JPH09196187A - Fitting structure of bellows - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fit a bellows used to seal an opening provided on a cylindrical housing for a projected part of a shaft body without dislocation in the axial direction associated with the movement of the shaft body while excellent sealing performance is secured. SOLUTION: Annular sealing projections 1c, 1c, 1c are circumferentially provided on an inner surface of fixed rings 1b which are continuously provided on one side of a body cylinder 1a of bellows shape. The fixed rings 1b are externally fitted to an opening edge part of a housing H to be fixed, and tightened from the outside by a tightening band 2 in which pressing projections 2a, 2a are provided on its inner surface. A closely tightened part over the whole circumference is generated to secure the sealing performance by squeezing the sealing projections 1c, 1c, 1c, and non-formed parts of the sealing projections 1c, 1c, 1c are pressed by the pressing projections 2a, 2a, and a contact part of the fixed ring 1b with the housing H is increased in area to prevent the positional dislocation in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows mounting structure used for hermetically sealing an opening formed in a cylindrical housing for projecting a shaft while allowing the shaft to move. Regarding

[0002]

2. Description of the Related Art For example, a rack housing extending in the left-right direction of a vehicle body is provided with a rack shaft slidably supported in the axial direction, and the projecting ends of the rack shaft on both sides of the rack housing are provided to the left and right. A rack and pinion type steering device, etc., which is connected to the steering wheel and is configured to perform steering by sliding the rack shaft in the axial direction, including movement in the axial direction inside the tubular housing. Is provided with a shaft body that makes a predetermined motion by projecting a part of the shaft body to the outside from an opening at one end or both ends of the housing, and performing a predetermined work by utilizing the motion of the projecting end. Devices are used in many industrial fields.

In this type of device, the opening provided at the end of the housing for projecting the shaft is hermetically sealed while allowing the above-mentioned movement of the shaft, so that water, dust, etc. A sealing means for preventing foreign matter from entering the inside of the housing is required, and a bellows has been conventionally used as this type of sealing means.

As is well known, the bellows has a corrugated peripheral wall in a cross section including a shaft, and a bellows-shaped main body tube which can be expanded and contracted in the axial direction by deformation of these corrugations, and the main body tube. Is a cylindrical body made of an elastic material, which is provided with annular portions (fixed rings) for fixing to an object that are continuously provided on both sides of the housing. The fixing rings on both sides are respectively fitted and fixed to the outer surface and a part of the shaft body protruding from the opening, and the fixed rings are mounted so as to be bridged between the housing and the shaft body. With this installation,
The opening is covered by the main body cylinder to realize sealing, and the expansion and contraction of the main body cylinder allows the movement of the shaft body (mainly movement in the axial direction).

When mounting the bellows as described above, it is necessary to surely fit the fixed ring to secure a high sealing property at the fitting portion. In particular, in the rack and pinion type steering device described above, when it is used as a sealing means between the rack housing and the rack shaft, the mounting position of the bellows is such that muddy water, dust, etc. splashed up by the wheels while the vehicle is traveling. It is important to enhance the sealing performance at the fitting portion of the fixed ring, because it is constantly exposed to foreign matter and may be submerged in water.

On the other hand, in the application as a sealing means between the rack housing and the rack shaft, damage due to the action of external force during traveling of the vehicle such as collision of flying stones jumped up by wheels is prevented, and it is provided in the engine room. It is required to have sufficient resistance to heat generated and to further reduce the weight. In recent years, in order to meet these requirements, resin bellows such as polyolefin elastomers are widely used. Has become. However, since the resin bellows is inferior in elasticity to general rubber bellows, it is a more important issue to secure the sealing property in the fitting portion of the fixed ring.

Conventionally, the inner diameter of the fixed ring is set by securing a sufficient tightening margin with respect to the outer diameter of the attachment target portion, and the fixed ring is fitted to the target portion while being extended, while By tightening the outside of the joint with a tightening band and pressing the inner surface of the fixed ring strongly against the outer surface of the target site to improve the adhesion on both sides, the sealing property is improved and the displacement of the fitting position is prevented. The mounting structure is generally adopted.

However, when such a mounting structure is adopted, especially in the case of a resin bellows which is difficult to secure a sufficient tightening margin due to lack of elasticity, the sealing property at the fitting portion of the fixed ring is not sufficient, There is a problem in that the supply and discharge of the inside and outside air due to the expansion and contraction of the main body tube occur via the fitting portion, and the foreign matter that enters the housing together with the supply and discharge of air cannot be sufficiently prevented.

[0009] Japanese Patent Laid-Open No. 6-313480 proposes to improve the sealing property in the fitting portion of the fixed ring of the bellows. FIG. 4 is an enlarged view of the periphery of a fixed ring of a bellows disclosed in Japanese Patent Laid-Open No. 6-313480, and FIG. 5 is an explanatory view of its mounting procedure. As shown in FIG. 4, the bellows 3 is provided with a bellows-shaped main body cylinder 3a in which only one mountain shape of the peripheral wall is shown, and a fixed ring 3b connected to one side of the main body cylinder 3a. An annular projection 3c is provided around the inner surface of the ring 3b, and an annular groove 3d is provided around the outer surface of the ring 3b so as to be aligned with the annular projection 3c.

Bellows 3 provided with such a fixed ring 3b
When the fixed ring 3b is fitted to the opening edge portion of the housing H to be attached, the annular projection 3c on the inner surface of the fixed ring 3b is pushed up by the fitting surface of the housing H as shown in FIG. 5 (a). Then, the corresponding portion of the outer surface rises with the concave groove 3d formed in the portion widened. In the fixed state obtained by tightening the outer side of the fixed ring 3b with the tightening band 4 in this state, as shown in FIG. 5 (b), both sides of the concave groove 3d are locally pressed and the inner surface is The annular projection 3c formed in the corresponding portion of the is crushed between the outer surface of the opening edge portion, and a dense crimped state is generated between the annular projections 3c, which ensures good sealing performance over the entire circumference. It is supposed to get.

[0011]

However, in the mounting structure as described above, the tightening band 4 mounted as shown in FIG. 5 (b) has a flat inner surface partly due to the raised portions on both sides of the concave groove 3d. In this case, there is an inconvenient mounting state in which the bearing is locally supported, and in this case, the supporting force in the axial length direction is insufficient, and there is a disadvantage that the other purpose of preventing displacement in the axial length direction cannot be achieved.

The concave groove 3d on the outer surface of the fixed ring 3b absorbs the bulge on the outer side due to the crushing of the annular projection 3c on the inner surface and is provided to avoid the above-mentioned inconvenience.
If the cross-sectional size of 3d is too large compared to the cross-sectional size of the annular projection 3c, the desired sealing performance cannot be obtained due to insufficient crushing of the annular projection 3c, and conversely, if it is too small, Tightening band 4
The mounting state becomes unstable, and positional deviation in the axial direction easily occurs.

That is, in the bellows mounting structure disclosed in Japanese Unexamined Patent Publication No. 6-313480, in order to achieve a desired purpose, it is necessary to secure high shape accuracy in the annular projection 3c and the concave groove 3d. However, it is difficult to obtain satisfactory shape accuracy by blow molding which is also disclosed in the above-mentioned publication and which is generally used for manufacturing this kind of bellows, and the above-mentioned inconvenience cannot be solved.

The present invention has been made in view of the above circumstances, and a bellows used for sealing an opening provided in a cylindrical housing for projecting a shaft body has a high sealing performance. At the same time, it is an object of the present invention to provide a mounting structure that can be mounted without displacement in the axial direction due to the movement of the shaft body.

[0015]

A bellows mounting structure according to the present invention uses a bellows formed by connecting a fixed ring continuously on both sides of a bellows-shaped main body tube which can expand and contract in the axial direction. The outer periphery of the end opening of the housing and the part of the shaft projecting from the opening, the fixing rings are respectively fitted on the outer surfaces, and tightened from the outside by a tightening band to move the shaft with respect to the housing. In the mounting structure of the bellows that hermetically seals the opening while allowing the expansion and contraction of the main body cylinder, one or a plurality of annular members are provided around the inner surface of the fixed ring or the outer surface of the edge of the opening. It is characterized by comprising a sealing protrusion and a pressing protrusion protruding on the inner surface of the tightening band so as to press the outer surface of the fixed ring while avoiding the corresponding portion of the sealing protrusion during the tightening.

In the present invention, when the fixed ring of the bellows is externally fitted to the opening edge portion of the housing to be fitted, the sealing projections provided around the inner surface of the fixed ring are locally formed on the outer surface of the opening edge portion. In a state of abutting, and when the tightening band is tightened to the outside of the fixed ring, the sealing projection is crushed between the outer surface of the opening edge portion and the sealing state is secured over the entire circumference, Further, the pressing projections provided on the inner surface of the tightening band press the fixing ring from the outside, and both sides of the sealing projection are pressed against the outer surface of the opening edge portion to prevent displacement in the axial direction. When the sealing projection is formed on the outer surface of the opening edge portion of the housing, when the tightening band is tightened, the inner surface of the fixed ring is locally crushed by the sealing projection to ensure a sealed state over the entire circumference. In addition, a pressing projection protruding from the inner surface of the tightening band presses the fixed ring from the outside, and the inner surface of the fixed ring is pressed against the outer surface of the opening edge portion on both sides of the sealing projection in the axial direction. Prevent misalignment.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is an enlarged cross-sectional view of a main part of a bellows and a tightening band used for implementing the present invention. The bellows 1 used for carrying out the present invention includes a bellows-shaped main body cylinder 1a in which only one mountain shape of the peripheral wall is shown, and a fixed ring 1b connected to one side of the main body cylinder 1a. Fixed ring 1b
The inner surface of the has three sealing protrusions with a semi-circular cross-sectional shape.
1c, 1c, 1c are annularly provided around the shaft length direction at substantially equal intervals.

The bellows 1 is made of an elastic material such as resin or rubber, and the fixed ring 1b can be expanded in diameter within an appropriate range by applying an external force. Bellows 1
It is used to fix one side of an object to an object.

The tightening band 2 used in the present invention together with the bellows 1 as described above is formed by molding a thin plate made of a material having high elasticity such as spring steel into an annular shape having a length corresponding to the fixed ring 1b. A metal ring, similar to those conventionally used for similar purposes, by a proper operation from the outer diameter side, a tightened state having an inner diameter sufficiently smaller than the outer diameter of the fixed ring 1b, and the fixed ring. It is configured so that it can be restrained in a fitted state having an inner diameter larger than the outer diameter of 1b.

As shown in the drawing, on the inner surface of the tightening band 2,
The pressing protrusion 2a is provided so as to protrude inward. The illustrated pressure protrusion
2a is formed as two annular protrusions that are formed by denting the peripheral wall of the tightening band 2 inwardly and are provided around the inner surface of the fixed ring 1b at substantially the same intervals as the sealing protrusions 1c, 1c, 1c. There is.

FIG. 2 is an explanatory view of a procedure for attaching the bellows 1 using the tightening band 2 as described above. In the figure, H is a housing to be attached,
As in the conventional case, the bellows 1 is attached to one side of the housing H by fitting a fixed ring 1b on the outer periphery of an opening edge portion provided for the projection of a shaft (not shown), and fixing the outer side of the fixed ring 1b. It is made by tightening with the tightening band 2.

FIG. 2A shows a state in which the fixed ring 1b is fitted to the outer periphery of the opening edge of the housing H. Stationary ring
The sealing projections 1c, 1c, 1c are provided around the inner surface of 1b, and in the fitted state of the fixed ring 1b shown in FIG. 2 (a),
Each of the sealing protrusions 1c, 1c, 1c is in a state of locally abutting on the outer peripheral surface of the opening edge portion.

The tightening band 2 is restrained in the above-mentioned fitted state, and the housing H is fitted before the fixed ring 1b is fitted.
2 is loosely fitted to the outside, and as shown by the broken line in FIG. 2 (a), the fixed ring 1b is made to stand by at a position where it does not interfere with the fitting of the fixed ring 1b. In the direction of the fixed ring as shown by the solid line in Fig. 2 (a).
Positioned outside 1b.

In this positioning, the pressing protrusions 2a, 2a provided around the inner surface of the tightening band 2 are respectively disposed between the central sealing protrusion 1c and the both side sealing protrusions 1c, 1c on the inner surface of the fixed ring 1b. Although it is performed so as to be positioned, high accuracy is not required, and for example, rough positioning such as aligning the periphery of the tightening band 2 with a matching mark appropriately formed on the outer surface of the fixed ring 1b is sufficient. is there. In the figure, a recess is formed on the outer surface of the fixed ring 1b to indicate the tightening position of the tightening band 2, and the edge of the recess is used as a matching mark.

The bellows 1 is fixed by releasing the restraint of the tightening band 2 after the above positioning is completed, and
It is realized as shown in (b). By releasing the restraint, the tightening band 2 tries to be in a tightened state in which its inner diameter is reduced, and a tightening force is applied to the fixed ring 1b aligned inside. At this time, the sealing projections 1c, 1c, 1c, which are provided in an annular shape on the inner surface of the fixed ring 1b, are crushed between the outer surface of the opening edge of the housing H and the entire circumference therebetween. While a tight sealing state is created and good sealing performance is ensured, the pressing projections 2a, 2a on the inner surface of the tightening band 2 locally press the outer side of the fixed ring 1b, so that the inner surface of the fixed ring 1b is , The parts that are aligned with the pressing protrusions 2a, 2a, that is, the respective sealing protrusions 1c, 1c,
Even in the portion between 1c, it is strongly pressed against the outer surface of the opening edge portion of the housing H, and the positional displacement of the fixed ring 1b with respect to the housing H in the axial direction can be prevented.

According to the bellows mounting structure as described above, the sealing protrusions 1c, 1c, 1c projectingly provided on the inner surface of the fixed ring 1b.
And a pressing protrusion 2a protruding from the inner surface of the tightening band 2,
By the action with 2a, the attachment of the bellows 1 to the opening end of the housing H secures a good sealing property in the fitting portion of the fixed ring 1b, and effectively prevents the positional displacement in the axial direction after the attachment. You will be able to do it while doing it.

The sealing property is obtained by crushing the sealing projection 1c on the inner surface of the fixed ring 1b by tightening the tightening band 2, and the sealing projection 1c extends over the entire circumference of the fixed ring 1b. It must be a circular projection that is circumferentially provided.
The number of the sealing protrusions 1c is not limited to three as shown in the figure, and may be one or two, or may be four or more. The cross-sectional shape of the sealing protrusion 1c is not limited to the semicircular shape shown in the figure, and another cross-sectional shape can be adopted as long as it is substantially uniform over the entire circumference. Further, with respect to the circumferential position of the sealing projection 1c, only rough accuracy is required so that the above-mentioned matching relationship can be obtained between the sealing projection 1c and the pressing projections 2a, 2a on the tightening band 2 side.

Further, as shown in FIG. 3, the sealing projection 1c may be projected on the outer surface of the opening edge portion of the housing H to which the fixed ring 1b is fitted. By tightening 2, the three sealing protrusions 1c, 1c, 1c on the housing H side locally crush the inner surface of the fixed ring 1b to secure the sealing property over the entire circumference.

On the other hand, the pressing projection 2a provided on the inner surface of the tightening band 2 presses the fixed ring 1b at a portion which is not aligned with the sealing projection 1c, and the close contact between the fixed ring 1b and the housing H. And mainly serves to prevent positional displacement in the axial direction after attachment. Pressing protrusion 2a in FIGS. 1 to 3
Is shown as an annular projection having a trapezoidal cross section formed by denting the peripheral wall of the tightening band 2 inwardly, but the formation mode of the pressing projection 2a is not limited to this, and is different from the sealing projection 1c. Differently, it does not have to be an annular projection extending over the entire circumference.

The pressing projection 2a shown in FIGS. 1 to 3 can be formed at the same time in the step of forming the plate material into an annular body in order to obtain the tightening band 2, and the predetermined shape accuracy can be obtained without the need for subsequent processing and finishing. And, there is an effect that the position accuracy can be obtained. Further, the number of the pressing protrusions 2a is not limited to the two shown in the figure, and may be appropriately determined according to the number of the sealing protrusions 1c.

[0031]

As described above, in the bellows mounting structure according to the present invention, when the fixed ring of the bellows is externally fitted to the opening edge of the housing to be fitted, the fitting portion of the fixed ring and the housing is fitted. The sealing projection provided around one side locally abuts on the other side, and then the tightening of the tightening band causes a close contact portion over the entire circumference at a corresponding position of the sealing projection to secure the sealing property, At the same time, the pressing projections protruding from the inner surface of the tightening band tighten the fixing ring at the non-formation portions of the sealing projections to increase the contact area with the outer surface of the housing and prevent displacement in the axial direction. The present invention has excellent effects such that the bellows can be attached to the opening provided at the end portion of the housing due to the protrusion of No. 1 without any displacement in the axial direction while ensuring high sealing performance.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a bellows and a tightening band used for implementing the present invention.

FIG. 2 is an explanatory view showing an embodiment of a bellows mounting structure according to the present invention.

FIG. 3 is an explanatory view showing another embodiment of the bellows mounting structure according to the present invention.

FIG. 4 is an enlarged view of the periphery of a fixed ring of a conventional bellows with improved sealing performance.

5 is an explanatory view of a procedure for attaching the bellows shown in FIG.

[Explanation of symbols]

 1 Bellows 1b Fixed ring 1c Sealing protrusion 2 Tightening band 2a Pressing protrusion H Housing

Claims (1)

[Claims] 1. An outer surface of an edge portion of an end opening of a tubular housing, which comprises a bellows formed by connecting a fixed ring continuously on both sides of a bellows-shaped main body tube which can expand and contract in the axial direction. The fixed ring is externally fitted to a part of the shaft projecting from the opening, and tightened from the outside by a tightening band to allow the movement of the shaft with respect to the housing by expansion and contraction of the main body cylinder while opening the opening. In a bellows mounting structure that hermetically seals, one or a plurality of sealing projections formed in an annular shape on an inner surface of the fixed ring or an outer surface of an edge portion of the opening,
A mounting structure for a bellows, comprising: a pressing protrusion projectingly provided on an inner surface of the tightening band so as to press the outer surface of the fixed ring while avoiding the corresponding portion of the sealing projection during the tightening.