The present invention relates to the mutual attachment of mixed metals in which each metal has a different coefficient of thermal expansion, and more particularly to a bracket system for the attaching of mixed metals with thermal compensation.
It is well known that each material has a thermal expansion coefficient which is particular to that material. As per its particular coefficient of thermal expansion, a material will change its dimensions when the temperature changes, given generally by the relation:
ΔX=αXΔT (1)
where X is the original length, ΔT is the change in temperature, α is the coefficient of thermal expansion of the material, and ΔX is the change in length in response to the ΔT.
When mixed materials are mutually superposed, most commonly one material will have a first coefficient of thermal expansion while the other material will have a second, different (usually very different) coefficient of thermal expansion; nonetheless it is possible for mixed materials to have similar, even the same, coefficient of thermal expansion. This thermal aspect of mixed materials may be illustrated by the theory behind the making of reinforced concrete. It is an “accident” of nature that steel/iron has about exactly the same thermal coefficient of expansion as that of concrete (a for steel/iron and concrete is about 12×10−6 per degree C.), and this is the reason steel or iron rods may be used in the making of reinforced concrete, whereby the steel/iron rods make the concrete much better at load bearing. However, aluminum could not be used for reinforcing concrete, as its coefficient of thermal expansion (α for aluminum is about 25×10−6 per degree C.) is very different from that of concrete, and over the temperature swings of the seasons, the concrete would be broken by the forces applied to it by the relatively larger amounts of expansion/contraction of aluminum in response to temperature change.
It is seen, therefore, that if mixed materials are mutually connected, it may be necessary to take into account the difference in the coefficients of thermal expansion over a range of temperature to which the mixed materials are expected to experience, particularly if there are two mutually separated connection locations.
An application of interest in this regard is depicted at
In modern motor vehicles, opportunities to utilize lighter materials are actively pursued, and among these may be the utilization of differing materials which are mixed and mutually connected. And, in that the temperature variation encountered may be more than that experienced by temperature changes due the seasons, as for example if the motor vehicle may be subjected to a heating booth responsive to a painting process, some accommodation of the disparate dimension change due to temperature change is desirable. As a result, if mixed metals are used in a door assembly, it is a common practice to loosely bolt the impact beam to the door panel, perform the painting process with its associated higher than seasonal heat, and then tighten the bolts; however, this practice only allows for accommodation of paint booth expansion and contraction, not that due to seasonal temperature changes, nor allow for the elevated temperatures of a second painting process should the vehicle require that in later life.
Accordingly, what is needed is a way in which mixed materials, be they dissimilar metals or other dissimilar materials, may be mutually connected together at two spaced connection locations, and yet be enabled to remain connected even as each has a mutually differing thermal expansion coefficient.
The present invention is a thermally compensating connection bracket system which allows mixed components having dissimilar coefficients of thermal expansion to be connected together at two mutually separated connection locations, and yet be able to expand and contract therebetween at different rates in response to temperature changes without adversely compromising either of the connections.
The thermally compensating connection bracket system according to the present invention provides a thermally compensated connection between two components via at least one junction composed of a junction pad of a first component, a junction slot of a second component and a junction boss of a junction boss bracket.
The junction pad is superposed the junction slot, wherein the junction slot is localized (narrow) along a transverse axis and nonlocalized (elongated) along a longitudinal axis. In this regard, the longitudinal axis is an axis along which the length between two mutually separated connection locations of the first and second components is such that there is a significant disparity between expansion and contraction of the first and second components over a predetermined operational temperature range, per equation (1); wherein the transverse axis is perpendicular to the longitudinal axis.
The junction boss bracket is disposed on a side of the second component which is opposite the first component, wherein the junction boss thereof is localized in both the longitudinal and transverse axes and passes vertically (that is, parallel to a vertical axis perpendicular to the transverse-longitudinal axes plane) through the junction slot of the second component and affixedly abuts the junction pad of the first component. While the junction boss is immovable with respect to the junction pad due to the affixment, it is movable within the junction slot along the longitudinal axis to the extent permitted by the elongation of the junction slot. Accordingly, the second component is enabled to slide relative to the first component along the longitudinal axis. The affixment between the junction boss and the junction pad may be, for example, a weld, a fastener (i.e., a threaded fastener, rivet, etc.) or other fastening modality (i.e., adhesive, etc.).
The thermally compensated connection between the first and second components may be provided by a plurality of relatively closely spaced junctions.
In operation of the thermally compensating bracket connection system of the present invention, expansion or contraction of the first component at a different rate than that of the second component with respect to temperature change is accommodated by the elongation of the junction slot along the longitudinal axis. In this regard, the first and second components will slide relative to each other to the extent permitted by movement of the junction boss within the junction slot, while the affixment clamps tightly the first component to the second component.
Accordingly, it is an object of the present invention to provide a thermally compensating connection bracket system which allows components having dissimilar coefficients of thermal expansion to be connected together and yet be able to expand and contract at different rates responsive to temperature changes without affecting the connection therebetween.
This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.
Referring now to the Drawings,
Turning attention firstly to
As a preliminary to the discussion, a directional convention is defined by longitudinal, transverse and vertical axes L, T and V depicted at
The first connection location A is provided by the thermally compensating connection bracket system 100, wherein the first component 102 is connected to the second component 104 via at least one junction 106, three being shown by way of exemplification. Each junction 106 includes a junction pad 108 of the first component 102, a junction slot 110 of the second component, and a junction boss 112 of a junction boss bracket 114. In order that multiple junctions be unaffected by temperature change, per equation (1), the spacing therebetween must be sufficiently small that that the changes in length over that small spacing can be ignored. This is exemplified at
The second component 104 is disposed between the junction boss bracket 114 and the first component 102. The junction pad 108 is superposed the junction slot 110, wherein the junction slot is nonlocalized (elongated) along the longitudinal axis L in the sense that it has a first cross-section elongated therealong, and is localized (narrow) along the transverse axis T in the sense it has a second cross-section along the transverse axis T smaller that the first cross-section. The junction boss bracket 114 carries the junction boss 112 for each junction 106, respectively. Each junction boss 112 is localized in both the longitudinal and transverse axes L, T and passes vertically (that is, along the vertical axis V perpendicular to the transverse-longitudinal axes plane P) through the junction slot 110 of the second component 104 and affixedly abuts the junction pad 108 of the first component 102, whereby each junction pad is immovable with respect to its junction boss.
The first and second components 102, 104 are able to slide relative to one another based upon the freedom of movement of the junction boss 112 in the junction slot 110. In this respect, since the first cross-section of the junction slot 110 is nonlocal (elongated) along the longitudinal axis L relative movement is allowed for expansion and contraction differentials of the first and second components over a predetermined temperature range, as per equation (1). At the same time, since the second cross-section of the junction slot 110 is constant and local along the transverse axis T, the junction boss 112 guidingly abuts the junction slot along a parallel to the longitudinal axis as it moves in response to expansion and contraction differentials of the first and second components over a predetermined temperature range, as per equation (1).
As shown by way of exemplification in
The affixment modality between the junction boss bracket 114 and the first component 102 is shown by way of example in the form of a weld 130 between the junction boss 110 (at each flat 112a of the respective flanges 112f) and the junction pad 108 of the first component 102. In this regard, the choice of material for the junction boss bracket 114 is based upon ease of weld with respect to the material of the first component 102. For example, if the first component 102 is aluminum, then for purposes of making the welds 130, the junction boss bracket 114 is similarly made of aluminum. Other affixment modalities may be used, as mentioned hereinbelow.
Advantageously included are first and second gaskets 122, 124, which may, for example, be composed of an elastomer or a polymer. The first gasket 122 is disposed between the first and second components 102, 104, and the second gasket 124 is disposed between the second component 104 and the junction boss bracket 114. An elongated gasket hole 122a, 124a is provided in the first and second gaskets 122, 124, one gasket hole for each junction 106, respectively, wherein each gasket hole is sized to be at least as large as each junction slot 110 (elongated hole 110h) of the second component 102 such that each junction boss 112 (flange 112f) passes therethrough and is operatively movable therein in response to differential length changes of the first and second components. The purpose of the first and second gaskets 122, 124 is to minimize vibration and rattling as between the first and second components 102, 104 and provide a slippage medium as between the second component with respect to both the junction boss bracket 114 and the first component. An adhesive can be applied to one side of the first and second gaskets in order to locate them immovably to one of the junction boss bracket, the first component or the second component, as the case may be.
Operation of the thermally compensating bracket connection system 100 is depicted at
In the examples, the junction boss 112 will guidingly abut the portion of the slot wall 110w which is parallel to the longitudinal axis L as the first component changes length relative to the second component 102, 104, thereby providing fixed location of the first and second components with respect to the transverse axis T.
It will be understood that the length of the first cross-section of the junction slots 110 (elongated holes 110h) is sized to accommodate the differential in length as between the mixed metals at the connection location due to expansion and contraction over a predetermined range of temperature, as per freedom of movement of the junction boss 112 therewithin. For example, the junction boss 112 (the flat 112a of the flange 112f) could be affixed at a medial disposition of the junction boss, as for example depicted at
In this illustration, the junction boss 112′ is in the form of a vertically depending frustoconical flange 112f′ of the junction boss bracket 114′ but now having a flange hole 152 formed in the flat 112a′. Each of the junctions 106′ further include a first component hole 154 which is superposed the flange hole 152. A threaded fastener 156 passes through the flange hole 152, the elongated hole 110h and the first component hole 154, and is threadably tightened thereat. In operation, the thermally induced differential in expansion and contraction as between the first and second components is accommodated as described with respect to
The use of a fastener is preferred over a weld in situations, as mentioned above, a weld would be difficult. For example if the first component is aluminum and the junction boss bracket is steel, then welding would be difficult and a fastener (threaded fastener, rivet, etc.) would be a preferred affixment modality.
During differential thermal expansion and contraction as between the first and second components 102′, 104″ as temperature changes, the movement of the second component relative to the junction boss bracket 114″ (which must always be stationary with respect to the first component 102′ due to its affixment thereto), is accommodated by distortion of the loop 142. The loop 142 can be weakened to provide better flexibility, as for example by scoring or slotting.
To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.