Variable-ratio spherical worm roller electric redundant steering gear

Abstract

The application discloses a variable transmission ratio spherical worm roller type electric redundant steering gear, which comprises an input shaft, a rocker shaft, a power unit and a transmission ratio control device, a first worm is coaxially arranged on the input shaft, a rocker holder is arranged on the rocker shaft, a roller is arranged on the rocker holder, and the roller is matched with the first worm; the first worm drives the rocker holder to swing when rotating; the input end of the transmission ratio control device is connected with the power unit, and the output end of the transmission ratio control device is in transmission connection with the input shaft; and the transmission ratio control device is used for adjusting the output power of the power unit. In the application, the transmission ratio control device adjusts the output power of the power unit; when steering at low speed, the transmission ratio control device adjusts the output power of the power unit and increases the output power; and when driving at high speed, the transmission ratio control device appropriately reduces the assist output, so that the steering wheel feels more stable, and the driving stability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power steering gear, in particular to a variable transmission ratio spherical worm roller type electric redundant steering gear. BACKGROUND

[0002] With the development of automobile technology, electric power steering system is gradually replacing the traditional hydraulic power steering system, and becomes the industry development trend. At present, electric power steering system has been widely used in passenger cars and light commercial vehicles, while heavy trucks still commonly use traditional hydraulic power steering system and electric hydraulic power steering system. The existing heavy truck steering gears are mainly based on hydraulic circulating ball structure and electro-hydraulic circulating ball structure. In the process of assisting, the circulating ball transmission is accompanied by hydraulic pushing of the piston, which reduces the torque that the circulating ball needs to transmit, thereby ensuring the service life of the circulating ball structure. However, for a pure electric steering gear with an output torque of more than 7000N.m, if the circulating ball structure is still used and lacks hydraulic auxiliary assistance, it completely relies on the circulating ball structure to transmit large torque, the raceway and steel ball of the circulating ball structure are easily damaged, the service life is low, and the use requirements of the steering gear cannot be met.

[0003] In addition, the output power of the existing pure electric steering gear is usually fixed; however, in actual driving conditions, different vehicle speeds and different road conditions have different requirements for the power output of the pure electric steering gear. The existing pure electric steering gear cannot meet the requirements of different output forces under different steering requirements, and thus cannot better adapt to actual driving requirements. SUMMARY

[0004] The purpose of the present application is to solve the problems in the prior art, and to provide a variable transmission ratio spherical worm roller type electric redundant steering gear.

[0005] The purpose of the present application is achieved by the following technical scheme: a variable transmission ratio spherical worm roller type electric redundant steering gear, comprising an input shaft, a rocker shaft, a power unit, a transmission ratio control device, a first worm being coaxially arranged on the input shaft, a rocker bracket being arranged on the rocker shaft, a roller being arranged on the rocker bracket, and the roller cooperating with the first worm; the first worm drives the rocker bracket to swing when rotating; the input end of the transmission ratio control device is connected with the power unit, and the output end of the transmission ratio control device is in transmission connection with the input shaft; the transmission ratio control device is used for adjusting the output power of the power unit; when the power unit fails, the transmission ratio control device provides auxiliary power for the rotation of the first worm.

[0006] As a preferred, the first worm is a spherical worm, the roller groove is arranged in the circumferential direction of the roller, the cross section of the roller groove is matched with the cross section of the helical tooth on the worm, and the helical tooth on the worm is embedded in the roller groove on the roller.

[0007] As preferred, the power unit comprises a first motor and a reducer connected to the first motor.

[0008] As preferred, the transmission ratio control device comprises a worm wheel outer cylinder, a first sun gear shaft, a second sun gear shaft and a second motor, the worm wheel outer cylinder is in a cylindrical shape, a worm gear is arranged on the outer ring surface of the worm wheel outer cylinder, an input end side plate and an output end side plate are arranged on both sides of the worm wheel outer cylinder respectively, the first sun gear shaft is rotatably connected to the center of the input end side plate, the second sun gear shaft is rotatably connected to the center of the output end side plate, a first sun gear is arranged on the first sun gear shaft, a second sun gear is arranged on the second sun gear shaft, a planetary gear shaft is arranged between the input end side plate and the output end side plate, both ends of the planetary gear shaft are rotatably matched with the input end side plate and the output end side plate respectively; a first planetary gear and a second planetary gear are arranged on the planetary gear shaft, the first planetary gear is engaged with the first sun gear, and the second planetary gear is engaged with the second sun gear; a second worm is connected to the second motor, and the second worm is engaged with the worm gear on the outside of the worm wheel outer cylinder; the first sun gear shaft is connected with the power unit, and the second sun gear shaft is in transmission connection with the input shaft.

[0009] As preferred, when the vehicle speed of the vehicle is in the first speed range and in the steering state, the second motor drives the second worm to rotate, the second worm drives the worm wheel outer cylinder to rotate, the rotation direction of the worm wheel outer cylinder is consistent with the output rotation direction of the first motor; the transmission ratio control device plays a role of enhancing the output power; when the vehicle speed of the vehicle is in the second speed range and in the steering state, the second motor drives the second worm to rotate, the second worm drives the worm wheel outer cylinder to rotate, the rotation direction of the worm wheel outer cylinder is opposite to the output rotation direction of the first motor, and the transmission ratio control device plays a role of reducing the output power.

[0010] As preferred, when the vehicle speed of the vehicle is less than 30km / h, the calculation formula of the target rotation speed N of the second worm is as follows:

[0011] ;

[0012] Wherein, is a low speed zone proportionality coefficient, V1=30km / h; n1 is a first basic rotation speed value; V is the vehicle speed;

[0013] When the vehicle speed of the vehicle is 30km / h-80km / h, the calculation formula of the target rotation speed N of the second worm is as follows:

[0014] ;

[0015] is a medium speed zone proportionality coefficient; n2 is a second basic rotation speed value;

[0016] When the vehicle speed is higher than 80km / h, the calculation formula of the target rotating speed N of the second worm is as follows:

[0017] ;

[0018] is a proportional coefficient for high-speed area, V2=80km / h; n3 is a third basic rotating speed value.

[0019] As preferred, when the first motor fails, the first motor self-locking fixes the first sun gear shaft, at this time, the second motor is used as a booster motor, the second motor drives the second worm to rotate to drive the worm gear outer cylinder to rotate, the torque is transmitted to the second sun gear shaft through the second planetary gear and the second sun gear, and the second sun gear shaft transmits the torque to the input shaft to realize the boosting effect.

[0020] As preferred, the first pulley is arranged on the second sun gear shaft, the second pulley is arranged on the input shaft, and the synchronous belt is connected between the first pulley and the second pulley.

[0021] As preferred, the input shaft comprises a front end shaft body and a main shaft body, the front end shaft body and the main shaft body are connected through a torsion bar; a torque rotation angle sensor is arranged at the connection position of the front end shaft body and the main shaft body; and the torque rotation angle sensor is used for detecting the relative torsion angle between the front end shaft body and the main shaft body.

[0022] As preferred, the transmission ratio control device further comprises a shell assembly, the shell assembly comprises a first shell part, a second shell part and a third shell part, the first shell part, the second shell part and the third shell part are fixedly connected through screws; the second worm and the worm gear outer cylinder are arranged in the first shell part, and the second motor is fixedly connected with the first shell part; the first pulley, the second pulley and the synchronous belt are located in the second shell part, the first worm, the rocker arm and the roller are located in the third shell part, and the swing arm shaft is rotationally matched with the third shell part.

[0023] The beneficial effects of the present application are: 1. The input end of the transmission ratio control device is connected with the power unit, the power unit outputs corresponding power according to the driving state of the vehicle; the transmission ratio control device adjusts the output power of the power unit and transmits it to the input shaft to provide power assistance for steering; when steering at low speed, the resistance required to be overcome by tire deflection is large, which is manifested as heavy steering wheel feel; at this time, the transmission ratio control device adjusts the output power of the power unit and increases the output power; when driving at high speed, the transmission ratio control device appropriately reduces the power assistance output, so that the steering wheel feel is more stable, and the driving stability is improved.

[0024] 2. In the normal driving state, the power unit serves as the main power source; when the power unit fails, the power unit cannot output power, at which time the transmission ratio control device will play its standby function, the transmission ratio control device will replace the power output function of the power unit, and the transmission ratio control device will serve as the main power output to provide power to the steering gear, so as to avoid the sudden loss of power to the steering wheel after the power unit fails, which causes the steering wheel to be difficult to rotate, through the redundant power design of the transmission ratio control device, the driving safety of the vehicle after the power unit of the steering gear fails is ensured, the vehicle has basic steering ability, and the safety and reliability of vehicle driving are improved.

[0025] 3. The worm + roller structure adopted by the present application is more suitable for transmitting large torque than the traditional circulating ball structure, avoids the problem that the raceway and steel ball of the circulating ball structure are easily damaged when lacking hydraulic auxiliary power, effectively improves the service life of the steering gear, and meets the use requirements of heavy trucks on large torque steering gears. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present application.

[0027] Figure 2 It is a structural schematic diagram of the present application after removing the shell assembly.

[0028] Figure 3 It is a sectional view of the roller and the rocker arm frame.

[0029] Figure 4 It is a sectional view of the rocker arm worm position.

[0030] Figure 5 It is a structural schematic diagram of the transmission ratio control device.

[0031] Figure 6 It is a front view of the transmission ratio control device.

[0032] Figure 7 It is a gear transmission principle diagram of the present application.

[0033] Figure 8 It is a system connection schematic diagram of the present application.

[0034] Figure 9 It is a control schematic diagram of the present application.

[0035] In the figure: 1, input shaft, 1a, front end shaft body, 1b, main shaft body, 2, rocker shaft, 3, first motor, 4, speed reducer, 5, first housing part, 6, second housing part, 7, third housing part, 8, first worm, 9, roller, 10, rocker arm holder, 11, worm gear outer tube, 12, second worm, 13, second motor, 14, second sun gear shaft, 15, first pulley, 16, second pulley, 17, synchronous belt, 18, roller shaft, 19, roller groove, 20, bearing, 21, torsion bar, 22, torque angle sensor, 23, first pin shaft, 24, second pin shaft, 25, first sun gear shaft, 26, input end side plate, 27, output end side plate, 28, first sun gear, 29, planetary gear shaft, 30, first planetary gear, 31, second planetary gear, 32, reinforced connecting rod, 33, first sun gear. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0037] Those skilled in the art should understand that in the disclosure of the present application, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation on the present application.

[0038] It can be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of one element can be one, and in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation on the number.

[0039] As Figures 1 to 9As shown, a variable transmission ratio spherical worm roller 9 type electric power redundant steering gear includes an input shaft 1, a rocker shaft 2, a power unit, a transmission ratio control device, a first worm 8 is coaxially arranged on the input shaft 1, a rocker arm frame 10 is arranged on the rocker shaft 2, a roller 9 is arranged on the rocker arm frame 10, and the roller 9 cooperates with the first worm 8; the first worm 8 drives the rocker arm frame 10 to swing when rotating; the input end of the transmission ratio control device is connected with the power unit, and the output end of the transmission ratio control device is in transmission connection with the input shaft 1; the transmission ratio control device is used for adjusting the output power of the power unit; when the power unit fails, the transmission ratio control device provides auxiliary power for the rotation of the first worm 8.

[0040] Wherein, the input shaft 1 on the steering gear will be adjacent to the steering wheel of the automobile through a universal shaft or other transmission mechanism, and when the driver operates the steering wheel, the input shaft 1 will be directly driven to rotate. When the input shaft 1 rotates, the first worm 8 coaxially arranged thereon will also rotate synchronously, and through the cooperation between the first worm 8 and the roller 9, the rotary motion of the first worm 8 can be converted into the swing of the rocker arm frame 10, and further drive the rocker shaft 2 to swing, and the swing of the rocker shaft 2 will drive the rotation deflection of the automobile vehicle, so as to realize the steering of the vehicle.

[0041] The input end of the transmission ratio control device is connected with the power unit, and the power unit outputs corresponding power according to the driving state (such as vehicle speed, road condition, etc.) of the vehicle; the transmission ratio control device adjusts the output power of the power unit and transmits it to the input shaft 1 to provide power assistance for steering. When steering at low speed, the resistance required to be overcome by the tire deflection is large, which is manifested as the heavy feeling of the steering wheel; at this time, the transmission ratio control device adjusts the output power of the power unit and increases the output power, so that the steering wheel rotates more lightly. When driving at high speed, the transmission ratio control device appropriately reduces the power assistance output, so that the steering wheel feels more stable, and the driving stability is improved.

[0042] The transmission ratio control device in the application has a certain power. In the normal driving state, the power unit serves as the main power source; when the power unit fails, the power unit cannot output power, at this time, the transmission ratio control device will play its standby function, the transmission ratio control device will replace the power output function of the power unit, and the transmission ratio control device will serve as the main power output to provide power assistance for the steering gear, so as to avoid that the steering wheel loses power suddenly after the power unit fails and causes the steering wheel to rotate difficultly. Through the redundant power design of the transmission ratio control device, the driving safety of the vehicle after the power unit of the steering gear fails is ensured, the vehicle has basic steering ability, and the safety and reliability of the vehicle driving are improved.

[0043] The worm + roller 9 structure is more suitable for transmitting large torque compared with the traditional recirculating ball structure. For the pure electric power steering gear with an output torque of more than 7000 N·m, the problem that the raceway and steel ball are easily damaged when the recirculating ball structure lacks hydraulic auxiliary assistance is avoided, the service life of the steering gear is effectively improved, and the use requirement of heavy trucks for large torque steering gears is met.

[0044] The first worm 8 is a spherical worm, and the roller 9 is provided with an annular roller groove 19 in the circumferential direction, the cross section of the roller groove 19 is matched with the cross section of the spiral tooth on the worm, and the spiral tooth on the worm is embedded in the roller groove 19 on the roller 9. The roller shaft 18 is arranged on the swing arm frame, the roller 9 is rotatably arranged on the roller shaft 18, and the roller 9 and the roller shaft 18 are provided with a needle bearing 20 to reduce the friction resistance when the roller 9 rotates.

[0045] The cross section of the spiral tooth of the spherical worm and the roller groove 19 is accurately matched, that is, the profiles of the two are matched, the spiral tooth is embedded in the roller groove 19 to form a containing type engagement, and the transmission idle stroke caused by too large engagement gap is avoided: if the engagement precision of the traditional recirculating ball structure or the ordinary worm roller 9 structure is insufficient, the idle stroke problem of "steering wheel rotation but wheel response delay" during steering is easy to occur, and the cross section of the design is completely matched, the engagement gap is controlled in a very small range, and the torque of the steering wheel operated by the driver can be transmitted to the rocker shaft 2 without loss and in time, the steering response speed and control accuracy are improved, and it is especially suitable for heavy trucks and other vehicles with high requirements for steering accuracy.

[0046] The power unit includes a first motor 3 and a reducer 4 connected with the first motor 3. The types of the first motor 3 and the reducer 4 can be selected according to actual needs. In the embodiment, the first motor 3 is a double-winding motor, and the reducer 4 is a planetary gear reducer 4.

[0047] The transmission ratio control device comprises a worm outer cylinder 11, a first sun gear shaft 25, a second sun gear shaft 14 and a second motor 13. The worm outer cylinder 11 is in a cylindrical shape, and a worm gear is arranged on the outer ring surface of the worm outer cylinder 11. An input end side plate 26 and an output end side plate 27 are arranged on the two sides of the worm outer cylinder 11 respectively. The first sun gear shaft 25 is rotatably connected to the center of the input end side plate 26, and the second sun gear shaft 14 is rotatably connected to the center of the output end side plate 27. A first sun gear 28 is arranged on the first sun gear shaft 25, and a second sun gear is arranged on the second sun gear shaft 14. A planetary gear shaft 29 is arranged between the input end side plate 26 and the output end side plate 27, and the two ends of the planetary gear shaft 29 are rotatably connected to the input end side plate 26 and the output end side plate 27 respectively. A first planetary gear 30 and a second planetary gear 31 are arranged on the planetary gear shaft 29. The first planetary gear 30 is engaged with the first sun gear 28, and the second planetary gear 31 is engaged with the second sun gear. The second motor 13 is connected with a second worm 12, and the second worm 12 is engaged with the worm gear on the outside of the worm outer cylinder 11. The first sun gear shaft 25 is connected with a power unit, and the second sun gear shaft 14 is in transmission connection with an input shaft 1.

[0048] The first sun gear shaft 25 and the second sun gear shaft 14 are coaxially arranged. A reinforcing connecting rod 32 is arranged between the input end side plate 26 and the output end side plate 27.

[0049] The first sun gear shaft 25 (connected with the power unit) in the transmission ratio control device is a "driving input end", the second sun gear shaft 14 (in transmission connection with the input shaft 1 of the steering gear) is a "power output end", and the worm outer cylinder 11 can realize "driving rotation" or "fixed locking" through the second worm 12 (driven by the second motor 13). When the second motor 13 drives the worm outer cylinder 11 to rotate, the first planetary gear 30 shaft will revolve around the sun gear shaft through the input end side plate 26 and the output end side plate 27, and the first planetary gear 30 and the second planetary gear 31 will rotate around their own axes under the meshing action of the first sun gear 28. The "revolution + rotation" compound motion of the planetary gear will change the output rotation speed and torque of the second sun gear and the second sun gear shaft 14, and finally realize the adjustment of the transmission ratio of the transmission ratio control device.

[0050] When the second motor 13 is not running, the worm outer cylinder 11 remains unchanged. At this time, the output power of the first motor 3 is input through the first sun gear shaft 25, and the first sun gear shaft 25 drives the first sun gear 28 to rotate. The first sun gear 28 drives the first planetary gear 30 to rotate through meshing. Since the first planetary gear 30 and the second planetary gear 31 are coaxially fixed, the rotation of the first planetary gear 30 synchronously drives the second planetary gear 31 to rotate synchronously, and the second planetary gear 31 drives the second sun gear to rotate. Finally, the power is output through the second sun gear shaft 14. At this time, the transmission ratio is 1:1.

[0051] When the second motor 13 drives the second worm 12 to rotate according to the vehicle speed signal, the second worm 12 drives the worm gear outer cylinder 11 to rotate through the worm gear tooth, and provides additional revolution power for the planetary gear, at this time, the planetary gear rotates both with the worm gear outer cylinder 11 and rotates by itself due to the driving of the first sun gear 28, and the two kinds of movements are superimposed and transmitted to the second sun gear through the second planetary gear 31; through the rotation of the worm gear outer cylinder 11, the original transmission ratio of the transmission ratio control device is changed, and the greater the rotation speed of the worm gear outer cylinder 11, the greater the change range of the transmission ratio.

[0052] When the rotation direction of the worm gear outer cylinder 11 is consistent with the output rotation direction of the first motor 3, at this time, the transmission ratio of the transmission ratio control device is increased after superposition, and the assist force will be increased. When the rotation direction of the worm gear outer cylinder 11 is opposite to the output rotation direction of the first motor 3, the transmission ratio of the transmission ratio control device is reduced after superposition, and the assist force will be reduced.

[0053] When the vehicle speed is in the first speed range and in the steering state, the second motor 13 drives the second worm 12 to rotate, the second worm 12 drives the worm gear outer cylinder 11 to rotate, and the rotation direction of the worm gear outer cylinder 11 is consistent with the output rotation direction of the first motor 3; the transmission ratio control device plays a role in improving the output power; when the vehicle speed is in the second speed range and in the steering state, the second motor 13 drives the second worm 12 to rotate, the second worm 12 drives the worm gear outer cylinder 11 to rotate, and the rotation direction of the worm gear outer cylinder 11 is opposite to the output rotation direction of the first motor 3, and the transmission ratio control device plays a role in reducing the output power.

[0054] Further, the transmission ratio control device will accurately control the rotation speed of the second worm according to the vehicle speed, and then accurately adjust the transmission ratio. In the present application, the vehicle speed is divided into three intervals, when the vehicle speed is less than 30km / h, it is a low speed interval; when the vehicle speed is 30km / h-80km / h, it is a medium speed interval; when the vehicle speed is higher than 80km / h, it is a high speed interval.

[0055] When the vehicle speed is less than 30km / h, the calculation formula of the target rotation speed N of the second worm is as follows:

[0056] ;

[0057] Wherein, is a low speed interval proportion coefficient, which is a fixed constant and takes a positive value. In the present application, the value is 0.5. V1=30km / h. n1 is a first basic rotation speed value for ensuring basic assist, which can be determined according to actual needs. V is the vehicle speed.

[0058] In the low speed range, the calculated value of the target rotation speed N of the second worm is positive, representing that the rotation direction of the worm wheel outer cylinder is consistent with the power output direction of the first motor. As the vehicle speed increases, the target rotation speed of the second worm gradually decreases, and the output assist of the steering gear will also decrease. However, in this low speed range, the rotation direction of the worm wheel outer cylinder is always consistent with the power output direction of the first motor, and the second worm always promotes the assist.

[0059] When the vehicle speed is 30-80km / h, the calculation formula of the target rotation speed N of the second worm is as follows:

[0060] ;

[0061] is the medium speed range proportional coefficient, and is a fixed constant with a negative value. In the present application, the medium speed range proportional coefficient is-0.4. n2 is the second basic rotation speed value.

[0062] In the medium speed range, as the vehicle speed V increases, the calculated value of the target rotation speed N of the second worm will change from positive to negative. When the target rotation speed N of the second worm is negative, it represents that the rotation direction of the worm wheel outer cylinder is opposite to the power output direction of the first motor, and the second worm will switch the rotation direction, and the second worm will change from "boosting assist" to "reducing assist".

[0063] When the vehicle speed is higher than 80km / h, the calculation formula of the target rotation speed N of the second worm is as follows:

[0064] ;

[0065] is the high speed range proportional coefficient, and is a fixed constant with a positive value. In the present application, the high speed range proportional coefficient is 0.3. V2=80km / h; n3 is the third basic rotation speed value. In this high speed range, the calculated value of the target rotation speed N of the second worm is always negative, representing that the rotation direction of the worm wheel outer cylinder is opposite to the power output direction of the first motor, and the second worm plays a role of reducing assist and increasing high speed driving stability.

[0066] When the first motor 3 fails, the self-locking of the first motor 3 fixes the first sun gear shaft 25, at this time, the second motor 13 is used as the assist motor, the second motor 13 drives the second worm 12 to rotate and drives the worm gear outer cylinder 11 to rotate, and the torque is transmitted to the second sun gear through the second planetary gear 31 and the second sun gear, and the second sun gear shaft 14 transmits the torque to the input shaft 1 to realize the assist effect. When the first motor 3 fails, the system can quickly switch to the working mode of using the second motor 13 as the assist motor, ensuring that the steering system can still work normally, providing assist for the driver, ensuring that the steering operation of the vehicle is not affected, thereby improving the reliability and stability of the entire steering system, reducing the risk of loss of steering assist caused by motor failure, and enhancing the safety of vehicle driving.

[0067] The controllers of the first motor 3 and the second motor 13 communicate through CAN lines, when the first motor 3 fails, the controller receives the signal sent by the control unit of the steering gear and drives the second motor 13 to make relevant movements. When the second motor 13 fails, the first motor 3 normally assists.

[0068] The input shaft 1 includes a front end shaft body 1a and a main shaft body 1b, and the front end shaft body 1a and the main shaft body 1b are connected through a torsion bar 21. A torque rotation sensor 22 is arranged at the connection between the front end shaft body 1a and the main shaft body 1b. The torque rotation sensor 22 is used to detect the relative torsion angle between the front end shaft body 1a and the main shaft body 1b. One end of the torsion bar 21 is fixedly connected with the front end shaft body 1a through a first pin shaft 23, and the other end of the torsion bar 21 is fixedly connected with the main shaft body 1b through a second pin shaft 24.

[0069] The input shaft 1 is composed of a front end shaft body 1a, a main shaft body 1b and a torsion bar 21. The torsion bar 21, as an elastic connecting piece, is connected with the front end shaft body 1a and the main shaft body 1b at two ends respectively. When the driver rotates the steering wheel, the front end shaft body 1a is first subjected to force and rotates, and drives the main shaft body 1b to rotate through the torsion bar 21. Due to the elastic property of the torsion bar 21, an elastic deformation proportional to the size of the torque is generated in the process of transmitting the torque, resulting in a small relative torsion angle between the front end shaft body 1a and the main shaft body 1b. The torque rotation sensor 22 is installed at the connection between the front end shaft body 1a and the main shaft body 1b, and can accurately capture the relative torsion angle between the two. The angle signal is directly related to the steering torque applied by the driver (the greater the torsion angle, the greater the steering force applied by the driver), and also reflects the direction and speed of the steering operation. After the sensor converts the mechanical angle signal into an electrical signal, it is transmitted to the control unit of the steering system as the core basis for adjusting the size of the assist.

[0070] The application further comprises a shell assembly, which comprises a first shell part 5, a second shell part 6, a third shell part 7, the first shell part 5, the second shell part 6 and the third shell part 7 being fixedly connected through screws; the second worm 12 and the worm wheel outer cylinder 11 are arranged in the first shell part 5, and the second motor 13 is fixedly connected with the first shell part 5; the first belt wheel 15, the second belt wheel 16 and the synchronous belt 17 are all located in the second shell part 6, the first worm 8, the rocker arm frame 10 and the roller 9 are located in the third shell part 7, the first worm 8 is rotatably matched with the third shell part 7 through a bearing 20, and the swing arm shaft is rotatably matched with the third shell part 7.

[0071] The application is not limited to the above-mentioned best mode of implementation, and anyone can derive other various forms of products under the inspiration of the application, but regardless of any change in shape or structure, any technical solution with the same or similar to the application falls within the protection scope of the application.

Claims

1. A variable-ratio spherical worm roller electrically redundant steering gear characterized by, The transmission ratio control device is connected with the power unit, and the second sun shaft is in transmission connection with the input shaft. When the vehicle speed is less than 30km / h, the calculation formula of the target rotating speed N of the second worm is as follows: When the vehicle speed is 30km / h-80km / h, the calculation formula of the target rotating speed N of the second worm is as follows: ； wherein, is a low speed zone proportionality coefficient, V1=30 km / h; n1 is a first base rotational speed value; V is a vehicle travel speed; When the vehicle speed is higher than 80km / h, the calculation formula of the target rotating speed N of the second worm is as follows: ； n2 is the second base speed value; and n3 is the third base speed value. The first worm is a spherical worm, and the circumferential direction of the roller is provided with an annular roller groove, the cross section of the roller groove is matched with the cross section of the helical tooth on the worm, and the helical tooth on the worm is embedded in the roller groove on the roller. ； V2=80 km / h; n3is the third base speed value.

2. The variable-ratio spherical worm roller electrically redundant steering gear of claim 1, wherein, The power unit comprises a first motor and a speed reducer connected with the first motor.

3. The variable-ratio spherical worm roller motor-redundant steering gear of claim 1, wherein, When the vehicle speed is in the first speed range and in the steering state, the second motor drives the second worm to rotate, the second worm drives the worm outer cylinder to rotate, the rotating direction of the worm outer cylinder is consistent with the output rotating direction of the first motor, the transmission ratio control device plays a role of improving the output power; when the vehicle speed is in the second speed range and in the steering state, the second motor drives the second worm to rotate, the second worm drives the worm outer cylinder to rotate, the rotating direction of the worm outer cylinder is opposite to the output rotating direction of the first motor, and the transmission ratio control device plays a role of reducing the output power.

4. The variable-ratio spherical worm roller motor-redundant steering gear of claim 1, wherein, When the first motor fails, the first sun shaft is fixed by the self-locking of the first motor, at this time, the second motor is used as a booster motor, the second motor drives the second worm to rotate to drive the worm outer cylinder to rotate, the torque is transmitted to the second sun shaft through the second planetary gear and the second sun, the second sun shaft transmits the torque to the input shaft to realize the boosting effect.

5. The variable-ratio spherical worm roller motor-redundant steering gear of claim 1 wherein, ​ 6. The variable-ratio spherical worm roller motor-redundant steering gear of claim 1, wherein, The second sun gear is provided with a first pulley, the input shaft is provided with a second pulley, and the first pulley and the second pulley are connected with a synchronous belt.

7. The variable-ratio spherical worm roller motor-redundant steering gear of claim 1, wherein, The input shaft comprises a front end shaft body and a main shaft body, and the front end shaft body is connected with the main shaft body through a torsion bar; a torque rotation angle sensor is arranged at the connection position of the front end shaft body and the main shaft body; and the torque rotation angle sensor is used for detecting the relative torsion angle between the front end shaft body and the main shaft body.

8. The variable-ratio spherical worm roller motor-redundant steering gear of claim 6, wherein, Further comprising a shell assembly, the shell assembly comprises a first shell part, a second shell part and a third shell part, the first shell part, the second shell part and the third shell part are fixedly connected through screws; the second worm and the worm wheel outer cylinder are arranged in the first shell part, and the second motor is fixedly connected with the first shell part; the first pulley, the second pulley and the synchronous belt are located in the second shell part, the first worm, the rocker arm frame and the roller are located in the third shell part, and the swing arm shaft is rotationally matched with the third shell part.

Images