Patent Application
20080226419
The present invention relates generally to a fastening device, and more particularly to a fastening device that includes an integrated spring.
Fastening devices are used to couple a first work-piece in mounted relation to a second work-piece. In an assembly line application, components may be pre-assembled using one or more fastening devices to facilitate subsequent assembly thereof with other components. The assembly of rocker arm covers, or manifolds, to internal combustion engines in the automotive industry is representative of one such application among many others where pre-assembled work-pieces are employed with significant economic advantage.
One known method of coupling the first work-piece to the second work-piece includes using a non-isolated system. In a non-isolated system, the first work-piece is coupled directly to the second work-piece in a rigid or non-forgiving assembly. Another method of coupling the first work-piece to the second work-piece includes using an isolated system. In an isolated system, the first work-piece is decoupled from the second work-piece, such that noise, vibration, harshness, etc. generated by the second work-piece is not transferred to the first work-piece. One known isolated system utilizes a grommet installed between the first and second work-pieces to isolate the work-pieces.
For example, a pre-assembled valve cover may include one or grommets disposed in corresponding openings of the valve cover for subsequently fastening the valve cover to a head portion of an automotive engine. While isolated systems are preferable in many assembly applications, certain drawbacks exist. For example, isolated systems include an increased quantity of components in the assembly, e.g. grommets. Moreover, grommets may degrade or wear during use. As a result, the material costs of utilizing an isolated system increase due the increased costs of the component assemblies.
A need remains for a fastening device that provides the benefits of an isolated system, while also decreasing the quantity of parts and thus the cost to fabricate the isolated system.
In one embodiment, a fastening device is provided that includes a fastener body configured to be received in the first work-piece. The fastening device also includes a spring assembly coupled to the fastener body. The spring assembly includes a flange member, and a plurality of tunable springs extending radially outward from the flange member, the tunable springs are each configured to deform when a predetermined pressure is applied to the flange member, the predetermined pressure is sufficient to couple the first work-piece to the second work-piece. The plurality of tunable springs are spaced equidistantly around a periphery of the flange member. The plurality of tunable springs may be formed unitarily with the flange member.
In another embodiment, a method is provided for fabricating a fastening device for coupling a first work-piece to a second work-piece. The method includes determining a coupling force to be utilized to couple the first work-piece to the second work-piece, and fabricating a fastening device including a fastener body and a spring assembly coupled to the fastener body. The method further includes forming the spring assembly with a plurality of tunable springs that extend radially outward from the fastener body. The tunable springs are formed to deform when a predetermined pressure is applied to the fastening device. The predetermined pressure relates to the coupling force.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.
The first work-piece 10 has an opening 20 extending there through that is sized to receive fastening device 100. The opening 20 has a diameter 22 that is greater than a diameter 24 of the fastening device 100 as will be discussed below. The first work-piece 10 has an inner surface 30 and an outer surface 32. As shown in
The exemplary fastening device 100 includes a fastener body 102 having an opening 104 extending there through. The fastener body 102 is configured to capture the fastener 46, and allow the fastener 46 to extend or retract through the fastener body 102. As such, the fastener body 102 is substantially tubular and has a centerline axis 106 extending axially there through. The fastener body 102 has a first end 108 and an opposite second end 110. The opening 104 has a diameter 112 that is greater than a diameter 48 of fastener 46 to enable the fastener 46 to be inserted at least partially through the opening 104. The fastener body 102 also has an outer diameter 114 that is less than the diameter 22 of opening 20 to enable the fastener body 102 to be inserted at least partially through opening 20.
The fastening device 100 further includes a radial spring assembly 120 that is coupled to the first end 108 of the fastener body 102 and a second radial flange 123 that is coupled to the second end 110 of the fastener body 102. In one embodiment, the second radial flange 123 has a diameter 125 that is less than the diameter 22 of opening 20 to enable the fastener body 102 to be inserted through the opening 20. In the exemplary embodiment, the diameter 125 of the second radial flange 123 is greater than the diameter 22 of opening 20 and the second radial flange 123 is fabricated from a flexible material to enable the fastener body 102 and the second radial flange 123 to be inserted into the opening 20.
In the exemplary embodiment, the flange member 122 is formed on the first end 108 of the fastener body 102 such that flange member 122 is approximately perpendicular to an outer periphery of fastener body 102. The flange member 122 has a substantially circular shape and includes an opening 126 extending there through. As such, opening 126 has a diameter 128 that is approximately equal to the diameter 112 of fastener body opening 104. Flange member 122 also has an outer diameter 130 that is greater than the diameter 112 of opening 104.
The spring assembly 120 may include one or more tunable spring arms 124. Each tunable spring arm 124 has a width 132 and a length 134. More specifically, the width 132 and length 134 of spring arm 124 is approximately equal to a respective width 140 and length 142 of a slot 144 formed in flange member 122. By way of example only, the spring arms 124 may be stamped and formed from the flange member 122 to form respective slots 144 in the flange member 122. In the exemplary embodiment, the spring arms 124 are spaced equidistantly around a periphery of the flange member 122. The width 132, length 134 and thickness of the spring arms 124 collectively form a portion of the dimensions that determine an amount of pressure that the spring assembly 120 is able to endure before deforming.
Each spring arm 124 includes a spring portion 150 having a first end that is coupled to, or formed unitarily with, the flange member 122. The spring arm also includes an integral contact portion 152 formed at a distal end of the spring portion. As shown in
In the exemplary embodiment, to fabricate fastening device 100, fastening device 100 is stamped from a single plate to form fastener body 102 and spring assembly 120. Optionally, spring assembly 120 is coupled to fastener body 102 using a welding or brazing procedure, for example. The spring assembly is stamped to form the flange member 122 and the plurality of spring arms 124. In the exemplary embodiment, each spring arm 124 is identical to each other respective spring arm 124 such that during fabrication, a single stamp may be utilized to manufacture multiple spring arms 124.
As discussed above, the spring arms 124 distributes the load applied by the bolt 46 onto a work-piece to allow the work-piece to move a designed amount to compensate for noise, vibration, or harshness purposes. As such, the spring arms 124 are tunable to fit any particular application and load curve desired. One such method of tuning the spring arms 124 is to fabricate the fastening device 100, including spring arms 124, from a selected material. The fastening device 100 may be fabricated from a particular metallic material to facilitate increasing the fastening device 100 ability to compensate for increased vibration or harsh conditions. For example, under some conditions, it may be desirable to fabricate the fastening device 100 using a stainless steel material. Under other operating conditions, it may be desirable to fabricate the fastening device using a copper or brass material for example. Under all conditions, the material for fastening device 100 is selected based on the various operational parameters, i.e. torque required, temperature, etc., to which the fastening device 100 is to be subjected.
Another exemplary method of tuning the fastening device 100 is to alter the quantity, size, or thickness of the spring arms 124. For example, to increase the stiffness and thus the load bearing capabilities of the spring arms 124, it may be desirable to increase a thickness 127 of the spring arms 124. To increase the surface area of the spring arms 124 contacting the work-piece 12, it may be desirable to increase the quantity of spring arms 124. Moreover, the length and/or width 132/134 of the spring arms 124 may be adjusted to allow for a decreased or increased torque to be transmitted from the bolt 46 to the second work-piece 12, i.e. to increase the pressure coupling the first and second work-pieces 10 and 12 together. For example, decreasing the length 134 and/or increasing the width 132 of a spring arm 124 increases the overall stiffness of the spring arm 124 which allows greater torque to be transmitted to the second work-piece 12. Whereas increasing the length 134 and/or decreasing the width 132 of the spring arm 124 results in a fastening device 100 which may be used to fasten work-piece 10 and work-piece 12 using less torque. Additionally, the fastener body 102 may function as a compression limiter allowing the fastener 46 to be adjusted to its proof load without crushing the fastener body 102.
During operation, the spring arms 124 maintain a predetermined torque on the fastener 46. Moreover, the spring arms 124 are flexible to enable the work pieces 10 and 12 to expand or contract while still maintaining the predetermined torque on the fastener 46 under variable operating conditions. The spring arms 124 also distribute the retention load of the fastening device 100 over an increased surface area of the first work-piece 10 thereby reducing any concentration of retention or coupling forces applied to the work-pieces.
As discussed above, the tunable springs 124 are fabricated to deform at the predetermined pressure. To form an isolated system and thus reduce and/or eliminate the noise, vibration, or harshness between the first and second work-pieces 10 and 12, the spring arms 124 are configured to flex or deform when a desired amount of pressure is applied by the fastener 46. As such, when the desired amount of pressure is applied to fastening device 100, spring arms 124 are configured to deform at a pressure that is less than the pressure required to deform either work-piece 10 or work-piece 12.
In one exemplary embodiment, shown in
As shown in
The tunable spring arm 324 also has a length 334. The length of spring arm 324 is based on the overall circumference of the spring assembly 320. For example, in the exemplary embodiment, the quantity of spring arms 324 is based on the equation S=rΦ, where r is the radius of fastening device, S is the length of the combination of the tunable spring arm 324 and a respective tab 323, and Φ is the linear angle between each combination of the tunable spring arm 324 and a respective tab 323. For example, as shown in
To fabricate fastening device 300, fastening device 300 is stamped from a single plate to form fastener body 302 and spring assembly 320. Optionally, spring assembly 320 is coupled to fastener body 302 using a welding or brazing procedure, for example. The spring assembly 320 is stamped to form the flange member 322 and the plurality of spring arms 324. In the exemplary embodiment, each spring arm 324 is identical to each other respective spring arm 324.
As discussed above, the spring arms 324 distribute the load applied by the bolt 46 onto a work-piece to allow the work-piece to move a designed amount to compensate for noise, vibration, or harshness purposes. As such, the spring arms 324 are tunable to fit any particular application and load curve desired. One such method of tuning the spring arms 324 is to fabricate the fastening device 300, including spring arms 324, from a selected material as discussed above. Another exemplary method of tuning the fastening device 100 is to alter the quantity, size, or thickness of the spring arms 324. For example, to increase the stiffness and thus the load bearing capabilities of the spring arms 324, it may be desirable to increase the surface area of the spring arms 324 contacting the work-piece 12. It may also be desirable to increase the quantity of spring arms 324 as discussed above. Moreover, the length and/or width of the spring arms 324 may be adjusted to allow decreased or increased torque to be transmitted from the bolt 46 to the second work-piece 12, i.e. to increase the pressure coupling the first and second work-pieces 10 and 12 together.
One such method of tuning the spring assembly 420 is to fabricate the fastening device 400, including springs 424, from a selected material as discussed above. Another exemplary method of tuning the fastening device 400 is to alter the quantity, size, or thickness of the springs 424. For example, to increase the stiffness and thus the load bearing capabilities of the springs 424, it may be desirable to increase the surface area of the springs 424 contacting the work-piece 12, e.g. to increase the quantity of springs 424. Moreover, the length and/or width of the springs 424 may be adjusted to allow decreased or increased torque to be transmitted from the bolt 46 to the second work-piece 12, i.e. to increase the pressure coupling the first and second work-pieces 10 and 12 together.
In the exemplary embodiment, the quantity of springs 424 is based on the equation S=rΦ, where r is the radius of fastening device, S is the length of the spring 424, and Φ is the angle between respective springs 424. For example, as shown in
To fabricate fastening device 400, fastening device 400 is stamped from a single plate to form fastener body 402 and spring assembly 420. Optionally, spring assembly 420 is coupled to fastener body 402 using a welding or brazing procedure, for example. The spring assembly 420 is stamped to form the flange member 422 and the plurality of springs 424. In the exemplary embodiment, each spring 424 is identical to each other respective spring 424. However, the springs 424 are arranged in an alternating convex and concave arrangement as discussed above.
Described herein is a fastening device that includes a metallic spring that is formed in the top of a drawn tube as a means of preventing vibration from transferring from a base to a work-piece. A bolt passes through a center of the tube. When the bolt is tightened, the bolt transfers load into the spring and the spring begins to compress. The metal tube limits the compressive force created by the bolt. The spring transfers the load to the top of the first work-piece. A rubber gasket is installed on the bottom of the first work-piece to transfer the load from the first work-piece to second work-piece. When the second work-piece vibrates the compressed gasket and metal spring absorb kinetic energy and reduce the amount of vibration force that is transferred to the first work-piece.
The fastening device described herein utilizes fewer components than known fastening devices by eliminating the known grommet system. Moreover, the fastening device is more durable that the rubber grommet. There is potentially less tolerance stack-up in the fastening device since there is one less component, i.e. the grommet has been eliminated. Additionally, the isolation effect of the fastening device described herein is greater than the known rubber grommet system, i.e. the transmissibility ratio of the first work-piece to the second work-piece is reduced. Lower ratio value equates to more isolation benefit.
Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.
The present invention addresses these drawbacks and other drawbacks by providing a fastening device that replaces the functionality of the grommet yet eliminates the need for the grommet. In short, the fastening device described herein provides a new sleeve for use in an isolated system.
Various features of the invention are set forth in the following claims.
This Non-Provisional Application claims benefit to U.S. Provisional Application Ser. No. 60/906,978 filed Mar. 14, 2007, the complete subject matter of which is expressly incorporated herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60906978 | Mar 2007 | US |
