JP3875202B2 - Electric power steering apparatus, manufacturing method and manufacturing apparatus thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering apparatus, a manufacturing method thereof, and a manufacturing apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known an electric power steering apparatus that reduces the steering force by a steering wheel by applying an assist force by a motor to a steering mechanism coupled to a steering shaft. In such an electric power steering apparatus, since the steering wheel rotates within a finite number of rotations of one or more left and right, the “position of the steering wheel where the vehicle goes straight” is set as a neutral position, and anything from the neutral position to the left or right is determined. The steering angle is grasped by detecting whether the steering wheel is located at the rotational position of the degree by the sensor as an absolute position.
[0003]
And the steering angle by such a steering wheel is detected by the rotation angle sensor comprised from the slit board and photo interrupter which rotate with a steering shaft, for example, For example, it is disclosed by the following patent documents 1. By adopting a configuration such as “steering angle sensor and power steering device”, the neutral position of the steering wheel can be accurately detected by one rotation angle sensor.
[0004]
By the way, in general, the steering wheel of a vehicle is not capable of controlling the angle of the steered wheel in the entire range by steering within one rotation (360 degrees). For example, the steering wheel rotates twice in the left direction around the neutral position of the steering wheel ( 720 degrees) and two rotations in the right direction (720 degrees). By rotating the steering wheel ± 720 degrees, the steering angle can be freely changed within a predetermined angle range. For this reason, even if a configuration such as the “steering angle sensor and power steering device” disclosed in Patent Document 1 is adopted, it is impossible to detect the absolute rotational position of the steering wheel with a single rotational angle sensor. It is necessary to detect the absolute rotation position by combining a plurality of rotation angle sensors. However, on the other hand, a configuration using many rotation angle sensors directly leads to an increase in product cost and failure rate, and therefore there is a situation that it is difficult to adopt a configuration that causes an increase in the number of parts.
[0005]
Therefore, the applicant of the present application uses a resolver as a means for detecting a motor rotation position in a motor that generates assist force in a general electric power steering apparatus, and means for detecting steering torque by a steering wheel. However, by using a signal that is output from these resolvers and that is linear with respect to the rotation angle, steering is performed without causing an increase in the number of parts. Japanese Patent Application Nos. 2001-268388 and 2002-196131 have proposed an absolute position detection device that can detect the absolute position of a wheel. The invention of “absolute position detection device and absolute position detection method for electric power steering apparatus” according to the application specification of Japanese Patent Application No. 2002-196131 is disclosed in the application specification of the previous Japanese Patent Application No. 2001-268388. This is a further improvement of the technical content.
[0006]
[Patent Document 1]
JP 2002-145095 A (2nd to 8th pages, FIGS. 1 to 4)
[0007]
[Problems to be solved by the invention]
However, the “absolute position detection device and absolute position detection method for an electric power steering device” disclosed in the application of Japanese Patent Application No. 2002-196131 filed by the applicant of the present application also determines the number of counter poles of the resolver and the configuration of the steering mechanism. When the relationship satisfies a predetermined condition, it has been found by subsequent investigation and research by the present inventor that it is difficult to provide a margin for the absolute position of the steering wheel.
[0008]
The present invention has been made in order to solve the above-described problems. The object of the present invention is to accurately detect the absolute rotational position of the steering wheel even if there is an error factor, and based on the absolute rotational position. Another object of the present invention is to provide an electric power steering apparatus that can control a motor that assists steering.
Another object of the present invention is to provide an electric power steering apparatus capable of accurately detecting the absolute rotational position of a steering wheel and controlling a motor that assists steering based on the absolute rotational position even if there is an error factor. An object of the present invention is to provide a method for manufacturing an electric power steering apparatus that can be manufactured and an apparatus for manufacturing an electric power steering apparatus.
[0009]
[Means for solving the problems and functions and effects of the invention]
  In order to achieve the above object, in the electric power steering apparatus according to claim 1, a steering wheel, a first resolver for detecting a first steering angle which is a rotation angle of a steering shaft coupled to the steering wheel, A second resolver that has a counter electrode number different from that of the first resolver and detects a second steering angle that is a rotation angle of the steering shaft, and a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer And a third resolver that detects a motor electrical angle that is a rotation angle of the motor, and the absolute rotational position of the steering wheel that is obtained from the first steering angle, the second steering angle, and the motor electrical angle. The electric power steering device for controlling the motor based on the product of the reduction gear ratio of the reduction gear and the counter electrode number of the third resolver Calculated values, so that a non-integer having a value after the decimal point, at least one of the reduction gear ratio or logarithmic poles is setThe numerical value after the decimal point of the calculated value is the calculated value when the angle deviation of the motor electrical angle that differs for each unit of at least one rotation range of the steering wheel is 67% or more and 100% or less of the maximum value of the angle deviation. Is in the range of decimalsThis is a technical feature. Here, the “number of counter poles” refers to the number of magnetic poles in which the combination of the N pole and the S pole is a pair.
[0010]
  In the first aspect of the invention, the reduction gear ratio or the counter electrode number is calculated so that an arithmetic value obtained by multiplying the reduction gear ratio of the reduction gear by the counter electrode number of the third resolver becomes a non-integer having a numerical value after the decimal point. Since at least one of them is set, the numerical value after the decimal point is not 0 (zero), that is, an integer. As a result, the steering angle (0 degree to 360 degrees) within one rotation of the steering wheel, which is obtained from the first steering angle of the first resolver and the second steering angle of the second resolver, is the number of left and right rotations of the steering wheel. , So that no one rotation range unit can take the same value.The
  In addition, the numerical value after the decimal point of the calculated value by the product of the reduction gear ratio of the reduction gear and the number of counter poles of the third resolver indicates that the angular deviation of the motor electrical angle that differs for each unit of at least one rotation range of the steering wheel 1 of the steering wheel obtained from the first steering angle of the first resolver and the second steering angle of the second resolver. In addition to the fact that the steering angle (0 ° to 360 °) in the rotation does not take the same value in any one rotation range unit among the plurality of left and right rotations of the steering wheel, However, a non-interference area can be secured.
  In other words, even if a detection error occurs in the steering angle of the steering wheel due to an error due to dimensional accuracy of mechanical parts constituting the steering mechanism, an error due to wear, or an error in the temperature characteristics of the electrical parts that process the resolver signal, It is possible to provide a margin such that adjacent one rotation range units do not take the same value. As a result, even if such an error can occur, the absolute rotational position of the steering wheel can be accurately detected, and thus steering is assisted based on the detected absolute rotational position of the steering wheel. The motor to be controlled can be controlled.
[0015]
For example, centering on the neutral position of the steering wheel, A = 0 for the steering wheel's right rotation range (0 ° <θ ≦ 360 °), and the right one rotation range on the right side (360 ° <θ ≦ 720 °). A = 1, the left rotation range (0 degree> θ ≧ −360 degrees) around the neutral position, A = −1, and the left one rotation range (−360 degrees> θ ≧ −720 degrees) on the left side. When A = -2, the motor electrical angle of another rotation range A = -1, 0, 1 with respect to the motor electrical angle of one rotation range A = -2 is the numerical value after the decimal point of the calculated value. 10 (A) has an angle deviation, and further, this angle deviation is folded around 180 degrees to represent a fold line K as shown in FIG. 10 (B). It has been found by investigation and research by the present inventor that a chain line can be obtained. This broken line K is obtained by selecting the smallest angular deviation among the angular deviations of one rotation range A = -1, 0, 1.
[0016]
Here, “the angular deviation of the motor electrical angle that is different for each unit of at least one left / right rotation range of the steering wheel” means, for example, as shown in FIG. 10B, one rotation range A = -2 is intended to be a broken line K due to a deviation from the motor electrical angle. Further, “67% or more and 100% or less of the maximum value of the angle deviation” means, for example, in the broken line K, as shown in FIG. 9, 67% or more and 100% or less of the maximum value (90 degrees) of the broken line K (60 The hatched area in the figure, which is a range of not less than 90 degrees and not more than 90 degrees, is intended.
[0017]
As a result, even if a detection error occurs in the steering angle of the steering wheel due to an error due to dimensional accuracy or wear due to mechanical parts constituting the steering mechanism, or due to a temperature characteristic error of an electrical part that processes the resolver signal, such an error causes an adjacent 1 rotation range units (for example, in the example of FIG. 10, between 1 rotation range A = −2 and 1 rotation range A = −1, between 1 rotation range A = −1 and 1 rotation range A = 0. And 1 rotation range A = 0 and 1 rotation range A = 1). Therefore, even if such an error can occur, the absolute rotational position of the steering wheel can be accurately detected, and thus steering is assisted based on the detected absolute rotational position of the steering wheel. The motor can be controlled.
[0018]
  In order to achieve the above object, the claims2In the method for manufacturing an electric power steering apparatus, a steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft coupled to the steering wheel, and a counter electrode number different from the first resolver A second resolver that detects a second steering angle that is a rotation angle of the steering shaft, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a rotation angle of the motor And a third resolver that detects the motor electrical angle, and controls the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle. A method of manufacturing an electric power steering apparatus that is configured to be capable of performing the operation by the product of a reduction gear ratio of the reduction gear and a counter electrode number of the third resolver. The value is “0.17 or more and 0.28 or less”, “0.39 or more and 0.42 or less”, “0.58 or more and 0.61 or less” and “0.72”. The present invention is characterized by including a step of setting at least one of the reduction gear ratio or the number of counter electrodes so as to be a non-integer having “more than 0.83”.
[0019]
  Furthermore, in order to achieve the above object, the claims3In the electric power steering apparatus manufacturing apparatus, a steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft coupled to the steering wheel, and a counter electrode number different from that of the first resolver A second resolver that detects a second steering angle that is a rotation angle of the steering shaft, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a rotation angle of the motor And a third resolver that detects the motor electrical angle, and controls the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle. A device for manufacturing an electric power steering apparatus that is configured to be capable of performing an operation based on a product of a reduction gear ratio of the reduction gear and a counter electrode number of the third resolver. The value is “0.17 or more and 0.28 or less”, “0.39 or more and 0.42 or less”, “0.58 or more and 0.61 or less” and “0.72”. Technical features include means for setting at least one of the reduction gear ratio or the number of counter electrodes so as to be a non-integer having “more than 0.83”.
[0020]
  Claim2And claims3In the present invention, the calculated value by the product of the reduction gear ratio of the reduction gear and the counter electrode number of the third resolver is “0.17 or more and 0.28 or less”, “0. 39 to 0.42 or less "," 0.58 to 0.61 or less "and" 0.72 or more and 0.83 or less ". Set.
[0021]
That is, the numerical value after the decimal point of the calculated value is equal to or less than the decimal point of the calculated value when the angle deviation of the motor electrical angle that differs for each unit of at least one rotation range of the steering wheel is 67% to 100% of the maximum value of the angular deviation. Therefore, when this numerical range is specifically expressed, “0.17 or more and 0.28 or less”, “0.39 or more and 0.42 or less”, “0.58 or more and 0.61 or less And “0.72 to 0.83”. The reason for defining such a numerical range is that the steering wheel right rotation range (0 degree <θ ≦ 360 degrees) is set to A = 0 and the right one rotation range (right side) 360 ° <θ ≦ 720 °) A = 1, left rotation range around the neutral position (0 °> θ ≧ −360 °) A = −1, and left rotation range on the left side (−360) In the case where A = −2 in the case of degree> θ ≧ −720 degrees), by selecting the angle deviation having the smallest angle deviation among the angle deviations of one rotation range A = −1, 0, 1 and FIG. Can be obtained (see FIG. 10B), and based on this fold line K, 67% or more and 100% or less of the maximum angle deviation (90 degrees) (60 degrees or more and 90 degrees). The value after the decimal point is obtained According to the door.
[0022]
As a result, even if a detection error occurs in the steering angle of the steering wheel due to a dimensional accuracy error of the mechanical parts constituting the steering mechanism or a temperature characteristic error of the electrical parts that process the resolver signal, the adjacent one rotation range is caused by such errors. Units (for example, in the example of FIG. 10, between one rotation range A = −2 and one rotation range A = −1, between one rotation range A = −1 and one rotation range A = 0, and one rotation range It is possible to prevent the same value from being obtained between A = 0 and one rotation range A = 1. Therefore, even if such an error can occur, the absolute rotational position of the steering wheel can be accurately detected, and thus steering is assisted based on the detected absolute rotational position of the steering wheel. An electric power steering apparatus capable of controlling a motor can be manufactured.
[0023]
  In order to achieve the above object, the claims4In the electric power steering device ofA steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a counter electrode number different from that of the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotational position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle, and the reduction gear ratio of the reduction gear and the The reduction gear ratio or the number of counter electrodes is small so that the calculated value by the product of the counter electrode number of the third resolver becomes a non-integer having a numerical value after the decimal point. One and also is set,The absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle may be specified from a plurality of absolute rotation position candidates.RudenA pneumatic power steering apparatus comprising: a rotation range restricting means for restricting the rotation of the steering wheel within a predetermined rotation range when the ignition switch is off; and the first steering immediately before the ignition switch is turned off. The absolute rotation position of the steering wheel obtained from the angle, the second steering angle and the motor electrical angle is stored as an IG off absolute rotation position, and stored in the storage means after the ignition switch is turned on. Based on the previous IG off absolute rotation position and the predetermined rotation range of the steering wheel regulated by the rotation range regulating means, this time, from the first steering angle, the second steering angle, and the motor electrical angle The required absolute rotation position of the steering wheel is determined from the plurality of absolute rotation position candidates. It is technically characterized by comprising an absolute rotational position specifying means for specifying.
[0024]
  Claim4In the invention ofAt least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. For this reason, the numerical value after the decimal point is 0 (zero), that is, the calculated value does not become an integer. As a result, the steering angle (0 degree to 360 degrees) within one rotation of the steering wheel, which is obtained from the first steering angle of the first resolver and the second steering angle of the second resolver, is the number of left and right rotations of the steering wheel. Since the same value cannot be taken in any one rotation range unit, the absolute rotation position of the steering wheel can be accurately detected. Therefore, it is possible to control the motor that assists the steering based on the absolute rotation position of the steering wheel detected in this way.
  Also,The absolute rotation position of the steering wheel obtained immediately before the ignition switch is turned off is stored by the storage means as the IG off absolute rotation position. Then, after the ignition switch is turned on, based on the previous IG-off absolute rotation position stored in the storage means and the predetermined rotation range of the steering wheel restricted by the rotation range restriction means, the first steering angle, the second The absolute rotation position of the steering wheel obtained from the steering angle and the motor electrical angle is specified from a plurality of absolute rotation position candidates by the absolute rotation position specifying means. Thus, even if the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle may be specified from a plurality of absolute rotation position candidates, the previous IG-off absolute rotation position and the ignition can be determined. Based on the predetermined rotation range in which the steering wheel can rotate when the steering wheel is off, the absolute rotation position of the steering wheel obtained this time can be specified from the plurality of absolute rotation position candidates. Accordingly, even in such a case, the absolute rotational position of the steering wheel can be accurately detected, and the motor that assists steering can be controlled based on the absolute rotational position of the steering wheel thus detected. .
[0025]
  And claims5In the electric power steering apparatus, the steering wheel has a right rotation range that rotates once to the right from a neutral position of steering, a right rotation range that rotates further to the right beyond the right rotation range, and the steering wheel The predetermined range restricted by the rotation range restricting means is rotatable in a left one rotation range that rotates one left from the neutral position and a left two rotation range that further rotates to the left beyond the one left rotation range. The angle is less than 360 degrees, and the plurality of absolute rotation position candidates are present in the right two rotation ranges and the left two rotation ranges.4The electric power steering apparatus according to claim 1, wherein the calculated value has “0.22 or more and 0.39 or less” and “0.61 or more and 0.78 or less” as a numerical value after the decimal point of the calculated value. A technical feature is that it is set to be a non-integer.
[0026]
  Claim5In the present invention, the predetermined range restricted by the rotation range restriction means is less than 360 degrees, and a plurality of absolute rotational position candidates exist in the right two rotation ranges and the left two rotation ranges of the steering wheel. The calculated value by the product of the reduction gear ratio of the speed reducer and the counter electrode number of the third resolver is “0.22 or more and 0.39 or less” and “0.61 or more and 0 or less” as numerical values after the decimal point of the calculated value. .78 or less "is set to be a non-integer. The reason for defining such a numerical range is that the steering wheel has a right rotation range (0 degree <θ ≦ 360 degrees) A = 0 and a right rotation range (360 degrees <θ ≦ 720 degrees) A = 1. When the left rotation range (0 degrees> θ ≧ −360 degrees) is A = −1 and the left rotation range (−360 degrees> θ ≧ −720 degrees) is A = −2, a plurality of absolute rotations In the case where the position candidate exists in one rotation range A = 1, -2, it is shown in FIG. 17 by selecting the one with the smallest angle deviation among the angle deviations by one rotation range A = -1, 0. Since such a broken line M can be obtained (see FIG. 18 (B)), based on this broken line M, 67% to 100% of the maximum angle deviation (120 degrees) (80 degrees to 120 degrees) This is because the numerical value after the decimal point of the calculated value corresponding to) is obtained.
[0027]
Thus, even if the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle may be specified from a plurality of absolute rotation position candidates, the previous IG-off absolute rotation position and the ignition can be determined. Based on the rotation range of less than 360 degrees in which the steering wheel can rotate when the steering wheel is off, the absolute rotation position of the steering wheel obtained this time can be specified from the plurality of absolute rotation position candidates. Accordingly, even in such a case, the absolute rotational position of the steering wheel can be accurately detected, and the motor that assists steering can be controlled based on the absolute rotational position of the steering wheel thus detected. .
[0028]
  And claims6In the electric power steering apparatus, the steering wheel has a right rotation range that rotates once to the right from a neutral position of steering, a right rotation range that rotates further to the right beyond the right rotation range, and the steering wheel The predetermined range restricted by the rotation range restricting means is rotatable in a left one rotation range that rotates one left from the neutral position and a left two rotation range that further rotates to the left beyond the one left rotation range. , Less than 180 degrees, and the plurality of absolute rotation position candidates exist in “the right rotation range and the left rotation range” and “the right rotation range and the left rotation range”.4The electric power steering apparatus according to the technology, wherein the calculated value is set to be a non-integer having a value of 0.33 or more and 0.67 or less as a numerical value after the decimal point of the calculated value. Characteristic.
[0029]
  Claim6In the present invention, the predetermined range restricted by the rotation range restriction means is less than 180 degrees, and the plurality of absolute rotation position candidates are “the right rotation range and the left rotation range” and “the right rotation 2” of the steering wheel. Rotation range and left one rotation range ". And the calculation value by the product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver is set to be a non-integer having a value of 0.33 or more and 0.67 or less as a numerical value after the decimal point of the calculation value. Has been. The reason for defining such a numerical range is that the steering wheel has a right rotation range (0 degree <θ ≦ 360 degrees) A = 0 and a right rotation range (360 degrees <θ ≦ 720 degrees) A = 1. When the left rotation range (0 degrees> θ ≧ −360 degrees) is A = −1 and the left rotation range (−360 degrees> θ ≧ −720 degrees) is A = −2, a plurality of absolute rotations When position candidates exist in one rotation range A = 0, -2 and A = 1, -1, the one with the smallest angle deviation is selected from the angle deviations in one rotation range A = -1, 1. 20 can be obtained (see FIG. 21 (B)). Based on this broken line P, 67% or more and 100% or less of the maximum angle deviation (180 degrees) A numerical value after the decimal point of the calculated value corresponding to (120 degrees or more and 180 degrees or less) is obtained. According.
[0030]
Thus, even if the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle may be specified from a plurality of absolute rotation position candidates, the previous IG-off absolute rotation position and the ignition can be determined. Based on the rotation range of less than 180 degrees in which the steering wheel can rotate when the steering wheel is off, the absolute rotation position of the steering wheel obtained this time can be specified from the plurality of absolute rotation position candidates. Accordingly, even in such a case, the absolute rotational position of the steering wheel can be accurately detected, and the motor that assists steering can be controlled based on the absolute rotational position of the steering wheel thus detected. .
[0031]
  In order to achieve the above object, the claims7In the electric power steering device ofA steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a counter electrode number different from that of the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotational position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle, and the reduction gear ratio of the reduction gear and the The reduction gear ratio or the number of counter electrodes is small so that the calculated value by the product of the counter electrode number of the third resolver becomes a non-integer having a numerical value after the decimal point. One and also is set,The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. The steering wheel is rotatable in one rotation range and two left rotation ranges that rotate further to the left beyond the left one rotation range, and is obtained from the first steering angle, the second steering angle, and the motor electrical angle. When the absolute rotational position is specified from two absolute rotational position candidatesRudenA pneumatic power steering apparatus, wherein one of the two absolute rotation position candidates is any one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range. Is present in any one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range, the two absolute rotation positions. A technical feature is that the other of the candidates is specified as the absolute rotational position.
[0032]
  Claim7In the invention ofAt least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. For this reason, the numerical value after the decimal point is 0 (zero), that is, the calculated value does not become an integer. As a result, the steering angle (0 degree to 360 degrees) within one rotation of the steering wheel, which is obtained from the first steering angle of the first resolver and the second steering angle of the second resolver, is the number of left and right rotations of the steering wheel. Since the same value cannot be taken in any one rotation range unit, the absolute rotation position of the steering wheel can be accurately detected. Therefore, it is possible to control the motor that assists the steering based on the absolute rotation position of the steering wheel detected in this way.
  Also,Of the two absolute rotation position candidates, one does not exist in any of the left 2 rotation range, left 1 rotation range, right 1 rotation range, and right 2 rotation range, and the other is the left 2 rotation range, left If it exists in any one of the one rotation range, the right one rotation range, and the right two rotation range, the other is specified as the absolute rotation position from the two absolute rotation position candidates. As a result, even if the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle is specified from the two absolute rotation position candidates, one of them is determined as the absolute value of the steering wheel. It can be specified as a rotational position. Therefore, in such a case, the absolute rotational position of the steering wheel can be accurately detected even when the vehicle in which the steering wheel is difficult to rotate is parked. Therefore, even when the vehicle is parked or stopped, the motor for assisting steering can be controlled based on the absolute rotation position of the steering wheel detected in this way.
[0033]
  Furthermore, in order to achieve the above object, the claims8In the electric power steering device ofA steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a counter electrode number different from that of the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotational position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle, and the reduction gear ratio of the reduction gear and the The reduction gear ratio or the number of counter electrodes is small so that the calculated value by the product of the counter electrode number of the third resolver becomes a non-integer having a numerical value after the decimal point. One and also is set,The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. The steering wheel is rotatable in one rotation range and two left rotation ranges that rotate further to the left beyond the left one rotation range, and is obtained from the first steering angle, the second steering angle, and the motor electrical angle. When the absolute rotational position is specified from two absolute rotational position candidatesRudenA pneumatic power steering apparatus, wherein each of the two absolute rotation position candidates is any one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range. If the steering wheel is rotated beyond a predetermined angle, one of the two absolute rotation position candidates becomes the left two rotation range, the left one rotation range, or the right one rotation. A technical feature is that, when no longer exists in any of the range and the two right rotation ranges, the other of the two absolute rotation position candidates is specified as the absolute rotation position.
[0034]
  Claim8In the invention ofAt least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. For this reason, the numerical value after the decimal point is 0 (zero), that is, the calculated value does not become an integer. As a result, the steering angle (0 degree to 360 degrees) within one rotation of the steering wheel, which is obtained from the first steering angle of the first resolver and the second steering angle of the second resolver, is the number of left and right rotations of the steering wheel. Since the same value cannot be taken in any one rotation range unit, the absolute rotation position of the steering wheel can be accurately detected. Therefore, it is possible to control the motor that assists the steering based on the absolute rotation position of the steering wheel detected in this way.
  Also,If any of the two absolute rotation position candidates is present in any one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range, the steering wheel exceeds the predetermined angle. When one of the two absolute rotation position candidates does not exist in any of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range due to the rotation, 2 The other of the two absolute rotation position candidates is specified as the absolute rotation position. Thereby, even when the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle is specified from the two absolute rotation position candidates, the steering wheel exceeds the predetermined angle. By rotating, either one can be specified as the absolute rotational position of the steering wheel. Therefore, even in such a case, if the steering wheel rotates beyond a predetermined angle, the absolute rotational position of the steering wheel can be accurately detected regardless of whether the vehicle is parked or stopped. . Therefore, the motor for assisting steering can be controlled based on the absolute rotation position of the steering wheel thus detected regardless of the vehicle state.
[0035]
  Furthermore, in order to achieve the above object, the claims9In the electric power steering device ofA steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a counter electrode number different from that of the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotational position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle, and the reduction gear ratio of the reduction gear and the The reduction gear ratio or the number of counter electrodes is small so that the calculated value by the product of the counter electrode number of the third resolver becomes a non-integer having a numerical value after the decimal point. One and also is set,The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. The steering wheel is rotatable in one rotation range and two left rotation ranges that rotate further to the left beyond the left one rotation range, and is obtained from the first steering angle, the second steering angle, and the motor electrical angle. When the absolute rotational position is specified from two absolute rotational position candidatesRudenA pneumatic power steering device, wherein the steering wheel is capable of detecting the rotational speeds of the left and right wheels, and the steering wheel based on a difference between the rotational speeds of the left and right wheels detected by the wheel speed detecting means. Steering direction determination means for determining the steering direction by the absolute rotation position specifying means for specifying the absolute rotation position from the two absolute rotation position candidates based on the steering direction determined by the steering direction determination means, It is a technical feature to provide.
[0036]
  Claim9In the invention ofAt least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. For this reason, the numerical value after the decimal point is 0 (zero), that is, the calculated value does not become an integer. As a result, the steering angle (0 degree to 360 degrees) within one rotation of the steering wheel, which is obtained from the first steering angle of the first resolver and the second steering angle of the second resolver, is the number of left and right rotations of the steering wheel. Since the same value cannot be taken in any one rotation range unit, the absolute rotation position of the steering wheel can be accurately detected. Therefore, it is possible to control the motor that assists the steering based on the absolute rotation position of the steering wheel detected in this way.
  Also,The wheel speed detection means detects the rotation speeds of the left and right wheels, and the steering direction determination means determines the steering direction by the steering wheel based on the difference between the rotation speeds of the left and right wheels. Based on this steering direction, the absolute rotational position is specified by the absolute rotational position specifying means from the two absolute rotational position candidates. Thus, even if the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle is specified from the two absolute rotation position candidates, the left and right wheels of the vehicle are rotated. In this case, either one can be specified as the absolute rotation position of the steering wheel. Therefore, even in such a case, if the left and right wheels rotate, the absolute rotational position of the steering wheel can be accurately detected. Therefore, if the vehicle is traveling, the motor for assisting steering can be controlled based on the absolute rotation position of the steering wheel detected in this way.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an electric power steering apparatus, a manufacturing method thereof, and a manufacturing apparatus according to the present invention will be described with reference to the drawings.
[First embodiment]
First, the main configuration of the electric power steering apparatus 20 according to the first embodiment will be described with reference to FIGS. As shown in FIGS. 1 and 5, the electric power steering apparatus 20 mainly includes a steering wheel 21, a steering shaft 22, a pinion shaft 23, a rack shaft 24, a torque sensor 30, a motor 40, a motor resolver 44, and a ball. It is composed of a screw mechanism 50, an ECU 60, and the like, and detects a steering state by the steering wheel 21 and generates an assist force corresponding to the steering state by the motor 40 to assist steering by the driver. Note that wheels (not shown) are connected to both sides of the rack shaft 24 via tie rods or the like.
[0038]
That is, as shown in FIGS. 1 and 2, one end side of a steering shaft 22 is connected to the steering wheel 21, and the other end side of the steering shaft 22 is connected to a torque sensor 30 housed in a pinion housing 25. The input shaft 23 a and the torsion bar 31 are connected by a pin 32. Further, the output shaft 23b of the pinion shaft 23 is connected to the other end 31a of the torsion bar 31 by spline coupling.
[0039]
The input shaft 23a of the pinion shaft 23 is rotatably supported in the pinion housing 25 by the bearing 33a, and the output shaft 23b is also rotatably supported by the bearing 33b. Further, between the input shaft 23a and the pinion housing 25, The first resolver 35 and the second resolver 37 are provided between the output shaft 23b and the pinion housing 25, respectively. The first resolver 35 and the second resolver 37 can detect the steering angle by the steering wheel 21 and are electrically connected to the ECU 60 via the terminals 39 (see FIG. 5). The configuration of the first and second resolvers 35 and 37 will be described in detail later.
[0040]
A pinion gear 23c is formed at an end portion of the output shaft 23b of the pinion shaft 23, and a rack groove 24a of the rack shaft 24 is coupled to the pinion gear 23c so as to be meshable. Thus, a rack and pinion mechanism is configured.
[0041]
With this configuration, the steering shaft 22 and the pinion shaft 23 can be connected to each other by the torsion bar 31 so as to be relatively rotatable, and the rotation angle of the steering shaft 22, that is, the rotation angle (mechanical angle) of the steering wheel 21. θTm can be detected by the first steering angle (electrical angle) θT1 by the first resolver 35 and the second steering angle (electrical angle) θT2 by the second resolver 37. Further, the torsion amount of the torsion bar 31 (corresponding to the steering torque) can be detected as the torsion angle from the angle difference between the first steering angle θT1 and the second steering angle θT2, the angle ratio, or the like.
[0042]
As shown in FIGS. 1 and 3, the rack shaft 24 is accommodated in a rack housing 26 and a motor housing 27, and a ball screw groove 24 b is formed in a spiral shape at an intermediate portion thereof. A cylindrical motor shaft 43 is provided around the ball screw groove 24 b and is supported by a bearing 29 so as to be rotatable coaxially with the rack shaft 24. This motor shaft 43 constitutes the motor 40 together with the stator 41, the excitation coil 42, etc., and the field generated by the excitation coil 42 wound around the stator 41 is generated on the outer periphery of the motor shaft 43 corresponding to the rotor. By acting on the permanent magnet 45 provided, the motor shaft 43 can be rotated.
[0043]
A ball screw nut 52 is attached to the inner periphery of the motor shaft 43, and the ball screw nut 52 is also formed with a ball screw groove 52a in a spiral shape. Therefore, a large number of balls 54 are movably interposed between the ball screw groove 52a of the ball screw nut 52 and the ball screw groove 24b of the rack shaft 24, whereby the rack shaft 24 is pivoted by the rotation of the motor shaft 43. A ball screw mechanism 50 that can move in the direction can be configured.
[0044]
In other words, the rotational torque of the motor shaft 43 rotating in the forward and reverse directions can be converted into the reciprocating motion in the axial direction of the rack shaft 24 by the ball screw mechanism 50 including both the ball screw grooves 24b and 52a. As a result, the reciprocating motion becomes an assist force that reduces the steering force of the steering wheel 21 via the pinion shaft 23 that constitutes the rack and pinion mechanism together with the rack shaft 24.
[0045]
A motor resolver 44 capable of detecting the rotation angle (electrical angle) θMe of the motor shaft 43 is provided between the motor shaft 43 of the motor 40 and the motor housing 27. The motor resolver 44 is not shown. It is electrically connected to the ECU 60 via a terminal (see FIG. 5).
[0046]
Here, the configuration of the first resolver 35, the second resolver 37, and the motor resolver 44 will be described with reference to FIG. Since these resolvers have substantially the same configuration, the common part will be described by using the first resolver 35 as a representative.
[0047]
As shown in FIG. 4A, the first resolver 35 includes a first yoke YK1, a second yoke YK2, a third yoke YK3, a fourth yoke YK4, a first coil CL1, a second coil CL2, and a third coil. It is a resolver having 5 counter electrodes (so-called 5X), which is composed of CL3 and a fourth coil CL4. The “number of counter electrodes” will be described later.
[0048]
The first yoke YK1 is formed in an annular shape along the inner periphery of the pinion housing 25 and is fixed to the pinion housing 25. A first coil CL1 is wound around the inner periphery of the first yoke YK1. On the other hand, the second yoke YK2 is formed in an annular shape like the first yoke YK1, and is fixed to the outer periphery of the input shaft 23a of the pinion shaft 23 so as to face the first yoke YK1, and the second coil CL2. Is wound. As a result, the second yoke YK2 can rotate integrally with the input shaft 23a.
[0049]
The third yoke YK3 is offset from the second yoke YK2 in the axial direction of the input shaft 23a, is fixed on the outer periphery of the input shaft 23a, and is configured to be rotatable integrally with the input shaft 23a. A third coil CL3 is wound around the third yoke YK3, and the third coil CL3 is electrically connected in parallel to the second coil CL2 of the second yoke YK2. On the other hand, the fourth yoke YK4 is formed in an annular shape along the inner periphery of the pinion housing 25 and is fixed to the pinion housing 25, like the first yoke YK1. The third coil CL3 and the fourth coil CL4 are composed of two types of coils whose phases are shifted by 90 degrees.
[0050]
In the second resolver 37, the second yoke YK2 and the third yoke YK3, the second coil CL2 and the third coil CL3 are provided on the output shaft 23b, and the number of counter electrodes is 6 (so-called 6X). The point is the same as that of the first resolver 35 except that the first resolver 35 is different from the first resolver 35.
[0051]
The motor resolver 44 includes a first yoke YK1 and a fourth yoke YK4, a first coil CL1 and a fourth coil CL4 provided in the motor housing 27, a second yoke YK2 and a third yoke YK3, The same as the first resolver 35 except that the two coils CL2 and the third coil CL3 are different from the first resolver 35 in that the motor shaft 43 is provided with a counter electrode number of 7 (so-called 7X). It is configured.
[0052]
Next, the electrical characteristics of the first resolver 35, the second resolver 37, and the motor resolver 44 will be described with reference to FIG. Since these resolvers have substantially the same electrical characteristics, the first resolver 35 will be described as a representative here.
[0053]
As described above, the first resolver 35 is constituted by the first coil CL1 to the fourth coil CL4, and each of these coils has a connection relationship according to a circuit diagram as shown in FIG. This is a two-phase output (voltage detection) type resolver. Therefore, the excitation signal E1 output from the output port P0 of the CPU 61 constituting the ECU 60 is given to the first coil CL1 and the second coil CL2 which are transformers via the buffer amplifier 63 of the ECU 60, and further, the one-phase excitation coil. By applying to the third coil CL3, the resolver output signals E2 and E3 corresponding to the detected angle θ (electrical angle) can be obtained from the fourth coil CL4 which is a two-phase output coil. Since the resolver output signal output from the first resolver 35 is an analog signal composed of a sin phase signal and a cos phase signal, the resolver output signal is built in the CPU 61 via the buffer amplifiers 64 and 65 of the ECU 60. By being input to the A / D converter, it is converted into a digital signal that can be processed by the CPU 61.
[0054]
In the first embodiment, the resolver output signal obtained from the first resolver 35 in this way is obtained as an electrical angle θT1 via the buffer amplifier 64 and from the second resolver 37 as shown in FIG. The resolver output signal is input to the CPU 61 as an electrical angle θT2 through the buffer amplifier 65.
[0055]
Here, the electrical angle θT1 obtained from the first resolver 35 has five peak points per one rotation (360 degrees) of the steering wheel 21. As described above, this is because the first resolver 35 is a resolver having 5 counter electrodes, and electrically has 5 sets of N poles and S poles. Therefore, 360 ° × 5 = This is because an electrical angle corresponding to 1800 ° can be output. That is, the first resolver 35 has a resolution five times that of a resolver having an electrical angle of 360 °.
[0056]
The electrical angle θT2 obtained from the second resolver 37 has six peak points per one rotation (360 degrees) of the steering wheel 21. As described above, this is because the second resolver 37 is a resolver having 6 counter electrodes and electrically has 6 sets of N poles and S poles, and therefore, 360 ° × 6 = for a mechanical angle of 360 °. This is because an electrical angle corresponding to 2160 ° can be output. That is, the second resolver 37 has a resolution six times that of a resolver with an electrical angle of 360 °.
[0057]
As described above, the first resolver 35 outputs the electrical angle θT1 as the resolver output signal, and the second resolver 37 outputs the electrical angle θT2 as the resolver output signal. As can be seen from FIG. 6, both signal waveforms have the same steering. The same value is not taken in the rotation angle of the wheel 21. Therefore, the CPU 61 performs a calculation process based on the electrical angle θT1 of the first resolver 35 and the electrical angle θT2 of the second resolver 37, thereby obtaining a high-resolution mechanical angle θTm for one rotation of the steering wheel 21. Obtainable.
[0058]
Next, torque detection based on resolver signals output from the first and second resolvers 35 and 37 will be described.
When the steering wheel 21 is steered by a driver or the like and the input shaft 23a of the pinion shaft 23 rotates at the rotation angle θ1, as shown in FIG. 4 (B), when an AC voltage El is applied to the first coil CL1. A magnetic flux is generated in the first yoke YK1 and the second yoke YK2 in accordance with the applied voltage.
[0059]
Since an AC voltage is induced in the second coil CL2 according to the change in magnetic flux at this time, an AC voltage is also generated in the third coil CL3 connected to the second coil CL2. By the AC voltage generated in the third coil CL3, an AC voltage is induced in the fourth coil CL4, and AC voltages E2 and E3 are output. At this time, two types of AC voltages E2 and E3 having different phases are output from the fourth coil CL4 composed of two types of coils, and these satisfy the relationship of the following formulas (1) and (2). .
[0060]
E2 = K ・ E1 × cosθ (1)
E3 = K · E1 x sinθ (2)
[0061]
In the above formulas (1) and (2), K represents a transformation ratio.
At this time, θ can be calculated from the above equations (1) and (2), and this angle θ becomes the rotation angle θ1 of the input shaft 23a of the pinion shaft 23. On the other hand, when the input shaft 23a rotates, the output shaft 23b of the pinion shaft 23 connected via the torsion bar 31 also rotates, so that the above-described equation (1) is obtained from the second resolver 37 provided on the output shaft 23b side. ) And Expression (2), the rotation angle θ2 of the output shaft 23b can also be calculated.
[0062]
Here, when the input shaft 23a and the output shaft 23b of the pinion shaft 23 are rotated, a relative rotation angle difference Δθ (= θ1−θ2) is generated between the input shaft 23a and the output shaft 23b due to the torsion of the torsion bar 31. . As a result, the steering torque T can be calculated from the relative rotation angle difference Δθ that is the twist angle of the torsion bar 31 and the rigidity of the torsion bar 31. Thus, by performing the known assist control for assisting the steering force in accordance with the steering torque T by the CPU 61 of the ECU 60, the steering by the driver can be assisted by the steering force generated by the motor 40 described above. .
[0063]
The detection of the rotation angle of the motor shaft 43 (hereinafter referred to as “motor rotation angle”) based on the resolver signal output from the motor resolver 44 can also be described as follows.
When the motor shaft 43 rotates at a certain rotation angle, when an AC voltage E1 is applied to the first coil CL1 of the motor resolver 44, a magnetic flux is generated in the first yoke YK1 in accordance with the applied voltage, and the magnetic flux is transferred to the second yoke. It is conveyed to YK2. Since this magnetic flux links the second coil CL2, an alternating voltage is induced, so that an alternating voltage is also generated in the third coil CL3 connected to the second coil CL2. An AC voltage is induced in the fourth coil CL4 by the AC voltage generated in the third coil CL3, and AC voltages E2 and E3 are output. Then, the motor rotation angle can be calculated from the applied AC voltage El and the output AC voltages E2 and E3 based on the aforementioned equations (1) and (2). The detected motor rotation angle is used for various controls in the electric power steering apparatus 20.
[0064]
Next, an absolute position detection process of the steering wheel 21 in the electric power steering apparatus 20 configured as described above will be described with reference to FIGS.
As described with reference to FIG. 5, the first resolver 35, the second resolver 37, and the motor resolver 44 are electrically connected to the CPU 61 constituting the ECU 60 via the buffer amplifiers 63, 64, 65. Yes. Although not shown in FIG. 5, the CPU 61 is connected to a semiconductor memory device as a main storage device and various interface devices.
[0065]
The first and second resolvers 35 and 37 can detect the steering angle (electrical angles θT1 and θT2) by the steering wheel 21, and the motor resolver 44 can detect the motor rotation angle (electrical angle θMe) by the motor 40, respectively. Therefore, in the first embodiment, processing for detecting the absolute position of the steering wheel 21 based on the electrical angles θT1, θT2, and θMe based on resolver output signals output from these three resolvers (hereinafter referred to as “absolute position detection processing”). "). This absolute position detection process is executed immediately after the ignition is turned on, and thereafter, as will be described later, the parameter A (which indicates the rotation range of the steering wheel 21 obtained by this absolute position detection process) Based on A = 1, 0, −1, −2), the parameter A (hereinafter simply referred to as “A”) is updated periodically (for example, every 5 milliseconds) by a timer interrupt or the like.
[0066]
As shown in FIG. 7, in the absolute position detection process, after a predetermined initialization process, first, a process of acquiring the electrical angles θT1, θT2, and θMe of each resolver is performed in step S101. That is, since the electrical angles θT1 and θT2 corresponding to the steering angle of the steering wheel 21 are detected by the first resolvers 35 and 37, the resolver signals output from the first resolvers 35 and 37 are converted into buffer amplifiers 64 and 65 and Since the electric angle θMe obtained through the A / D converter and corresponding to the motor rotation angle of the motor 40 is detected by the motor resolver 44, the resolver signal output from the motor resolver 44 is converted into a buffer amplifier 64, 65 and acquired via an A / D converter.
[0067]
In the subsequent step S103, processing for calculating the mechanical angle θTm of the steering wheel 21 from the electrical angles θT1 and θT2 is performed. That is, in the first embodiment, since the first resolver 35 is set to the number of counter electrodes 5 and the second resolver 37 is set to the number of counter electrodes 6, the steering wheel 21 is based on the electrical angles of two resolvers having different numbers of counter electrodes. The mechanical angle θTm can be calculated. This arithmetic processing is described in detail in the application specification of Japanese Patent Application No. 2002-196131 filed by the applicant of the present application, so please refer to that.
[0068]
In the next step S105, a process of calculating an arithmetic motor electrical angle θMe (A) for each rotation amount (A = 1, 0, −1, −2) is performed. For example, with the neutral position of the steering wheel 21 as the center, the rotation range of the steering wheel 21 to the right (0 degree <θ ≦ 360 degrees) is A = 0, and the right rotation range to the right (360 degrees <θ ≦ 720 degrees). ) A = 1, left rotation range around the neutral position (0 degree> θ ≧ −360 degrees) is A = −1, and left rotation range on the left side (−360 degrees> θ ≧ −720 degrees) ) For each rotation range when A = −2, four arithmetic motor electrical angles θMe (corresponding to A = 1, 0, −1, −2 are obtained by arithmetic processing according to the following equation (3). 1) Calculate θMe (0), θMe (-1), and θMe (-2). That is, in this step S105, a process for obtaining the arithmetic motor electrical angle θMe (A) is performed only for the total number of rotations of the steering wheel 21 (four rotations of the steering wheel in the first embodiment).
[0069]
θMe (A) = (θTm + 360 × A) × r (3)
[0070]
Here, r is an arithmetic value obtained by the product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44, and is a value that is at least a non-integer having a numerical value after the decimal point, as will be described later. Is a necessary condition. In the first embodiment, the reduction gear ratio of the ball screw mechanism 50 is set to 8.2, for example, and the counter electrode number of the motor resolver 44 is set to 7, for example, so that the calculated value is 57.4. (= 8.2 × 7), which has 0.4 as a numerical value after the decimal point.
[0071]
Further, in step S107, a process of rounding the four arithmetic motor electrical angles θMe (A) within a predetermined range is performed. That is, the process of calculating θMe (A) −INT (θMe (A) / 360) × 360 so that the calculation motor electrical angle θMe (A) calculated in step S105 falls within the range of 0 degree to less than 360 degrees. Is done. Here, INT () is a function that rounds off the number after the decimal point to the nearest integer. For example, INT (8.9) = 8 and INT (−8.9) = − 9.
[0072]
For example, when the arithmetic motor electrical angle θMe (−2) is −80 degrees, it is 280 degrees (= −80 degrees − (− 360 degrees)), and the arithmetic motor electrical angle θMe (1) is 380 degrees. 20 degrees (= 380 degrees-1 × 360 degrees) in the case, and further 320 degrees (= −400 degrees − (− 720 degrees)) when the calculation motor electrical angle θMe (2) is −400 degrees. Are converted and rounded.
[0073]
In the subsequent step S109, among the four arithmetic motor electrical angles θMe (A), in order to distinguish from the actual motor electrical angle θMe (hereinafter referred to as the arithmetic motor electrical angle θMe (A)), it is referred to as “actual motor electrical angle θMe”. The process of selecting the one closest to) is performed. That is, as will be described later, one of the four arithmetic motor electrical angles θMe (A) corresponding to the total number of rotations of the steering wheel 21 obtained in steps S105 and S109 is appropriate for the absolute position of the steering wheel 21. Therefore, in step S109, a process for selecting this is performed.
[0074]
As described in the application specification of Japanese Patent Application No. 2002-196131 filed by the applicant of the present application, the processing in step S109 is performed among the calculation motor electrical angles θMe (A) calculated in steps S105 and S109. Although the process for selecting the closest value to the integer value may be performed, in the first embodiment, the process for selecting the closest value to the actual motor electrical angle θMe detected by the motor resolver 44 is performed. Thus, the difference between the actual motor electrical angle θMe acquired in step S101 and all the calculated motor electrical angles θMe (A) is calculated, and the smallest difference is selected as the calculated motor electrical angle θMe (near). Since it is good, the algorithm by the said step S109 can be simplified compared with the process which selects the thing nearest to an integer value.
[0075]
In step S111, processing is performed to determine whether or not the arithmetic motor electrical angle θMe (near) selected in step S109 is truly appropriate. That is, the arithmetic motor electrical angle θMe (near) is selected by step S109 as the closest to the actual motor electrical angle θMe detected by the motor resolver 44. When the difference from the actual motor electrical angle θMe is equal to or greater than a predetermined threshold (for example, 10 degrees), the mechanical parts constituting the pinion shaft 23, the rack shaft 24, the ball screw mechanism 50, etc. are dimensional accuracy or due to wear. There is a high probability that dimensional errors and errors in temperature characteristics of semiconductor electrical components such as operational amplifiers that process resolver signals exceed the allowable values. A series of this absolute position detection processing is terminated abnormally to notify (ERROR).
[0076]
On the other hand, when the difference between the arithmetic motor electrical angle θMe (near) and the actual motor electrical angle θMe is less than a predetermined threshold value, the mechanical components and resolver constituting the pinion shaft 23, the rack shaft 24, the ball screw mechanism 50, and the like. Since it is not recognized that the semiconductor electrical component such as an operational amplifier for processing the signal is abnormal, the process proceeds to the subsequent step S113 to calculate the absolute steering angle θAm.
[0077]
That is, in step S113, A of the arithmetic motor electrical angle θMe (near) selected in step S109 (in the case of the first embodiment, A is 0, 1, -1, or -2) is The absolute steering angle θAm is calculated by substituting into (4) and performing arithmetic processing based on the mechanical angle θTm of the steering wheel 21 calculated in step S103. Thus, since the absolute position of the steering wheel 21 is detected, a series of the absolute position detection process ends normally.
[0078]
θAm = θTm + 360 × A (4)
[0079]
In addition, by periodically monitoring the mechanical angle θTm obtained from the first resolver 35 and the second resolver 37 (for example, every 5 milliseconds), the A thus obtained can be updated. After this absolute position detection process is executed, the absolute steering angle θAm can be calculated based on the above equation (4).
[0080]
That is, A is updated based on the following equations (4) ′ and (4) ″.
First, it is determined whether or not the angle obtained by subtracting the previous mechanical angle θTm-old from the current mechanical angle θTm of the steering wheel 21 exceeds 180 degrees, that is, whether or not the following equation (4) ′ is satisfied. If 4) 'is satisfied, the steering wheel 21 has turned left and has exceeded one rotation, so A is decremented (A = A-1), and the current mechanical angle θTm is set to the previous mechanical angle. Store as θTm-old.
[0081]
On the other hand, if the following equation (4) ′ is not satisfied, whether or not the angle obtained by subtracting the previous mechanical angle θTm-old from the current mechanical angle θTm is less than −180 degrees, that is, the following equation (4) ′ 'If it is determined whether or not, and the expression (4)' 'is satisfied, the steering wheel 21 is turned right and exceeds one rotation, so A is incremented (A = A + 1) Is stored as the previous mechanical angle θTm-old. If neither of the equations (4) ′ and (4) ″ is satisfied, the steering wheel 21 is rotated within the range of one rotation left and right, so A and the previous mechanical angle θTm There is no need to update -old, and the current A and mechanical angle θTm-old are retained.
[0082]
θTm-θTm-old> 180 [deg] (4) '
θTm − θTm-old <−180 [deg] (4) ''
[0083]
Since A can be appropriately updated by such an algorithm, the absolute steering angle θAm can be calculated based on the above equation (4) after the above-described absolute position detection processing is executed.
[0084]
Here, the reason why it is a necessary condition that the calculated value r of the above formula (3) calculated from step S105 is a non-integer value having a numerical value at least after the decimal point will be described.
[0085]
In the application specification of Japanese Patent Application No. 2002-196131, the applicant of the present application defines the steering angle by the torque sensor 30 as θt (the mechanical angle θTm) and the electrical angle θm by the motor rotation angle (the actual motor electrical angle θMe). ), The absolute position Pt of the steering wheel 21 by the torque sensor is expressed by the following equation (5), and the absolute position Pm of the steering wheel 21 by the motor rotation angle is expressed by the following equation (6). The calculated value r is the product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44.
[0086]
Pt = θt + 360 · A (5)
Pm = (θm + 360 · B) / r (6)
[0087]
Here, in equation (5), A is an integer and is −2, −1, 0, 1, and in equation (6), B is a mechanical system that theoretically connects the steering wheel 21 and the motor 40. If there is no electrical angle absolute accuracy error in the first resolver 35, the second resolver 37 of the torque sensor 30 or the motor resolver 44 of the motor 40, etc., it becomes an integer value, and a value of −126 to 125 is obtained. Take.
[0088]
Here, both the above formulas (5) and (6) represent the absolute position of the steering wheel 21, and since both formulas are equal, the following formula (7) is established and formula (8) is derived.
[0089]
θt + 360 · A = (θm + 360 · B) / r (7)
B = (r · (θt + 360 · A) −θm) / 360 (8)
[0090]
In the above formulas (5) to (8), in the above-mentioned application specification by the applicant of the present application, the calculation value r is replaced with 57.4. This is because if the movement distance of the rack shaft 24 during one rotation of the steering wheel 21 is Smm and the lead for one rotation of the ball screw mechanism 50 in the rack shaft 24 and the motor shaft 43 is L, the rack shaft 24 Since the motor shaft 43 rotates (S / L) while the motor moves by Smm, it is set to 8.2 as the reduction gear ratio of the ball screw mechanism 50, and the detection signal θm from the motor resolver 44 is set. Is set to 7 as the counter electrode number, so that the period Tm2 of the detection signal θm from the motor resolver 44 for one rotation of the steering wheel 21 (pinion shaft 23), that is, the reduction gear ratio of the ball screw mechanism 50 is obtained. And the counter electrode number of the motor resolver 44 is 57.4 (= Tm1 × (S / L) = 7 × 8.2).
[0091]
Here, as described above, B is a value that takes an integer theoretically, but actually, an error caused by rattling of a mechanical system that connects the steering wheel 21 and the motor 40, or the first of the torque sensor 30. The resolver 35, the second resolver 37, or the motor resolver 44 of the motor 40 has an electrical angle absolute accuracy error. Therefore, in reality, while B includes a value after the decimal point, four types of values are obtained as B from the above equation (8) according to the value of A (−2, −1, 0, 1). Therefore, when one appropriate value (true value) is selected as the absolute position of the steering wheel 21, confusion may occur with other three values (false values).
[0092]
In other words, in the application specification of Japanese Patent Application No. 2002-196131, processing is performed so as to select B closest to the integer value among all B values, and therefore, due to the backlash of the mechanical system as described above. In the case where there is an error or the like, an investigation by the present inventor that there is a possibility of selecting one of the other three values (false value) by mistake when selecting one appropriate value (true value).・ It became clear by research.
[0093]
For example, FIG. 8 shows the mechanical angle θTm (thin line) of the steering wheel 21 with respect to the rotation amount (A = −2, −1, 0, 1) of the steering wheel 21 and the actual motor electrical angle θMe (thick line) by the motor resolver 44. FIG. 8A is a characteristic diagram showing a change, FIG. 8A shows the case where the calculated value r = 3.75, FIG. 8B shows the case where the calculated value r = 3.05, 8 (C) is the case where the calculated value r = 4.00. The calculated value r is the product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44.
[0094]
As shown in FIG. 8A, when the numerical value after the decimal point of the calculated value r is set to 0.75 (for example, r = 3.75), for example, γa corresponding to the neutral position of the steering wheel 21 is a true value. , The other three values αa, βa, and δa, which are false values, are different from the true value γa by 90 degrees. In other words, FIG. 8A shows that there is a margin of 90 degrees from the adjacent value even if there is an error due to mechanical backlash, etc., and therefore between the true value γa and the false values αa, βa, δa. Indicates that the possibility of confusion is low.
[0095]
Further, as shown in FIG. 8B, when the numerical value after the decimal point of the calculated value r is set to 0.05 (for example, r = 3.05), γb corresponding to the neutral position of the steering wheel 21 is a true value. Then, the other three values that are the false values αb, βb, and δb are not different from the true value γb by about 10 degrees. That is, in FIG. 8B, since the margin is only about 10 degrees from the adjacent value, the true value γb and the false values αb, βb, and δb depend on the magnitude of the error due to the backlash of the mechanical system. It shows that there is a possibility of confusion between them.
[0096]
On the other hand, as shown in FIG. 8C, when the numerical value after the decimal point of the operation value r is set to 0 (zero) (for example, r = 4.00), γc corresponding to the neutral position of the steering wheel 21 is a true value. However, since the other false values αc, βc, and δc have similar values (zero margin), the true value γc cannot be distinguished from the false values αc, βc, and δc. That is, FIG. 8C shows that the true value γc cannot be specified from the other false values αc, βc, δc.
[0097]
Thus, from FIG. 8, in the above-described step S109, the reduction gear ratio of the ball screw mechanism 50 and the motor are selected in selecting the true value from the plurality of arithmetic motor electrical angles θMe (A) without being confused with the false value. It can be seen that the value of r, which is the product of the counter electrode number of the resolver 44, has a great influence, and in particular, when the value of the operation value r is an integer, it can be seen that the true value cannot be specified. As described above, this is the basis for the requirement that the calculated value r of Equation (3), which is calculated from step S105, is a non-integer value having a numerical value at least after the decimal point.
[0098]
Next, the influence that such a margin can be affected by an error caused by rattling of the mechanical system constituting the electric power steering apparatus 20 will be described with reference to FIGS. 8 and 9. FIG. 9 is a characteristic diagram showing a change in the true value detection margin with respect to the numerical value after the decimal point of the calculated value r, and the basis of this characteristic diagram will be described later.
[0099]
The true value detection margin is a true value of four types (A = −2, −1, 0, 1) of the arithmetic motor electrical angle θMe (A) obtained as described above. The difference from the false value closest to the true value is expressed as an absolute value (0 degree ≦ minimum deviation <180 degree). For example, in the example of FIG. 8B, the difference (for example, 20 degrees) between the true value (γb) and the false value (δb) closest to the true value (γb). The true value detection margin corresponds to “angle deviation of motor electrical angle” recited in the claims.
[0100]
For example, in the first embodiment, assuming that the error due to the backlash of the mechanical system is ± 0.24 degrees and the detection accuracy of the torque sensor 30 is ± 0.16 degrees, as described above, the electrical angle θT1 The error of the mechanical angle θTm of the steering wheel 21 calculated from θT2 is 0.4 degrees due to the sum of the two.
[0101]
Here, since the motor electrical angle θMe (A) is obtained by the above equation (3), for example, the arithmetic motor electrical angle θMe (0) when A = 0, θTm = 0, r = 60.76 is θTm When calculating by substituting θTm = (0 + 0.4) into equation (3), including the error of 0.4, ((0 + 0.4) + 360 × 0) × 60.76 = 24.3 (degrees) become. That is, 0.4 of the error is multiplied by r (here, 60.76 times) and appears as the arithmetic motor electrical angle θMe (A). Then, if it is calculated in consideration of the fact that such an error can occur in both the true value and the fake value adjacent thereto, it is necessary to double this, and therefore it is twice 24.3 degrees. It will be 6 degrees.
[0102]
Therefore, as described with reference to FIG. 8A, even if the true value has a margin of 90 degrees with the adjacent value, the calculation motor electrical angle θMe ( Since an error of approximately 50 degrees (≈48.6 degrees) can occur in A), the margin is limited to 40 degrees (= 90-50) at the maximum. When such an error range is shown in FIG. 9, the boundary of the error range can be clearly indicated by drawing a one-dot chain line with a true value detection margin of 50.0 (deg).
[0103]
Further, as described with reference to FIG. 7, in the first embodiment, the difference between the calculated motor electrical angle θMe (near) and the actual motor electrical angle θMe is set to a predetermined threshold value in step S111 of the absolute position detection process. It is determined whether or not (for example, 10 degrees) or more, and if it is equal to or more than the predetermined threshold value, the process is abnormally terminated (ERROR). Therefore, 60 degrees (= 50 + 10), which is a value obtained by adding the predetermined threshold (for example, 10 degrees) to the boundary (50 degrees) of the error range, is set as the lower limit value of the angle deviation of the arithmetic motor electrical angle θMe (A). (A broken line with a true value detection margin of 60.0 (deg) shown in FIG. 9).
[0104]
That is, as shown in FIG. 9, the true value detection margin is set to a numerical value below the decimal point of the calculated value r so that the true detection margin is in the range of 60.0 degrees to 90.0 degrees (the hatched area shown in FIG. 9). If set, even if there is an error due to rattling of the mechanical system constituting the electric power steering device 20, in step S109 described above, a plurality of arithmetic motor electrical angles θMe (A) are confused with false values. The true value can be selected without any change.
[0105]
Specifically, since the true value detection allowance 60.0 degrees is 67% (= 60/90) of 90 degrees which is the maximum value of the broken line K, the true value detect allowance is 60.0 degrees or more. 90.0 degrees or less means 67% or more and 100% or less of the maximum value of the broken line K indicating the change in the true value detection margin with respect to the numerical value of the calculated value r after the decimal point. The numerical values after the decimal point of the calculated value r in this range are “0.17 to 0.28”, “0.39 to 0.42”, “0.58 to 0.61” from FIG. ”And“ 0.72 or more and 0.83 or less ”, and when such a calculated value r is set, in step S109 described above, a plurality of calculated motor electrical angles θMe (A) are used as false values. The true value can be selected without confusion.
[0106]
In addition, about 90 degrees of 100% which is the upper limit of the error range, as can be seen from FIG. 8A, the steering wheel 21 rotates four times as A = −2, −1, 0, 90 (= 360/4) degrees obtained by dividing 360 degrees by this value 4 is the middle of false values (βa, δa) located on both sides of the true value (γa) in terms of angle, and has the highest margin. From this is set.
[0107]
Next, the basis of the characteristic diagram (broken line K) showing the change in the true value detection margin with respect to the numerical value after the decimal point of the calculated value r shown in FIG. 9 will be described with reference to FIGS. 10 and 11. FIG. 10A shows a characteristic indicating a change in deviation of the calculated value r from the calculated motor electrical angle θMe (−2) with respect to the numerical value after the decimal point.
[0108]
For example, from the above equation (3), the arithmetic motor electrical angle θMe (A) is obtained by (θTm + 360 × A) × r. Therefore, when A = −2, the arithmetic motor electrical angle θMe (−2) Is (θTm + 360 × (−2)) × 57.4. Similarly, when A = −1, the arithmetic motor electrical angle θMe (−1) is (θTm + 360 × (−1)) × 57.4. become. The difference between the two is θMe (−1) −θMe (−2) = 360 × 57.4. Since the value after the decimal point is 0.4, 360 × 0.4 = 144 ( (See FIG. 10 (A)).
[0109]
As described with reference to FIG. 8C, when the numerical value after the decimal point of the calculated value r is 0 (zero), the four types of rotation amounts of the steering wheel 21 (A = −2, −1) , 0, 1), since the arithmetic motor electrical angle θMe (A) takes the same value, the true value and the false value cannot be discriminated. That is, in FIG. 10 (A), when the numerical value after the decimal point of the calculated value r is 0 (zero), the deviation from the broken line of A = -2 is 0. Both the dotted line of A = 0 and the one-dot chain line of A = 1 have a value of 0 (zero).
[0110]
On the other hand, when the numerical value after the decimal point is gradually increased, the deviation of the A = −1 solid line, the A = 0 dotted line, and the A = 1 dashed line from the A = −2 broken line increases. . At this time, the positive slope amount increases in the order of the solid line of A = −1, the dotted line of A = 0, and the one-dot chain line of A = 1. As can be seen from the above equation (3), A and This is because the product value 360 is further multiplied by the operation value r. Thus, with reference to the broken line of A = -2, the solid line of A = -1 changes from 0 degrees to 360 degrees, and the dotted line of A = 0 starts from 0 degrees, which is twice the solid line of A = -1. It changes up to 720 degrees. It can be seen from FIG. 10A that the one-dot chain line of A = 1 changes from 0 degrees to 1080 degrees, which is three times the solid line of A = -1.
[0111]
In this way, when the deviation of the arithmetic motor electrical angle θMe (A) is A = −1 by changing the numerical value after the decimal point of the arithmetic value r from 0 to 1 on the basis of the broken line of A = −2, A = 0 In the case of A = 1, when A = 1 is obtained, it can be seen that there is a relationship as shown in FIG. 10 (A) between them, but by expressing this deviation by folding it back at 180 degrees, FIG. A mountain-shaped characteristic diagram as shown in B) can be obtained. In FIG. 10B, the broken line with A = -2 is omitted.
[0112]
That is, the solid line of A = −1 increased linearly from 0 degree to 360 degrees in FIG. 10A, but turns back at 180 degrees in FIG. When the numerical value reaches 0.5, it turns back and decreases linearly with a negative slope, forming an isosceles triangular fold line (solid line).
[0113]
In addition, the dotted line of A = 0 increased linearly from 0 degrees to 720 degrees in FIG. 10 (A), but in FIG. 10 (B), it is folded back at 180 degrees and 0 degrees. When the numerical value after the decimal point of r reaches 0.25, 0.5, and 0.75, the return increase / decrease is repeated twice to form two isosceles triangles (dotted lines).
[0114]
Further, the one-dot chain line of A = 1 increased linearly from 0 degrees to 1080 degrees in FIG. 10 (A), but in FIG. 10 (B), it is folded back at 180 degrees and 0 degrees. When the numerical value after the decimal point of the value r reaches 0.167, 0.333, 0.5, 0.667, 0.833, the return increase / decrease is repeated three times, and a broken line (one point) consisting of three isosceles triangles Chain line).
[0115]
Each broken line represented in this way is true as the deviation from the broken line of A = -2 approaches 0 (zero) when the arithmetic motor electrical angle θMe (-2) in the case of A = -2 is a true value. This indicates that confusion is likely to occur between the calculation motor electrical angle θMe (-2), which is the value, and other calculation motor electrical angles θMe (-1), θMe (0), θMe (1), which are false values. Therefore, when a false value closest to the true value θMe (−2) is selected from each broken line, a broken line K (thick dashed line in FIG. 10B) can be generated. That is, this broken line K is a characteristic (broken line K) showing the change in the true value detection margin with respect to the numerical value below the decimal point of the calculated value r as shown in FIG.
[0116]
In FIG. 10, the numerical value after the decimal point of the calculated value r is changed from 0 to 1 on the basis of the broken line of A = -2, and the deviation of the calculated motor electrical angle θMe (A) is expressed as A = −1, 0. 11, the deviation of the arithmetic motor electrical angle θMe (A) is obtained for each case of A = −2, 0, 1 with reference to the broken line of A = −1. It is expressed as shown in A). Further, by expressing each deviation shown in FIG. 11A by turning back at 180 degrees, a mountain-shaped characteristic diagram as shown in FIG. 11B can be obtained. When A = −1 When the calculation motor electrical angle θMe (-1) is set to a true value, a false value closest to the calculation motor electrical angle θMe (-1), which is a true value, is selected from the respective broken lines, and then a broken line L (FIG. 11) is selected. (B) A thick one-dot chain line) can be generated. In FIG. 11B, the solid line A = −1 is omitted.
[0117]
Further, when the deviation of the arithmetic motor electrical angle θMe (A) is obtained for each case of A = −2, −1, 1 with reference to the broken line of A = 0, if A = −1, 1, then A Since the shift is the same from = 0, and further when A = -2, the table is the same as in the case where the broken line of A = -1 shown in FIGS. 11 (A) and 11 (B) is used as a reference. Is done.
[0118]
Further, when the deviation of the arithmetic motor electrical angle θMe (A) is obtained for each case of A = −2, −1, 0 based on the broken line of A = 1, when A = 0, A = −1 In the case of A = -2, the order is shifted in the order of A = -2, and therefore, it is expressed in the same manner as the case where the broken line of A = -2 shown in FIGS. 10 (A) and 10 (B) is used as a reference. The
[0119]
Further, comparing the characteristic diagram according to FIG. 10B and the characteristic diagram according to FIG. 11B, the calculation value r = 0.5 by A = −1 shown in FIG. The characteristics of an isosceles triangle having a maximum value) and the characteristics of an isosceles triangle having an apex (maximum value) of an operation value r = 0.5 by A = 0 and -2 shown in FIG. The two isosceles sides having the same characteristics and having apexes (maximum values) of the calculation value r = 0.25 by A = 0 and the calculation value r = 0.75 by A = 0 shown in FIG. The characteristic of the triangle shape and two isosceles triangle shapes with the calculated value r = 0.25 by A = 1 and the calculated value r = 0.75 by A = 0 as shown in FIG. It can be seen that these characteristics are the same characteristics.
[0120]
Thus, the broken line L obtained when the deviation of the arithmetic motor electrical angle θMe (A) is obtained for each case of A = −2, 0, 1 with reference to the broken line of A = −1 (FIG. 11 (B)). Or a broken line (a broken line shown in FIG. 11B) obtained when the deviation of the arithmetic motor electrical angle θMe (A) is obtained for each of A = −2, −1, and 1 with reference to the broken line of A = 0. As for L), a range around the maximum value (about 120 degrees) (for example, 60 degrees or more and 120 degrees or less) is 60.0 degrees or more and 90.0 degrees or less by the broken line K shown in FIG. It is included in the range (shaded area). Therefore, even when the broken line with A = −1, 0 is used as a reference, the range of 60.0 degrees or more and 90.0 degrees or less (shaded area) by the broken line K shown in FIG. 9 can be applied as it is.
[0121]
As described above, according to the electric power steering apparatus 20 according to the first embodiment, the calculated value r by the product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44 is a numerical value after the decimal point. Since the speed reduction gear ratio is set so as to be a non-integer having a value, the numerical value after the decimal point is not 0 (zero), that is, an integer. Thus, the mechanical angle θTm of the steering wheel 21 determined by the electrical angle θT1 of the first resolver 35 and the electrical angle θT2 of the second resolver 37 is any one of the total four rotations of the left and right rotations of the steering wheel 21. Since it is possible not to take the same value in the rotation range unit (A = −2, −1, 0, 1), the absolute value of the steering wheel 21 is determined in step S109 of the absolute position detection process executed by the CPU 61 of the ECU 60. The steering angle θAm can be accurately detected. Therefore, the ECU 60 can control the motor 40 that assists the steering based on the absolute steering angle θAm of the steering wheel 21 detected in this way.
[0122]
Even if the counter electrode number of the motor resolver 44 is set so that the operation value r by the product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44 becomes a non-integer having a numerical value after the decimal point. The mechanical angle θTm of the steering wheel 21 determined by the electrical angle θT1 of the first resolver 35 and the electrical angle θT2 of the second resolver 37 is any one rotation range of the total four rotations of the left and right rotations of the steering wheel 21. Since the unit (A = −2, −1, 0, 1) can be prevented from taking the same value, the absolute steering angle of the steering wheel 21 in step S109 of the absolute position detection process executed by the CPU 61 of the ECU 60. θAm can be accurately detected. As a result, as in the case where the reduction gear ratio of the ball screw mechanism 50 is set, the ECU 60 can control the motor 40 that assists the steering based on the absolute steering angle θAm of the steering wheel 21.
[0123]
Further, in the electric power steering apparatus 20 according to the first embodiment, the numerical value after the decimal point of the calculated value r is within a predetermined range, and the predetermined range is a total of four rotations for each two left and right rotations of the steering wheel 21. A = −2, −1, 0, 1 and the difference between the calculation motor electrical angle θMe (−2) for each rotation range is 67% or more and 100% or less of the maximum value of the deviation, below the decimal point of the calculation value r Set to the number of. As a result, the mechanical angle θTm of the steering wheel 21 is increased due to the dimensional accuracy of the mechanical parts constituting the pinion shaft 23, the rack shaft 24, the ball screw mechanism 50, etc. Even when a detection error occurs, adjacent one rotation range units (for example, in the example of FIG. 10, between the rotation range A = −2 and the rotation range A = −1, the rotation range A = −1. And the rotation range A = 0 and between the rotation range A = 0 and the rotation range A = 1). Therefore, even if such an error can occur, the absolute steering angle θAm of the steering wheel 21 can be accurately detected. Therefore, based on the absolute steering angle θAm of the steering wheel 21 thus detected. The ECU 40 can control the motor 40 that assists steering.
[0124]
Furthermore, in the manufacturing method or the manufacturing apparatus of the electric power steering apparatus 20 and the electric power steering apparatus 20 according to the first embodiment, the numerical value after the decimal point of the calculated value r is determined every two rotations of the steering wheel 21 left and right. The calculation value when the deviation from the calculation motor electrical angle θMe (−2), which is different for each rotation range of A = −2, −1, 0, 1 in total 4 rotations, is 67% or more and 100% or less of the maximum value of the deviation Within the numerical range of the decimal point of r, for example, “0.17 to 0.28”, “0.39 to 0.42”, “0.58 to 0.61” and “0.72 to 0. 83 ”or less”, or by providing the steps and means for setting as described above, the error in the dimensional accuracy of mechanical parts constituting the pinion shaft 23, the rack shaft 24, the ball screw mechanism 50, etc. signal Even if a detection error occurs in the mechanical angle θTm of the steering wheel 21 due to a temperature characteristic error of the electrical component to be processed, adjacent one rotation range units due to such an error (for example, in the example of FIG. 10, the rotation range A = −2). And the rotation range A = −1, between the rotation range A = −1 and the rotation range A = 0, and between the rotation range A = 0 and the rotation range A = 1). Can be. Therefore, even if such an error can occur, the absolute steering angle θAm of the steering wheel 21 can be accurately detected. Therefore, based on the absolute steering angle θAm of the steering wheel 21 thus detected. The motor 40 that assists steering can be controlled by the ECU 60, and a controllable electric power steering apparatus can be manufactured.
[0125]
In addition, in the manufacturing method or manufacturing apparatus of the electric power steering apparatus 20, the numerical value after the decimal point of the calculated value r is, for example, “0.17 or more and 0.28 or less”, “0.39 or more and 0.42 or less”, In the process or means for setting “0.58 or more and 0.61 or less” and “0.72 or more and 0.83 or less”, for example, the reduction gear ratio of the ball screw mechanism 50 is expressed by the following equations (9), (10): You may set as follows.
[0126]
Reduction gear ratio = specific stroke / lead (9)
Reduction gear ratio = (module x number of pinion teeth x pi / cos (rack helix angle)) / lead (10)
[0127]
Further, in the first embodiment described above, the case where the steering wheel 21 rotates four times in total by two left and right rotations has been described as an example, but the present invention is not limited to this, and the steering wheel rotates two or more times. If there is, for example, the case of two rotations of one rotation left and right, the rotation of six rotations of three rotations of right and left, or the case of three rotations of 1.5 rotations of left and right, the same as described above The technical effects and effects can be obtained.
[0128]
[Second Embodiment]
Next, a second embodiment according to the electric power steering apparatus of the present invention will be described with reference to FIGS.
Hereinafter, in the electric power steering apparatus 120 according to the second embodiment to be described, an arithmetic value r that is a product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44 is less than the decimal point. For example, the numerical value is set to take 0.33 or 0.50. In the second embodiment, when the counter electrode number of the motor resolver 44 is 7, for example, by setting the reduction gear ratio of the ball screw mechanism 50 to 8.19, for example, the calculated value r = 57.33 (= 8. 19 × 7). Thereby, the numerical value after the decimal point of the calculation value r is set to 0.33.
[0129]
Thus, by setting the numerical value after the decimal point of the calculated value r to 0.33 or 0.50, as described later, the vertex of the broken line K shown in FIG. Since it can be increased, the boundary of the error range (one-dot chain line shown in FIG. 9) and the lower limit value of the angle deviation of the arithmetic motor electrical angle θMe (A) (the broken line of the true value detection allowance 60.0 (deg)) Can be raised. Thereby, for example, even when the error in the dimensional accuracy of the mechanical parts constituting the steering mechanism is extremely large, the absolute steering angle θAm of the steering wheel 21 can be accurately detected.
[0130]
However, when the numerical value after the decimal point of the calculated value r is set to 0.33 or 0.50 in this way, a new problem as shown in FIGS. 12A and 12B occurs. In FIGS. 12 (A) and 12 (B), with the steering wheel neutral position as the center, the steering wheel's right rotation range (0 ° <θ ≦ 360 °) is A = 0, and further to the right One rotation range (360 ° <θ ≦ 720 °) A = 1, left rotation center (0 °> θ ≧ −360 °) A = −1, and further left one rotation The range (−360 degrees> θ ≧ −720 degrees) is A = −2.
[0131]
That is, as shown in FIG. 12A, for example, when the numerical value after the decimal point of the calculated value r is set to 0.33 (for example, r = 3.33), αd and δd having the same value are 2 Since it appears at a location (A = -2 and A = 1), if any of them is a true value, it cannot be determined which one can be selected to obtain a true value.
[0132]
As shown in FIG. 12B, when the numerical value after the decimal point of the calculated value r is set to 0.50 (for example, r = 3.50), “αe and γe” having the same value and “Βe and δe” appear in two sets of two locations (A = −2 and A = 0, A = −1 and A = 1). Therefore, even in such a case, if any of them is a true value, it cannot be determined which one can be selected to obtain a true value.
[0133]
That is, in the electric power steering apparatus 20 according to the first embodiment described above, the numerical values after the decimal point of the calculated value r are “0.17 or more and 0.28 or less”, “0.39 or more and 0.42 or less”, By setting any of “0 · 58 to 0.61” and “0.72 to 0.83”, each rotation range of the steering wheel 21 (A = −2, −1, 0, 1) However, by setting the numerical value after the decimal point of the calculated value r to 0.33, for example, the rotational range A = −2, −1, 0 or A = -1, 0, 1 can be configured to detect the amount of rotation (hereinafter, the rotation range A = -2, -1, 0, 1 can be detected as "N4 type", Rotation range A = -2, -1, 0 or A = -1, 0, 1 What can be detected is referred to as "N3 type."). Further, the numerical value after the decimal point of the calculated value r is set to 0.50, for example, so that the rotation amount can be detected in the rotation range A = −2, −1 or A = 0, 1 of the steering wheel 21. (Hereinafter, those capable of detecting the rotation range A = −2, −1 or A = 0, 1 will be referred to as “N2 type”).
[0134]
Therefore, in the electric power steering apparatus 120 according to the second embodiment, by adopting the configuration shown in FIGS. 13 and 14, the numerical value after the decimal point of the calculated value r is set to 0.33 or 0.50. Even if it is set (that is, N3 type or N2 type), the true value is specified from “αd and δd” or “αe and γe” and “βe and δe” having the same value, and the same as that of the N4 type In the range, the absolute steering angle θAm of the steering wheel 21 can be accurately detected. In the configuration shown in FIGS. 13 and 14, substantially the same components as those of the electric power steering apparatus 20 (FIGS. 1 and 5) described above are denoted by the same reference numerals, and the description thereof is omitted. Omitted.
[0135]
As shown in FIGS. 13 and 14, the electric power steering apparatus 120 is mainly similar to the electric power steering apparatus 20 according to the first embodiment described above, and mainly includes a steering wheel 21, a steering shaft 22, The ECU includes a pinion shaft 23, a rack shaft 24, a torque sensor 30, a motor 40, a motor resolver 44, a ball screw mechanism 50, an ECU 160, and the like. The difference from the electric power steering apparatus 20 described above is that an on / off signal is input from the ignition switch sensor 163 and that the ECU 160 includes a nonvolatile memory 161 (see FIGS. 1 and 5). Other mechanical components and their functions are the same as those of the electric power steering apparatus 20 described above, and the steering state by the steering wheel 21 is detected and an assist force corresponding to the steering state is generated by the motor 40. Assist the driver to steer. Note that wheels (not shown) are connected to both sides of the rack shaft 24 via tie rods or the like.
[0136]
The lock mechanism 130 added in the second embodiment is configured to rotate the steering wheel 21 connected to the steering shaft 22 when the ignition switch IGSW is turned off or when the ignition key is removed after the ignition switch IGSW is turned off. Is provided for the purpose of preventing theft of the vehicle.
[0137]
The predetermined rotation range is, for example, less than one rotation (over 0 degree and less than 360 degrees) for the N3 type, and less than half rotation (more than 0 degree and less than 180 degrees) for the N2 type. This refers to the rotatable range of the wheel 21. The lock mechanism 130 employs a known configuration (for example, Japanese Patent Publication No. 50-39299, Japanese Patent Laid-Open No. 47-8411, etc.), and therefore detailed description thereof is omitted.
[0138]
As shown in FIG. 14, an ignition switch sensor 163 that can detect the on / off state of the ignition switch IGSW is connected to the input boat Pl of the ECU 160 that constitutes the electric power steering apparatus 120. As a result, the ECU 160 receives an ignition switch signal for notifying the ON / OFF state of the ignition switch IGSW, so that the CPU 61 immediately before the ignition switch IGSW enters the OFF state, the first resolver 35, the second resolver 37, and the motor resolver. The absolute steering angle θAm (absolute rotation position) of the steering wheel 21 obtained from 44 can be stored in the nonvolatile memory 161 as the IG off-time steering angle θAm-off (IG off absolute rotation position). The absolute steering angle θAm of the steering wheel 21 is obtained by the absolute position detection process shown in FIG.
[0139]
That is, as shown in FIG. 15, the CPU 61 constituting the ECU 160 performs the following process in the steering angle storing process at the time of IG off.
First, in step S201, based on the ignition switch signal input from the ignition switch sensor 163, it is determined whether or not the ignition switch IGSW has shifted from the on state to the off state. When the ignition switch IGSW is turned off (Yes in S201), in the subsequent step S203, the current absolute steering angle θAm is set as the steering angle θAm-off at the time of IG off, and a nonvolatile memory (for example, EEPROM or battery backup) (SRAM, DRAM, etc.) 161 is stored. Even if “current one rotation range A (= −2, −1, 0, 1)” is stored in the nonvolatile memory instead of “current absolute steering angle θAm”, an absolute position detection process (to be described later) ( In 1 and 2), the same processing as the steering angle θAm-off at the time of IG off can be performed.
[0140]
As a result, the absolute steering angle θAm of the steering wheel 21 obtained immediately before the ignition switch IGSW is turned off is stored in the nonvolatile memory 161 as the steering angle θAm-off at the time of IG off. Is turned on, the steering angle θAm-off when the IG is off can be read from the nonvolatile memory 161. Note that step S203, the CPU 61, and the nonvolatile memory 161 correspond to “storage means” recited in the claims.
[0141]
Next, the flow of the absolute position detection process (part 1) by the CPU 61 constituting the ECU 160 will be described with reference to FIGS. 16 to 18 and FIG. The absolute position detection process (No. 1) described here is applicable to the case where the numerical value after the decimal point of the calculated value r is set to, for example, 0.33 (N3 type). In steps S305, S307, S309, S311, S313, S323, and S325 constituting the absolute position detection process shown in FIG. 16, steps S10l, S103, S105, Sl07, Sl09, Sll1, The same processing as in S13 is performed. Therefore, description of the processing content by these steps is omitted.
[0142]
As shown in FIG. 16, in the absolute position detection process, first, in step S301, based on the ignition switch signal input from the ignition switch sensor 163, it is determined whether or not the ignition switch IGSW has shifted from the off state to the on state. To do.
[0143]
When it is determined that the ignition switch IGSW has been turned on (Yes in S301), a process of reading the IG off-time steering angle θAm-off from the nonvolatile memory 161 is performed in step S303. The IG off-time steering angle θAm-off read out in step S303 is stored in the non-volatile memory 161 by the IG off-time steering angle storage processing shown in FIG. 15, so that the ignition switch IGSW is turned off. This corresponds to the absolute steering angle θAm of the steering wheel 21 obtained immediately before. Further, when the ignition switch IGSW is turned off, the rotation range of the steering wheel 21 is restricted to less than one rotation or the like by the lock mechanism 130. Therefore, the rotation range of the steering wheel 21 and the steering angle when the IG is off. Based on θAm-off, the range of the absolute steering angle θAm of the steering wheel 21 immediately after turning on the ignition switch IGSW can be specified as will be described later.
[0144]
When the process of reading the steering angle θAm-off at the time of IG off from the nonvolatile memory 161 is performed in step S303, subsequently, in steps S305 to S313, as in steps S10l to S09 shown in FIG. From the electrical angles θTl, βT2, and θMe acquired from 44, processing for calculating the current mechanical angle θTm of the steering wheel 21 and the arithmetic motor electrical angle θMe (A) is performed, and four arithmetic motor electrical angles θMe ( Of A), the process of selecting the one closest to the actual motor electrical angle θMe is performed. That is, in order to obtain the current (current) absolute steering angle θAm of the steering wheel 21, the most appropriate arithmetic motor electrical angle θMe (A) is selected.
[0145]
In the subsequent step S315, the one rotation range A of the arithmetic motor electrical angle θMe (A) selected in step S313 is any of the four types of rotation amounts (A = −2, −1, 0, 1) of the steering wheel 21. A process for determining whether or not it corresponds is performed.
That is, as shown in FIG. 12 (A), one rotation of the steering wheel 21 is detected in the N3 type rotation range (A = −2, −1, 0 or A = −1, 0, 1). When the range is A = 1 or A = −2, the absolute steering angle θAm (αd and δd shown in FIG. 12A) of the steering wheel 21 in both ranges cannot be determined. Therefore, in this step S315, the case where the absolute steering angle θAm of the steering wheel 21 can be determined (A = 0 or −1) and the case where it cannot be determined (A = 1 or −2) are distinguished based on the value of one rotation range A. Judgment processing is performed.
[0146]
If it is determined in step S315 that the absolute steering angle θAm can be determined from the value of one rotation range A of the steering wheel 21 (A = 0 or −1 in step S315), the process proceeds to step S323, and the absolute If it is determined that the steering angle θAm can be determined (A = 1 or −2 in step S315), the process proceeds to step S317.
[0147]
Step S317 is performed when the current (current) one-turn range of the steering wheel 21 is A = 1 or -2, that is, when the steering wheel 21 exceeds one right turn from the neutral position (A = 1) or from the neutral position. In a determination process that is performed when the vehicle is positioned in a range exceeding one left turn (A = −2), it is determined whether or not the steering angle θAm-off at the time of IG off is 0 ° or more.
[0148]
That is, the rotation range of the steering wheel 21 when the ignition switch IGSW is off is read from the nonvolatile memory 161 because it is restricted to less than one rotation (360 degrees) by the lock mechanism 130 as described above. If the steering angle θAm-off at the time of the previous IG off is 0 degree or more (Yes in Step S317), the steering angle is at least on the right side of the neutral position of the steering wheel 21 and the steering angle θAm-off at the time of IG off. If it is not greater than 0 degrees (No in step S317), at least the steering wheel 21 is positioned on the left rotation side with respect to the neutral position.
[0149]
That is, as shown in FIG. 12 (A), when the steering angle θAm-off at the time of IG off is 0 degree or more, the neutral position N (absolute steering angle θAm at the leftmost rotation side when the ignition switch IGSW is off). Even if it is assumed that the steering wheel 21 is located at 0 degree), the rotation range θN3LK of the steering wheel 21 is restricted to “−360 degrees <θN3LK ≦ 0 degrees” by the lock mechanism 130. The wheel 21 is not positioned in a rotation range (A = −2) exceeding 360 degrees from the neutral position N to the left rotation side. Therefore, when the IG off-time steering angle θAm-off is equal to or greater than 0 degree, it can be determined that the current one rotation range A of the steering wheel 21 is A = 1.
[0150]
On the other hand, when the steering angle θAm-off at the time of IG off is not 0 ° or more, the steering wheel 21 is positioned at the neutral position N (absolute steering angle θAm = 0 °) which is the most clockwise side when the ignition switch IGSW is off. Even if it is assumed that the rotation range θN3LK of the steering wheel 21 is restricted to “0 ° ≦ θN3LK <360 °” by the lock mechanism 130, the current steering wheel 21 is 360 ° clockwise from the neutral position N. It is not located in the rotation range exceeding A degree (A = 1). Therefore, when the steering angle θAm-off at the time of IG off is not 0 ° or more, it can be determined that the current one rotation range A of the steering wheel 21 is A = −2.
[0151]
Accordingly, when it is determined in step S317 that the IG off-time steering angle θAm-off is 0 ° or more (Yes in S317), one rotation range A = of the selected arithmetic motor electrical angle θMe (A). 1 is selected in step S319, and if it is not determined in step S317 that the IG off-time steering angle θAm-off is greater than or equal to 0 degrees (No in S317), the selected calculation motor electrical angle Of θMe (A), one rotation range A = −2 is selected in step S321.
[0152]
When the arithmetic motor electrical angle θMe (A) is selected in step S313, step S319, or step S321 in this manner, the selected arithmetic motor electrical angle is selected in step S323 in the same manner as in step S111 shown in FIG. A process for determining whether or not θe (A) is really proper is performed, and a process for calculating the absolute steering angle θAm based on the above-described equation (4) is performed in step S325 as in step S113. Thus, since the absolute position of the steering wheel 21 is detected, a series of the absolute position detection process (part 1) is normally completed.
[0153]
Here, the basis of the characteristic diagram (broken line M) showing the change in the true value detection margin with respect to the numerical value after the decimal point of the calculated value r shown in FIG. 17 will be described with reference to FIG. FIG. 18A shows a characteristic indicating a change in deviation of the calculated value r from the calculated motor electrical angle θMe (−2) with respect to the numerical value after the decimal point.
[0154]
As described with reference to FIG. 12A, when the numerical value after the decimal point of the calculated value r is 0.33, the four types of rotation amounts of the steering wheel 21 (A = −2, −1, 0 and 1), αd and δd having the same value appear in two places (A = −2 and A = 1). It cannot be determined whether it is obtained. That is, in FIG. 18A, not only when the numerical value after the decimal point of the calculated value r is 0 (zero), but also when the numerical value after the decimal point of the calculated value r is 0.33, A = -2 and A = 1 take the same value, so they cannot be distinguished.
[0155]
On the other hand, as in the case of the electric power steering apparatus 20 described with reference to FIG. 10, the calculation is performed by changing the numerical value after the decimal point of the calculation value r from 0 to 1 on the basis of the broken line of A = −2. When the deviation of the motor electrical angle θMe (A) is obtained for A = −1 and A = 0, it can be seen that there is a relationship as shown in FIG. By expressing the deviation by turning it back at 180 degrees, a mountain-shaped characteristic diagram as shown in FIG. 18B can be obtained. In FIG. 18B, the broken lines with A = -2 and A = 1 are omitted.
[0156]
That is, the solid line of A = −1 increased linearly from 0 degrees to 360 degrees in FIG. 18A, but turns back at 180 degrees in FIG. When the numerical value reaches 0.5, it turns back and decreases linearly with a negative slope, forming an isosceles triangular fold line (solid line).
[0157]
In addition, the dotted line of A = 0 increased linearly from 0 degree to 720 degrees in FIG. 18A, but in FIG. 18B, it is folded back at 180 degrees and 0 degrees. When the numerical value after the decimal point of r reaches 0.25, 0.5, and 0.75, the return increase / decrease is repeated twice to form two isosceles triangles (dotted lines).
[0158]
Each broken line represented in this way is true as the deviation from the broken line of A = -2 approaches 0 (zero) when the arithmetic motor electrical angle θMe (-2) in the case of A = -2 is a true value. This indicates that confusion is likely to occur between the calculation motor electrical angle θMe (-2), which is the value, and other calculation motor electrical angles θMe (-1), θMe (0), θMe (1), which are false values. Therefore, when a false value closest to the true value θMe (−2) is selected from each broken line, a broken line M (thick one-dot chain line in FIG. 18B) can be generated. That is, the broken line M is a characteristic (broken line M) indicating the change in the true value detection margin with respect to the numerical value after the decimal point of the calculated value r as shown in FIG.
[0159]
According to the electric power steering apparatus 120 in which the absolute steering angle θAm is detected by such absolute position detection processing (part 1), the absolute steering angle of the steering wheel 21 obtained immediately before the ignition switch IGSW is turned off. The non-volatile memory 161 stores θAm as the steering angle θAm-off when the IG is off. Then, after the ignition switch IGSW is turned on, this time based on the previous steering angle θAm-off at IG off stored in the nonvolatile memory 161 and the rotation range of the steering wheel 21 less than 360 degrees regulated by the lock mechanism 130 The absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is calculated in steps S301, S303, and S317 of the absolute position detection process (part 1). , S319 and S321 are specified from a plurality of one rotation ranges A = -2 or A = 1.
[0160]
As a result, the absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is obtained from a plurality of one rotation ranges A = 1 or A = −2. Even if there is a specific case, based on the previous steering angle θAm-off at the time of IG off and the rotation range of less than 360 degrees at which the steering wheel 21 can rotate at the time of ignition off, the plurality of one rotation ranges A = 1 or The absolute steering angle θAm of the steering wheel 21 obtained this time can be specified from A = −2. Therefore, even in such a case, the absolute steering angle θAm of the steering wheel 21 can be accurately detected. Therefore, the motor 40 that assists the steering based on the absolute steering angle θAm of the steering wheel 21 thus detected can be provided. Can be controlled.
[0161]
Subsequently, the flow of the absolute position detection process (part 2) applicable when the numerical value after the decimal point of the calculated value r is set to 0.50 (N2 type) will be described with reference to FIGS. The absolute position detection process (part 2) shown in FIG. 19 is also executed by the CPU 61 of the ECU 160, and steps S401, S403, S405, S407, S409, and S411 constituting the absolute position detection process (part 2). In step S413, the same processing as in steps S301, S303, S101, S103, S105, S107, and S109 of the absolute position detection processing shown in FIG. 7 or FIG. 16 is performed. Therefore, description of the processing content by these steps is omitted.
[0162]
As shown in FIG. 19, in the absolute position detection process (part 2), when each process from step S401 to step S413 is sequentially executed, the calculation motor electrical angle θMe (A) selected in step S413 by the next step S415 is performed. ) Is determined to correspond to one of the four types of rotation amounts (A = −2, −1, 0, 1) of the steering wheel 21.
[0163]
That is, as shown in FIG. 12B, in the case where detection is possible in the N2-type rotation range (A = −2, −1 or A = 0, 1), one rotation range of the steering wheel 21 is “A = 0 or A = -2 "or" A = 1 or A = -1 ", that is, in any case of one rotation range, the absolute steering angle θAm of the steering wheel 21 (in FIG. 12B) Αe and γe or βe and δe) cannot be discriminated. Therefore, in this step S415, first, based on the value of one rotation range A, in which case the absolute steering angle θAm of the steering wheel 21 (A = 0 or A = −2, A = 1 or A = −1) A determination process is performed to determine whether or not If the value of one rotation range A is A = 0 or A = −2 (A = 0 or −2 in S415), the previous IG OFF steering angle θAm− read from the nonvolatile memory 161 is read. A process for determining whether or not off is less than −180 degrees is performed.
[0164]
That is, as shown in FIG. 12 (B), when the steering angle θAm-off at IG off is less than −180 degrees, −360 degrees (neutral position N) that is the leftmost rotation side when the ignition switch IGSW is off. Even if it is assumed that the steering wheel 21 is located 360 degrees to the left), the rotation range θN2LK of the steering wheel 21 is “−360 degrees <θN2LK ≦≦” by the lock mechanism 130 that is restricted to less than half rotation (180 degrees). -180 degrees ". Therefore, the steering wheel 21 is not positioned in the rotation range (A = 0) exceeding 180 degrees further from −180 degrees to the right rotation side. Therefore, when the steering angle θAm-off during IG off is less than −180 degrees, it can be determined that the current one rotation range A of the steering wheel 21 is A = −2.
[0165]
On the other hand, when the steering angle θAm-off at the time of IG off is not less than −180 degrees, the steering wheel 21 is positioned at the neutral position N (absolute steering angle θAm = 0 degrees) that is the rightmost rotation side when the ignition switch IGSW is off. Even if it is assumed that the rotation range θN2LK of the steering wheel 21 is restricted to “−180 degrees ≦ θN2LK <0 degree” by the lock mechanism 130, the steering wheel 21 is further moved from −180 degrees to the left rotation side. It is not located in the rotation range (A = -2) exceeding 180 degrees. Therefore, when the steering angle θAm-off at the time of IG off is not less than −180 degrees, it can be determined that the current one rotation range A of the steering wheel 21 is A = 0.
[0166]
Therefore, when it is determined in step S421 that the IG off-time steering angle θAm-off is less than −180 degrees (Yes in S421), one rotation range A of the selected arithmetic motor electrical angle θMe (A). = −2 is selected in step S423, and if it is not determined in step S421 that the IG off-time steering angle θAm-off is less than −180 degrees (No in S421), the selected calculation is performed. A process of selecting one rotation range A = 0 of the motor electrical angle θMe (A) in step S425 is performed.
[0167]
As shown in FIG. 12 (C), when the steering angle θAm-off at the time of IG off is over 180 degrees, 360 degrees (right from the neutral position N to the right side) when the ignition switch IGSW is off. Even if it is assumed that the steering wheel 21 is positioned at 360 degrees), the rotation range θN2LK of the steering wheel 21 is restricted to “180 degrees <θN2LK ≦ 360 degrees” by the lock mechanism 130. Therefore, the steering wheel 21 is not located in a rotation range (A = −1) exceeding 360 degrees from 360 degrees to the left rotation side. Therefore, when the IG off-time steering angle θAm-off exceeds 180 degrees, it can be determined that the current one rotation range A of the steering wheel 21 is A = 1.
[0168]
On the other hand, when the steering angle θAm-off at the time of IG off does not exceed 180 degrees, the steering wheel 21 is positioned at the neutral position N (absolute steering angle θAm = 0 degree) which is the leftmost rotation side when the ignition switch IGSW is off. Even if it is assumed that the rotation range θN2LK of the steering wheel 21 is restricted to “0 degrees ≦ θN2LK <180 degrees” by the lock mechanism 130, the steering wheel 21 is further rotated 180 degrees from 180 degrees to the right rotation side. It is not located in the rotation range exceeding (A = 1). Therefore, when the steering angle θAm-off at the time of IG off does not exceed 180 degrees, it can be determined that the current one rotation range A of the steering wheel 21 is A = −1.
[0169]
Therefore, if it is determined in step S431 that the IG off-time steering angle θAm-off exceeds 180 degrees (Yes in S431), one rotation range A = of the selected arithmetic motor electrical angle θMe (A). 1 is selected in step S433, and if it is not determined in step S431 that the IG off-time steering angle θAm-off exceeds 180 degrees (No in S431), the selected calculation motor electrical angle Of θMe (A), one rotation range A = −1 is selected in step S435.
[0170]
When the arithmetic motor electrical angle θMe (A) is selected in steps S423, S425, S433, and S435 in this way, the subsequent arithmetic operation electrical angle θe is selected in step S441 in the same manner as in step S111 shown in FIG. A process for determining whether or not (A) is really proper is performed, and a process for calculating the absolute steering angle θAm based on the above equation (4) is performed in step S443 similarly to step S113. As a result, the absolute position of the steering wheel 21 has been detected, and the series of the absolute position detection processing (part 2) is normally terminated.
[0171]
Here, the basis of the characteristic diagram (broken line P) showing the change of the true value detection margin with respect to the numerical value after the decimal point of the calculated value r shown in FIG. 20 will be described with reference to FIG. FIG. 21 (A) shows a characteristic indicating a change in deviation of the calculated value r from the calculated motor electrical angle θMe (−2) with respect to the numerical value after the decimal point.
[0172]
As described with reference to FIG. 12B, when the numerical value after the decimal point of the calculated value r is 0.50, the four types of rotation amounts of the steering wheel 21 (A = −2, −1, “Αe and γe” and “βe and δe” having the same value among 0, 1) appear in two sets of two locations (A = −2 and A = 0, A = −1 and A = 1) . Therefore, even in such a case, if any of them is a true value, it cannot be determined which one can be selected to obtain a true value. That is, in FIG. 21A, not only when the numerical value after the decimal point of the calculated value r is 0 (zero), but also when the numerical value after the decimal point of the calculated value r is 0.50, A = -2 and A = 0, or A = -1 and A = 1 have the same value, and thus cannot be distinguished.
[0173]
On the other hand, as in the case of the electric power steering apparatus 20 described with reference to FIG. 10, the calculation is performed by changing the numerical value after the decimal point of the calculation value r from 0 to 1 on the basis of the broken line of A = −2. When the deviation of the motor electrical angle θMe (A) is obtained for A = −1 and A = 1, it can be seen that there is a relationship as shown in FIG. By expressing the deviation by turning back 180 degrees, it is possible to obtain a mountain-shaped characteristic diagram as shown in FIG. In FIG. 21B, the broken lines with A = -2 and A = 0 are omitted.
[0174]
That is, the solid line of A = -1, 1 increased linearly from 0 degrees to 360 degrees in FIG. 18 (A), but in FIG. 18 (B), it turns back at 180 degrees. When the numerical value after the decimal point reaches 0.5, it turns back and decreases linearly with a negative slope, forming an isosceles triangular broken line (solid line).
[0175]
Each broken line expressed in this way has a deviation from the broken line of A = -2 approaches 0 (zero) when the arithmetic motor electrical angle θMe (-2) in the case of A = -1, 1 is a true value. This indicates that confusion is likely to occur between the arithmetic motor electrical angle θMe (-2), which is a true value, and the arithmetic motor electrical angles θMe (0), θMe (1), which are other false values. When a false value closest to the value θMe (−2) is selected from each broken line, a broken line P (thick one-dot chain line in FIG. 21B) can be generated. That is, this broken line P is a characteristic (broken line P) indicating the change in the true value detection margin with respect to the numerical value below the decimal point of the calculated value r as shown in FIG.
[0176]
According to the electric power steering apparatus 120 in which the absolute steering angle θAm is detected by such absolute position detection processing (part 2), the absolute steering angle of the steering wheel 21 obtained immediately before the ignition switch IGSW is turned off. The non-volatile memory 161 stores θAm as the steering angle θAm-off when the IG is off. Then, after the ignition switch IGSW is turned on, this time based on the previous IG-off steering angle θAm-off stored in the nonvolatile memory 161 and the rotation range of the steering wheel 21 less than 180 degrees regulated by the lock mechanism 130 The absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is calculated in steps S401, S403, and S421 of the absolute position detection process (part 2). , S423, S425, S431, S433, and S435, a plurality of one rotation ranges A = -2 or A = 0 or A = -1 or A = 1.
[0177]
Accordingly, the absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is set to a plurality of one rotation ranges A = −2 or A = 0 or Even if it may be specified from A = −1 or A = 1, based on the steering angle θAm-off at the time of the previous IG off and the rotation range of less than 180 degrees in which the steering wheel 21 can rotate at the time of ignition off, The absolute steering angle θAm of the steering wheel 21 obtained this time can be specified from a plurality of one rotation ranges A = −2 or A = 0 or A = −1 or A = 1. Therefore, even in such a case, the absolute steering angle θAm of the steering wheel 21 can be accurately detected. Therefore, the motor 40 that assists the steering based on the absolute steering angle θAm of the steering wheel 21 thus detected can be provided. Can be controlled.
[0178]
[Third Embodiment]
Then, 3rd Embodiment which concerns on the electric power steering device of this invention is described with reference to FIGS.
Hereinafter, in the electric power steering apparatus 120 according to the third embodiment to be described, an operation value r that is a product of the reduction gear ratio of the ball screw mechanism 50 and the counter electrode number of the motor resolver 44 is less than the decimal point. For example, the numerical value is set to take 0.33. In the third embodiment, when the counter electrode number of the motor resolver 44 is 7, for example, the calculated value r = 57.33 (= 8. 19 × 7). Thereby, the numerical value after the decimal point of the calculation value r is set to 0.33.
[0179]
In this way, by setting the numerical value after the decimal point of the calculated value r to 0.33, the vertex of the broken line K shown in FIG. 9 can be increased and the true value detection margin can be increased. And the lower limit value of the angle deviation of the arithmetic motor electrical angle θMe (A) (broken line with a true value detection margin of 60.0 (deg)) can be raised. Thereby, for example, even when the error in the dimensional accuracy of the mechanical parts constituting the steering mechanism is extremely large, the absolute steering angle θAm of the steering wheel 21 can be accurately detected.
[0180]
However, when the numerical value after the decimal point of the calculated value r is set to 0.33 in this way, for example, the numerical value after the decimal point of the calculated value r is set to 0. 3 as shown in FIG. When 33 is set (for example, r = 3.33), αd and δd having the same value appear in two places (A = −2 and A = 1), and one of them is a true value. Sometimes a new problem arises that it is not possible to determine which one can be selected to obtain a true value. That is, the detectable range of the rotation amount is limited to the rotation range A = −2, −1, 0 or A = −1, 0, 1 of the steering wheel 21 (hereinafter, the rotation range A = −2, -1, 0, 1 can be detected as "N4 type", and rotation range A = -2, -1, 0 or A = -1, 0, 1 can be detected as "N3 type". ").
[0181]
In FIG. 12A, with the neutral position of the steering wheel 21 as the center, the steering wheel 21 rotation range (0 degrees <θ ≦ 360 degrees) is A = 0, and the right rotation range (right side) ( 360 ° <θ ≦ 720 °) A = 1, left rotation range around the neutral position (0 °> θ ≧ −360 °) A = −1, and left rotation range on the left side (−360) Degree> θ ≧ −720 degrees) is A = −2.
[0182]
Therefore, the electric power steering apparatus 120 according to the third embodiment will be described later with reference to FIGS. 23 and 24 without changing the configuration from the electric power steering apparatus 20 according to the first embodiment. Even when the numerical value after the decimal point of the calculated value r is set to 0.33 by the absolute position detection processing (that is, the N3 type), the true value is specified from “αd and δd” having the same value, and the N4 type The absolute steering angle θAm of the steering wheel 21 can be accurately detected in the same steering angle range as the above. As will be described later, by adopting the configuration shown in FIG. 26 as necessary, the absolute position detection processing (part 3) shown in FIG. 27 can be used to obtain true values from “αd and δd” having the same value. The value can be specified more accurately.
[0183]
<Absolute position detection processing (part 1)>
As shown in FIG. 23, the absolute position detection process (part 1) according to the third embodiment includes steps S1201 to S1225. In steps S1201, S1203, S1205, S1207, S1209, S1221, and S1223, the first implementation is performed. The absolute position detection processing steps S10l, S033, S105, S107, S09, Sll11, and Sll13 shown in FIG. Therefore, description of the processing content by these steps is omitted. 23 is processed by the CPU 61 of the ECU 60 shown in FIG. 5 referred to in the first embodiment.
[0184]
The absolute position detection process (part 1) is a process that is started immediately after an ignition switch (hereinafter referred to as “IG switch”) is turned on. After the process of obtaining the electrical angles θT1, θT2, and θMe of each resolver (first resolver 35, second resolver 37, and motor resolver 44) is performed in step S1201, four arithmetic motors are performed in steps S1203, S1205, and S1207. The electrical angle θMe (A) is obtained, and the one closest to the actual motor electrical angle θMe is selected in step S1209.
[0185]
However, as described with reference to FIG. 12A, in the N3 type, αd and δd having the same value appear in two places (A = −2 and A = 1). In other words, in step S1209, two of A = -2 and A = 1 or any one of them may be selected as being closest to the actual motor electrical angle θMe, so A = -2 or A = 1. One of these needs to be identified. Therefore, when the selected arithmetic motor electrical angle θMe (A) is A = −2 or A = 1, the processes in steps S1213 to S1219 are performed as follows.
[0186]
First, in step S1211, one rotation range A of the arithmetic motor electrical angle θMe (A) selected in step S1209 corresponds to any of the four types of rotation amounts (A = −2, −1, 0, 1) of the steering wheel 21. When the selected one rotation range A is A = 1 or A = -2, the process proceeds to the subsequent step S1213. On the other hand, if one rotation range A of the arithmetic motor electrical angle θMe (A) is A = 0 or A = −1 in step S1211, βd (A = −1) as shown in FIG. , Δd (A = 0), and one rotation range can be specified, respectively, and the process proceeds to step S1221 without performing the processes in steps S1213 to S1219.
[0187]
If it is determined in step S1211 that the selected one rotation range A is A = 1, A = -2, or A = 1 and A = -2, step S1213 indicates that A = 1, -2 Processing for calculating the absolute steering angles θAm (1) and θAm (−2) is performed, and one of the absolute steering angles θAm (1) and θAm (−2) calculated thereby is within the rotatable range ( The process of determining whether or not it is outside the physical steering angle range) is subsequently performed in step S1215. Note that the rotatable range of the steering wheel 21 is the two left rotation ranges (A = -2), one left rotation range (A = -1), and one right rotation range (A = 0) shown in FIG. ) And right two rotation range (A = 1).
[0188]
If it is determined in step S1215 that one of the absolute steering angles θAm (1) and θAm (−2) is outside the rotatable range of the steering wheel 21 (Yes in S1215), the process proceeds to step S1217. Processing for specifying one rotation range A of the other absolute steering angle θAm within the rotatable range of the steering wheel 21 is performed.
[0189]
That is, if the absolute steering angle θAm (−2) indicated by a circle X in FIG. 25A is present in the left outside range XL that is out of the left side of the rotatable range RtoR of the steering wheel 21 by the calculation in step S1215. When the determined absolute steering angle θAm exists (Yes in S1215), the steering wheel 21 can rotate with such an absolute steering angle θAm (−2) indicated by a circle in the left outside range XL. It can be determined that this is a false value indicating no position. Therefore, from the two A = −2 and A = 1, the absolute steering angle θAm (1) of the double circle existing within the rotatable range RtoR is specified as a true value in step S1215. For example, the rotatable range RtoR is set to ± 630 degrees around the neutral position N (black circle) of the steering wheel 21.
[0190]
On the other hand, when it is determined that both are within the rotatable range, such as absolute steering angles θAm (1) and θAm (−2) indicated by white circles shown in FIG. Since it is not determined that the wheel 21 is outside the rotatable range (No in S1215), the two cannot be distinguished. Therefore, after setting the determination flag to OFF in step S1219, the absolute position detection process (part 1) is terminated, and the absolute position detection process (part 2) described later is distinguished between them to set the absolute steering angle θAm. Entrust the requested process.
[0191]
When one rotation range A of the absolute steering angle θAm within the rotatable range is specified in step S1217, the absolute steering angle θAm is calculated in steps S1221 and S1223, and the determination flag is set to ON in step S1225. This determination flag is set to ON when one rotation range of the absolute steering angle θAm is specified, and is set to OFF when it is not specified. Therefore, if it is determined in step S1215 that both of the absolute steering angles θAm (1) and θAm (−2) are within the rotatable range, the determination flag is set to OFF in step S1219.
[0192]
In the description with reference to FIG. 25 (A), the case where the absolute steering angle θAm exists in the left outside range XL that deviates from the rotatable range RtoR to the left is illustrated, but the right that deviates from the rotatable range RtoR to the right Even when the absolute steering angle θAm (1) exists in the outer range XR, the absolute steering angle θAm (−2) is specified in step S1217, and the processing from step S1221 is performed as described above.
[0193]
Thus, according to the electric power steering apparatus 120 that executes the absolute position detection process (part 1) shown in FIG. 23, the two absolute rotational positions are obtained by steps S1213, S1215, and S1217 of the absolute position detection process (part 1). Of the absolute steering angles θAm (1) and θAm (−2) as candidates, one does not exist in any of the rotation ranges A = −2, −1, 0, 1 of the steering wheel 21, and the other When the rotation range A is in any one of -2, -1, 0, 1 range, the other is converted from the two absolute steering angles θAm (1), θAm (-2) to the absolute steering angle θAm. Is specified as one rotation range A.
[0194]
Thus, the absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is two absolute steering angles θAm (1), θAm (−2 ) Can be specified as the absolute steering angle θAm of the steering wheel 21. Therefore, in such a case, the absolute steering angle θAm of the steering wheel 21 can be accurately detected even when the vehicle in which the steering wheel 21 is difficult to rotate is parked. Therefore, even when the vehicle is parked or stopped, the motor 40 that assists steering can be controlled based on the absolute steering angle θAm of the steering wheel 21 detected in this way.
[0195]
<Absolute position detection process (2)>
Next, when it is determined that both are within the rotatable range (physical steering angle range), such as absolute steering angles θAm (1) and θAm (−2) indicated by white circles shown in FIG. In FIG. 24, an example of the absolute position detection process (part 2) in which both can be distinguished will be described with reference to FIG. This absolute position detection process (part 2) is also processed by the CPU 61 of the ECU 60 shown in FIG. 5, and is repeatedly executed as an interrupt process or the like at predetermined intervals after the absolute position detection process (part 1) described above. Is.
[0196]
As shown in FIG. 24, first, in step S1301, processing for obtaining the electrical angles θT1, θT2, and θMe of each resolver (first resolver 35, second resolver 37, and motor resolver 44) is performed, and then in step S1303. A process of calculating the mechanical angle θTm of the steering wheel 21 and storing the calculated mechanical angle θTm in the memory is performed. Note that this memory is a semiconductor memory device such as a DRAM that is built in the CPU 61 or is mounted on the ECU 60 and connected to the CPU 61 by a bus, and that provides a work area or the like used when the CPU 61 performs arithmetic processing. It is.
[0197]
Next, in step S1305, it is determined whether or not the determination flag is set to OFF, that is, whether or not one rotation range of the absolute steering angle θAm could not be specified by the absolute position detection process (part 1) described above. Processing is performed. Accordingly, when the determination flag is not set to OFF (No in S1305), since one rotation range of the absolute steering angle θAm has already been specified by the above-described absolute position detection process (No. 1), this absolute position The detection process (part 2) ends without further processing.
[0198]
On the other hand, if it is determined in step S1305 that the determination flag is set to OFF (Yes in S1305), the process proceeds to subsequent step S1307 to determine whether the steering wheel 21 has rotated beyond a predetermined angle. A process for determining is performed. That is, the mechanical angle θTm ′ of the steering wheel 21 stored in the memory in the previous step S1303 is read from the memory, and the angle difference ΔθTm between the read mechanical angle θTm ′ and the mechanical angle θTm calculated this time is calculated. . Then, based on the absolute value of this angle difference ΔθTm, the next step S1307 determines whether or not the steering wheel 21 has rotated beyond a predetermined angle.
[0199]
That is, whether or not the steering wheel 21 is rotating is determined based on whether or not the absolute value of the angle difference ΔθTm exceeds a predetermined angle in step S1307. If it is determined that the steering wheel 21 has rotated beyond a predetermined angle and the cutting direction of the steering wheel 21 is the left rotation direction (Yes in S1307), the absolute steering angle is determined in step S1309. A process of subtracting 1 from the value of one rotation range A of θAm (decrement) is performed.
[0200]
On the other hand, when it is determined in step S1307 that the steering wheel 21 has rotated beyond a predetermined angle and the cutting direction of the steering wheel 21 is the right rotation direction (Yes in S1307 (right turn)), In step S1311, processing for adding (incrementing) the value of one rotation range A of the absolute steering angle θAm by 1 is performed. The rotation direction of the steering wheel 21 is determined by a predetermined algorithm based on the sign of the angle difference ΔθTm.
[0201]
On the other hand, when the absolute value of the angle difference ΔθTm does not exceed the predetermined angle and it is not determined in step S1307 that the steering wheel 21 has rotated beyond the predetermined angle (No in S1307), the processing in steps S1309 and S1311 is performed. Without performing this, the process proceeds to step S1313.
[0202]
As described above, when it is determined in step S1307 that the steering wheel 21 is rotated beyond the predetermined angle, before rotating beyond the predetermined angle, for example, as shown in FIG. After the absolute steering angles θAm (1), θAm (−2) indicated by white circles existing within the rotatable range RtoR of the steering wheel 21 have exceeded the predetermined angle, FIG. 25 (C) As shown, the steering wheel 21 moves outside the rotatable range RtoR. As a result, it is possible to distinguish between the absolute steering angle θAm (−2) indicated by a circle × existing outside the rotatable range RtoR and the absolute steering angle θAm (1) indicated by a double circle existing within the rotatable range RtoR. Therefore, it is possible to perform the same processing as the absolute position detection processing (part 1) described above.
[0203]
This predetermined angle is, for example, as shown in FIG. 25B when the rotatable range RtoR of the steering wheel 21 is set to ± 630 degrees around the neutral position N (black circle) of the steering wheel 21. As shown, 90 (= 630−) is the angle difference from the boundary YL (−630 degrees) between the left outer range XL and the left two rotation range A = −2 to the center position (−540 degrees) of the left two rotation range. 540) degrees.
[0204]
In step S1313, based on one rotation position of the absolute steering angle θAm shifted in steps S1309 and S1311 or one rotation position of the absolute steering angle θAm without being shifted, the rotation position A = 1, −2. A process of calculating the absolute steering angle θAm is performed, and a process of determining whether one of the absolute steering angles θAm (1) and θAm (−2) calculated thereby is outside the physical steering angle range is performed. Subsequently to S1315.
[0205]
If it is determined in step S1315 that one of the absolute steering angles θAm (1) and θAm (−2) is outside the rotatable range (physical steering angle range) of the steering wheel 21 (S1315). In step S1317, processing for specifying one rotation range A of the other absolute steering angle θAm within the rotatable range (physical steering angle range) of the steering wheel 21 is performed.
[0206]
In other words, when the steering wheel 21 rotates beyond a predetermined angle, the absolute steering angle θAm calculated in step S1315 as indicated by the rounded absolute steering angle θAm (−2) shown in FIG. Indicates the left outer side range XL outside the rotatable range RtoR of the steering wheel 21. Therefore, the absolute steering angle θAm (−2) of the x circle indicates a false value indicating a position where the steering wheel 21 cannot rotate. Can be determined. For this reason, the absolute steering angle θAm (1) shown in FIG. 25 (C), for example, that is present in the physical steering angle range that is not a false value is set as a true value, and absolute steering is performed in step S1317. One rotation range A of the angle θAm is specified.
[0207]
When one rotation range A of the absolute steering angle θAm within the rotatable range (physical steering angle range) is specified in step S1317, the determination flag is set to ON in step S1319. This determination flag is set to ON when one rotation range of the absolute steering angle θAm is specified, and is set to OFF when it is not specified. Therefore, the process is terminated halfway through step S1305 or step S1315. In this case, the determination flag setting process in step S1319 is not performed.
[0208]
In the description with reference to FIG. 25 (B) and FIG. 25 (C), the case where the absolute steering angle θAm exists in the left outer side range XL that deviates to the left of the rotatable range RtoR is exemplified. Even when the absolute steering angle θAm (1) exists in the right outer side range XR deviating to the right side, the absolute steering angle θAm (−2) is specified in step S1317, and the subsequent processing is performed as described above.
[0209]
As described above, according to the electric power steering apparatus 120 that executes the absolute position detection process (part 2) shown in FIG. 24, the steps S1307, S1309, S1311, S1313, S1315, and S1317 of the absolute position detection process (part 2) are performed. Both of the absolute steering angles θAm (1) and θAm (−2) as two absolute rotation position candidates exist in any one of the rotation ranges A = −2, −1, 0 and 1 of the steering wheel 21. When the steering wheel 21 rotates beyond a predetermined angle, one of the two absolute steering angles θAm (1) and θAm (−2) has a rotation range A = −2, −1, 0, 1 Of the two absolute steering angles θAm (1) and θAm (−2) is replaced with the other absolute steering angles θAm (1) and θAm (−2). From the absolute steering angle θAm Identifying as a rotational range A.
[0210]
Thus, the absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is two absolute steering angles θAm (1), θAm (−2 ), The steering wheel 21 can be specified as the absolute steering angle θAm of the steering wheel 21 by rotating the steering wheel 21 beyond a predetermined angle. Therefore, even in such a case, if the steering wheel 21 rotates beyond a predetermined angle, the absolute rotational position of the steering wheel 21 can be accurately detected regardless of whether the vehicle is parked or traveling. Can do. Therefore, regardless of the vehicle state, the motor 40 that assists steering can be controlled based on the absolute rotation position of the steering wheel 21 thus detected.
[0211]
<Absolute position detection processing (part 3)>
Subsequently, an absolute position detection process (part 3) in which the true value can be specified more accurately than the absolute position detection process described above will be described with reference to FIGS. As shown in FIG. 26, the absolute position detection process (part 3) includes wheel speed sensors 162 and 164 that can detect the rotational speeds of the left and right wheels of the vehicle (hereinafter referred to as “wheel speed”), respectively, as input ports P 1 Are processed by the CPU 61 connected to P2, and are repeatedly executed, for example, as interrupt processing at predetermined intervals after the above-described absolute position detection processing (part 1).
[0212]
The wheel speed sensors 162 and 164 are configured to output a pulse signal whose frequency increases and decreases in response to the increase and decrease of the wheel speed. The wheel speed sensor 162 is a wheel of the right front wheel of the vehicle. The speed WH-R is detected, and the wheel speed sensor 164 is provided on each corresponding wheel so as to detect the wheel speed WH-L of the left front wheel of the vehicle. Further, the wheel speed sensor may be configured to detect the wheel speeds of all four wheels of the vehicle. Thereby, if the difference between the left and right wheel speeds is detected by the combination of the left and right wheel speed sensors positioned diagonally with respect to the vehicle body, it can be detected with high accuracy.
[0213]
As shown in FIG. 27, in the absolute position detection process (part 3), first, a process of acquiring the wheel speeds WH-R and WH-L from the left and right wheel speed sensors 162 and 164 is performed in step S1401. That is, a process for directly or indirectly acquiring information about the wheel speeds WH-R and WH-L output from the left and right wheel speed sensors 162 and 164 is performed. Specifically, since a pulse signal whose frequency changes according to the wheel speed is input from the wheel speed sensors 162 and 164, the CPU 61 receives the pulse frequency (1) by counting the number of the pulses. The wheel speeds WH-R and WH-L are obtained by calculating (/ the number of counts per unit time). Note that the wheel speeds WH-R and WH-L calculated by another ECU may be acquired via a shared memory or a network with the other ECU.
[0214]
In the next step S1403, it is determined whether or not the decision flag is set to OFF, that is, whether or not one rotation range of the absolute steering angle θAm could not be specified by the above-described absolute position detection process (part 1). Processing is performed. Accordingly, when the determination flag is not set to OFF (No in S1403), one absolute rotation range of the absolute steering angle θAm has already been specified by the above-described absolute position detection processing (part 1). The detection process (part 3) ends without further processing.
[0215]
On the other hand, if it is determined in step S1403 that the determination flag is set to OFF (Yes in S1403), the process proceeds to the subsequent step S1405, and the left and right wheel speeds WH-R and WH-L are determined. A process for determining whether or not the difference ΔWH exceeds a predetermined range is performed. For example, if the difference between the left and right wheels ΔWH between the wheel speed WH-R calculated in step S1401 and the wheel speed WH-L is more than two pulses in terms of the number of pulses, the difference between the left and right wheels ΔWH Is determined to exceed the predetermined range. Then, the rotation direction of the steering wheel 21 is determined by a predetermined algorithm based on the sign of the left / right wheel difference ΔWH.
[0216]
As a result, when it is determined in step S1405 that the left / right wheel difference ΔWH between the left and right wheel speeds WH-R and WH-L exceeds a predetermined range, and the turning direction of the steering wheel 21 is the left rotation direction (S1405). Yes (left turn)), both are within the rotatable range (physical steering angle range), such as the absolute steering angles θAm (1) and θAm (-2) in white circles shown in FIG. Even if it is determined that the steering wheel 21 is cut to the left (the direction in which the absolute steering angle θAm becomes a negative value with respect to the neutral position N), it is shown in FIG. Of the absolute steering angles θAm (1) and θAm (−2) indicated by white circles, the absolute steering angle θAm (−2) can be selected as a true value. Therefore, in this case, the process proceeds to step S1407, and one rotation range of the absolute steering angle θAm is specified as A = −2.
[0217]
Similarly, if it is determined in step S1405 that the left / right wheel difference WH-R between the left and right wheel speeds WH-R and WH-L exceeds a predetermined range, and the turning direction of the steering wheel 21 is the right rotation direction ( In S1405 (Yes (right turn)), the steering wheel 21 is turned rightward (the direction in which the absolute steering angle θAm becomes a positive value with respect to the neutral position N). Of the absolute steering angles θAm (1) and θAm (−2) indicated by white circles, the absolute steering angle θAm (1) can be selected as a true value. Therefore, in this case, the process proceeds to step S1409, and one rotation range of the absolute steering angle θAm is specified as A = 1.
[0218]
On the other hand, if it is not determined in step S1405 that the left and right wheel speeds WH-R and WH-L have a left-right wheel difference ΔWH exceeding the predetermined range (No in S1405), the steering direction by the steering wheel 21 is determined this time. Since it cannot be determined, the absolute position detection process (part 3) is terminated, and the system waits for the next process.
[0219]
In step S1411, similarly to step S113 shown in FIG. 7 described above, processing for calculating the absolute steering angle θAm is performed, and further, processing for setting the determination flag to ON is performed in step S1413. This determination flag is the same as that described in the absolute position detection process (part 1) and the absolute position detection process (part 2).
[0220]
As described above, according to the electric power steering apparatus 120 that executes the absolute position detection processing (part 3) shown in FIGS. 26 and 27, the left and right wheel speeds WH-R and WH-L are obtained by the wheel speed sensors 162 and 164, respectively. Each is detected, and the steering direction by the steering wheel 21 is determined based on the left / right wheel difference ΔWH between the left and right wheel speeds WH-R and WH-L in step S1405 by the absolute position detection process (part 3). Then, based on the determination result in step S1405, the absolute steering angle θAm (1), θAm (−2) as two absolute rotation position candidates is used as one rotation range A of the absolute steering angle θAm, and the same processing is performed in steps S1407 and S1409. Identify.
[0221]
Thus, the absolute steering angle θAm of the steering wheel 21 obtained from the electrical angle θT1 of the first resolver, the electrical angle θT2 of the second resolver, and the actual motor electrical angle θMe is two absolute steering angles θAm (1), θAm (−2 ), The left and right wheels of the vehicle rotate, and either one can be specified as the absolute steering angle θAm of the steering wheel 21. Therefore, even in such a case, the absolute steering angle θAm of the steering wheel 21 can be accurately detected if the left and right wheels rotate. Therefore, if the vehicle is traveling, the motor 40 that assists steering can be controlled based on the absolute steering angle θAm of the steering wheel 21 detected in this way.
[0222]
Hereinafter, the description in parentheses in the column of “Explanation of Symbols” represents the words and phrases described in the claims, and indicates that the names listed immediately before or immediately before the parentheses correspond to the words in parentheses. .
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an electric power steering apparatus according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of an ellipse taken along one-dot chain line II shown in FIG.
FIG. 3 is an enlarged view of an ellipse taken along one-dot chain line III shown in FIG.
FIG. 4 (A) is an explanatory view showing a configuration of a resolver used in the electric power steering apparatus of the first embodiment, and FIG. 4 (B) is a circuit diagram of the resolver.
FIG. 5 is a block diagram showing a connection configuration between an ECU that controls the electric power steering apparatus of the first embodiment and a resolver.
FIG. 6 is a characteristic diagram showing resolver output signals from the first resolver and the second resolver and the mechanical angle of the steering wheel with respect to the rotation angle of the steering wheel.
7 is a flowchart showing the flow of absolute position detection processing executed by the CPU shown in FIG.
FIG. 8 is a characteristic diagram showing changes in the steering wheel mechanical angle θTm and the motor electrical angle θMe with respect to the amount of rotation of the steering wheel. FIG. 8A shows the case where the calculated value r = 3.75; ) Shows the case where the calculation value r = 3.05, and FIG. 8C shows the case where the calculation value r = 4.00.
FIG. 9 is a characteristic diagram (broken line K) showing a change in the true value detection margin with respect to a numerical value after the decimal point of the calculated value r.
FIG. 10 (A) shows the angle deviation between the arithmetic motor electrical angle θMe (−2) and θMe (−1), θMe (0), θMe (1) with respect to the numerical value after the decimal point of the arithmetic value r. FIG. 10B is a characteristic diagram showing the change, and FIG. 10B is a characteristic diagram (folded line K) in which FIG. 10A is folded back at 180 degrees.
FIG. 11 (A) shows the angle deviation between the arithmetic motor electrical angle θMe (−1) and θMe (−2), θMe (0), θMe (1) with respect to the numerical value after the decimal point of the arithmetic value r. FIG. 11 (B) is a characteristic diagram (folded line L) showing FIG. 11 (A) folded at 180 degrees.
FIG. 12 is a characteristic diagram showing changes in the mechanical angle θTm of the steering wheel and the motor electrical angle θMe with respect to the amount of rotation of the steering wheel. FIG. 12A is a calculation value r = 3.33 in the case of the N3 type. FIG. 12B shows the case where the operation value r = 3.5 in the case of the N2 type.
FIG. 13 is a configuration diagram showing a configuration of an electric power steering apparatus according to a second embodiment of the present invention.
FIG. 14 is a block diagram showing a connection configuration between an ECU that controls the electric power steering apparatus of the second embodiment and a resolver and the like.
15 is a flowchart showing a flow of an IG off-time steering angle storage process executed by the CPU shown in FIG. 14;
FIG. 16 is a flowchart showing the flow of absolute position detection processing (part 1) executed by the CPU shown in FIG. 14, and is for the N3 type.
FIG. 17 is a characteristic diagram (broken line M) showing a change in the true value detection margin with respect to a numerical value after the decimal point of the calculated value r.
FIG. 18 (A) is a characteristic diagram showing a change in angular deviation between the arithmetic motor electrical angle θMe (−2) and θMe (−1), θMe (0) with respect to the numerical value after the decimal point of the arithmetic value r. FIG. 18B is a characteristic diagram (folded line M) obtained by folding back FIG. 18A at 180 degrees.
FIG. 19 is a flowchart showing the flow of absolute position detection processing (part 2) executed by the CPU shown in FIG. 14, and is for the N2 type.
FIG. 20 is a characteristic diagram (broken line P) showing a change in the true value detection margin with respect to a numerical value after the decimal point of the calculated value r.
FIG. 21A is a characteristic diagram showing a change in angular deviation between the arithmetic motor electrical angle θMe (−2) and θMe (−1), θMe (1) with respect to the numerical value after the decimal point of the arithmetic value r. FIG. 21B is a characteristic diagram (folded line P) obtained by folding FIG. 21A at 180 degrees.
FIG. 22 is an explanatory diagram showing the positional relationship of one rotation range indistinguishable in a rotation range (A = −2, −1, 0, 1) in which the steering wheel rotates twice left and right around the neutral position. 22A is for the N3 type, and FIGS. 22B and 22C are for the N2 type.
FIG. 23 is a flowchart showing a flow of absolute position detection processing (part 1) according to the third embodiment of the present invention;
FIG. 24 is a flowchart showing the flow of absolute position detection processing (part 2) according to the third embodiment.
FIG. 25 (A) shows the case where one of the absolute steering angles θAm (1) and θAm (−2) is outside the rotatable range RtoR of the steering wheel immediately after the IG switch is turned on. When the absolute steering angle θAm (1) and θAm (−2) are both within the rotatable range RtoR immediately after the IG switch is turned on, FIG. 25 (C) shows that the steering wheel is turned on after the IG switch is turned on. It is explanatory drawing which respectively shows when it rotates exceeding a predetermined angle range and one of absolute steering angles (theta) Am (1) and (theta) Am (-2) moves out of the said rotatable range RtoR.
FIG. 26 is a block diagram showing a connection configuration between an ECU that controls the electric power steering apparatus of the third embodiment and a resolver and the like.
FIG. 27 is a flowchart showing a flow of absolute position detection processing (part 3) executed by the CPU shown in FIG. 26;
[Explanation of symbols]
20, 120 Electric power steering device
21 Steering wheel
22 Steering shaft
23 Pinion shaft
23c pinion gear
24 rack shaft
24a Rack groove
30 Torque sensor
35 First resolver
37 Second resolver
40 motor
44 Motor resolver (3rd resolver)
50 Ball screw mechanism (reduction gear)
130 Lock mechanism (rotation range regulating means)
60, 160 ECU
162, 164 Wheel speed sensor (wheel speed detection means)
61 CPU (storage means, steering direction determining means, absolute rotational position specifying means)
161 Nonvolatile memory (storage means)
IGSW ignition switch
θT1 First resolver electrical angle (first steering angle)
θT2 Second resolver electrical angle (second steering angle)
θMe Actual motor electrical angle (Motor electrical angle)
θTm Steering wheel mechanical angle
θMe (A) Calculation motor electrical angle
θAm Absolute steering angle (Absolute rotational position)
θAm-off IG off steering angle (IG off absolute rotation position)
r Calculated value
K, L, M, P
S203 (storage means)
S301, S303, S317, S319, S321, S401, S403, S421, S423, S425, S431, S433, S435 (absolute rotational position specifying means)
S1405 (steering direction determination means)
S1407, S1409 (absolute rotational position specifying means)

Claims (9)

A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a counter electrode number different from that of the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; An electric power steering apparatus for controlling the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle,
At least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. and,
The numerical value after the decimal point of the calculated value is the decimal point of the calculated value when the angular deviation of the motor electrical angle, which is different for each unit of at least one rotation range of the steering wheel, is 67% or more and 100% or less of the maximum value of the angular deviation. An electric power steering apparatus characterized by being in the following numerical range . A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; An electric power steering apparatus configured to be able to control the motor based on the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle. A manufacturing method comprising:
The calculation value by the product of the reduction gear ratio of the reduction gear and the counter electrode number of the third resolver is “0.17 or more and 0.28 or less”, “0.39 or more and 0 or less” as a numerical value after the decimal point of the calculation value. .42 or less "," 0.58 or more and 0.61 or less ", and" 0.72 or more and 0.83 or less ", the step of setting at least one of the reduction gear ratio or the counter electrode number to be a non-integer The manufacturing method of the electric power steering device characterized by including. A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; An electric power steering apparatus configured to be able to control the motor based on the absolute rotation position of the steering wheel obtained from the first steering angle, the second steering angle, and the motor electrical angle. Manufacturing equipment,
The calculation value by the product of the reduction gear ratio of the reduction gear and the counter electrode number of the third resolver is “0.17 or more and 0.28 or less”, “0.39 or more and 0 or less” as a numerical value after the decimal point of the calculation value. .42 or less "," 0.58 or more and 0.61 or less "and" 0.72 or more and 0.83 or less ", means for setting at least one of the reduction gear ratio or the counter electrode number to be a non-integer An apparatus for manufacturing an electric power steering apparatus. A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle,
Calculated value by the product of the counter number of the third resolver and the reduction gear ratio of the reduction gear, so that the non-integer having a value of below decimal point, at least one set of reduction gear ratio or logarithmic poles And
The first steering angle, the absolute rotational position of the steering wheel obtained from the second steering angle and the motor electric angle, with there Ru electric power steering apparatus when it is identified from the plurality of absolute rotational position candidates There,
A rotation range restricting means for restricting the rotation of the steering wheel within a predetermined rotation range in an off state of the ignition switch;
Storage means for storing the absolute rotational position of the steering wheel obtained from the first steering angle, the second steering angle and the motor electrical angle immediately before the ignition switch is turned off as an IG off absolute rotational position; ,
After the ignition switch is turned on, based on the previous absolute IG-off absolute rotation position stored in the storage means and the predetermined rotation range of the steering wheel restricted by the rotation range restriction means, the first steering is performed this time. An absolute rotational position specifying means for specifying an absolute rotational position of the steering wheel obtained from an angle, the second steering angle and the motor electrical angle from the plurality of absolute rotational position candidates;
An electric power steering apparatus comprising: The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. It can be rotated in one rotation range and two left rotation ranges that rotate further leftward beyond the left one rotation range,
The predetermined range regulated by the rotation range regulating means is less than 360 degrees,
The electric power steering apparatus according to claim 4, wherein the plurality of absolute rotation position candidates are present in the right two rotation ranges and the left two rotation ranges,
The calculation value is set to be a non-integer having “0.22 or more and 0.39 or less” and “0.61 or more and 0.78 or less” as a numerical value after the decimal point of the calculation value. Electric power steering device. The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. It can be rotated in one rotation range and two left rotation ranges that rotate further leftward beyond the left one rotation range,
The predetermined range regulated by the rotation range regulating means is less than 180 degrees,
The electric power steering apparatus according to claim 6, wherein the plurality of absolute rotation position candidates exist in “the right rotation range and the left rotation range” and “the right rotation range and the left rotation range”. Because
5. The electric power steering according to claim 4 , wherein the calculated value is set to be a non-integer having a value of 0.33 or more and 0.67 or less as a numerical value after the decimal point of the calculated value. Taking device. A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle,
At least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. ,
The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. It can be rotated in one rotation range and two left rotation ranges that rotate further leftward beyond the left one rotation range,
The first steering angle, the absolute rotational position of the steering wheel obtained from the second steering angle and the motor electric angle at Oh Ru electric power steering apparatus in the case specified from two absolute rotational position candidates There,
Of the two absolute rotation position candidates, one does not exist in any of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range, and the other If it exists in any one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range, the other of the two absolute rotation position candidates is replaced with the absolute rotation position. An electric power steering apparatus characterized by specifying as follows. A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle,
At least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. ,
The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. It can be rotated in one rotation range and two left rotation ranges that rotate further leftward beyond the left one rotation range,
The first steering angle, the absolute rotational position of the steering wheel obtained from the second steering angle and the motor electric angle at Oh Ru electric power steering apparatus in the case specified from two absolute rotational position candidates There,
When any of the two absolute rotation position candidates is present in any one of the left two rotation range, the left one rotation range, the right one rotation range, and the right two rotation range, the steering wheel Is rotated beyond a predetermined angle, one of the two absolute rotation position candidates is one of the left 2 rotation range, the left 1 rotation range, the right 1 rotation range, and the right 2 rotation range. An electric power steering apparatus characterized by specifying the other of the two absolute rotation position candidates as the absolute rotation position when no longer exists in the range. A steering wheel, a first resolver that detects a first steering angle that is a rotation angle of a steering shaft that is coupled to the steering wheel, and a rotation angle of the steering shaft that has a different number of counter electrodes from the first resolver. A second resolver that detects a steering angle, a motor that assists steering by a steering mechanism coupled to the steering shaft via a speed reducer, and a third resolver that detects a motor electrical angle that is a rotation angle of the motor; And controlling the motor based on the absolute rotation position of the steering wheel determined from the first steering angle, the second steering angle, and the motor electrical angle,
At least one of the reduction gear ratio or the number of counter electrodes is set so that a calculation value by a product of the reduction gear ratio of the reduction gear and the number of counter electrodes of the third resolver becomes a non-integer having a numerical value after the decimal point. ,
The steering wheel has a right rotation range that rotates once to the right from the steering neutral position, a right rotation range that rotates further to the right beyond the right rotation range, and a left rotation that rotates one rotation to the left from the steering neutral position. It can be rotated in one rotation range and two left rotation ranges that rotate further leftward beyond the left one rotation range,
The first steering angle, the absolute rotational position of the steering wheel obtained from the second steering angle and the motor electric angle at Oh Ru electric power steering apparatus in the case specified from two absolute rotational position candidates There,
Wheel speed detection means capable of detecting the rotational speeds of the left and right wheels respectively;
Steering direction determining means for determining a steering direction by the steering wheel based on a difference in rotational speed between the left and right wheels detected by the wheel speed detecting means;
Absolute rotational position specifying means for specifying the absolute rotational position from the two absolute rotational position candidates based on the steering direction determined by the steering direction determining means;
An electric power steering apparatus comprising:

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