CN109278849B - Inner end cover assembly of steering gear and steering gear thereof - Google Patents

Inner end cover assembly of steering gear and steering gear thereof Download PDF

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Publication number
CN109278849B
CN109278849B CN201810807626.1A CN201810807626A CN109278849B CN 109278849 B CN109278849 B CN 109278849B CN 201810807626 A CN201810807626 A CN 201810807626A CN 109278849 B CN109278849 B CN 109278849B
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assembly
input shaft
shaft
steering
screw
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CN109278849A (en
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张勇
李玉
王成玲
刘富强
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China North Vehicle Research Institute
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China North Vehicle Research Institute
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0445—Screw drives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0454—Worm gears
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D3/00—Steering gears
    • B62D3/02—Steering gears mechanical
    • B62D3/04—Steering gears mechanical of worm type
    • B62D3/06—Steering gears mechanical of worm type with screw and nut
    • B62D3/08—Steering gears mechanical of worm type with screw and nut using intermediate balls or the like

Abstract

The invention provides an inner end cover assembly of an electric power steering device and a steering device thereof, wherein the inner end cover 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. The invention provides an inner end cover assembly and a steering device thereof, which adopt a large reduction ratio mechanism, a corner torque sensor and the like to replace a rotary valve structure in a recirculating ball type hydraulic power steering gear, realize the conversion from hydraulic transmission to intelligent electric transmission under the condition of not increasing extra space, and compared with the recirculating ball type hydraulic power steering gear with the same volume, the power requirement is reduced by 300 percent, and the maximum output torque is improved by 5 percent.

Description

Inner end cover assembly of steering gear and steering gear thereof
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.
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 addition, for the recirculating ball type electric steering gear with torque-assisted and angular position dual control modes, the angular position control mode is generally applied to a steer-by-wire mode or an unmanned remote steering mode, and is a control mode of a closed loop depending on the rotation angle of an input shaft of the steering gear. In such a steer-by-wire mode, the application range of the recirculating ball type electric steering gear is greatly improved, and the recirculating ball type electric steering gear is not limited to be used in a front steering axle or a first steering axle, and can be used as a steering actuating mechanism of other steering axles or steering wheels in a multi-wheel/all-wheel steering system, but when the recirculating ball type electric steering gear is applied in such a steering system, the problems of maintaining the middle position of a non-full-time steering axle or steering wheels in the multi-wheel/all-wheel steering system and ensuring the middle position mechanical locking of the wheels when a motor or a control system fails exist necessarily exist, and the problems are key problems directly influencing the running safety of a vehicle. Therefore, it is necessary for a recirculating ball electric steering gear with dual control modes to be able to achieve a purely mechanical locking of the input shaft.
In view of the above problems, the present invention provides a new locking device and a steering device thereof, thereby solving various problems encountered in the steering of a heavy vehicle.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: how to provide a heavy recirculating ball type dual-mode electric power locking device and a steering device thereof.
In order to achieve the purpose, the technical scheme of the invention is as follows:
an inner end cap assembly of an electric power steering apparatus, the inner end cap assembly comprising: 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.
An electric power steering apparatus comprising: the motor comprises a shell assembly, an input shaft and screw assembly, a gear sector shaft assembly, a supporting seat assembly, a worm wheel, a worm, an inner end cover assembly, a corner torque sensor, a plum blossom-shaped 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 arranged outside the worm wheel, the corner torque sensor is connected with the axial direction and the input shaft and the screw rod assembly, and the input shaft locking device is sleeved on the input shaft and the screw rod assembly, is arranged outside the corner torque sensor and is fixed at the front end of the shell assembly.
Preferably, the input shaft locking device comprises an end cover, a locking cover and a locking sleeve, the locking cover is connected to the first end of the end cover through a connecting device, a through hole for the input shaft to be inserted is formed between the end cover and the locking cover, the locking sleeve is sleeved on the input shaft and is installed in the through hole of the locking cover, and the locking cover is sleeved on the locking sleeve in the through hole of the locking cover.
Preferably, the end cover is connected to the steering gear housing, and a sealing gasket is arranged between the end cover and the steering gear housing.
Preferably, the second end is provided with an extension extending outwards along the central position of the locking device, and the extension is provided with a through hole.
Preferably, a second end of the end cap opposite the first end is provided with an annular boss forming an annular cavity at the second end.
Preferably, 3 through holes are uniformly processed along the circumference of the central position of the locking device.
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 input shaft and one end of the screw rod assembly are arranged in the first inner circular surface B, the supporting seat assembly is arranged in the first inner threaded surface D, the worm wheel is arranged in the primary transmission cavity E, the inner end cover assembly is press-mounted on the second inner circular surface F of the shell assembly, and the inner end cover assembly is limited on a circular boss formed between the second inner circular surface F and the primary 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.
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. 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.
2. 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.
3. 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.
4. 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.
The invention provides a heavy circulating ball type dual-mode electric power steering device, which has the structural characteristics completely different from the forms of a rack-and-pinion type, a steering column type and the like of a small passenger car, effectively solves the problems of integral output torque and system structure, uses a large reduction ratio mechanism, a corner torque sensor and the like to replace a rotary valve structure in a circulating ball type hydraulic power steering gear by taking the reference of the structure of the circulating ball type hydraulic power steering gear, realizes the conversion from hydraulic transmission to intelligent electric transmission under the condition of not increasing extra space, and has the power requirement reduced by 300 percent and the maximum output torque improved by 5 percent compared with the circulating ball type hydraulic power steering gear with the same volume.
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 worm gear 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 front view of an input shaft locking arrangement of the recirculating ball-type electric steering gear;
FIG. 18 is a top view of an input shaft locking arrangement for a recirculating ball-type electric steering gear;
fig. 19 is a left side view of an input shaft locking device of the recirculating ball-type electric steering gear.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
Herein, if not specifically stated, "/" denotes division, "×", "x" denotes multiplication, referring to formulas.
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, characterized in that it comprises: 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 worm wheel 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;
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 a 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 rod assembly 2 and is installed outside the worm wheel 5, the corner torque sensor 8 is connected with the input shaft and screw rod assembly 2 in the axial direction, and the outer end cover assembly 9 is sleeved on the input shaft and screw rod assembly 2, is installed outside the corner torque sensor 8 and is fixed at the front end of the shell assembly 1.
The non-through cavity is a cavity with one open end and one closed end.
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 worm and gear structure with large reduction ratio, 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 screw assembly 2 is axially arranged in a shell assembly 1 and is axially limited and fixed through a support seat assembly 4, the support seat assembly 4 is arranged on a first inner thread surface D of the shell assembly 1, preferably in a screwing mode, a worm wheel 5 is axially arranged on the input shaft and screw assembly 2 in a primary transmission cavity E in a flat key connection mode, an inner end cover assembly 7 is pressed on a second inner circle surface F of the shell assembly 1 in a tight fit mode and is limited on a circular boss formed between the second inner circle surface F and the primary transmission cavity E, a corner torque sensor 8 is fixed on the outer side of the inner end cover assembly 7 through screws and is coaxial with the input shaft and the screw assembly 2, an outer end cover assembly 9 is connected through bolts and 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, a sector shaft assembly 3 is vertically arranged in the secondary transmission cavity C, a sector is meshed with a steering nut in the input shaft and screw assembly 2, is connected and fixed on an upper end cover flange L of the shell assembly 1 through bolts, the worm wheel assembly I in an axial direction, is meshed with a worm wheel assembly 6, the worm wheel assembly, the worm shaft assembly is connected with a motor output torque output shaft through a plum blossom shaft, and a motor output shaft, and is connected with a motor output torque output screw assembly through a motor output screw assembly 10, and a motor output screw assembly, the motor output screw assembly through a screw assembly, and a screw assembly, the motor output screw.
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
Figure GDA0002374613370000061
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 QT450-10 GB1348-2009 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, a sector of the sector shaft is provided with a plurality of parts, preferably involute conical teeth, the involute conical teeth are meshed with conical teeth on the side face of a steering nut 29, a small middle groove is machined on the axial bottom end face of the sector shaft, the sector shaft adjusting pin 33 is fixed at the bottom of an annular groove through a sector shaft plug 35 riveted on an inner circular face, an internal thread through hole is machined in the center of the top face of the sector shaft side cover plate 32, the internal thread through hole is machined in the center of the top face of the sector shaft adjusting pin 33, the top end of the sector shaft adjusting pin 33 can penetrate through the sector shaft side cover plate 32 to be connected with the sector shaft adjusting nut 34, a through hole 4 is additionally machined in the top face, the sector shaft assembly is fixed at an upper end cover flange L through a bolt connection, the upper portion of the sector shaft adjusting pin 33 is machined into an external thread structure, the sector shaft adjusting nut is convenient to connect with the sector shaft adjusting nut, the bottom is machined into a smooth and flat structure, the center of the sector shaft adjusting pin is machined in the center of the sector shaft adjusting pin, the sector shaft adjusting pin 31 can be tightly connected with the top end of the cylindrical sector shaft 31 through the sector shaft, the cylindrical sector shaft 31 and the cylindrical sector shaft, the cylindrical sector shaft is tightly connected with the cylindrical sector shaft through the sector shaft, the cylindrical sector shaft.
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 an annular boss of the sector shaft plug screw, preferably compressing the annular boss of the sector shaft plug screw, screwing a side cover pressed into a needle bearing into the 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 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 worm wheel 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 worm wheel 5 and the input shaft and the screw assembly 2 are coaxially rotatable.
The inner diameter circular surface of the worm wheel 5 is provided with a key groove 61, and the surface of the inner diameter circular surface of the worm wheel 5 is provided with a notch 62, so that the actual effects of effectively reducing the weight of the worm wheel and reducing the rotational inertia are achieved, and the worm wheel 5, the input shaft and the screw assembly 2 are coaxially arranged to 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 in the assembling process, 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, 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.
Preferably, the steering device further comprises an input shaft locking device. As shown in fig. 17 to 19, the locking device for the input shaft of the electric power steering apparatus includes an end cap 103, a locking cap 104, and a locking sleeve 105, wherein the locking cap 104 is connected to a first end of the end cap 103 through a connecting device, a through hole for inserting the input shaft is provided between the end cap 103 and the locking cap 104, the locking sleeve 105 is sleeved on the input shaft and installed in the through hole of the locking cap 104, and the locking cap 104 is sleeved on the locking sleeve 105 in the through hole of the locking cap 104.
Preferably, the end cover is connected to the steering gear housing, and a sealing gasket is arranged between the end cover and the steering gear housing.
Preferably, the end cap is the aforementioned outer end cap assembly, and the structure of the aforementioned outer end cap assembly can be adopted. It is therefore practical to employ the input shaft locking device directly in place of the front outer end cap assembly.
Preferably, the second end is provided with an extension extending outwards along the central position of the locking device, and the extension is provided with a through hole. The through hole may be provided with a fixing means, such as a nut.
Preferably, a second end of the end cap 103 opposite the first end is provided with an annular boss forming an annular cavity at the second end.
Preferably, 3 through holes are uniformly processed along the circumference of the central position of the locking device.
Preferably, a through hole is provided in a direction perpendicular to the axis of the locking cover through hole, the through hole communicating with the locking cover through hole.
The invention provides a locking device for an input shaft of a recirculating ball type electric steering gear, which comprises a locking sleeve 105, a locking cover 104, a locking cover bolt 107, a locking screw 108 and the like. The locking sleeve 105 is an internal spline and has certain elasticity, and an opening is provided with a unthreaded hole. The locking sleeve 105 is fitted over the steering input shaft 101, i.e. the front input shaft 22. Connected with the input shaft through a spline, and the outer circular surface is arranged in the locking cover 104. The locking cover is a quincunx flange, the shape of the locking cover is matched with the shape of the steering gear end cover 103 according to the number of the extending claws, the middle part of the locking cover 104 is provided with a threaded hole, and the extending claws are provided with unthreaded holes for installing locking cover bolts 107.
The end cover 103 is fixed on the steering gear shell through an end cover bolt 106, and a sealing gasket 102 is arranged between the end cover 103 and the shell. The locking process is as follows: the input shaft 101 is rotated to a proper position (the scale marks on the input shaft are aligned with the scale marks on the end cover), the locking sleeve 105 is sleeved on the input shaft 101, the locking cover 104 is sleeved on the locking sleeve 105 and is fixed on the end cover 103 through the locking cover bolt 107, the locking screw 108 is screwed into the threaded hole in the middle of the locking cover 104, the locking screw 108 is fastened, and the locking sleeve 105 deforms to lock the input shaft.
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:
Figure GDA0002374613370000131
Figure GDA0002374613370000132
wherein:
electric machine assembly (target) torque Tm(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 Fmin(N) is a system design set value, preferably 20N;
maximum driver hand force Fmax(N) is a system design set value, preferably 50N;
electric steering gear primary transmission ratio im(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 in(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 diverterm(0-1) is a system set value, preferably 0.6;
steering wheel angle thetasw(t)(rad) is the value acquired by the sensor, the unit time is preferably the rotation angle of the steering wheel within 50ms, and the optimization is carried outThe range is-15.7 to 15.7; here, the unit time and the motor assembly (target) torque Tm(t)The unit time of (N.M) is the same;
steering linkage angle transmission ratio isThe optimal range is 1-1.2 for the system setting value;
pivot steering drag torque Tw(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 of front axle
Figure GDA0002374613370000141
The preferable range is-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:
Figure GDA0002374613370000151
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 centerg(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) βkThe 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;
electric steering gear secondary transmission ratio in(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;
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:
Figure GDA0002374613370000161
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 omegar(S) the steering wheel rotation angle threshold value theta under different vehicle speeds can be obtainedp(S), therefore, when the vehicle yaw angle threshold value appears at a certain vehicle speed, the theta is comparedp(S) and θpWhen the steering wheel angle threshold value thetap(S) target steering angle thetapWhen the ratio of (A) to (B) is less than 1, the system will automatically use the steering wheel angle threshold value thetap(S) replacement of the target steering wheel Angle θp(ii) a Steering wheel angle threshold thetap(S) target steering angle thetapWhen the ratio of (A) is greater than or equal to 1, the target steering wheel angle theta is maintainedpAnd therefore, dynamic intervention on the target turning angle of the wheel is realized. In which theta is obtained by the following formulap(S)：
Figure GDA0002374613370000162
Figure GDA0002374613370000163
Wherein:
Figure GDA0002374613370000171
Figure GDA0002374613370000172
Figure GDA0002374613370000173
Figure GDA0002374613370000174
Figure GDA0002374613370000175
Figure GDA0002374613370000176
the parameters in the above formulas are as follows:
Figure GDA0002374613370000177
Figure GDA0002374613370000181
it should be noted that the heavy recirculating ball type dual mode electric power steering apparatus of the present invention can be easily understood by those skilled in the art to be applied to different types of wheeled vehicle steering systems, manned and unmanned, in the above-mentioned manner, and that various modifications and changes in form can be made thereto without departing from the spirit and scope of the present invention as defined by the appended claims.
The device adopts direct current 24 +/-4 VDC for power supply, the total rated power is 1.6kW, the maximum output torque is 4000 N.m, the maximum angular speed of the gear sector shaft is 18 degrees per second, the maximum stroke of the gear sector shaft is +/-37 degrees, the maximum stroke of the input shaft is-720 degrees to 720 degrees, and the device is provided with a double CAN communication interface, and has the functions of position, power-assisted double working modes and active return.
The communication protocol of the device is as follows: the device adopts CAN 2.0B communication protocol, 1 byte is used for clearly indicating the working mode of the device in 8 data bytes of a sending frame and a returning frame, 2 bytes are used for indicating angle data, and the data bits of the communication protocol are specifically explained as follows:
Figure GDA0002374613370000191
Figure GDA0002374613370000192
TABLE 1 operating mode interpretation (1 for valid, 0 for invalid)
Figure GDA0002374613370000193
Figure GDA0002374613370000201
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 (6)

1. An electric power steering apparatus comprising an inner end cap assembly, the inner end cap assembly comprising: 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 a sensor outlet end and is fixed on the inner surface of the inner end cover;
the electric power steering apparatus further includes: a shell assembly (1), an input shaft and screw assembly (2), a tooth sector shaft assembly (3), a supporting seat assembly (4), a worm wheel (5), a worm (6), an inner end cover assembly (7), a corner torque sensor (8), a plum blossom connecting sleeve assembly (10) and a motor assembly (11), a cavity with one closed end and one open 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 the closed end, the other end of the input shaft and the screw assembly (2) extends out of the cavity of the shell assembly, installing a gear sector shaft assembly (3) in the shell assembly (1) along the direction vertical to the input shaft and the screw assembly (2) and enabling the gear sector shaft assembly (3) to be 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); 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 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 worm wheel (5), the corner torque sensor (8) is connected with the axial direction and input shaft and screw assembly (2), the input shaft locking device 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 input shaft locking device comprises an end cover, a locking cover and a locking sleeve, wherein the locking cover is connected to the first end of the end cover through a connecting device, a through hole for inserting the input shaft is formed in the middle of the end cover and the locking cover, the locking sleeve is sleeved on the input shaft and is installed in the through hole of the locking cover, and the locking cover is sleeved on the locking sleeve in the through hole.
2. An electric power steering apparatus according to claim 1, wherein the end cap is attached to the steering gear housing, and a seal is provided between the end cap and the steering gear housing.
3. The electric power steering apparatus of claim 1, wherein a second end of the end cap opposite the first end is provided with an extension extending outward from a center of the locking device, the extension being provided with a through hole.
4. An electric power steering apparatus according to claim 3 wherein a second end of the end cap opposite the first end is provided with an annular boss forming an annular cavity at the second end.
5. An electric power steering apparatus according to claim 3, wherein 3 through holes are uniformly formed along the circumference of the central position of the locking device.
6. The steering device according to claim 5, wherein a non-through cavity with a variable inner diameter is arranged in the housing assembly (1) 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; 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);
one end of the input shaft and screw assembly (2) is arranged in the first inner circular surface (B), the support seat assembly (4) is arranged in the first inner threaded surface (D), the worm wheel (5) is arranged 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) and 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) and is coaxial with the input shaft and the screw assembly (2); 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 (9) 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 arranged in the secondary transmission cavity (C); the worm (6) is arranged in the screw cavity (I), is meshed with the worm wheel (5) and is fixed by a ball bearing of the fourth inner circular surface (J) and a locking nut screwed with the second inner thread surface (K); one end of the plum blossom-shaped connecting sleeve assembly (10) 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 (11); the motor assembly (11) is fixed on a motor flange mounting surface (M) of the shell assembly (1) through bolts; the worm gear and the worm transmit the torque of the motor to the input shaft and screw assembly (2), 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).
CN201810807626.1A 2016-10-09 2016-10-09 Inner end cover assembly of steering gear and steering gear thereof Active CN109278849B (en)

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CN112937675A (en) * 2021-04-06 2021-06-11 舍弗勒技术股份两合公司 Electric power steering apparatus
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CN108974116B (en) 2020-04-28
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CN109278849A (en) 2019-01-29
CN106394657A (en) 2017-02-15

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