DESC:FIELD OF THE INVENTION
The present invention is related to design of engine head and its overhang projections. The present invention also related to method of producing the engine head and its projections as a single piece; more particularly but not exclusively related to hollow projections.

BACKGROUND AND PRIOR ART
Internal combustion engines includes of components like engine head, block, carburettor, overhang projections like intake/ exhaust passages also called as manifolds. A flange of intake passage is fixed to the inlet port of the engine by appropriate fasteners during built up of the engine. A carburettor is connected to intake passage through a duct. A circular indentation is provided on the outer surface of intake passage for securely mounting the duct. The fuel charge from carburettor is fed to combustion chamber through this duct.

This arrangement bears many problems. One of the drawbacks is variation in surfaces of connecting portions of intake passage and intake port of engine head. This variation of joining surfaces creates disturbance in fuel charge supply route, thereby reducing the efficiency of the engine. Another drawback is that variation in the surfaces of connecting portions of exhausts passage and exhaust port. This variation at joining or connecting portion leads to leakage of exhaust gases. One more drawback is that as the engine head and intake passage are manufactured by different methods, the internal surfaces of both are different, this disturb smooth flow of fuel charge. This also decreases efficiency of engine.

Hence, to overcome above said drawbacks, it is recommended to make a single piece engine head with these passages.

There are some prior arts available in this field. Japanese patent application no 2000298901 discloses port structures of internal combustion engine where the end portion of intake port liner is integrally cast with engine head. However the port liner disclosed here is a different part and is of different material and having a flanged end. Here a separate intake port liner is kept in the mould while moulding process of engine head. But in this case the port liner has to be manufactured separately. Hence the productivity is hampered. Another disadvantage of this structure is a separate arrangement to be provided to locate the liner to in the head. Also there are chances of material ingress in the hollow portion of liner while casting. Heat dissipation problem also faced due to 2 different materials.

Normally a die casting method includes plurality of dies inserts of which some dies are moving and some are stationary. For example an pack of six die inserts may include five movable die inserts, one non-movable die insert. But, for casting the single piece engine head with intake passage with circular indentation, it is unrealistic to make it with five movable die inserts, as the overhang part of intake passage and circular indentation required on the intake passage do not allow this method .This is because the movable insert which makes the intake passage and its circular indentation does not allow any die insert moving in the direction of passage as this movement creates faults like undercutting .Also, the movable insert which moves inline with intake passage does not allow enough room for air escape, this leads to under filling at the segment of intake passage wall and the part gets discarded. Also, the movable die insert which creates circular indentation creates faults like undercut during return path. Also , this six movable die inserts method used to make single piece engine head with intake passage (with circular indentation or without circular indentation) may face problems like un-filling due to inadequate air venting & fast solidification of metal at the cavity segment of intake passage.

The movable inserts for making intake passage and other parts of engine head are stack of plates put together or a solid block.

There is always possibility of breakage of these plates if the length of these plates is more and thickness is less.

Also, it exerts a problem of lack of air vents. Further when the thickness of the casted part is less like intake passage wall portion & its circular indentation, it take out more heat from metal which leads to fast solidification of metal at thin portions. Therefore thin wall portion of intake passage & circular indentation may face problems like unfilling.

Also, as the projected length of intake passage is more in lateral direction, it is difficult to cast if as a single piece with engine head due to material un-filling and air venting problem.

Finally, considering the above limitations, it is difficult to make a single piece engine head with intake passage whether with circular indentation or without circular indentation by using known die casting processes.

Further the single piece engine head passage without comprising circular indentation requires machining of circular indentation after the casting process which need resources like man and machine.

Present invention tries to solve the problems in above prior arts.

OBJECTIVES OF THE INVENTION
In this view, one objective of the present invention to provide a single piece engine head with overhang projection, for example intake passage to facilitate the smooth flow of fuel charge by avoiding variation of profiles at joints and avoiding different surface pattern of separately manufactured parts.

An another objective of the invention is to provide a most cost effective method for producing of single piece engine head with intake passage.

An another objective of the present invention is to provide a most cost effective method for producing of single piece engine head with intake passage with circular indentation.

SUMMARY OF THE INVENTION
An engine head of an internal combustion engine comprising atleast an overhang projection wherein the said engine head is manufactured along with these overhang projections as a single piece.

The single piece engine head of internal combustion engine as decscribe above wherein the cyl head and overhang projections is provided with atleast one rib extending from cylinder head surface to the outer periphery of overhang projections.
The single piece engine head of internal combustion engine as decscribe above wherein projected length of overhang passage is 40 mm or more.

A method of producing single piece engine head with overhang projection includes multiple movable die inserts and a non-movable die insert in which at least one movable die insert & one non- movable die insert making the shape of overhang projection including shape of other peripheral portions of engine head nearby the overhang projection and having their centreline significantly orthogonal to the centreline of intake port of the engine head.

The said die inserts may be oriented in the upright direction or in lateral direction or in combination.

The said peripheral portions may be constructed by said die inserts left & right side and top & bottom portions peripheral to the overhang projection.

The said peripheral portions of intake passage may be connected to intake passage manufactured by said die inserts.

The upper and lower segments are provided with atleast one rib extending from cylinder head surface to the outer periphery of overhang projections.

According to another feature of invention, the method includes use of water jacket core to create water passage cavities in the engine head.

When two movable die inserts and one non-movable die insert are used, the said movable die inserts may be located in front of each other and non-movable insert may be located in separate direction.

The said two of the movable die inserts may be located in lateral direction and non-movable die insert may be located in upright direction.

When one movable die insert and one non-movable die insert is used, the said movable insert and non-movable insert may be located in front of each other.

The said movable and non-movable die inserts may be located in upright direction.

The non-movable die insert may be a lower die insert.

By the above said method, it is possible to manufacture a single piece engine head with overhang projection.

By the said method it is possible to manufacture a single piece engine head with overhang projection and circular indentation.

The method consist of two or three die inserts to form the structure of the single piece engine head with overhang projection with or without circular indentation along with other segments of engine head peripheral area of overhang projection.
According to another feature of invention, the structure of the overhang projection may be created through three die inserts, two die inserts being located in lateral direction, other being located in upright direction.

The die inserts located in lateral direction may be movable inserts and die insert located in upright direction may be non-movable insert.

According to another feature of invention, the structure of the overhang projection may be created through two die inserts, both die inserts being located in upright direction. One of the die insert may be movable die insert and other die insert may be non-movable.

According to another feature of invention, one of the die insert is provided with cavity from top side and another die insert is provided with cavity at bottom side forming corresponding ribs or supporting members on the manufactured part.

According to another feature of invention, the overhang projection is casted with only two die inserts namely top movable die insert and bottom non-movable die insert to minimise the parting lines.

The casting method used may be a low pressure die casting method as the gravity die casting method is a time consuming, costly process and gives less yield.

According to another feature of invention, the overhang projection as describe above may be an intake passage of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS
REFERENCE NUMBER TABLE
PART NUMBER PART NAME PART NUMBER PART NAME
1 ENGINE HEAD 20a LOWER NON-MOVING DIE INSERT
2 INTAKE PORT LINER 21 IGNITION PLUG AREA
3 - 22 CHAIN TUNNEL AREA
4 - 23 -
5 - 24 -
6 - 25 -
7 - 26 -
8 - 27 -
9 - 28 -
10 SINGLE PIECE ENGINE HEAD 29 SIDE PORTION
11 INTAKE PASSAGE 30 SIDE PORTION
12 CIRCULAR INDENTATION 31 EXHAUST SEGMENT STRUCTURE
13 TOP RIB 32 REAR SEGMENTS
14 BOTTOM RIBS 33 -
15 - 34 COMBUSTION CHAMBER
16 LEFT MOVABLE INSERT 35 ROCKER CAM AREA
116a MOVABLE INSERTS OF STACK PLATE 36 INTAKE SAND CORE
17 RIGHT MOVABLE DIE INSERT 37 EXHAUST SAND CORE
17a MOVABLE INSERTS 38 WATER JACKET SAND CORE
18 REAR INSERT 39 CHAIN TUNNEL SAND CORE
19 UPPER INSERT 40 EXHAUST MUFFLER ATTACHING AREA
19a UPPER MOVING DIE INSERT 41 CAVITIES
20 LOWER INSERT 42 ROCKER SAND CORE

Figure 1is a front view of engine head and integrally cast intake port with intake liner as per prior art.
Figure 2 is a top side isometric view of single piece engine head with intake passage without circular indentation according to one of the embodiment of the invention.
Figure 3a shows a top side isometric view of single piece engine head with intake passage comprising a circular indentation and ribs according to another embodiment of the invention.
Figure 3b is a bottom side isometric view of figure 3a.
Figure 3c is a rear side isometric view of figure 3a
Figure 3d is a left side isometric view of figure 3a
Figure 4 is an exploded view of die arrangement as per one of the embodiment of invention.
Figure 5 is top view of die arrangement shown in figure 4.
Figure 6 is a cross section view of die arrangement shown in figure 5.
Figure 7 is detail view ‘Y’ of die insert for intake passage with circular indentation shown in figure 6.
Figure 8 is detail view ‘Y’ of die insert for intake passage without circular indentation shown in figure 6.
Figure 9 is an isometric view of die arrangement as per one of the embodiment of invention.
Figure 10 is sectional view of die arrangement as shown in figure 9
Figure 11 is sectional view of die arrangement as shown in fig. 6 illustrating creation of intake passage with solid inserts.
Figure 12 is sectional view of die arrangement illustrating creation of intake passage with stack plate inserts according to yet another embodiment of invention.

DETAILED DESCRIPTION
Figure 1 shows a front view of engine head (1) and integrally cast intake port liner (2) according to one prior art. This discloses port structures of air cooled internal combustion engine where the end portion of intake port liner (2) is integrally cast with engine head (1). However the port liner (2) disclosed here is a different part and is of different material. Here a separate intake port liner (2) is kept in the mould while moulding process of engine head (1). But in this case the port liner (2) has to be manufactured separately. Hence the productivity is hampered.

Figure 2 shows the single piece engine head (10) with intake passage (11) without circular indentation, top rib (13) and bottom ribs manufactured by using method according to invention which avoid above said problems.

Figure 3a, 3b, 3c and 3d shows the single piece engine head (10) with intake passage (11) and with circular indentation (12), top rib (13) and bottom ribs (14)manufactured by using method according to invention.

As the projection length of intake passage (11) is more in lateral direction Z (for example 40 mm or more), it is difficult to cast it as a single piece with engine head (10) due to material un-filling and air venting problem.

To avoid this problem, according to one of the embodiment or aspect of the invention as illustrated in figures 3a to 3d, ribs are provided at top and bottom surface of intake passage. Cavities in the die inserts for bottom ribs (14) help to increase the filling rate of material and reduce un-filling problem. Cavity in the die inserts for top rib (13) helps to reduce air venting problem while filling of material. These provisions of ribs also strengthen the single piece intake passage. Similar ribs may be provided at sideway surface of the intake passage.

As the passage (11) is to be cast as single piece with engine head (10), the die insert forming this intake passage (11) cannot be located and moved in the direction parallel to the direction of intake port or intake passage (11), because the die insert while on its return path will create an under cut on the intake passage (11) and circular indentation (12) of the intake passage.

In one embodiment of the present invention as shown in figures 4 to 11, the means of the method consist of three movable inserts marked as (16, 17, 18) capable of moving in lateral direction, one upper movable insert (19) capable of moving in upright direction and one non-movable lower insert (20). The internal surfaces of these inserts are so designed as to manufacture desired shape of the engine head (10) when the casting sequence is decided using these means. The movable insert (16) is located at left side and movable die insert (17) is located at right side while looked from intake port (i.e. from ‘Z’ direction as shown in figure (3a) of engine head (10). The molten material provided through the lower side of the die. The movable inserts (16, 17) upper insert (19) and lower insert (20) are so designed as to create structure of ignition plug opening (21, chain tunnel region (22) and intake passage(11) and side sections ( 29, 30) as shown in figures 3a and 3b.

The rear insert (18) creates the exhaust segment structure (31) and rear segments (32) as shown in figure 3a-3d. The lower insert (20) apart from creating segment of intake passage (11) creates structure of combustion chamber (34) as shown in figure 3b. The upper insert (19) creates structure of rocker cam area (35) as shown in figure 3c.
It can be seen that from the figure 4-11, the creation of intake passage (11) with circular indentation (12) from the movable inserts (16, 17) and bottom insert (20). The intake sand core (36) required to create structure of passage (11) is supported by bottom insert (20). The figure 6 and 7 show sectional and detail views for creation of intake passage (11) and circular indentation (12). The detail view Y shows the profile of die insert (17) which creates segment of the circular indentation (12). To circumvent the problem of unfilling, a normal slit say for example 0.2 mm is kept in between mating faces of movable inserts (17, 18) and lower insert (20) for air venting purpose. In addition the thickness of movable inserts (17, 18) is kept minimum in this area for less heat removal from molten metal while cavity filling, as shown in figure 10.

It can be seen that the direction of movable inserts (16, 17) is significantly orthogonal to the direction of intake passage (11) in lateral plane and direction of lower insert (20) and upper die insert (19) are significantly orthogonal to the direction of intake passage (11) in upright plane .These inserts create the shape of passage (11) and segments of engines head (10) around the intake passage (11). But these angles can be changed according to the direction of intake passage (11) with respect to engine head (10).

According to another embodiment of the present invention as shown in figure 9 and 10, the creation of single piece intake passage (11) with engine head (10) and segments of engine head around engine head can be produced through, two die inserts (19, 20) by making suitable modifications in the structure of internal surfaces of these die inserts. These die inserts are located in upright direction. The upper die insert (19) is moving die insert and lower die insert (20) is non-moving. Despite from contributing in making lower portion of the intake passage (11), the lower die insert(20) create the combustion chamber (34) and lower profile. In addition the lower die insert supports the intake sand core (36), exhaust sand core (37), water jacket sand core (38), rocker sand core (42) and chain tunnel sand core (39). The molten material supplied through the lower side of the die inserts. The upper die insert (19) creates upper segment of intake passage (11), the Rocker cam area (35) & partial chain tunnel area (22) of engine head (10). The left side insert (16) & right side insert (17) located in lateral direction creates the first ignition plug area (21), side portion (29) and chain tunnel area (22) & side portion (30) respectively. The rear side insert (18) creates the exhaust muffler attaching area (40) & side portions (32). Fig 11 shows a section view showing the creation of intake passage 11.

The relevant faces of die inserts are aligned to water jacket sand core (38) to create the water passage cavities (41) in the engine head. These cavities (41) are necessary to flow the water through them to cool the engine as the embodiment shown is for water cooled engine. These water passage cavities (41) are provided as per engine design necessity.

The above referred features of die inserts make the process smooth without creating any faults like under cut on intake passage & its circular indentation and unfilling in walls of intake passage engine head. In addition, the structure of single piece engine head with passage created with this method increase the heat dissipation efficiency of the engine head and reduce the weight of engine.

Also, this method use of only five die inserts as against use of 6 die inserts according to prior art. Thus, this method can be used for multicavity die set up in which multiples of single piece engine heads with passage can be made in one cycle of the casting.

The movable inserts 16a and 17a are the assembly of stack plates as shown in the figure 12. There is a normal gap between mating faces of these stack plates. Due to these gaps, there may be many parting lines formed on outer surface of intake passage (11). These parting lines are not desirable especially at circular indentation area and have to be flushed manually.

To avoid this, according to another embodiment of the present invention, the intake passage is casted with only two die inserts namely upper moving die insert 19a and lower non-moving die insert 20a having a single solid block as shown in the figure 11. Due to this only two parting lines are formed at side portion of intake passage and are easy to remove.

The probable steps of the above described method are illustrated as below.
1. Dies are in open state: - all the movable inserts (16, 17, and 18) are in pull back state & upper moving die insert (19) at top most state.
2. Position of sand cores: - Position of water jacket (38), Intake (36), exhaust (37) & chain tunnel (39) sand cores on lower die insert (20).
3. Closing of movable die inserts :- The entire movable inserts (16, 17, 18) in forward position.
4. Position of sand core: - Position of Rocker sand core (42) on ignition plug side moving insert (16) chain tunnel sand core (39).
5. Die closing state: - upper die insert (19) in lower position closing the die.
6. Feeding of molten metal: - The cavity is filled by feeding the molten metal at low pressure from opening in the lower die insert.
7. Cooling: - A solid part is created as per profile of the cavity after the molten metal is cooled.
8. Die opening state: - all the movable die inserts (16, 17, 18) are in pullback state & upper moving die insert (19) at top most state. Then a casted part is ejected from upper moving die insert.
A method with similar steps may be used for other embodiments of the invention.

The single piece intake passage (11) without circular indentation (12) with engine head (10) can also be produced with above said method by doing required changes in the profile of relevant die inserts.

The above said method eliminates different parts and process & assembly procedures necessary to assemble intake passage and engine head. Also, it increases flow of fuel change to the combustion chamber and increases efficiency of engine.

The above said method is capable of creating any form of single piece engine head with intake passage by doing relevant changes in internal surfaces of die inserts and selecting appropriate combination of moving die insert and non-moving die insert to produce required shape.

The present invention is not limited to any embodiment described above. Other modifications obvious to those skilled in the art are within the scope of the present invention. The applicant also relies on the provisional specification and drawings annexed to the provisional specification in support of this specification.
,CLAIMS:
1. An engine head of an internal combustion engine comprising overhang projections and having circular indentation on it; wherein the said engine head is manufactured along with at least one overhang projection as a single piece.
2. The single piece engine head of internal combustion engine as claimed in claim 1; wherein the cyl head with overhang projection is provided with atleast one rib extending from cylinder head surface to the outer periphery of overhang projections.
3. The single piece engine head of internal combustion engine as claimed in claim 2; wherein length of overhang projection is at least 40 mm.
4. The single piece engine head of internal combustion engine as claimed in claim 3; wherein the overhang projection is an intake passage of the engine.
5. A method of producing single piece engine head with overhang projection includes multiple movable die inserts and a non-movable die inserts; wherein at least one movable die insert & one non-movable die insert forming the shape of overhang projection including shape of other sections of engine head nearby the overhang projection and said die inserts having their centreline significantly orthogonal to the centreline of intake port of the engine head:
6. A method as claimed in claim 5; wherein the said die inserts are located in the upright direction or in lateral direction or in combination.
7. A method as claimed in claim 5; wherein peripheral part of overhang projection are left & right side and upper & lower segments peripheral to the overhang projection are constructed by said die inserts .
8. A method as claimed in claim 7; wherein the said peripheral part of overhang projection are connected to overhang projection constructed by said die inserts.
9. A method as claimed in claim 7; wherein the said upper and lower segments are provided with atleast one rib extending from cylinder head surface to the outer periphery of overhang projections constructed by said die inserts.
10. A method as claimed in claim 5; wherein method includes use of water jacket core to create water passage cavities in the engine head.
11. A method as claimed in claim 5; wherein method includes two movable die inserts and one non-movable die insert.

12. A method as claimed in claim 11; wherein said movable inserts are located opposite to each other in same plane and non-movable insert is located in the plane orthogonal to plane of movable die inserts.
13. A method as claimed in claim 12; wherein said movable inserts are located in lateral plane and said non-movable insert is located in upright plane.
14. A method as claimed in claim 5; wherein casting process includes one movable die insert and one non-movable die insert.
15. A method as claimed in claim 14; wherein said one movable insert and said non-movable insert are located opposite to each other in same plane
16. A method as claimed in claim 14; wherein said movable insert and said non-movable insert are located in upright plane.
17. A method as claimed in claim 5; wherein one of the die insert is provided with cavity from top side and another die insert is provided with cavity at bottom side forming corresponding ribs or supporting members on the manufactured part.
18. A method as claimed in claim 5; wherein the outer surface of overhang projection is casted with only two die inserts namely upper moving die insert and lower fixed die insert.
19. A method of manufacturing single piece engine head with overhang projection as claimed in any of the preceding claims; wherein the method is low pressure die casting.
20. A method of manufacturing single piece engine head with overhang projection as claimed in any of the preceding claims; wherein the overhang projection is an intake passage.