Patent Application
20190211854
The disclosed inventive concept relates to fastening arrangements for attaching a first component to a second component. More particularly, the disclosed inventive concept relates to a system for fastening two components together comprising a first component having a fastener bore terminating in a counterbore, a second component having a fastener bore terminating in a counterbore, a fastener for attaching the components together, and an elastomeric member positioned in the counterbores. Upon attachment of the two components together using the fastener, the elastomeric member is compressed and expands laterally to substantially fill the cavity formed by the two counterbores. The disclosed system thus resists shear motion between the two attached components.
Common to many industries is the need to attach one component to another component where the components are frequently composed of dissimilar materials. Several methods of attachment are known, including the use of one or more threadforming fasteners. This type of inexpensive fastener is used in, for example, the automotive industry for attaching a metal component, such as a throttle body, to a polymerized component, such as a nylon composite intake manifold. Other uses in the automotive industry may be identified.
This approach, however, has certain known disadvantages that may be easily identified. Referring to
A characteristic of polymerized material, in this case, nylon, is that it tends to creep. Over time, plastic creep in the throttle body-to-intake manifold joint (containing the gasket to seal the joint) can result in a loss of bolt stretch thereby reducing clamp load as illustrated by the arrow A in
Recognizing the described deficiency and in an effort to overcome the problems associated therewith, an approach has been taken to prevent shear motion. Illustrated in
However, this pin-to-hole type of design also suffers from certain limitations. Specifically, the ideal joint will always assemble under an arethmetic tolerance stack-up. This stack-up includes the accumulation of positional and geometrical tolerances of each of the features used. With a single pin 26/hole 28 feature as illustrated in
In an additional approach to solving the known challenges encountered when using a threadforming fastener to attach a throttle body to a nylon intake manifold, “crushable” plastic features have been used. However, these arrangements as well as “designed interference” fits have been shown to create issues with fastener rundown consistency.
Accordingly, known approaches to attaching a metal part, such as an aluminum throttle body, to a part made from a polymerized material, such as a nylon intake manifold, using a threadforming fastener have not provided completely satisfactory results. As in so many areas of vehicle technology, there is always room for improvement related to fastening systems used in the automotive vehicle for attaching a first component to a second component.
The disclosed inventive concept provides a system for fastening two components together. The system disclosed herein is a cost-effective and practical solution to the challenges faced when using known arrangements for fastening two components to one another in any of a broad variety of applications.
The components may be of the same or may be of different materials. However, the system is particularly adapted for use in fastening a metal component, such as an aluminum throttle body, to a component composed of a polymerized material, such as an intake manifold. The metal component has a fastener bore terminating in a counterbore and the component made from a polymerized material has a fastener bore terminating in a counterbore. When positioned next to one another, the counterbore of the throttle body faces the counterbore of the intake manifold forming a cavity therebetween.
A fastener, such as a threadforming fastener, is provided for attaching the throttle body to the intake manifold. A sealing gasket is preferably positioned between the throttle body and the intake manifold.
An elastomeric member, such as an elastomeric ring, is positioned in one of the two counterbores. The ring is configured to sit proud of the contact surfaces between the components. Upon attachment of the two components together using the fastener, the elastomeric member is compressed, thereby causing the elastomeric member to become deformed from the initial geometry of its original shape to a deformed geometry wherein the elastomeric member expands laterally to substantially fill the cavity formed by the two counterbores due to the Poisson's ratio of the material. The stiffness and geometry of the elastomeric ring may be tuned to provide the optimal filling of the void between the components and the fastener based on a number of variables, such as but not being limited to the compression distance, the joint geometry, and the positional and geometrical tolerances. The rundown torque traces of the elastomer ring are very consistent, similar to the effect seen on elastomer gasket rundown.
The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.
For a more complete understanding of this invention, reference should now be made to the embodiment illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein:
In the following figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting.
The accompanying figures and the associated description illustrate the fastening system according to the disclosed inventive concept. The embodiment of the disclosed inventive concept is illustrated as being of a certain shape and configuration in which a metal component is attached to a component composed of a polymerized material. It is to be understood that the shapes of the embodiments of the fastening system of the disclosed inventive concept shown in the figures is only illustrative as other shapes may be possible without deviating from the spirit and scope of the disclosed inventive concept.
Referring to
Extending through the first component 42 is a fastener bore 46 that terminates in a counterbore 48. The fastener bore 46 is preferably a smooth bore. Extending through the second component 44 is a fastener bore 50 that terminates in a counterbore 52. The fastener bore 50 may be a smooth bore in which threads are formed if a threadforming fastener is used or may be a threaded bore if a conventional threaded fastener is used. Preferably, the counterbores 48 and 52 are each the same depth and same width.
A sealing gasket 54 is disposed between the first component 42 and the second component 44. The sealing gasket 54 may be formed from any material suitable to the purpose of providing a fluid-tight seal between two components. The sealing gasket 54 includes a fastener-passing hole formed therein.
A threaded fastener 56 is used for fastening the first component 42 to the second component 44. The threaded fastener 56 includes a fastener head 58 and threads 60. Preferably, but not absolutely, the threaded fastener 56 is of the threadforming type.
An elastomeric member 62 is fitted in one of the components 42 and 44 prior to assembly. The elastomeric member 56 may be of any shape but is preferably ring-shaped. The elastomeric member 56 may be made of any of several compressible materials. Non-limiting examples of such materials include nitrile elastomers, EPDM, fluorosilicone, fluoroelastomer, natural and synthetic polyisoprene, neoprene, polyurethane, silicon, and thermoplastic rubber.
Regardless of the selected material, the elastomeric member 56 is capable of being reshaped from its initial, uncompressed and pre-loaded geometry as illustrated in
With reference to
As the first component 42 and the second component 44 are brought into contact with opposite sides of the sealing gasket 54, the elastomeric member 62 is increasingly compressed, resulting in the elastomeric member 62 being extended laterally until the first component 42 and the second component 44 are brought into fullest possible contact with the sealing gasket 54 and it is not possible to thread the threaded fastener 56 any further. This final condition is illustrated in
In this compressed state, the elastomeric member 62 minimizes or prevents entirely shear motion of the first component 42 relative to the second component 44. The stiffness and geometry of the elastomeric member 62 may be tuned to provide optimal filling of the cavity formed by the counterbores 48 and 52 based on the compression distance, the joint geometry and the positional and geometrical tolerances.
Thus, the disclosed invention as set forth above overcomes the challenges faced by known approaches to attaching a first component to a second component in many applications, but particularly in the automotive setting. The combination of the counterbores 48 and 52 and the use of the elastomeric member 62 provides a relatively low cost solution to the known challenges of providing a desirable connection between components. In addition, the fastening system of the disclosed inventive concept can be readily disassembled and reassembled while re-using the elastomeric component 62, thus minimizing time and cost required for servicing the vehicle. Even with these several advantages in mind, one skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
