FORM 2

THE PATENT ACT, 1970
(39 Of 1970)
&
THE PATENTES RULES, 2005
COMPLETE SPECIFICATION (See section 10, rule 13)
1. TITLE OF THE INVENTION
"Unit Pump Drive Mechanism for Common Rail Diesel Engine"
2. APPLICANT(S)
(a) Name : MAHINDRA & MAHINDRA LIMITED
(b) Nationality : Indian Company registered under the provisions
of the Companies Act, 1956
(c) Address : R & D Center, Automotive Sector,
89, M.I.D.C, Satpur, NASHIK - 422 007 Maharashtra State, India
3. PREAMBLE OF THE DESCRIPTION
COMPLETE
The following specification particularly
describes the invention and the manner
in which it is to be performed.

Field of invention
The present invention is related to unit pump drive mechanism.for common rail diesel engine. More particularly, the present invention is related to the unit pump drive mechanism of a diesel engine.
Background of the present Invention
Modern day diesel engine architecture especially for automotive vehicles includes common rail fuel injection system. Common rail fuel injection system is must feature to achieve new emission norms i.e. BS IV & beyond along with fuel economy. Common rail gives freedom to vary injection timing & quantity independent of RPM. It makes possible to optimize noise with more than two injections per strokes as per requirement. Therefore, existing engines are upgraded by replacing rotary fuel injection pump with unit pump with necessary modifications in the engine structure for achieving emission compliance, reduction in engine noise and achieving better fuel economy along with better drivability.
Up-gradation of existing engine with common rail fuel injection system is done by replacing rotary fuel injection pump by three plungers high pressure pump for achieving rail pressure beyond 1400 bar. In smaller capacity engines high pressure and flow requirement can be met by single plunger reciprocating pump called unit pump. This unit pump requires reciprocating motion for pumping action which is given by twin cam lobe generally integrated on valve train camshaft. This puts additional loads on valve train camshaft. If the existing engine with rotary fuel injection pump (FIP) is to be replaced with unit pump, it demands modification in crankcase casting, valve train camshaft, and drive gear to take up increased loads, crank, cam and FIP drive gear train lay out. All these modifications and arrangement of driving unit pump by valve train camshaft is feasible only if new engine is being designed. It requires high tooling cost and greater amount of time

for redesign. To get rid of this, a unique drive mechanism to run unit pump in the upgraded engine from the existing one is developed.
Objectives of the Present Invention
Object of the present invention is to provide unit pump drive mechanism, which is adaptable in existing engines to meet emission compliances.
Another object of the present invention is to provide a unit pump drive mechanism, which enables use of Common Rail system on existing engine without design changes in interfacing parts.
Still another object of the present invention is to provide a unit pump drive mechanism, which is low in cost as compared to existing engines to meet emission (BS IV) norms
Further object of the present invention is to provide a unit pump drive mechanism for unit pump that enables extension of life of the existing engine (BIO life of 3 lakh kms) and avoid obsolescence.
Brief description of the Figures
Further objectives and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein,
Figures la and lb show a general arrangement and parts of unit pump drive mechanism in accordance with the present invention;
Figure 2 shows oil supply lines for hydrodynamic lubrication of camshaft of the present invention;

Figure 3 shows drain passage facilitated for oil from cambox of figures la & lb; and
Figure 4 shows layout of assembly of unit pump drive mechanism, crankcase & drive gear.
Detailed description of the Present Invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
In general automotive diesel engines are fitted with rotary mechanical pumps. These pumps are having their own limitations, as mentioned above, to achieve emission compliance, reduction in noise, and lowering BSFC (break specific fuel consumption). To overcome these limitations the existing engines are upgraded using common rail (CR) diesel injection system. In this CR system reciprocating pump is used to increase the fuel pressure in common rail up to 1400 bar and above. This reciprocating high pressure pump needs drive system which gives reciprocating action through rotating camshaft.
This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring now to figure la, lb & figure 2, show a general arrangement and parts of a unit pump drive mechanism (1) for driving a fuel pump in accordance with the present invention. The unit pump drive mechanism (1) comprises a camshaft

(2), a cambox (7), a rear plate / thrust plate (3), an 'O' ring (4), a pin (5) for roller tappet locking, a member (15) and oil galleries (6). The camshaft (2) is a twin lobe camshaft and it is housed in the cambox (7). The camshaft (2) is supported by two hydro dynamically lubricated journal bearings (11- i) & (11- ii) and the thrust plate (3) is lubricated by engine oil. The 'O' ring (4) does the sealing at join faces of the thrust plate (3) and a unit pump (8). The oil galleries (6) enable supplying and draining the lubrication oil therethrough.
Referring now to figure 3. shows drain passage facilitated for oil from the cambox (7) of the present invention. The cambox (7) is designed to have proper clamping on to a crankcase flange (12). The crankcase flange (12) is configured to take load of drive torque & engine borne vibrations. The cambox (7) also sufficiently secures the unit pump (8) against hydraulic forces. The unit pump (8) is a reciprocating pump. The unit pump (8) is mounted on the cambox (7) with the member (15) therebetween in such a manner that its roller tappet (9) and plunger rod (10) gets reciprocating action from the twin lobes of the camshaft (2). A camshaft locking pin (5) is provided to restrict rotational movement of the roller tappet (9). Care has been taken in design that no side forces are coming on to the camshaftlocking pin (5). This entire drive mechanism assembly (1) comprising of the cambox (7), the camshaft (2) and the rear plate (3) is placed where earlier rotary pump used to get drive.
Referring now to figure 4 shows layout of assembly of unit pump drive mechanism (1), the crankcase flange (12) & a drive gear (13). The cambox (7) is mounted on the crankcase flange (12) and the drive gear (13) is placed on camshaft conical portion for gear clamping. Drive gear & conical portion is common with rotory pump for facilitating modularity. This arrangement makes the diesel engine design modular that means the same diesel engine can be fitted with Common Rati (herein after referred as CR) system as well as rotary fuel Injection pump (FIP) as per need / requirement.

Oil is supplied from engine main oil gallery to the unit pump driving mechanism (1) wherein it is supplied to the camshaft journal bearings (11), the thrust faces (3) & the roller tappet (9). Oil drain passages (not shown) have been provided for effective draining of the oil from the combox (7) back to crankcase. The drain passages have been designed to drain the oil without oil foaming & without addition of oil particles in blow by. This has been achieved by avoiding oil churning by cam lobe & oil draining along the walls of crankcase avoiding oil squirts. Endurance tests of unit pump driving mechanism (1) are complete & it is proved that this works very well & it out lasts engine B10 life of 3 Lakh kms. No leakage from any of the joint through out the tests indicates that while the unit pump driving mechanism (1) is sufficiently lubricated, oil draining is also satisfactory as per design intent.
Thus, the unit pump drive mechanism (1) of the present invention make it feasible to fit the unit pump on the crankcase by replacing the rotary pump and thereby upgrading the existing engine with CR system to comply with the targeted emission norms.
Advantages of the present invention
• Up-gradation of existing engine for meeting emission compliance, noise reduction and improved drivability without changes in interfacing parts is possible/achieved.
• No' maintenance for unit pump drive mechanism is required.
• It is a low cost solution and requires short duration for upgrading the existing engine.
• The mechanism is simple to design and manufacture.

It should be understood that the present invention is not to be limited by the exact details of the illustrated embodiment. However, it is to be taken as the preferred example of the invention and that various changes may be resorted to by a person skilled in the art without departing from the spirit of the invention. Also, the terminologies used herein are for the purpose of description and should not be regarded as limiting.

We Claim:
1. A unit pump drive mechanism for driving a fuel pump of an automobile engine, the mechanism comprising:
a cambox for enclosure;
a camshaft rotatably disposed in the cambox, wherein the camshaft having twin lobes configuration;
a thrust plate disposed over the cambox for securing the camshaft therein, wherein the thrust plate is lubricated by the engine oil;
a pair journal bearing disposed around the camshaft for lubricating and reducing friction thereof;
a unit pump disposed over the camshaft, wherein the twin lobes of the camshaft reciprocates the unit pump thereby pumping the fuel therethrough.
2. The mechanism as claimed in claim 1, further comprises a member, a plunger road, a roller tappet and a compression spring disposed between the camshaft and the unit pump.
3. The mechanism as claimed in claim 1, further comprises oil galleries for lubricating thereof.