Title of Invention

A GEAR SHIFT SYSTEM FOR QUICKER START OF DIESEL ENGINE BY INCREASING THE RATE OF RAIL PRESSURE IN THE COMMON RAIL SYSTEM

Abstract A Gear Shift system for Diesel engine for increasing the rate of rail pressure in the common rail system comprises of a starter, an alternator both coupled operably to the diesel engine, an engine ECU operably coupled to engine speed sensor and a Gear train arrangement with two sets of gears, each set with two wheels, operably coupled between the crank shaft and the pump, such that first wheel of each set of gears mounted on the crank shaft meshes with the second wheel mounted on the pump shaft. A movable synchromesh collar mounted between the two gear wheels mounted on the crank shaft alongwith gear shift mechanism which operable by ECU for moving or locking the synchromesh collar with the selected gear based on mode of operation. An engine ECU also includes a logic circuits stored within and communicate with gear shift mechanism and ECU is further configured to have a predetermined duration at start so as to minimize the wait time during starting.
Full Text INTRODUCTION:
The Work taken up here explores the possibility of using a gear shift arrangement between the crankshaft and the high pressure pump such that initially during the start of the engine, the high pressure pump is accelerated in order to increase the rate of rise of rail-pressure to achieve reduction in the time waited for achieving the minimum rail pressure after engine synchronization has been achieved.
PRIOR ART:
Existing Conventional systems use methodologies to reduce the time taken to achieve synchronization by introducing sophisticated cam profiles, but does not focus on reducing the time taken to build minimum rail pressure faster and hence there is no prior art found for this concept with the literature survey performed.
FIELD OF INVENTION:
The idea basically aims at aiding the diesel engine during starting by increasing the rate of rise of rail pressure in the common rail system during the start of the engine. By accelerating the build up of rail pressure initially the minimum injection pressure can be obtained earlier thus resulting in a quicker start and conservation of energy taken from the battery by the starter for this period. This can yield benefits in the form of quicker engine starts and reduced consumption of energy from the battery.
OBJECT OF INVENTION:
The objective of the work undertaken is to optimize the starting time of the common rail diesel engine and reduce the Energy consumed from the Battery by reducing the time waited for the minimum rail pressure to build up after Engine Synchronization has been achieved.
Main Improvements achieved in the invention:
• As the proposed system enables to achieve minimum rail pressure earlier, it would aid in quicker starts.

• Due to reduction in the time waited for minimum rail pressure to be achieved, the energy consumed by the starter motor from the battery during the starting of the engine is reduced.
• Offers possibility of introducing newer advancements in Engine Synchronization like multi-teeth cam profile.
• Hence cam profiles used for gasoline can also be used here reducing the costs.
• With the usage of the proposed system, effective cold starts can be achieved.
DESCRIPTION OF THE INVENTION:
We hereby describe the invention with accompanying drawings:
Fig 1 is the schematic diagram of the proposed system, wherein the components are numbered as follows:
1. Engine unity.
2. Gear Train.
3. Alternator.
4. Crank Shaft.
5. Pump.
6. Battery.
7. Fly Wheel.
8. Switch.
9. Starter
10. Gear Shift.
Fig 2 illustrates the graphical representation of pressure against time characteristics, wherein If starter rating is p KW then energy consumed during the period waiting for the Pmin to be achieved after the Engine Synch has been achieved is
Δ E = j Δ p dt The time is along the horizontal axis and pressure is marked along vertical axis.

Fig 3 illustrates the Realistic Target Characteristic of the proposed system, wherein time is along the horizontal axis and pressure is marked along vertical axis.
As is known in conventional common rail diesel systems, there is a considerable waiting time to start the engine even after synchronization is achieved due to slower rate of rail pressure build up. As the High Pressure Pumps in the common rail systems are driven by the engine crankshaft, the rate of build up of pressure in the high pressure pump is directly a function of engine speed. Hence the time taken to build the minimum injection pressure in the pump during starting is directly influenced by the inertia of the moving components in the Engine. For this time period as explained in the above figure (tl-t0) Δt, the starter motor drives the engine and hence energy is consumed from the battery as explained in the note in the above figure. This energy consumed can also be represented in the form of the area under the starter power curve between the time tl and t0.
Due to the fact that the time taken to build up rail pressure being larger than that of engine synchronisation, new advancements to achieve Faster Engine Synchronisation is not introduced. Hence it is very clear that unless there is a way to achieve minimum injection pressure faster, it would not be possible to reduce the waiting time and also the energy consumed from the battery by the starter.
Hence with the implementation of the proposed system there is a good possibility of introducing newer advancements in the Engine synchronization which can enable much quicker engine starts.
The objective of the concept proposed is to move the current rail pressure build up characteristic represented by the red line as close as possible to the ideal characteristic represented by blue line in such a way that the time waited for achieving the minimum rail pressure to start the injection after engine synchronization being achieved is reduced. By reducing the aforesaid time period the energy consumed from the battery by the starter to crank the Engine for every engine start can be reduced.
In the present invention a starter coupled operably to the diesel engine.

In the present invention an alternator coupled operably to the diesel engine
In the present invention an engine ECU operably coupled to engine speed sensor, and the engine.
In the present invention the gear train arrangement comprising of 2 gear combination sets coupled between the crank shaft and the pump, along with gear shift mechanism, first wheel of each of the two gear sets is mounted on the crank shaft and second wheel of each of the two gear set is mounted on the pump shaft, and a movable synchromesh collar mounted on the crank shaft between the two gear wheels mounted on the crank shaft,
In the present invention a gear shift mechanism operably coupled to the engine ECU and the synchromesh collar for moving the synchromesh collar between the gear wheels and locking the synchromesh collar with one of the two gear wheels mounted on crank shaft, and
In the present invention the gear train arrangement characterized in having a first set of gears and a second set of gears, each set further comprising of two gear wheels, one gear wheel mounted on pump shaft meshing with a corresponding gear wheel mounted on crank shaft;
In the present invention the gear shift mechanism characterized in that it is operable by a engine ECU capable of moving the synchromesh collar along the crank shaft between the first gear and the second gear wheel and locking the synchromesh collar with the selected gear based on the mode of operation;.
In the present invention the system is characterized in locking the synchromesh collar with the one of the two gear wheel mounted on crank shaft,
In the present invention the system is characterized in that engine ECU having a logic circuits stored within and communicate with gear shift mechanism;
In the present invention the system is characterized in engine ECU coupled to and for controlling the gear shift mechanism

In the present invention the said system characterized in that the gear trains are positioned between the shaft of the high pressure pump and the crank shaft and thereby specified drive speed is dependent directly on the gear ratio,
In the present invention the said system characterized in that gear train mechanism drives the pump until the engine reaches a predetermined rpm, after which engine ECU commands gear shift to drive pump at lower second speed,
In the present invention the said system characterized in that the gears transfer the mechanical power from crank shaft to pump drive shaft,
It is also expected that this idea would be more appealing when it is applied in the case of Large engines where the starter capacity would be higher, volume of the high pressure circuit is also high and hence the effective energy consumed would be considerable.
The amount of energy conserved per engine start is (AE - e), where e is the energy consumed for energizing the Gear shift mechanism. Hence over a considerable number of Engine starts the stress on the battery could be reduced which would improve the life of the battery.
The limitation on the faster acceleration of the rail pressure build up is from the mechanical construction of the high pressure pump and also depends very much on the ability of the High Pressure Pump's design and construction to withstand a faster acceleration.
So to accelerate the build up of rail pressure better, a small modification is proposed, where in a new gear shift arrangement is introduced between the crankshaft and the high pressure pump drive. This arrangement would have two gear trains between the Crankshaft and the pump drive with different gear ratios separated by a small synchromesh collar.
During starting of the engine, one set of gears would be chosen which would drive the high pressure pump at a better rate than the conventional systems, enabling the high pressure pump to be driven faster and hence a quicker build up of rail pressure. Once the engine picks up, the synchromesh collar is locked with the other set of gears, so that the high pressure pump is driven

as in the conventional systems. The Design of the gear and the exact moment of shifting from the one gear train to the other for driving the high pressure pump is to be calibrated case by case.
In conventional cases,
the starter to crankshaft ratio 15:1 (approx)
And crankshaft to the pump drive ratio is 2:1 (approx)
Then starter drives the pump indirectly at 30:1 (approx)
If n is the number of rotations required for building the minimum injection pressure Pmin
Then time taken to achieve Pmin is
tl = n/{1/30 of the starter speed} Mathematically the objective of the design of the gear system can be written as
Then time taken to achieve Pmin is
tl = n / { 1/x of the starter speed} where x So when x reduces tl reduces At reduces AE reduces.
The effective gear ratio has should be maintained at 1/x only during the initial starting of the Engine in order to have faster build up of rail pressure, but once the engine starts, the gear ratio should be shifted to the conventional l/30.The design also insists on keeping the energy consumed by the gear shft mechanism minimum to maximize the amount of energy saved per engine start.

Documents:

1016-che -2006 claim.pdf

1016-che -2006 complete description.pdf

1016-che -2006 correspondance -others.pdf

1016-che -2006 drawings.pdf

1016-che -2006 form 1.pdf

1016-che -2006 form 26.pdf

1016-che -2006 form 3.pdf

1016-che -2006 form 5.pdf

1016-CHE-2006 AMENDED CLAIMS 24-12-2013.pdf

1016-CHE-2006 CORRESPONDENCE OTHERS 24-12-2013.pdf

1016-CHE-2006 ABSTRACT.pdf

1016-CHE-2006 CORRESPONDENCE OTHERS.pdf


Patent Number 258641
Indian Patent Application Number 1016/CHE/2006
PG Journal Number 05/2014
Publication Date 31-Jan-2014
Grant Date 27-Jan-2014
Date of Filing 12-Jun-2006
Name of Patentee Robert Bosch India Limited
Applicant Address 123, Industrial Layout, Hosur Road, Koramangala, Bangalore 560 095
Inventors:
# Inventor's Name Inventor's Address
1 Mr. Varadharajan Raman 123, Industrial Layout, Hosur Road, Koramangala, Bangalore 560 095
PCT International Classification Number F02M51/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA