REFERENCE DATA

The present application claims priority from Indian patent application 3255/CHE/2010 filed November 1, 2010. The present invention comprises a modification of the invention claimed in the specification of the patent application 3255/CHE/2010.

FIELD OF INVENTION

The subject matter described herein, relates to a cylinder head of an internal combustion engine more particularly to an oxygen sensor mounting structure, for mounting an oxygen sensor to an exhaust port of an internal combustion engine, suitable for use in an exhaust purifying system of an internal combustion engine.

BACKGROUND OF THE INVENTION

In recent years, regulations of exhaust emissions from vehicles fitted with internal combustion engine are becoming stringent in view of environment protection.

To address such stringent regulations, and without comprising on fuel efficiency and engine performance, the known method is ECU having a closed loop system provided with an 02 sensor (Oxygen concentration sensor). In this known system, the oxygen concentration in the exhaust gas is detected and feedback is given to an engine control unit to effect finer control of fuel-air mixtures supplied to the engine of an automotive vehicle, so that nitrogen oxide, and particulate carbon or smoke in the exhaust gas can be reduced, It is common that, as an exhaust sensor for detecting oxygen concentration in an exhaust gas, a sensor of the zirconia solid electrolyte type is used, that utilizes oxygen ion pumping action of the zirconia solid electrolyte. Such a sensor of the zirconia solid electrolyte type has to be heated over 650° C. to produce an accurate sensor output, because it uses zirconia solid electrolyte in its sensing section.

Generally, in order to obtain mentioned requirements oxygen sensor is mounted over the exhaust pipe but in that case it becomes extremely necessary to protect sensor element at higher temperature as exhaust pipe of vehicle shows great fluctuations in temperature.

This makes it necessary to pass an electric current to the oxygen sensor and heat the same nearly at all times. However, to achieve economy in fuel consumption, it would be necessary to minimize electric power used for the purpose of heating.

Further when the engine is started from cold state, since an inner wall temperature of the exhaust pipe is low, water vapour contained in the exhaust gas is condensed on the inner wall of the exhaust pipe. This condensed water flies off the inner wall due to the flow of the exhaust gas, and spatters on the sensing section of the sensor that is being heated by the electric heater included therein.

This causes large thermal stress to the sensing section of the sensor, as a result of which the zirconia solid electrolyte forming the sensing section of the sensor gets damaged over a period of time. If the zirconia solid electrolyte is damaged, not only the accuracy of the sensor output become worse but also the exhaust purifying system using the sensor output of the sensor malfunctions.

During starting, engine is not heated up causing vapour condensation near the oxygen sensor which affects the accuracy of the sensor. To prevent this, it is necessary to heat the sensor by external means by supplying electric power.

Further, in some vehicles sensors are provided to regulate the intake of air in the combustion chamber through a microcontroller based circuit. But the location of said sensor has always been an issue as during running condition external factors such as obstacles like stones etc comes in contact with the engine harms said sensor considerably and hence microcontroller based gets affected and does not provide required result.

However, in order to address above mentioned issues oxygen sensor is mounted over the cylinder head i.e. over the exhaust port of the cylinder head. Although this location addresses the above mentioned issue up to a certain extent but the mentioned location has other problems.

Mostly lesser sensing area of sensing part of the oxygen sensor is exposed to the coming exhaust gases that give inconsistency readings and hence the efficiency of the sensing system reduces.

SUMMARY OF THE INVENTION

The present subject matter herein described is related to a cylinder head for an internal combustion engine, with an oxygen sensor mounting structure.

The preferred embodiment of the invention incorporates a standard thread hole for mounting an oxygen sensor in such a manner that the vertical axis of thread hole is parallel to the vertical axis of cylinder head and is at acute angle in upwards direction, with respect to the horizontal axis of the exhaust opening of the cylinder head.

This arrangement ensures that the exhaust gas sensor is placed at a location where temperature fluctuation is largely reduced and thus accuracy is maintained along with the reduction in external power usage for maintaining the temperature of the oxygen sensor. Further, as oxygen sensor is placed at an acute angle with respect to the exhaust port, the sensing part of the oxygen sensor is placed inside the exhaust port in the direction opposite to the incoming exhaust air i.e. placed in the downstream to upstream direction. This provision for oxygen sensor ensures larger surface area for contact with exhaust air and hence the accuracy of the system increases. Further angular orientation of the said sensor on the cylinder head will generate additional turbulence locally and hence enhance efficiency.

Moreover as the distance of exhaust gas sensor from the combustion chamber is largely reduced, water vapour, which condenses and subsequently reaches the exhaust gas sensor, remains so low that deposition of larger quantities of water, which are critical in terms of damage to the oxygen sensor, is eliminated.

The angular location also ensures easy assembly and disassembly in production line and during service and hence compact packaging., f The elevated location of the said oxygen sensor in the present invention ensures protection of the said sensor from external factors such as obstacles e.g. stone etc during running condition.

Claimed arrangement of the sensor over the cylinder head facilitates a better cooling of the oxygen sensor. As said sensor is subjected to direct heat and hot exhaust gas from the cylinder head, proper cooling arrangement for the same is required in order to ensure accuracy of sensor. Since the air flowing through the vehicle body directly comes to sensor positioned in upward inclined direction over the cylinder head cooling of the sensor increases effectively.

The oxygen sensor is preferably a sensor without heating element to bring down the cost. Further the oxygen sensor may be an oxygen concentration sensor including a zirconia solid electrolyte type sensing element, with an electric heater or heating element for heating the zirconia solid electrolyte type sensing element.

These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following description and appended claims.

This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus, are not limited of the present invention and wherein:

Figure 1 is the pictorial representation a two-wheeled vehicle representing the embodiments of the present invention.

Figure 2 is the pictorial representation of an internal combustion engine depicting the embodiments of the invention.

Figure 3 is a typical representation of the claimed invention depicting the mounting arrangement of essential embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. The application of this invention is extended to all kind vehicles.

In the present disclosure, Figure 1 illustrates a two-wheeled motor vehicle, indicated by reference numeral 01, mainly comprising of a body frame 02, a front suspension 08 attached to a head pipe 03 of the body frame 02, a front wheel 07 secured to the front fork 08 along with the mud shield 04 and a handle bar assembly 11 further attached to the front fork 08. Furthermore, an engine 09 is mounted to centre portion of the body frame 02, a rear wheel 06 is secured to the rear portion of body frame 02.

Figure 2 illustrates the engine 09 focusing on the exhaust side of the cylinder head 17. Said cylinder head 17 is integrated with cylinder block 23 and covered with the cylinder head cover 24. Said cylinder head cover has an opening covered by the cylinder head cover cap 25.

Said cylinder block 23 and the cylinder head 17 are connected with each other and whole unit is classified as a cylinder unit. An exhaust port 14 is connecting the cylinder head 18 to an exhaust passage 15. Mentioned exhaust port 14 is acting as mounting area for oxygen sensor 12.

Said exhaust port 14 has an oxygen sensor 12 mounted between the space available between the cylinder head 17 and exhaust passage 15.

Further, referring to Figure 3, cylinder head 17 is shown in order to show mounting arrangement of the embodiments of the invention. The oxygen sensor 12, particularly used to measure the amount of oxygen in the exhaust gas, is mounted over the exhaust port 14 located between the cylinder head 17 and the exhaust passage 15.

Oxygen sensor 12 is mounted over the exhaust port 14 in downstream to upstream direction. Said upstream to downstream inclination of the exhaust sensor 12 is achieved by keeping angle 20 between the vertical axis 18 of oxygen sensor 12 and horizontal axis 19 of exhaust port 14 less that 90 degree i.e. an acute angle. For best assembly and maximum benefits of the arrangement preferred angle 20 is 82 degree.

Arrangement of acute angle 20 is made in such a way that sensing tip 21 of the oxygen sensor 12 remains in contact with the exhaust gas 22 for maximum possible duration due to inclined positioning of the oxygen sensor 12.

Further, as shown in Figure 3, vertical axis 16 of the cylinder head 17 is parallel to the vertical axis 18 of the oxygen sensor 12 due to which the oxygen sensor 12 is located on the top of the engine 09 and hence remains secured from the external obstacles like stones etc specially during running condition. This oxygen sensor 12 is mounted in upward direction such that conditions for axis 16,18 and 19 are strictly fulfilled.

With the above described arrangement damage to the said oxygen sensor 12 can be prevented to a considerable limit and the performance of said oxygen sensor 12 remains consistent.

Although the oxygen sensor 12 is described as being an oxygen concentration sensor of zirconia solid electrolyte type, it may be of any other suitable sensor that can be mounted.

Claimed arrangement of the oxygen sensor 12 over the cylinder head 18 facilitates a better cooling of the oxygen sensor 12. As said sensor 12 is subjected to direct heat and hot exhaust gas from the cylinder head 18 thus proper cooling arrangement for the same is required in order to ensure accuracy of sensor 12. As the air flowing through the vehicle body directly comes to vertically positioned sensor 12 over the cylinder head 18 cooling of the sensor 12 is ensured.

The above explained preferred embodiments are exemplary of the invention of the present application, which is described solely by the claims appended below. It should be understood that modifications of the preferred embodiments might be made as would occur to one of skill in the art.

WHAT IS CLAIMED IS

1) An internal combustion engine, comprising:

a) a cylinder head unit having a cylinder head with a cylinder head cover secured over a cylinder block such that the cylinder head unit is connected to an intake passage and an exhaust passage;

b) an exhaust port connecting the cylinder head to the exhaust passage onto which oxygen sensor is mounted on the exhaust port;

wherein, the oxygen sensor is inserted vertically downward on the upper part of the exhaust port such that the vertical axis of the cylinder head is parallel to the vertical axis of the oxygen sensor and an acute angle is formed between horizontal axis of the exhaust port and the vertical axis of the oxygen sensor such that a sensing part of the oxygen sensor is secured inside the exhaust port in a downstream to upstream direction.

2) The internal combustion engine, as claimed in claim 1, wherein the sensing part of the oxygen sensor is secured inclined inside the exhaust port such that direction of incoming exhaust air is opposite to the direction of the oxygen sensor mounting.

3) The internal combustion engine, as claimed in claim 1, wherein the oxygen sensor is fixed into the exhaust port through a hollow open ended holding bracket.

4) The internal combustion engine, as claimed in claim 1, wherein the acute angle is defining the range of from 80 degree to 85 degree.