JP5382435B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus.

A transmission ratio control motor for changing a rotation transmission ratio in a vehicle steering apparatus having a transmission mechanism including a planetary gear mechanism capable of changing a rotation transmission ratio in the middle of a steering shaft connecting a steering member and a steering mechanism There has been proposed a vehicle steering apparatus provided with a lock mechanism that locks a change in rotation transmission ratio when an abnormality occurs in the vehicle (for example, Patent Documents 1 and 2).
Further, when the relative rotation angle between the input member and the output member is equal to or less than a predetermined set angle, the lock member is disposed at a rotation allowable position that allows rotation of the components of the planetary gear mechanism, and the relative rotation angle is There has been proposed a vehicle steering apparatus in which a lock member is disposed at a rotation prevention position that prevents rotation of the constituent element when the set angle is exceeded (Patent Document 3).

  In Patent Document 1, a lock pin is inserted into a slot of a screw gear as the engine is stopped to lock a transmission ratio control motor. In addition, a diagnostic circuit for generating a maximum torque on the motor shaft at the time of starting the engine and confirming that the transmission ratio control motor does not move and thereby determining that the lock is normal is provided.

Japanese National Patent Publication No. 2006-521957 JP 2008-24058 A JP 2002-145102 A

  The diagnostic circuit of Patent Document 1 can diagnose that the lock pin is normally locked, but cannot diagnose whether or not the lock pin is normally unlocked. Therefore, even when the ECU outputs a lock release command signal, the lock pin may be locked. In this case, if the ECU tries to perform rotation control of the transmission ratio control motor, a larger current than usual flows in the transmission ratio control motor, and as a result, the transmission ratio control motor may be burned out.

On the other hand, when the tire is riding on an obstacle such as a curb with the maximum turning angle of the tire, if the handle (steering member) is further rotated, the angle of the tire does not change, only the handle Occurs. In this case, the driver feels a great sense of discomfort.
Also, when traveling on a high μ road (road coefficient of friction on the road surface, such as a bad road such as a stone pavement) (especially climbing uphill), the load of the transmission ratio control motor increases and the transmission ratio control motor burns out. There is a fear.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle steering apparatus that can prevent the transmission ratio control motor from being burned out and increase the reliability of fail-safe.

In order to achieve the above object, the present invention provides an input shaft (3a) that rotates in response to an operation of the steering member (2) and an output shaft (3b) that rotates in conjunction with the operation of the steering mechanism (9). A transmission ratio variable mechanism (13) interposed between the input shaft and the output shaft; a transmission ratio control motor (14) capable of changing the transmission ratio of the transmission ratio variable mechanism; A lock mechanism (29) capable of locking the rotation of the transmission ratio control motor, a rotational position detection device (34) for detecting the rotational position (θ) of the rotor of the transmission ratio control motor, the transmission ratio control motor, and the lock A control unit (30) for controlling the mechanism, wherein the control unit can set a lock mode for locking the lock mechanism and a lock release mode for releasing the lock, and the control unit With the start of An initial diagnosis unit (41) for diagnosing the operation of the lock mechanism, and after confirming that the initial diagnosis unit is set to the unlock mode, the rotor of the transmission ratio control motor is The rotational position detection device outputs a rotational displacement command for rotating the first predetermined angle (A1) exceeding the play amount (B) of the rotor when locked by the locking mechanism, and outputs the rotational displacement command. When the change amount (Δθ) of the detected value is less than the first predetermined angle, the first abnormality of the lock mechanism is detected, and the initial diagnosis unit is set to the lock mode. After confirming, a rotational displacement command for rotating the rotor of the transmission ratio control motor by a second predetermined angle (A2) exceeding the play amount of the rotor when locked by the locking mechanism is output. The change amount of the detection value of the rolling displacement commands the rotational position detecting device with the can, when more than the amount of play, to provide a vehicle steering system (1) for detecting a second abnormality in the lock mechanism.

  In the present invention, in the initial diagnosis associated with the activation of the control unit, when the lock mechanism is in the locked state in spite of the lock release mode, this can be detected as the first abnormality. If the control unit tries to control the rotation of the transmission ratio control motor when the lock mechanism is in the locked state even though it is in the unlocking mode, a larger current than normal flows through the transmission ratio control motor. The transmission ratio control motor may burn out. On the other hand, in the present invention, the first abnormality can be detected at the time of the initial diagnosis associated with the activation of the control unit, that is, before the vehicle starts to be driven. It becomes possible. Therefore, occurrence of burning of the transmission ratio control motor can be prevented as much as possible, and as a result, reliable fail safe can be realized.

In addition, the initial diagnosis unit confirms that the lock mode is set, and then secondly exceeds a play amount of the rotor when the rotor of the transmission ratio control motor is locked by the lock mechanism. When the amount of change in the detected value of the rotational position detecting device accompanying the rotational displacement command exceeds the play amount, a second displacement of the lock mechanism is output. Since an abnormality is detected , there are the following advantages. That is, in the initial diagnosis, when the lock mechanism is not in the locked state in spite of the lock mode, this can be detected as the second abnormality. Since the second abnormality can be detected at the time of the initial diagnosis accompanying the activation of the control unit, that is, before the vehicle starts to travel, it is possible to deal with repairs or the like according to the second abnormality. Therefore, reliable fail safe can be realized.

Further, the lock mechanism can lock the rotor at a plurality of lock positions arranged at equal intervals in the circumferential direction of the rotor, and the control unit can perform the second diagnosis of the lock mechanism by the initial diagnosis unit. when an abnormality is detected, there is a case of outputting the rotational displacement command for rotating the rotor of the transmission ratio control motor by a third predetermined angle greater than the rotational angle corresponding to the spacing (claim 2). When the second abnormality that the lock mechanism is not in the locked state is detected in spite of being in the lock mode, the rotor of the transmission ratio control motor is moved to a third angle greater than the rotation angle corresponding to the lock position arrangement interval. Displace by a predetermined angle. Thereby, if the lock mechanism is operating normally, the lock mechanism is locked at the adjacent lock position. It becomes possible to eliminate the temporary lock failure naturally.

A temperature detection device (35) for detecting the temperature of the transmission ratio control motor; and a current detection device (36) for detecting a current of the transmission ratio control motor, wherein the control unit includes the temperature detection device. The transmission ratio control motor is determined to be abnormal on the basis of the detected temperature (T) by the sensor and the current detected by the current detector (i), and a lock command signal is output to the lock mechanism in response to the determination of the abnormality. In some cases, the transmission ratio control motor has a fail-safe function for reducing the current to zero (claim 3 ). In this case, monitoring of the state of the transmission ratio control motor becomes more reliable, and therefore, even under conditions of traveling on a high μ road (a road with a high friction coefficient, for example, a bad road such as a stone pavement) Occurrence of overheat burning of the transmission ratio control motor can be prevented in advance, and as a result, reliable fail safe can be realized.

In addition, a torque sensor (32) for detecting a torque (P) loaded on the steering shaft is provided, and the control unit outputs an output value of the torque sensor at a predetermined value when the fail-safe function is executed. with the proviso that it (P1) hereinafter, may have a function to cancel the fail-safe function, and controls the transmission ratio of the transmission ratio control motor (claim 4). When the lock mechanism is locked by fail-safe, if the driver exerts a large steering input on the steering shaft (when the output value of the torque sensor is greater than or equal to the predetermined value), the driver loses his coolness. It is determined that the lock mechanism is locked to ensure safety. On the other hand, when the steering input by the driver is low (when the output value of the torque sensor is less than the predetermined value), it is determined that the driver has returned to calm, the lock mechanism is released, and the transmission ratio control is performed. The motor is returned to the normal control state (that is, the transmission ratio control state). That is, even if the fail-safe function for avoiding the emergency state is executed, when it is determined that the state is returned to a state where safe steering is possible, the normal control is returned.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles of one embodiment of the present invention. It is a schematic sectional drawing of a transmission ratio variable mechanism. FIG. 3A is a schematic diagram of the lock mechanism and the output gear to be locked, and FIG. 3B is a schematic diagram for explaining the play amount of the output gear locked at the time of locking. It is a flowchart which shows the flow of the return operation | movement from a fail safe operation | movement and a fail safe operation | movement. It is a flowchart which shows operation | movement of an initial diagnosis. It is a flowchart which shows the flow of the operation | movement of burnout prevention of a transmission ratio control motor.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus according to an embodiment of the present invention.
Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, and an intermediate shaft. A rack shaft as a steered shaft extending in the left-right direction of the automobile, having a pinion shaft 7 connected to 5 through a universal joint 6 and a rack 8a meshing with the pinion 7a provided in the vicinity of the end of the pinion shaft 7 8. The pinion shaft 7 and the rack shaft 8 constitute a turning mechanism 9 including a rack and pinion mechanism.

The rack shaft 8 is supported in a housing (not shown) fixed to the vehicle body through a plurality of bearings (not shown) so as to be capable of linear reciprocation along the axial direction X1. A tie rod 10 is coupled to each end of the rack shaft 8. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion in the axial direction X1 of the rack shaft 8 by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.

  In addition, the vehicle steering apparatus 1 is capable of applying a steering assist force to the rack shaft 8, and the ratio of the steering angle of the steered wheels 11 to the steering angle of the steering member 2 (the electric pump-type steering assist mechanism 12 ( A transmission ratio variable mechanism 13 capable of changing the transmission ratio). The transmission ratio variable mechanism 13 includes a transmission ratio control motor 14 that can change the transmission ratio. The transmission ratio variable mechanism 13 is integrally provided with a reaction force control motor 15 that can apply a steering reaction force to the steering member 2.

The steering shaft 3 is divided into two shafts: an input shaft 3a on the steering member 2 side and an output shaft 3b on the steering mechanism 9 side.
The steering assist mechanism 12 will be specifically described. In the middle of the pinion shaft 7, a torsion bar 16 that twists according to the direction and magnitude of the steering torque applied to the steering member 2, and an opening degree according to the direction and magnitude of the twist of the torsion bar 16. A hydraulic control valve 17 that changes is interposed.

  The hydraulic control valve 17 is connected to a power cylinder 18 that gives a steering assist force to the steering mechanism 9. The power cylinder 18 includes a piston 19 provided integrally with the rack shaft 8, and a pair of oil chambers 20 and 21 defined by the piston 19. The pair of oil chambers 20 and 21 are connected to the hydraulic control valve 17 via corresponding oil passages 22 and 23, respectively. The hydraulic control valve 17 is connected to a hydraulic pump 24 and a reservoir tank 25 for generating a steering assist force through corresponding oil passages 26 and 27, respectively.

  The hydraulic pump 24 is composed of, for example, a gear pump, is driven by the electric motor 28, pumps out the hydraulic oil stored in the reservoir tank 25, and supplies the hydraulic oil to the hydraulic control valve 17. The hydraulic control valve 17 connects the hydraulic pump 24 to one of the oil chambers 20 and 21 and connects the reservoir tank 25 to either one of the oil chambers 20 and 21 according to the twist direction of the torsion bar 16. Switch the oil passage inside. The steering assist mechanism 12 is configured by the hydraulic control valve 17, the power cylinder 18, the hydraulic pump 24, and the electric motor 28.

  The vehicle steering apparatus 1 includes a lock mechanism 29 that can lock the rotation of the transmission ratio control motor 14. The vehicle steering apparatus 1 includes a steering control unit 30 that controls steering by controlling the operations of the transmission ratio control motor 14, the reaction force control motor 15, and the lock mechanism 29, and the hydraulic pump 24 of the steering assist mechanism 12. A steering assist control unit 31 that controls the operation of the electric motor 28 is provided. The steering control unit 30 and the steering assist control unit 31 are each configured by an electronic control unit (ECU: Electronic Control Unit), and are connected so as to be able to transmit signals to each other via, for example, an in-vehicle network.

  The steering control unit 30 includes a torque sensor 32 that detects a steering torque applied to the steering member 2, a rotation angle sensor 33 that detects a rotation angle of the output shaft 3 b of the steering shaft 3, and a rotor of the transmission ratio control motor 14. As a rotational position detecting device for detecting the rotational position, a rotational angle sensor 34 made of, for example, a resolver, a temperature sensor 35 for detecting the temperature of, for example, a motor housing of the transmission ratio control motor 14, and a current flowing through the transmission ratio control motor 14. A current sensor 36 serving as a current detection device to be detected and a running state sensor 37 for detecting a running state (vehicle speed, turning angle, etc.) of the vehicle are connected to each other, and detection signals from the sensors 32 to 37 are used for steering. It is input to the control unit 30.

  The steering control unit 30 includes a transmission ratio control unit 38 that controls the transmission ratio control motor 14 to control the transmission ratio, a reaction force control unit 39 that controls the reaction force control motor 15 to control the reaction force, and a lock mechanism. A mode setting unit 40 for setting a lock mode for locking 29 and a lock release mode for releasing the lock, and an initial diagnosis unit 41 for diagnosing an abnormality of the lock mechanism 29 when the system is activated.

FIG. 2 is a schematic sectional view of the transmission ratio variable mechanism 13. As shown in FIG. 2, the input shaft 3a and the output shaft 3b of the steering shaft 3 are supported so as to be coaxially rotatable with their tips opposed to each other.
The transmission ratio variable mechanism 13 includes an input sun gear 42a and an output sun gear 42b, a plurality of input planetary gears 43a and output planetary gears 43b that mesh with the gears 42a and 42b, and the input planetary gears 43a and the output planetary gears 43b. The carrier 45 is supported so as to be able to rotate along with the corresponding support shaft 44, and the transmission ratio control motor 14 that rotates the carrier 45 about its axis.

  The input sun gear 42a and the output sun gear 42b are provided at opposite ends of the input shaft 3a and the output shaft 3b, respectively. The input sun gear 42a rotates along with the input shaft 3a, and the output sun gear 42b rotates along with the output shaft 3b. As illustrated, the outer diameter of the input sun gear 42a is different from the outer diameter of the output sun gear 42b. Different numbers of teeth are formed on the outer circumferences of the input sun gear 42a and the output sun gear 42b, respectively.

  A plurality of input planet gears 43a are meshed with the input sun gear 42a, and a plurality of output planet gears 43b are meshed with the output sun gear 42b. Each input planetary gear 43a and the corresponding output planetary gear 43b are supported by a common support shaft 44. The plurality of input planetary gears 43 a and the plurality of output planetary gears 43 b are accommodated inside a hollow cylindrical carrier 45.

  The carrier 45 has support holes penetrating through the axial centers of the end walls 45a and 45b on both sides, and the input shaft 3a and the output shaft 3b are supported via bearings respectively supported by the support holes. . The carrier 45 and the two shafts 3a and 3b are relatively rotatable on the same axis of the two shafts 3a and 3b. On the outer periphery of the carrier 45, a transmission gear 46 is formed over the entire circumference, and the output gear 47 of the transmission ratio control motor 14 is meshed with the transmission gear 46.

  In the vehicle steering apparatus 1 configured as described above, when the steering member 2 is rotated for steering, the input shaft 3 a connected to the steering member 2 rotates, and the input sun gear of the transmission ratio variable mechanism 13 is rotated. 42a rotates. When the transmission ratio control motor 14 is in a non-driven state, the input planetary gear 43a meshing with the input sun gear 42a rotates around the support shaft 44 together with the output planetary gear 43b having the support shaft 44 in common. As a result of this rotation, a rotational force is applied to the output sun gear 42b meshing with the output planetary gear 43b, and the output shaft 3b provided with the output sun gear 42b rotates, and the above-described steering is performed according to this rotation.

  At this time, rotation transmission from the input shaft 3a to the output shaft 3b is performed at a specific rotation ratio determined by the number of teeth of the input sun gear 42a, the input planet gear 43a, the output planet gear 43b, and the output sun gear 42b. As a result, the steered wheels 11 are steered in the operation direction of the steering member 2 by an amount corresponding to the angle obtained by multiplying the steering angle of the steering member 2 by the rotation ratio. The transmission ratio to the steering wheel 11 is a constant value.

On the other hand, when the transmission ratio control motor 14 is driven to rotate the carrier 45, the input shaft 3a rotates around the respective support shafts 44 while rotating around the input sun gear 42a and the output sun gear 42b together with the carrier 45. It is transmitted to the output sun gear 42b and the output shaft 3b through the rotating input planetary gear 43a and output planetary gear 43b.
At this time, rotation transmission from the input shaft 3a to the output shaft 3b is performed at a rotation ratio that is increased or decreased by the rotation of the carrier 45 from the inherent rotation ratio described above, and the rotation ratio between the input shaft 3a and the output shaft 3b, That is, the transmission ratio from the steering member 2 to the steered wheel 11 can be changed steplessly.

  On the other hand, during traveling of the vehicle, the self-alignment torque and disturbance input of the steered wheels 11 are transmitted to the steering member 2 via the transmission ratio variable mechanism 13, and these forces are reaction force torques when the driver steers. Is acting as. As described above, when the transmission ratio of the transmission ratio variable mechanism 13 is changed, the reaction force torque acting on the steering member 2 changes according to the change in the transmission ratio. For example, when the transmission ratio control motor 14 is driven to change the transmission ratio to a large value, the reaction force torque acting on the steering member 2 increases, and thus the steering member 2 suddenly becomes heavy, which may cause the driver to feel uncomfortable. is there.

  In order to reduce such discomfort to the driver, the reaction force control motor 15 is provided. That is, as shown in FIG. 2, a reaction force gear 48 is fitted and fixed in the middle of the input shaft 3a, and an output gear 49 of the reaction force control motor 15 is engaged with the reaction force gear 48. is there. The reaction force control motor 15 is driven according to the drive of the transmission ratio control motor 14 and is input via the reaction force gear 48 so as to cancel the increase / decrease according to the increase / decrease of the reaction force torque acting on the steering member 2. The reaction force torque is applied to the shaft 3a.

As shown in FIG. 1, the input shaft 3a above the reaction force gear 48 is provided with the torque sensor 32 for detecting the steering torque applied to the steering member 2 on the input shaft 3a. As the torque sensor 32, a known twin resolver including two resolvers having different shaft angle multipliers (1/2 of the number of poles) can be used.
The twin resolver is configured by dividing the input shaft 3a into two upper and lower shafts connected by a torsion bar, and attaching a resolver to each of both shafts. The two resolvers detect the rotation angles of the two axes, calculate the relative angular displacement generated between the two axes in accordance with the torsion of the torsion bar, and calculate the steering torque. The detection signals from these two resolvers are obtained as signals in which the same number of waveforms as the shaft angle multiplier appear in one rotation. By combining these two signals, the aforementioned steering torque is obtained and the input shaft 3a is obtained. The rotation angle is obtained.

  The steering torque detected by the torque sensor 32 and the rotation angle of the input shaft 3a are given to the steering control unit 30 as shown in FIG. The rotation angle sensor 33 for detecting the rotation angle of the output shaft 3 b is attached to the output shaft 3 b below the transmission ratio variable mechanism 13, and the output shaft 3 b detected by the rotation angle sensor 33. The rotation angle is also given to the steering control unit 30. In addition, the steering control unit 30 is also provided with detection results of various traveling states that affect the steering, such as the vehicle speed and the turning angle detected by the traveling state sensor 37.

  The steering control unit 30 issues an operation command to the transmission ratio control motor 14 to perform steering according to the rotation operation of the steering member 2, and performs a transmission ratio control operation for rotationally driving the transmission ratio control motor 14 (transmission ratio control). Equivalent to the function of the unit 38). In this transmission ratio control operation, the steering angle of the steering member 2 obtained from the torque sensor 32 is applied to a predetermined control map to obtain a target transmission ratio, and the transmission ratio control motor 14 is driven to obtain this target transmission ratio. This is done by controlling. The traveling state detected by the traveling state sensor 37 is used to select a control map that gives a target transmission ratio.

  Further, the steering control unit 30 issues an operation command to the reaction force control motor 15 in order to apply a steering reaction force according to the steering angle to the steering member 2, and performs a reaction force control operation for rotationally driving the reaction force control motor 15. Performed (corresponding to the function of the reaction force control unit 39). This reaction force control operation is performed, for example, by obtaining a target steering reaction force according to a predetermined control map and drivingly controlling the reaction force control motor 15 so as to generate this target steering reaction force. The traveling state detected by the traveling state sensor 37 is used to select a control map for applying the target steering reaction force.

The transmission ratio control motor 14 is driven in accordance with an operation command given from the steering control unit 30 via a motor drive circuit (not shown), and acts on the transmission ratio variable mechanism 13 as described above, from the steering member 2 to the steered wheels 11. The operation is to change the transmission ratio of steplessly.
The reaction force control motor 15 is driven according to a control command given from the steering control unit 30 via a motor drive circuit (not shown) based on the detection result by the torque sensor 32, and acts on the input shaft 3a as described above to operate the steering member 2. An operation is performed to compensate for a change in the reaction force torque acting on the steering member 2 in accordance with the change in the transmission ratio.

  The transmission ratio control motor 14 is speed-controlled by the steering control unit 30 so that the rotational speed becomes high or low, for example, according to the slow speed of the vehicle speed, which is one of the detection results by the running state sensor 37. As described above, the transmission ratio from the steering member 2 to the steered wheels 11 becomes larger or smaller depending on the rotational speed of the transmission ratio control motor 14, so that the change in the steering angle with respect to the steering angle of the steering member 2 during low speed traveling. It is possible to make the driving operation easier. Further, when the vehicle is traveling at high speed, the change in the turning angle with respect to the operation of the steering member 2 can be reduced, and the unstable behavior of the vehicle due to abrupt steering can be prevented in advance, thereby improving traveling stability.

The rotation angle of the input shaft 3 a detected by the torque sensor 32 and the rotation angle of the output shaft 3 b detected by the rotation angle sensor 33 are used as feedback information for controlling the transmission ratio control motor 14.
The reaction force control motor 15 is drive-controlled by the steering control unit 30 so as to increase or decrease the reaction force torque applied to the input shaft 3a in accordance with the slow speed of the transmission ratio control motor 14. As a result, when the transmission ratio is increased during low speed traveling, the reaction torque acting on the input shaft 3a is reduced, and when the transmission ratio is decreased during high speed traveling, the reaction torque applied to the steering member 2 is increased. The reaction torque acting on the steering member 2 can be kept constant regardless of the change of the transmission ratio. Thus, even when the transmission ratio is changed, the driver does not feel uncomfortable.

The steering torque detected by the torque sensor 32 is used as feedback information for controlling the reaction force control motor 15 as information indicating the reaction force torque experienced by the driver operating the steering member 2.
The transmission ratio variable mechanism 13 as described above is provided with the lock mechanism 29 that restricts the differential between the input shaft 3a and the output shaft 3b. The lock mechanism 29 is a solenoid arranged to face the outer surface of the carrier 45. The lock mechanism 29 has a main body 50 fixed to the vehicle body and an output rod 51 protruding from the main body 50.

  As shown in FIGS. 3A and 3B, the lock mechanism 29 extends the output rod 51 in response to excitation, and rotates the tip of the extended output rod 51 along with the rotor of the transmission ratio control motor 14. The output gear 47 is engaged with any one of a plurality of lock holes 52 provided on the outer periphery 47a (portion where the gear teeth are not formed) to restrain the rotation of the transmission control motor 14. The lock holes 52 are arranged at equal intervals in the circumferential direction of the outer periphery 47 a of the output gear 47. For example, they are arranged at an arrangement interval corresponding to the rotation angle C (for example, 45 °) of the rotor of the transmission ratio control motor 14 (ie, the output gear 47). When the lock mechanism 29 restricts the rotation of the output gear 47 (transmission ratio control motor 14), the rotation of the carrier 45 is restricted accordingly.

As shown in FIG. 3B, the output gear 47 has a play amount B in the rotation direction in a state where the output rod 51 of the lock mechanism 29 is engaged with the lock hole 52.
Thus, when the steering member 2 is rotated in a state where the rotation of the carrier 45 is restricted by the operation of the lock mechanism 29, the input shaft 3 a connected to the steering member 2 rotates and the input of the transmission ratio variable mechanism 13 is rotated. The sun gear 42a rotates. By this rotation, the input planetary gear 43a meshing with the input sun gear 42a rotates together with the output planetary gear 43b having the common support shaft 44. By this rotation, a rotational force is applied to the output sun gear 42b that meshes with the output planetary gear 43b, and the output shaft 3b including the output sun gear 42b rotates, and steering is performed in accordance with this rotation.

  At this time, the rotation transmission from the input shaft 3a to the output shaft 3b is performed at a specific rotation transmission ratio determined by the number of teeth of the input sun gear 42a, the input planet gear 43a, the output planet gear 43b, and the output sun gear 42b. Is steered in the operation direction of the steering member 2 by an amount corresponding to an angle (steering angle) obtained by multiplying the operation amount (steering angle) of the steering member 2 by the rotation transmission ratio. That is, steering is performed by mechanical transmission from the steering member 2 to the steered wheels 11.

  During execution of the transmission ratio control for the transmission ratio control motor 14 and the reaction force control for the reaction force control motor 15, as shown in step S1 of the flowchart of FIG. When a failure diagnosis is performed to check whether or not the transmission ratio control motor 14 and the reaction force control motor 15 on the side have failed, the result of the failure diagnosis is that a failure has occurred (step in FIG. 4). In the case of YES in S1), in step S2 of FIG. 4, a fail-safe operation that stops erroneous transmission ratio control and reaction force control under the occurrence of a failure and issues an operation command to the lock mechanism 29 of the transmission ratio variable mechanism 13 Execute.

  Specifically, the transmission ratio control and the reaction force control are stopped by setting the control currents of the transmission ratio control motor 14 and the reaction force control motor 15 to zero. In addition, a lock mode for setting the lock mechanism 29 to the locked state is set, a lock command signal is output to the lock mechanism 29 according to the setting of the lock mode, and the output rod 51 of the lock mechanism 29 is inserted into the lock hole 52. Engage.

  Thereby, the rotation of the carrier 45 is restrained together with the output gear 47 of the transmission ratio control motor 14 of the transmission ratio variable mechanism 13. As a result, the rotation operation of the steering member 2 is transmitted to the steering mechanism 9 through deceleration by the transmission ratio variable mechanism 13. Therefore, emergency steering when stopping the steering control and the reaction force control accompanying the occurrence of the failure can be performed by manual steering by mechanical transmission from the steering member 2 to the steering mechanism 9.

At this time, the lock mechanism 29 restrains the rotation of the carrier 45 together with the output gear 47 of the transmission ratio variable mechanism 13, but a large force is not necessary for this rotation restraint. As the lock mechanism 29, an actuator having a small and simple configuration such as the solenoid described above can be used, and can be reliably realized without requiring a complicated configuration.
After performing the fail safe operation as described above, in step S3 of FIG. 4, the steering torque P is taken from the torque sensor 32, and in step S4, it is monitored whether or not the steering torque P becomes less than a predetermined value P1. The

  If the steering torque P is greater than or equal to the predetermined value P1 in step S4 (NO in step S4), the fail-safe operation is continued. In step S4, it is determined that the steering torque P is less than the predetermined value P1. In the case (YES in step S4), the fail safe operation is stopped, and as shown in step S5, the transmission ratio control and the reaction force control are started, the lock release mode is set, and the transmission ratio control motor 14 (output) is set. The rotational restraint of the gear 47 and the carrier 45) is released.

This is particularly effective in the following situations. That is, for example, when the steered wheel 11 rides on the curb, fail safe is executed, and the driver is steering the steering member 2 at the maximum steering angle.
As described above, when the lock mechanism 29 is in the locked state due to fail-safe, when the driver exerts a large steering input on the steering shaft (when the steering torque P is equal to or greater than the predetermined value P1), the driver In order to ensure safety, the transmission ratio control and the reaction force control are stopped and the lock by the lock mechanism 29 is maintained.

  On the other hand, when the steering input by the driver is low (when the steering torque P is less than the predetermined value P1), it is determined that the driver has returned to calm, the lock by the lock mechanism 29 is released, and transmission ratio control is performed. The motor 14 is returned to the normal control state (ie, the transmission ratio control state), the reaction force control motor 15 is returned to the normal control state (ie, the reaction force control state), and the lock by the lock mechanism 29 is released. The transmission ratio of the transmission ratio variable mechanism 13 is variable. That is, even if the fail-safe function for avoiding the emergency state is executed, when it is determined that the state is returned to a state where safe steering is possible, the normal control is returned.

In addition, when making it shift to manual steering by the above fail safe operation | movement, the steering feeling sensed by the driver | operator who operates the steering member 2 changes. Therefore, the steering control unit 30 performs alarm operations such as sounding an alarm sound and generating a voice message in parallel with the output of the operation command to the lock mechanism 29, and notifies the driver that the steering feeling changes. It is preferable to do.
Alternatively, one or both of the transmission ratio control motor 14 and the reaction force control motor 15 may be direct drive motors, and the rotational force may be directly transmitted to the corresponding input shaft 3a and output shaft 3b.

Further, the steering control unit 30 has a function (corresponding to the function of the initial diagnosis unit 41) for initial diagnosis of an abnormality of the lock mechanism 29 when the system is started, that is, when the ignition switch is turned on. .
Specifically, as shown in the flowchart of FIG. 5, the fail flag FF is initialized to 0 in step S <b> 1 as the system is started. Next, in step S2, it is determined whether or not the lock release mode is set. If it is confirmed that the lock release mode is set (YES in step S2), the rotational position of the rotor of the transmission ratio control motor 14 is determined in step S3 based on the signal of the rotation angle sensor 34 (for example, resolver) of the transmission ratio control motor 14. Capture θ and store it as the previous acquired value.

Next, in step S4, the rotor of the transmission ratio control motor 14 is rotationally displaced by the first predetermined angle A1. The first predetermined angle A1 is an angle that exceeds the play amount B (for example, B = 1 °) of the rotor of the transmission ratio control motor 14 when locked by the lock mechanism 29 (A1> B), for example, 5 °. Yes (A1 = 5 °).
After the rotor is rotationally displaced by the first predetermined angle A1 in this way, in step S5, the rotational position θ of the rotor of the transmission ratio control motor 14 is captured again. In step S6, the rotational position θ captured this time and the previous time A rotational position change amount Δθ between the acquired rotational position θ is calculated.

  When the calculated rotational position change amount Δθ is less than the first predetermined angle A1 (Δθ <A1) (YES in step S7), the lock mechanism 29 is in spite of the lock release mode. In step S8, the first abnormal signal is output. After that, in step S9, the fail flag FF is set to 1 (corresponding to the occurrence of a failure), and the process ends.

  On the other hand, when the calculated rotational position change amount Δθ is equal to or larger than the first predetermined angle A1 (in the case of NO in step S7 and Δθ ≧ A1), the lock mechanism 29 is in the unlock mode. It is determined that the lock mechanism 29 is functioning normally and the lock mechanism 29 is unlocked, and after a normal signal is output in step S10, the initial diagnosis process is terminated.

If it is determined in step S2 that the lock release mode is not set (NO in step S2), the process proceeds to step S11, and the transmission ratio control motor 14 is controlled based on the resolver signal of the transmission ratio control motor 14. The rotational position θ of the rotor is taken in and stored as the previous acquired value.
Next, in step S12, the rotor of the transmission ratio control motor 14 is rotationally displaced by the second predetermined angle A2. The second predetermined angle A2 is an angle exceeding the play amount B (for example, B = 1 °) of the rotor when locked by the lock mechanism 29 (A2> B), for example, 5 ° (A2 = 5 °). ).

After the rotor has been rotationally displaced by the second predetermined angle A2 in this way, in step S13, the rotational position θ of the rotor of the transmission ratio control motor 14 is captured again, and the rotational position θ acquired this time and the rotational position acquired last time. In step S14, the rotational position change amount Δθ with respect to θ is calculated.
The rotational position change amount Δθ calculated in step S14 is equal to or less than the play amount B (play amount of the rotor of the transmission ratio control motor 14 when locked by the lock mechanism 29) in step S15 (Δθ ≦ B). ) Is determined (NO in step S15), the process proceeds to step S10 to output a normal signal indicating that the lock mechanism 29 is normal, and then the initial diagnosis process is terminated.

On the other hand, when it is determined in step S15 that the rotational position change amount Δθ calculated in step S14 exceeds the play amount B (B <Δθ) (YES in step S15), the next step Proceed to S16.
In step S16, the rotor of the transmission ratio control motor 14 is rotationally displaced by a third predetermined angle A3. The third predetermined angle A3 is an angle equal to or greater than a rotation angle C (for example, 45 °) corresponding to the arrangement interval of the lock position by the lock mechanism 29 (A3 ≧ C).

If the lock mechanism 29 has not been locked due to a temporary abnormality, the rotor of the transmission ratio control motor 14 is rotationally displaced by the second predetermined angle A3 in step S16, thereby the transmission ratio control motor. 14 re-examines whether it is locked in the adjacent lock position.
That is, Steps S17 to S21, which are the same processes as Steps S11 to S15, are executed to determine again whether or not the lock mechanism 29 is in the locked state. As a result of the re-determination, when the rotational position change amount Δθ is equal to or less than the play amount B (Δθ ≦ B) (NO in step S21), it is determined that the lock mechanism 29 is normally locked, In step S10, after outputting a normal signal, the initial diagnosis process is terminated.

  As a result of the re-determination, if the rotational position change amount Δθ still exceeds the play amount B (B <Δθ) (YES in step S21), in step S22, the lock is set regardless of the lock mode. After outputting the second abnormal signal indicating that the mechanism 29 is not in the locked state, the fail flag FF is set to 1 in step S23, and the initial diagnosis process is terminated.

According to the present embodiment, in the initial diagnosis accompanying the activation of the steering control unit 30, when the lock mechanism 29 is in the locked state in spite of the unlocking mode, this is regarded as the first abnormality. Can be detected.
If the steering control unit 30 tries to control the rotation of the transmission ratio control motor 14 when the lock mechanism 29 is in the locked state even in the unlocking mode, the transmission ratio control motor 14 has a larger current than usual. As a result, the transmission ratio control motor 14 may burn out. On the other hand, in the present embodiment, at the time of the initial diagnosis accompanying the activation of the steering control unit 30, that is, before starting the running of the vehicle, the first abnormality (although the lock mechanism is in the unlocked mode) Therefore, it is possible to take measures such as repairs before traveling according to this. Therefore, it is possible to prevent the transmission ratio control motor 14 from being burned out as much as possible, and as a result, it is possible to realize a reliable fail safe.

  In addition, after confirming that the lock mode is set, the initial diagnosis unit 41 exceeds the rotor (output gear 47) play amount B when the transmission ratio control motor 14 is locked by the lock mechanism 29. When the rotation position change amount Δθ detected by the rotation angle sensor 34 accompanying the rotation displacement command exceeds the play amount B, the rotation mechanism command is output. A second abnormality is detected. That is, in the initial diagnosis, when the lock mechanism 29 is not in the locked state in spite of the lock mode, this can be detected as the second abnormality. Accordingly, since the second abnormality can be detected before the vehicle starts to travel, it is possible to cope with repairs and the like according to this, and as a result, a reliable fail safe can be realized.

  Further, when the second abnormality that the lock mechanism 29 is not in the locked state is detected in spite of the lock mode as described above, the transmission ratio control motor 14 corresponds to the arrangement interval of the lock position. The rotation is displaced by a third predetermined angle A3 that is equal to or greater than the rotation angle C. Thereby, if the lock mechanism 29 is operating normally, the lock mechanism 29 is locked at the adjacent lock position. Thereby, it becomes possible to eliminate the temporary lock failure naturally.

  Further, the steering control unit 30 has a function of preventing the transmission ratio control motor 14 from burning out. Specifically, referring to the flowchart of FIG. 6, in step S1, the temperature T detected by the temperature sensor 35 is captured, and in step S2, whether or not the temperature T is equal to or higher than a predetermined temperature T1 is determined. Determined. When the temperature T is equal to or higher than the predetermined temperature T1, the process proceeds to step S14, and the fail flag FF is set to 1.

  On the other hand, if it is determined in step S2 that the temperature T is lower than the predetermined temperature T1 (T <T1) (NO in step S2), a timer (timer count) is started (step S3). In step S6, the current i detected by the current sensor 36 is captured (step S4) until the time is up (timer count up) (for example, 30 seconds), and the current integrated value W is calculated (step S5). Repeat the operation.

Next, in step S7, it is determined whether or not the current integrated value W accumulated until the time is up is equal to or greater than a predetermined value W1. If it is determined in step S7 that the integrated current value W is greater than or equal to the predetermined value W1 (YES in step S7), the process proceeds to step S14, and the fail flag FF is set to 1.
If it is determined in step S7 that the current integrated value W is less than the predetermined value W1 (NO in step S7), a timer (timer count) is started (step S8), and then in step S12. Until the time is up (timer count up) (for example, for 30 seconds), the current i detected by the current sensor 36 is captured (step S9), and the deviation Δi between the current i value acquired this time and the previous acquired value is obtained. The operation of calculating (step S10) is repeated.

If the deviation Δi remains less than the predetermined value Δi1 (i <Δi1) and the time is up (timer count up) (YES in step S12), the process proceeds to step S13, and the fail flag FF is set to 0. Set to.
On the other hand, if the deviation Δi is equal to or greater than the predetermined value Δi1 before the time is up (YES in step S11), the process proceeds to step S14, and the fail flag FF is set to 1.

  According to the present embodiment, when any one of the temperature, current, and current integrated value of the transmission ratio control motor 14 meets the corresponding condition, the fail safe is executed. Therefore, the transmission ratio control motor 14 Monitoring of the state of is reliable. Therefore, even when the vehicle travels on a high μ road (a road with a high coefficient of friction on the road surface, for example, a rough road such as a stone pavement) (especially, traveling on an uphill), the transmission ratio control motor 14 is not overheated. As a result, reliable fail safe can be realized.

  The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the lock mechanism 29 locks the output gear 47 that rotates together with the transmission ratio control motor 14, but the present invention is not limited thereto. The rotor of the transmission ratio control motor 14 may be locked, the carrier 45 of the transmission ratio variable mechanism 13 may be locked, and other transmission elements of the transmission ratio variable mechanism 13 may be locked. You may make it lock. In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 3 ... Steering shaft, 3a ... Input shaft, 3b ... Output shaft, 9 ... Steering wheel, 11 ... Steering wheel, 12 ... Steering assist mechanism, 13 ... Transmission ratio variable mechanism , 14 ... Transmission ratio control motor, 15 ... Reaction force control motor, 17 ... Hydraulic control valve, 18 ... Power cylinder, 24 ... Hydraulic pump, 28 ... Electric motor, 29 ... Lock mechanism, 30 ... Steering control unit, 31 ... Steering Auxiliary control unit 32 ... torque sensor 33 ... rotation angle sensor 34 ... rotation angle sensor (rotation position detection device) 35 ... temperature sensor (temperature detection device) 36 ... current sensor (current detection device) 37 ... travel State sensor 38 ... Transmission ratio control unit 39 ... Reaction force control unit 40 ... Mode setting unit 41 ... Initial diagnosis unit 47 ... Output gear 47a ... Outer periphery 50 ... Main body 51 ... Output rod 52 ... Lock Hole, θ ... times Position, Δθ ... rotational position change amount, A1 ... first predetermined angle, A2 ... second predetermined angle, A3 ... third predetermined angle, B ... play amount, C ... (corresponding to arrangement interval), rotation angle, i: current, Δi: deviation, T: temperature, P: steering torque

Claims (4)

A transmission ratio variable mechanism that is interposed between an input shaft that rotates in response to an operation of the steering member and an output shaft that rotates in conjunction with the operation of the steering mechanism, and that can change the transmission ratio between the input shaft and the output shaft; ,
A transmission ratio control motor capable of changing the transmission ratio of the transmission ratio variable mechanism;
A lock mechanism capable of locking the rotation of the transmission ratio control motor;
A rotational position detector for detecting the rotational position of the rotor of the transmission ratio control motor;
A control unit that controls the transmission ratio control motor and the lock mechanism;
The control unit includes a mode setting unit capable of setting a lock mode for locking the lock mechanism and an unlock mode for releasing the lock, and an initial diagnosis unit for diagnosing the operation of the lock mechanism when the control unit is activated. Including,
The initial diagnosis unit confirms that the lock release mode is set, and then the first diagnosis unit exceeds a play amount of the rotor when the rotor of the transmission ratio control motor is locked by the lock mechanism. When the rotational displacement command for rotating by a predetermined angle is output, and the amount of change in the detection value of the rotational position detecting device accompanying the output of the rotational displacement command is less than the first predetermined angle, the first of the lock mechanism to detect the abnormality,
The initial diagnosis unit confirms that the lock mode is set, and then a second predetermined amount exceeding the play amount of the rotor when the rotor of the transmission ratio control motor is locked by the lock mechanism. A rotational displacement command for rotating by an angle is output, and when the amount of change in the detected value of the rotational position detection device accompanying the rotational displacement command exceeds the play amount, a second abnormality of the lock mechanism is detected; Vehicle steering system. Oite to claim 1, said locking mechanism is lockable the rotor at a plurality of locking positions which are arranged at equal intervals in the circumferential direction of the rotor,
When the second abnormality of the lock mechanism is detected by the initial diagnosis unit, the control unit rotates the rotor of the transmission ratio control motor by a third predetermined angle equal to or greater than the rotation angle corresponding to the interval. A steering apparatus for a vehicle that outputs a rotational displacement command. The temperature detection device according to claim 1 or 2 that detects the temperature of the transmission ratio control motor, and the current detection device that detects the current of the transmission ratio control motor,
The control unit determines an abnormality of the transmission ratio control motor based on the temperature detected by the temperature detection device and the current detected by the current detection device, and outputs a lock command signal to the lock mechanism according to the determination of the abnormality. A steering apparatus for a vehicle having a fail-safe function for outputting and making the current of the transmission ratio control motor zero. The torque sensor according to claim 3 , further comprising a torque sensor for detecting a torque applied to the steering shaft,
The controller may, when the fail-safe function is executed, the condition that the output value of the torque sensor is equal to or less than a predetermined value, cancel the fail-safe function, and controls the transmission ratio of the transmission ratio control motor A vehicle steering apparatus having a function.

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