratio, and the actual rotation angle of the second steering force transmission shaft 18B is calculated. To match the target rotation angle, a drive current is supplied to the motor 40 to rotate the rotor 45.

  The map is set so that the transmission ratio decreases as the vehicle speed increases. As a result, in the low speed range, the front wheels 11, 11 can be cut with a slight steering operation, and the turning performance is improved. On the other hand, in a high speed range, so-called sudden steering is restricted, and stable running is possible.

  When the vehicle 10 stops and an abnormality occurs, the motor 40 is held so as not to rotate. When the handle 17 is steered in this state, the input rotation ring 31 of the differential reduction gear 30 rotates integrally with the handle 17. Here, since both the input rotation ring 31 and the output rotation ring 32 mesh with the flexible ring 33, both the input rotation ring 31 and the output rotation ring 32 rotate in conjunction with the handle 17 and cut the front wheel 11. be able to.

  There is a concern that foreign matter may enter the actuator 20 or foreign matter may be generated in the actuator 20 and the steering resistance of the handle 17 may increase due to the biting of the foreign matter. However, in the actuator 20 of the present embodiment, since the movable ring 70 is disposed between the inner peripheral surface of the actuator housing 21 and the outer peripheral surface of the connecting member 83, the foreign matter is caught by the actuator housing 21 and the connecting member. It occurs between the movable ring 70 and the connecting member 83, not between 83. Since the movable ring 70 is rotatably fitted to the inner peripheral surface of the actuator housing 21, the movable ring 70 rotates with respect to the actuator housing 21, and an increase in steering resistance can be suppressed. Further, since the disk wall 71 of the movable ring 70 is disposed between the connecting member 83 and the disk part 81 and the lower end surface of the actuator housing 21, an increase in the steering resistance due to the jamming of foreign matter is also suppressed here. It is done.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

(1) Although the movable ring 70 of the embodiment is made of a synthetic resin, the movable ring may be made of a sintered material (for example, ceramics) or metal having higher hardness than the actuator housing. By increasing the hardness of the movable ring in this way, the occurrence of the biting phenomenon itself can be prevented.

(2) Although the movable ring 70 of the embodiment has the disc wall 71, it may have a simple cylindrical shape without the disc wall.

(3) In the above-described embodiment, the first steering force transmission shaft 18A is connected to the input rotation ring 31 via the input shaft 55 and the like, while the second steering force transmission shaft 18B is connected to the output shaft 80 and the like. Although connected to the output rotating ring 32, the actuator 20 of the above embodiment is turned upside down to connect the first steering force transmission shaft 18A to the output rotating ring 32 via the output shaft 80 and the like. Two steering force transmission shafts 18B may be coupled to the input rotation ring 31 via the input shaft 55 or the like. In this case, the output rotating ring 32 corresponds to “one of a pair of differential rotating portions” according to the present invention, and the input rotating ring 31 corresponds to “the other of a pair of differential rotating portions”.

The conceptual diagram of the vehicle which concerns on one Embodiment of this invention. Side sectional view of the steering ratio change actuator

Explanation of symbols

14 Vehicle body 17 Handle 18A First steering force transmission shaft 18B Second steering force transmission shaft 20 Actuator (steering ratio changing actuator)
21 Actuator housing 30 Differential reduction gear 31 Input rotation ring (differential rotation part)
32 Output rotating ring (differential rotating part)
40 Motor 70 Movable ring 71 Disk wall 83 Connecting member

Claims (4)

A motor and a differential reduction gear are housed in an actuator housing fixed to a vehicle body, and a first steering force transmission shaft extends from a handle to one of a pair of differential rotation portions provided in the differential reduction gear. And a second steering force transmission shaft extending on a lower extension line of the first steering force transmission shaft is connected to the other of the pair of differential rotating parts, and the motor is operated according to the driving situation. By driving the differential reduction gear according to the steering ratio change actuator that can change the transmission ratio of rotation between the first and second steering force transmission shafts, In what comprises a connecting member for connecting the first or second steering force transmission shaft and the differential rotating portion,
A steering ratio changing actuator, characterized in that a movable ring is provided that is rotatably fitted to the inner peripheral surface of the actuator housing and loosely fitted to the outside of the connecting member. Extending the disk wall from one end of the movable ring to the inside,
The steering ratio changing actuator according to claim 1, wherein an end surface of the connecting member is covered with the disk wall.   The steering ratio changing actuator according to claim 1 or 2, wherein the movable ring is made of a synthetic resin.   The steering ratio changing actuator according to claim 1 or 2, wherein the movable ring is made of a sintered material or metal having a hardness equal to or higher than that of the actuator housing.

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