JPS62214058A - Automobile steering device - Google Patents

Abstract

PURPOSE:To improve a steering stability, by providing a differential gear unit comprising a sun gear, a planetary gear and an internal gear, rotating a gear unit by a support member of the planetary gear and controlling a steering angle ratio through a motor for rotating the internal gear. CONSTITUTION:A control circuit 11 determines an optimum steering angle based on a steering angle ratio property with respect to a traveling mode set and stored in advance in accordance with a change in the traveling mode and applies a signal to a motor 5. Then, a ratio of a rotating angle of an internal gear 33 to a rotating angle of a sun gear 31 rotated by a steering wheel 1 is controlled in accordance with a rotatingly driving angle of the motor 5 so that an optimum steering angle ratio is obtained. With such an arrangement, an optimum steering angle ratio is automatically regulated in accordance with a traveling mode, whereby a steering stability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a steering device for a motor vehicle.

2. Description of the Related Art In general, steering devices for automobiles use a gear device to convert the rotational operation of the steering wheel into an axial displacement of a shaft proportional to the rotation angle of the steering wheel. Wheel)
In the past, devices in which the steering operation is performed have been widely used (see, for example, Japanese Utility Model Application Publication No. 57-55671, Japanese Utility Model Application Publication No. 57-74876, etc.).

In addition, in a steering device having a gear device as described above, by devising the tooth profile of the gear, for example, the gear ratio is reduced in a small range of the steering wheel rotation angle, that is, near the straight-ahead state, and the gear ratio is reduced when the steering wheel rotation angle is large. Various so-called barrier-pull gear ratio steering devices have been developed in the past, in which the angle ratio between the steering wheel rotation angle and the actual steered wheel angle is non-linear, such as by increasing the angle of rotation of the steering wheel and the actual steering angle of the steered wheels.
It is disclosed in the specification of No. 3 or Japanese Utility Model Application Publication No. 59-16269.

Problems to be Solved by the Invention As mentioned above, the conventional device in which the ratio of the steering wheel rotation angle to the actual steered wheel angle, that is, the steering angle ratio, is in a proportional relationship, and the conventional device in which the nonlinear characteristic is used, are both gear devices. Steering output can only be obtained at an angle uniquely determined by the design.

In general, if the steering angle ratio is large, the steering will be light, but the steering wheel rotation angle to obtain the specified turning radius will be large, making the steering less effective.On the other hand, if the steering angle ratio is small, the steering will be light The steering wheel rotation angle required to obtain this effect is small, which improves the effectiveness of the rudder, but makes the steering heavier. Therefore, for example, it is desirable to reduce the steering angle ratio so that it is more effective while running at low speeds, but if you do so, the steering becomes too heavy when steering at very low speeds, including stationary steering, and it becomes difficult to steer at stationary steering or at extremely low speeds. If the steering angle ratio is increased in order to reduce the weight, a problem arises in that the steering becomes less effective when driving at high speeds.

In this way, the preferred steering angle ratio varies depending on the driving mode such as vehicle speed and road surface conditions, and whether the steering angle ratio has conventional proportional characteristics or nonlinear characteristics, the steering angle ratio depends on the design of the gear system. In the case of a steering system that is uniquely determined by the above, it is inevitable that the design will be a compromise by selecting an appropriate steering angle in consideration of the balance between steering force and rudder effectiveness in various driving modes. do not have.

The main object of the present invention is to provide a device that can finely control the steering angle ratio depending on the driving mode such as vehicle speed.

Means for Solving the Problems The present invention provides a steering system for an automobile in which steering wheels are steered through a gear device of a steering gear box by rotational operation of the steering wheel. A differential gear device consisting of a sun gear or a gear equivalent to it, a planetary gear or a gear equivalent to it, and an internal gear or a gear equivalent to it is interposed in the middle of the steering system leading to the gear device of the steering gear box, and the sun gear or an equivalent gear is rotated by the rotation operation of the steering wheel, and a gear device of the steering gear box is rotated by rotation of a support member that supports the rotating shaft of the planetary gear or the equivalent gear, and an internal gear or the equivalent thereof. The gear is configured to be rotated by an electric motor, and the rotation angle ratio between the sun gear or a gear equivalent to the sun gear and the support member that supports the rotating shaft of the planetary gear or the gear equivalent to the sun gear is set as follows: The steering angle ratio between the steering wheel rotation angle and the actual steered wheel angle is variably controlled by changing the ratio of the rotation angle of an internal gear rotated by an electric motor or an equivalent gear to the rotation angle. The input angle signal of the input angle sensor detects the rotation angle of the steering wheel and generates the input angle signal, and the driving mode signal of the driving mode sensor detects the driving mode such as vehicle speed and issues the driving mode signal. The present invention is characterized in that a control circuit is provided which determines the optimum steering angle ratio for the driving mode from the above and generates an output corresponding to the optimum steering angle ratio to rotationally drive the electric motor.

Effect As described above, as the driving mode changes due to vehicle speed, road surface conditions, etc., the control circuit should rotate the electric motor by determining the optimum steering angle ratio based on the steering angle ratio characteristics for the driving mode that have been set and stored in advance. Controls the rotation angle ratio of the internal gear or its equivalent gear to the rotation angle of the sun gear or its equivalent gear rotated by the steering wheel, thereby making the steering angle ratio match the above-mentioned optimal steering angle ratio. It is something that makes you

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show a first embodiment of the present invention,
1 is a steering wheel, 2 is a steering shaft, and 4 is a steering gear box. A pinion gear is rotatably supported in the steering gear box 4, and a rack shaft that meshes with the pinion gear is movable in the axial direction. The rack shaft is supported as shown in FIG. Since the gear device and the steering mechanism from the gear device to the steering wheels have been commonly used as steering devices for automobiles, detailed illustrations and explanations will be omitted.

The steering shaft 2 is divided into an input shaft 21 connected to the steering wheel 1 and an output shaft 22 connected to the pinion gear supported within the steering gear box 4. The rotation of the input shaft 21 is controlled by a planetary gear. It is configured to be transmitted to the output shaft 22 via the differential gear device 3.

The planetary gear type differential gear device 3 includes a sun gear 31 that rotates integrally with the output shut 22, a plurality of planet gears 32 that mesh with the sun gear 31, and a plurality of planet gears 32 on the inner peripheral surface. It consists of an internal gear 33 having internal teeth that mesh with the outer circumference, and external teeth that mesh with the worm gear 6 fixed to the output shaft of the electric motor 5 and constitute a reduction mechanism are formed on the external peripheral surface of the internal gear 33. The output shaft 22 is coupled to a carrier 32a that supports the rotating shaft of the planetary gear 32.

7 is an input angle sensor that detects the rotation angle of the steering wheel l and emits an input angle signal according to the rotation angle; 8 is an output angle sensor that detects the rotation angle of the output shaft 22 and emits an output angle signal according to the rotation angle; 9 is a driving mode This is a driving mode sensor that detects the vehicle speed and issues a driving mode signal.As the driving mode sensor 9, only a vehicle speed sensor that detects the vehicle speed and generates a vehicle speed signal corresponding to the vehicle speed is used, or a vehicle speed sensor that detects the vehicle speed and generates a vehicle speed signal corresponding to the vehicle speed, or A combination of part or all of an engine load sensor that detects engine load, a road condition sensor that detects road conditions such as whether the road is good or slippery and issues a signal is used.

Reference numeral 10 denotes an intermediate angle sensor that detects the rotation angle of the internal gear 33 and generates an intermediate angle signal corresponding to the rotation angle.

ll is a control circuit, and the control circuit 11 calculates the rotation angle at which the internal gear 33 should be rotated from the input angle signal of the input angle sensor 7 and the running mode signal of the running mode sensor 9, It emits an output to rotate the electric motor 5. Note that the rotation of the electric motor 5 is feedback-controlled by the output angle signal of the output angle sensor 8 and the intermediate angle signal of the intermediate angle sensor 10.

In the above, when the steering wheel 1 (i.e., the input shaft) 21 is rotated by 01 angle with a torque of T1, and the internal gear 33 is rotated by an angle φ with a torque of T through the reduction mechanism due to the rotational drive of the electric motor 5, the carrier 32a, i.e., the output shaft 22 is rotated by 02 angles with a torque of T2, the rotation angle ratio θ1102 between the input shaft 21 and the output shaft 22 is expressed by the following equation.

θ1/θ2−−L−t−Jl! −・・・・・・・・・・・・
...(1) 1+np However, p is the ratio r/rl of the radius r1 of the sun gear 31 and the radius r of the internal teeth of the internal gear 33, and n is the rotation angle θ1 of the input shaft 21 and the rotation angle φ of the internal gear 33. The ratio of φ/θ1 and the torque T, , T, T2 are T1/T2=#' T/T2
Since there is a relationship of -1+p, T2 ='rl +"r
・・・・・・・・・・・・・・・ (2)

From the above equation (1), by changing the rotation angle φ of the internal gear 33 with respect to the rotation angle θ1 of the input shaft 21 and changing φ101, that is, n, the rotation angle ratio of input shaft 21 and output shaft 22 can be arbitrarily changed. It is clear that the rotation of the output shaft 22 is proportionally transmitted and converted to the actual steering angle of the steered wheels by the gear device in the gear box 4, so that the rotation of the output shaft 22 is proportionally transmitted and converted to the actual steering angle of the steering wheel. The electric motor 5 corresponds to the steering wheel rotation angle.
By controlling the rotational drive angle of the steering wheel 1, the ratio between the rotational operation angle of the steering wheel 1 and the actual steering angle of the steered wheels, that is, the steering angle ratio, is controlled to an optimal value that matches the current driving mode. can 21 and output shaft 2
Even if the rotation angle ratio θl/θ2 of 2 changes, it is always proportional to the output torque T2, so the steering wheel can feel the road reaction force as a response, and the steering feeling can be improved.

FIG. 3 shows a second embodiment of the present invention, and in this example, the sun gear 31 and planetary gear 3 of FIGS. 1 and 2 are used.
2 shows an example in which a bevel gear type differential gear unit 1 consisting of a combination of bevel gears is used instead of the planetary gear type differential gear unit 3 consisting of a ring gear 2 and an internal gear 33.

That is, in FIG. 3, the bevel gear type differential gear device 3' includes a pair of front and rear large differential gears 31' and 33' made of bevel gears, and a small differential gear 3 made of two bevel gears meshing with these large differential gears 31' and 33'. and a differential gear box 32 that supports the rotating shaft of the differential pinion 3g. (
The input shaft 21 connected to the steering handle 1 is connected to one of the large differential gears 31.
', and the other large differential gear 33' is configured to be rotated by the electric motor 5 via a reduction mechanism consisting of a worm gear 6 and a worm wheel 6', and the rotating shaft of the small differential gear 32 is The output shaft 22 is configured to be rotated by the supported differential gear box 32a,
The rest of the structure is the same as that in FIG. 1, and the same reference numerals as in FIG. 1 represent the same parts.

In the bevel gear type differential gear device 3 of FIG. 3, one large differential gear 31' corresponds to the sun gear 31 of FIG. 1, and the other large differential gear 33' corresponds to the internal gear of FIG. 33, the differential pinion 32' corresponds to the planetary gear 32 in FIG. 1, and the differential gear box 32a corresponds to the carrier 32a in FIG. motor 5
and the angles θ] and φ of the differential gears 37 and 31, respectively.
Assuming that the small differential gear 32' revolves around the large differential gears 31' and 33' at an angle of θ2 by rotating
Since the radius r1 of one large differential gear 31' and the radius r of the other large differential gear 33' are the same, p=r/r1=1
The rotation angle ratio θ1/θ2 between the input shaft 21 and the output shaft 22 is 2 from the above equation (1).
(3) However, n is φ/θ! By changing the ratio of the rotation angle φ of the differential large gear 3 rotated by the electric motor 5 to the steering wheel rotation angle θ1 according to the driving mode such as vehicle speed, the optimum steering angle ratio for that driving mode can be determined. Obtainable.

In addition, the input side torque TI, the output side torque T2, and the rotational torque T of the differential large gear 33' caused by the electric motor 5 are T1
/T2= or T/T2=+, and even if the rotation angle ratio θ1/θ2 of the input shaft 21 and output shaft 22 changes, the ratio of T1 and T2 is always constant, so the steering wheel can be used to control the road surface. The reaction force can be felt and the steering feeling can be improved.

In both the embodiments shown in FIG. 1 and FIG. 3, the control circuit 11 is configured to increase the steering angle ratio to suppress the rudder's effectiveness when driving at very low speeds, and to reduce the steering angle ratio at low to medium speeds. Optimum steering angle ratio according to the vehicle speed, such as by making the steering angle smaller to improve the effectiveness of the rudder and allow for agile steering, and by making the steering angle ratio slightly thicker because too much rudder effectiveness is dangerous at high speeds. n to obtain (=φ/θ1)
In addition to the above, you can set n to obtain the optimal steering angle ratio depending on the road surface condition, such as increasing the steering angle ratio since agile steering is dangerous on slippery roads. Remember the settings,
The electric motor 5 is activated based on the stored data by inputting the driving mode signal from the driving mode sensor 9.
The control circuit 11 is provided with an operation section that can manually change the rate of change of n stored in the control circuit 11, so that the control circuit 11 can change the rate of change of n stored in the control circuit 11 according to the driver's preference, for example, to change the vehicle speed. It is desirable to be able to adjust the control mode of the steering angle ratio.

Effects of the Invention By having the present invention configured as described above, the steering angle ratio is automatically adjusted so that the optimum steering feeling is always obtained depending on the driving mode, and the steering stability can be significantly improved. Even if the steering angle ratio is changed, the ratio between the steering torque and the torque on the output side is always in a constant relationship, so changes in road reaction force can be felt through the steering wheel, which can improve steering feel. .

In addition, in the event that the electric motor malfunctions and stops moving, the gear rotated by the electric motor will be in a fixed state, that is, n = in equations (1) and (3) above
Since the state is 01 in the embodiments of FIGS. 1 and 2,
The rotation angle ratio is 102=1+p, and in the embodiment shown in FIG.
Steering is performed at a rotation angle ratio of 1/θ2 = 2, which does not interfere with driving at all.In the end, the device of the present invention also has a fail-safe function, greatly improving safety. The overall structure is simple and the cost is relatively low, and together with this, it can bring about great practical effects.

[Brief explanation of drawings]

FIG. 1 is a side view showing the first embodiment of the present invention, FIG. 2 is an explanatory diagram schematically showing the planetary gear type differential gear unit of FIG. 1, and FIG. 3 is a side view showing the first embodiment of the present invention. FIG. 2 is a vertical sectional side view of main parts showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Steering wheel, 2... Steering shaft, 21... Input shaft, 22... Output shaft, 3, 3... Differential gear device, 4... Steering gear box, 5... ... Electric motor, 6... Worm gear, 7... Input angle sensor, 8... Output angle sensor, 9... Traveling mode sensor, lO... Intermediate angle sensor, 11... Control circuit. that's all

Claims (2)

[Claims] (1) In an automobile steering system in which the steering wheels are steered via the gear system of the steering gear box by the rotational operation of the steering wheel, from the steering wheel to the gear system of the steering gear box. A differential gear device consisting of a sun gear or a gear equivalent to it, a planetary gear or a gear equivalent to it, and an internal gear or a gear equivalent to it is interposed in the middle of the steering system, and the sun gear or the gear equivalent to it is connected to the steering wheel. The gear device of the steering gear box is rotated by the rotation of the supporting member that supports the rotating shaft of the planetary gear or the equivalent gear, and the internal gear or the equivalent gear is rotated by the electric motor. The rotation angle ratio between the sun gear or a gear equivalent to the sun gear and the support member that supports the rotation shaft of the planetary gear or the gear equivalent to the sun gear is
Steering by changing the ratio of the rotation angle of an internal gear or gear equivalent to it rotated by an electric motor to the rotation angle of a sun gear or equivalent gear A driving device configured to variably control the angle ratio, and detecting the input angle signal of an input angle sensor that detects the rotation angle of the steering wheel and generates an input angle signal, and a driving mode such as vehicle speed, and generates a driving mode signal. A steering device for an automobile, comprising a control circuit that determines an optimum steering angle ratio for a driving mode from the driving mode signal of a mode sensor and generates an output corresponding to the optimum steering angle ratio to rotationally drive an electric motor. (2), the differential gear device is a bevel gear type differential gear device,
The gears corresponding to the sun gear and the internal gear are front and rear large differential gears made of bevel gears, and the gears corresponding to the planetary gears are small differential gears that mesh astride the front and rear large differential gears. Claim 1: The gear is a gear, and the support member is a differential gear box that houses the front and rear differential gears and the differential gear, and supports the rotating shaft of the differential gear. A steering device for an automobile as described in paragraph.