Claims:WE CLAIM:

1. A method of spray cooling with lubricating oil of a stator coil of an ACG in an IC engine with ACG having a rotor (8) and a stator (10), with the rotor (8) fitted on a crank shaft LH (6) of the IC engine with a key (7) and a hexagonal Flange bolt (14) and with the stator (10) fitted onto the engine cover (9) with a hexagonal bolt (13) and further the arrangement also at least including a crank shaft RH (1), a crank pin (5), a crank pin bearing (4), a washer (2) and an oil sump, and wherein the locking bolt (14) is adapted to rotate alongwith the crank shaft, the said method comprising of:

- forming an oil passage in crank shaft RH (1) to receive the pumped lubricating oil from an oil feed,

- forming an oil hole in the crank pin (5) to receive the pumped lubricating oil from crank shaft RH (1) and allow the flow around the crank pin bearing (4), and also around the clearance of washer (2) and downwardly towards the oil sump,

- forming another oil passage (x) in crank pin (5) to direct the oil flow from the crank pin (5) towards the crank shaft LH (6),

- forming another oil passage (y) in crank shaft LH (6) to receive the directed oil flow from the crank pin (5) oil passage (x),

- forming another oil passage (z) in bolt (14) to receive the directed oil flow from the crank shaft LH (6) oil passage (y) and allow the oil flow towards stator coil (10),

- thereby creating an additional passage for oil jet splashes through the inner surface of the stator coil beyond the passage for oil jet splashes on the outer surface of the stator coil.

2. The method of spray cooling of stator coil of ACG in an IC engine, as claimed in claim 1 wherein the bolt (14) is arranged to have atleast one linear internal hole and including atleast one radial opening at one of the across flat sides of the bolt head.
, Description:Field of Invention:

This invention is relating to an internal combustion engine and which IC engine is fluid cooled.

Prior art:

In prior art, the stator cooling is by splashing lubricant oil on the stator coils. In prior art, “Lubrication” is advantageously exploited to create cooling effect on the engine parts such as heat generated by piston, cylinder and bearings also to a large extent. There are many lubrication systems such as

a) Splash system
b) Forced feed system
c) Splash system and forced feed system

In prior art, the cooling of stator is splashing oil onto the stator, which splashing action of oil maintains a fog or mist of oil that drenches the inner parts of the engine including the stator, alongwith bearing, cylinder walls, pistons, piston pins, gears etc. Alternatively ‘oil’ can be directed through crankshaft through guided path and under desired pressure. This method of splashing does not allow good coverage of oil splash over substantial surface of stator coil.

Object of Invention:

The main object of the invention is to design a cooling system for stator cooling of an IC engine which is simple and compact.

The other object of the invention is to design the cooling system in which cooling is uniform and thereby providing even cooling to the stator.

The other object of the invention is to design cooling system which is capable of removing excess heat from actual heat generated in the stator.

The other object of the invention is to remove heat at a faster rate.

The other object of the invention is to remove excess heat from the engine with the help of a flowing fluid with a standardized design for various applications of IC engines.

The other object of the invention is to provide cooling system which can be used in both small and big engines for preventing excess heat generation in stator.

Description of Invention:

An internal combustion engine generally consists of an Alternator cum generator (ACG) unit that generates alternating electrical current while the engine is in operation. Existing arrangement of crankshaft and ACG in engine is shown in Fig1. Stator cooling is very critical and overheating stator can result in reduced generating capacity or even catastrophic failure of the generator.

Existing Arrangement of prior art is :

Figure 1 Part Number
Item Description
1. Crankshaft RH
2. Washer
3. Connecting Rod
4. Bearing – Crankpin
5. Pin Comp- Crank
6. Crankshaft LH
7. Key Wodruff
8. Rotor assembly
9. Cover
10. Stator assembly
11. Plug
12. Washer
13. Bolt
14. Hex Socket Head Cap Screw
15. Pin Comp – Crank (stator cooling)
16. Crankshaft LH (stator cooling)
17. Bolt (stator cooling)

The ACG effectively consists of 2 main parts namely the rotor (8) and stator (10). The rotor is fitted onto the crankshaft LH(6) of the internal combustion engine on a tapered surface, timed with respect to Top dead centre with a key(7) and axially arrested in position using a hexagonal flange bolt(13). The stator (10) is fitted on to the engine cover (9) using hexagonal bolts (14). The oil flow path is shown in dash arrows. Lubrication oil pumped through the crankshaft RH (1) passes through the connecting hole and enters the internal diameter of the crankpin (5). Then the oil flows through the oil hole in crank pin(5) and lubricates the crank pin bearing(4). The oil also lubricates the clearance around washer (2) before dropping down in to oil sump.

In this arrangement, when crankshaft rotates, the rotor rotates along with the crankshaft and alternating electrical current is produced. Strength of this current depends on the electrical loads with which the vehicle operates. The higher the electrical loads the higher the strength of alternating current. Generation of current heats up the stator coil (10). The stator coil is generally cooled by the lubricating oil that splashes on the coil. Under certain conditions, may be due to improper cooling or excess heat generation, the stator coil temperature increases beyond the safe limit for the coil and results in failure of the coil leading to loss of primary function of ACG.

The design as disclosed is not restricted to a particular IC engine used in a particular vehicle configuration with a particular cooling demand. There is no need to “redesign” for each cooling demand level but it can be very easily “adapted” to ensure proper heat transfer, volumetric coolant flow and directional flow control, amongst other consideration. The consequence of engine running too hot is serious such as eg. Pre-ignition resulting in damage of engine, or heat fatigue of components such as burnt valves or burnt pistons or warping and factures of components. In fact it can even lead to failure of lubrication system itself by oil break down etc.

The new arrangement as per invention is described below:-

In an attempt to keep the coil temperature within allowable safe limit, there is defined a new methodology/arrangement to cool the stator coil. The new arrangement is as shown in Fig2.

The engine typically includes a generator having a stator and a rotor. The stator needs to be cooled by a cooling component to reduce the operating temperature of the stator. These generator, as is known, employing a rotor and a stator create an electric current. Specifically as the rotor rotates within the stator, the movement creates an alternating current of electricity that is largely dependent upon the speed of rotation. Typically the stator is mounted to a housing which structurally supports the crankshaft and the rotor is attached to the crankshaft. So that the rotor is rotated as the crankshaft turns. Due to deficiency and difficulty with cooling the generators i.e cooling the stator, most conventional generators suffer generating capacity. Hence there is a need to design a generator that can supply adequate capacity but do not suffer the heat generation issues. However in prior art, the biggest problem is with required increase in power generating capacity comes a potentially damaging increase in stator temperature. Hence the main aim of the invention is to design a stator cooling method without increasing the bulk of engine, or the weight of engine but be able to accommodate an alternative arrangement to provide a novel cooling arrangement, such that the arrangement will advantageously provide a novel cooling arrangement for a generator to enable an increased power generating capabilities.

It is this known system splashing lubricating oil that has been utilized to create an arrangement of delivering lubricating oil to the stator in a novel manner, wherein, the lubricating oil is that distribution of lubrication oil is ‘uniform’ and not randomly ‘splashed’ around the stator zone which is a good but simple design of oil circulation system with the increase in cooling efficiency of stator, and thereby the engine which causes increase in life time of engine. Further due to ‘uniform’ distribution and ‘uniform’ cooling, this coolant oil based cooling system has minimized the happening of hot spot that is difficult to avoid when applying ‘random’ cooling ‘splash’.

Modification and inventive step of the invention (Figure 2):-

Figure 2 Part Number
Item Description
1 Crankshaft RH
2 Washer
3 Connecting Road
4 Bearing – Crankpin
5 Pin Comp – Crank
6 Crankshaft LH
7 Key Woodruff
8 Rotor assy
9 Cover
10 Stator assy
11 Plug
12 washer
13 Hex Socket Head Cap Screw
14 Bolt
X Oil passage in crank pin (5)
Y Oil passage in Crank Shaft LH (6)
Z Oil passage in Bolt 14

Thus is one aspect of the invention, the new arrangement includes modification to the existing parts namely crank pin (5), crankshaft LH (6) and bolt (14). Crank pin (5) and crankshaft LH (6) are modified in such a way that oil passage is established between crankshaft LH (6) and crankshaft RH (1). The bolt (14) is modified so as to pass the oil out of crankshaft LH (6) and thereby spray oil on the stator coil (10) (figure 2). The above features and advantages and other features and advantages of the present invention are radially apparent from the detailed description of few embodiments for carrying out the invention when taken in connection with the accompanying drawings.

Working of the invention (Figure 2):-

Lubrication oil pumped through the crankshaft RH (1) passes through the connecting hole and enters the internal diameter of the crankpin (5). Then the oil flows through the oil hole in crank pin and lubricates the crank pin bearing(4). The oil also lubricates the clearance around washer (2) before dropping down in to oil sump. At the same time, because of modifications in new arrangement, some amount of oil entering the internal diameter of crank pin bore goes through the connecting passage and enters the hole in Crankshaft LH(6) reaching to the bolt (14). This bolt has an internal hole and opening radially at the one of the across flat sides of the bolt head. Oil exiting through this hole hits against the stator coil (10) inner diameter directly. As the locking bolt (14) continues to rotate along with the crankshaft, the oil jet splashes throughout the inner surface of stator coil and takes away heat from the coil.

This arrangement allows us to maintain the stator coil temperature within safe limits. The design achieves an improvement in the cooling effect of stator and thereby enjoys a wide range of applications in automotive and even heavy duty IC engines in view of obtaining cooling system performance, which arrangement can be used to regulate engine temperature i.e., most efficient temperature which shall allow engine to warm up in cool weather and maintain engine in optimum range.

Testing & results of the invention:-

The heat transfer has been analyzed:

Coil temperature was measured at 2 locations on the stator coil with original and modified arrangement, keeping all other parameters same. The measurement results are tabulated in Table 1. Temperature reduction of about 14% to 20% was observed with modified arrangement and temperature of stator coil is within safe limits.
Table 1 - test results

Temperature measurement on stator coil
Maximum temperature of stator coil in original arrangement
(without oil jet)
Maximum temperature of stator coil in modified arrangement
(with oil jet)
Location 1 100% 86%
Location 2 100% 80%

These and other features, aspects and advantages of the present invention have been disclosed intended to describe and illustrate the invention but which above embodiments are not to limit the invention.
The examples and embodiments are provided only for the purpose of understanding and none of them shall limit the scope of the invention. All variants and modifications as will be envisaged by skilled person are within the spirit and scope of the invention.