Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/08—Other arrangements or adaptations of exhaust conduits
  • F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/30—Arrangements for supply of additional air
  • F01N3/34—Arrangements for supply of additional air using air conduits or jet air pumps, e.g. near the engine exhaust port
• • 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
  • F02F1/4264—Shape or arrangement of intake or exhaust channels in cylinder heads of exhaust channels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2340/00—Dimensional characteristics of the exhaust system, e.g. length, diameter or volume of the apparatus; Spatial arrangements of exhaust apparatuses
  • F01N2340/02—Dimensional characteristics of the exhaust system, e.g. length, diameter or volume of the apparatus; Spatial arrangements of exhaust apparatuses characterised by the distance of the apparatus to the engine, or the distance between two exhaust treating apparatuses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2590/00—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines
  • F01N2590/04—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines for motorcycles
• • 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
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• • 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

• the present subject matter relates to an internal combustion engine for a two-or three-wheeled vehicle and more particularly, relates to an exhaust system of the internal combustion engine.
• an internal combustion (IC) engine in a motor vehicle, includes an intake system for supplying air-fuel to the IC engine.
• An exhaust system connects the internal combustion engine to a muffler of the vehicle.
• the exhaust gas generated in a combustion chamber of the IC engine is discharged to the atmosphere.
• an exhaust port of the IC engine is connected to an exhaust pipe of the exhaust system enabling discharge of the combusted gases to the atmosphere.
• the position of the exhaust port is subject to specific orientation of mounting of the engine on to the vehicle which has layout & packaging challenges associated with it.
• it is important to position a catalytic converter as close as possible to the exhaust port.
• optimally positioning the catalytic converter also becomes a challenge, which is mainly due to the layout constraint of the motor vehicle.
• FIG. 1 depicts a right-side view of an exemplary two-wheeled vehicle, in accordance with an embodiment of the present subject matter.
• Fig. 2 illustrates a right-side view of an internal combustion engine including its exhaust system, in accordance with the embodiment as depicted in Fig. 1.
• FIG. 3 (a) illustrates a cross-sectional front view of a cylinder head assembly of the internal combustion engine, in accordance with an implementation of the present subject matter.
• FIG. 3 (b) illustrates a cross-sectional view of exhaust port taken at the section Z-Z of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• FIG. 3 (c) illustrates a cross-sectional view of exhaust port taken at the section XX-XX of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• Fig. 3 (d) illustrates a cross-sectional view of exhaust port taken at the section YY-YY of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• FIG. 4 (a) illustrates a cross-sectional view of the exhaust system of the internal combustion engine, in accordance with a first embodiment of the present subject matter.
• FIG. 4 (b) illustrates a cross-sectional view of the exhaust system of the internal combustion engine, in accordance with a second embodiment of the present subject matter.
• FIG. 5 illustrates a cross-sectional view of the exhaust port of the internal combustion engine, in accordance with another embodiment of the present subject matter.
• Fig. 6 (a) depicts a characteristic curve of exhaust gas temperature in the exhaust system of the internal combustion engine, in accordance with an embodiment of the present subject matter.
• Fig. 6 (b) illustrates a cross-sectional view of a conventional exhaust system depicting the intersection of the exhaust port and the exhaust pipe.
• Fig. 6 (c) illustrates a cross-sectional view of the exhaust system depicting the intersection of the exhaust port and the exhaust pipe, in accordance with an embodiment of the present subject matter.
• Fig. 7 depicts a characteristic curve of engine torque of the internal combustion engine, in accordance with an embodiment of the present subject matter.
• FIG. 8 depicts a method of manufacturing of the cylinder head in accordance with an embodiment of the present subject matter.
• FIG. 9 illustrates a cross-sectional view of the cylinder head assembly of the present subject matter depicting an intake port passage and an exhaust port passage with an integrated sand core disposed therein.
• the internal combustion engine having 4-stroke cycle is popular.
• the 4-stroke cycle starts with an intake stroke and ends at an exhaust stroke. Due to combustion of air-fuel mixture that gets compressed during compression stroke and then combusted thereby resulting in the power stroke.
• the combusted gases are transmitted to the exhaust system from the cylinder head.
• the performance of the vehicle depends on various parameters that include the air-fuel mixture that is supplied during intake.
• the performance of the engine is also dependent on the nature of the exhaust gases being transmitted out. For example, contaminants in the combustion chamber created during combustion process affect lubrication properties in the combustion chamber. This in turn, increases friction, which affects the performance of the vehicle.
• an upstream end of the exhaust pipe is connected to the exhaust port of the cylinder head.
• the muffler is either disposed towards one lateral side of the vehicle or is disposed along a vehicle center & typically downstream of the engine with exhaust pipe being routed between the two so as to enable discharge of exhaust gases towards downstream end of the vehicle.
• the upstream end of the exhaust pipe being connected to the cylinder head assembly includes a bend portion to connect to the exhaust port, which is generally disposed either on a front facing side of the cylinder head or on a downward facing side of the cylinder head. This typically requires complex routing of the exhaust pipe with a bent portion.
• any gaps arising at the joint interface with the cylinder head assembly can lead to undesirable leakage, performance loss, noise, contamination & poor durability cum life of the entire power train system as a whole.
• this bent portion further affects the flow of exhaust gas, therethrough, which affects the performance of the engine.
• presence of bent portion affects flow of exhaust gas creating resistance that adversely affects performance.
• the exhaust gas may result in undesirable exhaust noise.
• the structural strength of the exhaust pipe is low at the bent portion on the exhaust pipe since the bent portion undergoes wall thinning on the outward surface of the exhaust pipe at the bent portion. This can result in breakage or failure at the bent portion.
• the conventionally known cylinder heads are provided with one or more exhaust ports having a diameter or cross-sectional area that gradually increases from the valve seat to the port outlet.
• exhaust pipes have a construction with its end connecting the exhaust port flared out, i.e., the ends of the exhaust pipe joining the exhaust port region are flared out to be able to connect to the mounting flanges of the exhaust port.
• the diameter or cross-sectional area of the exhaust pipe at its joining face with the outlet of the exhaust port remains substantially lesser than the diameter or cross-sectional area of the outlet of the exhaust port.
• Typical exhaust systems having exhaust port whose diameter or cross- sectional area gradually increases up to the joining face with the exhaust pipe and the diameter or cross-sectional area of the exhaust pipe at the joining face being substantially lesser than the outlet diameter or cross-sectional area of the exhaust port, tends to reduce the velocity of the exhaust gases that reaches the one or more catalytic converters, which are disposed downstream in the exhaust pipe.
• the expanded outer cross-section of the exhaust port and the corresponding joining face of the exhaust pipe having a diameter or cross- sectional area substantially lesser than the outlet diameter or cross-sectional area of the exhaust port tends to increase the pressure and flow rate, but results in reducing the velocity of the exhaust gases.
• the reduction in velocity of the exhaust gases mean the temperature of the exhaust gases reaching the one or more catalytic converters also drops, which in most cases affects the early light-off of the catalytic converter.
• the exhaust port was configured to include a combination of an inwardly swollen region and an outer venturi unit.
• the present subject matter is aimed at increasing the velocity of the exhaust gases, for which a pressure drop is created, the impending loss of flow rate is compensated by the profile of the exhaust port, the chamfer angle of the reduced cross-section and the length of the land provided at the outlet face of the exhaust port of the present subject matter.
• the present subject matter provides an exhaust system for an internal combustion engine including an exhaust system that is capable of improving the performance of the engine at specific operating points.
• the present subject matter ensures that the problems faced in the existing art with respect to flaring of the exhaust pipe, which results in lack of consistency with respect to geometric accuracy of the interface components that prevents achieving a leak proof system, are overcome.
• the present subject matter is aimed at achieving desired consistency of design of the exhaust system by largely reducing the variation in design.
• the present subject matter provides an exhaust system, in which the flow characteristics are transferred from the exhaust pipe and incorporated in the exhaust port, without compromising on the torque and power requirement of the engine.
• the present subject matter provides increase in exhaust gas velocity for achieving early light-off of catalytic converters provided downstream of the exhaust pipe, especially in its cold phase.
• the present subject matter provides an internal combustion engine for a two-or-three-wheeled vehicle.
• the present subject matter provides a four-stroke internal combustion engine.
• the present subject matter provides a four-stroke internal combustion engine having a single cylinder.
• the internal combustion engine typically includes at least one cylinder head.
• the at least one cylinder head includes at least one intake port.
• a combustion chamber that receives intake charge from a fuel supply device through at least one intake port is provided.
• the cylinder head is also provided with at least one exhaust port capable of expelling combusted gases from the combustion chamber to atmosphere through an exhaust pipe of the vehicle.
• the engine assembly consists of at least one spark plug.
• the at least one exhaust port has an upstream portion adjoining the combustion chamber and a downstream portion adjoining an inlet opening of the exhaust pipe.
• the downstream portion of the exhaust port has a first diameter or cross-sectional area substantially equal to a second diameter or cross-sectional area of the inlet opening of the exhaust pipe at a joining face of the exhaust pipe with the exhaust port.
• the exhaust port of the present subject matter has an intermediate portion disposed adjacent to the downstream portion. Further, the second diameter or cross-sectional area of the inlet opening of the exhaust pipe is approximately 1.10 to 1.20 times the first diameter or cross-sectional area of the downstream portion of the exhaust port. In one implementation, the exhaust port has a first region connecting an upstream portion of the exhaust port and the intermediate portion and a second region connecting the downstream portion and the intermediate portion.
• the intermediate portion has a specific profile design of the exhaust port, for example, a reduced cross-section provided with a predetermined angle ranging from 3° to 20°.
• the reduced cross-section has an upstream diameter or cross-sectional area substantially greater than a downstream diameter or cross-sectional area.
• the second region of the exhaust port has a length ranging approximately between 2.5 mm to 4 mm, while the first diameter ranges approximately between 15 mm to 25 mm.
• the exhaust pipe includes at least one catalytic converter unit disposed at a predetermined distance from the exhaust port, for example, at a distance of approximately between 175 mm to 300 mm from the reduced cross-section of the exhaust port.
• the exhaust pipe also includes an oxygen sensor disposed between the exhaust port and the catalytic converter unit.
• the oxygen sensor is disposed substantially closer to the catalytic converter unit, for example at a distance of approximately between 15 mm to 20 mm upstream of the catalytic converter unit.
• the intermediate portion of the exhaust port receives at least one secondary air injection outlet conduit and, in another embodiment, the exhaust port is provided with an exhaust gas recirculation conduit instead of at least one secondary air injection outlet conduit.
• the present subject matter provides an internal combustion engine for a two-or-three-wheeled vehicle.
• the internal combustion engine typically includes at least one cylinder head.
• the at least one cylinder head includes at least one intake port.
• a combustion chamber that receives intake charge from a fuel supply device through at least one intake port is provided.
• the cylinder head is also provided with at least one exhaust port capable of expelling combusted gases from the combustion chamber to atmosphere through an exhaust pipe of the vehicle.
• the at least one exhaust port has an upstream portion adjoining the combustion chamber and a downstream portion adjoining an inlet opening of the exhaust pipe.
• the downstream portion of the exhaust port has a first diameter or cross-sectional area substantially lesser than a second diameter or cross-sectional area of the inlet opening of the exhaust pipe at a joining face of the exhaust pipe with the exhaust port.
• the second diameter or cross-sectional area of the inlet opening of the exhaust pipe is approximately 1.2 to 1.5 times the first diameter or cross-sectional area of the downstream portion of the exhaust port.
• the present subject matter provides an internal combustion engine for a two-or-three-wheeled vehicle.
• the internal combustion engine typically includes at least one cylinder head.
• the at least one cylinder head includes at least one intake port.
• a combustion chamber that receives intake charge from a fuel supply device through at least one intake port is provided.
• the cylinder head is also provided with at least one exhaust port capable of expelling combusted gases from the combustion chamber to atmosphere through an exhaust pipe of the vehicle.
• the at least one exhaust port has an upstream portion adjoining the combustion chamber and a downstream portion adjoining an inlet opening of the exhaust pipe.
• the downstream portion of the exhaust port has a first diameter or cross-sectional area substantially lesser than a second diameter or cross-sectional area of the inlet opening of the exhaust pipe at a joining face of the exhaust pipe with the exhaust port.
• the exhaust port has an intermediate portion disposed adjacent to the downstream portion.
• the exhaust port has a first region connecting the upstream portion of the exhaust port and the intermediate portion and a second region connecting the downstream portion and the intermediate portion.
• the intermediate portion has a reduced cross-section provided with a predetermined angle ranging from 3° to 20°.
• the present subject matter also provides a method of manufacturing a cylinder head of an internal combustion engine having at least one exhaust port.
• the method includes the steps of forming an integrated sand core having a stepped diameter or cross-sectional area before at least a predetermined distance ranging between 6 mm to 12 mm from a downstream portion of the exhaust port. This step is followed by forming a locating element beyond the stepped diameter or cross-sectional area of the integrated sand core, and receiving the locating element of the integrated sand core by a metal core.
• the forming process described above includes integral forming of the at least one exhaust port along with at least one intake port and a combustion chamber. Further, the method involves the step of low pressure die casting (LPDC).
• LPDC low pressure die casting
• the present subject matter provides a cylinder head in which the exhaust port is provided with a diameter or cross-sectional area that is substantially closer to the diameter or cross-sectional area of the exhaust pipe, but not perfectly matching to that of the diameter or cross-sectional area of the outlet portion of the exhaust port.
• the present subject matter involves creating a stepped portion in the casting of the exhaust port. The modification is done at the exit point of the port for a width of approximately 6 ⁇ 12 mm towards the end of the port.
• the length of the second region of the exhaust port that ranges approximately between 2.5 mm to 4 mm ensures that the minimum land required for mounting the exhaust pipe to the port is maintained after machining over and above any production variations that may arise.
• the lack of consistency of the sheet metal flaring process is compensated by the casting process involving forming of integrated sand core for the exhaust port, which achieves the desired consistency, thereby reducing any variations in the process with a tolerance of ⁇ 0.2 mm of diameter or correspondingly to the cross-sectional area.
• the casting process of the cylinder head involving forming of sand core enables achieving required surface finish. Taking any manufacturing variations into consideration, the present subject matter achieves a ratio of diameter or cross-sectional area of the outlet of the portion of the port to that of the inlet of the exhaust pipe diameter or cross- sectional area ranging from 1:1 to 1:1.3, which helps in achieving the desired improvement in efficiency of catalytic converter without compromising on the engine performance.
• the cross-sectional area of the port at the valve seat, or the corresponding diameter of the port at the valve seat is close to 20 mm.
• the diameter of the port increases from the port near the valve seat till it reaches the port intermediate portion, after which, it reduces at the outlet portion of the exhaust port. This helps in achieving the desired restriction in outlet flow, which increases the exhaust gas velocity.
• increase in gas velocity is directly proportional to area of the outlet region of the exhaust port achieved as a result of reduction in diameter or cross-sectional area of the outlet portion of the exhaust port as a result of the reduced cross-section before the outlet portion of the exhaust port.
• a nozzle action caused due to the reduced cross-section provided towards the end of the exhaust port of the present subject matter helps to increase the velocity of the exhaust gases. This phenomenon supports in quickly moving the exhaust gases to the CAT at a higher volumetric rate without resulting in drop in temperature of the exhaust gases. Thus, faster light-off of the CAT is achieved.
• the nozzle action caused due to the reduced cross-section provided towards the end of the exhaust port quickly transfers the exhaust gases from exhaust port to the exhaust pipe and through to the muffler towards the end of the exhaust pipe. This results in quick removal of the diluted gases in the combustion chamber for the next cycle of combustion.
• the volumetric efficiency is enhanced. This also helps in better breathing and improving low end torque of the engine. This in turn, increases the performance of the engine at the desired operating points.
• the generally known exhaust systems are provided with secondary air injection (SAI) outlet at the exhaust ports to improve conversion of emission gases such as NOx, HC and CO.
• SAI secondary air injection
• providing a SAI outlet at the reduced cross-section of the exhaust port helps in improving suction due to the vacuum created at the reduced cross-section. Further, this also ensures that more oxygen is made available at the catalytic converter disposed downstream of the exhaust pipe. This enables improving the catalytic converter’s efficiency and the performance of the engine.
• Fig. 1 illustrates a two-wheeled vehicle (100), which is an exemplary motor vehicle, having an IC engine (101) that is vertically disposed.
• the IC engine (101) is a single-cylinder type IC engine.
• the two-wheeled vehicle comprises a front wheel (110), a rear wheel (103), a frame member (102) shown schematically, a fuel tank (121) and seat (106).
• the frame member (102) includes a head pipe (111), a main tube (not shown), a down tube (not shown), and seat rails (not shown).
• the head pipe (111) supports a steering shaft (not shown) and two telescopic front suspension(s) (114) (only one shown) is attached to the steering shaft through a lower bracket (not shown).
• the two telescopic front suspension(s) (114) supports the front wheel (110).
• the upper portion of the front wheel (110) is covered by a front fender (115) mounted to the lower portion of the telescopic front suspension (114) at the end of the steering shaft.
• a handlebar (108) is fixed to upper bracket (not shown) and can rotate to both sides.
• a head light (109), a visor guard (not shown) and instrument cluster (not shown) is arranged on an upper portion of the head pipe (111).
• the down tube may be located in front of the IC engine (101) and extends slantingly downward from head pipe (111).
• the main tube is located above the IC engine (101) and extends rearward from head pipe (111).
• the IC engine (101) is mounted at the front by the down tube and connects the rear of the IC engine (101) at the rear portion of the main tube.
• a fuel tank (121) is mounted on the horizontal portion of the main tube (112).
• Seat rails are joined to main tube and extend rearward to support a seat (106).
• a rear swing arm (not shown) is connected to the frame member (102) to swing vertically, and a rear wheel (103) is connected to rear end of the rear swing arm (118).
• the rear swing arm is supported by a mono rear suspension (117) (as illustrated in the present embodiment) or two suspensions on either side of the two-wheeled vehicle.
• a tail light unit (not shown) is disposed at the end of the two-wheeled vehicle at the rear of the seat (106).
• a grab rail (105) is also provided on the rear of the seat rails.
• the rear wheel (103) arranged below seat (106) rotates by the driving force of the IC engine (101) transmitted through a chain drive (116) from the IC engine (101).
• a rear fender (127) is disposed above the rear wheel (103).
• Fig. 2 illustrates a right-side view of an internal combustion engine (101) including its exhaust system, in accordance with the embodiment as depicted in Fig. 1.
• the internal combustion engine (101) includes a cylinder head assembly (210) having a cylinder head (203) and a cylinder head cover (202) mounted atop the cylinder head (203).
• the internal combustion engine (101) is a single cylinder engine. More particularly, in one embodiment, the internal combustion engine (101) is a four-stroke internal combustion engine (101). In other alternative embodiment, the internal combustion engine (101) can include more than one cylinder head (203), or a plurality of cylinders.
• the cylinder head (203) of the present subject matter includes one or more ports (not shown in this figure).
• an exhaust port (not seen in this figure) of the internal combustion engine (101) enables exiting out the exhaust gases arising out of the combustion of the air-fuel mixture that occurs inside the combustion chamber (not shown) of the internal combustion engine (101).
• the gases exiting from the exhaust port are transported through an exhaust pipe (200) of the exhaust system of the internal combustion engine (101).
• the exhaust pipe (200) includes an inlet opening (201) which is connected to the exhaust port (not seen in this figure) of the internal combustion engine (101) for enabling smooth travel of the exiting exhaust gases.
• the cylinder head (203) of the internal combustion engine (101) is mounted atop a cylinder block (204), which together with crankcase (205) allows up and down movement of piston (not seen in this figure) of the internal combustion engine (101) for effecting optimal burning of the air- fuel mixture entering the combustion chamber.
• the exhaust pipe (200) of the present subject matter includes a first bend (208) adjacent to the inlet opening (201) and a second bend (209) farther from the first bend (208).
• the distance between the first bend (208) and the second bend (209) is defined by a vertical space available between the exhaust port and the ground clearance (C) shown in Fig 1 of the vehicle (100).
• the engine (101) includes at least one spark plug.
• the vehicle (100) is a saddle-ride type vehicle.
• the distance between the first bend (208) and the second bend (209) also depends, for example, on the diameter of the front wheel (not shown in this figure) and the rear wheel (not shown in this figure) and the wheel base between both the wheels.
• the exhaust pipe (200) includes at least one catalytic converter unit (206).
• the exhaust pipe (200) includes the at least one catalytic converter unit (206) substantially closer to the exhaust port of the cylinder head, in particular, the catalytic converter unit (206) is disposed between the first bend (208) and the second bend (209) of the exhaust pipe (200).
• the at least one catalytic converter unit (206) is a pre-catalytic converter or an auxiliary catalytic converter, which is provided upstream of a main catalytic converter in the exhaust system of the present subject matter.
• the main catalytic converter (not shown) is disposed within the muffler assembly (130) of the exhaust system of the present subject matter.
• the catalytic converter unit is disposed at a predetermined distance ranging approximately between 175 mm to 225 mm from a tapering section of said exhaust port (not seen in this figure).
• an oxygen sensor (207) is disposed substantially closer and upstream to the catalytic converter unit (206).
• the oxygen sensor (207) is disposed at a distance of about 15 mm to 20 mm upstream of the catalytic converter unit (206).
• Fig. 3 (a) illustrates a cross-sectional front view of the cylinder head assembly (210) of the internal combustion engine (101), in accordance with an implementation of the present subject matter.
• the cylinder head assembly (210) of the present subject matter has at least one intake port (301) that allows entry of air-fuel mixture into the combustion chamber (not shown).
• the intake port (301) is seated on an intake valve seat (302) at a juncture where an intake valve is disposed at an intake valve disposition opening (303) on the cylinder head assembly (210).
• the cylinder head assembly (210) includes at least one exhaust port (304) disposed on the other side of the intake port (301).
• the cylinder head assembly (210) can include more than one exhaust port (304).
• the exhaust port (304) is seated on an exhaust valve seat (305) of an exhaust valve (306).
• the portion of the exhaust port (304) that is near the exhaust valve seat (305) is an upstream portion (310).
• the diameter of the upstream portion (310) of the exhaust port (304) is approximately 20 mm.
• an intermediate portion (308) of the exhaust port (304) divides the exhaust port (304) into two regions, viz., a first region (311) that is more than three-fourth of the entire exhaust port (304) extending between the upstream portion (310) and the intermediate portion (308), and a second region (312) that is substantially equal to or lesser than one-fourth of the entire exhaust port (304) extending between the intermediate portion (308) and a downstream portion (307) of the exhaust port (304).
• the intermediate portion (308) is disposed at approximately a distance of 6 mm to 12 mm from the downstream portion (307) of the exhaust port (304).
• the intermediate portion (308) of the exhaust port (304) includes a reduced cross-section (309).
• the reduced cross-section (309) can include a tapering section.
• the reduced cross-section (309) is provided with a predetermined angle of 3° to 20°, for example a tapering angle ranging from 3° to 20°.
• the reduced cross- section (309) has an upstream diameter or cross-sectional area substantially greater than a downstream diameter or cross-sectional area.
• the length of the second region (312) of the exhaust port (304) ranges approximately between 2.5 mm to 4 mm, which ensures that the minimum land required for mounting the exhaust pipe (not seen in this figure) to the port (304) is maintained.
• the cylinder head assembly (210) includes two exhaust ports seated on two exhaust valve seats of two corresponding exhaust valves.
• both the exhaust ports converge upstream of the reduced cross-section (309), which thereafter adjoins the exhaust pipe in a similar manner as that of the previous embodiment containing the single exhaust port (304).
• Fig. 3 (b) illustrates a cross-sectional view of exhaust port (304) taken at the section Z-Z of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• Fig. 3 (c) illustrates a cross- sectional view of exhaust port (304) taken at the section XX-XX of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• Fig. 3 (d) illustrates a cross-sectional view of exhaust port (304) taken at the section YY-YY of the engine depicted in Fig. 3 (a), in accordance with one implementation of the present subject matter.
• the diameter or cross-sectional area of the exhaust port at the section Z-Z, which is at the first region of the exhaust port (304), as depicted in Fig. 3 (b) is substantially lesser than the diameter or cross-sectional area of the exhaust port at the section XX-XX, which is at the intermediate portion (308) of the exhaust port (304) as depicted in Fig. 3 (c).
• the diameter or cross-sectional area of the exhaust port (304) at the section XX-XX, which is at the intermediate portion (308) of the exhaust port (304) is greater than the diameter or cross-sectional area of the exhaust port at the section YY-YY, which is taken at the second region (312) of the exhaust port (304) as depicted in Fig.
• the profile of the exhaust port may be any non-circular cross section e.g. like a D-shape shown in Fig 3(b) & similarly the shape of the exhaust port at intermediate portion (308) as well as the downstream portion (307) can be a non circular cross section.
• the equivalent cross sectional area of the exhaust port at upstream portion (310) is greater than the equivalent cross sectional area of the exhaust port (304) at the intermediate portion (308)
• the cross-sectional area of the exhaust port (304) at the downstream portion (307) is lesser than the cross-sectional area of the intermediate portion (308).
• Fig. 4 (a) illustrates a cross-sectional view of a first exemplary exhaust system (400a) of the internal combustion engine (101), in accordance with an embodiment of the present subject matter.
• the first exemplary exhaust system (400a) includes a first cross-sectional area (APT) of the downstream portion (307) of the exhaust port (304) substantially equal to a second cross-sectional area (APE) of the inlet opening (201) of the exhaust pipe (200).
• APT first cross-sectional area
• APE second cross-sectional area
• the second cross-sectional area (APT) of the inlet opening (201) of the exhaust pipe (200) is approximately 1.10 to 1.20 times that of the first cross-sectional area (APT) of the downstream portion (307) of the exhaust port (304), i.e., both the cross-sectional areas are substantially equal, but does not match.
• the exhaust pipe (200) is attached to the exhaust port (304) by means of a mounting flange (401), which is comfortably mounted on to the mounting region of the downstream portion (307) of the exhaust port (304).
• the intermediate portion (308) of the exhaust port (304) includes a reduced cross-section (309).
• the reduced cross-section (309) can include a tapering cross-section (309-1).
• the tapering cross-section (309-1) is provided with a predetermined angle of 3° to 20°, for example a tapering angle ranging from 3° to 20°.
• Fig. 4 (b) illustrates a cross-sectional view of a second exemplary exhaust system (400b) of the internal combustion engine (101), in accordance with an embodiment of the present subject matter.
• the second exemplary exhaust system (400b) includes a first cross-sectional area (Ap T) of the downstream portion (307) of the exhaust port (304) substantially equal to a second cross-sectional area (APE) of the inlet opening (201) of the exhaust pipe (200).
• the intermediate portion (308) of the exhaust port (304) includes a reduced cross-section (309).
• the reduced cross-section (309) can include a smooth merging cross-section (309-2).
• the smooth merging cross-section (309-2) is provided with a predetermined angle of 3° to 20°.
• Fig. 4 (c) illustrates a cross-sectional view of a third exemplary exhaust system (400c) of the internal combustion engine (101), in accordance with an embodiment of the present subject matter.
• the second exemplary exhaust system (400b) includes the first cross-sectional area (APT) of the downstream portion (307) of the exhaust port (304) substantially lesser than the second cross-sectional area (APE) of the inlet opening (201) of the exhaust pipe (200).
• the second cross-sectional area (APE) of the inlet opening (201) of the exhaust pipe (200) is approximately 1.2 to 1.5 times that of the first cross-sectional area (APT) of the downstream portion (307) of the exhaust port (304).
• the exhaust pipe (200) is attached to the exhaust port (304) by means of the mounting flange (401), which is comfortably mounted on to the mounting region of the downstream portion (307) of the exhaust port (304).
• the intermediate portion (308) of the exhaust port (304) includes a reduced cross-section (309).
• the reduced cross-section (309) can include a tapering cross-section (309-1).
• the tapering cross-section (309-1) is provided with a predetermined angle of 3° to 20°, for example a tapering angle ranging from 3° to 20°.
• Fig. 4 (d) illustrates a cross-sectional view of a fourth exemplary exhaust system (400d) of the internal combustion engine (101), in accordance with an embodiment of the present subject matter.
• the fourth exemplary exhaust system (400d) includes a first cross-sectional area (Ap T) of the downstream portion (307) of the exhaust port (304) substantially lesser than the second cross-sectional area (APE) of the inlet opening (201) of the exhaust pipe (200).
• the intermediate portion (308) of the exhaust port (304) includes a reduced cross-section (309).
• the reduced cross-section (309) can include a smooth merging cross-section (309-2).
• the smooth merging cross-section (309-2) is provided with a predetermined angle of 3° to 20°.
• FIG. 5 illustrates a third exemplary exhaust system (500) depicting a cross-sectional view of the exhaust port (304) of the internal combustion engine, in accordance with another embodiment of the present subject matter.
• the intermediate portion (308), more particularly, the reduced cross- section (309) of the exhaust port (304) is provided with an entry point (502) for receiving at least one secondary air injection outlet conduit (501).
• providing the secondary air injection outlet conduit (501) at the reduced cross- section (309) of the exhaust port (304) helps in improving suction due to the vacuum created at the reduced cross-section (309). Further, this also ensures that more oxygen is made available at the catalytic converter (not shown in this figure) disposed downstream of the exhaust pipe (200). This enables improving the catalytic converter’s efficiency and the performance of the engine at desired operating points.
• Fig. 6 (a) depicts a first characteristic curve (600) of exhaust gas temperature in the exhaust system of the internal combustion engine, in accordance with an embodiment of the present subject matter.
• the first characteristic curve (600) depicts two varying curves, viz., a first temperature curve (601) for an engine with conventional cylinder head, and a second temperature curve (602) for an engine with improved cylinder head as described in the present subject matter.
• the temperature of exhaust gases travelling through the exhaust port (304) and into the exhaust pipe (200) has a steeper drop in the case of the first temperature curve (601) that has a conventional cylinder head assembly in comparison with the second temperature curve (602) employing the improved cylinder head assembly as described in the present subject matter.
• the exhaust port (304) of the cylinder head assembly (210) of the present subject matter involves an initial increase in cross-sectional area and a reduction in cross-sectional area towards the end of the exhaust port (304), as can be observed from Fig. 3 (a), 3 (b), 3 (c) and 3 (d).
• the conventional exhaust systems also include the inlet opening of the exhaust pipe (200) having a diameter or cross-sectional area that is lesser than the diameter or cross-sectional area of the exhaust port (304) at its downstream portion (307).
• the velocity of the exhaust gases exiting out of the exhaust port (304) does not show a significant increase as they progress within the exhaust pipe passage.
• the temperature of the exhaust gases drops close to 12 ⁇ 14% than in the case of the improved cylinder head of the present subject matter.
• Such a steep drop in the exhaust gases temperature is due to the loss of velocity in the exhaust gas stream.
• Fig. 6 (b) illustrates a cross-sectional view of a conventional exhaust system (600 (b)) depicting the intersection of the exhaust port and the exhaust pipe.
• Fig. 6 (c) illustrates a cross-sectional view of an exemplary exhaust system (600 (c)) depicting the intersection of the exhaust port and the exhaust pipe, in accordance with an embodiment of the present subject matter.
• the cross-sectional area of the conventional exhaust pipe (200’) abruptly decreases at the joining face of the exhaust port (304’). Such an abrupt change (603’) in the cross-sectional area tends to create turbulence in the exhaust gas flow.
• the exhaust system (600 (c)) of the present subject matter as seen in Fig. 6 (c) provides a reduction in cross-sectional area within the exhaust port (304), which not only helps in increasing the exhaust gas velocity from that point onwards, but also ensures that there exists a smoother transition of exhaust gas flow, thereby preventing any turbulence in the exhaust gas flow caused due to such reduction in cross-sectional area towards the downstream portion (307) of the exhaust port (304).
• the reduction in cross-sectional area towards the downstream portion (307) of the exhaust port (304) of the exhaust system (600(c)) of the present subject matter ensures that the high pressure within the exhaust port (304) is fully utilized for achieving effective increase in exhaust gas velocity without any losses.
• any increase in velocity of the exhaust gases that can be observed in the conventional exhaust system (600 (b)) will experience drop in pressure at the exhaust pipe (200’), which will impact the effective increase in the exhaust gas velocity.
• the improved cylinder head of the present subject matter is provided with a reduced cross-section when the exhaust gases exiting out of the combustion chamber approaches the downstream portion of the exhaust port (304).
• the reduced cross-section, and in particular, the tapered angle provided ensures that the velocity of the exhaust gases flowing past the reduced cross-section increases.
• the diameter or cross-sectional area of the inlet opening of the exhaust pipe (200) varies between 1.10 to 1.20 times that of the diameter or cross-sectional area of the downstream portion of the exhaust port (304), such a configuration of the exhaust port and the exhaust pipe joining face in combination with the reduced cross-section and the angle of the reduced cross-section ensures that the velocity of the exhaust gases in the exhaust pipe passage does not drop significantly.
• the catalytic converter unit (206) is disposed in the exhaust pipe (200).
• the velocity of the exhaust gases reaching the catalytic converter unit (206) of the present subject matter is high enough so that the temperature of the exhaust gases is at least 12 ⁇ 14% higher than in the case of the conventional cylinder head, thereby enabling an early light- off of the catalytic converter unit (206), which in turn increases the efficiency of the catalytic converter unit (206).
• Fig. 7 depicts a second characteristic curve (700) of engine torque of the internal combustion engine, in accordance with an embodiment of the present subject matter.
• the second characteristic curve (700) depicts a first torque curve (701) for engine with conventional cylinder head and a second torque curve (702) for engine with improved cylinder head as described in the present subject matter.
• the first torque curve (701) has a significantly low torque (Nm) at low engine speed (rpm) as compared to the second torque curve (702).
• Nm significantly low torque
• rpm engine speed
• Such a significant increase in engine torque at low engine speed in the improved cylinder head of the present subject matter is achieved as a result of the specific profile design of the exhaust port (304), for example, a reduced cross-section (309).
• the increase in the velocity of the exhaust gases at the reduced cross-section of the exhaust port (304) ensures that there is an improvement in the low-end torque of the engine and it also enhances the performance of the engine at certain specific operating points.
• the nozzle action caused due to the tapered profile section towards the end of the exhaust port (304) creates a back pressure or restriction during the valve overlap period. This back pressure facilitates the exhaust gases to push the piston down effectively and helps in improving low end torque of the engine. Further, the above low end torque is achieved without compromising mid-range and high end torque. In high speed region of the engine, the nozzle action caused due to the tapered profile section of the exhaust port (304) assists in sending the exhaust gases quickly to the muffler body (130) without any restriction for next cycle and thereby enhancing power of the engine.
• Fig. 8 depicts an exemplary method (800) of manufacturing of the cylinder head in accordance with an embodiment of the present subject matter.
• the method (800) of manufacturing the cylinder head of the present subject matter involves a first step (805) of forming an integrated sand core.
• the step (805) of forming the integrated sand core involves creating a sand core that is integral to the cylinder head along with the one or more intake ports and the one or more exhaust ports.
• the sand core of the improved exhaust port of the present subject matter is formed integrally with that of the cylinder head.
• the method (800) involves providing a stepped diameter or cross-sectional area before the outlet or the downstream portion of the exhaust port (304).
• the stepped diameter or cross-sectional area provided towards the end of the exhaust port (304) enables forming of the tapered profile portion of the exhaust port (304) with the desired characteristics of increasing the velocity of the exhaust gases without causing a performance drop in terms of drop in low end torque of the engine.
• the method (800) involves forming a locating element for the integrated sand core beyond the stepped diameter or cross-sectional area. The locating element thus formed ensures that the sand core is held stably during the casting process and metal is filled in the throat of the exhaust port after the stepped diameter or cross-sectional area.
• the method (800) involves receiving the locating element that is formed in the sand core beyond the stepped diameter or cross- sectional area of the exhaust port (304) by a metal core, which is held towards the ends of the sand core.
• the method (800) involves flow of material, for example, in an exemplary embodiment the material is an aluminum alloy. The aluminum alloy is allowed to flow into the cast containing the sand core.
• the method (800) involves low pressure die casting (LPDC) of the aluminum alloy in the cast.
• LPDC low pressure die casting
• the method (800) involves removal of gates or air vents from the cast after the low pressure die casting is carried out for a predetermined time and at predetermined operating conditions. Furthermore, at an eighth step (840), the method (800) involves cleaning of the casted part; the cleaning involves operations such as fettling for removal of undesired edges and burrs from the casted part. At a ninth step (845), the method (800) involves heat treatment of the die cast part for a predetermined time and at predetermined operating conditions. Further, at a tenth step (850), the method (800) involves machining of the cast cylinder head.
• the machining is done to ensure that the desired ratio of tapered angle to the length of the exhaust port (304) at the second region connecting the intermediate portion and the downstream portion is achieved. It is important to achieve the above described desired ratio, as it is critical to achieve the desired increase in velocity of the exhaust gases without compromising the performance characteristics such as low end torque and power.
• FIG. 9 illustrates a cross-sectional view of the cylinder head assembly of the present subject matter depicting an intake port passage and an exhaust port passage with an integrated sand core disposed therein.
• the cylinder head assembly (210) of the present subject matter is die casted with the help of the integrated sand core formed therein.
• an intake port metal core (901) is provided to hold the underneath sand core firmly during die casting process described above.
• the sand cores (903, 904, 905) of the intake port, the exhaust port and the combustion chamber are glued to form the integrated sand core.
• the exhaust port sand core (904) is provided with a stepped diameter or cross-sectional area (906) before the outlet portion of the exhaust port (304).
• a locating element (907) is formed beyond the stepped diameter or cross-sectional area (906) of the exhaust port (304), which ensures that the necessary reduced cross-section before the downstream portion of the exhaust port (304) is formed in the die-cast cylinder head assembly (210) for effecting the increase in exhaust gas velocity and improving low-end torque without compromising on engine performance.
• the locating element (907) is formed on an exhaust core metal core (902). [00075]

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• 2019
  • 2019-10-27 EP EP19809653.9A patent/EP3874134A1/de not_active Withdrawn
  • 2019-10-27 WO PCT/IN2019/050791 patent/WO2020089930A1/en unknown
  • 2019-10-27 BR BR112021008498-3A patent/BR112021008498A2/pt unknown
  • 2019-10-27 CN CN201980069727.6A patent/CN112912597B/zh active Active
• 2021
  • 2021-04-28 CO CONC2021/0005588A patent/CO2021005588A2/es unknown

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