OUTBOARD ENGINE ASSEMBLY HAVING AN IDLE RELIEF SYSTEM

Abstract

An outboard engine assembly has an engine unit including an engine unit housing, an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber, a gearcase connected to the engine unit housing, and an exhaust system, the exhaust system including an idle relief passage fluidly communicating with an exhaust passage, the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the outboard engine assembly is mounted to a watercraft and the watercraft is at rest, and a propulsion device operatively connected to the engine.

Claims

1. An outboard engine assembly for a watercraft, comprising: an engine unit including: an engine unit housing; an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber; a gearcase connected to the engine unit housing; and an exhaust system including: an exhaust passage fluidly communicating with the at least one combustion chamber, the exhaust passage having an exhaust outlet, the exhaust passage extending through the gearcase, the exhaust passage being configured for supplying exhaust gases from the at least one combustion chamber to an exterior of the gearcase via the exhaust outlet; and an idle relief passage fluidly communicating with the exhaust passage, the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the outboard engine assembly is mounted to a watercraft and the watercraft is at rest; and a propulsion device operatively connected to the engine.

2. The outboard engine assembly of claim 1, wherein the idle relief outlet is disposed vertically higher than the gearcase.

3. The outboard engine assembly of claim 1, further comprising an anti-ventilation plate connected to the gearcase; and wherein the idle relief outlet is vertically higher than the anti-ventilation plate.

4. The outboard engine assembly of claim 1, wherein the idle relief outlet is disposed on a front side of the engine unit housing.

5. The outboard engine assembly of claim 1, wherein: the engine unit further includes: a driveshaft operatively connected to and driven by the internal combustion engine; and the propulsion device includes: a propeller shaft disposed at least in part in the gearcase, the propeller shaft being operatively connected to and driven by the driveshaft; and a propeller operatively connected to and driven by the propeller shaft.

6. The outboard engine assembly of claim 5, wherein: the internal combustion engine further comprises a crankshaft operatively connected to the driveshaft for driving the driveshaft, the crankshaft defining a crankshaft axis; and the idle relief outlet is disposed between the crankshaft axis and an axis of the propeller shaft.

7. The outboard engine assembly of claim 1, further comprising a lower motor mount; and wherein the idle relief outlet is aligned with the lower motor mount.

8. The outboard engine assembly claim 1, wherein: the internal combustion engine comprises an engine block; and the idle relief outlet is disposed between an upper side and a lower side of the engine block.

9. The outboard engine of claim 1, wherein the idle relief outlet is disposed between 6 inches to 8 inches below the waterline.

10. The outboard engine assembly of claim 1, wherein: the idle relief passage includes an inlet; the exhaust passage is a high-rise exhaust passage having an apex; and the inlet of the idle relief passage is positioned downstream from the apex of the high-rise exhaust passage.

11. The outboard engine assembly of claim 1, wherein: the idle relief passage further comprises a tube disposed outside the engine housing; and the tube defines the idle relief outlet and is sized such that the idle relief outlet is below the waterline.

12. The outboard engine assembly of claim 1, further comprising: a transom bracket; wherein the propulsion device further comprises a driveshaft operatively connected to and driven by the internal combustion engine; and the idle relief outlet is disposed below the transom bracket when an axis of the driveshaft is vertical.

13. A watercraft comprising: a watercraft body; and an outboard engine assembly pivotably connected to the watercraft body, the outboard engine comprising: an engine unit including: an engine unit housing; an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber; a gearcase connected to the engine unit housing; and an exhaust system including: an exhaust passage fluidly communicating with at least one combustion chamber, the exhaust passage having an exhaust outlet, the exhaust passage extending through the gearcase, the exhaust passage being configured for supplying exhaust gases from the at least one combustion chamber to an exterior of the gearcase via the exhaust outlet; and an idle relief passage fluidly communicating with the exhaust passage, the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the watercraft is at rest; and a propulsion device operably connected to the engine.

14. The watercraft of claim 13, wherein: the watercraft body comprises a rear platform; and the outboard engine assembly is connected below the rear platform.

15. The watercraft of claim 14, wherein the idle relief outlet is disposed below the platform.

16. The watercraft of claim 13, wherein the outboard engine assembly further comprises: a transom bracket having a watercraft portion connected to the watercraft body; and the idle relief outlet is disposed longitudinally between the watercraft portion of the transom bracket and the watercraft body.

17. The watercraft of claim 13, wherein: the idle relief passage further comprises a tube disposed outside the engine housing; and the tube defines the idle relief outlet and is sized such that the idle relief outlet is below the waterline.

18. The watercraft of claim 13, wherein: the internal combustion engine includes a crankshaft; the engine unit includes a driveshaft operatively connected to and driven by the crankshaft; the propulsion device includes: a propeller shaft disposed at least in part in the gearcase, the propeller shaft being operatively connected to and driven by the driveshaft; and a propeller operatively connected to and driven by the propeller shaft; and the idle relief outlet is disposed between an axis of the crankshaft and an axis of the propeller shaft.

19. The watercraft of claim 13, wherein: the internal combustion engine comprises an engine block; and the idle relief outlet is disposed between an upper side and a lower side of the engine block.

20. The watercraft of claim 13, wherein: the outboard engine assembly further comprises an anti-ventilation plate connected to the gearcase; and the idle relief outlet is vertically higher than the anti-ventilation plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a better understanding of the present technology, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

[0034] FIG. 1 is a right side elevation view of a watercraft having an outboard engine assembly according to the present technology;

[0035] FIG. 2 is left side elevation view of the outboard engine assembly of the watercraft of FIG. 1;

[0036] FIG. 3 is a left side elevation view of the outboard engine assembly of FIG. 2, with a cowling of the engine unit housing removed;

[0037] FIG. 4 is a perspective view, taken from a rear, right side of a vertical cross-section of an engine, an exhaust system and other components of the outboard engine assembly of FIG. 3, the vertical cross-section being taken laterally through a center of a middle cylinder of the engine;

[0038] FIG. 5 is a perspective view taken from a top, front, left side of the outboard engine assembly of FIG. 2;

[0039] FIG. 6 is a perspective view taken from a top, rear, left side of a vertical cross-section of the outboard engine assembly of FIG. 2, taken through line 6-6 of FIG. 2;

[0040] FIG. 7 a perspective view taken from a top, rear, left side of the outboard engine assembly of FIG. 3, with the engine and cowling removed;

[0041] FIG. 8 is a cross-section of the outboard engine assembly of FIG. 2, taken through line 6-6 of FIG. 2;

[0042] FIG. 9 is a rear vertical cross-section of a portion of an exhaust system of the outboard engine assembly of FIG. 2, taken through line 6-6 of FIG. 2;

[0043] FIG. 10 is a cross-section of FIG. 7 taken through a vertical and longitudinal plane of the outboard engine assembly of FIG. 2; and

[0044] FIG. 11 is a left side elevation view of a cross-section of an alternative embodiment of the outboard engine assembly of FIG. 2, with a cowling of the engine unit housing and an engine removed.

DETAILED DESCRIPTION

[0045] The present disclosure 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 drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of including, comprising, or having, containing, involving and variations thereof herein, is meant to encompass the items listed thereafter as well as, optionally, additional items. In the following description, the same numerical references refer to similar elements.

[0046] In FIG. 1, a watercraft 10 is illustrated. The watercraft 10 is specifically a pontoon boat 10, but this is simply one non-limiting example of a watercraft according to the present technology. This particular embodiment of the boat 10 includes a watercraft body 12 formed generally from two pontoons 14 (only one being illustrated) and a platform 16.

[0047] The boat 10 also includes an outboard engine assembly 100, also referred to herein as the assembly 100. The assembly 100 is pivotably and rotatably connected to the watercraft body 12 for providing propulsion via a propulsion device 102. The propulsion device 102 is specifically a propeller 102 driven by a propeller shaft 170 which rotates the propeller 102 about a propeller shaft axis 170a (FIGS. 3 and 11) in the present embodiment, but it is contemplated that the propulsion device 102 could be different in some embodiments.

[0048] The assembly 100 includes a transom bracket 104 which fastens the assembly 100 to the watercraft body 12. In a particular embodiment, the transom bracket 104 is connected to a lower portion of the platform 16 such that the assembly 100 is disposed below a deck 18 of the watercraft body 12 and, more specifically, below a rear platform 20 of the watercraft body 12, laterally between the pontoons 14. The rear platform 20 extends laterally across the width of the boat 10 and is structured to support the weight of one or more occupants. In some embodiments, the rear platform 20 is vertically offset from the deck 18 such that a top surface of the rear platform 20 is vertically above a top surface of the deck 18. It is contemplated, that in an alternative embodiment, the top surface of the rear platform 20 and the top surface of the deck 18 may be at the same level or the top surface of the deck 18 may be vertically above the top surface of the rear platform 20.

[0049] With reference now to FIGS. 2 and 3, the outboard engine assembly 100, shown separately from the boat 10, will now be described in further detail. The assembly 100 includes an engine unit 106, and a lower unit 108, and the transom bracket 104.

[0050] The engine unit 106 includes an engine unit housing 110 for supporting and covering components disposed therein. The housing 110 is sealed such that water in which the engine unit housing 110 is immersed is impeded from entering the engine unit housing 110 during normal operating conditions including when at rest and components of the engine inside the housing 110 are water-proofed to the same degree as in a conventional outboard engine. Depending on the specific embodiment of the housing 110 and methods used to produce a generally water-tight seal, the housing 110 could be waterproof to varying degrees. It is contemplated that the housing 110 could receive different treatments to seal the housing 110 depending on the specific application for which the marine engine assembly 100 is going to be used. In the present embodiment, the housing 110 includes a cowling 112. The cowling is fastened to the rest of the housing 110 along a diagonally extending parting line 114. A seal (not shown) is provided between the cowling 112 and the rest of the housing 110 along the parting line 114.

[0051] With reference to FIGS. 3 and 4, the engine unit 106 includes an internal combustion engine 116 disposed in the engine unit housing 110 for powering the assembly 100 and driving the propeller 102. By removing the cowling 112, the engine 116 can be accessed. In certain embodiments, the internal combustion engine 116 is a three-cylinder, two-stroke, gasoline-powered, direct injected internal combustion engine. It is contemplated that the internal combustion engine 116 could be another type of internal combustion engine, such as a four-stroke internal combustion engine. It is contemplated that the engine 116 could have more or less than three cylinders. In alternative embodiments, the internal combustion engine 116 could use a fuel other than gasoline, such as diesel.

[0052] The engine 116 includes a crankcase 118. A cylinder block 120 defining three cylinders 122 (FIG. 4) is disposed above the crankcase 118. A cylinder head 124 is disposed on top of the cylinder block 120. Each cylinder 122 has a piston 126 reciprocally received inside of it. Each piston 126 is connected by a corresponding connecting rod 128 to a crankshaft 130. The crankshaft 130 rotates in the crankcase 118 about a crankshaft axis 130a (as seen in FIG. 3). For each cylinder 122 the piston 126, the cylinder 122 and the cylinder head 124 define together a combustion chamber 132. For each combustion chamber 132, a fuel injector 134 supported by the cylinder head 124 is provided to inject fuel directly into the combustion chamber 132, and a spark plug 136 extends into the combustion chamber 132 through the cylinder head 124 to ignite an air-fuel mixture inside the combustion chamber 132.

[0053] The engine 116 includes one air intake 138 per cylinder 122. The air intakes 138 are provided at the bottom of the crankcase 118. Air is delivered to the air intakes 138 by an air intake assembly (not shown). The air passes through reed valves 142 provided in the crankcase 118 adjacent the air intakes 138. The reed valves 142 allow air to enter the crankcase 118 but help prevent air from exiting the crankcase 118. For each cylinder 122, a transfer port 144 communicates the crankcase 118 with the corresponding combustion chamber 132 for air to be supplied to the combustion chamber 132.

[0054] As depicted in FIG. 4, each combustion chamber 132 has a corresponding exhaust port 146. Exhaust gases flow from the combustion chambers 132, through the exhaust ports 146, into an exhaust manifold 148. Each exhaust port 146 has a corresponding reciprocating exhaust valve 150 that varies the effective cross-sectional area and timing of its exhaust port 146. From the exhaust manifold 148, the exhaust gases are routed out of the outboard engine assembly 100 via the other portions of an exhaust system 152, described in more detail below.

[0055] The transom bracket 104 includes a watercraft portion 154 which is adapted for fastening to the watercraft body 12. The bracket 104 also includes an engine portion 156, pivotally connected to the watercraft portion 154, and which is fastened to the engine unit housing 110. As depicted in FIG. 5, the engine portion 156 includes an upper portion 153 which is fastened to an upper mount 155 of the engine unit housing 110, and a lower portion 157 which is fastened to a lower mount 159 of the engine unit housing 110. The engine portion 156 is pivotable with respect to the watercraft portion 154 about a tilt-trim axis 158. The transom bracket 104 thus defines the tilt-trim axis 158 of the outboard engine assembly 100, about which the assembly 100 can be trimmed or tilted relative to the watercraft body 12. The engine portion 156 of the transom bracket 104 includes a tilt/trim actuator 151 for tilting or trimming the assembly 100 relative to watercraft body 12. In the illustrated embodiment, the tilt/trim actuator is a linear hydraulic actuator adapted for pushing the engine portion 156 away from the watercraft portion 154, but other types of tilt/trim actuators 160 are contemplated. The engine portion 156 includes steering actuator 162 configured for steering the engine unit 106 and the lower unit 108 relative to the transom bracket 104 about a steering axis 162a (FIGS. 2 and 11). In the present embodiment, the steering actuator 162 is a rotary hydraulic actuator, but other types of steering actuators 162 are contemplated.

[0056] As the assembly 100 is designed to be disposed below the deck 18, more specifically the rear platform 20, the engine 116 and the transom bracket 104 partially vertically overlap, rather than the engine 116 being disposed well above the bracket 104 as would be the case in a conventional outboard engine assembly meant to extend higher relative to the watercraft body 12.

[0057] With reference to FIGS. 6 to 8, the lower unit 108 will now be described. The lower unit 108 includes a gearcase 164 fastened to the engine unit housing 110. The lower portion 108 includes an anti-ventilation plate 166 extending from the gearcase 164. The anti-ventilation plate 166 extends rearward above the propeller 102, creating a barrier of higher water pressure, to prevent surface air or exhaust gases from being drawn into the propeller 102.

[0058] The lower unit 108 further includes a driveshaft 168, a transmission (not shown), a propeller shaft 170, and the propeller 102. Reciprocation of the pistons 126 drive an output shaft 172 which drives the driveshaft 168 about a driveshaft axis 168a. In certain embodiments, the driveshaft 168 is driven by the output shaft 172 via bevel gears 173. The driveshaft 168 drives the transmission which, in turn, selectively drives the propeller shaft 170 connected to the propeller 102, about a propeller shaft axis 170a.

[0059] An exhaust passage 174 receives exhaust gas from the engine 116. The exhaust passage 174 extends into the gearcase 164. The exhaust passage 174 is fluidly connected to a main exhaust outlet 176. In certain embodiments, the main exhaust outlet 176 is disposed proximate to the propeller 102. Under running speed conditions, exhaust gas leaves the outboard engine assembly 100 through the center of the propeller 102 under water, into the low-pressure region immediately behind the propeller 102.

[0060] Referencing FIGS. 4 and 6 to 11, the exhaust system 152 will now be described in further detail. As previously described, each combustion chamber 132 has an exhaust port 146. Exhaust gases from the combustion chambers 132 flow through the exhaust ports 146 and into the exhaust manifold 148. From the manifold 148 exhaust gases flow into a manifold outlet 178 (FIG. 7) and into the exhaust passage 174. In certain embodiments, the exhaust passage 174 is defined by an inner housing 180 of the engine unit housing 110. The exhaust passage 174 is located in front of the engine 116. The exhaust passage 174 extends forwards and upward, then curves and extends downward and rearward, thus forming a gooseneck having an apex 182. The exhaust passage 174 is thus referred to as a high rise exhaust passage. Exhaust gas flows in the exhaust passage 174 in the direction indicated by arrow 186 (FIGS. 8 and 9). The inner portion 184 of the apex 182 is vertically higher than the top of the combustion chambers 132 when the outboard engine assembly 100 is in the trim range to help prevent intrusion of water into the combustion chambers 132 from the exhaust system 152. From the exhaust passage 174, the exhaust gas flows downward and under the output shaft 172 to be expelled from the main exhaust outlet 176 when the outboard engine is under running speeds.

[0061] During idle or low speeds, exhaust gas pressure is too low to keep water out of the lower portion of the exhaust system 152. As a result, water can flow into the passages and channels through the main exhaust outlet 176 and rise to or close to the same level as the water outside of the outboard engine assembly 100 (i.e., the waterline 22). The exhaust system 152 includes an idle relief system to allow exhaust gases to flow out of the outboard engine assembly 100 when the passage of exhaust gas via the exhaust outlet 176 is blocked by water. The idle relief system includes an idle relief inlet 190, an idle relief passage 192, and an idle relief outlet 194.

[0062] With continued reference to FIGS. 6 to 11, the idle relief system will now be described in more detail. Exhaust gases flow from the idle relief inlet 190, travel through the idle relief passage 192, exiting via the idle relief outlet 194. The idle relief inlet 190 is in fluid communication with the exhaust passage 174. During idle or low speeds, the idle relief inlet 190 is above the waterline 22. In the present embodiment, the idle relief inlet 190 branches off the exhaust passage 174 at a location downstream from the apex 182, preventing water from bypassing the high-rise passage 174 and entering the engine 116 which would impact its proper functioning.

[0063] From the inlet 190, the idle relief passage 192 extends through the engine unit housing 110. The flow of exhaust gas through the idle relief system is indicated by dotted line 196 as depicted in FIGS. 8 to 10. In the present embodiment, exhaust gases flow into the idle relief passage 192 and move leftward through a passage 200 before moving upwards along a passage 202. The exhaust gas then flows rearwardly before descending along a passage 204 (as seen in FIG. 10) where the gas then moves forwardly through a passage 206 before exiting through the outlet 194. In an alternative embodiment, it is contemplated that the idle relief passage 192 may assume a non-tortuous configuration, simply branching off the main exhaust passage 174, extending outwards towards the engine housing 110. In a further alternative embodiment, it is contemplated that an idle relief muffler (not shown) may be included in the idle relief system.

[0064] Referring to FIGS. 2, 3, 5, and 11, the positioning of the idle relief outlet 194 relative to the outboard engine assembly 100 will now be described in further detail. The idle relief outlet 194 is positioned along outside of the engine unit housing 110 such that the occurrence of exhaust gas being conveyed onto the rear platform 20, which results in an undesirable and unpleasant smell for the occupants, is reduced or eliminated. The idle relief outlet 194 is disposed vertically lower than the waterline 22 (FIG. 2), that is the level reached by the water on the outside of the watercraft 10 when the outboard engine assembly 100 is at rest or running at low speeds. Exhaust gases are expelled from the idle relief outlet 194 just below the waterline 22. At this depth, the water pressure is not high enough to block exhaust gases from exiting the idle relief outlet 194. When the exhaust gas is released, it moves upwards towards the water surface which results in the gas being cooled, becoming heavier, and preventing some or all components of the gas from rising above the outboard engine assembly 100 and above the rear platform 20. However, the idle relief outlet 194 should not be positioned too far below the water surface as to impact the proper function of the outboard engine assembly 100. The idle relief outlet 194 is positioned on the outside of the engine unit housing 110. The idle relief outlet 194 is disposed below the axis 130a defined by the crankshaft 130 (FIG. 3). The idle relief outlet 194 is disposed below the transom bracket 104 (FIGS. 2 and 3). The idle relief outlet 194 is disposed above the gearcase 164 (FIG. 2). The idle relief outlet 194 is disposed above the anti-ventilation plate 166 (FIG. 2). The idle relief outlet 194 is aligned with the lower mount 159 (FIG. 2). The idle relief outlet 194 is disposed in between an upper surface 119 and a lower surface 121 of the cylinder block 120 (FIG. 3). In the present embodiment, the idle relief outlet 194 expels exhaust gases between 6 to 8 inches below the waterline 22. As the watercraft 10 increases speed and is lifted to be on plane, the idle relief outlet 194 is above the waterline 22. It is contemplated that, in other embodiments, the idle relief outlet 194 may have a different position relative to at least some of the components listed above.

[0065] In the present embodiment, the idle relief outlet 194 faces downwards, away from the waterline 22. However, it is contemplated that the outlet 194 may be oriented in a different direction, for example facing laterally, in a direction substantially parallel with the waterline 22. The idle relief outlet 194 is disposed on the front side of the engine unit housing 110, closer to the transom bracket 104 and further from the rear edge of the rear platform 20 and the occupants (as seen in FIG. 5). In certain embodiments, the outlet 194 is longitudinally between the watercraft portion 154 of the transom bracket 104 and the watercraft body 12. It is contemplated that the idle relief outlet 194 may be disposed on the rear side of the engine unit housing 110. The idle relief outlet 194 is disposed on the left side of the engine unit housing 110. However, it is contemplated the idle relief outlet 194 may be disposed on the right side of the engine unit housing 110. It is appreciated that the positioning of the idle relief outlet 194 may vary with respect to the configuration of the outboard engine 100. For example, outboard engines 100 come in a variety of shaft lengths, in which a spacer or a combination of spacers may be positioned between the gearcase 164 and the housing 110. This may result in some outboard engine assemblies 100 having different anti-ventilation plate 166 heights, or transom bracket 104 heights, for example.

[0066] Referring to FIGS. 2, 3, and 5 to 10, a tube 198 is disposed on the outside of the engine unit housing 110 and forms part of the idle relief passage 192. The idle relief outlet 194 is defined by the end of the tube 198. The tube 198 is sized to accommodate the different shaft lengths and mounting heights. In other words, the length of the tube 198 may be selected to position the idle relief outlet 194 below the waterline 22. The tube 198 is a straight tube fitted inside a 90-degree hose 197 (FIG. 10) and secured by a collar 199. It is contemplated that the tube 198 may be sized to be fitted on the outside of the hose. It is further contemplated that the tube 198 may be secured by a clamp, a push fitting, glue, or other means. In the present embodiment, the tube 198 is connectable to the lower mount 159. For example, the lower mount 159 may include a receiving arm configured to receive a portion of the tube 198. It is contemplated that the tube 198 may be connectable to another portion of the engine unit housing 110. It is further contemplated that the tube 198 could be omitted and the 90-degree hose 197 could be extended to the position the idle relief outlet 194 below the waterline 22, as shown in FIG. 11.

[0067] Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the appended claims.