GB2552669A

GB2552669A - Engine pre-chamber

Info

Publication number: GB2552669A
Application number: GB1613293.8A
Authority: GB
Inventors: A Schultze Marco
Original assignee: Caterpillar Energy Solutions GmbH
Current assignee: Caterpillar Energy Solutions GmbH
Priority date: 2016-08-02
Filing date: 2016-08-02
Publication date: 2018-02-07
Anticipated expiration: 2036-08-02
Also published as: GB2552669B; GB201613293D0

Abstract

A pre-chamber 128 for use in an engine and/or a spark plug 130. The pre-chamber includes a capillary tube 142, positioned at one side of the pre-chamber, and a ring element 144 positioned within. The ring element includes an annular main body 145 with a defined annular groove 146 in fluid communication with the capillary tube (supplying methane). The ring element also includes a plurality of holes 152 formed in the main body which provide fluid communication between the annular groove and an internal volume 134 of the pre-chamber. The plurality of holes preferably control flame backlash. The annular ring is preferably a porous ceramic ring, may be temperature resistant and may be adapted to induce a gaseous fuel into the internal volume. The ring element may be milled and the groove is preferably lesser than the thickness of the main body, disposed centrally. An ignition assembly and engine are also claimed.

Description

(54) Title of the Invention: Engine pre-chamber Abstract Title: Engine pre-chamber (57) A pre-chamber 128 for use in an engine and/or a spark plug 130. The pre-chamber includes a capillary tube 142, positioned at one side of the pre-chamber, and a ring element 144 positioned within. The ring element includes an annular main body 145 with a defined annular groove 146 in fluid communication with the capillary tube (supplying methane). The ring element also includes a plurality of holes 152 formed in the main body which provide fluid communication between the annular groove and an internal volume 134 of the pre-chamber. The plurality of holes preferably control flame backlash. The annular ring is preferably a porous ceramic ring, may be temperature resistant and may be adapted to induce a gaseous fuel into the internal volume. The ring element may be milled and the groove is preferably lesser than the thickness of the main body, disposed centrally. An ignition assembly and engine are also claimed.

130

FIG. 2

1/3

C5 <=5

120 116

FIG. 1

2/3

FIG. 2

3/3

Xr ία

Qo

FIG. 3

ENGINE PRE-CHAMBER

Technical Field [0001] The present disclosure relates to an engine, and more particularly to a pre-chamber for use in at least one of an engine and a spark plug.

Background [0002] Engines including pre-chambers are generally flushed with a gaseous fuel. The gaseous fuel used for flushing the pre-chamber is introduced in an internal volume of the pre-chamber by a capillary tube positioned at the side of the pre-chamber. As the capillary tube is thin in structure, sometimes, during operation the capillary tube may get clogged. This may happen, for example, due to accumulation of deposits at an exit of the capillary tube where the capillary tube connects with the pre-chamber.

[0003] Further, in some occasions, due to a sideward supply of the gaseous fuel by the capillary tube, an uneven distribution of the gaseous fuel may occur in the pre-chamber. In such situations, the uneven distribution may hinder ignition in the engine, especially if a relatively rich mixture with a fuel concentration above an upper ignition limit aggregates at an area of a spark plug electrode at which the spark originates.

[0004] To facilitate reliable ignition in large lean gas engines, unflushed prechamber spark plugs are used. These spark plugs contain an integral pre-chamber that forms a part of the spark plug, and which can be replaced with the spark plug. To increase an efficiency of such spark plugs, the pre-chamber can be flushed with fuel, resulting in problems listed above.

[0005] German Application Number 102005005851 describes a method for supplying gaseous or liquid fuel or fuel-air mixture via channels or separate pathways of a pre-chamber during a compression stroke in the pre-chamber. The fuel-air mixture is supplied to an ignition spark section in the form of a mixture cloud and ignited by an ignition spark. A mixture of materials of two different compositions takes place in the pre-chamber before spark ignition.

Summary of the Disclosure [0006] In one aspect of the present disclosure, a pre-chamber for use in at least one of an engine and a spark plug. The pre-chamber includes a capillary tube positioned at one side of the pre-chamber. The pre-chamber also includes a ring element positioned within the pre-chamber. The ring element includes an annular main body defining an annular groove. The annular groove is formed to circumferentially surround the main body of the ring element. The annular groove is in fluid communication with the capillary tube. The ring element also includes a plurality of holes formed in the main body. The plurality of holes provide fluid communication between the annular groove and an internal volume of the pre-chamber.

[0007] In another aspect of the present disclosure, an ignition assembly is provided. The ignition assembly includes a spark plug. The spark plug includes a housing. The ignition assembly also includes a pre-chamber coupled to the housing. The pre-chamber includes a capillary tube positioned at one side of the pre-chamber. The pre-chamber also includes a ring element positioned within the pre-chamber. The ring element includes an annular main body defining an annular groove. The annular groove is formed to circumferentially surround the main body of the ring element. The annular groove is in fluid communication with the capillary tube. The ring element also includes a plurality of holes formed in the main body. The plurality of holes provide fluid communication between the annular groove and an internal volume of the pre-chamber.

[0008] In yet another aspect of the present disclosure, an engine is provided. The engine includes at least one combustion chamber formed within the engine. The engine also includes an ignition assembly coupled to the at least one combustion chamber. The ignition assembly includes a spark plug. The spark plug includes a housing. The ignition assembly also includes a pre-chamber coupled to the housing. The pre-chamber includes a capillary tube positioned at one side of the pre-chamber. The pre-chamber also includes a ring element positioned within the pre-chamber. The ring element includes an annular main body defining an annular groove. The annular groove is formed to circumferentially surround the main body of the ring element. The annular groove is in fluid communication with the capillary tube. The ring element also includes a plurality of holes formed in the main body. The plurality of holes provide fluid communication between the annular groove and an internal volume of the pre-chamber.

[0009] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings [0010] FIG. 1 is a sectional view of a portion of an exemplary engine, according to one embodiment of the present disclosure;

[0011] FIG. 2 is a sectional view of a portion of an ignition assembly having a pre-chamber; and [0012] FIG. 3 is a top view of a ring element of the pre-chamber.

Detailed Description [0013] Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Also, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.

[0014] Referring to FIG. 1, a sectional view of a portion of an exemplary engine 100 is illustrated. The engine 100 is an internal combustion engine. The engine 100 is a four stroke engine that uses four stroke cycles, i.e. intake, compression, expansion, and exhaust for generating power. Alternatively, the engine 100 may include any other internal combustion engine, such as, a spark ignition engine, a compression ignition engine, a natural gas engine, among others to carry out principles of current disclosure without departing from the meaning and scope of the disclosure.

[0015] The engine 100 is a V-type engine. Alternatively, the engine 100 may embody an inline engine. The engine 100 may be used to power a machine including, but not limited to, an on-highway truck, an off-highway truck, an earth moving machine, an electric generator, etc. Further, the engine 100 may be associated with an industry including, but not limited to, transportation, construction, agriculture, forestry, power generation, and material handling.

[0016] The engine 100 includes a cylinder head (not shown) and a cylinder block 102. Further, the engine 100 includes a cylinder 104. Based on the type of application, the engine 100 may embody a 6-cylinder engine or an 8-cylinder engine. A cylinder bore 106 is defined in the cylinder block 102 of the engine 100. It should be understood that although only one-cylinder bore 106 is shown, the engine 100 would likely include multiple cylinder holes 106.

[0017] A piston 108 reciprocates within the cylinder bore 106 of the engine 100. A crankshaft 110 and a connecting rod 112 are operatively connected to the piston 108. Further, the engine 100 includes a main combustion chamber 114, hereinafter interchangeably referred to as main chamber 114. The main chamber 114 is formed within the cylinder bore 106 of the engine 100. More particularly, the piston 108, the cylinder 104, and associated cylinder head define the main chamber 114 above the piston 108.

[0018] The engine 100 includes a valve timing mechanism 116. The valve timing mechanism 116 includes two camshafts with axes extending in the longitudinal direction of the engine 100. An intake camshaft 118 and an exhaust camshaft (not shown) rotate to operate a pair of intake valves 120 and a pair of exhaust valves (not shown) respectively located in the associated cylinder head. The intake valves 120 are movable based on a movement of a push rod 122 and a rocker arm 124 associated with the intake camshaft 118. Similarly, the exhaust valves are movable by another push rod and rocker arm associated with the exhaust camshaft.

[0019] As is conventional, the cylinder head has intake and exhaust ports (not shown) leading to the main chamber 114 sealed by head portions of the intake valves 120 and the head portions of the exhaust valves, when the respective valves are in a closed operative position. The intake and exhaust ports are connected to intake and exhaust passages (not shown) for introducing air to the main chamber 114 and allowing the discharge of combustion products from the main chamber 114.

[0020] The engine 100 also includes an ignition assembly 126. The ignition assembly 126 is located substantially central to the intake valves 120 and the exhaust valves, and an axial centerline of the piston 108 and the cylinder bore

106 in which the piston 108 reciprocates. The ignition assembly 126 includes a pre-combustion chamber 128, hereinafter interchangeably referred to as prechamber 128. A portion of the pre-chamber 128 protrudes into the main chamber 114. The ignition assembly 126 also includes a spark plug 130. In some examples, the pre-chamber 128 and the spark plug 130 are provided in the cylinder head of the engine 100. In one example, the pre-chamber 128 may form an integral part of the spark plug 130. More particularly, for a small size engine, the pre-chamber 128 may be small in size, and form a part of the spark plug 130. In another example, the pre-chamber 128 and the spark plug 130 may be formed as separate components that are later assembled to form the ignition assembly 126. More particularly, for a large size engine, the pre-chamber 128 is manufactured as a separate component of a size that is larger than the size of the pre-chamber for the small size engine.

[0021] Referring now to FIG. 2, the spark plug 130 of the ignition assembly 126 includes a housing 132. The housing 132 encloses the spark plug 130 and a portion of the pre-chamber 128. The pre-chamber 128 is coupled to the housing 132. The housing 132 includes external threads so that the housing 132 can be coupled to the cylinder head of the engine 100 (see FIG. 1).

[0022] An internal volume 134 is defined by the pre-chamber 128. The spark plug 130 is in fluid communication with the internal volume 134 of the prechamber 128. The spark plug 130 initiates a first combustion in the pre-chamber 128 in order to create jets, based on an ignition spark from tips 138 of the spark plug 130. Further, the pre-chamber 128 is in fluid communication with the main chamber 114 (see FIG. 1) via orifices 136. The jets created in the pre-chamber 128 may spread to improve combustion efficiency in the main chamber 114 since the jets may rapidly spread through a volume of the cylinder 104, serving as an ignition source for the main chamber 114. A second combustion in the main chamber 114 may take place based on the ignition timing in the pre-chamber 128 as well as based on the spreading of the jets created in the pre-chamber 128. In some examples, a second volume 140 is defined in the housing 132 above the tips 138. The second volume 140 stores exhaust gases residue from the previous combustion event.

[0023] Further, the pre-chamber 128 includes a capillary tube 142. The capillary tube 142 extends vertically along one side of the pre-chamber 128. The capillary tube 142 is provided in the housing 132. The capillary tube 142 receives a gaseous fuel for flushing of the pre-chamber 128. The capillary tube 142 may embody any known in the art tube that allows a flow of gaseous fuel therethrough. Further, the gaseous fuel used for flushing may be same as an operating fuel introduced in the engine 100. In some examples, the gaseous fuel may be different from the operating fuel introduced in the engine 100. In one example, the gaseous fuel may include natural gas, such as methane.

[0024] Referring to FIGS. 2 and 3, the pre-chamber 128 also includes a ring element 144. The ring element 144 is positioned within the pre-chamber 128. The ring element 144 is embodied as an annular porous ceramic ring. The ring element 144 is made of a high temperature ceramic element so that the ring element 144 can sustain high temperatures during operation of the engine 100. The ring element 144 may be made of any porous ceramic material known in the art that meets application requirements.

[0025] The ring element 144 includes an annular main body 145, hereinafter interchangeably referred to as main body 145. The main body 145 defines an annular groove 146. The annular groove 146 is formed to circumferentially surround the main body 145 of the ring element 144. The annular groove 146 is provided at an outer side 148 (see FIG. 3) of the ring element 144, such that the annular groove 146 is in communication with an outer surface 150 (see FIG. 3) of the ring element 144.

[0026] The annular groove 146 is disposed at a central portion of a thickness “t” (see FIG. 2) of the main body 145. Further, a height “h” (see FIG. 2) of the annular groove 146 is lesser than the thickness “t” of the main body 145 of the ring element 144. In one embodiment, the annular groove 146 is provided centrally and extends from the outer surface 150 of the ring element 144 towards a centrally disposed through hole that defines the inner surface 154 of the ring element 144, forming a circular passage along the ring element 144. The annular groove 146 is in fluid communication with the capillary tube 142 (see FIG. 2), such that the capillary tube 142 and the annular groove 146 of the ring element

144 introduce the gaseous fuel in the internal volume 134 of the pre-chamber 128. The gaseous fuel received from the capillary tube 142 flows sideward within the internal volume 134 of the pre-chamber 128 and is introduced into the annular groove 146.

[0027] In one example, the annular groove 146 is formed by machining the main body 145. For example, the main body 145 may be milled to form the annular groove 146. Alternatively, the main body 145 may be manufactured by molding such that the main body 145 includes the annular groove 146. The main body 145 having the annular groove 146 may be manufactured by an additive manufacturing process, such as, 3D printing.

[0028] The ring element 144 includes a number of holes 152 formed within the main body 145. The holes 152 of the ring element 144 provide fluid communication between the annular groove 146 and the internal volume 134 of the pre-chamber 128. Some of the holes 152 extend between the annular groove 146 and an inner surface 154 (see FIG. 3) of the ring element 144 to form a fluid communication between the annular groove 146 and the internal volume 134 of the pre-chamber 128. Thus, the gaseous fuel is introduced into the internal volume 134 via the capillary tube 142, the annular groove 146, and the holes 152. In one example, the holes 152 may be integrally formed in the ring element 144 during manufacturing of the ring element 144. Alternatively, the material of the ring element 144 may be chosen such that the ring element 144 includes the number of holes 152. For example, the ring element 144 may include a porous ceramic element having a number of holes, as discussed above.

[0029] A density and size of the holes 152 may vary based on application requirements. The size, and more particularly, a diameter of each of the holes 152 is decided such that the respective holes 152 allow smooth passage of the gaseous fuel from the annular groove 146 towards the internal volume 134. Further, the diameter of the each of the holes 152 is also decided such that the respective holes 152 control flame backlash from the internal volume 134 of the pre-chamber 128 into the annular groove 146 via the holes 152. More particularly, the holes 152 act as flame retardants so that the products of combustion or flames in the pre-chamber 128 may not travel towards the annular groove 146 and the capillary tube 142. In one example, the diameter of the holes 152 is approximately between 0.3 mm and 0.5 mm.

[0030] During operation, the gaseous fuel that is introduced into the internal volume 134 of the pre-chamber 128 mixes with an air-fuel mixture present in the internal volume 134, thereby enriching the mixture. The enriched mixture is ignited by the spark plug 130 to form the jets in the pre-chamber 128, which are then introduced into the main chamber 114 (see FIG. 1) for second combustion.

Industrial Applicability [0031] The present disclosure relates to the ignition assembly 126 having the pre-chamber 128. The pre-chamber 128 includes the capillary tube 142 and the ring element 144. The gaseous fuel is introduced into the internal volume 134 of the pre-chamber 128 via the capillary tube 142 and the ring element 144. The ring element 144 includes the main body 145. The main body 145 includes the annular groove 146 and the number of holes 152 that allow introduction of the gaseous fuel into the internal volume 134.

[0032] The diameter of each of the holes 152 is small enough so that the flame from the internal volume 134 is prevented from entering through the holes 152 into the annular groove 146. As the gaseous fuel is supplied via several holes 152, the pre-chamber 128 can be flushed even if some of the holes 152 may be clogged by deposits. Further, as the holes 152 are small in size and the flames from the internal volume 134 cannot enter the annular groove 146 or the capillary tube 142, it is possible to design the capillary tube 142 which conducts the gaseous fuel gas into the pre-chamber 128 with a larger diameter, further reducing chances of the clogging of the capillary tube 142. The ring element 144 also allows even distribution of the gaseous fuel in the internal volume 134 of the pre-chamber 128, thereby promoting ignition.

[0033] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

1. A pre-chamber for use in at least one of an engine and a spark plug, the pre-chamber comprising:

a capillary tube positioned at one side of the pre-chamber; and a ring element positioned within the pre-chamber, the ring element comprising:

an annular main body defining an annular groove, wherein the annular groove is formed to circumferentially surround the main body of the ring element, and wherein the annular groove is in fluid communication with the capillary tube; and a plurality of holes formed in the main body, wherein the plurality of holes provide fluid communication between the annular groove and an internal volume of the pre-chamber.

2. The pre-chamber of claim 1, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to control flame backlash from the internal volume of the pre-chamber into the annular groove.

3. The pre-chamber of claim 1, wherein the ring element is an annular porous ceramic ring.

4. The pre-chamber of claim 1, wherein the ring element is made of a hightemperature resistant ceramic.

5. The pre-chamber of claim 1, wherein the capillary tube and the annular groove of the ring element are adapted to introduce a gaseous fuel into the internal volume of the pre-chamber.

6. The pre-chamber of claim 5, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to allow passage of the gaseous fuel from the annular groove to the internal volume of the prechamber.

7. The pre-chamber of claim 1, wherein the ring element is milled to form the annular groove therein.

8. The pre-chamber of claim 1, wherein a height of the annular groove is lesser than a thickness of the main body of the ring element.

9. The pre-chamber of claim 8, wherein the annular groove is disposed at a central portion of the thickness of the main body.

10. An ignition assembly for an engine comprising:

a spark plug having a housing; and a pre-chamber coupled to the housing, the pre-chamber comprising:

a capillary tube positioned at one side of the pre-chamber;

and a ring element positioned within the pre-chamber, the ring element comprising:

11. The ignition assembly of claim 10, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to control flame backlash from the internal volume of the pre-chamber into the annular groove.

12. The ignition assembly of claim 10, wherein the ring element is an annular porous ceramic ring.

13. The ignition assembly of claim 10, wherein the capillary tube and the annular groove of the ring element are adapted to introduce a gaseous fuel into the internal volume of the pre-chamber.

14. The ignition assembly of claim 13, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to allow passage of the gaseous fuel from the annular groove to the internal volume of the pre-chamber.

15. The ignition assembly of claim 10, wherein a height of the annular groove is lesser than a thickness of the main body of the ring element.

16. The ignition assembly of claim 15, wherein the annular groove is disposed at a central portion of the thickness of the main body.

17. An engine comprising:

at least one combustion chamber formed within the engine; and an ignition assembly coupled to the at least one combustion chamber, the ignition assembly comprising:

a capillary tube positioned at one side of the prechamber; and a ring element positioned within the pre-chamber, the ring element comprising:

18. The engine of claim 17, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to control flame backlash from the internal volume of the pre-chamber into the annular groove.

19. The engine of claim 17, wherein the ring element is an annular porous ceramic ring.

20. The engine of claim 17, wherein a diameter of each of the plurality of holes is such that the respective hole is adapted to allow passage of a gaseous fuel from the annular groove to the internal volume of the prechamber.

Intellectual

Property

Office

Application No: GB1613293.8 Examiner: Mr Mat Smith