JPH0257478A - Oil seal structure for power steering device - Google Patents

Abstract

PURPOSE:To enhance the swing stop accuracy of a rack shaft by forming an oil seal, which is installed at a step between a rack retraining hole in a steering body and a cylinder hole on the power cylinder side, from an overhang part which hangs over from the inner end of a metal ring in the axial direction. CONSTITUTION:In an oil seal 11 to check outflux of pressure oil from the cylinder 7a side arranged interposed at the step part 13 on the rack retaining hole 12 side of a cylinder hole 7a in the steering body 3 having a large dia. cylinder hole 7a for piston and a small dia. rack retaining hole 12 for rack 5a the inner end of a metal ring 20 installed inside this oil seal 11 is overhung from the side face on the rack 5a side in the axial direction. This overhang part 21 is put in contact with the body inner wall side forming the rack retaining hole 12 as a backup ring, and to the inside surface of this overhang part 21 a resin layer 22 in contact with the periphery of a rack shaft 5 is fixed by means of application of coatings.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to, for example, a rack and pinion type power steering device, and particularly relates to a rack as an output shaft and a rack integrally connected to the rack to constitute a power cylinder portion. The present invention relates to an improvement in an oil seal structure disposed inside a steering body that retains liquid so that a rack shaft having a piston can move in the axial direction.

[Conventional technology]

As a rack and pinion type power steering device M (power steering) 1, one having a configuration schematically illustrated in FIG. 4 is known. To explain this simply, reference numeral 2 denotes a steering shaft extending from a steering wheel (not shown), which is fitted into the main body 3a of the steering body shown by 3, and whose inner end pinion is connected to the steering wheel. It meshes with a rack 5a of a rack shaft 5, which is an output shaft constituting a steering link mechanism 4 that steers the steering link mechanism 4. Also.

Reference numeral 6 denotes a large-diameter piston provided in the middle of the extending portion 5b of the rack shaft 5 that extends integrally in the axial direction of the rack 5a. A power cylinder 8 is formed which is slidably held by a large-diameter cylinder hole 7a in a metal pipe body 7 made of iron or the like, which is integrally connected for the purpose of steering, etc., and which generates a steering assist force. . That is, in the cylinder left and right chambers 8a and 8b formed on both sides of the piston 6,
As is well known, hydraulic pressure is guided through a hydraulic circuit that is switched by a rotary flow path switching valve (not shown) that is interposed between a body 3 in which a steering shaft 2 is installed and a pinion as an output side.

Here, 9a and 9b are connection members for connecting the left and right chambers 8a and 8b to the hydraulic circuit, and IO is 0 at the outer end of the pipe body 7.
It is a sleeve-shaped holder that is fixed via a ring and slidably supports the rack shaft extension portion 5b, and has an oil seal loa that seals the cylinder left chamber 8a.

Further, reference numeral 11 denotes an oil seal which is interposed at the inner end side of the cylinder hole 7a formed by the pipe body 7 and at the stepped portion 13 at the outer end portion of the rack holding hole 12 in the body cylindrical portion 3b, and seals the cylinder right chamber 8b. In the annular groove 12a of the inner wall of the rack holding hole 12 on the rack 5a side of this oil seal 11, there is a fifth groove.
As is clear from the figure, there is a sleeve-shaped sleeve that slidably holds the rack 5a and also supports the rack 5a in the radial direction when a large load is applied to the rack 5a to prevent excessive deformation of the oil seal 11. Backup ring 1
4 are arranged. In addition, reference numeral 15 in FIG. 4 is a tie rod connected to the steering wheel side at both ends of the link mechanism 4, and the rack 5a and extension portion 5b that constitute the rack shaft 5 are connected to the pole joint between these left and right tie rods 15 and 15. It is provided in series via the point 15FL.

[Problem to be solved by the invention]

By the way, in the conventional device 1 described above, the rack shaft 5 as an output shaft is disposed to penetrate through the rack holding hole 12 in the body cylindrical portion 3b and the cylinder hole 7a in the pipe body 7, and is arranged to penetrate the piston 6 and the oil at both ends. sticker! Oa
, 11, and are held in a liquid seal. In the seal portions on both end sides, especially in the inner oil seal 11 portion on the rack holding hole lz side, the rack shaft 5
A problem arises in that the steering wheel inevitably swings in the radial direction when steering.

Of course, on the back side of this oil seal 11, there is a body cylindrical part 3 having a rack shaft 5 and a holding hole 12 for holding the rack shaft 5.
As mentioned above, there is a backup ring 14 between
This buffer 2 pulling 14 is provided with a buffer 2 intervening to prevent excessive vibration of the rack shaft 5 and suppress deformation of the oil seal 11.

Since both the outer circumferential portion of the rack shaft 5 and the inner circumferential portion of the body cylindrical portion 3b (annular yt12a) are opposed to each other with a required clearance, a certain amount of swinging movement is unavoidable. And rack shaft 5 like this
The swinging motion of the steering link mechanism 4 causes a problem in terms of steering performance, and it is desirable to minimize it as much as possible.The conventional structure described above has limitations, and such problems It is desired that some kind of countermeasure be taken to solve the problem.

That is, according to the conventional structure, the backup ring 14
The thickness of the annular $11 formed on the inner circumference of the rack holding hole 12 in the body cylindrical portion 3b! 12a, the outer diameter of the rack shaft 5, etc. In particular, for the backup ring 14 described above, it is necessary to provide a certain amount of clearance between the outer diameter of the ring 14 and the body-side annular %Ij l 2 a due to ease of assembly, thermal expansion, low-temperature contraction, etc. It has been difficult to improve the precision of the steady rest of the shaft 5. That is, such a clearance is required to be at least about 0.2 to 0.31, and the deflection of the rack shaft 5 caused by this is about 0.81 m at maximum.

Further, according to the conventional AT device described above, the oil seal 11 for sealing the cylinder right chamber 8b, which is disposed in the step portion 13 between the roller 2 holding hole 12 and the cylinder hole 7a in the body 3, is installed in the device 11. When the oil seal 11 is removed together with the rack shaft 5 and the like from the body 3 during maintenance, problems arise such as deformation of the oil seal 11 and difficulty in performing the work.

That is, in order to remove and pull out the oil seal 11 from the insertion part, conventionally, the oil seal 11 is inserted into the gap between the outer circumference of the rack 5a and the rack holding hole 12 in the cylindrical part 3b.

A pipe-shaped seal extraction jig (indicated by reference numeral 17 in FIG. 5) is inserted from the outer end of the rack 5a, and the oil seal 11 is extracted by pushing it toward the cylinder hole 7a through the backup ring 14. However, the outer circumferential side of the oil seal 11 is press-fitted into the cylinder hole 7a, and it is difficult to remove it from the inner circumferential side where the backup ring 14 comes into contact. Oil seal 1 during work
1 may become deformed and become difficult to remove, which may lead to problems such as further difficulty in work, and there is a need to solve these problems as well.

[Means to solve the problem]

In order to meet such demands, the oil seal structure for a power steering device according to the present invention has a small-diameter holding hole into which a rack is inserted, and a large-diameter holding hole provided at one end of the rack shaft L connected to the rack. The steering body has a large-diameter cylinder hole in which the piston is held, and includes an oil seal that is placed between the cylinder hole and the rack holding hole side, and a metal ring provided in the oil seal. The inner end of the is provided so as to protrude in the axial direction from the side surface on the rack side, and this protruding part is brought into contact with the inside V of the body forming the rack holding hole as a backup ring, and the inner end of this protruding part is A resin layer is provided on the periphery in contact with the outer periphery of the rack.

[Effect]

According to the present invention, when installing an oil seal in the stepped portion between the small-diameter rack holding hole and the large-diameter cylinder hole on the power cylinder side in the steering body, the metal ring inside the oil seal The overhang provided extending from the end toward the rack in the axial direction is inserted into the inner wall of the body so that there is no gap, and the overhang is attached to the outer periphery of the rack via the resin layer provided on the inner periphery of the overhang. By making contact with
It is possible to improve the accuracy of the runout W of the rack shaft.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of the oil seal structure for a power steering device according to the present invention.
The same parts as those in the figures and FIG. 5 are given the same numbers, and the explanation thereof will be omitted.

Now, according to the present invention, in the steering body 3 having the small-diameter rack holding hole 12 for the rack 5a and the large-diameter cylinder hole 7a for the piston 6, there is a stepped portion 13 between the cylinder hole 7a and the rack holding hole 12 side. An oil seal 11 is arranged to prevent pressure oil from flowing out from the cylinder hole 7a side.
In.

The inner end of the metal 1120 provided in this oil seal 11 is provided so as to protrude in the axial direction from the side surface on the rack 5a side, and this protrusion fi21 is used as a backup ring on the inner wall of the body that forms the rack holding hole 12. (inner circumferential portion of the annular groove 12a) side, and the inner circumferential portion of this overhang portion 21 is coated with a resin layer 22 that is in contact with the outer circumferential portion of the rack shaft 5, as is clear from FIG. 2 or 3. Or, the burning is characterized by the fact that it is firmly fixed by etc.

When the oil seal 11 configured as described above is installed in the stepped portion 13 between the small-diameter rack holding hole 12 and the large-diameter cylinder hole 7a on the power cylinder 8 side in the body 3, this oil An overhang i' is provided extending from the inner end of the metal ring 20 in the seal 11 toward the rack 5a in the axial direction.
11121 so that there is no gap on the inner wall part (inner peripheral part of the annular groove 12a) of the body, and this overhang part 21
By contacting the outer circumferential portion of the rack shaft 5 via the resin layer 22 such as Teflon provided on the inner circumferential portion, the degree of deflection of the rack shaft 5 can be improved.

That is, according to the above-mentioned configuration, the oil seal 11 and the backup ring, which were conventionally at least two parts, can be integrated, which not only reduces the number of component parts and simplifies the configuration, but also makes it possible to It is excellent in terms of performance and has no effect on the function of the oil seal ti side.
The required sealing performance can be ensured. In particular, according to the structure of the present invention, the overhanging portion 21 overhanging from the oil seal 11 is formed integrally with the metal ring 20 and has a small wall thickness, so that it can be easily press-fitted into the body 3 side by appropriate deformation. This allows the projecting portion 21 to be assembled in proper and reliable contact with the inner wall side of the body 3 without creating a gap, and the steady rest accuracy can be improved by the amount of the conventional clearance. . Conventionally, the maximum amount of deflection of the shaft 5 was approximately 0.61 m layer, whereas according to the present invention, the maximum amount of deflection was reduced to 0.31 to 0.4 m.
It can be pressed down to about 1mm.

Further, according to the present invention, the metal ring 20 provided with the overhanging portion 21 is elastically held by the sealing material constituting the oil seal body, and is attached to the inner circumferential portion in contact with the outer circumferential portion of the rack shaft 5. Since the resin layer 22 is provided, even if thermal expansion or low-temperature contraction occurs, there will be no problem, and the function of the oil seal 11 as a backup ring can be ensured.

Furthermore, according to the structure of the present invention, when an extrusion force is applied from the rack 5a side (using a jig or the like shown at 17 in Fig. W45) in order to remove the oil seal 11 during maintenance, etc. The force is transmitted to the metal ring 20 side through the overhanging portion 21 which also serves as a backup ring, so that the oil seal 11 can be pressed and extracted to the outside without being deformed. This method has the advantage of simplifying the conventional extraction work, which is troublesome and difficult to perform.

Note that the present invention is not limited to the structure of the above-described embodiment, but can also be applied to a power steering device! 11. The shape and structure of each part can be modified and changed as necessary, and various modifications can be made. For example, in the above-mentioned embodiment, a rack and pinion type power steering device TL is exemplified. Although the present invention is applied to the oil seal 11 that holds a part of the rack shaft 5 as a liquid seal, the present invention is not limited to this, and can be used in various power steering devices to prevent shaking like the rack shaft. It is easy to understand that any oil seal used to hold a cylinder rod in a liquid seal for which it is desired to improve accuracy can be applied to achieve the desired effect.

〔Effect of the invention〕

As explained above, according to the oil seal structure for a power steering device according to the present invention, in a steering body having a small-diameter rack holding hole and a large-diameter cylinder hole, there is a step between the cylinder hole and the rack holding hole side. The inner end of a metal ring provided in the oil seal is provided so as to protrude in the axial direction from the side surface on the rack side, and this protrusion is connected to the bar two quadrupling. As a result, the inner wall of the body that forms the rack holding hole is inserted so that it is in contact with the inner wall side of the body, which forms the rack holding hole, and a resin layer that is in contact with the outer periphery of the rack is provided in the inner part of this overhang, which reduces the number of component parts. Despite its simple and inexpensive configuration, it is possible to easily install an oil seal at the step between the large diameter cylinder hole and the rack holding hole without compromising sealing performance. This has various excellent effects such as improving the stabilization accuracy of the rack shaft. Further, according to the present invention, the oil seal can be extracted by applying an extrusion force to the overhanging part integral with the metal ring with a jig or the like without causing deformation, which is different from the conventional method. The advantages are huge compared to

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of essential parts showing an embodiment of the oil seal structure for power steering Sa according to the present invention, and FIGS. 2 and 3 are enlarged cross-sectional views of the oil seal that characterizes the present invention and modifications thereof. FIG. 4 is an enlarged sectional view showing an example. FIG. 4 is a sectional view of main parts showing a schematic configuration of the steering body in a conventional rack and pinion type power steering device. FIG. 5 is an enlarged view of a conventional oil seal installation part. It is a schematic sectional view. l... Rack and pinion type power steering device, 3...
Steering body, 3b...tubular part, 4...
Steering gear a structure, 5... Chee 2 shaft, 5a...
...-Rack, 5b...Shaft extension part, 6...
...Piston, 7...Metal vibrator body, 7a...
・Cylinder hole, 8...Power cylinder, 10a, 1
1...Oil seal, 12...Rack holding hole,
12a... Annular groove, 13... Step portion, 14...
... Buffer 2 Bling, 20 ... Metal ring, 21
.--. Overhanging portion, 22. . . Resin layer. Patent applicant Jidosha Kiki Co., Ltd.

Claims (1)

[Claims] A rack holding hole that slidably holds the rack; and a large cylinder hole that slidably holds a large-diameter piston that is connected to one end of this holding hole and is provided on a rack shaft that is connected to the rack. and an oil seal that is disposed in the body at a step between the cylinder hole and the rack holding hole side to prevent pressure oil from flowing out from the cylinder hole side. The inner end of the metal ring provided in the metal ring is provided so as to extend in the axial direction from the side surface on the rack side, and this projecting portion is used as a backup ring and comes into contact with the inner wall side of the body forming the rack holding hole, An oil seal structure for a power steering device, characterized in that a resin layer in contact with the outer circumference of the rack is provided on the inner circumference of the projecting portion.