Fastener assembly with sleeve

Abstract: A pre-assembled workpiece (100) such as a plastic component is fastenable to a mounting surface (12) of a second workpiece (10) such as a metal automotive engine. The pre-assembled workpiece (100) includes an opening (102) extending therebetween an outer surface (101) and a mounting surface (106). A sleeve member (120) is retainably disposed in the opening (102), and a fastener (110) having a threaded shank position (112) is retainably disposed through the sleeve member (150). The fastener (110) is axially and laterally positionable relative to the pre-assembled workpiece (100), whereby the pre-assembled workpiece (100) is mountable and alignable on the mounting surface (12) of the second workpiece (10) without interference from the fastener (110). The sleeve member (120) includes a resilient first substantially radial flange member (124) whereby the sleeve member (120) is axially positionable relative to the opening (102) through the pre-assembled workpiece (100) upon fastening the pre-assembled workpiece (100) to the second workpiece (10) to compensate for misalignment tolerance and thermal expansion of the pre-assembled workpiece (100).

Description: The invention relates generally to systems and methods for a pre-assembled workpiece fastenable to a second workpiece wherein the pre-assembled workpiece compensates for manufacturing tolerances, misalignment and differing thermal expansion characteristics between workpieces, and more particularly to systems and methods for a pre-assembled plastic component mountably fastenable to a metal automotive engine by a fastener, which is part of the pre-assembled cover. Fastening members are used widely to fasten a first workpiece in mounted relation to a second workpiece, and in assembly lines and other operations it is known to pre-assemble one or more fastening members with one of the workpieces to facilitate subsequent assembly thereof with other component: The assembly of rocker arm covers, or manifolds, to internal combustion engines in the automotive industry is representative one such application among others where pre-assembled workpieces are employed with significant economic advantage. US-A-4,732,519, for example, discloses a pre-assembled valve cover having one or more fasteners and grommet assemblies retainably disposed in corresponding openings of the valve cover for subsequently fastening the valve cover to a head portion of an automotive engine. US-A-4,732,519 also teaches retaining the fasteners with sufficient axial play relative to the pre-assembled valve cover so that the fasteners do not project beyond an underside mounting surface thereof, thereby facilitating the mounting of the pre-assembled valve cover and alignment of the fasteners with corresponding holes in the engine head portion before tightening the fasteners. US-A-5,244,325 discloses a threaded fastener assembly in which a preassembled sleeve is allowed to slide axially on the fastener without slipping off the fastener. Advances in polymer technologies now permit the manufacture and use of relatively lightweight and less costly moldable plastics in applications once requiring fabricated metals. This is true also for components used in variable temperature environments, including valve covers mounted on automotive engine heads, as discussed above. Plastics, and more generally most other materials, however are subject to molding and manufacturing tolerances which may result, for example, in lateral misalignment of fasteners retained in a pre-assembled workpiece relative to corresponding holes in a second workpiece on which the pre-assembled workpiece is mounted. Plastics and other materials are also susceptible to concentrations of stress and strain, and particularly to concentrations thereof proximate fastening members extending through a workpiece. And in applications where mountably fastened workpieces of unlike materials are subject to varying temperature extremes, differences in thermally induced stresses and strains may adversely affect one or both workpieces, especially in applications where a plastic is mountably fastened to a metal. Yet known existing workpieces pre-assembled with fastening members do not compensate for manufacturing and molding tolerances of the pre-assembled workpiece, or fastener misalignment between first and second workpieces, or for the susceptibility of plastics and other materials to concentrations of stress and strain caused by fasteners, or for differing thermal expansion rates of unlike workpieces. According to a first aspect of this invention a pre-assembled workpiece fastenable to a mounting surface of a second workpiece comprises: an opening extending through a first workpiece between an outer surface of the first workpiece and a mounting surface of the first workpiece; a sleeve member retainably disposed in the opening through the first workpiece; a fastener retainably disposed through the sleeve member, the fastener having a shank portion and a head, the fastener axially positionable through the sleeve member relative to the first workpiece, characterised in that the diameter of the opening through the first workpiece is greater than an outer diameter of the sleeve member so that the fastener is laterally positionable relative to the first workpiece, whereby the pre-assembled workpiece is mountable and alignable on the mounting surface of the second workpiece without interference from the fastener retainably coupled to the first workpiece. According to a second aspect of this invention a method of making a pre-assembled workpiece fastenable to a mounting surface of a second workpiece comprises: retainably disposing a sleeve member in an opening through a first workpiece; retainably disposing a fastener having a shank and a head through the sleeve member; axially positioning the fastener through the sleeve member relative to the first workpiece; characterised by laterally positioning the sleeve member relative to the first workpiece, the opening through the first workpiece having a greater diameter than an outer diameter of the sleeve member, whereby the pre-assembled workpiece is mountable and alignable on the mounting surface of the second workpiece without interference from the fastener retainably coupled to the first workpiece. The present invention provides a novel pre-assembled workpiece and method therefor that compensates for misalignment between the pre-assembled workpiece mountable on a second workpiece, that compensates for manufacturing tolerances of the pre-assembled workpiece, that compensates for the susceptibility of the pre-assembled workpiece, especially pre-assembled plastic workpieces, to concentrations of stress and strain caused by fastening members, and that compensates for differing thermal characteristics of unlike workpieces. Particular embodiments in accordance with this invention will now be described with reference to the accompanying drawings; which may be disproportionate for ease of understanding, wherein like structure and steps are referenced by corresponding numerals and indicators; and wherein:- Figure 1 is a partially sectioned side elevation of a pre-assembled workpiece retainably mountable on a second workpiece by a fastener of the pre-assembled workpiece according to an exemplary embodiment of the invention; Figure 2 is another partially sectioned side elevation of the pre-assembled workpiece of Fig 1 illustrating axial positioning of the fastener relative thereto. Figure 3 is partially sectioned side elevation of a pre-assembled workpiece illustrating lateral positioning of a sleeve member relative to the pre-assembled workpiece; Figure 4a is a partially sectioned side elevation of a pre-assembled workpiece illustrating in more detail an opening through the pre-assembled workpiece; Figure 4b is partial to plan view along lines I-I of Figure 4a; Figure 5a is a partial plan view along lines II-II of Figure 2 according an exemplary embodiment of the invention; FIG. 5b is a partial plan view along lines II - II of FIG. 2 according an alternative embodiment of the invention; and FIGS. 6a and 6b are partial sectional views of a pre-assembled workpiece illustrating another feature of the invention. FIG. 1 is a partial sectional view of a pre-assembled workpiece 100 including a first workpiece 101 mountable on a mounting surface 12 of a second workpiece 10, and fastenable thereto by a fastener 110 retainably coupled to the first workpiece 101 and disposeable in a bore 14 of the second workpiece 10. In the exemplary application, the first workpiece 101 is a molded plastic intake manifold and the second workpiece 10 is an automotive engine component, but more generally the first workpiece 101 and the second workpiece 10 may be any members mountably fastenable together by a fastening member, wherein the workpieces are of like or unlike materials. FIGS. 1 and 2 show a sleeve member 120 retainably disposed in an opening 102 extending through the first workpiece 101 between an outer surface 104 and a mounting surface 106 thereof. The fastener member 110 has a threaded shank portion 112 and a head 114, and is retainably disposed through the sleeve member 120. The fastener 110 is axially positionable through the sleeve member 120 relative to the opening 102 through the first workpiece 101 with sufficient axial play so that the fastener 110 does not always project beyond the mounting surface 106 thereof, thereby facilitating the mounting of the pre-assembled workpiece 100 and alignment of the fastener 110 with the corresponding hole 14 in the second workpiece 10 prior to tightening the fastener 110 without interference therefrom. The fastener 110 is also positionable laterally relative to the opening 102 through the first workpiece 101 to compensate for misalignment of the threaded portion 112 of the fastener 110 and the bore 14, wherein the misalignment may result from molding or manufacturing tolerances and other factors. This type of misalignment is particularly significant in applications, including rocker arm cover applications, where the pre-assembled workpiece includes a plurality of fasteners, which must be aligned with a corresponding plurality of bores in the second workpiece. FIG. 3, 4 and 6 of the exemplary embodiment show the opening 102 of the first workpiece 101 including a protruding opening rib member 108 on the inner surface thereof. The sleeve member 120 also has a first substantially radial flange 124 at a first end thereof and a second radial flange at a second end 126 thereof. A first inner surface 125 of the first substantially radial flange 124 is engageable with the outer surface 104 of the first workpiece 101, and a second inner surface 127 of the second radial flange 126 is engageable with the opening rib member or members 108 to retainably couple the sleeve member 120 to the first workpiece 101. FIG. 4a shows the opening 102 through the first workpiece 101 having a plurality of at least two opening protruding rib members 108 arranged annularly on the inner surface thereof, wherein each opening rib member 108 has an axially aligned inclined surface 107, shown partially in FIG. 4b, and a substantially radial second flange engagement surface 109 engageable with the inner surface 127 of the second radial flange 126 of the sleeve member 120 as shown best in FIG. 6a. In one configuration shown in FIG. 4a, the axially inclined surface 107 extends substantially the entire length of the opening 102 for improved mechanical integrity. According to a related aspect of the invention, the sleeve member 120 is disposable in the opening 102 by inserting and advancing the second flange 126 of the sleeve member 120 into the opening 102 from the outer surface 104 and along the inclined surface or surfaces 107 until the inner surface 127 of the second flange 126 is engaged by the radial surface or surfaces 109 of the opening rib member or members 108. According to this aspect of the invention, either or both of the opening rib members 108 and the second flange 126 of the sleeve member 120 are sufficiently resilient to allow passage of the second flange 126 along and over the inclined surface 107 of the opening rib members 108 until the sleeve member 120 is retainably coupled through the opening 102 of the first workpiece 101. FIGS. 1-4 and 6 show the sleeve member 120 having a sleeve rib member 122 protruding from an inner surface thereof, and more generally a plurality of sleeve rib members 122 arranged annularly about an inner sleeve surface. FIG. 6b shows each sleeve rib member 122 having an inclined surface 121 and a radial surface 123. The fastener 110 includes a protruding shank rib member 116 between the threaded end portion 112 and the head 114, wherein the shank rib member 116 is more generally a plurality or continuous annularly arranged rib member as shown. FIG. 2 shows the shank rib member 116 having an inclined surface 117 and a radial surface 118. The radial surface 118 of the shank rib member 116 is engageable with the radial surface 123 of the sleeve rib member 122 and the head 114 of the fastener 110 has an enlarged flange portion 115 engageable with the first end of the sleeve member 120 to retainably couple the fastener 110 to the first workpiece. According to this aspect of the invention, the fastener 110 is axially positionable relative to the first workpiece so that the fastener 110 does not protrude beyond the mounting surface 106 of the first workpiece 101 during mounting and alignment. The fastener 110 is subsequently axially extendable into the bore 14 ofthe second workpiece 10. The inclined surface 121 of the sleeve rib member 122 and the inclined surface 117 of the shank rib member 116 cooperate and are sufficiently resilient to allow passage of the fastener 110 through the sleeve member 120 until the fastener is retainably disposed therein. FIG. 5a shows the opening 102 through the first workpiece 101 having an enlarged diameter relative to an outer diameter of the second flange 126 of the sleeve member 120, whereby the sleeve member 120 is laterally positionable in the opening 102 relative to the first workpiece 101. FIG. 5b shows the opening 102 through the first workpiece 101 enlarged in only one dimension to permit lateral positioning of the sleeve member 120 in said one dimension. According to these embodiments, the fastener 110 is movable axially but not laterally relative to the sleeve member 120, and the sleeve member 120 and fastener 110 retainably coupled thereto are movable laterally relative to the first workpiece 101. All the while though the sleeve member 120 remains retainably coupled to the workpiece 101 as discussed herein by appropriate dimensioning of the second flange 126 and the opening rib members 108. In a related alternative embodiment, the sleeve member 120 has an opening with an enlarged diameter relative to an outer diameter of the fastener 110, whereby the fastener is laterally positionable in the sleeve member 120 and thus relative to the first workpiece 101. According to this alternative embodiment, the fastener 110 is movable axially and laterally relative to the sleeve member 120, wherein the fastener 110 remains retainably coupled to the sleeve member 120 by appropriate dimensioning of the shank rib member 116 and the sleeve rib member 122. The sleeve member 120 is laterally positionable relative to the opening 102 of the first workpiece 101 and the fastener 110 is laterally positionable relative to the sleeve member 120. FIGS. 1, 2 and 6 show the first substantially radial flange member 124 of the sleeve member 120 formed as a resilient spring member, whereby the sleeve member 120 is axially positionable relative to the opening 102 through the first workpiece 101 upon fastening the first workpiece 101 to the second workpiece 10 with the fastener 110 and flexing the spring member. FIG. 6a shows the sleeve member 120 in a pre-assembled configuration, without the fastener 110 for clarity, wherein the resilient first substantially radially flange member 124 biases the sleeve member 122 partially withdrawn from the opening 102 of the first workpiece 101 so that the second radial flange member 126 is recessed relative to the mounting surface 106 of the first workpiece 101. FIG. 6b shows the resilient first substantially radial flange member 124 flexed, by clamping action of the fastener 110 not shown, to advance the sleeve member 120 into the opening 102 of the first workpiece 101 until the second radial flange member 126 is seated on the mounting surface 12 of the second workpiece 10. According to this aspect of the invention, flexed resilient first substantially radial flange member 124 maintains a prevailing torque on the fastener 110. The resilient first substantially radial flange member 124 is also flexible to allow expansion and contraction of the first workpiece 101 while maintaining the prevailing torque on the fastener 110 under variable temperature conditions. The first substantially radial flange member 124 also distributes the retention load of the fastener 110 over an increased surface area of the first workpiece 101, and the second radial flange member 126 distributes the retention load of the fastener 110 over an increased surface area of the second workpiece 10, thereby reducing any concentration of retention forces applied to the workpieces.

Claims: A pre-assembled workpiece (100) fastenable to a mounting surface of a second workpiece (10), the pre-assembled workpiece (100) comprising: an opening (102) extending through a first workpiece (101) between an outer surface (104) of the first workpiece (101) and a mounting surface (106) of the first workpiece; a sleeve member (120) retainably disposed in the opening (102) through the first workpiece (101); a fastener (110) retainably disposed through the sleeve member (120), the fastener (110) having a shank portion (112) and a head (114), the fastener (110) axially positionable through the sleeve member (120) relative to the first workpiece (101), characterised in that the diameter of the opening (102) through the first workpiece is greater than an outer diameter of the sleeve member (120) so that the fastener (110) is laterally positionable relative to the first workpiece (101), whereby the pre-assembled workpiece (100) is mountable and alignable on the mounting surface of the second workpiece (10) without interference from the fastener (110) retainably coupled to the first workpiece (101). A pre-assembled workpiece according to claim 1, the opening (102) of the pre-assembled workpiece (100) having a protruding opening rib member (108) and the sleeve member (120) having a first substantially radial flange (124) at a first end and a second substantially radial flange (126) at a second end, a first inner surface (125) of the first substantially radial flange (124) engageable with the outer surface (104) of the pre-assembled workpiece (100) and a second inner surface (127) of the second radial flange (126) engageable with the opening rib member (108) to retainably couple the sleeve member (120) to the first workpiece (101). A pre-assembled workpiece according to claim 2, in which the opening through the pre-assembled workpiece has a plurality of at least two opening protruding rib members (108), each opening protruding rib member (108) having an axially aligned inclined surface (107) and a substantially radial second flange engagement surface (109). A pre-assembled workpiece according to any one of the preceding claims, the sleeve member (120) having a sleeve rib member (122) protruding from an inner surface of the sleeve member (120), and the fastener (110) having a protruding shank rib member (116), the head (114) of the fastener (110) engageable with the first end of the sleeve member (120) and the protruding shank rib member (116) of the fastener (110) engageable with the sleeve rib member (122) to retainably couple the fastener (110) to the first workpiece (101). A pre-assembled workpiece according to any one of the preceding claims, in which the pre-assembled workpiece (100) is a plastic component fastenable to a metal automotive engine component (10). A pre-assembled workpiece according to any one of the preceding claims, in which the opening (102) through the first workpiece (101) is enlarged in one dimension only to permit lateral positioning of the sleeve member (120) in said one dimension. A pre-assembled workpiece according to any one of the preceding claims, in which the first substantially radial flange (124) member is a resilient spring member, whereby the sleeve member (120) is axially positionable relative to the opening (102) through the first workpiece (101) upon fastening the pre-assembled workpiece (100) to the second workpiece (10). A method of making a pre-assembled workpiece (100) fastenable to a mounting surface of a second workpiece (10), the method comprising: retainably disposing a sleeve member (120) in an opening through a first workpiece (101); retainably disposing a fastener (110) having a shank (112) and a head (114) through the sleeve member (120); axially positioning the fastener (110) through the sleeve (120) member relative to the first workpiece (101); characterised by laterally positioning the sleeve member (120) relative to the first workpiece (101), the opening (102) through the first workpiece (101) having a greater diameter than an outer diameter of the sleeve member (120), whereby the pre-assembled workpiece (100) is mountable and alignable on the mounting surface of the second workpiece (10) without interference from the fastener (110) retainably coupled to the first workpiece (101). A method according to claim 8, also comprising laterally positioning the fastener (110) relative to the first workpiece (101) by laterally positioning the fastener (110) relative to the sleeve member (120), the fastener (110) being retainably disposed in an enlarged opening of the sleeve member (120).

Inventors: JONES JAMES D JR, VAN BOVEN ALBERT W, JONES, JAMES D., JR., VAN BOVEN, ALBERT W.
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1998
Main classification: F16B41
IPC codes: F16B41, F02F1