JP2013186059A - Stress measurement apparatus and stress measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stress measurement apparatus and a stress measurement method capable of measuring a stress of an intermediate shaft by an infrared camera.SOLUTION: A stress measurement apparatus 1 includes: a first rolling mechanism 30 for revolving a first column edge part 71A with respect to an intermediate shaft 72; a second rolling mechanism 40 for revolving a rack gear 74A with respect to a pinion gear 73C; a drive mechanism 20 for rotating the first rolling mechanism 30 and the second rolling mechanism 40 that are synchronized with each other; an infrared camera 61 for measuring a temperature of the intermediate shaft 72; and a stress arithmetic section 62 for calculating a stress occurring in the intermediate shaft 72 on the basis of output of the infrared camera 61.

Description

  The present invention relates to a stress measuring device and a stress measuring method for measuring stress generated in a vehicle steering device.

  The stress measurement device described in Patent Literature 1 includes an infrared camera and a stress calculation unit. The infrared camera outputs a signal corresponding to the temperature of the measurement object. The stress calculation unit calculates the stress of the measurement object based on the output of the infrared camera.

JP-A-9-159590

The stress measuring device cannot measure a rotating object. For this reason, the stress which arises in the intermediate shaft of a vehicle steering device cannot be measured.
In order to solve the above problems, an object of the present invention is to provide a stress measuring device and a stress measuring method capable of measuring the stress of an intermediate shaft with an infrared camera.

  (1) The first means is the stress measuring apparatus having the invention according to claim 1, that is, a support unit that supports the vehicle steering device, and a measuring unit that measures the stress of the vehicle steering device. The apparatus includes a column shaft having a first column end and a second column end, an intermediate shaft having a first intermediate end and a second intermediate end, a first pinion end and a second pinion end. A pinion shaft, a first universal joint that connects the second column end and the first intermediate end, a second universal joint that connects the second intermediate end and the first pinion end to each other, And a rack shaft having a rack gear meshed with a pinion gear of the pinion shaft, and the support portion has the intermediate column at the first column end. A first rotation mechanism that revolves relative to the shaft; a second rotation mechanism that revolves the rack gear relative to the pinion gear; and a drive mechanism that rotates the first rotation mechanism and the second rotation mechanism synchronously. The measuring unit is a stress measuring device having an infrared camera that measures the temperature of the intermediate shaft and a stress calculation unit that calculates the stress of the intermediate shaft based on an output of the infrared camera. The gist.

  The inventor of the present application has studied a stress measuring device and a stress measuring method for measuring the stress of an intermediate shaft of a vehicle steering device using an infrared camera. The inventor of the present application uses a vehicle steering device that is not mounted on a vehicle as an object to be measured, and a stress corresponding to a stress during operation of the vehicle steering device mounted on the vehicle ("Means for Solving the Problem" "Measurement equivalent stress" in the column ")" was set as a measurement condition to measure from the measurement object.

  When the vehicle steering device operates, the column shaft, the intermediate shaft, and the pinion shaft rotate. For this reason, as a method of measuring the motion equivalent stress using the infrared camera, a method of revolving the infrared camera with respect to the intermediate shaft according to the rotation of the intermediate shaft can be considered. However, in this measurement method, the wiring of the infrared camera and the stress calculation unit is complicated.

  Based on the above points, the inventor of the present application has studied a method of measuring the motion equivalent stress of the intermediate shaft with the infrared camera in a state where the position of the infrared camera is fixed with respect to the vehicle steering device as the measurement object.

  When the position of the infrared camera is fixed, in order to accurately measure the equivalent stress of the intermediate shaft, the relative relationship between the intermediate shaft and the infrared camera ("Means for solving problems" column) The “relative relationship at the time of measurement” is preferably substantially the same as the relative relationship at the time of measurement when both the intermediate shaft and the infrared camera rotate.

  Therefore, in the stress measuring apparatus and the stress measuring method of the present invention (referred to as “apparatus etc.” in the “Means for Solving the Problems” section), by not rotating both the intermediate shaft and the infrared camera. The relative relationship at the time of measurement is substantially the same as the relative relationship at the time of measurement when both the intermediate shaft and the infrared camera are rotating.

  On the other hand, since the device of the present application aims to measure the motion equivalent stress from the intermediate shaft of the vehicle steering device that is the object to be measured, the vehicle steering device is provided on condition that the intermediate shaft does not rotate. It is necessary to reproduce substantially the same state as when the intermediate shaft is rotating.

  And in this application apparatus etc., the above-mentioned state is formed by forming substantially the same relation as the relative relation between the intermediate shaft and the other parts constituting the vehicle steering apparatus when the intermediate shaft rotates. It is reproduced.

  In the stress measurement device of the present invention, the support portion plays a role for reproducing the above-described state. That is, the support portion revolves the first column end with respect to the intermediate shaft, revolves the rack gear with respect to the pinion gear, and rotates the first rotation mechanism and the second rotation mechanism in synchronization.

  In the vehicle steering apparatus, the relative relationship among the column shaft, the intermediate shaft, and the pinion shaft is maintained when each component is rotated by the support portion. Further, when the rack gear revolves with respect to the pinion gear, the rack shaft moves in the axial direction with respect to the pinion shaft.

  The state of the vehicle steering device at this time corresponds to a state in which the column shaft, the intermediate shaft, and the pinion shaft rotate together and, as a result, the rack shaft moves in the axial direction. That is, this corresponds to a state in which the rack shaft is moved by operating the steering wheel.

  As described above, the stress measuring device of the present invention reproduces substantially the same state as when the intermediate shaft rotates as the state of the vehicle steering device. For this reason, it becomes possible to measure the stress of the intermediate shaft in a state where the position of the infrared camera is fixed.

  (2) The second means is the invention according to claim 2, that is, the first support portion is capable of supporting the column shaft in a posture inclined with respect to the intermediate shaft. A first rotation support shaft having a rotation center axis coaxially with the intermediate shaft, and a first transmission portion for transmitting the rotation of the first rotation support shaft to the first support portion, The two-rotation mechanism includes a second support portion capable of supporting the pinion shaft in a posture inclined with respect to the intermediate shaft, and a second rotation support shaft having a rotation center axis coaxially with the intermediate shaft. And a second transmission part that transmits the rotation of the second rotation support shaft to the second support part.

  (3) The third means is the invention according to claim 3, that is, the vehicle steering apparatus has a rack housing that accommodates the rack shaft, and the first rotation mechanism includes the first rotation support shaft. A first bearing mechanism that supports the rotor in a rotatable state; a fixed shaft fixed to the first bearing mechanism; a fixed circular member fixed to the fixed shaft; and a transmission side fixed to the first support portion. The stress according to claim 2, further comprising: a circular member; and a winding member wound around the fixed-side circular member and the transmission-side circular member, wherein the first support portion supports the first column end. The gist is that it is a measuring device.

  In the vehicle steering device supported by the stress measuring device, the movement of the rack shaft is restricted by the rack housing when the rotation amount of the column shaft and the pinion shaft by the drive mechanism exceeds a certain amount. As the movement of the rack shaft is restricted, the revolution of the rack gear relative to the pinion gear is also restricted. At this time, assuming that torque transmission from the drive mechanism to the second rotation mechanism is continued, a force for revolving the rack gear relative to the pinion gear acts on the rack gear. However, since the revolution of the rack gear relative to the pinion gear is restricted as described above, the force acting on the rack gear acts as a force for rotating the pinion gear.

  For this reason, the force which rotates the pinion shaft, the intermediate shaft, and the column shaft integrally acts on these shafts. On the other hand, the 1st support part which supports the 1st column edge part is connected to the fixed shaft via the transmission side circular member, the winding member, and the fixed side circular member. For this reason, the first support portion cannot rotate.

  For this reason, the rotation of the column shaft is restricted by the first support portion. That is, rotation by the torque acting on the pinion gear is allowed at the second intermediate end of the intermediate shaft, and rotation by the same torque is restricted by the first support portion at the first intermediate end of the intermediate shaft. Is done.

  For this reason, a torsional stress is generated in the intermediate shaft. In the stress measuring device of the present invention, the torsional stress generated in the intermediate shaft can be calculated by measuring the temperature of the intermediate shaft when the torsional stress is generated in the intermediate shaft.

  (4) The fourth means is the invention according to claim 4, that is, the vehicle steering apparatus has a rack housing that accommodates the rack shaft, and the second support portion is inserted through the rack housing. The gist of the stress measuring device is the stress measuring device according to claim 2 or 3, wherein the stress measuring device supports a pinion shaft, is coaxial with the second rotation support shaft, and is formed integrally with the second rotation support shaft.

  In the stress measuring device, the second support portion and the second rotation support shaft are integrally formed. For this reason, compared with the structure in which a 2nd support part and a 2nd rotation support shaft are formed separately, the components which comprise a 2nd rotation mechanism decrease.

  (5) The fifth means is the invention according to claim 5, that is, the vehicle steering device has a rack housing that houses the rack shaft, and the stress measuring device is an auxiliary housing attached to the rack housing. The gist of the auxiliary housing is the stress measuring device according to any one of claims 1 to 4, which contacts the rack shaft.

  According to the stress measuring device, friction is generated between the auxiliary housing and the rack shaft when reproducing the state where the intermediate shaft of the vehicle steering device rotates. For this reason, by adjusting the magnitudes of the frictional forces of the auxiliary housing and the rack shaft, it is possible to reproduce the state of the vehicle steering device when the vehicle is traveling on a rough road, for example.

  (6) The sixth means is the invention according to claim 6, that is, the stress measuring method for measuring the stress of the vehicle steering device, wherein the vehicle steering device has a first column end and a second column end. A column shaft, an intermediate shaft having a first intermediate end and a second intermediate end, a pinion shaft having a first pinion end and a second pinion end, the second column end and the first intermediate A rack shaft having a first universal joint for connecting ends to each other, a second universal joint for connecting the second intermediate end and the first pinion end to each other, and a rack gear meshed with a pinion gear of the pinion shaft; And the stress measuring method revolves the first column end with respect to the intermediate shaft, Reproducing the same state as when the intermediate shaft is rotating as the state of the vehicle steering device by revolving the rack gear with respect to the pinion gear in synchronization with the revolving of the first column end with respect to the light shaft. A stress measurement method comprising: a reproduction step; a temperature measurement step of measuring the temperature of the intermediate shaft by an infrared camera; and a stress calculation step of calculating a stress of the intermediate shaft based on an output of the infrared camera. Is the gist.

  In the stress measuring method of the present invention, the first column end is revolved with respect to the intermediate shaft in the reproduction step, and the rack gear is revolved with respect to the pinion gear in synchronization with the revolution of the first column end with respect to the intermediate shaft.

  In the vehicle steering apparatus, the same relationship as the relative relationship among the column shaft, the intermediate shaft, and the pinion shaft when the intermediate shaft rotates is maintained when each component is rotated by the reproduction process. Further, the rack shaft revolves around the pinion gear, so that the rack shaft moves in the axial direction with respect to the pinion shaft.

  The state of the vehicle steering device at this time corresponds to a state in which the column shaft, the intermediate shaft, and the pinion shaft rotate together and, as a result, the rack shaft moves in the axial direction. That is, this corresponds to a state in which the rack shaft is moved by operating the steering wheel.

  As described above, the stress measurement method of the present invention reproduces substantially the same state as the state where the intermediate shaft rotates as the state of the vehicle steering device in the reproduction step. For this reason, it becomes possible to measure the stress of the intermediate shaft in a state where the position of the infrared camera is fixed in the temperature measurement process.

  The present invention provides a stress measuring device and a stress measuring method capable of measuring the stress of an intermediate shaft with an infrared camera.

The block diagram which shows the whole structure of the vehicle steering device which is a measuring object in the stress measuring device of embodiment of this invention. The block diagram which shows the structure of the stress measuring device of embodiment. Sectional drawing which shows the cross-section of the stress measuring device of embodiment. Sectional drawing which shows the cross-section of the load provision mechanism which the stress measuring device of other embodiment of this invention has. Sectional drawing which shows the cross-section of the 2nd rotation mechanism which the stress measuring device of other embodiment of this invention has.

With reference to FIG. 1, the whole structure of the vehicle steering device 70 is demonstrated.
The vehicle steering device 70 includes a column shaft 71, an intermediate shaft 72, a pinion shaft 73, a rack shaft 74, a cardan joint as a first universal joint 75, a cardan joint as a second universal joint 76, a rack housing 77, and an assist device. 78.

  The column shaft 71 has a first column end 71A and a second column end 71B. The first column end 71 </ b> A supports the steering wheel 2. The second column end 71 </ b> B is connected to the first universal joint 75.

  The intermediate shaft 72 has a first intermediate end 72A and a second intermediate end 72B. The first intermediate end portion 72 </ b> A is connected to the first universal joint 75. The second intermediate end 72B is connected to the second universal joint 76.

  The pinion shaft 73 has a first pinion end portion 73A and a second pinion end portion 73B. The first pinion end portion 73 </ b> A is connected to the second universal joint 76. The second pinion end 73B has a pinion gear 73C.

  The first universal joint 75 connects the column shaft 71 and the intermediate shaft 72 to each other. The first universal joint 75 transmits the rotation of the column shaft 71 to the intermediate shaft 72 in a state where the rotation center axis of the column shaft 71 and the rotation center axis of the intermediate shaft 72 intersect.

  The second universal joint 76 connects the intermediate shaft 72 and the pinion shaft 73 to each other. The second universal joint 76 transmits the rotation of the intermediate shaft 72 to the pinion shaft 73 in a state where the rotation center axis of the intermediate shaft 72 and the rotation center axis of the pinion shaft 73 intersect.

  The rack shaft 74 has a rack gear 74A and a rack-side stopper 74B. The rack shaft 74 supports the drive wheel 3 at both ends. The rack gear 74A meshes with the pinion gear 73C. The rack side stopper 74B has an annular shape. The rack-side stopper 74B is fixed to both ends of the rack shaft 74 in the axial direction.

The rack housing 77 accommodates the entire rack shaft 74 and a part of the pinion shaft 73. The rack housing 77 has a housing-side stopper 77A.
The housing side stopper 77 </ b> A is fixed to both ends of the rack housing 77 in the longitudinal direction. The housing-side stopper 77A regulates the movement of the rack shaft 74 relative to the rack housing 77 by contacting the rack-side stopper 74B.

  The assist device 78 includes an electric motor 78A, a worm shaft 78B, and a worm wheel 78C. The worm wheel 78C is fixed to an intermediate portion of the column shaft 71. The worm shaft 78B is meshed with the worm wheel 78C. The output shaft of the electric motor 78A is fixed to the worm shaft 78B.

  With reference to FIG. 2, the outline | summary of a structure of the stress measuring apparatus 1 is demonstrated. In the following description, “mounting equivalent posture” indicates a posture of the vehicle steering device 70 corresponding to a posture substantially the same as the posture when the vehicle steering device 70 is mounted on the vehicle. The “practical steering state” indicates a state in which the vehicle steering device 70 is operating in accordance with the operation of the steering wheel 2.

The stress measurement device 1 includes a support unit 10 and a measurement unit 60.
The support unit 10 reproduces the practical steering state of the vehicle steering device 70 in a state where the vehicle steering device 70 in the mounting equivalent posture is supported. The support unit 10 includes a drive mechanism 20, a first rotation mechanism 30, a second rotation mechanism 40, and an intermediate shaft support mechanism 50.

  The drive mechanism 20 rotates the first rotation mechanism 30 and the second rotation mechanism 40 in synchronization. The synchronization of the rotations of the first rotation mechanism 30 and the second rotation mechanism 40 is within a range that does not deviate from the range of difference in rotation of the pinion shaft 73 with respect to the rotation of the column shaft 71 that occurs in the practical steering state of the vehicle steering device 70. The difference of the rotational speed of the 2nd rotation mechanism 40 with respect to the rotation speed of the 1 rotation mechanism 30 is included.

The first rotation mechanism 30 revolves the first column end 71 </ b> A with respect to the intermediate shaft 72.
The second rotation mechanism 40 rotates the rack housing 77 and the rack shaft 74.

The intermediate shaft support mechanism 50 supports the intermediate shaft 72.
The measurement unit 60 measures the stress of the intermediate shaft 72 (hereinafter, “operation equivalent stress”) when the vehicle steering device 70 is in a practical steering state. The measurement unit 60 includes an infrared camera 61, a stress calculation unit 62, and a display unit 63.

  The infrared camera 61 calculates the temperature of the intermediate shaft 72 by measuring the infrared light of the intermediate shaft 72. The infrared camera 61 outputs a signal corresponding to the temperature of the intermediate shaft 72 to the stress calculation unit 62.

  The stress calculation unit 62 calculates an operation equivalent stress of the intermediate shaft 72 based on the output of the infrared camera 61. The stress calculation unit 62 generates an image showing the stress distribution of the motion equivalent stress by associating the calculated motion equivalent stress with the image of the intermediate shaft 72. The display unit 63 displays the image generated by the stress calculation unit 62.

With reference to FIG. 3, the detailed structure of the stress measuring apparatus 1 is demonstrated.
In the stress measurement device 1, the direction toward the second rotation mechanism 40 and the first rotation mechanism 30 in this order is referred to as “upward direction ZA1”. Further, a direction toward the first rotation mechanism 30 and the second rotation mechanism 40 in this order is referred to as “downward direction ZA2”.

The drive mechanism 20 includes a first drive transmission unit 21, a second drive transmission unit 22, an electric motor 23, and a rotating shaft 24.
The rotating shaft 24 is connected to the output shaft of the electric motor 23. The first drive transmission unit 21 includes an upper input side rotation member 21A, an upper output side rotation member 21B, and an upper winding member 21C. The first drive transmission unit 21 transmits the rotation of the output shaft of the electric motor 23 to the first rotation mechanism 30. The upper input side rotation member 21 </ b> A is fixed to the upper end portion of the rotation shaft 24. The upper output side rotation member 21 </ b> B is fixed to the first rotation support shaft 31 of the first rotation mechanism 30. The upper winding member 21C is wound around the upper input side rotating member 21A and the upper output side rotating member 21B. The upper winding member 21C transmits the rotation of the upper input side rotation member 21A to the upper output side rotation member 21B.

  The second drive transmission unit 22 includes a lower input side rotating member 22A, a lower output side rotating member 22B, and a lower winding member 22C. The second drive transmission unit 22 transmits the rotation of the output shaft of the electric motor 23 to the second rotation mechanism 40.

  The lower input side rotating member 22 </ b> A is fixed to the lower end portion of the rotating shaft 24. The lower output side rotation member 22 </ b> B is fixed to the second shaft body 41 of the second rotation mechanism 40. The lower winding member 22C is wound around the lower input side rotating member 22A and the lower output side rotating member 22B. The lower winding member 22C transmits the rotation of the lower input side rotating member 22A to the lower output side rotating member 22B.

  The first rotation mechanism 30 includes a first rotation support shaft 31, a fixed shaft 32, a fixed side circular member 33, a first transmission portion 34, a first support portion 35, a rolling bearing 36, a transmission side circular member 37, and a winding member 38. And a first bearing mechanism 39.

  The first bearing mechanism 39 has a fixed hole 39A, an opening portion 39B, and a rolling bearing 39C. The fixed hole 39 </ b> A passes through the first bearing mechanism 39 in the rotation center axis of the first rotation support shaft 31. The opening portion 39B opens toward the downward direction ZA2. The opening portion 39B communicates with the fixing hole 39A. The rolling bearing 39C is fixed to the opening portion 39B. The rolling bearing 39C supports the first rotation support shaft 31 in a state where the first rotation support shaft 31 can rotate with respect to the first bearing mechanism 39.

  The first rotation support shaft 31 is inserted into the opening portion 39B. The first rotation support shaft 31 has a through hole 31 </ b> A that penetrates the first rotation support shaft 31 in the axial direction of the first rotation support shaft 31. The first rotation support shaft 31 has a rotation center axis coaxially with the intermediate shaft 72.

  The fixed shaft 32 is inserted into the through hole 31 </ b> A of the first rotation support shaft 31. The upper end portion of the fixed shaft 32 protrudes in the upward direction ZA1 from the first rotation support shaft 31. The upper end portion of the fixed shaft 32 is press-fitted into the inner peripheral surface of the fixed hole 39A. The lower end portion of the fixed shaft 32 protrudes in the downward direction ZA2 from the first rotation support shaft 31.

The fixed-side circular member 33 is fixed to the lower end portion of the fixed shaft 32.
The first transmission portion 34 has a space inside. The first transmission portion 34 is fixed to the lower end portion of the first rotation support shaft 31. The first transmission portion 34 has a rotation center axis coaxially with the first rotation support shaft 31. The first transmission portion 34 transmits the rotation of the first rotation support shaft 31 to the first support portion 35.

  The first support portion 35 is connected to the column shaft 71. The first support portion 35 supports the column shaft 71 that is inclined with respect to the intermediate shaft 72. The first support portion 35 revolves with respect to the intermediate shaft 72 by revolving with respect to the rotation center axis of the first transmission portion 34. The first support portion 35 includes a transmission side support portion 35A, a column side support portion 35B, and a constant velocity joint 35C. The posture in which the column shaft 71 is inclined with respect to the intermediate shaft 72 indicates the posture of the column shaft 71 with respect to the intermediate shaft 72 in the posture equivalent to the mounting of the vehicle steering device 70.

  The transmission side support portion 35 </ b> A is attached to the outer peripheral portion of the first transmission portion 34. The transmission side support portion 35 </ b> A is parallel to the rotation center axis of the first transmission portion 34. The column side support portion 35B is connected to the first column end portion 71A. The constant velocity joint 35C connects the lower end portion of the transmission side support portion 35A and the upper end portion of the column side support portion 35B. The constant velocity joint 35C changes the posture of the column side support portion 35B with respect to the transmission side support portion 35A.

  The rolling bearing 36 is fixed to the first transmission portion 34. The rolling bearing 36 supports the transmission side support portion 35 </ b> A in a state where the transmission side support portion 35 </ b> A can rotate with respect to the first transmission portion 34. One rolling bearing 36 supports the upper end portion of the transmission-side support portion 35A. The other rolling bearing 36 supports an intermediate portion of the transmission side support portion 35A.

The second rotation mechanism 40 includes a second shaft body 41 and a second bearing mechanism 42.
The second shaft body 41 is coaxial with the intermediate shaft 72 and the first rotation support shaft 31. The second shaft body 41 is fixed to the rack housing 77. The second shaft body 41 supports the pinion shaft 73 that is inclined with respect to the intermediate shaft 72. The second shaft body 41 has a rotation center axis coaxially with the intermediate shaft 72. Note that the posture in which the pinion shaft 73 is inclined with respect to the intermediate shaft 72 indicates the posture of the pinion shaft 73 with respect to the intermediate shaft 72 in the mounting equivalent posture of the vehicle steering device 70.

  The second bearing mechanism 42 has a through hole 42A and two rolling bearings 42B. The through hole 42 </ b> A penetrates the second bearing mechanism 42 in the rotation center axis of the second shaft body 41. The rolling bearing 42B is fixed to the inner peripheral surface of the through hole 42A. The rolling bearing 42 </ b> B supports the second shaft body 41 in a state where the second shaft body 41 can rotate with respect to the second bearing mechanism 42.

  Two intermediate shaft support mechanisms 50 are formed apart from each other in the axial direction of the intermediate shaft 72. The intermediate shaft support mechanism 50 includes a through hole 51 and two rolling bearings 52. The through hole 51 passes through the intermediate shaft support mechanism 50 in the axial direction of the intermediate shaft 72. The rolling bearing 52 is fixed to the inner peripheral surface of the through hole 51. The rolling bearing 52 supports the intermediate shaft 72 in a state where the intermediate shaft 72 can rotate with respect to the intermediate shaft support mechanism 50. One rolling bearing 52 supports the intermediate shaft 72 in the upward direction ZA1. The other rolling bearing 52 supports a portion of the intermediate shaft 72 in the downward direction ZA2.

  The infrared camera 61 is disposed at a position where the infrared light of the intermediate shaft 72 can be detected. The infrared camera 61 has a central axis orthogonal to the rotational central axis of the intermediate shaft 72. The infrared camera 61 uses a portion between the two intermediate shaft support mechanisms 50 in the intermediate shaft 72 as a measurement target portion. The infrared camera 61 uses a part of the measurement target portion of the intermediate shaft 72 as a detection range in the circumferential direction of the intermediate shaft 72. The infrared camera 61 has an infrared sensor and a lock-in processor (both not shown).

  The infrared sensor detects infrared rays emitted from the surface of the measurement target portion of the intermediate shaft 72. The infrared sensor outputs an electrical signal corresponding to the infrared ray as an image signal to the lock-in processor.

The lock-in processor performs a lock-in process. The lock-in processor outputs the image signal after the lock-in process to the stress calculation unit 62.
In the lock-in process, only an electric signal in a predetermined range of frequency band including a temperature change waveform due to the thermoelastic effect of the intermediate shaft 72, that is, a frequency synchronized with stress fluctuation, is extracted from the image signal of the infrared sensor.

  The stress calculation unit 62 receives an image signal output from the lock-in processor. The stress calculation unit 62 calculates the stress distribution of the operation equivalent stress of the intermediate shaft 72 based on the temperature of the intermediate shaft 72 obtained from the received image signal. The display unit 63 displays the stress distribution of the operation equivalent stress of the intermediate shaft 72 on the monitor.

The operation and action of the stress measuring device 1 will be described.
When the output shaft of the electric motor 23 of the drive mechanism 20 rotates, the rotating shaft 24, the upper input side rotating member 21A of the first rotating mechanism 30, and the lower input side rotating member 22A of the second rotating mechanism 40 rotate together.

In the first rotation mechanism 30, rotation is transmitted as follows.
The rotation of the upper input side rotating member 21A is transmitted to the upper output side rotating member 21B via the upper winding member 21C. The first rotation support shaft 31 and the first transmission portion 34 rotate with the rotation of the upper output side rotation member 21B. The transmission-side support portion 35A revolves with respect to the rotation center axis of the first transmission portion 34 as the first transmission portion 34 rotates. The column side support portion 35B revolves with respect to the rotation center axis of the first transmission portion 34 as the transmission side support portion 35A revolves. The first column end 71A revolves with respect to the intermediate shaft 72 as the column-side support portion 35B revolves. The “intermediate shaft 72 is stationary” includes a slight rotation of the intermediate shaft 72 in a range where the measurement target portion of the intermediate shaft 72 does not deviate from the detection range of the infrared camera 61.

In the second rotation mechanism 40, rotation is transmitted as follows.
The rotation of the lower input side rotating member 22A is transmitted to the lower output side rotating member 22B via the lower winding member 22C. The second shaft body 41 rotates with the rotation of the lower output side rotation member 22B. The rack housing 77 rotates as the second shaft body 41 rotates. The rack gear 74A revolves with respect to the pinion gear 73C. As a result, the meshing position of the rack gear 74 </ b> A and the pinion gear 73 </ b> C changes, so that the rack shaft 74 moves in the axial direction of the rack shaft 74 with respect to the rack housing 77. The pinion shaft 73 revolves with respect to the intermediate shaft 72 at the second pinion end 73 </ b> B.

  The intermediate shaft 72 is restrained from rotating with respect to the revolution of the column shaft 71 by the first universal joint 75. The intermediate shaft 72 is restrained from rotating with respect to the revolution of the pinion shaft 73 by the second universal joint 76. The intermediate shaft 72 includes the column shaft 71, the intermediate shaft 72, and the pinion when the intermediate shaft 72 rotates as a state of the vehicle steering device 70 when the column shaft 71 and the pinion shaft 73 rotate synchronously. The same relationship as the relative relationship of the shaft 73 is maintained.

  When the rotation amounts of the column shaft 71 and the pinion shaft 73 by the drive mechanism 20 exceed a certain amount, the rack-side stopper 74B comes into contact with the housing-side stopper 77A. Thereby, the movement of the rack shaft 74 is restricted by the rack housing 77. At this time, the electric motor 23 increases the current to rotate the second shaft body 41. The stress measuring device 1 reversely rotates or stops the output shaft of the electric motor 23 based on the current of the electric motor 23 reaching a preset threshold value. In this way, the practical steering state of the vehicle steering device 70 is reproduced while the intermediate shaft 72 is kept stationary by the first rotating mechanism 30 and the second rotating mechanism 40.

  When the movement of the rack shaft 74 is restricted by the rack housing 77, the revolution of the rack gear 74A relative to the pinion gear 73C is also restricted. At this time, when the transmission of torque from the drive mechanism 20 to the second rotation mechanism 40 is continued, a force for revolving the rack gear 74A with respect to the pinion gear 73C acts on the rack gear 74A. However, since the revolution of the rack gear 74A relative to the pinion gear 73C is restricted as described above, the force acting on the rack gear 74A acts as a force for rotating the pinion gear 73C.

  For this reason, the force which rotates the pinion shaft 73, the intermediate shaft 72, and the column shaft 71 integrally acts on these shafts 71-73. On the other hand, the first support portion 35 is connected to the fixed shaft 32 via the transmission-side circular member 37, the winding member 38, and the fixed-side circular member 33. For this reason, the first support portion 35 cannot rotate.

  For this reason, the rotation of the column shaft 71 is restricted by the first support portion 35. That is, the second intermediate end portion 72B of the intermediate shaft 72 is allowed to rotate by torque acting on the pinion gear 73C, and the first intermediate end portion 72A of the intermediate shaft 72 is rotated by the same torque. 1 is regulated by the support portion 35.

  For this reason, a torsional stress is generated in the intermediate shaft 72. In the stress measuring apparatus 1, the torsional stress generated in the intermediate shaft 72 is calculated by measuring the temperature of the intermediate shaft 72 when the torsional stress is generated in the intermediate shaft 72.

A stress measurement method using the stress measurement apparatus 1 will be described.
The stress measurement method includes a reproduction process, a temperature measurement process, and a stress calculation process.
In the reproduction step, the practical steering state of the vehicle steering device 70 is reproduced while the intermediate shaft 72 is stationary by rotating the first rotation mechanism 30 and the second rotation mechanism 40.

  In the temperature measurement step, the temperature of the measurement target portion of the intermediate shaft 72 is measured by the infrared camera 61 in a state where the practical steering state of the vehicle steering device 70 is reproduced by the reproduction step.

  When the movement of the rack shaft 74 in the axial direction with respect to the rack housing 77 is restricted, the intermediate shaft 72 is twisted, so that the temperature of the intermediate shaft 72 changes due to the thermoelastic effect of the intermediate shaft 72. The infrared camera 61 acquires the temperature change of the intermediate shaft 72.

  In the stress calculation process, the stress calculation unit 62 calculates the operation equivalent stress of the intermediate shaft 72 based on the temperature of the intermediate shaft 72 acquired by the infrared camera 61 in the temperature measurement process. The operation equivalent stress of the intermediate shaft 72 is displayed on the display unit 63 as a stress distribution of the operation equivalent stress.

The stress measuring device 1 of this embodiment has the following effects.
(1) The stress measurement device 1 includes a first rotation mechanism 30 and a second rotation mechanism 40. According to this configuration, the stationary state of the intermediate shaft 72 is maintained in the practical steering state of the vehicle steering device 70. Thereby, in the practical steering state of the vehicle steering device 70, the temperature of the measurement target portion of the intermediate shaft 72 can be measured with the infrared camera 61 fixed.

  (2) When the vehicle steering device 70 is attached to the support portion 10, the vehicle steering device 70 is maintained in the mounting equivalent posture. According to this configuration, the stress measuring device 1 can measure the operation equivalent stress of the intermediate shaft 72 when the vehicle steering device 70 is in the mounting equivalent posture.

  (3) The stress measuring device 1 includes a fixed shaft 32, a fixed-side circular member 33, a transmission-side circular member 37, and a winding member 38. According to this configuration, when the movement of the rack shaft 74 in the axial direction with respect to the rack housing 77 is restricted, the rack shaft 74 and the pinion shaft 73 are twisted to the intermediate shaft 72. For this reason, the stress measuring apparatus 1 can measure the torsional stress of the intermediate shaft 72 in the practical steering state of the vehicle steering apparatus 70.

  (4) The second shaft body 41 has a function of a second support portion that supports the pinion shaft 73 in a posture inclined with respect to the intermediate shaft 72, and a rotation center axis coaxially with the intermediate shaft 72. It has the function of the 2nd rotation support shaft which rotates the rack housing 77, and the function of the 2nd transmission part which transmits rotation of a 2nd rotation support shaft to a 2nd support part. According to this structure, compared with the structure which forms a 2nd support part, a 2nd rotation support shaft, and a 2nd transmission part separately, the components which comprise the 2nd rotation mechanism 40 decrease.

  The present invention includes an embodiment different from the above embodiment. Hereinafter, the modification of the said embodiment as other embodiment of this invention is shown. The following modifications can be combined with each other.

  -Stress measuring device 1 of an embodiment measures the stress of intermediate shaft 72 in the state where assistant device 78 stopped. On the other hand, the stress measuring device 1 of the modified example measures the stress of the intermediate shaft 72 in a state where the assist device 78 is driven. In short, as long as the state of the vehicle steering device 70 can occur as a practical steering state, the state of the vehicle steering device 70 reproduced by the stress measurement device 1 is not limited to the state reproduced in the stress measurement device 1 of the embodiment.

  The drive mechanism 20 of the stress measurement device 1 according to the embodiment includes one electric motor 23 and a rotation shaft 24 that are common to the first rotation mechanism 30 and the second rotation mechanism 40. On the other hand, the drive mechanism 20 of the modified example is replaced with the first electric motor that transmits torque to the first rotating mechanism 30 instead of the electric motor 23 and the rotating shaft 24, and the second electric motor that transmits torque to the second rotating mechanism 40. Has a motor. The upper input side rotation member 21A is fixed to the output shaft of the first electric motor. The lower input side rotating member 22A is fixed to the output shaft of the second electric motor. The drive circuits for the first electric motor and the second electric motor rotate the first electric motor and the second electric motor in synchronization with each other.

  The stress measurement device 1 according to the embodiment does not have a mechanism that applies a load to the rack shaft 74 that moves in the axial direction. On the other hand, as shown in FIG. 4, the stress measuring apparatus 1 according to the modification includes a load applying mechanism 80 that applies a load to the rack shaft 74 that moves in the axial direction. The load application mechanism 80 has an auxiliary housing 81. The auxiliary housing 81 is fixed to each end of the rack housing 77. The auxiliary housing 81 accommodates a part of the portion of the rack shaft 74 that protrudes from the rack housing 77. The base end portion of the rack side stopper 74 </ b> B contacts the inner surface of the auxiliary housing 81.

  According to the stress measurement device 1 of the above modification, friction is generated between the auxiliary housing 81 and the rack-side stopper 74B when the practical steering state of the vehicle steering device 70 is reproduced. For this reason, by adjusting the magnitudes of the frictional forces of the auxiliary housing 81 and the rack-side stopper 74B, it is possible to reproduce the state of the vehicle steering device 70 when the vehicle is traveling on a rough road, for example.

  -The 2nd shaft body 41 of the 2nd rotation mechanism 40 of embodiment has a function as a 2nd rotation support shaft, a 2nd transmission part, and a 2nd support part. That is, the second shaft body 41 supports the pinion shaft 73, has a rotation center axis coaxially with the intermediate shaft 72, and rotates about the rotation center axis. On the other hand, as shown in FIG. 5, the modified second rotation mechanism 40 includes a second rotation support shaft 91, a second transmission portion 92, and a second support portion 93 instead of the second shaft body 41. The second rotation support shaft 91 has a rotation center axis coaxially with the intermediate shaft 72 and rotates around the rotation center axis. The second transmission portion 92 transmits the rotation of the second rotation support shaft 91 to the second support portion 93. The second support portion 93 supports the pinion shaft 73 that is inclined with respect to the intermediate shaft 72.

  -The measurement part 60 of embodiment does not have the imaging device which image | photographs the external appearance of the intermediate shaft 72. FIG. On the other hand, the measurement unit 60 according to the modified example includes a photographing device that photographs the appearance of the intermediate shaft 72. The stress calculation unit 62 calculates the stress of the intermediate shaft 72 based on the temperature output from the infrared camera 61 and the captured image output from the imaging device. In short, in addition to the temperature measured by the infrared camera 61, other information related to the intermediate shaft 72 can be measured, and the stress of the intermediate shaft 72 can be calculated based on the temperature and other information.

  In the embodiment, the infrared camera 61 measures the temperature of the intermediate shaft 72. On the other hand, the infrared camera 61 of the modified example measures the temperature of the intermediate shaft 72 and photographs the appearance of the intermediate shaft 72 at the same time. The stress calculation unit 62 calculates the stress of the intermediate shaft 72 based on the temperature output from the infrared camera 61 and the captured image.

  -The measurement part 60 of embodiment has the infrared camera 61 which has a lock-in processor. On the other hand, the measurement unit 60 of the modification has an infrared camera 61 in which the lock-in processor is omitted. Further, a lock-in processor is provided as a device different from the infrared camera 61. In short, as long as the stress can be calculated based on the output of the infrared camera 61, the specific configuration of the infrared camera 61 provided in the measurement unit 60 is not limited to the configuration of the embodiment.

  The support unit 10 according to the embodiment supports the vehicle steering device 70 in the mounting equivalent posture. On the other hand, the support unit 10 of the modified example supports the vehicle steering device 70 in a posture other than the mounting equivalent posture. In short, the column shaft 71, the intermediate shaft 72, and the pinion have a configuration in which the posture in which the column shaft 71 is inclined with respect to the intermediate shaft 72 and the posture in which the pinion shaft 73 is inclined with respect to the intermediate shaft 72 are possible. The specific configuration of the shaft 73 is not limited to the configuration of the embodiment.

  The vehicle steering apparatus 70 according to the embodiment includes cardan joints as the first universal joint 75 and the second universal joint 76. On the other hand, the vehicle steering apparatus 70 according to the modified example has a Rzeppa joint instead of at least one cardan joint of the first universal joint 75 and the second universal joint 76. In short, if it is a universal joint, the specific structure of the 1st universal joint 75 and the 2nd universal joint 76 is not restricted to the structure of embodiment.

  -The stress measuring device 1 of embodiment uses the vehicle steering device 70 which has the assist apparatus 78 as a measuring object. On the other hand, the stress measuring device 1 according to the modified example uses the vehicle steering device 70 having a configuration in which the assist device 78 is omitted as a measurement target. In short, as long as the vehicle steering apparatus has the intermediate shaft 72, the specific configuration of the vehicle steering apparatus to be measured is not limited to the configuration of the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Stress measuring device, 2 ... Steering wheel, 10 ... Support part, 20 ... Drive mechanism, 30 ... 1st rotation mechanism, 31 ... 1st rotation support shaft, 32 ... Fixed shaft, 33 ... Fixed side circular member, 34 ... 1st transmission part, 35 ... 1st support part, 37 ... Transmission side circular member, 38 ... Winding member, 39 ... 1st bearing mechanism, 40 ... 2nd rotation mechanism, 41 ... 2nd shaft body, 60 ... Measurement part , 61 ... Infrared camera, 62 ... Stress calculation unit, 70 ... Vehicle steering device, 71 ... Column shaft, 71A ... First column end, 71B ... Second column end, 72 ... Intermediate shaft, 72A ... First intermediate Object end, 72B ... second intermediate end, 73 ... pinion shaft, 73A ... first pinion end, 73B ... second pinion end, 73C ... pinion gear, 74 ... rack shaft, 74A ... rack gear, 75 ... first Universal joint, 76 ... second universal joint, 77 ... rack housing, 81 ... auxiliary housing 90 ... second rotating mechanism, 91 ... second rotary support shaft, 92 ... second transmission portion, 93 ... second support portion.

Claims (6)

In a stress measurement device having a support portion that supports a vehicle steering device and a measurement unit that measures stress of the vehicle steering device,
The vehicle steering apparatus includes a column shaft having a first column end and a second column end, an intermediate shaft having a first intermediate end and a second intermediate end, a first pinion end and a second pinion. A pinion shaft having an end, a first universal joint for connecting the second column end and the first intermediate end, and a second joint for connecting the second intermediate end and the first pinion end to each other; A universal joint, and a rack shaft having a rack gear meshed with the pinion gear of the pinion shaft;
The support portion includes a first rotation mechanism for revolving the first column end portion with respect to the intermediate shaft, a second rotation mechanism for revolving the rack gear with respect to the pinion gear, the first rotation mechanism, and the A drive mechanism that rotates the second rotation mechanism synchronously;
The said measurement part has an infrared camera which measures the temperature of the said intermediate shaft, and a stress calculating part which calculates the stress of the said intermediate shaft based on the output of the said infrared camera. The first rotation mechanism includes a first support portion capable of supporting the column shaft in a posture inclined with respect to the intermediate shaft, and a first rotation having a rotation center axis coaxially with the intermediate shaft. A support shaft; and a first transmission portion that transmits rotation of the first rotation support shaft to the first support portion;
The second rotation mechanism has a second support portion capable of supporting the pinion shaft in a posture inclined with respect to the intermediate shaft, and a second rotation having a rotation center axis coaxially with the intermediate shaft. The stress measuring device according to claim 1, further comprising: a support shaft; and a second transmission portion that transmits rotation of the second rotation support shaft to the second support portion. The vehicle steering apparatus has a rack housing that houses the rack shaft,
The first rotation mechanism includes a first bearing mechanism that supports the first rotation support shaft in a rotatable state, a fixed shaft that is fixed to the first bearing mechanism, and a fixed-side circular shape that is fixed to the fixed shaft. A member, a transmission-side circular member fixed to the first support portion, and a winding member wound around the fixed-side circular member and the transmission-side circular member,
The stress measurement apparatus according to claim 2, wherein the first support portion supports the first column end. The vehicle steering apparatus has a rack housing that houses the rack shaft,
The second support portion supports the pinion shaft via the rack housing, has the same axis as the second rotation support shaft, and is formed integrally with the second rotation support shaft. The stress measuring device described in 1. The vehicle steering apparatus has a rack housing that houses the rack shaft,
The stress measuring device has an auxiliary housing attached to the rack housing,
The stress measuring device according to any one of claims 1 to 4, wherein the auxiliary housing contacts the rack shaft. In a stress measurement method for measuring the stress of a vehicle steering device,
The vehicle steering device is
A column shaft having a first column end and a second column end, an intermediate shaft having a first intermediate end and a second intermediate end, a pinion shaft having a first pinion end and a second pinion end A first universal joint for connecting the second column end and the first intermediate end to each other, a second universal joint for connecting the second intermediate end and the first pinion end to each other, and the pinion A rack shaft having a rack gear meshed with a pinion gear of the shaft;
The stress measuring method is:
The vehicle steering apparatus is configured to revolve the first column end with respect to the intermediate shaft and revolve the rack gear with respect to the pinion gear in synchronization with the revolution of the first column end with respect to the intermediate shaft. A reproduction process for reproducing the same state as when the intermediate shaft rotates as a state of
A temperature measuring step of measuring the temperature of the intermediate shaft with an infrared camera;
A stress calculation method comprising: calculating a stress of the intermediate shaft based on an output of the infrared camera.