WO2013015779A2

WO2013015779A2 - Starting system for an engine

Info

Publication number: WO2013015779A2
Application number: PCT/US2011/045174
Authority: WO
Inventors: Neal Chandler; Timothy CHOTE; Mikael HOLMDHAL; Mosheeer Abdelgalil
Original assignee: Husqvarna Consumer Outdoor Products Na, Inc.; ABDELGALIL, Anna María
Priority date: 2011-07-25
Filing date: 2011-07-25
Publication date: 2013-01-31
Also published as: WO2013015779A3

Abstract

A starting system includes an energy-storing hub assembly and a final member being operative to rotate about a first rotational axis. The energy-storing hub assembly includes an energy-storing hub and a resilient member, the resilient member being connected to the energy-storing hub and the final member. An electric motor is also provided to rotate the final member. Further, a locking member is configured to selectively lock the energy-storing hub such that energy is accumulated in the resilient member. Moreover, an energy-release cam is arranged to actuate the locking member such that the energy-storing hub is unlocked, thereby releasing the energy accumulated in the resilient member. Consequently, the energy-storing hub rotates and starts the internal combustion engine.

Description

STARTING SYSTEM FOR AN ENGINE

TECHNICAL FIELD

The present invention relates to a starting system. In particular, the present invention relates to a starting system for an internal combustion engine.

BACKGROUND

Handheld products powered by internal combustion engines, such as, chainsaws, hedge trimmers, line trimmers, blowers, or the like, are well know in the art. An internal combustion engine for hand-held products is usually started manually by rotating a starter pulley via a rope. However, manual starting may require a lot of physical effort on part of the user thereby causing fatigue or injury. To avoid this, an electric starter, having an electric motor powered by a battery or mains power supply, is used for starting the internal combustion engine. However, in the case of a battery, the battery may be discharged in locations where charging means or a spare battery is not always present and, in case of main power supply, there may be a lack of access to such power.

As a solution to the above problems, starting systems that integrate a manual starter and an electric starter have been proposed in the art. For example, JP Patent Publication 2, 146,260 published on June 5, 1990 and assigned to Mitsubishi Heavy Industries, LTD titled "SPIRAL-SPRING-TYPE STARTER FOR GENERAL- PURPOSE GASOLINE ENGINE", discloses a starting system, for an internal combustion engine, utilizing a spiral spring. The electric starter includes a spiral spring which is wound up by an electric starter or by a hand crank. When sufficient energy is accumulated in the spiral spring, the spiral spring is unwound to start the internal combustion engine. When using the electric starter, an electronic system is used to control the unwinding of the spiral spring. However, such an electronic system, having sensors and a solenoid, may be expensive and complex.

SUMMARY

An exemplary embodiment of a starting system includes an energy-storing hub assembly and a final member being operative to rotate about a first rotational axis. The energy-storing hub assembly includes an energy-storing hub and a resilient member, the resilient member being connected to the energy-storing hub and the final member. An electric motor is also provided to rotate the final member. Further, a locking member is configured to selectively lock the energy-storing hub such that energy is accumulated in the resilient member. Moreover, an energy-release cam is arranged to actuate the locking member such that the energy-storing hub is unlocked, thereby releasing the energy accumulated in the resilient member. Consequently, the energy-storing hub rotates and starts the internal combustion engine. The locking member is mechanically actuated by the energy-release cam to determine the duration of accumulation of energy in the resilient member for starting the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Several representative embodiments will in the following be described in more detail with reference to the enclosed drawings, wherein:

FIG . 1 illustrates a schematic view of a device powered by an internal combustion engine with a starting system;

FIG. 2 illustrates an exploded view of the starting system for the internal combustion engine, according to an exemplary embodiment;

FIG.3 illustrates a sectional view of the starting system of the embodiment of FIG. 2; FIG. 4 illustrates a front view of the starting system of FIGS. 2 and 3, with a housing cover removed;

FIG. 5 illustrates a perspective view of a locking member and an energy-release cam, according to another embodiment;

FIG. 6 illustrates a detailed view of the energy-release cam of the embodiment of FIG. 5;

FIG. 7 illustrates an exploded view of the starting system for the internal combustion engine, according to another exemplary embodiment;

FIG. 8 illustrates an exploded view of the starting system for the internal combustion engine, according to yet another exemplary embodiment; and

FIG. 9 illustrates an exploded view of the starting system for the internal combustion engine, according to yet another exemplary embodiment.

DESCRI PTION OF EMBODIMENTS

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the invention incorporating one or more aspects of the present invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. For example, one or more aspects of the present invention can be utilized in other embodiments and even other types of devices. In the drawings, like numbers refer to like elements.

FIG. 1 illustrates a device D powered by an internal combustion engine E (hereinafter referred to as "the engine E"), according to an embodiment of the present invention. The device D may be any type of powered device D, such as, but not limited to, hand-held tools, mowers, and outboard motors. Further, the internal combustion engine E may be any type, for example, a two-stroke engine, a four- stroke engine, or the like. The engine E may drive any working member of the device D, for example, a cutting member, a propeller, a blower, or the like. Moreover, a starting system S is provided for starting the engine E. In various embodiments of the present invention, the starting system S may be able to start the engine E both manually and electrically while, in other embodiments, only electrically is accommodated.

FIGS. 2-4 illustrate a starting system S for the engine E, according to an embodiment of the present invention. As illustrated in FIGS. 2 and 3, the starting system S includes an energy-storing assembly 102, a final member 104, and a manual starter pulley 106 (hereinafter referred to as "the pulley 106" with reference to FIGS. 2-4) configured to rotate about a first rotational axis R1. The energy-storing assembly 102 includes an energy-storing hub 108 (hereinafter referred to as the "hub 108" with reference to FIGS. 2-4) and a resilient member 10. The resilient member 110 is a torsion spring in the present embodiment, as illustrated in FIGS. 2-4. However, any type of resilient member may be used in place of a torsion spring, for example, one or more rubber discs. The hub 108 includes an engaging portion 112 which includes one or more mating projections 114. The mating projections 114 are utilized for attaching the engaging portion 112 with a corresponding part of the engine E, for example, but not limited to, a flywheel or a crankshaft. Thus, the starting system S starts the engine E by rotating the flywheel or the crankshaft, for example, via the hub 108.

The starting system S also includes a housing 116 and a housing cover 118 to enclose at least some components of the starting system S. As illustrated in FIG. 3, the engaging portion 112 of the hub 108 projects out of the housing cover 118 for attachment with a corresponding part of the engine E. The housing 116 and the housing cover 118 may be connected to each other via one or more mechanical fasteners (not shown). Sealing members may also be provided at an interface between the housing 116 and the housing cover 118. Further, the housing 116 includes an integral shaft 120 on which at least the hub 108, the final member 104 and the pulley 106 are mounted. In this embodiment, the shaft 120 has a stepped design to limit axial movement of the various mounted components. However, in other embodiments, various other shaft designs may be used.

For manual starting of the engine E, the pulley 106 is manually rotated via a pull member 123, for example, a pull rope wound around a groove 121 of the pulley 106. The pull rope may include a handle at one end so that the handle can be grasped and pulled by an operator. A second resilient member 122 is connected to the pulley 106 such that energy is stored in the second resilient member 122 when the pulley 106 is rotated by manual movement of the pull member 123. The second resilient member 110 is a torsion spring in the present embodiment, as illustrated in FIGS. 2-4. However, any type of resilient member may be used in place of a torsion spring, for example, one or more rubber discs. The second resilient member 122 accumulates energy when the pulley 106 is rotated and releases the energy when the pull member 123 is released. Further, a one-way clutch 124 is provided between the final member 104 and the pulley 106 to only transmit rotary motion from the pulley 106 to the final member 104 and not vice versa. The final member 104 rotates the hub 108 via the resilient member 110. Finally, the hub 108 starts the engine E via the engaging portion 112.

In addition to manual starting, the starting system S also includes an electric motor 126 (hereinafter referred to as "the motor 126" with reference to FIGS. 2-4) for starting of the engine E. The motor 126 may be any type of electric motor, for example, an AC motor or a DC motor. Further, the motor 126 may be driven by a battery or directly from a mains power source. The motor 126 is at least partly enclosed within a motor housing 127 which protrudes from the housing cover 118. The motor 126 includes a driveshaft 128 which drives a reduction gear set 130. The driveshaft 128 and the reduction gear set 130 rotate about a second rotational axis R2 which is substantially parallel to and offset from the first rotational axis R1. In other embodiments, various other configurations can be used, such as an orthogonal arrangement of axes.

As illustrated in FIGS. 2 and 3, the reduction gear set 130 is located inside a gear housing 132. The gear housing 132 may include projections on an outer surface which engage with complementary features on an inner surface of the housing 116 for circumferentially fixing the gear housing 132 with respect to the housing 116. Further, the reduction gear set 130 is a planetary gear set with a first ring gear 135 (shown in FIG. 3) formed on an inner surface of the gear housing 132. The reduction gear set 130 also includes a first reduction stage 136 and a second reduction stage 137. The first reduction stage 136 includes a sun gear 138 (shown in FIG. 3) such that the driveshaft 128 is coupled to the sun gear 138 of the first reduction stage 136. Further, the first reduction stage 136 also includes three planet gears 140 which are disposed around the sun gear 138. The planet gears 140 engage with the first ring gear 135 such that the planet gears 140 simultaneously rotate about their own axes as well as revolve around the sun gear 138. A carrier member 141 is connected to each of the planet gears 140 such that the carrier member 141 rotates with revolution of the planet gears 140 around the sun gear 138. The carrier member 141 includes attachment sections 142 (shown in FIG. 3) which are inserted into central apertures of the corresponding planet gears 140. Further, the carrier member 141 includes a gear section 144 (shown in FIG. 3) which acts as a sun gear for the second reduction stage 137. Similar to the first reduction stage 136, three planet gears 145, of the second reduction stage 137, are disposed around the gear section 144 of the carrier member 141. The planet gears 145 also engage with the first ring gear 135 such that the planet gears 145 simultaneously rotate about their own axes as well as revolve around the gear section 144 of the carrier member 141. Moreover, an elongate member 146 is connected to each of the planet gears 145 such that the elongate member 146 rotates with revolution of the planet gears 145 around the gear section 144. The elongate member 146 acts as the output of the reduction gear set 130.

Further, the elongate member 146 includes three gear connecting portions 147 (shown in FIG. 3) which are inserted into central apertures of the corresponding planet gears 145. The elongate member 146 also includes an attachment portion 148 and a gear portion 150. The attachment portion 148 may be attached to a drive member 149 by splines which mate with corresponding grooves present on a central aperture of the drive member 149. As illustrated in FIGS. 2 (shown in dotted lines) and 3, the drive member 149 is also configured to rotate about the second rotational axis R2. The gear housing 132 also includes an opening such that the drive member 149 can engage with the final member 104. Further, in the embodiment illustrated in FIGS. 2-4, the final member 104 and the drive member 149 are gears which mesh with each other.

Further, the gear portion 150 of the elongate member 146 drives the cam gear set 154 which is also configured to rotate about the second rotational axis R2. The cam gear set 154 is also a planetary gear set such that the gear portion 150 of the elongate member 146 acts as a sun gear. The cam gear set 154 is substantially enclosed within the gear housing 132. The gear housing 132 also includes a second ring gear 158 formed on an inner surface. Further, the cam gear set 154 includes three planet gears 160 disposed around the gear portion 150. Each of the planet gears 160 is also integrated with an additional gear 161 which engages with the second ring gear 158. This enables the planet gears 160 to simultaneously rotate about their own axes as well as revolve around the gear portion 150.

In other embodiments, the reduction gear set 130 and the cam gear set 154 may be provided in other configurations. For example, there can be any other number of planet gears in both the reduction gear set 130 and the cam gear set 154. Further, the reduction gear set 130 may only include one reduction set. The gears (including the final member 104 and the drive member 149) may be any type of gear, for example, spur, helical, herringbone, or the like. The reduction gear set 130 and/or the cam gear set 154 may also be any other type of gear drive other than planetary gears sets, for example, conventional gear drive, bevel drive, worm drive etc.

As illustrated in FIGS. 2 and 3, an energy-release cam 162 (hereinafter referred to as "the cam 162" with reference to FIGS. 2-4) is attached to the planet gears 160 such that the cam 162 rotates with the revolution of the planet gears 160 about the second rotational axis R2. Further, due to the cam gear set 154, the cam 162 may rotate at a lower rotational speed than the final member 104. The cam 162 is a disc with a cam lobe 164 protruding from the disc. In some embodiments of the present invention, the cam lobe 164 has a length which extends to about one-third the circumference of the disc. During rotation of the cam 162, the cam lobe 164 actuates a locking member 166 which is operative to selectively lock the hub 108. The locking member 166 includes a ratchet 168 which is mounted on a pin 170 and normally biased by a ratchet spring 172 in a locking position. The cam 162 is partially enclosed within a cam housing 173 which has an opening so that the cam lobe 164 may actuate the locking member 166. The cam housing 173 is located between the gear housing 132 and the motor housing 127. Further, the pin 170 is mounted on the cam housing 173.

As illustrated in FIG 4, the ratchet 168 engages with any one of locking teeth 174 of the hub 108 in the locking position, thereby preventing the hub 108 from rotating. The cam lobe 164 engages with an actuating portion 176 of the ratchet 168 such that the ratchet 168 rotates against a biasing force of the ratchet spring 172 to a released position and disengages with a locking tooth 174. Consequently, the hub 108 is permitted to rotate as long as the cam lobe 164 remains engaged with the actuating portion 176 of the ratchet 168. Thus, in a full rotation of the cam 162, the hub 108 is allowed to rotate along the length of the cam lobe 164 and remains locked along the rest of the circumference of the cam 162.

For electric starting of the engine E, the driveshaft 128 of the motor 126 rotates the reduction gear set 130. The elongate member 146 then drives the drive member 149 and the cam gear set 154. The drive member 149 rotates the final member 104 while the cam gear set 154 rotates the cam 162. The pulley 106 does not rotate with the final member 104 due to the one-way clutch 124. The hub 108 also does not rotate as the hub 108 is locked by the ratchet 168. Thus, the resilient member 110 winds and energy is accumulated in the resilient member 110. Subsequently, due to the rotation of the cam 162, the cam lobe 164 actuates the ratchet 168 to the released position such that the hub 108 is unlocked. As a result, the resilient member 110 is released and rotates the hub 108 for starting the engine E. In an embodiment of the present invention, the hub 108 is locked and the resilient member 10 is wound for about one to five rotations of the final member 104, and then the hub 108 is unlocked so that the resilient member 110 can release the accumulated energy.

The starting system S uses the reduction gear set 130, the cam gear set 154 and the cam 162 to determine the duration of accumulation and subsequent release of energy in the resilient member 110 for starting the engine E. Thus, the starting system S may eliminate the need for a complicated and expensive electronic system involving sensors and solenoid. The co-axial arrangement of the reduction gear set 130, the cam gear set 154 and the cam 162 with respect to the driveshaft 128 of the motor 126 may also lead to a compact configuration of the starting system S. The starting system S may also be easily retrofitted with existing internal combustion engines, the engaging portion 12 of the hub 108 being easily attachable to an internal combustion engine (E.g., at the flywheel or the crankshaft). The integration of manual and electric starting may also improve the portability of the starting system S.

Note that the cam 162 may be configured differently in other embodiments. For example, the cam 162 may include multiple lobes and may be located at any other location within the starting system S. Further, the locking member 166 may include another mechanism, for example, a friction band (not illustrated in the figures) which is operative to selectively lock the hub 108. In such a case, the friction band may be selectively actuated by the cam 162.

FIGS. 5 and 6 illustrate a locking member 202 and a cam 204, according to another embodiment of the present invention. Various components of the starting system S, including the resilient member 110, are not shown for clarity. As illustrated in FIGS. 5 and 6, an energy-storing hub 205 (hereinafter referred to as "the hub 205" with reference to FIGS. 5 and 6) includes locking teeth 206 on the circumference. The locking member 202 includes a ratchet 208 with multiple projections 210 such that the projections 210 can selectively engage the locking teeth 206 in the locked position and prevent the hub 205 from rotating. The ratchet 208 may move in a substantially vertical direction between the locking position and the released position. Further, the ratchet 208 may be normally biased in the locking position by the ratchet spring (not illustrated in FIGS. 5 and 6).

As illustrated in FIGS. 5 and 6, the cam 204 is rotatable relative to the final member 104. The cam 204 may be rotatably mounted on the housing 116. The cam 204 includes a cam lobe 212 which selectively engages with an actuating portion 214 of the ratchet 208. The cam 204 also includes multiple actuating lobes 216 which are angularly displaced by a trigger member 218 formed on the final member 104. In an embodiment of the present invention, the cam 204 includes five actuating lobes 216 which are equally spaced about 360 degrees.

During rotation of the final member 104, the actuating lobes 216 are angularly displaced by the trigger member 218 such that the ratchet 208 is in the locking position for a predetermined fraction of a whole rotation of the cam 204. In an embodiment of the present invention, the ratchet 208 is in the locking position for about three-fifth of a whole rotation of the cam 204 which is roughly equivalent to an angular spacing of three actuating lobes 216. During the rest of the rotation of the cam 204, the cam lobe 212 engages the actuating portion 214 of the ratchet 208, thereby lifting the ratchet 208 to the released position, as illustrated in FIGS. 5 and 6.

It should be noted that the cam 204 does not require a cam gear set 154 for actuation. Thus, in the embodiment illustrated in FIGS. 5 and 6, the cam gear set 154 is not present. Absence of the cam gear set 154 may lead to a further reduction in size and cost of the starting system S. However, the drive member 149 may be rotated by the motor 126 via the reduction gear set 130, as described in conjunction with FIGS. 2 and 3.

Alternative mechanisms may be utilized to simulate the motion of a cam and a locking member. For example, a spiral follower mechanism (not illustrated in the figures) may be used. In such a case, the spiral may act as the cam while the follower acts as the locking member. The follower is constrained to move along a spiral groove provided on the spiral. The follower locks the hub when the follower is located in a first region of the spiral region. When the follower is located in a second region of the spiral region, the follower releases the hub. The follower and the spiral may be reset to an initial position after a starting procedure due to the presence of one or more biasing members, such as, springs.

FIG. 7 illustrates an exploded view of the starting system S, according to another embodiment of the present invention. The starting system S includes an energy-storing assembly 302, a final member 304, and a manual starter pulley 306 (hereinafter referred to as "the pulley 306" with reference to FIG. 7) configured to rotate about a first rotational axis R3. The final member 304 is a gear in the present embodiment. Further, the energy-storing assembly 302 includes an energy-storing hub 308 (hereinafter referred to as the "hub 308" with reference to FIGS. 7) and a resilient member 310. The resilient member 310 is a torsion spring in the present embodiment, as illustrated in FIG. 7. The hub 308 includes an engaging portion 312 which includes one or more mating projections 314. The mating projections 314 are utilized for attaching the engaging portion 312 with a corresponding part of the engine E, for example, but not limited to, a flywheel or a crankshaft. Thus, the starting system S starts the engine E by rotating the flywheel or the crankshaft, for example, via the hub 308.

The starting system S also includes a housing 316 and a housing cover (not illustrated in FIG. 7) to enclose at least some components of the starting system S. Further, the housing 316 includes an integral shaft 318 on which at least the hub 308, the final member 304 and the pulley 306 are mounted.

For manual starting of the engine E, the pulley 306 is manually rotated via a pull member (not illustrated in FIG. 7), for example, a pull rope wound around a groove 320 of the pulley 306. The pull rope may include a handle at one end so that the handle can be grasped and pulled by an operator. A second resilient member 322 is connected to the pulley 306 such that energy is stored in the second resilient member 322 when the pulley 306 is rotated by manual movement of the pull member. The second resilient member 322 is a torsion spring in the present embodiment, as illustrated in FIG. 7. The second resilient member 322 accumulates energy when the pulley 306 is rotated and releases the energy when the pull member is released. Further, a one-way clutch 324 is provided between the final member 304 and the pulley 306 to only transmit rotary motion from the pulley 306 to the final member 304 and not vice versa. The final member 304 rotates the hub 308 via the resilient member 310. Finally, the hub 308 starts the engine E via the engaging portion 312.

In addition to manual starting, the starting system S also includes an electric motor 325 (hereinafter referred to as "the motor 325" with reference to FIG. 7) for starting of the engine E. The motor 325 is at least partly enclosed within a motor housing 326 and a motor housing cover 327. The motor 325 includes a driveshaft 328 which drives a transmission assembly 330. The driveshaft 328 and different components of the transmission assembly 330 rotate about a second rotational axis R4 which is substantially parallel to and offset from the first rotational axis R3.

As illustrated in FIG. 7, the transmission assembly 330 includes a reduction gear set 332, a cam gear set 334, a first carrier 336, a second carrier 338 and an elongate member 340. Further, the transmission assembly 330 is located inside a transmission housing 342. Moreover, the reduction gear set 332 and the cam gear set 334 are planetary gear sets. The reduction gear set 332 is provided with the first carrier 336, while the cam gear set 334 is provided with the second carrier 338. A ring gear 344 is formed on an inner surface of the transmission housing 342 such that the ring gear 344 acts as a stationary ring gear for both the reduction gear set 332 and the cam gear set 334. Moreover, the elongate member 340 acts as the output of the reduction gear set 332. The elongate member 340 includes a gear portion (not shown in FIG. 7) and an attachment portion 345. The gear portion acts as an input for the cam gear set 334 while the attachment portion 345 is configured to engage with a corresponding engaging part 346. The engaging part 346 is integrated to a drive member 348. As illustrated in FIG. 7, the drive member 348 is a gear which drives an intermediate gear 350. Further, the intermediate gear 350 drives the final member 304.

Further, the second carrier 338 includes an energy-release cam 352 (hereinafter referred to as "the cam 352" with reference to FIG. 7) which rotates with the second carrier 338 about the second rotational axis R4. The cam 352 may rotate at a lower rotational speed than the final member 304 due to the cam gear set 334. The cam 352 actuates a locking member 354 which is operative to selectively lock the hub 308. The locking member 354 includes a ratchet 356 which normally biased by a ratchet spring 358 in a locking position. In the locking position, the ratchet 356 engages with locking teeth 360 provided on the hub 308, thereby locking the hub 308. Further, the transmission housing 342 has an opening so that the ratchet 356 may protrude out while an actuating portion 362 is located inside the transmission housing 342 and is actuated by the cam 352.

For electric starting of the engine E, the driveshaft 328 of the motor 325 rotates the reduction gear set 332. The elongate member 340 then drives the drive member 348 and the cam gear set 334. The drive member 348 rotates the final member 304 via the intermediate gear 350. Moreover, the cam gear set 334 rotates the cam 352 via the second carrier 338. The pulley 306 does not rotate with the final member 304 due to the one-way clutch 324. The hub 308 also does not rotate as the hub 308 is locked by the ratchet 356. Thus, the resilient member 310 gets wound up and energy is accumulated in the resilient member 310. Subsequently, due to the rotation of the cam 352, the cam 352 actuates the ratchet 356 to a released position such that the hub 308 is unlocked. As a result, the resilient member 310 is released and rotates the hub 308 for starting the engine E.

FIG. 8 illustrates an exploded view of the starting system S, according to another embodiment of the present invention. The embodiment illustrated in FIG. 8 is substantially similar to the embodiment illustrated in FIG. 7. However, in the present embodiment, a final member 402 and a drive member 404 are belt sprockets. Further, the drive member 404 drives the final member 402 via a belt 406. The belt 406 may be a toothed belt to prevent slipping.

FIG. 9 illustrates an exploded view of the starting system S, according to another embodiment of the present invention. The starting system S includes a final member 502, a manual starter pulley 504 (hereinafter referred to as "the pulley 504" with reference to FIG. 9) and an energy-storing hub assembly 506 configured to rotate about a first rotational axis R5. The energy-storing hub assembly 506 includes an energy-storing hub 508 (hereinafter referred to as "the hub 508" with reference to FIG. 9), a common hub 510 and a resilient member 511. The resilient member 511 is connected to the final member 502 and the hub 508. The resilient member 511 is a torsion spring in the present embodiment, as illustrated in FIG. 9. Further, the common hub 510 includes an engaging portion 512 with one or more mating projections 514 which engage with a corresponding part of the engine E, for example a flywheel 516. Further, as illustrated in FIG. 9, the various parts of the starting system S are at least partly enclosed by a housing 518 and a housing cover 520. The engaging portion 512 of the common hub 510 projects out of the housing cover 520 so that the engaging portion 512 may engage with the flywheel 516.

For manual starting of the engine E, the pulley 504 is manually rotated via a pull member 521. A second resilient member 523 is connected to the pulley 504 such that energy is stored in the second resilient member when the pulley 504 is rotated. The second resilient member 523 is a torsion spring in the embodiment illustrated in FIG. 9. Thus, the second resilient member 523 accumulates energy when the pulley 504 is rotated and releases energy when the pulley 504 is released. Further, a set of manual starter dogs (not shown in FIG. 9) are provided on the pulley 504 to only transmit rotary motion from the pulley 504 to the common hub 510. The manual starter dogs engage with locking projections 522 of the common hub 510, thereby rotating the common hub 510. Hence, the common hub 510 rotates the flywheel 516 and starts the engine E.

The starting system S, as illustrated in Fig. 9, also includes an electric motor 524 (hereinafter referred to as "the motor 524" with reference to FIG. 9) for electrically starting the engine E. The motor 524 is at least partly enclosed within a motor housing 526 which may protrude from the housing cover 520. A driveshaft 528 of the motor 524 drives a reduction gear set 530. A fixing member 532 secures the reduction gear set 530 to a gear housing 533. In some embodiments of the present invention, the reduction gear set 530 may be a planetary gear set. Further, the motor housing 526 may be integral with the gear housing 533. The reduction gear set 530 rotates a drive member 534 which in turn rotates the final member 502. The driveshaft 528, the reduction gear set 530 and the drive member 534 rotate about a second rotational axis R6 which is parallel to and offset from the first rotational axis R5.

The final member 502 includes a sun gear portion (not shown in FIG. 9) which rotates a cam gear set 536. The cam gear set 536 is a planetary gear set with three planet gears 538 disposed around the sun gear portion of the final member 502. The planet gears 538 also engage with a ring gear 539 provided on an inner surface of the housing 518 such that the planet gears 538 simultaneously rotate about their own axes as well as revolve around the sun gear portion of the final member 502. Further, an energy-release cam 540 (hereinafter referred to as "the cam 540" with reference to FIG. 9) is attached to the planet gears 538 such that the cam 540 rotates with the revolution of the planet gears 538 around the sun gear portion of the final member 502. Thus, the cam gear set 536 and the cam 540 rotate about the first rotational axis R5.

As illustrated in FIG. 9, the cam 540 includes a cam lobe 542 which actuates a locking member 544 during rotation of the cam 540. The locking member 544 includes a ratchet 546 which is normally biased in a locking position by a spring member (not shown in FIG. 9). As illustrated in FIG. 9, the ratchet 546 engages locking teeth 548 of the hub 508 to lock the hub 508.

For electric starting of the engine E, the driveshaft 528 of the motor 524 drives the reduction gear set 530 which in turn rotates the drive member 534. The drive member 534 then rotates the final member 502. Hence, the sun gear portion of the final member 502 rotates the cam 540 via the cam gear set 536. However, the hub 508 is locked by the ratchet 546. Thus, the resilient member 511 winds and energy is accumulated in the resilient member 5 1. Subsequently, due to the rotation of the cam 540, the cam lobe 542 actuates the ratchet 546 to a released position and the hub 508 is unlocked. As a result, the resilient member 5 1 is released and rotates the hub 508. Further, the hub 508 includes a set of hub starter dogs 550 which selectively engages with locking projections 522 of the common hub 510 to only transmit rotary motion from the hub 508 to the common hub 510. Finally, the common hub 510 rotates the flywheel 516 to start the engine E.

In the drawings and specification, there have been disclosed several exemplary embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.

Claims

1. A starting system for use with an internal combustion engine, the starting system comprising:

an energy-storing hub assembly and a final member operative to rotate about a first rotational axis;

the energy-storing hub assembly comprising an energy-storing hub and a resilient member, wherein the resilient member is connected to the energy-storing hub and the final member;

an electric motor operative to rotate the final member;

a locking member operative to selectively lock the energy-storing hub such that energy is accumulated in the resilient member; and

an energy-release cam operative to actuate the locking member such that the energy-storing hub is unlocked and the energy accumulated in the resilient member is released to rotate the energy-storing hub for starting the internal combustion engine.

2. The system of claim 1 , wherein the electric motor drives a reduction gear set, the reduction gear set being operative to drive a drive member, and the drive member being operative to drive the final member.

3. The system of claim 2, wherein the final member and the drive member are gears.

4. The system of claim 3, wherein the drive member directly drives the final member.

5. The system of claim 3, wherein the drive member drives the final member via an intermediate gear.

6. The system of claim 2, wherein:

the drive member drives the final member via a belt; and the drive member and the final member are belt sprockets.

7. The system of claim 2, wherein the reduction gear set drives a cam gear set, the cam gear set being operative to drive the energy-releasing cam.

8. The system of claim 7, wherein the reduction gear set and the cam gear set are planetary gear sets.

9. The system of claim 7, wherein a driveshaft of the electric motor, the energy- release cam, the reduction gear set, the drive member and the cam gear set are operative to rotate about a second rotational axis which is offset from the first rotational axis.

10. The system of claim 1 , wherein:

the locking member comprises a ratchet, the ratchet being normally biased in a locking position; and

the energy-storing hub comprises at least one locking tooth, the ratchet being operative to engage with the locking tooth on the energy-storing hub in the locking position.

11. The system of claim 10, wherein:

the energy-release cam comprises at least one cam lobe; and the cam lobe is operative to selectively actuate the ratchet to a released position such that the ratchet disengages with the locking tooth of the energy-storing hub.

12. The system of claim 10, wherein:

the energy-release cam further comprises a plurality of actuating lobes, the energy-release cam being rotatable relative to the final member; and

the final member comprises a trigger member, the trigger member is operative to displace one of the plurality of actuation lobes such that the cam lobe selectively actuates the ratchet to the released position.

13. The system of claim 1 , wherein:

the energy-storing hub comprises an engaging portion; and the engaging portion comprises a plurality of mating projections operative to engage with a part of the internal combustion engine.

14. The system of claim 7, wherein the energy storing hub assembly further comprises a common hub, the common hub being selectively engageable with the energy-storing hub.

15. The system of claim 14, wherein:

the energy-storing hub further comprises a set of hub starter dogs; and the common hub comprises a plurality of locking projections, the set of hub starter dogs being operative to selectively engage with the locking projections to transmit motion from the energy-storing hub to the common hub.

16. The system of claim 14, wherein:

the cam gear set and the energy-releasing cam are operative to rotate about the first rotational axis; and

a driveshaft of the electric motor, the reduction gear set and the drive member are operative to rotate about a second rotational axis which is offset from the first rotational axis.

17. The system of claim 14, wherein:

the common hub comprises an engaging portion; and

the engaging portion comprises a plurality of mating projections operative to engage with a part of the internal combustion engine.

8. The system of claim 1 , wherein the system further comprises a manual starter pulley and a pull member, the manual starter pulley being operative to selectively rotate the energy-storing hub assembly responsive to manual movement of the pull member for starting the internal combustion engine.

19. The system of claim 1 , wherein the resilient member is a torsion spring.

20. A device comprising:

an internal combustion engine; and

a starting system according to any of claims 1 - 20, wherein the starting system is operative to start the internal combustion engine..

21 . The device of claim 20, wherein the device is a handheld power tool.