The present invention relates to a primary drive housing assembly for a motorcycle engine. In a motorcycle engine in which the engine assembly is separate from the transmission assembly, a primary drive assembly is utilized to transfer rotary output from the engine crankshaft to an input shaft of the transmission assembly. The primary drive assembly can include a number of suitable power transmission elements including gearing arrangements, belt and pulley systems, and chain and sprocket systems. In addition to the power transmission elements of the primary drive assembly, many primary drive assemblies include housings that protect and/or support the power transmission elements. The housings may also function to contain oil or other fluids for lubrication of the power transmission elements.
In some instances the primary housing may comprise a relatively large and exposed portion of the motorcycle engine. As such, the aesthetic appearance of the housing may be of some concern. Furthermore, dynamic excitation forces, such as those generated during engine operation, may result in resonance of the primary housing. Such resonance can contribute to undesirable noise during vehicle operation.
The invention provides an internal combustion engine including a crankshaft that defines a crankshaft axis, and a crankcase supporting the crankshaft for rotation about the crankshaft axis. The crankcase defines a first surface that extends around and is substantially normal to the crankshaft axis, and a plurality of threaded bores that extend through the first surface and are angularly spaced about the crankshaft axis. The engine also includes a transmission having an input shaft defining an input axis that is substantially parallel to the crankshaft axis. A primary housing defines a crankshaft opening through which the crankshaft extends, an input shaft opening through which the input shaft extends, and a second surface that faces the first surface. The primary housing is configured to house a primary drive assembly that drivingly couples the crankshaft and the input shaft. The primary housing includes an inner housing that defines the second surface, and an outer housing that is coupled to the inner housing. The inner housing and the outer housing define a plurality of coupling apertures substantially aligned with some of the threaded bores in the crankcase. Fasteners extend through the external coupling apertures and into the threaded bores to couple the outer housing to the inner housing and to couple the inner housing to the crankcase.
In another aspect, the present invention provides an internal combustion engine including an engine component that is adapted to be coupled to the internal combustion engine and having a wall portion. A damping mass is provided to be coupled to the wall portion. When the damping mass is not coupled to the wall portion, the wall portion resonates at a resonant frequency during engine operation and emits a noise caused by resonation at the resonant frequency. Without the damping mass, the wall portion includes an anti-node region that exhibits a maximum resonant amplitude when the wall portion resonates at the resonant frequency. When the damping mass is coupled to the wall portion at the anti-node region, the resonant frequency of the wall portion is reduced. Reduction of the resonant frequency of the wall portion by coupling the damping mass to the wall portion reduces the radiation efficiency and the noise emissions of the wall portion during engine operation.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
a is a section view taken along line 5-5 of
b is a section view similar to
c is a section view similar to
d is a section view similar to
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
The engine assembly 14 also includes a transmission assembly 58 that is coupled to the crankcase 38. The transmission assembly 58 includes a transmission case 62 that rotatably supports a transmission input shaft 66 for rotation about an input axis 70. The input axis 70 extends substantially parallel to the crankshaft axis 46.
A primary housing assembly 74 includes an inner housing 78 and an outer housing 82 coupled to the inner housing 78. The primary housing assembly 74 houses a primary drive assembly 86 that drivingly couples the crankshaft 42 to the input shaft 66. The illustrated primary drive assembly 86 includes sprockets 90 and a chain 94, however other drive systems incorporating belts and pulleys or gearing arrangements can be used instead.
The inner housing 78 includes an elongated inner housing wall 98 that defines a crankshaft opening 102 that receives the crankshaft 42 and an input shaft opening 106 that receives the input shaft 66. A generally cylindrical wall 110 extends away from the inner housing wall 98 toward the crankcase 38 at a forward end of the inner housing 78. The cylindrical wall 110 defines a second surface 114 that faces and is substantially parallel to the first surface 50 when the inner housing 78 is coupled to the crankcase 38. An outer wall 118 extends away from the inner housing wall 98 in a direction opposite that of the cylindrical wall 110. The outer wall 118 substantially defines an outer perimeter of the inner housing 78 and further defines a first sealing surface 122 that faces away from the crankcase 38.
The cylindrical wall 110 and the outer wall 118 cooperate to define a plurality of external coupling apertures 126 that extend through the first sealing surface 122 and the second surface 114 substantially parallel to the crankshaft axis 46, and which are angularly spaced about the crankshaft axis 46. The inner housing wall 98 and the cylindrical wall 110 cooperate to define a plurality of internal coupling apertures 130. The internal coupling apertures 130 extend through the housing wall 98 and through the second surface 114 substantially parallel to the crankshaft axis 46. The inner housing wall 98 also defines a plurality of transmission coupling apertures 132 near the rearward portion of the inner housing 78 that extend substantially parallel to the crankshaft axis 46. The outer wall 114 defines a plurality of blind bores 134 spaced generally about the rear periphery of the inner housing 78 that extend substantially parallel to the crankshaft axis 46.
The outer housing 82 includes a forward portion 138 and an enlarged rearward portion 142. The forward portion 138 includes an arcuate forward edge 146 that is substantially coaxially aligned with the crankshaft axis 46. The rearward portion 142 defines a circular opening 150 that is substantially coaxially aligned with the input axis 70. A removable clutch cover 152 can be coupled to the opening to afford access to the clutch portion of the primary drive assembly 86 without requiring removal of the outer housing 82.
The outer housing 82 includes an outer perimeter that substantially corresponds to the outer perimeter of the inner housing 78 as defined by the outer wall 114. The outer housing 82 defines a second sealing surface 154 that faces the first sealing surface 122 and is a substantial mirror-image thereof. In the vicinity of the outer perimeter, the outer housing 82 defines a plurality of coupling apertures 158 that extend through the second sealing surface 154. Some of the coupling apertures 158 are defined in protrusions 162 which extend generally outwardly from the outer housing 82, while other coupling apertures 158 are defined in recessed or countersunk portions 166 of the outer housing 82. Each coupling aperture 158 is positioned and configured for alignment with a corresponding one of either the external coupling apertures 126 or the blind bores 134.
The primary housing assembly 74 also includes an outer primary gasket 170 including apertures 174. The outer primary gasket 170 is sandwiched between the first and second sealing surfaces 122, 154 to seal the interface between the inner housing 78 and the outer housing 82. The apertures 174 are positioned along the outer primary gasket 170 for alignment with the external coupling apertures 126 and the blind bores 134 of the inner housing 78. The primary housing assembly 74 also includes an inner primary gasket 176 that is sandwiched between the first surface 50 of the crankcase 38 and the second surface 114 of the inner housing 78. The inner primary gasket 176 surrounds the crankshaft 42 and includes a substantially planar rigid portion 178 and a resilient portion 180 that is coupled to the rigid portion 178. The rigid portion 178 defines a plurality of gasket apertures 182 that can be aligned with the threaded bores 54 of the crankcase 38, and includes a generally circular inner edge. The resilient portion 180 extends circumferentially around the inner edge of the rigid portion 178 and, as seen in
The primary housing assembly 74 is coupled to the crankcase 38 and the transmission case 62 in the following manner. The inner housing 78 is coupled to the crankcase 38 by extending inner fasteners 186 through the internal coupling apertures 130 and into the threaded bores 54 in the crankcase 38. The inner fasteners 186 also extend through the gasket apertures 182 defined by the inner primary gasket 176. The inner housing 78 is also coupled to the transmission case 62 by extending inner fasteners 186 through the transmission coupling apertures 132 and into the transmission case 62. When the inner housing 78 is coupled to the crankcase 38 and to the transmission case 62 the crankshaft 42 extends through the crankshaft opening 102 and the input shaft 66 extends through the input shaft opening 106. The primary drive assembly 86 can then be coupled to the crankshaft 42 and the input shaft 66.
The outer housing 82 is then coupled to the inner housing 78 by extending a first set of outer fasteners 194 through the coupling apertures 158 that are adjacent the arcuate forward edge 146 of the outer housing 82. Each fastener 194 of the first set of fasteners extends through the coupling aperture 158, through an aperture 174 in the outer primary gasket 170, through an external coupling aperture 126 of the inner housing 78, through a gasket aperture 182 in the inner primary gasket 176, and into a threaded bore 54 in the crankcase 38. The fasteners 194 therefore couple the outer housing 82 to the inner housing 78, and also couple the inner and outer housings 78, 82 to the crankcase 38. A second set of outer fasteners 198 extend through the remaining coupling apertures 158 of the outer housing 82, through the apertures 174 in the outer primary gasket 170, and into the blind bores 134 of the inner housing 78.
With reference also to
a illustrates a first embodiment of the resonant damping device 200a where the damping mass 204a is rigidly coupled to the outer housing 82. The outer housing 82 defines a boss 208 that defines a threaded bore 212. The boss 208 is appropriately located within the anti-node region of the outer housing 82. The damping mass 204a is in the form of a hollow-cylinder, and is rigidly coupled to the boss 208 by a fastener 216. The rigidly-mounted damping mass 204a can take on many different shapes or forms, and can be coupled to the inner wall in a variety of different ways which may include one or more fasteners or clamps. The damping mass 204a can also be permanently coupled to the outer housing 82 by welding, adhesives or the like, or the damping mass 204 could be integrally formed (e.g. by casting) with outer housing 82. By positioning the damping mass 204a in the anti-node region of the outer housing 82, the resonant frequency of the outer housing 82 is reduced, which in turn reduces the radiation efficiency and noise emission of the outer housing 82 during engine operation.
b illustrates a second embodiment of the resonant damping device 200b where the damping mass 204b is moveably coupled to the outer housing 82. In the illustrated construction, the outer housing 82 defines a boss 220 including a threaded bore 224. A fastener 228 including a shaft portion 232 and a head portion 236 is received by the threaded bore and extends away from the boss 220. The damping mass 204b is in the form of a hollow cylinder and includes a length L. The damping mass 204b is supported for sliding movement along the shaft portion 232 between the boss 220 and the fastener head portion 236, the boss 220 and the head portion 236 being separated by a distance greater than the length L. Because the resonant damping device 200b is located within the primary housing assembly 58 (see
c illustrates a third embodiment of the resonant damping device 200c. The damping device 200c operates in a manner similar to that of the damping device 200b of
d illustrates a fourth embodiment of the resonant damping device 200d. The resonant damping device 200d operates in substantially the same manner as the device 200c of
Various features and advantages of the invention are set forth in the following claims.
This application is a divisional of application Ser. No. 11/174,427 filed Jul. 1, 2005 now U.S. Pat. No. 7,174,875, the entire contents of which is incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
4030553 | Rockwell | Jun 1977 | A |
4516658 | Scarton et al. | May 1985 | A |
6834741 | Miller et al. | Dec 2004 | B2 |
Number | Date | Country |
---|---|---|
56159520 | Dec 1981 | JP |
Number | Date | Country | |
---|---|---|---|
20070056550 A1 | Mar 2007 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 11174427 | Jul 2005 | US |
Child | 11550550 | US |