阅读说明：本技术 一种商用车电动助力转向装置 (Electric power steering device of commercial vehicle ) 是由 陈锋 王辉 温选辉 吴林健 章炬辉 鲍柯 常相要 张军成 于 2021-06-24 设计创作，主要内容包括：本发明公开一种商用车电动助力转向装置,包括：循环球机构包括螺杆和螺母,螺杆与输入结构轴连接,螺母套设在螺杆,螺母与摇臂机构啮合连接,以带动摇臂机构摆动并输出扭矩；循环球机构还包括钢球以及两个并列设置的第一导管、第二导管,螺母内螺纹和螺杆外螺纹之间形成第一滚道；第一导管和第二导管固设在螺母的外侧,第一导管和第二导管内设置有第二滚道,第一导管内的第二滚道的首尾与第一滚道的第一段相连通,第二导管内的第二滚道的首尾与第一滚道的第二段相连通,钢球可在第一滚道和第二滚道内滚动；第一段和第二段内的钢球滚动的有效圈数均为2.5圈。该装置能够输出大扭矩,有效的满足商用车的动力转向需求。(The invention discloses an electric power steering device of a commercial vehicle, which comprises: the circulating ball mechanism comprises a screw rod and a nut, the screw rod is connected with the input structural shaft, the nut is sleeved on the screw rod, and the nut is meshed with the rocker arm mechanism to drive the rocker arm mechanism to swing and output torque; the circulating ball mechanism also comprises a steel ball, a first guide pipe and a second guide pipe which are arranged in parallel, and a first roller path is formed between the nut internal thread and the screw rod external thread; the first guide pipe and the second guide pipe are fixedly arranged on the outer side of the nut, a second raceway is arranged in the first guide pipe and the second guide pipe, the head and the tail of the second raceway in the first guide pipe are communicated with the first section of the first raceway, the head and the tail of the second raceway in the second guide pipe are communicated with the second section of the first raceway, and the steel ball can roll in the first raceway and the second raceway; the effective number of rolling circles of the steel balls in the first section and the second section is 2.5 circles. The device can output large torque, and effectively meets the power steering requirement of the commercial vehicle.)

1. The utility model provides an electric power assisted steering device of commercial car which characterized in that includes: the device comprises a power structure, an input structure, a worm and gear mechanism, a circulating ball mechanism and a rocker arm mechanism;

the circulating ball mechanism comprises a screw rod and a nut, the screw rod is connected with the input structural shaft, the nut is sleeved on the screw rod, and the nut is meshed with the rocker arm mechanism to drive the rocker arm mechanism to swing and output torque;

the worm and gear mechanism comprises a worm gear and a worm, the power structure is in driving connection with the worm, the worm gear is sleeved on the screw, and the worm is in meshing connection with the worm gear to drive the screw to rotate;

the circulating ball mechanism also comprises a steel ball, a first guide pipe and a second guide pipe which are arranged in parallel, and a first roller path is formed between the nut internal thread and the screw rod external thread;

the first guide pipe and the second guide pipe are fixedly arranged on the outer side of the nut, a second roller path is arranged in the first guide pipe and the second guide pipe, the head and the tail of the second roller path in the first guide pipe are communicated with the first section of the first roller path, the head and the tail of the second roller path in the second guide pipe are communicated with the second section of the first roller path, the first section and the second section are arranged in parallel and are separated by a preset distance, and the steel ball can roll in the first roller path and the second roller path;

the effective rolling circles of the steel balls in the first section and the second section are both 2.5 circles.

2. The electric power steering device for the commercial vehicle according to claim 1, wherein the diameter of the steel ball is 7.144mm to 9.525mm, the thread pitch of the screw and the nut is 9mm to 15mm, the central helix angle of the steel ball is controlled to be 5.3 to 6.5 degrees, the helix angle of the steel ball at the contact point with the screw is controlled to be 6.2 to 7.1 degrees, the helix angle of the steel ball at the contact point with the nut is controlled to be 4.6 to 5.3 degrees, the radius of the double arcs of the nut, the screw and the contact raceway of the steel ball is controlled to be 3.5mm to 5.5mm, the central distance of the steel ball is controlled to be 32mm to 48mm, and the wall thickness of the guide pipe is 1.0mm to 2.0 mm.

3. The electric power steering device for the commercial vehicle according to claim 2, wherein the speed ratio of the worm gear mechanism is controlled to be 21: 1-26: 1.

4. The electric power steering device for the commercial vehicle according to claim 3, wherein the speed ratio of the circulating ball mechanism is controlled to be 17: 1-23: 1.

5. The electric power steering device for the commercial vehicle according to claim 4, wherein a rack is arranged outside the nut, the rocker arm mechanism comprises sector teeth meshed with the rack, the modulus of the sector teeth is controlled within the range of 5.0-8.0, the theoretical tooth number is controlled within the range of 12-15 teeth, and the effective tooth number is 3-5 teeth.

6. The electric power steering apparatus for commercial vehicle according to any one of claims 1 to 5, wherein the input structure includes an input shaft, a torsion bar and an angle torque sensor, and the power structure includes a motor and a controller;

the input shaft is sleeved on the outer peripheral wall of the torsion bar, the torsion bar is connected with the screw shaft, the angle torque sensor is arranged on the outer side of the input shaft and used for sensing the deformation of the torsion bar and converting the deformation into torque and angle signals, and the angle torque sensor transmits the torque and angle signals to the controller;

the controller is connected with the motor, the controller receives the torque and angle signals to control the motor to rotate, and the motor is in driving connection with the worm.

7. The electric power steering apparatus of claim 6, wherein the torsion bar is press-fitted to the input shaft and the torsion bar is press-fitted to the screw.

8. The electric power steering device for the commercial vehicle according to claim 7, wherein double-headed splines are provided at both ends of the torsion bar, the outer peripheral wall of the torsion bar is in interference fit with the inner peripheral wall of the input shaft, and the outer peripheral wall of the torsion bar is in interference fit with the inner peripheral wall of the screw.

Technical Field

The invention relates to the technical field of electric power steering devices, in particular to an electric power steering device for a commercial vehicle.

Background

The electric steering meets the requirements of automobile development electronization, automation, intellectualization, energy conservation and consumption reduction, greatly improves the comfort and safety of driving, is the development direction of an automobile steering system, and becomes the standard configuration of an automobile power steering system.

At present, passenger vehicles have already completed electric power steering, such as CEPS, PEPS, REPS and the like, but because the output torque of the electric power steering device is smaller, the steering torque requirement of large-tonnage commercial vehicles cannot be met, and the electric power steering device cannot be applied to the commercial vehicles.

Disclosure of Invention

The electric power steering device for the commercial vehicle is capable of outputting large torque and effectively meeting the power steering requirement of the commercial vehicle.

The specific technical scheme is as follows:

the utility model provides an electric power assisted steering device of commercial car mainly includes: the method comprises the following steps: the device comprises a power structure, an input structure, a worm and gear mechanism, a circulating ball mechanism and a rocker arm mechanism;

the circulating ball mechanism comprises a screw rod and a nut, the screw rod is connected with the input structural shaft, the nut is sleeved on the screw rod, and the nut is meshed with the rocker arm mechanism to drive the rocker arm mechanism to swing and output torque;

the worm and gear mechanism comprises a worm gear and a worm, the power structure is in driving connection with the worm, the worm gear is sleeved on the screw, and the worm is in meshing connection with the worm gear to drive the screw to rotate;

the circulating ball mechanism also comprises a steel ball, a first guide pipe and a second guide pipe which are arranged in parallel, and a first roller path is formed between the nut internal thread and the screw rod external thread;

the first guide pipe and the second guide pipe are fixedly arranged on the outer side of the nut, a second roller path is arranged in the first guide pipe and the second guide pipe, the head and the tail of the second roller path in the first guide pipe are communicated with the first section of the first roller path, the head and the tail of the second roller path in the second guide pipe are communicated with the second section of the first roller path, the first section and the second section are arranged in parallel and are separated by a preset distance, and the steel ball can roll in the first roller path and the second roller path;

the effective rolling circles of the steel balls in the first section and the second section are both 2.5 circles.

The commercial vehicle electric power steering device is further characterized in that the diameter of the steel ball is 7.144 mm-9.525 mm, the thread pitch of the screw rod and the nut is 9 mm-15 mm, the central helix angle of the steel ball is controlled to be 5.3-6.5 degrees, the helix angle of the steel ball and the screw rod contact point is controlled to be 6.2-7.1 degrees, the helix angle of the steel ball and the nut contact point is controlled to be 4.6-5.3 degrees, the double-arc radius of the nut, the screw rod and the steel ball contact raceway is controlled to be 3.5 mm-5.5 mm, the center distance of the steel ball is controlled to be 32 mm-48 mm, and the wall thickness of the guide pipe is 1.0 mm-2.0 mm.

The electric power steering device for the commercial vehicle is further characterized in that the speed ratio of the worm gear mechanism is controlled to be 21: 1-26: 1.

The electric power steering device for the commercial vehicle is further characterized in that the speed ratio of the circulating ball mechanism is controlled to be 17: 1-23: 1.

In the above-mentioned commercial car electric power steering device, still have such characteristic, the nut outside is provided with the rack, rocker mechanism including with the sector tooth of rack toothing, the modulus control of sector tooth is in 5.0 ~ 8.0 within ranges, and theoretical number of teeth control is in 12 tooth ~ 15 tooth within ranges, and the number of effective teeth is 3 tooth ~ 5 teeth.

In the above commercial vehicle electric power steering apparatus, the input structure includes an input shaft, a torsion bar and an angle torque sensor, and the power structure includes a motor and a controller;

the input shaft is sleeved on the outer peripheral wall of the torsion bar, the torsion bar is connected with the screw shaft, the angle torque sensor is arranged on the outer side of the input shaft and used for sensing the deformation of the torsion bar and converting the deformation into torque and angle signals, and the angle torque sensor transmits the torque and angle signals to the controller;

the controller is connected with the motor, the controller receives the torque and angle signals to control the motor to rotate, and the motor is in driving connection with the worm.

In the above commercial vehicle electric power steering apparatus, the torsion bar is press-fitted and fixed to the input shaft, and the torsion bar is press-fitted and fixed to the screw.

In the above commercial vehicle electric power steering apparatus, the two ends of the torsion bar are provided with double-headed splines, the outer peripheral wall of the torsion bar is in interference fit with the inner peripheral wall of the input shaft, and the outer peripheral wall of the torsion bar is in interference fit with the inner peripheral wall of the screw.

The positive effects of the technical scheme are as follows:

the electric power steering device for the commercial vehicle, provided by the invention, can output large torque and effectively meet the power steering requirement of the commercial vehicle.

Drawings

FIG. 1 is a schematic diagram of a first directional structure of an electric power steering apparatus for a commercial vehicle according to the present invention;

FIG. 2 is a schematic diagram of a second directional structure of the electric power steering apparatus of a commercial vehicle according to the present invention;

FIG. 3 is a schematic diagram of a third directional structure of the electric power steering apparatus of a commercial vehicle according to the present invention;

FIG. 4 is a schematic view of a first directional structure of the recirculating ball mechanism provided in the present invention;

FIG. 5 is a schematic diagram of a second directional structure of the recirculating ball mechanism provided in the present invention;

fig. 6 is a schematic diagram of a third directional structure of the recirculating ball mechanism provided by the invention.

In the drawings: 1. a power structure; 11. a motor; 12. a controller; 2. an input structure; 21. an input shaft; 22. a torsion bar; 23. an angle torque sensor; 3. a worm and gear mechanism; 31. a worm gear; 32. a worm; 4. a recirculating ball mechanism; 41. a screw; 412. a first raceway; 4121. a first stage; 4122. a second stage; 42. a nut; 421. a rack; 43. a steel ball; 44. a first conduit; 445. a second raceway; 45. a second conduit; 5. a rocker arm mechanism; 51. a rocker shaft; 511. sector gear; 52. a rocker arm; 6. a housing; 61. a recirculating ball mechanism chamber; 62. worm gear mechanism room.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below by way of embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The numbering of the components themselves, such as "first", "second", etc., is used herein only to distinguish between the objects depicted and not to have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

Referring to fig. 1 to 6, fig. 1 is a first directional structural schematic diagram of an electric power steering apparatus of a commercial vehicle according to the present invention; FIG. 2 is a schematic diagram of a second directional structure of the electric power steering apparatus of a commercial vehicle according to the present invention; FIG. 3 is a schematic diagram of a third directional structure of the electric power steering apparatus of a commercial vehicle according to the present invention; FIG. 4 is a schematic view of a first directional structure of the recirculating ball mechanism provided in the present invention; FIG. 5 is a schematic diagram of a second directional structure of the recirculating ball mechanism provided in the present invention; fig. 6 is a schematic diagram of a third directional structure of the recirculating ball mechanism provided by the invention.

The invention discloses an electric power steering device of a commercial vehicle, which comprises: the device comprises a power structure 1, an input structure 2, a worm gear mechanism 3, a circulating ball mechanism 4, a rocker arm mechanism 5 and a shell 6.

The circulating ball mechanism 4 comprises a screw rod 41, a nut 42, a steel ball 43, a first conduit 44 and a second conduit 45 which are arranged in parallel;

the screw rod 41 is connected with the input structure 2 through a shaft, and the nut 42 is sleeved on the screw rod 41.

A first raceway 412 is formed between the internal thread of the nut 42 and the external thread of the screw 41;

the first guide pipe 44 and the second guide pipe 45 are fixedly arranged on the outer side of the nut 42, a second raceway 445 is arranged in the first guide pipe 44 and the second guide pipe 45, the head and the tail of the second raceway 445 in the first guide pipe 44 are communicated with the first section 4121 of the first raceway 412, the head and the tail of the second raceway 445 in the second guide pipe 45 are communicated with the second section 4122 of the first raceway 412, the first section 4121 and the second section 4122 are arranged in parallel, and a preset distance is arranged between the first section 4121 and the second section 4122;

the steel ball 43 can roll in the first raceway 412 and the second raceway 445;

specifically, in this embodiment, in view of the characteristics of a commercial vehicle, such as large load, poor vehicle condition, poor working condition, frequent use, and long continuous driving time, the electric power steering apparatus for a commercial vehicle needs to be designed in a brand-new manner, and the design parameters are different from those of the original mechanical steering gear and hydraulic steering gear. In order to meet the requirements of product reliability and service life, the invention carries out high-strength and high-fatigue life differentiation design on the circulating ball component, and is mainly characterized in that:

in this embodiment, with a ball outer circulation raceway (in this embodiment, the raceway includes the first raceway 412 and the second raceway 445) design that can carry a large load, the nut 42, the screw 41, and the outer ball guide (including the first guide 44 and the second guide 45) form a closed raceway area in which an appropriate amount of the steel balls 43 reciprocate.

The effective rolling circles of the steel balls 43 in the first section 4121 and the second section 4122 are both 2.5 circles, the number of the steel balls 43 in the raceway is twice that in the single conduit structure, and more steel balls 43 are used for evenly distributing the load, so that the bearing capacity of the device is stronger. In addition, the first guide pipe 44 and the second guide pipe 45 are designed by adopting 2.5 circles of circulating steel ball groups, namely, 2.5 circles of steel balls 43 are arranged in an envelope channel formed by each pair of steel ball guide pipes and a raceway, compared with the design of 1.5 circles of circulating steel ball groups, the number of the steel balls 43 is increased, and the bearing capacity is improved; compared with the design of a steel ball group with 3.5 cycles and above, the steel ball 43 has good fluidity and high transmission efficiency, and the impact of the steel balls 43 is smaller.

The diameter of the steel ball 43 is optimized to enable the steel ball 43 to bear larger load, and the diameter of the steel ball 43 is controlled to be 7.144-9.525 mm.

The diameter of the screw rod 41 is optimized to ensure enough rigidity and strength, and the middle diameter of the steel ball is controlled within the range of 34 mm to 45 mm.

The screw pitch of the screw 41 and the nut 42 is 9 mm-15 mm, the central helix angle of the steel ball 43 is controlled to be 5.3-6.5 degrees, the helix angle of the contact point of the steel ball 43 and the screw 41 is controlled to be 6.2-7.1 degrees, the helix angle of the contact point of the steel ball 43 and the nut 42 is controlled to be 4.6-5.3 degrees, the double-arc radius of the contact raceway of the nut 42, the screw 41 and the steel ball 43 is controlled to be 3.5 mm-5.5 mm, the central distance of the steel ball 43 is controlled to be 32 mm-48 mm, and the wall thickness of the guide pipe is 1.0 mm-2.0 mm.

Preferably, two opposite side surfaces of the nut 42 are set to be cambered surfaces and matched with the inner wall of the shell 6 to share the radial force of the rocker arm mechanism 5 on the nut 42 and the screw rod 41, so that the pressure of the steel ball 43 and the raceway is reduced, the pitting abrasion is reduced, and the fatigue life of the circulating ball raceway and the steel ball 43 under heavy load is prolonged.

In this embodiment, the first conduit 44 and the second conduit 45 are in an external setting mode, and the first conduit 44 and the second conduit 45 both adopt an integral complete pipeline, which is different from a two-petal structure widely adopted at present, and the steel ball conduit has high precision, strong bearing capacity and greatly improved impact resistance. The inner wall is specially shaped and strengthened, the inner surface is smooth, no fold is generated, the cylindricity is high, and the steel ball 43 rolls flexibly and smoothly. The shapes of the first conduit 44 and the second conduit 45 are also optimized and subjected to finite element analysis, so that the impact of the steel ball 43 at the bending part is small, the stress is light, the bad impact is avoided, and the service life is prolonged. Through theoretical calculation and finite element analysis, the diameter of the double arcs of the raceway has a large influence on the service life of the circulating ball mechanism 4, and the most effective parameter values are found through multiple times of theoretical calculation and experimental verification in order to overcome pitting fatigue wear of the steel ball 43 and the raceway thereof.

The lubricating performance of the circulating ball mechanism 4 also affects the service life, the pressure resistance, the wear resistance, the oxidation resistance and the adhesiveness of the lubricating oil of the original mechanical steering gear or the original hydraulic steering gear can not meet the special requirements of the electric steering gear on the lubricating performance, the base oil and the anti-pressing agent, the anti-wear agent and the like with the optimal proportion are selected through adjusting the formula for many times, the adhesiveness and the oxidation resistance of the lubricating oil are improved, and the requirements of complicated use conditions and ultra-long service life of the electric steering gear of the commercial vehicle are met through test comparison verification.

The nut 42 is engaged with the rocker mechanism 5 to drive the rocker mechanism 5 to swing and output torque.

Further, a rack 421 is disposed outside the nut 42, and the rocker arm mechanism 5 includes a sector gear 511 engaged with the rack 421. The screw 41 rotates to drive the nut 42 to move linearly, the linear motion of the nut 42 is converted into the rotary motion of the rocker arm mechanism 5, and the rocker arm mechanism 5 is driven to swing and output torque.

Specifically, the rocker arm mechanism 5 comprises a rocker arm shaft 51 and a rocker arm 52, sector teeth 511 are arranged on the rocker arm shaft 51, the part of the rocker arm shaft 51, which extends out of the housing 6, is positioned in the housing 6, part of the rocker arm shaft 51 extends out of the housing 6 and is connected with the rocker arm 52, preferably, the rocker arm shaft 51 is in splined connection with the rocker arm 52, the rocker arm 52 is connected with other structures of the whole vehicle, such as a steering drag link, a nut 42 is meshed with the sector teeth 511 of the rocker arm shaft 51 through a rack 421, the linear motion of the nut 42 is converted into the rotary motion of the rocker arm shaft 51, the speed is reduced and the torque is increased, the torque of the whole steering device is output to the rocker arm 52 through the splines of the rocker arm shaft 51, and the rocker arm 52 drives the drag link of the whole vehicle to move, so as to achieve the steering of the vehicle.

Preferably, in order to ensure sufficient steering force and meshing smoothness and ensure the strength of the sector gear 511, the modulus of the sector gear 511 is controlled within the range of 5.0-8.0, the theoretical tooth number is controlled within the range of 12-15 teeth, and the effective tooth number is 3-5 teeth.

The worm and gear mechanism 3 comprises a worm wheel 31 and a worm 32, the power structure 1 is in driving connection with the worm 32, the worm wheel 31 is sleeved on the screw rod 41, and the worm 32 is in meshing connection with the worm wheel 31 to drive the screw rod 41 to rotate.

The worm wheel 31 is arranged on the screw rod 41, the mounting axial position of the worm wheel 31 is positioned through the rabbet on the screw rod 41, and as the axial position of the screw rod 41 is accurately positioned and the mounting position of the worm 32 is fixed, the mounting sizes of the worm wheel 31 and the worm 32 are also effectively controlled, and the axial clearance adjustment is not required again, so that the assembly precision and the assembly efficiency are improved, the consistency of products is ensured, the assembly manufacturability is good, the influence of human factors is reduced, and the automation is easy to realize.

Further, the power structure 1 includes a motor 11 and a controller 12. The input structure 2 includes an input shaft 21, a torsion bar 22, and an angular torque sensor 23.

The input shaft 21 is sleeved on the outer peripheral wall of the torsion bar 22, the torsion bar 22 is connected with the screw rod 41 through a shaft, the angle torque sensor 23 is arranged on the outer side of the input shaft 21, the angle torque sensor 23 is used for sensing the deformation of the torsion bar 22 and converting the deformation into a torque signal and an angle signal, and the angle torque sensor 23 transmits the torque signal and the angle signal to the controller 12.

Specifically, the torsion bar 22 is press-fitted and fixed to the input shaft 21, and the torsion bar 22 is press-fitted and fixed to the screw 41.

Preferably, double-headed splines are provided at both ends of the torsion bar 22, the outer peripheral wall of the torsion bar 22 is in interference fit with the inner peripheral wall of the input shaft 21, and the outer peripheral wall of the torsion bar 22 is in interference fit with the inner peripheral wall of the screw 41.

Specifically, the torsion bar 22 is double-headed splined at both ends.

The torsion bar 22 in this embodiment fixes the input shaft 21, the torsion bar 22 and the screw 41 together by press fitting through interference fit, which has the advantages of high assembly efficiency, high reliability and more precise positioning compared with riveting through a cylindrical pin.

The controller 12 is connected with the motor 11, and the controller 12 receives the torque and the angle signal to control the motor 11 to rotate.

The motor 11 is in driving connection with the worm 32, and specifically, the motor 11 is in driving connection with the worm 32 through a coupling (not shown). The motor 11, under the control of the controller 12, drives the worm 32 to rotate, and further drives the worm wheel 31 to rotate, and the worm wheel 31 drives the screw rod 41 to rotate. Alternatively, the motor 11 employs a brushless motor.

When a driver starts to steer, the input shaft 21 of the steering device is driven to rotate through a steering wheel and a steering column, then a torque signal and a rotation angle signal of the driver are collected in real time and output to the controller 12 of the steering device through the angle torque sensor 23 arranged on the input shaft 31, the controller 12 judges and processes the signals, and the rotation direction of the motor 11 is controlled according to a specific power-assisted characteristic curve and appropriate power-assisted torque is output in a servo mode. An output shaft of the motor 11, such as a brushless motor, is connected with the worm 32, the worm 32 is meshed with the worm wheel 31 to realize the first-stage speed reduction and reinforcement, and the speed ratio of the worm and gear mechanism 3 is controlled within the range of 21: 1-26: 1 according to the characteristics and requirements of the commercial vehicle so as to ensure the requirements of the whole vehicle such as the maximum rotating speed of a steering wheel, steering control hand force, emergency avoidance and the like. Among them, the transmission ratio of the automobile is also called a speed ratio. It is the ratio of the rotation speed of the front and the rear transmission mechanisms of the transmission device in the automobile transmission system.

The worm wheel 31 is rigidly connected with the screw rod 41, and the worm wheel 31 rotates to drive the screw rod 41 to synchronously rotate; the circulating ball mechanism 4 composed of the screw rod 41, the nut 42, the steel balls 43 and the like is a two-stage speed reducing mechanism, the rotating torque of the screw rod 41 is transmitted to the nut 42 through the steel balls 43 which are in external circulation, the nut 42 linearly moves along the screw rod 41 and outputs thrust through the rack 421 at the lower end, and in order to guarantee the total number of turns and the steering sensitivity of a steering wheel of a commercial vehicle and meet the requirements on the steering portability and the sensitivity, the speed ratio of the circulating ball mechanism 4 is controlled within the range of 17: 1-23: 1.

Preferably, in the embodiment, the housing 6 is provided as an integrated structure, an inner wall is cast inside the housing 6 to separate the worm and gear mechanism 3 from the recirculating ball mechanism 4, and the recirculating ball mechanism chamber 61 and the worm and gear mechanism chamber 62 are respectively arranged on two sides of one housing 6, so that the housing 6 is designed integrally, and compared with a split design, the integrated circulating ball mechanism has the advantages of compact structure, small volume and light weight, and is convenient for the installation and arrangement of the whole vehicle; in addition, the shell machining center completes one-time clamping machining, the size precision and the position precision of each shaft system are high, split type assembly adjustment is not needed, the assembly precision and the consistency of an assembly product are high, the overall dimension of the product is greatly reduced, the weight is reduced, more importantly, the whole vehicle arrangement is facilitated, extra design work is simplified, and convenience is provided for installing and using the product in an automobile host factory.

The electric power steering device of the commercial vehicle in the embodiment of the invention comprises the following components:

compared with the existing electric steering system, the electric power steering device of the commercial vehicle is highly integrated, and has the characteristics of compact structure, small volume, light weight, convenience in installation, maintenance-free property and the like. By adopting the motor 11, the controller 12 and the non-contact angle torque sensor and through three-stage speed reduction and force reinforcement of a specially designed worm and gear mechanism 3, a circulating ball mechanism 4, a sector gear rack mechanism and the like, the output torque is greatly increased to 3500 Nm, and the power steering requirement of a commercial vehicle with the total mass of 10 tons is met.

The electric steering device for the commercial vehicle meets the electric steering requirement of the commercial vehicle, fills the domestic and foreign blank, provides technical support for the intellectualization of the commercial vehicle, saves the energy consumption of the whole vehicle by 3-5 percent, and reduces the emission and use cost.

The electric steering device for the commercial vehicle solves the problem of pitting fatigue of the circulating ball mechanism 4, overcomes a short plate on the electric steering device mechanism for the electric steering device for the commercial vehicle has greatly prolonged service life, has practicability, and meets the requirements of a small card, a light card, a minibus, a passenger car and the like for electric steering below 5 tons of front axle load.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.