Patent Application
20130019822
The present invention relates generally to the field of small, internal combustion engines, such as those engines that may be used to power outdoor power equipment including, for example, walk-behind lawn mowers, snow throwers, and pressure washers. More specifically, the present invention relates to the engine cover, the recoil starter, and the air cooling system of an engine.
Small, internal combustion engines often include a recoil starter. An operator pulls a rope attached to a wheel coupled to the crankshaft of the engine, to rotate the crankshaft. Rotation of the crankshaft, in turn, initiates combustion processes of the engine by facilitating the movement of air and fuel through the engine and simultaneously producing sparks in the combustion chamber via the ignition system of the engine. Typically the recoil starter further includes an automatic rewind in the form of a torsion spring that recoils the rope after the operator has completed a pull. In some cases, the engine may require several pulls to start. When the engine is running fast enough, the combustion processes automatically drive the crankshaft without assistance from the recoil starter.
During manufacturing of the engine, installation of the recoil starter may take significant time and effort. In some instances, the recoil starter may be manually screwed onto the top of an engine. In such cases, the number and strength of the screws must be strong enough to hold the recoil starter to the top of the engine when the operator is pulling the rope.
One embodiment of the invention relates to an engine, which includes an engine cover, a blower fan, and a recoil starter having a cover. The engine cover includes an inlet aperture and is configured to house working components of the engine. The blower fan is configured to disperse air received through the inlet aperture to cool the working components of the engine. The recoil starter cover has an opening for air to pass through and is fastened to the underside of the engine cover.
Another embodiment of the invention relates to an engine, which includes an engine cover, a recoil starter having a cover, a blower fan, and an air deflector. The engine cover includes an inlet aperture and is configured to house working components of the engine. The recoil starter cover has an opening for air to pass through and is configured to span the inlet aperture of the engine cover. The blower fan is configured to disperse air received through the inlet aperture to cool the working components of the engine. The air deflector is configured to be positioned proximate to the underside of the recoil starter cover and to extend from a rim of the inlet aperture toward the center of the inlet aperture, partially over the inlet aperture. The air deflector helps direct air dispersed by the blower fan toward the working components of the engine.
Yet another embodiment of the invention relates to a method of manufacturing an engine. The method includes fastening a recoil starter to an underside of an engine cover such that the recoil starter spans an inlet aperture of the engine cover. Contact between the underside of the engine cover and the recoil starter provides a load-bearing interface during starting of the engine.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, in which:
Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.
Referring to
The recoil starter assembly 136 includes a cover 138 (e.g., recoil starter cover), a handle 140 connected to a rope 142, and a spool 144 (e.g., wheel, sheave) for the rope 142. The spool 144 is coupled to the crankshaft 116 of the engine 110. To start the engine, an operator pulls the rope 142 to rotate the crankshaft 116 and initiate combustion processes of the engine 110. According to an exemplary embodiment, the recoil starter cover 138 includes openings 146 through which air may pass into the interior 148 of the engine cover 112 to be dispersed by the blower fan 114 to cool the working components of the engine 110.
The recoil starter assembly 136 may be coupled to the crankshaft 116 in a variety of different ways, such as directly, using a ratcheting member, or indirectly via intermediate gearing, with or without a ratcheting member. According to an exemplary embodiment, a ratchet (e.g., including “dogs”) of the rewind extends, engages, and rotates a starter cup when the rewind rope is pulled. The starter cup then communicates the rotation to the crankshaft. When the rope is subsequently released, the rope automatically rewinds and the ratchet retracts and disengages the starter cup. In other embodiments, other connection systems and features may be used, such as a clutch to selectively engage the starter with the crankshaft.
According to an exemplary embodiment, the engine 110 is a small, internal combustion engine designed for outdoor power equipment, such as walk-behind lawn mowers, snow throwers, pressure washers, portable generators, go-carts, rotary tillers, and other such equipment. In some embodiments, the engine 110 is vertically shafted; while in other embodiments, the engine is horizontally shafted. The engine 110 may include one or more cylinders, and may operate on a two- or four-stroke cycle. In contemplated embodiments, the engine 110 may include an electric starter motor with an air intake piece for the blower fan in place of the recoil starter cover 138 shown in
Referring now to
Referring to
According to an exemplary embodiment, the recoil starter cover 210 includes a flange 222 (e.g., lip, extension) projecting outward from a side of the recoil starter cover 210. The flange 222 is sized to be wider than the intake aperture 218, preventing the recoil starter cover 210 from passing fully through the intake aperture 218 when inserted from the underside 220 of the engine cover 216. The flange 222 is then configured to contact a rim 224 of the intake aperture 218. In contemplated embodiments, the contact may be indirect, such as in cases where a gasket, glue, or other intermediate element is positioned between the flange 222 and rim 224, such as to establish an air seal or to fasten the flange 222 and rim 224 together. Contact between the rim 224 and flange 222 provides a load-bearing interface during operation of the recoil starter, which may be stronger or more reliable than interfaces provided by other fastening methods, such as gluing, screwing, clipping, etc. the recoil starter to the top of the engine cover. The load-bearing interface may help to keep the recoil starter cover attached to the engine despite loading caused by operation of the recoil starter. However, in contemplated embodiments, the recoil starter cover may be fastened to the top of the engine cover via other such fastening methods.
Referring to
In some embodiments, the first and second parts 232, 234 of the fastening system 230 include a hook 236 and a receiving surface 238 (e.g., catch, ledge) for the hook 236. The hook 236 may face toward the center of the intake aperture 218, away therefrom, or may be otherwise oriented, where the receiving surface 238 is correspondingly oriented to receive the hook 236. In some embodiments, the receiving surface 238 is the bottom rim of the recoil starter cover 210. In other embodiments, the receiving surface is a hole, a groove, or part of a flange or extension from the side of the recoil starter cover 210. As shown in
According to an exemplary embodiment, the top 240 of the hook 236 includes an inclined surface. As such, movement of the recoil starter cover 210 into the intake aperture 218 of the engine cover 216, during assembly of the engine, provides an orthogonal component to the contact force between the top 240 of the hook 236 and a contacting surface 242. The orthogonal component causes the hook 236 to temporarily deflect (e.g., flex, move out of the way of), allowing the recoil starter cover 210 to pass into a fastened position in the intake aperture 218 of the engine cover 216, as shown in
According to an exemplary embodiment, the hook 236 of the first part 232 of the fastening system 230 is part of the engine cover 216, and the receiving surface 238 of the second part 234 of the fastening system 230 is on the recoil starter cover 210. In other embodiments, positioning of the hook and receiving surface is reversed. In still other embodiments, each of the engine cover and recoil starter cover includes a hook and a receiving surface.
In some embodiments, guide structures, such as pins 226 and corresponding holes 228, may be used with the fastening system 230 to guide the attachment of the recoil starter cover 210 to the engine cover 216. In other embodiments, pins may be used to facilitate heat staking of the recoil starter cover to the engine cover. In still other embodiments, pins or other guide structures are not included (see generally
Referring now to
The air deflector 314 shown in
In some embodiments, the intake aperture 316 is round and the air deflector 314 extends from the rim 318 of the intake aperture 316 toward the center of the intake aperture 316 a distance that is less than half the radius of the intake aperture 316, providing an opening through the center of the intake aperture 316 with sufficient area for air to flow through the intake aperture 316 to the blower fan to cool the engine. However, in some embodiments, the air deflector 314 extends at least an eighth of the radius, such as about a quarter of the radius, from the rim 318 toward the center of the intake aperture 316 in order to sufficiently limit air flow out of the intake aperture 316. In other embodiments, an air deflector extends further than half the radius toward the center or less than an eighth of the radius toward the center.
According to an exemplary embodiment, the air deflector 314 extends around the full periphery of the intake aperture 316. In other embodiments, the air deflector extends only partially around the periphery of the air intake, such as around portions of the periphery corresponding to the rear and lateral sides of the engine. In contemplated embodiments, the air deflector may not be round.
Referring to
In the embodiment shown in
Still referring to
A fastening system 416 may be used for fastening the recoil starter cover 412 to the underside of the engine cover 414 by engaging a hook 418 with a receiving surface 420. The hook 418, in some embodiments, is integrally formed with one of the recoil starter cover 412 and the engine cover 414, while the receiving surface 420 is integrally formed with the other of the recoil starter cover 412 and the engine cover 414.
In some embodiments, the manufacturing method further includes fastening the air deflector 422, as described above, proximate to an underside of the recoil starter cover 412. The air deflector 422 extends from a rim of the inlet aperture toward the center of the inlet aperture, partially over the inlet aperture. Accordingly, the air deflector 422 helps to direct air dispersed by a blower fan of the engine toward working components of the engine.
The construction and arrangements of the engine, as shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention.
