JP2001106472A - Center swivel joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a center swivel joint solving the problems with a conventional hydraulic center swivel joint in which reversals of the pressure acting on the seal of a ring-shaped groove is frequent, the range of acting pressure is wide and the seal is put in an unstable condition at all times, and in particular when it is applied to a hydraulic steering circuit, the seal is damaged to result in poor sealing performance to lead to a poor performance of steering operation. SOLUTION: Above and below each ring-shaped groove, proprietary seal grooves are formed in the body or core, and there seals are set in, and a communication passage is formed in the body or core from the sliding surfaces of the body and core between the seal grooves of adjoining ring-shaped grooves and communication is generated to a drain passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal portion of a center swivel joint used for a work vehicle with a revolving body such as a truck crane and a work vehicle at a high place.

[0002]

2. Description of the Related Art In a work vehicle with a revolving body of this type,
It is necessary to supply hydraulic, pneumatic, electric, and other power sources to hydraulic equipment, pneumatic equipment, electric equipment, etc. mounted on the revolving unit, but the revolving unit turns on the vehicle frame. For this reason, the power is supplied to various devices via a center swivel joint (a hydraulic center swivel joint, a pneumatic center swivel joint, and an electric center swivel joint).

FIG. 3 shows a center swivel joint 1 used for a working vehicle such as a truck crane with a revolving body 3 which is rotatably mounted on a vehicle frame 2.
Only the hydraulic center swivel joint is shown. Reference numeral 4 denotes a body, which is connected to the vehicle frame 2 by a connecting means (not shown) via a mounting hole 5, and is restricted from rotating with respect to the vehicle frame 2. Reference numeral 6 denotes a core polymerized in the inward direction of the body 4,
The core 6 is attached to the revolving unit 3 by bolts 7. Are a plurality of annular grooves formed in the body 4;
Are a plurality of body-side passages formed in the body 4 communicating with the annular grooves 8, 8,. .. Are core-side passages communicating with the respective annular grooves 8, 8,. .., 11... Are seals incorporated in seal grooves formed in the body 4. With the above configuration, the body side passages 9, 9,... Communicate with the core side passages 10, 10,... Through the annular grooves 8, 8,. You can send oil.

FIG. 4 is a detailed view of a portion A in FIG. The seals 11 are alternately arranged with respect to the annular grooves 8 formed in the body 4. Now, paying attention to the seal 11a, the seal 11a functions as a seal for the upper annular groove 8a and also as a seal for the lower annular groove 8b. In general, the pressure of the pressure oil in the annular groove fluctuates greatly depending on the use condition of the hydraulic device, and the seal 11a sometimes receives the pressure alternately from the annular grooves 8a and 8b.

[0005]

As described above, the frequency of pressure reversal applied to the seal of the annular groove of the hydraulic center swivel joint may be high, and the applied pressure range is wide. Therefore, the seal is always in an unstable state. Was placed.

In particular, the above conditions are severe in a steering circuit or the like that uses hydraulic pressure, so that if the seal is damaged and a seal failure occurs, there is a possibility that the steering operation will be defective.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a center swivel joint having improved reliability in use of a seal for an annular groove of a hydraulic center swivel joint and having improved reliability.

[0008]

An invention according to claim 1 of the present application is a center swivel joint used for a work vehicle with a revolving body having a revolving body pivotally mounted on a vehicle frame, comprising a body and a core. Are polymerized inward and outward, the core is rotatable with respect to the body, a plurality of annular grooves are formed in the body or the core, and a plurality of body-side passages communicating with the respective annular grooves are formed in the body. And
In the center swivel joint, each of which has a core-side passage communicating with each of the annular grooves, a dedicated seal groove is formed in the body or the core above and below each of the annular grooves, and a seal is incorporated into the core or the core. A communication passage is formed in the body or the core from a sliding surface between the body and the core, between the seal grooves of the matching annular grooves, and is connected to the drain passage.

With this configuration, the seal incorporated in the seal groove formed in the body or the core is a dedicated seal for the adjacent annular groove, and a drain passage is provided on the back side thereof. It is only necessary to seal the pressure oil from only one direction, and stable sealing performance can be exhibited.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows only a hydraulic center swivel joint of a center swivel joint 21 according to an embodiment of the present invention. Reference numeral 24 denotes a body, which is connected to the vehicle frame 22 by connecting means (not shown) via a mounting hole 25, and is restricted from rotating with respect to the vehicle frame 22. Reference numeral 26 denotes a core polymerized in the inward direction of the body 24,
4 is rotatable with respect to the core 26 and the core 26 is
7, it is attached to the revolving superstructure 23. 28, 28
Are a plurality of annular grooves formed in the body 24, and 29, 29, are a plurality of body-side passages formed in the body 24 communicating with the respective annular grooves 28, 28,.
Are passages on the core 26 side communicating with the annular grooves 28, 28, respectively. 31, 31,
Is a seal incorporated in a seal groove formed in the body 24. With the above configuration, the body side passage 29,
29 and the core side passages 30, 30
Since the communication is performed through 8..., The pressurized oil can be mutually sent between the vehicle frame 22 side and the revolving body 23 side.

FIG. 2 is a detailed view of a portion B in FIG. For the annular grooves 28a, 28b,... Formed in the body 24, dedicated seals 31a, 31b and 31c, 31d,. Reference numeral 32 denotes a drain passage formed in the core 26.
3b, the body 24 and the core 2 between the seal grooves
The sliding surfaces 34a, 34b,.

Now, paying attention to the seal 31a, the seal 31a functions as a seal dedicated to the lower annular groove 28a. Since the sliding surface 34a between the body 24 and the core 26, which is the back of the seal 31a, communicates with the drain passage 32 via the communication passage 33a, it is guaranteed that the pressure on the back side of the seal 31a is zero. Have been.

With the above arrangement, the annular grooves 28a, 28b
Even if the pressure of the internal pressure oil fluctuates greatly depending on the use condition of the hydraulic device, the seal 31a only needs to receive the pressure from the annular groove 28a, so that the seal performance is stable.

The structure of the present invention is similar to that of the annular groove 28,
Of the 28..., It is used where the use conditions are severe for seals used in annular grooves where the pressure reversal frequency is large and the working pressure range is wide, and where the use conditions are not so severe, conventional configurations may be used. Of course.

[0015]

As described above, in the center swivel joint according to the present invention, the seal incorporated in the seal groove formed in the body or the core is a dedicated seal for the adjacent annular groove. Since the drain passage is provided on the back side, the seal only needs to seal the pressure oil from one direction, and a stable sealing performance can be exhibited.

In particular, when the center swivel joint of the present invention is applied to a steering circuit using hydraulic pressure, the reliability is greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a center swivel joint according to the present invention.

FIG. 2 is a detailed view of a portion B in FIG. 1;

FIG. 3 is a sectional view of a conventional center swivel joint.

FIG. 4 is a detailed view of a portion A in FIG. 3;

[Explanation of symbols]

 1,21 Center swivel joint 2,22 Vehicle frame 3,23 Upper revolving body 4,24 Body 5,25 Mounting hole 6,26 Core 8,28 Annular groove 9,29 Body side passage 10,30 Core side passage 11,31 Seal 32 Drain passage 33 Communication passage 34 Sliding surface

Claims (1)

[Claims] 1. A center swivel joint used for a work vehicle with a revolving body having a revolving body pivotally mounted on a vehicle frame, wherein a body and a core are superposed inward and outwardly, and a core is mounted on the body. Are rotatable, a plurality of annular grooves are formed in the body or the core, a plurality of body-side passages are formed in the body to communicate with the respective annular grooves, and the core communicates with the respective annular grooves. In the center swivel joint each having a core-side passage formed therein, a dedicated seal groove is formed on the body or the core above and below each of the annular grooves to incorporate a seal, and between the respective seal grooves of the adjacent annular grooves. A center, wherein a communication passage is formed in the body or the core from a sliding surface between the body and the core, and is connected to a drain passage. Lee Bell joint.