Patent Description:
Gas engines are often fitted with a pre-combustion chamber in fluid communication with the combustion chamber. Fuel gas is supplied directly to the pre-combustion chamber where it is ignited to detonate the main charge in the combustion chamber.

The fuel gas may be supplied via a pipe which extends through a passageway in the engine body (typically the cylinder head) to a cavity in the cylinder head in which a chamber body defining the pre-combustion chamber is housed.

It is necessary to seal the pipe in fluid communication with the pre-combustion chamber to prevent the fuel gas from leaking.

In one conventional arrangement, the fuel gas supply pipe is sealed to the chamber body within the cylinder head by means of a metal sealing tube arranged between the outlet end of the pipe and the inlet orifice of the chamber body, with metal-to-metal interference contact all around its circumference at each end of the tube.

This requires accurate dimensional and surface quality control and so is a technically demanding and expensive solution.

Care is also required to exactly align the inlet orifice of the chamber body with the pipe, and to avoid unseating the chamber body in the cavity of the cylinder head by the sealing force which is applied to the tubular seal by axial compression of the pipe.

There may also be difficulty in remaking the seal satisfactorily after maintenance.

In another conventional arrangement, the fuel gas supply pipe and the chamber body are sealed to the cylinder head, each by means of a separate group of O-ring seals, so that an inner end region of the passageway in the cylinder head in which the fuel gas supply pipe is installed forms a conduit for conveying the fuel gas from the outlet end of the fuel gas supply pipe to the inlet orifice of the pre-combustion chamber.

The O-rings are relatively soft and so care must be taken to avoid damaging them during installation by abrasion against the material of the cylinder head as they are inserted together with the chamber body or fuel gas supply pipe into the respective passageway or cavity of the cylinder head.

Moreover, since the cylinder head may be made from a relatively more porous material than the gas inlet pipe and the chamber body, its porosity must be carefully controlled to avoid leakage of the fuel gas through the cylinder head into the ambient environment or coolant passages.

<CIT> discloses an internal combustion engine having a pre-combustion chamber body located in a cavity in the cylinder head in fluid communication with the combustion chamber. The pre-combustion chamber body is supplied with fuel gas via a fuel inlet connector that passes through a passageway in the cylinder head.

In a first aspect, the present disclosure provides an internal combustion engine including an engine body, a chamber body defining a pre-combustion chamber, a pipe, and a seal.

The engine body defines a combustion chamber, a cavity communicating with the combustion chamber, and a passageway communicating with the cavity.

The pipe is arranged to supply fuel gas to the pre-combustion chamber in use.

The chamber body is installed in the cavity of the engine body with the pre-combustion chamber in fluid communication with the combustion chamber of the engine, and the pipe is installed in the passageway of the engine body in fluid communication with the pre-combustion chamber of the chamber body.

The seal includes a wall, the wall surrounding an interior space and including first and second portions. The interior space opens through the wall at first, second and third openings.

The first portion extends between the first and second openings, while the second portion extends between the third opening and the first portion.

The first portion includes a first sealing region arranged between the first opening and the second portion, and a second sealing region arranged between the second opening and the second portion.

Each of the first and second sealing regions is configured to sealingly engage the chamber body, the chamber body being received in the interior space to extend through the first and second sealing regions.

The second portion includes a third sealing region arranged between the third opening and the first portion, the third sealing region being configured to sealingly engage the pipe. The pipe is received in the interior space to extend through the third sealing region in fluid communication with the pre-combustion chamber of the chamber body.

In embodiments, the wall may define oppositely directed, internal and external surfaces, the internal surface bounding the interior space, with the internal surface of the wall in each of the first, second and third sealing regions defining a respective one of first, second and third, inner annular ribs, each of the inner annular ribs encircling the interior space in the respective one of the first, second and third sealing regions. In such embodiments, the external surface of the wall in each of the first, second and third sealing regions may define a respective one of first, second and third, outer annular ribs, each of the outer annular ribs encircling the interior space in the respective one of the first, second and third sealing regions.

In embodiments, the first portion may extend along a first axis passing through the first and second openings, with the second portion extending along a second axis, the second axis being acollinear with the first axis and passing through the third opening.

In embodiments, the wall may include a unitary body of elastomeric material defining both of the first and second portions.

In embodiments, the wall in each of the first and second sealing regions may be arranged in compression between the engine body and the chamber body, with the wall in the third sealing region being arranged in compression between the engine body and the pipe.

In another aspect, the disclosure provides a method for assembling an internal combustion engine, the internal combustion engine including an engine body, the engine body defining a combustion chamber, a cavity communicating with the combustion chamber, and a passageway communicating with the cavity.

The method includes providing an apparatus including a chamber body defining a pre-combustion chamber, a pipe, and a seal.

The first portion extends between the first and second openings, and the second portion extends between the third opening and the first portion.

The second portion includes a third sealing region arranged between the third opening and the first portion.

The method further includes installing the apparatus in the engine body, wherein: the first portion of the wall is arranged in the cavity; the second portion of the wall is arranged in the passageway; the chamber body is received in the interior space of the seal to extend through the first and second sealing regions within the cavity of the engine body, with the pre-combustion chamber in fluid communication with the combustion chamber; the pipe is received in the interior space of the seal to extend through the third sealing region within the passageway of the engine body, in fluid communication with the pre-combustion chamber of the chamber body to supply fuel gas to the pre-combustion chamber; each of the first and second sealing regions is sealingly engaged with the chamber body; and the third sealing region is sealingly engaged with the pipe.

In embodiments, the seal may be installed in the engine body before introducing the chamber body and the pipe into the interior space of the seal.

The optional features of the above mentioned embodiments may be combined together as appropriate in any desired combination.

Further features and advantages will become evident from the following illustrative embodiment comprising a seal which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:.

Reference numerals and characters appearing in more than one of the figures indicate the same or corresponding features in each of them.

Referring to the figures, an apparatus includes a chamber body <NUM>, a pipe <NUM>, and a seal <NUM> as further explained below.

Referring to <FIG>, an internal combustion engine <NUM> includes an engine body <NUM> which defines a combustion chamber <NUM>, a cavity <NUM> communicating with the combustion chamber <NUM>, and a passageway <NUM> communicating with the cavity <NUM>.

The engine <NUM> may be a gas engine, which is to say, an engine fuelled by a fuel gas which exists in gaseous form at ambient temperature and pressure and is supplied in gaseous form to the engine. The engine body <NUM> may be a cylinder head of the engine, which may be made from a monolithic block of solid material such as cast iron, with the lower surface <NUM> of the cylinder head forming an upper wall of the combustion chamber, the remaining walls of the combustion chamber being formed by another part of the engine body (not shown), optionally with a liner, as known in the art. The combustion chamber may be one of several combustion chambers, each of which may contain a piston, the pistons driving a crankshaft, and may be supplied with a mixture of fuel gas and air via individual or combined inlet valves (not shown). The remaining details of the engine are conventional as well known in the art.

An upper end region <NUM> of the cavity <NUM> may open at an external surface (not shown) of the engine body <NUM>, for example, at an upper surface of the cylinder head, so that the chamber body <NUM> can be inserted via its upper end region <NUM> into the cavity. The cavity <NUM> may be generally cylindrical about its central longitudinal axis X1 which lies in the plane of the section of <FIG>, and may narrow towards its opposite or lower end region <NUM> which opens into the combustion chamber <NUM>.

The passageway <NUM> opens into the cavity <NUM> at an opening <NUM> and may be generally cylindrical about its central length axis X2 which lies in the plane of the section of <FIG>. The inner surface of the passageway may include a smooth, annular, and optionally cylindrical region which encircles its central length axis X2 proximate the opening <NUM> to engage the third sealing region of the seal <NUM> in compression in the use position as further explained below.

The inner surface of the cavity <NUM> may include smooth, annular, and optionally cylindrical regions which encircle the central longitudinal axis X1 of the cavity to engage respectively the first and second sealing regions of the seal <NUM> in compression in the use position as further explained below, with the opening <NUM> being arranged axially in-between these smooth, annular regions when considered along the direction of the central longitudinal axis X1 of the cavity <NUM>.

Both the cavity <NUM> and the passageway <NUM>, at least in the region comprising the opening <NUM>, may be formed in a unitary body of material forming the cylinder head or engine body, for example, by casting and/or machining a monolithic block of cast iron or other material.

Referring to <FIG>, the chamber body <NUM> may be made from a suitable metal and defines within the chamber body a pre-combustion chamber <NUM>. The metal or other material of the chamber body <NUM> may be less permeable by the fuel gas than the material of the engine body <NUM>.

In this specification, a pre-combustion chamber means a chamber that is supplied with fuel gas which is ignited to assist in igniting the charge or mixture in the combustion chamber.

An igniter assembly <NUM> may be arranged in the chamber body to extend into the pre-combustion chamber <NUM>. The igniter assembly <NUM> may comprise a spark igniter for causing a spark in the pre-combustion chamber responsive to an electrical ignition current. Alternatively or additionally, the igniter assembly <NUM> may comprise a fuel injector for injecting a liquid fuel into the pre-combustion chamber which is ignited by compression of the charge in the combustion chamber <NUM> or by the spark from the spark igniter. The igniter assembly <NUM> may controlled via electrical and/or fluid connections (not shown) connected to the engine ignition system and/or fuel supply system (not shown) via the upper end region <NUM> of the chamber body.

The pre-combustion chamber is arranged to receive fuel gas G via a fuel gas supply inlet <NUM> in the chamber body, and also fluidly communicates with an exterior of the chamber body via one or more outlet orifices <NUM> which may be arranged at a tip <NUM> of the chamber body.

A valve assembly (not shown), optionally with an actuation assembly controlled by the engine control system (not shown) may also be arranged in the chamber body <NUM> to control the flow of fuel gas via the fuel gas supply inlet <NUM> and retain pressure in the combustion chamber <NUM>.

The chamber body <NUM> may be generally cylindrical about its central length axis X3, which lies in the plane of the section of <FIG>, at least in that portion of its axial length in which the fuel gas supply inlet <NUM> is located. The fuel gas supply inlet <NUM> may open through the exterior surface of the chamber body <NUM> between two generally smooth, annular, and optionally cylindrical regions of the exterior surface of the chamber body which engage respectively the first and second sealing regions of the seal <NUM> in compression in the use position as further explained below.

Referring to <FIG>, the pipe <NUM> is provided to supply fuel gas to the pre-combustion chamber <NUM>. The pipe <NUM> may be generally cylindrical as shown about its central length axis X4, which lies in the plane of the section of <FIG>, and may be made for example from a suitable metal. The metal or other material of the pipe may be less permeable by the fuel gas than the material of the engine body <NUM>. The pipe may include a generally smooth, annular, and optionally cylindrical region encircling its central length axis X4 and forming part of its external surface <NUM> proximate its outlet end <NUM> at which its internal bore or lumen <NUM> opens, and positioned to engage the third sealing region of the seal <NUM> in compression in the use position as further explained below.

Referring to <FIG>, the seal <NUM> includes a wall <NUM> which surrounds an interior space <NUM> of the seal. The wall <NUM> includes a first portion <NUM> and a second portion <NUM>.

The interior space <NUM> opens through the wall <NUM> at a first opening <NUM>, a second opening <NUM>, and a third opening <NUM>.

The first portion <NUM> of the wall extends between the first and second openings <NUM>, <NUM>, while the second portion <NUM> extends between the third opening <NUM> and the first portion <NUM> of the wall.

The first portion <NUM> of the wall includes a first sealing region <NUM> arranged between the first opening <NUM> and the second portion <NUM> of the wall, and a second sealing region <NUM> arranged between the second opening <NUM> and the second portion <NUM> of the wall.

The second portion <NUM> of the wall includes a third sealing region <NUM> arranged between the third opening <NUM> and the first portion <NUM> of the wall.

It can be seen that the wall <NUM> defines oppositely directed, internal and external surfaces <NUM>, <NUM>. The internal surface <NUM> bounds the interior space <NUM>. The first and second portions <NUM>, <NUM> may be formed integrally with each other and may form a continuous barrier so that the internal surface <NUM> is unbroken between the three sealing regions <NUM>, <NUM>, <NUM> except by the fluid passageway forming the interior space <NUM> and opening through the wall at the three openings <NUM>, <NUM>, <NUM>.

The wall <NUM> may include or consist of a unitary body of elastomeric material defining both of the first and second portions <NUM>, <NUM>. The elastomeric material may be selected for resistance to the fuel gas and other service conditions.

The wall <NUM> may include a unitary body of elastomeric material defining both of the first and second portions <NUM>, <NUM> and a reinforcement or framework, made for example from metal or plastics material, which may be relatively more stiff or less elastic than the elastomeric material while still allowing elastic deformation of the wall during installation of the seal. The reinforcement or framework may support the elastomeric material and help to maintain the sealing regions in the correct, use position after the seal is located in the cavity and passageway and while the chamber body and pipe are introduced through the openings to energise the sealing regions by compression between the chamber body or pipe and the engine body.

The seal <NUM> may be made by moulding, and may consist essentially of the wall <NUM>.

The first portion <NUM> of the wall may extend along a first axis X5 passing (optionally, centrally) through each of the first and second openings <NUM>, <NUM>, with the second portion <NUM> extending along a second axis X6, the second axis X6 being acollinear (which is to say, not collinear) with the first axis X5 and passing (optionally, centrally) through the third opening <NUM>, for example, as shown.

The second axis X6 may be normal to the first axis X5 as shown, or may intersect the first axis X5 at an acute angle when considered in, or projected onto, a plane containing the first axis X5 (such as the plane of <FIG>).

The first portion <NUM> of the wall may form a first cylinder, and the second portion <NUM> may form a second, optionally smaller, cylinder extending radially outwardly from the first cylinder, for example, as shown.

The internal surface <NUM> of the wall <NUM> in each of the first, second and third sealing regions <NUM>, <NUM>, <NUM> may define a respective one of first, second and third, inner annular ribs <NUM>, <NUM>, <NUM>, each of the inner annular ribs encircling the interior space <NUM> in the respective one of the first, second and third sealing regions.

Alternatively or additionally, the external surface <NUM> of the wall <NUM> in each of the first, second and third sealing regions <NUM>, <NUM>, <NUM> may define a respective one of first, second and third, outer annular ribs <NUM>, <NUM>, <NUM>, each of the outer annular ribs encircling the interior space <NUM> in the respective one of the first, second and third sealing regions.

Alternatively, only one or two of the inner and/or outer annular ribs may be provided. For example, the inner and/or outer annular ribs may be provided in the first and second sealing regions, or in the third sealing region.

Where both inner and outer annular ribs are provided in one or more of the sealing regions, the inner and outer annular ribs may be arranged opposite each other (which is to say, oppositely directed and at the same axial position relative to the length axis of the respective portion of the wall), as shown. Each rib may be formed with a rounded, optionally semicircular profile as shown, or with a square or other angular profile as known in the art to ease installation and provide effective sealing. More than one internal and/or external rib may be arranged in the or each sealing region.

Referring now to <FIG>, in the use position of the apparatus the chamber body <NUM> is installed in the cavity <NUM> of the engine body <NUM> with the pre-combustion chamber <NUM> in fluid communication with the combustion chamber <NUM> of the engine, and the pipe <NUM> is installed in the passageway <NUM> of the engine body <NUM> in fluid communication with the pre-combustion chamber <NUM> of the chamber body <NUM>, with the seal <NUM> being arranged to enclose both components in the region where they meet to prevent the fuel gas from leaking from the fluid connection between the pipe <NUM> and the pre-combustion chamber <NUM>, as will now be explained.

The seal <NUM> is installed in the engine body <NUM> so that the first portion <NUM> of the wall <NUM> is arranged in the cavity <NUM>, and the second portion <NUM> of the wall <NUM> is arranged in the passageway <NUM>, as shown in <FIG> and <FIG>.

The seal <NUM> may be installed in the engine body <NUM> before introducing the chamber body <NUM> and the pipe <NUM> into the interior space of the seal as explained below. This helps to minimise sliding contact between the seal and the adjacent surfaces so as to ensure that the seal is not damaged during installation.

The seal <NUM> including the wall <NUM> may be elastically deformable so that it can be folded or rolled or squashed into a suitable shape to insert it into the cavity <NUM>, whereupon the first and second portions <NUM>, <NUM> of the wall elastically return to their original shape (defined for example during moulding of the wall <NUM>) within the interior space of the cavity <NUM> and the passageway <NUM>.

Where the sealing regions <NUM>, <NUM>, <NUM> are provided with outer annular ribs <NUM>, <NUM>, <NUM>, the outer annular ribs <NUM>, <NUM>, <NUM> may be compressed respectively against the corresponding smooth, annular regions of the cavity <NUM> and passageway <NUM> as shown in <FIG>.

The chamber body <NUM> is inserted slidingly into the cavity <NUM>, for example, along its central length axis X1 via its open, upper end region <NUM>, and passes slidingly through the first opening <NUM> so that the chamber body <NUM> is received in the interior space <NUM> of the seal <NUM> to extend through the first and second sealing regions <NUM>, <NUM> within the cavity <NUM> in its use position as shown in <FIG>.

In this position as shown, the tip <NUM> of the chamber body <NUM> extends into the combustion chamber <NUM> so that the pre-combustion chamber <NUM> is in fluid communication with the combustion chamber <NUM> via the outlet orifices <NUM>. The chamber body <NUM> may be sealed proximate its tip <NUM> by contact with the engine body <NUM> at the narrowed neck in the lower end region <NUM> of the cavity <NUM>, optionally with a further seal (not shown) being arranged in this region to retain pressure in the combustion chamber <NUM>.

The pipe <NUM> is inserted slidingly into the passageway <NUM> along its central length axis X2 and is received in the interior space <NUM> of the seal <NUM> to extend through the third sealing region <NUM> within the passageway <NUM>. In its use position the internal bore or lumen <NUM> of the pipe is in fluid communication via the fuel gas supply inlet <NUM> of the chamber body <NUM> with the pre-combustion chamber <NUM>.

The supply end (not shown) of the pipe <NUM> is connected to the fuel gas supply of the engine to supply fuel gas G to the pre-combustion chamber <NUM>.

References to the chamber body <NUM> or the pipe <NUM> being "received in" the interior space <NUM> of the seal should be construed to mean that at least a part of the chamber body or the pipe is received in the interior space <NUM> of the seal so that the or each respective sealing region encircles (i.e. extends entirely around) the respective part to provide a complete seal. As shown in the illustrated example, in the use position of the apparatus the chamber body <NUM> may extend through the interior space <NUM> of the seal and through its first and second openings <NUM>, <NUM>, while the pipe <NUM> extends through the third opening <NUM> into the interior space <NUM> of the seal to terminate at its outlet end <NUM> within the interior space <NUM> of the seal.

By assembling the seal <NUM> together with the chamber body <NUM> and the pipe <NUM> in the confined space of the cavity <NUM> and the passageway <NUM>, each of the first and second sealing regions <NUM>, <NUM> is sealingly engaged with the external surface of the chamber body <NUM> and the third sealing region <NUM> is sealingly engaged with the external surface of the pipe <NUM>, as shown.

Thus it can be seen that each of the first and second sealing regions <NUM>, <NUM> is configured to sealingly engage the chamber body <NUM> when the chamber body <NUM> is received in the interior space <NUM> of the seal to extend through the first and second sealing regions <NUM>, <NUM>, while the third sealing region <NUM> is configured to sealingly engage the pipe <NUM> when the pipe <NUM> is received in the interior space <NUM> of the seal to extend through the third sealing region <NUM> in fluid communication with the pre-combustion chamber <NUM> in the use position of the apparatus as shown in <FIG>.

The wall <NUM> in each of the first and second sealing regions <NUM>, <NUM> may be arranged in compression between the engine body <NUM> and the chamber body <NUM>, while the wall <NUM> in the third sealing region <NUM> is arranged in compression between the engine body <NUM> and the pipe <NUM>.

Where the sealing regions <NUM>, <NUM>, <NUM> are provided with inner annular ribs <NUM>, <NUM>, <NUM>, the inner annular ribs <NUM>, <NUM>, <NUM> may be compressed respectively against the respective smooth, annular regions of the chamber body <NUM> and the smooth, annular region of the pipe <NUM> as previously described and best seen in <FIG>.

Where as illustrated the inner annular ribs are arranged opposite the respective, outer annular ribs, the corresponding smooth, annular regions of the chamber body <NUM> and pipe <NUM> are arranged opposite (i.e. at the same position along the respective axis of the cavity or pipe) to the corresponding smooth, annular regions of the cavity <NUM> and passageway <NUM> in the use position.

The outer surfaces of the chamber body <NUM> and the pipe <NUM> including said smooth, annular regions may be contoured to slidingly engage and compress and so, progressively energise the sealing regions of the seal, including where provided the annular ribs, as they advance to the installed, use position.

In <FIG> it can be seen that the sealing regions <NUM>, <NUM> encircle the chamber body <NUM> axially on either side of the fuel gas supply inlet <NUM> of the chamber body <NUM>, so that by energising the sealing regions <NUM>, <NUM> an annular portion of the external surface of the chamber body <NUM> including the fuel gas supply inlet <NUM> is fluidly isolated within the interior space <NUM> of the seal <NUM> in fluid communication only with the internal bore or lumen <NUM> of the pipe. This provides a gas tight seal and ensures that the fuel gas does not come into contact with the engine body <NUM> in the region of the fluid connection between the pipe <NUM> and the chamber body <NUM>.

The seal <NUM> may be installed by elastically deforming it before introducing it into the cavity and passageway of the engine body <NUM>, and may be removed in the same way. Since all three sealing regions are united by the wall <NUM> of the seal they are supported by the wall <NUM> in the correct installed position while the chamber body and pipe are introduced through the openings <NUM>, <NUM>, <NUM> of the seal inside the engine body <NUM>, providing a simpler assembly and maintenance procedure where fuel gas is supplied to the pre-combustion chamber of an engine.

The seal <NUM> forms an impermeable shroud surrounding the interface between the fuel gas supply pipe <NUM> and the chamber body <NUM> and sealed to respective outer surface portions of both components to enclose the interface. This prevents fuel gas from escaping from the interface via the cylinder head, irrespective of its relative porosity.

The seal <NUM> accommodates small variations in the position of the chamber body <NUM> relative to the fuel gas supply pipe <NUM> and so provides easier and more satisfactory installation and sealing of both parts, which is not compromised by small relative movements between them.

In summary, fuel gas G is supplied via a pipe <NUM> to a pre-combustion chamber <NUM> of an internal combustion engine <NUM>. The pre-combustion chamber <NUM> is formed inside a chamber body <NUM> which is received in a cavity <NUM> of the engine body <NUM>, while the pipe <NUM> is received in a passageway <NUM> of the engine body <NUM> which communicates with the cavity <NUM>. A seal <NUM> which may be made from an elastomer comprises a wall <NUM> defining an interior space <NUM> opening through the wall <NUM> at first, second and third openings <NUM>, <NUM>, <NUM>. A first portion <NUM> of the wall <NUM> defining the first and second openings <NUM>, <NUM> is arranged in the cavity <NUM> so that the chamber body <NUM> can be inserted through the openings <NUM>, <NUM> into the interior space <NUM> of the seal, while a second portion <NUM> of the wall <NUM> comprising the third opening <NUM> is received in the passageway <NUM> so that the pipe <NUM> can be inserted into the interior space <NUM> of the seal via the third opening <NUM>. The pipe <NUM> is sealed in fluid communication with the pre-combustion chamber <NUM> via an inlet <NUM> in the chamber body <NUM> by sealing regions <NUM>, <NUM>, <NUM> of the seal which may be arranged proximate the respective openings <NUM>, <NUM>, <NUM>.

Many further adaptations are possible within the scope of the claims.

Claim 1:
An internal combustion engine (<NUM>) including:
an engine body (<NUM>),
a chamber body (<NUM>) defining a pre-combustion chamber (<NUM>),
a pipe (<NUM>), and
a seal (<NUM>);
the engine body (<NUM>) defining:
a combustion chamber (<NUM>),
a cavity (<NUM>) communicating with the combustion chamber (<NUM>), and
a passageway (<NUM>) communicating with the cavity (<NUM>);
the pipe (<NUM>) being arranged to supply fuel gas (G) to the pre-combustion chamber (<NUM>) in use;
the chamber body (<NUM>) being installed in the cavity (<NUM>) of the engine body (<NUM>) with the pre-combustion chamber (<NUM>) in fluid communication with the combustion chamber (<NUM>) of the engine (<NUM>);
the pipe (<NUM>) being installed in the passageway (<NUM>) of the engine body (<NUM>) in fluid communication with the pre-combustion chamber (<NUM>) of the chamber body (<NUM>);
characterised in that
the seal (<NUM>) includes a wall (<NUM>), the wall (<NUM>) surrounding an interior space (<NUM>) and including first and second portions (<NUM>, <NUM>);
the interior space opening (<NUM>) through the wall (<NUM>) at first, second and third openings (<NUM>, <NUM>, <NUM>);
the first portion (<NUM>) extending between the first and second openings (<NUM>, <NUM>), the second portion (<NUM>) extending between the third opening (<NUM>) and the first portion (<NUM>);
the first portion (<NUM>) including:
a first sealing region (<NUM>) arranged between the first opening (<NUM>) and the second portion (<NUM>), and
a second sealing region (<NUM>) arranged between the second opening (<NUM>) and the second portion (<NUM>);
each of the first and second sealing regions (<NUM>, <NUM>) being configured to sealingly engage the chamber body (<NUM>), the chamber body (<NUM>) being received in the interior space (<NUM>) to extend through the first and second sealing regions (<NUM>, <NUM>);
the second portion (<NUM>) including a third sealing region (<NUM>) arranged between the third opening (<NUM>) and the first portion (<NUM>),
the third sealing region (<NUM>) being configured to sealingly engage the pipe (<NUM>), the pipe (<NUM>) being received in the interior space (<NUM>) to extend through the third sealing region (<NUM>) in fluid communication with the pre-combustion chamber (<NUM>) of the chamber body (<NUM>).