Steering

Abstract

In an EPS controller (3), a first automatic steering operation instruction (B) is generated based on a steering operation angle instruction (θrc) and a steering operation angle (θr), and is output to a line (CL2). The first automatic steering operation instruction (B) is converted into a second steering operation instruction (D) by adding a steering operation instruction signal correction value (C) in an adder (56). The steering operation instruction signal correction value (C) is set based on manufacturing errors of a power cylinder (6) and a rotary valve (16) of a steering device. A motor instruction signal generating unit (59) generates a target current (Iq*, Id*) based on the second steering operation instruction (D) and a motor speed (Nm).

Description

Technical Field

[0001] The present invention relates to a steering device. Background Art

[0002] As a steering device, for example, the steering device described in the following Patent Document 1 is known.

[0003] The steering system described in Patent Document 1 includes a steering mechanism that transmits the driver's steering force and a steering mechanism that steers the steering wheels in response to the steering force. The steering mechanism includes a power cylinder that applies the steering force to the steering wheels. Working fluid is supplied to the power cylinder via a rotary valve.

[0004] Typically, power cylinders and rotary valves, comprised of multiple components, experience manufacturing variations between individual components in the assembled state. Therefore, even if the steering force input to the steering mechanism is identical between steering system products, there is a risk of variations in steering force, or in other words, variations in output characteristics, due to individual manufacturing variations.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-9682 Summary of the Invention

[0008] The present invention has been made in view of the existing actual situation, and an object of the present invention is to provide a steering device capable of suppressing variations in output characteristics between products.

[0009] Means of solving the problem

[0010] In one embodiment of the present invention, the steering operation command signal correction unit corrects the first steering operation command signal based on the steering operation command signal correction value to generate the second steering operation command signal.

[0011] According to the present invention, variations in output characteristics among steering device products can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a longitudinal sectional view of the steering device according to the first embodiment.

[0013] Figure 2 yes Figure 1 A partially enlarged cross-sectional view of the steering device.

[0014] Figure 3 yes Figure 1 Control block diagram of the EPS controller.

[0015] Figure 4 (a) is a graph showing the output torque relative to the input torque to the steering shaft. Figure 4 (b) is a graph showing the steering command signal correction value relative to the input torque to the steering shaft.

[0016] Figure 5 This is a control block diagram of the EPS controller in the second embodiment.

[0017] Figure 6 This is a control block diagram of the EPS controller in the third embodiment.

[0018] Figure 7 This is a graph of the third embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the third embodiment.

[0019] Figure 8 This is a graph of the fourth embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the fourth embodiment.

[0020] Figure 9 This is a graph of the fifth embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the fifth embodiment.

[0021] Figure 10 This is a graph of the sixth embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the sixth embodiment.

[0022] Figure 11 This is a graph of the seventh embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the seventh embodiment.

[0023] Figure 12 This is a graph of the eighth embodiment showing a steering command signal correction value relative to an input torque to a steering shaft in the eighth embodiment.

[0024] Figure 13 This is a control block diagram of the EPS controller in the ninth embodiment.

[0025] Figure 14 Graph showing a ninth embodiment of the present invention showing a steering command signal correction value relative to an input torque to a steering shaft.

[0026] Figure 15 This is a control block diagram of the EPS controller in the tenth embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the steering device according to the present invention will be described with reference to the drawings.

[0028] [First embodiment]

[0029] (Structure of Steering Device)

[0030] Figure 1 It is a longitudinal sectional view of the steering device according to the first embodiment. Figure 2 yes Figure 1 A partially enlarged cross-sectional view of a portion of the steering device including the electric motor 2. Figure 1 In the figure, for the sake of convenience, the side of the steering operating shaft 7 connected to the steering wheel (not shown) in the Z direction of the rotation axis is set as "one end", and the side connected to the piston 15 (the lower side in the figure) is set as "the other end" for explanation.

[0031] The steering device is an integral type steering device used in large vehicles and the like, and is mainly composed of a steering device body 1 , an electric motor 2 , and an EPS controller (ECU) 3 .

[0032] The steering system body 1 includes a steering mechanism 4 , a sector gear shaft 5 , and a power cylinder 6 .

[0033] The steering mechanism 4 receives rotational force from a steering wheel (not shown) and includes a steering shaft 7. A portion of the steering shaft 7 is housed within a housing 8 and includes an input shaft 9, an intermediate shaft 10, and an output shaft 11. One end of the input shaft 9 is connected to the steering wheel for input of the driver's steering torque. The other end of the input shaft 9 is inserted into an open recess 10a formed on one end of the intermediate shaft 10. One end of the intermediate shaft 10 is rotatably connected to the input shaft 9 via a first torsion bar 12 and receives drive torque from the electric motor 2 connected to the outer periphery. The intermediate shaft 10 is inserted into an open recess 11a formed in the expanded diameter portion of one end of the output shaft 11. One end of the output shaft 11 is rotatably connected to the intermediate shaft 10 via a second torsion bar 13. The steering torque input from the intermediate shaft 10 is output to a piston 15 via a ball screw mechanism 14, which serves as a conversion mechanism.

[0034] The ball screw mechanism 14 is composed of the following structure: the above-mentioned output shaft 11 serving as a screw shaft has a ball groove 14a serving as a spiral groove formed on the outer periphery of the other end side; the above-mentioned piston 15 serving as a nut is arranged on the outer periphery of the output shaft 11, and has a ball groove 14b serving as a spiral groove corresponding to the ball groove 14a formed on the inner periphery; and a plurality of balls 14c are arranged between the piston 15 and the output shaft 11.

[0035] A well-known rotary valve 16, serving as a control valve, is provided between the intermediate shaft 10 and the output shaft 11. The rotary valve 16 selectively supplies hydraulic fluid, supplied by a vehicle-mounted pump device 17, to the first and second fluid chambers (pressure chambers) P1 and P2, based on the amount and direction of twisting of the second torsion bar 13, which is derived from the relative rotational angle between the intermediate shaft 10 and the output shaft 11.

[0036] The sector gear shaft 5 is used for steering in accordance with the axial movement of a piston 15 provided on the outer periphery of the other end side of the steering operation shaft 7. The sector gear shaft 5 is connected to the steering wheel via a link arm (not shown).

[0037] The ball screw mechanism 14, the sector gear shaft 5, and the link arm constitute a transmission mechanism that converts the rotational force (steering force) input to the steering operation shaft 7 into a steering force for the steering wheel. When a steering device is configured without using the ball screw mechanism 14 or the like, a rack bar and pinion shaft constituting a rack-and-pinion mechanism, for example, can be used as the transmission mechanism.

[0038] The power cylinder 6 is formed by dividing a first fluid chamber P1 and a second fluid chamber P2 into a pair of fluid chambers by a cylindrical piston 15 slidably housed in a housing 8 , and is a hydraulic actuator that generates assist torque to assist steering torque.

[0039] The electric motor (hollow motor) 2 is a three-phase AC brushless motor that applies rotational torque to the input shaft 9. The electric motor 2 includes a motor element 18 consisting of a motor rotor 18a and a motor stator 18b, a motor housing 19 that houses the motor element 18, and a first bearing B1 and a second bearing B2 that rotatably support a coupling member 20. The coupling member 20 is secured to the intermediate shaft 10 via a known key connection, formed by fitting a key 21 protruding from the outer periphery of the intermediate shaft 10 into a groove 20a formed on the inner periphery of the coupling member 20. This key connection allows the coupling member 20 to rotate integrally with the intermediate shaft 10.

[0040] The motor rotor 18a is integrally rotatably mounted on the outer periphery of the input shaft 9 via a cylindrical coupling member 20. The motor stator 18b is disposed on the outer periphery of the motor rotor 18a with a predetermined gap therebetween and is electrically connected to the EPS controller 3 outside the housing 8.

[0041] Alternatively, instead of or in addition to the electric motor 2 which is a hollow motor, an electric motor capable of applying assist torque to the steering shaft 7 via a speed reducer having a worm shaft or a worm wheel may be used.

[0042] The motor housing 19 is formed of a metal material, such as an aluminum alloy. It includes a bottomed, cylindrical housing body 24 that houses the motor element 18 and the first and second resolvers 22 and 23, respectively. A first closing portion 25 closes the opening of the housing body 24 from the electric motor 2 side, and a second closing portion 26 closes the opening of the expansion portion 24a from the side opposite the electric motor 2.

[0043] The housing body 24 has a bottom 24b that is formed into a roughly disc shape so that the input shaft 9 and the coupling member 20 can be inserted, a cylindrical barrel portion 24c that stands upright from the outer peripheral edge of the bottom 24b toward the other end side of the steering operating shaft 7, and a cylindrical expansion portion 24a that stands upright from the outer peripheral edge of the bottom 24b toward one end side of the steering operating shaft 7.

[0044] The opening of the cylindrical portion 24c is closed by a first, generally disc-shaped, closing portion 25, which is formed to allow the input shaft 9 and the coupling member 20 to be inserted. The first closing portion 25 is fixed to the open end surface 24d of the cylindrical portion 24c via a fixing member, such as a bolt 27. The space enclosed by the first closing portion 25, the bottom portion 24b, the cylindrical portion 24c, and the coupling member 20 forms a motor housing 28 that houses the motor element 18. Furthermore, the first closing portion 25 is fixed to an adapter member 30 via a fixing member, such as a bolt 29. The first closing portion 25 is fixed to the housing 8 via the adapter member 30.

[0045] The opening of the expanded portion 24a is sealed by a second, generally disc-shaped, sealing portion 26, which is formed to accommodate the input shaft 9 and the coupling member 20. The second sealing portion 26 is secured to the open end surface 24e of the expanded portion 24a via a securing member, such as a bolt 31. The space enclosed by the second sealing portion 26, the bottom portion 24b, the extended portion 24a, and the input shaft 9 forms a torque sensor housing 33. This housing houses a torque sensor 32, which is used to calculate the steering torque Tr generated in the first torsion bar 12. An annular sealing member 34 hermetically seals the space between the second sealing portion 26 and the input shaft 9.

[0046] The torque sensor 32 includes a first resolver 22 and a second resolver 23 . The first resolver 22 is provided on the outer periphery of the coupling member 20 in the torque sensor housing 33 , and the second resolver 23 is provided on the outer periphery of the input shaft 9 in the torque sensor housing 33 .

[0047] The first resolver 22 includes a first resolver rotor 22a and a first resolver stator 22b. The first resolver rotor 22a is fixed to the outer periphery of one end of the coupling member 20. The first resolver stator 22b is provided on the outer periphery of the first resolver rotor 22a and is attached to the base 24b via a fixing member, such as a screw 35. The first resolver stator 22b is attached to the base 24b via the screw 35, abutting against the inner circumferential surface 24g of the thick wall portion 24f of the base 24b that overlaps the sector gear shaft 5 in the Z direction of the rotation axis of the steering shaft 7. The first resolver stator 22b is electrically connected to the EPS controller 3 via output wiring (not shown). The intermediate shaft rotation angle θa of the intermediate shaft 10, described later, detected by the first resolver 22 is input to the EPS controller 3.

[0048] The second resolver 23 includes a second resolver rotor 23a and a second resolver stator 23b. The second resolver rotor 23a is fixed to the outer circumference of the input shaft 9 closer to one end than the first resolver stator 22b. The second resolver stator 23b is provided on the outer circumference of the second resolver rotor 23a and is attached to the thick-walled portion 24f via a spacer 37 using a fixing member, such as a screw member 36. Like the first resolver stator 22b, the second resolver stator 23b is electrically connected to the EPS controller 3 via output wiring (not shown). The input shaft rotation angle θh of the input shaft 9 detected by the second resolver 23 (described later) is input to the EPS controller 3.

[0049] The torque sensor 32 composed of the first resolver 22 and the second resolver 23 calculates the steering operation torque Tr by multiplying the difference between the input shaft rotation angle θh of the input shaft 9 detected by the second resolver 23 and the intermediate shaft rotation angle θa of the intermediate shaft 10 detected by the first resolver 22 by the torsion spring constant g1 of the first torsion bar 12.

[0050] In addition, in the first resolver 22 and the second resolver 23, the first resolver stator 22b and the second resolver stator 23b output sine wave signals and cosine wave signals that satisfy "the amplitude number Ax per rotation of the first resolver rotor 22a is less than 360° / (specified angle θx×2)". Based on each output signal, the rotation angle of the input shaft 9 and the electric motor 2, etc. is calculated in the EPS controller 3.

[0051] The first bearing B1 is provided on the inner peripheral surface of an annular first bearing holding portion 24h protruding from the vicinity of the inner peripheral edge of the bottom portion 24b toward the other end of the steering shaft 7, and rotatably supports one end of the coupling member 20.

[0052] Similarly, the second bearing B2 is arranged on the inner circumferential surface of the annular second bearing retaining portion 24i, and can rotatably support the other end side of the coupling member 20. The second bearing retaining portion 24i is formed to protrude from near the inner circumferential edge of the first closing portion 25 in a manner opposite to the first bearing retaining portion 24h.

[0053] The EPS controller 3 is configured to include electronic components such as a microcomputer. In addition, the EPS controller 3 is electrically connected to the ADAS controller 38, which is used to control the automatic driving (automatic steering operation) of the vehicle, such as parking or lane keeping, when the driver turns on the automatic driving switch. In the case of manual steering operation based on the steering torque Tr input from the driver, the EPS controller 3 controls the steering torque Tr and the vehicle speed V (see FIG. 1 ). Figure 3 ) drives the electric motor 2. On the other hand, in the case of automatic steering operation, the steering operation angle θr (refer to Figure 3 ) drives and controls the electric motor 2. The EPS controller 3 corresponds to the "controller" described in the claims.

[0054] The ADAS controller 38 understands the surrounding conditions of the vehicle based on detection signals from a radar (e.g., millimeter wave or infrared laser) or images from a camera (e.g., not shown), and understands the vehicle's position based on vehicle position information from GPS or the like. Furthermore, during an automatic steering operation, such as when performing lane keeping, the ADAS controller 38 calculates a steering angle command θrc (see FIG. 1 ) which is a target steering angle for maintaining the vehicle within a predetermined lane based on the surrounding conditions and the vehicle's position. Figure 3 ) In addition, when the driver turns on the automatic driving switch, the ADAS controller 38 generates an automatic driving request signal X and transmits it to the EPS controller 3 via CAN communication.

[0055] The housing 8 is composed of a first housing 39 and a second housing 40. The first housing 39 is cylindrical, open at one end and closed at the other end, and defines a first liquid chamber P1 and a second liquid chamber P2. The second housing 40 is provided to close the opening at one end of the first housing 39 and houses the rotary valve 16 therein. The first and second housings 39, 40 are fastened to each other by a plurality of fixing means (not shown), such as bolts, appropriately provided on their outer circumferences.

[0056] A power cylinder body 39a and a shaft housing 39b are provided within the first housing 39. The power cylinder body 39a is formed along the rotation axis Z of the steering operating shaft 7, and the shaft housing 39b is formed so as to be orthogonal to the power cylinder body 39a and partially face the power cylinder body 39a. A piston 15 connected to the output shaft 11 is housed within the power cylinder body 39a, thereby dividing the first liquid chamber P1 on one end side and the second liquid chamber P2 on the other end side by the piston 15. In addition, a sector gear shaft 5 is housed within the shaft housing 39b. One axial end side of the sector gear shaft 5 is connected to the piston 15, and the other end side is connected to the steering wheel via a link arm (not shown).

[0057] The piston 15 and the sector gear shaft 5 are each provided with meshing teeth 15a and 5a on their outer circumferences. The meshing of the teeth 15a and 5a causes the sector gear shaft 5 to rotate in response to the axial movement of the piston 15, thereby pulling the link arm in the vehicle width direction, changing the direction of the steering wheel. Furthermore, at this time, the hydraulic fluid in the first fluid chamber P1 is directed into the shaft housing 39b, thereby lubricating the teeth 15a and 5a.

[0058] On the inner circumference of the second housing 40, a shaft insertion hole 40a, through which the overlapping intermediate shaft 10 and output shaft 11 are inserted, extends in a stepped, tapering pattern from one end to the other, along the rotation axis Z. A bearing Bn is provided at the large-diameter portion of one end, rotatably supporting the output shaft 11. Meanwhile, at the small-diameter portion of the other end, an inlet 41 is provided, communicating with the pump device 17; a supply / discharge port 42 for supplying and discharging hydraulic fluid introduced from this inlet 41 to and from the respective fluid chambers P1 and P2; and a discharge port 44 for discharging hydraulic fluid discharged from the respective fluid chambers P1 and P2 via this supply / discharge port 42 into a fluid reservoir 43. Furthermore, the supply / discharge port 42 communicates with the first fluid chamber P1 via a first supply / discharge passage L1 provided at the expanded-diameter portion of one end of the output shaft 11, and communicates with the second fluid chamber P2 via a second supply / discharge passage L2 provided within the first housing 39.

[0059] In this configuration, when the driver steers the steering wheel in the steering system, hydraulic fluid pumped by pump device 17 is supplied via rotary valve 16 to the fluid chambers P1 and P2 on the side corresponding to the steering direction. Meanwhile, hydraulic fluid corresponding to the supplied amount (remaining amount) is discharged from the other fluid chambers P1 and P2 to reservoir tank 43. This hydraulic pressure then drives piston 15, resulting in an assist torque applied to sector gear shaft 5 based on the hydraulic pressure acting on piston 15.

[0060] Figure 3 yes Figure 1 The control block diagram of the EPS controller 3. Figure 3, for convenience of explanation, the state in which the first switching unit 46 and the second switching unit 47 are connected to the automatic steering operation mode is shown.

[0061] The EPS controller 3 mainly includes a steering command signal generating unit 45 , a first switching unit 46 , a second switching unit 47 , a steering command signal correcting unit 48 , a motor control unit 49 , and a motor command signal output unit 50 .

[0062] The steering operation instruction signal generating unit 45 includes a manual steering operation instruction signal generating unit 45a that generates a first manual steering operation instruction signal (hereinafter referred to as the "first manual steering operation instruction") A as a torque instruction signal during manual steering operation, and an automatic steering operation instruction signal generating unit 45b that generates a first automatic steering operation instruction signal (hereinafter referred to as the "first automatic steering operation instruction") B as a torque instruction signal during automatic steering operation.

[0063] As external inputs, the interface of the EPS controller 3 is provided with a steering torque signal receiving unit 51 , a vehicle speed signal receiving unit 52 , a steering angle command signal receiving unit 53 , and a steering angle signal receiving unit 54 .

[0064] The steering torque signal receiving unit 51 receives the signal from the torque sensor 32 (see Figure 2 ) outputs a steering operation torque signal (hereinafter referred to as “steering operation torque”) Tr.

[0065] The vehicle speed signal receiving unit 52 receives a vehicle speed signal (hereinafter referred to as “vehicle speed”) V output from a vehicle speed sensor (not shown).

[0066] The steering angle command signal receiving unit 53 receives a steering angle command signal (hereinafter referred to as “steering angle command”) θrc, which is a signal related to a target steering angle of the steering shaft 7 and is output from the ADAS controller 38 .

[0067] The steering angle signal receiving unit 54 receives a steering angle signal (hereinafter referred to as “steering angle”) Tr, which is a signal related to an actual steering angle applied to the steering shaft 7 and detected by a steering angle sensor (not shown).

[0068] The manual steering operation command signal generating unit 45a generates a first manual steering operation command A based on the steering torque Tr detected by the torque sensor 32 and the vehicle speed V detected by the vehicle speed sensor. That is, the manual steering operation command signal generating unit 45a generates a first manual steering operation command A by referring to the correlation between the steering torque Tr and the vehicle speed V and the first manual steering operation command A. Figure 3 The mapping shown generates a first manual steering operation instruction A.

[0069] Furthermore, the automatic steering command signal generator 45b is configured as a PI controller (proportional-integral controller). When the ADAS controller 38 generates the automatic driving request signal X, the automatic steering command signal generator 45b calculates the difference between the steering angle command θrc output from the ADAS controller 38 and the steering angle θr detected by a steering angle sensor (not shown), performs proportional integration, and thereby generates a first automatic steering command B.

[0070] Furthermore, the first manual steering operation command A and the first automatic steering operation command B correspond to the “first steering operation command signal” in the scope of claims.

[0071] The first switching unit 46 switches between the manual steering operation mode and the automatic steering operation mode based on whether the automatic driving request signal X is input to the EPS controller 3. When the automatic driving request signal X is not input, the first switching unit 46 connects the line CL1 to the line CL2 in the manual steering operation mode and outputs the first manual steering operation command A to the line CL2. On the other hand, when the driver turns on the automatic driving switch, the automatic steering operation mode is switched off. Figure 3 As shown, when the automatic driving request signal X is input, the first switching unit 46 connects the line CL3 to the line CL2 as the automatic steering operation mode, and outputs the first automatic steering operation command B to the line CL2.

[0072] Similarly, the second switching unit 47 switches between the manual steering mode and the automatic steering mode based on whether the automatic driving request signal X is input to the EPS controller 3. When the automatic driving request signal X is not input, the second switching unit 47 sets the manual steering mode to connect the line CL4 to the line CL5, and outputs the steering torque Tr to the absolute value generating unit 55. On the other hand, when the driver turns on the automatic driving switch, the steering torque Tr is output to the absolute value generating unit 55. Figure 3 When the automatic driving request signal X is input, the second switching unit 47 connects the line CL6 and the line CL5 as the automatic steering operation mode, and outputs the first automatic steering operation command B to the absolute value generating unit 55 .

[0073] The process of generating the second steering operation command D described later based on the first manual steering operation command A and the process of generating the second steering operation command D based on the first automatic steering operation command B are basically the same process, so the latter process will be described as a representative process below.

[0074] The first automatic steering operation command B outputted via the first switching unit 46 is inputted to the adder 56 and then to the sign determination unit 57. The sign determination unit 57 determines whether the first automatic steering operation command B has a positive sign or a negative sign. The result of the determination by the sign determination unit 57 is inputted to the correction value output unit 58.

[0075] In addition, the first automatic steering operation instruction B output via the second switching unit 47 is set to an absolute value in the absolute value generating unit 55. That is, the first automatic steering operation instruction B is set to a positive value by the absolute value generating unit 55. The first automatic steering operation instruction B as a positive value is input to the steering operation instruction signal correction unit 48. The steering operation instruction signal correction unit 48 generates a steering operation instruction signal correction value C based on the first automatic steering operation instruction B. The steering operation instruction signal correction value C is generated according to the output of the power cylinder 6 for the third steering operation instruction signal when the third steering operation instruction signal is input to the electric motor 2. As the third steering operation instruction signal, the signal output from the EPS controller 3 is used. In addition, when the instruction signal of the electric motor 2 is corrected in the factory, the third steering operation instruction signal can also be output to the electric motor 2 from the equipment in the factory. In addition, regarding the calculation method of the steering operation instruction signal correction value C, reference will be made. Figure 4 (a) Figure 4 (b) will be described later. The steering operation command signal correction value C is input to the correction value output unit 58 .

[0076] Moreover, in the adder 56, a second steering operation instruction signal (hereinafter referred to as "second steering operation instruction") D is generated by adding the steering operation instruction signal correction value C output from the steering operation instruction signal correction unit 48 and the first automatic steering operation instruction B output via the first switching unit 46.

[0077] The motor control unit 49 includes a motor command signal generating unit 59, a first subtractor 60, a second subtractor 61, a first PI control unit 62, a second PI control unit 63, a two-phase to three-phase conversion unit 64, a voltage-PWM duty ratio conversion unit 65, a three-phase to two-phase conversion unit 66, and an angle-speed calculation processing unit 67.

[0078] The motor command signal generating unit 59 generates a q-axis target current Iq* as a motor command signal and a d-axis target current Id* as a similar motor command signal based on the second steering operation command D and the motor speed Nm output from the angle-speed calculation processing unit 67 .

[0079] The first subtractor 60 subtracts the q-axis actual current Iqr output from the three-phase to two-phase conversion unit 66 from the q-axis target current Iq* to generate a q-axis current deviation ΔIq.

[0080] The second subtractor 61 subtracts the d-axis actual current Idr output from the three-phase to two-phase conversion unit 66 from the d-axis target current Id* to generate a d-axis current deviation ΔId.

[0081] The first PI control unit 62 generates a q-axis voltage command Vq* for controlling the electric motor 2 by performing proportional integration on the q-axis current deviation ΔIq.

[0082] The second PI control unit 63 generates a d-axis voltage command Vd* for controlling the electric motor 2 by performing proportional integration on the d-axis current deviation ΔId.

[0083] The first PI control unit 62 and the second PI control unit 63 correspond to the "feedback control unit" described in the scope of the claims. Alternatively, feedback control may be performed by a first PID control unit and a second PID control unit (not shown) instead of the first PI control unit 62 and the second PI control unit 63.

[0084] The two-phase to three-phase converter 64 calculates the command signals Vu*, Vv*, and Vw* for the U, V, and W phases of the electric motor 2 configured as a three-phase brushless motor based on the two-phase voltage commands Vq* and Vd* and the motor rotation angle θm detected by the motor rotation angle sensor 68.

[0085] The voltage-PWM duty ratio converter 65 converts the commands Vu*, Vv*, Vw* into the U-, V-, W-phase duty ratios Du, Dv, Dw, and outputs them to the motor command signal output unit 50 .

[0086] The three-phase to two-phase converter 66 calculates the actual currents Iqr and Idr based on the actual supplied currents Iur and Ivr of the U and V phases detected by the motor current sensors 69 and 70 and the motor rotation angle θm detected by the motor rotation angle sensor 68 .

[0087] The angle-speed calculation processing unit 67 calculates the motor rotation speed Nm, which is the rotation speed of the electric motor 2 , based on the motor rotation angle θm, and outputs the calculated calculation to the motor command signal generating unit 59 .

[0088] The motor command signal output unit 50 is composed of a switching element, for example, a switching circuit formed by bridge-connected FETs. By operating the switching element based on duty ratios Du, Dv, and Dw, the DC voltage of the power supply 71 is converted into a three-phase AC voltage and supplied to the electric motor 2.

[0089] Figure 4 (a) is a graph showing the output (steering assist) torque relative to the input torque to the steering shaft 7. Figure 4 (b) is a graph showing the steering command signal correction value C with respect to the input torque to the steering shaft 7 . Figure 4 The reference output torque 72 shown by the solid line in (a) is the desired output torque of the steering device obtained when there is no manufacturing error in the power cylinder 6 or the rotary valve 16. Figure 4 The measured output torque 73 shown by the dotted line in (a) is the output torque obtained when measuring the output of the steering device having manufacturing errors of the power cylinder 6 or the rotary valve 16. Figure 4 (a) and Figure 4 The input torque shown on the horizontal axis of (b) becomes larger toward the right side of these figures, and the output torque and the steering command signal correction value C shown on the vertical axis become larger toward the upper side.

[0090] First, we'll explain how to measure the output torque (static characteristics of the output) relative to the input torque (steering torque during manual steering operation, motor torque during automatic steering operation) of the steering shaft 7. This measurement is performed, for example, in a factory measurement room. A torque measuring device is installed on the steering shaft 7, and a strain gauge is pre-installed on a link arm with its end fixed. A rotational force is applied to the steering shaft 7, which in turn acts on the link arm in the vehicle width direction. The torque measuring device detects the steering torque and motor torque, and the measured output torque 73, representing the steering force, is detected based on the strain measured by the strain gauge.

[0091] like Figure 4 As shown in (a), the reference output torque 72 is a higher value than the measured output torque 73, and both increase in a quadratic function. Figure 4 As shown in Figure (a), to obtain a predetermined output torque To based on reference output torque 72, first input torque Tia is required. In contrast, to obtain the same output torque To based on measured output torque 73, second input torque Tib, which is greater than first input torque Tia, is required. In other words, to obtain output torque To based on measured output torque 73, a greater input torque is required, which is the difference between input torque Tia and input torque Tib, Tib-Tia, than when obtaining output torque To based on reference output torque 72.

[0092] like Figure 4 As shown in the curve diagram of (b), the difference in input torque between the reference output torque 72 and the measured output torque 73 (for example, the difference Tib-Tia) is converted into a correction value for obtaining an output torque equal to the reference output torque 72 by measuring the output torque 73, and is represented as a steering operation instruction signal correction value C.

[0093] When the input torque is relatively small, Figure 4As the right side of (a) is reached, the difference in input torque between the reference output torque 72 and the measured output torque 73 becomes larger, so the steering operation command signal correction value C becomes as follows: Figure 4 (b) increases linearly (the portion indicated by symbol R1). On the other hand, when the input torque is relatively large, as shown in FIG. Figure 4 As shown in (a), the difference in input torque between the reference output torque 72 and the measured output torque 73 is substantially constant, so the steering operation command signal correction value C is as follows: Figure 4 As shown in (b), it becomes horizontal (the portion shown by the symbol R2).

[0094] Regarding the steering operation command signal correction value C, by understanding, for example, Figure 4 The correlation between the difference Tib - Tia (a) and the difference between the reference value and the measured value related to the shaping of the power cylinder 6 or rotary valve 16 can be estimated from the difference between the reference value and the measured value. The steering command signal correction value C is used, for example, for a steering system set including the difference between the reference value and the measured value. Information related to the steering command signal correction value C is input from the ADAS controller 38 to the steering command signal correction unit 48.

[0095] [Effects of the First Embodiment]

[0096] In conventional steering systems, the power cylinder and rotary valve, comprised of various components, contain manufacturing variations in their assembled state. Specifically, due to dimensional variations in these components during molding and assembly errors in the factory, the power cylinder and rotary valve contain manufacturing variations in their assembled state. These manufacturing variations can cause the output torque relative to the steering system's input torque to deviate from a baseline output torque value, as would be expected without these variations.

[0097] Furthermore, when considering various steering devices having different manufacturing tolerances, even if the same input torque is input to each steering device, the output torque generated by the input torque may vary due to the manufacturing tolerances of the power cylinder and the rotary valve.

[0098] In contrast, in the first embodiment, the steering device, in one mode thereof, comprises: a steering operating mechanism 4, comprising a steering operating shaft 7 and a transmission mechanism, the steering operating shaft 7 comprising an input shaft 9, an output shaft 11 and torsion bars 12 and 13 connecting the input shaft 9 and the output shaft 11, the transmission mechanism transmitting the rotation of the steering operating shaft 7 to the steering wheel; a power cylinder 6, comprising a power cylinder body 39a, a piston 15, a first liquid chamber P1 and a second liquid chamber P2, imparting a steering force to the transmission mechanism for steering the steering wheel, the piston 15 being arranged inside the power cylinder body 39a and dividing the internal space of the power cylinder body 39a into a first liquid chamber P1 and a second liquid chamber P2; a rotary valve 16, selectively supplying a working fluid supplied from the outside to the first liquid chamber P1 and the second liquid chamber P2 according to the torsion of the second torsion bar 13; an electric motor 2, imparting a steering force to the input shaft 9 Provide rotational force; and EPS controller 3, including steering operation instruction signal generating unit 45, steering operation instruction signal correction unit 48, motor instruction signal generating unit 59 and motor instruction signal output unit 50, the steering operation instruction signal generating unit 45 generates a first automatic steering operation instruction B (first manual steering operation instruction A), the steering operation instruction signal correction unit 48 corrects the first automatic steering operation instruction B based on the steering operation instruction signal correction value C, and generates a second steering operation instruction D, the steering operation instruction signal correction value C is generated according to the output of the power cylinder 6 for the third steering operation instruction signal when the third steering operation instruction signal is input to the electric motor 2, the motor instruction signal generating unit 59 generates a motor instruction signal based on the second steering operation instruction D, and the motor instruction signal output unit 50 outputs the motor instruction signal to the electric motor 2.

[0099] More specifically, a steering command signal correction value C is provided to absorb variations in output torque caused by manufacturing errors in the power cylinder 6 or rotary valve 16 at the factory. Based on this steering command signal correction value C, the first automatic steering command B is corrected to a second steering command D. A motor command signal is then generated based on this second steering command D to drive the electric motor 2. Consequently, variations in output torque due to manufacturing errors in the rotary valve 16 and other components are absorbed, allowing the desired output torque (output characteristics) relative to the input torque to be achieved immediately after the steering system is operated.

[0100] Assuming that even if there is no first automatic steering operation instruction B based on the above-mentioned steering operation instruction signal correction value C, in this embodiment, since feedback control is performed by the first PI control unit 62 and the second PI control unit 63, the desired output torque can be obtained after a specified time.

[0101] However, as in the present embodiment, by generating the motor command signal based on the second steering operation command D corrected by the steering operation command signal correction value C, it is possible to obtain desired output characteristics immediately after the steering device is operated.

[0102] Furthermore, even when the same input torque is input to various steering devices having different manufacturing errors, variations in output characteristics between steering device products can be suppressed by performing corrections based on steering operation command signal correction values ​​corresponding to the respective manufacturing errors.

[0103] Furthermore, even if there are variations in output characteristics between steering device products, the output torque can be corrected using a steering operation command signal correction value corresponding to each manufacturing error. Therefore, there is no need to reduce the dimensional tolerances of the power cylinder 6 and the rotary valve 16. Consequently, the manufacture of the power cylinder 6 and the rotary valve 16 is simplified, and an increase in manufacturing costs can be suppressed.

[0104] Furthermore, in the first embodiment, the steering operation command signal correction value C is generated based on the difference between the output of the power cylinder 6 and the reference output torque 72 when the third steering operation command signal is input to the electric motor 2 .

[0105] Therefore, by setting the reference output torque 72 to the desired output characteristic value, the desired output characteristic of the steering device can be obtained. In addition, by correcting the output characteristic of each steering device in accordance with the reference output torque 72, the deviation of the output characteristic between steering device products can be effectively suppressed.

[0106] [Second embodiment]

[0107] Figure 5 This is a control block diagram of the EPS controller in the second embodiment.

[0108] In the second embodiment, the steering operation command signal correction unit 48 includes a steering operation command signal correction value storage unit 74 that stores the steering operation command signal correction value C. The steering operation command signal correction value storage unit 74 is a non-volatile memory, such as an EEPROM. The steering operation command signal correction value storage unit 74 stores a map related to the steering operation command signal correction value C obtained based on the measurement results of the output torque relative to the input torque of each steering device at the factory stage. This map is obtained by obtaining the above-mentioned map for each steering device. Figure 4 (b) shows the result.

[0109] [Effects of the Second Embodiment]

[0110] In the second embodiment, the EPS controller 3 has a steering operation instruction signal correction value storage unit 74, which stores the steering operation instruction signal correction value C. The steering operation instruction signal correction unit 48 corrects the first automatic steering operation instruction B (the first manual steering operation instruction A) based on the steering operation instruction signal correction value C stored in the steering operation instruction signal correction value storage unit 74, and generates a second steering operation instruction D.

[0111] Therefore, for each steering device at the factory stage, Figure 4 The output characteristic measurement method described in (a) precisely measures the output characteristic in advance and uses the steering operation command signal correction value corresponding to the measurement result to correct the output torque, thereby effectively suppressing the variation in output characteristics between steering device products.

[0112] [Third embodiment]

[0113] Figure 6 This is a control block diagram of the EPS controller 3 in the third embodiment. Figure 7 Graph 1 is a graph showing the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7 in the third embodiment. Figure 7 In the figure, line 76 represents the steering operation command signal correction value C when the pump rotation speed Np is relatively high, and line 77 represents the steering operation command signal correction value C when the pump rotation speed Np is relatively low.

[0114] In the third embodiment, the EPS controller 3 includes a pump speed calculation unit 75 for calculating a pump speed Np that increases or decreases in proportion to the engine speed Ne. Alternatively, the pump speed Np may be calculated based on an object corresponding to the pump speed Np, such as the speed of the drive shaft of the pump device 17 or the speed of the electric motor 2 that drives the pump device 17. The pump speed Np corresponds to the "speed of the pump device" described in the scope of the claims.

[0115] The steering operation command signal correction unit 48 includes a steering operation command signal correction value adjustment unit 78 that adjusts the steering operation command signal correction value C based on the pump rotation speed Np output from the pump rotation speed calculation unit 75 .

[0116] like Figure 7 As shown, the steering operation command signal correction value C is set to decrease as the pump speed Np increases. Furthermore, since the discharge volume of the pump device 17 increases or decreases according to the pump speed Np, the steering operation command signal correction value C decreases as the discharge volume (flow rate) of the working fluid from the pump device 17 increases.

[0117] In addition, at the interface of the EPS controller 3, a working fluid temperature signal receiving unit 93, a load weight signal receiving unit 94, an air pressure signal receiving unit 95, an ambient temperature signal receiving unit 96, a motor terminal resistance value signal receiving unit 97, a steering operation signal correction value receiving unit 98 for right steering, and a steering operation instruction signal correction value receiving unit 99 for left steering are provided as external inputs.

[0118] The working fluid temperature signal receiving unit 93 receives a signal related to the temperature Tk of the working fluid supplied to the first fluid chamber P1 or the second fluid chamber P2 .

[0119] The load weight signal receiving unit 94 receives a signal related to the load weight W, which is the weight of the cargo loaded in the cargo box or the luggage room of the vehicle.

[0120] The air pressure signal receiving unit 95 receives a signal related to the air pressure Ap of the steering wheel.

[0121] The ambient temperature signal receiving unit 96 receives a signal related to the ambient temperature Tx.

[0122] The motor inter-terminal resistance value signal receiving unit 97 receives a signal related to the inter-terminal resistance value R of the output terminal of the electric motor 2 .

[0123] The right-turn steering operation signal correction value receiving unit 98 receives the right-turn steering operation signal correction value Rx, which is a correction value when the steered wheel is turned right.

[0124] The left-turn steering operation command signal correction value receiving unit 99 receives the left-turn steering operation command signal correction value Lx, which is a correction value when the steered wheel is turned left.

[0125] [Effects of the Third Embodiment]

[0126] In the third embodiment, the working fluid supplied to the rotary valve 16 is supplied from the pump device 17, and the steering operation command signal correction unit 48 includes a steering operation command signal correction value adjustment unit 78. The steering operation command signal correction value adjustment unit 78 adjusts the steering operation command signal correction value C based on a signal related to the pump rotation speed Np. Specifically, in the third embodiment, the steering operation command signal correction value adjustment unit 78 reduces the steering operation command signal correction value C as the value of the signal related to the pump rotation speed Np increases.

[0127] In more detail, since the discharge volume of the pump device 17 increases or decreases according to the pump speed Np, the output of the power cylinder 6 can be obtained by calculating the amount of working fluid flowing into the first liquid chamber P1 and the second liquid chamber P2 of the power cylinder 6. In addition, the output of the steering device is the sum of the output of the power cylinder 6 and the output of the electric motor 2 (motor torque). Moreover, the higher the pump speed Np and the larger the discharge volume of the pump device 17, the greater the proportion of the output of the power cylinder 6 to the overall output of the steering device, and the smaller the proportion of the output of the electric motor 2. Therefore, when the pump speed Np is high and the proportion of the output of the power cylinder 6 is large, the output of the electric motor 2 can be suppressed by reducing the steering operation instruction signal correction value C by the increase in the output of the power cylinder 6, so that the overall output of the steering device can be maintained at a desired value.

[0128] [Fourth embodiment]

[0129] Figure 8 Graph 1 is a graph showing the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7 in the fourth embodiment. Figure 8 In FIG. 7 , line 79 shows the steering operation command signal correction value C when the working fluid temperature Tk is relatively high, and line 80 shows the steering operation command signal correction value C when the working fluid temperature Tk is relatively low. Figure 6 The illustrated embodiment is controlled by the same EPS controller 3 , and the same components are denoted by the same reference numerals.

[0130] Although not shown in detail, in the fourth embodiment, unlike the first to third embodiments, the temperature Tk of the working fluid supplied to the first fluid chamber P1 or the second fluid chamber P2 is input from the working fluid temperature signal receiving unit 93 to the steering operation command signal correcting unit 48. The working fluid temperature Tk is detected by a working fluid temperature sensor (not shown).

[0131] The steering operation command signal correction value adjustment unit 78 provided in the steering operation command signal correction unit 48 adjusts the steering operation command signal correction value C based on the temperature Tk of the working fluid. Figure 8 As shown, the steering operation command signal correction value C is set to be larger as the temperature Tk of the working fluid is lower.

[0132] [Effects of the Fourth Embodiment]

[0133] In the fourth embodiment, the steering operation command signal correction value adjustment unit 78 adjusts the steering operation command signal correction value C based on a signal related to the temperature Tk of the working fluid supplied to the first fluid chamber P1 or the second fluid chamber P2. Specifically, in the fourth embodiment, the steering operation command signal correction value adjustment unit 78 increases the steering operation command signal correction value C as the value of the signal related to the temperature Tk of the working fluid supplied to the first fluid chamber P1 or the second fluid chamber P2 decreases.

[0134] More specifically, when the working fluid temperature Tk is relatively low, the viscous resistance of the working fluid is large, and therefore the output of the power cylinder 6 decreases. Furthermore, as described above, the overall output of the steering system is the sum of the output of the power cylinder 6 and the output of the electric motor 2. Therefore, even when the working fluid temperature Tk is low and the output of the power cylinder 6 decreases, increasing the steering operation command signal correction value C to increase the output of the electric motor 2 can maintain the overall output of the steering system.

[0135] [Fifth embodiment]

[0136] Figure 9 Graph 1 is a graph showing the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7 in the fifth embodiment. Figure 9 In FIG. 8 , line 81 shows the steering operation command signal correction value C when the vehicle speed V is relatively high, and line 82 shows the steering operation command signal correction value C when the vehicle speed V is relatively low. Figure 6 The illustrated embodiment is controlled by the same EPS controller 3 , and the same components are denoted by the same reference numerals.

[0137] Although not specifically shown in the figure, in the fifth embodiment, unlike the first to fourth embodiments, the vehicle speed V detected by the vehicle speed sensor is input from the vehicle speed signal receiving unit 52 to the steering operation command signal correction unit 48. The steering operation command signal correction value adjustment unit 78 provided in the steering operation command signal correction unit 48 adjusts the steering operation command signal correction value C based on the vehicle speed V. Figure 9 As shown, the steering operation command signal correction value C is set to be larger as the vehicle speed V is lower.

[0138] [Effects of the Fifth Embodiment]

[0139] In the fifth embodiment, the EPS controller 3 includes a vehicle speed signal receiving unit 52 that receives a vehicle speed signal (vehicle speed V). The steering operation command signal correction value adjusting unit 78 increases the steering operation command signal correction value C as the vehicle speed V decreases.

[0140] More specifically, when the vehicle speed V is low, the frictional force acting on the steering wheel from the road surface is large. Therefore, to overcome this frictional force and steer the steering wheel, the steering system output must be increased. Therefore, by increasing the steering operation command signal correction value C to increase the output of the electric motor 2, the overall steering system output can be increased, resulting in a steering system output that can counteract the increased frictional force. In other words, the desired steering feel (steering operability) can be maintained.

[0141] [Sixth embodiment]

[0142] Figure 10 Graph 1 is a graph showing the sixth embodiment of the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7. Figure 10 In the embodiment, line 83 shows the steering operation command signal correction value C when the load weight W is relatively large, and line 84 shows the steering operation command signal correction value C when the load weight W is relatively small. Figure 6 The illustrated embodiment is controlled by the same EPS controller 3 , and the same components are denoted by the same reference numerals.

[0143] Although specific illustrations are omitted, in the sixth embodiment, unlike the first to fifth embodiments, the weight of the cargo loaded in the cargo box or luggage compartment of the vehicle, i.e., the load weight W, is input from the load weight signal receiving unit 94 to the steering operation command signal correction unit 48. The load weight W is measured by a load weight measuring device provided in the cargo box or luggage compartment. The steering operation command signal correction value adjustment unit 78 provided in the steering operation command signal correction unit 48 adjusts the steering operation command signal correction value C based on the load weight W. Figure 10 As shown, the steering operation command signal correction value C is set to be larger as the load weight W is larger.

[0144] [Effects of the Sixth Embodiment]

[0145] In the sixth embodiment, the EPS controller 3 has a loading weight signal receiving unit 94 that receives a signal related to the loading weight (loading weight W). The signal related to the loading weight is a signal related to the weight of the cargo loaded in the cargo box or luggage compartment of the vehicle. The greater the loading weight W, the larger the steering operation instruction signal correction value adjustment unit 78 makes the steering operation instruction signal correction value C.

[0146] More specifically, when the load weight W is high, a greater load of the load weight W acts on the steering wheels. Therefore, to steer the steering wheels against the load W, the steering system requires a higher output. Therefore, by increasing the steering operation command signal correction value C by the load weight W and thereby increasing the output of the electric motor 2, the overall output of the steering system can be increased, resulting in a steering system output that can cope with the load weight W. In other words, the desired steering feel (steering operability) can be maintained.

[0147] [Seventh embodiment]

[0148] Figure 11 Graph 1 is a graph showing the seventh embodiment of the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7. Figure 11 In the embodiment, line 85 shows the steering operation command signal correction value C when the steering operation torque Tr is relatively large, and line 86 shows the steering operation command signal correction value C when the steering operation torque Tr is relatively small. Figure 6 The illustrated embodiment is controlled by the same EPS controller 3 , and the same components are denoted by the same reference numerals.

[0149] In the seventh embodiment, unlike the first to sixth embodiments, the steering force, i.e., the steering torque Tr detected by the torque sensor 32, is input from the steering torque signal receiving unit 51 to the steering command signal correction unit 48. The steering command signal correction value adjustment unit 78 provided in the steering command signal correction unit 48 adjusts the steering command signal correction value C based on the steering torque Tr. Figure 11 As shown in FIG. 1 , the steering command signal correction value C is set to be smaller as the steering torque Tr is larger.

[0150] [Effects of the Seventh Embodiment]

[0151] In the seventh embodiment, the steering device has a torque sensor 32, which is arranged on the steering operating shaft 7 to detect the driver's steering operating load, namely the steering operating torque Tr. The EPS controller 3 has a steering operating torque signal receiving unit 51, which receives a signal related to the steering operating torque, namely the steering operating torque Tr. The larger the steering operating torque Tr, the more the steering operation instruction signal correction value adjustment unit 78 reduces the steering operation instruction signal correction value C.

[0152] Thus, when the steering torque Tr is large, the driver is actively steering the steering wheel. Therefore, increasing the steering command signal correction value C hinders the driver's steering operation. Therefore, when the steering torque Tr is large, the driver's steering operation is prioritized. Therefore, by reducing the steering command signal correction value C, the driver's steering feel can be improved.

[0153] [Eighth Embodiment]

[0154] Figure 12 Graph 1 is a graph showing the eighth embodiment of the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7. Figure 12 In FIG. 8 , line 87 shows the steering operation command signal correction value C when the air pressure Ap of the steering wheel is relatively high, and line 88 shows the steering operation command signal correction value C when the air pressure Ap of the steering wheel is relatively low. Figure 6 The illustrated embodiment is controlled by the same EPS controller 3 , and the same components are denoted by the same reference numerals.

[0155] Although not shown in detail, in the eighth embodiment, unlike the first to seventh embodiments, the air pressure Ap of the steering wheel is input from the steering torque signal receiving unit 51 to the steering command signal correction unit 48. The steering command signal correction value adjustment unit 78 provided in the steering command signal correction unit 48 adjusts the steering command signal correction value C based on the air pressure Ap of the steering wheel. Figure 12 As shown, the steering operation command signal correction value C is set to be larger as the air pressure Ap of the steering wheel is lower.

[0156] [Effects of the Eighth Embodiment]

[0157] In the eighth embodiment, the EPS controller 3 has an air pressure signal receiving unit 95, which receives a signal related to the air pressure Ap of the steering wheel tire, namely, an air pressure signal. The lower the air pressure Ap of the steering wheel tire, the larger the steering operation instruction signal correction value adjustment unit 78 makes the steering operation instruction signal correction value C.

[0158] More specifically, when the air pressure Ap of the steering wheel is low, the contact area between the outer peripheral surface of the steering wheel and the road surface increases, and the friction acting on the steering wheel from the road surface also increases, making it difficult to steer the steering wheel. Therefore, to overcome the friction and steer the steering wheel, a higher output is required in the steering system. Therefore, by increasing the steering operation command signal correction value C and thereby increasing the output of the electric motor 2, the output of the steering system can be increased, resulting in a steering system output that can counteract the increased friction. In other words, the desired steering feel (steering operability) can be maintained.

[0159] [Ninth embodiment]

[0160] Figure 13 This is a control block diagram of the EPS controller 3 in the ninth embodiment. Figure 14 Graph 1 is a graph showing the ninth embodiment of the steering operation command signal correction value C relative to the input torque to the steering operation shaft 7. Figure 14 In the figure, line 89 shows the steering operation command signal correction value C when a correction parameter P (described later) is relatively large, and line 90 shows the steering operation command signal correction value C when the correction parameter P is relatively small.

[0161] In the ninth embodiment, unlike the first to eighth embodiments, a motor torque signal receiving unit 101 and a steering acceleration signal receiving unit 102 are provided at the interface of the EPS controller 3. The motor torque signal receiving unit 101 receives a signal related to the motor torque Tm of the electric motor 2. The steering acceleration signal receiving unit 102 receives a signal related to the steering acceleration Q of the steering wheel. The steering acceleration Q is based on the steering angle θs (refer to Figure 15 ) and the motor rotation angle θm. The motor torque Tm and the steering acceleration Q are input to the correction parameter calculation unit 100 provided in the EPS controller 3. The correction parameter calculation unit 100 generates a correction parameter P by dividing the steering acceleration Q by the motor torque Tm and outputs it to the steering operation command signal correction unit 48. The correction parameter P is equivalent to the gain of the output torque of the power cylinder 6. Figure 14 As shown, the steering operation command signal correction unit 48 is set so that the correction parameter P becomes smaller as it becomes larger.

[0162] As the signal of the motor torque Tm, an output signal from the torque sensor 32 may be used, or a current flowing through the electric motor 2 or a command signal to the electric motor 2 may be used.

[0163] [Effects of the Ninth Embodiment]

[0164] In the ninth embodiment, the EPS controller 3 includes a steering acceleration signal receiving unit 102 and a motor torque signal receiving unit 101. The steering acceleration signal receiving unit 102 receives a signal related to the steering acceleration Q of the steering wheel, and the motor torque signal receiving unit 101 receives a signal related to the motor torque Tm of the electric motor 2. The steering operation command signal correction unit 48 includes a steering operation command signal correction value adjustment unit 78. The steering operation command signal correction value adjustment unit 78 adjusts the steering operation command signal correction value C based on the signal related to the steering acceleration Q of the steering wheel and the motor torque Tm. Specifically, the steering operation command signal correction value C is set to decrease as a correction parameter P, which is obtained by dividing the steering acceleration Q by the motor torque Tm of the electric motor 2, increases.

[0165] When the friction force decreases due to aging of the power cylinder 6, for example, deterioration of the sealing of the piston 15, the steering acceleration Q becomes higher. As a result, the correction parameter P obtained by dividing the steering acceleration Q by the motor torque Tm becomes larger. Since the correction parameter P is equivalent to the gain of the output torque of the power cylinder 6, when the correction parameter P is large, the gain of the output torque of the power cylinder 6 also becomes larger. In this case, by reducing the steering operation instruction signal correction value C by an amount corresponding to the reduction in friction caused by aging, that is, the increase in the steering acceleration Q, the output torque of the electric motor 2 is reduced, thereby suppressing the overall output of the steering device. In this way, the output of the steering device can be maintained at a desired value.

[0166] [Tenth embodiment]

[0167] Figure 15 This is a control block diagram of the EPS controller 3 according to the tenth embodiment.

[0168] In the tenth embodiment, the steering angle command signal receiving unit 53 and the steering angle signal receiving unit 54 provided at the interface of the steering operation command signal generating unit 45 in the first to ninth embodiments are replaced by a steering angle command signal receiving unit 91 and a steering angle signal receiving unit 92 .

[0169] The steering angle command signal receiving unit 91 receives an external input of a steering angle command signal (hereinafter referred to as “steering angle command”) θsc, which is a signal related to a target steering angle of the steered wheels.

[0170] The steering angle signal receiving unit 92 receives an external input of a steering angle signal θs (hereinafter referred to as "steering angle"), which is a signal related to the actual steering angle of the steering wheel. The steering angle θs is provided on a steering shaft connected to the steering wheel and is detected by a steering angle sensor (not shown) that detects the stroke position of the steering shaft.

[0171] Alternatively, the steering angle θs may be calculated based on the torsional torque of the first torsion bar 12 and the second torsion bar 13 and the motor torque Tm.

[0172] Furthermore, as the steering angle θs, a value estimated based on the motor rotation angle θm of the electric motor 2 may be used.

[0173] like Figure 15As shown, the steering angle command θsc and the steering angle θs are converted into a first automatic steering command B by the automatic steering operation command signal generator 45b. Furthermore, this first automatic steering operation command B is added to the steering operation command signal correction value C by the adder 56 to be converted into a second steering operation command D. This second steering operation command D is input to the motor command signal generator 59 along with the motor speed Nm. The motor command signal generator 59 then generates a q-axis target current Iq* and a d-axis target current Id* based on the second steering operation command D and the motor speed Nm. The second steering operation command D is obtained based on the steering angle command θsc and the steering angle θs. Current deviations ΔIq and ΔId are generated by subtracting the actual currents Iqr and Iqr from the target currents Iq* and Id*. These current deviations ΔIq and ΔId are input to the first PI control unit 62 and the second PI control unit 63, respectively, which serve as feedback control units.

[0174] [Effects of the Tenth Embodiment]

[0175] In the tenth embodiment, the EPS controller 3 includes a steering angle command signal receiving unit 91 and a steering angle signal receiving unit 92. The steering angle command signal receiving unit 91 receives a signal related to the target steering angle of the steering wheel, namely, the steering angle command θsc, and sends the steering angle command θsc to the steering operation command signal generating unit 45. The steering angle signal receiving unit 92 receives a signal related to the actual steering angle θs of the steering wheel, namely, the steering angle θs. The motor command signal generating unit 59 includes a first PI control unit 62 and a second PI control unit 63. The first PI control unit 62 and the second PI control unit 63 generate a motor command signal through feedback control based on the second steering operation command D and the steering angle θs.

[0176] During driving using automatic steering, such as lane keeping, steering torque Tr may be input from the ADAS controller 38 to the motor command signal generator 59. The electric motor 2 is driven without feedback control using a command signal calculated based on the steering torque Tr. In this case, a predetermined steering angle and assist torque are output while the steering torque Tr is input, resulting in so-called open-loop control. Consequently, high-precision control of the electric motor 2 may not be possible.

[0177] However, as in the present embodiment, target currents Iq* and Id* are generated based on the second steering operation instruction D calculated using the steering angle θs, and the current deviations ΔIq and ΔId obtained by subtracting them are input to the first PI control unit 62 and the second PI control unit 63 for feedback control. As a result, the electric motor 2 can be controlled with high precision compared to the above-mentioned open-loop control case.

[0178] Furthermore, regarding the first automatic steering command B for generating the second steering command D, by using the steering angle θs instead of the steering angle θr, the electric motor 2 can be efficiently controlled in accordance with the gain of the power cylinder 6 .

[0179] [Other embodiments]

[0180] In other embodiments, for example, in the steering device of the third embodiment, the EPS controller 3 has an ambient temperature signal receiving unit 96, which receives the output signal of a temperature sensor provided on the vehicle, and the steering operation instruction signal correction value adjustment unit 78 adjusts the steering operation instruction signal correction value C based on the output signal of the temperature sensor.

[0181] Therefore, the ambient temperature Tx is acquired from the ambient temperature signal receiving unit 96 via CAN communication, and the temperature Tk of the working fluid supplied to the first fluid chamber P1 or the second fluid chamber P2 is estimated based on the ambient temperature Tx. This allows the working fluid temperature Tk to be determined even without providing a working fluid temperature sensor in the steering system. This reduces the manufacturing cost of the steering system.

[0182] In addition, in other embodiments, such as in the steering device of the third embodiment, the EPS controller 3 has a motor terminal resistance value signal receiving unit 97, which receives a signal related to the terminal resistance value R of the output terminal of the electric motor 2, and the steering operation command signal correction value adjustment unit 78 can also adjust the steering operation command signal correction value C based on the signal related to the motor terminal resistance value R.

[0183] Since the inter-terminal resistance value R changes with the ambient temperature Tx, the hydraulic fluid temperature Tk can be estimated based on the inter-terminal resistance value R, even without providing a hydraulic fluid temperature sensor in the steering device. This reduces the manufacturing cost of the steering device.

[0184] In addition, in another embodiment, for example, in the steering device of the third embodiment, the steering operation instruction signal correction value C may include a steering operation instruction signal correction value Rx for right steering and a steering operation instruction signal correction value Lx for left steering, and the steering operation instruction signal correction value Rx for right steering and the steering operation instruction signal correction value Lx for left steering may have different values ​​from each other, and the steering operation instruction signal correction unit 48 generates a second steering operation instruction D by correcting the first automatic steering operation instruction B (first manual steering operation instruction A) based on the steering operation instruction signal correction value Rx when the steering wheel turns right, and generates a second steering operation instruction D by correcting the first automatic steering operation instruction B (first manual steering operation instruction A) based on the steering operation instruction signal correction value Lx when the steering wheel turns left.

[0185] Generally speaking, in an integral steering device, due to the difference in volume between the first liquid chamber P1 and the second liquid chamber P2, and the difference in pressure area between the first liquid chamber P1 and the second liquid chamber P2, the output characteristics of the power cylinder 6 sometimes differ when the working fluid is supplied to the first liquid chamber P1 (for example, right steering) and when the working fluid is supplied to the second liquid chamber P2 (for example, left steering).

[0186] Therefore, in this embodiment, in order to compensate for the difference in output characteristics of the power cylinder 6 during the above-mentioned left and right steering, the steering operation command signal correction unit 48 uses the right steering operation command signal correction value Rx to generate the second steering operation command D when turning right, and uses the left steering operation command signal correction value Lx to generate the second steering operation command D when turning left.

[0187] Furthermore, in each of the above-described embodiments, an example is disclosed in which variations in the static characteristics of the power cylinder 6 are suppressed. However, a configuration in which variations in the dynamic characteristics of the power cylinder 6 are suppressed can also be applied to the present invention.

[0188] As a steering device based on the embodiment described above, for example, the following aspects are conceivable.

[0189] A steering device, in one embodiment, comprises: a steering operating mechanism, the steering operating mechanism having a steering operating shaft and a transmission mechanism, the steering operating shaft having an input shaft, an output shaft, and a torsion bar connecting the input shaft and the output shaft, the transmission mechanism transmitting the rotation of the steering operating shaft to the steering wheel; a power cylinder, the power cylinder having a power cylinder body, a piston, a first liquid chamber and a second liquid chamber, which imparts a steering force to the transmission mechanism to steer the steering wheel, the piston being arranged inside the power cylinder body and dividing the internal space of the power cylinder body into the first liquid chamber and the second liquid chamber; a rotary valve, the rotary valve selectively supplies working fluid supplied from the outside to the first liquid chamber and the second liquid chamber according to the torsion of the torsion bar; an electric motor, the electric motor The shaft imparts rotational force; the controller comprises a steering operation instruction signal generating unit, a steering operation instruction signal correcting unit, a motor instruction signal generating unit, and a motor instruction signal output unit, the steering operation instruction signal generating unit generating a first steering operation instruction signal, the steering operation instruction signal correcting unit correcting the first steering operation instruction signal based on a steering operation instruction signal correction value to generate a second steering operation instruction signal, the steering operation instruction signal correction value being generated according to the output of the power cylinder for the third steering operation instruction signal when the third steering operation instruction signal is input to the electric motor, the motor instruction signal generating unit generating a motor instruction signal based on the second steering operation instruction signal, and the motor instruction signal output unit outputting the motor instruction signal to the electric motor.

[0190] In a preferred embodiment of the steering device, the controller has a steering operation instruction signal correction value storage unit, which stores the steering operation instruction signal correction value; and the steering operation instruction signal correction unit corrects the first steering operation instruction signal based on the steering operation instruction signal correction value stored in the steering operation instruction signal correction value storage unit to generate the second steering operation instruction signal.

[0191] In another preferred embodiment, in any embodiment of the steering device, the steering operation command signal correction value is generated based on a difference between an output of the power cylinder and a reference output when the third steering operation command signal is input to the electric motor.

[0192] In another preferred embodiment, in any embodiment of the steering device, the working fluid supplied to the rotary valve is supplied from a pump device, and the steering operation instruction signal correction unit has a steering operation instruction signal correction value adjustment unit, which adjusts the steering operation instruction signal correction value based on a signal related to the rotational speed of the pump device.

[0193] In another preferred embodiment, in any embodiment of the steering device, the steering operation command signal correction value adjustment unit reduces the steering operation command signal correction value as the value of the signal related to the rotational speed of the pump device increases.

[0194] In another preferred embodiment, in any embodiment of the steering device, the steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on a signal related to the temperature of the working fluid supplied to the first fluid chamber or the second fluid chamber.

[0195] In another preferred embodiment, in any embodiment of the steering device, the steering operation command signal correction value adjustment unit increases the steering operation command signal correction value as the value of the signal related to the temperature of the working fluid supplied to the first liquid chamber or the second liquid chamber decreases.

[0196] In another preferred embodiment, in any embodiment of the steering device, the controller has an ambient temperature signal receiving unit, which receives an output signal of a temperature sensor provided on the vehicle, and the steering operation instruction signal correction value adjustment unit adjusts the steering operation instruction signal correction value based on the output signal of the temperature sensor.

[0197] In another preferred embodiment, in any embodiment of the steering device, the controller has a motor terminal resistance value signal receiving unit, which receives a signal related to the terminal resistance value of the output terminal of the electric motor, and the steering operation instruction signal correction value adjustment unit adjusts the steering operation instruction signal correction value based on the signal related to the motor terminal resistance value.

[0198] In another preferred embodiment, in any embodiment of the steering device, the controller includes a vehicle speed signal receiving unit that receives a vehicle speed signal, and the steering operation command signal correction value adjusting unit increases the steering operation command signal correction value as the vehicle speed decreases.

[0199] In another preferred embodiment, in any embodiment of the steering device, the controller has a loading weight signal receiving unit that receives a signal related to the loading weight, and the signal related to the loading weight is a signal related to the weight of the cargo loaded in the cargo box or luggage compartment of the vehicle, and the greater the loading weight, the more the steering operation instruction signal correction value adjustment unit increases the steering operation instruction signal correction value.

[0200] In another preferred embodiment, in any embodiment of the steering device, the steering device is equipped with a torque sensor, which is arranged on the steering operating shaft to detect the steering operating torque serving as the driver's steering operating load. The controller is equipped with the steering operating torque signal receiving unit, which receives a signal related to the steering operating torque, namely, a steering operating torque signal. The larger the steering operating torque, the more the steering operation instruction signal correction value adjustment unit reduces the steering operation instruction signal correction value.

[0201] In another preferred embodiment, in any embodiment of the steering device, the controller has an air pressure signal receiving unit, which receives a signal related to the air pressure of the tire of the steering wheel, namely, an air pressure signal. The lower the air pressure of the tire of the steering wheel, the more the steering operation instruction signal correction value adjustment unit increases the steering operation instruction signal correction value.

[0202] In another preferred embodiment, in any embodiment of the steering device, the controller includes a steering acceleration signal receiving unit and a motor torque signal receiving unit, the steering acceleration signal receiving unit receives a signal related to the steering acceleration of the steering wheel, the motor torque signal receiving unit receives a signal related to the output torque of the electric motor, and the steering operation instruction signal correction unit includes a steering operation instruction signal correction value adjustment unit, and the steering operation instruction signal correction value adjustment unit adjusts the steering operation instruction signal correction value based on the signal related to the steering acceleration of the steering wheel and the motor torque signal.

[0203] In another preferred embodiment, in any embodiment of the steering device, the controller has a steering angle command signal receiving unit and a steering angle signal receiving unit, the steering angle command signal receiving unit receives a signal related to the target steering angle of the steering wheel, namely, the steering angle command signal, and sends the steering angle command signal to the steering operation command signal generating unit, the steering angle signal receiving unit receives a signal related to the actual steering angle of the steering wheel, namely, the steering angle signal, and the motor command signal generating unit has a feedback control unit, and the feedback control unit generates the motor command signal through feedback control based on the second steering operation command signal and the steering angle signal.

[0204] In another preferred embodiment, in any embodiment of the steering device, the steering operation command signal correction value includes a steering operation command signal correction value for right steering and a steering operation command signal correction value for left steering, and the steering operation command signal correction value for right steering and the steering operation command signal correction value for left steering have different values ​​from each other. When the steering wheel turns right, the steering operation command signal correction unit corrects the first steering operation command signal based on the steering operation command signal correction value for right steering, thereby generating the second steering operation command signal. When the steering wheel turns left, the first steering operation command signal is corrected based on the steering operation command signal correction value for left steering, thereby generating the second steering operation command signal.

Claims

1. A steering device, wherein: have: A steering mechanism including a steering shaft and a transmission mechanism. The steering shaft includes an input shaft, an intermediate shaft, an output shaft, a first torsion bar connecting the input shaft and the intermediate shaft, and a second torsion bar connecting the intermediate shaft and the output shaft. The transmission mechanism includes a ball screw mechanism, a sector gear shaft, and a link arm for transmitting the rotation of the steering operation shaft to the steering wheel; A power cylinder including a power cylinder body, a piston, a first fluid chamber, and a second fluid chamber, which imparts a steering force to the transmission mechanism for steering the steering wheel, wherein the piston is a nut constituting a part of the ball screw mechanism. The piston is disposed inside the main body of the power cylinder and divides the internal space of the main body of the power cylinder into the first liquid chamber and the second liquid chamber; a rotary valve that selectively supplies externally supplied working fluid to the first and second fluid chambers in accordance with the twisting of the second torsion bar; an electric motor that imparts a rotational force to the intermediate shaft; as well as a steering angle sensor, the steering angle sensor detecting a steering angle; a vehicle speed signal receiving unit, the vehicle speed signal receiving unit receiving a signal related to the vehicle speed; a torque sensor provided on the steering shaft and detecting a steering torque serving as a steering load applied by a driver; An EPS controller including a steering operation command signal generating unit, a steering operation command signal correcting unit, a motor command signal generating unit, and a motor command signal output unit. The steering command signal generating unit generates a first steering command signal based on the steering torque and the vehicle speed or based on the steering angle and a steering command output by an ADAS controller connected to the EPS controller. The steering operation command signal correction unit generates a second steering operation command signal by adding a steering operation command signal correction value to the first steering operation command signal. The steering operation command signal correction value is generated based on the output of the power cylinder for the third steering operation command signal when the third steering operation command signal is input to the electric motor, and the steering operation command signal correction value is generated based on the difference between the output of the power cylinder and the reference output when the third steering operation command signal is input to the electric motor. The motor command signal generating unit generates a motor command signal based on the second steering operation command signal. The motor command signal output unit outputs the motor command signal to the electric motor.

2. The steering device according to claim 1, wherein: The EPS controller includes a steering operation command signal correction value storage unit. The steering operation command signal correction value storage unit stores the steering operation command signal correction value. The steering operation command signal correction unit generates the second steering operation command signal by adding the steering operation command signal correction value stored in the steering operation command signal correction value storage unit to the first steering operation command signal.

3. The steering device according to claim 1, wherein: The working fluid supplied to the rotary valve is the working fluid supplied from the pump device. The EPS controller includes a steering operation command signal correction value adjustment unit. The steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on a signal related to the rotational speed of the pump device.

4. The steering device according to claim 3, wherein: The steering operation command signal correction value adjustment unit reduces the steering operation command signal correction value as the value of the signal related to the rotational speed of the pump device increases.

5. The steering device according to claim 3, wherein: The steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on a signal related to a temperature of the working fluid supplied to the first fluid chamber or the second fluid chamber.

6. The steering device according to claim 5, wherein: The steering operation command signal correction value adjustment unit increases the steering operation command signal correction value as the value of the signal related to the temperature of the working fluid supplied to the first fluid chamber or the second fluid chamber decreases.

7. The steering device according to claim 5, wherein: The EPS controller includes an ambient temperature signal receiving unit. The ambient temperature signal receiving unit receives an output signal of a temperature sensor provided in the vehicle. The steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on the output signal of the temperature sensor.

8. The steering device according to claim 5, wherein: The EPS controller includes a motor terminal resistance value signal receiving unit. The motor inter-terminal resistance value signal receiving unit receives a signal related to the inter-terminal resistance value of the output terminal of the electric motor. The steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on a signal related to the motor inter-terminal resistance value.

9. The steering device according to claim 3, wherein: The EPS controller includes a vehicle speed signal receiving unit for receiving a vehicle speed signal. The steering operation command signal correction value adjustment unit increases the steering operation command signal correction value as the vehicle speed decreases.

10. The steering device according to claim 3, wherein: The EPS controller includes a load weight signal receiving unit that receives a signal related to the load weight. The signal related to the load weight is a signal related to the weight of the cargo loaded in the cargo box or luggage compartment of the vehicle. The steering operation command signal correction value adjustment unit increases the steering operation command signal correction value as the load weight increases.

11. The steering device according to claim 3, wherein: Equipped with torque sensor, The torque sensor is provided on the steering shaft and detects the steering torque as the driver's steering load. The EPS controller includes the steering torque signal receiving unit. The steering torque signal receiving unit receives a steering torque signal which is a signal related to the steering torque. The steering operation command signal correction value adjustment unit reduces the steering operation command signal correction value as the steering torque increases.

12. The steering device according to claim 3, wherein: The EPS controller includes an air pressure signal receiving unit. The air pressure signal receiving unit receives an air pressure signal which is a signal related to the air pressure of the tire of the steering wheel. The steering operation command signal correction value adjustment unit increases the steering operation command signal correction value as the air pressure of the tire of the steered wheel decreases.

13. The steering device according to claim 1, wherein: The EPS controller includes a steering acceleration signal receiving unit and a motor torque signal receiving unit. The steering acceleration signal receiving unit receives a signal related to the steering acceleration of the steering wheel. The motor torque signal receiving unit receives a signal related to the motor torque of the electric motor. The EPS controller includes a steering operation command signal correction value adjustment unit. The steering operation command signal correction value adjustment unit adjusts the steering operation command signal correction value based on a signal related to the steering acceleration of the steered wheel and a motor torque signal of the electric motor.

14. The steering device according to claim 1, wherein: The EPS controller includes a steering angle command signal receiving unit and a steering angle signal receiving unit. The steering angle command signal receiving unit receives a steering angle command signal that is a signal related to the target steering angle of the steering wheel, and sends the steering angle command signal to the steering operation command signal generating unit. The steering angle signal receiving unit receives a steering angle signal which is a signal related to the actual steering angle of the steering wheel. The motor command signal generating unit includes a feedback control unit. The feedback control unit generates the motor command signal through feedback control based on the second steering operation command signal and the steering angle signal.

15. The steering device according to claim 1, wherein The steering operation command signal correction value includes a steering operation command signal correction value for right steering and a steering operation command signal correction value for left steering. The right-turn steering operation command signal correction value and the left-turn steering operation command signal correction value have different values ​​from each other. The steering operation instruction signal correction unit corrects the first steering operation instruction signal based on the steering operation instruction signal correction value for right steering when the steering wheel turns right, thereby generating the second steering operation instruction signal. When the steering wheel turns left, the steering operation instruction signal correction unit corrects the first steering operation instruction signal based on the steering operation instruction signal correction value for left steering, thereby generating the second steering operation instruction signal.

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