Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/28—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of coaxial valves; characterised by the provision of valves co-operating with both intake and exhaust ports
  • F01L1/285—Coaxial intake and exhaust valves

Definitions

• the present invention relates to an intake and exhaust valve system for an internal combustion engine.
• Intake and exhaust valve systems commonly used in relation to internal combustion engines include rotary, sleeve and poppet valves. Of such valves, poppet valves are favoured and are predominantly in use. In typical arrangements, intake and exhaust poppet valves are separate from each other.
• BERGERON As identified in BERGERON, deficiencies of some of the prior proposals for concentric intake and exhaust valve systems include excessive mass associated with such arrangements, and loading problems caused by the relatively large surface area of the exhaust valve opening against compressed gases within the combustion chamber.
• BERGERON seeks to provide a concentric intake and exhaust valve system which provides an increased volume of charge per unit time through the engine per intake stroke and which also reduces the mass of the concentric valve assembly. Nevertheless, the intake and exhaust system proposed by BERGERON still presents a significant reciprocating mass which is undesirable.
• FALERO utilises a concentric intake and exhaust valve system in which the outer intake valve has a hollow bell-shaped valve disc.
• the outer intake valve has a valve stem connected to the bell-shaped valve disc by radial arms, with the radial arms and the adjacent end of the valve stem being located within the confines of the bell-shaped valve disc.
• the bell-shaped valve disc has a generally cylindrical side wall with a flanged portion at the free end of the side wall to sealing contact with a valve seat and an inwardly curved section at the other end of the side wall.
• the cylindrical side wall slidingly engages an inner generally cylindrical surface defined by a somewhat annular projection positioned between the intake and exhaust ports.
• the annular projection co-operates with the cylindrical side wall of - 3 - the bell-shaped valve disc to maintain separation between the intake and exhaust ports during movement of the outer intake valve.
• FALERO does not address the problem of reciprocating mass, as is apparent from the size of the bell-shaped valve disc. Indeed, the intake and exhaust valve system proposed by FALERO utilises an arrangement in which the axial length of the side wall of the bell-shaped valve disc exceeds the axial length of the cylindrical surface on the annular projection.
• the size of the cylindrical side wall on the bell-shaped valve disc is disadvantageous in that it provides the valve with a significant reciprocating mass which is undesirable.
• a further disadvantage of FALERO is location of the radial arms connecting the bell-shaped valve disc. Because the adjacent end of the valve stem is located within the confines of the hollow bell-shaped valve disc through which there is fluid flow, the presence of the valve stem can have the effect of reducing the cross-sectional flow area within the valve, so providing a restriction to flow.
• a still further disadvantage of FALERO is that the annular projection forming the cylindrical surface cannot be readily refurbished or replaced in the event of excessive wear or damage.
• the present invention seeks to provide an intake and exhaust valve system which has a reduced reciprocating mass in comparison to the prior art referred to above or at least provides a useful choice as an alternative to such prior art proposals.
• the present invention provides an intake and exhaust valve system for an internal combustion engine having a combustion chamber within a cylinder closed at one end by a cylinder head, the valve system comprising a cavity in the cylinder head opening onto the combustion chamber through a first port; a valve assembly comprising first and second valves one of which is an intake valve movable between open and closed conditions for controlling intake fluid flow into the combustion chamber and the other of which is an exhaust valve movable between open and closed conditions for controlling exhaust gas flow from the combustion chamber; the first valve comprising a valve head sealingly engagable with the first port and a skirt structure; the skirt structure being in sliding and sealing engagement with a tubular wall structure within the cavity whereby the skirt and wall structures cooperate to divide the cavity into an inner cavity section and an outer cavity section surrounding the inner cavity section; a first flow passage communicating with the outer cavity section; and a second flow passage communicating with the inner cavity section; the second valve being disposed in the first valve for opening and closing a second port in the first valve for controlling fluid flow between the combustion chamber and inner cavity section
• This arrangement provides a concentric intake and exhaust valve system with reduced reciprocating mass in comparison to the prior art proposals referred to hereinbefore.
• the reduction in reciprocating mass is accomplished by an arrangement: (a) which utilises the skirt structure (which forms part of the reciprocating mass) and the wall structure (which does not form part of the reciprocating mass) to separate the intake and exhaust gas flow paths; and (b) in which the axial length of the skirt structure is less than the axial length of the wall structure.
• the skirt structure is preferably cylindrical, as is also the tubular wall structure within the cavity.
• the skirt structure may be sealingly engagable with the tubular wall structure by way of any suitable means such as a close sliding fit or by sealing means such as sealing rings provided therebetween.
• tubular wall structure may be formed integrally with the cylinder head, it is preferably formed separately thereof and attached thereto in any suitable fashion.
• the first valve preferably has a valve stem connected to the skirt structure.
• the connection between the valve stem and the skirt structure may be provided by one or more connecting elements extending therebetween.
• the or each connecting element presents a thin profile in the direction of fluid flow so as to minimise any disturbance to such flow.
• valve stem is located outside of the confines of the skirt structure.
• the first valve stem may be hollow to provide an axial passage in which the stem of the second valve is received.
• the second valve stem is preferably guidingly supported within the hollow first valve stem for reciprocation relative thereto.
• the second valve stem may extend beyond the first valve stem.
• the first valve stem and the second valve stem are preferably connected to means operable to move the first and second valves between their respective open and closed conditions in timed sequence.
• a first valve biasing means such as a valve spring may be provided for biasing the first valve into the closed condition.
• a second valve biasing means such as a valve spring may be provided for biasing the second valve into the closed condition.
• the first valve is the intake valve and the second valve is the exhaust valve.
• the present invention further provides an intake and exhaust valve system for an internal combustion engine having a combustion chamber within a cylinder closed at one end by a cylinder head, the valve system comprising a cavity in the cylinder head opening onto the combustion chamber through an intake port; a valve assembly comprising an intake valve movable between open and closed conditions for controlling intake fluid flow into the combustion chamber and an exhaust valve movable between open and closed conditions for controlling exhaust gas flow from the combustion chamber; the intake valve comprising a valve head sealingly engagable with the intake port and a skirt structure; the skirt structure being in sliding and sealing engagement with a tubular wall structure whereby the skirt and wall structures cooperate to divide the cavity into an inner cavity section and an outer cavity section surrounding the inner cavity section; an of intake flow passage communicating with the outer cavity section for delivery intake fluid thereto; and an exhaust flow passage communicating with the inner cavity section; the exhaust valve being disposed in the intake valve for opening and closing an exhaust port in the intake valve for controlling exhaust gas from the combustion chamber into the inner cavity section; wherein the skirt structure has a first axial
• the present invention still further provides an intake and exhaust valve system for an internal combustion engine having a combustion chamber within a cylinder closed at one end by a cylinder head, the valve system comprising a cavity in the cylinder head opening onto the combustion chamber through a first port; a valve assembly comprising first and second valves one of which is an intake valve movable between open and closed conditions for controlling intake fluid flow into - 7 -
• the first valve comprising a valve head sealingly engagable with the first port and a skirt structure; a tubular wall structure removably mounted in the cavity; the skirt structure being in sliding and sealing engagement with the tubular wall structure within the cavity whereby the skirt and wall structures cooperate to divide the cavity into an inner cavity section and an outer cavity section surrounding the inner cavity section; a first flow passage communicating with the outer cavity section; and a second flow passage communicating with the inner cavity section; the second valve being disposed in the first valve for opening and closing a second port in the first valve for controlling fluid flow between the combustion chamber and inner cavity section.
• the present invention provides an intake and exhaust valve system for an internal combustion engine having a combustion chamber within a cylinder closed at one end by a cylinder head, the valve system comprising a cavity in the cylinder head opening onto the combustion chamber through a first port; a valve assembly comprising first and second valves one of which is an intake valve movable between open and closed conditions for controlling intake fluid flow into the combustion chamber and the other of which is an exhaust valve movable between open and closed conditions for controlling exhaust gas flow from the combustion chamber; the first valve comprising a valve head sealingly engagable with the first port and a skirt structure; the skirt structure being in sliding and sealing engagement with a tubular wall structure within the cavity whereby the skirt and wall structures cooperate to divide the cavity into an inner cavity section and an outer cavity section surrounding the inner cavity section; a first flow passage communicating with the outer cavity section; and a second flow passage communicating with the inner cavity section; the second valve being disposed in the first valve for opening and closing a second port in the first valve for controlling fluid flow between the combustion chamber and inner cavity section
• the present invention still further provides a cylinder head for accommodating an intake and exhaust system as previously defined, the cylinder head comprising a body having a cavity and an insert removably received in the body, the first and second valves being mounted in the insert.
• Figure 1 is a schematic sectional view of a cylinder head incorporating an intake and exhaust valve system according to a first embodiment, with the intake and exhaust valves being shown in the closed condition;
• Figure 2 is a side view of Figure 1 ;
• FIG. 3 is view similar to Figure 1 with the exception that the exhaust valve is shown in an open condition
• Figure 4 is also a view similar to Figure 1 with the exception that the intake valve is also shown in an open condition;
• Figure 5 is a side view of the cylinder head showing intake and exhaust passages forming part of the intake and exhaust valve system
• Figure 6 is a side view of an intake valve used in the valve assembly
• Figure 7 is a sectional side view of the intake valve
• Figure 8 is a side view of an exhaust valve used in the valve assembly
• Figure 9 is a side view of a wall structure forming part of the valve assembly.
• Figure 10 is a sectional side view of the wall structure
• Figure 11 is a schematic sectional view of a cylinder head incorporating valve system according to a second embodiment, with the intake and exhaust valves being shown in the closed condition;
• Figure 12 is a view similar to Figure 11 with the exception that the exhaust valve is shown in an open condition;
• Figure 13 is also a view similar to Figure 11 with the exception that the intake valve is also shown in an open condition;
• Figure 14 is a schematic sectional view of a cylinder head of modular construction, incorporating an intake and exhaust valve system according to a third embodiment
• Figure 15 is a side sectional view of the cylinder head of Figure 14;
• Figure 16 is a sectional view of a body forming part of the cylinder head of Figure 14.
• Figure 17 is a side view of an insert adapted to be received in the body of Figure 16.
• the first embodiment shown in Figures 1 to 10 of the drawings is directed to an intake and exhaust valve system 10 for a four-stroke internal combustion engine - 10 - comprising a cylinder block 11 defining a cylinder 13.
• a piston 15 is mounted for reciprocation within the cylinder 13 and is connected to a crankshaft (not shown) in conventional fashion.
• a cylinder head 17 is mounted on the cylinder block 11 and closes one end of the cylinder 13.
• a combustion chamber 19 is defined within the cylinder 13 between the piston 15 and the cylinder head 17.
• the cylinder head 17 incorporates a threaded hole 21 for installation of a spark plug (not shown) for ignition of a combustible mixture in the combustion chamber 19.
• the intake and exhaust valve system 10 is provided for controlling the introduction of a combustible air/fuel mixture into the combustion chamber 19 and for controlling the discharge of spent products of combustion (exhaust gases) from the combustion chamber.
• the valve system 10 comprises a cavity 25 formed in the cylinder head 17.
• the cavity 25 comprises a generally cylindrical upper section 25a, a somewhat bulbous intermediate section 25b, and a generally cylindrical lower section 25c.
• the cavity 25 opens onto the combustion chamber 19 at the lower section 25c by way of an intake port 27 which is surrounded by a valve seat 29.
• an edge 22 which incorporates a circumferential recess 24, the purpose of which will become apparent later.
• An intake fluid flow passage 26 is formed in the cylinder head 17 to communicate with the cavity 25 for delivery of an intake fluid thereto (the intake fluid in this embodiment being an air/fuel mixture but it may be air only in an engine having a direct-fuel injection system).
• An exhaust fluid flow passage 28 is also formed in the cylinder head to communicate with the cavity 25 for discharge of exhaust gases therefrom.
• a valve assembly 30 comprises an intake valve 31 moveable between open and closed conditions in relation to the intake port 27 for controlling intake of the air-fuel mixture into the combustion chamber 19.
• the valve assembly 30 further - 11 - comprises an exhaust valve 33 moveable between open and closed conditions for controlling flow of products of combustion from the combustion chamber 19.
• Valve timing gear 32 of known kind is used to control movement of each valve 31 , 33 between the open and closed conditions.
• the intake valve 31 and the exhaust valve 33 are each biased into the closed condition by a respective valve spring 34.
• the valve timing gear 32 includes push-rods 36 and rocker arms 38.
• the intake valve 31 comprises a valve head 35, a skirt structure 37, a hollow valve stem 39, and a connection structure 41 connecting the valve stem 39 to the skirt structure 37.
• the valve head 35 presents a valve face 43 which is adapted to sealingly engage the valve seat 29 of the intake port 27 when the intake valve is in a closed condition.
• the skirt structure 37 is of cylindrical construction and its purpose will be described later.
• the connection structure 41 extends between the skirt structure 37 and the valve stem 39 and comprises a plurality of connecting elements 44 in circumferentially spaced relationship to the valve stem, as best seen in Figure 6 of the drawings.
• the connecting elements 44 each present a thin profile along the axial length of the valve stem so as to minimise any disturbance of fluid flow through the region defined between the skirt structure 37 and the valve stem 39, as will be explained in more detail later.
• the connecting elements 44 may extend substantially for the full axial length of the skirt structure 37 so as to provide adequate support between the skirt structure and the valve stem.
• the valve stem 39 is located entirely outside of the confines of the skirt structure 37 so as not to require the cross-sectional flow area within the skirt structure.
• the skirt structure 37 is in sliding and sealing engagement with a tubular wall structure 49 disposed within the cavity 25 whereby the skirt and the tubular wall structure cooperate to divide the cavity into an inner cavity section 51 and an outer cavity section 53 which surrounds the inner cavity section.
• the tubular wall structure 49 is adapted to be releasably mounted in the cavity 25.
• the tubular wall structure 49 comprises an annular body 54 having a - 12 - mounting flange portion 55 adjacent to, and inwardly spaced from, one end of the annular body.
• the inward spacing of the mounting flange portion 55 provides the tubular wall structure 49 with a locating portion 56 on the body at said one end thereof.
• the locating portion 56 of the tubular wall structure 49 is adapted to be received in the circumferential recess 24 in the edge 22 between the upper and intermediate cavity sections 25a and 25b respectively, with the mounting flange portion 55 bearing against the edge 22, as best seen in Figures 1 , 3 and 4.
• the mounting flange portion 55 is adapted to be detachably secured to the cylinder head 17 in any suitable fashion such as by machine screws (not shown).
• tubular wall structure 49 is removably mounted in the cavity, it can be removed for refurbishment or replacement as necessary.
• the skirt structure 37 is sealingly engagable with the tubular wall structure 49 by way of a close sliding fit which provides an effective seal therebetween while allowing reciprocation of the skirt structure with respect to the wall structure.
• the skirt structure 37 has an axial length (as identified by reference character X is Figure 7) which is less than the axial length of the wall structure 49 (as identified by reference character Y in Figure 10).
• Such an arrangement is intended to reduce the reciprocating mass of the intake valve 31.
• the stem 39 of the intake valve 31 extends axially through the cavity 25 and through a guide hole 57 axially aligned therewith in the cylinder head 17.
• the guide hole 57 is defined by a guide sleeve 58 mounted in the cylinder head 17.
• the hollow stem 39 has an axial passage 40 which includes two portions (not shown) of reduced section which provide bearing surfaces. - 13 -
• the valve head 35 incorporates an exhaust port 61 which provides fluid communication between the inner cavity section 51 and the combustion chamber 19.
• the exhaust port 61 is surrounded by a valve seat 63.
• the exhaust valve 33 is disposed within the intake valve 31 for opening and closing the exhaust port 61 defined within the intake valve 31 for controlling flow of the exhaust gases from the combustion chamber 19.
• the exhaust valve 33 comprises a valve head 65 and a valve stem 67.
• the valve head 65 presents a valve face 69 which is adapted to sealingly engage the exhaust port valve seat 63 in the exhaust port 61 when the exhaust valve is in a closed condition.
• the exhaust valve stem 67 is slidably supported within the axial passage 40 of the hollow valve stem 37 of the intake valve 31 for guided movement therealong.
• the bearing surfaces (not shown) in the axial passage 40 within the hollow valve stem 39 slidingly and guidingly support the valve stem 67 while limiting the extent of contact between the two stems thereby to reduce frictional losses.
• valve stem 67 of the exhaust valve 33 extends beyond the valve stem 39 of the intake valve 31 , as shown in the drawings.
• the intake valve stem 39 and the exhaust valve stem 67 are responsive to the valve timing gear 32 operable to move the intake and exhaust valves between their respective open and closed conditions in timed sequence.
• FIG. 1 of the drawings shows both the intake and exhaust valves 31 , 33 in their respective closed conditions.
• the valve system will be described in operation from commencement of the exhaust stroke where the inlet and exhaust valves 31 ,
• Opening of the inlet valve 31 allows a combustible air-fuel mixture to flow along the intake passage 26 into the outer cavity section 53 and enter the combustion chamber 19 through the inlet port 27.
• the intake valve 31 returns to the closed conditions as shown in Figure 1 of the drawings, together with the closed exhaust valve 33.
• the skirt 37 maintains sealing engagement with the tubular wall structure 49. This ensures that there are separate flow paths for the intake mixture and the exhaust gases.
• the intake valve 31 is the outer of the two valves in the concentric valve assembly 30.
• the outer valve is larger and so provides less restriction to fluid flow, which is beneficial in terms of the intake process.
• the intake mixture can be in heat exchange relationship with the cylinder head 17 (and more particularly with the tubular wall structure 49 and with the intake valve 31 ) and so receive heat therefrom and so provide some cooling.
• valve timing gear 34 for controlling operation of each of the intake and exhaust valves 31 and 33 respectively is of the underhead type.
• valve timing gear 90 is of an overhead configuration which is not of conventional construction.
• the valve timing gear 90 employs an upper rocker arm 91 and a lower rocker arm 92.
• a valve spring 93 is accommodated between an upper spring retainer 95 which is attached to the stem 67 of the exhaust valve 33, and a lower spring retainer 97 which is attached to the stem 39 of the intake valve 31.
• the upper and lower rocker arms 91 and 92 respectively are operated by a common cam 99 having two cam profiles 101, 102.
• the upper rocker arm 91 is operated by cam profile 101
• the lower rocker arm 92 is operated by cam profile 102.
• the upper rocker arm 91 controls operation of the exhaust valve 33 and acts on the free end of the valve stem 67 thereof.
• the lower rocker arm 92 controls operation of the intake valve 31 and acts on the underside of the lower spring retainer 97 which is attached to the intake valve 31.
• the lower rocker arm 92 is positioned on a lobe 104 of the cam 102, preventing the retainer 97 from moving towards the cylinder 13, keeping the intake valve 31 closed.
• the lower rocker arm 92 is positioned on a flat 103 of the cam 102, the lower rocker arm 92 is 'relaxed', allowing the spring 93 to expand, as can be seen in Figure 13, pushing the retaining 97 towards the cylinder 13, opening the intake valve 31.
• This arrangement has the advantage of a common cam 99 and associated drive mechanism therefor, as well as a common valve spring 93.
• valve systems are incorporated into a cylinder head 17 which presents some difficulties in manufacture owing to the need to form the cavity 25 with its three sections 25a, 25b and 25c, and the associated intake passage 26 and exhaust passage 28, as well as the valve seat 29. Similarly, such a construction can present difficulties when repairs or refurbishment of the cylinder head is necessary.
• the intake and exhaust valve system utilises a cylinder head 110 of modular construction.
• the cylinder head 110 comprises a body 111 formed with a cavity 113 which receives an insert 115.
• the body 111 is formed with the intake passage 26 and exhaust passage 28 which open onto the cavity 113.
• the insert 115 is formed with the cavity 25 and associated valve seat 29, and accommodates the intake valve 31 and exhaust valve 33.
• the cavity 25 in the insert registers with the intake passage 26 and exhaust passage 28 in the body 111. This then provides the cylinder head 110 incorporating a concentric intake arm exhaust valve system similar to the first and second embodiments.
• This embodiment has the advantage that the insert 115 (and accompanying intake valve 31 and exhaust valve 33) can simply be removed for repair or replacement, as necessary.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

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• 1998
  • 1998-01-23 AU AUPP1523A patent/AUPP152398A0/en not_active Abandoned
• 1999
  • 1999-01-22 JP JP2000528779A patent/JP4372998B2/ja not_active Expired - Fee Related
  • 1999-01-22 WO PCT/AU1999/000049 patent/WO1999037892A1/en not_active Ceased
• 2000
  • 2000-07-21 US US09/621,631 patent/US6546902B1/en not_active Expired - Fee Related

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