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 exhaust air sensor mounting structure, for mounting an exhaust air 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 internal combustion engine mounted vehicle are becoming stringent in view of environment protection.

To address such regulations, and to achieve improved fuel efficiency and engine performance, one of the known methods is to detect oxygen concentration in the exhaust gas, and feedback the detected oxygen concentration 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 oxygen 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.

Thus, to obtain accuracy and wide range of operation of a typical oxygen sensor in the entire range of working air-fuel ratios, it is necessary that the sensor element be controlled at a higher temperature however, the exhaust pipe of an automotive vehicle in which the oxygen sensor is mounted, 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, 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 an 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 applies a 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 can be damaged. If the zirconia solid electrolyte is damaged, not only the accuracy of the sensor output become worse but also an exhaust purifying system using the sensor output of the sensor malfunctions.

To prevent this, it is necessary to start supplying electric power to the electric heater after the water vapours that has been condensed on the inner wall of the exhaust pipe since the start of the engine is dried oft Accordingly, the sensor cannot be put into operation until a fair amount of time has elapsed since the start of the engine.

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.

SUMMARY OF THE INVENTION

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

The preferred embodiment of the invention incorporates a standard thread hole for mounting an exhaust air sensor in such a manner that the vertical axis of thread hole is parallel to the vertical axis of cylinder head and is perpendicular to the horizontal axis of the exhaust opening of the cylinder head.

The oxygen sensor is secured in upwards direction over the exhaust opening of cylinder head such that vertical axis of oxygen sensor is parallel to the vertical axis of cylinder head and perpendicular to the horizontal axis of the exhaust port 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 distance of exhaust gas sensor from the combustion chamber is largely reduced, water vapours, 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 excluded.

This arrangement also ensures ease of serviceability and production and compact packaging of the same. 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 thus proper cooling arrangement for the same is required in order to ensure accuracy of sensor. As the air flowing through the vehicle body directly comes to vertically positioned sensor over the cylinder head in more amount results in more cooling effect for the sensor.

The oxygen sensor is preferably low cost sensor used without heating element. 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 the top view of the internal combustion engine depicting the essential embodiments of the invention.

Figure 4 is the sectional side view of the internal combustion engine showing the mounting arrangement of the essential embodiments of the invention.

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 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 18. Said cylinder head 18 is placed over the cylinder block 16 and covered with the cylinder head cover 17 with an opening which is closed by the cylinder head cover cap 13. Said cylinder block 16 and the cylinder head 18 are integrated with each other and for a cylinder unit. An exhaust passage 15 is connected to the cylinder head 18 through a sensor mounting area 14 such that the sensor mounting area 14 is covering the joint between the exhaust passage 15 and the cylinder head 18.

Figure 2 is further showing a sensor holding bracket 20 fixed over the sensor mounting area 14 in such a way that the exhaust air sensor 12 is passing through the sensor holding bracket 20 and upper end of the exhaust air sensor 12 is connected to the cylinder head cover cap 13 through a connecting passage 19.

Further, referring to Figure 3, cut section top view of the cylinder head 18 is shown. Air from the intake guide 21 enters into the cylinder head 18 and after combustion passes through the exhaust guide 22 and then exits from the cylinder head 18 through the exhaust passage 15. Amount of oxygen, in the intake guide 21 and the exhaust guide 22 is different, as the major part of the present oxygen bums during the combustion of the fuel.

The exhaust air sensor 12, particularly used to measure the amount of oxygen in the exhaust air, is mounted between the exhaust guide 22 and the exhaust passage 15, such that the exhaust air passes by the exhaust air sensor 12. As shown in Figure 4, exhaust air sensor 12 is passing through the sensor holding bracket 20 fixed over the sensor mounting area 14, such that the lower end 23 of the exhaust air sensor 12 is secured inside the exhaust passage 15 from where the exhaust air passes.

Further, referring back to Figure 3, the sensor mounting bracket 20 is shown, which is holding or surrounding the exhaust air sensor 12. Said sensor mounting bracket 20 is generally a hollow open ended structure e.g. a hole, which is integrated with the sensor mounting area 14 and the exhaust air sensor 12 can pass through the sensor mounting bracket 20. Mentioned sensor mounting bracket 20 can be a threaded or a plain structure.

Further, as shown in Figure 4, vertical axis Rc of the cylinder head 18/ the cylinder unit is parallel to the vertical axis Rs of the exhaust air sensor 12 due to which the exhaust air 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.
Further, the vertical axis Rs of the exhaust air sensor 12 is perpendicular to the horizontal axis Re of the exhaust air passage 15 of the cylinder head 18. This exhaust sensor 12 is mounted in upward direction such that conditions for axis Rc, Rs and Re are strictly fulfilled.

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

Although the exhaust air sensor 12 is described as being an oxygen concentration sensor of zirconia solid electrolyte type, it may 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 in more amount results in more cooling effect for the sensor 12.

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 air sensor secured in a sensor holding bracket fixed over a sensor mounting area covering the joint of the exhaust passage and the cylinder head;

wherein, the exhaust air sensor is inserted vertically downward on the upper part of the sensor mounting area such that the vertical axis of the cylinder head is parallel to the vertical axis of the cylinder head is parallel to the vertical axis of the exhaust air sensor and horizontal axis of the exhaust passage is perpendicular to the vertical axis of the exhaust air sensor and the exposed end of the exhaust air sensor is attached to the cylinder head cover through a connecting passage and lower end of exhaust air sensor is passing through the sensor mounting area.

2) The internal combustion engine, as claimed in claim 1, wherein sensor mounting area comprises joint of exhaust passage and the cylinder head.

3) The internal combustion engine, as claimed in claim 1, wherein bottom part of the exhaust air sensor is passing through the sensor mounting area and is secured inside the air exhaust passage.

4) The internal combustion engine, as claimed in claim 1, wherein the exhaust air sensor is an oxygen sensor.

5) The internal combustion engine, as claimed in claim 1, wherein the sensor holding bracket is a hollow open ended bracket.