JPS6332544Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rack and pinion type steering device used for a vehicle.

Typical examples of steering devices used in automobiles and the like are the ball screw type and the rack and pinion type, but the rack and pinion type steering device is often used because of its low price and sharp response. There is. The rack and pinion type steering device has a sharp response as a structural feature, but the rack bars in this device are relatively long because they extend in the width direction of the vehicle to near the wheels on both sides. Because of this, bending is likely to occur during manufacturing,
This bending may cause problems such as increased resistance, increased operating force, and poor responsiveness. For this reason, for example, Japanese Utility Model Application No. 56-122680 proposes dividing the rack bar into a portion having a rack and a rod portion to facilitate manufacturing and prevent bending.

On the other hand, when using a rack and pinion type steering device, the mounting position of this device must be carefully considered since the mounting device for this device greatly affects the toe-in/toe-out characteristics of the tire. Regarding the mounting method, for example, in Japanese Utility Model Application No. 55-37721, the mounting part of the gear housing of a rack and pinion type steering device is made into a cylindrical shape with a part of the protrusion, etc., and the support surface of the support bracket that supports it is made into a circular arc. A proposal has been made to make it possible to easily change the mount angle of the steering device as a shape, but this proposal concerns the mount angle and does not consider the mount position (in particular, the position in the vertical direction of the vehicle body). do not have. Therefore, the relationship between the mounting position of the rack and pinion type steering device and the toe-in/toe-out characteristics will be explained below.

FIG. 1 is a perspective view showing an example of the suspension and steering section of a front-wheel drive vehicle. (referred to as a device). This steering device 6 has a gear housing 5 fixed to a vehicle body (not shown), and a steering wheel 7.
The rotation of the tie rods 21 and 22 is changed to the movement of the axis in the left-right direction of the vehicle body, and the tie rods 21 and 22 are moved in the left-right direction of the vehicle body. The tie rods 21, 22 have one end fixed to the steering device 6, and the other end fixed to the knuckle 3a,
Since it is fixed to the arm of 3b by a ball joint, the movement of the tie rods 21 and 22 turns the knuckles 3a and 3b, and the knuckles 3a and 3b
The wheels attached to the wheels are rotated to perform steering operations. The nuts 3a, 3b are attached to the vehicle body via suspensions 8a, 8b, and the lower arm 1
It is also supported by numbers 1 and 12. The lower arms 11, 12 are attached at their inner ends to the vehicle body by shafts 11a, 12a so as to be vertically rotatable, and at their outer ends, ball joints 11b are attached to the knuckles 3a, 3b. , 12b are rotatably attached. Note that this example shows the case of a front-wheel drive vehicle, and the drive shafts 4a, 4b are connected to left and right tires.

In the above structure, the steering wheel 7, shaft 8, steering device 6, tie rod 21, knuckle 3a, and lower arm 11
Figures 2a and 2b are schematic diagrams schematically showing the
The figure is a plan view seen from the top of the vehicle body. Tie rod 21 is the steering device and ball joint 2
1b, Knuckle 3a (represented by a straight line)
are connected to each other by ball joints 21a, and the lower arm 11 has its inner end connected to the shaft 1.
1b, it is supported by the vehicle body so as to be vertically rotatable about this shaft 11b, and its outer end is connected to the knuckle by a ball joint 11a. In Fig. 2a, when the tires move up and down (that is, when the vehicle body moves up and down due to unevenness of the road surface while driving), the ball joint that connects to the tie rod 21 is connected to the knuckle 3a that moves together with the tire. 21a follows a trajectory along an arc A centered on the ball joint 21b at the other end, and the ball joint 11a coupled to the lower arm 11 follows a trajectory along an arc B centered on the shaft 11b at the other end. Since the arcs A and B have different trajectories, when the tire moves up and down, the ball joint 21a of the tie rod 21 moves relative to the vehicle body with respect to the ball joint 11a of the lower arm 11, as shown in Fig. 2b. Movement in the left-right direction (movement in the direction indicated by arrow C in the figure). Since the tie rod 21 is located at the rear of the lower arm 11, the above relative movement rotates the knuckle 3a and changes the toe-in and toe-out (toe-in: To, toe-out: Ti) of the tire 9.

In this way, the toe-in and toe-out characteristics change as the tire moves up and down.
In Figure a, when the position of the steering device 6 moves in the vertical direction, the position of the ball joint 21b of the tie rod 21 also moves in the vertical direction, so the arc A, which is the locus of the ball joint 21a, also changes, causing the tire to move up and down. Affects toe-in/toe-out characteristics. That is, it can be said that the mounting device of the steering device 6 is one of the major factors that influences the toe-in/toe-out characteristics of the tire.

The relationship between the vertical movement of the tire and the toe-in/toe-out characteristics has an effect on vehicle performance: when the tire moves upward (hereinafter referred to as a bump), the greater the toe-out, the better the stability, but the less responsiveness. tends to get worse. For this reason, for example, when using a manual steering system,
Due to the desire to reduce steering force, there is a constraint that the steering gear ratio cannot be made small and responsiveness cannot be improved very much.Since it is not desirable to sacrifice responsiveness, changes in toe-in/toe-out characteristics are minimized even when bumps occur. It is desirable to do so. However, when using the power steering system, reducing the steering gear ratio does not cause problems with operating force due to the power assist force, so the gear ratio is reduced to improve responsiveness and the toe-out is increased when bumping. It is desirable to set it to improve stability.

Conventionally, while taking these matters into consideration, the steering device was mounted at a position where the characteristics could be compromised between the manual steering system and the power steering system.

On the other hand, in addition to the desire to set toe-in and toe-out characteristics differently for manual steering and power steering, we have also responded to various customer requests, including cars with the same steering system that emphasize responsiveness. It would be very convenient if it were possible to easily create cars with different characteristics, such as cars that emphasize stability (so-called sporty cars), and cars with characteristics similar to quiet cars. There is also a strong demand for this.

In view of these circumstances, the present invention provides a rack and pinion type steering device that allows different toe-in and toe-out characteristics when the tires are up and down by simply changing the assembly direction (angle) of some parts. The purpose is to

In the rack and pinion type steering device of the present invention, tie rods are connected via ball joints to both ends of the rack bar that meshes with the pinion driven by the steering wheel, and the connection between the ball joint and the ends of the rack bar is This is a connection using a screw, and is characterized in that the center of the ball joint is displaced in a direction perpendicular to the center of the screw with respect to the center line of the screw.

According to the present invention, since the center of the ball joint is displaced from the center of the connecting screw between the rack bar and the ball joint, when the ball joint is rotated along the screw, the center of the ball joint is aligned with the center line of the screw. It forms a circular locus centered on the screw center line in a perpendicular plane. In other words, by adjusting the rotation angle (screwing amount) of the screw, the center of the ball joint can be set at any position on the circular trajectory mentioned above with respect to the rack bar, so the center position of the ball joint can be adjusted up or down. This means that the toe-in and toe-out characteristics can be set differently for each vehicle.

Therefore, for example, in a manual steering vehicle, the toe change at the time of a bump can be set small, and in a power steering vehicle, the toe out at the time of a bump can be set large, so that the requirements in both cases can be satisfied. Furthermore, even in cars with the same steering system, by setting different toe-in and toe-out characteristics, cars with excellent stability can be created.
It is possible to obtain a car with several different performance characteristics, such as a highly responsive car.

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

FIG. 3 is a perspective view of a rack and pinion type steering device according to an embodiment of the present invention, and shows an example of a power steering system. Figure 4 shows the third
FIG. 4 is a sectional view of the device shown in the figure taken along a horizontal plane passing through the rack bar, and will be described with reference to FIGS. 3 and 4; FIG. In addition, in FIG. 4, only both ends of the tie rods 36 and 37 are shown in a front view.

When the steering wheel 7 is operated, the shafts 8, 8 connected thereto are driven, and the rotation of the shaft 8 is transmitted to the steering device 30. Within this steering device, a pinion 39 directly connected to the shaft 8 is rotated. The pinion 39 meshes with the rack 38a of the rack bar 38, and the rack bar 38 is connected to the tie rod 3 via ball joints 40, 40 at both ends thereof.
6 and 37, and ball joints 36a and 37a are provided at the tips of the tie rods 36 and 37, respectively.
is connected to the arm of a knuckle arm (not shown). Therefore, when the pinion 39 is turned,
The rack bar 38 is moved in the length direction (left and right direction of the vehicle) due to the rack 38a meshing with this, and the tie rods 36, 37 connected thereto are moved.
The vehicle body is also moved left and right, and steering is performed by turning the nut. Pinion 39 and rack bar 3
8 is guided and held in the steering gear case 34 so as to be able to move freely, and is fixed to the vehicle body (not shown) by attachment means 41a and 41b.

Note that the ball joint 40 is the ball part 40
a and a ball receiver 40b, the ball part 40a
is fixed to the ends of the tie rods 36 and 37 (or is integrally formed with the tie rods), and has a screw 40c on the opposite side of the ball receiver 40b to the side that contacts the ball portion 40a. It is screwed together.

In addition, the steering device 30 also includes piping 32a, 3
The hydraulic pump 31 is connected to the hydraulic pump 31 via the piping 32a or 3b, and the hydraulic oil discharged when the hydraulic pump 31 is driven by an engine (not shown) is delivered to the piping 32a or 3.
2b to the steering device 30.
This pressure oil is selectively sent to the tube 33a or tube 33b by a control valve 35 built into the steering device 30, depending on the direction of rotation of the steering wheel 7 (ie, shaft 8). On the other hand, a space is provided between the steering case 34 and the rack bar 38, and this space is divided into two by a piston 38c fixed to the rack bar 38.
Two oil chambers 38d and 38e are formed. The oil chambers 38d and 38e are tubes 33a and 33, respectively.
b, and when the steering wheel 7 is operated clockwise, the rack bar 38 is moved to the left in the figure. At this time, the control valve 35 moves the oil chamber 3 through the tube 33b.
Pressure oil is sent to 8e, and the piston 38c fixed to the rack bar 38 is pushed leftward in the figure by this oil pressure, thereby providing an assisting force. When the steering wheel 7 is operated counterclockwise, pressurized oil is sent to the oil chamber 38d, and an assist force in the right direction is obtained in the same manner as described above.

In the steering device configured in this way, the ball portion 40a of the ball joint 40 that connects the rack bar 38 and the tie rods 36, 37 is
The center and the center line of the threaded portion 40c of the ball receiver 40b are eccentric, and this portion will be explained using FIG. 5.

FIG. 5 is a sectional view showing the ball joint 40. However, the ball portion 40a and the tie rod 37 connected thereto are not shown in cross section. The ball joint 40 consists of a ball part 40a and a ball receiver 40b, and a screw 40c is provided on the opposite side of the ball receiver 40b to the side that contacts the ball part 40a.
and a rack bar 38 are coupled. Note that a lock nut 42 is placed between the ball receiver 40b and the rack bar 38, and is screwed into the screw 40c.
0b can be fixed to the rack bar 38 at any desired screwing position. Displacement in a direction perpendicular to the center line of the screw 40c (displacement amount:
e) A ball portion 40a is formed at the center of the tie rod 37, and this ball portion 40a is fixed to the tie rod 37 (or is integrally molded with the tie rod).
For this reason, the ball joint 40 is connected to the rack bar 3.
8, the ball portion 40a moves up and down relative to the rack bar 38 by a maximum of 2e.

FIGS. 6a to 6d are diagrams showing the positional relationship between the center of the ball portion 40a and the center of the screw 40c, and the upper side in the figures is shown as the upper side of the vehicle body.

FIG. 6a is a sectional view of the ball joint 40 when the center B of the ball joint 40 is located at the lowest position with respect to the center line A of the screw 40c, and the centers A and B are located on the right side. Fig. 6b is a right side view when viewed from above. Center B of ball portion 40a
is located below the screw center A by a dimension "e". Next, rotate the ball joint 90 degrees, and the 6th
As shown in Figure 6d, the ball center B and the screw center A are at the same position in the vertical direction, and when the ball joint is rotated 180 degrees, the ball center B and the screw center A are at the same position in the vertical direction as shown in Figure 6d.
is located above the screw center A by a dimension "e". In this manner, the center of the ball joint can be set at any position within the range of dimension "e" in the vertical direction with respect to the rack bar 38.

Therefore, the position of the connecting ball joint 21b between the tie rod and the rack bar shown in FIGS. 1, 2a and 2b can be moved up and down, and the toe-in/toe-out characteristics can be changed.

Here, at the ball joint positions shown in FIGS. 6b to 6d, toe-in and toe-out characteristics can be expressed as characteristic examples as shown by lines b to d in FIG. 7, respectively.
In the graph of Fig. 7, the (+) side of the vertical axis shows the toe-out amount To, the (-) side shows the toe-in amount Ti, and the (+) side of the horizontal axis shows the bump amount (the amount of upward movement of the tire). The rebound amount (the amount of downward movement of the tire) is shown on the (-) side.

In this case, for example, the installation position of the ball joint that has the characteristic of line c is set in the manual steering vehicle to reduce toe change when bumping, and the installation position of the ball joint that has the characteristic of line b is set in the manual steering vehicle. It can be set on the steering vehicle to increase the amount of toe-out during bumps and increase stability.

Furthermore, even in cars with the same steering system, the toe-in/toe-out characteristics can be set to line a, line b, or line c at any time during assembly. (characteristics of line b), car with normal characteristics (characteristics of line c)
Alternatively, it is possible to obtain cars with different characteristics for each car, such as a car with sporty (good responsiveness) characteristics (characteristics of line d).

As explained above, according to the present invention, it is possible to change the toe-in/toe-out characteristics of a car simply by changing the assembly direction of the ball joint that connects the rack bar and tie rod. This is convenient because it allows you to set different toe-in and toe-out characteristics depending on the characteristics of each car, and to set different toe-in and toe-out characteristics for cars with the same steering system.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the suspension and steering section of a front-wheel drive vehicle, FIGS. 2a and 2b are schematic diagrams schematically showing the suspension and steering section, and FIG. 2a is a front view; Figure 2b is a plan view. Fig. 3 is a perspective view of a rack and pinion type steering device according to an embodiment of the present invention, Fig. 4 is a sectional view of the steering device of Fig. 3 taken along a horizontal plane passing through the rack bar, and Fig. 5 shows the combination of the rack bar and tie rod. Figures 6a to 6d are cross-sectional views of the ball joint in Figure 5 and diagrams showing the positional relationship between the screw center and the ball center in this ball joint. 6d from the figure
The figure is a view of the sectional view of FIG. 6a viewed from the right side.
FIG. 7 is a graph showing an example of changes in toe-in/toe-out characteristics at the ball joint assembly positions shown in FIGS. 6b to 6d. 7... Steering wheel, 11, 12...
Lower arm, 21, 22...Tie rod, 30
... Steering device, 31 ... Hydraulic pump, 3
4... Steering gear case, 35... Control valve, 36, 37... Tie rod, 38
...Rack bar, 39...Pinion, 40...Ball joint, 40a...Ball part, 40b...
...Ball receiver, 40c...Thread part, A...Screw center line, B...Ball part center.

Claims (1)

[Scope of utility model registration request] A pinion that is rotationally driven by the operation of the steering wheel, a rack bar that meshes with the pinion and is moved in the longitudinal direction, a pair of tie rods that work in conjunction with this rack bar and transmit the movement of this rack bar to the left and right tires, and both ends of the rack bar are connected to the ends of the rack bar. and the tie rod end, respectively, to pivotally connect the rack bar and the tie rod, and the ball joint and the rack bar end are coupled by a screw means, and the screw means A rack and pinion type steering device, wherein the ball joint is formed by displacing the center of the ball joint in a direction perpendicular to the center line of the screw.