WO1992014923A1 - Internal combustion engines - Google Patents
Internal combustion engines Download PDFInfo
- Publication number
- WO1992014923A1 WO1992014923A1 PCT/GB1992/000291 GB9200291W WO9214923A1 WO 1992014923 A1 WO1992014923 A1 WO 1992014923A1 GB 9200291 W GB9200291 W GB 9200291W WO 9214923 A1 WO9214923 A1 WO 9214923A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- engine
- inlet
- exhaust
- valves
- valve
- Prior art date
Links
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 claims description 14
- 239000007789 gas Substances 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 230000002000 scavenging effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/104—Intake manifolds
- F02M35/108—Intake manifolds with primary and secondary intake passages
- F02M35/1085—Intake manifolds with primary and secondary intake passages the combustion chamber having multiple intake valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B31/00—Modifying induction systems for imparting a rotation to the charge in the cylinder
- F02B31/04—Modifying induction systems for imparting a rotation to the charge in the cylinder by means within the induction channel, e.g. deflectors
- F02B31/06—Movable means, e.g. butterfly valves
- F02B31/08—Movable means, e.g. butterfly valves having multiple air inlets, i.e. having main and auxiliary intake passages
- F02B31/085—Movable means, e.g. butterfly valves having multiple air inlets, i.e. having main and auxiliary intake passages having two inlet valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
- F02F1/4214—Shape or arrangement of intake or exhaust channels in cylinder heads specially adapted for four or more valves per cylinder
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B1/00—Engines characterised by fuel-air mixture compression
- F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
- F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B31/00—Modifying induction systems for imparting a rotation to the charge in the cylinder
- F02B2031/006—Modifying induction systems for imparting a rotation to the charge in the cylinder having multiple air intake valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/02—Engines characterised by their cycles, e.g. six-stroke
- F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
- F02B2075/027—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle four
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
- F02B2275/18—DOHC [Double overhead camshaft]
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F2001/244—Arrangement of valve stems in cylinder heads
- F02F2001/245—Arrangement of valve stems in cylinder heads the valve stems being orientated at an angle with the cylinder axis
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- This invention relates to internal combustion engines, and in particular to four stroke, throttled, gasoline engines having four poppet valves per cylinder.
- Valve timings and valve port flow areas affect power, especially if both inlet and exhaust valves are open at the same time, during a "valve overlap" phase. Further, they affect the exhaust emission composition, particularly with respect to unburnt hydrocarbons.
- the composition of exhaust emissions has a low proportion of unburnt hydrocarbons when the engine is operating at low and medium speeds, and at low loads, and it comprises an object of the present invention to provide an engine of a novel construction whereby this requirement is obtained in an advantageous way.
- a four stroke internal combustion engine has four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, leading individually to each of the inlet valves is a bifurcated part of the inlet port, characterised in that leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and the arrangement is such that the settings of the two flow control valves are changed in unison in response to variations of engine conditions, and such that the two flow control valves are fully closed when the engine is operating at
- the present invention relates to a method of operating a four stroke internal combustion engine having four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, and the method is characterised by operating an engine having a bifurcated part of the inlet port leading individually to each of the inlet valves, and leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and in the method the settings or the two flow control are changed in unison in response to variations of engine conditions, and such that the two
- flow control valves are fully closed when the engine is operating at least at a particular low or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed.
- Figure 1 is a valve event diagram for an engine and suitable for low and medium operating speeds of the engine
- Figure 2 corresponds to Figure 1, but is for higher operating speeds of the engine
- Figure 3 shows a typical valve train mechanism, and the associated part of the cylinder head, associated with a cylinder of an embodiment of a four stroke internal combustion engine, having four poppet valves per cylinder, and in accordance with the present invention
- FIG. 1 is a representation, generally in plan, of the part of the cylinder head shown in Figure 3, together with the inlet and exhaust ports associated with the four poppet valves.
- Valve timings to suit a typical engine so that there are desirably low unburnt hydrocarbon emissions, and required tractability , at low and medium engine speeds are indicated by the valve event diagram of Figure 1.
- TDC top dead centre
- BDC bottom dead centre
- the exhaust valve opens 50 degrees before BDC as indicated at C; and closes 5 degrees after BDC as indicated at D. There are only short “valve overlap" phases when both the inlet and exhaust valves are open, and curtailed timings due to the suppression of intake and exhaust pressure wave interactions.
- Valve timings to suit the same engine so that there is the required tractability, at higher engine speeds, are indicated by the valve event diagram of Figure 2.
- the inlet valve opens at 45 degrees before TDC; and, as indicated at B , the inlet valve closes at 65 degrees after BDC.
- the exhaust valve opens at 60 degrees before BDC; and as indicated at D , the exhaust valve closes at 35 degrees after TDC.
- the part of a throttled gasoline, four stroke, internal combustion engine shown in Figures 3 and 4 includes the cylinder head 2, an inlet camshaft 4 actuating first and second inlet valves, respectively, 6 and 7, via the usual tappet and spring system, and an exhaust camshaft 8 actuating first and second exhaust valves, respectively, 10 and 11, via the usual tappet and spring system.
- Gf the two inlet valves 6 and 7, and the two exhaust valves 10 and 11, only the face of the second inlet valve 7, and only the face of the second exhaust valve 11, are illustrated in Figure 1.
- the cam associated with the first inlet valve 6 is indicated at 14, and the cam associated with the first exhaust valve 10 is indicated at 16.
- Unillustrated cams are associated with the second inlet valve 7, and the second exhaust valve 11.
- the illustrated cams 14 and 16 have timing profiles suited to low and medium engine speeds, the corresponding inlet and exhaust valve timings, respectively, for the illustrated first inlet valve 6, and the illustrated first exhaust valve 10, being somewhat similar to those indicated on the valve event diagram of Figure 1.
- the unillustrated cams for the second xnlet valve ana tne second exhaust valve 11 have timing profiles suited to higher engine speeds, the corresponding inlet and exhaust - /
- valve timings being similar to those indicated on the valve event diagram of Figure 2.
- FIG. 3 Indicated in Figure 3 is the common inlet port 20 provided in the cylinder head 2 for the two inlet valves 6 and 7. Adjacent to the inlet valves 6 and 7 the inlet port 20 is bifurcated by a partition 22, so that the port is split into two passages each leading individually to an inlet valve. Similarly, a common exhaust port 24 is provided in the cylinder head 2 for the two exhaust valves 10 and 11. Adjacent to the exhaust valves 10 and 11 the exhaust port is bifurcated by a partition 26, so that the port is split into two passages each leading individually from an exhaust valve.
- Figure 4 is a representation, generally in plan, of the part of the cylinder head 2 shown in Figure 3.
- Figure 4 sh ws more clearl than Figure 3 both the arrangement of the two inlet valves 6 and 7, and the two exhaust valves 10 and 11, in relation to the cylinder; and also the arrangement of the inlet port 20 and the exhaust port 24 in relation to these valves.
- a pivotally mounted, plate type, flow control valve 56 there is provided in the passage 54 of the bifurcated part of tne inlet port 20 leading to the second inlet valve 7, a pivotally mounted, plate type, flow control valve 56; and there is provided in the passage 58 of the bifurcated part of the exhaust port 24 leading from the second exhaust valve 11, a second, pivotally mounted, plate type, flow control valve 60.
- the flow control valves 56 and 60 are linked together, for example, by mechanical means, and the settings thereof are controlled by ⁇ ovements of a linkage indicated generally at 62.
- Movements of the linkage 62, and corresponding changes of the settings of the flow control valves 56 and 60, are under the control of any suitable construction of actuator, indicated generally at 64, operatively coupled to a known form of electronic engine management controller (not shown), and subject to operation in accordance with pre-programmed data.
- the linkage may have any convenient form.
- the actuator may be coupled to the engine throttle (not shown).
- inlet and exhaust crankshafts 4 and 8 rotate, respectively, the two inlet cams and the two exhaust cams at half engine crankshaft speed, and all the valves 6, 7, 10, and 11 open and close at the timings determined by their respective cams.
- the first exhaust valve 10 provides an adequate exhaust time-area integral for blowdown, whilst he absence of "valve overlap" minimises the risk of undesired h drocarbon emissions from the engine due to unburnt charge being sucked directly from the passage 66 of t e bifurcated part of the inlet port 20 into the passage 68 of the bifurcated part of the exhaust port 24.
- the actuator 64 causes the linkage 62 to be moved, and tne settings of tne flow control valves 56 and 60 are changed so that these valves are fully open. Intake cnarge is no admitted to the cylinder through both the first and second inlet valves 6 and 7 when these valves are open; and exhaust gases are expelled from the cylinder through both the first and second exhaust valves 10 and
- the second inlet valve 7 Since the second inlet valve 7 is caused to be open in angular advance of the first inlet valve 6, the gas in the non-bifurcated part of the inlet port 20 accelerates before the first inlet valve 6 opens. Thus, when the first inlet valve 6 does open the mass flow through this valve is greater than otherwise would be the case.
- the plate valve 56 on the inlet side of the engine ma be of steel, brass, aluminium, or of a suitable plastics material.
- the plate valve 60 on the exhaust side of the engine is required to be of a heat resistant steel, or of a ceramic.
- the arrangement may be such hat the plate valves are actuated progressively above a predetermined percentage opening.
- the inlet and exhaust valves may be actuated by push rod and/or rocker means if there are provided cams individually actuating each valve.
- the plate valves controlling the flow to the second inlet valve, and from the second exhaust valve, could be slideably mounted instead of being pivotably moveable.
- the cams actuating the poppet valves each may be mounted individually on a camshaft.
- the mechanical linkage may be replaced by any suitable form of actuator; and separate actuators may be provided fcr the two plate valves.
- actuators may be provided fcr the two plate valves.
- low and medium engine speeds conveniently refer to engine speeds having the mean piston velocity up to 7 metres per second, for engines having bore to stroke ratios in the range 0.8:1 to 1.1:1.
- higher engine speeds conveniently refers to engine speeds having the mean piston velocity in the range 7 to 18 metres per second, with normal bore to stroke ratios as referred to in the preceding sentence, and a specific output in the range 50 to 90 Kilowatts per litre of swept cylinder volume for naturally aspirated engines.
Abstract
A four-stroke internal combustion engine having, per cylinder, first and second inlet valves (6, 7) and first and second exhaust valves (10, 11) has a bifurcated part of the inlet port leading individually to each inlet valve, and a bifurcated part of the exhaust port leading individually from each exhaust valve. The first inlet valve and the first exhaust valve are actuated by cams (14, 16) having timing profiles suited to low and medium engine speeds. The second inlet valve and the second exhaust valve are actuated by cams having timing profiles suited to higher engine speeds. The flow of intake charge to the second inlet valve, and the flow of exhaust gases from the second exhaust valve, are controlled by the settings of two valves (56, 60) in the inlet and exhaust ports being changed in unison. The control valves are opened either at a particular engine setting, or over a range of engine settings.
Description
Internal combustion engines
This invention relates to internal combustion engines, and in particular to four stroke, throttled, gasoline engines having four poppet valves per cylinder.
It is known that the respective angular timings of poppet inlet and exhaust valves in four stroke engines affect scavenging efficiency, and hence power developed. Valve timings and valve port flow areas affect power, especially if both inlet and exhaust valves are open at the same time, during a "valve overlap" phase. Further, they affect the exhaust emission composition, particularly with respect to unburnt hydrocarbons.
More recently it has been known to employ two inlet and two exhaust valves per cylinder in order to achieve good cylinder scavenging without recourse to a "valve overiap" phase, but high speed performance is inevitably compromised to some extent.
It is desired, in particular, that the composition of exhaust emissions has a low proportion of unburnt hydrocarbons when the engine is operating at low and medium speeds, and at low loads, and it comprises an object of the present invention to provide an engine of a novel construction whereby this requirement is obtained in an advantageous way.
According to the present invention a four stroke internal combustion engine has four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, leading individually to each of the inlet valves is a bifurcated part of the inlet port, characterised in that leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and the arrangement is such that the settings of the two flow control valves are changed in unison in response to variations of engine conditions, and
such that the two flow control valves are fully closed when the engine is operating at least at a particular lo or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed.
According to another aspect the present invention relates to a method of operating a four stroke internal combustion engine having four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, and the method is characterised by operating an engine having a bifurcated part of the inlet port leading individually to each of the inlet valves, and leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and in the method the settings or the two flow control are changed in unison in response to variations of engine conditions, and such that the two
- k -
flow control valves are fully closed when the engine is operating at least at a particular low or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed.
The present invention will now be described by way of example with reference to the accompanying drawings, in which
Figure 1 is a valve event diagram for an engine and suitable for low and medium operating speeds of the engine,
Figure 2 corresponds to Figure 1, but is for higher operating speeds of the engine,
Figure 3 shows a typical valve train mechanism, and the associated part of the cylinder head, associated with a cylinder of an embodiment of a four stroke internal combustion engine, having four poppet valves per cylinder, and in accordance with the present invention, and
Figure is a representation, generally in plan, of the part of the cylinder head shown in Figure 3, together with the inlet and exhaust ports associated with the four poppet valves.
Valve timings to suit a typical engine so that there are desirably low unburnt hydrocarbon emissions, and required tractability , at low and medium engine speeds are indicated by the valve event diagram of Figure 1. As the piston reciprocates, and the engine crankshaft is rotated thereby, and as indicated in Figure 1 at A, the inlet valve opens with the crankshaft 5 degrees before the piston reaches, its top dead centre, (TDC), position. The inlet valve closes, as indicated at B, at 40 degrees after the piston has passed its bottom dead centre, (BDC), position. The exhaust valve opens 50 degrees before BDC as indicated at C; and closes 5 degrees after BDC as indicated at D. There are only short "valve overlap" phases when both the inlet and exhaust valves are open, and curtailed timings due to the suppression of intake and exhaust pressure wave interactions.
Valve timings to suit the same engine so that there is the required tractability, at higher engine speeds, are indicated by the valve event diagram of Figure 2. As indicated at A , the inlet valve opens at 45 degrees before TDC; and, as indicated at B , the inlet valve closes at 65 degrees after BDC. As indicated at C , the exhaust valve opens at 60 degrees before BDC; and as indicated at D , the exhaust valve closes at 35 degrees after TDC. There are relatively longer "valve overlap" phases, and late inlet valve closure, compared with the
valve timings of Figure 1, commensurate with inertia wave effects in both the intake and exhaust systems.
The part of a throttled gasoline, four stroke, internal combustion engine shown in Figures 3 and 4 includes the cylinder head 2, an inlet camshaft 4 actuating first and second inlet valves, respectively, 6 and 7, via the usual tappet and spring system, and an exhaust camshaft 8 actuating first and second exhaust valves, respectively, 10 and 11, via the usual tappet and spring system. Gf the two inlet valves 6 and 7, and the two exhaust valves 10 and 11, only the face of the second inlet valve 7, and only the face of the second exhaust valve 11, are illustrated in Figure 1. The cam associated with the first inlet valve 6 is indicated at 14, and the cam associated with the first exhaust valve 10 is indicated at 16. Unillustrated cams are associated with the second inlet valve 7, and the second exhaust valve 11.
The illustrated cams 14 and 16 have timing profiles suited to low and medium engine speeds, the corresponding inlet and exhaust valve timings, respectively, for the illustrated first inlet valve 6, and the illustrated first exhaust valve 10, being somewhat similar to those indicated on the valve event diagram of Figure 1. The unillustrated cams for the second xnlet valve ana tne second exhaust valve 11 have timing profiles suited to higher engine speeds, the corresponding inlet and exhaust
- /
valve timings being similar to those indicated on the valve event diagram of Figure 2.
Indicated in Figure 3 is the common inlet port 20 provided in the cylinder head 2 for the two inlet valves 6 and 7. Adjacent to the inlet valves 6 and 7 the inlet port 20 is bifurcated by a partition 22, so that the port is split into two passages each leading individually to an inlet valve. Similarly, a common exhaust port 24 is provided in the cylinder head 2 for the two exhaust valves 10 and 11. Adjacent to the exhaust valves 10 and 11 the exhaust port is bifurcated by a partition 26, so that the port is split into two passages each leading individually from an exhaust valve.
Figure 4 is a representation, generally in plan, of the part of the cylinder head 2 shown in Figure 3. Figure 4 sh ws more clearl than Figure 3 both the arrangement of the two inlet valves 6 and 7, and the two exhaust valves 10 and 11, in relation to the cylinder; and also the arrangement of the inlet port 20 and the exhaust port 24 in relation to these valves.
In accordance with the present invention, and shown in Figure 4, there is provided in the passage 54 of the bifurcated part of tne inlet port 20 leading to the second inlet valve 7, a pivotally mounted, plate type, flow control valve 56; and there is provided in the passage 58
of the bifurcated part of the exhaust port 24 leading from the second exhaust valve 11, a second, pivotally mounted, plate type, flow control valve 60. The flow control valves 56 and 60 are linked together, for example, by mechanical means, and the settings thereof are controlled by πovements of a linkage indicated generally at 62. Movements of the linkage 62, and corresponding changes of the settings of the flow control valves 56 and 60, are under the control of any suitable construction of actuator, indicated generally at 64, operatively coupled to a known form of electronic engine management controller (not shown), and subject to operation in accordance with pre-programmed data. The linkage may have any convenient form. Instead of being coupled to an electronic engine management controller, the actuator may be coupled to the engine throttle (not shown).
In the operation of the engine the inlet and exhaust crankshafts 4 and 8 rotate, respectively, the two inlet cams and the two exhaust cams at half engine crankshaft speed, and all the valves 6, 7, 10, and 11 open and close at the timings determined by their respective cams.
When the plate valves 56 and 60 are closed, the flow of intake charge through the second inlet valve 7, and the flow of exnaust gases through the second exhaust valve 11, are cut off. In response to the pressure drop caused across - the inlet valves by the piston (not shown) moving
on its intake stroke in the co-operating cylinder, the intake charge is accelerated more strongly in the unthrottled passage 66 of the bifurcated part of the inlet port 20. This results in a high gas velocity in the cylinder; and due to the offset of the unthrottled passage 66 and the first inlet valve 6 from the cylinder centre line, there is a strong swirl effect imparted to the inflowing charge in the cylinder. This swirl effect aids in-cylinder turbulence, and enables the ignition advance for optimum combustion to be reduced advantageously, giving good engine thermal efficiency, torque, and fuel consumption.
A similar effect is noted when the piston is moving on its exhaust stroke. The first exhaust valve 10 provides an adequate exhaust time-area integral for blowdown, whilst he absence of "valve overlap" minimises the risk of undesired h drocarbon emissions from the engine due to unburnt charge being sucked directly from the passage 66 of t e bifurcated part of the inlet port 20 into the passage 68 of the bifurcated part of the exhaust port 24.
When the engine's performance corresponds to a predetermined point on the speed/load graph associated therewith, the actuator 64 causes the linkage 62 to be moved, and tne settings of tne flow control valves 56 and 60 are changed so that these valves are fully open. Intake cnarge is no admitted to the cylinder through both the
first and second inlet valves 6 and 7 when these valves are open; and exhaust gases are expelled from the cylinder through both the first and second exhaust valves 10 and
Since the second inlet valve 7 is caused to be open in angular advance of the first inlet valve 6, the gas in the non-bifurcated part of the inlet port 20 accelerates before the first inlet valve 6 opens. Thus, when the first inlet valve 6 does open the mass flow through this valve is greater than otherwise would be the case.
Further, the potential for exploiting the extraction effect of exhaust pressure waves by the effect of the delayed closing of the second exhaust valve 11 is not detracted from by the normal operation of the first exhaust valve 10.
The plate valve 56 on the inlet side of the engine ma be of steel, brass, aluminium, or of a suitable plastics material. The plate valve 60 on the exhaust side of the engine is required to be of a heat resistant steel, or of a ceramic.
Instead of being snapped open to impart a step change in the engine torque curve beyond a certain range of load/speed/throttle setting, the arrangement may be such
hat the plate valves are actuated progressively above a predetermined percentage opening.
The inlet and exhaust valves may be actuated by push rod and/or rocker means if there are provided cams individually actuating each valve.
The plate valves controlling the flow to the second inlet valve, and from the second exhaust valve, could be slideably mounted instead of being pivotably moveable.
The cams actuating the poppet valves each may be mounted individually on a camshaft.
The mechanical linkage may be replaced by any suitable form of actuator; and separate actuators may be provided fcr the two plate valves. In any such arrangement the settings of the two plate valves are changed in the same c cle of the engines, and hence are considered as being changed in unison.
The terms low and medium engine speeds conveniently refer to engine speeds having the mean piston velocity up to 7 metres per second, for engines having bore to stroke ratios in the range 0.8:1 to 1.1:1. The term higher engine speeds conveniently refers to engine speeds having the mean piston velocity in the range 7 to 18 metres per second, with normal bore to stroke ratios as referred to
in the preceding sentence, and a specific output in the range 50 to 90 Kilowatts per litre of swept cylinder volume for naturally aspirated engines.
Claims
1. A four stroke internal combustion engine has four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, characterised in that leading individually to each of the inlet valves is a bifurcated part of the inlet port, and leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and the arrangement is such that the settings of the two flow control valves are changed in unison in response to variations of engine conditions, and such that the two flow control valves are fully closed hen the engine is operating at least at a particular low or medium speed, and tne two flow control valves are fully open when the engine is operating at least at a particular higher speed.
2. An engine as claimed in claim 1 characterised in that the arrangement is such that the settings of the two flow control valves are changed by an actuator operatively coupled to an electronic engine management controller.
3. An engine as claimed in claim 1 characterised in that the arrangement is such that the settings of the two flow control valves are changed by an actuator operatively coupled to the engine throttle.
An engine as claimed in claim 1, or claim 2, or claim 3, characterised by being arranged such that the second inlet valve is caused to be open in angular advance of the first inlet valve.
5. An engine as claimed in any one of the preceding claims, characterised by being arranged such that the second exhaust valve is caused to close after the closure of the first exhaust valve.
6. A method of operating a four stroke internal combustion engine having four poppet valves per cylinder, comprising first and second inlet valves, and first and second exhaust valves, and the method is characterised by operating an engine having a bifurcated part of the inlet port leading individually to each of the inlet valves, and leading
individually from each of the exhaust valves is a bifurcated part of the exhaust port, the first inlet valve and the first exhaust valve are actuated individually by cams having timing profiles suited to low and medium engine speeds, the second inlet valve and the second exhaust valve are actuated individually by cams having timing profiles suited to higher engine speeds, included in the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve is an exhaust flow control valve, and in the method the settings of the two flow control valves are changed in unison in response to variations of engine conditions, and such that the two flow control valves are fully closed when the engine is operating at least at a particular low or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed.
7. A method as claimed in claim 6 characterised in that the settings of the two flow control valves are changed so that the valves change from being fully open to being fully closed at a particular engine setting.
8. A method as claimed in claim 6 or claim 7, characterised in that the settings of the two flow control valves are changed so that the valves change from being fully closed to being fully open at a particular engine setting.
9. A method as claimed in claim 6, characterised in that the setting of the two flow control valves are changed so that the valves change from being fully open to being fully closed over a particular range cf engine settings.
10. A method as claimed in claim 6, characterised in that the setting of the two flow control valves are changed so that the valves change from being fully closed to being fully open over a particular range of engine settings.
AMENDED CLAIMS
[received by the International Bureau on 6 July 1992 (06.07.92); original claim 1 amended; other claims unchanged (4 pages)]
A four stroke internal combustion engine has four poppet valves per cylinder, the engine including an inlet camshaft actuating first and second inlet valves, and an exhaust camshaft actuating first and second exhaust valves, leading individually to each of the inlet valves is a bifurcated part of the inlet port, and leading individually from each of the exhaust valves is a bifurcated part cf the exnaust port, characterised by including m the passage of the bifurcated part of the inlet port leading to the second inlet valve is an inlet flow control valve, and including in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve an exhaust flow control valve, the arrangement being such that the settings of the two flow control valves are changed in unison m response to variations of engine conditions, sucn that the two flow control valves are fully closed when the engine is operating at least at a particular low or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed, and the first inlet valve and the first exhaust valve being actuated individually by cams having timing profiles suited to low and medium engine speeds, including causing botn tne first inlet valve and the first exnaust valve to oe open for a first period, and the second inlet valve and the
second exhaust valve being actuated individually by cams having timing profiles suited to higher engine speeds, ncluding causing both the second inlet valve and tne second exhaust valve to be open for a second period longer than said first period.
2. An engine as claimed in claim 1 characterised in that the arrangement is such that the settings of the two flow control valves are changed by an actuator operatively coupled to an electronic engine management controller.
2. An engine as claimed in claim 1 characterised in that the arrangement is such that the settings of the two flow control valves are changed by an actuator operatively coupled to the engine throttle.
4. An engine as claimed in claim 1, or claim 2, cr claim 2, cnaracterised by being arranged such that the second inlet valve is caused to be open in angular advance of the first inlet valve.
Ξ. An engine as claimed in any one of the preceding claims, characterised by being arranged such that the second exhaust valve is caused to close after the closure of the first exhaust valve.
6. A method of operating a four stroke internal comDustion engine having four poppet valves per
cylinder, the engine including an inlet camshaft actuating first and second inlet valves, and exhaust camshaft actuating first and second exhaust valves, a bifurcated part of the inlet port leading individually to each of the inlet valves, and leading individually from each of the exhaust valves is a bifurcated part of the exhaust port, and the method being characterised by the combination of controlling the inlet flow to the cylinder by a control valve included in the passage of the bifurcated part of the inlet port leading to the second inlet valve, controlling the exhaust flow from the cylinder by a control valve included in the passage of the bifurcated part of the exhaust port leading from the second exhaust valve, the settings of the two flow control valves being changed in unison in response to variations of engine conditions, such that the two flow control valves are fully closed when the engine is operating at least at a particular low or medium speed, and the two flow control valves are fully open when the engine is operating at least at a particular higher speed, and the first inlet valve and the first exhaust valve being actuated individually by cams having timing profiles suite to low and medium engine speeds, including causing both the first inlet valve ar.d first exhaust valve to be c~ r. for a first period, and the second inlet valve and the second exhaust valve being actuated individually by cams having timing profiles suited to higher engine
speeds, including causing both the second inlet valve and the second exhaust valve to be open for a second period longer than said first period.
7. A method as claimed in claim 6 characterised in that the settings of the two flow control valves are changed so that the valves change from being fully open to being fully closed at a particular engine setting.
STATEMENT UNDER ARTICLE 19
Substantially the same amendment has been to both independent claim 1 directed to an engine, and to independent claim 6 directed to a method of operating an engine.
Two features described in the specification, but not explicitly claimed previously, have been inserted into both claims.
In the precharacterising part of both claims reference is now made to the inlet camshaft and to the exhaust camshaft, the presence of these components in the claimed engine being described in the specification, and being implicit for a skilled reader.
Further, in either claim the references to an inlet flow control valve in a bifurcated part of the inlet port, and to an exhaust flow control valve in a bifurcated part of the exhaust port, have been transferred to the initial portion of the pre-characterising part of the claim. In addition, the pre-characterising part of either claim is directed to the combination of the inlet and exhaust flow control valves; with the inlet and exhaust valve opening overlap being shorter for the first inlet and exhaust valves than for the second inlet and exhaust valves, all these latter valves being operable at high engine speeds, but only the first such valves being operable at low and medium engine speeds. In this manner, the claimed invention is now set out by a more explicit statement than before.
Because of the prior art cited in the search report it is believed that the claimed invention should be clarified, and restricted in ambit, by the statement of the combination of the characterising part of either new claim.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9103634.3 | 1991-02-21 | ||
GB9103634A GB2253008A (en) | 1991-02-21 | 1991-02-21 | Charge control in four valve i.c.engines |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1992014923A1 true WO1992014923A1 (en) | 1992-09-03 |
Family
ID=10690341
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1992/000291 WO1992014923A1 (en) | 1991-02-21 | 1992-02-19 | Internal combustion engines |
Country Status (2)
Country | Link |
---|---|
GB (1) | GB2253008A (en) |
WO (1) | WO1992014923A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2328975A (en) * | 1997-09-03 | 1999-03-10 | Ford Global Tech Inc | Combustion engine with internal EGR |
US6263854B1 (en) * | 1999-07-22 | 2001-07-24 | Caterpillar Inc. | Cylinder head for an internal combustion engine |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2063362A (en) * | 1979-11-23 | 1981-06-03 | British Leyland Cars Ltd | I.C. engine cylinder head |
GB2087975A (en) * | 1980-11-25 | 1982-06-03 | Opel Adam Ag | Air fuel aspirating four-stroke internal combustion engines |
US4512311A (en) * | 1980-10-20 | 1985-04-23 | Yamaha Hatsudoki Kabushiki Kaisha | Intake control system for multi-valve type internal combustion engine |
JPS6114435A (en) * | 1984-06-29 | 1986-01-22 | Mazda Motor Corp | Engine exhaust device |
US4627396A (en) * | 1981-03-12 | 1986-12-09 | Yamaha Hatsudoki Kabushiki Kaisha | Intake control system of engine |
JPS6432059A (en) * | 1987-07-27 | 1989-02-02 | Mazda Motor | Combustion controller for engine |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB682628A (en) * | 1949-07-20 | 1952-11-12 | Carl Friedrich Wilhelm Borgwar | Improvements in or relating to induction systems for internal combustion engines |
JPS595769B2 (en) * | 1978-10-06 | 1984-02-07 | 本田技研工業株式会社 | High output engine |
DE3306355A1 (en) * | 1983-02-24 | 1984-08-30 | Ford-Werke AG, 5000 Köln | INTERNAL COMBUSTION ENGINE WITH VARIABLE CHANGE-OF-CHARGE TIMES |
US4703734A (en) * | 1985-03-06 | 1987-11-03 | Nissan Motor Co., Ltd. | Multi-valve internal combustion engine |
US4875455A (en) * | 1987-04-28 | 1989-10-24 | Mazda Motor Corporation | Automobile exhaust gas recirculating system |
-
1991
- 1991-02-21 GB GB9103634A patent/GB2253008A/en not_active Withdrawn
-
1992
- 1992-02-19 WO PCT/GB1992/000291 patent/WO1992014923A1/en not_active Application Discontinuation
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2063362A (en) * | 1979-11-23 | 1981-06-03 | British Leyland Cars Ltd | I.C. engine cylinder head |
US4512311A (en) * | 1980-10-20 | 1985-04-23 | Yamaha Hatsudoki Kabushiki Kaisha | Intake control system for multi-valve type internal combustion engine |
GB2087975A (en) * | 1980-11-25 | 1982-06-03 | Opel Adam Ag | Air fuel aspirating four-stroke internal combustion engines |
US4627396A (en) * | 1981-03-12 | 1986-12-09 | Yamaha Hatsudoki Kabushiki Kaisha | Intake control system of engine |
JPS6114435A (en) * | 1984-06-29 | 1986-01-22 | Mazda Motor Corp | Engine exhaust device |
JPS6432059A (en) * | 1987-07-27 | 1989-02-02 | Mazda Motor | Combustion controller for engine |
Non-Patent Citations (2)
Title |
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PATENT ABSTRACTS OF JAPAN vol. 10, no. 159 (M-486)7 June 1986 & JP,A,61 014 435 ( MAZDA KK ) 22 January 1986 * |
PATENT ABSTRACTS OF JAPAN vol. 13, no. 214 (M-827)18 May 1989 & JP,A,1 032 059 ( MAZDA MOTOR CORP. ) 2 February 1989 * |
Also Published As
Publication number | Publication date |
---|---|
GB2253008A (en) | 1992-08-26 |
GB9103634D0 (en) | 1991-04-10 |
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