CN110282006B

CN110282006B - Manual mode of electric power steering device

Info

Publication number: CN110282006B
Application number: CN201910257460.5A
Authority: CN
Inventors: 刘富强; 张勇; 李玉; 武建斌; 王东亮; 邱实
Original assignee: China North Vehicle Research Institute
Current assignee: China North Vehicle Research Institute
Priority date: 2016-10-09
Filing date: 2016-10-09
Publication date: 2020-08-18
Anticipated expiration: 2036-10-09
Also published as: CN107140007A; CN110282006A; CN107140007B

Abstract

The invention provides a power-assisted manual mode of an electric power steering device, wherein an angle torque sensor is axially connected with an input shaft and a screw shaft, a control system calculates the target torque of a motor assembly by acquiring the output torque value of the angle torque sensor, the motor assembly is driven to output the power-assisted torque in a torque control mode, the motor assembly transmits the torque to a worm through a plum blossom connecting sleeve assembly, the torque is applied to the screw shaft and drives the screw shaft to rotate after the speed and the torque are reduced and increased through a worm gear, a steering nut is pushed to horizontally move, and the thrust and the linear motion stroke of the steering nut are converted into the torque and the angular displacement by the tooth sector shaft assembly due to the meshing of the steering nut and the tooth sector shaft. The manual power-assisted mode can ensure the effect of improving the steering device and has the effect of automatically preventing rollover or sideslip.

Description

Manual mode of electric power steering device

Technical Field

The invention belongs to the field of electromechanical systems and motor vehicle application, and particularly relates to a heavy recirculating ball type dual-mode electric power steering device and a shell assembly thereof.

Background

From the situation of the automobile industry, with the increasing number of fuel vehicles, the environmental pollution caused by vehicle emission is more and more serious, and meanwhile, petroleum serving as a non-renewable energy source faces the crisis of exhaustion, so that the fuel oil serving as a low-emission or zero-emission electric vehicle and a hybrid vehicle becomes a hot point of government and social attention due to the advantages of energy conservation, environmental protection and the like, and becomes the core development theme of the current wheeled vehicle technology. The Electric Power Steering (EPS) technology has been widely applied in domestic and foreign vehicle fields due to the obvious advantages of high integration level, energy conservation, maintenance-free and the like, but is mostly used for domestic vehicles or passenger vehicles with steering load less than or equal to 2t, and is still in a blank state when being applied to large-tonnage electric power steering technologies of electric buses, heavy trucks, special vehicles and the like, so that the market demand is urgent and the prospect is wide.

From the military requirement situation, the military wheeled vehicle has the operating stability requirement far higher than that of the civil vehicle due to the factors of large single-axle load, complex road conditions (such as trenches, off-road mountain roads, ice and snow roads, muddy roads and the like), harsh use conditions and the like, and the chassis of the wheeled vehicle meets the requirement of high maneuverability during highway military combat and also has better driving stability and off-road safety under extremely harsh road conditions. Among them, the steering system of the wheeled vehicle is the most direct factor affecting the steering stability and driving safety of the wheeled vehicle, and its own performance determines the overall performance of the chassis system of the wheeled vehicle. At present, a hydraulic power-assisted steering system is basically adopted in a military wheeled vehicle steering system in China, and an actuating mechanism is a circulating ball type hydraulic power-assisted steering device, so that the steering and aligning of the vehicle are mainly determined by steering positioning parameters, such as a caster angle of a main pin and a caster angle of the main pin, and the aligning capability of the vehicle is poor and unstable when the error of the positioning parameters is large, so that the maneuverability of the vehicle is influenced; for another example, when a vehicle runs at a high speed, the steering feeling is "fluttering", that is, the steering power is too large, which is determined by the principle of the recirculating ball type hydraulic power steering gear, a steering pump in the hydraulic power steering system is powered by an engine, the rotating speed of the engine is increased at a high speed, the pressure of the hydraulic power steering system is increased, and the steering power is naturally increased.

From the future development trend, with the development of power battery technology, hybrid power technology, motor technology and the like, wheeled vehicles are rapidly developing towards the direction of digitization, full electrification, unmanned and intellectualization, while the traditional wheeled vehicle steering system can not meet the future requirements, more and more novel steering systems such as intelligent steering systems, active steering systems and steer-by-wire systems are gradually emerged out of the water, and the novel steering systems need to be expanded or upgraded by depending on the electric power steering technology.

At present, the electric power steering technology is mature applied in the field of small passenger vehicles, and in structural form, most of the electric power steering technology is a rack and pinion steering device or a steering column type steering device, but the electric power steering technology is not used on large-tonnage heavy vehicles, and the main technical problem is that:

1. the steering device has large output torque, high integration requirement and large overall design difficulty. Due to the actual factors such as large load (generally more than 4 tons) of a steering axle of a heavy vehicle, the unicity of the arrangement position of a power steering device (generally positioned in a power cabin) and the like, the requirements cannot be met by adopting a rack-and-pinion steering device or a steering column type steering device, a recirculating ball type structure with high integral structural strength and strong impact resistance is required to be adopted, and the existing recirculating ball type steering structure only exists in a heavy hydraulic power-assisted steering device and has no relation with an electric power steering system.

2. The key parts and parts have high structural strength requirements, and the system matching difficulty is high. Because the medium-sized vehicle has large load on a steering axle, the vehicle has severe working conditions, and is mostly used on non-paved roads or muddy off-road roads, the steering system of the vehicle can bear quite large impact load, and a quite large part of the impact load needs to be borne by the power steering device, so the strength of a shell and a transmission part in the power steering device determines the reliability and the safety of the steering system. In the case of a recirculating ball-type hydraulic power steering gear, the screw, the pinion shaft, the housing, the steering nut, and the like are often damaged by external impact loads.

3. The electromechanical matching difficulty is large. Under the constraint of a certain space range and the constraint condition of power supply quality, the size of the motor is reduced as much as possible, the power characteristic of the motor is effectively utilized, a large transmission ratio structure is matched, the requirement of low power is met, and the characteristic of large torque output is the technical bottleneck of the electric power steering technology of the heavy vehicle.

In view of the above problems, the present invention provides a new steering apparatus to solve various problems encountered in the steering of a heavy vehicle. The steering device includes: the input shaft and screw assembly, the gear sector shaft assembly, the supporting seat assembly, the worm gear, the inner end cover assembly, the outer end cover assembly, the motor assembly and the like, so a platform is needed to integrate the components, and the platform is required to have good manufacturability, easy processing and enough strength to ensure the stable and reliable work of the whole electric power steering device. In order to solve the above problems and meet the use requirements of the electric power steering apparatus, a platform, i.e., a housing structure, needs to be designed.

Disclosure of Invention

In order to meet the use requirements of the electric power steering device, the invention provides the shell of the circulating ball type electric power steering device of the steering system of the heavy wheeled vehicle, which has the advantages of good manufacturability, easy processing and forming, enough strength, capability of bearing complex and changeable impact loads and reliable use.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the utility model provides an electric power steering device's casing assembly, its characterized in that, casing assembly includes first installation cavity, second installation cavity and third installation cavity, first installation cavity is for arranging along the horizontal direction, is non-through type cavity, the second installation cavity is non-through type cavity, the third installation cavity is through type cavity, first installation cavity and second installation cavity intercommunication, first installation cavity and third installation cavity intercommunication, second installation cavity and third installation cavity do not communicate.

Preferably, the first mounting cavity is a non-through cavity with a changeable inner diameter arranged along the horizontal direction, and a first inner circular surface, a second-stage transmission cavity, a first internal thread surface, a first-stage transmission cavity and a second inner circular surface are sequentially machined from the bottom surface of the non-through end serving as a reference surface.

Preferably, the second mounting cavity is a non-through cavity with a variable inner diameter along the vertical direction, and a third inner circular surface, a worm cavity, a fourth inner circular surface and a second inner thread surface are sequentially processed from the non-through bottom surface.

Preferably, the firstThe cross verticality of the axis of the first mounting cavity and the axis of the third mounting cavity is not more than

Preferably, the axes of the first mounting cavity and the second mounting cavity are perpendicular, and the axes of the second mounting cavity and the third mounting cavity are parallel.

Preferably, the shell material is nodular cast iron QT450-10GB 1348-2009.

An electric power steering apparatus includes the housing assembly described above.

Preferably, the electric power steering device further comprises an input shaft and screw assembly, a toothed sector shaft assembly, a support seat assembly, a turbine, a worm, an inner end cover assembly, a corner torque sensor, an outer end cover assembly, a plum blossom connecting sleeve assembly and a motor assembly, wherein a cavity with one closed end and one opened end is arranged in the shell assembly along the horizontal direction; the support seat assembly is sleeved outside the input shaft and the screw rod assembly and used for limiting the input shaft and the screw rod assembly; the worm is arranged in the shell assembly along the direction vertical to the input shaft and the screw assembly, and one end of the worm is sequentially and coaxially provided with the plum blossom-shaped connecting sleeve assembly and the motor assembly; the worm wheel is meshed with the worm, and the worm drives the input shaft and the screw assembly to rotate; the inner end cover assembly is sleeved on the input shaft and the screw rod assembly and is installed outside the turbine, the corner torque sensor is connected with the axial direction and the input shaft and the screw rod assembly, and the outer end cover assembly is sleeved on the input shaft and the screw rod assembly, is installed outside the corner torque sensor and is fixed at the front end of the shell assembly.

Preferably, a non-through cavity with variable inner diameters is arranged in the shell assembly along the horizontal direction, and a first inner circular surface B, a secondary transmission cavity C, a first internal thread surface D, a primary transmission cavity E and a second inner circular surface F are sequentially machined from a non-through end bottom surface A serving as a reference surface; a non-through cavity with variable inner diameters is also processed in the main body along the vertical direction, and a third inner circular surface H, a worm cavity I, a fourth inner circular surface J and a second inner thread surface K are sequentially processed from a non-through bottom surface G;

the inner end cover assembly is press-mounted on a second inner circular surface F of the shell assembly and limited on a circular boss formed between the second inner circular surface F and the first-stage transmission cavity E; the corner torque sensor is fixed on the outer side of the inner end cover assembly and is coaxial with the input shaft and the screw rod assembly; the worm is arranged in the worm cavity, and one end of the worm is arranged in the third inner circular surface H; the outer end cover assembly is arranged on an outer end cover flange mounting surface N of the shell assembly and is coaxial with the input shaft and the screw assembly; the gear sector shaft assembly is arranged in the secondary transmission cavity C; the worm is arranged in the screw cavity I, is meshed with the worm wheel and is fixed by a ball bearing of the fourth inner circular surface J and a locking nut in threaded connection with the second inner threaded surface K; one end of the plum blossom-shaped connecting sleeve assembly is connected with the top end of the screw rod, and the other end of the plum blossom-shaped connecting sleeve assembly is connected with an output spline shaft of the motor assembly; the motor assembly is fixed on a motor flange mounting surface M of the shell assembly through bolts; the worm gear transmits the torque of the motor to the input shaft and the screw assembly, and the input shaft and the screw assembly convert the torque into the torque output by the input shaft assembly through the gear sector shaft assembly.

Preferably, the housing assembly comprises: the device comprises a shell 1A, an output shaft oil seal, a rectangular sealing ring, an oil plug, a one-way thrust bearing, a ball bearing and an angular contact bearing; the output shaft oil seal is arranged in the secondary transmission cavity C and is coaxial with the gear sector shaft assembly;

the rectangular sealing ring and the oil plug are arranged in a threaded hole in the upper part of the shell and are used for sealing the oil filling port after lubricating oil is filled into the secondary transmission cavity C; the one-way thrust bearing is arranged on a first inner circular surface B of the shell 1A; the ball bearing is arranged in the secondary transmission cavity C and is coaxial with the gear sector shaft assembly; the angular contact bearing is arranged on the third inner circular surface H of the primary transmission cavity E.

Preferably, the input shaft and screw assembly comprises: the device comprises a first cylindrical pin, an input shaft, an elastic torsion bar, a needle bearing, a second cylindrical pin, a screw shaft, a steel ball conduit, a conduit pressure plate and a steering nut 29, wherein a variable-diameter inner cavity is arranged at one end of the screw shaft along the axial direction, a through hole is formed at one end of the screw shaft and is communicated with the inner cavity, one end of the elastic torsion bar is inserted into the inner cavity, and the second cylindrical pin is inserted into the through hole, so that the coaxial relative rotation of one end of the elastic torsion bar and the screw shaft is locked; the needle bearing is inserted into the reducing inner cavity and is abutted against the side part of the inner cavity; the middle part of the input shaft is provided with a cavity structure along the axial direction, the second end of the input shaft is provided with a through hole, the through hole is communicated with the cavity structure, the other end of the elastic torsion bar is inserted into the cavity structure of the input shaft, and the first cylindrical pin is inserted into the through hole, so that the relative rotation between the other end of the elastic torsion bar and the input shaft is locked; a first end of the input shaft abuts against a needle bearing; the other end of the screw shaft is provided with a steering nut, a plurality of steel ball injection holes are processed on the upper surface of the steering nut, and after steel balls are injected, a steel ball guide pipe and a guide pipe pressing plate for fixing the steel ball guide pipe are installed on the upper portion of the steering nut.

Preferably, the sector shaft assembly includes: the gear sector shaft, the gear sector shaft side cover plate, the gear sector shaft adjusting pin, the gear sector shaft adjusting nut, the gear sector shaft plug screw and the needle bearing; the gear sector shaft comprises a gear sector and a shaft, the gear sector is processed into a sector gear structure with involute bevel teeth, one end of the shaft is provided with an annular groove, a gear sector shaft adjusting pin is inserted into the gear sector shaft annular groove, a gear sector shaft plug screw is sleeved outside the gear sector shaft adjusting pin and has a certain interval with the gear sector shaft adjusting pin, one end of the shaft is provided with a gear sector shaft side cover plate, and a needle bearing is arranged between the gear sector shaft side cover plate and the shaft; the side cover plate is provided with a certain interval with one end of the shaft along the axial direction of the shaft, a through hole is arranged on the side cover plate, the sector shaft adjusting pin extends through the hole on the side cover plate from the annular groove, and the adjusting nut is sleeved on the sector shaft adjusting pin and is arranged and abutted against the outer part of the sector shaft side cover plate.

Preferably, the support seat assembly includes: a support seat and a one-way thrust angular contact bearing; the supporting seat is of a through annular structure with variable inner diameter, external threads are machined on the outer circumference of the supporting seat, and the one-way thrust angular contact bearing is installed inside the supporting seat 41; after the support seat assembly is axially sleeved with the input shaft and the screw rod assembly, the input shaft and the screw rod assembly are mounted and limited by fastening the outer threads of the support seat assembly on the first inner thread surface D of the shell assembly.

Preferably, the inner diameter circular surface of the turbine is provided with a key groove, the surface of the inner diameter circular surface of the turbine is provided with a notch, and the turbine, the input shaft and the screw assembly are arranged to be capable of coaxially rotating.

Preferably, the upper end of the screw is processed with an external spline, the lower end of the screw is a smooth cylindrical surface inner diameter circular surface, the lower end of the screw is axially arranged in the screw cavity and is matched with the inner circular surface of the angular contact bearing, and the upper part of the screw is sleeved with a hollow locking plug screw which is processed with an external thread and is fastened on the second inner thread surface K.

Preferably, the diverter inner end cap assembly comprises: the inner end cover, the framework oil seal, the corner torque sensor positioning plate and the sensor fixing rubber block; the inner surface of the inner end cover is provided with a threaded hole for mounting a corner torque sensor positioning plate and a corner torque sensor; the sensor fixing rubber block is used for fixing the outlet end of the sensor and is fixed on the inner surface of the inner end cover.

Preferably, two ends of the plum blossom-shaped connecting sleeve assembly are of an internal spline structure, one end of the plum blossom-shaped connecting sleeve assembly is connected with an external spline end of the worm in a spline mode, and the other end of the plum blossom-shaped connecting sleeve assembly is connected with an output spline shaft of the motor assembly to play a role of a coupler; and the motor assembly is fixed on the motor mounting surface of the shell 1A in a flange connection mode after being axially mounted with the worm through the plum blossom-shaped connecting sleeve assembly.

In addition, the device greatly improves the reliability, the shock resistance and the implementability of the system through the innovative design of key components and key parts, and is mainly embodied as follows:

① in the scheme of the casing assembly, the cross verticality between the installation axis of the input shaft and screw assembly and the installation cavity axis of the gear sector shaft assembly is not more than

Secondly, the shell material is made of nodular cast iron QT450-10GB1348-2009 and subjected to aging treatment, so that the performance of the material is exerted to the maximum extent, and the strength of the shell is improved;

fillet transition is adopted outside the shell, the whole shell is formed by casting, the draft of a drawing die is 2-3 degrees, and the processing efficiency and the processing quality are improved;

the bottom surface of the shell assembly is installed in 5 holes, so that the connection strength between the device and the vehicle body is enhanced;

fifthly, carburizing the surface of the gear sector shaft for 0.8-1.2 mm, wherein the hardness requirement is 58-62 HRC, so as to exert the performance of the material to the maximum extent and improve the strength of the knuckle arm;

the side cover plate of the gear sector shaft and the shell are connected in a 4-point connection mode, so that the assembly strength of the gear sector shaft assembly, the integrity and the air tightness of the device are ensured;

a rubber pad is added in the gear sector shaft assembly, and when a gap appears after the gear sector shaft gear surface and the steering nut gear surface are engaged for a long time and under heavy load, the gap can realize flexible automatic compensation within a certain range;

the upper surface of a steering nut in the input shaft and screw assembly is provided with 4 steel ball injection holes, and after steel balls are injected, double-path steel ball circulation can be formed, so that the stress of decomposing the steel balls and the spiral grooves in the inner surface of the steering nut is reduced, and the reliability of the steering nut and the circulating steel balls is effectively improved;

the pipe clamp plate is integral dull and stereotyped structure in input shaft and the screw rod assembly, makes its can be by a large scale with the fitting of steering nut, has effectively decomposed the atress of steel ball, guarantees that the steel ball smoothly rolls, greatly reduced the steel ball when bearing huge external force, hardly push up the possibility that falls or push up bad, promoted the reliability of device.

Compared with the prior art, the invention has the following advantages:

compared with the traditional hydraulic power-assisted system, the electric power steering system (EPS) has obvious advantages in the aspects of driving form, realization principle and the like, and is mainly embodied as follows:

1. compared with the prior art, the shell assembly has the following excellent effects: the integral strength is high, complex impact vibration can be borne, and the use is reliable; the manufacturability is good, easy to process and shape, the cost is low, suitable for the batch production; the integrated level is high, the assembly is good, and the whole assembly of the steering device is easy.

2. Simple structure and space saving. The electric power steering system cancels parts such as a steering pump, a hydraulic pipeline, an oil tank and the like of a hydraulic power-assisted system, greatly simplifies the structure of the steering system, saves the space in the vehicle and enables the steering system of the wheeled vehicle to be more convenient and flexible to arrange.

3. And energy consumption is saved. The electric power steering system provides power only when the vehicle is turning, which results in energy consumption, while the hydraulic power steering system is operated all the time even when the vehicle is not turning, which results in serious energy waste.

4. And (4) maintenance-free property. Compared with a hydraulic power-assisted steering system, the electric power steering system has no leakage, and the conventional maintenance problems of seal part replacement, pipeline replacement and the like.

5. The operation stability and the safety of the vehicle are improved. Different from the single power-assisted characteristic of a hydraulic power-assisted steering system, the power-assisted characteristic of an electric power steering system is a controllable factor, so that the optimal power can be provided under various running conditions, the disturbance to a steering system caused by uneven road surfaces is reduced, the steering characteristic of a vehicle is improved, the steering control force of the vehicle during low-speed running is reduced, and the steering stability of the vehicle during high-speed running is improved.

6. A new algorithm for intelligent control is provided.

The invention provides a heavy circulating ball type dual-mode electric power steering device which comprises a steering gear shell assembly, an input shaft and screw assembly, a gear sector shaft assembly, a supporting seat assembly, a turbine, a worm, an inner end cover assembly, a corner torque sensor, an outer end cover assembly, a plum blossom connecting sleeve assembly, a motor assembly and the like. The device has very high integration level of the overall configuration, and completes the integration of a plurality of structures such as a circulating ball and sector structure, a large reduction ratio worm and gear structure, a corner torque sensor, a motor general scale and the like in the space range of the traditional circulating ball type hydraulic power-assisted steering gear with the same tonnage; the turbine is axially arranged on the input shaft and the screw assembly in a flat key connection mode and is positioned in the primary transmission cavity; the screw rod is axially arranged in a worm cavity of the steering gear shell assembly and is completely meshed with the input shaft and a steering nut in the screw rod assembly; the inner end cover assembly, the input shaft and the screw rod assembly are coaxially arranged and fastened in the shell of the steering gear shell assembly; the corner torque sensor assembly is required to be coaxially installed with the input shaft and the screw assembly, is positioned outside the inner end cover assembly and is fixed through an internal threaded hole machined in an inner end cover in the inner end cover assembly; the outer end cover assembly is connected to the outer end face of the shell assembly in a flange mode and is coaxial with the input shaft and the input shaft in the screw assembly; one end of the inner spline structure at two ends of the plum blossom-shaped connecting sleeve assembly is connected with the outer spline end of the worm, and the other end of the inner spline structure is connected with the outer spline end of the output shaft of the motor assembly, so that the integration of the steering gear and the motor is completed. The structural characteristics of the hydraulic power steering gear are completely different from the gear-rack type and steering column type of a small passenger car, the problem of overall output torque and system structure is effectively solved, the structure of the recirculating ball type hydraulic power steering gear is used for reference, a rotary valve structure in the recirculating ball type hydraulic power steering gear is replaced by a large reduction ratio mechanism, a corner torque sensor and the like, the conversion from hydraulic transmission to intelligent electric transmission is realized under the condition that no extra space is added, compared with the recirculating ball type hydraulic power steering gear with the same volume, the power requirement is reduced by 300%, and the maximum output torque is improved by 5%.

Drawings

Fig. 1 is a top sectional view of a heavy recirculating ball type dual-mode electric power steering apparatus.

Fig. 2 is a left side sectional view of the heavy recirculating ball type dual-mode electric power steering apparatus.

Fig. 3 is a right side sectional view of the heavy recirculating ball type dual-mode electric power steering apparatus.

FIG. 4 is a top sectional view of the steering gear housing

FIG. 5 is a sectional view of the right-hand first stage transmission chamber of the steering gear housing

FIG. 6 is a bottom view of the steering gear housing

FIG. 7 is a left side view of the steering gear housing

FIG. 8 is a right side view of the steering gear housing

FIG. 9-1 is a right side sectional view of the steering gear housing assembly.

Fig. 9-2 is a left side sectional view of the steering gear housing assembly.

Fig. 9-3 are top partial cross-sectional views of the steering gear housing assembly.

FIG. 10 is a schematic view of the input shaft and screw assembly.

Fig. 11 is a structural view of a gear sector shaft assembly.

FIG. 12 is a view showing a structure of a support base assembly.

Fig. 13 is a schematic view of a turbine structure.

Fig. 14 is a schematic view of a worm structure.

FIG. 15 is a view of the construction of the diverter inner end cap assembly.

FIG. 16 is a view of the outer end cap assembly;

FIG. 17 is a perspective view of the housing assembly;

fig. 18 is a perspective view of the housing as a whole.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

In this document, "/" denotes division and "×", "denotes multiplication, referring to formulas, if not specifically stated.

As shown in fig. 17 to 18, a housing assembly of an electric power steering apparatus, where the housing assembly (1) includes a first mounting cavity 1-1, a second mounting cavity 1-2, and a third mounting cavity 1-3, the first mounting cavity 1-1 is a non-through cavity arranged along a horizontal direction, the second mounting cavity 1-2 is a non-through cavity, the third mounting cavity 1-3 is a through cavity, the first mounting cavity 1-1 is communicated with the second mounting cavity 1-2, the first mounting cavity 1-1 is communicated with the third mounting cavity 1-3, and the second mounting cavity 1-2 is not communicated with the third mounting cavity 1-3.

The non-through cavity is a cavity with one open end and one closed end.

Preferably, the first mounting cavity 1-1 is a non-through cavity with a variable inner diameter arranged along the horizontal direction, and a first inner circular surface (B), a secondary transmission cavity (C), a first internal thread surface (D), a primary transmission cavity (E) and a second inner circular surface (F) are sequentially processed from a non-through end bottom surface (a) serving as a reference surface.

Preferably, the second mounting cavity 1-2 is a non-through cavity with a variable inner diameter along the vertical direction, and a third inner circular surface (H), a worm cavity (I), a fourth inner circular surface (J) and a second inner thread surface (K) are sequentially processed from a non-through bottom surface (G).

Preferably, the intersection perpendicularity of the first installation cavity axis and the third installation cavity axis is not more than

Preferably, the shell material is nodular cast iron QT450-10GB 1348-2009.

Preferably, the first installation cavity 1-1 is an input shaft and screw assembly installation cavity 1-1, the second installation cavity 1-2 is a turbine, worm and motor assembly installation cavity 1-2, and the third installation cavity 1-3 is a sector shaft assembly installation cavity 1-3, wherein the input shaft and screw assembly installation cavity 1-1 is transversely arranged, the end of an installation hole is leftward, the worm and motor assembly installation cavity 1-2 and the sector shaft assembly installation cavity 1-3 are arranged at the front end of the shell, the ends of the installation holes of the two cavities are both positioned at the upper end of the shell, and the worm and motor assembly installation cavity 1-2 is positioned at the left side of the sector shaft assembly installation cavity 1-3.

Wherein, the left side mounting hole end of the input shaft and screw assembly mounting cavity 1 is provided with a slot 1-a and a concave platform 1-b as shown in figure 18); a boss 1-c is arranged in the middle of the upper end of the shell, and a mounting threaded hole is formed in the boss 1-c; the lower end of the shell is provided with fixed seats 1-d (shown in figure 18), and reinforcing ribs 1-e (shown in figure 18) are arranged between the fixed seats 1-d and the shell so as to improve the strength of the fixed seats; reinforcing ribs 1-f (shown in figure 18) are arranged between the cylindrical surface at the lower end of the installation cavity 1-3 of the gear sector shaft assembly and the shell and the fixed seat 1-d so as to improve the strength of the cylindrical surface at the lower end of the installation cavity 1-3 of the gear sector shaft assembly.

Meanwhile, to solve the problems of the prior art, the present invention provides a heavy recirculating ball type dual-mode electric power steering apparatus, as shown in fig. 1 to 3, which includes: the device comprises a shell assembly 1, an input shaft and screw assembly 2, a tooth sector shaft assembly 3, a supporting seat assembly 4, a turbine 5, a worm 6, an inner end cover assembly 7, a corner torque sensor 8, an outer end cover assembly 9, a plum blossom connecting sleeve assembly 10 and a motor assembly 11;

preferably, the housing assembly described above is used as the housing assembly.

A cavity with one closed end and one opened end is arranged in the shell assembly along the horizontal direction, the input shaft and the screw assembly 2 are arranged in the cavity of the shell assembly, one end of the input shaft and one end of the screw assembly 2 are arranged at one closed end, the other end of the input shaft and the other end of the screw assembly 2 extend out of the cavity of the shell assembly, a sector shaft assembly 3 is arranged in the shell assembly 1 along the direction perpendicular to the input shaft and the screw assembly 2, and the sector shaft assembly 3 is meshed with the input shaft and the screw assembly 2 through gears; the support seat assembly 4 is sleeved outside the input shaft and screw assembly 2 and used for limiting the input shaft and screw assembly 2, so that the input shaft and screw assembly 2 cannot move up and down, left and right but can rotate; the worm 6 is arranged in the shell assembly 1 along the direction vertical to the input shaft and the screw assembly 2, and one end of the worm 6 is sequentially and coaxially provided with a plum blossom-shaped connecting sleeve assembly 10 and a motor assembly 11; the worm wheel 5 is meshed with the worm, and the worm 6 drives the input shaft and the screw assembly 2 to rotate; the inner end cover assembly 7 is sleeved on the input shaft and screw assembly 2 and is installed outside the turbine 5, the corner torque sensor 8 is connected with the input shaft and screw assembly 2 in the axial direction, and the outer end cover assembly 9 is sleeved on the input shaft and screw assembly 2, is installed outside the corner torque sensor 8 and is fixed at the front end of the shell assembly 1.

The invention provides an electric power steering device of a heavy vehicle with a novel structure, which has very high integration level of the overall configuration, and completes the integration of a plurality of structures such as a sector structure, a large reduction ratio worm and gear structure, a corner torque sensor, a motor general name and the like in the space range of the prior circulating ball type hydraulic power steering gear with the same tonnage, thereby eliminating parts such as a steering pump, a hydraulic pipeline, an oil tank and the like of a hydraulic power steering system, greatly simplifying the structure of the steering system, saving the space in the vehicle and enabling the steering system of a wheeled vehicle to be more conveniently and flexibly arranged.

Preferably, the heavy vehicle is a vehicle having a load of more than 5 tons.

Preferably, the housing assembly 1 is an important part of the device, and a non-through complex cavity with variable inner diameters is arranged in the body along the horizontal direction, as shown in fig. 4, a first inner circular surface B, a secondary transmission cavity C, a first inner threaded surface D, a primary transmission cavity E and a second inner circular surface F are sequentially processed from a non-through end bottom surface a serving as a reference surface; a non-through cavity with variable inner diameters is also processed in the main body along the vertical direction, and as shown in fig. 5, a third inner circular surface H, a worm cavity I, a fourth inner circular surface J and a second inner thread surface K are sequentially processed from a non-through bottom surface G.

As shown in fig. 6, the housing assembly 1 has a plurality of, preferably 5, internally threaded mounting holes formed in the outer bottom surface thereof, an upper end cover flange mounting surface L as shown in fig. 4 and a motor flange mounting surface M as shown in fig. 7 formed in the top surface thereof, and an outer end cover flange mounting surface N as shown in fig. 8 formed in the side surface thereof.

The input shaft and the screw rod assembly 2 are axially arranged in the shell assembly 1, axially limited and fixed through a support seat assembly 4, and the support seat assembly 4 is arranged on a first inner thread surface D of the shell assembly 1, preferably in a screw connection mode; the worm wheel 5 is axially arranged on the input shaft and the screw assembly 2 in a flat key connection mode and is positioned in the primary transmission cavity E; the inner end cover assembly 7 is pressed on the second inner circular surface F of the shell assembly 1 in a tight fit mode and is limited on a circular boss formed between the second inner circular surface F and the primary transmission cavity E; the corner torque sensor 8 is fixed on the outer side of the inner end cover assembly 7 through a screw and is coaxial with the input shaft and the screw assembly 2; the outer end cover assembly 9 is connected through a bolt, is arranged on an outer end cover flange mounting surface N of the shell assembly 1 and is coaxial with the input shaft and the screw assembly 2; the gear sector shaft assembly 3 is vertically arranged in the secondary transmission cavity C, and the gear sector is meshed with the input shaft and a steering nut in the screw assembly 2 and is fixedly connected with an upper end cover flange mounting surface L of the shell assembly 1 through a bolt; the worm 7 is axially arranged in the screw cavity I, is meshed with the turbine 6 and is fixed by a ball bearing of the fourth inner circular surface J and a lock nut in threaded connection with the second inner threaded surface K; the plum blossom-shaped connecting sleeve assembly 10 is of a structure with internal splines on two sides and is axially connected with the top end of the screw and an output spline shaft of the motor assembly 11; the motor assembly 11 is fixed on a motor flange mounting surface M of the shell assembly 1 through bolts; the device transmits the torque of the motor to the input shaft and screw assembly 2 through the worm gear and the worm, and the input shaft and screw assembly 2 converts the torque into the torque output by the input shaft assembly through the gear sector shaft assembly 3.

The invention can integrate all parts of the steering device through the shell with the special internal structure, and realizes the electric power steering device of the heavy vehicle under the condition of not increasing extra space.

Preferably, in the scheme of the shell assembly of the device, the cross verticality of the installation axis of the input shaft and the screw assembly and the axis of the installation cavity of the gear sector shaft assembly is not more than

The meshing area between the gear surface of the gear sector shaft and the gear surface of the steering nut is maximized, and compared with the meshing relation with the position degree out of tolerance, the transmission efficiency is improved by more than 5%.

Preferably, the shell material is made of nodular cast iron QT450-10GB1348-2009 and subjected to aging treatment so as to exert the performance of the material to the maximum extent and improve the strength of the shell.

Preferably, the outer part of the shell adopts fillet transition, the whole shell adopts casting forming, the draft angle is 2-3 degrees, and the processing efficiency and the processing quality are improved.

The bottom surface installation mode of the shell assembly is 5-hole installation, and the connection strength between the device and the vehicle body is enhanced.

As shown in fig. 9-1 to 9-3, the housing assembly 1 includes: the device comprises a shell 1A, an output shaft oil seal 12, a rectangular sealing ring 13, an oil plug 14, a one-way thrust bearing 15, a ball bearing 16 and an angular contact bearing 17; the output shaft oil seal 12 is arranged in the secondary transmission cavity C and is coaxial with the sector shaft assembly 3, and is used for sealing the output end of the sector shaft assembly 3 and the bottom surface of the shell to ensure that lubricating oil does not leak from the output shaft end of the sector;

the rectangular sealing ring 13 and the oil plug 14 are arranged in a threaded hole in the upper part of the shell and are used for sealing an oil filling port after lubricating oil is filled into the secondary transmission cavity C; the outer circular surface of the one-way thrust bearing 15 is tightly matched and arranged on the first inner circular surface B of the shell 1A, and the axial direction is tightly attached to the non-through bottom surface A, so that the input shaft and the screw assembly 2 are conveniently arranged and limited, and the smooth rotation of the input shaft and the screw assembly is ensured; the ball bearing 16 is arranged in the secondary transmission cavity C and is coaxial with the sector gear shaft assembly 3, and the ball bearing is used for ensuring the coaxiality of the sector gear shaft assembly 3 and the shell 1A and reducing the rotation resistance of the sector gear shaft assembly 3; the angular contact bearing 17 is arranged in the first-stage transmission cavity E, the outer circular surface of the angular contact bearing is arranged in the third inner circular surface H in a tight fit mode, and the bottom surface is tightly attached to the non-through bottom surface G, so that the worm 6 can be conveniently arranged and limited, and the smooth rotation of the worm is guaranteed.

As shown in fig. 10, the input shaft and screw assembly 2 includes: the device comprises a first cylindrical pin (21), an input shaft (22), an elastic torsion bar (23), a needle bearing (24), a second cylindrical pin (25), a screw shaft (26), a steel ball guide pipe (27), a guide pipe pressing plate (28) and a steering nut (29), wherein one end of the screw shaft (26) is provided with a variable-diameter inner cavity along the axial direction, and one end of the screw shaft (26) is provided with a through hole, preferably the through hole is processed along the direction perpendicular to the axial direction; the through hole is communicated with the inner cavity, one end of the elastic torsion bar (23) is inserted into the inner cavity, and the second cylindrical pin (25) is inserted into the through hole, so that the coaxial relative rotation of one end of the elastic torsion bar (23) and the screw shaft (26) is locked; the needle roller bearing (24) is inserted into the variable-diameter inner cavity and abuts against the side part of the inner cavity; a cavity structure is arranged in the middle of the input shaft (22) along the axial direction, a through hole is formed in the second end of the input shaft (22), the through hole is communicated with the cavity structure, the other end of the elastic torsion bar (23) is inserted into the cavity structure of the input shaft, and the first cylindrical pin (21) is inserted into the through hole, so that the relative rotation of the other end of the elastic torsion bar (23) and the input shaft (22) is locked; a first end of the input shaft abuts a needle bearing (24); the other end of the screw shaft (26) is provided with a steering nut, a plurality of steel ball injection holes are processed on the upper surface of the steering nut, and after steel balls are injected, a steel ball guide pipe (27) and a guide pipe pressing plate (28) for fixing the steel ball guide pipe (27) are arranged on the upper portion of the steering nut.

Preferably, the main body of the screw shaft (26) is of a multi-diameter cylindrical structure, one end of the main body is processed into a high-finish spiral groove along the outer surface, a reducing inner cavity is processed inwards along the axial direction at the end face of the other end of the main body, a square groove is formed in the end face, a through hole is processed in the vertical direction at the bottom of the reducing inner cavity, one end of an elastic torsion bar (23) is installed in the axial direction, a second cylindrical pin (25) is inserted into the through hole in the bottom of the reducing inner cavity, so that the screw shaft (26) is locked to coaxially rotate relative to the screw shaft, and then a needle bearing (24) is installed in.

Preferably, the needle bearing (24) is not in contact with the elastic torsion bar (23), and the practical effects of the needle bearing are that the gap between the input shaft (22) and the screw shaft (26) can be axially and mechanically limited, the elastic torsion bar (23) is prevented from being extruded by the change of the gap in the assembling and using processes, and the reliability of the elastic torsion bar (23) and the realizability of the input shaft and the screw assembly (2) can be effectively improved;

one end of the input shaft (22) is provided with a vertical through hole, an inner cavity is axially processed, a hexagonal boss is processed inwards along the end face, included angles between the inclined edge and the horizontal direction are +/-5 degrees respectively, and after the other end of the elastic torsion bar (23) extends into the through hole along the axial direction, the first cylindrical pin (21) is tightly matched with the through hole, so that the relative rotation between the other end of the elastic torsion bar (23) and the input shaft (22) is locked. Preferably, the hexagonal end face of the input shaft (22) is just abutted to the inner ring of the needle bearing (24), and the upper and lower 2 inclined planes of the hexagonal boss and the square groove of the screw shaft (26) form a relative rotation space of just +/-5 degrees, so that the practical effect is that the mechanical limit of the relative rotation of the input shaft (22) and the screw shaft (26) is formed, the over-twisting condition of the elastic torsion bar (23) in the assembling and using processes is effectively avoided, and the reliability of the screw shaft (26) is improved;

preferably, the first cylindrical pin and the second cylindrical pin are in interference fit with the through hole.

Install steering nut (29) along the axial from screw shaft (26) other end, its upper surface processing has many places steel ball filling hole, after the injection steel ball, installation steel ball pipe (27), its effect lies in guaranteeing when screw shaft (26) is rotatory, extrude by the helicla flute and turn to the inside steel ball of nut (29) and can get into another steel ball filling hole smoothly from a steel ball filling hole, return to inside steering nut (29) again, steel ball pipe (27) itself does not have fixing device, need to fix through pipe clamp plate (28), pipe clamp plate (28) fastening is behind steering nut (29) upper surface, steel ball pipe (27) have not only been fixed to its actual effect, can effectively decompose steel ball pipe (27) stress again. The upper surface of the steering nut 29 is provided with a plurality of steel ball injection holes, preferably 4 steel balls, and after the steel balls are injected, a steel ball guide pipe 27 and a guide pipe pressing plate 28 are installed to ensure that the steel balls can circularly roll in a closed channel formed by the screw shaft 26, the steering nut 29, the steel ball guide pipe 27 and the guide pipe pressing plate 28 when the screw shaft 26 rotates, the side surface of a sector of the sector shaft is provided with 3 involute conical teeth, and the involute conical teeth are meshed with the sector shaft 31 to convert the horizontal motion of the steering nut 29 into the rotation of the sector shaft 31; the end of the input shaft 22 connected with the screw shaft 26 is beveled to ensure that the input shaft 22 and the screw shaft 26 can rotate relatively within a small angle range.

As the preferred, the pipe clamp plate is integral dull and stereotyped structure among input shaft and the screw rod assembly, makes its can be by a large scale with the fitting of steering nut, has effectively decomposed the atress of steel ball, guarantees that the steel ball smoothly rolls, greatly reduced the steel ball when bearing huge external force, hardly pushed down or pushed up bad possibility, promoted the reliability of device.

4 steel ball injection holes are formed in the upper surface of the steering nut in the input shaft and screw assembly, and after the steel balls are injected, double-path steel ball circulation can be formed, so that the stress of spiral grooves in the inner surfaces of the decomposed steel balls and the steering nut is reduced, and the reliability of the steering nut and the circulating steel balls is effectively improved.

As shown in fig. 11, the sector shaft assembly (3) includes: a sector shaft (31), a sector shaft side cover plate (32), a sector shaft adjusting pin (33), a sector shaft adjusting nut (34), a sector shaft plug screw (35) and a needle bearing (36); the gear sector shaft (31) comprises a gear sector and a shaft, the gear sector is processed into a sector gear structure with involute bevel teeth, one end of the shaft is provided with an annular groove, a gear sector shaft adjusting pin is inserted into the gear sector shaft annular groove, the gear sector shaft is sleeved outside the gear sector shaft adjusting pin in a screw plug mode and has a certain interval with the gear sector shaft adjusting pin, one end of the shaft is provided with a gear sector shaft side cover plate, and a needle bearing (36) is arranged between the gear sector shaft side cover plate and the shaft; the side cover plate is spaced from one end of the shaft along the axial direction of the shaft, a through hole is formed in the side cover plate, the sector shaft adjusting pin (33) extends through the hole in the side cover plate from the annular groove, and the adjusting nut (34) is sleeved on the sector shaft adjusting pin (33) and is arranged and abutted against the outer portion of the sector shaft side cover plate (32).

The sector shaft 31 is of a sector gear structure, the sectors of the sector shaft are machined with a plurality of parts, preferably involute conical teeth, the sector shaft is meshed with conical teeth on the side surface of the steering nut 29, and small middle-position scribed lines are machined on the axial bottom end surface of the sector shaft, so that the sector shaft can rotate more conveniently for identification and measurement; an internal thread through hole is processed in the center of the top surface of the tooth sector shaft side cover plate 32, the purpose is to enable the top end of a tooth sector shaft adjusting pin 33 to penetrate through the tooth sector shaft side cover plate 32 to be connected with a tooth sector shaft adjusting nut 34, a through hole 4 is additionally processed in the top surface, and the purpose is to fix the tooth sector shaft assembly 3 on the upper end cover flange mounting surface L through bolt connection; the upper part of the sector shaft adjusting pin 33 is processed into an external thread structure so as to be convenient for connecting an adjusting nut, the bottom of the sector shaft adjusting pin is processed into a smooth and flat cylindrical structure, and an external thread is processed at the central position of the sector shaft adjusting pin and can be arranged at an internal thread hole at the center of an annular groove at the bottom of the sector shaft 31 and tightly press the upper surface of the smooth and flat cylindrical bottom through a sector shaft plug 35, so that the sector shaft 31 is axially connected; the sector shaft adjusting nut 34 is in threaded connection with the top end of the sector shaft adjusting pin 33 and is tightly attached to the top end of the sector shaft side cover plate 32, and the axial positions of the sector shaft adjusting pin 33 and the sector shaft 31 can be locked or fine-adjusted synchronously by rotating the sector shaft adjusting nut 34; the outer circle surface of the needle bearing 36 is tightly fitted with the inner circle surface at the bottom end of the cover plate 32 at the side of the sector gear shaft, and the inner circle surface is tightly fitted with the outer circle surface at the top end of the sector gear shaft 31, so as to ensure the coaxiality of the sector gear shaft 31, the cover plate 32 at the side of the sector gear shaft and the sector gear shaft adjusting pin 33 and reduce the rotation resistance of the sector gear shaft 31.

Preferably, the sector shaft further includes a rubber pad 37, the rubber pad 37 is disposed between an end surface in the groove and an end surface of the sector shaft adjusting pin 33, and the adjusting pin 33 presses the rubber pad 37.

Preferably, the diameter of the end of the adjusting pin 33 disposed in the groove is larger than the diameter of the adjusting pin 33 at other positions. Preferably, the diameter of the end portion is 1.6 to 2.2 times the diameter of the other portion. By increasing the diameter of the end portion, a large-area contact can be ensured, and the contact pressure can be increased.

Preferably, the needle bearings are arranged at other positions of the adjusting pin 33 and abut against the ends.

The surface of the output end a of the gear sector shaft is provided with a triangular spline for realizing spline connection with a steering mechanism, and the surface of the output end b is provided with a fine middle-position scale line for finishing centering of the assembly of the steering mechanism; the annular groove is a step hole, and the hole at the bottommost part is used for sequentially placing a rubber pad and the large end face of the gear sector shaft adjusting pin.

The surface roughness of the triangular spline on the surface A of the output end of the gear sector shaft (2) is 1.6.

A rubber pad (3) is additionally arranged in the gear sector shaft assembly, and when a gap is formed between the gear sector of the gear sector shaft and the steering nut rack in a matching mode, automatic compensation can be achieved within a certain range.

4 through holes are processed on the side cover plate (7) of the gear sector shaft and are used for connecting the side cover plate with a main shell of an electric steering gear, and the integrity and the air tightness of the electric recirculating ball steering gear are guaranteed.

Preferably, the surface of the gear sector shaft is carburized (0.8-1.2) mm, and the hardness is required to be (58-62) HRC, so that the performance of the material is exerted to the maximum extent, and the strength of the knuckle arm is improved.

The side cover plate of the gear sector shaft and the shell are connected in a 4-point connection mode, so that the assembly strength of the gear sector shaft assembly, the integrity of the device and the air tightness are guaranteed.

Preferably, through adding the rubber pad, when the meshing position of the gear surface of the gear sector shaft and the gear surface of the steering nut is in long-term and heavy-load use, a gap appears, and the flexible automatic compensation can be realized within a certain range.

Installing a rubber pad at the bottom end of an inner hole at the side cover end of the sector shaft, sequentially installing the sector shaft adjusting pins, enabling the large end face of the sector shaft adjusting pin to be attached to the rubber pad, screwing a sector shaft plug screw into the threaded position of the inner hole of the sector shaft, pressing the large end face of the sector shaft adjusting pin and the rubber pad tightly, ensuring that the compression amount of the rubber pad is 2mm, screwing the sector shaft plug screw in place, riveting and installing, pressing the sector shaft plug screw, preferably pressing an annular boss of the sector shaft plug screw, screwing a needle bearing pressed into a side cover sector shaft adjusting pin through a central threaded hole of the sector shaft side cover plate, enabling the sector shaft adjusting pin to be screwed and penetrate through the sector shaft side cover plate, and realizing axial locking and unlocking of the positions of the sector shaft, the sector shaft adjusting pin and the sector shaft plug screw by adjusting a sector shaft adjusting nut.

The adjustment working principle of the invention is as follows:

the clearance between the rack on the steering nut and the sector on the sector shaft is ensured by adjusting the sector shaft adjusting pin. After the clearance is adjusted, the gear sector shaft adjusting pin, the gear sector shaft side cover plate and the gear sector shaft adjusting nut are fixed together, and the gear sector shaft screw plug and the gear sector shaft are fixed together. After the steering engine is used for a period of time, the rack on the steering nut and the sector on the sector shaft are abraded, the fit clearance is increased, the step surface of the head of the sector shaft adjusting pin and the right end surface of the sector shaft plug screw can be abraded to a certain degree, the compressed rubber pad automatically enables the sector shaft to move leftwards, the fit clearance between the sector shaft and the rack is automatically compensated, and the compensated movement amount is the abrasion amount of the surface of the sector shaft plug screw.

As shown in fig. 12, the support seat assembly 4 includes: a support base 41 and a one-way thrust angular contact bearing 42; the supporting seat 41 is a through annular structure with variable inner diameter, external threads are machined on the outer circumference of the supporting seat, and the one-way thrust angular contact bearing 42 is installed inside the supporting seat 41 in a tight fit manner; after the support seat assembly 4 axially sleeves the input shaft and the screw rod assembly 2, the input shaft and the screw rod assembly 2 are mounted and limited by fastening the outer threads of the support seat assembly on the first inner thread surface D of the shell assembly 1.

As shown in fig. 13, the inner diameter circular surface of the turbine 5 is provided with a key groove, which is used for being axially mounted on the input shaft and the screw assembly 2 shaft in a flat key connection manner, and the surface is provided with 6 notches, so that the weight is reduced, the rotational inertia is reduced, and the turbine 5 and the input shaft and the screw assembly 2 are coaxially rotatable.

The inner diameter circular surface of the turbine 5 is provided with a key groove 61, and the surface of the inner diameter circular surface of the turbine 5 is provided with a notch 62, so that the weight of the turbine can be effectively reduced, the rotational inertia can be reduced, and the turbine 5, the input shaft and the screw assembly 2 can coaxially rotate; it is emphasized that 2 internal thread adjusting holes 63 are processed on the end face of the worm wheel 5, and the practical effect is that only by using special tools or tools at the internal thread adjusting holes 63, the position degree and the meshing condition of the worm wheel 5 and the worm 6 can be accurately positioned or finely adjusted in the assembling process, so that the realizability and the adjustability of the transmission chain are ensured.

As shown in fig. 14, the upper end of the screw rod 6 is processed with an external spline, the lower end is a smooth cylindrical surface inner diameter circular surface, the lower end is axially installed in the screw rod cavity and is tightly fitted with the inner circular surface of the angular contact bearing 17, and the upper part is sleeved with a hollow locking plug screw processed with an external thread and fastened on the second inner thread surface K.

As shown in fig. 15, the diverter inner end cover assembly 7 includes: an inner end cover 71, a framework oil seal 72, a corner torque sensor positioning plate 73 and a sensor fixing rubber block 74; the inner surface of the inner end cover 71 is provided with a threaded blind hole for mounting the corner torque sensor positioning plate 73 and the corner torque sensor 8, and is axially processed into a reducing through hole; the framework oil seal is arranged in the reducing through hole of the inner end cover 71, the outer circular surface of the framework oil seal is tightly matched with the inner circular surface of the large end of the reducing through hole of the inner end cover 71 and is limited on the reducing end surface, and the framework oil seal has the function of preventing lubricating oil in the shell assembly 1 from leaking and damaging the corner torque sensor 8; the positioning plate 73 of the corner torque sensor is fixed on the threaded blind hole on the inner surface of the inner end cover 71 in a bolt connection mode, and has the function of avoiding the outer ring of the corner torque sensor 8 from deviating along the axial angle; the sensor fixing rubber block 74 functions to fix the sensor outlet terminal and prevent foreign matter from entering the inside of the steering gear.

As shown in fig. 16, the outer end cover assembly 9 includes an outer end cover 91, a dust ring 92, a deep groove ball bearing 93; the outer end cover 91 is provided with a through hole on the outer surface, the outer end cover is used for being fixed on an outer end cover flange mounting surface N in a bolt connection mode, the inner surface of the outer end cover is outwards processed into a reducing through structure along the axial direction, an inner circular surface I and a circular groove II are sequentially processed, and a deep groove ball bearing 93 is installed in the inner circular surface I, so that the purpose of ensuring smooth rotation of an input shaft 22 is achieved, and after an outer end cover assembly 9 is installed on a shell 1A, the coaxiality of the input shaft and a screw assembly 2 with a primary transmission cavity E and a secondary transmission cavity C can be ensured; the dust ring 92 is an irregular rubber sealing ring, the section of the dust ring is an irregular plane formed by a rectangle and a triangle, the main body of the dust ring is a rectangular section rubber sealing ring, the minimum diameter of the sealing ring with the obtuse-angle triangular section at the outer side is smaller than the inner diameter of the part with the rectangular section, and the part with the rectangular section is arranged in the circular groove II.

The two ends of the plum blossom-shaped connecting sleeve assembly 10 are processed into an inner spline structure, an inner spline at one end of the plum blossom-shaped connecting sleeve assembly is connected with an outer spline end of the worm 6, and an output spline shaft of the motor assembly 11 is connected at one end of the plum blossom-shaped connecting sleeve assembly, so that the motor assembly 11 is flexibly connected with the worm 6.

The motor assembly 11 is a 24V direct-current permanent magnet synchronous motor, the rated power is 1.6kW, the rated torque is 7N/M, the rated rotating speed is 2200rpm, a Hall position sensor is integrated, a square internal thread mounting flange is used as a power source of the device, and the device is fixed on a motor flange mounting surface M in a bolt connection mode after the axial mounting of the plum blossom connecting sleeve assembly 10 and the worm 6 is completed.

The heavy recirculating ball type dual-mode electric power steering device is structurally different from a recirculating ball type hydraulic power steering gear in that the heavy recirculating ball type dual-mode electric power steering device adopts a worm and gear structure and a corner torque sensor structure to replace a hydraulic rotary valve structure of the recirculating ball type hydraulic power steering gear; a direct current motor is used as a power-assisted power source to replace a hydraulic steering pump power source; the heavy-duty circulating ball type dual-mode electric power steering device is compact in overall structure and higher in integration level, greatly reduces the number of parts of a power steering system, and achieves the purpose of actively controlling steering power.

As shown in fig. 1 to 16, the working principle of the heavy recirculating ball type dual-mode electric power steering apparatus according to the present invention is characterized as follows:

a power-assisted manual mode

When the input shaft 22 is rotated forward or backward by the steering wheel, because the input shaft 22 and the screw shaft 26 are connected through the elastic torsion bar 23 and have a certain angle, preferably an angular displacement idle stroke of ± 10 degrees, the screw shaft 26 and the input shaft 22 can rotate coaxially with the input shaft 22 when reaching the angular displacement idle stroke limit, the angular torque sensor 8 is axially connected with the input shaft 22 and the screw shaft 26, the control system calculates the target torque of the motor assembly 11 by collecting the output torque value of the angular torque sensor 8, drives the motor assembly 11 to output an assisting torque in a torque control mode, the motor assembly 11 transmits the torque to the worm 6 through the quincunx connection sleeve assembly 10, applies the torque to the screw shaft 26 and drives the screw shaft 26 to rotate after decelerating and increasing the torque through the worm wheel 5, at this time, the steel balls in the input shaft and the screw assembly 2 can roll in the steering nut 29 along with the screw lead of the screw shaft 26, the steering nut 29 guides the rolling steel ball into the steel ball guide pipe 27 through an opening on the upper surface, and the steel ball is guided by the steel ball guide pipe 27 and returns to the interior of the steering nut 29 again; the steel ball circularly rolling in the steering nut 29 provides horizontal lateral thrust to push the steering nut 29 to move horizontally, and the steering nut 29 is meshed with the sector gear shaft 31, so that the sector gear shaft assembly 3 converts the thrust and the linear motion stroke of the steering nut 29 into torque and angular displacement for output.

When the input shaft 22 stops rotating through the steering wheel, the elastic torsion bar 23 between the input shaft 22 and the screw shaft 26 overcomes the angular displacement stroke between the input shaft 22 and the screw shaft 26 to generate elastic deformation during the rotation process, and the elastic deformation is recovered under the condition that no external force is applied to the input shaft 22, namely, the input shaft 22 rotates to the middle position of the steering wheel.

In a control system, an intelligent power-assisted characteristic function and a steering active safety characteristic function are innovatively introduced, specifically, the intelligent power-assisted function is a transient target torque value of a steering resistance motor which is calculated according to the vehicle speed condition and the steering wheel rotation angle condition in a transient time domain range, and a basic method is as follows:

wherein:

electric machine assembly (target) torque T_m(t)(N · M) is a system calculation output value, which is an output value within a unit time, more preferably within 50 ms;

minimum driver hand force F_min(N) is a system design set value, preferably 20N;

maximum driver hand force F_max(N) is a system design set value, preferably 50N;

electric steering gear primary transmission ratio i_m(constant) is a system set value, namely the transmission ratio of the worm wheel to the worm is preferably 25-35, and further preferably 30;

electric steering gear secondary transmission ratio i_n(constant) is a system set value, namely a transmission ratio of the screw shaft to the sector shaft, preferably 21-31, and more preferably 26.13;

positive efficiency η of diverter_m(0-1) is a system set value, preferably 0.6;

steering wheel angle theta_sw(t)(rad) is the collection value of the sensor, the unit time, the preferred steering wheel rotation angle within 50ms, the bestSelecting the range from-15.7 to 15.7; here, the unit time and the motor assembly (target) torque T_m(t)The unit time of (N.M) is the same;

steering linkage angle transmission ratio i_sThe optimal range is 1-1.2 for the system setting value;

pivot steering drag torque T_w(N.M) is a system set value, and the preferred range is 2000-4000;

vehicle speed v_(t)(km/h) is a sensor acquisition value, and the preferred range is 0-120;

outer wheel corner theta of front axle₀'_(t)(rad), preferably in the range of-0.54 to 0.54;

maximum steering angle theta of wheel₀(rad) is the design input value, preferably 0.61 absolute;

steering wheel radius R₀(m) is a system set value, preferably 0.21.

In addition, the main characteristic of the steering active safety characteristic function is that according to the state information (such as vehicle speed, steering radius, road surface inclination angle and the like) and the vehicle structure characteristics (such as wheel track, wheel base, weight and the like) when the vehicle runs, under different running speeds, the maximum angle α allowed by the steering wheel under the critical state that the vehicle is supposed to be in the side turning or sideslip state is dynamically pre-judged and analyzed₀(ii) a When a driver operates the vehicle to exceed the maximum angle time, the system reversely and rapidly increases the steering resistance of the driving motor and prevents the steering wheel from rotating, thereby effectively avoiding the situation that the driver operates the vehicle to turn over or sideslip, greatly improving the driving safety, and the basic method is as follows:

wherein:

maximum safe steering angle α₀(°) is the system calculated output value;

the wheel track B (mm) is a system set value, and the preferred range is 800-1500;

the wheelbase L (mm) is a system set value, and the preferred range is 2000-3500;

the rotating arm a (mm) of the wheel is a system set value, and the preferred range is 40-100;

height h of vehicle mass center_g(mm) is a system set value, and the preferred value is 400-1500;

vehicle speed v_(t)(km/h) is an acquisition value of a driver, and the preferable range is 0-120;

road side rake angle (centroid side rake angle) β_kThe degree is the inclination angle of the road surface relative to the horizontal plane and is a value collected by a driver, and the preferred range is-30 degrees to 30 degrees;

g is the acceleration of gravity, 9.8 m/s squared.

Two-wire control unmanned mode

The control system calculates the absolute target position of the motor assembly 11 needing to move by calculating the current rotation angle value of the rotation angle torque sensor 8 and the received target rotation angle value, and drives the motor assembly 11 to rotate to the absolute target position in a position control mode; the motor assembly 11 drives the worm 6 and the worm wheel 5 to rotate through the plum blossom-shaped connecting sleeve assembly 10; preferably, the reduction ratio between the worm 6 and the worm wheel 5 is 30. Because the worm wheel 5 and the screw shaft 26 rotate coaxially, namely the rotating angular speed and the rotating angle are the same, at the moment, the steel balls in the input shaft and the screw assembly 2 roll in the steering nut 29 along with the screw lead of the screw shaft 26, the steering nut 29 guides the rolling steel balls into the steel ball guide pipe 27 through the upper surface opening, and the steel balls are guided by the steel ball guide pipe 27 and then return to the interior of the steering nut 29 again; the steel ball circularly rolling in the steering nut 29 provides horizontal lateral thrust to push the steering nut 29 to move horizontally, and the steering nut 29 is meshed with the sector gear shaft 31, so that the sector gear shaft assembly 3 converts the thrust and the linear motion stroke of the steering nut 29 into torque and angular displacement for output.

In the control system, a wheel target steering angle algorithm based on dynamic intervention of a vehicle yaw angle is innovatively proposed, and specifically: firstly, the functional relation between the target steering wheel angle and the target wheel deflection angle is solved through parameters such as the steering wheel angle, the secondary transmission ratio of the electric steering device, the angle transmission ratio of a steering rod system and the like, namely:

secondly, in the running and steering process of the vehicle, due to the dynamic characteristics of the vehicle, more or less vehicle body yaw phenomena can be generated under the conditions of different vehicle speeds and different steering wheel angles, and the vehicle generates an overlarge yaw angle which can possibly cause the vehicle to sideslip or turn over, so that the control system estimates the transmission relationship between the vehicle yaw angle and the steering wheel angle under the conditions of different vehicle speeds in a frequency domain, and sets a vehicle yaw angle threshold value omega_r(S) the steering wheel rotation angle threshold value theta under different vehicle speeds can be obtained_p(S), therefore, when the vehicle yaw angle threshold value appears at a certain vehicle speed, the theta is compared_p(S) and θ_pWhen the steering wheel angle threshold value theta_p(S) target steering angle theta_pWhen the ratio of (A) to (B) is less than 1, the system will automatically use the steering wheel angle threshold value theta_p(S) replacement of the target steering wheel Angle θ_p(ii) a Steering wheel angle threshold theta_p(S) target steering angle theta_pWhen the ratio of (A) is greater than or equal to 1, the target steering wheel angle theta is maintained_pAnd therefore, dynamic intervention on the target turning angle of the wheel is realized. In which theta is obtained by the following formula_p(S)：

Wherein:

the parameters in the above formulas are as follows:

although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A manual power-assisted method for an electric power steering device is characterized in that when an input shaft is rotated forwards or reversely through a steering wheel, the input shaft and a screw shaft are connected through an elastic torsion bar and form a certain angle, so that the screw shaft can rotate coaxially with the input shaft when the screw shaft and the input shaft reach an angular displacement idle stroke limit, a corner torque sensor is axially connected with the input shaft and the screw shaft, a control system calculates a target torque of a motor assembly by acquiring an output torque value of the corner torque sensor, the motor assembly is driven to output a power-assisted torque in a torque control mode, the motor assembly transmits the torque to a worm through a quincunx connection sleeve assembly, the torque is applied to the screw shaft and drives the screw shaft to rotate after speed reduction and torque increase through a worm gear, at the moment, steel balls in the input shaft and the screw assembly roll in a steering nut along with a screw lead of the screw shaft, the steering nut guides the rolling steel ball into the steel ball guide pipe through the opening on the upper surface, and the steel ball is guided by the steel ball guide pipe and returns to the interior of the steering nut again; the steel ball circularly rolling in the steering nut provides horizontal lateral thrust to push the steering nut to move horizontally, and the gear sector shaft assembly converts the thrust and linear motion stroke of the steering nut into torque and angular displacement for output as the steering nut is meshed with the gear sector shaft;

the system dynamically pre-judges and analyzes the maximum angle α allowed by the steering wheel under the condition that the vehicle is supposed to be in the critical state of side turning or sideslip according to the state information and the structural characteristics of the vehicle when the vehicle runs and under different running speeds₀(ii) a When the driver operates the vehicle for more than the maximum angle time, the system reversely and rapidly increases the steering resistance of the driving motor and prevents the steering wheel from rotating, thereby effectively avoiding the situation of side turning or sideslip when the driver operates the vehicle;

determining the maximum angle α₀The formula of (1) is as follows:

wherein:

maximum angle α₀The unit is DEG, calculating an output value for the system;

the unit of the wheel base B is mm, the wheel base B is a system set value and ranges from 800 to 1500;

the unit of the wheelbase L is mm, the wheelbase L is a system set value and ranges from 2000 to 3500;

the unit of the wheel rotating arm a is mm, the wheel rotating arm a is a system set value and is in the range of 40-100;

height h of vehicle mass center_gThe unit is mm, and the unit is a system set value and is in the range of 400-1500;

vehicle speed v_(t)The unit is km/h, which is an acquisition value of a driver and ranges from 0 to 120;

road side inclination angle β_kThe unit is an inclination angle of the road surface relative to the horizontal plane, and is a value acquired by a driver, and the range is-30 degrees to 30 degrees;

electric steering gear secondary transmission ratio i_nIs constant and is a system set value, namely the transmission ratio of the screw shaft to the gear sector shaft is 21-31;

g is the acceleration of gravity, 9.8 m/s squared.

2. A power assisted manual method according to claim 1 wherein the input shaft stops rotating by the steering wheel and is resiliently deformed by the resilient torsion bar between the input shaft and the screw shaft during rotation against the angular displacement travel between the input shaft and the screw shaft and returns to the neutral position of the steering wheel in the absence of external force.

3. A power assisted manual method according to claim 1 wherein there is an angular lost motion of ± 10 degrees between the input shaft and the screw shaft.

4. A manual power-assisted method for an electric power steering device is characterized in that when an input shaft is rotated forwards or reversely through a steering wheel, the input shaft and a screw shaft are connected through an elastic torsion bar and form a certain angle, so that the screw shaft can rotate coaxially with the input shaft when the screw shaft and the input shaft reach an angular displacement idle stroke limit, a corner torque sensor is axially connected with the input shaft and the screw shaft, a control system calculates a target torque of a motor assembly by acquiring an output torque value of the corner torque sensor, the motor assembly is driven to output a power-assisted torque in a torque control mode, the motor assembly transmits the torque to a worm through a quincunx connection sleeve assembly, the torque is applied to the screw shaft and drives the screw shaft to rotate after speed reduction and torque increase through a worm gear, at the moment, steel balls in the input shaft and the screw assembly roll in a steering nut along with a screw lead of the screw shaft, the steering nut guides the rolling steel ball into the steel ball guide pipe through the opening on the upper surface, and the steel ball is guided by the steel ball guide pipe and returns to the interior of the steering nut again; the steel ball circularly rolling in the steering nut provides horizontal lateral thrust to push the steering nut to move horizontally, and the gear sector shaft assembly converts the thrust and linear motion stroke of the steering nut into torque and angular displacement for output as the steering nut is meshed with the gear sector shaft; the target torque calculation formula of the motor assembly is as follows:

wherein the target torque T of the motor assembly_m(t)The unit is N.M, and an output value is calculated for the system;

electric steering gear primary transmission ratio i_mIs a constant which is a system set value, namely the transmission ratio of the worm wheel and the worm;

electric steering gear secondary transmission ratio i_nIs a constant which is a system set value and is the transmission ratio of the worm shaft and the gear sector shaft;

positive efficiency η of diverter_mTaking the value of 0-1 as a system set value;

steering wheel angle theta_sw(t)The unit is rad, which is a sensor acquisition value and a steering wheel rotation angle in unit time;

pivot steering drag torque T_wThe unit is N.M, which is a system set value;

vehicle speed v_(t)The unit is km/h which is a sensor acquisition value;

outer wheel corner theta' of front axle_0(t)Unit is rad;

i_sthe angle transmission ratio and the constant of the steering rod system are set values of the system;

maximum steering angle theta of wheel₀In units of rad, as design input values；

Steering wheel radius R₀The unit is m, which is the system set value.