WO2011111059A2

WO2011111059A2 - Ignition control for internal combustion engine

Info

Publication number: WO2011111059A2
Application number: PCT/IN2011/000064
Authority: WO
Inventors: Subramanian Vaidyanathan; Dinesh Shyamsundar
Original assignee: Varroc Engineering Private Limited
Priority date: 2010-03-11
Filing date: 2011-01-31
Publication date: 2011-09-15
Also published as: TW201144586A; AR080581A1; WO2011111059A3; WO2011111059A4

Abstract

The present subject matter relates to a system in an internal combustion (IC) engine, comprising an actuator (6), a pulse generating unit (3) and an ignition controller. The actuator (6) rotates in conjunction with a crankshaft of the IC engine and comprises at least two consecutive leading edges (LE1, LE2) and at least one trailing edge (TE1). The pulse generating unit (3), actuated by the edges (LE1, LE2, TE1) of the actuator (6) passing under the pulse generating unit (3) upon rotation of the crankshaft, generates a sequence of pulses. The pulses are indicative of a crankshaft angle. The ignition controller generates a spark to ignite fuel in the IC engine based on the sequence of pulses and a speed of the crankshaft.

Description

IGNITION CONTROL FOR INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The subject matter described herein, in general, relates to a system and method for detection of the direction of rotation of the crankshaft of an internal combustion (IC) engine and for controlling ignition to prevent kickback in an IC engine. The subject matter described herein, in general, further relates to an IC engine based on the system and the method of present subject matter.

BACKGROUND

In an internal combustion (IC) engine the ignition timing is required to be synchronized in accordance with the movement of the crankshaft of the IC engine. For the purpose, a pulser coil is often employed. The pulser coil generates pulse signals which are indicative of the angular position of the crankshaft. The pulse signals may be utilized for various purposes. For example, the pulse signals may be sensed by a controller to initiate a spark within the IC engine at a desired angular position of the crankshaft, typically, before the piston of the IC engine reaches the top dead center (TDC). Further, the pulse signals may be used to determine the speed and direction of rotation of the crankshaft.

The determination of the direction of rotation of the crankshaft is vital in prevention of the phenomenon referred to as "kickback". A "kickback" is said to have occurred, when the piston is pushed back before reaching the TDC causing the crankshaft to rotate in a reverse direction. During this movement of the piston in the backward direction, occurrence of a spark results in the combustion and expansion of the charge within the cylinder of the IC engine and may impart a large pressure to the piston, accentuating this reverse movement. This large pressure on the piston moving in the backward direction results in a reverse torque on the crankshaft. This reverse torque often causes damage to components associated with the IC engine. Thus, the reverse torque is undesirable and needs to be prevented. SUMMARY

The subject matter disclosed herein describes a system in an internal combustion (IC) engine, comprising an actuator, a pulse generating unit and an ignition controller. The actuator is rotating in conjunction with a crankshaft of the IC engine. The actuator comprises at least two consecutive leading edges and at least one trailing edge. The pulse generating unit, actuated by the edges of the actuator passing under the pulse generating unit upon rotation of the crankshaft, generates a sequence of pulses. The pulses are indicative of a crankshaft angle. The ignition controller generates a spark to ignite fuel in the IC engine based on the sequence of pulses and a speed of the crankshaft.

The subject matter disclosed herein also describes a system to prevent kick back in an internal combustion (IC) engine. The system comprises a rotor configured to rotate in conjunction with a crankshaft of the IC engine, a pulser pip coupled to the rotor, and a pulser coil configured stationary at a predefined air-gap with respect to the rotor. The pulser pip alters the air-gap to actuate the pulser coil to generate a pulse at an instance of change^in the air-gap. The system further comprises an ignition controller configured to generate a spark to ignite fuel in the IC engine. The pulser pip comprises at least two consecutive leading edges and at least one trailing edge, such that in one complete positive rotation of the crankshaft, the pulser pip actuates the pulser coil to generate a sequence of pulses comprising at least two consecutive pulses of the first polarity followed by at least one pulse of the second polarity. The ignition controller generates the spark based on the sequence of pulse and a rotational speed of the crankshaft.

The subject matter disclosed herein further describes an internal combustion engine comprising a system, according to the present subject matter, to control ignition.

The subject matter disclosed herein further describes a method for controlling ignition in an internal combustion (IC) engine using a system according to the present subject matter. The method comprises generating a sequence of pulses comprising at least two consecutive pulses of a first polarity by a pulse generating unit actuated by an actuator comprising at least two consecutive leading edges. The actuator is rotating in conjunction to a crankshaft of the IC engine, and the pulses are indicative of a crankshaft angle. The method further comprises detecting the sequence of pulses, and generating a spark to ignite fuel in the IC engine based on the detected sequence of pulses.

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.

BRIEF DESCRIPTION OF DRAWINGS

The novel features of the subject matter are set forth in the appended claims hereto.

The subject matter itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein the same numbers are used throughout the drawings to reference like features, and wherein:

Figures la and lb illustrate a system including rotor assembly, pulser pip and pulser coil of an internal combustion engine, according to the present subject matter.

Figure 2 illustrates a pulser pip positioned on a rotor, according to the present subject matter.

Figures 3a and 3b illustrate a sequence of pulses generated to indicate a positive rotation of crankshaft in a predefined direction, according to the present subject matter.

Figures 4a and 4b illustrate a sequence of pulses generated to indicate a reversal in the rotation of the crankshaft, according to the present subject matter.

Figure 5 illustrates another embodiment of the pulser pip, according to the present subject matter.

Figures 6a and 6b illustrate another embodiment of the pulser pip, according to the present subject matter.

Figures 7a and 7b illustrate another embodiment of the pulser pip, according to the present subject matter. Figures 8a and 8b illustrate another embodiment of the pulser pip, according to the present subject matter.

Figure 9 illustrates the flow of method steps, according to the present subject matter.

DETAILED DESCRIPTION

In a conventional internal combustion (IC) engine, an ignition control system is associated with the crankshaft of the IC engine to cause a spark at a desired angular position of the crankshaft. For the purpose, the ignition control system needs to determine whether the desired angular position of the crankshaft has been attained. This determination of the desired angular position is typically achieved using a pulse generating means. The pulse generating means includes a sensor, such as a pulser coil, and an actuator, such as a pulser pip. The pulser pip is located on a member rotatably coupled to the crankshaft and undergoes a rotary motion in accordance with the crankshaft with respect to the sensor which is stationary. In every 360° rotation of the crankshaft the pulser pip crosses the sensor once. As the crankshaft completes one rotation, the pulser pip enters and exits the air-gap separating the sensor and the pulser pip thereby resulting in a change in the air-gap. The entering of the pulser pip in the air-gap reduces the air-gap, thereby inducing a voltage in the sensor to generate a positive polarity pulse. Similarly, when the pulser pip exits the air-gap, the air-gap increases and a negative polarity pulse is generated. Accordingly, in every 360° rotation, a sequence of one positive and one negative pulse is obtained.

The ignition control system detects this sequence of pulses to ascertain that the desired angular position of the crankshaft has been attained and accordingly initiates the spark. The spark is typically generated a few degrees prior to the piston of the IC engine reaching the top dead centre (TDC).

When the piston is approaching the TDC, in the compression cycle, the compressed fuel in the cylinder of the IC engine offers a backward thrust. In a situation where the speed of rotation of the crankshaft is low, the backward thrust experienced by the piston may push the piston backwards, thereby causing the crankshaft to rotate in a reverse direction. Reverse rotation of the crankshaft hampers the proper operation of the IC engine causing damage to components coupled to the IC engine and thus is undesirable. To effectively prevent reverse rotation, it is significant to detect that a reversal in the direction of rotation of the crankshaft has occurred. Upon determining that the crankshaft has begun rotating in the reverse direction, a spark which may aid the rotation of the crankshaft in the reverse direction needs to be prevented. The reverse rotation of the crankshaft may not only happen at the low rotational speed of the crankshaft, but also during the start-up (cranking) of the IC engine and also when there is a sudden drop in the rotational speed of the crankshaft.

However, in the conventional engine if a reversal in the direction of rotation of the crankshaft happens after the entering of the pulser pip in the air-gap between the sensor and the pulser pip but before its exiting, the aforementioned sequence of the positive and the negative pulse is generated and sensed by the ignition control means resulting in a spark. The occurrence of the spark during the reverse movement of the crankshaft more often than not results in the reverse rotation of the crankshaft.

In accordance with the present subject matter, disclosed herein is a system and a method to control ignition in an IC engine based on the detection of the direction of rotation of the crankshaft. Accordingly, prevention of generation of a spark takes place in case a reversal in the direction of rotation of the crankshaft, in order to retard the reverse rotation of the crankshaft and prevent shortcomings such as kickback.

The system, according to the present subject matter, includes an actuator rotating in conjunction with the crankshaft of the IC engine, and a pulse generating unit, actuated by the actuator, to generate a sequence of pulses upon rotation of the crankshaft. The actuator includes at least two consecutive leading edges and at least one trailing edge. The pulse generating unit is actuated by the edges of the actuator passing under the pulse generating unit. The pulses are indicative of a crankshaft angle and the sequence is indicative of the direction rotation of the crankshaft. The system further includes an ignition controller. The ignition controller initiates a spark based on the sequence of pulses and a rotational speed of the crankshaft. The pulse generating unit of the system includes at least one sensor head. The at least one sensor head and the actuator are separated by an air-gap. The pulse generating unit generates the pulse based on changes in the air-gap by the passing of the edges of the actuator under the at least one sensor head upon the rotation of the crankshaft.

Further, due to the at least two consecutive leading edges of the actuator, in each full positive rotation of the crankshaft the sequence of pulses includes at least two pulses of a first polarity. In one full positive rotation of the crankshaft, the number of pulses of the first polarity is equal to the number of consecutive leading edges. The positive rotation of the crankshaft is defined as the rotation of the crankshaft in the desirable direction.

The sequence of pulses, according to the present subject matter, generated by the pulse generating unit, is characteristic of the direction of rotation of the crankshaft. By detecting the sequence of pulses, the direction of rotation of the crankshaft can be determined. The principle of detection of reversal in the direction of rotation of the crankshaft may be applied for various purposes, such as, prevention of reverse rotation or prevention of kickback in an IC engine. It would be apparent that various modifications, adaptations, and alternative embodiments thereof may be made to extend the principle explained herein to other machines/apparatus which include rotating members.

The specification provided here explains in a detailed manner the system and method to control ignition in an IC engine based on the direction of rotation of the crankshaft. For the ease of understanding, the system and the method have been explained herein in context of an IC engine of a two-wheeled vehicle. However, it will be appreciated by one skilled in the art, that although the system and the method have been described with respect to an IC engine of a two-wheeled vehicle, the concept explained in context thereto may be extend to any other application of an IC engine without deviating from the scope and spirit of the invention. For example, the system and the method may be implemented in an IC engine of gen-sets, agricultural sprayers, lawnmowers and so on.

In an embodiment, the sequence of pulses includes at least two consecutive pulses of the first polarity, and at the time of initial cranking or below a predefined speed of the crankshaft the spark is generated by the ignition controller at any consecutive pulse of the first polarity after the first pulse of the first polarity. In an embodiment, the sequence of pulses includes at least two consecutive pulses of the first polarity, and at the time of initial cranking or below a predefined speed of the crankshaft the spark is generated by the ignition controller at a last pulse of the consecutive pulses of the first polarity.

In an embodiment, the sequence of pulses includes at least two consecutive pulses of the first polarity, and above the predefined speed of the crankshaft the spark is generated by the ignition controller at a predefined time after a first pulse of the first polarity.

Further, in an embodiment, below or above the predefined speed of the crankshaft the spark is generated by the ignition controller based on a time difference between the first pulse of the first polarity and the previous consecutive pulses of the first polarity.

Further, in an embodiment, the system includes a rotor rotating in conjunction with the crankshaft of the IC engine, and the actuator is coupled to the rotor. In an embodiment, the actuator is integrated with the rotor in the form of a protrusion on a periphery of the rotor. In an embodiment, the actuator is integrated with the rotor in the form of a depression on a periphery of the rotor.

Further, in an embodiment, the system includes a rotor rotating in conjunction with the crankshaft of the IC engine, and the actuator is positioned over a periphery of the rotor and configured to rotate in conjunction with the rotor.

Further, in en embodiment, the actuator is directly coupled to the crankshaft.

Further, in an embodiment, the actuator is a single-piece structure.

In an alternate embodiment, the actuator is a multi-piece structure.

Further, in an embodiment, the actuator is made of a magnetic material.

Further, in an embodiment, the pulse generating unit is a pulser coil.

Figure la shows a sectional view of components of a system of an internal combustion (IC) engine for detection of the direction of rotation of a crankshaft of the IC engine, according to an embodiment of the present subject matter. The system includes a rotor assembly 1 that is mounted on the crankshaft (not shown) and that rotates in conjunction with the crankshaft. The rotor assembly 1 includes a rotor 2. The rotor 2 depicted in the figure in accordance with one implementation is the rotating part of the magneto assembly commonly implemented in association with the IC engine in two- wheeled vehicles. In accordance with various other implementations, it will be understood that the rotor 2 may be accordingly embodied as any rotating member coupled to the crankshaft.

The IC engine may include one or more cylinders with their corresponding pistons, linked to the rotor assembly 1 through the crankshaft. The IC engine, according to the present subject matter, may be a two stroke engine or a four stroke engine. In case of the four stroke engine, all four strokes are completed upon 720° rotation of the rotor 2. In the two stroke engine, the strokes are completed upon 360° rotation of the rotor 2.

Figure la further shows a pulse generating unit 3 configured stationary and positioned over the rotor 2 of the rotor assembly 1. The pulse generating unit 3 may work on the principle of electromagnetic induction, or Hall Effect. In an embodiment of the present subject matter, the pulse generating unit 3 is a pulser coil magnetically coupled to the rotor 2. The terms 'pulse generating unit' and 'pulser coil' hereinafter are interchangeable in the specification. The pulser coil 3, according to the embodiment shown in figure la, includes two sensor heads in the form of sensor projections 4 and 5. The terms 'sensor head'- and 'sensor projection' hereinafter are interchangeable in the specification. An air-gap is maintained between the sensor projections 4 and 5, and the rotor 2, as shown in figure la. The pulse generating unit 3 generates a pulse when the air- gap between the projection and the rotor 2 changes.

Figure lb shows the components of the system shown in figure la viewed along arrow A shown in figure la. Figure lb shows an actuator 6 positioned along the periphery of the rotor 2 of the rotor assembly 1. The actuator 6 rotates in conjunction with the crankshaft and actuates the sensor heads 4 and 5. In the embodiment shown in figure lb, the actuator 6 is a pulser pip made of a magnetic material, preferably steel, which allows the passage of magnetic flux. The terms 'actuator' and 'pulser pip' hereinafter are interchangeable in the specification.

In an embodiment, the pulser pip 6 can be integrated with the rotor 2, on the periphery of the rotor 2, in form of a protrusion or a depression. In an alternate embodiment of the present subject matter, the pulser pip 6 can be a strip or strips, positioned over the periphery of the rotor 2, and configured to rotate in conjunction with the rotor 2.

On rotation of the rotor 2, the pulser pip 6 passes under the sensor projections 4 and 5 of the pulser coil 3. The entering and exiting of the pulser pip 6 under the sensor projections 4 and 5 alters the air-gap between the sensor projections 4 and 5, and the rotor 2. In particular, the air-gap changes at the passing of the edges of the pulser pip 6 under the sensor projections 4 and 5.

In an embodiment, the pulser pip 6 may be configured such that the entering of the pulser pip 6 in the air-gap reduces the air-gap, thereby inducing a voltage in the pulser coil 3 to generate a pulse of a first polarity. Similarly, when the pulser pip 6 exits the air-gap, the air-gap increases thereby inducing a voltage in the pulser coil 3 to generate a pulse of a second polarity.

In an embodiment, the pulser pip 6 may be configured such that the entering of the pulser pip 6 in the air-gap increases the air-gap, thereby inducing a voltage in the pulser coil 3 to generate a pulse of a first polarity and similarly, when the pulser pip 6 exits the air-gap, the air-gap reduces thereby inducing a voltage in the pulser coil 3 to generate a pulse of second (alternate) polarity.

In an embodiment, the first polarity is positive and the second polarity is negative. In an embodiment, the first polarity is negative and the second polarity is positive. The pulser pip 6, according to the present subject matter, includes at least two consecutive leading edges and at least one trailing edge.

Figure 2 shows the pulser pip 6, according to an embodiment of the present subject matter, positioned on the rotor 2. The pulser pip 6 is 'L-shaped'. The pulser pip 6 includes a first leading edge LEI , a second leading edge LE2 consecutive with respect to the first leading edge LEI, and one trailing edge TE1. The pulser coil 3 is positioned over the rotor 2 in such a way that, on rotation of the rotor 2, the first leading edge LEI passes under the sensor projection 4 of the pulser coil 3 and the second leading edge LE2 passes under the sensor projection 5 of the pulser coil 3 in succession of leading edge LEI . In an alternate embodiment of the present subject matter, the pulser pip 6 may be 'L-shaped', with the first leading edge LEI passing under the sensor projection 5 and the second leading edge LE2 passing under the sensor projection 4. Furthermore, it will be apparent that the L shape of the pulser pip 6 has been described merely as an illustration to ease the understanding of the specification and should not be construed as limiting in any way. The concepts and teachings described herein apply to any other shape having at least two leading edges followed by at least one trailing edge.

Although in the above described embodiments, the pulser coil 3 depicted in the figures illustrates two sensor projections 4 and 5, other embodiments with varying number of sensor projections are possible. In an embodiment, the pulser coil 3 may include a single sensor projection, with a substantially elongated length. The single sensor projection may span the width 'b' of the pulser pip 6 such that all the leading and trailing edges pass under the single sensor projection and thus alter the air-gap between the single sensor projection and the rotor 2.

The pulser coil 3 with one or multiple sensor projections generates a single signal of the sequence of pulses. In other words, the output from the sensor projection(s) may be retrieved from a single output electrical wire. Advantageously this makes the system, according to; present subject matter, compact and reliable.

Further, in an exemplary embodiment of the present subject matter, the pulser pip 6 is positioned on the rotor 2, such that the crankshaft reaches its top dead centre (TDC) position after the leading edges LEI and LE2 cross the sensor projections 4 and 5, respectively, and before the trailing edge TEl crosses the sensor projections 4 and 5. In an alternate embodiment of the present subject matter, the pulser pip 6 is positioned on the rotor 2, such that the crankshaft reaches its TDC position after the leading edges LEI and LE2 and the trailing edge TEl cross the projections 4 and 5.

Figures 3a and 3b illustrate a sequence of pulses generated by the pulser coil 3 on passing of the pulser pip 6, with two consecutive leading edges and one trailing edge, under the sensor projections 4 and 5 for continuous rotation of the crankshaft in a predefined direction. In an embodiment, the predefined direction of rotation is clockwise. In an alternate embodiment, the predefined direction can be anti-clockwise. For the sake of simplicity, the system with a pulser pip having two consecutive leading edges and one trailing edge is described herein. However, a similar description can be extended to a pulser pip with more than two consecutive leading edges and at leat one trailing edge.

Figure 3a shows positions of the crankshaft, in terms of crankshaft angle (#CA), at which the leading edges LEI and LE2, and the trailing edge TEl cross the sensor projections 4 and 5 of the pulser coil 3. Figure 3b shows the sequence of pulses generated under the continuous rotation of the crankshaft in the predefined direction. As the crankshaft rotates, at #CAI the first leading edge LEI enters the sensor projection 4. At this, a pulse of the first polarity is generated by the pulser coil 3 due to a decrease in the air-gap between the projection 4 and the rotor 2. As the crankshaft further rotates in the same direction, at O M the second leading edge LE2 enters the sensor projection 5. At this instance, a pulse of the first polarity is again generated by the pulser coil 3 due to a decrease in the air-gap between the sensor projection 5 and the rotor 2. As the crankshaft further rotates in the same direction and crosses the TDC position, at #CA3 the trailing edge TEl crosses the sensor projections 4 and 5, resulting in the pulser pip 6 to exit the sensor projections 4 and 5. At this instance, a pulse of the second polarity is generated by the pulser coil 3 due to an increase in the air-gap between the sensor projections 4 and 5 and the rotor 2. For every 360° rotation of the rotor 2 in the predefined direction in conjunction with the crankshaft, the sequence having two consecutive pulses of the first polarity and one pulse of the second polarity, as shown in figure 3b, is generated.

Figures 4a and 4b illustrates a sequence of pulses generated by the pulser coil 3 on passing of the pip 6, with two consecutive leading edges and one trailing edge, under the sensor projections 4 and 5 when the crankshaft reverses its direction of rotation. Under this condition, the crankshaft is unable to cross the TDC position and moves in a reverse direction with respect to the predefined direction.

Figure 4a shows a sequence of pulses generated when the crankshaft reverses its direction after the first leading edge LEI enters the sensor projection 4 but before the second leading edge LE2 enters the sensor projection 5. As the crankshaft rotates in the predefined direction, at #CAI the first leading edge LEI enters the sensor projection 4. At this, a pulse of the first polarity is generated by the pulser coil 3 due to a decrease in the air-gap between the sensor projection 4 and the rotor 2. Since the crankshaft reverses before the second leading edge LE2 enters the sensor projection 5, the first leading edge LEI exits the sensor projection 4 in the reverse direction. At this, a pulse of the second polarity is generated by the pulser coil 3 due to an increase in the air-gap between the sensor projection 4 and the rotor 2. The sequence of pulse generated in this situation has one pulse of the first polarity followed by one pulse of the second polarity, as shown in figure 4a. The sequence of pulse generated in the current circumstances is detected to be different from the sequence obtained in the normal rotation and thus, a reversal in direction of rotation is sensed.

Figure 4b shows a sequence of pulses generated when the crankshaft reverses its direction after the first leading edge LEI and second leading edge LE2 cross the projections 4 and 5, respectively, but before the crankshaft reaches the TDC position. As the crankshaft rotates in the predefined direction, at #CAI, the first leading edge LEI enters the sensor projection 4. At this, a pulse of the first polarity is generated by the pulser coil 3 due to a decrease in the air-gap between the sensor projection 4 and the rotor 2. As the crankshaft further rotates in the predefined direction, at 0CA2, the second leading edge LE2 enters the sensor projection 5. At this, a pulse of the first polarity is again generated by the pulser coil 3 due to a decrease in the air-gap between the sensor projection 5 and the rotor 2. Since the crankshaft reverses before reaching the TDC position, the second leading edge LE2 exits the sensor projection 5 in the reverse direction. At this, a pulse of the second polarity is generated by the pulser coil 3 due to an increase in the air-gap between the sensor projection 5 and the rotor 2. As the crankshaft further moves in the . reverse direction, the first leading edge LEI exits the sensor projection 4 in the reverse direction. At this, a pulse of the second polarity is again generated by the pulser coil 3 due to an increase in the air-gap between the sensor projection 4 and the rotor 2. Thus, the sequence of pulse generated in this situation has two consecutive pulses of the first polarity followed by two consecutive pulses of the second polarity, as shown in figure 4b, notably different from the sequence obtained in during the normal rotation.

Thus, according to the present subject matter, the sequence of pulses generated by the pulser coil 3 is characteristic of the direction of rotation of the rotor 3 of the rotor assembly 1. The principle of detection of the direction of rotation of the crankshaft described herein may be applied for various purposes, such as, prevention of reverse rotation or prevention of kickback in an IC engine. In an embodiment of the present subject matter, illustrated herein, direction of rotation of the crankshaft is utilized to prevent kickback in the IC engine. In the aforementioned embodiments, the sequence of pulses generated by the pulser coil 3 is detection by a controller (not shown), preferably an ignition controller, to control a spark (or firing) to ignite a fuel in the cylinder.

In an exemplary embodiment, during initial cranking or below a predefine speed of the crankshaft, the spark (or firing) takes place on detection of any consecutive pulse of the first polarity after the first pulse of the first polarity. The pulser pip 6 and the pulser coil 3 are positioned in the IC engine such that a predefined consecutive leading edge of the pulser pip 6 crosses the projection of the pulser coil 3 at the desired angular position of the crankshaft at which the spark occurs. In other words, the pulser pip 6 and the pulser coil 3 are positioned in the IC engine such that a predefined consecutive pulse of the first polarity is generated at the desired angular position of the crankshaft at which the spark (or firing) occurs.

As illustrated in figure 3b, according to an embodiment, in case of normal rotation of the crankshaft in the predefined direction, the firing takes place at the onset of the second consecutive pulse of the first polarity, indicated by arrow B. In case of reversal of the crankshaft as described earlier in respect of figure 4a, the ignition controller detects the sequence, shown in figure 4a, having one pulse of the first polarity followed by one pulse of the second polarity. Since there is no consecutive pulse of the first polarity detected, the spark (or firing) will not occur in the reverse rotation of the crankshaft. Thus, the kickback would not occur.

Further, in case of reversal of the crankshaft as described earlier in respect of figure 4b, the ignition controller detects the sequence, shown in figure 4b, having two consecutive pulses of the first polarity followed by two consecutive pulses of the second polarity. In this situation, the spark (or firing) will take place at the onset of the second consecutive pulse of the first polarity (shown by arrow C in figure 4b), when the crankshaft was moving in the predefined direction. However, there is no consecutive pulse of the first polarity detected when the crankshaft rotates in the reverse direction before reaching the TDC position. Thus, the spark (or firing) will not occur in the reverse rotation of the crankshaft. Thus, the kickback may be prevented.

Further, in an exemplary embodiment, in case of normal rotation of the crankshaft in a predefined direction at a speed above a predefined speed, the spark (or firing) may not take place on detection of the predefined consecutive pulse of the first polarity. Instead the spark takes place at a predefined time after the first pulse of the first polarity. The value of predefined time is based on the rotational speed of the crankshaft.

Further, in an exemplary embodiment, when crankshaft is rotating below or above a predefine speed the spark (or firing) takes place based on the time difference between the first pulse of the first polarity and the previous consecutive pulses of the first polarity is more than a predefined threshold value.

Further, in an exemplary embodiment, when crankshaft is rotating below or above a predefine speed the spark (or firing) takes place based on the time difference between the last two sets of the consecutive pulses of the first polarity is more than a predefined threshold value.

Figure 5 shows an alternate structure of the pulser pip 6, according to the present subject matter, positioned on the rotor 2. The pulser pip 6, shown in figure 5, includes a first leading edge LEI, a second consecutive leading edge LE2, a first trailing edge TE1 and a second consecutive trailing edge TE2. Generation of a sequence of pulses for the pulser pip 6 of figure 5 can be described on the similar lines as described earlier in figures 3 and 4 with respect to the pulser pip 6 shown in figure 2. The detection of the sequence of pulses and the criterion of generating a spark at any consecutive pulse of the first polarity after the first pulse of the first polarity, as described earlier, according to the present subject matter, is applied.

Figures 6a and 6b show alternate structures of the pulser pip 6, according to the present subject matter, in the form of a two-piece structure positioned on the rotor 2. The pulser pips 6 shown in figures 2 and 5 are in the form of single-piece structures. Figure 6a illustrates the pulser pip 6, with the two-piece structure, having the first leading edge LEI , and the second leading edge LE2, consecutive with respect to the first leading edge LEI . The two-piece structure, in this embodiment, includes two strips with their trailing ends inline with each other, forming a single trailing edge TE1, as shown. The strips are preferably made of a magnetic material. Figure 6b illustrates the pulser pip 6, with the two-piece structure, having the first leading edge LEI , the second consecutive leading edge LE2, the first trailing edge TE1 and the second consecutive trailing edge TE2. The two- piece structure, again in this embodiment, includes two strips, as shown, preferably made of a magnetic material.

Figure 7a shows an alternate structure of the pulser pip 6, according to the present subject matter, positioned on the rotor 2. The pulser pip 6, shown in figure 7a, includes two consecutive leading edges and one trailing edge. The consecutive leading edge, as shown, extends in a radial direction instead of a direction perpendicular to the radial direction as shown in figures 2 and 5. Figure 7b illustrates figure 7a viewed along arrow D. In the embodiment shown in figure 7b the pulser coil 3 includes a single projection 4. The pulser coil 3 generates a pulse each time any edge of the pulser pip 6 passes under the sensor projection 4 and changes the magnitude of air-gap between the pulser coil 3 and the rotor 2. Generation of a sequence of pulses for the pulser pip 6 of figure 7a can be described on the similar lines as described earlier in figures 3 and 4 with respect to the pulser pip 6 shown in figure 2. The detection of the sequence of pulses and the criterion of generating a spark at any consecutive pulse of the first polarity after the first pulse of the first polarity, as described earlier, according to the present subject matter, is applied.

Figures 8a and 8b shows the structure of the pulser pip 6, according to further embodiments of the present subject matter. The pulser pip 6 shown in figure 8a is an extension of the pulser pip 6 shown in figures 2 and 6a. The pulser pip includes n number of steps forming consecutive leading edges followed by m number of steps forming consecutive trailing edge. Here, n > 2, m > 1 , and n > m. The pulser pip 6 shown in figure 8b is an extension of the pulser pip 6 shown in figures 5 and 6b. The pulser pip includes p number of steps forming consecutive leading edges followed by q number of steps forming consecutive trailing edge. Here, p = q > 2. According to the present subject matter, in the embodiment of the system that includes the pulser pip 6 of figure 8a or figure 8b, the " pulser coil 3 may include one or more sensor projections, such that all the leading and trailing edges pass under the sensor projection(s) and thus alter the air-gap between the sensor projection(s) and the rotor 2. The pulser pips 6 shown in figures 8a and 8b can be in the form of single-piece structures and multi-piece structures. Furthermore, the steps in pulser pips 6, shown in figures 8a and 8b, may extend in a radial direction or a direction perpendicular to the radial direction.

Further, in an embodiment, the pulser pip 6 is directly coupled or integrated with the crankshaft. The pulser pip 6 rotates in conjunction with the crankshaft and actuates the pulser coil 3 to generate the sequence of pulse, according to the present subject matter.

The system, according to the present subject matter, prevents kickback during the start-up (initial cranking) of the IC engine and at substantially low rotational speeds, below a threshold value of speed, of the crankshaft. The system, according to the present subject matter, also prevents kickback when the rotational speeds of the crankshaft drops below the threshold value.

The method, according to the present subject matter, controls ignition in an IC engine using the system described herein. The method further enables prevention of kickback in an IC engine. The method includes generation and detection of a sequence of pulses with at least two consecutive pulses of a first polarity. The sequence of pulses is generated by the pulse generating unit 3 and detected by a controller. The pulse generating unit 3 is actuated by the actuator 6 rotating in conjunction to the crankshaft of the IC engine. The actuator 6 includes at least two consecutive leading edges and at least one trailing edge. The pulses are indicative of a crankshaft angle.

In an embodiment, the generation of the pulses is based upon a change in an air-gap between the at least one sensor head of the pulse generating unit 3 and the rotor 2 of the rotor assembly 1 coupled to the crankshaft. The air-gap changes particularly at the each passing edge of the actuator 6. The at least two consecutive leading edges of the actuator 6 correspondingly leads to generation of at least two consecutive pulses of the first polarity upon one full positive rotation of the crankshaft. In an embodiment, the method further includes generation of a spark to ignite a fuel in the cylinder of the IC engine based on the detected sequence of pulses. In an embodiment, at the initial cranking or below a predefined rotational speed of the crankshaft the spark is generated at any consecutive pulse of the first polarity after the first pulse of the first polarity. In an embodiment, above a predefined speed of the crankshaft the spark is generated at a predefined time after a first pulse of the first polarity. Further, in an embodiment, above or below the predefined speed of the crankshaft the spark is generated based on the time difference between the first pulse of the first polarity and the previous consecutive pulses of the first polarity is more than a predefined threshold value.

Figure 9 illustrates a flowchart elucidating a method of controlling ignition in an IC engine based on generation and detection of a sequence of pulses, according to the present subject matter. For the sake of simplicity, the method described herein is for system having an actuator with two consecutive leading edges and one trailing edge. However, a similar description can be extended to an actuator with more than two consecutive leading edges and at least one trailing edge. At step 10, the pulse generated by the pulser generating unit is received or detected by the ignition controller. The polarity of the pulses is checked at step 20. If the pulse is not of the first polarity the controller is reset and step 10 is executed again. If the pulse is of the first polarity the information of the polarity is saved by the controller. Then, at step 30, it is check whether the pulse is generated at an initial cranking of the IC engine. If the pulse is generated at the initial cranking then, at step 60, another pulse from the pulse generating unit is received or detected by the ignition controller. The polarity of this further pulse is checked at step 70. If, at step 70, the further pulse is of the first polarity the spark is generated to ignite fuel in the IC engine. Thus, at the initial cranking, the spark is generated at the consecutive pulse of the first polarity. If, at step 70, the pulse is not of the first polarity the controller is reset and step 10 is executed again.

Further, if, at step 30, the pulse is not generated at the initial cranking then, at step 40, the speed of rotation of the crankshaft (or rotor in an embodiment) is calculated. At step 50, the speed of crankshaft is compared with a predefined threshold speed and if the speed of crankshaft is below the predefined threshold speed then, at step 60, a further pulse from the pulse generating unit is received or detected by the ignition controller. The polarity of this further pulse is checked at step 70. If, at step 70, the further pulse is of the first polarity the spark is generated to ignite fuel in the IC engine. Thus, below the predefine speed of the crankshaft the spark is generated at the consecutive pulse of the first polarity. If, at step 70, the pulse is not of the first polarity the controller is reset and step 10 is executed again.

Further, if, at step 50, the speed of crankshaft is above the predefined threshold speed then, at step 80, a time difference between the pulse of the first polarity and the previous set of pulses of the first polarity is calculated. At step 90, the calculated time difference is compared with a predefined threshold time difference. The predefine threshold time difference is dependent on the speed of the crankshaft. If, at step 90, the calculated time difference is below the predefine threshold time difference the controller is reset and step 10 is executed again. However, if, at step 90, the calculated time difference is above the predefine threshold time difference the spark is generated to ignite fuel in the IC engine. Thus, above the predefine speed of the crankshaft the spark is at a predefined time after the first pulse of the first polarity.

The system and method, according to the present subject matter, is advantageous as the system and the method are easy to implement and are cost effective. The system and the method are reliable, involve simple electronics and are feasible to implement in IC engines of irrespective of their size and configuration. Further, the system and the method are adaptive to the existing IC engines. Further advantage of the system and the method, according to the present subject matter, is that they work on the basis of the signal from the pulser generating unit only.

The inventive system and method of the present subject matter for detection of direction of rotation of a crankshaft in an IC engine, for controlling ignition and for preventing kickback in the IC engine are not restricted to the embodiments that are mentioned above in the description.

Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.

Claims

I/We claim:

1. A system in an internal combustion (IC) engine, the system comprising:

an actuator (6) rotating in conjunction with a crankshaft of the IC engine, wherein the actuator (6) comprises at least two consecutive leading edges (LEI ,

LE2) and at least one trailing edge (TE1);

a pulse generating unit (3), actuated by the edges (LEI, LE2, TE1) of the actuator (6) passing under the pulse generating unit (3) upon rotation of the crankshaft, to generate a sequence of pulses, wherein the pulses are indicative of a crankshaft angle; and

an ignition controller to generate a spark to ignite fuel in the IC engine based on the sequence of pulses and a speed of the crankshaft.

2. The system as claimed in claim 1 , wherein the pulse generating unit (3) comprises at least one sensor head (4, 5), wherein the at least one sensor head (4, 5) and the actuator (6) are separated by an air-gap, and wherein the pulse generating unit (3) generates the pulse based on changes in the air-gap by the passing of the edges (LEI, LE2, TE1) of the actuator (6) under the at least one sensor head (4, 5) upon the rotation of the crankshaft.

3. The system as claimed in claim 1 or 2, wherein, at cranking of the IC engine, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at any consecutive pulse of the first polarity after the first pulse of the first polarity.

4. The system as claimed in claim 1 or 2, wherein, below a predefined speed of the crankshaft, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at any consecutive pulse of the first polarity after the first pulse of the first polarity.

5. The system as claimed in claim 1 to 2, wherein, above a predefined speed of the crankshaft, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at a predefined time after a first pulse of a first polarity.

6. The system as claimed in claim 4 or 5, wherein the ignition controller generates the spark based on a time difference between the first pulse of the first polarity and the previous consecutive pulses of the first polarity.

7. The system as claimed in any one of the claims 1 to 6, wherein the system comprises a rotor (2) rotating in conjunction with the crankshaft, wherein the actuator (6) is coupled to the rotor (2).

8. The System as claimed in claim 7, wherein the actuator (6) is integrated with the rotor (2) in the form of a protrusion on a periphery of the rotor (2).

9. The system as claimed in claim 7, wherein the actuator (6) is integrated with the rotor (2) in the form of a depression on a periphery of the rotor (2).

10. The system as claimed in any one of the claims 1 to 6, wherein the system comprises a rotor (2) rotating in conjunction with the crankshaft, wherein the actuator (6) is positioned over a periphery of the rotor (2) and configured to rotate in conjunction with the rotor (2).

1 1. The system as claimed in any one of the claims 1 to 6, wherein the actuator (6) is directly coupled to the crankshaft.

12. The system as claimed in any one of the claims 1 to 1 1, wherein the actuator (6) is a single-piece structure.

13. The system as claimed in any one of the claims 1 to 1 1 , wherein the actuator (6) is a multiple-piece structure.

14. The system as claimed in any one of the claims 1 to 13, wherein the actuator (6) is made of a magnetic material.

15. The system as claimed in any one of the claims 1 to 14, wherein the pulse generating unit (3) generates the sequence of pulses in the form of a single signal retrieved via a single wire from the pulse generating unit (3).

16. The system as claimed in any one of the claims 1 to 15, wherein the pulse generating unit (3) is a pulser coil.

17. A system to prevent kick back in an internal combustion (IC) engine, the system comprising:

a rotor (2) configured to rotate in conjunction with a crankshaft of the IC engine; a pulser pip (6) coupled to the rotor (2);

a pulser coil (3) configured stationary at a predefined air-gap with respect to the rotor (2), wherein the pulser pip (6) alters the air-gap to actuate the pulser coil (3) to generate a pulse at an instance of change in the air-gap; and

an ignition controller configured to generate a spark to ignite fuel in the IC engine; characterized in that, .

the pulser pip (6) comprises at least two consecutive leading edges (LEI , LE2) and at least one trailing edge (TE1), such that in one complete positive rotation of the crankshaft, the pulser pip (6) actuates the pulser coil (3) to generate a sequence of pulses comprising at least two consecutive pulses of the first polarity followed by at least one pulse of the second polarity, wherein the ignition controller generates the spark based on the sequence of pulse and a rotational speed of the crankshaft.

18. The system as claimed in claim 17, wherein the pulser coil (3) comprises at least one sensor head (4, 5), wherein the at least one sensor head (4, 5) and the rotor (2) are separated by the air-gap, and wherein the pulser coil (3) generates the pulse based on changes in the air-gap by the passing of the edges (LEI, LE2, TE1) of the pulser pip (6) under the at least one sensor head (4, 5) upon the rotation of the crankshaft.

19. The system as claimed in claim 17 or 18, wherein, at cranking of the IC engine, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at any consecutive pulse of the first polarity after the first pulse of the first polarity.

20. The system as claimed in claim 17 or 18, wherein, below a predefined speed of the crankshaft, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at any consecutive pulse of the first polarity after the first pulse of the first polarity.

21. The system as claimed in claim 17 to 18, wherein, above a predefined speed of the crankshaft, the sequence of pulses comprises at least two consecutive pulses of a first polarity, and wherein the ignition controller generates the spark at a predefined time after a first pulse of a first polarity.

22. The system as claimed in claim 20 or 21 , wherein the ignition controller generates the spark based on a time difference between the first pulse of the first polarity and the previous consecutive pulses of the first polarity.

23. The system as claimed in any one of the claims 17 to 22, wherein the pulser pip (6) is integrated with the rotor (2) in the form of a protrusion on a periphery of the rotor (2).

24. The system as claimed in any one of the claims 17 to 22, wherein the pulser pip (6) is integrated with the rotor (2) in the form of a depression on a periphery of the rotor (2).

25. The system as claimed in any one of the claims 17 to 24, wherein the pulser pip (6) is a single-piece structure.

26. The system as claimed in any one of the claims 17 to 24, wherein the pulser pip (6) is a multiple^piece structure.

27. The system as claimed in any one of the claims 17 to 26, wherein the pulser pip (6) is made of a magnetic material.

28. The system as claimed in any one of the claims 17 to 27, wherein the pulser coil (3) generates the sequence of pulses in the form of a single signal retrieved via a single wire from the pulser coil (3).

29. An internal combustion engine comprising a system, as claimed in any of the preceding claims, to control ignition.

30. A method for controlling ignition in an internal combustion (IC) engine using a system as claimed in one of the claims 1 to 28, the method comprising:

generating a sequence of pulses comprising at least two consecutive pulses of a first polarity by a pulse generating unit actuated by an actuator comprising at least two consecutive leading edges, wherein the actuator is rotating in conjunction to a crankshaft of the IC engine, and wherein the pulses are indicative of a crankshaft angle;

detecting the sequence of pulses; and

generating a spark to ignite fuel in the IC engine based on the detected sequence of pulses.

31. The method as claimed in claim 30, wherein the generating the spark is at any consecutive pulse of the first polarity after the first pulse of the first polarity, at cranking of the IC engine.

32. The method as claimed in claim 30, wherein the generating the spark is at any consecutive pulse of the first polarity after the first pulse of the first polarity, below a predefined speed of the crankshaft.

33. The method as claimed in claim 30, wherein the generating the spark is at a predefined time after a first pulse of the first polarity, above a predefined speed of the crankshaft.

34. The method as claimed in claim 32 or 33, wherein the generating the spark is based on a time difference between the first pulse of the first polarity and a previous consecutive pulses of the first polarity.

35. The method as claimed in any one of the claims 30 to 34, wherein the method further comprises:

generating the pulse upon changing an air-gap between the actuator and an at least one sensor head of the pulse generating unit.