JPH0133384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rack and pinion steering device.

As a steering device for an automobile, a rack shaft having rack teeth is fitted into a gear case so as to be slidable in the axial direction, and a pinion that meshes with the rack teeth of the rack shaft is rotatably mounted on the gear case. is fixed to a member on the vehicle body side, and when the steering handle is rotated, the pinion rotates and slides the rack shaft in the axial direction, and this sliding motion is transmitted to the wheels via the tie rod and the knuckle arm to perform steering. A so-called rack and pinion type steering device is generally widely used (see, for example, Japanese Utility Model Application Publication No. 55-37721).

Although the rack and pinion steering device described above has a simple structure, high rigidity, and is excellent in practical use, the steering angle ratio (handle rotation angle/actual steering angle of the steering wheel) is Since it is determined by the gear ratio, there is a problem in that it is extremely difficult to make the steering angle ratio variable.

In general, one of the biggest factors that determines the steering stability of a car is the steering angle ratio.If the angle ratio is large, the steering force will be light, which is convenient when making large turns, but the steering wheel will be too light when driving straight at high speed. This not only gives the driver a sense of uneasiness, but also has the disadvantage of increasing the angle of rotation of the steering wheel to obtain the specified turning radius.Contrary to the above, if the angle ratio is made small, stability during straight-line high-speed driving is better The angle of rotation of the steering wheel to obtain a turning radius of 1 is small, making it easier to operate the steering wheel, but the problem arises in that the steering force becomes heavy, making it particularly difficult to perform large turns. In order to satisfy the conflicting demands of reducing steering force and improving stability during straight high-speed driving, it is effective to set the steering angle ratio to a non-linear characteristic, and also to adjust the steering angle ratio to a non-linear characteristic. Since the optimum characteristic value changes depending on conditions or the level of driving skill, it is essentially desirable that the steering angle ratio be variable.

An object of the present invention is to provide a rack and pinion type steering device that can variably control the steering angle ratio according to various external conditions using extremely simple measures. Explain with reference to.

In Fig. 1, 1 is a steering wheel;
2 is a steering shaft, and the steering shaft 2 has universal joints 3, 3'.
and the pinion shaft 15 via the intermediate shaft 2' etc.
is connected to. Reference numeral 4 denotes a gear case which rotatably supports the pinion shaft 15 and has a rack shaft 16 having rack teeth that mesh with the pinion teeth of the pinion shaft 15 inside so as to be slidable in the axial direction, and the gear case 4 has a bearing. 19 so as to be movable in the same direction as the sliding direction of the rack shaft 16. The bearing 19 is fixed to a vehicle body side member.

Both ends of the rack shaft 16 are connected to left and right tie rods 5, 5, and knuckle arms 7, 7 are connected to the tips of the tie rods 5, 5, respectively.
The rack shaft 16 is moved in the axial direction by the rotation of the pinion shaft 15 in conjunction with the rotation of the steering handle 1, and steering is performed by rotating the wheel 8 via the tie rod 5 and the knuckle arm 7, unlike the conventional rack pinion. It is similar to a type steering device.

6 is a dustproof cover, and 9 is a suspension member. Reference numeral 12 denotes a lever whose approximately L-shaped central portion is rotatably attached to the gear case 4 via a shaft 11, and one arm 12a of the lever 12 has a lever extending from near the tip of the arm 12a in the direction of the shaft 11. long hole 12
a' is provided, and the other end 14' of the link 14 whose one end is rotatably attached to the vehicle body side member 10 is connected to the elongated hole 1.
2a' so as to be rotatable and slidable,
A pin 13 is fixed to the tip of the other arm 12b of the lever 12, and the pin 13 is slidably fitted into a groove 17 provided in the rack shaft 16, as shown in FIG. .

As shown in FIG. 2, the groove 17 has an inclined groove portion 17' which is inclined with respect to the axis XX of the rack shaft 16 in a predetermined intermediate range a, and the ranges b and b' on both sides thereof are
The pin 13 is formed in axial grooves 17'', 17 parallel to the slanted groove 17'' as shown in FIG.
It is arranged so that it is located almost in the center of the

The gear case 4 has a pin 1 as shown in Fig. 1.
3 is provided with a slot 4' through which it passes with a margin.

An actuator 18 made of a telescoping member such as an electromagnetic solenoid or a cylinder device is provided between the link 14 and the vehicle body side member 10, and the link 14 is moved by the telescoping action of the actuator 18.
rotates around the connection point to the vehicle body member side, and the tip end 14' of the link 14 engages with the elongated hole 12 of the lever 12.
a' to change the engagement point between the link 14 and the lever 12.

In the above configuration, for example, by rotating the steering handle 1 in the direction of arrow A, the pinion shaft 1
5 rotates in the same direction, and the rack shaft 16 moves in the axial direction.
When moving by B', the groove 17 is moved as shown in Figure 3.
moves from the solid line position to the dotted line position, and following the shape of the inclined groove 17', the pin 13 is displaced from the solid line position to the dotted line position by B'' in a direction approximately perpendicular to the axis X-X of the rack shaft 16. do.

Therefore, the lever 12 is connected to the shaft 11 as shown in FIG.
It rotates clockwise in the figure around .
One arm portion 12a of the lever 12 is locked to the vehicle body side member 10 at a point 14' via a link 14, and this point 14' does not move in the X-X direction. 11 is from the position in _{Figure 4} A _: C = B _' ' (indicates the length to the point) to the left of the figure and reaches the position shown in Figure 4 B.
The gear case 4 is forcibly moved to the left in the figure by the amount of movement C of the shaft 11.

Therefore, movement B of tie rod 5 is caused by gear case 4.
The value obtained by adding the movement amount C of the gear case 4 itself to the movement amount B' of the rack shaft 16, ie, B=B'+C, the actual steering angle D becomes larger than the amount B' due to the gear ratio of the rack and pinion itself. That is, the steering angle ratio becomes small.

When the steering handle 1 is further rotated in the A direction, the rack shaft 16 is further moved in the B' direction, and the pin 13 reaches the axial groove part 17 from the inclined groove part 17', the pin 13 no longer moves in the axial direction. Since there is no displacement in the orthogonal direction and the lever 12 no longer rotates, the shaft 11 and gear case 4 do not move, and therefore, after the pin 13 reaches the axial groove 17, it depends only on the gear ratio of the pinion and rack. The actual steering angle becomes the actual steering angle, and the steering angle ratio becomes larger than when steering in range a, and as a result, as shown in Figure 5, the movement of the gear case itself is added to the movement of the rack shaft relative to the gear case due to the gear ratio of the rack and pinion. In the range where the rotation angle of the steering wheel is small, that is, in the range a of the inclined groove portion 17', the steering angle ratio is small, the movement of the rudder is good, and the steering force is too light near straight-ahead travel. This improves steering stability when driving straight at high speed, and the steering angle ratio is large in the range b and b', making it possible to reduce the steering force during large turns.

Furthermore, the amount of movement C of the gear case itself in the steering direction is determined by each arm 1 of the lever 12, as shown in equation (1) above.
Since it is proportional to the ratio of the effective lengths of 2a and 12b, l ₂ /l ₁ ,
As will be described later, the movement characteristics of the gear case 4 itself are variably controlled by extending and contracting the actuator 18 based on various external conditions and changing _l2 , which moves the point 14'. As shown by the dotted lines, it is possible to obtain various nonlinear steering angle characteristics that match the external conditions.

Next, an example of an operation control circuit for the actuator 18 will be explained with reference to FIG.

In FIG. 7, 20 is a sensor that detects external conditions such as a vehicle speed sensor 21, a loaded weight sensor 22, a rough road detection sensor 23, etc., and each signal of the sensor 20 that detects these external conditions is sent to an arithmetic circuit 24. The arithmetic circuit 24 calculates the optimum steering angle ratio for the external conditions from these signals and generates an output signal 25. This output signal adjusts the output 27 of the actuator's power source 26, thereby controlling the actuator. 18 is telescopically operated to change the effective length _l2 of the arm portion 12a of the lever 12, and the change signal is inputted from the actuator displacement sensor 28 to the calculation circuit 24 to determine the steering angle ratio that best suits the external conditions at that time. The actuator 18 is configured to stop operating at the position where it should be.

Reference numeral 29 is an adjustment dial, which allows the driver to manually operate the steering angle ratio to suit his/her own driving technique or preference.

As described above, according to the present invention, with an extremely simple configuration, it has a nonlinear steering angle ratio, and depending on external conditions, the characteristics of the nonlinear steering angle ratio can be varied to characteristics that suit the external conditions. It is possible to obtain a rack and pinion type steering device that can be controlled precisely, and it can bring about a great practical effect in that it can significantly improve the steering stability of an automobile at an extremely low cost.

[Brief explanation of drawings]

FIG. 1 is an explanatory plan view showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part of FIG. , Figures 4A and 4B are explanatory diagrams showing the rotational behavior of the lever due to the displacement of the pin in Figure 3, respectively, and Figure 5 is a diagram showing the change characteristics of the steering angle ratio due to the rotation of the lever in Figure 4. , FIG. 6 is a diagram showing control characteristics of the steering angle ratio by actuator operation, and FIG. 7 is a block diagram showing an example of a control circuit for the actuator. 1...Steering handle, 4...Gear case, 5...Tie rod, 7...Natsukuru arm,
8...Wheel, 12...Lever, 13...Pin, 1
5...Pinion shaft, 16...Rack shaft, 17...
Groove, 18... Actuator.

Claims (1)

[Claims] 1 A pinion that rotates as the steering handle is rotated is rotatably mounted in the gear case, and a rack shaft that meshes with the pinion is fitted so as to be slidable in the axial direction. In a rack and pinion type steering device configured to perform steering by moving to a position, the gear case is attached to a vehicle body side member so as to be movable in the axial direction of the rack shaft, a lever is rotatably attached to the gear case, One arm of the lever is supported by the vehicle body side member, and the other arm is related to the rack shaft, and as the rack shaft moves within a predetermined range, the point of the other arm relative to the rack shaft is displaced. Then, the lever rotates around the point where it is attached to the gear case, and the gear case is loosened according to the lever ratio of each length from the rotation center of the lever to the support point to the vehicle body side member and the related point to the rack shaft. The shaft is configured to move in the same direction as the shaft, and
A rack and pinion type steering device characterized by being provided with an actuator that operates based on external conditions such as vehicle speed and loaded weight to variably control the lever ratio of the lever.