CN106915380B - Power-assisted steering and independent driving integrated wheel-side electric driving device and control method thereof - Google Patents
Power-assisted steering and independent driving integrated wheel-side electric driving device and control method thereof Download PDFInfo
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- CN106915380B CN106915380B CN201710247964.XA CN201710247964A CN106915380B CN 106915380 B CN106915380 B CN 106915380B CN 201710247964 A CN201710247964 A CN 201710247964A CN 106915380 B CN106915380 B CN 106915380B
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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
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
- B62D5/046—Controlling the motor
- B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
- B60L15/2036—Electric differentials, e.g. for supporting steering vehicles
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- 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
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- 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
- B62D3/12—Steering gears mechanical of rack-and-pinion type
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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
- B62D5/0418—Electric motor acting on road wheel carriers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D9/00—Steering deflectable wheels not otherwise provided for
- B62D9/002—Steering deflectable wheels not otherwise provided for combined with means for differentially distributing power on the deflectable wheels during cornering
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/423—Torque
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Power Engineering (AREA)
- Power Steering Mechanism (AREA)
- Electric Propulsion And Braking For Vehicles (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
Abstract
The invention discloses a power steering and independent driving integrated wheel-side electric driving device, which comprises: the inner rotor of the double-rotor motor is connected with a first driving half shaft and used for driving wheels on one side, and the outer rotor is connected with a driving gear through an output shaft and can drive the driving gear to rotate; the rotor of the driving motor is connected with a second driving half shaft and is used for driving wheels on the other side; the two ends of the rack screw shaft are respectively hinged with a tie rod; and the central hole of the driven gear is matched with the rack screw shaft thread pair, and the driven gear can drive the rack screw shaft to move under the driving of the driving gear so as to realize steering assistance. The invention discloses a control method of a power steering and independent driving integrated wheel-side electric driving device.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a power steering and independent driving integrated wheel-side electric driving device and a control method thereof.
Background
The distributed driving electric automobile mainly comprises two forms of hub driving and wheel edge driving, unsprung mass is increased by the hub driving, ground dynamic load of tires is large, driving smoothness and maneuverability are affected, and meanwhile, a steering system and a suspension frame need to be redesigned in order to arrange a hub motor. Compared with wheel hub driving, wheel edge driving can also have the advantage of independent driving of each wheel in a wheel hub motor driving mode under the condition that unsprung mass is not increased, a steering system and a suspension can continue to use the prior art, and comprehensive performance is more excellent.
The electric power steering system can control the power motor to realize power assistance according to optimized power assistance characteristics, can realize low-speed steering at the same time, is light and convenient, has good road feel during high-speed running, improves the control stability and the control comfort of a driver, and is a steering system form with the widest application range at present. The conventional electric power steering system mainly has three types, i.e., a steering shaft assist type, a gear assist type, and a rack assist type.
The steering shaft power-assisted electric power steering system minimizes the space occupied by a steering gear, but because the electric motor is close to a driver, the fluctuation of the output torque of the electric motor and noise are easily transmitted to a steering wheel, so that the driving comfort and the road feel are influenced; the gear-assisted electric power steering system integrates the torque sensor, the motor, the speed reducing mechanism and the clutch, the motor directly drives the gear shaft through the speed reducing mechanism to assist power, the structure is complex, and the failure rate is high. The rack power-assisted electric power steering system realizes power assistance by directly applying power-assisted torque on the rack, has good system rigidity, large power transmission capacity and compact structure, is not limited by a mounting position, and improves driving comfort because the fluctuation of the motor is not easily transmitted to a steering wheel. However, the rack assist type electric power steering system needs a large output torque because the power assisting position is below the steering gear, and generally adopts 24V or 48V dc voltage for power supply in order to improve the economy, which needs an additional dc conversion circuit. This adds virtually additional cost to the existing 12V dc powered conventional automobile. Even for an electric vehicle, any type of electric power steering system needs to be additionally provided with a power steering motor and a speed reducing mechanism thereof to complete the required power assisting function.
Disclosure of Invention
Based on the background, the invention designs and develops a power-assisted steering and independent driving integrated wheel-side electric driving device, and aims to realize the integrated integration of a steering system and wheel-side independent driving by using a double-rotor motor for steering assistance.
The invention also designs and develops a control method of the power-assisted steering and independent driving integrated wheel-side electric driving device, and aims to apply additional power to the steering of an automobile by utilizing the differential power-assisted steering function which can be realized by independent driving so as to obtain additional output torque.
The technical scheme provided by the invention is as follows:
an integrated power steering and independent drive wheel-side electric drive device comprising:
the inner rotor of the double-rotor motor is connected with a first driving half shaft and used for driving wheels on one side, and the outer rotor is connected with a driving gear through an output shaft and can drive the driving gear to rotate;
the rotor of the driving motor is connected with the second driving half shaft and is used for driving the wheel on the other side;
the two ends of the rack screw shaft are respectively hinged with a tie rod;
and the central hole of the driven gear is matched with the rack screw shaft thread pair, and the driven gear can drive the rack screw shaft to move under the driving of the driving gear so as to realize steering.
Preferably, the steering system further comprises:
the center of the steering wheel is connected with a steering shaft;
a steering wheel torque sensor mounted on the steering shaft for detecting a torque of a steering wheel;
the rack screw shaft comprises a rack portion located on one side and a middle screw portion located on the other side, the rack portion is meshed with a steering gear at the lower end of the steering shaft, and the screw portion is matched with a central hole screw pair of the driven gear.
Preferably, the double rotor motor includes:
a housing having an accommodating space therein for arranging an outer rotor and an inner rotor;
permanent magnets embedded on the inner side and outer side surfaces of the outer rotor;
a stator fixed on the inner surface of the housing;
an excitation winding fixed to the stator and supplied with a current to generate a magnetic field;
an armature winding mounted on the inner rotor;
the outer rotor output shaft of the double-rotor motor is connected with a driving gear and used for outputting torque, and the inner rotor output shaft is connected with the first driving half shaft and used for outputting driving torque for driving a vehicle to run.
Preferably, the driving motor includes:
a housing having an accommodating space therein for arranging a rotor;
a permanent magnet embedded on the rotor surface;
a stator fixed on the inner surface of the housing;
an excitation winding fixed to the stator and supplied with a current to generate a magnetic field;
an armature winding mounted on the inner rotor;
and the rotor output shaft of the driving motor is connected with the second driving half shaft and is used for driving the wheel on the other side.
Preferably, the outer rotor of the dual-rotor motor comprises a main body and an end cover which are in jaw fit with each other, an inner rotor of the dual-rotor motor is supported and nested in an accommodating space formed by the main body and the end cover through upper and lower bearings, and an output end of the inner rotor penetrates out of the accommodating space and is connected with an output shaft of the inner rotor.
Preferably, the method further comprises the following steps:
the inner wall of a central hole of the driven gear is provided with a semicircular spiral groove, an inner circulating channel is further processed on the inner wall along the axial direction, and an inlet and an outlet of the driven gear are respectively arranged at the starting point and the ending point of the semicircular spiral groove;
the rack screw shaft is provided with a semicircular spiral groove, and the semicircular spiral groove corresponds to the semicircular spiral groove of the driven gear;
and the ball rolls along the semicircular spiral groove and the inner circulation channel.
It is preferable that the first and second liquid crystal layers are formed of,
one end of the first driving half shaft is connected with an inner rotor output shaft of the double-rotor motor through a universal joint and used for inputting driving force;
one end of the second driving half shaft is connected with a rotor output shaft of the driving motor through a universal joint and used for inputting driving force;
the steering knuckle is supported on the wheel hub and the wheel through a wheel hub bearing, and a hollow shaft neck is arranged on the steering knuckle;
wherein the tie rod is connected with the knuckle through a ball stud.
Preferably, the method further comprises the following steps:
a central processing unit connected to the dual-rotor motor through a CAN bus;
the steering wheel torque sensor is electrically connected with the central processing unit, and the central processing unit controls the torque of the double-rotor motor through the steering wheel torque.
A control method of an integrated power steering and independent driving wheel-side electric driving device comprises the following steps:
step one, collecting vehicle speed, accelerator pedal opening and steering wheel torque to obtain target total driving torque T d And target steering wheel steering assist torque T a ；
Step two, calculating to obtain the assistance F of the target required by the movement of the rack and loaded on the rack a Distribution of differential power-assisted steering rack force F a1 And a rack force F of the power-assisted steering of the double-rotor motor a2 The calculation formula is as follows:
F a ＝T a /r p ，
F a1 ＝kF a ，
F a2 ＝(1-k)F a ，
in the formula, r p The radius of a steering gear pinion, k is a differential power steering distribution coefficient, and k = 0-1;
step three, calculating to obtain a left-right wheel driving torque difference delta T, wherein the calculation formula is as follows:
wherein N is the transmission ratio from the translational displacement of the rack to the angular displacement of the knuckle, r w For rolling of wheels with variable diameter r σ A lateral offset distance for the grounding of the main pin;
step four, calculating to obtain the left and right driving torque, wherein the calculation formula is as follows:
T d ＝T r +T l ，
ΔT＝|T r -T l |，
in the formula, T r Output torque, T, for the inner rotor of a two-rotor motor l Outputting a torque for driving the motor, wherein when the vehicle turns to the left, T r ＞T l When the car turns to the right, T r ＜T l ；
Step four, calculating to obtain the output torque T of the outer rotor of the double-rotor motor w The calculation formula is as follows:
in the formula i 1 For the transmission ratio of the driving gear to the intermediate gear shaft gear, i 2 Gear ratio of gear pair for intermediate gear shaft gear to driven gear, d 2 Is the pitch diameter of the ball screw, and λ is the lead screw lead angle of the ball screw mechanism.
Compared with the prior art, the invention has the following beneficial effects:
1. the system integration is good; the power-assisted steering and independent driving integrated wheel-side electric driving device disclosed by the invention realizes the independent driving function of a traditional wheel-side driving system and simultaneously realizes the electric power-assisted steering function by using the double-rotor motor and the ball screw mechanism. Namely, the integration of a steering system and a driving system is realized;
2. the structure is compact; the power steering and independent driving integrated wheel-side electric driving device uses the double-rotor motor to provide driving torque and steering power steering torque at the same time, and adopts the ball screw mechanism to realize speed reduction, torque increase and motion conversion;
3. the differential drive can be utilized to cooperate with the power-assisted steering, thereby realizing the energy-saving steering; the power-assisted steering and independent driving integrated wheel-side electric driving device can exert the technical advantages of independent wheel-side motor driving of the left wheel and the right wheel, and utilizes the driving torque difference value of the left wheel and the right wheel to generate ground driving force difference, so that differential power-assisted steering torque is generated to cooperate with the double-rotor motor arranged on one side to complete power-assisted steering, the power-assisted steering torque requirement of the double-rotor motor can be reduced, and the steering energy conservation is realized;
4. the driving comfort is good; when the power-assisted steering and independent driving integrated wheel-side electric driving device is used for power-assisted steering, moment fluctuation and noise generated by the motor are not easy to transmit to a driver, and driving comfort is greatly improved.
Drawings
Fig. 1 is a three-dimensional view of an integrated power steering and independent driving wheel rim electric driving device according to the present invention.
Fig. 2 is a schematic structural diagram of an integrated power steering and independent driving wheel-side electric driving device according to the present invention.
Fig. 3 is a full sectional view of the ball screw mechanism of the integrated power steering and independent driving wheel-side electric drive device according to the present invention.
Fig. 4 is an axial view of a nut of a ball screw mechanism of an integrated power steering and independent drive wheel-side electric drive according to the present invention.
Fig. 5 is an external rotor axial view of a dual-rotor motor of the power steering and independent driving integrated wheel-side electric driving device according to the present invention.
Fig. 6 is an inner rotor axial view of a dual-rotor motor of an integrated power steering and independent driving wheel-side electric driving device according to the present invention.
Fig. 7 is a diagram illustrating electrical connections of an integrated power steering and independent drive wheel electric drive according to the present invention.
Fig. 8 is a flowchart illustrating a control method of the integrated power steering and independent driving wheel electric drive apparatus according to the present invention.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof. FIGS. 1-7 illustrate an example of an implementation of the present disclosure, but are not limited to this form. All systems which realize the integration of power steering and independent driving by utilizing a double-rotor motor belong to the protection scope of the claims. In addition, the directional terms used in the description of the present invention, such as "upper", "lower", "left", "right", "front", "rear", and the like, are only directional terms used for convenience of discussion in conjunction with the present example and the drawings thereof, and do not mean that the structures shown in the examples can only be arranged and installed in such a direction, and the direction and the connection relationship can be changed according to the actual arrangement space in actual use. Merely exchanging the orientation and arrangement relationship does not constitute a new structure different from the present invention.
As shown in fig. 1, the integrated power steering and independent driving wheel electric drive device according to the present invention includes: the steering system 100, the left wheel driving system 300, the power-assisted steering actuating system 400, the left driving motor 500, the dual-rotor motor 600 and the right wheel driving system 700.
In the embodiment shown in fig. 1 and 2, the dual-rotor motor 600 includes a housing 670, an outer rotor 610, an inner rotor 620, a permanent magnet 630, a field winding 640, a stator 650, and an armature winding 660. Wherein, the outer shell 670 is used for accommodating the outer rotor 610 and the inner rotor 620; the permanent magnets 630 are attached to the inner and outer side surfaces of the outer rotor 610; the stator 650 is fixed to the case 670; the field winding 640 is mounted on the stator 650; an armature winding 660 is mounted on the inner rotor 620. In the embodiment shown in fig. 5, the outer rotor 610 of the dual-rotor motor 600 includes a main body 611 and an end cap 612 that are engaged with each other by means of a jaw, and a stepped through hole formed by a bearing hole with a larger inner diameter and a light hole with a smaller inner diameter is formed in the center of the front end surface of the main body 611, and the bearing hole is used for installing an upper support bearing of the inner rotor 620. A bearing counter bore is machined in the inner side of the bottom of the end cap 612 and used for installing a lower support bearing of the inner rotor 620. Meanwhile, the output shaft end of the end cover 612 is provided with an external spline for connecting with the driving gear 440 through the spline. The inner rotor 620 is nested in the accommodating space formed by the jaw-type mutually-matched main body 611 and the end cover 612.
When the double-rotor steering motor is installed, the upper end of the inner rotor 620 and the bearing are installed inside the main body 611 of the outer rotor 610, the end cover 612 of the outer rotor is sleeved, and the outer rotor 610 and the inner rotor 620 are integrally installed in the double-rotor steering motor shell 670. The double-rotor motor shell is fixed on the frame, arranged above the suspension and belongs to sprung mass.
In another embodiment, as shown in fig. 5, six arc trapezoidal groove teeth are machined on the circumference of the matching part of the rear end of the main body 611 and the end cover 612, that is, the size of the radial near-center end of the groove teeth is smaller than that of the radial far-center end, and circular arc small grooves are also machined on the heel plane of the groove teeth; six arc trapezoid protruding teeth are processed at the corresponding positions of the six arc trapezoid grooves of the end cover 612 and the main body 611, the size of the radial near-center end of the protruding teeth is smaller than that of the radial far-center end of the protruding teeth, circular arc-shaped protrusions corresponding to small grooves at the tooth heel positions of the arc trapezoid grooves of the main body are further processed on the tooth crest plane of the arc trapezoid protruding teeth, and the arc trapezoid protrusions and the arc trapezoid grooves are the same in basic size. When the main body 611 and the end cover 612 are combined into the outer rotor 610, the arc trapezoid grooves of the main body 611 and the two sides of the tooth form of the corresponding circular trapezoid protruding teeth of the end cover are matched and positioned to play a role in radial positioning, so that the centers of the main body and the end cover are centered, and the small grooves of the respective tooth heels and the tooth centering circular arc-shaped protrusions are in clearance fit with each other correspondingly to play a role in auxiliary radial limiting and axial positioning, so that reliable centering is guaranteed when the main body 611 and the end cover 612 are in tooth embedding fit.
The dual-rotor motor is of a double-end output type structure, the output end of an inner rotor 620 of the dual-rotor motor is connected with a right inner universal joint 740 through a spline, and the output end of an outer rotor 610 is connected with the driving gear 440 through a spline.
In another embodiment, as shown in fig. 2, the left driving motor 500 is a general single-rotor motor, which is composed of a stator 550, a rotor 520, a permanent magnet 530, a field winding 540, and a motor housing 510. The stator 550 is fixed to the motor housing 510, the stator 550 is provided with the field winding 540, and the rotor 520 is fixed with the permanent magnet 530. The output end of the left driving motor 500 is the output shaft end of the rotor 520, and the top of the output end is provided with an external spline for connecting with the left inner universal joint 340. The left driving motor shell is fixed on the frame, arranged on the suspension and belongs to sprung mass.
As shown in fig. 1 and 2, the left wheel driving system 300 includes a left outer half shaft 310, a left outer universal joint 320, a left inner half shaft 330, a left inner universal joint 340, a left steering knuckle 350, and a left wheel 360. Wherein, the left inner universal joint 340 and the left outer universal joint 320 are equal angular velocity universal joints. The journal portion of the left steering knuckle 350 is made hollow to facilitate the penetration of the outboard half shaft 310 therethrough.
As shown in fig. 1 and 2, the right drive system 700 includes a right outer half shaft 710, a right outer universal joint 720, a right inner half shaft 730, a right inner universal joint 740, a right steering joint 750, and a right wheel 760. Wherein, the right inner universal joint 340 and the right outer universal joint 320 are equal angular velocity universal joints. The journal portion of the right knuckle 750 is made hollow to facilitate the penetration of the outboard half shaft 710 therethrough.
The left driving system 300 and the right driving system 700 are completely the same in composition, and the structure and the structures of the components are completely the same.
As shown in fig. 1 and 2, the output end of the inner rotor 620 of the double-rotor motor 600 is connected to the inner end of the right inner half shaft 730 through a right inner universal joint 740, and the outer end of the right inner half shaft 730 is connected to the inner end of the right outer half shaft 710 through a right outer universal joint 720. The outer end of the right external half shaft 710 is provided with a flange, six evenly distributed bolts are arranged on the flange, and the flange of the right external half shaft 710 is fixedly connected with a hub of a right wheel 760 through the bolts and nuts, so that the right external half shaft 710 can drive the right wheel 760 to rotate.
As shown in fig. 1 and 2, the output end of the left driving motor 500 is connected to the inner end of the left inner half shaft 330 via a left inner universal joint 340, and the outer end of the left inner half shaft 330 is connected to the inner end of the left outer half shaft 310 via a left outer universal joint 320. The outer end of the left outer half shaft 310 is provided with a flange, six evenly distributed bolts are processed on the flange, and the flange of the left outer half shaft 310 is fixedly connected with a hub of the left wheel 360 through bolts and nuts, so that the left outer half shaft 310 can drive the left wheel 360 to rotate.
In another embodiment, as shown in fig. 1, 2, 3 and 4, the power steering system 400 comprises a ball screw mechanism nut 410, an intermediate gear shaft gear 420, a rack screw shaft 430, a driving gear 440, an intermediate gear shaft 450 and balls 460. The ball 460, the rack screw shaft 430 and the ball screw mechanism nut 410 form a ball screw nut pair, and the ball screw nut pair has the function of converting the rotary motion of the dual-rotor motor outer rotor 610 into linear motion of the rack screw shaft 430 through the special function of the ball screw nut mechanism. Wherein the rack screw shaft 430 and the rack in the steering gear 160 are of an integrated structure, and a semicircular spiral groove is processed on the rack screw shaft 430 to be used as a rolling track of the ball 460; the ball screw mechanism nut 410 is in a gear shaft shape, a semicircular spiral groove which is the same as that of the screw 430 is machined in the inner wall of the center of the nut and used for assembling the ball 460 and serving as a sliding track of the ball 460, and the hole wall is a unthreaded hole. Meanwhile, an inner circulation channel with balls is formed in the inner wall of the nut 410 in the axial direction, the inlet and the outlet of the channel are respectively arranged at the starting point and the final point of the semicircular spiral groove, and the balls 460 can circularly roll in the track through the ball circulation channel, so that the rotary motion of the nut 410 is converted into the linear motion of the lead screw 430. The driven gear 401 in the middle of the nut 410 of the ball screw mechanism is a generally straight-toothed gear, which is engaged with a generally straight-toothed spur gear 420 on the counter gear shaft 450. The intermediate gear shaft 450 is supported on the steering gear housing by a pair of angular contact ball bearings. The driving gear 440 is a common spur gear, and a spline hole corresponding to a spline at the output end of the dual-rotor motor outer rotor 610 is formed in the center of the driving gear for connecting with the output shaft end of the dual-rotor motor outer rotor 610. The driving gear 440 is engaged with the counter gear shaft gear 420, and has the same pressure angle and module as the counter gear shaft gear 420.
In another embodiment, as shown in fig. 1 and 2, the steering system 100 is composed of a steering wheel 101, a steering shaft 110, a steering wheel torque sensor 120, a first universal joint 130, a steering transmission shaft 140, a second universal joint 150, a steering gear 160, a left steering gear housing 170, a right steering gear housing 180, and a tie rod 190. The center of the steering wheel 101 is connected with a steering shaft 110, a steering wheel torque sensor 120 is arranged on the steering shaft, the lower end of the steering shaft 110 is connected with the input end of a steering transmission shaft 140 through a first universal joint 130, the output end of the steering transmission shaft 140 is connected with the input end of a second universal joint 150, and the output end of the second universal joint 150 is connected with the input end of a steering gear 160.
The gear rack steering gear selected for the steering gear 160 comprises a steering input pinion, a rack and a steering gear shell. Wherein, the rack and the lead screw of the ball screw mechanism are processed into a whole to form a rack lead screw shaft 430. Threaded holes are formed in the centers of both ends of the rack screw shaft 430 to receive ball studs, the left and right tie rods 190 are connected by the ball studs, and the left and right tie rods 190 are connected to the left knuckle 350 and the right knuckle 750, respectively, by the ball studs. It should be noted that the present invention is not limited to the use of rack and pinion steering gear, and other types of steering gear can be used, and this is not intended to limit the scope of the present invention.
As shown in fig. 1, 2 and 3, the steering gear housing is divided into a left steering gear housing 170 and a right steering gear housing 180, the left steering gear housing 170 and the right steering gear housing 180 are connected and fixed by bolts and nuts, wherein a driving gear 440, an intermediate gear shaft 450 and a ball screw mechanism nut 410 are installed in parallel, and a thrust bearing 190 is installed between the outer walls of the ball screw mechanism nut 410 and the left and right steering gear housings to limit the horizontal movement of the ball screw mechanism nut 410. Both the drive gear 440 and the intermediate gear shaft 450 are supported on the steering gear housing by bearings. The steering gear housing is fixed with the frame, arranged above the suspension and belonging to the sprung mass.
As shown in fig. 1 and fig. 2, the specific connection relationship between the components is as follows: the output end of an inner rotor 620 of the double-rotor motor is connected with the inner end of a right inner half shaft 730 through a right inner universal joint 740, the other end of the right inner half shaft 730 is connected with the inner end of a right outer half shaft 710 through an outer universal joint 720, the right outer half shaft 710 penetrates through the hollow shaft neck center of a right wheel steering joint 750, and the right outer half shaft 710 is connected with the hub of a right wheel 760 through flanges on the right outer half shaft 710 by uniformly distributed bolts and nuts; the output shaft end of the left driving motor 500 is connected with the inner end of the left inner half shaft 330 through a left inner universal joint 340, the other end of the left inner half shaft 330 is connected with the inner end of the left outer half shaft 310 through a left outer universal joint 320, the left outer half shaft 310 passes through the hollow shaft neck center of the left wheel steering knuckle 350, and the left outer half shaft 310 and the wheel hub of the left wheel 360 are fixed through flanges on the left outer half shaft 310 by uniformly distributed bolts and nuts. The center of a steering wheel 101 is connected with a steering shaft 110, the steering shaft 110 is provided with a steering wheel torque sensor 120, the lower end of the steering shaft 110 is connected with the input end of a steering transmission shaft 140 through a first universal joint 130, the output end of the steering transmission shaft 140 is connected with the input end of a second universal joint 150, the output end of the second universal joint 150 is connected with the input end of a steering gear 160, a rack of the steering gear 160 and a lead screw of a ball screw mechanism are processed into a whole to form a rack lead screw shaft 430, the two ends of the rack lead screw shaft 430 are respectively connected with a left steering tie rod 190 and a right steering tie rod 190 through ball pins, and the left steering tie rod 190 and the right steering tie rod 190 are respectively connected with a left wheel steering knuckle 350 and a right wheel steering knuckle 750 through ball pins. The output shaft of the birotor motor outer rotor 610 is fixed with a driving gear 440 through a spline, the driving gear 440 is meshed with an intermediate gear shaft gear 420, and the driving gear 440 and the intermediate gear shaft 450 are respectively supported on a steering gear shell through a pair of angular contact ball bearings. The screw of the ball screw mechanism and the rack of the steering gear 160 are processed into a whole to form a rack screw shaft 430, the driven gear 401 on the ball screw mechanism nut 410 is meshed with the intermediate gear shaft gear 420, two axial ends of the ball screw mechanism nut 410 are respectively provided with a thrust bearing 190, and the pair of thrust bearings 190 are respectively arranged on the left steering gear shell 170 and the right steering gear shell 180, so that the linear motion of the ball screw mechanism nut 410 along the screw is limited, the ball screw mechanism nut 410 can only rotate around the axis of the rack screw shaft 430, and the rack screw shaft 430 is driven to move linearly.
In another embodiment, as shown in fig. 7, the steering wheel torque sensor 120 is connected to a central processing unit (ECU) by a cable, and the ECU is connected to the double-rotor motor 600 by a cable. The ECU CAN read the steering wheel torque signal measured in the steering wheel torque sensor 120, and simultaneously, is connected to the entire vehicle CAN bus, and CAN read the vehicle speed and other signals of the CAN bus. The ECU may control the pair-rotor motor 600.
The steering and driving integrated wheel-side electric drive system has the specific working process and working principle that:
an inner rotor 620 of the double-rotor motor is controlled to generate driving torque, and the driving torque is transmitted to a hub of a right wheel 760 through a right inner universal joint 740, an inner half shaft 730, an outer universal joint 720 and an outer half shaft 710 so as to drive the right wheel 760 to rotate; similarly, the left driving motor 500 is controlled by the rotor to output driving torque, and the driving torque is transmitted to the hub of the left wheel 360 through the left inner universal joint 340, the left inner half shaft 330, the left outer universal joint 320 and the left outer half shaft 310, so as to drive the left wheel 360 to rotate.
When the vehicle travels straight, the driving torque output by the inner rotor 620 of the dual-rotor motor 600 is equal to that output by the left driving motor 500; when the automobile turns, because the torque of the wheel side motors at two sides can be independently controlled, the driving motors (namely the double-rotor motor and the left driving motor) of the left wheel and the right wheel which are positioned at the inner side and the outer side of the curve can output unequal torque, so that left and right driving force differences are generated on the ground, differential power-assisted steering torque can be generated by utilizing the driving force differences and the lateral offset distance of the tire grounding main pin, and the power-assisted steering torque output by the outer rotor of the double-rotor motor can be used for assisting a driver to complete steering action together with the power-assisted steering torque output by the outer rotor of the double-rotor motor, thereby lightening the steering burden of the driver and improving the steering portability.
When a driver operates the steering wheel 101 to rotate, the steering wheel 101 drives the steering shaft 110 to rotate, the steering wheel torque sensor 120 measures torque applied by the driver and transmits signals to a central control unit (ECU), the ECU reads corresponding boosting torque from a boosting characteristic curve chart stored in the ECU by combining vehicle speed signals, calculates winding current corresponding to the boosting torque generated by the dual-rotor motor outer rotor 610, sends a control command to the dual-rotor motor outer rotor 610, the dual-rotor motor outer rotor 610 generates boosting torque, the boosting torque directly acts on the rack 430 through the driving gear 440, the intermediate gear shaft gear 420 and the ball screw mechanism, and the boosting torque is superposed with the steering torque applied by the driver on the rack 430, so that the steering tie rod 190 is pulled to enable the left wheel 360 and the right wheel 760 to rotate through corresponding angles, and the function of electric power steering is realized.
As shown in fig. 8, the control method of the integrated power steering and independent driving wheel-side electric drive device according to the present invention specifically includes the following steps:
step 1: initializing a system program, and reading vehicle running state signals such as vehicle speed, accelerator pedal opening, steering wheel torque and the like by a controller;
step 2: firstly, look-up table is searched according to vehicle speed and accelerator pedal opening degree signals to obtain target total driving torque T d . Secondly, look-up table is carried out according to the vehicle speed and the steering wheel torque signal to obtain the target steering wheel steering power-assisted torque T a . The required data table is calibrated in advance and stored in the ECU;
and step 3: calculating the assistance F of the target loaded on the rack required by the movement of the rack a The calculation formula is as follows:
F a ＝T a /r p ，
wherein r is p Is the steering gear pinion radius; the assistance force F a The wheel is pushed to deflect around the main pin together with the moving force applied to the rack by the driver, and the steering is completed.
And 4, step 4: distributing differential power assisted steering rack forces F a1 And a power-assisted steering rack force F of the double-rotor motor a2 The calculation formula is as follows:
F a1 ＝kF a ，
F a2 ＝(1-k)F a
wherein k (the value is between 0 and 1) is defined as a differential power-assisted steering distribution coefficient, and when k =1, all the coefficients are differential power-assisted steering; when k =0, all the motors are used for power steering of the double-rotor motor. K =0 in the case of normal driving, and k > 0 in the case of energy-saving driving. The specific value of k is determined according to the principle that the distributed torque of each motor is smaller than the most economic working torque of the motor at the current rotating speed, so that the requirement of saving the total energy as much as possible is ensured.
And 5: calculating the left-right wheel driving torque difference Delta T according to the following formula:
wherein N is the transmission ratio (unit: m/rad) from the translational displacement of the rack to the angular displacement of the knuckle; r is a radical of hydrogen w Rolling and reducing the diameter of the wheel; r is a radical of hydrogen σ Is the kingpin ground lateral offset.
Step 6: calculating the left and right wheel driving torque command according to the following two formulas,
T d ＝T r +T l ，
ΔT＝|T r -T l |，
wherein, T r Output torque, T, for the inner rotor of a two-rotor motor l And outputting torque for the left driving motor. When the differential power-assisted steering requires the automobile to turn left, T r ＞T l (ii) a When the car turns to the right, T r ＜T l 。
And finally, outputting a torque control command of an inner rotor of the double-rotor motor to the double-rotor motor and a torque control command of the left driving motor to the left driving motor.
And 7: calculating the output torque T of the outer rotor of the double-rotor motor w Instruction, T w The calculation formula is as follows:
in the formula i 1 Is the gear ratio of the driving gear 440 to the intermediate gear shaft gear 420, i 2 A gear ratio, d, of the counter gear shaft gear 420 to the driven gear 401 on the ball screw mechanism nut 410 2 Is the pitch diameter of the ball screw, and λ is the lead screw lead angle of the ball screw mechanism.
And finally, outputting a torque control command of an outer rotor of the double-rotor motor to the double-rotor motor.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (8)
1. An integrated power steering and independent drive wheel-side electric drive device, comprising:
the inner rotor of the double-rotor motor is connected with a first driving half shaft and used for driving wheels on one side, and the outer rotor is connected with a driving gear through an output shaft and can drive the driving gear to rotate;
the rotor of the driving motor is connected with the second driving half shaft and is used for driving the wheel on the other side;
the two ends of the rack screw shaft are respectively hinged with a tie rod; the rack and a lead screw of the ball screw mechanism are processed into a whole to form a rack lead screw shaft;
the central hole of the driven gear is matched with the rack screw shaft thread pair, and the driven gear can drive the rack screw shaft to move under the driving of the driving gear so as to realize steering;
the driving gear is meshed with the intermediate gear shaft gear, and the driven gear is meshed with the intermediate gear shaft gear.
2. The integrated power steering and independent drive wheel rim electric drive of claim 1, further comprising a steering system comprising:
the center of the steering wheel is connected with a steering shaft;
a steering wheel torque sensor mounted on the steering shaft for detecting a torque of a steering wheel;
the rack screw shaft comprises a rack portion located on one side and a middle screw portion located on the other side, the rack portion is meshed with a steering gear at the lower end of the steering shaft, and the screw portion is matched with a central hole screw pair of the driven gear.
3. The power steering and independent drive integrated wheel-side electric drive device according to claim 2, wherein the double-rotor motor includes:
a housing having an accommodating space therein for arranging an outer rotor and an inner rotor;
permanent magnets embedded on the inner side and outer side surfaces of the outer rotor;
a stator fixed on the inner surface of the housing;
an excitation winding fixed to the stator and supplied with a current to generate a magnetic field;
an armature winding mounted on the inner rotor;
the outer rotor output shaft of the double-rotor motor is connected with a driving gear and used for outputting torque, and the inner rotor output shaft is connected with the first driving half shaft and used for outputting driving torque for driving a vehicle to run.
4. The power steering and independent drive integrated wheel-side electric drive device according to claim 3, wherein the drive motor includes:
a housing having an accommodating space therein for arranging a rotor;
a permanent magnet embedded on the rotor surface;
a stator fixed on the inner surface of the housing;
an excitation winding fixed to the stator and supplied with a current to generate a magnetic field;
an armature winding mounted on the inner rotor;
and the rotor output shaft of the driving motor is connected with the second driving half shaft and is used for driving the wheel on the other side.
5. The integrated power steering and independent driving wheel electric driving device according to claim 4, wherein the outer rotor of the dual-rotor motor comprises a jaw-type mutually-matched main body and an end cover, the inner rotor of the dual-rotor motor is supported and nested in an accommodating space formed by the main body and the end cover through an upper bearing and a lower bearing, and the output end of the inner rotor penetrates out of the accommodating space to be connected with the output shaft of the inner rotor.
6. An integrated power steering and independent drive wheel-side electric drive device according to claim 5, further comprising:
the inner wall of a central hole of the driven gear is provided with a semicircular spiral groove, an inner circulating channel is further processed on the inner wall along the axial direction, and an inlet and an outlet of the driven gear are respectively arranged at the starting point and the ending point of the semicircular spiral groove;
the rack screw shaft is provided with a semicircular spiral groove, and the semicircular spiral groove corresponds to the semicircular spiral groove of the driven gear;
and the ball rolls along the semicircular spiral groove and the inner circulation channel.
7. An integrated power steering and independent drive wheel rim electric drive as recited in claim 4,
one end of the first driving half shaft is connected with an inner rotor output shaft of the double-rotor motor through a universal joint and used for inputting driving force;
one end of the second driving half shaft is connected with a rotor output shaft of the driving motor through a universal joint and used for inputting driving force;
the steering knuckle is supported on the wheel hub and the wheel through a wheel hub bearing, and a hollow shaft neck is arranged on the steering knuckle;
wherein the tie rod is connected with the knuckle through a ball stud.
8. An integrated power steering and independent drive wheel-side electric drive device according to any of claims 2 and 4 to 7, further comprising:
a central processing unit connected to the dual-rotor motor through a CAN bus;
the steering wheel torque sensor is electrically connected with the central processing unit, and the central processing unit controls the torque of the double-rotor motor through the steering wheel torque.
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| CN108248378B (en) * | 2018-01-26 | 2023-08-15 | 浙江三锋实业股份有限公司 | Power-assisted transmission structure of running machine |
| CN108146423B (en) * | 2018-02-09 | 2023-07-21 | 吉林大学 | Steering, anti-tilting and driving integrated wheel electric driving system and control method |
| CN108582093A (en) * | 2018-04-02 | 2018-09-28 | 北京理工大学 | A kind of pipeline detection robot based on rack-and-pinion reducing |
| CN114312991B (en) * | 2022-03-07 | 2022-05-17 | 深圳小象电动科技有限公司 | Wheel-side power module of integrated steering mechanism |
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| JP4487676B2 (en) * | 2004-08-03 | 2010-06-23 | 株式会社ジェイテクト | Electric power steering device with variable transmission ratio mechanism |
| EP1990256B1 (en) * | 2007-05-08 | 2011-06-15 | Jtekt Corporation | Electric power steering device |
| US9502931B2 (en) * | 2012-03-23 | 2016-11-22 | Asmo Co., Ltd. | Brushless motor |
| CN103633813B (en) * | 2013-11-12 | 2015-09-30 | 江苏大学 | Split electromagnetic coupled clutch and the electric-controlled hydraulic steering be used as power with it |
| CN105667576B (en) * | 2015-12-30 | 2017-10-17 | 北京理工大学 | A kind of steering mechanism of electric car |
| CN106428201B (en) * | 2016-12-16 | 2018-09-25 | 吉林大学 | A kind of nested type birotor steering motor multi-mode steering system and control method |
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