Steering device

Abstract

The EPS controller (3) of the steering device includes: a hydraulic abnormality determination section (50) that determines a hydraulic abnormality of a hydraulic chamber (P1, P2) when a prescribed abnormality determination condition is satisfied in normal control of the steering device; a manual driving additional torque calculation section (51) that calculates an additional torque (Tx) based on a map of the absolute value (|Tr+Tm|) of the additional torque (Tx) with respect to the total torque (Tr+Tm) when the hydraulic abnormality determination section (50) determines that there is a hydraulic abnormality at the time of manual driving; and an ADAS control additional torque calculation section (53) that calculates an additional torque (Tx) based on a map of the absolute value (|Tr+Tm|) of the additional torque (Tx) with respect to the total torque (Tr+Tm) when the hydraulic abnormality determination section (50) determines that there is a hydraulic abnormality at the time of automatic driving.

Description

Technical Field

[0001] This invention relates to steering devices. Background Technology

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

[0003] The steering device described in Patent Document 1 includes: a power cylinder having a piston and a pair of fluid chambers defined by the piston, and applying a hydraulic assist torque to steer the steering wheel; a rotary valve selectively supplying working fluid to the pair of fluid chambers according to the rotation of the steering shaft; and an electric motor applying a motor assist torque to the steering shaft. Furthermore, the steering device includes a control device for controlling the electric motor, which includes an anomaly detection unit that determines hydraulic anomalies in the fluid chambers based on the steering torque.

[0004] In the steering device described in Patent Document 1, since the hydraulic abnormality of the fluid chamber is judged based on the steering torque, there is a potential risk that the hydraulic abnormality of the fluid chamber cannot be judged during automatic driving when the steering torque is zero.

[0005] This invention is proposed in view of past practical situations, and its purpose is to provide a steering device that can determine whether there is a hydraulic abnormality in the fluid chamber during both manual driving and automatic driving.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-11585 Summary of the Invention

[0009] In this invention, the control device has a hydraulic abnormality judgment unit. When the torque obtained by adding the steering torque and the motor auxiliary torque is greater than a predetermined threshold torque, the hydraulic abnormality judgment unit judges that the hydraulic chamber is abnormal. When the hydraulic abnormality judgment unit judges that the hydraulic abnormality is abnormal, it increases the motor auxiliary torque of the electric motor.

[0010] According to the present invention, it is possible to determine the hydraulic abnormality of the liquid chamber in both manual and automatic driving modes. Attached Figure Description

[0011] Figure 1 This is a longitudinal sectional view of the steering device according to the first embodiment.

[0012] Figure 2 yes Figure 1 A partially enlarged sectional view of the steering device.

[0013] Figure 3 This is a control block diagram of the first embodiment.

[0014] Figure 4 It is the mapping used in the additional torque calculation unit for manual driving and the additional torque calculation unit for ADAS control.

[0015] Figure 5 This is a flowchart illustrating the starting steps of the hydraulic anomaly detection mode in the hydraulic anomaly detection unit.

[0016] Figure 6 This is a flowchart illustrating the steps for resolving hydraulic abnormality modes in the hydraulic abnormality judgment unit.

[0017] Figure 7 This is a perspective view of the steering device according to the fifth embodiment.

[0018] Figure 8 This is a partial longitudinal sectional view of the steering device according to the fifth embodiment. Detailed Implementation

[0019] Hereinafter, embodiments of the steering device applicable to the present invention will be described based on the accompanying drawings.

[0020] [First Implementation Method]

[0021] (Composition of the steering system)

[0022] Figure 1 This 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 the steering mechanism, including the electric motor 2. Figure 1 For ease of explanation, the side of the steering shaft 7 connected to the steering wheel (not shown) in the Z direction of rotation (the upper side in the figure) is referred to as "one end", and the side connected to the piston 15 (the lower side in the figure) is referred to as "the other end".

[0023] The steering system is an integrated steering system used in large vehicles, etc., and mainly consists of the steering system body 1, electric motor 2 and EPS controller (ECU) 3.

[0024] The main body of the steering device 1 includes a steering mechanism 4, a sector shaft 5, and a power cylinder 6.

[0025] The steering mechanism 4, which receives rotational force from a steering wheel (not shown), has 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 and is used to input the driver's steering torque. The other end of the input shaft 9 is inserted into an opening recess 10a formed at 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 is used to input the motor auxiliary torque of the electric motor 2 connected to the outer periphery. The intermediate shaft 10 is inserted into an opening recess 11a formed at one end of the output shaft 11 with an expanded diameter. One end of the output shaft 11 is rotatably connected to the intermediate shaft 10 via a second torsion bar 13, and the steering torque input from the intermediate shaft 10 is output to the piston 15 via a conversion mechanism, namely a ball screw mechanism 14.

[0026] The ball screw mechanism 14 is composed of the aforementioned output shaft 11, the aforementioned piston 15, and a plurality of balls 14c. The aforementioned output shaft 11, which serves as the screw shaft, has a helical groove, i.e., a ball groove 14a, formed on the outer periphery of the other end side. The aforementioned piston 15, which serves as the nut, is disposed on the outer periphery of the aforementioned output shaft 11 and has a helical groove, i.e., a ball groove 14b, formed on its inner periphery corresponding to the ball groove 14a. The aforementioned plurality of balls 14c are disposed between the piston 15 and the output shaft 11.

[0027] A rotary valve 16, a known control valve, is configured between the intermediate shaft 10 and the output shaft 11. The rotary valve 16 selectively supplies working fluid supplied by the pump unit 17 mounted on the vehicle to the first and second liquid chambers (pressure chambers) P1 and P2, described later, based on the amount and direction of the torsion of the second torsion bar 13 derived from the relative rotation angle between the intermediate shaft 10 and the output shaft 11.

[0028] The sector shaft 5 has a sector gear 5a, which rotates along with the axial movement of the piston 15 by meshing with the rack teeth 15a of the piston 15 disposed on the outer periphery of the other end of the steering shaft 7. The sector shaft 5 is connected to the steering wheel via a steering arm (not shown) for steering.

[0029] Thus, the aforementioned ball screw mechanism 14, sector shaft 5, and steering arm constitute a transmission mechanism that converts the rotational force (steering force) input to the steering shaft 7 into the steering force of the steering wheels. It should be noted that, in the absence of using the ball screw mechanism 14 or the like to constitute the steering device, the aforementioned transmission mechanism can be, for example, a rack rod or pinion shaft constituting a rack and pinion mechanism.

[0030] The power cylinder 6 is configured by dividing a pair of liquid chambers, namely the first and second liquid chambers P1 and P2, by a cylindrical piston 15 that can be slidably housed in the housing 8, and is a hydraulic actuator that generates hydraulic auxiliary torque to assist steering torque.

[0031] The electric motor (hollow motor) 2 is configured as a three-phase AC brushless motor that applies rotational torque to the input shaft 9. The electric motor 2 includes: a motor element 18, which is composed of a motor rotor 18a and a motor stator 18b; and a motor housing 19, which houses the motor element 18.

[0032] The motor rotor 18a is mounted on the outer periphery of the input shaft 9 in a manner that allows it to rotate integrally via a cylindrical connecting member 20. The motor stator 18b is disposed on the outer periphery of the motor rotor 18a with a predetermined gap and is electrically connected to the EPS controller 3 disposed outside the housing 8.

[0033] The connecting component 20 is fixed to the intermediate shaft 10 by embedding a key 21 protruding from the outer periphery of the connecting component 20 into a groove 20a formed on the inner periphery surface of the connecting component 20 using a known key connection. Through the aforementioned key connection, the connecting component 20 rotates integrally with the intermediate shaft 10 and is supported by a first bearing B1 and a second bearing B2.

[0034] The motor housing 19 is made of a metallic material, such as aluminum alloy. The motor housing 19 includes: a bottomed cylindrical housing body 24 that houses the motor component 18 and the first and second rotary transformers 22 and 23 (described later); a first closing portion 25 that closes the opening of the housing body 24 from the electric motor 2 side; and a second closing portion 26 that closes the opening of the extension portion 24a from the side opposite to the electric motor 2.

[0035] The housing body 24 has: a generally disc-shaped bottom 24b, which is formed to allow the input shaft 9 and the coupling member 20 to be inserted; a cylindrical cylindrical portion 24c, which stands from the outer periphery of the bottom 24b toward the other end of the steering shaft 7; and a cylindrical extension 24a, which stands from the outer periphery of the bottom 24b toward one end of the steering shaft 7.

[0036] The opening of the cylindrical portion 24c is closed by a generally disc-shaped first closing portion 25, which is formed to allow the input shaft 9 and the connecting member 20 to be inserted. The first closing portion 25 is mounted and fixed to the opening end face 24d of the cylindrical portion 24c via a fixing member such as a bolt 27. The space surrounded by the first closing portion 25, the bottom 24b, the cylindrical portion 24c, and the connecting member 20 becomes a motor storage portion 28 for storing the motor element 18. Furthermore, the first closing portion 25 is mounted and fixed to the connector member 30 via a fixing member such as a bolt 29. That is, the first closing portion 25 is fixed to the housing 8 via the connector member 30.

[0037] Furthermore, the opening of the extension 24a is closed by a generally disc-shaped second closing portion 26, which is formed to allow the input shaft 9 and the connecting member 20 to be inserted. The second closing portion 26 is mounted and fixed to the opening end face 24e of the extension 24a via a fixing member, such as a bolt 31. The space surrounded by the second closing portion 26, the bottom 24b, the extension 24a, and the input shaft 9 forms a torque sensor housing 33, which houses a torque sensor 32 used to calculate the steering torque generated by the first torque lever 12. The second closing portion 26 and the input shaft 9 are airtightly sealed by an annular sealing member 34.

[0038] The torque sensor 32 is composed of a first rotary transformer 22 disposed in the torque sensor housing 33 on the outer periphery of the connecting member 20 and a second rotary transformer 23 disposed in the torque sensor housing 33 on the outer periphery of the input shaft 9.

[0039] The first rotary transformer 22 includes: a first rotary transformer rotor 22a, which is fixed to the outer periphery of one end of the connecting member 20; and a first rotary transformer stator 22b, which is disposed on the outer periphery of the first rotary transformer rotor 22a and is fixed to the bottom 24b by a fixing member, such as a screw member 35. The first rotary transformer stator 22b is fixed to the bottom 24b by the screw member 35 while abutting against the inner peripheral surface 24g of the thick-walled portion 24f of the bottom 24b, the inner peripheral surface 24g of which overlaps with the sector shaft 5 in the Z direction of the rotation axis of the steering shaft 7. The first rotary transformer stator 22b is electrically connected to the EPS controller 3 via an output wiring (not shown). The EPS controller 3 inputs the intermediate shaft rotation angle θa (described later) of the intermediate shaft 10 detected by the first rotary transformer 22.

[0040] The second rotary transformer 23 includes: a second rotary transformer rotor 23a, which is fixed to the outer periphery of the input shaft 9 at a position closer to one end than the first rotary transformer stator 22b; and a second rotary transformer stator 23b, which is disposed on the outer periphery of the second rotary transformer rotor 23a and is mounted and fixed to the thick-walled portion 24f by a fixing member, such as a screw member 36, and via a washer 37. The second rotary transformer stator 23b is electrically connected to the EPS controller 3 via an output wiring (not shown) similarly to the first rotary transformer stator 22b. In the EPS controller 3, the input shaft rotation angle θh, described later, is input to the input shaft 9 as detected by the second rotary transformer 23.

[0041] The torque sensor 32, which consists of the first and second rotary transformers 22 and 23, calculates the steering torque by multiplying the difference between the input shaft rotation angle θh of the input shaft 9 detected by the second rotary transformer 23 and the intermediate shaft rotation angle θa of the intermediate shaft 10 detected by the first rotary transformer 22, and the torsion spring constant g1 of the first torsion bar 12.

[0042] It should be noted that in the first and second rotary transformers 22 and 23, the stators 22b and 23b of the first and second rotary transformers output sine wave signals and cosine wave signals that satisfy the condition that "the amplitude Ax of the rotor 22a of the first rotary transformer per revolution 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.

[0043] The first bearing B1 is disposed on the inner circumferential surface of the annular first bearing retaining portion 24h that protrudes from near the inner circumferential edge of the bottom 24b toward the other end of the steering shaft 7, supporting one end of the connecting member 20 so that it can rotate.

[0044] Similarly, the second bearing B2 is disposed on the inner peripheral surface of the annular second bearing retainer 24i, which protrudes from near the inner peripheral edge of the first closed portion 25 and is opposite to the first bearing retainer 24h, and supports the other end of the connecting member 20 so that it can rotate.

[0045] The EPS controller 3 is a control device comprising electronic components such as a microcomputer (not shown). The EPS controller 3 receives inputs including the steering torque Tr detected by the torque sensor 32, the vehicle speed V detected by the vehicle speed sensor (not shown), the steering angle θr detected by the steering angle sensor (not shown), and the engine speed N. Furthermore, the EPS controller 3 is electrically connected to the ADAS controller 38, which controls the vehicle's automatic driving (automatic steering) functions such as parking and lane keeping when the driver activates the automatic driving switch.

[0046] The ADAS controller 38 assesses the vehicle's surroundings based on detection signals from radar (not shown, such as millimeter-wave or infrared laser) and images from a camera (not shown), and determines the vehicle's position based on its own position information from GPS or the like. Furthermore, during automatic steering, such as lane keeping, the ADAS controller 38 calculates a steering angle command (ADAS command C) based on the aforementioned surroundings and the vehicle's position, aiming to keep the vehicle within the designated lane. When the driver activates the automatic driving switch, the ADAS controller 38 generates an automatic driving request signal X and sends it to the EPS controller 3 via CAN communication. Additionally, the ADAS controller 38 generates further information, such as ADAS switch signals for ADAS activation / deactivation and the value of a message counter used to assess the accuracy of CAN communication, and sends this information to the EPS controller 3 via CAN communication.

[0047] The housing 8 is a cylindrical shape with one end open and the other end closed. It consists of a first housing 39 that defines the first and second liquid chambers P1 and P2, and a second housing 40 that is provided to close one end opening of the first housing 39 and houses the rotary valve 16 inside. The first and second housings 39 and 40 are fastened to each other by a plurality of fastening means (not shown) appropriately provided on their outer peripheries, such as bolts.

[0048] Inside the first housing 39 are: a power cylinder body 39a, which is formed along the rotation axis Z of the steering shaft 7; and a shaft housing 39b, which is formed orthogonal to the power cylinder body 39a and partially faces the power cylinder body 39a. A piston 15 connected to the output shaft 11 is housed within the power cylinder body 39a, and the piston 15 defines a first liquid chamber P1 at one end and a second liquid chamber P2 at the other end. Furthermore, a sector-shaped shaft 5 is housed within the shaft housing 39b, with one axial end connected to the piston 15 and the other end connected to the steering wheel via a steering arm (not shown).

[0049] The outer periphery of the piston 15 and the sector shaft 5 is provided with rack teeth 15a and sector gears 5a that can mesh with each other. Through the meshing of the rack teeth 15a and sector gears 5a, the sector shaft 5 rotates along with the axial movement of the piston 15, thereby pulling the steering arm in the width direction of the vehicle body and changing the orientation of the steering wheels. It should be noted that at this time, the working fluid in the first liquid chamber P1 is introduced into the shaft receiving part 39b, thereby lubricating the rack teeth 15a and sector gears 5a.

[0050] On the inner circumferential side of the second housing 40, a shaft insertion hole 40a for inserting the overlapping intermediate shaft 10 and output shaft 11 extends from one end to the other along the rotation axis Z in a stepped diameter-reducing manner. Furthermore, a bearing Bn supporting the output shaft 11 for rotation is provided at the large diameter portion at one end. On the other hand, an inlet 41 communicating with the pump device 17, a discharge port 42 for discharging hydraulic pressure introduced through the inlet 41 to each liquid chamber P1 and P2, and a discharge port 44 for discharging working fluid discharged from each liquid chamber P1 and P2 through the discharge port 42 to the storage tank 43. It should be noted that the discharge port 42 communicates with the first liquid chamber P1 via a first discharge passage L1 provided at one end of the expanded diameter portion of the output shaft 11, and with the second liquid chamber P2 via a second discharge passage L2 provided inside the first housing 39.

[0051] According to the above structure, in the steering device, if the driver steers the steering wheel, the working fluid pumped by the pump device 17 is supplied via the rotary valve 16 to the fluid chambers P1 and P2 on the side corresponding to the steering direction, and the remaining working fluid corresponding to the supplied amount is discharged from the fluid chambers P1 and P2 on the other side to the reservoir 43. Moreover, as a result of driving the piston 15 by this hydraulic pressure, a hydraulic auxiliary torque based on the hydraulic pressure acting on the piston 15 is applied to the sector shaft 5.

[0052] Figure 3 This is a control block diagram of the first embodiment. Figure 4 This is the mapping used in the manual driving additional torque calculation unit 51 and the ADAS control additional torque calculation unit 53.

[0053] Figure 3 The control block diagram is configured such that, for example, in the event of a hydraulic abnormality in the liquid chambers P1 and P2 caused by a malfunction of the power cylinder 6, rotary valve 16, or pump unit 17, the motor auxiliary torque command value (hereinafter referred to as "motor auxiliary torque Tm") is increased by the electric motor 2. Furthermore, in Figure 3 For example, the calculation of motor assist torque Tm is switched between manual driving mode and automatic driving mode by a switch (not shown) located near the second adder 49B described later, which is capable of switching between manual driving mode and automatic driving mode.

[0054] The EPS controller 3 includes a basic auxiliary torque calculation unit 45, an additional control calculation unit 46, a total auxiliary torque calculation unit 47, an auxiliary torque limit calculation unit 48, a first adder 49A, a second adder 49B, a hydraulic abnormality judgment unit 50, an additional torque calculation unit for manual driving in case of hydraulic abnormality (hereinafter referred to as "additional torque calculation unit for manual driving") 51, an ADAS control torque calculation unit 52, an additional torque calculation unit for ADAS control in case of hydraulic abnormality (hereinafter referred to as "additional torque calculation unit for ADAS control") 53, and a fail-safe torque limit calculation unit 54.

[0055] The basic auxiliary torque calculation unit 45 is used in manual driving mode. Based on the steering torque Tr and vehicle speed V, it generates a specified mapping representing the basic auxiliary torque Ta relative to the steering torque Tr and vehicle speed V. The basic auxiliary torque Ta is, for example, 0 Nm to 1 Nm, and is output to the total auxiliary torque calculation unit 47.

[0056] The additional control calculation unit 46 is, for example, a phase compensation calculation unit that calculates a compensation value M based on the steering torque Tr. This compensation value M is output to the total auxiliary torque calculation unit 47 and added to the basic auxiliary torque Ta, thereby improving the responsiveness of the motor auxiliary force to torque changes relative to the steering torque Tr. It should be noted that the additional control calculation unit 46 is not limited to a phase compensation calculation unit, and can also be other calculation units such as a return angle control calculation unit for specified return angle control.

[0057] The total auxiliary torque calculation unit 47 generates the summed motor auxiliary torque Tb by adding the basic auxiliary torque Ta to the compensation value M. The summed motor auxiliary torque Tb is then output to the auxiliary torque limit calculation unit 48.

[0058] The auxiliary torque limit calculation unit 48 performs limit processing on the summed motor auxiliary torque Tb within a range of ±1 Nm based on the basic auxiliary torque Ta and the vehicle speed V, generating the limit-processed motor auxiliary torque Tc. The limit-processed motor auxiliary torque Tc is then output to the second adder 49B via the first adder 49A.

[0059] When the hydraulic anomaly detection unit 50 satisfies either the first or second anomaly detection condition during normal control of the steering device, it determines that there is a hydraulic anomaly in the fluid chambers P1 and P2. Here, "during normal control" refers to the state of normal control represented by a known state machine mounted in the EPS controller 3. When the hydraulic anomaly detection unit 50 determines that there is a hydraulic anomaly in the fluid chambers P1 and P2, it enters a hydraulic anomaly mode. During manual driving, the additional torque Tx is calculated in the manual driving additional torque calculation unit 51; on the other hand, during automatic driving, the additional torque Tx is calculated in the ADAS control additional torque calculation unit 53.

[0060] The first anomaly detection condition is that the absolute value of the sum of the steering torque Tr and the motor auxiliary torque Tm, Tr+Tm (the actual torque applied to the hydraulic gear), |Tr+Tm|, is greater than a specified threshold torque, which is 8 Nm in this embodiment, and the absolute value of the steering speed Vr, |Vr|, is less than a specified threshold steering speed, which is 90 degrees / second (deg / s) in this embodiment. This threshold steering speed is set to be less than the steering speed generated when the steering shaft 7 is steered at 8 Nm without hydraulic anomalies in the fluid chambers P1 and P2, for example, 800 deg / s. The threshold steering speed serves as a reference for insufficient hydraulic pressure, but its impact on the detection of hydraulic anomalies is very small. Therefore, the detection of hydraulic anomalies is highly dependent on the threshold torque, and the threshold steering speed is not a necessary condition, but rather a slightly auxiliary condition for detecting hydraulic anomalies.

[0061] The second abnormality judgment condition is that the engine speed N is less than 100 rpm. This is because the pump device 17 increases the pump output according to the increase of the engine speed N. Therefore, when the engine speed N is less than 100 rpm, it is considered that the pump output has not increased enough to apply hydraulic auxiliary torque, thus judging that there is a hydraulic abnormality in the liquid chambers P1 and P2.

[0062] The manual driving auxiliary torque calculation unit 51 is used in manual driving mode. When the hydraulic abnormality judgment unit 50 determines that a hydraulic abnormality exists, it calculates based on... Figure 4 The mapping of the additional torque Tx to the absolute value |Tr+Tm| of the total torque Tr+Tm is shown, and the additional torque Tx is output to the second adder 49B. The additional torque Tx is set to a value sufficient to compensate for the insufficient hydraulic auxiliary torque in the event of hydraulic abnormality.

[0063] like Figure 4 As shown in the mapping, when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is between 0 N and 5 Nm, the additional torque Tx is 0 Nm. When the absolute value of |Tr+Tm| is greater than 5 Nm but less than 10 Nm, the additional torque Tx increases linearly from 0 Nm to 2 Nm. In addition, when the absolute value of |Tr+Tm| is greater than 10 Nm, the additional torque Tx remains at 2 Nm.

[0064] The additional torque Tx obtained by the additional torque calculation unit 51 for manual driving is added to the motor auxiliary torque Tc after limit processing in the second adder 49B, thereby generating the first additional motor auxiliary torque Td.

[0065] The ADAS control torque calculation unit 52 is used in autonomous driving mode. Based on the ADAS command C and additional information, such as the ADAS switch signal mentioned above or the value from the message counter, it calculates the ADAS control torque Te. The ADAS control torque Te is output to the first adder 49A and the ADAS control auxiliary torque calculation unit 53. It should be noted that in autonomous driving mode, there is no driver steering, and the steering torque Tr is zero. Therefore, no calculation is performed between the auxiliary control calculation unit 46 and the auxiliary torque limit calculation unit 48, and only the ADAS control torque Te is output to the first adder 49A. The ADAS control torque Te of the first adder 49A is output to the second adder 49B.

[0066] The ADAS control additional torque calculation unit 53 is used in automatic driving mode. When the hydraulic anomaly judgment unit 50 determines that there is a hydraulic anomaly in fluid chambers P1 and P2, based on... Figure 4 The additional torque Tx is generated by mapping the absolute value of the total torque Tr+Tm, |Tr+Tm|, to the total torque Tr+Tm. This additional torque Tx is output to the second adder 49B, where it is added to the ADAS control torque Te to generate the second additional post-motor auxiliary torque Tf.

[0067] The fail-safe torque limit calculation unit 54 performs limit processing on the additional post-motor auxiliary torques Td and Tf after adding the additional torque Tx, within a range of ±4.2 Nm, based on predetermined limit processing conditions, to generate the motor auxiliary torque Tm. As a predetermined limit processing condition, for example, in the event of a hardware malfunction of the EPS controller 3, such as the temperature of the EPS controller 3 becoming too high, limit processing is performed to limit the limit. This is then applied to the electric motor 2 (refer to...). Figure 1 and Figure 2 It outputs the motor auxiliary torque Tm and feeds back the motor auxiliary torque Tm to the hydraulic abnormality judgment unit 50.

[0068] Furthermore, when additional torque control is performed by the manual driving additional torque calculation unit 51 or the ADAS control additional torque calculation unit 53 in the hydraulic abnormality mode, the hydraulic abnormality mode is released if the following first release condition or second release condition lasts for more than 800ms.

[0069] The first reset condition is the detection of an internal fault in the AHPS (Electric Power Steering). Specifically, the first reset condition is, for example, detecting an electrical system fault in the electric motor 2 of the electric power steering system by monitoring the current and voltage states using ammeters and voltmeters (not shown). This first reset condition is set because, in the event of a fault in the electric motor 2, it would be impossible to increase the motor auxiliary torque Tm of the electric motor 2.

[0070] The second release condition is that the engine speed N is greater than 400 rpm, the vehicle speed V is greater than 20 km / h, the absolute value of the steering angle θr |θr| is greater than 30 degrees (deg), and the absolute value of the steering torque Tr |Tr| is less than 5 Nm, and the sign of the steering torque Tr is consistent with the sign of the steering angle θr. This second release condition is set because, when the above conditions are met, the engine speed N is high, and the pump device 17 works fully to apply hydraulic auxiliary torque, thus enabling the steering system to operate even without additional torque control.

[0071] Figure 5 This is a flowchart showing the start step of the hydraulic abnormality mode in the hydraulic abnormality judgment unit 50.

[0072] First, in step S1, it is determined whether the system is in a hydraulic malfunction mode. If it is in a hydraulic malfunction mode, proceed to step S7 to clear the duration and end the process. If it is not in a hydraulic malfunction mode, proceed to step S2.

[0073] In step S2, a known state machine is used to determine whether the system is under normal control. If it is not under normal control, the process proceeds to step S7 to clear the duration and end the process. If it is under normal control, the process proceeds to step S3.

[0074] In step S3, the hydraulic anomaly judgment unit 50 determines whether the first or second anomaly judgment condition is met. Specifically, it determines whether the absolute value of the total torque Tr+Tm, |Tr+Tm|, is greater than 8 Nm and the absolute value of the steering speed Vr, |Vr|, is less than 90 degrees / s, or whether the engine speed N is less than 100 rpm. If neither condition is met, the process proceeds to step S7 to clear the duration and end the process. If the condition is met, the process proceeds to step S4.

[0075] In step S4, the timing for the duration of the aforementioned establishment begins. In step S5, if the duration is less than 100ms, the process proceeds to step S7 to clear the duration and end the process. If the duration is greater than 100ms, the process proceeds to step S6.

[0076] In step S6, a hydraulic malfunction mode is activated as a hydraulic malfunction exists. In the manual driving auxiliary torque calculation unit 51 or the ADAS control auxiliary torque calculation unit 53, the following steps are performed: Figure 4 The mapping is used to calculate the additional torque Tx.

[0077] Figure 6 This is a flowchart illustrating the steps for resolving hydraulic abnormality modes in the hydraulic abnormality judgment unit 50.

[0078] First, in step S11, it is determined whether the system is in a hydraulic malfunction mode. If it is not in a hydraulic malfunction mode, the process proceeds to step S16 to clear the duration and end the process. If it is in a hydraulic malfunction mode, the process proceeds to step S12.

[0079] In step S12, it is determined whether the first or second release condition of the hydraulic abnormality mode is met. Specifically, it is determined whether an internal fault in the AHPS is detected, or whether the engine speed N is greater than 400 rpm, the vehicle speed V is greater than 20 km / h, the absolute value of the steering angle θr |θr| is greater than 30 degrees, the absolute value of the steering torque Tr |Tr| is less than 5 Nm, and whether the sign of the steering torque Tr is consistent with the sign of the steering angle θr. If neither condition is met, the process proceeds to step S16 to clear the duration and end the process. If the condition is met, the process proceeds to step S13.

[0080] In step S13, the timing for the duration of the aforementioned establishment begins. In step S14, if the duration is less than 800ms, the process proceeds to step S16 to clear the duration and end the process. If the duration is greater than 800ms, the process proceeds to step S15.

[0081] In step S15, the hydraulic malfunction mode is turned off as if there is no hydraulic malfunction. That is, the use of the system is discontinued. Figure 4 The calculation of the additional torque Tx mapped to the value.

[0082] [Effects of the First Embodiment]

[0083] In the first embodiment, a hydraulic anomaly detection unit 50 is included. This unit can detect hydraulic anomalies in chambers P1 and P2 when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is greater than 8 Nm. When the hydraulic anomaly detection unit 50 determines that a hydraulic anomaly has occurred, it obtains an additional torque Tx and increases the motor auxiliary torque Tm of the electric motor 2. Therefore, during manual driving, the additional torque Tx is obtained based on the absolute value of the total torque Tr+Tm, |Tr+Tm|. On the other hand, during automatic driving, the steering torque Tr is zero, and the absolute value of the total torque Tr+Tm, |Tr+Tm|, is only the value of the motor auxiliary torque Tm. Based on this motor auxiliary torque Tm, the additional torque Tx is obtained. Therefore, in both manual and automatic driving, the motor auxiliary torque Tm can be increased by the additional torque Tx, thereby stabilizing the driver's steering in the event of a hydraulic anomaly.

[0084] Furthermore, in this embodiment, when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is greater than 8 Nm and the absolute value of the steering speed, |Vr|, is less than 90 degrees / s, a hydraulic anomaly is determined by the hydraulic anomaly determination unit 50. By adding the absolute value of the steering speed, |Vr|, to the absolute value of |Tr+Tm|, the determination of hydraulic anomalies can be performed efficiently.

[0085] In addition, in this embodiment, when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is between 0 Nm and 5 Nm, the EPS controller 3 does not generate additional torque Tx, and does not increase the motor auxiliary torque Tm of the electric motor 2.

[0086] Here, in manual driving mode, the reason why no additional torque Tx is generated when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is between 0 Nm and 5 Nm is that the range of manual steering is generally between 0 Nm and 5 Nm, and there is no need to intentionally generate additional torque Tx within this range. Furthermore, even if the hydraulic pressure is sufficient but incorrectly judged as abnormal when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is between 0 Nm and 5 Nm, no additional torque Tx will be generated. This suppresses the discomfort experienced by the driver due to excessive auxiliary torque from the hydraulic system and electric motor 2.

[0087] Furthermore, in autonomous driving mode, the absolute value of the total torque Tr+Tm, |Tr+Tm|, is between 0 Nm and 5 Nm, that is, the ADAS control torque Te is between 0 Nm and 5 Nm (the steering torque Tr in ADAS control is zero) and the additional torque Tx is zero. This is because ADAS control does not perform any control within this range.

[0088] [Second Implementation]

[0089] In the second embodiment, unlike the first embodiment, the hydraulic abnormality judgment unit 50 judges the hydraulic abnormality of fluid chambers P1 and P2 when the absolute value of the steering speed Vr of the steering shaft 7, |Vr|, is less than any steering speed between 90 and 360 deg / s.

[0090] Generally, the steering torque Tr required by the driver under normal hydraulic conditions is less than 5 Nm. However, even under normal conditions, at high-speed steering (e.g., above approximately 500 deg / s), there are situations where the amount of working fluid supplied by the pump unit 17 is insufficient, causing the steering torque Tr to exceed 5 Nm (catch-up). Assuming that the steering torque Tr is higher than 8 Nm, it is difficult to distinguish whether there is a hydraulic abnormality or insufficient working fluid due to high-speed steering. Therefore, in this embodiment, an upper limit of 360 deg / s, which is smaller than the approximately 500 deg / s expected for insufficient working fluid due to high-speed steering, is set to eliminate false detections associated with insufficient working fluid due to high-speed steering.

[0091] It should be noted that, except during high-speed steering, the accuracy of hydraulic anomaly detection is highly dependent on the threshold steering torque and almost independent of the absolute value of steering speed Vr, |Vr|.

[0092] [Effects of the Second Embodiment]

[0093] In the second embodiment, hydraulic abnormalities in fluid chambers P1 and P2 are determined when the absolute value of the steering speed Vr of the steering shaft 7, |Vr|, is less than any steering speed between 90 and 360 deg / s. Therefore, erroneous detections due to insufficient working fluid caused by high-speed steering can be eliminated, and only hydraulic abnormalities in fluid chambers P1 and P2 can be determined, thus improving the accuracy of hydraulic abnormality detection.

[0094] [Third Implementation Method]

[0095] In the third embodiment, unlike the first embodiment, the hydraulic anomaly detection unit 50 determines a hydraulic anomaly in chambers P1 and P2 when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is greater than any torque between 7 Nm and 12 Nm. This is because the criteria for anomaly detection differ in various steering systems, thus the threshold torque is given a range to flexibly address the detection criteria of each steering system.

[0096] [Effects of the Third Implementation]

[0097] The hydraulic anomaly detection unit 50 of the third embodiment can increase the motor auxiliary torque Tm by adding an additional torque Tx during both manual driving and automatic driving, thereby stabilizing the driver's steering when there is a hydraulic anomaly.

[0098] [Fourth Implementation Method]

[0099] In the fourth embodiment, unlike the first embodiment, the EPS controller 3 does not generate additional torque Tx and does not increase the motor auxiliary torque Tm of the electric motor 2 when the absolute value of the total torque Tr+Tm, |Tr+Tm|, is below any torque between 4 Nm and 8 Nm. This is because the reference used to invalidate the generation of additional torque Tx differs in various steering systems, thus allowing the invalidation reference to have a range to flexibly address the invalidation reference of each steering system.

[0100] [Effects of the Fourth Implementation]

[0101] In the EPS controller 3 of the fourth embodiment, even if the hydraulic pressure is sufficient but it is mistakenly judged to be abnormal, the discomfort of steering caused to the driver due to excessive auxiliary torque of the hydraulic system and electric motor 2 can be suppressed by not generating additional torque Tx.

[0102] [Fifth Implementation Method]

[0103] Figure 7 This is a perspective view of the steering device according to the fifth embodiment. Figure 8 This is a partial longitudinal sectional view of the steering device according to the fifth embodiment.

[0104] In the second embodiment, the electric motor 2 is not connected via a hollow motor, but rather via a reducer 55 consisting of a worm gear and worm shaft that meshes the worm shaft 59 and the worm wheel 60, and a connecting shaft 56 provided around the input shaft 9.

[0105] The electric motor 2 and the EPS controller 3 are integrally constructed and housed within a motor housing 58, which is integrally formed with an input-side housing 57 that houses the input shaft 9, etc. The electric motor 2 has a motor shaft (not shown), one axial end of which is connected to a worm shaft 59. A worm 59a is integrally formed on the outer circumference of the worm shaft 59, and this worm 59a meshes with the helical tooth portion 60a of the worm wheel 60. The worm wheel 60 is connected to the outer circumference of the connecting shaft 56 via a known key connection (not shown). The connecting shaft 56 has a recess 56a on one axial end face, within which a portion of the other axial end of the input shaft 9 is embedded. Furthermore, the other axial end of the connecting shaft 56 has an external thread portion 56b, which is screwed into the internal thread portion 10b of an opening recess 10a provided on one axial end face of the intermediate shaft 10. The connecting shaft 56 is supported by a third bearing B3 provided on the outer peripheral surface at one end of the axial direction and a fourth bearing B4 provided on the outer peripheral surface at the other end of the axial direction, enabling it to rotate.

[0106] The torque sensor 32A is positioned around the connecting shaft 56, which is fixed to the outer circumference of the input shaft 9, with the first torsion bar 12 passing through the interior of the annular torque sensor 32A. The torque sensor 32A mainly consists of a permanent magnet 62, a pair of first and second magnetic yokes 63 and 64, a pair of first and second magnetic collecting rings 65 and 66, and a magnetic sensor 67. The permanent magnet 62, magnetic yokes 63 and 64, and magnetic collecting rings 65 and 66 are all configured to be approximately concentric with the rotation axis Z of the steering shaft 7.

[0107] The permanent magnet 62 is formed of a magnetic material into a generally cylindrical shape and is a magnetic component fixed to the outer periphery of one end of the connecting shaft 56. The permanent magnet 62 is constructed by alternating N poles and S poles (magnetizing) along the circumference of the permanent magnet 62.

[0108] A pair of magnetic yokes 63 and 64 are both formed into a generally cylindrical shape from soft magnetic materials. The magnetic yokes 63 and 64 are respectively arranged in a row along the circumference on one end side of the intermediate shaft 10 and are radially opposed to the permanent magnet 62. On the other hand, for the other end side, the first magnetic yoke 63 is arranged on the inner circumference side and the second magnetic yoke 64 is arranged on the outer circumference side, thereby being radially opposed.

[0109] A pair of magnetic collecting rings 65 and 66 are approximately circular rings that collect the magnetic flux of the permanent magnets 62 leaking to the other ends of the two yokes 63 and 64 within a predetermined range, and are arranged radially between the other ends of the yokes 63 and 64. The magnetic collecting ring 65 is located on the outer circumference, and the magnetic collecting ring 66 is located on the inner circumference, with the two facing each other radially. A Hall element 68 is arranged radially between the magnetic collecting rings 65 and 66. A magnetic collecting portion 65a, formed by pressing radially inward, is provided at a predetermined position in the circumference of the magnetic collecting ring 65; conversely, a magnetic collecting portion 66a, formed by protruding radially outward, is provided in the circumference of the magnetic collecting ring 66 opposite to the magnetic collecting portion 65a.

[0110] The magnetic sensor 67 comprises a Hall element 68 and a connection terminal 70. The Hall element 68 is housed in the radial gap between the magnetic collecting sections 65a and 66a. The connection terminal 70 connects the Hall element 68 to the control board 69, which is positioned above the torque sensor 32A. The magnetic sensor 67 detects the magnetic flux passing between the magnetic collecting sections 65a and 66a caused by the Hall element 68 using the Hall effect, and outputs a signal corresponding to the magnetic flux to the control board 69. This allows for the calculation of the relative rotation angle between the input shaft 9 and the intermediate shaft 10 in the control board 69, and the calculation of the steering torque based on this relative rotation angle.

[0111] [Effects of the Fifth Implementation]

[0112] In the fifth embodiment, the electric motor 2 is not connected to the hollow motor, but rather to the input shaft 9 via a reducer, connecting shaft 56.

[0113] In a steering system with such an electric motor 2, both manual and automatic driving can increase the motor's auxiliary torque Tm through the additional torque Tx, thereby stabilizing the driver's steering in case of hydraulic abnormalities.

Claims

1. A steering device, characterized in that, have: The steering shaft receives input from the rotation of the steering wheel; A transmission mechanism that transmits the rotation of the steering shaft to the steering wheels; A power cylinder having a piston disposed in the transmission mechanism and a pair of liquid chambers defined by the piston, applies a hydraulic auxiliary torque to steer the steering wheel; A rotary valve that selectively supplies working fluid to the pair of liquid chambers according to the rotation of the steering shaft; An electric motor applies motor-assisted torque to the steering shaft; A torque sensor that detects the steering torque corresponding to the rotation of the steering shaft; The control device includes a hydraulic anomaly detection unit. This unit determines a hydraulic anomaly in the hydraulic chamber when the torque obtained by adding the steering torque and the motor auxiliary torque is greater than a predetermined threshold torque. When the hydraulic anomaly detection unit determines that a hydraulic anomaly has occurred, it increases the motor auxiliary torque of the electric motor. After the hydraulic anomaly judgment unit determines that the hydraulic anomaly is present, the control device releases the judgment of the hydraulic anomaly when the engine speed is greater than 400 rpm, the vehicle speed is greater than 20 km / h, the absolute value of the steering angle is greater than 30 degrees, the absolute value of the steering torque is less than 5 Nm, and the sign of the steering torque is consistent with the sign of the steering angle.

2. The steering device according to claim 1, wherein, The specified threshold torque is 8 Nm. The hydraulic anomaly judgment unit judges the hydraulic anomaly when the summed torque is greater than 8 Nm and the absolute value of the steering speed of the steering shaft is less than 90 degrees / second.

3. The steering device according to claim 1, wherein, The hydraulic anomaly detection unit determines the hydraulic anomaly during automatic driving.

4. The steering device according to claim 2, wherein, The hydraulic anomaly detection unit determines the hydraulic anomaly during automatic driving.

5. The steering device according to any one of claims 1 to 4, wherein, The control device does not increase the motor auxiliary torque of the electric motor when the absolute value of the summed torque is less than 5 Nm.

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