GB2107811A

GB2107811A - High-pressure swivel joint

Info

Publication number: GB2107811A
Application number: GB08207872A
Authority: GB
Inventors: Yoshiichi Yamatani
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-12
Filing date: 1982-03-18
Publication date: 1983-05-05
Also published as: CA1181451A; JPS5865392A; SE8201301L; DE3209340A1; GB2107811B; DE3209340C2; SE454014B; AU8709082A

Abstract

The swivel joint comprises a fixed casing (1) and a tube (4) rotatably disposed in the fixed casing for being supplied with a high-pressure fluid. A chamber (8) containing packings (6) is defined between the casing and the tube, and is supplied with a lubricant via passages (9) under a pressure which is at least equal to that of the high-pressure fluid. The lubricant under such a pressure is conducted to slidable contact surfaces of the casing and the tube for smooth rotation of the tube in the casing and prevention of leakage of the high-pressure fluid along the slidable contact surfaces. The high-pressure fluid enters the joint through passage (2), and flows into radial passage (3) of the tube via peripheral grooves (10) and radial passage (11) in a packing ring (12). <IMAGE>

Description

SPECIFICATION High-pressure swivel joint The present invention relates to a swivel joint for use in hydraulic pressure lines such as those carrying high pressure oil.

Swivel joints in hydraulic systems such as for construction machines or other fluid power applications include a fixed tube or casing, a rotatable tube housed therein and a mechanical seal disposed between the fixed and rotatable tubes for protection against oil leakage occurring along slidable contact surfaces therebetween.

Such a simple mechanical seal fails to provide complete sealing especially when the power line carries oil of an extremely high pressure. With high-pressure swivel joints, lubricating oil for the joints cannot be retained securely at the contacting surfaces of the fixed and rotatable tubes. Maintaining such a lubricant in the swivel joint in high-pressure applications is tedious, timeconsuming, and costly.

According to the present invention, a swivel joint comprises a fixed casing having first and second passages, a rotatable tube disposed in the fixed casing and having a third passage, and a packing chamber defined between the fixed casing and the rotatable tube and containing packings therein, the first and third passages being held in communication with each other via the chamber for introducing a high-pressure fluid into the rotatable tube, and the second passage being held in communication with the chamber for introducing a lubricant into the chamber under a pressure which is at least equal to that of the highpressure fluid.

Preferred features of the invention are set forth in claims 2-4.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a longitudinal cross-sectional view of a preferred embodiment of a swivel joint according to the present invention; FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1; and FIG. 3 is a diagrammatic view showing the way in which lubricating oil for the swivel joint shown in FIGS. 1 and 2 is pressurized.

As shown in FIGS. 1 and 2, a swivel joint comprises a fixed hollow body or casing 1 connected to a source of high-pressure oil (not shown) and having a lateral passage 2 for introducing high-pressure oil. The swivel joint also includes a rotatable body 4 in the form of a tube having a passage 3 extending in a radial direction thereof, the rotatable body 4 being slidably rotatably disposed in the fixed casing 1. The casing 1 has an end flange 5 and an open end remote from the end flange 5 and closed off by an end plate 16. The casing 1, the rotatable tube 4, the end flange 5 and the end plate 16 jointly define a chamber 8 in which there are disposed a plurality of packings 6 of the V type and packing retainers 7. The casing 1 has a suitable number of passages 9 held in communication with the chamber 8 for introducing lubricating oil into the chamber 8.The passage 2 in the casing 1 is held in communication with the passage 3 in the rotatable tube 4 via the chamber 8 for introducing the high-pressure oil into the passage 3.

As described in detail hereinafter, the lubricating oil supplied into the chamber 8 via the passages 9 is maintained under a pressure which is at least equal to the pressure of the highpressure oil delivered into the rotatable tube 4.

The casing 1 has drain holes 17 located at the ends of the chamber 8 for draining oil out of the chamber 8. A ring 12 is disposed in the chamber 8 in surrounding relation to the rotatable tube 4 and has grooves 10 in its inner and outer peripheral surfaces and radial through passageways 11. The high-pressure oil is allowed to pass from the passage 2 through the passageways 1 1 into the passage 3. Rings 12', 12" similar to the ring 12 are also housed in the chamber 8 in radial alignment with respective passages 9 in the casing 1. Thus, the lubricating oil is supplied from the passages 9 through the rings 12', 12" into the chamber 8.

As illustrated in FIG. 3, a tank 13 of lubricating oil containing a piston 14 therein which defines a pressurization chamber 15 and a supply chamber 18 one on each side of the piston 14 in the tank 13. A portion of the high-pressure oil which is fed into the rotatable tube 4 is introduced into the pressurization chamber 15 in the tank 14. The supply chamber 18 contains the lubricating oil and communicates with the passages 9 in the casing 1. This arrangement enables the lubricating oil to be supplied into the chamber 8 under a pressure equal to that of the high-pressure oil delivered to the tube 4.

Operation of the swivel joint thus constructed will now be described. The high-pressure fluid is supplied from the non-illustrated hydraulic source through the passage 2, the grooves 10, and the passageways 11 into the passage 3 in the rotatable tube 4. The lubricating oil is fed from the tank 13 through the passages 9 and the rings 12', 12", into the chamber 8. Since the pressure of the lubricating oil is equalized to at least the pressure of the high-pressure oil supplied into the rotatable tube 4, the lubricating oil in the chamber 8 is also kept under such pressure, and the high-pressure fluid is prevented from leaking out along slidable contact surfaces of the casing 1 and the tube 4.

The drain holes 17 may be appropriately closed and opened to supply a suitable amount of lubricating oil to such rotatable contact surfaces, thus providing a film of lubricating oil having a constant thickness for the prevention of frictional damage to the slidable contact surfaces and smooth rotation of the tube 4.

The pressure of the lubricating oil may be increased above that of the high-pressure fluid by suitably selecting the areas of the pressurization and supply chambers 15, 18 which undergo hydraulic pressures.

Although a certain specific embodiment has been shown and described, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.

Claims

1. A high-pressure swivel joint comprising: a fixed casing having first and second passages; a tube rotatably disposed in said fixed casing and having a third passage; and a packing chamber defined between said casing and said tube and containing packings therein; said first and third passages being held in communication with each other through said packing chamber for the introduction of a highpressure fluid into said tube, and said second passage being held in communication with said packing chamber for the introduction of a lubricant into the latter under a pressure which is at least equal to that of the high-pressure fluid.

2. A high-pressure swivel joint according to claim 1, including a ring disposed in said packing chamber around said tube and having a passageway held in communication with said first and third passages for conducting the highpressure fluid.

3. A high-pressure swivel joint according to claim 1 or 2, including a ring disposed in said packing chamber around said tube and having a passageway held in communication with said second passage for conducting the lubricant.

4. A high-pressure swivel joint according to claim 1, 2 or 3, including a tank having a piston therein which defines pressurization and supply chambers one on each side thereof in said tank for receiving a portion of the high-pressure fluid and the lubricant, respectively, therein, said supply chamber being held in communication with said packing chamber through said first and second passages.

5. A high-pressure swivel joint substantially as hereinbefore described with reference to and as shown in the accompanying drawings.