WO1995015451A1

WO1995015451A1 - T-joint seal

Info

Publication number: WO1995015451A1
Application number: PCT/US1994/013149
Authority: WO
Inventors: Jaime L. Klomhaus; Scott Christman Gaynor
Original assignee: Huron Plastics Group, Inc.
Priority date: 1993-12-02
Filing date: 1994-11-18
Publication date: 1995-06-08

Abstract

A seal (54) for the intersection of three mating surfaces, such as at a corner, has one of the surfaces (30) provided with a seal receiving groove (50) terminating at the corner in a pocket (52). An elastomeric seal (54) is disposed in the groove (50) with a bulge projecting out of the groove. When another mating surface (32) is disposed against the surface (30) having the groove (50), the elastomeric seal (54) is flattened and displaced into the pocket (52). When the third mating surface (18) is disposed over the elastomeric seal in the pocket, a seal is effected at the corner between the three surfaces.

Description

T- JOINT SEAL

FIELD OF INVENTION

This invention relates to the sealing of joints between structural members and in particular the sealing of the joint between three structural members at a T-shaped interface therebetween.

BACKGROUND OF THE INVENTION

A so called T-joint is a joint occurring between three structural members where the interface between abutting surfaces of the members meet at a corner. An example of such a joint is the intersection between the engine block, oil pan and crankshaft seal carrier in currently manufactured automobile engines. In such a joint the engine block and seal carrier are juxtaposed to provide a first interface. Such interface may be sealed by a conventional gasket. The oil pan is then bolted to the engine block and seal carrier. The lip of the pan extends generally perpendicularly across the interface between the block and seal carrier thus forming a T-shaped joint. The sealing of such a joint is the subject of this application.

Heretofore the sealing of a T-shaped joint has usually involved applying Room Temperature Vulcanising materials to the joint area. This is a process that is secondary to the assembly of the engine block, seal carrier and oil pan, and is both messy, because of the clean-up and handling problems, and very costly because of the hand labor involved. Additionally, upon disassembly of the joint, it must be resealed in a similar fashion. The problem confronting the engine designer is to avoid this secondary operation and the attendant mess and cost. Optimally the joint should be sealed without any additional step by the line worker. To accomplish this the seal should already be in place such that merely upon bolting the members together the proper seal is effected at the T-joint. Further, the T-joint seal should be inexpensive and foolproof in operation. Considerations leading to this object involve creation of a seal that does not require human intervention, that may be created by components put in place or created at the time the structural members are themselves made, which are subject to quality control procedures that may be verified before assembly of the T-joint members and will remain with the members during subsequent handling. shipping and assembly of the joint members. Further, the

T-joint seal should be such that it may be easily assembled without special tools and preferably without interfering with the normal assembly of the structural members. SUMMARY OF THE INVENTION

We have discovered that the above objects may be nicely accomplished through the combined use of a special seal design and a two shot injection molding technique for one of the three members. In a commercial application for the joint the crankshaft seal carrier is formed of reinforced plastic by molding it as the first shot in a two-shot injection molding machine, and as the second shot an elastomeric seal is molded in situ in a groove in that face of the carrier which abuts the engine block. The groove opens through a pocket at the edge of the interface between the carrier and block covered by the oil pan and the elastomeric seal is shaped to be first slightly extruded outwardly through such edge, i.e. caused to bulge outwardly and into the interface formed when the pan is bolted across the block and carrier. This bulge of the elastomeric seal is abutted by the pan as it is bolted in place and the elastomeric seal is then compressed tightly against the opposed surfaces to effect a seal at the corner between the engine block, seal carrier and oil pan. Any excess elastomer is displaced back into the pocket in the carrier.

As a result of this mode of manufacture, the elastomeric seal fits snugly and properly in the seal carrier groove and need not be inserted in the groove as a separate operation. In the preferred embodiment, the elastomeric seal is not chemically bonded to the seal carrier and thus may move in the groove as necessary to effect a good seal and may also be peeled therefrom if it becomes necessary to replace it.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a perspective view of an automotive engine showing the engine block and oil pan with the transmission housing withdrawn slightly to expose the crankshaft seal carrier therewithin,-

Fig. 2 is a close-up perspective view of the crankshaft seal carrier mounted on the engine block with the oil pan extending beneath the carrier;

Fig. 3 is a front plan view of the seal carrier showing the elastomeric seal in the grooved face thereof,-

Fig. 3A is an enlarged fragmentary perspective view looking at the lower right hand corner of the front face of the seal carrier (as seen in Fig. 3) ; Fig. 4 is a cross-sectional view taken on the line 4-4 of Fig. 3 showing the crankshaft seal carrier with its elastomeric seal therein in it relaxed, uncompressed state prior to mounting on the engine block; Fig. 5 is similar to Fig. 4 but depicts the seal carrier bolted on the engine block and the displacement of the elastomeric seal; " Fig. 6 is similar to Figs. 4 and 5 but shows

5 the final form of the T-joint wherein the oil pan has been secured to the engine block and to the seal carrier and showing the seal effected at the T-joint therebetween; and

Fig. 7 is a cross-sectional view taken on the 10 line 7-7 of Fig. 3.

Brief description of a preferred embodiment

Referring to the drawings, Fig. 1 shows the general environment for the seal carrier embodying this invention wherein an automotive engine 10 has an engine

15 block 12 and an oil pan 16 closing the bottom of the block and forming therewith the crankcase. The lower edge face 14 of the block abuts the upwardly facing surface 18 of the pan lip 20. Normally a transmission cover or housing 22 is bolted to the rear of the engine,

20 but this is shown backed off or removed slightly to expose the crankshaft seal carrier 24 which is bolted to the rear of the engine where the crankshaft is located.

The seal carrier is better shown in Figs. 2, 3 and 3A.

It is intended to carry a crankshaft oil seal (not

. 25 shown) which surrounds the crankshaft and prevents oil in the crankcase from escaping therefrom along the crankshaft.

The seal carrier may be manufactured from a variety of materials including steel or aluminum, but in the preferred embodiment is made from reinforced plastic. Various plastics may be used for this purpose each of which should be reinforced with glass or mineral fibre. Preferred plastics may be a Polyphthalamide (ppa) , available from Amoco, or polyphenylene sulfide (pps) , available either from Phillips 66 or Hoechst

Celanese, or Nylon 4/6 which is available from DS Engineering Plastics. As shown in Fig. 3, the seal carrier 24 is of an inverted generally U-shaped configuration with the space between the sides of the U filled with the reinforced plastic material and with a circular hole 26 therethrough provided with four equidistantly spaced lugs 28 for receiving the crankshaft seal. The carrier has a front face 30 which is flat and smooth and is intended to be juxtaposed against the engine block rear face 32 to form a first interface therebetween when the carrier is bolted to the block as shown in Figs. 2 and 5. The opposite side or rear face of the carrier exhibits a peripheral flange 36 which extends around the edge 38 or periphery of the carrier. Parallel side edges 38' join with a semicircular top edge 38'' as shown in Fig. 3. Insert molded in the carrier are a plurality of steel bushings 40 which extend between the front and rear faces and are adapted to receive bolts 42 having threaded ends, not shown, to be screwed into the engine block for securing the carrier to the engine block. The bushings have integral washer-like faces or flanges 46 for underlying the heads 48 of the bolts, as shown in Fig. 4. Internally threaded metal inserts 44 may be insert molded in the bottom of the carrier and open downwardly through lower edge face 56 to receive bolts

(not shown) to secure the lip 20 of the oil pan to the carrier.

The front face 30 is provided with a groove 50 (see Fig.4) in which is an elastomeric seal 54. This seal may be formed of any suitable elastomer but in a preferred form is molded of liquid silicone rubber, or a thermoplastic elastomer, such as FTPE (a fluorinated thermoplastic elastomer) or a nitrile based thermoplastic elastomer, or Santoprene available from Advanced Elastomer Systems, or Sarlink, available from

DSM Thermoplastic Elastomers, Inc. This groove with the seal therein is spaced inwardly from the peripheral edge 38 and inwardly of the bushings 40 as best shown in Fig. 3 and terminates at opposite ends at the lower edge face 56 of the carrier. At each of the lower front edges of face 56 of the carrier the groove opens downwardly into a pocket 52 which extends rearwardly into the carrier as shown in Figs. 4-6. The pockets 52 extends laterally toward the side edges 38' stopping short thereof at the pocket end wall 58. At opposite ends of each pocket the front face of the carrier is relieved or beveled as at

51 and 53 to provide spaces into which displaced portions of the elastomeric seal may enter. The walls of the groove and the pocket walls 60, 62 and 64 and the round retention pins 79 (which are integral projections of the seal received in complementary sockets in the carrier) as shown in Fig. 4 serve mechanically to grip the elastomeric seal sufficiently to hold the seal in the groove and pockets without any chemical bonding therebetween. The elastomeric seal is preferably molded in situ in the groove 50 and pocket 52 as part of a two- shot injection molding process. Two-shot molding is a known commercial process of injection molding wherein the injection molds first receive a molten plastic material which fills the molds and either before or after this material has set-up the molds are repositioned or rearranged or another mold is moved into place and a second molten plastic material is injected into the molds and into contact with the first molded material, and the first and second molding materials are either chemically or mechanically (or both) mated together in the molds, and when set-up has occurred sufficiently for the purpose, the molds are opened and the composite part removed. In the present instance, two shot molding is used to make the crankshaft seal carrier of this invention. Such process may be carried out using a two-shot molding machine such as made by Battenfeld Maschinenfabriken GmbH & Co. KG of einerzhagen, Germany.

In the first shot the carrier 24 is first molded and the groove 50 and pockets 52 are formed therein. In the second shot the elastomeric seal 54 is molded in the groove 50 and pocket 52 and shaped as shown in the drawings. One of ordinary skill in the art of two-shot molding technique will be able to design the molds and operate the machine to produce the article as herein described and accordingly further description of the two-shot molding process will not be required.

However, there are several aspects to the design of the elastomeric seal and the seal carrier which we have found desirable or necessary to provide a satisfactory oil seal between the seal carrier and the engine block and at the T-joint formed at the corner of the interface between faces 30 and 32, the upper surface 18 of oil pan 16 and the lower edge face 56 of the carrier 24 as best shown in Fig. 6. In Fig. 7 the elastomeric seal 54 is shown in cross section in the groove 50. It has a generally rectangular shape to closely fit the groove. It exhibits along the open side of the groove a centrally arranged linearly extending triangular rib 66 having a tip 73 which projects above the adjacent surface 30 of the seal carrier. Extending along opposite sides of the rib are longitudinal grooves 69 and 71 formed in the seal and providing spaces into which the seal tip 73 may be displaced when the seal carrier is bolted to the engine block and the surfaces 30 and 32 are brought into abutment. In one satisfactory embodiment the groove 50 was .120" wide, .100" deep and the tip 73 projected above the face 30 .030" and was formed on a radius of .02".

In the pocket 52, the elastomeric seal is formed as shown in Figs. 3 and 4 to substantially fill it except that the lower surface 68 of the seal is not flush with the lower edge face 56 of the carrier, but rather is .010" above it, and face 66' instead of being triangular as in groove 50, tapers forwardly from the top wall 60 of the pocket to the bottom face 68 at an angle of 10 degrees and projects above the face 30 .030". It will also be noted that the pocket includes a forwardly facing lower wall portion 70 that directly abuts the seal adjacent the surface 68. The elastomeric seal 54 is proportioned in size relative to the pocket 50 that upon juxtaposing the engine block and seal carrier in abutting opposition as shown in Fig.5, the seal 54 is squeezed against the surface 32 of the block and displaced to project beyond the surface 14 of the block and surface 56 of the carrier as indicated at 72. A gasket 74 on the upper surface 18 of the oil pan lip 20 is disposed to seal the oil pan to the lower edge 14 of the engine block 12 and extend beneath the seal carrier as shown in Fig. 6. Upon juxtaposing the oil pan against the engine block with the lip 20 extending beneath the seal carrier surface 56 and bolting the components together to draw them into close abutment, the protruding seal portion 72 is flattened against the lip 20 (or more particularly against the gasket 74 thereon) to effect a seal at the T-joint as shown in Fig. 6. Excess elastomeric seal material is displaced into the space 76 toward the wall 58 in the pockets 52 (see Fig. 3) . The reliefs or bevels 51 and 53 at opposite ends of the pockets 52 are also adapted to provide a space between the front face 30 of the seal carrier and the opposed face 32 when the block, seal carrier and oil pan are bolted together. These may be particularly useful if the seal fills the pockets 52 and further space is needed for displaced elastomer. Thus, the design of seal 54 and groove 50 and pockets 52 enable formation of a seal between the carrier and the engine block and at the T-joint at the intersection between the three abutting surfaces of the engine block, seal carrier and oil pan. The formation of the elastomeric seal 54 in situ in the groove 50 and pockets 52 in the two-shot molding process provides a perfect fit or mating of the elastomer therein ensuring good quality control for the resulting sealed joint.

In summary, the engine block 12 and seal carrier 24 have opposed first abutting surfaces 30 and 32 and second surfaces 14 and 56 angularly related to the first surfaces and forming therewith corners on the block and carrier. The oil pan 16 has a surface 18 (or the gasket 74) which is opposed to and abuts the second surfaces 14 and 56 and the corners thereof. The seal carrier 24 has a groove 50 terminating at opposite ends in pockets 52 formed in the first and second surfaces 30 and 56 respectively at the corner thereof. An elastomeric seal 54 is disposed in the groove and pockets and projects outwardly therefrom beyond the first surface 30 thereof as best shown in Figs. 4 and 7.

The elastomeric seal 54 is proportioned in size relative to the groove 50 and pocket 52 and the surfaces 32, 30, 14, and 56 of the block and seal carrier that upon juxtaposing the block and seal carrier in abutting opposition the seal 54 is squeezed against the block and excess volume of the seal displaced into the grooves 69 and 71 and that portion of the seal in pockets 54 is squeezed to project beyond the surfaces 14 and 56 as shown in Fig. 5 at 72. Then when the oil pan 16 is juxtaposed against the block and seal carrier with its surface 18 (or gasket 74) abutting the surfaces 14 and 56 of the block and carrier, the elastomeric seal 54 is squeezed thereagainst to effect a fluid tight seal between the three members.

Claims

WHAT IS CLAIMED IS:

1. A joint for sealing the intersection between abutting surfaces of three adjacent members comprising, in combination: two members having opposed first abutting surfaces and second surfaces angularly related to the first surfaces and forming therewith corners on the two members: a third member having a surface opposed to and abutting said second surfaces of the first two members at the corners thereof; one of said two members having a pocket formed in the first and second surfaces at the corner thereof; an elastomeric seal in said pocket normally projecting beyond said first opposed abutting surface; said elastomeric seal being proportioned in size relative to the pocket and the said surfaces of the three members that upon juxtaposing the first and second members in abutting opposition the seal is squeezed against the second member and displaced to project beyond the second surfaces of the first and second members, and when the third member is juxtaposed against the first and second members with its said surface abutting the second surfaces of the first and second members the seal is squeezed thereagainst to effect a seal between the three members.

2. The invention of claim 1 wherein said elastomeric seal is formed of a material selected from the group consisting of silicone rubber and thermoplastic elastomers.

3. The invention defined by claim 1 or 2 wherein said first member is molded of a plastic material and said seal is integrally molded therewith in said pocket.

4. The invention defined by claim 1 or 2 wherein said first member and said seal are formed by two shot plastic injection molding.

5. The invention of claim 1 or claim 2 wherein said first member is a reinforced injection molded plastic and said second member is injection molded as the second stage of a two shot injection molding process.

6. The invention defined by claim 1 or 2 wherein said pocket opens outwardly through the first member and said second surface is relieved around the pocket opening to provide a space into which the seal may be displaced.

7. The invention defined by claim 1 wherein said one member has a groove formed in the said one surface thereof which groove opens at an end into said pocket; and said elastomeric seal in said pocket having a integral portion extending along such groove .

8. The invention defined by claim 7 wherein said elastomeric seal in said groove projects above the adjacent said one surface.

9. The invention defined by claim 7 wherein said elastomeric seal in said groove has a centrally arranged linearly extending triangularly shaped rib projecting out of the groove and terminating in a tip; and longitudinal grooves formed in the elastomeric seal at opposite sides of said triangularly^' shaped rib for receiving displaced portions of the rib when said two members are disposed in abutting opposition.

10. The invention defined in claim 9 wherein said pocket opens outwardly through the first and second surfaces of the first member and has a volume greater than the volume of the elastomeric seal in the pocket such that when the third member is juxtaposed against the first and second members with its said surface abutting the second surfaces of the first and second members, the elastomeric seal is squeezed thereagainst to effect a seal between the three members and any excess elastomeric seal material is displaced into the unoccupied volume of the pocket.

11. The invention defined in claim 1 wherein said one member having its said first abutting surface relieved adjacent said pocket for receiving excess of the elastomeric seal when said three members are disposed in the aforesaid abutting oppositions.

12. The invention defined by claim 1 wherein said elastomeric seal is molded in situ in said pocket.