Claims:WE CLAIM:
1. A hybrid engagement mechanism with faulty crank and milling prevention, said mechanism comprising:
at least one starter motor [1];
pinion [2];
ring gear [3];
a solenoid switch [4];
plunger [5]; and
engagement spring [6] to split the plunger [5] and pinion [2],
wherein power from the starter motor [1] is transferred to the engine through the pinion [2] which is engaged with the ring gear [3] of engine flywheel through the solenoid switch [4] only at the time of cranking,
wherein when the cranking signal is sensed, the solenoid switch [4] shifts the plunger [5] which thereby simultaneously moves the pinion [2] towards the ring gear [3] and aids closure of contacts [11 and 12],
wherein a low voltage is applied to the starter motor [1] once the solenoid switch [4] is energized, which enables the starter motor [1] to rotate with a soft torque even when contact closure is not achieved, thereby aiding the pinion [2] to slip into the ring gear [3] and achieve meshing,
wherein when there is obstruction to the pinion [2] travel due to abutment with ring gear [3] teeth face, engagement spring [6] enables plunger [5] to advance independent of the pinion [2] and close the contacts [11 and 12] and apply full power to the starter motor [1],
wherein the starter motor [1] overcomes friction between pinion teeth and ring gear teeth and causes the pinion [2] to rotate,
wherein when the pinion [2] reaches a position where there is no obstruction, the energy stored in plunger return spring [14] pushes the pinion [2] to engage with the ring gear [3], and
wherein hybrid engagement mechanism thus with both the soft engagement and engagement spring [6] mechanisms ensures successful engagement as per requirement.

2. The hybrid engagement mechanism as claimed in claim 1, wherein when the cranking signal is sensed, winding in the solenoid switch [4] is configured to provide a low voltage to the starter motor [1] even before the contacts [11 and 12] are closed, enabling soft rotation of the pinion [2] to overcome the face friction between pinion [2] and ring gear and engage with the ring gear [3].

3. The hybrid engagement mechanism as claimed in claim 2, wherein the low voltage causes current flow through the starter motor [1], which in turn develops a torque to rotate the starter motor [1] and pinion [2] by overcoming the friction between the pinion teeth and ring gear teeth.

4. The hybrid engagement mechanism as claimed in claim 3, wherein said torque before contacts [11 and 12] closure is lesser than the full torque of the starter motor [1].

5. The hybrid engagement mechanism as claimed in claim 1, wherein the engagement by the spring [6] mechanism is enabled only when the soft rotation of the pinion [2] cannot overcome the obstruction and hence the ring gear [3] wear rate is reduced, thereby enhancing the durability of the ring gear [3].
, Description:FIELD OF THE INVENTION
The present invention generally relates to a starter system for an engine, particularly to a starter system for an internal combustion engine with electromagnetically induced engagement mechanism to reduce faulty crank during abutment. More particularly, the present invention relates to a hybrid system with both soft engagement and engagement spring mechanisms. Further, the hybrid engagement system is configured to reduce ring gear wear rate, thereby enhancing the durability of the ring gear.

BACKGROUND OF THE INVENTION
Generally, starter motor is used to rotate or crank an internal combustion engine to the minimum required speed to trigger firing. The power from the starter motor is transferred to the engine through a pinion, which is engaged with a ring gear of engine flywheel only at the time of cranking. When DC power from the battery is applied to a solenoid switch, usually through a key-operated switch or "ignition switch", the solenoid pulls a plunger which in turn engages a lever that pushes out the drive pinion on the starter driveshaft and meshes the pinion with the ring gear on the flywheel of the engine. In addition, to engage the pinion with the ring gear, the solenoid pulls the plunger in such a way that it simultaneously closes the high-current contacts, thereby applying full system voltage to the motor and causing it to rotate the pinion and eventually the ring gear. Once the engine starts, the key-operated switch is opened, a spring in the solenoid assembly pulls the pinion away from the ring gear, and the starter motor stops as the plunger releases the high-current contacts.

In certain cases, there is a probability that the forward motion of the pinion teeth is halted due to the pinion getting obstructed while trying to mesh with the ring gear teeth creating a condition known as abutment. This results in non-closure of contacts, leading to failure of basic functionality of the starter. In addition to this, when windings of the solenoid are energized continually at this condition, irreparable damage occurs to the solenoid due to over-heating.

US6633099 discloses a coaxial starter motor assembly that includes a housing. An electrical motor is provided in the housing that has a rotatable armature shaft that is linked with a drive shaft. A pinion assembly is provided that is engageable at one end with the drive shaft and includes a pinion at the other end engageable with a flywheel of an engine. A return spring is provided that is positioned at least in part within the bore of the plunger of the solenoid assembly for moving the pinion assembly including the pinion away from engagement with the flywheel. However, said prior art is to disconnect the contacts irrespective of the position of the pinion.The prior art has a spring which aids the return of plunger to home position, even though the pinion is struck in extended position. This is to prevent permanent closure of contacts when pinion is mechanically struck forward.

US20130168974 discloses a solenoid in an engine starter assembly that includes an electromagnetic coil operable on a plunger coupled to a shift lever to move a pinion gear into contact with the engine ring gear. The solenoid is provided with a return spring to restore the plunger to an initial position in which the pinion and ring gears are disengaged, in the absence of a coil force. An over-travel spring resists movement of the plunger once a contact plate engages the electrical contacts. However, said prior art uses an additional spring to reduce the impact force of the plunger/pinion at the point of contact of the ring gear thereby reducing ring gear wear. Whereas the proposed invention reduces ring gear wear by preventing the application of full power to the starter by providing a soft rotation feature before the closure of high-current contacts.

Accordingly, there exists a need for a hybrid engagement system with both soft engagement and engagement spring mechanisms as per requirement to reduce faulty crank during abutment and to reduce ring gear wear rate.

OBJECTS OF THE INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the system of the present invention.

It is the primary object of the present invention to provide a starter system for an internal combustion engine with electromagnetically induced engagement mechanism to reduce faulty crank during abutment.

Another object of the present invention is to provide a hybrid engagement system with both soft engagement and engagement spring mechanisms as per requirement.

It is another object of the present invention, wherein the hybrid engagement system with both soft engagement and engagement spring mechanisms ensures successful engagement whenever required.

It is another object of the present invention, wherein the hybrid engagement mechanism reduces ring gear wear by preventing the application of full power to starter motor by providing soft rotation before the closure of high-current contacts, wherein during soft rotation, the starter motor rotates with a minimal torque which does not damage ring gear entry region.

It is another object of the present invention, wherein during soft engagement, pinion rotates with a lower torque before the closure of contacts, and is configured such that it indexes through the ring gear in case of obstruction and hence reduces ring gear wear rate, thereby enhancing the durability of the ring gear.

SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention, there is provided a hybrid engagement mechanism with faulty crank and milling prevention, said mechanism comprising:
at least one starter motor;
pinion;
ring gear;
a solenoid switch;
plunger; and
an engagement spring to split the plunger and pinion incase of abutment of the pinion,
wherein power from the starter motor is transferred to the engine through the pinion which is engaged with the ring gear of engine flywheel through the solenoid switch only at the time of cranking,
wherein when the cranking signal is sensed, the solenoid switch shifts the plunger which thereby simultaneously moves the pinion towards the ring gear and aids closure of contacts,
wherein a low voltage is applied to the starter motor once the solenoid switch is energized, which enables the starter motor to rotate with a soft torque even when contact closure is not achieved, thereby aiding the pinion to slip into the ring gear and achieve meshing,
wherein when there is obstruction to the pinion travel due to abutment with ring gear teeth face, engagement spring enables plunger to advance independent of the pinion and close the contacts and apply full power to the starter motor,
wherein the starter motor overcomes friction between pinion teeth and ring gear teeth and causes the pinion to rotate,
wherein when the pinion reaches a position where there is no obstruction, the energy stored in plunger return spring pushes the pinion to engage with the ring gear, and
wherein the hybrid engagement mechanism thus with both the soft engagement and engagement spring mechanisms ensures successful engagement as per requirement.

It is another aspect of the present invention, wherein when the cranking signal is sensed, winding in the solenoid switch is configured to provide a low voltage to the starter motor even before the contacts are closed, enabling soft rotation of the pinion to overcome the face friction between pinion and ring gear and engage with the ring gear.

It is another aspect of the present invention, wherein the low voltage causes current flow through the starter motor, which in turn develops a torque to rotate the starter motor and pinion by overcoming the friction between the pinion teeth and ring gear teeth.

It is another aspect of the present invention, wherein said torque before contact closure is lesser than the full torque of the starter motor.

It is another aspect of the present invention, wherein the engagement by the spring mechanism is enabled only when the soft rotation of the pinion cannot overcome the obstruction and hence the ring gear wear rate is reduced, thereby enhancing the durability of the ring gear.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: illustrates hybrid engagement mechanism in abutment condition according to the present invention.
Figure 2: illustrates hybrid engagement mechanism in contacts closure condition according to the present invention.
Figure 3: illustrates ring wear pattern comparison after durability test of 60000 cycles done in three samples.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES
The present invention as herein described relates to a starter system for an internal combustion engine with electromagnetically induced engagement mechanism to reduce faulty crank during abutment. Further, the present invention relates to a hybrid engagement system with both soft engagement and engagement spring mechanisms ensuring successful engagement whenever required. Advantageously, the hybrid engagement system is configured to reduce ring gear wear rate, thereby enhancing the durability of the ring gear.

Referring to Figures 1 and 2, the hybrid engagement mechanism of the proposed invention, comprising of at least one starter motor [1]; pinion [2]; ring gear [3]; a solenoid switch [4]; plunger [5]; and an engagement spring [6] to split the plunger [5] and pinion [2] when required, said engagement spring [6] in one embodiment is positioned in plunger operating rod [13]. Power from the starter motor [1] is transferred to the engine through the pinion [2] which is engaged with the ring gear [3] of engine flywheel through the solenoid switch [4] only at the time of cranking. The solenoid switch, preferably magnetic solenoid switch [4] in response to the cranking signal, shifts the plunger [5] which in turn simultaneously moves the pinion [2] towards the ring gear [3] and closes contacts [11 and 12], thereby applying full system voltage to the starter motor [1] and causes said starter motor [1] to rotate the pinion [2] and eventually the ring gear [3].

When there is obstruction to the pinion [2] travel due to abutment with ring gear [3] teeth face, soft engagement by the solenoid switch [4] enables rotation of the pinion [2] to engage with the ring gear [3] even before the contacts [11 and 12] closure. When the cranking signal is sensed, even before the contacts [11 and 12] are closed, winding in the solenoid switch [4] is configured to provide a low voltage to the starter motor [1]. The low voltage causes current flow through the starter motor [1], which in turn develops a mild torque to rotate the starter motor [1] and pinion [2] by overcoming friction between the pinion [2] and ring gear [3], said torque before contacts [11 and 12] closure is lesser than the full torque of the starter motor [1]. The solenoid switch [4] which enables the soft rotation of pinion [2] even before contacts closure [11 and 12] thereby aiding the pinion [2] to slip into the ring gear [3] and achieve meshing is known as soft engagement. During soft engagement, the pinion [2] is configured such that it indexes through the ring gear [3] in case of obstruction and hence reduces ring gear wear rate, thereby enhancing the durability of the ring gear.

When there is an obstruction to the pinion [2] travel which is strong enough such that it could not be overcome by the soft rotation, the engagement spring [6] enables separation of the plunger [5] from the plunger operating rod [13], allowing the plunger [5] to close the contacts [11 and 12] enabling the starter motor [1] to operate with full power and hence full rotation of the pinion [2] to engage with the ring gear [3] by compressing the engagement spring [6] and allowing the contacts [11 and 12] to close. The engagement spring [6] preload is such that it does not compress when there is no obstruction to the pinion [2] travel. When there is an obstruction during rotation of the pinion [2], the engagement spring [6] compresses thereby allowing the plunger [5] in aiding closure with contacts [11 and 12] and rotating the starter motor [1] with full power as shown in Figure 2. The starter motor [1] overcomes the friction between pinion teeth and ring gear teeth when it attains the full power and causes the pinion [2] to rotate. Once the pinion [2] reaches a position where there is no obstruction, the energy stored in plunger return spring [14] pushes the pinion [2] to engage with the ring gear [3].

Thus, when there is obstruction of pinion [2] travel due to abutment with ring gear [3] teeth face, the soft rotation ensures to engage with the ring gear [3]. When the obstruction is strong, the engagement spring [6] comes into action allowing the contacts [11 and 12] to close. Since the engagement by the spring [6] mechanism is enabled only when the soft rotation of the pinion [2] cannot overcome the obstruction, the wearing out of ring gear [3] teeth entry region is reduced, thereby enhancing the durability of the ring gear [3]. The hybrid engagement system thus with both soft engagement and engagement spring [6] mechanisms ensures successful engagement as per requirement.

In another embodiment, the engagement spring [6] can be located anywhere between the plunger pinion linkage. The locations include but not limited to drive sleeve [7], engaging lever [8], engaging lever support mould [9], and journal shaft [10].

In yet another embodiment, the pinion [2] spring can be modified to act as an engagement spring.

Durability Test Validation:
The hybrid engagement system of the present invention was validated by means of durability tests done in three samples and compared the wear pattern of the ring gear with the wear pattern in test involving pure soft engagement and pure direct engagement solenoids.
Test cycle:
Dead crank: 1 second
Live crank: 0.5 second
Cycle time: 30 seconds

The ring wear pattern comparison after durability test of 60000 cycles revealed that there were no faulty cranks throughout the test period and the ring gear wear was much less when compared with pure direct engagement type as shown in Figure 3.