TECHNICAL FIELD

The subject matter described herein, in general, relates to an electronic starting system for an internal combustion engine of a vehicle, and in particular, relates to soft engagement of a pinion with a ring gear using an electronic control.

BACKGROUND

An electric starting system is used for self starting an internal combustion (IC) engine. The electric starting system employs a starter motor for cranking the IC engine. Low power from a battery is applied to a solenoid when a key-operated switch is turned on to a start position. The solenoid enables the movement of a pinion on the starter motor's shaft by means of a lever, thus causing the pinion to mesh with a ring gear on a flywheel of the IC engine. Subsequently, the solenoid closes high-current switch contacts or main contacts, thereby connecting the starter motor to the battery so that the starter motor starts the IC engine.

Typically, the solenoid includes two windings. The first winding is used to move the pinion and the second winding is used to retain the pinion in meshing with the ring gear. However, the use of two windings in the solenoid increases manufacturing costs of the solenoid, further, the solenoid is supplied with the high power when the main contacts arc closed to crank the IC engine through the starter motor. This results in overheating of the solenoid windings and affects the reliability of the solenoid. Furthermore, the design of the solenoid having two windings is often unreliable due to the possibility of failure of either coil of the windings.

In the present system, when the pinion is completely engaged with the ring gear, the starter motor is supplied with the high power for cranking the IC engine. However, in an event of
engagement failure, the rotation of the starter motor at the high power damages the teeth of both the pinion and the ring gear. Also, such an engagement failure at full power leads to excessive noise. An engagement process takes up finite time to the extent of delaying ignition process, thereby causing the \C engine to start slowly.

Therefore, there is a long felt need for facilitating a soft engagement of the pinion with the ring gear smoothly to prevent the engagement failure. The soft engagement is a process of slowly engaging the pinion with the ring gear when the pinion is not in proper engagement with the ring gear, a condition known as tooth-to-tooth abutment, without causing impact, noise, and wear and tear.

Further, it is desirable that the system also prevents overheating of the solenoid and subsequent malfunction of the starting system.

SUMMARY

The subject matter described herein is directed to an electronically controlled starting system (hereinafter referred as electronic starting system) for an internal combustion (1C) engine. The electronic starting system includes a starter motor assembly, which further includes a solenoid, a pinion on drive assembly, and a ring gear for starting the IC engine. The electronic starting system facilitates a soft engagement of the pinion with the ring gear by controlling the power supply to the solenoid and the starter motor. The electronic starting system further includes an electronic control unit and a sensor mounted on the solenoid. The electronic control unit regulates the power to the solenoid and the starter motor based on the response from the sensor. The electronic control unit supplies regulated power through two switches such that a first switch is connected to the solenoid and a second switch is connected to the starter motor.

The soft engagement of the pinion with the ring gear through an electronic control reduces the dependence on mechanical parts, and ensures reliable and smooth engagement of the pinion with the ring gear.. Further, the electronic control for supplying regulated power to the solenoid and the starter motor in response to the sensor input prevents overheating of the solenoid and the starter motor thereby increasing their durability and reliability.

These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRKIF DESCRIPTION OF DRAWINGS
The above and other features, aspects, and advantages of the subject matter will become better understood with regard to the following description, appended claims, and accompanying drawings where:

Figure 1 illustrates a sectional view of an exemplary starter motor assembly in an electronic starting system for an internal combustion engine.

Figure 2 schematically illustrates an electronic starting system.

Figure 3A schematically illustrates an exemplary electronic control system in the electronic starting system of Figure 2 according to a first embodiment of the present subject matter.

Figure3B schematically illustrates the electronic control system of Figure 2 according to a second embodiment of the present subject matter.

Figure 3C schematically illustrates the electronic control system of Figure 2 according to a third embodiment of the present subject matter.

DFTAILED DESCRIPTION
An electronic starting system for a vehicle controlled by an electronic control unit (ECU) for providing soft engagement through sensors and switches is described herein. The electronic starting system includes a solenoid, a starter motor, and the ECU for starting an internal combustion (IC) engine. The power supply from a battery actuates the starter motor to facilitate the engagement of a pinion and a ring gear coupled to a flywheel. The electronic starting system further includes a sensor mounted on the solenoid for monitoring the engagement of the pinion with the ring gear. The ECU provides controlled power, to the starter motor for controlling the engagement of the pinion with the ring gear in accordance with the sensor input. The electronic starting system employs a first switch and a second switch to provide controlled power respectively to the solenoid and the starter motor, and also controls switching of the switches.

When the pinion is not in proper engagement with the ring gear the sensor input to the ECU is indicative of a tooth-to-tooth abutment condition. In response to the sensor input, the ECU controls the switching time of the second switch so as to regulate the supply of power to the starter motor. The regulated power supply to the starter motor enables the pinion to engage smoothly with the ring gear. Upon the complete engagement of the pinion with the ring gear, the sensor provides input to the ECU for indicating the engagement of the pinion with the ring gear.

Thereupon the ECU feeds the regulated power to the solenoid through the first switch such that the pinion remains in engagement with the ring gear.

The solenoid used in the electronic starting system has a single winding. The single winding employed in the solenoid results in design simplification of the solenoid and hence reduces the overall manufacturing cost of the solenoid. Further, an electronic control of the starling system using ECU prevents overheating of the solenoid by supplying regulated power to the solenoid through switches.

This feature of providing regulated power to the starter motor reduces noise caused during the cranking of IC engine of the vehicle. In addition, the electronic starting system ensures quick completion of the pinion engagement with the ring gear so that the IC engine starts quickly. Further, the electronic starting system prevents an event of engagement failure, thereby averting any damage to a variety of mechanical parts, such as a flywheel, of the vehicle.

Figure 1 illustrates a sectional view of an exemplary starter motor assembly in an electronic starting system for an internal combustion (IC) engine in accordance with the present subject matter.

The starter motor assembly 100 in an electronic starting system includes a starter motor 102, which further includes an armature assembly 104, a drive assembly 106, and a solenoid assembly 108. The drive assembly 106 includes a pinion 110, which is mounted on an armature shaft 112 using a plurality of mechanisms already known in the art, which further is able to rotate and move axially on the armature shaft 112. When the pinion 110 engages with a ring gear (not shown in the figure) mounted on a flywheel (not shown in the figure) of an IC engine and the starter motor 102 is powered, the IC engine is cranked. The solenoid assembly 108 is employed for actuating the movement of the pinion 110 on the armature shaft 112 using pinion shift lever 114 connected to a plunger 116, which is a part of the solenoid assembly 108. The solenoid assembly 108 also includes a sensor 118 for monitoring the engagement of the pinion 110 with the ring gear (not shown in the figure).

Figure 2 schematically illustrates the working of an exemplary electronic starting system lor the internal combustion engine.

The electronic starting system 200 for starting the IC engine generally includes the starter motor 102 and a solenoid assembly 108 (not shown in this figure). The solenoid assembly 108 employs a single winding solenoid 202. The plunger 116 is capable of moving linearly with respect to the longitudinal axis of the solenoid 202 is such that the movement of the plunger 116 moves the pinion 110 on the armature shaft 112. The pinion shift lever 114 is connected to the plunger 116 at one end and on the other end is connected to the armature shaft 112. The pivoting of the pinion shift lever 114 facilitates translation of motion in opposite directions across its two ends.

The electronic starting system 200 further includes an electronic control unit (ECU) 206. A battery 204 supplies power to the starter motor 102 and the solenoid 202. The ECU 206 supplies a regulated power from the battery 204 to the solenoid 202 through a first switch 208, and to the starter motor 102 through a second switch 210. In an implementation both the switch are electronic switches.

In an implementation, when a key operated starter switch is turned ON, the battery 204 supplies power to the solenoid 202, thereby energizing the solenoid 202. The energized solenoid 202 draws the plunger 116 inwards. The inward movement of the plunger 116 pulls the pinion shift lever 114 towards the solenoid 202, thereby moving the pinion 110 on the other end of the pinion shift lever 114 on the armature shaft 112. This enables the pinion 110 to engage with a ring gear 212, which is mounted on to a flywheel 214.

In an event of tooth-to-tooth abutment, that is, when the pinion 110 teeth touch the teeth of the ring gear 212 and the pinion 110 does not engage with the ring gear 212, the movement of the plunger 116 and the pinion 110 is stopped. Under this condition, the ECU 206 supplies the low power to the starter motor 102 through the second switch 210. The power supply is regulated by employing pulse width modulation (PWM) technique to the second switch 210. Thus, the average power to the starter motor 102 through the second switch 210 is reduced. The low power applied to the starter motor 102 causes slow rotation of the pinion 110 until the pinion 110 is engaged with the ring gear 212. The rotation of the ring gear 212 cause the flywheel 214 to rotate.

Further, when the pinion 110 and the ring gear 212 are engaged completely, the inward movement of the plunger 116 is completed or stopped. Upon completion of the inward movement of the plunger 116, the ECU 206 regulates the supply of power to the solenoid 202 by reducing the power supplied to the solenoid 202 from the high power to the low power through the first switch 208. The low power is supplied by employing PWM technique to the first switch 208 in a manner similar to the one discussed as above. Simultaneously, the ECU 206 facilitates an increase in the power supplied to the starter motor 102 thereby providing the high power to the starter motor 102. Accordingly, the armature and correspondingly, the pinion 110 through the armature shaft 112 rotate at a higher speed. This, in turn, results in rotation of the flywheel 214 coupled to the ring gear 212..

Further, when the key operated starter switch is turned OFF, the power supply to the solenoid 202 is ecased thereby de-energizing the solenoid 202. The de-energized solenoid 202 then pushes the plunger 116 outwards using a plurality of mechanisms.

Figure 3A schematically illustrates an exemplary electronic control system in the electronic starting system of Figure 2 according to a first embodiment of the present subject matter.

The electronic control system 300 in the electronic starting system 200 as discussed in Figure 2 includes the ECU 206, the first switch 208 and the second switch 210 for regulating the power supply to the starter motor 102 and the solenoid 202 from the battery 204. The electronic control system 300 achieves this function by employing a sensor 118 to monitor the inward movement of the plunger 116. The sensor 118 is mounted on the solenoid 202 and generates electric signals to the KCU 206 in response to the movement of the plunger 116. In the present embodiment, the sensor 118 mounted on the solenoid 202 is a contact sensor which includes electrical contacts as a pair of fixed contacts 304-1 and 304-2 and a movable contact 306. The contacts 304-1, 304-2, and 306 collectively act as a sensor for detecting the completion of the plunger 116 movement and it also act as an electrical path to supply the power to the starter motor 102. The electrical paths are provided between the starter motor 102 and the battery via the second switch 210 for supply of the low power, and via the sensor 118.

When the key operated starter switch is turned ON, the ECU 206 senses its activation. The ECU 206 then closes the first switch 208 and supplies the high power from the battery 204 to the solenoid 202. thereby energizing the solenoid 202. The energized solenoid 202 causes the inward movement of the plunger 116 towards itself, thereby pushing the pinion 110 towards the ring gear 212 through the pinion shift lever 114, as explained in detailed description of Figure 2. This movement of the pinion 110 towards the ring gear 212 can get the pinion 110 into a tooth-to-tooth abutment with the ring gear 218.

Under the tooth-to-tooth abutment condition, the inward movement of the plunger 116 is not complete leading to non-closure of the fixed contacts 304-1 and 304-2 with the movable contact 306 in the sensor 118 located on the solenoid 202. Thus, the sensor 118 sends an electric signal to the ECU 206 indicating the non-closure of the fixed contacts 304-1 and 304-2 with the movable contact 306. Upon receiving the electric signal from the sensor 118, the ECU 206 regulates the power delivered by the battery 204 to the starter motor 102 to a predetermined level by modulating the second switch 210.

Upon receiving the low power, the starter motor 102 rotates the pinion 110 slowly such that the pinion 110 gets into proper engagement with the ring gear 218, thereby completing the inward movement of the plunger 116. At the instance when the inward movement of the plunger 116 is complete the fixed contacts 304-1 and 304-2 are electrically closed by the movable contact 306. Upon the closure of the fixed contacts 304-1 and 304-2 and the movable contact 306 the sensor 118 sends an electric signal to the ECU 206 to switch off the second switch 210. Once the second switch 210 is switched off the ECU 206 facilitates application of the high power to starter motor 102 from the battery 204 through the electrical circuit completed by the closure of the fixed contacts 304-1 and 304-2, and the movable contact 306. The application of the high power to the starter motor 102 rotates the pinion 110 and the ring gear 212 and the fly wheel 214 at a high speed and thereby starting the IC engine.

Simultaneously, the low power is applied to the solenoid 202 through the first switch 208 by employing the PWM technique as already explained un Figure 2. The solenoid 202 then facilitates holding of the pinion 110 near the ring gear 212 after the pinion 110 is disengaged from the ring gear 212 when the IC engine has started. A regulated low power can also be applied to the first switch 208 during the engagement process to minimize the impact of the pinion 110 on the ring gear 212.

Figure 3B schematically illustrates the electronic control system of Figure 2 according to a second embodiment of the present subject matter.

As discussed in Figure 2, the inward movement of the plunger 116 is stopped during tooth-to-tooth abutment. This stops the fixed contacts 304-1 and 304-2 from being closed by the movable contact 306. The sensor 118 sends an electric signal to the ECU 206 indicating the non-closure of the fixed contacts 304-1 and 304-2 and movable contact 306. The ECU 206 upon receiving the electric signal from the sensor 118 turns on the second switch 210 to facilitate the transfer of the low power from the battery 204 to the starter motor 102.

In accordance with the second embodiment, the second switch 210 is directly connected to the starter motor 102 and provides both the low power and the high power to the starter motor 102. The sensor 118 acts as a means for detecting completion of the plunger 116 movement without providing the electrical path for the high or the low power. The sensor 118 is a non-contact sensor such as an active infra-red sensor, capacitance detection sensor, passive optical detection sensor, thermal detection sensor, or combinations thereof.

The second switch 210 uses the PWM technique for the transfer of the low power, as discussed in Figure 2. The low power applied to the starter motor 102 enables the completion of the plunger 116 travel by slowly engaging the pinion 110 with the ring gear 212.

Upon completion of the inward movement of the plunger 116 the fixed contacts 304-1 and 304-2 are electrically closed by the movable contact 306. An electric signal is sent by the sensor 118 in response to the electric contact to the ECU 206. The ECU 206 then provides the high power from the battery 204 to the starter motor 102 through the second switch 210. The duty cycle of the second switch 210 is enhanced to supply the high power from the battery 204 to the starter motor 102.

Figure 3C schematically illustrates the electronic control system of Figure 2 according to a third embodiment of the present subject matter.

According to the third embodiment of the present subject matter, the electronic control system 300 includes an additional relay 308 for providing the high power to the starter motor 102. The relay 308 is directly connected between the starter motor 102 and the battery 204 and is controlled by the ECU 206. Further, the relay 308 employed in the present embodiment is a low cost mechanical switch. As discussed in Figure 2, the ECU 206 turns ON the second switch 210 to provide the low power to the starter motor 102 during tooth-to-tooth abutment. Upon receiving the low power, the starter motor 102 rotates the pinion 110 slowly until the pinion 110 is engaged with the ring gear 212. The engagement of the pinion 110 with the ring gear 212 completes the inward movement of the plunger 116 and thereby electrically closing the fixed contacts 304 -1 and 304-2 by the movable contact 306. In accordance with the third embodiment, the sensor 118 employed for monitoring the inward movement of the plunger 116 is a non-contact sensor such as an active infra-red sensor, capacitance detection sensor, passive optical detection sensor, thermal detection sensor, or combinations thereof.

Further, the ECU 206 receives an electric signal from the sensor 118 indicating the closure of the fixed contact 304-1 and 304-2 by the movable contact 306. Consequently, the ECU 206 turns off the second switch 210 and immediately or with a delay provides the high power to the starter motor 102 from the battery 204 through the relay 308. In this embodiment the second switch 210 is used only for supplying the low power to the starter motor 102. Thus the use of relay 308 together with the switch is economical as the combined cost of the relay 308 and the second switch 210 is comparatively low.

This feature of providing the high power to the starter motor 102 with the delay after the pinion 110 is meshed with the ring gear 212 is advantageous during a stop-start operation of the vehicle. The stop-start operation generally refers to automatic switching OFF the IC engine when the vehicle is standstill or halted, such as waiting at a traffic signal, and then quickly switching the IC engine ON when the vehicle starts moving. During the stop-start operation, when the IC engine stops, the ECU 206 senses stopping of the IC engine and facilitates engagement of the pinion 110 with the ring gear 212 by applying the low power to the starter motor 102 through the second switch 210. When the vehicle starts moving the ECU 206 provides the high power to the starter motor 102 for restarting the IC engine. The starter motor 102 receives the high power from the battery 204 either through the second switch 210 or through the relay 308 connected to the starter motor 102. Thus, the starting time of the IC engine can be appreciably reduced. For example, the starting time of the IC engine can be reduced by 100 milliseconds. This feature is realizable for both the embodiments as described above with reference to Figure 3B and Figure 3C.

The previously described embodiments of the subject matter and its equivalent thereof have many advantages, including those which are described below. The engagement of the pinion with the ring gear is assured before the starter motor is powered with the high power for cranking the IC engine. The smooth engagement of the pinion with the ring gear enhances the reliability of the pinion and the ring gear. Also, application of the low power to the solenoid during the cranking of IC engine helps reduce the power consumption of the solenoid. Furthermore, the operating temperature of solenoid is also reduced, thus offering higher reliability and durability. Additionally, the high power supply can be selectively delayed to appreciably reduce the time for starting the engine during frequent stop-start operation.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are also possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

1/we claim:

1. An electronic starting system (200) for an internal combustion (IC) engine, comprising:

a starter motor assembly (100), and

an electronic control system (300) for soft starting the IC engine; said control system (300) comprising:

a first switch (208) to supply the low power to a solenoid (202), wherein the solenoid (202) is

a part of said starter motor assembly (100);

a second switch (210) to supply the low and the high power to a starter motor (102), wherein

the starter motor (102) is a part of said starter motor assembly (100);

an electronic control unit (ECU) (206) for regulating the power to the solenoid (202) and the starting motor (102) by controlling said first and second switches (208, 210); and

a sensor (118), said sensor (118) is in communication with said ECU (206) and monitors an engagement of a pinion (110) with a ring gear (212), wherein said pinion (110) is a part of the starter motor assembly (100);

said first switch (208) and said second switch (210) being controlled by said ECU (206) in response to inputs from said sensor (118), wherein said second switch (210) initially supplies low power to the starter motor (102) until ensuring a soft engagement of the pinion (110) with the ring gear (212) and thereafter supplies high power to said starter motor (102).

2. The electronic starting system (200) as claimed in claim 1, wherein said first switch (208) and said second switch (210) are electronic switches.

3. The electronic starting system (200) as claimed in claim 1, wherein said sensor (118) is mounted on the solenoid (202)

4. The electronic starting system (200) as claimed in claim 1, wherein said sensor (118) is a contact or a non-contact sensor.

5. The electronic starting system (200) as claimed in claim 1, wherein the solenoid (202) employs a single winding.

6. The electronic starting system (200) as claimed in claim 1, wherein said sensor (118) provides electrical path to supply the power to said starter motor (102).

7. The electronic starting system (200) as claimed in claim 4, wherein said second switch sensor (118), supplies high power to the starter motor (102) with a delay after completion of the soft engagement of the pinion (110) with the ring gear (212).

8. The electronic starting system (200) as claimed in claim 1, wherein said electronic
starting system (200) comprises a relay (308) for supplying the high power from said battery (204) to said starter motor (102).

9. The electronic starting system (200) as claimed in claim 7 or 8, wherein the starting time of the IC engine is reduced by about 100 milliseconds.