JPS624679A - 4-wheel steering apparatus for vehicle - Google Patents
4-wheel steering apparatus for vehicleInfo
- Publication number
- JPS624679A JPS624679A JP14344385A JP14344385A JPS624679A JP S624679 A JPS624679 A JP S624679A JP 14344385 A JP14344385 A JP 14344385A JP 14344385 A JP14344385 A JP 14344385A JP S624679 A JPS624679 A JP S624679A
- Authority
- JP
- Japan
- Prior art keywords
- steering
- road
- friction coefficient
- steering ratio
- characteristic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D7/00—Steering linkage; Stub axles or their mountings
- B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
- B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
- B62D7/15—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels
- B62D7/1518—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels comprising a mechanical interconnecting system between the steering control means of the different axles
- B62D7/1536—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels comprising a mechanical interconnecting system between the steering control means of the different axles provided with hydraulic assistance
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野〉
本発明は、前輪の転舵に応じて後輪をも転舵するように
した車両の４輪操舵装置に関し、詳しくは、低摩擦係数
路（低μ路）走行時の走行安定性の向上対策に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel steering system for a vehicle that steers the rear wheels in accordance with the steering of the front wheels. Concerning measures to improve running stability when driving (on low μ roads).
（従来の技術）
従来より、この種の車両の４輪操舵装置として、例えば
特開昭５９−７７９６８号公報に開示されるように、前
輪を転舵する前輪転舵機構と、後輪を転舵する後輪転舵
機構とを備え、前輪の転舵角および重速に応じて後輪の
転舵角を変化させ、低車速時では前輪と後輪とを逆位相
に、高車速時では同位相にすることにより、車輪の横す
べりを防止して走行安定性を向上させるとともに、低車
速時での小廻り性の向上を図り得るようにしたものは知
られている。(Prior Art) Conventionally, as a four-wheel steering system for this type of vehicle, a front wheel steering mechanism that steers the front wheels and a front wheel steering mechanism that steers the rear wheels have been used, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-77968. It is equipped with a rear wheel steering mechanism that changes the steering angle of the rear wheels according to the steering angle of the front wheels and the vehicle speed, so that the front and rear wheels are in opposite phases at low vehicle speeds and the same at high vehicle speeds. It is known that by adjusting the phasing, it is possible to prevent wheels from skidding and improve driving stability, as well as to improve maneuverability at low vehicle speeds.
（発明が解決しようとする問題点）
しかるに、雨天時や未舗装路走行時の如き低μ路走行時
には、路面に対する車輪の横方向グリップ力が低下する
ため、略天時等の通常走行時と同様に後輪が転舵される
と、高車速時・低車速時の別を問わず車輪が横すべりを
生じ易くなり、走行安定性が損われるという問題がある
。(Problem to be Solved by the Invention) However, when driving on a low μ road such as in rainy weather or when driving on an unpaved road, the lateral grip force of the wheels on the road surface decreases, so Similarly, when the rear wheels are steered, the wheels tend to skid regardless of whether the vehicle is running at high or low speeds, and there is a problem in that running stability is impaired.
本発明はかかる点に鑑みてなされたものであり、その目
的とするところは、路面の摩擦係数の状況に応じて前輪
に対する後輪の転舵比を適宜変更することにより、通常
走行時は勿論のこと、低μ路走行時においても車輪の横
すべりを可及的に防止して、走行安定性を確保せんとす
るものである。The present invention has been made in view of the above points, and its purpose is to appropriately change the steering ratio of the rear wheels to the front wheels according to the friction coefficient of the road surface. The purpose is to prevent wheels from slipping as much as possible even when driving on low-μ roads to ensure driving stability.
（問題点を解決するための手段）
上記目的を達成するため、本発明の解決手段は、ハンド
ル操舵に応じて前輪を転舵する前輪転舵機構と、この前
輪の転舵に応じて後輪を転舵する後輪転舵ｍ構とを備え
てなる車両の４輪操舵装置において、上記後輪転舵機構
に対し、別途、前輪転舵角に対する後輪転舵角の比を所
定の転舵比特性に従って可変とする転舵比可変手段と、
路面の摩擦係数を検出する検出手段と、該検出手段の出
力信号に基づいて路面の摩擦係数の状態を判断し、路面
の摩擦係数が低い時には高い時に比べて同位相側に補正
された特性で後輪を転舵するよう転舵比を補正する補正
手段とを設ける構成としたものである。(Means for Solving the Problems) In order to achieve the above object, the present invention provides a front wheel steering mechanism that steers the front wheels in response to steering wheel steering, and a rear wheel steering mechanism that steers the front wheels in response to steering of the steering wheel. In a four-wheel steering system for a vehicle comprising a rear wheel steering mechanism that steers a rear wheel, the rear wheel steering mechanism is provided with a predetermined steering ratio characteristic that determines the ratio of the rear wheel steering angle to the front wheel steering angle. a steering ratio variable means for varying the steering ratio according to;
A detection means for detecting the coefficient of friction of the road surface, and a state of the friction coefficient of the road surface is determined based on the output signal of the detection means, and when the friction coefficient of the road surface is low, the characteristics are corrected to the same phase side compared to when it is high. This configuration includes a correction means for correcting the steering ratio so as to steer the rear wheels.
（作用）
上記の構成により、本発明では、路面の摩擦係数が高い
晴天時等の通常走行時には、転舵比可変手段の所定の転
舵比特性でもって後輪が転舵されて、車両の走行安定性
が良好に確保される。(Function) With the above configuration, in the present invention, during normal driving such as on a clear day when the coefficient of friction of the road surface is high, the rear wheels are steered with the predetermined steering ratio characteristic of the steering ratio variable means, so that the vehicle Good running stability is ensured.
また、低μ路走行時には、上記転舵比可変手段の所定の
転舵比特性が補正手段により同位相側に補正されるので
、路面に対する車輪の横方向グリップ力が増大して、走
行安定性が一確保されることになる。Furthermore, when driving on a low μ road, the predetermined steering ratio characteristic of the steering ratio variable means is corrected to the same phase side by the correction means, so that the lateral grip force of the wheels on the road surface increases, resulting in improved running stability. One will be secured.
（実施例） 以下、本発明の実施例を図面に基づいて説明する。(Example) Embodiments of the present invention will be described below based on the drawings.
第１図は本発明の第１実施例に係−る車両の４輪操舵装
置の全体構成を示し、１は左右の前輪２ｍ。FIG. 1 shows the overall configuration of a four-wheel steering system for a vehicle according to a first embodiment of the present invention, where 1 indicates 2 m of left and right front wheels.
２Ｒを転舵する前輪転舵機構であって、該前輪転舵機構
１は、ステアリングハンドル３と、該ステアリングハン
ドル３の回転運動を直線運動に変換するラック＆とニオ
ン機構４と、該ラック＆ビニオン機構４の作動を前輪２
Ｌ、２Ｒに伝達して、これらを左右に転舵させる左右の
タイロッド５゜５およびナックルアーム６．６とからな
る。2R, the front wheel steering mechanism 1 includes a steering handle 3, a rack &nion mechanism 4 that converts rotational motion of the steering handle 3 into linear motion, and a rack & The operation of the binion mechanism 4 is controlled by the front wheel 2.
It consists of left and right tie rods 5.5 and knuckle arms 6.6 which transmit signals to L and 2R and steer them left and right.
７は左右の後輪８Ｌ、８Ｒを転舵する後輪転舵機構であ
って、該後輪転舵機構７は、両端が左右の後輪８ｍ、８
Ｒにタイロッド９．９およびナックルアーム１０．１０
を介して連結された車幅方向に延びる後輪操作ロッド１
１を備えている。該後輪操作ロッド１１にはラック１２
が形成され、該ラック１２に噛合するビニオン１３がパ
ルスモータ１４により一対の傘歯車１５．１６およびピ
ニオン軸１７を介して回転されることにより、上記パル
スモータ１４の回転方向および回転量に対応して後輪８
Ｌ、８Ｒが左右に転舵されるように構成されている。Reference numeral 7 denotes a rear wheel steering mechanism for steering left and right rear wheels 8L, 8R, and both ends of the rear wheel steering mechanism 7 steer left and right rear wheels 8L, 8R.
Tie rod 9.9 and knuckle arm 10.10 on R
Rear wheel operating rod 1 extending in the vehicle width direction and connected via
1. A rack 12 is attached to the rear wheel operating rod 11.
is formed, and the pinion 13 meshing with the rack 12 is rotated by the pulse motor 14 via a pair of bevel gears 15, 16 and the pinion shaft 17, thereby corresponding to the direction and amount of rotation of the pulse motor 14. rear wheel 8
The L and 8R are configured to be steered left and right.
また、上記後輪操作ロッド１１には、該ロッド１１を操
作ロッドとするパワーシリンダ１８が接続されている。Further, a power cylinder 18 is connected to the rear wheel operating rod 11, using the rod 11 as an operating rod.
該パワーシリンダ１８は、後輪操作ロッド１１に固着し
たピストン１８ａにより車幅方向に仕切られた左転用油
圧室１８ｂおよび右転用油圧室１８ｃを有しているとと
もに、該８油圧室１８ｂ、１８ｃはそれぞれ油圧通路１
９ａ。The power cylinder 18 has a left-turning hydraulic chamber 18b and a right-turning hydraulic chamber 18c partitioned in the vehicle width direction by a piston 18a fixed to the rear wheel operating rod 11, and the eight hydraulic chambers 18b, 18c are Hydraulic passage 1 each
9a.
１９ｂを介して、パワーシリンダ１８への油供給方向お
よび油圧を制御するコントロールバルブ２０に連通し、
該コントロールパルプ２０には油供給通路２１および油
戻し路２２を介して油圧ポンプ２３が接続されており、
該油圧ポンプ２３はモータ２４によって回転駆動される
。上記コントロールバルブ２０は、ピニオン軸１７の回
転方向を検出して後輪８Ｌ、８Ｒの左方向転舵（図中反
時計方向への転舵）時には油供給通路２１を左転用油圧
室１８ｂに連通しかつ右転用油圧室１８ｃを油戻し路２
２に連通する一方、後輪８１．８Ｈの右方向転舵（図中
時計方向への転舵）時には上記とは逆の連通状態とし、
同時に油圧ポンプ２３からの油圧をピニオン軸１７の回
転力に応じた圧力に減圧するものであり、パルスモータ
１４により傘歯車１５，１６、ピニオン軸１７、ビニオ
ン１３およびラック１２を介して後輪操作ロッド１１が
軸方向（車幅方向）に移動されるときには、パワーシリ
ンダ１８への圧油供給により上記後輪操作ロッド１１の
移動を助勢するようにしている。19b, communicates with a control valve 20 that controls the oil supply direction and oil pressure to the power cylinder 18,
A hydraulic pump 23 is connected to the control pulp 20 via an oil supply passage 21 and an oil return passage 22.
The hydraulic pump 23 is rotationally driven by a motor 24. The control valve 20 detects the rotational direction of the pinion shaft 17 and communicates the oil supply passage 21 with the left rotation hydraulic chamber 18b when the rear wheels 8L and 8R are steered to the left (counterclockwise in the figure). In addition, the right diversion hydraulic chamber 18c is connected to the oil return path 2.
2, while when the rear wheel 81.8H is steered to the right (clockwise in the figure), the communication state is opposite to the above,
At the same time, the hydraulic pressure from the hydraulic pump 23 is reduced to a pressure corresponding to the rotational force of the pinion shaft 17, and the rear wheel is operated by the pulse motor 14 via the bevel gears 15, 16, pinion shaft 17, pinion 13, and rack 12. When the rod 11 is moved in the axial direction (vehicle width direction), pressure oil is supplied to the power cylinder 18 to assist the movement of the rear wheel operating rod 11.
そして、上記パルスモータ１４および油圧ポンプ２３の
駆動用モータ２４は、後輪転舵機構７の制御部たるコン
トローラ２５から出力される制御信号によって作動制御
される。上記コントローラ２５には、前輪転舵機１１に
おけるステアリングハンドル３の操舵量等から前輪転舵
角を検出する舵角センサ２６からの舵角信号と、車速を
検出する車速センサ２７からの重速信号と、路面の摩擦
係数を検出する検出手段としての路面摩擦係数センサ２
８からの路面摩擦係数信号とがそれぞれ入力されている
とともに、バッテリ電源２９が接続されている。尚、上
記路面摩擦係数センサ２８は、絶対車速く実車速）と、
前輪２Ｌ、２Ｈの回転数に基づくメータ車速との比較に
より、路面摩擦係数を算出するものである。The operation of the pulse motor 14 and the drive motor 24 of the hydraulic pump 23 is controlled by a control signal output from a controller 25 that is a control section of the rear wheel steering mechanism 7. The controller 25 receives a steering angle signal from a steering angle sensor 26 that detects the front wheel steering angle from the steering amount of the steering wheel 3 in the front wheel steering device 11, and a heavy speed signal from a vehicle speed sensor 27 that detects the vehicle speed. and a road surface friction coefficient sensor 2 as a detection means for detecting the friction coefficient of the road surface.
The road surface friction coefficient signals from 8 and 8 are respectively inputted, and a battery power source 29 is also connected. Note that the road surface friction coefficient sensor 28 detects absolute vehicle speed (actual vehicle speed),
The road surface friction coefficient is calculated by comparing the rotation speed of the front wheels 2L and 2H with the meter vehicle speed.
上記コントローラ２５の内部には、第２図に示すように
、車速に対する前輪と後輪の転舵比特性を第３図に示す
如く２種類記憶する特性記憶部３０と、舵角センサ２６
からの舵角信号および車速センサ２７からの車速信号を
受け、上記特性記憶部３０に記憶された転舵比特性から
、前輪転舵角と車速とに対応する後輪の目標転舵角を演
算する目標転舵角演算部３１と、該目標転舵角演算部３
１で演算された目標転舵角に対応するパルス信号を出力
するパルスジェネレータ３２と、該パルスジェネレータ
３２からのパルス信号を受けてパルスモータ１４および
油圧ポンプ２３の駆動用モータ２４を駆動する駆動パル
ス信号に変換するドライバ３３とを備え、これらによっ
て前輪転舵角に対する後輪転舵角の比〈転舵比〉を所定
の転舵比特性に従って可変として後輪転舵角が目標転舵
角となるようにバルースモータ１４および油圧ポンプ２
３の駆動用モータ２４を制御する転舵比可変手段３４が
構成されている。Inside the controller 25, as shown in FIG. 2, there is a characteristic storage section 30 that stores two types of steering ratio characteristics of front wheels and rear wheels with respect to vehicle speed as shown in FIG. 3, and a steering angle sensor 26.
receives a steering angle signal from the vehicle speed sensor 27 and a vehicle speed signal from the vehicle speed sensor 27, and calculates a target steering angle of the rear wheels corresponding to the front wheel steering angle and the vehicle speed from the steering ratio characteristic stored in the characteristic storage section 30. a target steering angle calculation section 31 for calculating the target steering angle;
a pulse generator 32 that outputs a pulse signal corresponding to the target steering angle calculated in step 1; and a drive pulse that drives the pulse motor 14 and the drive motor 24 of the hydraulic pump 23 in response to the pulse signal from the pulse generator 32. and a driver 33 for converting into a signal, by which the ratio of the rear wheel turning angle to the front wheel turning angle (steering ratio) is varied according to a predetermined steering ratio characteristic so that the rear wheel turning angle becomes the target turning angle. a ballous motor 14 and a hydraulic pump 2
A steering ratio variable means 34 for controlling the drive motor 24 of No. 3 is configured.
ここに、上記特性記憶部３０に予め記憶されている転舵
比特性は、第３図に示すように、晴天時などの路面の摩
擦係数が高い状態の通常走行時用の転舵比特性Ａと、雨
天時や未舗装路などの低μ路走行時用の転舵比特性Ｂの
２種類であって、この両転舵比特性Ａ、Ｂは、基本的に
は、車速が低速から高速に上昇するに従って転舵比ｋが
負方向の一逆位相〈前後輪が逆方向に転舵される状態）
で大きな値から零に近づくように移行し、中速域にて転
舵比軟が正方向の同位相（前後輪が同方向に転舵される
状態）に変わり、高速域では同位相で転舵比ｋが大きく
なるように設定されている。そして、上記両転舵比特性
Ａ、Ｂのうち、低μ路走行時用の転舵比特性Ｂは、通常
走行時の転舵比特性Ａに比べて低速から高速までの全車
速域に亘って同位相側にずれた傾向にあり、転舵比ｋが
負方向の逆位相の値となる低速域ではその転舵比ｋが零
に近づきあるいは正方向の同位相に変化し、転舵比ｋが
正方向の同位相の値となる中速域ないし高速域ではその
転舵比ｋがより大きな値に設定されている。Here, as shown in FIG. 3, the steering ratio characteristic stored in advance in the characteristic storage section 30 is a steering ratio characteristic A for normal driving when the coefficient of friction of the road surface is high, such as on a clear day. and steering ratio characteristic B for driving on low μ roads such as rainy days and unpaved roads.Both steering ratio characteristics A and B are basically used when the vehicle speed is from low to high. As the steering ratio k increases, the steering ratio k becomes a reverse phase in the negative direction (a state in which the front and rear wheels are steered in opposite directions).
The steering ratio changes from a large value to close to zero in the medium speed range, and in the medium speed range, the steering ratio changes to the same phase in the positive direction (the front and rear wheels are steered in the same direction), and in the high speed range, the steering ratio changes to the same phase in the same direction. The steering ratio k is set to be large. Of the above-mentioned steering ratio characteristics A and B, the steering ratio characteristic B for driving on a low μ road is more stable over the entire vehicle speed range from low to high speeds than the steering ratio characteristic A for normal driving. In the low speed range where the steering ratio k has a value of opposite phase in the negative direction, the steering ratio k approaches zero or changes to the same phase in the positive direction, and the steering ratio The steering ratio k is set to a larger value in the medium speed range or high speed range where k has the same phase value in the positive direction.
そして、上記コントローラ２５の内部には、さらに、路
面摩擦係数センサ２８からの路面摩擦係数信号を受ける
特性選択部３５が備えられている。Further, inside the controller 25, there is provided a characteristic selection section 35 that receives a road surface friction coefficient signal from the road surface friction coefficient sensor 28.
該特性選択部３５は、上記路ＷＩＢ擦係数センサ２８の
路面摩擦係数信号値が設定値以上のときには、上記特性
記憶部３０から通常走行時用の転舵比特性へを選択する
一方、路面摩擦係数信号値が設定値未満のときには低μ
路走行時用の転舵比特性Ｂを選択するものであって、該
特性選択部３５で選択された特性記憶部３０の転舵比特
性に従って上記目標転舵角演算部３１における目標転舵
角の演算が行われるようになっている。When the road surface friction coefficient signal value of the road WIB friction coefficient sensor 28 is greater than or equal to the set value, the characteristic selection section 35 selects the steering ratio characteristic for normal driving from the characteristic storage section 30, while selecting the steering ratio characteristic for normal driving. Low μ when the coefficient signal value is less than the set value
The target steering angle calculation section 31 selects the steering ratio characteristic B for road driving according to the steering ratio characteristic stored in the characteristic storage section 30 selected by the characteristic selection section 35. The calculation is now performed.
よって、上記特性選択部３５により、路面摩擦係数セン
サ２８の出力信号に基づいて路面の摩擦係数の状態を判
断し、路面の１！！−係数が低い時には高い時に比べて
同位相側に補正された特性で後輪を転舵するよう、上記
転舵比を通常走行時用の転舵比特性へから低μ路走行時
用の転舵比特性Ｂに切換補正するようにした補正手段を
構成している。Therefore, the characteristic selection section 35 determines the state of the friction coefficient of the road surface based on the output signal of the road surface friction coefficient sensor 28, and determines the state of the road surface friction coefficient. ! - When the coefficient is low, the above steering ratio is changed from the steering ratio characteristic for normal driving to the steering ratio characteristic for driving on low μ roads so that the rear wheels are steered with characteristics corrected to the same phase side compared to when the coefficient is high. This constitutes a correction means that performs switching correction to the steering ratio characteristic B.
次に、上記第１実施例の作用・効果について説明するに
、路面の摩擦係数が設定値以上の通常走行時の場合には
、後輪転舵機構７のコントローラ２５においては、特性
選択部３５で特性記憶部３０に記憶された２種類の転舵
比特性Ａ、Ｂの中から通常走行時用の転舵比特性へが選
択され、この選択された転舵比特性へに基づいて転舵比
可変手段３４の目標転舵角演算部３１で目標転舵角が演
算されることにより、前輪転舵角に対する後輪転舵角の
転舵比が上記通常走行時用の転舵比特性Ａに従って可変
制御され、その結果、後輪８Ｌ、８Ｒは、低車速時では
前輪２ｍ、２Ｒと逆位相に転舵され、中・高車速時では
前輪２Ｌ、２Ｒと同位相に転舵される。Next, to explain the operation and effect of the first embodiment, when the friction coefficient of the road surface is higher than the set value during normal driving, the controller 25 of the rear wheel steering mechanism 7 selects the characteristics selector 35. The steering ratio characteristic for normal driving is selected from the two types of steering ratio characteristics A and B stored in the characteristic storage section 30, and the steering ratio is changed based on the selected steering ratio characteristic. By calculating the target steering angle in the target steering angle calculation unit 31 of the variable means 34, the steering ratio of the rear wheel steering angle to the front wheel steering angle is varied according to the steering ratio characteristic A for normal driving. As a result, the rear wheels 8L and 8R are steered in the opposite phase to the front wheels 2m and 2R at low vehicle speeds, and in the same phase as the front wheels 2L and 2R at medium and high vehicle speeds.
一方、路面の摩擦係数が設定値未満になる雨天時や未舗
装路、雪路走行時の場合には、上記特性選択部３５は、
路面摩擦係数センサ２８からの路面摩擦係数信号を受け
て上述の通常走行時用の転舵比特性Ａに代って低μ路走
行時用の転舵比特性Ｂを特性記憶部３０から選択し、こ
の選択された低μ路走行時用の転舵比特性Ｂに従りて転
舵比が転舵比可変手段３４によって可変制御される。On the other hand, in the case of rainy weather, unpaved roads, or snowy roads where the coefficient of friction of the road surface is less than the set value, the characteristic selection unit 35
In response to the road surface friction coefficient signal from the road surface friction coefficient sensor 28, a steering ratio characteristic B for driving on a low μ road is selected from the characteristic storage section 30 in place of the above-mentioned steering ratio characteristic A for normal driving. The steering ratio is variably controlled by the steering ratio variable means 34 in accordance with the selected steering ratio characteristic B for traveling on a low μ road.
この場合、上記低μ路走行時用の転舵比特性Ｂは、通常
走行時用の転舵比特性Ａに比べて同位相側にずれている
ので、後輪８Ｌ、８Ｒが通常走行時よりも前輪２Ｌ、２
Ｒと同位相方向に転舵されて車輪の横方向グリップ力が
増大し、その結果、低μ路走行時においても車輪（前輪
２Ｌ、２Ｒおよび後輪８Ｌ、８Ｒ）の横すべりが可及的
に防止されることになる。よって、走行安定性の向上を
図ることができる。In this case, since the steering ratio characteristic B for driving on a low μ road is shifted to the same phase side compared to the steering ratio characteristic A for normal driving, the rear wheels 8L and 8R are Also front wheels 2L, 2
It is steered in the same phase direction as R, increasing the lateral grip force of the wheels, and as a result, side slipping of the wheels (front wheels 2L, 2R and rear wheels 8L, 8R) is minimized even when driving on low μ roads. This will be prevented. Therefore, it is possible to improve running stability.
また、第４図は上記第１実施例における後輪転舵機構７
のコントローラ２５の変形例を示したものである。この
コントローラ２５は、目標転舵角Ｐｓ算部３１′とパル
スジェネレータ３２′とドライバ３３′とによって構成
され、前輪転舵角に対する後輪転舵角の転舵比を特性記
憶部３０’ に記憶された所定の転舵比特性〈第１実施
例における特性記憶部３０に記憶された通常走行時用の
転舵比特性Ａに相当）に従って可変制御する転舵比可変
手段３４′を備えているとともに、路面摩擦係数センサ
２８からの路面ｒｆＪ擦係数信号を受け、路面摩擦係数
の低下に応じて上記転舵比可変手段３４′の目標転舵角
演算部３１′で演算された目標転舵角に対して漸次正方
向の補正転舵角を加算して、転舵比を漸次同位相方向に
大きく補正する補正手段としての補正部３６を備えてな
るものである。Further, FIG. 4 shows the rear wheel steering mechanism 7 in the first embodiment.
This figure shows a modification of the controller 25 shown in FIG. This controller 25 is composed of a target steering angle Ps calculation section 31', a pulse generator 32', and a driver 33', and stores the steering ratio of the rear wheel steering angle to the front wheel steering angle in the characteristic storage section 30'. and a steering ratio variable means 34' that performs variable control according to a predetermined steering ratio characteristic (corresponding to the steering ratio characteristic A for normal running stored in the characteristic storage section 30 in the first embodiment). , receives the road surface rfJ friction coefficient signal from the road surface friction coefficient sensor 28, and adjusts the target steering angle to the target steering angle calculated by the target steering angle calculating section 31' of the steering ratio variable means 34' in accordance with the decrease in the road surface friction coefficient. A correction section 36 is provided as a correction means for gradually adding a corrected steering angle in the positive direction to gradually correct the steering ratio largely in the same phase direction.
したがって、上記変形例の場合には、通常走行時用の転
舵比特性が路面の摩擦係数の低下に応じて同位相方向に
漸次大きく補正されるので、上記第１実施例の如く路面
摩擦係数が設定値未満となった時点で転舵比特性を通常
走行時、用から低μ路走行時用のものに切換え選択する
場合に比べて転舵比の制御精度が細かくなり、走行安定
性の向上をより一層図ることができる。Therefore, in the case of the above modification, the steering ratio characteristic for normal driving is gradually corrected to a large extent in the same phase direction as the friction coefficient of the road surface decreases. When the steering ratio becomes less than the set value, the steering ratio characteristics are switched from normal driving or use to low μ road driving.Compared to the case where the steering ratio characteristics are selected, the control accuracy of the steering ratio becomes finer and the driving stability is improved. Further improvement can be achieved.
また、第５図は上記第１実施例の変形例として前輪転舵
角θＦの大きさに応じて後輪転舵角θＲを演算して転舵
比を制御する場合の転舵比特性を示したものである。こ
の舵角による転舵比制御は、前輪転舵角θＦが高車速時
では小さく、低車速時では大きくなるという実情に基づ
いて前輪転舵角θＦに対する後輪転舵角θＲの転舵比を
制御するものであり、その転舵比特性は、基本的には車
速による転舵比制御の場合と同様、低車速時では前輪と
後輪とを逆位相に、高車速時では同位相にするように設
定されている。Further, FIG. 5 shows the steering ratio characteristics in the case where the steering ratio is controlled by calculating the rear wheel steering angle θR according to the magnitude of the front wheel steering angle θF as a modification of the first embodiment. It is something. This steering ratio control using the steering angle controls the steering ratio of the rear wheel steering angle θR relative to the front wheel steering angle θF based on the fact that the front wheel steering angle θF is small at high vehicle speeds and becomes large at low vehicle speeds. The steering ratio characteristic is basically the same as in the case of steering ratio control based on vehicle speed, so that the front and rear wheels are in opposite phases at low vehicle speeds and in the same phase at high vehicle speeds. is set to .
そして、上記舵角による転舵比制御の場合においても、
その転舵比特性としては、通常走行時用の転舵比特性Ｃ
と低μ路走行時用の転舵比特性りの２種類がある。低μ
路走行時用の転舵比特性りは、通常走行時用の転舵比特
性Ｃに比べて前輪転舵角θＦの全範囲に亘って後輪転舵
角θＲの正方向の同位相側にずれた傾向にあり、路面摩
擦係数が設定値未満の状態において、この転舵比特性り
に従って後輪が第１実施例の場合と同様に通常走行時よ
りも前輪と同位相方向に転舵される。尚、舵角による転
舵比制御の場合には、第１実施例の如き車速を検出する
車速センサ２７は不要である。Also, in the case of steering ratio control using the above-mentioned rudder angle,
The steering ratio characteristic is the steering ratio characteristic C for normal driving.
There are two types: and one with steering ratio characteristics for driving on low μ roads. Low μ
Compared to the steering ratio characteristic C for normal driving, the steering ratio characteristic for road driving is shifted to the same phase side in the positive direction of the rear wheel steering angle θR over the entire range of the front wheel steering angle θF. In a state where the road surface friction coefficient is less than the set value, the rear wheels are steered in the same phase direction as the front wheels than during normal driving according to this steering ratio characteristic, as in the case of the first embodiment. . Note that in the case of steering ratio control using the steering angle, the vehicle speed sensor 27 for detecting vehicle speed as in the first embodiment is not required.
−さらに、第６図は本発明の第２実施例に係る車両の４
輪操舵装置の全体構成を示し、この４輪操舵装置にお番
ノる後輪転舵機構７′は、第１実施例の４輪操舵装置に
おける後輪転舵機構７の如（パルスモータ１４の作動に
より後輪８Ｌ、８Ｒを電気的に転舵する代わりに、前輪
転舵機構１の操舵力を利用して後輪８Ｌ、８Ｒを機械的
に転舵するようにしたものである。-Furthermore, FIG. 6 shows a vehicle according to a second embodiment of the invention.
The overall configuration of the wheel steering device is shown, and the rear wheel steering mechanism 7' that is in charge of this four-wheel steering device is similar to the rear wheel steering mechanism 7 in the four-wheel steering device of the first embodiment (operation of the pulse motor 14). Instead of electrically steering the rear wheels 8L, 8R, the steering force of the front wheel steering mechanism 1 is used to mechanically steer the rear wheels 8L, 8R.
すなわち、上記後輪転舵機構７′は、ギヤ等からなる転
舵比変受装＠３７を備え、該転舵比変更装置３７には車
体前後方向に延びる伝達ロッド３８の後端が連結され、
該伝達ロッド３８の前端部には、前輪転舵機構１のラッ
ク＆ピニオン機構４のラック軸４ａに形成されたラック
３９と噛合するビニオン４０が設けられている。また、
上記転舵比変更装置３７からは摺動部材４１が延出され
、該摺動部材４１に形成されたラック４２に対しては、
後輪操作ロッド１１にラック１２およびビニオン１３を
介して連結されたビニオン軸１７の前端部に設けたビニ
オン４３が噛合している。しかして、前輪転舵機構１の
操舵力がラック＆ピニオン機構４のラック軸４ａから伝
達ロッド３８を介して転舵比変更装置！３７に伝達され
、該転舵比変更装置３７においてコン１−ローラ２５の
制御に従って転舵比が変更された後に操舵力が摺動部材
４１およびビニオン軸１７を介して後輪操作ロッド１１
に伝達されることにより、後輪８ｍ、８Ｒが左右に転舵
されるように構成されている。尚、４輪操舵装置のその
他の構成は、第１実施例の４輪操舵装置と同じであり、
同一部材には同一符号を付してその説明は省略する。That is, the rear wheel steering mechanism 7' includes a steering ratio changing device @37 made of gears, etc., and the rear end of a transmission rod 38 extending in the longitudinal direction of the vehicle body is connected to the steering ratio changing device 37.
A pinion 40 is provided at the front end of the transmission rod 38 and meshes with a rack 39 formed on the rack shaft 4a of the rack and pinion mechanism 4 of the front wheel steering mechanism 1. Also,
A sliding member 41 extends from the steering ratio changing device 37, and a rack 42 formed on the sliding member 41 has the following functions:
A binion 43 provided at the front end of a binion shaft 17 connected to the rear wheel operating rod 11 via a rack 12 and a binion 13 meshes with it. Thus, the steering force of the front wheel steering mechanism 1 is transmitted from the rack shaft 4a of the rack and pinion mechanism 4 via the transmission rod 38 to the steering ratio changing device! 37, and after the steering ratio is changed in the steering ratio changing device 37 according to the control of the controller 1-roller 25, the steering force is transmitted to the rear wheel operating rod 11 via the sliding member 41 and the pinion shaft 17.
The rear wheels 8m and 8R are configured to be steered to the left and right by being transmitted to the rear wheels 8m and 8R. Note that the other configurations of the four-wheel steering device are the same as the four-wheel steering device of the first embodiment,
Identical members are given the same reference numerals and their explanations will be omitted.
そして、上記転舵比変更装置３７を制御するコントロー
ラ２５自体は、第１実施例の場合と同じであり、また、
それにより同様の作用・効果を奏することができるのは
勿論である。The controller 25 itself that controls the steering ratio changing device 37 is the same as in the first embodiment, and
Of course, similar actions and effects can be achieved thereby.
尚、上記実施例では、路面摩擦係数センサ２８を、実車
速とメータ車速との比較により検出するもので構成した
が、その他、路面状況に応じて運転者により適宜切換操
作されるマニ・ユアル切換スイッチで構成してもよい。In the above embodiment, the road surface friction coefficient sensor 28 is configured to detect by comparing the actual vehicle speed and the metered vehicle speed, but there is also a manual switch which can be switched as appropriate by the driver depending on the road surface condition. It may also be configured with a switch.
この場合、特性記憶部３ｏには、予め、マニュアル切換
スイッチの舗装路ウェット、未舗装、雪路等の各切換位
置に応じた多種の転舵比特性が記憶される。また、雨天
走行時には、ワイパースイッチのｒｌＮＴＪ、ｒＬＯＷ
Ｊ、ｒＨＩＧＨＪの各払拭速度位置の検出により路面摩
擦係数センサ２８を構成してもよい。In this case, the characteristic storage unit 3o stores in advance various steering ratio characteristics corresponding to each switching position of the manual changeover switch, such as wet paved road, unpaved road, snowy road, etc. Also, when driving in the rain, turn the wiper switch rlNTJ and rLOW.
The road surface friction coefficient sensor 28 may be configured by detecting the wiping speed positions J and rHIGHJ.
（発明の効果）
以上の如く、本発明における車両の４輪操舵装置によれ
ば、低μ路走行時には、転舵比可変手段の所定の転舵比
特性を補正手段によって同位相方向に補正して、車輪の
路面に対する横方向グリップ力を増大させたので、車輪
の横すべりを防止することができ、走行安定性の向上を
図ることができるものである。(Effects of the Invention) As described above, according to the four-wheel steering system for a vehicle according to the present invention, when traveling on a low μ road, the predetermined steering ratio characteristic of the steering ratio variable means is corrected in the same phase direction by the correction means. Since the lateral grip force of the wheels on the road surface is increased, it is possible to prevent the wheels from slipping sideways, and it is possible to improve running stability.
図面は本発明の実施例を示すもので、第１図ないし第３
図は第１実施例を示し、第１図は車両の４輪操舵装置の
全体構成図、第２図はコントローラのブロック構成図、
第３図はコントローラの車速による転舵比制御の場合に
おける転舵比特性を示す図である。第４図および第５図
はそれぞれ第１実施例の変形例を示し、第４図は第２図
相当図、第５図はコントローラの舵角による転舵比制御
の場合における転舵比特性を示す図である。第６図は第
２実施例を示す第１図相当図である。
１・・・前輪転舵機構、７．７′・・・後輪転舵機構、
２５・・・コントローラ、２８・・・路面摩擦係数セン
サ、３０・・・特性記憶部、３４．３４’・・・転舵比
可変手段、３５・・・特性選択部、３６・・・補正部。
−シーーーーーーThe drawings show embodiments of the present invention, and FIGS.
The figures show a first embodiment, in which Fig. 1 is an overall configuration diagram of a four-wheel steering system for a vehicle, Fig. 2 is a block configuration diagram of a controller,
FIG. 3 is a diagram showing steering ratio characteristics in the case of steering ratio control using the vehicle speed of the controller. 4 and 5 respectively show modifications of the first embodiment, FIG. 4 is a diagram corresponding to FIG. 2, and FIG. 5 shows the steering ratio characteristics in the case of steering ratio control using the steering angle of the controller. FIG. FIG. 6 is a diagram corresponding to FIG. 1 showing the second embodiment. 1... Front wheel steering mechanism, 7.7'... Rear wheel steering mechanism,
25... Controller, 28... Road surface friction coefficient sensor, 30... Characteristic storage section, 34.34'... Steering ratio variable means, 35... Characteristic selection section, 36... Correction section . -Shhhh
Claims (1)
構と、この前輪の転舵に応じて後輪を転舵する後輪転舵
機構とを備えてなる車両の４輪操舵装置であつて、上記
後輪転舵機構は、前輪転舵角に対する後輪転舵角の比を
所定の転舵比特性に従つて可変とする転舵比可変手段と
、路面の摩擦係数を検出する検出手段と、該検出手段の
出力信号に基づいて路面の摩擦係数の状態を判断し、路
面の摩擦係数が低い時には高い時に比べて同位相側に補
正された特性で後輪を転舵するよう転舵比を補正する補
正手段とを備えたことを特徴とする車両の４輪操舵装置
。(1) A four-wheel steering system for a vehicle, comprising a front wheel steering mechanism that steers the front wheels in response to steering wheel steering, and a rear wheel steering mechanism that steers the rear wheels in response to steering of the front wheels. The rear wheel steering mechanism includes a steering ratio variable means for varying the ratio of a rear wheel steering angle to a front wheel steering angle according to a predetermined steering ratio characteristic, and a detection means for detecting a friction coefficient of a road surface. , determines the state of the road surface friction coefficient based on the output signal of the detection means, and sets a steering ratio so that when the road surface friction coefficient is low, the rear wheels are steered with characteristics corrected to the same phase side as compared to when the road surface friction coefficient is high. A four-wheel steering device for a vehicle, comprising: a correction means for correcting.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14344385A JPS624679A (en) | 1985-06-29 | 1985-06-29 | 4-wheel steering apparatus for vehicle |
| CA000511535A CA1269335A (en) | 1985-06-17 | 1986-06-13 | Four-wheel steering system for vehicle |
| DE8686108194T DE3660036D1 (en) | 1985-06-17 | 1986-06-16 | Four-wheel steering system for vehicle |
| EP86108194A EP0208173B1 (en) | 1985-06-17 | 1986-06-16 | Four-wheel steering system for vehicle |
| US06/874,687 US4733878A (en) | 1985-06-17 | 1986-06-16 | Four-wheel steering system for vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14344385A JPS624679A (en) | 1985-06-29 | 1985-06-29 | 4-wheel steering apparatus for vehicle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS624679A true JPS624679A (en) | 1987-01-10 |
Family
ID=15338818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14344385A Pending JPS624679A (en) | 1985-06-17 | 1985-06-29 | 4-wheel steering apparatus for vehicle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS624679A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5089967A (en) * | 1987-08-10 | 1992-02-18 | Nippondenso Co., Ltd. | Auxiliary steering system associated with anti-skid control system for use in motor vehicle |
| US5261677A (en) * | 1991-07-30 | 1993-11-16 | Nitto Kohki Co., Ltd. | Seal ring |
-
1985
- 1985-06-29 JP JP14344385A patent/JPS624679A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5089967A (en) * | 1987-08-10 | 1992-02-18 | Nippondenso Co., Ltd. | Auxiliary steering system associated with anti-skid control system for use in motor vehicle |
| US5261677A (en) * | 1991-07-30 | 1993-11-16 | Nitto Kohki Co., Ltd. | Seal ring |
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