JP4295056B2 - Automobile steering structure - Google Patents

Description

  The present invention relates to a steering structure for an automobile in which a tie rod is disposed in front of or behind a wheel center line, and the turning angles of inner and outer wheels during steering are substantially equal.

  In vehicles such as automobiles, in general, in order to obtain a linear steering characteristic, an Ackermann-type steering theory in which an inner wheel turning angle is larger than an outer wheel turning angle is designed. As a result, it is known that the tire can be smoothly turned with little skidding when the vehicle is steered, and that the tire is less worn. However, depending on the type of vehicle, there is a possibility that a predetermined turning angle of the inner and outer wheels adopting the Ackermann steering theory cannot be obtained due to various restrictions. Further, in order to reduce the turning radius of the automobile, it is necessary to increase the total angle of the inner and outer rings, and therefore it is necessary to increase the angle of the outer ring.

For this reason, there has been proposed a steering device having a parallel steering geometry in which the turning angles of the inner and outer wheels are substantially the same during steering. In this device, the line connecting the steering center of the inner and outer front tires and the operating point of the knuckle at the end of the tie rod is arranged substantially parallel to the longitudinal direction of the vehicle. The cutting angle of the outer ring can be increased. However, in the steering device having such a parallel steering geometry, a phenomenon that the rudder is involved near the maximum steering occurs at a low speed of 5 to 10 km / h, and the operator feels uncomfortable. That is, when the tire has a slip angle, if the maximum steering angle is large, a cornering force is generated in the tire, and a moment due to the wheel becomes a cutting torque, and a steering characteristic in which the steering torque is reduced appears. For this reason, an improved parallel steering structure has been proposed (see, for example, Patent Document 1 below).
JP 2002-87314 A (paragraph 0014)

  What was described in the said patent document 1 is demonstrated using FIG. In this vehicle steering structure, rack ends 109 are provided at both ends of a steering rack 108 in a gear case 107, and a tie rod 110 is slidably connected to the rack 108 in a direction perpendicular to the axis via the rack ends 109. Are connected by a tie rod 110, a relatively rotatable joint portion 113 is provided at the connecting portion of the tie rod 110 and the knuckle 114, and a line connecting the joint portion 113 and the center of rotation of the wheels 102, 102 is substantially in the vehicle longitudinal direction. As the steering device 101 turns the steering from the neutral state between the gear case 107 in the rack boot 115 provided at the opening end of the gear case 107 and the rack end 109, the elastic force on the side that becomes the inner ring is adopted. In which the steering device 101 returns to the neutral state It provided springs 121 for biasing. The spring 121 has a length approximately ½ to ３ of the stroke between the gear case 107 and the rack end 109 from the neutral state to the full steer.

  With such a configuration, a restoring force for returning to the neutral state is generated by the action of the spring 121 during steering, and a good steering feel is obtained in the vicinity of the maximum steering angle. However, a space equivalent to the maximum compression length of the spring is required, and the rack end 109 must be disposed outside. As a result, the toe change due to the suspension stroke becomes excessive, and it is difficult to obtain good steering stability performance. It was. Further, there is a risk that abnormal noise may be generated due to interference between the spring 121 and the rack 108 when traveling on a rough road or the like. Further, the front-wheel tire side slip angle in the vicinity of the maximum steering angle is not changed by the fitting of the spring 121, and the tire uneven wear is not eliminated. Further, when the road surface friction coefficient is low, the rudder is little involved even in the parallel steering structure, and the presence of the spring 121 makes the user feel uncomfortable.

  Therefore, the present invention solves such problems of the conventional parallel steering structure, does not require any special space, does not cause abnormal noise or changes in performance due to road surface conditions, has a small minimum radius, and unsprung mass. It is an object of the present invention to provide a steering device for a small automobile.

Therefore, the present invention provides a connection structure between a rack and a tie rod or a connection between a tie rod and a wheel in an automobile steering structure in which a tie rod is disposed in front of the wheel center line and the turning angle of the inner and outer wheels during steering is substantially equal. in at least one site, out of the ordinary range of use, when the set value or more tensile load in the vicinity of the maximum steering angle applied, are compressed rigidity lower underlying arising by receiving an inflection point load characterized by being arranged rigidity reduction member having a Wami characteristics. Further, according to the present invention, in a steering structure for an automobile in which the tie rod is disposed behind the wheel center line and the turning angle of the inner and outer wheels at the time of steering is substantially equal, the connection portion between the rack and the tie rod or the connection portion between the tie rod and the wheel. at least one of, out of the ordinary range of use, the compression load of more than a set value in the vicinity of the maximum steering angle when applied, is compressed stiffness low down by receiving the inflection point load is arising A rigidity reducing member having a deflection characteristic is provided. The present invention is characterized in that the rigidity reducing member is disposed between a rack and a rack end. In the invention, it is preferable that the rigidity reducing member is disposed between a ball seat at a rack end and a tie rod. Further, the present invention is characterized in that the rigidity reducing member is arranged between a ball seat and a ball stud for connecting the tie rod and the knuckle, and these are used as means for solving the problems. .

According to the present invention, in a steering structure for an automobile in which a tie rod is disposed in front of the wheel center line and the turning angle of the inner and outer wheels during steering is substantially equal, the connection portion between the rack and the tie rod or the connection between the tie rod and the wheel. in at least one site, out of the ordinary range of use, when the set value or more tensile load in the vicinity of the maximum steering angle applied, are compressed rigidity lower underlying arising by receiving an inflection point load by the fact that disposed reduction in rigidity member having Wami properties, the reduction in rigidity in the inner ring side acts more than the set value of tensile load in the tie rod in the vicinity of the maximum steering angle, weakened parallel steering tendency, Ackermann steering theory Good steer feel can be obtained. In addition, when the rigidity reducing member is disposed, a special space is not required, and the rack end is not greatly disposed outside, so that a change in toe due to the suspension stroke can be appropriately set. Moreover, since it depends on the tensile load of the tie rod during steering, there is no sense of incongruity due to the road surface condition. In addition, the minimum radius can be reduced by a relatively large actual steering angle near the maximum steering angle. Further, in general, in a vehicle in which the tie rod is disposed in front of the center of the wheel, the rim offset of the wheel is excessive and the tie rod end is placed outside in order to obtain the Ackermann geometry. However, according to the present invention, this is not necessary, the rim offset can be reduced, and the unsprung mass can be reduced.

In addition, in a steering structure for an automobile in which the tie rod is disposed behind the wheel center line and the turning angle of the inner and outer wheels at the time of steering is substantially equal, at least one of the connection portion between the rack and the tie rod or the connection portion between the tie rod and the wheel. crab, out of the ordinary range of use, when a compressive load equal to or higher than a set value in the vicinity of the maximum steering angle applied, Wami is compressed stiffness low down by receiving the inflection point load is arising properties Because of the rigidity reduction member, the actual steering angle increases due to the rigidity reduction on the inner ring side where a compression load greater than the set value acts on the tie rod near the maximum steering angle, and the parallel steering tendency weakens. Good steer feel by steering theory can be obtained.

  Further, when the rigidity reducing member is disposed between the rack and the rack end, the rigidity decreasing member can be disposed between the strong members to securely assemble each component. There is no fear that the rigidity-decreasing member that receives the load generates abnormal noise. In particular, regarding the arrangement of the rigidity reducing member on the pull side of the tie rod, since the arrangement of the rigidity reducing member hardly affects the distance between the rack and the rack end, no special space is required. The toe angle change due to the suspension stroke can be corrected without the need to dispose the rack end largely outside.

  Furthermore, when the rigidity reducing member is disposed between the ball seat and the tie rod at the rack end, the rigidity reducing member is disposed in the ball seat so that it is not exposed to dust. The chance of sound generation is reduced. Further, when the rigidity reducing member is disposed between the ball seat and the ball stud connecting the tie rod and the knuckle, the rigidity reducing member is disposed in the ball seat in the same manner as described above. The chance of abnormal noise is reduced. The rigidity reducing member is disposed between the rack and the rack end, between the ball seat at the rack end and the tie rod, or between the ball seat at the end of the tie rod and the ball stud. In this case, in addition to the effects of being disposed in each of those parts, the increase in the actual steering angle due to the winding moment on the inner ring side becomes large, and a better steer feel can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the steering structure of an automobile according to the present invention. FIG. 1 (A) is a schematic diagram of a steering device before steering, and FIG. 1 (B) is a diagram of FIG. 1 (A). FIG. 2 is a schematic view of a steering device in the vicinity of maximum steering. The basic structure of the automobile steering structure of the present invention is that the tie rods 1A and 1B are disposed in front of or behind the wheel center line L, and the steering angles of the inner and outer wheels TA and TB during steering are substantially equal. 2, between the members 2, 1 A so that the rigidity between the rack 2 and the tie rods 1 A, 1 B and the wheels TA, TB is reduced when a tensile load or compression load greater than the set value is applied to the tie rods 1 A, 1 B. The rigidity reducing member 8B is disposed in at least one of 1B and TA / TB.

  The first embodiment of FIGS. 1 and 2 will be described in detail below. As shown in FIG. 1A, the present embodiment is of a type in which tie rods 1A and 1B are disposed in front of a wheel center line (a line connecting the steering centers OA and OB of the wheel) L. . Accordingly, a gear case G that houses the rack 2 in which the rotation of the steering shaft is converted into a linear motion is also disposed in front of the wheel center line L. The left and right tie rods 1A and 1B respectively connected to the ends of the rack 2 housed in the gear case G are connected to the left and right wheels (tires) TA and TB knuckles NA and NB at operating points PA and PB. . As shown in FIG. 12, in the case of parallel steering large turning, a positive skid angle is generated in the outer wheel and a negative skid angle is generated in the inner wheel. Further, the tire ground contact point moves to the front of the vehicle on the outer ring and to the rear of the vehicle on the inner ring. Therefore, a large tensile force is generated on the tie rod 1A and a small tensile force is generated on the tie rod 1B by the action of the tire cornering force and the self-aligning torque.

  FIG. 1B is an enlarged cross-sectional view of the rack 2 and the tie rod 1B in the portion A of FIG. 1A, and shows a characteristic configuration of the present invention. In the illustrated example, the rack 2 and the tie rod 1B are coupled via a rack end 3B. The same applies to the connecting portion (rack end 3A: not shown) between the left rack 2 and the tie rod 1A, and the description thereof is omitted. The rack end 3B is formed with a ball seat 6B on the tie rod 1B side and an end 5B on the rack 2 side. A ball portion at the inner end of the tie rod 1B is coupled to the ball seat 6B via a ball seat 7B, and is coupled to the end 5B via a stepped bolt 4B that is screwed to the rack 2 from the tie rod 1B side. The Between the head of the stepped bolt 4B and the end 5B of the rack end 3B, a wave washer 8B, which is a rigidity reducing member, is interposed via a washer 9B. Accordingly, since the end portion 5B of the rack end 3B and the connecting surface of the rack 2 are in direct contact with each other, the tensile load is equal to the spring characteristics and related dimensions of the wave washer 8B regardless of the arrangement of the wave washer 8B which is a rigidity reducing member. In the range below the predetermined load that is set, the dimension between the rack 2 and the tie rod 1B does not increase.

  With this configuration, as shown in FIG. 2, on the inner ring side, if a tensile load greater than the set value acts between the members of the rack 2, the rack end 3B, and the tie rod 1 near the maximum steering angle, the step is stepped. The wave washer 8B interposed between the head of the bolt 4B and the end 5B of the rack end 3B is compressed and crushed, and the rigidity is lowered. As a result, the inner wheel is further cut, the steering angle difference between the inner and outer wheels is increased, the parallel steering tendency is weakened, and a good steering feel is obtained. FIG. 5 shows the steering load-deflection characteristics when the rigidity reducing member is interposed. Outside the general range of use, an inflection point load greater than the set value is received near the maximum steering angle, and the rigidity-reducing member is compressed on the inner ring side, causing a decrease in rigidity. FIG. 6 shows changes in the tie rod axial force of the inner and outer rings.

  FIG. 3 shows a second embodiment of the steering structure of an automobile according to the present invention, in which a wave washer 8B, which is a member for reducing rigidity, is disposed between a ball seat 6B of a rack end 3B and a tie rod 1B. It is. The ball portion of the tie rod 1B is accommodated in the ball seat 6B of the rack end 3B via the ball seat 7B, and a wave that is a rigidity reducing member is provided between the retainer 10B and the flange portion 17B of the opening of the ball seat 6B. A washer 8B is interposed. Since the rack 2 on the outer ring side is pulled and pulled during steering and the wave washer 8B is compressed in the vicinity of the maximum steering angle, the inner ring is cut and the steering angle between the inner and outer wheels is set. By increasing the difference, the parallel steering tendency is weakened, and a good steering feel can be obtained. In addition, the rigidity reducing member is disposed in the ball seat 6B and is not exposed to dust, and the chance of occurrence of abnormal noise is reduced.

  FIG. 4 shows a third embodiment of the steering structure for an automobile according to the present invention. A wave washer 13B as a rigidity reducing member is disposed between a ball seat 16B at the end of the tie rod 1B and a ball stud 11B. Is. A ball stud 11B positioned at an operating point PB, which is a connecting portion between the outer end portion of the tie rod 1B and the wheel knuckle NB (see FIG. 1A), places the ball seat 12B in the ball seat 16B at the end of the tie rod 1B. Is housed through. A wave washer 13B, which is a rigidity reducing member, is interposed between the ball seat 12B and the outer portion of the ball seat 16B and the retainer 14B disposed on the ball seat 12B side. 15B is a boot. Since the tie rod 1B on the inner ring side is pulled and pulled during steering and the wave washer 8B is compressed near the maximum steering angle, the inner ring is cut and the steering angle between the inner and outer wheels is set. By increasing the difference, the parallel steering tendency is weakened, and a good steering feel can be obtained. In addition, the rigidity reducing member is disposed in the ball seat 6B and is not exposed to dust, and the chance of occurrence of abnormal noise is reduced.

  7 and 8 show a fourth embodiment of the steering structure of an automobile according to the present invention. As shown in FIG. 7A, the tie rods 1A and 1B and the gear case G are centered on the wheel. It is of a type arranged behind the line L. The left and right tie rods 1A and 1B respectively connected to the ends of the rack 2 housed in the gear case G are connected to the left and right wheels (tires) TA and TB knuckles NA and NB at operating points PA and PB. .

    FIG. 7B is an enlarged cross-sectional view of a connecting portion between the rack 2 and the tie rod 1B in the portion A of FIG. 7A, and the rack 2 and the tie rod 1B are connected via a rack end 3B. The rack end 3B is formed with a ball seat 6B on the tie rod 1B side and an end 5B on the rack 2 side. A ball portion at the inner end of the tie rod 1B is connected to the ball seat 6B via a ball seat 7B, and the end 5B is connected to a tie rod 2 via a stepped bolt 4B that is screwed from the tie rod 1B side. The A wave washer 8B, which is a rigidity reducing member, is interposed between the end 5B of the rack end 3B and the end surface of the rack 2. Therefore, in this embodiment, the dimension between the rack 2 and the tie rod 1B is slightly increased by the amount of the wave washer 8B.

  With this configuration, as shown in FIG. 8, when a pressing load exceeding the set value acts between the members of the rack 2, the rack end 3B, and the tie rod 1 near the maximum steering angle, the end surface of the rack 2 becomes the rack The wave washer 8B interposed between the end 3B and the end 5B is compressed and crushed, and the rigidity is lowered. As a result, the steering angle is cut and increased on the inner wheel side, the steering angle difference between the inner and outer wheels is increased, the parallel steering tendency is weakened, and a good steering feel is obtained.

  FIG. 9 shows a fifth embodiment of the steering structure for an automobile according to the present invention, in which a wave washer 8B as a rigidity reducing member is disposed between a ball seat 6B of the rack end 3B and a tie rod 1B. It is. The ball portion of the tie rod 1B is accommodated in the ball seat 6B of the rack end 3B via the ball seat 7B, and the rigidity is between the retainer 10B on the ball seat 7B side and the inner side on the rack 2 side of the ball seat 6B. A wave washer 8B as a lowering member is interposed. Since it is configured in this manner, the inner wheel is cut, the steering angle difference between the inner and outer wheels is increased, the parallel steering tendency is weakened, and a good steering feel is obtained. In addition, the rigidity reducing member is disposed in the ball seat 6B and is not exposed to dust, and the chance of occurrence of abnormal noise is reduced.

  FIG. 10 shows a sixth embodiment of the steering structure for an automobile according to the present invention. A wave washer 13B as a rigidity reducing member is disposed between a ball seat 16B at the end of the tie rod 1B and a ball stud 11B. Is. A ball stud 11B positioned at an operating point PB, which is a connecting portion between the outer end portion of the tie rod 1B and the wheel knuckle NB (see FIG. 7A), places the ball seat 12B in the ball seat 16B at the end of the tie rod 1B. Is housed through. A wave washer 13B, which is a rigidity reducing member, is interposed between the ball seat 12B and the inner portion of the ball seat 16B on the tie rod 1B side and the retainer 14B disposed on the ball seat 12B side. . 15B is a boot. Since it is configured in this way, the wave washer 8B on the inner ring side is compressed near the maximum steering angle during steering, so the inner ring is cut and the steering angle difference between the inner and outer wheels is increased, leading to a parallel steer tendency. Weakens and a good steer feel is obtained. In addition, the rigidity reducing member is disposed in the ball seat 6B and is not exposed to dust, and the chance of occurrence of abnormal noise is reduced.

  As described above, each embodiment of the present invention has been described. However, within the scope of the present invention, a knuckle, a tie rod, and a rack end (when the rack end is integral with the rack, separate, or separate) In addition to connecting via stepped bolts, it is possible to adopt a configuration in which the end of the rack is extended as a small diameter part to form a screw part, the end of the rack is penetrated and secured with a nut), the rack, and the gear case Shape, type, connection form of rack end and tie rod (in addition to the ball seat and retainer in the ball seat, connection form through appropriate members can be adopted), connection of tie rod and knuckle through ball stud Form (in addition to the ball seat and retainer in the ball seat, a connection form through an appropriate member can be adopted), the type of rigidity-reducing member (wave , Disc spring, single layer, multi-layer, etc.), placement position (between rack and rack end, between rack seat ball seat and tie rod, between tie rod end ball seat and ball stud, In addition, it is possible to appropriately select the deformation load setting value of the rigidity lowering member, etc. between appropriate members capable of relative displacement).

FIG. 1A is a schematic diagram of a steering apparatus before steering, and FIG. 1B is an enlarged view of a main part of A part of FIG. 1A. It is sectional drawing. It is a schematic diagram of the steering device near the maximum steering. FIG. 2 shows a second embodiment of the steering structure for an automobile according to the present invention, and is an enlarged cross-sectional view of a main part corresponding to part A in FIG. FIG. 3 shows a third embodiment of the automobile steering structure according to the present invention, and is an enlarged cross-sectional view of a main part corresponding to part B of FIG. FIG. 6 is a steering load-deflection characteristic graph when a rigidity reducing member is interposed. It is an axial force-rudder angle characteristic figure showing change of tie rod axial force of an inner and outer ring. FIG. 7A shows a fourth embodiment of the steering structure of an automobile according to the present invention, FIG. 7A is a schematic view of a steering device before steering, and FIG. It is sectional drawing. It is a schematic diagram of the steering device near the maximum steering. FIG. 9 shows a fifth embodiment of the steering structure for an automobile according to the present invention, and is an enlarged cross-sectional view of a main part corresponding to part A in FIG. FIG. 9 shows a sixth embodiment of the automobile steering structure according to the present invention and is an enlarged cross-sectional view of a main part corresponding to part B of FIG. It is explanatory drawing of the conventional steering structure for vehicles. It is explanatory drawing of tie-rod axial force generation | occurrence | production in case there is little inner / outer-wheel steering angle difference.

Explanation of symbols

1A Left tie rod 1B Right tie rod 2 Rack 3B Rack end 4B Stepped bolt 5B End 6B Ball seat 7B Ball seat 8B Wave washer (Rigidity reducing member)
9B Washer 10B Retainer 11B Ball stud 12B Ball seat 13B Wave washer (Rigidity reducing member)
14B Retainer 15B Boot 16B Ball seat 17B Flange L Wheel center line G Gear case OA, OB Steering center PA, PB Operating point NA, NB Knuckle TA, TB Front tire

Claims (5)

In a steering structure of an automobile in which the tie rod is disposed in front of the wheel center line and the turning angle of the inner and outer wheels at the time of steering is approximately equal, at least one of the connection part between the rack and the tie rod or the connection part between the tie rod and the wheel It has out of the ordinary range of use, when the set value or more tensile load in the vicinity of the maximum steering angle applied, the Wami properties is compressed rigidity lower bottom is arising by receiving an inflection point load A steering structure for an automobile, characterized in that a rigidity reducing member is provided. In a steering structure of an automobile in which the tie rod is disposed behind the wheel center line and the turning angle of the inner and outer wheels at the time of steering is approximately equal, at least one of the connection part between the rack and the tie rod or the connection part between the tie rod and the wheel It has out of the ordinary range of use, when a compressive load equal to or higher than a set value in the vicinity of the maximum steering angle applied, the Wami properties is compressed rigidity lower bottom is arising by receiving an inflection point load A steering structure for an automobile, characterized in that a rigidity reducing member is provided. The automobile steering structure according to claim 1, wherein the rigidity reducing member is disposed between a rack and a rack end. 4. The automobile steering structure according to claim 1, wherein the rigidity reducing member is disposed between a ball seat at a rack end and a tie rod. 5. The steering structure for an automobile according to any one of claims 1 to 4, wherein the rigidity reducing member is disposed between a ball seat and a ball stud connecting the tie rod and the knuckle.

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