JP3505992B2 - Vehicle steering system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system capable of varying a transmission ratio of a steering angle of a steering wheel to steered wheels.

[0002]

2. Description of the Related Art Conventionally, there is a steering device disclosed in Japanese Patent Application Laid-Open No. 3-153467 as a steering device for varying a transmission ratio of a steering wheel steering angle to a steered wheel. This steering device is provided with a transmission ratio variable mechanism by a planetary gear type differential mechanism on a steering shaft between a steering handle and a pinion connected to a steering wheel.

[0003]

However, in this steering device, since the variable transmission ratio mechanism is of the differential type, the variable transmission ratio mechanism does not operate in the case where an excessive reverse input is applied from the wheel side during traveling. If an excessive load is applied, the transmission ratio variable mechanism may be moved by this load, and the relationship between the steering amount of the steering wheel and the steering amount of the steered wheels may shift.

An object of the present invention is to provide a vehicle for which the relationship between the steering amount of the steering wheel and the steering amount of the steered wheels can be maintained even when an excessive load is input to the transmission ratio varying means during traveling. A steering device is provided.

[0005]

[0006]

[0007]

[0008]

[0009]

A vehicle steering system according to the present invention comprises differential transmission ratio varying means provided on a steering shaft connecting a steering handle and steered wheels to vary a transmission ratio by driving a motor. A reversal drive detection means for detecting that the motor of the transmission ratio variable means is reversibly driven by a load due to an input from a road surface while a control signal is output to the transmission ratio variable means,
An operation limiting unit that limits the operation of the transmission ratio varying unit when the reverse drive detecting unit detects the reverse drive of the motor. The steering shaft has an upper steering shaft connected to the steering handle and a lower steering shaft connected to the steered wheels, and the transmission ratio varying means is provided between the upper steering shaft and the lower steering shaft. It is preferable that the torque transmission is configured to be performed through the motor housing and the rotor, and the transmission ratio is changed by driving the motor.

According to the vehicle steering system of the present invention , when the reverse drive detecting means detects that the motor of the transfer ratio varying means starts to be reversely driven by the load, the operation limiting means operates the transfer ratio varying means. Since the operation is limited, it is possible to prevent the motor of the transmission ratio varying means from being reversely driven.

[0011] Operation slip limiting means, a one-way restriction mechanism that allows only rotation in a predetermined direction pair can be assumed that the direction of rotation allowed is arranged to differ.

In this case , since the operation limiting means is composed of the pair of one-way limiting mechanisms, the rotation of the motor in the right direction is limited by the one-way limiting mechanism, and the rotation of the motor in the left direction is the other one-way limiting mechanism. Limited by Therefore, in either case where the rotation in the right direction is the rotation in the reversing direction and the rotation in the left direction is the rotation in the reversing direction, one of the pair of one-way limiting mechanisms is selected. Thus, the reverse drive of the motor can be restricted.
In addition, the operation limiting means rotates together with the rotor of the motor.
The rotary member having an engaging recess in the radial direction of the rotor and the engaging recess.
It has an engaging protrusion that engages and can swing on the motor housing.
And a swing member attached to the
Yes. The reversal detection by the reversal drive detection means determines the target steering angle and
Deviation from the steering angle, rotation direction, or motor
Can be done by the supply current value and the number of rotations of the motor
It

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A vehicle steering system according to a first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of a vehicle steering system 2. In the figure, reference numeral 10 indicates a steering handle, and the steering handle 10 is connected to the upper end of the upper steering shaft 12a. Also,
The lower end of the upper steering shaft 12a is connected to the variable gear ratio unit 14, and the upper end of the lower steering shaft 12b is connected to the variable gear ratio unit 14.

A pinion (not shown) is provided at the lower end of the lower steering shaft 12b, and the pinion is meshed with the rack bar 18 in the steering gear box 16. Further, one ends of tie rods 20 are connected to both ends of the rack bar 18, and steering wheels 24 are connected to the other ends of the tie rods 20 via knuckle arms 22.

A steering angle sensor 26 for detecting the steering angle of the steering handle 10 is provided on the upper steering shaft 12a, and the lower steering shaft 12a.
The output angle sensor 3 for detecting the steering angle of the steered wheels 24 is shown at b.
0 is provided. The steering angle of the steering wheel 10 and the steering angle of the steered wheels 24 detected by the steering angle sensor 26 and the output angle sensor 30 are input to an ECU (electronic control unit) 28. Furthermore, the vehicle speed output from the vehicle speed sensor 32 that detects the vehicle speed is input to the ECU 28. On the other hand, the ECU 28 outputs a control signal for controlling the variable gear ratio unit 14 to the variable gear ratio unit 14.

The variable gear ratio unit 14 is shown in FIG.
As shown in FIG. 3, the motor 40 and the speed reducer 42 are provided. The motor 40 is configured to include a stator 46 and a rotor 48 fixed in a motor housing 44, and the reduction gear 42 is configured as a reduction gear using a planetary gear mechanism. That is, the rotating shaft 50 that rotates together with the rotor 48 is fixed to the sun gear 52, and the planet gear 54 meshes with the sun gear 52 and the ring gear 56 formed on the inner peripheral surface of the motor housing 44. The planet gear 54 is rotatably attached to the carrier 58.

Also, the rotor 4 in the motor housing 44
The lock mechanism shown in FIG. That is, the swing member 60 having an arch shape and having the engaging projection 60a on the inner side of the arch shape is disposed above the rotor 48 in the motor housing 44. The swing member 60 has a pin 44 on the motor housing 44 at one end.
It is swingably attached by a and has an electromagnetic coil 62 at the other end. The plate-shaped magnet 6 fixed to the motor housing 44 is provided above the electromagnetic coil 62.
4 are opposed to each other, and a metal plate 66 fixed to the stator 46 is opposed to the lower part of the electromagnetic coil 62.

Further, one end of a spring member 67 is attached to the end of the swinging member 60 on the side having the electromagnetic coil 62, and the other end of the spring member 67 is attached to the inner wall surface of the motor housing 44. The swing member 60 is attached to the rotary shaft 5.
It is biasing in the direction of 0.

On the other hand, on the upper surface of the rotor 48 of the motor 40, there is provided a rotating member 68 fixed to the rotating shaft 50 and rotating together with the rotor 48. This rotating member 68 includes
Engagement recess 68 that engages with the engagement protrusion 60a of the swing member 60
a is provided in several places (four places in the figure).

The motor housing 4 on the side of the motor 40
4 is connected to the upper end of the lower steering shaft 12b, and the carrier 58 is connected to the lower end of the upper steering shaft 12a via a universal joint (not shown).

In this vehicle steering system 2, first,
When the vehicle speed detected by the vehicle speed sensor 32 and the steering angle detected by the steering angle sensor 26 are input to the ECU 28, the ECU 28 calculates a target steering angle based on the vehicle speed and the steering angle, and the target steering angle is set to this target steering angle. A control signal based on this is output to the variable gear ratio unit 14. Based on this control signal, the motor 40 of the variable gear ratio unit 14 is driven to give the steered wheels 24 a steering angle corresponding to the target steering angle.

In this vehicle steering system 2, the ECU
28 determines whether or not there is a reverse input (kickback) from the side of the steered wheels 24 and determines whether the motor 40 has a failure. That is, the steering wheel 1 detected by the steering angle sensor 26
Steering is performed when the deviation between the target steering angle obtained based on the steering angle of 0 and the vehicle speed detected by the vehicle speed sensor 32 and the steering angle of the steered wheels 24 detected by the output angle sensor 30 is a predetermined value or more. It is determined that an excessive reverse input is applied from the wheel 24 side, and the failure of the motor 40 is determined based on the current value supplied to the motor 40. The motor 4
For the 0 failure, the motor is locked due to foreign matter being caught,
The failure of the ECU 28, the steering angle sensor 26, the output angle sensor 30, etc. is included.

The ECU 28 energizes the electromagnetic coil 62 as shown in FIG. 3 when no excessive reverse input is applied from the steered wheel 24 side and when the motor 40 is not in failure. Allows the metal plate 66 to be attached to the electromagnetic coil 62.
A force along the direction acts. Thereby, the swing member 60
Is the motor housing 4 against the spring force of the spring member 67.
4 is swung in the direction of the inner peripheral wall, that is, in the direction away from the rotating member 68, and the engagement between the engaging protrusion 60a of the swinging member 60 and the engaging recess 68a of the rotating member 68 is released.

Therefore, when there is no excessive reverse input from the steered wheels 24 side and when the motor 40 is not in failure,
The steered wheels 24 are steered by the transmission ratio determined based on the vehicle speed via the variable gear ratio unit.

On the other hand, when it is determined that there is an excessive reverse input from the steered wheel 24 side and when it is determined that the motor 40 has failed, the spring of the spring member 67 is stopped by stopping the energization of the electromagnetic coil 62. The swinging member is swung by the force in the direction of the rotating member 68 about the pin 44a, and the engaging convex portion 60a of the swinging member 60 and the engaging concave portion 68a of the rotating member 68 are engaged. That is, the swinging member 60 is the rotating member 6
When the rocking member 6 is rocked in the direction of
When the position of 0a coincides with the position of the engaging concave portion 68a of the rotating member 68, the engaging convex portion 60a and the engaging concave portion 68a directly engage with each other, and the position of the engaging convex portion 60a of the swinging member 60 changes. When the position of the engaging concave portion 68a of the rotating member 68 does not match, the rotating member 68 rotates to cause the engaging convex portion 60a.
When the position of is coincident with the position of the engaging recess 68a, the engaging protrusion 60a and the engaging recess 68a are engaged.

As a result, when it is determined that there is an excessive reverse input from the steered wheel 24 side and when it is determined that the motor 40 has failed, the motor housing 44 and the rotor 48.
Are directly connected. Therefore, the operation of the variable gear ratio unit 14 is stopped and the steering wheel 10 and the steered wheels 24 are directly connected, and even if there is an excessive reverse input from the side of the steered wheels 24, the phase shift due to the reverse input is caused. Can be prevented.

Further, since the steering wheel 10 and the steered wheels 24 are directly connected when the motor 40 fails, even if the motor 40 fails, steering can be performed with a fixed transmission ratio.

Further, a magnet 64 and an electromagnetic coil 62 provided on the rocking member 60 are used in a mechanism for directly connecting the rotating shaft 50 of the motor 40 and the motor housing 44, and the rocking member 60 is energized by energizing the electromagnetic coil 62. To use the swing,
The amount of movement of the swinging member 60 can be increased, and the size can be reduced as compared with the case where a solenoid actuator or the like is used.

When the excessive reverse input from the steered wheels 24 disappears and the cause of the failure of the motor 40 disappears, the ECU 28 restarts the energization of the electromagnetic coil and the swinging member 60 moves. The engagement between the engagement protrusion 60a and the engagement recess 68a of the rotary member 68 is released. As a result, the operation of the variable gear ratio unit 14 is restarted.

In the above embodiment, the motor housing 44 on the side of the motor 40 is connected to the upper end of the lower steering shaft 12b, and the carrier 5
Although 8 is connected to the lower end of the upper steering shaft 12a, the same control as in the above-described embodiment can be performed in the variable gear ratio unit 14 even if this connection relationship is reversed.

Further, in the above-mentioned embodiment, the metal plate 66 is arranged so as to face the stator 46 below the electromagnetic coil 62, but this metal plate may be changed to a magnet.
In this case, since the magnetic flux density increases, the swing member 60
The force for rocking can be increased. Further, the metal plate 66 fixed to the stator 46 below the electromagnetic coil 62 can be omitted.

In the above-described embodiment, the rocking member 60 is provided with the electromagnetic coil 62 and the motor housing 44 is provided with the magnet 64. However, the electromagnetic coil 62 is provided in the motor housing 44 and the rocking member 60 is provided. Magnet 64
May be provided.

Further, in the above-described embodiment, one end of the spring member 67 is attached to the end of the swinging member 60 on the side having the electromagnetic coil 62, and the swinging member 60 is attached to the rotary shaft 50 by this spring member 67. However, the present invention is not limited to this, and the swinging member 60 may be biased toward the motor housing 44 side by the spring member 67. In this case, when it is determined that there is an excessive reverse input from the steered wheel 24 side, the energization of the electromagnetic coil 62 is started, and the swing member 60 is moved against the spring force of the spring member 67. The engaging protrusion 60a of the oscillating member 60 and the engaging recess 68a of the rotating member 68 are engaged with each other by swinging in the direction of the rotating member 68.

Next, a vehicle steering system 4 according to a second embodiment of the present invention will be described with reference to FIGS. The vehicle steering system 4 according to the second embodiment is similar to the variable gear ratio unit 14 of the vehicle steering system 2 according to the first embodiment as shown in FIG. A rotation speed detection device 14a that detects the rotation speed of the motor that configures 14 and a rotation direction detection device 14b that detects the rotation direction of the motor are provided. Since the other parts are the same as the configuration of the vehicle steering system 2 according to the first embodiment, FIG. 2 used in the description of the vehicle steering system 2 according to the first embodiment.
4 will be described using the reference numerals attached to the respective components.

As shown in FIG. 6, E of the vehicle steering system 4
When the CU 28 is outputting a control signal to the motor 40 of the variable gear ratio unit 14 (step S
10) The rotation number NE of the motor 40 is detected by the rotation number detection device 14a (step S11).

Next, it is determined whether the lock flag RF is zero, that is, whether the lock flag RF is set (step S12). If the lock flag RF is determined to be zero, it is determined whether the rotation speed NE of the motor 40 detected in step S11 is zero (step S13), and the rotation speed NE of the motor 40 is determined to be zero. If so, the lock mechanism is operated (step S1
4). That is, by stopping the energization of the electromagnetic coil 62 of the variable gear ratio unit 14, the oscillating member is rotated about the pin 44a by the spring force of the spring member 67.
The engaging projection 60a of the swing member 60 and the engaging recess 68a of the rotating member 68 are engaged with each other by swinging in the direction of 8 (see FIG. 4). Therefore, as shown in FIG. 7, when the load torque acting on the motor 40 increases, the load torque reduces the rotation speed of the motor 40, and when the rotation speed of the motor 40 becomes zero, that is, the lock mechanism operates. In the region, the motor housing 44 and the rotor 48 are directly connected.

Next, the ECU 28 sets the lock flag RF (step S15), and the rotation direction detecting device 14b.
The rotation direction immediately before the motor 40 stopped detected by is stored (step S16).

When it is determined in step S12 that the lock flag RF is not zero, that is, the lock flag RF is set, it is determined in step S11 whether the rotational speed NE of the motor 40 detected is zero. When it is determined that the rotation speed NE of the motor 40 is not zero (begins to rotate) (step S17), the rotation direction of the motor 40 detected by the rotation direction detection device 14b is stored in step S16. It is determined whether or not the direction is reversed (step S18).

If it is determined that the reverse rotation has started, the locking of the lock mechanism is continued, and if it is determined that the normal rotation starts, the lock of the lock mechanism is released (step S19). That is, by starting to energize the electromagnetic coil 62 of the variable gear ratio unit 14, the swinging member 60 is swung in the direction away from the rotating member 68 about the pin 44a against the spring force of the spring member 67. , The engaging convex portion 60a of the swinging member 60 and the engaging concave portion 6 of the rotating member 68
The engagement with 8a is released (see FIG. 3). Then, the lock flag RF is reset (step S20).

Therefore, even if an excessive load torque is applied to the motor 40 of the variable gear ratio unit 14, it is possible to prevent the motor 40 from rotating in the reverse direction due to this load torque, and the motor 40 is excessively large. The steering wheel 10 can be steered even when the load torque is applied. Further, since the lock mechanism is operated to lock or release the lock while the motor 40 is stopped, it is possible to prevent the shock from being transmitted to the steering wheel 10. Further, since only one circuit can drive the lock mechanism, the manufacturing cost can be reduced.

Next, a vehicle steering system according to a third embodiment of the present invention will be described with reference to FIGS. The vehicle steering system according to the third embodiment is
The lock mechanism of the vehicle steering system 2 according to the first embodiment is changed to the lock mechanism shown in FIG. Since the other parts are the same as the configuration of the vehicle steering system 2 according to the first embodiment, FIG. 2 used in the description of the vehicle steering system 2 according to the first embodiment.
4 will be described using the reference numerals attached to the respective components.

This lock mechanism is composed of a pair of lock mechanisms 78 and 79 which allow rotation in only one direction. That is, one lock mechanism 78 (allowing rotation in the right direction) has one end swingably attached to the motor housing 44 and the other end having the engaging portion 80a.
A magnet 82 fixed to the rocking member 80, an electromagnetic coil 84 fixed to the motor housing 44, and a spring member 8 connecting the motor housing 44 and the rocking member 80.
6, the other lock mechanism 79 (allows leftward rotation) has a swing member 81 having one end swingably attached to the motor housing 44 and the other end having an engaging portion 81a. A magnet 83 fixed to the moving member 81,
An electromagnetic coil 85 fixed to the motor housing 44,
The spring member 87 connects the motor housing 44 and the swing member 81.

The ECU 28 of the vehicle steering system according to the third embodiment outputs the control signal to the motor 40 of the variable gear ratio unit 14 as shown in FIG. S30), the value of the current supplied to the motor 40 is detected, and the rotation speed detection device 14
The rotation speed NE of the motor 40 is detected by a (step S31). Next, the load torque acting on the motor 40 is calculated (step S32). That is, the load torque is calculated based on the detected current value and the rotation speed NE of the motor 40.

Next, when the calculated load torque is equal to or greater than the predetermined value (step S33), the rotation direction detecting device 14
The rotation direction of the motor 40 is detected by b (step S
34).

If it is determined that the rotation direction of the motor 40 is rightward, the lock mechanism 78 is operated (step S35). That is, the spring member 8 is started by energizing the electromagnetic coil 84 that constitutes the lock mechanism 78.
The rocking member 80 is rocked in the direction of the rotating member 68 against the spring force of the rocking member 6, and the engaging portion 80a of the rocking member 80 is rotated.
8 is located in the engaging recess 68a (see FIG. 8).

In this case, when the motor 40 continues to rotate to the right, the rotation of the motor 40 is not restricted by the lock mechanism 78, but when the motor 40 starts to rotate to the left, that is, reverses. , The motor 40 by the lock mechanism 78
Rotation is limited.

In step S34, the motor 40
When it is determined that the rotation direction of is the left direction, the lock mechanism 79 is operated (step S36). That is, by starting the energization of the electromagnetic coil 85 constituting the lock mechanism 79, the rocking member 8 is resisted against the spring force of the spring member 87.
1 is swung in the direction of the rotating member 68, and the engaging portion 81a of the swinging member 81 is positioned in the engaging recess 68a of the rotating member 68. In this case, if the motor 40 continues to rotate to the left, the lock mechanism 79 does not limit the rotation of the motor 40. However, if the motor 40 starts to rotate to the right, that is, reverses, the lock mechanism 79 does not rotate. The rotation of the motor 40 is restricted by 79.

Therefore, as shown in FIG.
When the load torque acting on the motor is increased and the rotational speed of the motor 40 is reduced by this load torque, that is, in the lock mechanism operating range, the motor housing 44 and the rotor
Are engaged, and the reverse rotation of the motor is prevented. In addition, since the lock mechanism is configured by the pair of lock mechanisms 78 and 79 that allows only one direction of rotation, the lock mechanism can be operated during rotation of the motor 40, and the lock mechanism operating range can be widened. You can

[0050]

[0051]

[0052]

According to the present invention, when the reversal drive detecting means detects that the motor of the transmission ratio varying means starts to be reversed driven by the load, the operation limiting means limits the operation of the transmission ratio varying means. Therefore, it is possible to prevent the motor of the transmission ratio varying means from being reversely driven.

Further, the operation limiting means is rotated in a predetermined direction.
Rotation method that allows a pair of one-way limiting mechanisms that allow only
If they are arranged so that the directions are different, since the operation limiting means is composed of a pair of one-way limiting mechanisms, when the rotation to the right is the rotation in the reverse direction and the rotation to the left is the rotation in the reverse direction. In any of the above cases, one of the pair of one-way limiting mechanisms can limit the reverse drive of the motor.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vehicle steering system according to a first embodiment.

FIG. 2 is a configuration diagram of a variable gear ratio unit of the vehicle steering system according to the first embodiment.

FIG. 3 is a schematic diagram of a lock mechanism of the variable gear ratio unit according to the first embodiment.

FIG. 4 is a view showing operating states of a rotating member and a swinging member of the lock mechanism of the variable gear ratio unit according to the first embodiment.

FIG. 5 is a configuration diagram of a vehicle steering system according to a second embodiment.

FIG. 6 is a flowchart for explaining control of the vehicle steering system according to the second embodiment.

FIG. 7 is a diagram for explaining a lock mechanism operation range in which a lock mechanism of the vehicle steering system according to the second embodiment is operated.

FIG. 8 is a schematic view of a lock mechanism of a variable gear ratio unit according to a third embodiment.

FIG. 9 is a flowchart for explaining control of the vehicle steering system according to the third embodiment.

FIG. 10 is a diagram for explaining a lock mechanism operating range in which a lock mechanism of the vehicle steering system according to the third embodiment is operated.

[Explanation of symbols]

2, 4 ... Steering device for vehicle, 10 ... Steering handle, 12a ... Upper steering shaft, 12b ... Lower steering shaft, 14 ... Variable gear ratio unit, 1
4a ... Rotation speed detection device, 14b ... Rotation direction detection device, 1
6 ... Steering gear box, 18 ... Rack bar, 2
0 ... Tie rod, 22 ... Knuckle arm, 24 ... Steering wheel, 26 ... Steering angle sensor, 28 ... ECU, 30 ... Output angle sensor, 32 ... Vehicle speed sensor, 40 ... Motor, 42 ... Reducer, 60 ... Oscillating member, 60a ... Engagement convex part, 62 ... Electromagnetic coil, 64 ... Magnet, 68 ... Rotating member, 68a ... Engagement concave part.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Toko Kawamuro, Toyota City, Toyota City, Aichi Prefecture, Toyota Toyota Motor Corporation (56) References JP-A-5-124534 (JP, A) JP-A-6 -1254 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B62D 5/22 B62D 6/00

Claims (7)

(57) [Claims] 1. A differential transmission ratio varying means provided on a steering shaft connecting a steering wheel and a steering wheel to vary a transmission ratio by driving a motor, and a control signal is output to the transmission ratio varying means. The reverse rotation drive detection means for detecting that the motor of the transmission ratio variable means is reversely driven by the load from the road surface in the state of being driven, and the reverse drive detection means detects the reverse drive of the motor. In some cases, an operation limiting unit that limits the operation of the transmission ratio changing unit, and a vehicle steering system. 2. The steering shaft has an upper steering shaft connected to the steering handle and a lower steering shaft connected to the steered wheels, and the transmission ratio varying means includes the upper steering shaft and the lower steering. 2. The vehicle steering system according to claim 1, wherein torque transmission to and from the shaft is configured to be performed via a motor housing and a rotor, and the transmission ratio is varied by driving the motor. apparatus. 3. The operation limiting means comprises a pair of one-way limiting mechanisms for permitting only rotation in a predetermined direction so that the permitted rotation directions are different. The vehicle steering system according to item 1. 4. The housing of the motor, wherein the operation limiting means includes a rotating member that rotates with the rotor of the motor and has an engaging recess in the rotor radial direction, and an engaging protrusion that engages with the engaging recess. The vehicle steering system according to claim 1 or 2, further comprising: a swinging member that is swingably attached to the vehicle. Wherein said inversion detecting means, the deviation between the target steering angle and the steering angle, according to claim 1 in which said motor and detecting that it has been inverted driven by the load by the input from the road surface The vehicle steering system according to any one of 4 above. Wherein said inversion detecting means includes a rotational direction detecting means for detecting a rotational direction of the motor, the detection result of said rotational direction detecting means, the motor is reversed driving the load by the input from the road surface The vehicle steering apparatus according to any one of claims 1 to 4, wherein the fact that it is detected is detected. 7. The reversal drive detection means detects that the motor has been reversibly driven by a load due to an input from a road surface, based on a value of a current supplied to the motor and a rotation speed of the motor. The vehicle steering system according to any one of claims 1 to 4.