The present disclosure relates to outboard motors and exhaust systems for outboard motors.
Typical four stroke outboard motors have several components that compete for common design space beneath the engine. For example, the exhaust conduit for conveying hot exhaust gas from the engine, the cooling water jacket for cooling exhaust gas in the exhaust conduit, the upper engine mounts, the oil pump, the engine oil sump, and engine oil drain back area all require space just below the internal combustion engine. These components are typically incorporated into a molded engine adapter plate that connects the engine to a housing for the driveshaft. The present inventor has recognized that this competition for design space at the location of the engine adapter plate usually compromises the design of the outboard motor, with added cost, reduced function, reduced performance, or a combination of these factors.
In order to achieve small-sized outboard configurations, typical outboard motors incorporate an engine cylinder block that is rotated so that the engine cylinders are not aligned with a vertical fore-aft central plane extending through the crankshaft. In these configurations, the exhaust conduit for conveying hot exhaust gas from the engine is located apart from the central plane. In fact, even in configurations where the engine cylinder block is not rotated, the exhaust conduit is located apart from the central plane to a certain extent. This off-center exhaust conduit must be routed back into alignment with the central plane at the bottom of the driveshaft housing in order to align with an exit port in the lower unit gear case.
The present inventor has recognized that routing the exhaust conduit back into alignment with the noted central plane undesirably places design constraints on the engine adapter plate, requires a great deal of space, often requires cover plates with screws and gaskets, and can often require sharp, flow-restricting corners in the exhaust conduit. These design constraints also often undesirably require location of the engine mounts at least partially in the exhaust conduit. As the engine adapter plate is utilized to bring the exhaust conduit into alignment with the central plane, the exhaust conduit is often in the way of the engine mounts. Further, placing the exhaust conduit though the center of the oil sump often wastes space and causes the sump to be longer and more expensive to form—in order to obtain a requisite oil volume. The present inventor has found that this is also true in cases where the sump has a “U” shape around the exhaust conduit. Further, U-shaped sumps often undesirably require increased fasteners to maintain a longer sealing flange that accompanies the U-shaped sump.
The present disclosure provides improved outboard motor configurations and exhaust system configurations. In one example, an outboard motor comprises an internal combustion engine, a driveshaft housing and a molded adapter plate connecting the internal combustion engine and the driveshaft housing. An elongated exhaust conduit conveys hot exhaust gas from the internal combustion engine. The exhaust conduit extends from a first end portion located proximate to the internal combustion engine to a second end portion located proximate to the driveshaft housing. The exhaust conduit and adapter plate are separate or segregated components.
In the present description, certain terms have been used for brevity, clearness and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different systems and methods described herein may be used alone or in combination with other systems and methods. 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, sixth paragraph only if the terms “means for” or “step for” are explicitly recited in the respective limitation.
An adapter plate K shown in cross-hatching supports the internal combustion engine B and connects the internal combustion engine B to the drive shaft housing L. The adapter plate K is a molded component that incorporates a section of the exhaust conduit D, a section of cooling water jacket E, the upper engine mounts (not shown), the engine oil sump M and the related oil drain back area. The above-noted competition for design space amongst the related components of the adapter plate K adds cost, reduces function, and reduces performance of the outboard motor A. For example, routing of the exhaust conduit D from its first end portion F to its second end portion H requires a great deal of space, requires cover plates with screws and gaskets, and requires sharp, flow-restricting corners N in the exhaust conduit D. Further, these design constraints undesirably require optimum location of the noted engine mounts to be compromised to avoid interference with the exhaust conduit D. Because the adapter plate K forms part of the exhaust conduit D to return the exhaust conduit D back into line with the central plane G, the conduit D is undesirably placed in the way of the noted engine mounts. Further, placing the exhaust conduit D through the center of the oil sump M wastes space and causes the sump M to be longer in the vertical direction and more expensive to form. This is also true in cases where the sump M has a “U” shape around the exhaust conduit D.
The internal combustion engine 12 extends in a vertical fore-aft central plane 40 (see
As shown in
The molded adapter plate 16 is also formed separate from or segregated from the exhaust conduit 24. In the example shown, the exhaust conduit 24 passes through the adapter plate 16 via an aperture 50 in the adapter plate 16. A pair of O-ring seals 52 seal the cooling water jacket 30 between the exhaust manifold 20 and the casting containing the exhaust conduit 24 (see
Separation or segregation of the exhaust conduit 24 and adapter plate 16, as shown in
Number | Name | Date | Kind |
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3431882 | Irgens | Mar 1969 | A |
4452194 | Watanabe | Jun 1984 | A |
4583953 | Nakase | Apr 1986 | A |
6250982 | Kashima | Jun 2001 | B1 |
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Photograph of a 2004 Yamaha 150 Hp Adapter. |
Photograph of a 2005 Suzuki 175 Hp Adapter. |
Photographs of a 2005 Suzuki 175 Hp Midsection. |
Photograph of a 2005 Suzuki 175 Hp Midsection. |
Photograph of a 2006 Yamaha 60 DSH and Oil Sump. |
Photograph of a 2005 Yamaha 90 Hp Adapter. |
Drawing of a 2005 Yamaha 90 Hp Midsection. |