WO2023242855A1

WO2023242855A1 - An internal combustion engine

Info

Publication number: WO2023242855A1
Application number: PCT/IN2022/050988
Authority: WO
Inventors: Padmanabha PILLAI LOGANAYAKAN; Dharmapuri NAGENDRA KUMAR; Vedhanayagam JAYAJOTHI JOHNSON
Original assignee: Tvs Motor Company Limited
Priority date: 2022-06-15
Filing date: 2022-11-10
Publication date: 2023-12-21

Abstract

An Internal Combustion Engine An internal combustion engine (100) is provided comprising a sensor (110) for sensing a concentration of unburnt oxygen in an exhaust of the engine (100) and a cross path (140) for passage of the gases of the exhaust of the engine (100). The sensor (110) is located directly within a flow-path (140f) of the exhaust coming out of a combustion chamber (150). The cross path (140) has a thicker path (140D) and a thinner path (140d) connected to one another to form a closed path for recirculation of exhaust gases for preheating the sensor 110. The sensor (110) is located within and at a distal end of the cross path (140) and close to the spark plug (124) on a right side of the engine. The invention reduces the response time for maintaining optimum air-fuel mixture ratio in the engine (100) and thus increasing efficiency and reducing emission.

Description

TITLE OF INVENTION

An Internal Combustion Engine

FIELD OF THE INVENTION

[001] The present invention relates to internal combustion engines and more particularly to lambda sensors in internal combustion engines. BACKGROUND OF THE INVENTION

[002] Technology has enabled continuous improvements in the performance of modern vehicles using various kinds of digital control systems. These control systems rely on the inputs provided by different types of sensors in the vehicle to control the engine, monitor emission, etc. It is desired that the sensors provide accurate and real time data so that the response time for the control unit is reduced. The types of sensors include mass airflow sensors, engine speed sensor, spark knock sensor, pressure sensor, oxygen sensor, and the like. The oxygen sensor is also known as Lambda Sensor. This sensor is present at an exhaust system of the vehicle. [003] In an internal combustion engine, a lambda sensor (oxygen sensor), is a small probe near a vehicle exhaust. It is typically located between an exhaust manifold and a catalytic converter of the engine. The lambda sensor senses concentration of gases such as oxygen gas in an exhaust of the engine and sends signals based upon the oxygen concentration to an Electronic Control Unit (ECU) to adjust the fuel amount that is sent to engine cylinders by optimizing a composition of the air and fuel mixture. This helps in an improved efficiency of the engine. Besides, this also reduces the amount of harmful gas emissions by making sure that the catalytic converter is working correctly. Hence, the lambda sensor helps in ensuring that the vehicle complies with the standard regulations on pollution and CO2 emissions. As the lambda sensor is placed before the catalytic converter, it can measure the amount of air and fuel in the unburnt hydrocarbons after the combustion. The Electronic Control Unit (ECU) which controls some functionalities of the engine, will receive the correct data on the emissions, and it will then release the exact quantity of gas needed. This is essential in decreasing polluting emissions. The arrangement of the sensor before and after the catalytic converter permits to maintain the hygiene of the exhaust and check the converter’s efficiency.

[004] It is also known in the art to provide two such lambda sensors placed in the vehicle: one located in an exhaust pipe right behind the catalytic converter and one in a cylinder head in an exhaust port.

[005] In existing internal combustion engines, the lambda sensor is dipped inside the exhaust port from a top portion of the exhaust port. For proper functioning, the lambda sensors need to be heated to a certain temperature. Accordingly, to achieve preheating of the lambda sensor, it is preferred if the sensor is located close to the exhaust port so they will heat up quickly and give data good enough for closed loop operation within seconds of engine start. Further, the distance between the exhaust valves and the place where the sensor is installed as well as the significant time for response of its sensitive element is important for effective functioning of the sensor.

[006] Such existing arrangements have the oxygen sensor placed away and at a significant distance from the exhaust valve. The distance is significant enough to cause a delay in the response time of the control system of the engine. The exhaust valves are placed downwards to the exhaust port. Hence, on opening of the valves, there is a significant delay of time for the gases to reach to the oxygen sensor, which is undesirable.

[007] In one known prior art, a multi cylinder internal combustion engine comprises a cylinder head internally defining exhaust passages extending from a plurality of combustion chambers defined in part by the cylinder head. The exhaust passages converge into a converging area also internally defined in the cylinder head. An oxygen sensor for detecting an oxygen concentration in exhaust gas is passed into the converging area substantially in parallel with a cylinder axial line. Thus, the oxygen sensor can be mounted relatively close to the combustion chamber while permitting the sensor to be uniformly exposed to the exhaust gas from the combustion chambers of an entire cylinder bank. Although close to the combustion chamber, there is significant time for response of its sensitive elements which causes a delay in continuous maintenance of the fuel mixture, thus effecting the performance of the oxygen sensor. Further, this also requires a preheated oxygen sensor to be placed here because the oxygen sensor requires a suitable higher temperature for operation.

[008] In another known prior art, an internal combustion engine management system employs an exhaust system sensor which senses exhaust gases by drawing exhaust gases from an exhaust of the engine. In some instances, this is done directly from the cylinder and in others it is done in the exhaust system. However, in each case, the sensor is provided in an accumulator chamber so as to provide an accurate signal of instantaneous engine running conditions. The use of the accumulator chamber insures that the combustible gases will not be diluted with fresh air charge, but will be able to purge from cycle to cycle so as to provide cycle-by-cycle information. Various arrangements are provided for protecting the sensor element including serpentine flow paths, shields, the direction in which the exhaust gases are delivered, lubricant catalysts, conduit shape, sensor cooling and combinations of these features. Furthermore, various structural elements help protect the exterior of the oxygen sensor from damage, such as housings, placement of the sensor within depressions in the engine and integrally forming the sensor in the cylinder block. As a result, there is a delay in the continuous maintenance of the air-fuel mixture.

[009] In another prior art, a cylinder head of an internal combustion engine has intake and exhaust valves arranged in the form of a V-shape, wherein an exhaust port is bent from the axis of the exhaust valve in a direction opposite to the intake valve, and a mounting surface for an exhaust member is formed at the downstream end of the exhaust port. A mounting structure for an exhaust gas sensor wherein the exhaust gas sensor is located on the periphery of the mounting surface so as to project from the outer side surface of the exhaust port in the condition where the exhaust gas sensor is inclined with respect to the axis of a cylinder.

[010] In the arrangements in the prior art, the distance between the exhaust valves and the place where the sensor is installed (on top portion of the exhaust port) is significant. The distance is significant enough to affect the time for response of its sensitive element. This causes an undesirable system delay, which doesn’t prevent continuous maintenance of the stoichiometric fuel mixture, thereby affecting the delay in effective performance of the oxygen sensor and the engine. Further, it is desired that the sensor reaches optimum temperature for performance and also remains at the desired optimum temperature while the engine is running. Further, compactness of the engine is affected since there has to be a separate opening in the exhaust port. Besides, if there is any crack in the exhaust port due to such opening for the oxygen sensor, this leads to incorrect measurement of data by the oxygen sensor.

[011] Thus, there is a need in the art for an internal combustion engine with an oxygen sensor, which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION

[012] In one aspect, the present invention is directed at an internal combustion engine comprising a sensor for sensing a concentration of gases in an exhaust of the engine and a cross path for passage of the gases of the exhaust of the engine. The sensor is mounted on a cylinder head of the engine. The sensor is located directly within in a direction of a flow-path of the exhaust coming out of a combustion chamber through an exhaust valve of the engine. The cross path has a thicker path and a thinner path. The thicker path has a diameter greater than a diameter of the thinner path. The sensor is located within the cross path.

[013] In an embodiment, the thicker path is substantially in line with the flowpath. The thicker path enables and directs the exhaust towards the sensor. The sensor is located within a distal end of the thicker path.

[014] In an embodiment, the sensor is an oxygen sensor. The oxygen sensor is configured to measure a concentration of oxygen gas in the gases of the exhaust. The oxygen sensor has a longitudinal arm for holding the sensor within the cylinder head.

[015] In an embodiment, the sensor is located adjacent to a spark plug of the engine and substantially closer to the spark plug as compared to an exhaust port of the engine. The sensor is located near a valve stem of the exhaust valve and directly in line with a valve opening of the exhaust valve of the engine. The sensor is located adjacent to the spark plug and on a right side of a vehicle with reference to a vehicle rider.

[016] In an embodiment, the cross path enables recirculation of the gases of the exhaust of the engine. The recirculation happens within the cylinder head of the engine and enables preheating of the sensor.

[017] In an embodiment, the cylinder head has a sensor opening located adjacent to the spark plug. The sensor is mounted on the cylinder head through the sensor opening. The internal combustion engine comprises a plug top. The plug top is configured for closing at least a part of the cross path. The plug top enables access to the cross path.

BRIEF DESCRIPTION OF THE DRAWINGS

[018] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 illustrates a cross sectional front view of a part of an internal combustion engine, in accordance with an embodiment of the present invention.

Figure 2 illustrates a cylinder head of the internal combustion engine in a perspective view, in accordance with an embodiment of the invention.

Figure 3 illustrates the cylinder head of the internal combustion engine in another perspective view, in accordance with an embodiment of the invention.

Figure 4 illustrates the cylinder head of the internal combustion engine in yet another perspective view, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[019] The present invention relates to internal combustion engines. More particularly, the present invention relates to sensors for sensing concentration of exhaust gases in internal combustion engines.

[020] Figure 1 illustrates a cross sectional front view of a part of an internal combustion engine 100, in accordance with an embodiment of the present invention. As an example, the engine 100 is a single cylinder, two-valve engine typical for a two wheeled vehicle such as a scooter, a motorcycle and the like. In other embodiments, the engine 100 is a multi-valve, multi-cylinder engine with cylinders arranged in V-arrangement and the like.

[021 ] The engine 100 comprises a sensor 110 for sensing a concentration of gases in an exhaust of the engine 100 and a cross path 140 for passage of the gases of the exhaust of the engine 100. The sensor 110 is mounted on a cylinder head 120 of the engine 100. The sensor 110 is located directly within a flow-path 140f of the exhaust coming out of a combustion chamber 150 through an exhaust valve 130 of the engine 100. The sensor 110 is located directly in line and within a direction of the flow-path 140f of the exhaust. The cross path 140 has a thicker path OD and a thinner path 140d (Also shown in Figure 3).

[022] The cross path 140 provides passage to the exhaust within the cylinder head 120 and is directly connected with the exhaust valve opening in the cylinder head 120. The thicker path MOD has a diameter greater than a diameter of the thinner path MOd. The sensor 110 is located within the cross path 140. The thicker path MOD starts from the exhaust valve opening and extends till a distal end at least till the sensor location. The thinner path MOd starts from and connects with the thicker path MOD from where the thicker path MOD ends at the distal end. The thinner path MOd ends at and connects the distal end of the thicker path OD to an exhaust port of the engine 100.

[023] In an embodiment, the thicker path MOD is substantially in line with the direction of the flow-path MOf. The thicker path MOD enables and directs the exhaust towards the sensor 110. The sensor is located within the distal end of the thicker path MOD.

[024] After a completion of a combustion cycle in the engine 100, when the exhaust valve 130 opens, the exhaust travels in the direction of the flow-path MOf, through the thicker path MOD. The gases in the exhaust come in contact with the sensor 110 located within and at the distal end of the thicker path MOD. The sensor measures the concentration of gases within the exhaust.

[025] Figure 2 illustrates the cylinder head 120 in a perspective view, in accordance with an embodiment of the invention. In an embodiment, the sensor 110 is an oxygen sensor. The oxygen sensor is configured to measure a concentration of oxygen gas in the gases of the exhaust. The oxygen sensor has a longitudinal arm 110a for holding the sensor within the cylinder head 120.

[026] In an embodiment, the sensor 110 is a lambda sensor. Lambda Sensor, also known as an oxygen sensor, measures the amount of unburnt oxygen present in the exhaust. The output of the sensor 110 is used to adjust the air/fuel mixture in the engine 100. The sensor 110 helps to determine whether this air-fuel ratio is lean or rich.

[027] Referring again to Figure 1 , in an embodiment, the cross path 140 enables recirculation of the gases of the exhaust of the engine 100. The recirculation happens within the cylinder head 120 of the engine 100 and enables preheating of the sensor 110. Once the exhaust comes in contact with the sensor 1 10, the exhaust is then directed towards and enters the thinner path 140d to recirculate inside the exhaust valve 130 and cylinder head 120. Post recirculation, the exhaust is directed out from the cylinder head 120 towards a muffler assembly connected to the engine 100. The sensor 110 has a heating sensor (not shown). The sensor 110 needs heating to reach an optimum temperature for performance. The heating sensor helps in determining whether the sensor 110 has reached the optimum operating temperature. For example, the optimum temperature for the Lambda sensor is from 300°C to 600°C. The recirculation enabled by the cross path 140 enables the sensor 110 to reach the optimum temperature and maintain the same.

[028] When the engine 100 reaches the right temperature, the sensor 110 starts measuring the unburnt oxygen present in the exhaust. This output is sent to a control unit where it calculates the air-fuel ratio and checks a lookup table to optimize this air-fuel ratio. Based on this information, a calculated amount of fuel required by the engine 100 to burn at a stoichiometric ratio is released, ensuring complete combustion.

[029] Referring again to Figure 2, in a preferred embodiment, the sensor 110 is located adjacent to a spark plug 124 of the engine 100 and substantially closer to the spark plug 124 as compared to an exhaust port 126 of the engine 100. The sensor 1 10 is located near a valve stem of the exhaust valve 130 and directly in line with a valve opening of the exhaust valve 130 of the engine 100. In a preferred embodiment, the sensor 110 is located adjacent to the spark plug 124 and on a right side of a vehicle with reference to a vehicle rider/driver. The sensor 110 is located on the engine 100 on the right side of the vehicle rider/driver while the vehicle rider/driver is riding/driving the vehicle in a normal/conventional position. The sensor is placed in such a manner that it falls directly in line with the angle of opening of exhaust valve 130. This eliminates or at least reduces the delay substantially for the exhaust to get in contact with the sensor 110.

[030] Figure 4 illustrates the cylinder head 120 of the engine 100 in another perspective view, in accordance with an embodiment of the invention. The cylinder head 120 has a sensor opening 110o located adjacent to the spark plug 124. The sensor 110 is mounted on the cylinder head 120 through the sensor opening 110o. The engine 100 includes a plug top 11 Op. The plug top 11 Op is configured for closing at least a part of the cross path 140. The plug top 11 Op enables access to the cross path 140. In an embodiment, the plug top 110p is made from aluminum.

[031] Advantageously, the invention provides a configuration of the sensor in the internal combustion engine which eliminates the problem of distance between the exhaust valves and the sensor, which in turn, reduces the response time. This enables continuous and better maintenance of the stoichiometric air-fuel mixture, thereby eliminating the delay in effective performance of the oxygen sensor. Moreover, the cross path created inside the engine enables recirculation of hot exhaust gases inside the engine, thereby eliminating the need for preheating the oxygen sensor, as the sensor keeps on continuously getting heated through the hot exhaust gases as it is close to the exhaust valve opening.

[032] Further, the lambda or oxygen sensor is placed on the side of the spark plug and not on the exhaust port. Since the location of the sensor is near the spark plug side of the engine, the engine compactness is also maintained.

[033] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims. REFERENCE NUMERAL SHEET:

INTERNAL COMDBUSTION ENGINE: 100

SENSOR: 110

LONGITUDINAL ARM: 110a

CYLINDER HEAD: 120

SPARK PLUG: 124

EXHAUST PORT: 126

FLOW-PATH: 140f

SENSOR OPENINIG: 110o

PLUG TOP: 11 Op

CROSS PATH: 140

THICKER PATH: 140D

THINNER PATH: 140d

EXHAUST VALVE: 130

COMBUSTION CHAMBER: 150

Claims

CLAIMS:

1. An internal combustion engine (100) comprising: a sensor (110) for sensing a concentration of gases in an exhaust of the engine (100), the sensor (110) being mounted on a cylinder head (120) of the engine (100), wherein the sensor (110) is located directly within a flow-path (140f) of the exhaust coming out of a combustion chamber (150) through an exhaust valve (130) of the engine (100); and a cross path (140) for passage of the gases of the exhaust of the engine (100), the cross path (140) having a thicker path (1400) and a thinner path (140d), the thicker path (1400) having a diameter greater than a diameter of the thinner path (140d), the sensor (110) being located within the cross path (140).

2. The internal combustion engine (100) as claimed in claim 1 , wherein the thicker path (1400) is substantially in line with the flow-path, the thicker path (1400) enables and directs the exhaust towards the sensor (110), the sensor being located within a distal end of the thicker path (1400).

3. The internal combustion engine (100) as claimed in claim 1 , wherein the sensor (110) is an oxygen sensor, the oxygen sensor being configured to measure a concentration of oxygen gas in the gases of the exhaust, the oxygen sensor having a longitudinal arm (110a) for holding the sensor (110) within the cylinder head (120). The internal combustion engine (100) as claimed in claim 1 , wherein the sensor (110) is located adjacent to a spark plug (124) of the engine (100) and substantially closer to the spark plug (124) as compared to an exhaust port (126) of the engine (100) The internal combustion engine (100) as claimed in claim 1 , wherein the sensor (1 10) is located near a valve stem of the exhaust valve (130) and directly in line with a valve opening of the exhaust valve (130) of the engine (100). The internal combustion engine (100) as claimed in claim 1 , wherein the cross path (140) enables recirculation of the gases of the exhaust of the engine (100), the recirculation being within the cylinder head (120) of the engine (100) and enabling preheating of the sensor (110). The internal combustion engine (100) as claimed in claim 1 , wherein the cylinder head (120) has a sensor opening (110o), the sensor (110) being mounted on the cylinder head (120) through the sensor opening (110o), the sensor opening (110o) being located adjacent to the spark plug (124). The internal combustion engine (100) as claimed in claim 7 , wherein the internal combustion engine (100) comprises a plug top (11 Op), the plug top (1 1 Op) being configured for closing at least a part of the cross path (140), the plug top (1 10p) enabling access to the cross path (140). The internal combustion engine (100) as claimed in claim 1 , wherein the sensor (110) is located adjacent to the spark plug (124) and on a right side of a vehicle with reference to a vehicle rider.