CN106995003B

CN106995003B - Steering device

Info

Publication number: CN106995003B
Application number: CN201710026443.1A
Authority: CN
Inventors: 高桥昌宏; 中井悠人; 中村江児
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2016-01-22
Filing date: 2017-01-13
Publication date: 2021-04-02
Anticipated expiration: 2037-01-13
Also published as: JP2017128300A; KR20170088290A; DE102017200140A1; CN106995003A; JP6654445B2

Abstract

The application discloses turn to device, it possesses: a reducer, comprising: an input mechanism to which a steering force corresponding to a torque applied to a steering shaft is input; an output mechanism having a 1 st output shaft that rotates about a predetermined rotation axis in accordance with the steering force input to the input mechanism; and a steering rocker arm having a connecting portion connected to the 1 st output shaft so as to intersect the rotation axis. The connecting part and the 1 st output shaft rotate coaxially.

Description

Steering device

Technical Field

The present invention relates to an electric steering apparatus mounted on a vehicle.

Background

A steering device that changes the direction of wheels is mounted on various vehicles. Jp 2007-1564 a discloses a steering mechanism provided with a steering rocker arm (japanese: ピットマンアーム). The steering rocker arm disclosed in japanese patent application laid-open No. 2007 and 1564 is attached to a speed reducer. The steering rocker arm swings in accordance with the rotation of the speed reducer.

Strong impact force applied to the wheels may be transmitted to the reduction gear via the steering rocker arm. In the technique of japanese patent application laid-open No. 2007-1564, a large torque around the rotation axis of the speed reducer acts on the speed reducer due to the impact force. This means that the gears inside the speed reducer generate an excessive load.

Disclosure of Invention

The invention aims to provide a steering device with a structure which is difficult to damage due to impact force transmitted through a steering rocker arm.

A steering device according to an aspect of the present invention includes: a reducer, comprising: an input mechanism to which a steering force corresponding to a torque applied to a steering shaft is input; an output mechanism having a 1 st output shaft that rotates about a predetermined rotation axis in accordance with the steering force input to the input mechanism; and a steering rocker arm having a connecting portion connected to the 1 st output shaft so as to intersect the rotation axis. The connecting part and the 1 st output shaft rotate coaxially.

The steering device described above can have a structure that is less likely to be damaged by the impact force transmitted via the steering rocker arm.

The objects, features and advantages of the above-described steering device will become more apparent from the detailed description and accompanying drawings.

Drawings

Fig. 1 is a conceptual block diagram of a steering device according to embodiment 1.

Fig. 2 is a conceptual block diagram of the steering device of embodiment 2.

Fig. 3 is a schematic cross-sectional view of the steering device according to embodiment 3.

Fig. 4 is a schematic sectional view taken along line a-a shown in fig. 3.

Fig. 5 is a schematic cross-sectional view of the steering device according to embodiment 4.

Fig. 6 is a schematic cross-sectional view of the steering device according to embodiment 5.

Fig. 7 is a schematic cross-sectional view of the steering device according to embodiment 6.

Detailed Description

< embodiment 1 >

During the period in which the vehicle is traveling, the wheels sometimes receive a large impact force. For example, if the wheel is rimmed, the impact force may be transmitted to the speed reducer through the wheel, the tie rod arm, and the steering arm. According to the conventional coupling structure between the pitman arm and the speed reducer, the coupling portion of the pitman arm to the speed reducer rotates about the rotation axis of the speed reducer. Since the product of the distance between the connecting portion and the rotation axis and the impact force corresponds to the torque applied to the speed reducer, the impact force applies a large load to the gears in the speed reducer under the condition of the conventional connecting structure between the pitman arm and the speed reducer. In embodiment 1, a technique for reducing the influence of impact force on gears in a speed reducer will be described.

Fig. 1 is a conceptual block diagram of a steering device 100 according to embodiment 1. Referring to fig. 1, a steering device 100 will be described.

The steering device 100 includes a reduction gear 200 and a steering rocker arm 300. The reducer 200 includes an input mechanism 210 and an output mechanism 220. The motor (not shown) and another drive source (not shown) generate a steering force in accordance with the rotation of the steering shaft (not shown). The steering force is input to the input mechanism 210. The input mechanism 210 and the output mechanism 220 cooperate to increase the steering force. The output mechanism 220 includes an output shaft 221 to which a steering rocker arm 300 is connected. The increased steering force is output as the rotational force of the output shaft 221. As a result of the rotation of the output shaft 221, the pitman arm 300 swings. As a result of the swing of the steering rocker arm 300, a tie rod arm (not shown) coupled to the steering rocker arm 300 and the wheels (not shown) is driven, and the direction of the wheels is changed. In the present embodiment, the 1 st output shaft is exemplified by the output shaft 221.

The reducer 200 may be a swing type reducer or another cycloid reducer. Further, the speed reducer may alternatively have a configuration using a planetary gear. The principle of the present embodiment is not limited to a specific structure of the speed reducer 200.

Known automotive technologies may be applied to the connection configuration from the pitman arm 300 to the wheels. Therefore, the principle of the present embodiment is not limited to a specific technique for coupling the pitman arm 300 to the wheel.

The pitman arm 300 includes a base end portion 310 and a tip end portion 320 on the opposite side of the base end portion 310. The base end 310 is directly connected to the output shaft 221 and rotates coaxially with the output shaft 221. Since the base end portion 310 is present on the rotation axis RAX, even if an impact force is transmitted to the reduction gear via the pitman arm 300, it is difficult to generate an excessive torque around the rotation axis RAX in the reduction gear 100. The tip end portion 320 is connected to the tie rod arm. Various steering arms commercially available can be used as the steering arm 300. The principle of the present embodiment is not limited to a specific structure of the pitman arm 300. In the present embodiment, the connection portion is exemplified by the base end portion 310.

The pitman arm 300 is coupled to the reduction gear 200 such that the base end portion 310 rotates coaxially with the output shaft 221. Thus, the impact force transmitted via the pitman arm 300 hardly causes a large torque of the output shaft 221 about the rotation axis RAX. As a result, the gears (not shown) in the reduction gear 200 are less likely to receive an excessive load.

< embodiment 2 >

The reducer may also be driven by a motor. If the motor rotates coaxially with the output shaft of the speed reducer, the steering device can have a small size in a direction orthogonal to the rotational axis of the output shaft. In embodiment 2, an exemplary steering device including a speed reducer driven by a motor will be described.

Fig. 2 is a conceptual block diagram of a steering device 100A according to embodiment 2. Referring to fig. 2, a steering device 100A will be described. The description of embodiment 1 refers to elements denoted by the same reference numerals as those of embodiment 1.

The steering device 100A includes a steering rocker arm 300, as in embodiment 1. The description of embodiment 1 is directed to a pitman arm 300.

The steering device 100A further includes a reduction gear 200A and a motor 400. As in embodiment 1, the reduction gear 200A includes an input mechanism 210. The description of embodiment 1 is referred to the input mechanism 210.

The decelerator 200A further includes an output mechanism 220A. As in embodiment 1, the output mechanism 220A includes an output shaft 221. The description of embodiment 1 is referred to the output shaft 221.

The output mechanism 220A also includes a gear 222. The gear 222 is attached to the output shaft 221 to rotate about the rotation axis RAX.

Fig. 2 schematically shows the steering gear STG, the steering shaft STS, and the steering wheel STW. The gear 222 meshes with the steering gear STG. The steering gear STG may also be a worm gear. Alternatively, the steering gear STG may be another gear. The principle of the present embodiment is not limited to a specific type of gear used as the steering gear STG. In the present embodiment, the 1 st gear is exemplified by the gear 222.

The steering gear STG is mechanically connected to the steering shaft STS. The steering gear STG may also be integrated with the steering shaft STS. Alternatively, a gear structure constructed between the steering gear STG and the steering shaft STS may be used for mechanical connection between the steering gear STG and the steering shaft STS. The principle of the present embodiment is not limited to a specific connection structure between the steering gear STG and the steering shaft STS.

Fig. 2 schematically shows a control device CTR. The control device CTR includes a torque sensor TQS and a signal generation unit SGT.

Since the steering shaft STS is mechanically coupled to the gear 222 via the steering gear STG, torque is generated in the steering shaft STS extending from the steering wheel STW immediately after the steering wheel STW is rotated by a driver (not shown) driving a vehicle (not shown). The torque sensor TQS detects torque applied to the steering shaft STS. Known torque detection techniques may also be applied to the torque sensor TQS. The principle of the present embodiment is not limited to a specific type of the torque sensor TQS.

The torque sensor TQS is mechanically connected to the steering shaft STS if it is required to directly connect the torque sensor TQS to the steering shaft STS in order to detect torque generated at the steering shaft STS. In other cases, the torque sensor TQS may not be directly connected to the steering shaft STS. The mechanical or electrical connection between the torque sensor TQS and the steering spindle STS depends on the performance of the torque sensor TQS. Therefore, the principle of the present embodiment is not limited to a specific connection structure between the steering shaft STS and the torque sensor TQS.

The torque sensor TQS generates torque data representing the detected torque. The torque data is output from the torque sensor TQS to the signal generation unit SGT.

The signal generation unit SGT generates the drive signal so as to reduce the torque indicated by the torque data. The drive signal is output from the signal generator SGT to the motor 400.

The motor 400 generates a steering force according to the driving signal. The steering force is output to the input mechanism 210 as the rotation of the motor 400. The input mechanism 210 and the output mechanism 220A cooperate to increase the steering force. The increased steering force is output to the pitman arm 300 as the rotational force of the output shaft 221. At this time, the gear 222 also rotates, and therefore the steering gear STG, the steering shaft STS, and the steering wheel STW also rotate.

The motor 400 rotates about the rotation axis RAX, similarly to the output shaft 221, the gear 222, and the base end portion 310 of the pitman arm 300. Since the motor 400 is disposed so as to rotate coaxially with the output shaft 221, the gear 222, and the base end portion 310 of the pitman arm 300, the steering device 100A can have a small size in a direction orthogonal to the rotation axis RAX.

< embodiment 3 >

A designer can design various steering devices based on the design principle described in connection with embodiment 2. In embodiment 3, an exemplary steering device will be described.

Fig. 3 is a schematic cross-sectional view of a steering device 100B according to embodiment 3. Fig. 4 is a schematic sectional view taken along line a-a shown in fig. 3. The steering device 100B will be described with reference to fig. 2 to 4. The description of embodiment 2 refers to elements denoted by the same reference numerals as embodiment 2.

The steering device 100B includes a reduction gear 200B, a steering rocker arm 300B, and a motor 400B. The decelerator 200B corresponds to the decelerator 200A described with reference to fig. 2. The description related to the decelerator 200A may also be cited for the decelerator 200B. The pitman arm 300B corresponds to the pitman arm 300 described with reference to fig. 2. The description relating to the pitman arm 300 may also be referred to the pitman arm 300B. The motor 400B corresponds to the motor 400 described with reference to fig. 2. The description relating to motor 400 may also be incorporated into motor 400B.

The motor 400B includes a housing 410 and a rotating shaft 420. The housing 410 contains a coil and a stator core, and generates a steering force based on a drive signal. The rotary shaft 420 protrudes from the housing 410 into the reduction gear 200B and extends along the rotation axis RAX. The steering force generated in the housing 410 is output as rotation of the rotary shaft 420. The rotary shaft 420 rotates about the rotation axis RAX. A gear portion 421 is formed at the tip end of the rotary shaft 420.

The reducer 200B includes 3 transmission gears 211 (fig. 3 shows 1 of the 3 transmission gears 211) and 3 crankshaft assemblies 212 (fig. 3 shows 1 of the 3 crankshaft assemblies 212). The transmission gear 211 is attached to the crankshaft assembly 212. The transmission gear 211 is engaged with a gear portion 421 of the rotary shaft 420. In the present embodiment, the 2 nd gear is exemplified by the transmission gear 211.

The 3 crankshaft assemblies 212 include a crankshaft 213, two tapered

roller bearings

214, 215, and two

needle bearings

216, 217, respectively. The crankshaft 213 includes two

journals

231, 232 and two

eccentric portions

233, 234. The

journals

231, 232 are coaxially rotated about a rotation axis TAX extending substantially parallel to the rotation axis RAX at positions separated from the rotation axis RAX. The transmission gear 211 and the tapered roller bearing 214 are mounted on the journal 231. Journal 232 is on the opposite side of journal 231. Tapered roller bearing 215 is mounted to journal 232.

The eccentric 233 is located between the

journals

231, 232. The eccentric 234 is located between the eccentric 233 and the journal 232. The

eccentric portions

233, 234 are eccentric with respect to the rotation axis TAX. The eccentric direction of the eccentric portion 233 is different from that of the eccentric portion 234.

Since the transmission gear 211 meshing with the gear portion 421 of the motor 400B is attached to the journal 231, the

journals

231 and 232 rotate about the rotation axis TAX in accordance with the rotation of the rotation shaft 420 of the motor 400B. During this time, the

eccentric portions

233, 234 eccentrically rotate with respect to the rotation axis TAX. The 3 transmission gears 211 and the 3 crankshaft assemblies 212 correspond to the input mechanism 210 described with reference to fig. 2.

The reduction gear 200B includes an outer cylinder 240 fixed to the motor 400B. The outer cylinder 240 includes a 1 st cylinder 241, a 2 nd cylinder 242, and a 3 rd cylinder 243.

The 1 st barrel portion 241 includes an end wall 244 and a peripheral wall 245. The end wall 244 is in close contact with the housing 410 of the motor 400B. The peripheral wall 245 protrudes from the substantially circular outer peripheral edge of the end wall 244, and surrounds the rotary shaft 420 and the transmission gear 211.

The 2 nd barrel portion 242 includes a peripheral wall 246 and a plurality of inner tooth pins 247. The peripheral wall 246 surrounds the

eccentric portions

233, 234. Each of the plurality of inner teeth pins 247 is a columnar member extending in the extending direction of the rotation axis RAX. The plurality of inner-tooth pins 247 are fitted into groove portions formed on the inner surface of the peripheral wall 246. Thus, the plurality of inner-tooth pins 247 are properly held by the peripheral wall 246.

As shown in fig. 4, the plurality of inner-tooth pins 247 are arranged at substantially constant intervals around the rotation axis RAX. Each half circumferential surface of the plurality of inner-tooth pins 247 protrudes from the inner surface of the circumferential wall 246 toward the rotation axis RAX. Therefore, the plurality of internal gear pins 247 can function as internal teeth of the reduction gear 200B. In the present embodiment, the 1 st outer cylinder is exemplified by the outer cylinder 240. The inner toothed ring is exemplified by a plurality of inner toothed pins 247 arranged in a ring.

The 3 rd drum 243 includes a peripheral wall 248 and an end wall 249. The peripheral wall 248 of the 3 rd tube part 243 is in close contact with the end edge of the peripheral wall 246 of the 2 nd tube part 242. The end wall 249 partially closes a substantially circular space surrounded by the peripheral wall 248.

The reduction gear 200B includes a gear portion 250 surrounded by the 2 nd cylindrical portion 242. The gear portion 250 includes two

oscillating gears

251, 252. The oscillating gear 251 has 3 circular through holes formed therein. The 3 crank assemblies 212 are inserted into the 3 circular opening holes of the oscillating gear 251. The needle roller bearings 216 of the 3 crankshaft assemblies 212 are fitted into the 3 circular through holes, respectively. The oscillating gear 252 has 3 circular through holes formed therein. The 3 crank shaft assemblies 212 are inserted into the 3 circular opening holes of the swing gear 252. The needle roller bearings 217 of the 3 crankshaft assemblies 212 are fitted into the 3 circular through holes, respectively. In the present embodiment, at least 1 gear is exemplified by at least one of the oscillating gears 251, 252.

The reduction gear 200B of the present embodiment includes two swing gears 251 and 252. Alternatively, the reduction gear may have a single oscillating gear. Also, as an alternative, the reducer may have more than 2 oscillating gears. The principle of the present embodiment is not limited in any way by the fact that several oscillating gears are incorporated in the speed reducer.

The oscillating gears 251, 252 mesh with an internal gear ring formed by a plurality of internal gear pins 247. During rotation of the crankshaft assembly 212, the swing gears 251 and 252 are swung by the

eccentric portions

233 and 234. During this, the centers of the swing gears 251, 252 are rotationally moved about the rotation axis RAX. The rotational swinging motion of the swing gears 251 and 252 is transmitted to a portion (for example, the crankshaft assembly 212) connected to the swing gears 251 and 252.

As described above, the

eccentric portions

233, 234 differ in the eccentric direction. Thus, the rotational movement at the center of the oscillating gears 251, 252 generates a rotational phase difference. The

eccentric portions

233 and 234 may be designed so that rotational movement at the centers of the swing gears 251 and 252 generates a rotational phase difference of, for example, 180 °. In this case, the swing gear 251 is meshed with substantially half of the plurality of internal tooth pins 247, and the swing gear 252 can be meshed with the remaining internal tooth pins 247.

The reduction gear 200B includes a carrier 223 disposed in a space surrounded by the outer cylinder 240. The carrier 223 includes a base portion 260 and an end plate portion 270. The end plate 270 is located between the base 260 and the end wall 244 of the 1 st tube 241.

The base 260 includes a base plate 261 (see fig. 3) and 3 shafts 262 (see fig. 4). The 3 shafts 262 protrude from the base plate portion 261 toward the end plate portion 270. The oscillating gears 251 and 252 are formed with 3 trapezoidal through holes, respectively. The 3 shafts 262 are inserted into these trapezoidal through holes. The size of these trapezoidal through holes is set so that interference does not occur between the oscillating gears 251 and 252 and the shaft 262.

The end plate portion 270 is fixed to the tip end surface of the 3 shafts 262. Accordingly, the swing gears 251 and 252 swing between the end plate portion 270 and the base plate portion 261.

The substrate 261 has 3 through holes 263 (fig. 3 shows 1 of the 3 through holes 263). The tapered roller bearings 215 of the 3 crankshaft assemblies 212 are fitted into the 3 through holes 263. The end plate portion 270 has 3 through holes 271 (fig. 3 shows 1 of the 3 through holes 271). The tapered roller bearings 214 of the 3 crankshaft assemblies 212 are fitted into the 3 through holes 271, respectively. Thus, the carrier 223 is connected to the crankshaft assembly 212. The carrier 223 serves as a part of the output mechanism 220A described with reference to fig. 2.

The oscillating rotational motion of oscillating

gears

251 and 252 is transmitted to carrier 223 via 3 crankshaft assemblies 212. As a result, the carrier 223 can rotate around the rotation axis RAX.

The reduction gear 200B includes an output shaft 221B and a gear 222B. The output shaft 221B corresponds to the output shaft 221 described with reference to fig. 2. The description relating to the output shaft 221 may also be cited for the output shaft 221B. The gear 222B corresponds to the gear 222 described with reference to fig. 2. The description relating to gear 222 is referenced for gear 222B.

The output shaft 221B includes a shaft 224 and a mounting plate 225. The mounting plate 225 is a disk-shaped portion that abuts against an end surface of the base plate 261 (an end surface facing the end wall 249 of the 3 rd tube 243). The center of the mounting plate 225 substantially coincides with the rotation axis RAX. The attachment plate 225 is fixed to an end surface of the base plate 261 (an end surface facing the end wall 249 of the 3 rd tube 243) by a bolt BLT. Thus, the mounting plate 225 may be separate from the gear rack 223. The shaft 224 extends along the rotation axis RAX from the mounting plate 225 toward the pitman arm 300B.

The reduction gear 200B further includes a gear case 280. The gear box case 280 includes a substantially cylindrical peripheral wall 281 and an end wall 282 that closes a substantially circular space surrounded by the peripheral wall 281. The end edge of the peripheral wall 281 of the gear case tube 280 is in close contact with the end wall 249 of the 3 rd tube section 243. The gearbox barrel 280 cooperates with the end wall 249 of the 3 rd barrel section 243 to form a gearbox that houses the gear 222B. In the present embodiment, the 2 nd outer cylinder is exemplified by the gear box cylinder 280.

A through hole 291 is formed in the end wall 249 of the 3 rd tube portion 243. A through hole 283 is formed in the end wall 282 of the gear case barrel 280. The rotation axis RAX substantially coincides with the centers of the through

holes

283 and 291. The shaft 224 extends along the rotation axis RAX and penetrates the through

holes

291 and 283. The pitman arm 300B includes a base end portion 310B connected to the tip end of the shaft 224 outside the outer cylinder 240 and the gear box cylinder 280. The pitman arm 300B extends in a direction substantially orthogonal to the rotation axis RAX. During rotation of the carrier 223, the pitman arm 300B oscillates in a plane orthogonal to the rotation axis RAX. The proximal end portion 310B corresponds to the proximal end portion 310 described with reference to fig. 2. The description about the proximal end portion 310B may be also referred to the proximal end portion 310B. In the present embodiment, the 1 st through hole is exemplified by the through hole 291.

The reduction gear 200B includes two

main bearings

292 and 284 defining a rotation axis RAX. The main bearing 284 is located between the main bearing 292 and the steering rocker arm 300B. The main bearing 292 is fitted into a through hole 291 formed in the end wall 249 of the 3 rd tube portion 243. The main bearing 284 is fitted into a through hole 283 formed in the end wall 282 of the gear case 280. The shaft 224 passes through the

main bearings

292, 284. Thus, the shaft 224 is properly held by the

main bearings

292, 284. In the present embodiment, the 1 st bearing is exemplified by the main bearing 292. The 2 nd bearing is exemplified by a main bearing 284. The 2 nd through-hole is exemplified by the through-hole 283. The end wall is exemplified by an end wall 282 of the gearbox barrel 280.

Fig. 3 schematically shows a steering shaft STS and a worm wheel WMG. The worm wheel WMG is integrally formed with the steering shaft STS at a lower end thereof. Gear 222B is mounted to shaft 224 between

main bearings

292, 284. The gear 222B meshes with a worm wheel WMG. The worm wheel WMG corresponds to the steering gear STG explained with reference to fig. 2. The description relating to the steering gear STG may also be cited for the worm wheel WMG.

< embodiment 4 >

The output shaft may be formed integrally with the carrier. In this case, the output shaft cannot be separated from the carrier, and the axial length of the steering device becomes short. In embodiment 4, an exemplary steering device including an output shaft integrated with a carrier will be described.

Fig. 5 is a schematic cross-sectional view of a steering device 100C according to embodiment 4. The steering device 100C will be described with reference to fig. 2, 3, and 5. The description of embodiment 3 refers to elements denoted by the same reference numerals as those of embodiment 3.

The steering device 100C includes a steering rocker arm 300B and a motor 400B, as in embodiment 3. The description of embodiment 3 refers to these elements.

The steering device 100C further includes a reduction gear 200C. As in embodiment 2, the speed reducer 200C includes 3 transmission gears 211 (fig. 5 shows 1 of the 3 transmission gears 211), 3 crankshaft assemblies 212 (fig. 5 shows 1 of the 3 crankshaft assemblies 212), a gear 222B, a carrier 223, an outer cylinder 240, a gear portion 250, a gear case 280, and

main bearings

284 and 292. The description of embodiment 3 refers to these elements.

The reducer 200C also includes an output shaft 221C. The output shaft 221C is formed integrally with the base plate portion 261 of the carrier 223. Therefore, unlike embodiment 3, the output shaft 221C cannot be separated from the carrier 223. The output shaft 221C corresponds to the output shaft 221 described with reference to fig. 2. The description relating to the output shaft 221 may also be cited for the output shaft 221C.

Since the output shaft 221C is integrated with the base plate 261 of the carrier 223, the mounting plate 225 and the bolt BLT described with reference to fig. 3 are not required. Thus, the steering device 100C can have a small size in the extending direction of the rotation axis RAX.

The output shaft 221C extends along the rotation axis RAX and penetrates the

main bearings

292 and 284 fitted into the through

holes

291 and 283. The pitman arm 300B is connected to the top end of the output shaft 221C outside the outer cylinder 240 and the gear box cylinder 280.

Fig. 5 schematically shows the steering shaft STS and the worm wheel WMG. The worm wheel WMG is integrally formed with the steering shaft STS at a lower end thereof. The gear 222B is mounted on the output shaft 221C between the

main bearings

292 and 284. The gear 222B meshes with a worm wheel WMG.

< embodiment 5 >

The output shaft of the steering device according to embodiments 3 and 4 is supported by a bearing. Alternatively, the bearing may support the carrier around the gear portion. In this case, the steering device can have a shorter dimension in the extending direction of the rotation axis. In embodiment 5, an exemplary steering device including a carrier supported by a bearing will be described.

Fig. 6 is a schematic cross-sectional view of a steering device 100D according to embodiment 5. The steering device 100D will be described with reference to fig. 5 and 6. The description of embodiment 4 refers to elements denoted by the same reference numerals as those of embodiment 4.

The steering device 100D includes a steering rocker arm 300B and a motor 400B, as in embodiment 4. The description of embodiment 4 refers to these elements.

The steering device 100D further includes a speed reducer 200D. As in embodiment 4, the speed reducer 200D includes 3 transmission gears 211 (fig. 6 shows 1 of the 3 transmission gears 211), 3 crankshaft assemblies 212 (fig. 6 shows 1 of the 3 crankshaft assemblies 212), an output shaft 221C, a gear 222B, a carrier 223, an outer cylinder 240, and a gear portion 250. The description of embodiment 4 refers to these elements.

Unlike the steering device 100C described in connection with embodiment 4, the steering device 100D does not include the gear box case 280 (see fig. 5) and the main bearings 284 and 292 (see fig. 5) that support the output shaft 221C around the gear box case 280. On the other hand, the steering device 100D includes

main bearings

293 and 294. The

main bearings

293, 294 cooperate to determine the rotational axis RAX of the steering device 100D. The gear portion 250 performs oscillating rotation between the

main bearings

293 and 294. In the present embodiment, the 1 st bearing is exemplified by one of the

main bearings

293 and 294. The 2 nd bearing is exemplified by the other of the

main bearings

293, 294.

Unlike the

main bearings

284 and 292 described in connection with embodiment 4, the

main bearings

293 and 294 are disposed in the outer tube 240. The main bearing 293 is fitted into an annular space formed between the outer peripheral surface of the end plate 270 of the carrier 223 and the inner peripheral surface of the 2 nd cylinder 242 of the outer cylinder 240. The main bearing 294 is fitted into an annular space formed between the outer peripheral surface of the base plate portion 261 of the carrier 223 and the inner peripheral surface of the 2 nd cylindrical portion 242 of the outer cylinder 240.

Unlike embodiment 4, the gear 222B is disposed in the outer cylinder 240 and meshes with the worm wheel WMG. Therefore, the steering device 100D can have a shorter dimension in the extending direction of the rotation axis RAX than the steering device 100C described in connection with embodiment 4.

< embodiment 6 >

The gears of the steering devices according to embodiments 3 to 5 mesh with worm gears between the steering rocker arm and the gear portion. Alternatively, the steering rocker arm may be disposed between the gear portion and a gear meshing with the worm wheel. In embodiment 6, an exemplary steering apparatus including a steering rocker arm disposed between a gear portion and a gear meshed with a worm wheel will be described.

Fig. 7 is a schematic cross-sectional view of a steering device 100E according to embodiment 6. Referring to fig. 2 and 7, a steering device 100E will be explained. The description of embodiment 5 refers to elements denoted by the same reference numerals as embodiment 5.

The steering device 100E includes a motor 400B, as in embodiment 5. The description of embodiment 5 is incorporated into motor 400B.

The steering device 100E further includes a reduction gear 200E and a steering rocker arm 300E. As in embodiment 5, the speed reducer 200E includes 3 transmission gears 211 (fig. 7 shows 1 of the 3 transmission gears 211), 3 crankshaft assemblies 212 (fig. 7 shows 1 of the 3 crankshaft assemblies 212), an output shaft 221C, a carrier 223, an outer cylinder 240, a gear portion 250, and

main bearings

293 and 294. The description of embodiment 5 refers to these elements.

The reducer 200E also includes an output shaft 221E, a gear 222E, a gearbox 290, two

secondary bearings

295, 296. The

output shafts

221C and 221E correspond to the output shaft 221 described with reference to fig. 2. In the present embodiment, the 2 nd output shaft is exemplified by the output shaft 221E.

A part of the output shaft 221E, the gear 222E, and the

sub bearings

295 and 296 are disposed in an internal space surrounded by the gear case 290. The centers of the

sub bearings

295, 296 substantially coincide with the rotation axis RAX defined by the

main bearings

293, 294. The output shaft 221E is supported within the gearbox 290 by

secondary bearings

295, 296. A part of the output shaft 221E extends along the rotation axis RAX, and protrudes from the gear case 290 toward the output shaft 221C. Thus, the output shaft 221E is aligned with the output shaft 221C on the rotation axis RAX.

The gear 222E is mounted to the output shaft 221E within the gearbox 290. Gear 222E is located between the

secondary bearings

295, 296. The gear 222E is engaged with a worm wheel WMG at the lower end of the steering shaft STS.

The pitman arm 300E is disposed outside the outer cylinder 240 and the gear box 290. The steering rocker arm 300E is disposed so as to straddle the boundary formed by the end surfaces of the

output shafts

221C, 221E, and is connected to the

output shafts

221C, 221E.

The design principle described in connection with the various embodiments described above can be applied to various steering devices. Some of the various features described in connection with 1 of the various embodiments described above may also be applied to a steering device described in connection with another embodiment.

The steering device described in connection with the above-described embodiment mainly has the following features.

A steering device according to an aspect of the above embodiment includes: a reducer, comprising: an input mechanism to which a steering force corresponding to a torque applied to a steering shaft is input; an output mechanism having a 1 st output shaft that rotates about a predetermined rotation axis in accordance with the steering force input to the input mechanism; and a steering rocker arm having a connecting portion connected to the 1 st output shaft so as to intersect the rotation axis. The connecting part and the 1 st output shaft rotate coaxially.

According to the above configuration, since the connecting portion of the steering rocker arm intersects with the rotation axis of the 1 st output shaft and rotates coaxially with the 1 st output shaft of the output mechanism, the point of action of the force from the steering rocker arm on the speed reducer substantially coincides with the rotation axis of the 1 st output shaft regardless of the rotational position of the steering rocker arm. As a result, excessive torque does not act even under the condition where the impact force transmitted via the pitman arm is present. Thus, the speed reducer is difficult to break.

In the above configuration, the steering device may further include a motor that generates the steering force. The output mechanism may include a 1 st gear attached to the 1 st output shaft so as to mesh with a steering gear that rotates in accordance with rotation of the steering shaft. The motor may include a rotary shaft that rotates coaxially with the 1 st gear and the connecting portion and outputs the steering force.

According to the above configuration, since the rotation shaft of the motor rotates coaxially with the 1 st gear and the connecting portion, the dimension of the steering device in the direction orthogonal to the rotation axis of the 1 st output shaft does not become excessively large.

In the above configuration, the input mechanism may include a 2 nd gear that meshes with a gear portion formed on the rotary shaft, and a crankshaft assembly to which the 2 nd gear is attached. The reduction gear may include: a gear part having at least 1 gear connected to the crankshaft assembly; a 1 st outer barrel comprising an inner gear ring in meshing engagement with the at least 1 gear. During rotation of the crankshaft assembly, the at least 1 gear may be rotated in an oscillating manner such that a center of the at least 1 gear rotates around the rotation axis.

According to the above configuration, the 2 nd gear meshes with the gear portion formed on the rotation axis of the motor, and therefore, the steering force is increased. At least 1 gear of the gear portion meshes with the inner ring gear of the 1 st outer cylinder, and therefore, the steering force is further increased.

In the above configuration, the output mechanism may include a carrier coupled to the crankshaft assembly and rotating integrally with the 1 st output shaft. The 1 st output shaft may extend from the carrier toward the pitman arm disposed outside the 1 st outer tube through a 1 st through hole formed in the 1 st outer tube.

According to the above configuration, the 1 st output shaft extends from the carrier connected to the crankshaft assembly toward the pitman arm disposed outside the 1 st outer cylinder through the 1 st through hole formed in the 1 st outer cylinder, and therefore, the increased steering force can be appropriately transmitted to the pitman arm.

In the above configuration, the 1 st output shaft may be separated from the carrier.

According to the above-described structure, the 1 st output shaft can be separated from the carrier, and therefore, the reduction gear can be easily disassembled.

In the above configuration, the 1 st output shaft may not be separated from the carrier.

According to the above configuration, the 1 st output shaft cannot be separated from the carrier, and therefore, a connection structure for connecting the 1 st output shaft to the carrier is not necessary. Thus, the steering device can have a simple configuration.

In the above configuration, the steering device may further include a 1 st bearing accommodated in the 1 st through hole, and a 2 nd bearing disposed between the 1 st bearing and the steering rocker arm. The 1 st output shaft may penetrate the 1 st bearing and the 2 nd bearing.

According to the above configuration, the 1 st output shaft passes through the 1 st bearing and the 2 nd bearing, and therefore, the 1 st output shaft is appropriately held by the 1 st bearing and the 2 nd bearing.

In the above-described configuration, the steering device may further include a 2 nd outer cylinder, and the 2 nd outer cylinder cooperates with the 1 st outer cylinder to form a gear box for accommodating the 1 st gear attached to the 1 st output shaft between the 1 st bearing and the 2 nd bearing. The 2 nd outer cylinder may include an end wall having a 2 nd through hole for receiving the 2 nd bearing formed therein. The 1 st output shaft may be coupled to the steering arm by passing through the 2 nd through hole.

According to the above configuration, the 2 nd outer cylinder cooperates with the 1 st outer cylinder to form the gear box, and therefore, the 1 st gear is properly protected by the 1 st outer cylinder and the 2 nd outer cylinder. The 1 st output shaft passes through the 2 nd through hole formed in the end wall of the 2 nd outer cylinder, and therefore can be appropriately coupled to the steering rocker arm.

In the above configuration, the steering device may further include a 1 st bearing disposed in the 1 st outer cylinder and a 2 nd bearing that cooperates with the 1 st bearing to define the rotation axis. The 1 st outer cylinder may include a peripheral wall formed with the internal gear ring. The 1 st bearing and the 2 nd bearing may be disposed in an annular space between the peripheral wall and the carrier. The gear portion may be located between the 1 st bearing and the 2 nd bearing.

According to the above configuration, since the gear portion is located between the 1 st bearing and the 2 nd bearing, eccentric vibration generated by the oscillating rotation of the gear portion is less likely to be transmitted to the 1 st output shaft.

In the above configuration, the 1 st gear may be located between the gear portion and the pitman arm.

According to the above configuration, the 1 st gear is located between the gear portion and the pitman arm, and therefore, the steering device is mechanically coupled to the steering shaft between the reduction gear and the pitman arm.

In the above configuration, the pitman arm may be located between the gear portion and the 1 st gear.

According to the above-described structure, the steering rocker arm is located between the gear portion and the 1 st gear, and therefore, even if the space in which the speed reducer is disposed is separated from the space in which the steering shaft is disposed, the steering apparatus can drive the steering rocker arm.

In the above configuration, the output mechanism may include a 2 nd output shaft coaxial with the 1 st output shaft. The 1 st gear may be attached to the 2 nd output shaft. The steering rocker arm may be connected to the 1 st output shaft and the 2 nd output shaft.

According to the above configuration, the 1 st output shaft and the 2 nd output shaft are connected to the steering rocker arm, and therefore, the steering force can be appropriately transmitted to the steering rocker arm.

Industrial applicability

The principles of the embodiments described above can be suitably utilized in various vehicle designs.

Claims

1. A steering device is provided with:

a motor that generates a steering force;

a reducer, comprising: an input mechanism to which the steering force generated by the motor and corresponding to a torque applied to a steering shaft is input; an output mechanism having a 1 st output shaft that rotates about a predetermined rotation axis in accordance with the steering force input to the input mechanism;

a steering rocker arm having a connecting portion connected to the 1 st output shaft so as to intersect the rotation axis,

the connecting part and the 1 st output shaft rotate coaxially,

the output mechanism includes a 1 st gear attached to the 1 st output shaft so as to mesh with a steering gear that rotates in accordance with rotation of the steering shaft,

the motor includes a rotating shaft that rotates coaxially with the 1 st gear and the connecting portion and outputs the steering force.

2. The steering device according to claim 1,

the input mechanism includes a 2 nd gear engaged with a gear portion formed at the rotation shaft and a crankshaft assembly to which the 2 nd gear is mounted,

the speed reducer includes: a gear part having at least 1 gear connected to the crankshaft assembly; a 1 st outer barrel comprising an inner gear ring in mesh with the at least 1 gear,

during rotation of the crankshaft assembly, the at least 1 gear performs an oscillating rotation in such a manner that a center of the at least 1 gear rotates around the rotation axis.

3. The steering device according to claim 2,

the output mechanism includes a carrier coupled to the crankshaft assembly and rotating integrally with the 1 st output shaft,

the 1 st output shaft extends from the carrier toward the steering rocker arm disposed outside the 1 st outer tube through a 1 st through hole formed in the 1 st outer tube.

4. The steering device according to claim 3,

the 1 st output shaft is detachable from the carrier.

5. The steering device according to claim 3,

the 1 st output shaft cannot be separated from the carrier.

6. The steering device according to claim 3,

the steering device further includes:

a 1 st bearing accommodated in the 1 st through hole;

a 2 nd bearing disposed between the 1 st bearing and the pitman arm,

the 1 st output shaft penetrates through the 1 st bearing and the 2 nd bearing.

7. The steering device according to claim 6,

the steering device further includes a 2 nd outer cylinder that cooperates with the 1 st outer cylinder to form a gear box that accommodates the 1 st gear attached to the 1 st output shaft between the 1 st bearing and the 2 nd bearing,

the 2 nd outer cylinder includes an end wall formed with a 2 nd through hole accommodating the 2 nd bearing,

the 1 st output shaft penetrates the 2 nd through hole and is connected to the steering rocker arm.

8. The steering device according to claim 3,

the steering device further includes:

a 1 st bearing disposed in the 1 st outer cylinder;

a 2 nd bearing cooperating with the 1 st bearing to determine the rotation axis,

the 1 st outer cylinder includes a peripheral wall formed with the internal gear ring,

the 1 st bearing and the 2 nd bearing are disposed in an annular space between the peripheral wall and the carrier,

the gear portion is located between the 1 st bearing and the 2 nd bearing.

9. The steering device according to any one of claims 2 to 8,

the 1 st gear is located between the gear portion and the pitman arm.

10. The steering device according to any one of claims 3 to 5,

the pitman arm is located between the gear portion and the 1 st gear.

11. The steering device according to claim 10,

the output mechanism comprises a 2 nd output shaft coaxial with the 1 st output shaft,

the 1 st gear is mounted to the 2 nd output shaft,

the steering rocker arm is connected with the 1 st output shaft and the 2 nd output shaft.