Claims:WE CLAIM:
1. A cylinder block (200) of an internal combustion engine (500), the cylinder block (200) comprising: a first face (210) having an exhaust outlet (212); a second face (220) extending perpendicular from the first face (210); a third face (230) opposite to the first face (210) and extending perpendicular from the second face (220), the third face (230) having an intake aperture; a fourth face (240), opposite to the second face (220) and extending perpendicular from the third face (230) and thereby meeting the first face (210), the fourth face (240) defines two corners; and a sensor mounting boss (400) formed on at least one corner of the two corners of the fourth face (240).

2. The cylinder block (200) as claimed in claim 1, wherein the cylinder block (200) comprising a timing chain placed adjacent to the second face (220).

3. The cylinder block (200) as claimed in claim 2, wherein the sensor mounting boss (400) is formed on a corner between the first face (210) and the fourth face (240).

4. The cylinder block (200) as claimed in claim 2, wherein the sensor mounting boss (400) is formed on a corner between the third face (230) and the fourth face (240).

5. The cylinder block (200) as claimed in claim 1, wherein the sensor mounting boss (400) extends between a first end (401) inside the cylinder block (200) and a second end (402).

6. The cylinder block (200) as claimed in claim 1, wherein the sensor mounting boss (400) receives a knock sensor (410).

7. The cylinder block (200) as claimed in claim 6, wherein the sensor mounting boss (400) protrudes from the cylinder block (200) and inclined at an angle of between 15° to 90° from an axial axis (280) of the cylinder block (200).

8. The cylinder block (200) as claimed in claim 1, wherein the cylinder block (200) comprises one or more cooling fins (260) formed around an outer periphery of the cylinder block (200), the outer periphery defined by the first face (210), the second face (220), the third face (230) and the fourth face (240).

9. The cylinder block (200) as claimed in claim 8, wherein the sensor mounting boss (400) is formed discontinuous from the cooling fins (260).

10. The cylinder block (200) as claimed in claim 1, comprises at least one stud bolt (270) for mounting the cylinder block (200) on a crankcase (100) wherein distance between the stud bolt (270) and the first end (401) of the sensor mounting boss (400) is between 0 mm to 15 mm.

11. An internal combustion engine (500), the internal combustion engine (500) comprising: a crankcase (100), the crankcase (100) housing a crankshaft; and a cylinder block (200) mounted on the crankcase (100), the cylinder block (200) comprising: a first face (210) having an exhaust outlet (212); a second face (220) extending perpendicular from the first face (210), the second face (220) having an adjacently placed timing chain; a third face (230) opposite to the first face (210) and extending perpendicular from the second face (220), the third face (230) having an intake aperture; a fourth face (240), opposite to the second face (220) and extending perpendicular from the third face (230) and thereby meeting the first face (210), the fourth face (240) defines two corners; and a sensor mounting boss (400) formed on at least one corner of the two corners of the fourth face (240).
, Description:FIELD OF THE INVENTION
[001] The present invention generally relates to a cylinder bock of an internal combustion engine, and more particularly to detection of knocking in internal combustion engines.

BACKGROUND OF THE INVENTION
[002] In spark ignited ICEs, combustion in cylinder of the ICE is due to propagation of flame front ignited by spark plug. However, when combustion results from one or more pockets of air/fuel mixture exploding away from the spark plug/ combustion front, it is termed as knocking. It is evident that the air/fuel charge is meant to be ignited by the spark plug only, and at a precise point in the piston's stroke. Thus, effects of untreated knocking range from inconsequential to completely destructive. Hence, detection of undesired engine knocking in the ICEs becomes absolutely necessary.
[003] Conventionally, a sensor – known as a knock sensor – is used to detect such knocking in the ICE. Accordingly, the knock sensor is mounted on a predetermined part of the ICE. When the engine knocks, vibrations caused due to knocking are picked up by the sensor and a corresponding electrical signal is generated. The electrical is then communicated to an Electronic Control Unit (ECU) for an appropriate action such as changing ignition timing. However, a running engine inherently produces loud sounds, has high vibrations and heats up to high temperatures. Thus, there are many problems associated with the sensor being able to correctly detect the engine knocks. Due to high sounds, high vibrations and the sensor not being able to sustain the high temperatures, knocks generated in the ICE often go undetected. There have been several attempts made in the industry to solve the problems.
[004] One of the prior arts discloses a water-cooled engine in which a knock sensor is fitted to a cylinder block. However, a water-cooled engine needs a flow passage for coolant, i.e., a water jacket, to be provided in, for example, a cylinder block and a cylinder head. It also requires a pump to convey the coolant and a radiator to cool the coolant. For this reason, the structure of the water-cooled engine tends to be complicated.
[005] Another prior art combines mounting arrangement of the knock sensor and engine temperature sensor together. The knock sensor is annually fitted to the extended cylindrical part of the engine temperature sensor and both these sensors are mounted together. This however is a complex arrangement which leads to poor vibration detection by the sensor and causes poor serviceability of either of the sensors.
[006] Yet another prior art proposes to suppress the temperature increase of knock sensor caused due to the engine heat, by providing a heat insulation member between knock sensor and mounting boss. The heat insulation member is made up of material having lower thermal conductivity than that of sensor mounting boss. However, even this type of arrangement is complex, increases manufacturing costs and has poor serviceability. Moreover, presence of such a heat insulator material between the engine and the mounting boss reduces the ability of knock sensor to detect the vibrations and also results in a reduced Signal to Noise Ratio (SNR) of the knock sensor.
[007] Thus, there is a need in the art for a cylinder block with a knock sensor which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[008] In one aspect, the present invention is directed to a cylinder block of an internal combustion engine. The cylinder block has a first face having an exhaust outlet; a second face extending perpendicular from the first face; a third face opposite to the first face and extending perpendicular from the second face, the third face having an intake aperture; a fourth face, opposite to the second face and extending perpendicular from the third face and thereby meeting the first face. The fourth face defines two corners. The cylinder block has a sensor mounting boss formed on at least one corner of the two corners of the fourth face.
[009] In an embodiment of the invention, the cylinder block has a timing chain placed adjacent to the second face.
[010] In another embodiment of the invention, the sensor mounting boss is formed on a corner between the first face and the fourth face, or on a corner between the third face and the fourth face. Further, the sensor mounting boss extends between a first end inside the cylinder block and a second end.
[011] In yet another embodiment of the invention, the sensor mounting boss receives a knock sensor.
[012] In further embodiment of the invention, the sensor mounting boss protrudes from the cylinder block and inclined at an angle of between 15° to 90° from an axial axis of the cylinder block.
[013] In yet another embodiment of the invention, the cylinder block has one or more cooling fins formed around an outer periphery of the cylinder block, the outer periphery defined by the first face, the second face, the third face and the fourth face.
[014] In yet another embodiment of the invention, the mounting boss is formed discontinuous from the cooling fins.
[015] In yet another embodiment of the invention, the cylinder block has at least one stud bolt for mounting the cylinder block on a crankcase wherein distance between the stud bolt and the first end of the mounting boss is between 0 mm to 15 mm.
[016] In another aspect, the present invention is directed towards an internal combustion engine, whereby the internal combustion engine has a crankcase, whereby the crankcase houses a crankshaft. The internal combustion engine further has a cylinder block mounted on the crankshaft. The cylinder block has a first face having an exhaust outlet; a second face extending perpendicular from the first face, the second face having an adjacently placed timing chain; a third face opposite to the first face and extending perpendicular from the second face, the third face having an intake aperture; a fourth face, opposite to the second face and extending perpendicular from the third face and thereby meeting the first face. The fourth face defines two corners. The cylinder block has a sensor mounting boss formed on at least one corner of the two corners of the fourth face. In an embodiment of the invention, the sensor mounting boss is formed on a corner between the first face and the fourth face, or on a corner between the third face and the fourth face. Further, the sensor mounting boss extends between a first end inside the cylinder block and a second end. The internal combustion engine further has a cylinder head, whereby the cylinder head is mounted above the cylinder block.

BRIEF DESCRIPTION OF THE DRAWINGS
[017] 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 shows an exemplary motor vehicle, in accordance with an embodiment of the invention.
Figure 2 shows an internal combustion engine in accordance with an embodiment of the invention.
Figure 3 shows an internal combustion engine in accordance with another embodiment of the invention.
Figure 4a shows an exploded view of the cylinder block in accordance with an embodiment of the invention.
Figure 4b shows the cylinder block along with a knock sensor in accordance with an embodiment of the invention.
Figure 5 shows a top view of the cylinder block along in accordance with an embodiment of the invention.
Figure 6 shows a cross-sectional view of the cylinder block in accordance with an embodiment of the invention.
Figure 7 shows a top view of the cylinder block along in accordance with an embodiment of the invention.
Figure 8 shows a comparative characteristic curve of Signal-to-Noise Ratio vs. the frequency of vibrations in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[018] The present invention relates to detection of knocking in internal combustion engines. In this regard, the present invention discloses a cylinder block of an internal combustion engine.
[019] Figure 1 illustrates an exemplary motor vehicle, in accordance with an embodiment of the invention. The motor vehicle 10 comprises an IC engine 12 that is vertically disposed. Preferably, the IC engine 12 is a single-cylinder type IC engine. The two-wheeled vehicle 10 comprises a front wheel 14, a rear wheel 16, a frame member, a seat 18 and a fuel tank 20. The frame member includes a head pipe 22, a main tube 24, a down tube (not shown), and seat rails (not shown). The head pipe 22 supports a steering shaft (not shown) and two telescopic front suspensions 26 (only one shown) attached to the steering shaft through a lower bracket (not shown). The two telescopic front suspensions 26 support the front wheel 14. The upper portion of the front wheel 14 is covered by a front fender 28 mounted to the lower portion of the telescopic front suspension 26 at the end of the steering shaft. A handlebar 30 is fixed to upper bracket not shown and can rotate to both sides. A head light 32, a visor guard (not shown) and instrument cluster (not shown) is arranged on an upper portion of the head pipe 22. The frame member comprises a down tube that may be located in front of the IC engine 12 and extends slantingly downward from head pipe 22. The main tube 24 of the frame member is located above the IC engine 12 and extends rearward from head pipe 22. The IC engine 12 is mounted at the front to the down tube and a rear of the IC engine 12 is mounted at the rear portion of the main tube 24. In an embodiment, the IC engine 12 is mounted vertically, with a cylinder block extending vertically above a crankcase. In an embodiment, the cylinder block is disposed rearwardly of the downtube.
[020] The fuel tank 20 is mounted on the horizontal portion of the main tube 24. Seat rails are joined to main tube 24 and extend rearward to support a seat assembly 18. A rear swing arm 34 is connected to the frame member to swing vertically, and a rear wheel 16 is connected to rear end of the rear swing arm 34. Generally, the rear swing arm 34 is supported by a mono rear suspension 36 (as illustrated in the present embodiment) or through two suspensions on either side of the motor vehicle 10. A taillight unit (not shown) is disposed at the end of the motor vehicle 10 and at the rear of the seat assembly 18. A grab rail (not shown) is also provided on the rear of the seat rails. The rear wheel 16 arranged below seat 18 rotates by the driving force of the IC engine 12 transmitted through a chain drive (not shown) from the IC engine 12. A rear fender 38 is disposed above the rear wheel 16.
[021] Further, an exhaust pipe 40 of the vehicle extends vertically downward from the IC engine 12 up to a point and then extends below the IC engine 12, longitudinally along the vehicle length before terminating in a muffler 42. The muffler 42 is typically disposed adjoining the rear wheel 16.
[022] Figure 2 depicts a typical internal combustion engine 500 (ICE) of a two-wheeler vehicle in accordance with an embodiment of the present invention. The ICE 500 typically has a crankcase 100, a cylinder block 200 and a cylinder head 300. The crankcase 100 is essentially a housing which has a crankshaft. The cylinder block 200 is mounted on the crankcase by stud bolts (not shown). The cylinder block 200 has a bore in its center which houses a piston. Cylinder head 300 sits above the cylinder block 200 forming a combustion chamber combustion of fuel occurs in order for the vehicle to move. In addition to the piston, the cylinder block 200 also has an intake channel and an exhaust outlet. The intake channel receives air/ fuel mixture from fuel assembly of the vehicle. The exhaust outlet lets out the combusted mixture. The axially movable piston inside the bore of the cylinder block 200 is connected to the crankshaft by a connecting rod. The crankshaft, the connecting rod and the piston are connected in a way that reciprocating motion of the piston causes rotational motion of the crankshaft. Further, the ICE 500 also comprises a knock sensor 410 in accordance with an embodiment of the present invention. In an embodiment, the knock sensor 410 is mounted at an intake side 440 of the cylinder block 200. For instance, the intake side 440 of the cylinder block 200 is adjoining an intake pipe 450 extending towards the ICE 500 from a carburetor 430. In one embodiment, the ICE 500 receives an intake charge from the carburetor 430, while in another embodiment, the carburetor 430 can be replaced by a throttle body mounted with a electronic fuel injector (EFI). Often it is seen, due to structural modifications made in the combustion chamber, or due to wear and tear, combustion of the air/ fuel mixture also happens at places other than at a spark plug site. This out of place combustion leads to knocking of the ICE. Untreated knocking leads to irreparable damages to the ICE 500. Thus, the knock sensor 410 mounted on the ICE 500 is used to detect knocking caused in the combustion chamber.
[023] Figure 3 depicts a typical internal combustion engine 500 (ICE) of a two-wheeler vehicle in accordance with another embodiment of the present invention. In this embodiment, the knock sensor 410 is mounted at an exhaust side 480 of the cylinder block 200. For instance, the exhaust side 480 of the cylinder block 200 is disposed at a side opposite to the side of the cylinder block 200 that adjoins the intake pipe 450 extending towards the ICE 500 from a throttle body 460. In this embodiment, the ICE 500 receives an intake charge from the throttle body 460 mounted with an electronic fuel injector (EFI) 470, while in another embodiment the throttle body 460 can be replaced by a carburetor.
[024] Referring to Figures 4a and 4b showing a cylinder block 200. The cylinder block 200 has a bore 250 made therethrough. The bore receives an axially movable piston (not shown). The cylinder block 200, as the name suggests, is a block having four faces. Accordingly, the cylinder block 200 has first face 210. Referring to Figure 5 and Figure 7, the first face 210 has an exhaust outlet 212. Thus, combusted mixture from the combustion chamber of the ICE is let out from the exhaust outlet 212. The cylinder block 200 further has a second face 220. The second face 220 extends perpendicular to the first face 210. As seen in Figure 4a, Figure 4b, Figure 5 and Figure 7, the second face 220 has an adjacently made slot 222. The slot 232 receives a timing chain (chain) wherein the timing chain connects a cam shaft to a crank shaft.
[025] The cylinder block 200 has a third face 230. The third face 230 extends perpendicularly from the second face 220. Accordingly, the third face 230 is opposite to the first face 210. Further, the third face 230 has an intake aperture (not shown) made therethrough. As seen in Figure 4a and Figure 4b, the cylinder block 200 has an intake channel 232 which connects to the intake aperture on the third face 230 leading into the combustion chamber. The cylinder block 200 has a fourth face 240 which extends perpendicularly from the third face 230 and meets the first face 210. The fourth face 240 thus is opposite to the second face 220 of the cylinder block 200.
[026] Referring to Figure 4a, Figure 4b and Figure 7, the cylinder block 200 has a plurality of cooling fins 260. In order to cool the cylinder block 200 from heat generated due to combustion, the cooling fins 270 are formed around outer periphery of the cylinder block 200, wherein the outer periphery is defined by the first face 210, the second face 220, the third face 230 and the fourth face 240. The cooling fins 270 are configured such that, when the vehicle is in motion, the cooling fins 270 direct incident air towards the cylinder block 200.
[027] As shown in Figure 4a, Figure 4b, Figure 5 and Figure 7, the cylinder block 200 further has apertures 270a, 270b, 270c, 270d to receive stud bolts. The stud bolts are essentially mounting means used to mount the cylinder block 200 on the crankcase 100 of the engine 500. Since the stud bolts extend completely along length of the cylinder block 200 as shown in Figure 6, they provide an added stability to the cylinder block 200. Thus, there is least amount of vibrations experienced around the stud bolts when the vehicle is in motion.
[028] According to the present invention, the cylinder block 200 has a sensor mounting boss 400 formed on a corner between the first face 210 and the fourth face 240 of the cylinder block 200 or on a corner between the first face 210 and the fourth face 240 of the cylinder block 200. As shown in Figure 6, the sensor mounting boss 400 extends from a first end 401, which is inside the cylinder block 200, to a second end 402 wherein the second end 402 extends away from the cylinder block 200.
[029] In an embodiment of the invention, the sensor mounting boss 400 is placed close to the stud bolt 270a. More particularly, as shown in Figure 6, distance ‘F’ between surface of the stud bolt 270a and the first end 410 of the sensor mounting boss 400 is 0 mm to 15 mm.
[030] In another embodiment of the invention, as shown in Figure 4a, the sensor mounting boss 400 is essentially made discontinuous with at least one cooling fin present on the outer periphery of the cylinder block 200. Further, the sensor mounting boss 400 protrudes from the cylinder block 200 and is inclined at an angle of between 15° to 90° from an axial axis 280 of the cylinder block 200.
[031] In a further embodiment of the invention, as shown in Figure 4a, the sensor mounting boss 400 receives a knock sensor 410. The knock sensor 410 is mounted on the sensor mounting boss 400 by using a fixating means 420 such as nut, bots, screw etc.
[032] Referring now to Figure 8 which is a comparative characteristic graph showing the signal-to-noise ratio at 5000 rpm detected by the knock sensor 410, over frequency of vibration in a cylinder block 200. Accordingly, solid line as seen in the figure represents signal-to-noise ratio as detected by the knock sensor 410 when the sensor mounting boss 400 is formed on a corner between the first face 210 and the fourth face 240 of the cylinder block 200. On the other hand, dotted line as seen in the figure represents signal-to-noise ratio as detected by the knock sensor 410 when the sensor mounting boss 400 is formed on a corner shared between the third face 230 and the fourth face 240 of the cylinder block 200.
[033] Advantageously, since the sensor mounting boss 400 is formed close to the stud bolts, stability of the sensor mounting boss 400 is higher. Thus, the sensor mounting boss 400 and consequently the knock sensor 410, experience vibrations arising only from the combustion chamber and not due to the movement of the vehicle. In other words, when the sensor mounting boss 400 is formed on any of the aforementioned locations, all vibrations sensed by the knock sensor 400 would pertain to the knocking in the combustion chamber 250 of the cylinder block 200. Thus, as shown in Figure 8, this leads to higher signal-to-noise ratio detected by the knock sensor 410. Additionally, since the sensor mounting boss 400 is made discontinuous with the cooling fins 260, it ensures sufficient air flow around the knock sensor 410. Due to the air flow, the knock sensor 410 is cooled and is not greatly affected by the excessive damaging heat generated by the combustion chamber. Furthermore, when the sensor mounting boss 400 is formed on the aforementioned positions, it offers better serviceability of the knock sensor 410 present therein.
[034] 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.