GB2535685A

GB2535685A - An engine cover having a sealed joint

Info

Publication number: GB2535685A
Application number: GB1420335.0A
Authority: GB
Inventors: James Dominic Fisher Martin; Lavender Joe
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2014-11-17
Filing date: 2014-11-17
Publication date: 2016-08-31
Anticipated expiration: 2034-11-17
Also published as: GB201420335D0; MX2015015549A; DE102015119168A1; GB2535685B; RU2015148337A; RU2015148337A3

Abstract

An engine cover 5 having a sealed joint is provided. The joint is sealed using a polymer sealant S (see figure 8) to mating surfaces of an engine subassembly formed of a cylinder block 2 and a cylinder head 3. The engine cover 5 includes a sealant retention channel 15 that is positioned so as to span an interface between the cylinder block 2 and the cylinder head 3 formed by a non projecting gasket 4. The sealant retention channel ensures that the polymer sealant S flows to fill any gaps between the engine cover 5 and an adjacent end of the non-projecting gasket 4.

Description

An Engine Cover having a Sealed Joint This invention relates to a sealed joint made using a polymer sealant and in particular to a sealed joint for sealing a cover to an engine.

It is well known to provide a cover for an engine that is sealed and attached to a cylinder head and a cylinder block of the engine using a sealant that cures at room temperature such room temperature vulcanising sealant (RTV).

It is known to seal the cylinder head to the cylinder block using a gasket often referred to as a cylinder head gasket or a rubber coated metal cylinder head gasket. It is a problem that where the cover overlies the joint between the cylinder head and the cylinder block a T-joint is formed which is difficult to seal in a cost effective manner.

One of the problems associated with the prior art is that when the cover is fastened to the cylinder head and cylinder block the sealant located between mating surface of the cover and the cylinder head and cylinder block tends to be expunged from the joint as it is made often leaving a gap between the adjacent end of the gasket and the sealant.

It is an object of the invention to provide an engine cover that can be sealed and attached to an engine using a room temperature curing sealant to form a T-joint that restricts the squeezing of sealant from the joint during assembly thereby overcoming the above referred to problem.

According to a first aspect of the invention there is provided an engine cover for sealing attachment to an engine having a non-projecting gasket interposed between a first engine component and a second engine component so as to form a sealed joint therebetween wherein the engine cover has a peripherally extending flange defining a mating surface for -2 -sealing abutment against complementary mating surfaces on the first and second engine components and has a peripherally extending recess for accommodating a bead of sealant wherein, in a region where the flange overlies the non-projecting gasket when the engine cover is in position, the flange defines an elongate sealant retention channel extending in a peripheral direction of the engine cover flange to prevent transverse spreading of the sealant bead during assembly of the engine cover to the first and second engine components.

The length of the sealant retention channel may be in the order of 0.01m.

The recess may be defined by a sloping surface extending inwardly away from the mating surface and a lip extending around an inner periphery of the flange.

An outer wall of the sealant retention channel may be formed by an extension of the sloping surface and an inner wall of the sealant retention channel may be formed by an upstanding elongate projection on the lip of the flange.

The upstanding elongate projection may be a sealant retention block having a side face defining the inner wall of the sealant retention channel.

The sealant retention channel may be offset in a transverse direction with respect to the recess.

The peripherally extending flange may define near an outer periphery thereof a mating surface for sealing abutment against complementary mating surfaces on respective longitudinal ends of the cylinder block and may define near an inner peripheral edge of the flange the recess for accommodating the bead of sealant.

The first engine component may be an engine block and the second engine component may be a cylinder head.

According to a second aspect of the invention there is provided an internal combustion engine assembly comprising a cylinder block having a sealing surface, a cylinder head having a sealing surface, a non-projecting gasket located and compressed between the sealing surfaces of the cylinder block and the cylinder head to form an interface therebetween, an engine cover attached to the cylinder block and cylinder head and sealed to mating surfaces of the cylinder block and cylinder head by a polymer sealant wherein the engine cover is an engine cover constructed in accordance with said first aspect of the invention, each elongate sealant retention channel spans the interface between the cylinder block and the cylinder head and is filled with the polymer sealant so as to form a seal between the engine cover and an adjacent end of the non-projecting gasket.

The polymer sealant may be a room-temperature vulcanising sealant.

The polymer sealant may be arranged around the entire length of the flange of the engine cover.

The sealant retention channel may have a longitudinal axis extending in a peripheral direction of the flange.

The length of the sealant retention channel along the longitudinal axis may be in the order of 0.01m.

The invention will now be described by way of example with reference to the accompanying drawing of which:-Fig.la is a schematic side view of an internal combustion engine assembly in accordance with a second -4 -aspect of the invention having a cylinder block, a cylinder head, a cylinder head gasket and an engine cover in accordance with a first aspect of the invention; Fig.lb is an end view of the cylinder head gasket of Fig.la showing its alignment with respect to a sealant retention channel; Fig.lc is an end view of the engine cover showing a U-shaped peripheral flange of the engine cover; Fig.2 is a scrap pictorial view of a flange part of a prior art engine cover in the region of an interface between a cylinder head and a cylinder block; Fig.3 is a scrap pictorial view showing a flange part of the engine cover shown in Fig.la in the region of the interface between the cylinder head and the cylinder block; Fig.4 is a view in the direction of the arrow P on Fig.3; Fig.5 is a partial cross-section on the line x-x on Fig.4; Fig.6 is a pictorial view on the line Y-Y on Fig.4 with the cylinder head removed and the engine cover cut-away showing the positioning of a sealant retention channel in 30 the engine cover with respect to a cylinder head gasket of the engine; Fig.7 is a pictorial view of part of the engine cover showing the sealant retention channel and a sealant retention block; _ 5 _ Fig.8 is a pictorial side view of the engine with the engine cover spaced away from the cylinder head and cylinder block showing the shape of the sealant located in the region of the sealant retention channel before the engine cover is assembled to the cylinder head and cylinder block; Fig.9 is a pictorial view of an inside of an engine cover showing the location of two sealant retention channels on the engine cover; Fig.10a is a scrap cross-section showing the shape of the sealant retention channel shown in Figs. 3 to 9; Fig.10b is a scrap cross-section similar to that of Fig.lOa but showing an alternative shape for the sealant retention channel; Fig.11a is a view similar to Fig.la but showing an 20 alternative embodiment of an engine cover; and Fig.11b is an end view of the engine cover shown in Fig.11a in the direction of arrow EV on Fig.11a.

With reference to Figs.la, lb and 3 there is shown an engine 1 comprising a cylinder block 2, a cylinder head 3 and an engine cover 5 in the form of a timing cover or chain case cover.

A cylinder head gasket 4 is interposed between the cylinder head 3 and the cylinder block 2 at the interface thereof to form a seal therebetween. The engine cover 5 is sealed to the cylinder block 2 and the cylinder head 3 using a polymer sealant in the form of a flexible room temperature curing sealant such as, for example, RTV. -6 -

The engine 1 has an upper cover St having a peripheral flange 6t sealed and fastened to the top of the cylinder head 3 and sealed to an upper end of the engine cover S. The cylinder block 2 and the cylinder head 3 both having mating surfaces formed on respective longitudinal ends thereof for co-operation with a complementary mating surface 7 formed on a peripheral flange 6 of the engine cover 5.

The cylinder head gasket 4 does not extend beyond the mating surfaces of the cylinder block 2 and the cylinder head 3 and is shown in Fig.la to be slightly set back with respect to a plane M-M arranged coincident with these mating surfaces. When a cylinder head gasket does not protrude beyond the plane M-M it is said to be a 'non-projecting gasket'.

At the juncture of the cylinder block 2, cylinder head 3, cylinder head gasket 4 and the engine cover 5 a T-joint is formed as indicted by the reference "T" on Fig.la.

In Fig.lb the arrangement of the cylinder head gasket 4 with respect to an elongate sealant retention channel 15 is shown (the sealant retention channel is shown as broken outline on Fig.lb). The cylinder head gasket 4 has a transverse axis G-G and the sealant retention channel 15 has a longitudinal axis C-C. The longitudinal axis C-C of the sealant retention channel 15 is arranged at an angle e with respect to the transverse axis G-G of the cylinder head gasket 4.

As shown the angle e is substantially ninety degrees but it will be appreciated that, provided the sealant retention channel 15 crosses the cylinder head gasket 4 and is not aligned with the cylinder head gasket 4, other angular arrangements could be used. That is to say, the -7 -angle 0 must not lie within the range of 0 to 10 degrees or 170 to 180 degrees.

With reference to Fig.2 a portion of a prior art engine cover 5' is shown in the region where the T-joint will be formed when the engine cover 5' is fastened to a cylinder block and the cylinder head.

The engine cover 5' has a flange 6' forming a mating surface 7'. The flange 6' has an inner face 9' and outer face 10'. The inner face 9' is located within the engine cover 5' when the engine cover 5' is sealed and fastened in position.

Between the mating surface 7' and the inner face 9' the flange 6' is stepped so as to provide a recess 8' in which sealant is accommodated. In some cases the sealant is applied prior to assembly to the engine cover and in other cases it is applied prior to assembly to the engine block and the cylinder head. The diameter of the sealant when it is applied to the engine cover flange 6' is such that the sealant projects above the level of the mating surface 7'. Therefore, when the engine cover 5' is fastened to the engine block and cylinder head, the sealant is compressed causing it to spread transversely outwardly onto the mating surface 7' so as to form a thin film between the mating surface 7' on the engine cover 5' and the complementary mating surfaces on the cylinder block and the cylinder head and fill recess 8'. However, some of the sealant is also spread or squeezed transversely inwardly as indicated by the arrow 'E' on Fig.2. As there is no constraint on this inward transverse spreading, no significant pressure can be generated in the sealant that can be used to urge it to spread towards the cylinder head gasket so as to seal any gap between an adjacent end of a cylinder head gasket and the engine cover 5. -8 -

Referring now to Figs.3 to 9 there is shown an engine cover 5 constructed in accordance with the invention to overcome the problems associated with the prior art construction shown in Fig.2.

Fig.3 corresponds to the view of Fig.2 and as before shows a region of the engine cover 5 where the T-joint 'I' will be formed when the engine cover 5 is fastened to the cylinder block 2 and the cylinder head 3.

The engine cover 5 has a peripherally extending flange 6 forming a mating surface 7. The flange 6 has an inner face 9 and outer face 10. The inner face 9 is located within the engine cover 5 when the engine cover 5 is sealed and fastened in position.

Between the mating surface 7 and the inner face 9 the flange 6 is stepped so as to provide a recess 8 in which sealant S is accommodated prior to assembly. The recess 8 is defined by a sloping portion 8P and a lip portion 8L. As before, when the sealant S is applied to the engine cover flange 6, the diameter of the sealant S is such that the sealant projects above the level of the mating surface 7.

In order to prevent the inward transverse spreading of the sealant 5, a sealant retention channel 15 is defined between the mating surface 7 and a sealant retention block 12. The sealant retention block 12 is in the form of an elongate upstanding projection from the lip 8L and is located at an inner periphery of the flange 6. The sealant retention block 12 has a rear face aligned with the inner face 9 of the flange 6, an upper face defining a small subsidiary mating surface 12m level with the mating surface 7 and an outer face 12f forming an inner wall of the sealant retention channel 15. An outer wall of the sealant retention channel 15 is formed by a continuation of the sloping portion 8P of the flange 6. _ 9 _

The longitudinal length of the retention block 12 is such that it extends across or spans an end of the non-projecting gasket 4 that forms an interface between the cylinder block 2 and the cylinder head 3. The length of the sealant retention channel 15 is sufficient to slightly pressurise the sealant S when the engine cover 5 is fastened in place such as, for example, 0.01m (10mm).

The sealant retention channel 15 is in the case of the embodiment being described offset with respect to the recess 8 so as to optimally align the sealant retention channel 15 with a seal bead 4b (Fig.6) formed on both sides of the cylinder head gasket 4. However, it will be appreciated that the retention channel does not need to be offset.

By offsetting the sealant retention channel 15 with respect to the recess 8 also to makes it more difficult for the sealant S to flow longitudinally out of the sealant retention channel 15 when the engine cover 5 is secured to the cylinder head 2 and the cylinder head 3 and so further increases pressurisation of the sealant S by the sealant restraint channel 15 thereby aiding the flow of sealant S towards an adjacent end of the cylinder head gasket 4.

Therefore, when the engine cover 5 is fastened to the engine block 2 and cylinder head 3, the sealant S is compressed causing it to spread transversely onto the mating surface 7 so as to form a thin film between the mating surface 7 on the engine cover 5 and the complementary mating surfaces on the cylinder block 2 and the cylinder head 3. However, due to the fact that the sealant S is constrained by the opposing walls 8P, 12f defining the sealant retention channel 15 some of the sealant S is also spread or squeezed towards the cylinder head gasket 4 so as to ensure that any gap between the cylinder head gasket 4 and the engine cover 5 is filled with sealant S. -10 -In order to make room for the sealant retention block 12 and the sealant retention channel 15, the flange 6 of the engine cover 5 has an outwardly extending tab 11. The tab 11 allows the width of the sealant retention channel 15 to be wider than the general width of the sealant S around the remaining portion of the periphery of the flange 6 and also allows the sealant retention channel 15 to be offset from the recess 8. The use of a wider sealant retention channel 15 permits more sealant S to be applied in the region of the T-joint further increasing the probability that any gaps between the cylinder head gasket 4 and the engine cover 5 are filled with sealant S. Fig.6 shows how the sealant retention channel 15 is aligned with both the cylinder head gasket 4 and a rubber bead 4b formed on the cylinder head gasket 4, the cylinder head gasket 4 being in this case a non-projecting rubber coated metal gasket.

Fig.8 shows the shape of the sealant S prior to attachment of the engine cover 5 in a case where the sealant has been applied to the cylinder block 2 and the cylinder head 3. The thickness or diameter of the sealant Se is greater in the region where the sealant retention channel 15 is located than the thickness of the sealant S elsewhere on the cylinder block 2 and cylinder head 3. It will be appreciated that it is wasteful and expensive to apply the sealant S at the /diameter (Se) used in the region of the sealant retention channel 15 around the entire perimeter of the flange 6 of the engine cover 5. Therefore the use of the sealant retention channel 15 allows a larger amount of sealant to be positioned at the T-joint where it is required to form a seal with an adjacent end of the cylinder head gasket 4 but not elsewhere on the flange 6 of the engine cover 5. The same situation would apply if the sealant S is applied to the engine cover 5 rather than to the cylinder block 2 and cylinder head 3 because, in that case, the sealant retention channel 15 is filled or slightly overfilled with sealant S prior to the assembly of the engine cover 5 to the cylinder block 2 and cylinder head 3.

Fig.9 shows the location of two sealant retention channels and blocks on the engine cover 5 in regions 'TJ' corresponding to the positions of the T-joints when the engine cover S is in position on the engine 1.

As can be seen in Figs.lc and 9, the flange 6 of the engine cover 5 does not extend around the entire outer periphery of the engine cover 5 because at a top end it abuts against the upper cover 5t. The flange 6 is in this case a U-shaped flange 6 and extends along three sides of the engine cover 5. The sealant is arranged around the entire length of the flange 6 of the engine cover 5 that is sealed to the cylinder block 2 and the cylinder head 3.

In an alternative embodiment shown in Figs.11a and llb where an engine cover 105 extends up the entire side of the engine, a flange 106 extends around the full periphery of the engine cover 105 and the sealant is in such a case arranged around the entire peripheral length of the flange 106 of the engine cover 105.

Fig.10a shows in a simplified manner the shape of the sealant retention channel 15 as applied in Figs.3 to 9 to the cover flange 6. The sealant retention channel 15 has one substantially upright wall 12f formed on the sealant retention block 12 and one sloping wall 09 leading to the mating surface 7.

It will be appreciated that the invention is not limited to a sealant retention channel having such a profile and, as shown in Fig.10b, a sealant retention channel 15a is defined in an engine cover flange 6a between a sealant -12 -retention block 12a and a mating surface 7a. The sealant retention channel 15a is in this case defined by a pair of sloping walls 12s, 8P and the sloping wall 8P is formed by a continuation of the sloping portion of the flange 6 and so is given the same reference characters.

Therefore, in summary, by providing a channel in the region of the T-joint that constrains the transverse flow of sealant and increases the pressure in the sealant during fastening of the engine cover to the cylinder block and cylinder head the sealant can be urged towards the cylinder head gasket to form a good seal therebetween.

In accordance with a second aspect of the invention there is provided an internal combustion engine assembly comprising the cylinder block 2 having a sealing surface, the cylinder head 3 having a sealing surface, a non-projecting gasket 4 located and compressed between the sealing surfaces of the cylinder block 2 and the cylinder head 3 to form an interface therebetween. The engine cover 5 is attached to the cylinder block 2 and to the cylinder head 3 and is sealed to the mating surfaces of the cylinder block 2 and cylinder head 3 by the polymer sealant S such that the or each sealant retention channel 15 spans the interface between the cylinder block 2 and the cylinder head 3. The polymer sealant Se fills the polymer sealant retention channel 15 so as to form a seal between the engine cover 5 and the adjacent end of the non-projecting gasket 4. As before, the polymer sealant is a room-temperature vulcanising sealant and is arranged to extend around the entire periphery of the flange 6 of the engine cover 5.

The sealant retention channel 15 has longitudinal axis extending in a peripheral direction of the flange 6 and the length of sealant retention channel is approximately 0.01m (10mm).

-13 -One of the advantages of the invention is that it is not necessary for any grooves or recesses to be formed in either the cylinder head or the cylinder block. The only change required is to the engine cover. The invention could therefore be used on existing engines by simply replacing a current engine cover with an engine cover constructed in accordance with this invention.

It is a further advantage of the invention is that it is not necessary in order for the invention to work for the cylinder head gasket to project out from the end of the cylinder block, cylinder head assembly. Therefore it is not necessary to use or replace a conventional cylinder head gasket with a specially designed projecting cylinder head gasket produced at increased cost. This allows the use of the invention on engines using a conventional cylinder head gasket thereby increasing its applicability.

Although the invention has been described with reference to its use where a cylinder head is sealed and fastened to a cylinder block and a thin non-projecting gasket is interposed between the cylinder block and the cylinder head it will be appreciated that it is also applicable to other joint where a thin non-projecting gasket is interposed between first and second engine components and a third component such as a cover is sealed and fastened to the first and third components so as to form a T-joint. The first and second components could, for example, be a cylinder block and a bearing support ladder or upper and lower parts of a two part cylinder head.

It will be appreciated by those skilled in the art that although the invention has been described by way of example with reference to one or more embodiments it is not limited to the disclosed embodiments and that alternative embodiments could be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

-14 -Claims 1. An engine cover for sealing attachment to an engine having a non-projecting gasket interposed between a 5 first engine component and a second engine component so as to form a sealed joint therebetween wherein the engine cover has a peripherally extending flange defining a mating surface for sealing abutment against complementary mating surfaces on the first and second engine components and has a 10 peripherally extending recess for accommodating a bead of sealant wherein, in a region where the flange overlies the non-projecting gasket when the engine cover is in position, the flange defines an elongate sealant retention channel extending in a peripheral direction of the engine cover flange to prevent transverse spreading of the sealant bead during assembly of the engine cover to the first and second engine components.
2. An engine cover as claimed in claim 1 wherein the recess is defined by a sloping surface extending inwardly away from the mating surface and a lip extending around an inner periphery of the flange.
3. An engine cover as claimed in claim 2 wherein an outer wall of the sealant retention channel is formed by an extension of the sloping surface and an inner wall of the sealant retention channel is formed by an upstanding elongate projection on the lip of the flange.
4. An engine cover as claimed in claim 3 wherein the upstanding elongate projection is a sealant retention block having a side face defining the inner wall of the sealant retention channel.
5. An engine cover as claimed in any of claims 1 to 4 wherein the sealant retention channel is offset in a transverse direction with respect to the recess.

-15 -
6. An engine cover as claimed in any of claims 1 to 5 wherein the peripherally extending flange defines near an outer periphery thereof a mating surface for sealing abutment against complementary mating surfaces on respective longitudinal ends of the cylinder block and defines near an inner peripheral edge of the flange the recess for accommodating the bead of sealant.
7. An engine cover as claimed in any of claims 1 to 6 wherein the first engine component is an engine block and the second engine component is a cylinder head.
8. An internal combustion engine assembly comprising a cylinder block having a sealing surface, a cylinder head having a sealing surface, a non-projecting gasket located and compressed between the sealing surfaces of the cylinder block and the cylinder head to form an interface therebetween, an engine cover attached to the cylinder block and cylinder head and sealed to mating surfaces of the cylinder block and cylinder head by a polymer sealant wherein the engine cover is an engine cover as claimed in claim 7, each elongate sealant retention channel spans the interface between the cylinder block and the cylinder head and is filled with the polymer sealant so as to form a seal between the engine cover and an adjacent end of the non-projecting gasket.
9. An engine assembly as claimed in claim 8 wherein 30 the polymer sealant is a room-temperature vulcanising sealant.
10. An engine assembly as claimed in claim 8 or in claim 9 wherein the polymer sealant is arranged around the entire length of the flange of the engine cover.

-16 -
11. An engine assembly as claimed in any of claims 8 to 10 wherein the sealant retention channel has a longitudinal axis extending in a peripheral direction of the flange.
12. An engine cover substantially as described herein with reference to the accompanying drawing.
13. An internal combustion engine assembly substantially as described herein with reference to the accompanying drawing.