DESC:TECHNICAL FIELD
[001] The embodiments herein generally relate to camshaft assembly in automotive engine and more particularly but not exclusively to an assembled camshaft formed of a plurality of parts assembled together to drive a fuel injector pump, a plurality of valves (intake and exhaust) and a vacuum pump.

BACKGROUND
[002] Conventionally, an engine assembly includes a technology in which cams corresponding to intake valves and exhaust valves of an internal combustion engine are provided on camshafts for opening and closing the intake and exhaust valves. In a Single Over Head Cam engine a single camshaft is shared between the intake system and the exhaust system. In a Double Over Head Cam engine, a separate camshaft is arranged for each system, i.e., one camshaft is provided for the intake system and another camshaft is provided for the exhaust system i.e., the valve operating cams rotate together with the camshaft, and as these valve operating cams rotate, the cam noses of the valve operating cams apply pressure to the intake and exhaust valves, thus driving the valves between open and closed position. Conventionally, a typical cast iron camshaft, the camshaft main body and the valve operating cams are integrally formed.
[003] The conventional camshaft driving the fuel injector pump includes an integrated cam lobe for operating the fuel injector pump. In order to drive the fuel injector pump the camshaft must have adequate strength and hence the entire camshaft is made of strong materials like steel which increases the cost of camshaft due to the material and heat treatment.
[004] Further, if the high pressure fuel pump were arranged protruding upward in the vicinity of the front end portion of the engine, sufficient distance must be ensured between the upper end of the high pressure fuel pump and the bonnet (i.e., engine hood) which would interfere with the degree of freedom in design for obtaining a structure that would protect a pedestrian in the event of contact with a pedestrian. On the other hand, if the high pressure fuel pumps were arranged protruding upward in the vicinity of the rear end portion of the engine, there is a possibility that the high pressure fuel pump would interfere with the dash panel (i.e., the panel that isolates the engine room from the cabin interior). To avoid this interference, the design of the dash panel or the high pressure fuel pump may have to be newly modified.
[005] Therefore, there exists a need for a camshaft that can drive a fuel injector pump and a vacuum pump. Furthermore, there exists a need for a camshaft that can eliminate the aforementioned drawbacks.

OBJECTS
[006] The principal object of an embodiment of this invention is to provide a camshaft assembly having a separate fuel injector pump driving cam assembled on a camshaft main body to drive a fuel injector pump, a plurality of valves, and a vacuum pump.
[007] Another object of an embodiment of this invention is to provide the fuel pump driving cam assembled onto a camshaft main body by press-fitting.
[008] Yet another object of an embodiment of this invention is to provide a slot at first end of the camshaft main body to connect a vacuum pump.
[009] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF DRAWINGS
[0010] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0011] FIG. 1 is an exploded view depicting the camshaft, fuel injector pump and vacuum pump according to an embodiment of the invention as disclosed herein;
[0012] FIG. 2 depicts an cross sectional view of the camshaft assembled with the fuel injector pump and vacuum pump according to an embodiment of the invention as disclosed herein;
[0013] FIG. 3 depicts an assembled view of the camshaft with the fuel injector pump and vacuum pump according to an embodiment of the invention as disclosed herein;
[0014] FIG. 4 is an exploded view depicting the camshaft, cylinder head, fuel injector pump and vacuum pump according to an embodiment of the invention as disclosed herein; and
[0015] FIG. 5 depicts an assembled view of the camshaft with the cylinder head, fuel injector pump and vacuum pump according to an embodiment of the invention as disclosed herein.

DETAILED DESCRIPTION
[0016] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0017] The embodiments herein achieve a camshaft assembly having a separate fuel injector pump driving cam assembled on a camshaft main body to drive a fuel injector pump and a vacuum pump. Further, embodiments herein achieve the fuel pump driving cam lobe assembled onto the camshaft main body by press-fitting. Referring now to the drawings, and more particularly to FIGS. 1 through 5, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0018] A cylinder head of an automotive engine assembly is provided with a camshaft assembly according to this example embodiment. More specifically, the cylinder head is mounted to an upper surface of a cylinder block, and a camshaft assembly is mounted to the upper side of this cylinder head. A plurality of intake valves and exhaust valves, and various parts of a valve operating mechanisms are assembled to the cylinder head. The camshaft assembly is integrally assembled to the upper sides of the cylinder head by bolts or other such means.
[0019] With reference to FIG. 1, the camshaft assembly 100 includes a camshaft main body 102 defining a first end 104 and a second end 106, a fuel injector pump driving cam lobe 108, a fuel tappet 110, a housing 112 for FIP assembly, a fuel injector pump (FIP) 114, at least one intake valve cam, at least one exhaust valve cam, and a cylinder head 124.
[0020] In an embodiment, the camshaft assembly 100 is designed to drive a Fuel Injector Pump (FIP) 114 and a vacuum pump 126 in addition to valve actuation. In an embodiment, the camshaft assembly 100 according to the present disclosure is illustrated in FIGS. 2-3. The camshaft assembly 100 includes a camshaft 102 that extends from the first end 104 to the second end 106. The camshaft 102 is a tube-like structure and includes a plurality of bearing support structures 116 and plurality of valve operating cams 118 distributed along the camshaft 102 between the first end 104 and the second end 106. The bearing support structures 116 provide the bearing surface for the support of the camshaft assembly 100 within the engine structure, e.g., cylinder head 124. As the camshaft assembly 100 is rotated, the valve operating cams 118 act to open the intake and/or exhaust valves. In an embodiment, each bearing structure is provided with a bearing cap 120 to secure the bearing structure firmly to the cylinder head 124.
[0021] In an embodiment, the camshaft main body 102 is made up of chilled cast iron. However, it is also within the scope of the invention to provide any type of material for fabricating camshaft main body 102 without otherwise deterring the intended function of the rotation as can be deduced from this description and corresponding drawings.
[0022] In an embodiment, the camshaft assembly 100 includes the fuel injector pump driving cam lobe 108 assembled separately on the camshaft main body 102 to drive the fuel injector pump 114 and the vacuum pump 126. In an embodiment, the fuel injector pump driving cam lobe 108 is assembled onto the camshaft main body 102 by press-fitting. The separate fuel injector pump driving cam lobe 108 makes it possible to reduce over-all packaging space.
[0023] In another embodiment, the fuel injector pump driving cam lobe 108 is formed of a predetermined shape selected from a group consisting of elliptical, circular, eccentric, oval, snail, pear, and hexagonal. Further, the fuel pump driving cam lobe 108 is made up of induction hardened steel. The separate fuel injector pump driving cam lobe 108 is configured to take a high contact stress while driving fuel injector pump for upto 1600bar injection pressure. However, it is also within the scope of the invention to provide any type of material and hardening process for fabricating the fuel injector pump driving cam lobe 108 without otherwise deterring the intended function of the rotation as can be deduced from this description and corresponding drawings.
[0024] FIG. 4 is an exploded view depicting the camshaft 102, the cylinder head 124, the fuel injector pump 114 and the vacuum pump 126 according to an embodiment of the invention as disclosed herein. In an embodiment the camshaft assembly 100 includes a fuel injector assembly coupled radially above the fuel injector pump driving cam lobe 108 at the first end 104. The fuel injector assembly includes a housing 112 defining a first opening axially to the camshaft main body 102 and a second opening radially above the fuel injector pump driving cam lobe 108. In an embodiment, the first opening of the housing is configured to receive the fuel injector pump driving cam lobe 108 i.e. the fuel injector pump driving cam lobe 108 is enclosed in the housing 112. Further the fuel injector assembly includes a second opening to receive the fuel tappet 110. The fuel tappet 110 is configured to slide on the fuel injector pump driving cam lobe 108. A reciprocating motion achieved from the motion of the fuel tappet 110 is passed to the fuel injector pump 114. In an embodiment, the fuel injector pump 114 is mounted to a predetermined position using a mounting flange and plurality of bolts.
[0025] In an embodiment, the camshaft main body includes a slot 122 to receive the vacuum pump 126 axially at the first end 104. The vacuum pump drive slot 122 is machined in the camshaft main body 102 while the fuel injector pump driving cam lobe 108 is press fit around it. This gives advantage in packaging length. In an embodiment, the camshaft assembly includes a low-pressure oil passageway for flow of oil from the camshaft main body 102 to the vacuum pump 126. With this design of camshaft assembly 100 the overall engine length is reduced, which improves engine packaging in vehicle as shown in FIG. 5.
[0026] In an embodiment, a method of assembling a camshaft assembly 100 includes step of: providing a camshaft main body 102 having a first end 104 and a second end 106 (step 201). The method further includes defining a plurality of valve operating cams between the first end 104 and the second end 106 of the camshaft main body 102 (step 203). Further, the method includes attaching a fuel injector pump driving cam lobe 108 to the camshaft main body 102 at the first end 104(step 205). The fuel pump driving cam lobe 108 is attached to the camshaft main body 102 by press-fitting. Furthermore, the method includes coupling a fuel injector assembly radially above the fuel injector pump driving cam lobe 108. In addition, the method includes coupling a vacuum pump 126 fluidically to the camshaft main body 102 at first end 104. The camshaft main body 102 includes at least one slot 122 at the first end 104 to receive the vacuum pump 126 axially.
[0027] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Referral Numerals
Camshaft assembly 100
Camshaft main body 102
First end 104
Second end 106
Fuel injector pump driving cam lobe 108
Fuel tappet 110
Housing 112
Fuel injector pump 114
Bearing support structure 116
Valve operating cams 118
Bearing cap 120
Slot 122
Cylinder head 124
Vacuum pump 126
,CLAIMS:CLAIMS
We claim,
1. A camshaft assembly 100 comprising:
a camshaft main body 102 defining a first end 104, and a second end 106;
a plurality of valve operating cams 118 distributed between the first end 104 and the second end 106 of the camshaft main body102;
a fuel injector pump driving cam lobe 108 assembled onto the camshaft main body 102 at the first end 104;
a fuel injector assembly radially coupled above the fuel injector pump driving cam lobe 108; and
a vacuum pump 126 fluidically coupled to the camshaft main body 102 at first end 104;
wherein
the fuel pump driving cam lobe 108 is assembled to the camshaft main body 102 by press-fitting;
the camshaft main body 102 includes at least one slot 122 at the first end 104 to receive the vacuum pump 126 axially.

2. The camshaft assembly 100 according to claim 1, wherein the fuel injector pump driving cam lobe 108 is formed of induction hardened steel.
3. The camshaft assembly 100 according to claim 1, wherein the camshaft main body 102 is made of chilled cast iron.

4. The camshaft assembly 100 according to claim 1, wherein the camshaft assembly 100 includes a plurality of bearing support structures 116 distributed between the first end 104 and the second end 106 of the camshaft main body 102.

5. The camshaft assembly 100 according to claim 1, wherein the plurality of bearing support structures 116 are provided with a bearing cap 120 at each bearing structure.

6. The camshaft assembly 100 according to claim 1, wherein the fuel injector pump driving cam lobe 108 is formed of a predetermined shape selected from a group consisting of elliptical, circular, eccentric, oval, snail, pear, and hexagonal.

7. The camshaft assembly 100 according to claim 1, wherein the fuel injector assembly includes:
a housing 112;
a first opening in the housing 112 to receive the fuel injector pump driving cam lobe 108;
a second opening in the housing 112 to receive a fuel tappet 110; wherein the fuel tappet 110 is provided in communication with the fuel injector pump driving cam lobe 108; and
a fuel injector pump 114 in communication with the fuel tappet 110.

8. The camshaft assembly 100 according to claim 1, wherein the fuel injector assembly includes the fuel injector pump 114 having reciprocating motion as the fuel tappet 110 slides on the fuel injector pump driving cam lobe 108.

9. The camshaft assembly according to claim 1, wherein the camshaft assembly 100 includes predefined oil passage communicating with the vacuum pump 126.

10. A method 200 of assembling a camshaft assembly comprising:
providing a camshaft main body 102 having a first end 104, and a second end 106;
defining a plurality of valve operating cams 118 between the first end 104 and the second end 106 of the camshaft main body 102;
attaching a fuel injector pump driving cam lobe 108 to the camshaft main body 102 at the first end 104;
coupling a fuel injector assembly radially above the fuel injector pump driving cam lobe 108; and
coupling a vacuum pump 126 fluidically to the camshaft main body 102 at first end 104;
wherein
the fuel pump driving cam lobe 108 is attached to the camshaft main body 102 by press-fitting;
the camshaft main body 102 includes at least one slot 122 at the first end 104 to receive the vacuum pump 126 axially.