JPH0732330Y2 - Power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a power steering apparatus for an automobile.

<Prior art> In an automobile power steering apparatus, in an integral type or a semi-integral power steering, a cylindrical input shaft that is rotated by a steering wheel operation and a ball screw coaxially provided on the input shaft are provided. A torsion bar having one end fixed to the inner circumference of the ball screw and the other end fixed to the inner circumference of the input shaft to elastically connect the input shaft and the ball screw, and a shaft screwed to the ball screw via the ball. A ball nut piston that moves in the direction, a cross shaft having a sector gear that meshes with rack teeth formed on the ball nut piston, a side cover that surrounds the cross shaft, and surrounds the ball nut piston,
In addition, a gear housing which communicates with the inside of the side cover and also serves as a power cylinder having oil chambers formed on the left and right of the ball nut piston, and an oil chamber of the power cylinder, which is provided in a valve housing fixed to the gear housing, respectively A servo valve for controlling the supply and discharge of pressure oil via a flow path, and an end cover fixed to the upper end of the side cover and bearing the upper end of the cross shaft are provided.

<Problems to be Solved by the Invention> In the above-mentioned conventional device, as shown in FIG. 5, an oil flow path for connecting the servo valve side oil chamber and the servo valve in the left and right oil chambers of the ball nut piston. Reference numeral 15 communicates with the side portion of the side cover 2a substantially parallel to the axis of the power cylinder.
In FIG. 5, 1 is a valve housing, 2 is a gear housing, and 3 is a power cylinder.

By the way, when this device is mounted on an automobile, it is mounted at an angle θ of about 24 ° with the valve housing 1 side facing upward. Therefore, even when the air A1 and A2 are accumulated in the upper part of the side cover 2a and the upper part of the oil chamber on the servo valve side of the power cylinder 3, the oil is supplied to and discharged from both oil chambers of the power cylinder by the handle operation. The air A1 and A2 do not come out, and the followability of the steering wheel is poor.

<Means for Solving Problems> The present invention solves the above problems. The gist of the present invention is that the oil of the cylinder located on the servo valve side with respect to the servo valve and the ball nut piston is An oil passage communicating with the chamber is located at an upper position when mounted on the vehicle body. A first oil passage communicating between an upper end in the side cover and the servo valve, and a cylinder located at an upper portion when mounted on the vehicle body. The second oil passage is configured to connect the upper end of the oil chamber and the upper end of the side cover.

<Operation> With the above configuration, by the operation of the servo valve, oil is supplied to and discharged from the cylinder oil chamber located on the servo valve side with respect to the ball nut piston by the first oil flow path and the second oil flow path.
Since it is performed via the upper end in the side cover in the state of being attached to the vehicle body, the air accumulated in the upper end in the side cover and the upper end of the cylinder oil chamber is discharged by supplying and discharging the oil to the cylinder oil chamber.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a valve housing, which is a rotary servo valve.
23 built-in. A gear housing 2 is fixed to the valve housing 1. This gear housing 2
Also serves as the power cylinder 3, and the valve housing 1
A ball screw 4 rotatably held in the power cylinder 3 faces the power cylinder 3. Reference numeral 16 is a cylindrical input shaft, which is provided coaxially with the ball screw 4 and is connected to a steering shaft (not shown). Reference numeral 6 denotes a torsion bar, one end of which is fixed to the inner circumference of the ball screw 4 and the other end of which is fixed to the inner circumference of the input shaft 16. Reference numeral 5 is a male screw groove provided in the ball screw 4. 8 is a ball nut piston,
The power cylinder 3 is slidably fitted in the power cylinder 3 to form a left oil chamber 3a and a right oil chamber 3b.

A female screw groove 9 is provided on the inner diameter of the ball nut piston 8, and the female screw groove 9 and the male screw groove 5 of the ball screw 4 are provided.
A large number of balls 10 are fitted between the balls 10 and, and the ball nut piston 8 is screwed onto the ball screw 4 via the balls 10.

The ball 10 circulates through a ball tube (not shown) by the rotation of the ball screw 4, and moves the ball nut piston 8 left and right in the axial direction.

Rack teeth 12 are formed on the ball nut piston 8, and a sector gear 13 provided on a cross shaft 14 meshes with the rack teeth 12. The cross shaft 14 is connected to the steered wheels via a pit unarm (not shown).

2a is a side cover surrounding the cross shaft 14,
The inside of the side cover 2a is open to the right oil chamber 3b on the valve housing 1 side. Then, as shown in FIG. 2, an end cover 20 is fixed to the upper end of the side cover 2a, and the upper end of the cross shaft 14 is supported by the end cover 20.

The oil flow passage that connects the right oil chamber 3b and the servo valve 23 is, as shown in FIG. 2 to FIG. 4, the first oil passage that connects the servo valve 23 built in the valve housing 1 and the upper portion of the side cover 2a. It is composed of a first oil flow passage 21 and a second oil flow passage 22 that connects the upper part of the side cover 2a and the upper part of the power cylinder 3 of the right oil chamber 3b. The left oil chamber 3a and the servo valve 23 are connected by a third oil passage 24 as shown in FIG.

Further, the valve housing 1 is provided with a supply port 25 for supplying pressure oil to the servo valve 23 and a discharge port 26 for discharging pressure oil.

The operation will be described based on the configuration described above. When the handle is in the neutral position, the pressure oil supplied from the supply port 25 is distributed to the left oil chamber 3a and the right oil chamber 3b by the servo valve 23, so that the ball nut piston 8 is in the neutral position. Hold. For example, when the handle is turned to the right, the input shaft 16 rotates to the right, and the operation of the servo valve 23 causes the pressure oil to move to the third oil passage 24.
Through the left oil chamber 3a, and the fluid in the right oil chamber 3b passes through the second oil passage 22, the first oil passage 21, the servo valve 23, and the discharge port 26.
Drained from. As a result, a pressure difference occurs between the left oil chamber 3a and the right oil chamber 3b, and the ball nut piston 8 produces an operating force to the right in FIG. 1, which assists the rotational force of the input shaft 16 to move the cross shaft 14 Turn clockwise.

As described above, in the present invention, oil is supplied to and discharged from the right oil chamber 3b of the power cylinder 3 by the first oil passage 21 and the second oil passage 22 via the upper portion of the side cover 2a. Therefore, even if this device is mounted on an automobile at an inclination angle with the valve housing 1 side facing upward, if air is accumulated in the upper part of the side cover 2a and the upper part of the right oil chamber 3b by this, this air will not be oiled. When it flows out, it is discharged to the servo valve 23 side together, and air does not remain.

In the illustrated example, the first and second oil passages 21 and 22 are the valve housing 1,
Although the structure is provided within the thickness of the gear housing 2 and the side cover 2a, it is also possible to connect them by a tube outside them.

<Effect of the Invention> Therefore, according to the present invention, the oil is supplied to and discharged from the cylinder oil chamber by the operation of the servo valve, so that the upper end of the side cover and the upper end of the cylinder oil chamber located in the upper portion when mounted on the vehicle body are oiled. Since the air is circulated, the accumulation of air at the upper end in the side cover and the upper end of the cylinder oil chamber is prevented, which has the effect of eliminating adverse effects on the operation of the handle and improving the followability of the handle.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a main part view of the device of the present invention, FIG. 2 is a side view, FIG. 3 is a view on arrow II of FIG. 2, and FIG. 4 is of FIG. FIG. 5 and FIG. 5 are views for explaining conventional problems. 1 ... Valve housing, 2 ... Gear housing, 2a ... Side cover, 3 ... Power cylinder, 3a, 3b ... Oil chamber, 4 ... Ball screw, 6 ... Torsion bar, 8 ... Ball nut piston, 10 ... Ball, 12 ... Rack tooth , 13 ... Sector gear, 14 ...
Cross shaft, 16 ... Input shaft, 21 ... First oil passage, 20 ... End cover, 22 ... Second oil passage.

Continuation of the front page (56) Reference JP-A-58-16960 (JP, A) JP-A-50-114735 (JP, A) JP-A-50-20430 (JP, A) JP-A-60-131369 (JP , A) Actually open 59-128470 (JP, U) Actually open 57-70974 (JP, U) Japanese public Sho 49-1809 (JP, B1) Japanese public 52-39530 (JP, B2) Japanese public Sho 62-11259 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A cylindrical input shaft that rotates by operating a handle, a ball screw provided coaxially with the input shaft, one end fixed to the inner circumference of the ball screw and the other end fixed to the inner circumference of the input shaft. A torsion bar that elastically connects the input shaft and a ball screw, a ball nut piston that is screwed to the ball screw via a ball and moves in the axial direction, and meshes with rack teeth formed on the ball nut piston. A cross shaft having a sector gear, a side cover surrounding the cross shaft, a gear housing that surrounds the ball nut piston and communicates with the inside of the side cover, and a power cylinder having oil chambers formed on both sides of the ball nut piston. , Provided in a valve housing fixed to the gear housing, respectively in the oil chamber of the power cylinder. In a power steering apparatus including a servo valve for controlling the supply and discharge of pressure oil via an oil flow path, and an end cover fixed to the side cover and bearing an end portion of the cross shaft, the servo valve and An oil passage communicating with an oil chamber of a cylinder located on the servo valve side with respect to the ball nut piston communicates with an upper end of the side cover located at an upper portion in a state of being attached to a vehicle body and the servo valve. And a second oil flow passage that communicates the upper end of the cylinder oil chamber located at the upper portion with the upper end in the side cover when mounted on the vehicle body. Steering device.