WO2016100537A1

WO2016100537A1 - Connection for pneumatic tubes

Info

Publication number: WO2016100537A1
Application number: PCT/US2015/066137
Authority: WO
Inventors: Derek K. SCHMID; Christophe Schorsch
Original assignee: Eaton Corporation; The Goodyear Tire & Rubber Company
Priority date: 2014-12-17
Filing date: 2015-12-16
Publication date: 2016-06-23

Abstract

A connection for pneumatic tubes includes a first resilient tube and a second resilient tube. A ribbed fitting defines annular ribs and an axial lumen. A first end of the ribbed fitting is disposed in a first end of the first resilient tube. A second end of the ribbed fitting opposite the first end of the ribbed fitting is disposed in a second end of the second resilient tube. The ribbed fitting fluidly connects the first resilient tube to the second resilient tube. A connector shell is to radially compress the first and the second resilient tubes against the ribbed fitting to prevent a compressed gas from leaking between the annular ribs and the first or the second resilient tube. The connector shell has a 90 degree internal elbow to hold a 90 degree bend in the second resilient tube.

Description

CONNECTION FOR PNEUMATIC TUBES

BACKGROUND

The present disclosure relates generally to a connection for resilient tubes conveying a pressurized gas. The resilient tubes may be part of a self-inflating tire. A self-inflating tire may have an integral peristaltic pump that includes a resilient tubular structure built into the wall of the tire. When the tire rolls, the resilient tubular structure is compressed and pinched closed in a location near where the tire contacts the road. As the tire continues to roll, the pinched portion of the resilient tubular structure progresses along the tubular structure, thereby squeezing air out of the pinched portion into the tubular structure ahead of the pinched portion. The air may be discharged into the tire cavity to inflate the tire.

SUMMARY

A connection for pneumatic tubes includes a first resilient tube and a second resilient tube. A ribbed fitting defines annular ribs and an axial lumen. A first end of the ribbed fitting is disposed in a first end of the first resilient tube. A second end of the ribbed fitting opposite the first end of the ribbed fitting is disposed in a second end of the second resilient tube. The ribbed fitting fluidly connects the first resilient tube to the second resilient tube. A connector shell is to radially compress the first and the second resilient tubes against the ribbed fitting to prevent a compressed gas from leaking between the annular ribs and the first or the second resilient tube. The connector shell has a 90 degree internal elbow to hold a 90 degree bend in the second resilient tube. BRIEF DESCRIPTION OF THE DRAWINGS

Features of examples of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to the same or similar, though perhaps not identical,

components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

Fig. 1 is a semi-schematic cross-sectional view of an example of a connection of the present disclosure;

Fig. 2 is a semi-schematic cross-sectional exploded view of the example of the connection depicted in Fig. 1 ;

Fig. 3 is a semi-schematic perspective view of an example of a ribbed fitting of the present disclosure;

Fig. 4A is a semi-schematic side view of an example of a ribbed fitting of the present disclosure;

Fig. 4B is a semi-schematic cross-sectional view of the example of the ribbed fitting depicted in Fig. 4A;

Fig. 4C is a detail view of the ribs taken from the cross-sectional view depicted in Fig. 4B;

Fig. 4D is a semi-schematic end view of the example of the ribbed fitting depicted in Fig. 4A;

Fig. 5 is a semi-schematic perspective view of an example of a connector shell of the present disclosure;

Fig. 6 is a semi-schematic rotated perspective view of an example of a connector shell of the present disclosure;

Figs. 7A-7C are semi-schematic orthographic projections of an example of an inside shell piece of the present disclosure;

Fig. 7D is a semi-schematic perspective view of the example of the inside shell piece depicted in Figs. 7A-7C; Figs. 8A-8C are semi-schematic orthographic projections of an example of an outside shell piece of the present disclosure; and

Fig. 8D is a semi-schematic perspective view of the example of the outside shell piece depicted in Figs. 8A-8C.

DETAILED DESCRIPTION

The present disclosure relates generally to a connection for resilient tubes conveying a pressurized gas. Examples of the present disclosure may be used in a self-inflating tire. Some land vehicles include a pneumatic tire mounted on a wheel to roll in contact with a ground surface. The tire may form a seal with the rim of the wheel, and substantially contain a gas in a substantially sealed tire cavity defined by the tire and wheel. The gas may be air, nitrogen, another gas or combination of gasses. The gas may be pressurized in the tire thereby inflating the tire. The inflated tire supports and cushions the wheel.

It is to be understood that gage pressure in a tire is the difference between the pressure in the tire and the atmospheric pressure outside the tire. It is to be further understood that tire pressure means the gage pressure of the tire.

If no air is added to some inflated tires, the tires may experience diminishing tire pressure over time. For example, some of the pressurized air substantially contained by the tire may slowly escape by diffusion through the tire wall. Atmospheric pressure and temperature may also influence the tire pressure. A tire will generally perform better when the tire pressure is at a particular design pressure. For example, a vehicle may experience better fuel economy with properly inflated tires compared to the same vehicle operating with underinflated tires.

A tire that includes a peristaltic pump may also be known as a self-inflating tire.

A peristaltic pump may include a resilient tube integrated into the tire wall. The weight of the vehicle causes the tire to change shape as the tire rolls. For example, the generally round tire may have a contact patch that is compressed to substantially match the road surface. A compressed region of the tire wall near the contact patch may pinch and close the resilient tube integrated into the tire wall. As the tire continues to roll, the pinched portion of the resilient tube progresses along the resilient tube structure, thereby squeezing air out of the pinched portion into the portion of the resilient tube ahead of the pinched portion. The air may be discharged from the resilient tube ultimately into the tire cavity to inflate the tire.

In some self-inflating tires, an air regulator prevents air from entering the peristaltic pump if a tire air pressure in a pressurizable cavity of the tire is greater than a predetermined set point pressure. It is to be understood that the mass of air pumped into the tire cavity by the peristaltic pump according to the present disclosure in a single revolution may be relatively small compared to the mass of air in a fully inflated tire. In an example, a self-inflating tire may pump enough air to make up for normal losses in a tire. For example, a self-inflating tire may pump about 1 psi into a 100 psi tire over a month. A range of airflow from about 250 SCCM (Standard Cubic

Centimeters per Minute) to about 1000 SCCM may flow into the tire. In terms of mass airflow the same example would range from about 0.3 g (gram) to about 1 .3 g of dry air at STP (Standard Temperature and Pressure). In an example, a commercial truck tire may contain 150 liters of air at about 100 psi (689 kilopascals) under normal operating conditions.

It may be desirable to join a first resilient tube to a second resilient tube. For example, the first resilient tube may be a part of the air regulator assembly, and the second resilient tube may be at least partially embedded in the tire wall. A connection between the first and second resilient tubes that is leak-tight at vehicle tire pressures is disclosed herein.

Fig. 1 is a semi-schematic cross-sectional view of an example of a connection 40 for pneumatic tubes according to the present disclosure. Fig. 2 is a semi-schematic cross-sectional exploded view of the example of the connection 40 depicted in Fig. 1 . In the example depicted in Figs. 1 and 2, the connection 40 includes a first resilient tube 50 and a second resilient tube 60. The first resilient tube 50 and the second resilient tube 60 may be made from a resilient polymer, for example rubber. Some other examples of resilient polymers that may be included in the first resilient tube 50 and the second resilient tube 60 are: nitrile rubber, natural rubber, neoprene, ethylene propylene diene monomer (M-class) rubber, hydrogenated nitrile rubber, silicone, styrene-butadiene rubber, acrylic ester rubber, fluoroelastomers, and polyurethane. The first resilient tube 50 and the second resilient tube 60 may have textile reinforcements. For example, a reinforcement made from a braided polyamide fiber may be embedded in the first resilient tube 50 or the second resilient tube 60.

The first resilient tube 50 and the second resilient tube 60 may be pneumatic tubes, used to convey, for example, compressed air. As used herein, "resilient" means able to recoil or spring back into shape after bending, stretching, or being compressed. It is to be understood that the connection of the present disclosure is not for metal tubing, for example, steel, aluminum, or copper tubing.

In an example, the first resilient tube 50 and the second resilient tube 60 may be made from a different material. For example, the first resilient tube 50 and the second resilient tube 60 may have different chemical compositions that result in differences in material properties, e.g. durometer. An inside diameter 66 of the first resilient tube 50 and an inside diameter 67 of the second resilient tube 60 may be equal. An outside diameter 69 of the first resilient tube 50 and an outside diameter 70 of the second resilient tube 60 may be equal. As used herein, the inside diameter 66 of the first resilient tube 50, the inside diameter 67 of the second resilient tube 60, the outside diameter 69 of the first resilient tube 50, and the outside diameter 70 of the second resilient tube 60 refer to diameters measured prior to insertion of a ribbed fitting 30 into the first resilient tube 50 and the second resilient tube 60 as depicted in Fig. 2.

Still referring to Figs. 1 and 2, a ribbed fitting 30 defines annular ribs 32 and an axial lumen 34. As used herein, "lumen" means a bore of a tube. A first end 36 of the ribbed fitting 30 is disposed in a first end 52 of the first resilient tube 50. A second end 38 of the ribbed fitting 30 opposite the first end 36 of the ribbed fitting 30 is disposed in a second end 62 of the second resilient tube 60. The ribbed fitting 30 fluidly connects the first resilient tube 50 to the second resilient tube 60.

A connector shell 20 is to radially compress the first resilient tube 50 and the second resilient tube 60 against the ribbed fitting 30 to prevent a compressed gas from leaking between the annular ribs 32 and the first resilient tube 50 or the second resilient tube 60. In an example, the first resilient tube 50 and second resilient tube 60 may convey a compressed gas (e.g. air) at a gage pressure from about 100 psi (pounds per square inch) to about 150 psi. The connector shell 20 has a 90 degree internal elbow to hold a 90 degree bend 64 in the second resilient tube 60. It is to be understood that the 90 degree bend 64 may be exactly 90 degrees, or may be about 90 degrees.

Fig. 3 and Figs. 4A-4D depict views of an example of a ribbed fitting 30 according to the present disclosure. In the example depicted in Figs. 3 and 4A-4D, the ribbed fitting 30 includes a straight, tubular body 31 having an outer body diameter 33 coaxial with the axial lumen 34.

An annular stop flange 35 projects radially outward from the tubular body 31 . The annular stop flange 35 is defined at a center 37 of the tubular body 31 to stop the ribbed fitting 30 at a predetermined depth of penetration into the first resilient tube 50 and the second resilient tube 60. The annular stop flange 35 defines a first side 39 of the ribbed fitting 30 and a second side 79 of the ribbed fitting 30 opposite the first side 39 of the ribbed fitting 30.

At least two of the annular ribs 32 are at longitudinally spaced intervals on the first side 39 of the ribbed fitting 30. Similarly, at least two of the annular ribs 32 are at longitudinally spaced intervals on the second side 79 of the ribbed fitting 30. A first chamfer 71 is at a first longitudinal extremity 72 of the tubular body 31 to reduce a first insertion force to insert the ribbed fitting 30 into the first resilient tube 50. Similarly, a second chamfer 73 is at a second longitudinal extremity 74 of the tubular body 31 opposite the first longitudinal extremity 72 of the tubular body 31 to reduce a second insertion force to insert the ribbed fitting 30 into the second resilient tube 60. Still referring to Figs. 3 and 4A-4D, each of the annular ribs 32 has bilateral symmetry about a plane 75 normal to a longitudinal axis 76 of the axial lumen 34. Plane 75 is depicted as a center-line in Figs. 4A, 4B and 4C. As used herein, bilateral symmetry means the property of being divisible into symmetrical halves on either side of a unique plane. The bilateral symmetry is in sharp contrast to "barbed" connectors that have barbed ridges that are larger on a central end of the barbed ridge and smaller on a distal end of the barbed ridge. As depicted in Fig. 4B, a longitudinal cross-section taken through the longitudinal axis 76 of the axial lumen 34 and through each of the annular ribs 32 defines a predetermined radius 77 at an outer diameter 78 of each of the annular ribs 32. The predetermined radius 77 is large enough to prevent the annular ribs 32 from cutting the first resilient tube 50 or the second resilient tube 60. The annular stop flange 35 has a radial clearance 80 between a maximum diameter 81 of the annular stop flange 35 and an inside surface 24 of the connector shell 20 spatially nearest to the annular stop flange 35 (see Fig. 1 ). As depicted in Fig. 4B, each of the annular ribs 32 has an outer diameter 78 less than the maximum diameter 81 of the annular stop flange 35.

Examples of the ribbed fitting 30 of the present disclosure may be relatively small compared to some components of pneumatic connections on a commercial vehicle. For example, commercial vehicle pneumatic brake lines may have a flow diameter about 10 times larger than the axial lumen 34 of the present disclosure. In an example of the connection 40 of the present disclosure, a length 82 of the ribbed fitting 30 may be from about 4.0 mm to about 6.0 mm. The predetermined radius 77 may be from about 0.07 mm to about 1 .03 mm. The maximum diameter 81 of the annular stop flange 35 may be from about 2.9 mm to about 3.1 mm. The outer diameter 78 of the annular ribs 32 may be from about 2.4 mm to about 2.6 mm. The axial lumen 34 may have a constant diameter 83 from about 0.9 mm to about 1 .1 mm. The outer body diameter 33 of the tubular body 31 may be about 1.9 mm to about 2.1 mm. The dimensions provided are examples. Examples of the present disclosure may have dimensions outside the ranges specifically provided as examples above. In an example of the present disclosure, the ribbed fitting 30 may be made entirely from stainless steel. For example, the ribbed fitting may be made entirely of American Iron and Steel Institute (AISI) 303 stainless steel, also designated as unified numbering system (UNS) S30300. The corrosion resistance of the stainless steel may be advantageous in keeping the axial lumen 34 open compared to materials that may corrode more rapidly. Examples of the ribbed fitting 30 may be made from other materials, for example, brass or polyamide.

Fig. 5 is a semi-schematic perspective view of an example of a connector shell

20 of the present disclosure. Fig. 6 is a semi-schematic rotated perspective view of the connector shell depicted in Fig. 5. In examples of the present disclosure, the connector shell 20 may include an inside surface 24 in contact with the first resilient tube 50 and the second resilient tube 60 (see Fig. 1 ). The inside surface 24 defines a first intersecting cylinder 21 and a second intersecting cylinder 23. The first

intersecting cylinder 21 intersects the second intersecting cylinder 23 to form an L- shaped conduit 25. The first intersecting cylinder 21 defines a first cylinder diameter 26. The second intersecting cylinder 23 defines a second cylinder diameter 27 equal to the first cylinder diameter 26. A connector shell plane 28 is defined by a first longitudinal axis 41 of the first intersecting cylinder 21 and a second longitudinal axis 43 of the second intersecting cylinder 23.

An inside shell piece 44 is fixedly attached to an outside shell piece 45 at a joint surface 46. The joint surface 46 defines a first joint plane 47 orthogonal to the connector shell plane 28. The first longitudinal axis 41 of the first intersecting cylinder

21 lies in the first joint plane 47. The joint surface 46 also defines a second joint plane 48 orthogonal to the connector shell plane 28. The second longitudinal axis 43 of the second intersecting cylinder 23 lies in the second joint plane 48.

The inside shell piece 44 defines a first inside flange 49 parallel to the joint surface 46. The inside shell piece 44 defines a second inside flange 51 parallel to the joint surface 46 with bilateral symmetry about the connector shell plane 28 to the first inside flange 49. The outside shell piece 45 defines a first outside flange 53 opposite the first inside flange 49 parallel to the joint surface 46. The outside shell piece 45 also defines a second outside flange 54 opposite the second inside flange 51 parallel to the joint surface 46 with bilateral symmetry about the connector shell plane 28 to the first outside flange 53. The first inside flange 49 and the first outside flange 53 define a first groove 55 therebetween. The second inside flange 51 and the second outside flange 54 define a second groove 68 therebetween.

To attain the best useful life of the connection 40, the radial compression of the first resilient tube 50 and the second resilient tube 60 between the connector shell 20 and the annular ribs 32 should be within an allowable compression ratio for the material used to make the first resilient tube 50 or the second resilient tube 60. The compression ratio, also known as the crimp ratio, may be determined from a ratio of a difference between the uninstalled wall thickness of the first resilient tube 50 or the second resilient tube 60 and the space between the connector shell 20 and the annular ribs 32 to the uninstalled wall thickness of the first resilient tube 50 or the second resilient tube 60. For example, the space between the connector shell 20 and the annular ribs 32 is the difference between the first cylinder diameter 26 and the outer diameter 78 of the annular ribs 32. The uninstalled wall thickness of the first resilient tube 50 is the difference between the outside diameter 69 of the first resilient tube 50 and the inside diameter 66 of the first resilient tube 50.

In an example, for a connection 40 having a first resilient tube 50 made from nitrile rubber, natural rubber, neoprene, ethylene propylene diene monomer (M-class) rubber, hydrogenated nitrile rubber, silicone, styrene-butadiene rubber, or acrylic ester rubber, an allowable compression ratio may be up to about 20 percent. In another example, for a connection 40 having a first resilient tube 50 made from a stiffer fluoroelastomer or polyurethane, the allowable compression ratio may be about 15 percent. The allowable compression ratio for the material may take the operational temperatures for the materials into account. Figs. 7A-7D depict an example of an inside shell piece 44 according to the present disclosure. Figs. 8A-8D depict an example of an outside shell piece 45 of the present disclosure. When referring to the inside shell piece 44 and the outside shell piece 45, "inside" and "outside" refer to an inside of a curve and an outside of a curve; similar to the context of the inside of a curve on a road and the outside of the curve on a road. In the particular instance of the inside shell piece 44 and the outside shell piece 45, "inside" and "outside" do not refer to surfaces that are visible from a particular vantage point e.g. the "inside" diameter of a tube and the "outside" diameter of a tube. An intersection point 56 is defined at an intersection of the first longitudinal axis 41 of the first intersecting cylinder 21 and the second longitudinal axis 43 of the second intersecting cylinder 23. A shortest distance 59 between the intersection point 56 and a first open end 57 of the first intersecting cylinder 21 opposite the intersection point 56 is from about 9.0 mm to about 1 1 .0 mm. A least distance 61 between the intersection point 56 and a second open end 58 of the second intersecting cylinder 23 opposite the intersection point 56 is from about 6.0 mm to about 8.0 mm. The first cylinder diameter 26 is from about 3.3 mm to about 3.6 mm. Examples of the present disclosure may have dimensions outside the ranges specifically provided as examples above.

In an example of the present disclosure, the inside shell piece 44 and the outside shell piece 45 may be made entirely of stainless steel. For example, the inside shell piece 44 and the outside shell piece 45 may be made entirely of AISI 316L stainless steel, also designated as UNS S31603. Examples of the inside shell piece

44 and the outside shell piece 45 may be made from other materials, for example polyamide.

In examples of the connection 40 of the present disclosure, the connector shell

20 may include the inside shell piece 44 and the outside shell piece 45. The inside shell piece 44 may be attached to the outside shell piece 45 via an adhesive bond. In other examples, the inside shell piece 44 may be attached to the outside shell piece

45 via a weld. As used herein, the connector 10 means the assembly of the connector shell 20 and the ribbed fitting 30 (see Fig. 1 ). The connector shell 20 includes the inside shell piece 44, and the outside shell piece 45. The connector 10 is a portion of the connection 40. The connection 40 includes the connector 10, the first resilient tube 50 and the second resilient tube 60 arranged to form a leak-tight conduit 42 for the gas conveyed by the first resilient tube 50 and the second resilient tube 60. As used herein, the first resilient tube 50 and the second resilient tube 60 are part of the connection 40; however, not part of the connector 10.

It is to be understood use of the words "a" and "an" and other singular referents may include plural as well, both in the specification and claims, unless the context clearly indicates otherwise. Any numerical designations, such as "first" or "second" used are not intended to be limiting, and any specific component may be referenced with any number unless specifically stated herein.

Further, it is to be understood that the terms "attach/attached" and/or the like are broadly defined herein to encompass a variety of divergent attachment

arrangements and assembly techniques. These arrangements and techniques include, but are not limited to (1 ) the direct communication between one component and another component with no intervening components therebetween; and (2) the communication of one component and another component with one or more components therebetween, provided that the one component being "attached to" the other component is somehow in operative communication with the other component (notwithstanding the presence of one or more additional components therebetween).

Still further, it is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range from about 4.0 mm to about 6.0 mm should be interpreted to include not only the explicitly recited limits of about 4.0 mm and about 6.0 mm, but also to include individual values, such as 4.2 mm, 5.1 mm, 5.5 mm, etc., and sub-ranges, such as from about 4.8 mm to about 5.5 mm, etc. Furthermore, when "about" is utilized to describe a value, this is meant to encompass minor variations (up to +/- 10%) from the stated value.

Furthermore, reference throughout the specification to "one example", "another example", "an example", and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the example is included in at least one example described herein, and may or may not be present in other examples. In addition, it is to be understood that the described elements for any example may be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.

While several examples have been described in detail, it is to be understood that the disclosed examples may be modified. Therefore, the foregoing description is to be considered non-limiting.

Claims

What is claimed is:

1 . A connection for pneumatic tubes, comprising:

a first resilient tube;

a second resilient tube;

a ribbed fitting defining annular ribs and an axial lumen, a first end of the ribbed fitting disposed in a first end of the first resilient tube, and a second end of the ribbed fitting opposite the first end of the ribbed fitting disposed in a second end of the second resilient tube wherein the ribbed fitting fluidly connects the first resilient tube to the second resilient tube; and

a connector shell to radially compress the first and the second resilient tubes against the ribbed fitting to prevent a compressed gas from leaking between the annular ribs and the first or the second resilient tube, the connector shell having a 90 degree internal elbow to hold a 90 degree bend in the second resilient tube.

2. The connection as defined in claim 1 wherein the ribbed fitting includes: a straight, tubular body having an outer body diameter coaxial with the axial lumen;

an annular stop flange projecting radially outward from the tubular body, the annular stop flange defined at a center of the tubular body to stop the ribbed fitting at a predetermined depth of penetration into the first resilient tube and the second resilient tube wherein the annular stop flange defines a first side of the ribbed fitting and a second side of the ribbed fitting opposite the first side of the ribbed fitting;

at least two of the annular ribs at longitudinally spaced intervals on the first side of the ribbed fitting;

at least two of the annular ribs at longitudinally spaced intervals on the second side of the ribbed fitting;

a first chamfer at a first longitudinal extremity of the tubular body to reduce a first insertion force to insert the ribbed fitting into the first resilient tube; and a second chamfer at a second longitudinal extremity of the tubular body opposite the first longitudinal extremity of the tubular body to reduce a second insertion force to insert the ribbed fitting into the second resilient tube. 3. The connection as defined in claim 2 wherein:

each of the annular ribs has bilateral symmetry about a plane normal to a longitudinal axis of the axial lumen;

a longitudinal cross-section taken through the longitudinal axis of the axial lumen and through each of the annular ribs defines a predetermined radius at an outer diameter of each of the annular ribs;

the annular stop flange has a radial clearance between a maximum diameter of the annular stop flange and an inside surface of the connector shell spatially nearest to the annular stop flange; and

each of the annular ribs has an outer diameter less than the maximum diameter of the annular stop flange.

4. The connection as defined in claim 3 wherein:

a length of the ribbed fitting is from about 4.0 mm to about 6.0 mm;

the predetermined radius is from about 0.07 mm to about 1 .03 mm;

the maximum diameter of the annular stop flange is from about 2.9 mm to about

3.1 mm;

the outer diameter of the annular ribs is from about 2.

4 mm to about 2.6 mm; the axial lumen has a constant diameter from about 0.9 mm to about 1 .1 mm; and

the outer body diameter of the tubular body is about 1 .9 mm to about 2.1 mm.

5. The connection as defined in claim 1 wherein the connector shell includes: an inside surface in contact with the first and second resilient tubes wherein: the inside surface defines a first intersecting cylinder and a second intersecting cylinder;

the first intersecting cylinder intersects the second intersecting cylinder to form an L-shaped conduit;

the first intersecting cylinder defines a first cylinder diameter; and the second intersecting cylinder defines a second cylinder diameter equal to the first cylinder diameter;

a connector shell plane defined by a first longitudinal axis of the first intersecting cylinder and a second longitudinal axis of the second intersecting cylinder; and

an inside shell piece fixedly attached to an outside shell piece at a joint surface wherein:

the joint surface defines a first joint plane orthogonal to the connector shell plane;

the first longitudinal axis of the first intersecting cylinder lies in the first joint plane;

the joint surface defines a second joint plane orthogonal to the connector shell plane; and

the second longitudinal axis of the second intersecting cylinder lies in the second joint plane.

6. The connection as defined in claim 5 wherein:

the inside shell piece defines a first inside flange parallel to the joint surface; the inside shell piece defines a second inside flange parallel to the joint surface with bilateral symmetry about the connector shell plane to the first inside flange;

the outside shell piece defines a first outside flange opposite the first inside flange parallel to the joint surface; the outside shell piece defines a second outside flange opposite the second inside flange parallel to the joint surface with bilateral symmetry about the connector shell plane to the first outside flange;

the first inside flange and the first outside flange define a first groove

therebetween; and

the second inside flange and the second outside flange define a second groove therebetween.

7. The connection as defined in claim 6 wherein:

an intersection point is defined at an intersection of the first longitudinal axis of the first intersecting cylinder and the second longitudinal axis of the second

intersecting cylinder;

a shortest distance between the intersection point and a first open end of the first intersecting cylinder opposite the intersection point is from about 9.0 mm to about 1 1 .0 mm;

a least distance between the intersection point and a second open end of the second intersecting cylinder opposite the intersection point is from about 6.0 mm to about 8.0 mm; and

the first cylinder diameter is from about 3.3 mm to about 3.6 mm.

8. The connection as defined in claim 5 wherein the inside shell piece is attached to the outside shell piece via an adhesive bond.

9. The connection as defined in claim 5 wherein the inside shell piece is attached to the outside shell piece via a weld.

10. The connection as defined in claim 1 wherein the ribbed fitting is composed of stainless steel.

1 1 . The connection as defined in claim 5 wherein the inside shell piece and the outside shell piece are composed of stainless steel.

12. The connection as defined in claim 1 wherein the first resilient tube is a different material from the second resilient tube.

13. The connection as defined in claim 1 wherein the first and second resilient tubes convey the compressed gas at a gage pressure from about 100 psi (pounds per square inch) to about 150 psi.

14. The connection as defined in claim 1 wherein:

an inside diameter of the first resilient tube and an inside diameter of the second resilient tube are equal;

an outside diameter of the first resilient tube and an outside diameter of the second resilient tube are equal; and

the first resilient tube and the second resilient tube are each formed from different materials.

15. A connector for pneumatic tubes, comprising:

a ribbed fitting defining annular ribs and an axial lumen, a first end of the ribbed fitting to be disposed in a first end of a first resilient tube, and a second end of the ribbed fitting opposite the first end of the ribbed fitting to be disposed in a second end of a second resilient tube wherein the ribbed fitting fluidly connects the first resilient tube to the second resilient tube; and

16. The connector as defined in claim 15, wherein the ribbed fitting includes: a straight, tubular body having an outer body diameter coaxial with the axial lumen;

a first chamfer at a first longitudinal extremity of the tubular body to reduce a first insertion force to insert the ribbed fitting into the first resilient tube; and

a second chamfer at a second longitudinal extremity of the tubular body opposite the first longitudinal extremity of the tubular body to reduce a second insertion force to insert the ribbed fitting into the second resilient tube.

17. The connector as defined in claim 16 wherein:

a longitudinal cross-section taken through each of the annular ribs defines a predetermined radius at an outer diameter of each of the annular ribs;

18. The connector as defined in claim 17 wherein:

a length of the ribbed fitting is from about 4.0 mm to about 6.0 mm;

the predetermined radius is from about 0.07 mm to about 1 .03 mm;

the maximum diameter of the annular stop flange is from about 2.9 mm to about .1 mm;

the outer diameter of the annular ribs is from about 2.4 mm to about 2.6 mm; the axial lumen has a constant diameter from about 0.9 mm to about 1 .1 mm; nd

the outer body diameter of the tubular body is about 1 .9 mm to about 2.1 mm.