JPH05310139A - Power steering - Google Patents

Abstract

PURPOSE:To lighten the weight of a power steering and shorten its whole axial length by providing a spool valve which is provided outside of a power cylinder and controls the supply/exhaust of the pressure oil to/from the oil chamber of the power cylinder and an axial groove on the outside cylindrical surface of a ball nut, and fixing a pin to the spool of the spool valve so as to engage this pin with the groove. CONSTITUTION:When a ball screw 27 is rotated by a steering shaft, a ball nut 25 is also rotated in the same direction as that of the ball screw 27. By this way, the spool 32 of a spool valve 31 is moved axially via a pin 33 engaged with the groove 30 of the ball nut 25, and the pressure oil is supply-exhaust controlled against the left chamber 34a and the right chamber 34b of a power cylinder 20 so as to operate a piston 21 into the left or right direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile power steering system.

[0002]

2. Description of the Related Art As shown in FIGS. 3 and 4, an integral type power tearing system that controls suction and discharge of pressure oil by a spool valve has a power cylinder 1 and a gear housing 2 integral with the power cylinder 1. A piston 3 is slidably fitted in the power cylinder 1, and the piston 3 divides the power cylinder 1 into a left chamber 4a and a right chamber 4b.

A nut 5 having a female screw groove 6 is integrally coupled to the piston 3 in the axial direction while allowing rotation, and is rotated by a steering shaft and corresponds to the ball screw shaft 7 having a male screw groove 8 and the male screw groove 8. It is screwed through balls 9 which circulate while rolling between the female screw grooves 6.

Further, a sleeve 11 is integrally attached to the nut 5 in the axial direction while allowing the rotation of the nut 5.
Rack teeth 10 are provided on the outer peripheral surface of the sleeve 11, and the sector gear 13 formed on the cross shaft 12 and the rack teeth 10 are meshed with each other. The sleeve 11 and the sector gear 13 are surrounded by the gear housing 2.

Reference numeral 14 is a spool valve, and an arm 16 provided on the nut 5 is engaged with the spool 15. In this spool valve 14, the ball screw shaft 7 is rotated by the handle operation, and the nut 5 is rotated in the same direction as this, whereby the arm 16 moves the spool 16 to transfer the pressure oil to the left and right chambers 4a, 4b of the power cylinder 1. Supply and discharge control.

[0006]

In the above conventional structure,
Since the piston 3, the nut 5, and the sleeve 11 are arranged in series on the same axis, there is a problem that the overall length in the axial direction becomes long and the size becomes large, and the weight also increases.

An object of the present invention is to provide a power steering system that solves the above-mentioned conventional problems.

[0008]

The object of the present invention to achieve the above object is to provide a ball screw which is rotated by a steering shaft and has a male screw groove, and a female screw groove corresponding to the male screw groove. A piston that has a built-in ball nut that moves in the axial direction through a ball that circulates while rolling between the female thread groove and the male thread groove,
A cross shaft provided with a sector gear that meshes with rack teeth formed on this piston, a power cylinder that also serves as a gear housing that surrounds the piston and the sector gear and forms oil chambers on the left and right of the piston, and the outside of this power cylinder. And a spool valve for controlling the supply and discharge of pressure oil to the oil chamber of the power cylinder, an axial groove is provided on the outer diameter surface of the ball nut, and a pin is fixed to the spool of the spool valve. A pin is engaged with the groove.

[0009]

With the above structure, the ball nut built in the piston is engaged with the pin protruding from the spool valve side, and the rotation of the ball nut is transmitted to the spool through the pin to control the supply and discharge of the pressure oil. This makes it possible to reduce the overall length in the axial direction and reduce the weight.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 20 is a power cylinder that also serves as a gear housing. A piston 21 is slidably fitted in the power cylinder 20.
1 is provided with rack teeth 22 and meshes with a sector gear 24 of a cross shaft 23.

A ball nut 25 having a female screw groove 26 is assembled in the piston 21 in a state where the ball nut 25 is allowed to rotate and is fitted therein, and a ball screw 2 having a male screw groove 28.
7 and the ball 29 are screwed together.

The ball screw 27 is connected to a steering shaft (not shown) and rotated by the steering shaft, and the ball 29 circulates while rolling between the female screw groove 26 and the male screw groove 28.

An axial groove 30 is provided on the outer peripheral surface of the ball nut 25, and the left chamber 34a and the right chamber of the power cylinder 20 are defined by the piston 21 in the gear housing at a position corresponding to the groove 30. A spool valve 31 for controlling the supply and discharge of the pressure oil is installed on 34b, and a pin 33 driven into the spool 32 of this spool valve 31 is engaged with the groove 30 of the ball nut 25.

Since the present invention has the above-described structure, when the ball screw 27 is rotated by the steering shaft (not shown), the ball nut 25 is also rotated in the same direction. Thereby, the pin 33 engaged with the groove 30 of the ball nut 25
The spool 32 of the spool valve 31 is axially moved via the control valve to control the pressure oil to be supplied to and discharged from the left chamber 34a and the right chamber 34b of the power cylinder 20, and the piston 21 is operated leftward or rightward.

[0015]

As described above, according to the present invention, the piston itself is provided with the rack that meshes with the sector gear of the cross shaft, the ball nut is built in the piston, and the axial groove is provided on the outer peripheral surface of the ball nut. Since the pin fixed to the spool of the spool valve provided in the gear housing is engaged with the groove of the ball nut, the overall length of the power cylinder in the axial direction is shortened, and the power steering is made compact and lightweight. ..

Further, with the above construction, it is possible to increase the diameter of the power cylinder, and the power receiving area of the piston can be increased thereby to increase the power.

[Brief description of drawings]

FIG. 1 is a sectional view of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a conventional cross-sectional view.

FIG. 4 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 20 Power Cylinder 21 Piston 22 Rack Teeth 23 Cross Shaft 24 Sector Gear 25 Bolnut 26 Female Thread Groove 27 Ball Screw 28 Male Thread Groove 29 Ball 30 Groove 31 Spool Valve 32 Spool 33 Pin

Claims (1)

[Claims] 1. A ball screw which is rotated by a steering shaft and has a male thread groove, and a female thread groove corresponding to the male thread groove. The ball screw is rotatably circulated while rolling between the female thread groove and the male thread groove. A piston with a built-in ball nut that moves to the shaft, a cross shaft with a sector gear that meshes with the rack teeth formed on this piston, a gear housing that encloses the piston and the sector gear, and forms an oil chamber on the left and right of the piston. A dual-purpose power cylinder; and a spool valve provided outside the power cylinder for controlling the supply and discharge of pressure oil to and from the oil chamber of the power cylinder, wherein an axial groove is provided on the outer diameter surface of the ball nut, A power steering characterized in that a pin is fixed to a spool of a spool valve and the pin is engaged with the groove. ..