JP3846415B2 - Vehicle steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus in which a steering reaction force is applied to a turning operation of a steering handle for turning steered wheels.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a rotor that is connected to a steering handle via a rotating shaft and rotates integrally with the steering handle, and a housing that houses the rotor and is filled with high-viscosity fluid (silicon oil) are provided. A technique for applying a friction reaction force to the rotation of a steering handle by a friction reaction force of a highly viscous fluid is known (see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 1-153379
[0004]
[Problems to be solved by the invention]
In the above-described conventional apparatus, a friction reaction force proportional to the rotational speed of the rotor is applied to the rotor. However, since the friction reaction force when the steering handle rotates at a very low speed is very small, the steering handle is stable at the neutral position. It is difficult to improve the straight running stability of the vehicle.
[0005]
SUMMARY OF THE INVENTION
The present invention has been made to cope with the above-described problems, and the object of the present invention is to make it possible to apply a certain amount of friction reaction force to a steering handle that rotates at a very low speed. An object of the present invention is to provide a vehicle steering apparatus that improves the stability in the neutral position and improves the straight-line stability of the vehicle.
[0006]
  In order to achieve the above object, the present invention is characterized in that, in a steering apparatus for a vehicle that steers steered wheels according to the rotation of a steering handle, the steering handle is coupled to the steering handle via a rotating shaft. A rotor that rotates integrally, and a non-Newtonian fluid that houses the rotor and applies a frictional reaction force that changes greatly and nonlinearly when the rotor changes from a stopped state to a rotating state.A non-Newtonian fluid containing magnetic powderFilled with housing andA magnetic field line generating means for generating a magnetic field line to form a magnetic field in the non-Newtonian fluid, and a step is provided on at least a part of the outer surface of the rotor facing the inner surface of the housing.There is. In this case, a Bingham fluid may be adopted as the non-Newtonian fluid.Yes. Further, the magnetic force line generating means can be constituted by a permanent magnet or an electromagnet.
[0007]
  According to this, a relatively large frictional reaction force can be applied even to a steering wheel that rotates at a very low speed, so the stability at the neutral position of the steering wheel is improved and the straight running stability of the vehicle is improved. To do. In addition, since the magnetic field line generating means forms a magnetic field in the non-Newtonian fluid,Increased viscosity of non-Newtonian fluidsAndA larger reaction force can be obtained.Furthermore, since the magnetic powder collected by the magnetic field functions like an orifice with respect to a non-Newtonian fluid that moves due to the step of the rotor when the rotor rotates, a larger reaction force can be obtained. Since the agitation does not cause precipitation, the viscosity of the non-Newtonian fluid by the magnetic powder can always be kept high, and the reaction force generation function by the magnetic powder can always be maintained.
[0010]
Another feature of the present invention is that magnetic field mode control means for changing and controlling the magnetic field forming mode by the electromagnet is provided. In this case, the magnetic field mode control means may be constituted by energization mode control means for controlling the energization mode for the electromagnet. According to this, since the reaction force against the rotation of the rotor can be variably controlled by changing and controlling the magnetic field formation mode, an accurate reaction force can be applied to various turning operations of the steering handle.
[0011]
Another feature of the present invention is that the turning limit control means detects the turning limit of the steered wheel and controls the magnetic field mode control means at the time of detecting the turning limit to strengthen the magnetic field by the electromagnet. It is in having established. According to this, when the steering wheel is steered to the limit by turning the steering handle, the reaction force against the turning operation of the steering handle is increased and controlled by the control of the magnetic field mode by the electromagnet. Steering wheels are well simulated, and the steering feeling is improved.
[0012]
Further, another feature of the present invention is that the steering delay control means detects the steering delay of the steered wheel and controls the magnetic field mode control means when the steering delay is detected to strengthen the magnetic field by the electromagnet. It is in having established. According to this, when there is a delay in the steering of the steering wheel, the reaction force against the turning operation of the steering handle is increased and controlled by the control of the magnetic field mode by the electromagnet. The wheel turning delay is accurately simulated, and the steering feeling is improved.
[0013]
Another feature of the present invention is that, in addition to the reaction force applying device using the non-Newtonian fluid, an electric motor connected to the steering handle via a rotating shaft to apply a reaction force to the rotation of the steering handle. It is in having. According to this, it becomes possible to apply a larger reaction force to the turning of the steering handle, and at the same time, it is possible to perform a reaction force application control with a high degree of freedom by controlling the electric motor. In particular, when a non-Newtonian fluid containing magnetic powder is used and a magnetic field is formed in the non-Newtonian fluid by an electromagnet, a high degree of reaction force control can be achieved through electric current control of the electric motor and the electromagnet. Even if an abnormality occurs in one of the control systems of the motor and the electromagnet, the control of the reaction force with respect to the turning of the steering wheel can be performed by one control.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a vehicle steering apparatus according to this embodiment. This steering device steers the left and right front wheels 20a and 20b, which are steered wheels, to the left and right according to the turning of the steering handle 10.
[0019]
The steering handle 10 is fixed to the upper end of the rotating shaft 11, and the rotating shaft 11 rotates integrally with the steering handle 10. An electric motor 12 for generating reaction force is connected to the lower end of the rotating shaft 11 via a speed reducer 13. The electric motor 12 applies a reaction force to the turning operation of the steering handle 10 via the speed reducer 13 according to the rotational torque. The electric motor 12 constitutes a motor reaction force generator. A fluid reaction force generator 14 is assembled in the middle of the rotating shaft 11.
[0020]
The fluid reaction force generating device 14 is fixed to a vehicle body member (not shown), and has a cylindrical shape and a non-rotating shape in which the rotary shaft 11 is pivotally penetrated in the axial direction at the center position of the upper surface and the lower surface as shown in FIG. A housing 41 made of a magnetic material is provided. The housing 41 accommodates a columnar rotor 42 fixed on the outer peripheral surface of the rotary shaft 11. Further, a seal member (not shown) is interposed between the housing 41 and the rotating shaft 11, and the internal space R <b> 1 formed between the outer surface of the rotating shaft 11 and the rotor 42 and the inner surface of the housing 41 is sealed. Yes.
[0021]
The internal space R1 is filled with a Bingham fluid mixed with magnetic powder (powder made of a magnetic material). This Bingham fluid is a kind of non-Newtonian fluid and has a characteristic of increasing the shear stress from a positive value with respect to an increase in the shear rate from “0”. In other words, the Bingham fluid is a non-Newtonian fluid that imparts to the rotor 42 a frictional reaction force that varies greatly and nonlinearly with respect to the change of the rotor 42 from the stopped state to the rotating state. In FIG. 2, the internal space R <b> 1 is widely drawn. However, in order to apply a large frictional reaction force to the rotation of the rotor 42, the internal space R <b> 1 is actually extremely narrow. That is, the gap between the inner surface of the housing 41 and the outer surface of the rotor 42 is set to be extremely small.
[0022]
Further, in order to apply a greater frictional reaction force to the rotation of the rotor 42, fins 42 a protruding from the outer peripheral surface are spirally and integrally formed on the outer peripheral surface of the rotor 42. The interval and height of the fins 42a, the angle with respect to the rotation direction of the rotor 42, and the like are determined by the required magnitude of the friction reaction force. The fin 42a also has a function of stirring the Bingham fluid in order to avoid precipitation of magnetic powder in the Bingham fluid, and constitutes the stirring means of the present invention. In addition, as long as it has a function to obtain a large frictional reaction force and stir the Bingham fluid, instead of the helical fin 42a, a protruding portion protruding in various shapes such as a square shape and a circular shape on the outer peripheral surface of the rotor 42 May be provided.
[0023]
On the inner peripheral surface of the housing 41, a magnetic force line generator composed of an electromagnet composed of an iron core 43 and a coil 44 is assembled at an appropriate position in the circumferential direction. The iron core 43 is configured by bending a cylindrical iron bar into a U-shape. The coil 44 is wound around the center of the iron core and molded with a resin 45. The magnetic field generator configured in this way forms a magnetic field at an appropriate location in the internal space R1, and restricts the movement of the magnetic powder mixed in the Bingham fluid, thereby reducing the friction reaction against the rotation of the rotor 42 by the Bingham fluid. Functions to increase power. The number of coils 44 is determined according to the required friction reaction force.
[0024]
Returning to the description of FIG. 1, the left and right front wheels 20a and 20b are connected to both ends of the rack bar 21 via left and right tie rods 22a and 22b and left and right knuckle arms 23a and 23b so as to be steerable. The rack bar 21 is supported by a vehicle body (not shown) so as to be displaceable in the axial direction, and steers the left and right front wheels 20a and 20b to the left and right according to the displacement. A pinion gear 24 meshes with the rack bar 21. The pinion gear 24 is connected to an electric motor 27 for turning via a rotating shaft 25 and a speed reducer 26. With this configuration, when the electric motor 27 rotates, the rotation is decelerated by the speed reducer 26 and transmitted to the pinion gear 24 via the rotating shaft 25. The rack bar 21 is displaced in the axial direction by the rotation of the pinion gear 24, and the left and right front wheels 20a and 20b are steered.
[0025]
Next, the electric control device 30 for controlling the rotation of the electric motor 12 for generating the steering reaction force and the electric motor 27 for turning and the energization of the coil 44 in the fluid reaction force generation device 14 will be described. . The electric control device 30 includes an electronic control unit 31, a steering angle sensor 32, a turning angle sensor 33, and a vehicle speed sensor 34. The electronic control unit 31 includes a microcomputer including a CPU, a ROM, a RAM, a timer, and the like as main components, and repeatedly executes the steering control program of FIG. 4 every predetermined short time to rotate the electric motors 12 and 27 and The energization of the coil 44 in the fluid reaction force generator 14 is controlled.
[0026]
The steering angle sensor 32 is assembled to the rotary shaft 11, detects the rotation angle from the neutral position of the shaft 11, that is, the steering angle θ of the steering handle 10, and supplies it to the electronic control unit 31. The turning angle sensor 33 is assembled to the rotating shaft 25, detects the turning angle from the neutral position of the shaft 25, that is, the turning angle φ of the left and right front wheels 20a, 20b, and supplies it to the electronic control unit 31. The steering angle θ and the turning angle ψ are represented by setting the neutral position to “0”, the left direction angle being positive, and the right direction angle being negative. The vehicle speed sensor 34 detects the vehicle speed V based on the rotational speed of the output shaft of the transmission and supplies it to the electronic control unit 31.
[0027]
In the vehicle steering apparatus configured as described above, the reduction gear 13 is greatly affected by the frictional force change in the mechanism and the inertia of the electric motor 12, so that the steering reaction force targeted for the driver's steering operation is targeted. In particular, it is difficult to apply an appropriate reaction force to the operation of the steering handle 10 in the vicinity of the neutral position. In order to solve this drawback, the vehicle steering device shown in FIG. 1 may be modified to directly connect the electric motor 12 to the rotary shaft 11 without the reduction gear 13 as shown in FIG. This is preferable in terms of controlling the reaction force against the steering operation of the person. However, in the case of this modification, it is necessary to use an electric motor having a large output and good control accuracy in order to omit the reduction gear 13. Other configurations are the same as those in FIG.
[0028]
Next, the operation of the vehicle steering device configured as described above will be described. However, the control operation by the electric control device 30 in the vehicle steering device shown in FIG. 1 and the vehicle steering device shown in FIG. 3 is the same. These operations will be described simultaneously. After turning on the ignition switch of the vehicle, the electronic control unit 31 repeatedly executes the steering control program of FIG. 4 every predetermined short time. The execution of this steering control program is started in step S10, and the steering wheel steering angle θ, the front wheel turning angle ψ, and the vehicle speed V are input from the steering angle sensor 32, the turning angle sensor 33, and the vehicle speed sensor 34 in step S11, respectively. . In step S12, the target turning angle ψ * of the left and right front wheels 20a, 20b is calculated in accordance with the steering wheel steering angle θ. In this calculation, a table that stores the target turning angle ψ *, which represents the relationship of the target turning angle ψ * with respect to the steering angle θ, and is approximately proportional to the steering angle θ.
[0029]
After the process of step S12, in step S13, the rotation of the electric motor 27 is controlled so that the input front wheel turning angle ψ matches the calculated target turning angle ψ *. The rotation of the electric motor 27 is transmitted to the pinion gear 24 via the speed reducer 26 and the rotating shaft 25, and is converted into a linear motion of the rack bar 21 by the action of the pinion gear 24 and the rack bar 21. The axial displacement of the rack bar 21 is transmitted to the left and right front wheels 20a and 20b via the tie rods 22a and 22b and the knuckle arms 23a and 23b, and the left and right front wheels 20a and 20b rotate according to the turning operation of the steering handle 10. Steered.
[0030]
Next, in steps S14 and S15, it is determined whether the fluid reaction force generator 14 and the reaction force generating electric motor 12 are normal. Various methods of determining the normality of the fluid reaction force generator 14 are conceivable. The determination is based on, for example, a detection circuit output that is included in the electronic control unit 31 and detects disconnection or short-circuit of the coil 44. Done. There are various methods for determining whether the electric motor 12 is normal. This determination is, for example, output from a detection circuit that is included in the electronic control unit 31 and detects a disconnection or a short circuit of the winding of the electric motor 12. Based on.
[0031]
First, the case where both the fluid reaction force generator 14 and the electric motor 12 are normal will be described. In this case, “Yes” is determined in steps S14 and S15, and the first reaction force control routine is executed in step S16. The details of the first reaction force control routine are shown in FIG. 5, and its execution is started in step S30. After this execution is started, the steering wheel steering speed θv is calculated by time-differentiating the steering wheel steering angle θ input in step S11 of FIG. 4 in step S31, and the determination processing in steps S32 and S33 is executed. The determination process in step S32 is to determine whether or not the steering wheel 10 is being cut. Specifically, the calculated time differential value d | θv | / dt of the absolute value | θv | of the steering wheel steering speed θv is calculated. It is determined whether or not it is equal to or greater than a predetermined value. The determination process in step S33 is to determine whether or not the steering handle 10 is being held near the neutral position. Specifically, the time differential value d | θv | / dt is equal to or less than a predetermined value, and It is determined whether or not the absolute value | θ | of the steering wheel steering angle θ is equal to or smaller than a predetermined value.
[0032]
If the steering wheel 10 is being cut, it is determined “Yes” in step S32, and the reaction force distribution ratio RT is set to a positive predetermined value ra1 smaller than “1” in step S34. If the steering handle 10 is being held near the neutral position, “Yes” is determined in Step S33, and the reaction force distribution ratio RT is set to a positive predetermined value ra2 smaller than “1” in Step S35. Further, if the steering handle 10 is not being cut or kept near the neutral position, it is determined as “No” in steps S32 and S33, and the reaction force distribution ratio RT is a positive value smaller than “1” in step S36. Set to the predetermined value rb. The reaction force distribution ratio RT determines the ratio of the steering reaction force by the fluid reaction force generator 14 and the reaction force by the electric motor 12. The predetermined values ra1, ra2, rb are in a relationship of ra1> rb, ra2> rb.
[0033]
Next, referring to the first to third maps for the fluid reaction force in step S37, the first to third energizations for the fluid reaction force according to the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V. Amount I₁₁, I₁₂, I₁₃Respectively. These first to third maps are prepared in advance in the memory of the electronic control unit 31.
[0034]
The first map shows the first energization amount I with respect to the steering wheel steering speed θv.₁₁The first energization amount I₁₁As shown in FIG. 8, when the steering wheel steering speed θv is “0”, it becomes a predetermined positive value and gradually increases as the absolute value | θv | of the steering wheel steering speed θv increases. This is because the energization control for the coil 44 described later enables the steering handle 10 to be easily turned at the start of operation of the steering handle 10 and gives a sense of stability to the fast turning operation of the steering handle 10. is there.
[0035]
The second map shows the second energization amount I with respect to the steering angle θ.₁₂The second energization amount I₁₂As shown by the solid line in FIG. 9, the value is a positive predetermined value when the steering angle θ is near “0”, and decreases slightly when the absolute value | θ | of the steering angle θ is slightly increased. It gradually increases as the absolute value | θ | increases further. This is because energization control to the coil 44 described later enables the steering handle 10 to be easily rotated when starting operation from the neutral position of the steering handle 10 and gives a feeling of operation when the steering handle 10 is steered at a large steering angle. Because. Further, the second energization amount I is near “0” of the steering angle θ of the steering wheel.₁₂Is slightly increased in order to increase the neutral stability of the steering wheel 10.
[0036]
The third map shows the third energization amount I with respect to the vehicle speed V.₁₃The third energization amount I₁₃As shown in FIG. 10, when the vehicle speed V is “0”, it becomes a positive predetermined value and gradually increases as the vehicle speed V increases. This is because energization control to the coil 44 described later enables the steering handle 10 to be easily rotated when the steering handle 10 is turned off when the vehicle is traveling at a low vehicle speed, and the steering handle 10 is rotated when the vehicle is traveling at a high speed. This is to give a sense of stability to the dynamic operation.
[0037]
After the process of step S37, the total energization amount I for the fluid reaction force I is obtained by executing the following equation 1 in step S38._TenCalculate
[0038]
[Expression 1]
I_Ten= (I₁₁+ I₁₂+ I₁₃) ・ RT
[0039]
In addition, instead of the above formula 1, the following formula 2 is used to calculate the total energization amount I_TenMay be calculated.
[0040]
[Expression 2]
I_Ten= (I₁₁+ I₁₂) ・ I₁₃・ RT
[0041]
In step S39, the total energization amount I_TenIs passed through the coil 44. As a result, the iron core 43 is magnetized, and the magnetic lines of force output from one end of the iron core 43 are input to the other end of the iron core 43, so that a magnetic field is formed in the internal space R <b> 1 of the housing 41. Due to the formation of this magnetic field, the Bingham fluid mixed with the handle magnetic powder hardly moves, that is, the viscosity of the Bingham fluid increases. The viscosity increases as the magnetic field increases, and a large reaction torque is applied to the rotation of the rotor 42. Therefore, the total energization amount I to the coil 44 is increased._TenAs the value increases, a larger reaction force torque is applied to the turning operation of the steering handle 10.
[0042]
Next, referring to the first to third maps for the motor reaction force in step S40, the first to third energizations for the motor reaction force according to the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V. Amount I_{twenty one}, I_{twenty two}, I_{twenty three}Respectively. These first to third maps are prepared in advance in the memory of the electronic control unit 31.
[0043]
The first map shows the first energization amount I with respect to the steering wheel steering speed θv._{twenty one}The first energization amount I_{twenty one}As shown by the solid line in FIG. 11, when the absolute value | θv | of the steering wheel steering speed θv is within a predetermined range, the absolute value | θv | is proportional to the steering wheel steering speed θv with a predetermined inclination. When the predetermined range is exceeded, the steering wheel speed changes proportionally with respect to the steering wheel steering speed θv with an inclination larger than the inclination. This is because energization control for the electric motor 12, which will be described later, enables the steering handle 10 to be turned easily when the steering handle 10 starts to operate, and provides a sense of stability when the steering handle 10 is quickly turned. It is. In this case, the first energization amount I_{twenty one}The positive and negative signs represent the rotational direction of the electric motor 12 and are determined so that a reaction torque is applied to the rotation of the steering handle 10.
[0044]
The second map shows the second energization amount I with respect to the steering angle θ._{twenty two}The second energization amount I_{twenty two}As shown in FIG. 12, when the absolute value | θ | of the steering wheel steering angle θ is within a predetermined range, it is kept at “0”, and when the absolute value | θv | exceeds the predetermined range, the steering wheel steering angle θ If the steering angle θ is positive, it gradually increases as the steering wheel steering angle θ increases. If the steering wheel steering angle θ is negative, it gradually decreases as the steering wheel steering angle θ decreases. This is because energization control to the electric motor 12 described later enables the steering handle 10 to be easily turned when starting operation from the neutral position of the steering handle 10, and gives a feeling of operation when steering the steering wheel 10 at a large steering angle. It is to do. In this case, the second energization amount I_{twenty two}The positive and negative signs represent the rotational direction of the electric motor 12 and are determined so that torque for returning the steering handle 10 to the neutral position is applied to the steering handle 10.
[0045]
The third map shows the third energization amount I with respect to the vehicle speed V._{twenty three}The third energization amount I_{twenty three}As shown in FIG. 13, when the vehicle speed V is “0”, it becomes a positive predetermined value, and gradually increases as the vehicle speed V increases. This is because energization control to the electric motor 12 described later enables the steering handle 10 to be easily rotated when the steering handle 10 is turned off when the vehicle is traveling at a low vehicle speed, and the steering handle 10 is operated when the vehicle is traveling at a high speed. This is to give a sense of stability to the turning operation.
[0046]
After the process of step S40, the total energization amount I for the motor reaction force I is obtained by executing the following equation 3 in step S41.₂₀Calculate
[0047]
[Equation 3]
I₂₀= (I_{twenty one}+ I_{twenty two}) ・ I_{twenty three}・ (1-RT)
[0048]
In addition, instead of the above formula 3, the total energization amount I is obtained by executing the calculation of the following formula 4.₂₀May be calculated. In this case, sig [I_{twenty one}+ I_{twenty two}] Is I_{twenty one}+ I_{twenty two}Is "0" when I is "0" and I_{twenty one}+ I_{twenty two}Is "1" when is positive and I_{twenty one}+ I_{twenty two}This is a function that becomes “−1” when is negative.
[0049]
[Expression 4]
I₂₀= (I_{twenty one}+ I_{twenty two}+ Sig [I_{twenty one}+ I_{twenty two}] ・ I_{twenty three}) ・ (1-RT)
[0050]
In step S42, the total energization amount I₂₀Is passed through the electric motor 12, and the execution of the first reaction force control routine is terminated in step S43. By this energization control, the electric motor 12 applies torque having a magnitude corresponding to the energization amount to the steering handle 10 via the speed reducer 13 and the rotating shaft 11 in the rotation direction corresponding to the energization direction. However, in the modified example of FIG. 3, the electric motor 12 directly applies the torque to the steering handle 10 via the rotating shaft 11. In this case, as described above, the first energization amount I_{twenty one}The direction of the current flowing through the electric motor 12 is determined so as to apply a reaction torque to the rotation of the steering handle 10, and the second energization amount I_{twenty two}Thus, the direction of the current flowing through the electric motor 12 is determined so that a torque for returning the steering handle 10 to the neutral position acts. Therefore, the total energization amount I₂₀As becomes larger, a larger reaction force torque is applied to the steering operation and the steering operation of the steering handle 10.
[0051]
As described above, according to the embodiment and the modification thereof, both the motor reaction force by the electric motor 12 and the fluid reaction force by the fluid reaction force generator 14 are applied to the turning operation of the steering handle 10 by the driver. Will be. In particular, as the fluid reaction force generating device 14, the housing 41 is filled with a Bingham fluid as a non-Newtonian fluid, and the Bingham fluid is a friction reaction force that changes greatly in a nonlinear manner when the rotor 42 changes from a stopped state to a rotating state. Is applied to the rotor 42. Accordingly, since a certain amount of friction reaction force can be applied to the steering handle 10 that rotates at a very low speed, the stability at the neutral position of the steering handle 10 is improved, and the straight running stability of the vehicle is improved. .
[0052]
In the above-described embodiment and its modification, the Bingham fluid is mixed with magnetic powder to give a magnetic viscosity, and a magnetic field generator comprising an iron core 43 and a coil 44 is provided in the housing 41 to provide a magnetic field in the Bingham fluid. To form. Therefore, the viscosity of the Bingham fluid increases and a larger steering reaction force can be obtained.
[0053]
Further, the rotor 42 is provided with fins 42a as stirring means so that the Bingham fluid mixed with the magnetic powder is stirred. Since the magnetic powder is agitated and does not settle with the rotation of the rotor 42, the viscosity of the Bingham fluid by the magnetic powder can always be kept high, and the reaction force generation function by the magnetic powder can always be maintained. Further, since the fin 42a protrudes from the outer peripheral surface of the rotor 42, a greater steering reaction force can be obtained by the resistance of the fin 42a to the Bingham fluid. Furthermore, by changing the inclination and shape of the fins, the resistance to the Bingham fluid can be variously changed, and an appropriate steering reaction force can be applied.
[0054]
Further, the electronic control unit 31 controls the energization mode to the coil 44 in accordance with the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V by the processing of steps S37 to S39 in FIG. Accordingly, as shown in FIG. 14, the reaction force against the steering operation of the steering handle 10 can be variably controlled in accordance with the driving state and the motion state of the vehicle. A reaction force can be applied.
[0055]
Further, in the above embodiment and the modification, the electric motor 12 is provided in addition to the fluid reaction force generator 14, and both of them apply a reaction force to the turning operation of the steering handle 10. Therefore, a larger reaction force can be applied to the rotation of the steering handle 10, and at the same time, a reaction force application control with a high degree of freedom can be performed by controlling the electric motor. In addition, since two actuators are used for applying the steering reaction force, the fluid reaction force generator 14 and the electric motor 12 as the actuators can be made compact.
[0056]
Furthermore, the application of the reaction force by the fluid reaction force generator 14 makes it possible to apply a favorable steering reaction force having hysteresis characteristics with respect to the rotation of the steering handle 10. That is, in the reaction force application control by the electric motor 12, only a reaction force torque that changes in proportion to the steering angle θ is obtained as shown in FIG. In this case, the steering wheel steering speed θv is neglected for simplification, but even when the steering wheel steering speed θv is taken into consideration, when the steering handle 10 in the neutral position is started to rotate, the reaction torque is first When it is “0” and the steering wheel 10 is near neutral, the reaction torque is extremely small. On the other hand, the reaction torque due to the Bingham fluid exhibits a change characteristic as shown in FIG. 15B with respect to the steering speed θv of the steering wheel. That is, even when the steering handle 10 in the neutral position is started to rotate, a somewhat large reaction force torque is applied. The combined torque of the reaction torque generated by these electric motors 12 and the reaction torque generated by the fluid reaction force generator 14 is as shown in FIG. 15C in response to the operation of the steering handle 10 near the neutral position. However, the characteristic has a large reaction torque, that is, a characteristic having hysteresis. Therefore, according to the above-described embodiment, an accurate reaction force can be applied to the steering operation of the steering handle 10, and particularly the steering operation of the steering handle 10 in the vicinity of the neutral position can be stabilized.
[0057]
The reaction force sharing of these two actuators is controlled by steps S32 to S36. Specifically, when the steering handle 10 is cut, control is performed so that the reaction force sharing by the fluid reaction force generator 14 is increased. Since the fluid reaction force generator 14 applies a frictional force to the rotation of the rotor 42, the fluid reaction force generator 14 is good at applying a reaction force to the steering handle 10 that is rotated at a high speed. Therefore, a large reaction force can be applied when the steering handle 10 that requires a large reaction force is cut, and the electric motor 12 can be downsized, power consumption can be saved, and the amount of heat generated by the electric motor 12 can be reduced.
[0058]
In addition, when the steering handle 10 is being held near the neutral position, the reaction force sharing by the fluid reaction force generator 14 is controlled to be larger than in other cases. In the first place, the electric motor 12 can generate torque only at low efficiency at low speeds. In contrast, the fluid reaction force generator particularly has a reaction force (shearing force) in the Bingham fluid itself. The reaction force can be generated with high efficiency even when the rotor 42 rotates at a low speed. As a result, a sufficient reaction force is obtained by the fluid reaction force generator 14 with respect to the steering in the vicinity of the neutral position of the steering handle 10, and the electric motor 12 can be reduced in size, power consumption can be reduced, and the electric motor 12 can be saved. The amount of generated heat can be reduced.
[0059]
Next, the case where the fluid reaction force generator 14 is normal but an abnormality has occurred in the electric motor 12 will be described. In this case, “Yes” is determined in step S14 of FIG. 4, “No” is determined in step S15, and the process proceeds to step S17. In step S17, the driver is notified that an abnormality has occurred in the electric motor 12 by operating a lamp, a sound generator, etc. (not shown).
[0060]
After the process of step S17, a second reaction force control routine is executed in step S18. The details of the second reaction force control routine are shown in FIG. 6, and its execution is started in step S50. After the start of execution, the steering wheel steering speed θv is calculated in step S51 in the same manner as in step S31 of FIG. 5 described above. In step S52, the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V are set in the same manner as in step S37 of FIG. Accordingly, first to third energization amounts I for fluid reaction force₁₁, I₁₂, I₁₃Respectively. After the process of step S52, the total energization amount I for the fluid reaction force I is obtained by executing the following equation 5 in step S53._TenCalculate
[0061]
[Equation 5]
I_Ten= (I₁₁+ I₁₂+ I₁₃) ・ K₁
[0062]
Instead of the above formula 5, the following formula 6 is used to calculate the total energization amount I_TenMay be calculated.
[0063]
[Formula 6]
I_Ten= (I₁₁+ I₁₂) ・ I₁₃・ K₁
[0064]
Coefficient K in the above formulas 5₁Is a predetermined value that is at least larger than the reaction force distribution ratio RT (predetermined values ra1, ra2 or rb) of Equations 1 and 2 above. In step S54, the total energization amount I_TenIs passed through the coil 44, and the execution of the second reaction force control routine is terminated in step S55. As a result, even if an abnormality occurs in the electric motor 12 and the application of the steering reaction force by the electric motor 12 becomes impossible, the application of the steering reaction force by the fluid reaction force generation device 14 is possible. The steering handle 10 can be turned while feeling an appropriate steering reaction force. In this case, the coefficient K₁Since the electric motor 12 and the fluid reaction force generator 14 are set larger than when the electric motor 12 and the fluid reaction force generator 14 are normal, there is no problem even if the steering reaction force by the electric motor 12 is not obtained.
[0065]
Further, in the present embodiment, the first to third of the same characteristics both in the case of reaction force generation by both the electric motor 12 and the fluid reaction force generator 14 and in the case of reaction force generation by only the fluid reaction force generator 14. Energization amount I₁₁, I₁₂, I₁₃Was used. However, instead of this, when the reaction force is generated only by the fluid reaction force generator 14, the first to first characteristics having different characteristics from the case of reaction force generation by both the electric motor 12 and the fluid reaction force generator 14 are used. 3 energization amount I₁₁, I₁₂, I₁₃May be used. For example, if the reaction force is applied to the fluid reaction force generator 14 only after the steering handle 10 is rotated, that is, the rotor 42 rotates, and the steering handle 10 is stationary at a fixed rotational position, the reaction force ( (Steering reaction force) does not occur. Actually, even if the steering handle 10 is being held, there is a slight change in the steering angle θ of the steering wheel, so that the steering reaction force acts as if it were working. However, after the steering handle 10 is held at a desired rotational position, when the steering handle 10 is further turned, the steering reaction force becomes insufficient, and when the steering handle 10 is turned back, the steering reaction force becomes excessive. .
[0066]
In order to improve such a point, the second energization amount I₁₂As shown by the broken line in FIG. 9, when the steering handle 10 is cut, the second energization amount I having the characteristic indicated by the broken line on the upper side of FIG.₁₂When the steering wheel 10 is switched back, the second energization amount I having the characteristic indicated by the broken line on the lower side of FIG.₁₂Should be used. In this case, the second energization amount I with respect to the steering angle θ of the steering wheel according to the both broken line characteristics of FIG.₁₂Are prepared in advance and stored in the memory of the electronic control unit 31. In step S52 in FIG. 6, if the time differential value d | θ | / dt of the absolute value | θ | of the steering wheel steering angle θ is positive, that is, if the absolute value | θ | The second energization amount I according to the broken line characteristic on the upper side of FIG.₁₂Is determined according to the steering angle θ. If the time differential value d | θ | dt is negative, that is, if the absolute value | θ | is in a decreasing tendency, the second energization amount I according to the broken line characteristic on the lower side of FIG.₁₂May be determined according to the steering angle θ. Other operations are the same as those described above.
[0067]
In addition, when the steering reaction force is generated only by the fluid reaction force generator 14 due to the abnormality of the electric motor 12 as described above, the load of the fluid reaction force generator 14 may be excessively large. Therefore, immediately after the abnormality of the electric motor 12, in order to avoid a sudden change in the steering reaction force before the abnormality, the amount of energization to the fluid reaction force generator 14 is increased. The amount of power supplied to the force generator 14 may be reduced. In this case, the temperature of the fluid reaction force generator 14, the current flowing through the fluid reaction force generator 14 (coil 44), and the like are measured, so long as the load on the fluid reaction generator 14 does not become excessive, the fluid reaction force generator The energization amount to 14 is kept large, and when the burden of the fluid reaction generator 14 becomes excessive, the energization amount to the fluid reaction force generator 14 is decreased.
[0068]
Next, a case where the electric motor 12 is normal but an abnormality has occurred in the fluid reaction force generator 14 will be described. In this case, “No” is determined in step S14 of FIG. 4, “Yes” is determined in step S19, and the process proceeds to step S20. In step S20, the operator is notified that an abnormality has occurred in the fluid reaction force generator 14 by operating a lamp, a sound generator, etc. (not shown).
[0069]
After the process of step S20, a third reaction force control routine is executed in step S21. The details of the third reaction force control routine are shown in FIG. 7, and the execution is started in step S60. After the start of execution, the steering wheel steering speed θv is calculated in step S61 in the same manner as in step S31 of FIG. 5 described above. In step S62, the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V are set in the same manner as in step S40 in FIG. Accordingly, the first to third energization amounts I for the motor reaction force_{twenty one}, I_{twenty two}, I_{twenty three}Respectively. After the process of step S62, the total energization amount I for the motor reaction force I is obtained by executing the following equation 7 in step S63.₂₀Calculate
[0070]
[Expression 7]
I₂₀= (I_{twenty one}+ I_{twenty two}) ・ I_{twenty three}・ K₂
[0071]
In place of the above formula 7, the following formula 8 is used to calculate the total energization amount I₂₀May be calculated.
[0072]
[Equation 8]
I₂₀= (I_{twenty one}+ I_{twenty two}+ Sig [I_{twenty one}+ I_{twenty two}] ・ I_{twenty three}) ・ (1-RT)
[0073]
The coefficient K of the above 7 and 8₂Is a predetermined value that is at least larger than the reaction force distribution ratio 1-RT (predetermined value 1-ra1, 1-ra2 or 1-rb) of Equations 3 and 4 above. In addition, the function sig [I_{twenty one}+ I_{twenty two}] Is the same as in the case of Equation 4 described above. In step S64, the total energization amount I₂₀Is passed through the electric motor 12, and the execution of the third reaction force control routine is terminated in step S65. As a result, even if an abnormality occurs in the fluid reaction force generator 14 and the application of the steering reaction force by the fluid reaction force generator 14 becomes impossible, the steering reaction force can be applied by the electric motor 12. The driver can turn the steering handle 10 while feeling an appropriate steering reaction force. In this case, the coefficient K₂Is set larger than when the electric motor 12 and the fluid reaction force generator 14 are normal, there is no problem even if the steering reaction force by the fluid reaction force generator 14 cannot be obtained.
[0074]
Further, in the present embodiment, the first to third energization amounts I having the same characteristics are generated both in the case of reaction force generation by both the electric motor 12 and the fluid reaction force generator 14 and in the case of reaction force generation by only the electric motor 12._{twenty one}, I_{twenty two}, I_{twenty three}Was used. However, instead of this, when the reaction force is generated only by the electric motor 12, the first to third energization amounts having different characteristics from the case of the reaction force generation by both the electric motor 12 and the fluid reaction force generator 14. I_{twenty one}, I_{twenty two}, I_{twenty three}May be used. For example, the fluid reaction force generator 14 generates a large steering reaction force when the steering handle 10 rotates, particularly when the rotational speed increases. Therefore, the steering reaction force by the electric motor 12 with respect to the rotation of the steering handle 10 becomes insufficient.
[0075]
In order to improve such a point, the first energization amount I_{twenty one}As shown in FIG._{twenty one}Should be used. In this case, the first energization amount I with respect to the steering wheel steering speed θv according to the broken line characteristics of FIG._{twenty one}Are prepared in advance and stored in the memory of the electronic control unit 31. Then, in the process of step S62 of FIG. 7, the first energization amount I according to the broken line characteristic of FIG._{twenty one}Is preferably determined according to the steering speed θv. Other operations are the same as those described above.
[0076]
In addition, when the steering reaction force is generated only by the electric motor 12 due to the abnormality of the fluid reaction force generator 14 as described above, the load on the electric motor 12 may be excessively large. Therefore, immediately after the abnormality of the fluid reaction force generating device 14, in order to avoid a sudden change in the steering reaction force before the abnormality, the amount of current supplied to the electric motor 12 is increased. The amount of current supplied to 12 may be relaxed. In this case, the temperature of the electric motor 12, the current flowing through the electric motor 12, and the like are measured, and unless the load on the electric motor 12 becomes excessive, the amount of current supplied to the electric motor 12 is kept large, and the load on the electric motor 12 is reduced. When it becomes excessive, the energization amount to the electric motor 12 is decreased.
[0077]
Next, a modified example of the fluid reaction force generator 14 configured as described above will be described. In the first modification, as shown in FIG. 16, a permanent magnet 46 is interposed in each iron core 43. Other configurations are the same as those in the above embodiment. According to this, the magnetic field lines generated from the permanent magnet 46 form a magnetic field in the Bingham fluid mixed with the magnetic powder through the iron core 43. Therefore, if the electronic control unit 31 controls the energization of the coil 44 so that the direction of the magnetic lines of force formed by the permanent magnet 46 and the direction of the magnetic lines of force formed by the coil 44 coincide, It is possible to form a magnetic field in which the magnetic field lines 44 are superimposed in the Bingham fluid, and to increase the variable range of the steering reaction force by the Bingham fluid. Further, the amount of energization to the coil 44 can be reduced by the processing of step S39 of FIG. 5 and step S54 of FIG. 6 of the above embodiment, and the electric motor 12 by the processing of step S42 of FIG. 5 and step S64 of FIG. It is also possible to reduce the amount of electricity applied to the. Furthermore, even when the energization control system for the coil 44 is abnormal, the steering reaction force using the magnetic powder by the permanent magnet 46 of the fluid reaction force generator 14 can be secured.
[0078]
Further, the electronic control unit 31 may control the energization of the coil 44 so that the direction of the magnetic lines of force formed by the permanent magnet 46 and the direction of the magnetic lines of force formed by the coil 44 are opposite. In this case, in the control of the steering reaction force by the coil 44, the magnetic field lines by the permanent magnet 46 are canceled by the magnetic field lines by the coil 44, and the energization amount by the coil 44 is determined according to the characteristics shown in FIGS. It is good to decide. Therefore, it is necessary to increase the energization amount to the coil 44 by the processing of step S42 in FIG. 5 and step S54 in FIG. 6 as compared with the above embodiment. According to this, even when the energization control system of the coil 44 is abnormal, the reaction force by the permanent magnet 46 can be secured, and at the same time, the reaction force is prevented from being drastically reduced as compared with the normal operation of the energization control system of the coil 44. it can.
[0079]
Next, a second modification of the fluid reaction force generator 14 configured as described above will be described. FIG. 17 shows a fluid reaction force generator 50 according to the second modification in a longitudinal sectional view. The fluid reaction force generating device 50 also includes a housing 51 made of a cylindrical and non-magnetic material that allows the rotary shaft 11 to rotate in the axial direction at the center position of the upper surface and the lower surface. The housing 51 accommodates a columnar rotor 52 fixed on the outer peripheral surface of the rotary shaft 11. Further, a seal member (not shown) is interposed between the housing 51 and the rotary shaft 11, and the internal space R <b> 1 formed between the outer surface of the rotary shaft 11 and the rotor 52 and the inner surface of the housing 51 is sealed. Yes.
[0080]
This internal space R1 is filled with a Bingham fluid mixed with magnetic powder, as in the above embodiment. This Bingham fluid has the same function as the above embodiment. Also in this case, although the internal space R1 is drawn widely in FIG. 17, in order to give a large frictional reaction force to the rotation of the rotor 52, the internal space R1 is actually extremely narrow. As shown in FIGS. 17 and 18, a groove 52 a is formed in the rotor 52 along the circumferential direction, leaving a part. On the other hand, in the housing 51, a plurality of electromagnets molded with a resin 53 and wound with a coil 55 around a cylindrical iron core 54 are embedded at appropriate locations in the circumferential direction. The magnetic pole surface of the electromagnet composed of the iron core 54 and the coil 55 faces the outer peripheral surface (groove 52 a) of the rotor 52.
[0081]
Also in the fluid reaction force generator 50 according to the second modified example configured as described above, energization control is performed by the electronic control unit 31 as in the above embodiment. Therefore, also in the vehicle steering apparatus using the fluid reaction force generating apparatus 50 according to the second modification, the reaction force similar to that in the above embodiment is caused by the friction between the Bingham fluid mixed with magnetic powder and the rotor 52. It is given to the turning operation of the steering handle 10. Further, since the outer peripheral surface of the rotor 52 that does not form the groove 52a forms a protrusion with respect to the bottom surface of the groove 52a, the Bingham fluid is agitated with the rotation of the rotor 52, and the precipitation of magnetic powder is avoided. be able to. Therefore, also in this case, an accurate steering reaction force is always maintained with respect to the rotation of the steering handle 10.
[0082]
Further, in this second modification, the non-formed portion of the groove 52a on the outer peripheral surface of the rotor 52 corresponds to the step of the present invention, and between the outer peripheral surface of the rotor 52 and the inner peripheral surface of the housing 51. The passage area is different in a part of the circumferential direction. On the other hand, when the coil 55 is energized, the magnetic powder mixed in the Bingham fluid is concentrated at a position facing the magnetic pole surface of the iron core 54. In this case, when the non-formed portion of the groove 52a is close to the position near the iron core 54, the non-formed portion of the groove 52a and the concentrated magnetic powder realize an orifice function for the Bingham fluid. Therefore, according to this, a larger steering reaction force can be obtained compared to the case of the above embodiment.
[0083]
In such a second modification, only one non-formed portion of the groove 52 a is provided on the outer peripheral surface of the rotor 52, but a plurality of non-formed portions of the groove 52 a are provided on the outer peripheral surface of the rotor 52. You may do it. Further, regarding the number of electromagnets composed of the iron core 54 and the coil 55, an appropriate number may be provided as necessary.
[0084]
Furthermore, in the fluid reaction force generator 50 according to the second modification, a permanent magnet may be provided in addition to the coil 55, as in the fluid reaction force generator 14 according to the first modification. In this case, the permanent magnet may be disposed in the iron core 54 or arranged in series with the iron core 54 so as to coincide with the traveling direction of the magnetic force lines by the coil 55, or at an appropriate position along the circumferential direction of the housing 51. Therefore, it may be arranged at a position different from the iron core 54 and the coil 55 in the circumferential direction.
[0085]
Next, the fluid reaction force generator 60 according to the third modification will be described. FIG. 19 shows the fluid reaction force generator 60 according to the third modification in a longitudinal sectional view. This fluid reaction force generation device 60 is a part of the fluid reaction force generation device 50 according to the second modification, and is formed in a cylindrical housing 61 filled with a Bingham fluid mixed with magnetic powder. A first rotor 62 and a second rotor 63 fixed to the rotating shaft 11 are accommodated. As shown in FIGS. 19 and 20A, the first rotor 62 is formed in a columnar shape having the same radius over the entire circumference. As shown in FIGS. 19 and 20B, the second rotor 63 is formed in a substantially cylindrical shape having a small-diameter portion 63c and a large-diameter portion 63d having different radii with respect to the steps 63a and 63b.
[0086]
On the other hand, a plurality of first and second electromagnets each having a first and second coils 67 and 68 wound around cylindrical first and second iron cores 65 and 66 are molded in the housing 51 by resin 64. It is embedded at appropriate locations in the direction. The magnetic pole surface of the first electromagnet including the first iron core 65 and the first coil 67 is opposed to the outer peripheral surface of the first rotor 62. A pair of second electromagnet magnetic pole surfaces including the second iron core 66 and the second coil 68 are opposed to the outer peripheral surface of the second rotor 62.
[0087]
In the fluid reaction force generator 60 according to the third modified example configured as described above, the first and second coils 67 and 68 are energized and controlled by the electronic control unit 31 as in the above embodiment. Therefore, also in the vehicle steering apparatus using the fluid reaction force generator 50 according to the third modification, the above-described implementation is performed due to the friction between the Bingham fluid mixed with magnetic powder and the first and second rotors 62 and 63. A reaction force similar to that of the form is applied to the turning operation of the steering handle 10. In the third modification, since the first and second rotors 62 and 63 are provided as the rotor that frictionally acts with the Bingham fluid, a larger reaction force can be obtained. Further, due to the action of the steps 63a and 63b of the second rotor 63, the Bingham fluid is agitated as the rotor 52 rotates, so that the precipitation of the magnetic powder can be avoided. Therefore, also in this case, an accurate steering reaction force is always maintained with respect to the rotation of the steering handle 10.
[0088]
Further, in the third modified example, as in the second modified example, on the outer periphery of the second rotor 63, the inner periphery of the housing 61 is formed by the small diameter portion 63c and the large diameter portion 63d with the steps 63a and 63b as boundaries. The passage area between the surfaces is different in a part of the circumferential direction. Also in this case, the magnetic powder mixed in the Bingham fluid is concentrated at a position facing the magnetic pole surface of the second iron core 66 by energization of the coil 68. In this case, in a state where the steps 63a and 63b of the second rotor 63 are close to the magnetic pole surface of the second iron core 66, the steps 63a and 63b of the second rotor 63 and the concentrated magnetic powder prevent the Bingham fluid. Orifice function is realized. Therefore, according to this, similarly to the fluid reaction force generator 50 according to the modified example, it is possible to obtain a larger steering reaction force than in the case of the above embodiment.
[0089]
In such a third modification, the two stepped portions 63a and 63b are provided on the outer peripheral surface of the second rotor 63, but more steps may be provided. Further, the first rotor 62 may be provided with a step. Further, regarding the number of first electromagnets composed of the first iron core 65 and the first coil 67 and the number of second electromagnets composed of the second iron core 66 and the second coil 68, an appropriate number is provided as necessary. You can do it. Further, in the fluid reaction force generator 60 according to the third modification, a permanent magnet may be provided in addition to the first and second coils 67 and 68, as in the case of the second modification. .
[0090]
Further, when a plurality of sets of coils 67 and 68 are provided as in the third modification, the process of step S39 in FIG. 5 in the above embodiment is modified as steps S70 to S73 in FIG. You can also. In step S70, the steering limit of the left and right front wheels 20a, 20b (in other words, the steering limit of the steering handle 10) is determined. Determined.
[0091]
In the determination of the turning limit, the absolute value | ψ | of the front wheel turning angle ψ input in step S11 in FIG. 4 is a predetermined value corresponding to the left and right maximum turning angle of the left and right front wheels 20a and 20b. When exceeded, the steering limit is judged. Alternatively, when the absolute value | θ | of the steering wheel steering angle θ input in step S11 of FIG. 4 exceeds a predetermined value corresponding to the maximum steering angle to the left and right of the steering wheel 10, the turning limit is reached. May be determined. In determining the turning delay, the absolute value | ψ of the difference ψ−ψ * between the front wheel turning angle ψ input in step S11 of FIG. 4 and the target turning angle ψ * calculated in step S12 of FIG. When -ψ * | exceeds a predetermined value, the steering delay is determined.
[0092]
If the turning limit has not been reached and no turning delay has occurred, “No” is determined in steps S70 and S71, and the total calculated by the processing in step S38 in step S72. Energization amount I_TenAccordingly, only the first coil 67 is energized and controlled. Thereby, in this case, the steering reaction force by the fluid reaction force generator 60 similar to that in the above embodiment is applied to the turning operation of the steering handle 10. On the other hand, if the steering limit has been reached or a steering delay has occurred, “Yes” is determined in either step S70 or S71, and the calculation in step S38 is performed in step S73. Total energization I_TenAccordingly, the energization of both the first and second coils 67 and 68 is controlled. Thereby, in this case, a larger steering reaction force than that described above is applied to the turning operation of the steering handle 10. In particular, an extremely large steering reaction force is applied due to the orifice effect described above.
[0093]
As a result, according to the control of this modification, when the left and right front wheels 20a and 20b are steered to the limit by turning the steering handle 10, the reaction force against the turning operation of the steering handle 10 is caused by the fluid reaction force generator 60. Since the increase control is very increased, the vicinity of the steering wheel (the left and right front wheels 20a, 20b) in the conventional vehicle is accurately simulated, and the steering feeling is improved. Further, even when a steering delay occurs in the left and right front wheels 20a, 20b, the reaction force against the turning operation of the steering handle 10 is greatly increased and controlled by the fluid reaction force generator 60. The wheel turning delay is accurately simulated, and the steering feeling is improved.
[0094]
In the above description, instead of the processing in step S39 (FIG. 5) of the first reaction force control routine performed in parallel with the reaction force application by the electric motor 12, the control including steps S70 to S73 in FIG. 21 is performed. I made it. However, this control can also be applied to the second counter-control routine that is executed when an abnormality occurs in the electric motor 12. In this case, what is necessary is just to replace the process of FIG.6 S54 with the process of said step S70-S73.
[0095]
Next, the fluid reaction force generator 70 according to the fourth modification will be described. FIG. 22 shows the fluid reaction force generator 70 according to the fourth modification in a longitudinal sectional view. This fluid reaction force generator 70 is a modified part of the fluid reaction force generator 50 according to the second modification, and in a cylindrical housing 71 filled with a Bingham fluid mixed with magnetic powder, The rotor 72 fixed to the rotating shaft 11 is accommodated. As shown in FIGS. 22 and 23, the rotor 72 is provided with a step 72a at a part of the outer peripheral surface with the radius gradually changed along the circumferential direction.
[0096]
On the other hand, in the housing 71, as in the case of the second modified example, a plurality of first electromagnets molded with resin 73 and wound with a first coil 75 around a cylindrical first iron core 74 are provided at appropriate locations in the circumferential direction. And is opposed to the outer peripheral surface of the rotor 72. In addition to the first electromagnet, a plurality of second electromagnets molded with resin 76 and having a second coil 78 wound around a cylindrical second iron core 77 on the upper surface portion and the lower surface portion of the housing 71 as appropriate in the circumferential direction. It is embedded at a location and faces the upper and lower surfaces of the rotor 72.
[0097]
In the fluid reaction force generator 70 according to the fourth modified example configured as described above, the first and second coils 75 and 78 are energized and controlled by the electronic control unit 31 as in the above embodiment. Therefore, also in the vehicle steering apparatus using the fluid reaction force generation apparatus 70 according to the fourth modification, the reaction force similar to that in the above embodiment is generated due to the friction between the Bingham fluid mixed with magnetic powder and the rotor 72. It is given to the turning operation of the steering handle 10. Further, due to the action of the step 72a of the rotor 72, the Bingham fluid is agitated with the rotation of the rotor 72, and precipitation of the magnetic powder can be avoided. Therefore, also in this case, an accurate steering reaction force is always maintained with respect to the rotation of the steering handle 10.
[0098]
Further, in the fourth modified example, as in the second and third modified examples, the passage area between the inner peripheral surface of the housing 61 is partially set in the circumferential direction by the step 72a on the outer periphery of the rotor 72. Is different. Also in this case, the magnetic powder mixed in the Bingham fluid is concentrated at a position facing the magnetic pole surface of the first iron core 74 by energizing the first coil 75. In this case, when the step 72a of the rotor 72 is close to the position near the first iron core 74, an orifice function for the Bingham fluid is realized by the step 72a of the rotor 72 and the concentrated magnetic powder. Therefore, a large steering reaction force can be obtained also by this.
[0099]
Also in the fourth modified example, only one step 72a is provided on the outer peripheral surface of the rotor 72, but a plurality of steps may be provided. In addition, regarding the number of first electromagnets composed of the first iron core 74 and the first coil 75 and the number of second electromagnets composed of the second iron core 77 and the second coil 78, an appropriate number is provided as necessary. You can do it. Further, in the fluid reaction force generator 70 according to the fourth modified example, a permanent magnet is provided in addition to the first and second coils 75 and 78, as in the case of the second and third modified examples. May be.
[0100]
Also in this fourth modification, the control of the turning limit and the turning delay can be accurately performed by applying the control of steps S70 to S73 of FIG. However, in this case, since the steering reaction force due to the energization of the first coil 75 is larger than the steering reaction force due to the energization of the second coil 78, step S72 in a state that is not at the turning limit and has no turning delay. During the energization control, it is preferable that only the second coil 78 be energized. And at the time of the energization control of step S73 in the state which is a steering limit or the steering delay generate | occur | produced, it is good to carry out energization control of both the 1st and 2nd coils 75 and 78.
[0101]
The embodiments of the present invention and various modifications thereof have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention. is there.
[0102]
For example, in the above-described embodiment and various modifications, the magnitude of the steering reaction force is controlled in accordance with the steering wheel steering speed θv, the steering wheel steering angle θ, and the vehicle speed V. In addition, the steering reaction force may be controlled in accordance with the steering steering acceleration, the steering reaction force of the steered wheels, the road surface friction coefficient (vehicle environment information), the yaw rate, and the like.
[0103]
When the steering reaction force is controlled according to the steering speed of the steering wheel, the steering wheel steering speed θv calculated by the processes in steps S31, S51, and S61 of the reaction force control routines of FIGS. The steering steering acceleration is calculated by further time differentiation by the program processing of the unit 31. Then, as the absolute value of the steering acceleration of the steering wheel increases, control is performed to increase one or both of the reaction force by the electric motor 12 and the reaction force by the fluid reaction force generators 14, 50, 60, 70, The steering operation of the steering handle 10 may be stabilized.
[0104]
Further, when the steering reaction force is controlled in accordance with the steering reaction force of the steered wheels, the steering for detecting the steering reaction force (steering torque) on the rotating shaft 25 as shown by the broken line in FIGS. 1 and 3. The reaction force sensor 35 is assembled. Then, as the detected turning reaction force increases, control is performed to increase either one or both of the reaction force by the electric motor 12 and the reaction force by the fluid reaction force generators 14, 50, 60, 70, The steered state of the left and right front wheels 20a, 20b may be reflected in the operation of the steering handle 10.
[0105]
When the steering reaction force is controlled according to the road surface friction coefficient or the yaw rate, a road surface friction coefficient detection device or a detection device such as a yaw rate sensor detects the friction coefficient of the steering road surface as indicated by a broken line in FIGS. 36 is provided so that the road friction coefficient or yaw rate can be detected. Then, as the detected road surface friction coefficient increases, control is performed so as to increase one or both of the reaction force by the electric motor 12 and the reaction force by the fluid reaction force generators 14, 50, 60, and 70, and the traveling road surface This state may be reflected in the operation of the steering wheel 10. In addition, as the detected yaw rate increases, control is performed so that either one or both of the reaction force by the electric motor 12 and the reaction force by the fluid reaction force generators 14, 50, 60, and 70 are increased. It is good to stabilize the steering operation.
[0106]
In the above-described embodiment and various modifications, examples in which the present invention is applied to a steer-by-wire vehicle steering apparatus have been described. However, the present invention can also be applied to a vehicle steering apparatus in which the steering handle 10 and the left and right front wheels 20a and 20b as steering wheels are mechanically connected. This also makes it possible to control a complex steering reaction force, which was difficult with only a hydraulic or electric motor, and to obtain a steering stability and a good steering feeling of the vehicle.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vehicle steering apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the fluid reaction force generator of FIG.
FIG. 3 is a schematic view of a modified example of the vehicle steering apparatus.
FIG. 4 is a flowchart of a steering control program executed by the electronic control unit of FIG.
FIG. 5 is a detailed flowchart of a first reaction force control routine of FIG.
6 is a detailed flowchart of a second reaction force control routine of FIG.
FIG. 7 is a detailed flowchart of a third reaction force control routine of FIG.
FIG. 8 is a graph showing a change characteristic of a first energization amount for fluid reaction force with respect to a steering wheel steering speed.
FIG. 9 is a graph showing a change characteristic of the second energization amount for the fluid reaction force with respect to the steering angle of the steering wheel.
FIG. 10 is a graph showing a change characteristic of a third energization amount for fluid reaction force with respect to vehicle speed.
FIG. 11 is a graph showing a change characteristic of the first energization amount for the motor reaction force with respect to the steering speed of the steering wheel.
FIG. 12 is a graph showing a change characteristic of the second energization amount for the motor reaction force with respect to the steering angle of the steering wheel.
FIG. 13 is a graph showing a change characteristic of the third energization amount for the motor reaction force with respect to the vehicle speed.
FIG. 14 is an explanatory diagram for explaining a change state of a reaction torque of a Bingham fluid mixed with magnetic powder.
15A is a graph showing a reaction force characteristic of a motor with respect to a steering angle of a steering wheel, FIG. 15B is a graph showing a reaction force characteristic of a Bingham fluid with respect to a steering speed of the steering wheel, and FIG. It is a graph which shows the synthetic reaction force characteristic by a Bingham fluid.
16 is a longitudinal sectional view of a fluid reaction force generator according to a first modification of the fluid reaction force generator of FIG.
FIG. 17 is a longitudinal sectional view of a fluid reaction force generator according to a second modification of the fluid reaction force generator of FIG. 2;
18 is a cross-sectional view of the rotor as seen along line AA in FIG.
FIG. 19 is a longitudinal sectional view of a fluid reaction force generator according to a third modification of the fluid reaction force generator of FIG.
20A is a cross-sectional view of the first rotor viewed along line AA in FIG. 19, and FIG. 20B is a view of the second rotor viewed along line BB in FIG. It is a cross-sectional view.
FIG. 21 is a flowchart that is applied to the fluid reaction force generator according to the third modified example, and is a modified part of the first and second reaction force control routines of the embodiment.
22 is a longitudinal sectional view of a fluid reaction force generator according to a fourth modification of the fluid reaction force generator of FIG.
23 is a cross-sectional view of the rotor as seen along line AA in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Steering handle, 11 ... Rotating shaft, 12 ... Electric motor, 13 ... Reduction gear, 14 ... Fluid reaction force generator, 20a, 20b ... Front wheel (steering wheel), 27 ... Electric motor, 30 ... Electric control device, DESCRIPTION OF SYMBOLS 31 ... Electronic control unit, 32 ... Steering angle sensor, 33 ... Steering angle sensor, 34 ... Vehicle speed sensor, 41 ... Housing, 42 ... Rotor, 42a ... Fin, 43 ... Iron core, 44 ... Coil, 46 ... Permanent magnet, 50 , 60, 70 ... fluid reaction force generator, 51, 61, 71 ... housing, 52, 62, 63, 72 ... rotor, 52a ... groove, 63a, 63b, 72a ... step, 54, 65, 66, 74, 77 ... iron core, 55, 67, 68, 75, 78 ... coil.

Claims (9)

In a steering apparatus for a vehicle that steers steering wheels according to the rotation of a steering handle,
A rotor coupled to the steering handle via a rotating shaft and rotating integrally with the steering handle;
A non-Newtonian fluid containing a magnetic powder and containing a non-Newtonian fluid that contains the rotor and imparts a frictional reaction force to the rotor that varies greatly in a nonlinear manner when the rotor changes from a stopped state to a rotating state. A filled housing ,
Magnetic field lines generating means for generating magnetic field lines to form a magnetic field in the non-Newtonian fluid,
A vehicle steering apparatus comprising a step provided on at least a part of an outer surface of the rotor facing an inner surface of the housing . In the vehicle steering apparatus according to claim 1,
A vehicle steering system employing a Bingham fluid as the non-Newtonian fluid. In the vehicle steering apparatus according to claim 1 or 2,
A vehicle steering apparatus in which the magnetic force line generating means is constituted by a permanent magnet . In the vehicle steering apparatus according to claim 1 or 2 ,
A vehicle steering apparatus in which the magnetic force line generating means is composed of an electromagnet . The vehicle steering apparatus according to claim 4 , further comprising:
A vehicle steering apparatus comprising magnetic field mode control means for changing and controlling a magnetic field formation mode by the electromagnet . In the vehicle steering apparatus according to claim 5 ,
A steering apparatus for a vehicle, wherein the magnetic field mode control unit includes an energization mode control unit that controls an energization mode of the electromagnet . The vehicle steering apparatus according to claim 5 or 6 , further comprising:
A turning limit control means for detecting a turning limit of the steered wheel and controlling the magnetic field mode control means when the turning limit is detected to strengthen the magnetic field by the electromagnet is provided. Vehicle steering device. The vehicle steering apparatus according to any one of claims 5 to 7 , further comprising:
A vehicle comprising: a steering delay control unit that detects a steering delay of a steered wheel and controls the magnetic field mode control unit when the steering delay is detected to strengthen a magnetic field by the electromagnet. Steering device. The vehicle steering apparatus according to any one of claims 1 to 8 , further comprising:
A vehicle steering apparatus comprising an electric motor coupled to a steering handle via the rotary shaft to apply a reaction force to the rotation of the steering handle.

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