Patent Description:
The present disclosure relates to a press-fit, friction-retention coupling assembly in which the two components being press-fit together are hard, inflexible materials.

The document <CIT> shows a press fit of the prior art, wherein a shaft with protrusions is fixed inside a collar.

Annular collars can be used to centrally position components within corresponding openings or recesses of another component. For example, in some cases it is desirable that the annular collar be inserted by hand into the corresponding recess and retained by friction fit. Difficulties arise in accomplishing this when both the annular collar and other component with the recess are made of very hard materials. For example, when one of the annular collar and the other component is made of metal and the other is made of an extremely hard plastic material (e.g., a Rockwell R hardness of at least <NUM> or greater).

Without the flexibility that softer materials provide, it is difficult to both (<NUM>) insure the force required to insert the annular collar into the recess is not greater than that which is suitable for manual insertion, and (<NUM>) that the contact force between the annular collar and the recess when inserted therein is sufficient to frictionally retain the annular collar within the recess. In some cases, these difficulties can be exacerbated by a further desire to also insure that insertion does not create any plastic shavings that could be left inside the manufactured product.

Without including a flexible material therebetween, the manufacturing tolerances need to be kept exceedingly small for both the outer diameter of the annular collar and the inner diameter of the recess due to the hardness of the components to simultaneously meet such combinations of desires. This is because such desires must be delivered throughout the entire range of manufacturing tolerances for both the outer diameter of the annular collar and the inner diameter of the recess, despite the hardness of the materials from which they are formed.

According to the invention, a press-fit, friction-retention coupling assembly includes an outer component formed of an outer material having a Rockwell R hardness of at least <NUM>. The outer component has a recess therein, including an outer component mating wall. An annular collar is formed of a collar material having a Rockwell R hardness of at least <NUM>. The annular collar has an annular collar mating wall including at least three protrusions. Each protrusion is surrounded by a recess so that an overall protrusion height between a base of the protrusion and a distal end thereof is greater than a protruding distance between an outer diameter of a cylindrical outer surface of the annular collar mating wall and the distal end of the protrusion. The number and configuration of the protrusions is designed to provide a press-fit insertion force of <NUM> Newtons or less throughout relevant tolerance ranges for the mating walls. The number and configuration of the protrusions is designed to provide a friction retention force sufficient to retain the annular collar within the recess under its own weight throughout relevant tolerance ranges for the mating walls.

With reference to <FIG> examples of a press-fit, friction-retention coupling assembly in accordance with the present disclosure are detailed herein. The same reference numbers are used to identify corresponding features throughout the drawings with respect to different example embodiments, regardless of whether the corresponding features are identical or not. The example press-fit, friction-retention coupling assemblies include an outer component <NUM> and an annular collar <NUM>. The outer component <NUM> is formed of an outer material having a Rockwell R hardness of at least <NUM>, or more. In some cases, the outer component <NUM> can be formed of a metal.

The outer component <NUM> (<FIG>) includes a recess <NUM> therein for receiving the annular collar <NUM>. The recess <NUM> can be a through-opening in the outer component <NUM> as illustrated. Alternatively, the recess <NUM> can extend only partially though the outer component <NUM>. Separately, the recess <NUM> can be a stepped recess in which each stepped portion <NUM>, <NUM> has a different diameter. The recess <NUM> defines an outer component mating wall <NUM>. As in the illustrated example, this mating wall <NUM> of the outer component <NUM> can be defined by the smaller diameter step portion <NUM> of the recess <NUM>. In some other examples, the recess <NUM> can have a single constant diameter throughout, or the larger diameter step portion can provide the outer component mating wall <NUM>.

The annular collar <NUM> is formed of a collar material having a Rockwell R hardness of at least <NUM>. The annular collar <NUM> can be formed of a hard polymer material. One exemplary class of such hard polymer materials is glass-filled polymers. One example of a glass-filled polymer comprises polyphenylene sulfide. One example of a glass-filled polymer comprising polyphenylene sulfide is sold by Polyplastics Co. of Tokyo, Japan, under the trade name polyphenylene sulfide®.

The annular collar <NUM> can have a stepped shape in which each step portion <NUM>, <NUM> has a different diameter. The annular collar <NUM> defines an annular collar mating wall <NUM>. As in the illustrated example, this mating wall <NUM> of the annular collar <NUM> can be defined by the smaller diameter step portion <NUM> of the annular collar <NUM>. In some other examples, the annular collar <NUM> can have a single constant diameter throughout, or the larger diameter step portion can provide the annular collar mating wall <NUM>.

The annular collar mating wall <NUM> includes at least three protrusions <NUM> with each protrusion <NUM> being surrounded by a recess <NUM> in the mating wall <NUM> so that an overall protrusion height <NUM> between a base <NUM> of the protrusion <NUM> and a distal end <NUM> thereof is greater than a protruding distance <NUM> between an outer diameter <NUM> of a cylindrical outer surface <NUM> of the annular collar mating wall <NUM> (i.e., excluding the protrusions <NUM>) and the distal end <NUM> of the protrusion <NUM>.

The number and configuration of the protrusions <NUM> of the annular collar mating wall <NUM> are designed to provide a press-fit insertion force low enough to enable an assembly line worker to manually insert the annular collar <NUM> into the recess <NUM> throughout relevant tolerance ranges for the mating walls <NUM>, <NUM> (including the protrusions <NUM>). In addition, the number and configuration of the protrusions <NUM> of the annular collar mating wall <NUM> are also designed to frictionally retain the annular collar <NUM> within the recess <NUM> of the outer component <NUM> under the overall weight of the annular collar <NUM> throughout relevant tolerance ranges for the mating walls <NUM>, <NUM>. In other words, when the components <NUM>, <NUM> are oriented so the weight of the annular collar <NUM> generates the greatest removal force due to the effects of gravity.

As in the example embodiments, a contacting relationship between the protrusions <NUM> of the annular collar mating wall <NUM> and the outer component mating wall <NUM> generates a press-fit insertion force that is <NUM> Newtons or less throughout the relevant tolerance ranges for the mating walls <NUM>, <NUM>. In some cases, the press-fit insertion force can be up to <NUM> Newtons, up to <NUM> Newtons, or up to <NUM> Newtons throughout the relevant tolerance ranges for the mating walls <NUM>, <NUM>. Additionally or alternatively, the contacting relationship between the protrusions <NUM> of the annular collar mating wall <NUM> and the outer component mating wall <NUM> can generate a friction retention force of at least <NUM>, at least <NUM> Newtons or at least <NUM> Newtons throughout the relevant tolerance ranges for the mating walls <NUM>, <NUM>.

The "relevant tolerance ranges for the mating walls" as used herein relate to the tolerance range for the inner diameter <NUM> of the mating wall <NUM> of the outer component <NUM> and for the outer diameter of the mating wall <NUM> (including the protrusions <NUM>) of the annular collar <NUM>. Thus, "throughout relevant tolerance ranges" spans from a minimum interference corresponding to the largest permissible diameter <NUM> of the mating wall <NUM> of the recess <NUM> in combination with the smallest permissible diameter of the mating wall <NUM> (including the protrusions <NUM>) of the annular collar <NUM>, to a maximum interference corresponding to the smallest permissible diameter <NUM> of the mating wall <NUM> of the recess <NUM> in combination with the largest permissible diameter of the mating wall <NUM> (including the protrusions <NUM>) of the annular collar <NUM>.

As in the example embodiments, the protrusions <NUM> can provide the only contact between the mating walls <NUM>, <NUM> throughout relevant tolerance ranges for the mating walls <NUM>, <NUM>. As in the example embodiments, the protrusions <NUM> can provide the only contact between the annular collar <NUM> and any axially extending portion of the recess <NUM> of the outer component <NUM>. In other words, there is also a cylindrical gap between the adjacent cylindrical surfaces of the stepped portions <NUM>, <NUM>.

As in the example embodiments of <FIG>, <FIG>, and <FIG> the annular recess <NUM> surrounding the protrusion <NUM> can have a teardrop shape. In addition, a pointed end of the teardrop shape recess <NUM> can be oriented toward an insertion end of the mating wall <NUM> of the annular collar <NUM>. As in the example embodiments of <FIG>, <FIG>, and <FIG>, the annular recess <NUM> surrounding the protrusion <NUM> can have a diamond shape. In addition, the diamond shape surrounding recess <NUM> can be elongated and can be oriented with the elongated overall dimension extending parallel to a central axis of the mating wall <NUM> of the annular collar <NUM>. In some other embodiments, different shapes of the annular recess <NUM> are possible.

Referring to <FIG>, lines representing four different cross-sections <NUM>, <NUM>, <NUM>, and <NUM>, respectively, of the protrusions <NUM> with surrounding recesses <NUM> are illustrated. For better clarity, the base <NUM>, overall distance or height <NUM> of the protrusion <NUM> are only referenced in <FIG> with respect to the cross-section <NUM>. Two of the cross-sections <NUM>, <NUM> correspond to protrusions <NUM> with annular recesses having the teardrop shape and orientation as illustrated in <FIG>. The difference between these two cross-sections <NUM>, <NUM> is that the respective protrusion <NUM> has an overall height <NUM> that is greater for cross-section <NUM> than for cross-section <NUM>, due to the increased depth of the respective surrounding recess <NUM>. In addition, the portion of the respective protrusion <NUM> within the protruding distance <NUM> has an axially aligned radius that is greater for cross-section <NUM> than for cross-section <NUM>.

Two of the cross-sections <NUM>, <NUM> correspond to protrusions <NUM> with annular recesses having the diamond shape and orientation of <FIG>. The difference between these two cross-sections <NUM>, <NUM> is that the respective protrusion <NUM> has an overall height <NUM> that is greater for cross-section <NUM> than for cross-section <NUM>, due to the increased depth of the respective surrounding recess <NUM>. In addition, the portion of the respective protrusion <NUM> within the protruding distance <NUM> has an axially aligned radius that is greater for cross-section <NUM> than for cross-section <NUM>.

As in the example embodiments, the overall protrusion height <NUM> between the base <NUM> of the protrusion <NUM> and the distal end <NUM> of each protrusion <NUM> can be at least <NUM> times, <NUM> times, or <NUM> times the protruding distance <NUM>, which is the distance between the outer diameter <NUM>, a cylindrical outer surface <NUM> of the annular collar mating wall <NUM> (excluding the protrusions <NUM>), and the distal end <NUM> of the protrusion <NUM>. In some embodiments, this overall protrusion height <NUM> can be up to <NUM> times, or <NUM> times the protruding distance <NUM> for each protrusion <NUM>.

As in the example embodiments, in some cases the portion of each protrusion <NUM> within the protruding distance <NUM> can have an axially aligned radius that can be at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>. Additionally or alternatively, in some embodiments, the portion of each protrusion <NUM> within the protruding distance <NUM> has an axially aligned radius that can be up to <NUM>, up to <NUM>, or up to <NUM>.

As in the example embodiments, in some cases the minimum interference between the protrusions <NUM> of the annular collar mating wall <NUM> and the mating wall <NUM> of the recess <NUM> of the outer component <NUM> throughout the relevant tolerance ranges can be at least <NUM>, at least <NUM>, or <NUM>. Alternatively or additionally, the maximum interference between the protrusions <NUM> of the annular collar mating wall <NUM> and the mating wall <NUM> of the recess <NUM> of the outer component <NUM> throughout the relevant tolerance ranges can be up to <NUM>, up to <NUM>, or up to <NUM>.

In some cases, a plurality of press-fit, friction-retention coupling assembly be used in forming a fuel cell stack. In some cases, the collar material forming the annular collar <NUM> can have a high chemical resistance. In some cases, the collar material forming the annular collar <NUM> can have a high temperature resistance. For example, the inner material forming the annular collar <NUM> can have a temperature resistance that is at least -<NUM> degrees C and up to <NUM> degrees C.

Claim 1:
A press-fit, friction-retention coupling assembly comprising:
an outer component (<NUM>) formed of an outer material having a Rockwell R hardness of at least <NUM>, and the outer component (<NUM>) having a recess therein including an outer component mating wall (<NUM>);
an annular collar (<NUM>) formed of a collar material having a Rockwell R hardness of at least <NUM>, and the annular collar (<NUM>) having an annular collar mating wall (<NUM>) including at least three protrusions (<NUM>), each protrusion (<NUM>) being surrounded by a recess (<NUM>) so that an overall protrusion height between a base of the protrusion (<NUM>) and a distal end thereof is greater than a protruding distance between an outer diameter (<NUM>) of a cylindrical outer surface (<NUM>) of the annular collar mating wall (<NUM>) and the distal end (<NUM>) of the protrusion (<NUM>); and
wherein the number and configuration of the protrusions (<NUM>) are designed to provide a press-fit insertion force of <NUM> Newtons or less throughout relevant tolerance ranges for the mating walls, and to provide a friction retention force sufficient to retain the annular collar (<NUM>) within the recess (<NUM>) under its own weight throughout relevant tolerance ranges for the mating walls.