JP7380412B2 - steering device - Google Patents

Description

The present invention relates to a steering device.

2. Description of the Related Art Conventionally, in an electric power steering device, a technique is known for reducing the load on a mechanical device caused by end contact when the steering angle exceeds a predetermined amount.

For example, the steering control device disclosed in Patent Document 1 limits the magnitude of the current command value for driving the steering assist motor when it is determined that the turning angle of the steered wheels has reached the limit angle. In other words, by reducing the output of the steering assist motor near the end, the load on the mechanical device caused by hitting the end is reduced.

JP 2018-30533 Publication

In this specification, a "steering assist actuator" that includes other than a motor is used as a generic term for the steering assist motor. In contrast to the electrical output limiting technique disclosed in Patent Document 1, a technique can be considered that reduces the load on the mechanical device by mechanically regulating the steering near the end of the steering angle. In this technology, when the driver applies torque while the steering is locked, control is activated to generate assist torque in response to the torque, increasing the output of the steering assist actuator. Therefore, the mechanical regulating device needs to be strong and large in size. Further, an actuator and a drive circuit for moving the mechanically regulating device are required, and it is also necessary to output an output that competes with the steering assist actuator, resulting in a problem that the actuator and drive circuit become larger.

The present invention was created in view of these points, and its purpose is to provide a steering device that mechanically locks the steering wheel near the end of the steering angle, in which the actuator and drive circuit are miniaturized. Our goal is to provide the following.

The steering device of the present invention includes a steering amount sensor (94), a steering assist actuator (800), a lock device (20), a lock actuator (710), a first circuit (68, 681, 682), It includes a second circuit (67) and a control section (30).

The steering amount sensor detects the amount generated when the driver turns the steering wheel. For example, the steering amount sensor is a torque sensor that detects the driver's steering torque. The steering assist actuator electrically assists the driver in steering according to the detected value of the steering amount sensor. The locking device is arranged closer to the driver than the steering amount sensor, and mechanically restricts rotation of the steering wheel. A lock actuator drives a locking device.

The first circuit energizes the steering assist actuator. A second circuit energizes the lock actuator. The control unit operates the first circuit and the second circuit to control operations of the steering assist actuator and the lock actuator.

During operation of the first circuit, the control unit energizes the lock actuator through the second circuit so as to lock the locking device when the absolute value of the steering angle equivalent value is larger than the threshold value, and controls the steering angle equivalent value. When the absolute value of is less than or equal to the threshold value, the second circuit energizes the lock actuator so as to release the lock device . For example, the steering assist actuator is a motor, and the steering angle equivalent value is a value calculated from the rotation angle of the steering assist actuator.

Since the locking device is arranged closer to the driver than the steering amount sensor, even if the driver applies torque in the locked state, the torque is not transmitted to the steering amount sensor. Therefore, the maximum output of the steering assist actuator, which is calculated according to the detected value of the steering amount sensor, can be lowered. Therefore, the actuator and drive circuit can be downsized.

FIG. 1 is a diagram of a column type EPS system to which the steering device of this embodiment is applied. A diagram of the rack type EPS system same as above. FIG. 2 is a diagram of circuit configuration example 1 of a motor drive circuit. FIG. 2 is a diagram of a second circuit configuration example of a motor drive circuit. FIG. 3 is a diagram of circuit configuration example 3 of a motor drive circuit. FIG. 1 is a schematic diagram showing the configuration of a three-phase double-winding rotating machine. FIG. 3 is a control block diagram of the steering device according to the present embodiment. FIG. 1 is a schematic diagram showing the overall configuration of a locking device according to each embodiment. A schematic cross-sectional view taken along the line IX-IX in FIG. 8. 5 is a flowchart showing operation control of the locking device. FIG. 2 is a schematic diagram of a locked body of the locking device according to the first embodiment. FIG. 2 is a schematic diagram showing (a) a state in which the protrusion of the movable part is in contact with the radially outer wall of the convex part of the locked object, and (b) a state in which the protrusion is fitted into the recess in the locking device of the first embodiment. FIG. 6 is a schematic diagram of a locked object near the (a) neutral position and (b) near the end of the locking device of the second embodiment. FIG. 7 is a schematic diagram of a locked object near the (a) neutral position and (b) near the end of the locking device of the third embodiment. FIG. 3 is a diagram of a modification of the rack type EPS system of FIG. 2;

Hereinafter, a plurality of embodiments of the steering device of the present invention will be described based on the drawings. The steering device of each embodiment is applied to an electric power steering system (hereinafter referred to as "EPS system") of a vehicle, and mechanically restricts the rotation of the steering wheel near the end of the steering angle.

[System configuration]
First, an EPS system 901 to which a "steering device" is applied will be described with reference to FIGS. 1 and 2. Among them, FIG. 1 shows a column type EPS system, and FIG. 2 shows a rack type EPS system. To distinguish between them, the column type EPS system is designated by the code 901C, and the rack type EPS system is designated by the code 901R. In FIGS. 1 and 2, only one side of the tire 99 is shown, and illustration of the tire on the opposite side is omitted.

As shown in FIGS. 1 and 2, the EPS system 901 includes a steering wheel 91 as a "steering", a steering shaft 92, an intermediate shaft 95, a steering rack 97, and the like. The steering shaft 92 is enclosed in a steering column 93, and has one end connected to the steering wheel 91 and the other end connected to an intermediate shaft 95.

A steering rack 97 is provided at the end of the intermediate shaft 95 opposite to the steering wheel 91, which uses a rack and pinion mechanism to convert rotation into reciprocating motion and transmit the same. When the steering rack 97 reciprocates, the tires 99 are steered via the tie rods 98 and knuckle arms 985. Moreover, universal joints 961 and 962 are provided in the middle of the intermediate shaft 95.

The steering device 200 includes a torque sensor 94, a steering assist actuator 800, a lock device 20, a lock actuator 710, a three-phase inverter circuit 68 as a "first circuit," an H-bridge circuit 67 as a "second circuit," and , a control section 30, etc. The torque sensor 94 detects the driver's steering torque Ts as a form of "a steering amount sensor that detects the amount generated in the driver's steering operation." The steering assist actuator 800 electrically assists the driver in steering according to the steering torque Ts.

The locking device 20 is disposed closer to the driver than the torque sensor 94, that is, closer to the steering wheel 91, and mechanically restricts rotation of the steering wheel. The lock actuator 710 drives the lock device 20 to mechanically restrict rotation of the steering shaft 92, thereby preventing the steering wheel 91 from being steered beyond the rack end.

In this embodiment, the steering assist actuator 800 is configured with a three-phase motor, and the lock actuator 710 is configured with a DC motor. The three-phase inverter circuit 68 serving as the "first circuit" energizes the steering assist actuator 800. The H-bridge circuit 67 as a "second circuit" energizes the lock actuator 710. The three-phase inverter circuit 68, which is the "first circuit," and the H-bridge circuit 67, which is the "second circuit," are collectively referred to as a "motor drive circuit . "

The control unit 30 is composed of a microcomputer, a drive circuit, etc., and includes a CPU (not shown), a ROM, a RAM, an I/O, a bus line connecting these components, etc., and a physical memory device such as a ROM (i.e. , a readable non-temporary tangible recording medium) by executing a program stored in advance on a CPU, or control by hardware processing using a dedicated electronic circuit.

The control unit 30 operates the three-phase inverter circuit 68 based on the steering torque Ts detected by the torque sensor 94 and the vehicle speed V detected by the vehicle speed sensor 14, and controls the drive of the steering assist actuator 800. The control unit 30 then causes the steering assist actuator 800 to output a desired steering assist torque.

The control unit 30 also operates the H-bridge circuit 67 and controls the operation of the lock actuator 710. Specifically, the control unit 30 energizes the lock actuator 710 through the H-bridge circuit 67 in accordance with the steering angle θs to operate the lock device 20. Here, the steering angle θs is not limited to the value detected by the steering angle sensor, but includes various “steering angle equivalent values ”. For example, a value calculated from the rotation angle of the steering assist actuator 800 is acquired by the control unit 30 as the steering angle θs.

In this embodiment, the three-phase inverter circuit 68, the H-bridge circuit 67, and the control unit 30 are included in the ECU (specifically, the EPS-ECU) 10. The ECU 10 is activated by an ON/OFF signal from the vehicle switch 11 or the like. Note that the vehicle switch 11 corresponds to an ignition switch in an engine vehicle, and corresponds to a push switch in a hybrid vehicle or an electric vehicle. Each signal to the ECU 10 is communicated using CAN, serial communication, etc., or sent as an analog voltage signal.

Furthermore, in this embodiment, the three-phase inverter circuit 68 and the H-bridge circuit 67, that is, the motor drive circuit, are provided in the same housing 600. Furthermore, in the examples shown in FIGS. 1 and 2, the control unit 30 and the motor drive circuit are provided in the same housing 600. Thereby, the steering device 200 can be downsized, and the number of wiring components such as harnesses and connectors can be reduced. In circuit configuration examples 1 and 3 (see FIGS. 3 and 5) to be described later, the number of harnesses, connectors, etc. for electrical connection to the positive and negative electrodes of the power source Bt may be one or two.

In the column type EPS system 901C shown in FIG. 1, the steering assist actuator 800 and the locking device 20 are both arranged on the steering column 93. The output torque of steering assist actuator 800 is transmitted to steering shaft 92. The torque sensor 94 is provided in the middle of the steering shaft 92 and detects the driver's steering torque Ts based on the torsional displacement of the torsion bar. The lock device 20 is arranged closer to the driver than the torque sensor 94.

In the rack-type EPS system 901R shown in FIG. 2, the steering assist actuator 800 and the locking device 20 are both arranged in the steering rack 97. The reciprocating movement of the steering rack 97 is assisted by the output torque of the steering assist actuator 800. The torque sensor 94 detects the driver's steering torque Ts transmitted to the steering rack 97. The lock device 20 is arranged closer to the driver than the torque sensor 94.

In this way, the lock device 20 is disposed closer to the driver than the torque sensor 94 in common to the column type and rack type EPS systems 901C and 901R. Therefore, even if the driver applies torque to the steering wheel 91 in the locked state, the torque is not transmitted to the torque sensor 94. Therefore, the maximum output of steering assist actuator 800, which is calculated according to the detected value of torque sensor 94, is suppressed.

[Example of configuration of motor drive circuit]
Next, three circuit configuration examples of the motor drive circuit will be described with reference to FIGS. 3 to 6. First, regarding the steering assist actuator 800 that is driven by the three-phase inverter circuit 68, a unit including a three-phase winding set and a three-phase inverter circuit corresponding to the winding set is referred to as a "system." Circuit configuration examples 1 and 2 shown in FIGS. 3 and 4 are single-system configurations, and circuit configuration example 3 shown in FIG. 5 is a two-system configuration. As shown in FIG. 6, in the two-system configuration, the "first circuit" 68 consists of two three-phase inverter circuits 681 and 682.

A three-phase winding set having a single system configuration includes U-phase, V-phase, and W-phase windings 811, 812, and 813 connected at a neutral point N. A voltage is applied from the three-phase inverter circuit 68 to the windings 811, 812, and 813 of each phase. A back electromotive force proportional to the product of the rotation speed and the sine value of the phase is generated in each phase. The back electromotive force generated in each phase is expressed by, for example, equations (1.1) to (1.3) based on voltage amplitude A, rotation speed ω, and phase θ.

Eu=-Aωsinθ...(1.1)
Ev=-Aωsin(θ-120)...(1.2)
Ew=-Aωsin(θ+120)...(1.3)

A steering assist actuator 800 with a two-system configuration has two three-phase winding sets 801 and 802. The three-phase winding set 801 of the first system includes windings 811, 812, and 813 of U1 phase, V1 phase, and W1 phase connected at neutral point N1. A voltage is applied from the first system three-phase inverter circuit 681 to the windings 811, 812, and 813 of each phase of the first system three-phase winding set 801.

The three-phase winding set 802 of the second system is configured by windings 821, 822, and 823 of U2 phase, V2 phase, and W2 phase connected at neutral point N2. A voltage is applied to the windings 821, 822, and 823 of each phase of the three-phase winding set 802 of the second system from the three-phase inverter circuit 682 of the second system.

As shown in FIG. 6, the two-system steering assist actuator 800 is a double-winding rotating machine in which two three-phase winding sets 801 and 802 are coaxially provided. The two three-phase winding sets 801 and 802 have the same electrical characteristics, and are arranged, for example, on a common stator with an electrical angle of 30[deg] shifted from each other. In that case, the back electromotive force generated in each phase of the first system and the second system is based on the voltage amplitude A, the rotation speed ω, and the phase θ, for example, equations (2.1) to (2.3), (2 .4a) to (2.6a).

Eu1=-Aωsinθ...(2.1)
Ev1=-Aωsin(θ-120)...(2.2)
Ew1=-Aωsin(θ+120)...(2.3)
Eu2=-Aωsin(θ+30)...(2.4a)
Ev2=-Aωsin(θ-90)...(2.5a)
Ew2=-Aωsin(θ+150)...(2.6a)

Note that when the phase relationship of the two systems is reversed, for example, the phase of the U2 phase (θ+30) becomes (θ−30). In that case, the back electromotive force generated in each phase of the second system is expressed by equations (2.4b) to (2.6b) instead of equations (2.4a) to (2.6a). Furthermore, a phase difference equivalent to 30[deg] is generalized and expressed as (30±60×k)[deg] (k is an integer). Alternatively, the second system may be arranged in the same phase as the first system .

Eu2=-Aωsin(θ-30)...(2.4b)
Ev2=-Aωsin(θ+90)...(2.5b)
Ew2=-Aωsin(θ-150)...(2.6b)

A lock actuator 710 that is driven by the H-bridge circuit 67 is composed of a winding 714 . When the lock actuator 710 is energized, a back electromotive force E1 proportional to the rotational speed ω1 is generated. When the proportionality constant is E, the back electromotive force E1 is expressed by the formula "E1=-Eω1". Further, the direct current applied to the lock actuator 710 is denoted as I1.

Next, circuit configuration examples 1 to 3 will be explained in order. In the ECU 101 of circuit configuration example 1 shown in FIG. 3, a three-phase inverter circuit 68 and an H-bridge circuit 67 are independently provided for a common power source Bt. The three-phase inverter circuit 68 and the H bridge circuit 67 are connected to the positive electrode of the power source Bt via the high potential line Lp, and to the negative electrode of the power source Bt via the low potential line Lg. The power source Bt is, for example, a battery with a reference voltage of 12 [V]. The DC voltage input from the power supply Bt to the three-phase inverter circuit 68 is referred to as "input voltage Vri," and the DC voltage input to the H-bridge circuit 67 is referred to as "input voltage Vrd."

The three-phase inverter circuit 68 converts the DC power of the power source Bt into three-phase AC power through the operation of a plurality of bridge-connected high-potential side and low-potential side inverter switching elements IUH, IUL, IVH, IVL, IWH, and IWL. Then, the steering assist actuator 800 is energized. On the power supply Bt side of the three-phase inverter circuit 68, a capacitor Ci is provided between the high potential line Lp and the low potential line Lg.

Specifically, inverter switching elements IUH, IVH, and IWH are upper arm elements provided on the high potential side of U phase, V phase, and W phase, respectively, and inverter switching elements IUL, IVL, and IWL are upper arm elements provided on the high potential side of U phase, V phase, and W phase, respectively. This is a lower arm element provided on the low potential side of the W phase and the W phase. Hereinafter, the upper arm element and lower arm element of the same phase will be collectively referred to as "IUH/L, IVH/L, and IWH/L." Further, a set of switching elements on the high potential side and the low potential side connected in series is referred to as a "leg". "IUH/L" corresponds to the code of the U-phase leg.

Between the lower arm elements IUL, IVL, and IWL of each phase of the three-phase inverter circuit 68 and the low potential line Lg, there are current sensors SAU, SAV, and SAW that detect phase currents Iu, Iv, and Iw flowing through each phase. is set up. The current sensors SAU, SAV, and SAW are composed of shunt resistors, for example.

In the current path between the power supply Bt and the capacitor Ci, a power supply relay Pir is connected in series on the power supply Bt side, and a reverse connection protection relay PiR is connected in series on the capacitor Ci side. The power supply relay Pir and the reverse connection protection relay PiR are constituted by semiconductor switching elements such as MOSFETs, mechanical relays, and the like, and are capable of cutting off current from the power supply Bt to the three-phase inverter circuit 68 when turned off. The power relay Pir interrupts the current flowing in the direction when the electrodes of the power source Bt are connected in the normal direction. The reverse connection protection relay PiR blocks current flowing when the electrodes of the power source Bt are connected in a direction opposite to the normal direction.

H-bridge circuit 67 includes two legs consisting of four switching elements. One leg is composed of a high potential side switching element 1Ha and a low potential side switching element 1La, and the other leg is composed of a high potential side switching element 1Hb and a low potential side switching element 1Lb. A lock actuator 710 is connected between the midpoints of each leg.

In the lock actuator 710, for example, the direction of the current I1 that is energized when the switching elements 1Ha and 1Lb are turned on is the positive direction, and the direction of the current I1 that is energized when the switching elements 1Hb and 1La are turned on is the negative direction. do. The lock actuator 710 rotates in the normal direction when it is energized in the positive direction, and rotates in the reverse direction when it is energized in the negative direction. For example, when the lock actuator 710 rotates in the normal direction, the lock device 20 is locked, and when the lock actuator 710 rotates in the reverse direction, the lock device 20 is unlocked.

Current sensors SA1a and SA1b that detect the direct current I1 are installed between the low potential side switching elements 1La and 1Lb of each leg and the low potential line Lg. Current sensors SA1a and SA1b are configured with shunt resistors, for example. The current sensors SA1a and SA1b may be installed between the high potential side switching elements 1Ha and 1Hb and the high potential line Lp. On the power supply Bt side of the H-bridge circuit 67, a capacitor Cd is provided between the high potential line Lp and the low potential line Lg. A power supply relay Pdr and a reverse connection protection relay PdR are connected in series in the current path between the power supply Bt and the capacitor Cd.

Each phase inverter switching element IUH/L, IVH/L, IWH/L of the three-phase inverter circuit 68 and each switching element of the H bridge circuit 67 is, for example, a MOSFET. In addition, the switching element may be a field effect transistor, IGBT, or the like other than MOSFET. Here, the current flowing through the lock actuator 710 is smaller than the phase current flowing through the steering assist actuator 800. Therefore, each switching element of the H-bridge circuit 67 may be a switch having a smaller current capacity than the inverter switching elements IUH/L, IVH/L, and IWH/L. Further, since it is sufficient to be able to lock and release, high-speed switching is not necessary, and a switch or mechanical relay with a slow on time may be used.

In the ECU 102 of circuit configuration example 2 shown in FIG. 4, one leg of the H-bridge circuit 67 is shared with the U-phase leg of the three-phase inverter circuit 68. For convenience of illustration, the symbol "67" appears to refer to the non-shared leg, but in reality it refers to the combined portion of the U-phase leg and the non-shared leg of the three-phase inverter circuit 68. There is. In the circuit configuration example 2, the number of switching elements can be reduced compared to the circuit configuration example 1.

In this specification, a power conversion circuit configured by sharing one phase (for example, U-phase) leg of the three-phase inverter circuit 68 and one leg of the H-bridge circuit 67 is referred to as an "integrated power conversion circuit". "circuit". In circuit configuration example 2, one system of three-phase inverter circuit 68 and H-bridge circuit 67 constitutes an "integrated power conversion circuit 650." The control unit 30 does not operate the three-phase inverter circuit 68 and the H-bridge circuit 67 individually, but operates the integrated power conversion circuit 650 as a whole.

The non-shared leg of the H-bridge circuit 67 includes a switching element MU1H on the high potential side and a switching element MU1L on the low potential side, which are connected in series via the DC motor terminal M1. Hereinafter, a set of switching elements constituting the non-shared leg will be referred to as a "DC motor switch ." Similar to the inverter switching element, the high-potential side and low-potential side switches are collectively referred to as "MU1H/L" for the DC motor switching element. As the DC motor switch MU1H/L, a switch having a smaller current capacity than the inverter switches IUH/L, IVH/L, and IWH/L may be used.

A first terminal T1, which is one end of the lock actuator 710, is connected to a branch point Ju of the U-phase current path of the three-phase winding set. A second terminal T2, which is an end of the lock actuator 710 opposite to the first terminal T1, is connected to a DC motor terminal M1 between the DC motor switch MU1H/L. DC motor switch MU1H/L is connected to U-phase winding 811 via lock actuator 710. The "U" in the code "MU1H/L" of the DC motor switch means U phase, and "1" is the number of the DC motor.

In circuit configuration example 2, with respect to the phase currents Iu, Iv, and Iw flowing through the three-phase inverter circuit 68, the phase currents flowing through the three-phase winding set are expressed as Iu#, Iv#, and Iw#. In the example of FIG. 4, a part of the phase current Iu is separated as a DC motor current I1 at a branch point Ju of the U-phase current path. The relationship between the inverter phase currents Iu, Iv, Iw flowing to the three-phase inverter circuit 68 side at the branch point Ju and the motor phase currents Iu#, Iv#, Iw# flowing to the steering assist actuator 800 side at the branch point Ju is as follows. , expressed by equations (3.1) to (3.4).

Iu#=-Iv-Iw...(3.1)
Iv#=Iv...(3.2)
Iw#=Iw...(3.3)
I1=Iu-Iu#...(3.4)

In the lock actuator 710, the direction of the current I1 flowing from the first terminal T1 to the second terminal T2 is defined as a positive direction, and the direction of the current I1 flowing from the second terminal T2 toward the first terminal T1 is defined as a negative direction. A voltage Vx is applied between the first terminal T1 and the second terminal T2 of the lock actuator 710. The lock actuator 710 rotates in the normal direction when it is energized in the positive direction, and rotates in the reverse direction when it is energized in the negative direction.

In the ECU 103 of circuit configuration example 3 shown in FIG. 5, a "first circuit" 68 (see FIG. 6 for the reference numeral) that energizes the steering assist actuator 800 is composed of two three-phase inverter circuits 681 and 682. The first system three-phase inverter circuit 681 is connected to the U1 phase, V1 phase, and W1 phase windings 811, 812, and 813 of the three-phase winding set 801. The second system three-phase inverter circuit 682 is connected to the U2 phase, V2 phase, and W2 phase windings 821, 822, and 823 of the three-phase winding set 802.

The first system three-phase inverter circuit 681 is provided with inverter switching elements IU1H/L, IV1H/L, IW1H/L, and current sensors SAU1, SAV1, and SAW1 that detect phase currents Iu1, Iv1, and Iw1. ing. A capacitor C1 is provided on the power supply Bt side of the three-phase inverter circuit 681. Further, a power supply relay P1r and a reverse connection protection relay P1R are provided between the power supply Bt and the three-phase inverter circuit 681. The DC voltage input from the power supply Bt to the three-phase inverter circuit 681 is referred to as "input voltage Vr1." Phase currents Iu1#, Iv1#, and Iw1# are applied to the three-phase winding set 801.

The symbols of the components of the second system and the symbols of the currents are represented by replacing "1" in the symbols of the components and currents of the first system with "2". Furthermore, the explanation regarding the components of the first system is used for the components of the second system.

The first terminal T1, which is one end of the lock actuator 710, is connected to the branch point Ju of the U1 phase current path of the three-phase winding set 801 of the first system, as in the second circuit configuration example. A second terminal T2, which is an end of the lock actuator 710 opposite to the first terminal T1, is connected to a DC motor terminal M1 between the DC motor switch MU1H/L. In the configuration of FIG. 5, no other DC motor is connected to the three-phase winding set 802 of the second system.

Further, one leg of the H bridge circuit 67 is shared with the U1 phase leg of the first system three-phase inverter circuit 681. In this manner, in circuit configuration example 3, the two systems of three-phase inverter circuits 681 and 682 and the H-bridge circuit 67 constitute an "integrated power conversion circuit 660." The control unit 30 operates the integrated power conversion circuit 660 in a comprehensive manner.

[Actuator drive control]
Next, drive control of the steering assist actuator 800 and the lock actuator 710 will be described with reference to FIG. 7. As mentioned in the description of FIGS. 1 and 2, the control unit 30 acquires the vehicle speed V from the vehicle speed sensor 14 and the steering torque Ts from the torque sensor 94. The control unit 30 also obtains the steering angle (equivalent value ) θs. The control unit 30 controls the operation of the steering assist actuator 800 by operating the three-phase inverter circuit 68, which is a "first circuit", based on the vehicle speed V and the steering torque Ts.

During operation of the three-phase inverter circuit 68, the control unit 30 energizes the lock actuator 710 through the H-bridge circuit 67 in accordance with the steering angle (equivalent value ) θs to operate the lock device 20. The operation of the lock device 20 mechanically restricts the rotation of the steering wheel by the driver. Next, the mechanical configuration and effects of the locking device 20 will be explained.

[Mechanical configuration of locking device]
First, with reference to FIGS. 8 to 10, the overall configuration of the locking device 20 common to each embodiment will be described. As shown in FIG. 8, the lock device 20 has a movable part 21 and a locked body 25. The movable part 21 is reciprocated by a lock actuator 710. The locked body 25 is rotatably provided coaxially with the steering wheel 91, for example.

The locked body 25 has one or more convex portions 27 and one or more concave portions 28 disposed in the circumferential direction, and rotates in the Rs direction following the steering. Note that FIG. 8 shows the shape of the locked object of the first embodiment as a representative of the locked object 25. As shown in FIG. In the second and third embodiments, the shapes of the locked objects are replaced.

As an example of the configuration of the movable part 21, FIGS. 8 and 9 show an example in which the rotation axis Az of the lock actuator 710, which is a motor, and the axis Ax of rotation and reciprocation of the movable part 21 are arranged orthogonal to each other. The motor output shaft 715 of the lock actuator 710 rotates forward and backward in the Rz direction about the rotation axis Az. The motor output shaft 715 and the driven gear section 215 of the movable section 21 constitute a worm gear, and the driven gear section 215 rotates forward and backward in the Rx direction about the rotation axis Ax as the motor output shaft 715 rotates. .

When the driven gear section 215 rotates, the coaxially fixed male threaded section 216 rotates, and the nut section 217 that is screwed into the male threaded section 216 reciprocates in the Lx direction. A rod-shaped projection 23 is connected to the distal end side of the nut portion 217 via the elastic portion 22 . When no external force is applied to the protrusion 23, the protrusion 23 reciprocates in the Lx direction together with the nut portion 217.

The elastic portion 22 is composed of a coil spring or the like, and urges the protrusion 23 in a direction away from the nut portion 217 by elastic force. Therefore, when an external force that pushes the protrusion 23 toward the nut portion 217 is applied, the elastic portion 22 is compressed. Note that illustration of a guide structure and the like for guiding the protrusion 23 to move straight on the axis Ax via the elastic portion 22 is omitted.

The rotation axis O of the locked body 25 is arranged to be perpendicular to the extension line of the axis Ax of the movable part 21. Depending on the rotational position of the locked body 25, the radially outer wall of the convex portion 27 or the concave portion 28 faces the tip surface of the protrusion 23. Here, moving the protrusion 23 closer to the locked object 25 is defined as forward movement, and moving away from the locked object 25 as the protrusion 23 moves backward. In other words, the above-mentioned elastic portion 22 urges the protrusion 23 in the forward direction by its elastic force. The control unit 30 energizes the lock actuator 710 using the H-bridge circuit 67 to move the protrusion 23 formed on the movable unit 210 forward or backward relative to the locked body 25 .

When the protrusion 23 moves forward, the protrusion 23 contacts the convex portion 27 or the concave portion 28 of the locked object 25, or the protrusion 23 fits between adjacent convex portions 27 or into the concave portion 28, which is a “locked state”. Become. Note that “between adjacent convex portions 27” and “concave portion 28” have substantially the same meaning, but as will be described later, there are two different interpretations of convex portions 27 and concave portions 28 in consideration of differences in interpretation. Also include the expression. At this time, rotation of the steering wheel 91 at least in the direction toward the end is mechanically restricted. When the protrusion 23 retreats, the protrusion 23 becomes separated from the locked body 25, which is a "released state". At this time, the steering wheel 91 becomes freely rotatable.

The flowchart in FIG. 10 shows operation control of the locking device 20 by the control unit 30. The symbol "S" indicates a step. In S1, the control unit 30 obtains the steering angle θs. As described above, the steering angle θs means a “steering angle equivalent value ” and includes a value calculated from a detection value of a steering angle sensor, a rotation angle of the steering assist actuator 800, and the like. As shown in FIG. 8, the steering angle θs is defined depending on the rotation direction of the steering wheel 91 with respect to the neutral position, for example, a clockwise rotation direction is defined as positive, and a counterclockwise rotation direction is defined as negative.

In S2, the control unit 30 determines whether the absolute value |θs| of the steering angle is larger than a threshold value set near the end. If YES is determined in S2, the control unit 30 moves the protrusion 23 of the movable part 21 of the locking device 20 forward relative to the locked body 25 in S3, thereby setting the locking state. If NO is determined in S2, the control unit 30 moves the protrusion 23 of the movable part 21 back from the locked body 25 in S4, thereby setting it in the released state.

In the locking devices 20 of each embodiment, the shape of the locked body 25 is different. Hereinafter, as the code for the locked body of each embodiment, the third digit following "25" is given the number of the embodiment to distinguish it. In the drawings of each embodiment, regarding the movable part 21, only the protrusion 23 or only the protrusion 23 and the elastic part 22 are illustrated. Substantially the same configurations in each embodiment are given the same reference numerals, and description thereof will be omitted.

(First embodiment)
The first embodiment will be described with reference to FIGS. 11 and 12. The locked object 251 of the first embodiment has a rotationally symmetric general gear shape. That is, in the locked body 251, a plurality of convex portions 27 and a plurality of concave portions 28 are arranged alternately around the base cylinder portion 29 in the circumferential direction.

In this specification , from a perspective based on the small virtual circle φi that connects the outer periphery of the base cylinder portion 29, the convex portion 27 is expressed as “relatively projecting in the radial direction from the small virtual circle φi” and “the small virtual circle φi” is used as a reference point. The concave portion 28 formed along the virtual circle φi is relatively concave in the radial direction. In this case, the circumferential side wall 275 connecting the convex portion 27 and the concave portion 28 is considered to be an outer wall of the convex portion 27 . The description of this embodiment basically adopts this viewpoint.

On the other hand, when viewed based on the large imaginary circle φo that connects the radial outer wall 274 of the convex portion 27, it is expressed as ``the recess 28 is recessed in the radial direction relative to the large imaginary circle φo,'' and ``the large imaginary circle It can also be expressed as "the protrusion 27 formed along φo relatively protrudes in the radial direction". In this case, the circumferential side wall 275 connecting the convex portion 27 and the concave portion 28 is considered to be the inner wall of the concave portion 28 .

In this way, generally speaking, the gear-shaped convex portion 27 and the concave portion 28 can be interpreted relative to each other in terms of their radial positional relationship. In interpreting this embodiment, it shall be interpreted not only based on expressions directly used in this specification but also expressions that may be used when viewed from a different perspective.

Assume that the locked body 251 is being steered to rotate clockwise in the figure. In this case, regarding the direction of rotation of the locked body 251, the clockwise direction is referred to as the advancing direction, and the counterclockwise direction is referred to as the returning direction. When the steering angle θs approaches the end, when the control section 30 moves the protrusion 23 of the movable section 21 forward, the protrusion 23 comes into contact with the circumferential side wall 275 of the locked object 251, and the direction of movement of the locked object 251 is changed. limit the rotation of. This restricts the rotation of the steering wheel 91 in the direction toward the end.

At this time, the steering wheel 91 is required to be rotatable in the return direction away from the end. The rotation angle range from the position of the protrusion 23 to the circumferential side wall 275 adjacent in the return direction becomes the "return direction margin Mret." In order not to impede the steering for turning back, the control unit 30 needs to retreat the protrusion 23 within the margin Mret in the returning direction.

Furthermore, as shown in FIG. 12A, depending on the timing at which the protrusion 23 moves forward, the protrusion 23 may come into contact with the radial outer wall 274 of the convex portion 27. At this time, the elastic part 22 of the movable part 21 is compressed as the nut part 217 moves forward, thereby preventing the protrusion 23 from being damaged. When the locked body 251 rotates from the position shown in FIG. 12(a) and the projections 23 and the recesses 28 are aligned, the urging force of the elastic portion 22 causes the projections to rotate. 23 moves forward and fits between adjacent protrusions 27 or into recesses 28. As a result, the locked body 251 is locked.

(effect)
In the present embodiment, the control unit 30 energizes the lock actuator 730 through the "second circuit" 67 according to the steering angle (equivalent value ) θs while the "first circuit" 68 is operating, and make it work. Here, since the locking device 20 is disposed closer to the driver than the torque sensor 94, even if the driver applies torque in the locked state, the torque is not transmitted to the torque sensor 94. Therefore, the maximum output of steering assist actuator 800 calculated according to the detected value of torque sensor 94 can be lowered. Therefore, the actuator and drive circuit of the locking device 20 and the regulating machine can be downsized.

In this embodiment, the three-phase inverter circuit 68 that is the "first circuit" and the H bridge circuit 67 that is the "second circuit" are provided in the same housing 600. Thereby, the steering device 200 can be downsized, and the number of wiring components such as harnesses and connectors can be reduced.

The locking device 20 of this embodiment can mechanically restrict the rotation of the locked body 251 with a simple configuration using the movable part 21 that is reciprocated by the lock actuator 710. In particular, the locked body 251 of the first embodiment has a rotationally symmetric general gear shape, and there is no need to adjust the initial rotational position to match the neutral position of the steering wheel 91, so assembly is easy. .

(Second embodiment)
Next, a second embodiment will be described with reference to FIG. 13. In the first embodiment, the "return direction margin Mret" is small, and the time available for moving the protrusion 23 forward and backward is short. Therefore, it is necessary to improve control responsiveness and followability of the lock actuator 710 and the movable part 21 so that the protrusion 23 of the movable part 21 moves at high speed. Therefore, in the second embodiment, a configuration is adopted in which a large "margin Mret in the return direction" can be ensured.

The locked body 252 of the second embodiment has a convex portion in a two-stage structure in a part of the circumferential direction, compared to the locked body 251 of the first embodiment. That is, a continuous convex portion 270 is formed continuously in the circumferential direction along the large imaginary circle φo, and an outer convex portion 26 that protrudes further radially outward from the continuous convex portion 270 is formed. The outer convex portion 26 is arranged approximately at the circumferential center of the continuous convex portion 270. Furthermore, although illustration of the detailed structure is omitted, the movable portion 21 is configured so that the stroke of the protrusion 23 can be switched in at least two stages.

As shown in FIG. 13(a), near the neutral position, the protrusion 23 of the movable part 21 faces the recess 28 on the opposite side of the outer convex part 26 with the rotation axis O in between. When the three-phase inverter circuit 68 is stopped, for example, when the steering wheel 91 is held at a neutral position while the steering wheel 91 is stopped, the projection 23 moves forward and fits between the adjacent projections 27 of the locked body 252 or into the recess 28. and becomes locked.

As shown in FIG. 13(b), when the steering angle θs approaches the end during operation of the three-phase inverter circuit 68, the protrusion 23 moves forward, and the circumferential side wall 265 of the outer convex portion 26 of the locked body 252 moves forward. It comes into contact with and becomes locked. At this time, the angular range of a little less than one circumference excluding the outer convex portion 26 becomes the "return direction margin Mret."

Therefore, in the second embodiment, a large "return direction margin Mret" can be secured, and the time available for moving the protrusion 23 forward and backward becomes longer. Therefore, the control responsiveness and followability of the lock actuator 710 and the movable part 21 can be lowered, and the degree of freedom in design is increased.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. 14. In the second embodiment, although the "return direction margin Mret" is increased, it is necessary to switch the stroke of the protrusion 23 into two stages, which complicates the structure and movement of the mechanism and drive circuit of the movable part 21. Therefore, in the third embodiment, the second embodiment is improved, and a configuration is adopted in which switching of the stroke of the protrusion 23 is not necessary while ensuring a large "return direction margin Mret".

The locked body 253 of the third embodiment has a hollow structure in which some of the convex portions 27 are removed compared to the locked body 251 of the first embodiment. That is, continuous recesses 280 with relatively long intervals are formed between one isolated convex portion 27S and two adjacent convex portions 27 in both circumferential directions. In the example of FIG. 14, another convex portion 27 is provided at a position just opposite to the isolated convex portion 27S across the rotation axis O, but a concave portion 28 is provided at a position exactly opposite to the isolated convex portion 27S. may be formed.

As shown in FIG. 14(a), in the vicinity of the neutral position, the protrusion 23 of the movable portion 21 faces the recess 28 on the opposite side of the isolated protrusion 27S with the rotation axis O in between. When the three-phase inverter circuit 68 is stopped, for example, when the steering wheel 91 is held in the neutral position while the steering wheel 91 is stopped, the protrusion 23 moves forward and fits between the adjacent protrusions 27 of the locked body 253 or into the recess 28. and becomes locked. As shown in FIG. 14(b), when the steering angle θs approaches the end, the protrusion 23 moves forward and comes into contact with the circumferential side wall 275 of the isolated convex portion 27S of the locked body 253, resulting in a locked state. At this time, the angular range of the continuous recessed portion 280 becomes the "return direction margin Mret."

The relative relationship between the circumferential positions of the convex portions 27 and 27S and the concave portion 28 of the locked body 253 and the position of the protrusion 23 of the movable portion 21 changes depending on the steering angle θs of the steering wheel 91. When the steering wheel 91 approaches the neutral position, the protrusion 23 approaches the recess 28. When the steering wheel 91 leaves the neutral position, the protrusion 23 approaches the isolated convex portion 27S.

In the third embodiment, it is possible to secure a larger "margin Mret in the return direction" than in the first embodiment, and the time available for advancing and retracting the protrusion 23 becomes longer, which improves control responsiveness and lock actuator 710 and The followability of the movable part 21 can be lowered. Furthermore, compared to the second embodiment, since there is no need to change the stroke of the protrusion 23, the configuration becomes simpler.

(Other embodiments)
(a) The "steering amount sensor" in the present invention is not limited to the torque sensor 94 that detects the steering torque Ts, but may be any sensor that detects some amount generated in the driver's steering operation. In other words, the control unit 30 may recognize the degree of steering performed by the driver from the detected value of the steering amount sensor, and control the operation of the steering assist actuator 800 accordingly. For example, a steering angle sensor may be used as the steering amount sensor.

(b) As described above, the steering angle θs of the steering wheel 91 includes a value calculated from the detection value of the steering angle sensor, the rotation angle of the steering assist actuator 800, and the like. In addition, any corresponding value having a correlation, such as a rack stroke or a tire turning angle, may be used for the steering angle θs. Furthermore, the "steering" that the driver steers includes not only the steering wheel 91 but also various shapes of steering sticks.

(c) FIG. 15 shows a rack type EPS system 901RC corresponding to a modification of FIG. 2. In the EPS system 901RC of FIG. 15, the steering assist actuator 800 and the torque sensor 94 are arranged at 97 on the steering rack similarly to the EPS system 901R of FIG. On the other hand, the locking device 20 is arranged on the steering column 93. That is, the locking device 20 is disposed closer to the driver than the torque sensor 94, and the same effects as in the embodiment described above can be obtained.

(d) The steering assist actuator 800 is not limited to a multi-phase motor such as a three-phase motor, but may be composed of a DC motor or an actuator other than a motor. Similarly, the lock actuator 710 is not limited to a DC motor, and may be configured with an actuator other than a motor, such as a linear cylinder.

(e) The relative arrangement of the lock actuator 710 and the movable part 21 of the lock device 20 and the configuration regarding power transmission are not limited to those illustrated in FIGS. 8 and 9. For example, the motor output shaft of the lock actuator 710 and the axis of the movable part 21 of the lock device 20 may be arranged in parallel, and the power may be transmitted by a parallel gear. Alternatively, when the lock actuator 710 is configured as a linear actuator, the reciprocating motion output shaft of the lock actuator 710 may be directly connected to the axis of the movable part 21.

(f) The relative arrangement of the protrusion 23 of the movable part 21 and the rotation axis O of the locked body 25 is not limited to that illustrated in FIG. 8 . For example, the axis of the movable part 21 and the rotation axis O of the locked body 25 may be arranged in parallel, and the protrusion 23 may be fitted into the recess 28 from the axial direction to be in the locked state.

(g) In the second and third embodiments with reference to FIGS. 13 and 14, for the sake of clarity, the explanation was made on the assumption that the end is a position where the steering wheel 91 rotates approximately 180 degrees or approximately 540 degrees from the neutral position. . However, the rotation angle from the neutral position to the end is not limited to 180 degrees or 540 degrees, and the rotation angle of the steering wheel 91 from the neutral position to the end is not limited to 180 degrees or 540 degrees. A large margin Mret in the return direction can be secured depending on the movable range.

(h) A three-phase motor relay or a DC motor relay may be added to the circuit configuration examples shown in FIGS. 3 to 5, or an LC filter circuit may be added to the input section. Further, the first circuit and the second circuit may not be connected to a common power source Bt but may be connected to separate power sources. In circuit configuration examples 2 and 3, a DC motor other than the lock actuator 710 may be connected to the same phase as the lock actuator 710, a different phase of the same system as the lock actuator 710, or one or more phases of another system.

The present invention is not limited to such embodiments, and can be implemented in various forms without departing from the spirit thereof.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

200... Steering device,
20...lock device,
30...control unit,
67...H bridge circuit (second circuit),
68 (681, 682)... three-phase inverter circuit (first circuit),
710...lock actuator,
800... Steering assist motor (steering assist actuator),
91...Steering wheel (steering),
94...Torque sensor (steering amount sensor).

Claims (11)

a steering amount sensor (94) that detects the amount generated in the driver's steering;
a steering assist actuator (800) that electrically assists the driver in steering according to the detected value of the steering amount sensor;
a locking device (20) that is placed closer to the driver than the steering amount sensor and mechanically restricts rotation of the steering wheel;
a lock actuator (710) that drives the lock device;
a first circuit (68, 681, 682) that energizes the steering assist actuator;
a second circuit (67) that energizes the lock actuator;
a control unit (30) that operates the first circuit and the second circuit to control operations of the steering assist actuator and the lock actuator;
Equipped with
The control unit energizes the lock actuator through the second circuit so as to place the lock device in a locked state when the absolute value of the steering angle equivalent value is larger than a threshold value while the first circuit is operating; A steering device in which the second circuit energizes the lock actuator so that the lock device is released when the absolute value of the steering angle equivalent value is equal to or less than the threshold value. The steering device according to claim 1, wherein the steering amount sensor is a torque sensor that detects a driver's steering torque. The steering assist actuator is a motor,
The steering device according to claim 1 or 2, wherein the steering angle equivalent value is a value calculated from a rotation angle of the steering assist actuator. The locking device includes:
a movable part (21) that reciprocates by the lock actuator;
One or more convex portions (27) relatively protruding in the radial direction and one or more concave portions (28) relatively concave in the radial direction are arranged in the circumferential direction and rotate following the steering wheel. It has a locked body (25),
The control unit energizes the lock actuator using the second circuit to move the protrusion (23) formed on the movable part forward toward the locked object or away from the locked object. retreat,
When the protrusion moves forward, the protrusion comes into contact with the convex part or the concave part of the locked object, or the protrusion enters a locked state between adjacent convex parts or into the concave part,
The steering device according to any one of claims 1 to 3, wherein when the protrusion retreats, the protrusion is in a released state in which it is separated from the locked object. The movable part has an elastic part (22) that urges the protrusion in the forward direction by elastic force,
When the to-be-locked body rotates from the position where the protrusion abuts the radial outer wall (274) of the convex portion and the protrusion and the concave portion are aligned, the biasing force of the elastic portion causes the The steering device according to claim 4, wherein the protrusion fits between the adjacent convex portions or into the concave portion. When the protrusion moves forward during operation of the first circuit, the protrusion comes into contact with a circumferential side wall (275, 265) of the convex part or the concave part and enters the locked state,
5. The steering device according to claim 4, wherein when the projection moves forward while the first circuit is stopped, the projection fits between the adjacent projections or into the recess to enter the locked state. The relative relationship between the circumferential position of the convex part and the concave part of the locked body and the position of the protrusion of the movable part changes depending on the steering angle of the steering wheel (91),
When the steering wheel approaches the neutral position, the protrusion approaches the recess;
The steering device according to claim 4, wherein the protrusion approaches the convex portion when the steering wheel leaves the neutral position. The steering device according to any one of claims 1 to 7, wherein the first circuit and the second circuit are provided in the same casing (600). The steering device according to any one of claims 1 to 8, wherein the steering assist actuator and the locking device are both arranged on a steering column (93). The steering device according to any one of claims 1 to 8, wherein the steering assist actuator and the locking device are both arranged in a steering rack (97). Steering device according to any one of the preceding claims, wherein the steering assist actuator is arranged on a steering rack (97) and the locking device is arranged on a steering column (93).

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