The present disclosure relates to internal combustion engines for marine engines, and particularly to cam phaser arrangements for outboard motors and marine engines for outboard motors.
Cam phasers are known in the art for increasing efficiency and improving idle stability of internal combustion engines. Examples of cam phasers for internal combustion engines are disclosed in the following U.S. Patents, which are incorporated herein by reference: U.S. Pat. Nos. 5,107,804; 5,327,859; 5,447,126; 5,588,404; 5,680,836; 5,680,837; 5,813,378; 6,129,060; 6,176,210; 6,247,434; 6,276,321; 6,405,696; 6,412,462; 6,691,656; 6,742,485; 6,843,214; 6,915,775; 6,997,150; 7,755,077; 7,647,904; 7,789,054; 8,453,616; 8,584,636.
This Summary is provided to introduce a selection of concepts that are further described herein below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In certain examples, marine engines comprise a bank of piston-cylinders; an intake camshaft that operates intake valves for controlling inflow of air to the bank of piston-cylinders; an exhaust camshaft that operates exhaust valves for controlling outflow of exhaust gas from the bank of piston-cylinders; and a cam phaser disposed on one of the intake camshaft and exhaust camshaft. The cam phaser is operably connected to and adjusts a timing of operation of the other of the intake camshaft and exhaust camshaft with respect to the one of the intake camshaft and exhaust camshaft.
In certain examples, outboard motors and marine engines for outboard motors comprise first and second banks of piston-cylinders that are aligned with respect to a longitudinal axis and extend transversely to each other in a V-shape so as to define a valley therebetween. A crankshaft extends along the longitudinal axis. Combustion in the first and second banks of piston-cylinders causes rotation of the crankshaft. A dual overhead cam arrangement is provided for each of the first and second banks of piston-cylinders. Each dual overhead cam arrangement is connected to the crankshaft and controls flow of intake air and exhaust gas to and from a respective one of the first and second banks of piston-cylinders upon rotation of the crankshaft. Each dual overhead cam arrangement comprises an exhaust camshaft and an intake camshaft. The crankshaft is coupled to one of the exhaust camshaft and intake camshaft such that rotation of the crankshaft causes rotation of the one of the exhaust camshaft and intake camshaft. A cam phaser is disposed on the one of the intake camshaft and exhaust camshaft. The cam phaser is connected to the other of the intake camshaft and exhaust camshaft so as to adjust a timing of rotation of the other of intake camshaft and the exhaust camshaft with respect to the one of the intake camshaft and exhaust camshaft.
Examples of outboard motors and internal combustion engines for outboard motors are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components.
In the present description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different systems and apparatuses described herein may be used alone or in combination with other systems and methods. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims. Each limitation in the appended claims is intended to invoke interpretation under 35 U.S.C. §112(f), only if the terms “means for” or “step for” are explicitly recited in the respective limitation.
Returning to
Combustion in the first and second banks of piston-cylinders 12, 14 causes rotation of the crankshaft 20 (arrows A), which in turn causes rotation of the respective exhaust camshafts 26 (arrows B). The crankshaft 20 is operatively connected to the exhaust camshafts 26 via a flexible connector, which in this example is a chain 38. The type of connector can vary and in certain examples can include a belt and/or the like. The chain 38 is driven into movement by a drive sprocket 40, which is disposed on the crankshaft 20 and engaged with the chain 38. Movement of the chain 38 engages with sprockets 42 on the respective exhaust camshafts 26, thereby causing rotation of the exhaust camshafts 26 (arrows B) about their own axes. An idler sprocket 46 is located at a center of the valley 18. The idler sprocket 46 is engaged with and driven into rotation about its own axis (arrows E) by movement of the chain 38. The idler sprocket 46 supports movement of the chain 38. Movement of the chain is also supported by conventional chain guides 41.
As shown in
In the example of the cam phaser 48 shown in
Referring to
In this example, the cam phaser 48 is disposed on the lower end 50 of the respective exhaust camshafts 26. The present inventors have found that by locating the cam phaser 48 on the lower end 50 of the respective exhaust camshafts 26, closer to the valley 18 than the respective intake camshafts 28, it is possible to provide phasing to the intake camshaft 28 and yet save critical design space on the outboard motor. For example, dual large outboard motors that are mounted on boats typically have a requirement to meet 26 inch centers. This restricts the allowable width of each outboard motor. Conventional cam phasing concepts otherwise add to the width of the outboard motor and in some cases make the outboard motor too wide to fit on the 26 inch centers. The arrangements in the present disclosure overcome these drawbacks. By placing the cam phaser 48 on the exhaust cam shaft 26, the cam phaser 48 does not contribute to the overall width of the outboard motor 11. The exhaust cam shaft 26 favorably provides a bearing surface for the rotor portion 54 of the cam phaser 48, thus phasing the intake cam shaft 28 but not the exhaust cam shaft 26.
The present application relates to and claims priority of U.S. Provisional Patent Application Ser. No. 61/782,829, filed Mar. 14, 2013, which is incorporated herein by reference in entirety.
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Number | Date | Country | |
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61782829 | Mar 2013 | US |