Around the shaft union

Abstract

A fluid coupling device has rotating seal mounted on a rotating device and a stationary seal mounted on a stationary device. The stationary seal is at least partially positioned adjacent a side of the rotating device parallel to its axis of rotation. The stationary seal is movable between a closed position where it engages with the rotating seal and an open position where it disengages from the rotating seal. A media inlet providing a media to the rotor at an area adjacent the rotating and stationary seals. A biasing member provides a balance ratio between the rotating and stationary seals, such that when no media or a compressible media is directed through the media inlet a net opening force maintains the stationary seal in the open position, and when a non-compressible media is directed through the media inlet a net closing force maintains the stationary seal in the closed position.

Description

TITLEAROUND THE SHAFT UNIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This International Application claims priority of U.S. Provisional Application No. 63 / 708,890 filed October 18, 2024, the disclosure of which is expressly incorporated by reference herein in its entirety.FIELD

[0002] The present teachings relate generally to rotary unions and, more particularly, to sealing arrangements that can be used for compressible and non-compressible media.BACKGROUND

[0003] Rotating unions, also known as fluid couplings, coolant unions, and rotary joints, are employed in a variety of operating applications. These include high-speed drilling and boring transfer operations, high-speed machine tool spindles, and in other operations where it is preferable or necessary to transfer a fluid medium (e.g., liquid, gas, etc.) to a rotating device.

[0004] Rotating unions are used to deliver non-compressible fluids such as water- or oil-based lubricants. Different arrangements have been employed to ensure tight engagement of rotating and non-rotating seal members. However, in such arrangements the interfacing surfaces of the seal members must be lubricated to avoid a condition known as “dry running”. This results in increased wear on the seals, particularly at high speeds. Extended periods of dry running operation can cause severe damage, thereby requiring replacement of some or all of the rotating union.{P74795 06817301. DOCX}

[0005] Rotating unions are also used without any medium, in which case a dry running condition may be prevented by separating the rotating and non-rotating seal. Such arrangements are commonly referred to as “pop off’ designs. In such designs, the non-rotating seal surface is mounted on a carrier that moves axially in relation to the rotating seal surface so that it engages the rotating seal in the presence of a medium and disengages the rotating seal in the absence of a medium.

[0006] Rotating unions are also used to deliver compressible fluids such as air- or gas-based based lubricants. In this case, it may also be preferable to avoid dry running by using a “pop off” design to save the seals from unnecessary wear.

[0007] U.S. Patent No. 8,047,576, entitled “Multi-media rotary union” and assigned to Deublin Company LLC, discloses a sealing arrangement for use with both compressible and non-compressible fluids, and is incorporated by reference in its entirety. The ‘576 patent discloses a set of end seals, and the media travels axially through its tubular carrier member (e.g., shaft).

[0008] Known rotating unions have been difficult to employ in radial driven tools. Such tools may have a full range of requirements to transfer fluids from a source to the rotating tool. For example, a rotating union in a machine tool may be used to deliver a lubricant for operating the tool, a coolant for regulating temperature of the tool, and / or air for cleaning the tool.

[0009] German Pat. No. DE 202018102291 U1 , entitled “Sealing Unit” and assigned to Ews Weigele & Co KG GmbH, discloses a mechanical seal for use with radial driven tools. The ‘229 patent discloses use of a lubricant, or otherwise appears to require limits on operation, in order prevent excessive seal wear.{P74795 06817301. DOCX}

[0010] Therefore, it would be beneficial to have an alternative system and method for an around the shaft union.SUMMARY

[0011] The needs set forth herein as well as further and other needs and advantages are addressed by the present embodiments, which illustrate solutions and advantages described below.

[0012] One embodiment of a system according to the present teachings includes, but is not limited to, a fluid coupling device. A rotating seal is adapted to be mounted on a rotating device. A stationary seal is adapted to be mounted on a stationary device. The stationary seal is at least partially positioned adjacent a side of the rotating device parallel to its axis of rotation. The stationary seal is operable to move between a closed position where it engages with the rotating seal and an open position where it disengages from the rotating seal. A media inlet is adapted to provide a media to the rotor at an area adjacent the rotating seal and the stationary seal. A biasing member provides a balance ratio between the rotating seal and the stationary seal, such that when no media or a compressible media is directed through the media inlet a net opening force maintains the stationary seal in the open position, and when a non-compressible media is directed through the media inlet a net closing force maintains the stationary seal in the closed position.

[0013] In one embodiment, the balance ratio is between 0.5 and 0.67.

[0014] In one embodiment, the media inlet is adapted to provide the media radially to the rotor.{P74795 06817301. DOCX}

[0015] In one embodiment, the stationary seal is generally L-shaped, with one length generally perpendicular to the axis of rotation and having a portion for engaging the rotating seal.

[0016] In one embodiment, the rotating seal is mounted on a flange extending from the rotor perpendicular to the axis of rotation.

[0017] In one embodiment, the biasing member comprises a spring.

[0018] In one embodiment, the biasing member comprises a structural shape of the stationary seal, including U-shape and a lip extension.

[0019] In one embodiment, a system according to the present teachings includes a radial driven tool having the fluid coupling device according to the present teachings.

[0020] Other embodiments of the system and method are described in detail below and are also part of the present teachings.

[0021] For a better understanding of the present embodiments, together with other and further aspects thereof, reference is made to the accompanying drawings and detailed description, and its scope will be pointed out in the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is an illustration of one embodiment of a prior art seal assembly system.

[0023] FIG. 2 is an illustration of a cross-section of one embodiment of a seal assembly system according to the present teachings.{P74795 06817301. DOCX}

[0024] FIG. 3 is an illustration showing the radial introduction of media into the embodiment of FIG. 2.

[0025] FIG. 4 is an illustration showing the full cross section of the seal assembly of FIG. 2.

[0026] FIG. 5 is an illustration showing a full stator seal in the seal assembly of FIG. 2.

[0027] FIG. 6 is an illustration of a full cross-section of a seal assembly system according to another embodiment of the present teachings.

[0028] FIG. 7 is an illustration of a close-up cross-section of the seal assembly of FIG. 6.DETAILED DESCRIPTION

[0029] The present teachings are described more fully hereinafter with reference to the accompanying drawings, in which the present embodiments are shown. The following description is presented for illustrative purposes only and the present teachings should not be limited to these embodiments. Any computer configuration and architecture satisfying the speed and interface requirements herein described may be suitable for implementing the system and method of the present embodiments.

[0030] In compliance with the statute, the present teachings have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the present teachings are not limited to the specific features shown and described, since the systems and methods herein disclosed comprise preferred forms of putting the present teachings into effect.{P74795 06817301. DOCX}

[0031] For purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description with unnecessary detail.

[0032] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. The use of “first”, “second,” etc. for different features / components of the present disclosure are only intended to distinguish the features / components from other similar features / components and not to impart any order or hierarchy to the features / components.

[0033] To aid the Patent Office and any readers of a patent issued on this application in interpreting the claims appended hereto, it is noted that none of the appended claims or claim elements are intended to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

[0034] Recitations of numerical ranges by endpoints include all numbers within that range (e.g., 1 to 5 includes 1 , 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Where a range of values is “greater than”, “less than”, etc., of a particular value, that value is included within the range.

[0035] Any direction referred to herein, such as “top,” “bottom,” “left,” “right,” “upper,” “lower,” “above,” below,” and other directions and orientations{P74795 06817301. DOCX}are described herein for clarity in reference to the figures and are not to be limiting of an actual device or system or use of the device or system. Many of the devices, articles, or systems described herein may be used in a number of directions and orientations.

[0036] Any citation to a reference in this disclosure or during the prosecution thereof is made out of an abundance of caution. No citation (whether in an Information Disclosure Statement or otherwise) should be construed as an admission that the cited reference qualifies as prior art or comes from an area that is analogous or directly applicable to the present teachings.

[0037] One object of the present teachings is to provide a high-speed rotary union capable of utilizing both non-compressible media (e.g., water, oil, etc.) and compressible media (e.g., air, gas, etc.) without excessive wear. Another object is to provide this capability for radially driven tools. Radially driven tools present unique challenges because they may not allow delivery of a media axially through the shaft. This may be because the shaft is too narrow or because of the presence of driving mechanisms, for example.

[0038] While known techniques may generally allow for extended use of lubricating media, the use of compressible and / or non-lubricating media (e.g., pressurized air) can limit operating time or the number of revolutions. Or they can require lubrication to be added so as not to damage components. Excessive wear of the seals will cause failure or excess leakage.

[0039] A rotary union according to the present teachings may allow for extended (even unlimited) use of compressible media in a radial driven tool without limitations of known techniques. In one embodiment, the present teachings make use of balancing the closing and opening forces (called a balance ratio). With compressible media, there is a net opening force and a{P74795 06817301. DOCX}small gap between the rotating and non-rotating seals. In this way, the rotary union may operate with some functional leakage of the compressible media. With non-compressible media, there is a net closing force such that the seals make contact and seal with no such functional leakage.

[0040] The outside diameter and the inside diameter of the rotating and non-rotating seals may be structurally arranged to create a specific balance ratio therebetween. The balance ratio is the proportion of the axial closing area to the opening area. As used herein and is known, the term “balance ratio,” B, is defined as the ratio between the average load imposed by the sealed pressure on the seal face, pf, over the sealed pressure, p, which canbe generally expressed algebraically as ? .

[0041] The average load pf involves an expression of the hydraulic surface area and / or dimensions of hydraulic surfaces that contribute to the action of a hydraulic force on the seal assembly. In other words, the balance ratio maybe be thought of as a non-dimensional parameter that encompasses the hydraulically significant structures of a seal that yield the net hydraulic force during seal operation. In this way, the net hydraulic force tending to engage or disengage a seal face is the result of a balancing between forces acting on the seal in an opening direction and forces acting on the seal in a closing direction. When the opening and closing forces are balanced, the seal will remain stationary even when pressurized. However, when either the opening or closing force is greater than the other, the seal will be urged to move.

[0042] In one embodiment according to the present teachings, the balance ratio is selected such that it is between 0.5 and 0.67, although not limited thereto. For example, the balance ratio may be 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51 , 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61 , 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, etc.{P74795 06817301. DOCX}

[0043] Referring now to FIG. 1, shown is an illustration of one embodiment of a prior art seal assembly system. As shown, the media travels axially down the shaft through the seal assembly. At the seal assembly there is functional leakage of compressible media (e.g., air).

[0044] Referring now to FIG. 2, shown is an illustration of a crosssection of one embodiment of a seal assembly system according to the present teachings. A stationary housing is shown on the left (depicted in yellow). This holds the stator seals (top and bottom, depicted in orange). A rotor is shown to the right of the stationary housing and stator seals (depicted in light blue). The rotor holds rotating seals above the top stator seal and below the bottom stator seal (depicted in green). To the right of the rotor is a rotating shaft (depicted in dark blue).

[0045] For purposes of demonstration, FIG. 2 shows two different states of the seal assembly with a dashed line separating them through the middle. The top stator seal forms a gap for functional leakage of a compressible media due to a net opening force. The bottom stator, however, shows the seal is engaged to seal (e.g., no functional leakage) a non- compressible media due to a net closing force. This demonstration shows the movement of the seals between the two states.

[0046] A net opening (or closing) force of the top stator may be provided by a biasing member. A biasing force may be provided by spring or other biasing member known in the art. As shown, the top stator may be in a resting state when there is no pressure. The biasing member pushes the stator seal from the rotating seal, but the biasing force may be overcome when there is enough force delivered by a compressible or non-compressible media.{P74795 06817301. DOCX}

[0047] An “around the shaft” configuration allows for operation with both compressible and non-compressible media. If non-compressible media is used, the seals will seal. If compressible media is used, a small gap will be made for functional leakage. This is accomplished by using balanced mechanical seals of between 0.5 and 0.67, although not limited thereto.

[0048] An around the shaft configuration may be desirable for certain applications, such as with radially driven tools. In radial driven tools the shaft may be a driving shaft and so incapable of being used for delivering media (e.g., through spindle coolant or “TSC”). For example, the driving mechanism may not allow an inlet for media or the shaft may be too small in diameter to allow a media channel.

[0049] Referring now to FIG. 3, shown is an illustration showing the radial introduction of media into the embodiment of FIG. 2. As shown, media enters radially from the side of the stator seals and is delivered to the shaft. The shaft is not being used for delivering the media. FIG. 3 shows use of a compressible media such that there is functional leakage between the stator seals and rotor seals.

[0050] Referring now to FIG. 4, shown is an illustration showing the full cross section of the seal assembly of FIG. 2. During pressurization with a non- compressible media, a low balance ratio results in reduced axial face load between the stationary seals and the rotating seals. This lowers friction, lowers wear rates, and provides a longer seal life. During pressurization with a compressible media, the low balance ratio results in the elimination of the axial load between the seal faces, which provides a gap (e.g., microscopic) between the seal faces that allows for frictionless operation.

[0051] When non-compressible media (such as water- or oil-based coolant) is used, the resultant net force engages the non-rotating seal surface{P74795 06817301. DOCX}with the rotating seal surface in the operated, pressurized condition. Because non-compressible media are generally liquid, the non-compressible media serves to lubricate the interfacing seal surfaces and prevent dry running. The engaged seal surfaces prevent undesirable leakage of the media.

[0052] When compressible media (such as air or gaseous-based coolant) is used, the resultant net force separates the non-rotating and rotating seal surfaces of the primary seal assembly by a small (e.g., microscopic) amount. This permits the seal surfaces to operate either with compressible media or without any lubrication from the media or from some external source, which results in little or no mechanical seal wear during operation of the rotary union.

[0053] Referring now to FIG. 5, shown is an illustration showing a full stator seal in the seal assembly of FIG. 2.

[0054] Referring now to FIG. 6, shown is an illustration of a full crosssection of a seal assembly system according to another embodiment of the present teachings. As shown, a U-shaped type of seal (aka a “U cup”) may be used that is structurally arranged to provide the proper balance ratio to permit the operation of the rotary union with non-compressible and compressible media. The U-shaped seal may be positioned within a groove of the stationary housing and have a lip extension.

[0055] Referring now to FIG. 7, shown is an illustration of a close-up cross-section of the seal assembly of FIG. 6. In such an embodiment, no other biasing members (e.g., springs) may be necessary.

[0056] While specific embodiments of biasing members have been disclosed, it is appreciated by one skilled in the art that any number of{P74795 06817301. DOCX}different types of biasing members may be used. What is desirable is to achieve an appropriate balance ratio for a particular application.

[0057] While the present teachings have been described above in terms of specific embodiments, it is to be understood that they are not limited to these disclosed embodiments. Many modifications and other embodiments will come to mind to those skilled in the art to which this pertains, and which are intended to be and are covered by both this disclosure and the appended claims. It is intended that the scope of the present teachings should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings.{P74795 06817301. DOCX}

Claims

What is claimed is:

1. A fluid coupling device, comprising: a rotating seal adapted to be mounted on a rotating device; a stationary seal adapted to be mounted on a stationary device, the stationary seal at least partially positioned adjacent a side of the rotating device parallel to its axis of rotation; the stationary seal operable to move between a closed position where it engages with the rotating seal and an open position where it disengages from the rotating seal; a media inlet adapted to provide a media to the rotor at an area adjacent the rotating seal and the stationary seal; a biasing member providing a balance ratio between the rotating seal and the stationary seal, such that when no media or a compressible media is directed through the media inlet a net opening force maintains the stationary seal in the open position, and when a non-compressible media is directed through the media inlet a net closing force maintains the stationary seal in the closed position.

2. The device of claim 1 , wherein the balance ratio is between 0.5 and 0.67.

3. The device of claim 1 , wherein the media inlet is adapted to provide the media radially to the rotor.

4. The device of claim 1 , wherein the stationary seal is generally L- shaped, with one length generally perpendicular to the axis of rotation and having a portion for engaging the rotating seal.

5. The device of claim 1 , wherein the rotating seal is mounted on a flange extending from the rotor perpendicular to the axis of rotation.{P74795 06817301. DOCX}6. The device of claim 1 , wherein the biasing member comprises a spring.

7. The device of claim 1 , wherein the biasing member comprises a structural shape of the stationary seal, including U-shape and a lip extension.

8. A radial driven tool having the fluid coupling device of claim 1 .{P74795 06817301. DOCX}

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