US20050266744A1

US20050266744A1 - Personal watercraft engine fluid cooling system

Info

Publication number: US20050266744A1
Application number: US10/854,625
Authority: US
Inventors: Jeffrey Gardner; Cory Knudtson
Original assignee: Individual
Current assignee: Polaris Inc
Priority date: 2004-05-26
Filing date: 2004-05-26
Publication date: 2005-12-01

Abstract

An engine fluid cooling system that utilizes the jet propulsion unit of a personal watercraft to cool the engine fluid. The cooling system includes passages for transporting engine fluid to and from a cooling system that includes a cooling channel formed about a component of the jet propulsion unit so that as the engine fluid travels through the cooling channel, heat, contained in the engine fluid, is transferred to the water flowing through the jet propulsion unit.

Description

FIELD

This disclosure relates to a system for cooling engine fluids in a personal watercraft. More particularly, this disclosure relates to a cooling system utilizing the watercraft's jet propulsion unit to cool engine fluids.

BACKGROUND

Personal watercrafts have an internal combustion engine contained within an engine compartment that is typically positioned forward of the tunnel. The engine powers a jet propulsion unit that propels the watercraft through the water. The output shaft of the engine drives an impeller on the jet propulsion unit. The impeller, which is conventionally contained within a housing, pulls in water from a water inlet located on the underside of the boat, and discharges the water at high velocity through a steerable nozzle at the rear of the boat. An oil tank, typically provided adjacent to or within the engine contains a lubricating fluid for lubricating the moving parts of the engine. The lubricating fluid, typically oil, is cycled through the engine and returns to the oil tank where it is reused until the lubricating fluid is drained and replaced during routine maintenance.
During operation, the lubricating fluid absorbs heat and must be cooled to function effectively. Known systems for cooling oil involve pumping oil from the engine to a tubular member located proximate to the water inlet. The water drawn up the water inlet by the jet propulsion pump passes over the tubular member and cools the engine oil contained therein. Other systems employ heat exchangers mounted to the internal combustion engine that draw heat from the lubricating oil and absorb it into a cooling fluid.
Engine fluids can be efficiently cooled by utilizing the flow of cool water through the jet propulsion unit.

SUMMARY

In various embodiments there is provided a personal watercraft that includes a hull and an overlying deck that includes a cavity defining an engine compartment. The watercraft further includes an engine located in the engine compartment, coupled to a jet propulsion unit for powering the watercraft. A cooling system for cooling a lubricating fluid of the engine is also included. The cooling system includes a lubricating fluid channel surrounding a component of the jet propulsion unit for flowing the lubricating liquid through the liquid passage to exchange heat of the lubricating fluid with water taken up by the jet propulsion unit.
In various embodiments there is provided a cooling system for engine lubricating fluid for a jet-propelled watercraft. The cooling system includes a jet propulsion unit and a channel formed about a component of the jet propulsion unit for circulating engine lubricating fluid thereabout. The cooling system further includes a fluid passageway coupled to an engine lubricating fluid reservoir for delivering heated lubricating fluid to the channel where it is cooled and then returning the lubricating fluid to the reservoir.
In various embodiments there is provided a jet propulsion unit for a jet-propelled watercraft. The jet propulsion unit includes an outer housing, an impeller journalled within the outer housing, a discharge nozzle positioned rearward of the impeller, and an engine lubricating fluid channel formed about an exterior of the outer housing so that heat from the engine lubricating fluid is transferred to water pumped by the jet pump.

DRAWINGS

FIG. 1 is a perspective view of a typical personal watercraft with the engine fluid cooling system.
FIG. 2 is a perspective exploded view of a prior art jet propulsion unit from a typical personal watercraft.
FIG. 3 is a schematic of an embodiment of an engine fluid cooling system.
FIG. 4 is a perspective view of an embodiment of an engine fluid cooling system shown coupled to a personal watercraft engine.
FIG. 5 is a perspective view of an embodiment of an engine fluid cooling system shown coupled to a personal watercraft engine.
FIG. 6 is a perspective view of an embodiment of an engine fluid cooling system provided on a jet pump housing of a jet propulsion unit.
FIG. 7 is a front perspective view of an embodiment of an engine fluid cooling system shown provided on a jet pump housing of a jet propulsion.
FIG. 8 is flowchart illustrating the operation of an embodiment of an engine fluid cooling system.

DESCRIPTION OF VARIOUS EMBODIMENTS

The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily drawn to scale, depict selected embodiments and are not intended to limit the scope of the embodiments. Several forms of the embodiments will be shown and described, and other forms will be apparent to those skilled in the art. It will be understood that embodiments shown in drawings and described are merely for illustrative purposes and are not intended to limit the scope of the embodiments as defined in the claims that follow. Although the engine fluid cooling system is shown with respect to a sit-down type jet ski it should be understood that the embodiments of the engine fluid cooling system can be practiced with any marine vehicle that utilizes a jet propulsion unit.
FIG. 1 illustrates generally a watercraft 10 that can include the embodiments of the engine fluid cooling system, as will be described hereinafter. Watercraft 10 has generally a front or bow 12 and a rear or stern 14 and includes an upper portion 16 that includes a top deck 18 and shroud 20. The top deck 18 is secured to a bottom hull 22 along an overlapping portion covered with a rub rail 24, thereby forming a hull. The hull formed by the bottom hull 22 and top deck 18 defines a compartment sized to house an internal combustion engine 28 for powering the watercraft 10 and may also include one or more storage compartments (not shown), depending on the size and configuration of the watercraft.
The deck portion 18 also has a raised, longitudinally extending seat 30 adapted to accommodate one or more riders seated in straddle fashion. A grab handle 31 may be disposed transversely across the rear of the seat 30.
Engine 28 powers a jet propulsion unit 32 (described with more detail with respect to FIG. 2), typically mounted in a tunnel at the bottom rear portion of the watercraft, all shown in phantom in FIG. 1. An oil reservoir 33 is provided adjacent to the engine for providing lubrication to the moving parts of the engine. Jet propulsion unit 32 includes a steerable water discharge nozzle 34 that is operatively coupled to a set of handlebars 36 to facilitate steering of the watercraft by the operator. The connection between handlebars 36 and discharge nozzle 34 may be of any suitable type, and typically includes mechanical linkages including a control cable (not shown). If desired, an electronic connection could also be utilized.
The engine may be a two-stroke or four-stroke type engine. Typically, in four-stroke engine watercrafts, a cooling system that circulates a cooling fluid, typically, a glycol/water mixture, is employed. Closed loop cooling systems, (not shown) are well known in the art and include generally, a coolant reservoir, which includes inlet and outlet conduits for directing coolant to and from the engine. Typically, a pump is included for continually circulating the fluid. In operation, as the engine cycles, coolant is circulated through various components of the engine where heat from the engine is transferred to the coolant. Thereafter, the coolant is returned to the coolant reservoir.
FIG. 2 is an exploded perspective view of a typical prior art jet propulsion unit 40 for a personal watercraft. Jet propulsion unit 40 is usually positioned towards the rear of the watercraft near a water inlet. A water inlet is generally provided at the rear of the watercraft. The jet propulsion unit 40 typically includes a water jet housing 42, a pump stator 44 and impeller 48. The pump stator 44 includes a plurality of stator blades 46 and impeller 48 includes a plurality of blades 50. Jet propulsion unit 40 may also include a pump extension 52 and a first stationary nozzle 54 and second rotatable nozzle 56. The impeller 48 is coupled to the engine (shown in FIG. 1) via a drive shaft (shown in FIG. 4) to pull water from the body of water in which the watercraft is operated.
The moving parts of 4-stroke engines are typically lubricated with oil. In the course of lubrication, heat generated by the moving parts of the engine is transferred to the lubricating fluid as it circulates, undesirably increasing the temperature of the lubricating fluid, which, in turn, decreases its efficiency as a lubricant. Obviously, the heat absorbed by the lubricating fluid must be transferred to another source to maintain functionality of the lubricating fluid, as well as, so that the lubricating fluid has capacity to absorb more heat on its subsequent pass through the engine.
FIG. 3 illustrates, diagrammatically, the cooling system of the disclosure. Typically, engines include a closed loop system 57 for circulating engine fluids, including, without limitation, engine lubricant and engine coolant. The closed loop system 57 continually recycles a volume of fluid until the fluid is replaced. Generally, engine fluids absorb heat produced by the moving parts of the engine so that the engine can operate efficiently. In order for the engine fluids to function efficiently, heat absorbed by the engine fluids must be removed. An embodiment of the engine fluid cooling system includes an open loop cooling system 59 that works in cooperation with the closed loop system 57 to remove heat retained in the engine fluid circulating therein. In operation, a heat transfer, depicted at 61, occurs between the closed loop system 57 and the open loop system 59.
FIG. 4 depicts an embodiment of the engine lubricating fluid cooling system. FIG. 4 illustrates a typical 4-stroke engine 58 for a personal watercraft coupled to a typical jet propulsion unit 40 via a drive shaft 60 for driving the impeller (shown in FIG. 2). The engine 58 includes an oil reservoir 33 for holding oil after it circulates through various parts of the engine 58. Oil passage lines 64 and 66 are coupled to openings (not shown) in the oil reservoir 33. The oil passage lines 64 and 66 may be made of rubber, plastic, metal, or any other suitable material. Oil passage line 64 transports warmed engine oil to the jet propulsion unit 40, where it is cooled. Return line 66 extends from a cooling channel 68 of the jet propulsion unit 40 to the reservoir 33 for returning cooled oil to the reservoir 33 so that it may circulate through the engine 58.
In the embodiment depicted in FIG. 4, the engine fluid being cooled is engine lubricating oil. Oil passage line 64 is coupled to a channel 68, which is a hollow conduit 70 that is coiled about a component of the jet propulsion unit 40. The conduit 70 is shown coiled about the jet pump housing of the jet propulsion unit 40. The conduit 70 is made of a material that allows for heat transfer, such as, without limitation, plastic, rubber, or metal. The diameter of the conduit 70 will vary depending upon the geometry of the component on which it is installed. It is preferable to maximize the surface area over which heat transfer will occur. Therefore, the diameter and geometry of the conduit 70 may be varied so that efficient cooling can occur.
The conduit 70 is coupled to the oil passage line 64 for delivering heated oil to the channel 68 and oil return line 66 for returning cooled oil to the reservoir 33. As the heated oil travels the length of the conduit, heat contained in the oil is transferred to the cool water streaming through the jet propulsion unit 40. Typically, as is known in the art, in closed loop systems, the system is pressurized and a small pump may be provided to continuously circulate the oil between the reservoir, engine and cooling system.
FIG. 5 illustrates an alternate embodiment where engine fluid, for example, engine coolant, is circulated to the cooling system at the jet propulsion unit 40. Similar to the embodiment depicted in FIG. 4, an outlet 66 and inlet 64 line are coupled to the engine coolant reservoir 69 and the cooling system is provided at the jet propulsion unit 40. This embodiment operates similarly to the embodiment depicted in FIG. 4. Typically, in closed loop systems, a pump is provided to maintain constant circulation. In general, the pressure created by this pump is adequate to continue the flow of coolant throughout the engine and to and from the open loop cooling system 59 provided at the jet propulsion unit 40. Thus, after coolant has circulated through the engine and absorbed heat therefrom, it circulates to the cooling system and the heat is transferred to the ambient water flowing through the jet propulsion unit 40.
FIG. 6 is a more detailed perspective view of an embodiment of the cooling channel. As can be seen, a length of hollow conduit 70 is coiled a number of times about the exterior of the jet propulsion unit 40. In the embodiment depicted, the hollow conduit 70 is coiled about the exterior surface of the jet pump housing 72 in a linear fashion. Those skilled in the art will appreciate that the conduit may be coiled about the component in any pattern, such as, for example, a helical pattern. In the embodiment depicted in FIG. 4, the adjacent coils are shown touching each other. The coils may or may not be welded together, however, it should be understood that the conduit may be coiled such that a gap is left between adjacent coils. The number of times that the conduit is coiled about a component is dependent on factors such as the length and diameter of the conduit as well as the geometry of the particular jet propulsion component about which the conduit is coiled. As mentioned above, it is desirable to maximize the surface area to maximize heat transfer.
As water is drawn through the jet pump housing 72, heat from the oil flowing through the hollow conduit 70 is transferred to the water that is at a lower temperature and thus cools the oil. The engine fluid cooling system de allows for cooling at any engine speed including idle. In a typical watercraft, the impeller rotates at approximately 1,500 RPM at idle. Thus, water continues to travel through the jet pump system even when the watercraft is at idle, thus providing continuous cooling capacity of engine fluids even when the watercraft is not in motion.
FIG. 7 depicts an embodiment of a cooling channel. In this embodiment, the oil is directed from the engine to a cooling channel 68 that is formed between the outer surface 74 of a component of the jet propulsion unit 40 and an internal surface 76 of ajacket 78. The jacket 78 is comprised of a solid enclosure that encases any qualifying component of the jet propulsion unit (described above). In the embodiment depicted in FIG. 7, the channel 68 is shown formed on the jet pump housing 79. An empty space, or channel 80 is created between the jet propulsion unit component and the jacket through which heated oil delivered from the oil reservoir may flow and transfer heat to the water traveling through the jet propulsion unit 40. Alternately, the cooling channel jacket 78 may be formed of a single piece that includes an internal channel with walls defined solely by the internal surfaces of the jacket. In this embodiment, the oil does not directly contact a surface of the jet propulsion unit. However, an internal surface contacts the outer surface of the jet propulsion unit and heat transfer from the oil to the water flowing through the jet propulsion unit occurs through the surface of the jacket and the surface of the jet propulsion unit. The jacket may be fabricated from metal, plastic, rubber, or any other suitable material that is impermeable yet capable of transferring heat efficiently. A separate water jacket piece as described above may be used to retrofit an existing jet propulsion unit.
In an alternate embodiment, the water jacket and jet propulsion unit are formed as one integral piece as is well known in the art. In this embodiment, a channel is formed between the jet propulsion component and water jacket, as in the embodiment already described, by providing a mold that produces such a channel.
The jacket, formed according to any of the embodiments, includes an inlet (not shown) for coupling the oil reservoir to the cooling jacket to deliver heated oil to the cooling jacket and an outlet (not shown) for returning the cooled oil to the oil reservoir 33. The inlet and outlet may be formed as orifices for receiving oil passage lines as shown in FIG. 3 in a sealed manner so that no oil is lost in the cooling process.
The cooling channel, according to any embodiment, is sized and shaped so that it interfaces with the component of the jet propulsion unit without interfering with the operation of the jet propulsion unit. For example, if the cooling channel is provided on the second nozzle (shown in FIG. 2), it should be of a size and configuration so as to not interfere with the pivotal rotation of the rotatable nozzle (shown in FIG. 2).
The channel may be provided on any component of the jet propulsion unit that is between the inlet and outlet of the jet pump. For example, without limitation, the channel may be provided on the pump extension, the jet pump housing, the stator, the first stationary nozzle or the second rotatable nozzle (all shown in FIG. 2). The only requirements for the placement of the cooling channel is that it lie adjacent to the flow of water through the jet propulsion unit and the component is of a size so that a sufficient surface is exposed to the water flowing through the jet propulsion unit to accomplish adequate cooling of the oil.
The cooling system can be used to cool any number of engine fluids. As FIG. 3 illustrates diagrammatically, the cooling system may be used to cool the engine cooling fluid. As depicted, coolant from the closed loop cooling system 57 may be directed to the open loop cooling system 59 and heat contained within the engine fluid is transferred to the water flowing through the jet propulsion unit 40 as described above.
The engine fluid cooling process is illustrated diagrammatically in FIG. 8. As the engine operates, various engine fluids, including lubricating oil and coolant, are circulated through various engine parts. During circulation, the temperature of the engine fluids increases. To function effectively, these fluids must be cooled before subsequent cycling through system. Contemporaneously with fluid cycling, the engine drives a drive shaft that rotates an impeller. As the impeller rotates, water is drawn inward and flows through the jet propulsion unit. Heated engine fluids are transferred to the jet propulsion unit where a heat transfer between the engine fluid and the ambient water entering the jet propulsion unit occurs. Finally, the cooled engine fluid is routed back to the engine where it can be cycled again.
Thus, embodiments of the Personal Watercraft Engine Fluid Cooling System are disclosed. One skilled in the art will appreciate that these embodiments can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the embodiments are limited only by the claims that follow.

Claims

1. A system for a personal watercraft having an engine fluid cooling apparatus, the system comprising:

a hull and an overlying deck, forming a cavity that defines an engine compartment;

an engine, located in the engine compartment, coupled to a jet propulsion unit for powering the watercraft; and

an engine fluid passage surrounding a component of the jet propulsion unit for directing the engine fluid through the engine fluid passage so that heat in the engine fluid is transferred to water taken up by the jet propulsion unit.

2. The personal watercraft of claim 1, further including an engine fluid channel line coupling an engine fluid reservoir to the engine fluid passage for delivering heated lubricating fluid to the passage for cooling.

3. The personal watercraft of claim 1, wherein the engine fluid passage is a conduit coiled about the component of the jet propulsion unit.

4. The personal watercraft of claim 1, wherein the engine fluid passage is a coil formed about a jet pump housing of the jet propulsion unit.

5. The personal watercraft of claim 1, wherein the engine fluid passage is a channel formed between an exterior of the component of the jet propulsion unit and a jacket formed about the component of the jet propulsion unit.

6. The personal watercraft of claim 5, wherein the jacket is integral with the component of the jet propulsion unit.

7. The personal watercraft of claim 1, wherein the engine fluid passage is a channel formed between an exterior of a jet pump housing of the jet propulsion unit and a jacket formed thereabout.

8. An engine fluid cooling apparatus for a jet-propelled watercraft, comprising:

an engine fluid passage formed about a component of a jet propulsion unit for circulating engine fluid thereabout, and

an engine fluid passageway coupling an engine fluid reservoir to the engine fluid passage, wherein heated engine fluid is delivered to the engine fluid passage where it is cooled and then returned to the engine fluid reservoir.

9. The cooling system of claim 8, wherein the engine fluid passage is formed by coiling a hollow conduit about the component of the jet propulsion unit.

10. The cooling system of claim 8, wherein the engine fluid passage is a hollow conduit coiled about a stator of the jet propulsion unit.

11. The cooling system of claim 8, wherein the engine fluid passage is formed by coiling a hollow conduit coiled about a jet pump housing of the jet propulsion unit.

12. The cooling system of claim 8, wherein the engine fluid passage is a channel formed between an exterior of the component of the jet propulsion unit and a jacket that at least partially surrounds the component of the jet propulsion unit.

13. The cooling system of claim 12, wherein the component of the jet propulsion unit is a stator.

14. The cooling system of claim 12, wherein the component of the jet propulsion unit is a jet pump housing.

15. A jet propulsion unit for a jet-propelled watercraft, comprising:

an outer housing;

an impeller journalled within the outer housing;

a discharge nozzle positioned rearward of the impeller; and

an engine lubricating fluid channel formed contiguously with the outer housing so that heat from an engine fluid is transferred to water flowing through the jet propulsion unit.

16. The jet propulsion unit of claim 15, wherein the engine lubricating fluid channel is couplable to an engine lubricating fluid reservoir.

17. The jet propulsion unit of claim 15, wherein the engine lubricating fluid channel is a hollow conduit coiled around the outer housing.

18. The jet propulsion unit of claim 17, wherein the hollow conduit is coiled around a jet pump housing.

19. The jet propulsion unit of claim 17, wherein the hollow conduit is coiled around a stator of the jet propulsion unit.

20. The jet propulsion unit of claim 15, further comprising an inlet in the engine lubricating fluid channel for receiving heated lubricating fluid from an engine of the watercraft.

21. The jet propulsion unit of claim 20, further comprising an outlet in the engine lubricating fluid channel for diverting cooled lubricating fluid back to the engine.

22. A cooling system for cooling an engine fluid of a watercraft, comprising:

cooling means formed about a component of the jet propulsion unit; and

means for transporting the engine fluid to and from the cooling means.

23. A method of cooling an engine fluid of a watercraft, the method comprising the steps of:

diverting an engine fluid from a circulatory path to an engine fluid cooling system located at a jet propulsion unit of a watercraft;

transferring heat stored in the engine fluid to ambient water traveling through the jet propulsion unit thereby cooling the engine fluid; and

returning the cooled engine fluid to its circulatory path.

24. A method of cooling an engine fluid in a watercraft, comprising the step of:

circulating a heated engine fluid adjacent to a component of a jet propulsion unit so that heat contained in the engine fluid is transferred to ambient water flowing through the jet propulsion unit.