JP3887213B2 - Vehicle steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention superimposes the steering angle on the steering operation of the driver.First rudder angle ratio variable mechanismAnd change the rudder angle ratioSecondThe present invention relates to a vehicle steering system including a steering angle ratio variable mechanism.
[0002]
[Prior art]
  A variable steering angle ratio steering apparatus described in Japanese Patent No. 2866302 according to the application of the present applicant is a steering angle ratio provided between an input shaft connected to a steering wheel and an output shaft for turning a steering wheel. The variable mechanism increases the steering angle ratio (steering wheel steering angle / steering wheel turning angle) at high vehicle speeds to ensure vehicle running stability, and at low vehicle speeds to reduce the steering angle ratio to handle the vehicle. To make it easier.
[0003]
  Further, in Japanese Patent No. 2992357, a clutch is provided between an input shaft connected to the steering wheel and an output shaft connected to the steering wheel, and normally the clutch is released to separate the input shaft and the output shaft, A so-called SBW (steer steering wheel) that corrects the vehicle motion by controlling the steering angle by the steering control means according to the driver's operation input so as to reduce the deviation between the normative vehicle motion state and the actual vehicle motion state. A vehicle motion characteristic correction apparatus of a (by-wire) system is described.
[0004]
  Japanese Laid-Open Patent Publication No. 7-315235 provides a steering angle ratio variable mechanism having a planetary gear device between an input shaft connected to a steering wheel and an output shaft connected to a steering wheel so that a driver can perform steering operation. A SBW type power steering device is described in which a first steering motion based on the above and a second steering motion based on the operation of a servo device are superimposed and input to the steering transmission device to intervene in the steering operation of the driver. Yes.
[0005]
[Problems to be solved by the invention]
  By the way, what is described in the above-mentioned Japanese Patent No. 2992357 is that a driver performs direct steering through a steering gear box with a predetermined steering angle ratio by engaging a clutch when the SBW system fails. However, since the steering control means performs steering with the clutch released and the input shaft and output shaft disconnected in normal times, the neutral position of the steering wheel and the neutral position of the steering wheel are There is a possibility that a large phase difference will occur between the left and right steering lock angles (the angle from the current steering wheel position to the position where the steering wheel can no longer be rotated) may become unbalanced. is there. In addition, if the SBW system fails, it is necessary to quickly engage the clutch and switch to direct steering by the driver. However, the steering torque applied to the steering wheel suddenly changes as the clutch is engaged, and the driver may feel uncomfortable. There is sex.
[0006]
  Also in the above-mentioned Japanese Patent Application Laid-Open No. 7-315235, when the SBW system breaks down and is switched to direct steering by the driver, a mismatch between the phase of the steering wheel and the phase of the steering wheel occurs, and the steering is again performed. Since the steering torque applied to the wheel may change suddenly, there is a problem that if the safety at the time of failure is anticipated, the range for changing the steering angle ratio cannot be set large.
[0007]
  In addition, a large change in the steering angle ratio due to a failure of the SBW system has a problem that it becomes difficult to predict the amount of operation required when the driver performs the next steering operation, and is particularly familiar with vehicle motion control using a small steering angle. If the driver changes to a fixed rudder angle ratio in the event of a failure, the driver may not be immediately familiar with the steering operation, which may interfere with the steering operation.
[0008]
  The present invention has been made in view of the above circumstances, and superimposes the steering angle on the steering operation of the driver.First rudder angle ratio variable mechanismAn object of the present invention is to minimize the occurrence of problems at the time of failure in a vehicle steering system equipped with the above.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, the steering angle of the steering wheel is transmitted to the steering mechanism of the steering wheel by mechanical connection with the steering wheel.RudeThe steering angle generated by the driving mechanism and the driving force of the actuator, DrivingSuperimposed on the steering angle transmitted from the dynamic mechanismTo change the rudder angle ratioDoFirst rudder angle ratio variable mechanismAnd the steering angle ratio, which is the ratio of the superposed steering angle and the steered wheel steered angle, is changed and transmitted to the steered wheel steered mechanism.SecondThere is proposed a vehicle steering apparatus including a steering angle ratio variable mechanism.
[0010]
  According to the above configuration,By the first rudder angle ratio variable mechanismThe rudder angle ratio between the steered steering angle and the steered wheel turning angle can be changed.SecondIn order to obtain the target turning angle of the steered wheels by providing the steering angle ratio variable mechanismFirst rudder angle ratio variable mechanismThe steering angle to be superimposed by actuating the actuator can be set small. Therefore, by any chanceFirst rudder angle ratio variable mechanismIf the steering angle overlaps from the actuator due to failure,First rudder angle ratio variable mechanismSince the steering angle superimposed from the actuator of the steering wheel is small, not only can the change in steering torque received by the driver from the steering wheel at that time be reduced, but also between the steering angle of the steering wheel and the turning angle of the steering wheel. Deviations that occur can be minimized.
[0011]
  And even after the failure,SecondSince the steering angle ratio between the steering angle and the turning angle can be changed by the steering angle ratio variable mechanism, for example, in a low vehicle speed range, the steering angle ratio is changed to be small and the steering is sharpened to facilitate the handling of the vehicle. In the high vehicle speed range, it is possible to continue to set the appropriate steering angle ratio according to the running state of the vehicle, for example, by improving the running stability of the vehicle by greatly changing the steering angle ratio and reducing the steering effect. .
[0012]
  By any chanceSecondWhen the steering angle ratio variable mechanism fails, it is possible to eliminate the change in the steering torque that the driver receives from the steering wheel by inheriting the steering angle ratio immediately before the failure as it is. MoreSecondEven if the rudder angle ratio variable mechanism breaks downFirst rudder angle ratio variable mechanismAs long as is functioning normally, there will be no phase difference between the neutral position of the steering wheel and the neutral position of the steering wheel.First rudder angle ratio variable mechanismFailure due to superposition of steering angle bySecondThe steering angle ratio can be changed in place of the steering angle ratio variable mechanism.
[0013]
  According to the invention described in claim 2, in addition to the configuration of claim 1, there is proposed a vehicle steering apparatus characterized in that the vehicle steering apparatus is a cable type steering apparatus.
[0014]
  The steering gear box 13 of the embodiment corresponds to the steering mechanism of the steered wheel of the present invention, and the steering angle transmission mechanism M1 of the embodiment is the present invention.The drive ofAgainst dynamic mechanismRespondThe
[0015]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0016]
  1 to 15 show an embodiment of the present invention. FIG. 1 is an overall perspective view of a vehicle steering apparatus, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. FIG. 4 is a perspective view of the steering torque sensor, FIG. 5 is a circuit diagram of a differential transformer of the steering torque sensor, FIG. 6 is an operation explanatory view of the steering torque sensor, and FIG. 7 is 7-7 in FIG. 8 is a sectional view taken along line 8-8 in FIG. 7, FIG. 9 is a sectional view taken along line 9-9 in FIG. 7, FIG. 10 is a sectional view taken along line 10-10 in FIG.SecondAn exploded perspective view of the steering angle ratio variable mechanism, FIG. 12 is an operation explanatory view corresponding to FIG. 8, and FIG.SecondFIG. 14 is a diagram for explaining the operating principle of the steering angle ratio variable mechanism.SecondThe steering angle ratio characteristic diagram of the steering angle ratio variable mechanism, FIG. 15 is a block diagram of the control system.
[0017]
  As shown in FIG. 1, a drive pulley casing 12 provided in front of a steering wheel 11 of an automobile and a driven pulley casing 14 provided above a steering gear box 13 include a first operation cable 15 formed of a Bowden cable and a first operation cable 15. Two operation cables 16 are connected. Tie rods 17L, 17R extending in the left-right direction of the vehicle body from both ends of the steering gear box 13 are connected to knuckles (not shown) that support the left and right steering wheels WL, WR. A steering torque sensor for detecting a steering torque input to the steering wheel 11 is built in the drive pulley casing 12 and is coaxial with the steering gear box 13 by a command from the control device 18 to which the detected steering torque is input. The auxiliary steering torque motor 20 provided in the above is actuated to assist the driver's steering operation.
[0018]
  As shown in FIG. 2, the drive pulley casing 12 includes a rear housing 21, a center housing 22, and a front housing 23 connected by bolts 24... And a front cover 25 is connected to the front surface of the front housing 23 by bolts (not shown). Is done. In the drive pulley casing 12, a bracket 21 a provided on the rear housing 21 is fixed to the mounting stay 26 with a pin 27, and a bracket 23 a provided on the front housing 23 is fixed to the mounting stay 26 with a bolt 28.
[0019]
  A hollow steering shaft 29 connected to the steering wheel 11 is rotatably supported on the rear housing 21 by two ball bearings 30 and 31. A metal pulley boss 33 is fixed to the outer periphery of a hollow pulley shaft 32 arranged coaxially with the steering wheel 11, and a drive pulley body made of synthetic resin so as to cover a serration portion 33 a formed on the outer periphery of the pulley boss 33. 34 is molded integrally. Both ends of the pulley boss 33 are rotatably supported by the front housing 23 and the front cover 25 by two ball bearings 35 and 36, respectively, and the pulley shaft 32 is rotatably supported by the center housing 22 by a ball bearing 37. . The pulley boss 33 and the drive pulley body 34 constitute a drive pulley 59.
[0020]
  The inner periphery of the front end portion of the steering shaft 29 is fitted to the outer periphery of the rear end portion of the pulley shaft 32 so as to be relatively rotatable, and both end portions of the torsion bar 38 are connected to the hollow portion of the steering shaft 29 and the hollow portion of the pulley shaft 32. They are fitted and connected by pins 39 and 40, respectively. Therefore, the steering torque input to the steering shaft 29 is transmitted from the steering shaft 29 to the pulley shaft 32 via the torsion bar 38, and the steering torque sensor 41 provided in the center housing 22 is connected to the torsion bar. The steering torque is detected based on the twist amount of 38.
[0021]
  As is clear from FIGS. 2 and 4, the steering torque sensor 41 is fixed to the steering shaft 29 and the cylindrical slider 42 supported on the outer periphery of the pulley shaft 32 so as not to rotate relative to the pulley shaft 32 and to be axially slidable. A guide pin 43 fitted in an inclined groove 42 a formed in the slider 42, a magnetic ring 44 fixed to the outer periphery of the slider 42 made of synthetic resin, and a magnetic ring 44 fixed to the inner periphery of the center housing 22. And a coil spring 46 that urges the slider 42 forward to prevent backlash between the guide pin 43 and the inclined groove 42a.
[0022]
  As shown in FIG. 5, the differential transformer 45 of the steering torque sensor 41 includes a primary coil 48 connected to an AC power source 47, a first secondary coil 49, and a second secondary coil 50. The magnetic ring 44 constitutes a movable iron core disposed between the first and second secondary coils 49 and 50.
[0023]
  As is apparent from FIG. 2, the front end portion of the pulley shaft 32 and the pulley boss 33 are coupled at the serration coupling portion 51, and are coupled via a tapered coupling portion 52 that is tapered toward the front end portion of the pulley shaft 32. Is done. A nut 53 is screwed into the front end of the pulley shaft 32, and the pulley boss 33 is urged rearward along the pulley shaft 32 by a load from the nut 53, so that the taper coupling portion 52 is brought into close contact with a sufficient surface pressure. The pulley shaft 32 and the pulley boss 33 can be firmly integrated. As a result, the influence of minute play existing in the serration coupling portion 51 can be eliminated, and the generation of noise can be suppressed, and the steering feeling can be improved. When the nut 53 is tightened, the driving pulley 59 is movable in the axial direction, so that an excessive load is prevented from being applied to the driving pulley casing 12.
[0024]
  As apparent from FIGS. 2 and 3, the first and second operation cables 15 and 16 are inner cables made of synthetic resin outer tubes 15o and 16o and a metal wire slidably housed therein. 15i and 16i. Short cylindrical pins 54, 54 fixed to the ends of the two inner cables 15 i, 16 i are fitted into pin holes 34 a, 34 a formed on both end surfaces of the drive pulley body 34, and extend from the pins 54, 54. The inner cables 15 i and 16 i are wound in a direction approaching each other along one spiral groove 34 b formed on the outer periphery of the drive pulley body 34, and then drawn out in a direction perpendicular to the axis of the pulley shaft 32.
[0025]
  The front housing 23 is formed with two cylindrical connection portions 23b and 23b, and the boss portions 56a and 56a of the outer tube coupling members 56 and 56 are fixed inside thereof. Pipe portions 56b, 56b extending from the boss portions 56a, 56a to the outside of the connecting portions 23b, 23b are fitted to the outer circumferences of the outer tubes 15o, 16o, and the caulked portions 56c, 56c are caulked to end the outer tubes 15o, 16o. The part is fixed to the front housing 23. A guide bush 57 made of a synthetic resin with good sliding property is provided to prevent the inner cables 15i, 16i and the boss portions 56a, 56a from rubbing directly on the inner periphery of the boss portions 56a, 56a of the outer tube coupling members 56, 56. , 57 are held.
[0026]
  As shown in FIG. 7, the driven pulley casing 14 is composed of an upper housing 61 and a lower housing 62 connected by bolts 67 (see FIG. 8), and a cable guide housing 63 is interposed between the upper housing 61 and the lower housing 62. It is fixed with a bolt 64. The gear casing 19 coupled to the lower surface of the lower housing 62 includes an upper housing 121 and a lower housing 122 coupled by a plurality of bolts 120 (see FIG. 10).
[0027]
  A pulley shaft 70 is rotatably supported by a ball bearing 66 provided in the upper housing 61 of the driven pulley casing 14 and a ball bearing 68 provided in the upper housing 121 of the gear casing 19. The upper ball bearing 66 does not directly support the pulley shaft 70 but supports a pulley boss 71 fixed to the outer periphery of the pulley shaft 70. The ball bearing 66 provided in the upper housing 61 is prevented from being removed by a bag-like nut 72.
[0028]
  The upper end portion of the pulley shaft 70 and the pulley boss 71 are coupled at a serration coupling portion 74 and are coupled via a taper coupling portion 75 that tapers toward the upper end portion of the pulley shaft 70. A nut 76 is screwed into the upper end of the pulley shaft 70, and the pulley boss 71 is biased downward along the pulley shaft 70 by a load from the nut 76, so that the taper coupling portion 75 is brought into close contact with a sufficient surface pressure. By firmly integrating the pulley shaft 70 and the pulley boss 71, the influence of minute play existing in the serration coupling portion 74 can be eliminated, noise generation can be suppressed, and steering feeling can be improved. When the nut 76 is tightened, the driven pulley 60 is movable in the axial direction, so that an excessive load is prevented from being applied to the driven pulley casing 14 and the gear casing 19.
[0029]
  A synthetic resin driven pulley body 77 is integrally molded on the serration portion 71a on the outer periphery of the pulley boss 71 and is fixed to the end portions of the inner cables 15i, 16i of the first and second operation cables 15, 16. The pins 78 and 78 are fitted into pin holes 77 a and 77 a formed on both end surfaces of the driven pulley body 77, and the two inner cables 15 i and 16 i extending from the pins 78 and 78 are formed on the outer periphery of the driven pulley body 77. After being wound in a direction approaching each other along one spiral groove 77b, it will be described later.First rudder angle ratio variable mechanismIt is pulled out in a direction perpendicular to the axis of the pulley shaft 70 via M2. At this time, the outer tubes 15o and 16o of the first and second operation cables 15 and 16 are fixed to the cable guide housing 63 via the outer tube coupling member 79. The pulley boss 71 and the driven pulley body 77 constitute a driven pulley 60.
[0030]
  The drive pulley 59, the driven pulley 60, and the operation cables 15 and 16 constitute a steering angle transmission mechanism M1 that mechanically transmits the steering angle input to the steering wheel 11 to the steering gear box 13, and this steering angle transmission mechanism M1. Is the present inventionThe drive ofIt corresponds to the moving mechanism.
[0031]
  Next, based on FIGS.First rudder angle ratio variable mechanismExplain the structure of M2.
[0032]
  The upper shaft 102 supported by the upper housing 61 via the ball bearing 101 and the lower shaft 104 supported by the lower housing 62 via the ball bearing 103 are arranged coaxially and fixed to the lower end of the upper shaft 102. The intermediate portion of the cross-section crank-shaped upper arm 105 and the intermediate portion of the cross-section crank-shaped lower arm 106 fixed to the upper end of the lower shaft 104 are integrally connected by a U-shaped connecting member 107. One end portions of the upper arm 105 and the lower arm 106 facing each other are connected via a spherical bearing 108, and the first guide pulley 109 is supported by the spherical bearing 108 so as to be able to swing. The other ends of the upper arm 105 and the lower arm 106 facing each other are connected via a spherical bearing 110, and the second guide pulley 111 is supported by the spherical bearing 110 so as to be able to swing.
[0033]
  The inner cable 15i of the first operation cable 15 guided to the inside of the driven pulley casing 14 through the outer tube coupling member 79 is wound around the driven pulley 60 via the first guide pulley 109, and the outer tube coupling member The inner cable 16 i of the second operation cable 16 led to the inside of the driven pulley casing 14 through 79 is wound around the driven pulley 60 via the second guide pulley 111.
[0034]
  By forming the upper arm 105 and the lower arm 106 in a crank shape in cross section, the height of the first guide pulley 109 and the second guide pulley 111 can be stepped, and the connecting member 107 is formed in a U shape. Thus, interference with the first guide pulley 109 and the second guide pulley 111 can be avoided.
[0035]
  The upper shaft 102 is positioned in the axial direction with respect to the upper housing 61 via the ball bearing 101 by screwing a nut 112 into the upper end thereof. The upper portion of the nut 112 is covered with a bag-like nut 113 screwed into the upper housing 61.
[0036]
  The worm 115 provided on the output shaft 114 a of the actuator 114 supported by the upper housing 61 meshes with the worm wheel 116 fixed to the upper shaft 102. Therefore, the actuator 114 is driven to drive the worm 115 and the worm wheel 116. When the upper shaft 102 is rotated, the upper arm 105, the lower arm 106, the connecting member 107, and the lower shaft 104 connected to the upper shaft 102 rotate integrally.
[0037]
  Next, based on FIG. 7, FIG. 10 and FIG.SecondThe structure of the steering angle ratio variable mechanism M3 will be described.
[0038]
  A support member 124 is rotatably supported on the upper housing 121 of the gear casing 19 via a ball bearing 123, and the input shaft 125 is located at a position eccentric from the center of the support member 124 via a pair of ball bearings 126, 126. And is supported rotatably. The upper end of the input shaft 125 and the lower end of the pulley shaft 70 are connected via an Oldham coupling 127 that transmits the rotation of the pulley shaft 70 to the input shaft 125 while allowing the eccentricity of the input shaft 125 with respect to the pulley shaft 70. A cross-sectional groove type coupling 128 is integrally provided at the lower end of the input shaft 125.
[0039]
  An output shaft 129 is rotatably supported on the lower housing 122 of the gear casing 19 via a pair of ball bearings 130 and 131. The output shaft 129 is located coaxially with the pulley shaft 70, but is eccentric with respect to the input shaft 125. An outer periphery of a conical roller bearing 133 supported by an intermediate shaft 132 projecting to an eccentric position on the upper surface of the output shaft 129 is slidably supported on a lower surface of a coupling 128 provided on the input shaft 125 via a flat needle bearing 134. The slider 135 is supported. The lower end of the output shaft 129 is positioned by a nut 136 on a lower ball bearing 131 provided in the lower housing 122 of the gear casing 19, and the ball bearing 131 is prevented from being removed by a bag-shaped nut 137.
[0040]
  An actuator 139 is supported on the upper housing 121 of the gear casing 19 via a reduction gear casing 138, and a drive shaft 143 is supported on the upper housing 121 and the reduction gear casing 138 via three ball bearings 140, 141, 142. Is done. A worm 144 provided on the output shaft 139 a of the actuator 139 and a worm wheel 145 provided on the drive shaft 143 mesh with each other inside the reduction gear casing 138, and provided on the upper surface of the worm 146 provided on the drive shaft 143 and the support member 124. A sector type worm wheel 147 is engaged. Therefore, when the actuator 139 is driven, the rotation of the output shaft 139a is transmitted to the worm wheel 147 via the worm 144, the worm wheel 145, the drive shaft 143, and the worm 146, and the support member 124 supported by the ball bearing 123 is rotated. .
[0041]
  A rack 85 of the steering gear box 13 (see FIG. 1) meshes with a pinion 84 formed on the outer periphery of the output shaft 129, and the rack 85 is biased toward the pinion 84 at the meshing portion. That is, the slide member 86 is slidably fitted to the through hole 122a formed in the lower housing 122 via the O-ring 87, and is arranged between the spring seat 88 screwed to the through hole 122a and the slide member 86. The low friction member 90 provided on the slide member 86 contacts the back surface of the rack 85 by the elastic force of the coil spring 89. As a result, when the rotation of the output shaft 129 is transmitted to the rack 85 via the pinion 84 and the steered wheels WL and WR are steered, the rack 85 is free from backlash and deflection without receiving a large sliding resistance. It is prevented and can operate smoothly.
[0042]
  Next, an outline of the structure of the control system will be described based on FIG.
[0043]
  The control device 18First rudder angle ratio variable mechanismAn “active steering angle control unit” for controlling the operation of M2,SecondA “steering angle ratio variable control unit” that controls the operation of the steering angle ratio variable mechanism M3 and an “auxiliary steering torque control unit” that controls the operation of the auxiliary steering torque motor 20 are provided.
[0044]
  The “active steering angle control unit” includes a target active steering angle setting unit based on the steering angle of the steering wheel 11 detected by the steering angle sensor, the yaw rate of the vehicle detected by the yaw rate sensor, and the vehicle speed detected by the vehicle speed sensor. The target active steering angle is output, and the actuator control signal output unit is based on the deviation between the target active steering angle and the actual active steering angle.First rudder angle ratio variable mechanismA control signal for the M2 actuator 114 is output, and the actuator drive circuit drives the actuator 114 based on the control signal. The active steering angle generated by driving the actuator 114 is detected by an active steering angle sensor, and is subtracted from the target active steering angle output from the target active steering angle setting unit to form a feedback loop.
[0045]
  The “steering angle ratio variable control unit” outputs a target steering angle ratio based on the vehicle speed detected by the vehicle speed sensor, and based on a deviation between the target steering angle ratio and the actual steering angle ratio. The actuator control signal outputSecondA control signal for the actuator 139 of the steering angle ratio variable mechanism M3 is output, and the actuator drive circuit drives the actuator 139 based on this control signal. The steering angle ratio generated by driving the actuator 139 is detected by a steering angle ratio sensor, and is subtracted from the target steering angle ratio output by the target variable steering angle ratio setting unit to form a feedback loop.
[0046]
  The “auxiliary steering torque setting unit” outputs a target auxiliary steering torque from the target auxiliary steering torque setting unit based on the vehicle speed detected by the vehicle speed sensor and the steering torque detected by the steering torque sensor 41. The target current determining unit determines the target current of the auxiliary steering torque motor 20 based on the torque, and the output current control unit drives the auxiliary steering torque motor 20 via the auxiliary steering torque motor drive circuit.
[0047]
  When the failure state determination unit determines a failure in the steering system, the operation of the target active steering angle setting unit, the target steering angle ratio setting unit, and the target auxiliary steering torque setting unit is stopped according to the content of the failure.
[0048]
  Next, the operation of the embodiment of the present invention having the above configuration will be described.
[0049]
  First,First rudder angle ratio variable mechanismA case where M2 is held at the neutral position shown in FIG. 8 will be described.
[0050]
  The steering torque detected by the steering torque sensor 41 is input to the control device 18, and the control device 18 controls the operation of the auxiliary steering torque motor 20 based on the steering torque. That is, when the steering wheel 11 is operated to turn the vehicle, the steering torque is transmitted to the pulley shaft 32 via the steering shaft 29 and the torsion bar 38 as shown in FIG. 1. One inner cable 15i, 16i of the first and second operation cables 15, 16 is pulled and the other inner cable 15i, 16i is loosened, whereby the rotation of the drive pulley 59 is transmitted to the driven pulley 60. As a result, the pulley shaft 70 shown in FIG. 7 rotates, and the steering torque is transmitted to the steered wheels WL and WR via the pinion 84, the rack 85 and the tie rods 17L and 17R in the steering gear box 13.
[0051]
  When the steering torque is not input to the steering wheel 11, the torsion bar 38 is not twisted and the steering shaft 29 and the pulley shaft 32 are held in the same phase, and as shown in FIG. The guide pin 43 is in the center of the inclined groove 42a, and the slider 42 is held at the center position in the vertical direction. At this time, as shown in FIG. 5, the magnetic ring 44 provided on the slider 42 is at an intermediate position between the first secondary coil 49 and the second secondary coil 50, and the output voltages of both the secondary coils 49 and 50 are It becomes equal and it is detected that the steering torque is zero.
[0052]
  Further, when the steering wheel 11 is operated to the right and the steering torque in the direction of arrow a in FIG. Since a phase difference is generated between the slider 42 and the pulley shaft 32 that cannot rotate relative to the pulley shaft 32, the slider 42 having the inclined groove 42a pushed by the guide pin 43 of the steering shaft 29 slides upward. As a result, the output voltage of the upper first secondary coil 49 increases and the output voltage of the lower second secondary coil 50 decreases, and the steering torque in the right turning direction is detected based on the voltage difference. The Similarly, when the steering wheel 11 is operated in the left direction and a steering torque is input to the steering shaft 29 in the direction of arrow b in FIG. That is, since a phase difference is generated between the slider 42 and the slider 42, the slider 42 having the inclined groove 42 a pushed by the guide pin 43 of the steering shaft 29 slides downward. As a result, the output voltage of the upper first secondary coil 49 decreases and the output voltage of the lower second secondary coil 50 increases, and the steering torque in the left turning direction is detected based on the voltage difference. The
[0053]
  As described above, when the steering torque is detected by the steering torque sensor 41, the control device 18 drives the auxiliary steering torque motor 20 so that the steering torque detected by the steering torque sensor 41 is held at a predetermined value. To do. As a result, the torque of the auxiliary steering torque motor 20 is transmitted to the pulley shaft 70 via the worm 83 and the worm wheel 82, and the steering operation by the driver is assisted. By combining the steering torque sensor 41 having the differential transformer 45 and the auxiliary steering torque motor 20, the auxiliary steering torque motor 20 can be operated only by electrical control, and the structure of the control system is simplified. The
[0054]
  continue,First rudder angle ratio variable mechanismThe case where M2 operates will be described.
[0055]
  With the driver holding the steering wheel 11 in the neutral position, the actuator 114 is driven as shown in FIG.First rudder angle ratio variable mechanismWhen the upper arm 105 and the lower arm 106 of M2 are rotated in the direction of arrow a, the first guide pulley 109 approaches the driven pulley 60, so that the inner cable 15i of the first operation cable 15 is loosened, and the second guide pulley When 111 is separated from the driven pulley 60, the inner cable 16i of the second operation cable 16 is pulled. As a result, the separation point p1 (see FIG. 3) of the inner cable 15i of the first operation cable 15 with respect to the drive pulley 59, and the separation point p2 (see FIG. 10) of the inner cable 15i of the first operation cable 15 with respect to the driven pulley 60. The length of the inner cable 15i between the inner cable 16i and the inner cable 16i of the second operation cable 16 with respect to the drive pulley 59 is reduced, and the inner cable 16i with respect to the driven pulley 60 is reversed. Since the length of the inner cable 16i between the cable 16i and the separation point q2 (see FIG. 10) increases, the driven pulley 60 rotates in the arrow b direction.
[0056]
  That is, even if the steering wheel 11 is not operated, the upper arm 105 and the lower arm 106 are rotated by the actuator 114, whereby the driven pulley 60 is rotated in an arbitrary direction to steer the steered wheels WL and WR, and active steering. The function of the apparatus can be exhibited. Further, if the actuator 114 is operated simultaneously with the steering of the steering wheel 11 by the driver, the rotation of the driven pulley 60 by the driver's steering operation and the rotation of the driven pulley 60 by the operation of the actuator 114 are overlapped, so It is steered and can exhibit the function of variable rudder angle ratio.
[0057]
  As described above, since the rotation of the driven pulley 60 by the driver's steering operation and the rotation of the driven pulley 60 by the operation of the actuator 114 overlap, the actuator 114 is operated in a direction to assist the driver's steering operation, thereby improving the steering effect. It is possible to sharpen or slow down the steering effect by actuating the actuator 114 in a direction to cancel the steering operation of the driver. At this time, if the operation amount of the actuator 114 is controlled in accordance with the rotation angle of the steering wheel 11, the ratio of the rotation angle of the driven pulley 60 to the rotation angle of the drive pulley 59 can be set to a predetermined value.
[0058]
  For example, if the actuator 114 is operated when the steering wheel 11 is not operated, the ratio becomes infinite. When the steering wheel 11 is operated, the actuator 114 is set so as to completely cancel the operation. If operated, the ratio becomes 0, and if the actuator 114 is operated so that the driven pulley 60 rotates in the direction opposite to the operation direction of the steering wheel 11, the ratio becomes a negative value.
[0059]
  As described above, the drive pulley 59 interlocked with the steering wheel 11 and the driven pulley 60 interlocked with the steering gear box 13 are connected by the first and second operation cables 15 and 16 that can be freely bent. In addition, the degree of freedom in setting the position of the steering gear box 13 can be greatly increased, and the driven pulley 60 can be rotated with a simple structure in which the actuator 114 simply changes the positions of the first and second guide pulleys 109 and 111. Therefore, the function of the steering system can be greatly enhanced with only a slight increase in cost.
[0060]
  When the distance between the first and second guide pulleys 109 and 111 and the driven pulley 60 changes, or when the axial position of the cable disconnection points p2 and q2 of the driven pulley 60 changes as the driven pulley 60 rotates, Since the first and second guide pulleys 109 and 111 are inclined around the spherical bearings 108 and 110 according to the inclination direction of the inner cables 15i and 16i of the first and second operation cables 15 and 16, the inner cables 15i and 16i are It is possible to reliably prevent the first and second guide pulleys 109 and 111 from being detached and to enable smooth operation.
[0061]
  next,SecondThe operation of the steering angle ratio variable mechanism M3 will be described.
[0062]
  In FIG. 13, the rotation center of the input shaft 125 is A, the rotation center of the output shaft 129 is B, the action point of the intermediate shaft 132 is C, the dimension between BC is b, and the distance between the input shaft 125 and the output shaft 129. When the displacement amount (distance between AB) is a, the rotation angle of the input shaft 125 (steering angle of the steering wheel 11) is α, and the rotation angle of the output shaft 129 (rotation angle of the pinion 84) is β,
          b · sin β = (b · cos β−a) · tan α
Because
          α = tan^-1{(B · sin β / (b · cos β-a)}
It is represented by
[0063]
  When the input shaft 125 is rotated, the intermediate shaft 132 is crank-rotated around the axis of the output shaft 129 due to the engagement of the input shaft 125 with the slider 135 of the coupling 128. When the support member 124 is rotated here, the axial center position of the input shaft 125 changes within the range of FIGS. 10 and 11 due to the eccentric cam action of the support member 124. As a result, if the displacement amount a between the input shaft 125 and the output shaft 129 is appropriately set and the input shaft 125 and the output shaft 129 are decentered from each other, the rotation angles of the input shaft 125 and the output shaft 129 will not match. Become. In addition, the rate of change of the angle of the output shaft 129 when the input shaft 125 is rotated by equal angles gradually increases (see the thick line a1 and the thin line a2 in FIG. 14).
[0064]
  Here, by changing the deviation amount a between the input shaft 125 and the output shaft 129 continuously in the range of a2 to a0 (a2> a1> a0 = 0), the output shaft with respect to the rotation angle of the input shaft 125 is obtained. The ratio (β / α) of the rotation angle of 129, that is, the practical steering angle ratio can be continuously changed. When the deviation amount a of the input shaft 125 and the output shaft 129 is increased, the output with respect to the input angle α is increased. If the rate of change of the angle β is gradually increased and the displacement amount a of the input shaft 125 and the output shaft 129 is set to 0, the input angle α and the output angle β become equal as shown by a chain line in FIG.
[0065]
  When the change in the steering angle ratio is shifted to the a0 side in FIG. 14 in the low speed traveling area, the steering effect can be sharpened to facilitate the handling of the vehicle. Conversely, in the high speed traveling area, the a2 side in FIG. If it shifts to, the effectiveness of the steering can be made dull and the vehicle stability during high speed traveling can be improved.
[0066]
  As aboveFirst rudder angle ratio variable mechanismM2 andSecondBy combining the steering angle ratio variable mechanism M3, the following effects can be achieved.
[0067]
  That is, the steering operation of the driver transmitted through the steering angle transmission mechanism M1 including the driving pulley 59, the operation cables 15, 16 and the driven pulley 60,First rudder angle ratio variable mechanismThe steering angle output to the pulley shaft 70 by superimposing the steering operation by the actuation of the actuator M2 114,SecondSince the steering angle ratio variable mechanism M3 increases and outputs as the steering angle of the steered wheels WL and WR, in order to obtain the desired steered wheel steer angle,First rudder angle ratio variable mechanismThe steering angle superimposed by M2 can be set small. Therefore, ifFirst rudder angle ratio variable mechanismEven if M2 breaks down and steering angle superposition stops, in the first placeFirst rudder angle ratio variable mechanismSince the steering angle superimposed by M2 is small, the change of the steering torque received by the driver from the steering wheel 11 when a failure occurs can be reduced, and the steering angle of the steering wheel 11 and the steering wheels WL and WR are steered. The phase difference generated between the corners can be minimized.
[0068]
  MoreoverFirst rudder angle ratio variable mechanismIf M2 breaks down, continueSecondSince the steering angle ratio between the steering angle and the turning angle can be changed by the steering angle ratio variable mechanism M3, the steering angle ratio is changed to be small in the low vehicle speed range to make the steering easier, In the high vehicle speed region, the steering angle ratio can be set appropriately in accordance with the traveling state of the vehicle by controlling the vehicle driving stability by changing the steering angle ratio greatly to make the steering less effective.
[0069]
  AlsoSecondEven if the steering angle ratio variable mechanism M3 breaks down, the steering angle ratio immediately before the failure is inherited as it is, so that a change in steering torque is not transmitted from the steering wheel 11 to the driver. MoreSecondEven if the steering angle ratio variable mechanism M3 breaks downFirst rudder angle ratio variable mechanismIf M2 is functioning normally, there will be no phase difference between the neutral position of the steering wheel 11 and the neutral positions of the steering wheels WL and WR. MoreoverSecondEven if the steering angle ratio variable mechanism M3 breaks downFirst rudder angle ratio variable mechanismFailure due to superposition of steering angle by M2SecondThe steering angle ratio can be changed instead of the steering angle ratio variable mechanism M3.
[0070]
  As mentioned above, although the Example of this invention was explained in full detail, this invention can perform a various design change in the range which does not deviate from the summary.
[0071]
  For example, the steering angle transmission mechanism M1,First rudder angle ratio variable mechanismM2 andSecondThe steering angle ratio variable mechanism M3 is not limited to that of the embodiment, and any structure can be adopted as long as the function can be exhibited.
[0072]
  Moreover, although the cable type steering device is exemplified in the embodiment, the present invention can be applied to a steering device other than the cable type.
[0073]
【The invention's effect】
  As described above, according to the invention described in claim 1,By the first rudder angle ratio variable mechanismThe rudder angle ratio between the steered steering angle and the steered wheel turning angle can be changed.SecondIn order to obtain the target turning angle of the steered wheels by providing the steering angle ratio variable mechanismFirst rudder angle ratio variable mechanismThe steering angle to be superimposed by actuating the actuator can be set small. Therefore, by any chanceFirst rudder angle ratio variable mechanismIf the steering angle overlaps from the actuator due to failure,First rudder angle ratio variable mechanismSince the steering angle superimposed from the actuator of the steering wheel is small, not only can the change in steering torque received by the driver from the steering wheel at that time be reduced, but also between the steering angle of the steering wheel and the turning angle of the steering wheel. Deviations that occur can be minimized.
[0074]
  And even after the failure,SecondSince the steering angle ratio between the steering angle and the turning angle can be changed by the steering angle ratio variable mechanism, for example, in a low vehicle speed range, the steering angle ratio is changed to be small and the steering is sharpened to facilitate the handling of the vehicle. In the high vehicle speed range, it is possible to continue to set the appropriate steering angle ratio according to the running state of the vehicle, for example, by improving the running stability of the vehicle by greatly changing the steering angle ratio and reducing the steering effect. .
[0075]
  By any chanceSecondWhen the steering angle ratio variable mechanism fails, it is possible to eliminate the change in the steering torque that the driver receives from the steering wheel by inheriting the steering angle ratio immediately before the failure as it is. MoreSecondEven if the rudder angle ratio variable mechanism breaks downFirst rudder angle ratio variable mechanismAs long as is functioning normally, there will be no phase difference between the neutral position of the steering wheel and the neutral position of the steering wheel.First rudder angle ratio variable mechanismFailure due to superposition of steering angle bySecondThe steering angle ratio can be changed in place of the steering angle ratio variable mechanism.
[Brief description of the drawings]
FIG. 1 is an overall perspective view of a vehicle steering system.
FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG.
3 is a cross-sectional view taken along line 3-3 in FIG.
FIG. 4 is a perspective view of a steering torque sensor.
FIG. 5 is a circuit diagram of a differential transformer of a steering torque sensor.
FIG. 6 is an explanatory diagram of the operation of the steering torque sensor.
7 is an enlarged sectional view taken along line 7-7 in FIG.
8 is a cross-sectional view taken along line 8-8 in FIG.
9 is a sectional view taken along line 9-9 in FIG.
10 is a sectional view taken along line 10-10 in FIG.
FIG. 11SecondDisassembled perspective view of rudder angle ratio variable mechanism
12 is a diagram for explaining the operation corresponding to FIG.
FIG. 13SecondThe figure explaining the operation principle of a rudder angle ratio variable mechanism
FIG. 14SecondRudder angle ratio characteristic diagram of the rudder angle ratio variable mechanism
FIG. 15 is a block diagram of a control system.
[Explanation of symbols]
11 Steering wheel
13 Steering gearbox (steering wheel steering mechanism)
114 Actuator
M1 steering torque transmission mechanism(WDMechanism)
M2First rudder angle ratio variable mechanism
M3SecondSteering angle ratio variable mechanism
WL Steering wheel
WR steering wheel

Claims (2)

The steering angle of the steering wheel (11), a steering wheel (11) and of the mechanical coupling by the steering wheel (WL, WR) drive kinematic mechanism you transmitted to the steering mechanism (13) of the (M1),
A steering angle generated by the driving force of the actuator (114), the first steering ratio varying mechanism superimposed on the steering angle transmitted from drive kinematic mechanism (M1) to change the steering ratio and (M2),
Second steering for transmitting the steering angle and the steering wheel after superposition (WL, WR) steered wheel to change the steering angle ratio is the ratio of the steering angle of (WL, WR) on the steering mechanism (13) Angle ratio variable mechanism (M3),
A vehicle steering apparatus comprising: The vehicle steering apparatus according to claim 1, wherein the vehicle steering apparatus is a cable-type steering apparatus.

Images