Title of Invention

A CONTROLLER FOR A SINGLE CYLINDER 4-CYCLE ENGINE

Abstract

ABSTRACT OF THE DISCLOSURE In a single-cylinder 4-cycle engine (10), its rotation speed is not uniform while a crankshaft (19) is rotated one rotation. A time (T30) required for rotating the crankshaft (19) a specified crank angle is different for each stroke. In particular, the tendency of a change in time (T30) required for rotation is different for each stroke. The times (T30) for crank angle numbers Cn = 8, 9 are acquired (steps S104, S107) and a time difference (AT30) between the times (T30) required for rotation is calculated (step S109). Then, the time difference (AT30) is compared with previously determined stroke determination values K1 and K2 (step S110, 113) to determine which of strokes the present stroke is (steps S111, S114).

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10; rule 13) TITLE CONTROLLER FOR SINGLE CYLINDER 4-CYCLE APPLICANT DENSO CORPORATION 1-1, Showa-cho Kariya-city Aichi-pref. 448-8661 Japan Nationality: a Japanese corporation The following specification particularly describes the nature of this invention and the manner in which it is to be performed CONTROLLER FOR SINGLE CYLINDER 4-CYCLE ENGINE FIELD OF THE INVENTION The present invention relates to a controller for a single cylinder 4-cycle engine and in particular to a controller for making a stroke determination of the engine. BACKGROUND OF THE INVENTION In a 4-cycle engine, an intake stroke, a compression stroke, a power stroke, and an exhaust stroke are sequentially performed to complete one cycle of its combustion cycle. That is, in the 4-cycle engine, when the crankshaft is rotated two rotations, one cycle of the combustion cycle is completed. For this reason, it is impossible to determine which of the strokes the present stroke is merely by detecting the rotation angle of the crankshaft. When it is impossible to determine which of the strokes the present stroke is, it is impossible to grasp timing when a fuel injection control or an ignition timing control is to be performed and hence it is impossible to control driving an engine in a suitable and appropriate manner. In a conventional control system of a 4-cycle engine, a camshaft rotates one rotation while the crankshaft is rotated two rotations, and the camshaft is provided with a cam sensor. A stroke determination is made based on a signal from the cam sensor. However, in this method, it is necessary to provide a sensor for sensing the rotation angle of the camshaft, which is disadvantageous in terms of cost and the like. Incidentally, in a single-cylinder 4-cycle engine, its rotation speed is not uniform while the crankshaft is rotated one rotation. The rotation speed of the crankshaft is increased in a power stroke by the work of combustion of air-fuel mixture and is decreased in the other strokes because a braking force is applied to the crankshaft. JP-2001-289109A (US-6550452B2), for example, discloses a method for making a stroke determination based on this phenomenon. That is, a time required for rotation, which is a time required for the crankshaft to rotate from a top dead center to a specified rotation angle, is measured and the times required for rotation, which are measured while the crankshaft is rotated two consecutive rotations, are compared with each other. Then, a stroke including the shorter time required for rotation of two measured times is determined to correspond to a power stroke. Moreover, in JP-2002-70708A (US-6595044B2), a signal rotor fitted to a crankshaft has a so-called chipped tooth portion formed at an appropriate position such that the chipped tooth portion passes a crank angle sensor while the piston of the engine moves from a top dead center to a bottom dead center. With this, a stroke in which the chipped tooth portion passes the crank angle sensor becomes either an intake stroke or a power stroke. Times required for the chipped tooth portion to pass the crank angle sensor while the crankshaft is rotated two consecutive rotations are measured. Then, two measured times are compared with each other and it is determined that a power stroke is included in a stroke including the shorter time of the two measured times. However, in the methods disclosed above, the crankshaft needs to be rotated two rotations to make a stroke determination. Incidentally, in JP-2002-70708A, the times required for rotation when the crankshaft is rotated a specified crank angle before and after the chipped tooth portion are computed and a stroke determination is made on the basis of the ratio between such two times required for rotation that are computed before and after the chipped tooth. However, in this method, the position of the chipped tooth portion of the signal rotor is limited. SUMMARY OF THE INVENTION It is an object of the present invention to provide a controller for a single-cylinder 4-cycle engine capable of making a stroke determination while a crankshaft is rotated one rotation and of performing an appropriate driving control quickly. In a single-cylinder 4-cycle engine that increases and decreases a cylinder volume and rotates a crankshaft by a reciprocating motion of a piston, one cycle of a combustion cycle is completed when the crankshaft is rotated two rotations. For this reason, when it is assumed that one rotation corresponding to an intake stroke and a compression stroke is "obverse" and that one rotation corresponding to a power stroke and an exhaust stroke is "reverse", merely by detecting the rotation angle of the crankshaft, it cannot be discriminated which of "obverse" and "reverse" the present rotation is. Hence, it cannot be determined which of strokes the present stroke is. Thus, the present invention notes that a time required for rotation when the crankshaft is rotated a specified crank angle is different for each stroke. The time required for rotation is shortened by a work of the expansion of air-fuel mixture in the power stroke. In the other strokes after the power stroke, the time required for rotation tends to be elongated because the crankshaft receives the action of braking forces caused by exhaust, suction, and compression, so that the present invention notes the tendency of change in the time required for rotation. According to the present invention, a controller includes a crank angle sensor that outputs a rotation detection signal every time the crankshaft is rotated an equal angle. Hence, it is possible to compute a time required for rotation when a crankshaft is rotated a specified crank angle at a previously determined angle position on the crankshaft. A stroke determination is performed based on two sequential times required for rotation, which are computed within a period during which the cylinder volume is increased by a piston or within a period during which the cylinder volume is decreased by the piston. The two sequential times required for rotation are computed within a period during which the cylinder volume is increased by a piston or within a period during which the cylinder volume is decreased by the piston and the tendency of change in the time required for rotation can be obtained by the two sequential times required for rotation. The tendency of change in time required for rotation is different for each stroke and hence it is possible to determine which of strokes the reference angle position belongs. That is, it is possible to make the stroke determination while the crankshaft is rotated one rotation and to perform an appropriate driving control quickly. Here, "two sequential times required for rotation" are not only two times required for rotation, which are computed sequentially and consecutively, but also may be two times required for rotation, which are computed sequentially but separately. BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which: FIG. 1 is a general construction diagram to show the outline of an engine control system; FIG. 2 is a diagram to show the state of a change in a time T30 required for rotation; FIG. 3 is a flow chart to show the processing procedure of a stroke determination; and FIG. 4 is a flow chart to show the processing procedure of a stroke determination in a second embodiment. DETAILED DESCRIPTION OF EMBODIMENTS [First Embodiment] Hereinafter, one embodiment embodying the present invention will be described with reference to the drawings. This embodiment constructs an engine control system for a 4-cycle single-cylinder gasoline engine for a motorcycle. In this engine control system, an electronic control unit (hereafter referred to as "ECU") performs an ignition timing control and the like. Referring to FIG. 1, the general schematic construction of this engine control system will be described. An intake port of an engine 10 has an intake valve 11 fitted therein and has an intake pipe 12 connected thereto. An electromagnetic fuel injection valve 13 is fitted near the intake port of the intake pipe 12 and fuel is supplied to this fuel injection valve 13 from a fuel supply system (not shown). Moreover, an exhaust port of the engine 10 has an exhaust valve 14 fitted therein and has an exhaust pipe 15 connected thereto. In this construction, when the intake valve 11 is opened, intake air is introduced into a combustion chamber 200 of the engine 10 from the intake pipe 12 and when the exhaust valve 14 is opened, exhaust gas after combustion is discharged into the exhaust pipe 15. The cylinder head of the engine 10 is fitted with an ignition plug 16 and high voltage is applied to this ignition plug 16 at a desired ignition timing by an ignition device (not shown) formed of an ignition coil and the like. When the high voltage is applied to the ignition plug 16, spark discharge is developed between the opposite electrodes of the ignition plug 16 to ignite air-fuel mixture introduced into the combustion chamber of the engine 10. Moreover, a piston 17 is fitted in a cylinder of the engine 10 and is coupled to a crankshaft 19 via a connecting rod 18. That is, the volume of the combustion chamber 200 is varied by the reciprocating motion of the piston 17. The crankshaft 19 is fitted with a signal rotor 21 having projections formed repeatedly at specified crank angle intervals of 30° CA and having a chipped tooth portion where a part of the projections is not formed. A crank angle sensor 22 is provided near the signal rotor 21. The rotation angle of the crankshaft 19 is detected by the crank angle sensor 22 based on the projections and the chipped tooth portion of the signal rotor 21. Describing this in more detail, the reference angle position of the crankshaft 19 is detected on the basis of the chipped tooth portion of the signal rotor 21 (determination of reference position) and it is detected the crankshaft 19 is rotated by 30° CA every time the projection is detected with reference to the reference angle position. In this embodiment, the signal rotor 21 is fitted to the crankshaft 19 in such a way that the reference angle position becomes 15° CA before a bottom dead center, but this angle position may be set at an arbitrary angle position. Moreover, a starter 23 that is driven by electric power supplied from a battery (not shown) and applies an initial rotation to the engine 10 is provided near the engine 10. The ECU 30 is constructed mainly of a microcomputer including a CPU, a ROM, a RAM and the like, and performs various control programs stored in the ROM to control the driving state of the engine 10. Describing the ECU 30 in more detail, the ECU 30 acquires the detection signals of various kinds of sensors such as the above-mentioned crank angle sensor 22 and performs various controls of the engine 10 such as ignition timing control based on the detection signals. In the 4-cycle engine 10, an intake stroke, a compression stroke, a power stroke, and an exhaust stroke are performed in sequence to complete one cycle of its combustion cycle. That is, in the engine 10, one cycle of combustion cycle is completed when the crankshaft 19 is rotated two rotations (720° CA). For this reason, when it is assumed that one rotation corresponding to the intake stroke and the compression stroke is "obverse" and that one rotation corresponding to the power stroke and the exhaust stroke is "reverse", merely by detecting the rotation angle of the crankshaft 19, it cannot be recognized which of "obverse" and "reverse" that rotation is. Hence, it cannot be determined which of strokes that stroke is. Thus, this embodiment notes that a time required for the crankshaft 19 to rotate a specified crank angle, that is, a time required for rotation is different for each of the strokes and makes a stroke determination based on the tendency of change in the time required for rotation. FIG. 2 is a diagram to show the aspect of change in time T30 required for rotation that is required for the crankshaft 19 to rotate 30° CA. A crank angle signal shown in FIG. 2 is such that the output of the crank angle sensor 22 is shaped by filtering or the like. Moreover, a crank angle number Cn is a value obtained by counting each falling edge of the crank angle signal with reference to an initial crank angle signal after a chipped tooth portion (number 0). Here, in the power stroke, the time T30 required for rotation is shortened by a work done by the expansion of gas produced when air-fuel mixture is ignited and combusted by ignition developed near a top dead center. In contrast to this, in the exhaust stroke, the intake stroke, and the compression stroke after the power stroke, the crankshaft 19 is rotated by inertia. At the same time, the crankshaft 19 receives the action of respective braking forces caused by the suction and compression of the air-fuel mixture and by the discharge of the exhaust gas, so that the time T30 required for rotation is elongated. Thus, even when the crank angle numbers Cn are the same, the tendency of a change in the time T30 required for rotation is different from each other. In particular, the tendency is significantly different for the crank angle numbers Cn = 7 to 10 corresponding to the intake stroke and the power stroke. Hence, a difference between two times T30 required for rotation, which are consecutive, is computed as the tendency of a change in the time T30 required for rotation. Then, the difference of the time T30 required for rotation is compared with a stroke determination value found previously by adaptation to determinate which of strokes the present stroke is. FIG. 3 is a flow chart to show the processing procedure of a stroke determination. In this stroke determination processing, the times T30 required for rotation of the crank angle numbers Cn = 8, 9 corresponding to the intake stroke or the power stroke are acquired and time difference AT30 between them is computed. Then, by comparing the time difference AT30 with the respective stroke determination values K1, K2 for the intake stroke and for the power stroke, it is recognized which of strokes the present stroke is. Here, the time difference AT30 becomes a negative comparatively large value in the power stroke and becomes a positive comparatively small value in the intake stroke, so that the stroke determination values K1, K2 are set at different values according to their tendencies (K1 First, in step S101, it is determined whether the stroke determination is not completed. When the stroke determination is not completed, the routine proceeds to step S102. When the stroke determination is completed, this stroke determination processing is finished without performing any processing. In this embodiment, one stroke determination is made for one trip and whether or not the stroke determination is completed is determined based on a determination completion flag F. The determination completion flag F is set at 0 by an initial operation at the time of turning on electric power to the ECU 30 and set at 1 when the stroke determination is completed. Moreover, the determination completion flag F is cleared to zero when the stroke determination needs to be made again, such as when a motorcycle rolls over to cause an engine stall. In step S102, it is determined whether the rotation speed of the engine 10 is within a specified range from a reference rotation speed. When the rotation speed of the engine 10 is within a specified range, the routine proceeds to step S103. When the rotation speed of the engine 10 is not within a specified range, this stroke determination processing is finished without performing any processing. This is due to the following reason. Usually, the starter 23 is used for starting the engine 10 and when the amount of charge of a battery is not sufficient, the engine is started by a kicking operation or a pushing operation. In this case, the aspect of a change in the time T30 required for rotation is varied by the starting operation of a driver, so that a stroke determination cannot be made correctly. Hence, when the rotation speed of the engine 10 is not within a specified range from a reference speed, a stroke determination is not made. Here, the rotation speed of the engine 10 is computed based on the detection signal of the crank angle sensor 22. In step S103, it is determined whether the crank angle number Cn is 8. When the crank angle number Cn is 8, the time T30 required for rotation for the crank angle number Cn = 8 is acquired in step S104, and the acquired value is stored as T30old in step S105. Thereafter, this stroke determination processing is once finished. In contrast, when the crank angle number Cn is not 8, the routine proceeds to step S106. In step S106, it is determined whether the crank angle number Cn is 9. When the crank angle number Cn is 9, the routine proceeds to step S107. When the crank angle number Cn is not 9, this stroke determination processing is finished without performing any processing. In step S107, the time T30 required for rotation for the crank angle number Cn = 9 is acquired, and the acquired value is stored as T30newinstepS108. In subsequent step S109, a time difference AT30 between the T30new and the T30old (AT30 = T30new - T30old) is computed. Then, in step S110, it is determined whether the magnitude of the time difference AT30 is a stroke determination value K1 or less. When the magnitude of the time difference AT30 is a stroke determination value K1 or less, it is determined in step S111 that the present stroke is a power stroke. Thereafter, in step S112, a determination completion flag F for indicating the completion of the stroke determination is set at 1 and this stroke determination processing is finished. In contrast, when the magnitude of the time difference AT30 is not a stroke determination value K1 or less, the routine proceeds to step S113. In step S113, it is determined whether the magnitude of the time difference AT30 is a previously set stroke determination value K2 or more. When the magnitude of the time difference AT30 is the stroke determination value K2 or more, the routine proceeds to step S114 where it is determined that the present stroke is an intake stroke. Thereafter, in step S115, the determination completion flag F for indicating the completion of the stroke determination is set at 1 and this stroke determination processing is finished. In contrast, when the magnitude of the time difference AT30 is not the stroke determination value K2 or more, it is determined that there is brought about a state where it cannot be determined which of strokes the present stroke is, so that this stroke determination processing is finished without determining which of strokes the present stroke is. According to the embodiment described above in detail, the following advantages can be obtained. On the basis of the fact that the tendency of a change in the time T30 required for rotation is different for each stroke, which of strokes the present stroke is is determined by two times T30 required for rotation, which is computed in the same period during which the cylinder volume is increased or decreased by the piston 17. Hence, a stroke determination can be made while the crankshaft 19 is rotated one rotation. Therefore, an appropriate driving control can be performed quickly. In particular, the time T30 required for rotation is acquired within a period during which the cylinder volume is increased or decreased by the piston 17, so that the time T30 required for rotation is acquired in the intake stroke or in the power stroke and the determination of stroke is made. Because the tendency of a change in the time T30 required for rotation is substantially different between the intake stroke and the power stroke, the determination of stroke can be made with more reliability. Further, because two times T30 required for rotation, which are consecutive, are computed and the time difference AT30 between them is determined and compared with the determination reference values K1 and K2, the determination of stroke can be made according to the rate of time change in the time T30 required for rotation. Moreover, because the determination reference value for the power stroke and the determination reference value for the intake stroke are set respectively, when the certainty of determination result is obscure, the determination of stroke is not made but a stroke determination is made again. Further, when the rotation speed of the engine 10 is not within a specified range from the reference rotation speed at the time of starting the engine 10, that is, when the tendency of a change in the time T30 required for rotation is varied by the operation of the driver such as a kicking operation or a pushing operation, a stroke determination is not made. With this, an erroneous determination can be avoided. (Second Embodiment) In a second embodiment, every time the crankshaft 19 is rotated one rotation, the same stroke determination as shown in FIG. 3 is made and its determination result is applied as a provisional result to various engine controls. When a plurality of correct stroke determinations are made consecutively, the determination result is fixed. A processing procedure of a stroke determination in this embodiment is shown in FIG. 4. In FIG. 4, the same processings as in FIG. 3 are denoted by the same step numbers. The descriptions will be presented on a focus of differences between them. In the stroke determination processing shown in FIG. 4, when a stroke determination is made correctly and stroke determinations of a specified number of times K3 (four in this embodiment) are made consecutively, the determination result is fixed and the number of times of the stroke determinations is counted by the use of a determination counter C. The determination counter C is initialized to zero by an initial operation at the time of turning on electric power to the ECU 30 and is incremented by one every time the stroke determination is made. Moreover, when the result of the stroke determination is erroneous or the stroke determination cannot be made consecutively, the determination counter C is cleared to zero. First, in step S101, it is determined whether a stroke determination is not completed. When a stroke determination is not completed, the routine proceeds to step S102, and when a stroke determination is completed, this stroke determination processing is finished without performing any processing. In step S102, it is determined whether a rotation speed is within a specified range from a reference rotation speed. When a rotation speed is within a specified range from a reference rotation speed, the routine proceeds to step S120. When a rotation speed is not within a specified range, the routine proceeds to step S121. In step S121, the determination counter C is cleared to zero and this stroke determination processing is finished because it is determined that the correct stroke determination is not made consecutively. In step S120, just as with step S103 to S109, the times T30 required for rotation for the crank angle numbers Cn = 8, 9 are acquired and are stored as T30old and T30new and the time difference AT30 between them (AT30 = T30new - T30old) is computed. Thereafter, the routine proceeds to step S122. In step S122, it is determined whether the magnitude of the time difference AT30 is the stroke determination value K1 or less. When the magnitude of the time difference AT30 is the stroke determination value K1 or less, the routine proceeds to step S123 where it is provisionally determined that the present stroke is a power stroke and the routine proceeds to step S126. In contrast, when the magnitude of the time difference AT30 is not the stroke determination value K1 or less, the routine proceeds to step S124. In step S124, it is determined whether the magnitude of the time difference AT30 is the stroke determination value K2 or more. When the magnitude of the time difference AT30 is the stroke determination value K2 or more, the routine proceeds to step S125 where it is provisionally determined that the present stroke is an intake stroke and the routine proceeds to step S126. In contrast, when the magnitude of the time difference AT30 is not the stroke determination value K2 or more, it is determined that there is brought about a state where it cannot be determined which of strokes the present stroke is, so that the routine proceeds to step S121 where the determination counter C is cleared to zero. In step S126, it is determined whether this determination result is the same as the last determination result. When this determination result is the same as the last determination result, it is determined that an erroneous determination is made, so that the routine proceeds to step S121 where the determination counter C is cleared to zero. In contrast, when this determination result is different from the last determination result, the determination counter C is incremented and it is determined in step S128 whether or not the determination counter C is a specified number of times K3 or more. When the determination counter C is a specified number of times K3 or more, the determination result is fixed in step S129 and the determination completion flag F is set at 1 in step S130 and this stoke determination processing is finished. In contrast, when the determination counter C is not a specified number of times K3 or more, this stoke determination processing is finished once and the stroke determination processing is performed again. According to the embodiment described above in detail, the following advantages can be obtained. Various controls are performed by using a determination result obtained every time the crankshaft 19 is rotated one rotation as a provisional determination result and when a plurality of correct stroke determinations are made consecutively, the determination result is fixed. With this, the reliability of the determination result is improved. Moreover, one stroke determination is made while the crankshaft 19 is rotated one rotation, so that two stroke determinations can be made during one cycle of a combustion cycle. Therefore, reliability can be improved as compared with the related art in which one stroke determination is made during one cycle of a combustion cycle. Incidentally, the present invention is not limited to the above-mentioned embodiments but may be implemented as follows. In the above-mentioned embodiments, the stroke determination is made based on the difference between two times required for rotation, which are consecutive. However, the way to make a stroke determination is not limited to this, but it can be thought that the following constructions (1) and (2) and a combination of them are used for making a stroke determination. (1) A stroke determination is made based on two times T30 required for rotation, which are not consecutive. As shown in FIG. 2, when the piston 17 is moving in the same direction, that is, in the same stroke, the tendency of change in the time T30 required for rotation is the same. Hence, a stroke determination can be made also based on a difference between two times T30 required for rotation, which are not consecutive. Moreover, paying attention on the two times T30 required for rotation, which are not consecutive, the time difference AT30 between the two times T30 required for rotation becomes large and hence a stroke determination can be made easily. (2) A stroke determination is made based on a ratio between two times T30 required for rotation. The time T30 required for rotation becomes short comparatively quickly in the power stroke and becomes long comparatively gently in the intake stroke. For this reason, the ratio is separate from 1 in the power stroke, whereas the ratio becomes close to 1 in the intake stroke. Hence, it is possible determine which of strokes the present stroke is by comparing the ratio with a previously set stroke determination value. In the above-mentioned embodiments, the stroke determination values K1 and K2 are set for the power stroke and for the intake stroke, but the stroke determination can be made also by setting K1 = K2 = α. In this case, when the time difference AT30 is smaller than the stroke determination value a, the present stroke is determined to be the power stroke, and when the time difference AT30 is larger than the stroke determination value a, the present stroke is determined to be the intake stroke. In the above-mentioned embodiments, the crank angle interval of the projections in the signal roller 21 is equal to a specified crank angle as an object for which a time required for rotation is computed, but the construction is not limited to this. There may be employed a construction in which the crank angle interval of the projections is different from a specified crank angle as an object for which a time required for rotation is computed, for example, a construction in which a specified crank angle is set at an integral multiple of the crank angle interval of the projections. Also in this construction, it is possible to determine which of strokes the present stroke is on the basis of computed two times required for rotation. Moreover, the crank angle interval of the projections in the crank angle sensor 22 is set at 30° CA, but the crank angle interval is not limited to this. A crank angle interval may be smaller than 30° CAor may be larger than 30° CA. WHAT IS CLAIMED IS: 1. A controller for a single-cylinder 4-cycle engine (10) that rotates a crankshaft (19) by reciprocating a piston (17) in a cylinder to increase and decrease a cylinder volume (200), the controller comprising: a crank angle sensor (22) outputting a rotation detection signal every time the crankshaft (19) is rotated a predetermined angle; a computing means (30) for computing a time period required for rotating the crankshaft (19) a predetermined crank angle at a reference angle position on the crankshaft on the basis of an output of the crank angle sensor (22); and a determination means (30) for making a stroke determination on the basis of two sequential times required for rotation, which are computed by the computing means within a period during which the cylinder volume (200) is increased or within a period during which the cylinder volume (200) is decreased. 2. A controller for a single-cylinder 4-cycle engine according to claim 1, wherein the reference angle position is an angle position within a period during which the cylinder volume (200) is increased by the piston. 3. A controller for a single-cylinder 4-cycle engine according to claim 2, wherein the determination means compares a difference between two consecutive times required for rotation, which are computed by the computing means, with a previously determined determination reference value to determine which of strokes a present stroke is. 4. A controller for a single-cylinder 4-cycle engine according to claim 1, wherein when a rotation speed of the engine is out of a predetermined range from a predetermined reference rotation speed at the time of starting up the engine, no stroke determination is made. 5. A controller for a single-cylinder 4-cycle engine according to claim 1, wherein the determination means sets a determination result obtained every time the crankshaft is rotated one rotation as a provisional result and fixes the determination result when a specified number of provisional results are obtained normally consecutively. Dated this 4 day of January 2007

Documents:

021-che-2007-abstract.pdf

021-che-2007-claims.pdf

021-che-2007-correspondnece-others.pdf

021-che-2007-description(complete).pdf

021-che-2007-drawings.pdf

021-che-2007-form 1.pdf

021-che-2007-form 18.pdf

021-che-2007-form 26.pdf

021-che-2007-form 3.pdf

021-che-2007-form 5.pdf

21-CHE-2007 CORRESPONDENCE OTHERS 17-08-2010.pdf