JPH0221343Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is mainly applicable to automobiles, in which a power cylinder for hydraulically driving the rack rod is connected to one end of a steering gear box that supports a pinion shaft and a rack rod that mesh with each other. The present invention relates to a power steering device used.

In conventional power steering devices, the power cylinder is coupled to the steering gear box by welding a mounting flange to the outer cylinder body of the power cylinder and fixing this mounting flange to the steering gear box via bolts. However, such a joint structure is relatively complex and difficult to assemble, and in order to coaxially align the steering gear box and power cylinder, high machining accuracy is required for the joint, making the overall As a result, high costs cannot be avoided.

In addition, in the conventional device described above, a communication path that communicates between the hydraulic control circuit that supplies and discharges hydraulic oil to and from the power cylinder and the inside of the power cylinder is machined to be bored in the steering gear box.
The shape of the communication passage is limited, and there are also problems such as a small degree of freedom in arranging the communication passage within the limited space of the steering gear box.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a power steering device that can solve all of the above problems of conventional devices.

In order to achieve this object, the present invention provides a power steering system in which a power cylinder for hydraulically driving the rack rod is connected to one end of a steering gear box that supports a pinion shaft and a rack rod that mesh with each other. In the device, the steering gear box is made of die-casting, and an end of the cylinder body of the power cylinder and a communication pipe fixed to the end and having one end opening inside the cylinder body are cast-in and joined to the steering gear box. The other end of the communication pipe is characterized in that a hydraulic control circuit is connected to supply and discharge hydraulic oil into the power cylinder.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a steering gear box fixed to a vehicle body (not shown), and a pinion that extends upwardly. The shaft 4 is rotatably supported through a pair of upper and lower bearings 5, 5', and a rack 3a of the rack rod 3 and a pinion 4a of the pinion shaft 4 are meshed inside the shaft 4. The pinion shaft 4 is rotated by a steering handle (not shown), and the rack rod 3 is driven by the pinion shaft 4 to move left and right, thereby turning a steering wheel (not shown).

The steering gear box 1 is made of Al alloy and die-cast. During casting, a power cylinder 10 for hydraulically driving the rack rod 3 is connected to the cylindrical portion 1a at the left end in the following manner.

That is, the power cylinder 10 includes an inner cylinder body 11 in which a rack rod 3 runs longitudinally, an outer cylinder body 12 that surrounds the inner cylinder body 11 with a cylindrical oil passage 13, and a cylinder fixed to the rack rod 3. The operating piston 14 slides inside the inner cylinder main body 11, and the operating piston 14 moves inside the inner cylinder main body 11 into a right chamber A on the steering gear box 1 side and a left chamber B on the opposite side. Classified into The right end of the outer cylinder main body 12 consists of a medium diameter part 12a and a small diameter part 12b that are narrowed in stages toward the tip, and the small diameter part 12b has a bearing that surrounds the rack 3a and enters the right chamber A. The right end of the cylinder 15 is fitted in an oil-tight manner, and a cap 16 having an inward stopper flange 16a that supports the right end surface of the bearing cylinder 15 is fitted and welded to the outer periphery of the small diameter part 12b. Ru. At the left end of the bearing sleeve 15, a bearing bush 17 and a seal member 18 are mounted which slidably support the intermediate portion of the rack 3a.

A support tube 11a at the right end of the inner cylinder body 11 is oil-tightly fitted into the middle diameter portion 12a of the outer cylinder body 12, and this support tube 11a is locked onto the bearing sleeve 15 via a stop ring 19.

A bearing cap 20 is fixed to the left end of the outer cylinder body 12, and a bearing bush 21 and a seal member 22 that slidably support the left end of the rack rod 3 are attached to this. Bearing cap 2
0 and the left end surface of the inner cylinder body 11,
A coil spring 23 that floats and supports the left end of the cylinder body 11 is compressed, and the inner cylinder body 11 passes through the gap between the wires of this coil spring 23.
The left ventricle B communicates with the cylindrical oil passage 13. Further, the coil spring 23 uses its elastic force to
The locked state between 1a and the retaining ring 19 is maintained.

A control valve 25 for controlling the operation of the power cylinder 10 is installed on the lower surface of the steering gear box 1. This control valve 25 has a hydraulic power source 26 such as a hydraulic pump installed in its valve box.
A high pressure port 27h connected to the oil reservoir 28, a low pressure port 27l connected to the oil reservoir 28, and a pair of output ports 29a, 2
9b, when the rack rod 3 is driven from the pinion shaft 4, it senses the driving force and depending on the magnitude of the driving force, either one of the output ports 29a, 29b is connected to the high pressure port 27h, and the other is connected to the high pressure port 27h. are connected to the low pressure port 27l, respectively.
The control valve 25, the oil pressure source 26 and the oil reservoir 28
and the oil passages that connect them together constitute the hydraulic control circuit C of the present invention.

A pair of communication pipes 30a, 30b each having one end open to the right chamber A and the cylindrical oil passage 13 are welded to the right end of the outer cylinder main body 12, and the other ends of the communication pipes 30a, 30b are , are respectively connected to the pair of output ports 29a and 29b.

Thus, the right end of the outer cylinder body 12, the cap 16 and the communication pipe 30 welded thereto
When the steering gear box 1 is die-cast, the members a and 30b are cast into the cylindrical portion 1a and joined together. At this time, the opening of the cap 16 is closed with a core so that the molten metal forming the gear box 1 does not penetrate into the outer cylinder body 12. The cap 16 and the communication pipes 30a and 30b exert an anchoring effect to strengthen the connection between the gear box 1 and the outer cylinder body 12.

In the above configuration, when the operator rotates the pinion shaft 4 clockwise using a steering handle (not shown), the control valve 25 is actuated and one of the output ports 29
a is connected to the high pressure port 27h, and the other output port 29b is connected to the low pressure port 27l, and the pressure oil of the hydraulic source 26 is communicated from the output port 29a to the communication pipe 3.
It flows into the right chamber A of the inner cylinder main body 11 through 0a and pushes the operating piston 14 to the left, and the pushing force assists the operator's operating force applied to the rack lever 3 via the pinion shaft 4. Therefore, the rack lever 3 can be easily moved to the left. As the actuating piston 14 moves to the left, the oil in the left chamber B of the inner cylinder body 11 passes through the gap between the wires of the coil spring 23 and flows into the cylindrical oil passage 13.
The oil is further discharged to the communication pipe 30b, the output port 29b, the low pressure port 27l, and the oil sump 28. When rotating the pinion shaft 4 counterclockwise, the control valve 25
The operating direction of the oil pressure source 26 is reversed to the above, and the oil flows in the opposite direction through the respective flow paths, that is, the pressure oil from the hydraulic source 26 flows through the output port 2.
The oil in the right chamber A flows into the cylindrical oil passage 13 from 9b and is discharged into the oil sump 28, allowing the rack lever 3 to be easily moved to the right.

As described above, according to the present invention, a power cylinder for hydraulically driving the rack rod is connected to one end of the steering gear box that supports the pinion shaft and the rack rod that mesh with each other. In the power steering device, the steering gear box is made of die-cast casting, and the end of the cylinder body of the power cylinder is cast-in and connected to the steering gear box, so that the steering gear box can be operated without using special connecting members such as mounting flanges or bolts. It is possible to connect the steering gear box and the power cylinder, so the structure is simple, and the conventional joining process can be omitted. By simply setting the cylinder body of the power cylinder in a fixed position, alignment of the two can be easily achieved, so that a highly accurate and inexpensive power steering device can be obtained.

Further, a communication pipe fixed to the end of the cylinder body of the power cylinder and having one end opened inside the cylinder body is also cast-in and coupled to the steering gear box, and the other end of the communication pipe is connected to the inside of the power cylinder. Since a hydraulic control circuit is connected to supply and discharge hydraulic oil to the cylinder body, by employing the above-mentioned communication pipe as a communication path between the hydraulic control circuit and the cylinder body, the power cylinder operation for the cast part of the steering gear box is controlled. Direct contact with oil is avoided, eliminating the risk of oil leakage due to cavities in the casting part, and the communication pipe itself is manufactured in a separate process before being cast into the steering gear box. Since the shape of the communication path can be selected relatively freely, the degree of freedom in arranging the communication path can be increased. Furthermore, the above-mentioned communication pipe exhibits an anchoring effect when it is cast into the steering gear box,
The strength of the connection between the steering gear box and the cylinder body can be significantly increased.

[Brief explanation of the drawing]

The drawing is a vertical cross-sectional rear view of one embodiment of the device of the present invention. A... Right ventricle, B... Left ventricle, C... Hydraulic control circuit, 1... Steering gear box, 3... Rack rod, 3a...
...Rack, 4...Pinion shaft, 4a...Pinion, 10...Power cylinder, 11...Inner cylinder body, 12...Outer cylinder body, 13...
Cylindrical oil passage, 14... Operating piston, 15... Bearing sleeve, 16... Cap, 25... Control valve, 26...
...Hydraulic power source, 27h...High pressure port, 27l...Low pressure port, 29a, 29b...Output port, 30
a, 30b...Communication pipe.

Claims (1)

[Scope of utility model registration request] In a power steering device, a power cylinder 10 for hydraulically driving the rack rod 3 is connected to one end of a steering gear box 1 that supports a pinion shaft 4 and a rack rod 3 that mesh with each other. The box 1 is made of die-casting, and the end of the cylinder body 12 of the power cylinder 10 and the communication pipes 30a and 30b fixed to the end and having one end opening inside the cylinder body 12 are cast-in and joined to the box 1. A power steering device characterized in that a hydraulic control circuit C is connected to the other ends of the communication pipes 30a and 30b for supplying and discharging hydraulic oil to and from the power cylinder 10.