JPS5897561A - Rack and pinion type power steering - Google Patents

Abstract

PURPOSE:To make it possible to obtain a joint-to-joint distance necessary for minimizing toe variation, by connecting one joint to the opposite end of a cylinder and the other joint to an intermediate position between the cylinder and a rack. CONSTITUTION:A rack 27 moves in either one of directions when a pinion 29 is rotated by turning a steering wheel 31. For example, when the rack 27 moves to the left, high pressure is fed to a right cylinder chamber 40B, and therefore, a piston rod 22 moves to the left while being subjected to power assist due to hydraulic pressure. Thereby side rods 26A, 26B which are connected to the pison rod 22 through ball joints 25A, 25B displace to the left, identically, for changing the direction of wheels. In this case, the joint-to-joint distance A0 is not the distance between both projecting ends of the cylinder 22, but one joint is connected to the one end of the cylinder and the other joint is connected to an intermediate position between a cylinder part 30 and the rack 27 so that the joint-to- joint distance A0 may be easily set in an optimum distance for minimizing toe variation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power steering for rack-and-binion vehicles.

Power steering, which uses hydraulic power to assist in reducing the steering force of a vehicle, is known.
The figure shows semi-integral power steering.

1 is a steering wheel, 2 is a steering gear part with a power cylinder inside, 3 is a pitman arm,
4 is a cross rod, 5 is an idler arm, and the cross rod 4 has knuckle arms 8 of the left and right wheels 7A and 7B.
Side rods 9A and 9B are connected via a ball joint 1o.

When the steering wheel 1 is rotated, a control valve (not shown) switches, sends pressure oil to a power cylinder inside the steering gear section 2, power assists gear rotation, and changes the angle of the pitman arm 3.

As a result, the cross slot 4 is displaced to the left or right, the side rods 9A and 9B are similarly displaced in parallel, and the knuckle arm 8 is rotated to rotate the wheel 7A.

The direction of 7B is changed in the same direction.

In addition, in the case of manual steering, there is no power cylinder inside the steering gear part 2;
Others are configured in exactly the same way.

By the way, in such a steering linkage, both ball joints 10 are used in order to minimize toe changes during wheel bounce and rebound due to the layout of the suspension and tension rods (not shown).
As is already well known, it is extremely important to ensure the optimum distance A for the vehicle, especially from the perspective of ensuring the straightness of the vehicle! It is.

In this regard, in the power steering system shown in FIG. 1, the predetermined dimension A can be easily secured because the link system has a high degree of freedom in design.

However, in the rack-and-binion type power steering shown in FIG. 2, it is extremely difficult to secure this optimum dimension A for the following reasons.

In the figure, reference numeral 11 denotes a rack-and-binion type power actuator, in which side rods 9A and 9B are connected via pole joints 10 to the ends of left and right ends 12A and 12B.

Rotation of the steering wheel 1 is transmitted to the rack and pinion gear section 14 via the universal joint 13,
Along with this, a control valve (not shown) switches, pressure oil is sent to the power actuator (cylinder part) 11, pistons (not shown) connected to the rods 12A and 12B are displaced, and the rods 12A and 12B are integrally moved to the left. Alternatively, the wheels 7A and 7B may be displaced to the right to change the direction of the wheels 7A, 7B.

However, in this way, when output is taken out from both ends of the rod 12A112B, the distance between the joints A
At present, it is difficult to obtain an appropriate value for A1, and the dimension A1 becomes larger than this, resulting in a large toe change during bounce and rebound, and the straightness is impaired.

On the other hand, there is a method called "central take-off" in which the output is taken out from the center of the actuator 11 as shown in FIG. Since the mounting part of the ball joint 10 is placed in the center of the piston rod 18 to be connected, the distance between the joints becomes short to A2, and in order to minimize the toe change, it is necessary to use the rack-and-binion type power actuator 11. There was a WRIII in which the layout position of the system was significantly restricted.

An object of the present invention is to ensure an appropriate distance between joints in rack-and-binion type power steering.

In the present invention, the side rod of one wheel, that is, the output take-out part, is ball jointed to the piston rod between the rack and the cylinder, and the other side rod is ball jointed to the rod protruding from the opposite side of the cylinder. By joining, it is possible to maintain an appropriate distance between both joints.

Hereinafter, embodiments of the present invention will be described based on FIG. 4.

The rack-and-binion hydraulic actuator 20 has two bearings 24 inside the cylinder tube 21.
The piston 2 is attached to the piston rod 22 that passes through A and 24B.
3 is fixed and constitutes the output cylinder section 30. The protruding side 22A of the piston rod 22 has a pole shim ind 25.
One output output side rod 26A is connected to the opposite side 22B of the piston rod 22, that is, the rack 27, through a ball joint 25B. Link.

A rack 27 carved into the end of the piston rod 22
is housed inside a gear housing 28 coaxially connected to the cylinder tube 21, and is connected to the steering wheel 3.
It meshes with the pinion 29 connected to 1.

The gear housing 28 is connected to the vehicle body frame 33 via bolts 32, and the cylinder tube 21 is also connected to the vehicle body frame via a bracket 34.

The cylinder tube 21 has the ball joint 25
A cutout window 36 is formed in the axial direction at the portion where B connects to the piston rod 22.

The end of the piston rod 22 and this notch window 36
Furthermore, the opening end of the gear housing 28 is provided with bellows-shaped boots 37A, 37B made of rubber, respectively.
37C coated.

In addition, 39A and 39B in the figure are cylinder chambers 40A.

This is a hydraulic oil supply/discharge port for 40B.

Accordingly, when the steering wheel 31 is turned to rotate the pinion 29, the rack 27 moves to either side, and at this time, the control valve (not shown) switches to supply high pressure to either the cylinder chamber 40A or 40B. , connect the other end to the low pressure tank side.

For example, when the rack 27 is displaced to the left, high pressure is supplied to the right cylinder chamber 40B, and the piston rod 22 moves to the left while receiving power assistance from hydraulic pressure.

Thereby, the side rods 26A, 2 connected to the piston rod 22 via the ball joints 25A, 25B.
6B is equally displaced to the left, changing the direction of the wheels.

By the way, in this case, the distance A between the ball joints 25A and 25B that take out the output is not between the two protruding ends of the piston rod 22, but between one end and the other between the cylinder part 30 and the rack 27. This makes it easy to set the optimum distance to minimize toe change.

That is, instead of extracting the output from both ends of the piston rod as in the conventional figure 2, or as in figure 3,
Since both outputs are not extracted from between the ring section and the rack, the distance between the joints can be set appropriately without being too long or too short.

As described above, according to the present invention, the output ends of the side rods are connected to the piston rod, one at the opposite end of the cylinder, and the other between the cylinder and the rack, thereby minimizing tow change. This has the effect of providing a lightweight and affordable power steering system that allows the vehicle to move in a straight line with high straightness.

[Brief explanation of drawings]

1 to 3 are configuration diagrams showing a conventional steering linkage, and FIG. 4 is a sectional view showing an embodiment of the present invention. 21...Cylinder tube, 22 River piston rod,
23... Piston, 25A, 25B... Ball joint, 26A, 26B... Side rod, 27...
- Rack, 28... Gear housing, 29... Pinion, 30... Output cylinder section, 31... Steering wheel, 33... Body frame, 37A, 37
B. 37G...boots.

Claims (1)

[Claims] A rack is formed at one end of the piston rod of the output cylinder section attached to the vehicle body, and a pinion connected to the steering wheel is engaged with this rack, and the pinion selected for the output cylinder section is passed through a control pulp that switches as the input rotation of the pinion rotates. In a rack-and-binion type power steering system that supplies and discharges pressurized oil, the output take-off part for one wheel side is placed at one end of a piston rond that protrudes from the output cylinder part, and the output take-off part for the other wheel side is placed at one end of the piston rond that protrudes from the output cylinder part. A rack-and-binion type power steering system characterized in that a piston rod is connected to a piston rod via a ball joint between an output cylinder portion on the opposite side of the end and a rack.