阅读说明：本技术 车辆用转向系统 (Steering system for vehicle ) 是由 伊藤公一 于 2019-06-26 设计创作，主要内容包括：本发明提供一种能够容易进行对传感器的检测值不合适的认定的线控转向型的车辆用转向系统。该转向系统具备转舵致动器(28),该转舵致动器(28)具有：具有1个马达旋转轴(48)的2系统的电动马达(24)、连结于车轮(12)并进行与自身的动作量相应的量的车轮的转向的转舵杆(26)、及将马达旋转轴的旋转动作变换为与该旋转动作的量相应的动作量的转舵杆的动作的动作变换机构(55),通过对与电动马达的2系统相对应的第1马达旋转角传感器(74a)、第2马达旋转角传感器(74b)各自的检测值、及检测转舵杆的动作量作为车轮(12)的转舵量的转舵量传感器(80)的检测值进行比较,从而能够容易认定哪一检测值不合适。(The invention provides a steer-by-wire type steering system for a vehicle, which can easily determine that a detection value of a sensor is inappropriate. The steering system is provided with a steering actuator (28), and the steering actuator (28) is provided with: a2-system electric motor (24) having 1 motor rotating shaft (48), a steering column (26) connected to a wheel (12) and steering the wheel by an amount corresponding to the amount of operation of the steering column, and an operation conversion mechanism (55) for converting the rotational operation of the motor rotating shaft into the operation of the steering column by an amount corresponding to the amount of the rotational operation, wherein the detection values of a 1 st motor rotation angle sensor (74a) and a 2 nd motor rotation angle sensor (74b) corresponding to the 2-system electric motor, and the detection value of a steering amount sensor (80) for detecting the amount of operation of the steering column as the amount of steering of the wheel (12) are compared, whereby it is possible to easily determine which detection value is inappropriate.)

1. A vehicle steering system is provided with:

a steering actuator having: a 2-system electric motor having 1 motor rotation shaft, a steering column connected to a wheel and steering the wheel by a steering amount corresponding to an amount of operation of the steering column, and an operation conversion mechanism for converting a rotational operation of the motor rotation shaft into an operation of the steering column by an amount corresponding to the amount of the rotational operation;

a 1 st motor rotation angle sensor and a 2 nd motor rotation angle sensor that detect motor rotation angles, which are rotation angles of the motor rotation shaft, respectively, corresponding to 2 systems of the electric motor;

a steering amount sensor that detects, as a steering amount of the wheel, an amount of operation of the steering column or an amount of operation of a movable body when the steering actuator has a movable body operating mechanism that operates the movable body by an amount of operation corresponding to the amount of operation of the steering column; and

a controller for controlling the steering amount of the wheel by controlling the operation of the electric motor,

the steering system for a vehicle is characterized in that,

the controller is configured to compare a detection value of the 1 st motor rotation angle sensor, a detection value of the 2 nd motor rotation angle sensor, and a detection value of the steering amount sensor, and thereby perform an improper determination of any one of these detection values, that is, an improper determination of the detection value.

2. The steering system for a vehicle according to claim 1,

the controller is configured to determine that the detected values are not appropriate on the premise that the 1 st motor rotation angle sensor, the 2 nd motor rotation angle sensor, and the steered amount sensor are not in failure.

3. The vehicular steering system according to claim 1 or 2,

the controller is configured to determine that one of the 1 st and 2 nd motor rotation angle sensors is not appropriate when the detected value of one of the 1 st and 2 nd motor rotation angle sensors does not match the detected value of the steered amount sensor and the detected value of the other of the 1 st and 2 nd motor rotation angle sensors matches the detected value of the steered amount sensor in the detected value improper determination.

4. The steering system for a vehicle according to claim 3,

the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor each have a stator attached to a housing of the electric motor and a rotor attached to the motor rotation shaft,

the controller is configured to recognize that a detected value of one of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor is inappropriate due to a failure in attachment of the fixed member or the rotating member of the one of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor.

5. The vehicular steering system according to any one of claims 1 to 4,

in the detection value improper confirmation, when the detection value of the 1 st motor rotation angle sensor matches the detection value of the 2 nd motor rotation angle sensor and the detection value of the 1 st motor rotation angle sensor and the detection value of the 2 nd motor rotation angle sensor do not match the detection value of the steering amount sensor, the controller is configured to perform improper confirmation for each sensor type, which is improper confirmation of the detection value of the 1 st motor rotation angle sensor, the detection value of the 2 nd motor rotation angle sensor, and the detection value of the steering amount sensor.

6. The steering system for a vehicle according to claim 5,

the controller is configured to determine that the detection value of the steering amount sensor is not appropriate when the delay occurs, and that the detection value of the 1 st motor rotation angle sensor and the detection value of the 2 nd motor rotation angle sensor are not appropriate when the delay does not occur, based on the presence or absence of the delay in the decrease in the detection value of the steering amount sensor when the control of the electric motor such as the increase in the steering amount is started, in the non-appropriate determination for each sensor type.

7. The steering system for a vehicle according to claim 6,

the steering amount sensor includes a fixed member attached to a housing of the steering actuator and a movable member attached to the steering column or the movable member,

the controller is configured to determine that a detection value of the steering amount sensor is inappropriate due to a failure in attachment of the fixed member or the movable member to the steering amount sensor or a backlash of the movable body operating mechanism when the delay occurs.

8. The vehicular steering system according to claim 6 or 7,

the controller is configured to determine that the detected value of the 1 st motor rotation angle sensor and the detected value of the 2 nd motor rotation angle sensor are not appropriate due to backlash of the motion conversion mechanism when the delay is not generated.

9. The vehicular steering system according to any one of claims 1 to 8,

the controller is configured to control the operation of the motor,

the steering amount control can be performed based on any one of the detection value of the 1 st motor rotation angle sensor, the detection value of the 2 nd motor rotation angle sensor, and the detection value of the steering amount sensor,

the control of the steering amount of the wheel is not performed based on any one of the detection value of the 1 st motor rotation angle sensor, the detection value of the 2 nd motor rotation angle sensor, and the detection value of the steering amount sensor, which is deemed inappropriate in the detection value improper determination.

10. The vehicular steering system according to any one of claims 1 to 9,

the electric motor is disposed so that the motor rotation shaft is parallel to the rudder stock,

the motion converting mechanism includes: the steering device comprises a screw thread arranged on the steering column, a nut which is provided with a screw thread screwed with the screw thread and is externally embedded on the steering column, and a transmission belt which is used for enabling the nut to rotate through the rotation of the motor rotating shaft.

11. The vehicular steering system according to any one of claims 1 to 10,

the movable body is a rotary shaft,

the movable body operating mechanism includes: a pinion gear provided on the rotary shaft, and a rack gear provided on the tiller and engaged with the pinion gear.

Technical Field

The present invention relates to a steering system mounted on a vehicle.

Background

In a steering system including an electric motor and using a force exerted by the electric motor, the electric motor is controlled based on detection values of various sensors. For example, in the following patent documents, in a so-called power steering system that assists a steering force applied to a steering wheel (a type of steering operation member) by a force of an electric motor, detection values of a plurality of sensors are compared, and when a detection value that does not match other detection values exists among the detection values, simply, which one detection value is not appropriate is determined based on a majority decision theory.

Disclosure of Invention

Problems to be solved by the invention

In the steering system described in the above patent document, in order to determine which sensor has an inappropriate detection value, it is necessary to provide 2 sensors of the same type, for example, a main sensor and a sub sensor. On the other hand, there is a steering system of a type in which the steering amount of the wheels is controlled by controlling the electric motor, that is, a so-called steer-by-wire (steber by wire) steering system, and it is impossible to apply a method of recognizing an improper detection value of a sensor related to the power steering system based on a difference of sensors provided. The present invention has been made in view of such circumstances, and an object thereof is to provide a steer-by-wire type vehicle steering system capable of easily recognizing that a detection value of a sensor is inappropriate.

Means for solving the problems

In order to solve the above problem, a vehicle steering system according to the present invention includes:

a steering actuator having: a 2-system electric motor having 1 motor rotation shaft, a steering column connected to a wheel and steering the wheel by a steering amount corresponding to an amount of operation of the steering column, and an operation conversion mechanism for converting a rotational operation of the motor rotation shaft into an operation of the steering column by an amount corresponding to the amount of the rotational operation;

a 1 st motor rotation angle sensor and a 2 nd motor rotation angle sensor that detect motor rotation angles, which are rotation angles of the motor rotation shaft, respectively, corresponding to 2 systems of the electric motor;

a steering amount sensor that detects, as a steering amount of the wheel, an amount of operation of the steering column or an amount of operation of a movable body when the steering actuator has a movable body operating mechanism that operates the movable body by an amount of operation corresponding to the amount of operation of the steering column; and

a controller for controlling the steering amount of the wheel by controlling the operation of the electric motor,

the steering system for a vehicle is characterized in that,

the controller is configured to compare a detection value of the 1 st motor rotation angle sensor, a detection value of the 2 nd motor rotation angle sensor, and a detection value of the steering amount sensor, and thereby perform an improper determination of any one of these detection values, that is, an improper determination of the detection value.

ADVANTAGEOUS EFFECTS OF INVENTION

The vehicle steering system according to the present invention (hereinafter, may be simply referred to as "steering system") is a redundant steer-by-wire type steering system in which an electric motor is 2 systems, and by performing the detection value misappropriation, it is possible to easily determine which of detection values is misappropriated when any of the detection values is inappropriate, based on the detection values of 2 motor rotation angle sensors corresponding to 2 systems and the detection values of 1 steered amount sensor for detecting the steered amount of the wheels.

Scheme of the invention

If the steering system of the present invention is configured to be able to execute the steering amount control based on any one of the detection value of the 1 st motor rotation angle sensor, the detection value of the 2 nd motor rotation angle sensor, and the detection value of the steering amount sensor, even when any one of these detection values is determined to be inappropriate due to the detection value being inappropriate, the steering amount control can be executed without using the inappropriate detection value. Specifically, for example, when one of the 2 systems configured as the normal electric motor is controlled based on the detection value of the 1 st motor rotation angle sensor and the other is controlled based on the detection value of the 2 nd motor rotation angle sensor, the respective 2 systems may be controlled based on the detection values of the 1 st and 2 nd motor rotation angle sensors when one of the 1 st and 2 nd motor rotation angle sensors is determined to be inappropriate. Further, since the rotational operation amount of the motor rotating shaft of the electric motor can be considered as an accumulation of the amount of change in the motor rotation angle, and the ratio of the rotational operation amount of the motor rotating shaft to the steering amount of the wheel can be considered as a set ratio depending on the structure of the motion conversion mechanism, when it is determined that the detection values of both the 1 st and 2 nd motor rotation angle sensors are inappropriate, it is sufficient to perform the control of each of the 2 systems based on the detection value of the steering amount sensor.

The 1 st and 2 nd motor rotation angle sensors in the steering system according to the present invention may be any sensors as long as they can detect a rotation angle of the motor rotation shaft, that is, a rotation phase for supplying electricity to the electric motor, and for example, a resolver, a rotary encoder, or the like may be used. Generally, a detection target to be detected is attached to a motor rotation shaft as a rotating member (rotor), and a detection target to be detected is attached to a housing of an electric motor as a fixing member (stator).

On the other hand, the steering amount sensor in the steering system according to the present invention may be a sensor capable of directly detecting the operation amount of the steering column as the steering amount of the wheel. Specifically, for example, a linear encoder or the like can be employed. In this case, the detection target may be attached to the rudder stock as a movable member (mover), and the detection target may be attached to the housing of the rudder actuator as a fixed member (stator). The steering amount sensor may be a sensor capable of indirectly detecting the operation amount of the steering column as the steering amount of the wheel. Specifically, for example, when the steering actuator is configured to include a mechanism that includes a rack and pinion mechanism, that is, a rotating shaft having a rack provided on the steering column and a pinion gear engaged with the rack, and that converts the rotational operation of the rotating shaft and the operation of the steering column into each other, as in a steering device of a general power steering system, a configuration that can detect the amount of rotation of the rotating shaft can be adopted. As such a steering amount sensor, for example, a resolver, an encoder, or the like may be used, and a so-called steering sensor used for detecting an operation angle of a steering wheel as a steering operation member may be used. The steering sensor is convenient because it can detect an absolute rotation amount exceeding 360 ° instead of detecting a phase within 360 ° of the rotation axis.

In addition, the steering actuator using the rack and pinion mechanism can use a steering device constituting a general power steering system as it is by releasing the connection between the rotating shaft (pinion shaft) and the steering wheel, and when using this steering device, a steering amount sensor can be attached without special labor instead of a steering torque sensor attached to the rotating shaft. The rack and pinion mechanism described above can be considered as a movable body operating mechanism in which the rotary shaft functions as a movable body and the movable body is operated by an operation amount corresponding to an operation amount of the rudder stock.

As the motion conversion mechanism employed in the steering actuator of the steering system of the present invention, for example, a mechanism including a screw mechanism may be employed. Specifically, the mechanism includes, for example, a screw provided on the rudder post and a nut provided with a screw to be screwed with the screw and externally fitted to the rudder post. In the case where the electric motor is disposed so that the motor rotation shaft is parallel to the rudder stock, a mechanism including a belt transmission mechanism having a belt for rotating the nut by the rotation operation of the electric motor may be employed.

The detection value improper determination performed by the controller in the steering system according to the present invention may be performed by comparing the detection values of the 1 st and 2 nd motor rotation angle sensors and the steering amount sensor, specifically, for example, by determining whether or not the detection values match each other. As described above, since the ratio of the rotational operation amount of the motor rotation shaft to the steering amount is the set ratio, it is possible to easily determine whether or not the detected values match each other by converting one of the detected values of the 1 st and 2 nd motor rotation angle sensors and the detected value of the steering amount sensor into the other based on the ratio. In addition, in this determination, when the difference between the 2 detection values to be compared is larger than the threshold difference set to be relatively small, it is sufficient that the 2 detection values are determined not to match.

Generally, whether or not the sensor itself is normal, in other words, whether or not a failure has occurred in the sensor itself, can be determined by a diagnostic function (also referred to as a "self-diagnostic function") provided in the controller. In consideration of this, in the steering system of the present invention, the detection value improper determination, that is, the detection value improper determination performed by comparing the detection values of the 1 st and 2 nd motor rotation angle sensors and the steering amount sensor with each other may be performed on the assumption that the 1 st and 2 nd motor rotation angle sensors and the steering amount sensor themselves do not fail. If the detection value is not properly recognized on the premise as described above, the processing for the recognition can be simplified, and more specifically, the processing obtained by limiting the factors that make the detection value unsuitable can be simplified.

Here, consideration is given to factors that the detection values of the 1 st and 2 nd motor rotation angle sensors and the steering amount sensor are inappropriate. In the steering system according to the present invention, for example, when the fixed member provided in each of the 1 st and 2 nd motor rotation angle sensors is attached to the housing of the electric motor and the rotating member is attached to the motor rotation shaft as described above, if a failure occurs in the attachment of the fixed member to the motor rotation shaft, the detection values of the 1 st and 2 nd motor rotation angle sensors become inappropriate. Similarly, for example, in the case where the fixed member included in the steering amount sensor is attached to the housing of the steering actuator and the movable member is attached to the steering column or the movable member as described above, when a failure occurs in the attachment of the fixed member to the steering column or the movable member, the detection value of the steering amount sensor becomes inappropriate. The mounting failure is, for example, a loose mounting, or a loose fixed member, a rotating member, or a movable member. In the above-described movable body operating mechanism, for example, the rack and pinion mechanism, when backlash or the like becomes large and backlash occurs, the detection value of the steering amount sensor becomes inappropriate. Further, when consideration is given to the factors that the detection values of the 1 st and 2 nd motor rotation angle sensors and the detection value of the steering amount sensor do not match, the detection values of the 1 st and 2 nd motor rotation angle sensors and the detection value of the steering amount sensor do not match again even when the loosening occurs in the motion conversion mechanism, specifically, when the loosening of the transmission belt or the backlash of the screw mechanism increases, for example.

In consideration of the above-described factors, in the detection value improper recognition in the steering system according to the present invention, when the detection value of one of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor does not match the detection value of the steering amount sensor and the detection value of the other of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor matches the detection value of the steering amount sensor, it can be recognized that the detection value of the one is improper due to a failure in mounting of one of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor or a rotating member.

On the other hand, when the detection value of the 1 st motor rotation angle sensor matches the detection value of the 2 nd motor rotation angle sensor and the detection values of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor do not match the detection value of the steered amount sensor, it is not possible to determine whether the detection values of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor are not suitable or the detection value of the steered amount sensor is not suitable based only on the fact that the matching and the mismatching are made, but it is possible to perform the determination that one of the detection values of the 1 st motor rotation angle sensor and the 2 nd motor rotation angle sensor and the detection value of the steered amount sensor is not suitable as the non-suitable determination for each sensor type.

In the above-described improper recognition for each sensor type, when it is intended to determine whether the detection value of the 1 st motor rotation angle sensor and the detection value of the 2 nd motor rotation angle sensor are improper or whether the detection value of the steering amount sensor is improper, for example, the determination may be made based on the presence or absence of a delay in the decrease of the detection value of the steering amount sensor at the time of starting the control of the electric motor such as to decrease the increased steering amount. In view of the above-described factors, for example, when a failure occurs in the attachment of the fixed member or the movable member of the steering amount sensor or when the backlash occurs in the movable member operating mechanism, the decrease in the detection value of the steering amount sensor is delayed by the slack or the backlash of the attachment due to the failure or the backlash of the attachment. Therefore, when a delay occurs in the decrease of the detection value of the steering amount sensor, it is sufficient to determine that the detection value of the steering amount sensor is not appropriate. On the other hand, for example, even if the motion conversion mechanism is loosened, a delay in reduction of the detection value of the steering amount sensor does not occur. Therefore, when there is no delay in the decrease of the detection value of the steering amount sensor, it is sufficient to determine that the detection value of the 1 st motor rotation angle sensor and the detection value of the 2 nd motor rotation angle sensor are not appropriate due to the backlash of the motion conversion mechanism. In other words, it is sufficient to perform determination that the detection value of the 1 st motor rotation angle sensor and the detection value of the 2 nd motor rotation angle sensor should not be used.

Drawings

Fig. 1 is a schematic diagram showing the entire configuration of a vehicle steering system of the embodiment.

Fig. 2 is a diagram for explaining the structure of a steering actuator included in the vehicle steering system according to the embodiment.

Fig. 3 is a diagram for explaining a steering motor and a motion conversion mechanism of the steering actuator shown in fig. 2.

Fig. 4 is a view schematically showing the mounting of a sensor provided in the vehicular steering system of the embodiment.

Fig. 5 is a graph for explaining a decrease in the detected value of the steering amount in the return steering operation.

Fig. 6 is a flowchart showing a detection value unsuitability determination routine executed by the control device, which is the controller of the vehicle steering system according to the embodiment.

Description of the reference numerals

12: a wheel; 14: a steering device; 16: a steering wheel; 18: an operating device; 20: control means [ controller ]; 24: steering motor [ electric motor ]; 26: steering the rudder stock; 28: a steering actuator; 40: a housing; 42: a thread groove; 44: a holding cylinder; 46: a nut; 48: a motor shaft; 50: a timing pulley; 54: a timing belt (transmission belt); 55: a motion changing mechanism; 70: an Electronic Control Unit (ECU); 72: CAN; 74a, 74 b: a motor rotation angle sensor [ 1 st motor rotation angle sensor, 2 nd motor rotation angle sensor ]; 76a, 76 b: a rotating member; 78a, 78 b: a fixing member; 80: a steering amount sensor; 82: a rack; 84: a pinion gear; 86: pinion shaft (movable body); 92: a rotary member (movable member); 94: a fixing member; 96: a movable body operating mechanism.

Detailed Description

Hereinafter, a vehicle steering system according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention can be implemented in various ways, including the way described in the above-mentioned [ invention ] item, in addition to the following examples, by making various changes and improvements based on the knowledge of those skilled in the art.