GB2554719A

GB2554719A - System for evacuating residual gases from pre-chamber of engine

Info

Publication number: GB2554719A
Application number: GB1616980.7A
Authority: GB
Inventors: Maier Thomas
Original assignee: Caterpillar Energy Solutions GmbH
Current assignee: Caterpillar Energy Solutions GmbH
Priority date: 2016-10-06
Filing date: 2016-10-06
Publication date: 2018-04-11
Also published as: GB201616980D0

Abstract

An internal combustion engine includes a pre-chamber 48 formed in the pre-chamber body 47 of a pre-chamber assembly 18 coupled with the cylinder head 16. An auxiliary passage 60 extends between the pre-chamber 48 and the inlet passage 30 to discharge residual gases from the pre-chamber 48. The outlet end 62 of the auxiliary passage 60 is disposed on the valve seating surface 45 of the inlet valve seat ring 38 so that the inlet valve 34 can open and close communication between the pre-chamber 48 and the main combustion chamber 28 via the auxiliary passage 60. Opening the inlet valve 34 during the suction stroke A causes a flow of residual gases B from the pre-chamber 48 to the main combustion chamber 28. The inlet end of the auxiliary passage 60 may comprise a number of circumferential channels 63 in the pre-chamber body 47 leading to a cavity 64 between the pre-chamber body 47 and the cylinder head 16; the outlet end may comprise a circumferential slot 68 and a number of channels 70 in the valve seat ring 38.

Description

(54) Title of the Invention: System for evacuating residual gases from pre-chamber of engine Abstract Title: System for evacuating residual gases from pre-chamber of an i.e. engine (57) An internal combustion engine includes a pre-chamber 48 formed in the pre-chamber body 47 of a pre-chamber assembly 18 coupled with the cylinder head 16. An auxiliary passage 60 extends between the pre-chamber 48 and the inlet passage 30 to discharge residual gases from the pre-chamber 48. The outlet end 62 of the auxiliary passage 60 is disposed on the valve seating surface 45 of the inlet valve seat ring 38 so that the inlet valve 34 can open and close communication between the pre-chamber 48 and the main combustion chamber 28 via the auxiliary passage 60. Opening the inlet valve 34 during the suction stroke A causes a flow of residual gases B from the prechamber 48 to the main combustion chamber 28. The inlet end of the auxiliary passage 60 may comprise a number of circumferential channels 63 in the pre-chamber body 47 leading to a cavity 64 between the pre-chamber body 47 and the cylinder head 16; the outlet end may comprise a circumferential slot 68 and a number of channels 70 in the valve seat ring 38.

FIG. 4

1/4

Ζ'

FIG. 1

2/4

FIG. 2

3/4

FIG. 3

4/4

FIG. 4

-1SYSTEM FOR EVACUATING RESIDUAL GASES FROM PRE-CHAMBER

OF ENGINE

Technical Field

The present disclosure relates to internal combustion engines, and more particularly to a system for evacuating residual gases from a pre-chamber of an engine.

Background

Lean combustion engines are known to include a pre-chamber assembly within a cylinder head of the engine. The pre-chamber assembly includes a number of orifices and an ignition unit, such as a spark plug. The pre-chamber assembly is in communication with a main combustion chamber of the engine, via the orifices. The ignition unit initiates ignition of air-fuel mixture in the pre-chamber assembly. Ignition of the air-fuel mixture creates a flame front of burning fuel in the pre-chamber assembly which is introduced into the main combustion chamber through the orifices. However, this also results in formation of residual gases in the pre-chamber assembly.

Typically, the residual gases remain in the pre-chamber assembly even after completion of an exhaust stroke of the engine. The residual gases may mix with fresh air-fuel mixture drawn during subsequent strokes of the engine. This results in formation of leaner air-fuel mixture in the pre-chamber assembly, when compared to the air-fuel mixture in the main combustion chamber. This leads to inadequate ignition of the air-fuel mixture in the pre-chamber assembly and the main combustion chamber. The inadequate ignition of the air-fuel mixture adversely affects various operational characteristics of the engine, such as efficiency and power output.

JP Patent Publication Number 2006-177250, hereinafter referred to as ’250 publication, discloses an indirect injection internal combustion engine capable of

-2stabilizing combustion in a subsidiary combustion chamber. The indirect injection internal combustion engine is provided with a main combustion chamber, the subsidiary combustion chamber, and a first bypass passage. The subsidiary combustion chamber adjoins and communicates to the main combustion chamber. The first bypass passage maintains communication between the subsidiary combustion chamber and an intake port corresponding to the main combustion chamber. The ’250 publication discloses a first bypass valve provided in the first bypass passage to discharge residual gas from the subsidiary combustion chamber to the first bypass passage.

Summary of the Disclosure

In one aspect of the present disclosure, an internal combustion is provided. The internal combustion engine includes a cylinder block. The cylinder block includes a piston assembly. The internal combustion engine also includes a cylinder head coupled with the cylinder block to define a main combustion chamber. The cylinder head defines an inlet passage in fluid communication with the main combustion chamber. The internal combustion engine includes a prechamber assembly coupled with the cylinder head. The pre-chamber assembly includes a pre-chamber in fluid communication with the main combustion chamber via a number of orifices. The pre-chamber assembly and the cylinder head define an auxiliary passage. The auxiliary passage includes an inlet end and an outlet end. The inlet end is in fluid communication with the pre-chamber. The outlet end is disposed on a first surface of a first valve seat ring. The internal combustion engine also includes an inlet valve adapted to biasedly overlay against the first surface of the first valve seat ring. The inlet valve is operable between an open position and a closed position. The inlet valve in the open position establishes fluid communication between the pre-chamber and the main combustion chamber via the auxiliary passage. The inlet valve in the closed position restricts fluid communication through the outlet end of the auxiliary passage.

-3Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

FIG. 1 is a perspective view of an internal combustion engine, according to a concept of the present disclosure;

FIG. 2 is a partial sectional view of the internal combustion engine having a prechamber assembly;

FIG. 3 is an enlarged sectional view of a portion of the internal combustion engine showing the pre-chamber assembly and an inlet valve in a closed position; and

FIG. 4 is an enlarged sectional view of a portion of the internal combustion engine showing the pre-chamber assembly and the inlet valve in an open position.

Detailed Description

Referring to FIG. 1, a perspective view of an internal combustion engine 10 is shown. The internal combustion engine 10, interchangeably referred to as engine 10, is a four-stroke gaseous fuel internal combustion engine. The engine 10 may be used as a source of power for any machine, such as on-highway trucks, offhighway trucks, earth moving equipment, and various devices, such as pumps, stationary equipment, and generators. The engine 10 may also be used to power machines or devices used in construction, transportation, power generation, aerospace applications, locomotive applications, marine applications, and any other applications that require a rotary power. Although the engine 10, as shown in FIG. 1, is a multi-cylinder engine, it may be contemplated that the present disclosure may be implemented in a single cylinder engine.

The engine 10 includes an engine housing 12. The engine housing 12 includes a cylinder block 14 and a cylinder head 16 disposed on the cylinder block 14. Referring to FIGS. 1 and 2, the cylinder block 14 defines a number of cylinder bores 20 (one of which is shown in FIG. 2). In the illustrated example, the engine 10 is a V-type multi cylinder engine with the cylinder bores 20 defined in a V-4type configuration. Although, the cylinder bores 20 are defined in the V-type configuration in the cylinder block 14, it should be understood that the cylinder bores 20 can be defined in any type of configuration, such as an inline configuration and a radial configuration, without departing from the scope of the present disclosure. For illustration purpose, the present disclosure will be described in connection with one of the cylinder bores 20 of the cylinder block 14, although it will be understood that the present disclosure is equally applicable to other cylinder bores of the cylinder block 14.

Referring to FIG. 2, the cylinder block 14 includes a piston assembly 22 slidably disposed within the cylinder bore 20 of the cylinder block 14 and connected to a crankshaft (not shown). The piston assembly 22 reciprocates within the cylinder bore 20. A connecting rod 26 connects the piston assembly 22 to the crankshaft such that a sliding movement of the piston assembly 22 within the cylinder bore 20 results in a rotational movement of the crankshaft.

The cylinder head 16 is coupled with the cylinder block 14 of the engine 10. A main combustion chamber 28 is defined between the cylinder head 16 and the cylinder bore 20 of the cylinder block 14. More specifically, the cylinder block 14, the piston assembly 22, and the cylinder head 16 define the main combustion chamber 28. In an example, a volume of the main combustion chamber 28 may vary with a location of the piston assembly 22 within the cylinder bore 20 relative to the cylinder head 16. The piston assembly 22 reciprocates between a Bottom Dead Center (BDC) to a Top Dead Center (TDC) in multiple cycles. The volume between the TDC and the BDC defines a swept volume. The term “swept volume” herein defines a volume available for air-fuel mixture to occupy.

The cylinder head 16 defines an inlet passage 30 and an exhaust passage 32. More specifically, the inlet passage 30 and the exhaust passage 32 are formed in the cylinder head 16. The inlet passage 30 is in fluid communication with the

-5main combustion chamber 28 to supply the air-fuel mixture into the main combustion chamber 28 during a suction stroke of the engine 10. Further, the exhaust passage 32 is also in fluid communication with the main combustion chamber 28 to discharge residual gases formed after combustion of the air-fuel mixture in the main combustion chamber 28.

Further, an inlet valve 34 and an exhaust valve 36 are disposed in the cylinder head 16. More specifically, the inlet valve 34 and the exhaust valve 36 are overlaid upon the inlet passage 30 and the exhaust passage 32, respectively. The inlet valve 34 is operable between an open position and a closed position. The inlet valve 34 in the open position allows a flow of the air-fuel mixture through the inlet passage 30 into the main combustion chamber 28. The inlet valve 34 in the closed position restricts the flow of the air-fuel mixture through the inlet passage 30 into the main combustion chamber 28. The exhaust valve 36 is also operable between an open position and a closed position. In an example, the inlet valve 34 and the exhaust valve 36 may be actuated by a valve train assembly (not shown), a solenoid actuator, a hydraulic actuator, a combination thereof, or by any other cylinder valve actuator to open and close the inlet valve 34 and the exhaust valve 36. In an example, opening and closing of each of the inlet valve 34 and the exhaust valve 36 may be operated in relation with the position of the piston assembly 22 within the cylinder bore 20, and operating cycle of the engine 10.

In an example, when the piston assembly 22 moves towards the BDC during the suction stroke, the inlet valve 34 may be operated to the open position in order to receive the air-fuel mixture into the main combustion chamber 28 driven by suction pressure generated due to a movement of the piston assembly 22. Alternatively, the air-fuel mixture may be driven into the main combustion chamber 28 due to pressure generated by a turbocharger (not shown). Further, when the piston assembly 22 reaches to the BDC after completion of the suction

-6stroke, the inlet valve 34 may be operated to the closed position for initiating a compression stroke of the engine 10.

The inlet passage 30 cooperates with the inlet valve 34 to allow the air-fuel mixture to be introduced into the main combustion chamber 28. The exhaust passage 32 cooperates with the exhaust valve 36 to discharge products, such as the residual gases. More specifically, once the air-fuel mixture is combusted in the main combustion chamber 28, the products of the combustion are forced out of the main combustion chamber 28 by a reciprocating movement of the piston assembly 22 through the exhaust passage 32 with the aid of the exhaust valve 36.

Referring to FIGS 2 and 3, the cylinder head 16 also includes a first valve seat ring 38, interchangeably referred to as first insert 38, and a second valve seat ring 40, interchangeably referred to as second insert 40. The first valve seat ring 38 is disposed in proximity of the inlet valve 34. The first valve seat ring 38 is disposed in a first groove 42 (shown in FIG. 3) formed adjacent to the inlet valve 34 in the cylinder head 16. The first valve seat ring 38 includes a first surface 45 (shown in FIG. 4). The inlet valve 34 is biasedly overlaid against the first surface 45 of the first valve seat ring 38. In the closed position, the inlet valve 34 abuts the first valve seat ring 38 to provide sealing between the main combustion chamber 28 and the inlet passage 30. More specifically, in the closed position, the inlet valve 34 abuts the first surface 45 of the first valve seat ring 38. The second valve seat ring 40 is disposed in proximity of the exhaust valve 36. The second valve seat ring 40 is disposed in a second recess (not shown) formed adjacent to the exhaust valve 36 in the cylinder head 16.

The engine 10 also includes a pre-chamber assembly 18 coupled to the cylinder head 16 of the engine 10. The engine 10 and the pre-chamber assembly 18 define a system for evacuating residual gases from the pre-chamber assembly 18 of the engine 10. The pre-chamber assembly 18 facilitates combustion of the air-fuel

-7mixture present in the main combustion chamber 28. During the compression stroke, the air-fuel mixture enters the pre-chamber assembly 18 from the main combustion chamber 28. The air-fuel mixture received in the pre-chamber assembly 18 is ignited, which further initiates ignition of the air-fuel mixture in the main combustion chamber 28. A sealing member 46 is provided between the pre-chamber assembly 18 and the cylinder head 16. The pre-chamber assembly 18 includes a pre-chamber body 47 and a pre-chamber 48. The pre-chamber body 47 is received within a recess 44 defined in the cylinder head 16. The prechamber 48 is defined within the pre-chamber body 47. The pre-chamber body 47 includes an upper portion 50 and a lower portion 52. The upper portion 50 is coupled to the lower portion 52 of the pre-chamber body 47. In an example, the upper portion 50 may be welded to the lower portion 52 of the pre-chamber body

47. Further, the upper portion 50 is also coupled to the cylinder head 16. In an example, the upper portion 50 may be coupled to the cylinder head 16 via fastening threads 54.

The upper portion 50 is provided with an ignition unit 56, such as spark plugs for gasoline engines or glow plugs for diesel engines. The ignition unit 56 is associated with the pre-chamber 48 in order to ignite the air-fuel mixture in the pre-chamber 48, and to subsequently initiate combustion of the air-fuel mixture in the main combustion chamber 28. In an example, the ignition unit 56 may include, but is not limited to, a laser ignition device, a spark plug, and a glow plug based on a type of fuel used for combustion. The lower portion 52 includes a number of orifices 58. The pre-chamber 48 is in fluid communication with the cylinder bore 20 through the orifices 58 formed on the lower portion 52. The airfuel mixture is directed into the pre-chamber 48 from the main combustion chamber 28 through the orifices 58. Also, the orifices 58 are provided to direct burning fuel, for example, expanding gases from the pre-chamber 48 into the main combustion chamber 28.

-8As shown in FIG. 3, the pre-chamber assembly 18 and the cylinder head 16 define an auxiliary passage 60 extending from the pre-chamber 48 to the inlet passage 30. More specifically, the pre-chamber assembly 18, the cylinder head 16, and the first valve seat ring 38 define the auxiliary passage 60 therethrough. The auxiliary passage 60 is in fluid communication with the pre-chamber 48 and the inlet passage 30 to communicate the residual gases from the pre-chamber 48 to the inlet passage 30. The auxiliary passage 60 discharges the residual gases from the pre-chamber 48 to the inlet passage 30 based on a position, such as the open position and the closed position, of the inlet valve 34. The inlet valve 34 in the open position facilitates a flow of the residual gases through the auxiliary passage 60 into the main combustion chamber 28 during the suction stroke of the engine 10. The inlet valve 34 in the closed position restricts the flow of the residual gases through the auxiliary passage 60. More specifically, the inlet valve 34 in the closed position restricts the flow of the residual gases through the outlet end 62 of the auxiliary passage 60. The auxiliary passage 60 includes an inlet end 61 and an outlet end 62 (shown in FIG. 4). The inlet end 61 is disposed in the pre-chamber assembly 18. The outlet end 62 is disposed on the first surface 45 of the first valve seat ring 38. The inlet end 61 is in fluid communication with the pre-chamber 48. The outlet end 62 is in fluid communication with the inlet passage 30.

The auxiliary passage 60 is defined by a number of first channels 63 (only one is shown in FIG. 3), a cavity 64, a second channel 66, a circumferential slot 68, and a number of third channels 70 (only one is shown in FIG. 3). The first channels 63 are provided in the pre-chamber assembly 18. An end of the each of the first channels 63 defines the inlet end 61 of the auxiliary passage 60. More specifically the first channels 63 are formed circumferentially in the upper portion 50 of the pre-chamber body 47. For illustration purposes, the present disclosure will be described in connection with only one of the first channels 63, although it will be understood that the present disclosure is equally applicable to other first channels 63 of the auxiliary passage 60. In an example, the first channel 63 may have a circular cross-section. The first channel 63 is in fluid

-9communication with the pre-chamber 48 of the pre-chamber assembly 18 through the inlet end 61. In an example, the first channel 63 may be embodied as a through-hole drilled in the upper portion 50 of the pre-chamber body 47.

Further, the cavity 64 is defined between the pre-chamber assembly 18 and the cylinder head 16. More specifically, the cavity 64 is defined between the upper portion 50 of the pre-chamber body 47 and the recess 44 of the cylinder head 16. The cavity 64 is in fluid communication with the pre-chamber 48 through the first channel 63 to receive the residual gases from the pre-chamber 48. As discussed earlier, the sealing member 46 is provided between the pre-chamber body 47 and the cylinder head 16. The sealing member 46 restricts leakage of the residual gases received from the pre-chamber 48 in the cavity 64 through the first channel 63. Further, the sealing member 46 is provided for sealing a combustion side against coolant flow in the cylinder head 16. In an example, the sealing member 46 may be embodied as any type of suitable sealing, such as a sealing ring, an Ciring, or a conical seat.

The second channel 66 of the auxiliary passage 60 is formed in the cylinder head 16 of the engine 10. In one example, the second channel 66 may be drilled through the cylinder head 16. In another example the second channel 66 may be formed during casting of the cylinder head 16. The second channel 66 extends from the recess 44 to the first groove 42 which receives the first valve seat ring 38. In an example, the second channel 66 may have a circular cross-section. The second channel 66 is in fluid communication with the cavity 64 and the first channel 63 for receiving the residual gases. More specifically, the second channel 66 is in fluid communication with the pre-chamber 48 through the first channel 63 and the cavity 64.

The circumferential slot 68 is formed on the first valve seat ring 38 disposed in the first groove 42. The circumferential slot 68 is in fluid communication with

-10the second channel 66 for receiving the residual gases. More specifically, the circumferential slot 68 is in fluid communication with the pre-chamber 48 through the second channel 66, the cavity 64, and the first channel 63. The circumferential slot 68 is defined by a top surface 72 and a bottom surface 74 distal to the top surface 72.

The third channels 70 are circumferentially formed in the first valve seat ring 38. For illustration purposes, the present disclosure will be described in connection with only one of the third channels 70, although it will be understood that the present disclosure is equally applicable to other third channels 70 of the auxiliary passage 60. The third channel 70 extends from the bottom surface 74 of the circumferential slot 68 to the inlet passage 30. An end of the third channel 70 defines the outlet end 62 of the auxiliary passage 60. In an example, the third channel 70 may have a circular cross-section. The third channel 70 is in fluid communication with the circumferential slot 68 and the inlet passage 30 for receiving the residual gases. More specifically, the third channel 70 is in fluid communication with the pre-chamber 48 through the circumferential slot 68, the second channel 66, the cavity 64, and the first channel 63.

Further, the third channel 70 is in fluid communication with the inlet passage 30 through the outlet end 62 (shown in FIG. 4) of the auxiliary passage 60. In the closed position, the inlet valve 34 restricts fluid communication through the outlet end 62 of the auxiliary passage 60. More specifically, in the closed position, the inlet valve 34 covers the outlet end 62, thereby restricting fluid communication between the pre-chamber 48 and the inlet passage 30 through the outlet end 62 of the auxiliary passage 60. Due to restriction of fluid communication between the pre-chamber 48 and the inlet passage 30, the flow of the residual gases from the pre-chamber 48 to the inlet passage 30 is restricted. In the open position, the inlet valve 34 moves away from the outlet end 62 to form a gap that establishes fluid communication between the pre-chamber 48 and the inlet passage 30, via the auxiliary passage 60. As fluid communication is

-11established between the pre-chamber 48 and the inlet passage 30, the flow of the residual gases from the pre-chamber 48 to the inlet passage 30 is allowed.

Referring to FIGS. 3 and 4, during an operation of the engine 10, at least some amount of the air-fuel mixture is provided in the main combustion chamber 28 through the inlet valve 34, during the suction stroke (as indicated by ‘A’ in FIG. 4). A portion of the air-fuel mixture in the main combustion chamber 28 is forced into the pre-chamber 48 by the piston assembly 22 through the orifices 58 of the pre-chamber 48, during the compression stroke. Subsequently, the ignition unit 56 ignites the air-fuel mixture in the pre-chamber 48 that further initiates combustion of the air-fuel mixture present in the main combustion chamber 28. More specifically, the ignited air-fuel mixture in the pre-chamber 48 then ignites the remaining air-fuel mixture in the main combustion chamber 28 via flames projected through the orifices 58 of the pre-chamber 48. The combustion of the air-fuel mixture results in a movement of the piston assembly 22 from the TDC to the BDC to generate power.

During combustion of the air-fuel mixture, the residual gases are formed in the pre-chamber 48 and the main combustion chamber 28. Subsequently, the residual gases are discharged through the exhaust valve 36 from the cylinder bore 20 during an exhaust stroke. After completion of the exhaust stroke, some amount of the residual gases left in the pre-chamber 48 is expelled through the auxiliary passage 60 from the pre-chamber 48 during subsequent suction stroke.

As shown in FIG. 4, during the subsequent suction stroke, the inlet valve 34 is operated to the open position for allowing the air-fuel mixture from the inlet passage 30 in the main combustion chamber 28. Also, the inlet valve 34 in the open position causes the flow of the residual gases (as indicated by ‘B’ in FIG. 4) from the pre-chamber 48 to the main combustion chamber 28 through the outlet end 62 of the auxiliary passage 60. When the inlet valve 34 is operated from the

-12closed position to the open position, the air-fuel mixture is drawn into the main combustion chamber 28 at a high flow velocity that generates a pressure difference between the pre-chamber 48 and the inlet passage 30. In one example, the pressure difference may vary based on crank angle. In another example, the pressure difference may vary based on engine parameters, such as engine load. Due to the pressure difference, the residual gases in the pre-chamber 48 are drawn through the first channel 63 of the auxiliary passage 60 to the cavity 64 between the pre-chamber assembly 18 and the cylinder head 16. Afterwards, the residual gases flow from the cavity 64 to the second passage, and further to the circumferential slot 68. Subsequently, the residual gases are discharged to the inlet passage 30 from the circumferential slot 68 through the third channel 70. The residual gases discharged to the inlet passage 30 mix with the air-fuel mixture in the main combustion chamber 28 through the inlet passage 30. Industrial Applicability

The present disclosure relates to the system for evacuating residual gases from the pre-chamber assembly 18 of the engine 10. The engine 10 includes the cylinder head 16 and the cylinder block 14. The cylinder head 16 includes the inlet valve 34 disposed on the inlet passage 30. The inlet passage 30 is in fluid communication with the main combustion chamber 28. Further, the engine 10 includes the auxiliary passage 60 in fluid communication with the inlet passage 30. The auxiliary passage 60 is drilled through the body of the pre-chamber 48, the cylinder head 16, and the first valve seat ring 38. The residual gases discharged from the pre-chamber 48 during the suction stroke mix with the airfuel mixture flowing into the main combustion chamber 28 through the inlet valve 34 via the inlet passage 30.

This sustains ignitability of the air-fuel mixture that flows into the pre-chamber 48 through the orifices 58 of the pre-chamber 48 during the compression stroke. More specifically, removal of the residual gases from the pre-chamber 48 through the auxiliary passage 60 eliminates formation of leaner air-fuel mixture due to mixing of the air-fuel mixture with the residual gases in the pre-chamber 48.

-13Further, removal of the residual gases from the pre-chamber 48 also increases overall efficiency of the engine 10.

Further, the auxiliary passage 60 of the engine 10 cooperates with the inlet valve 5 34 to allow or restrict the flow of the residual gases from the pre-chamber 48 to the inlet passage 30. The engine 10 with the auxiliary passage 60 can be used in any type of engine, such as internal combustion engine run by gasoline, diesel, gaseous fuel, or a combination thereof. The auxiliary passage 60 can be provided in the engine 10 for any type of machine used in construction, transportation, power generation, aerospace applications, locomotive applications, marine applications, and other engine power applications.

--14-Global Claim Set

Claims

What is claimed is:

1. An internal combustion engine (10) comprising:

a cylinder block (14) having a piston assembly (22); a cylinder head (16) coupled with the cylinder block (14) to define a main combustion chamber (28), the cylinder head (16) defining an inlet passage (30) in fluid communication with the main combustion chamber (28);

a pre-chamber assembly (18) coupled with the cylinder head (16), the pre-chamber (18) assembly having a pre-chamber (48) in fluid communication with the main combustion chamber (28) via a number of orifices (58), the pre-chamber assembly (18) and the cylinder head (16) defining an auxiliary passage (60) having an inlet end (61) and an outlet end (62), the inlet end (61) in fluid communication with the pre-chamber (48) and the outlet end (62) disposed on a first surface (45) of a first valve seat ring (38); and an inlet valve (34) adapted to biasedly overlay against the first surface (45) of the first valve seat ring (38) and operable between an open position and a closed position, wherein the inlet valve (34) in the open position establishes fluid communication between the pre-chamber (48) and the main combustion chamber (28) via the auxiliary passage (60) and wherein the inlet valve (34) in the closed position restricts fluid communication through the outlet end (62) of the auxiliary passage (60).

2. The internal combustion engine (10) of claim 1, wherein the inlet valve (34) is operated to the open position during a suction stroke to cause a flow of residual gases from the pre-chamber assembly (18) to the main combustion chamber (28) through the outlet end (62) of the auxiliary passage (60).

Intellectual

Property

Office

Application No: GB1616980.7 Examiner: John Twin