JP3084781B2 - Cooling system for jet propulsion boat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for a jet propulsion boat.

[0003]

2. Description of the Related Art There is a jet propulsion device as a propulsion device for a small boat. This jet propulsion device has a jet pump that sucks water from an intake port of an intake duct by an impeller that is rotationally driven by an engine, pressurizes the water, and jets the pressurized water into the water from a nozzle at the rear of the intake duct. The thrust is given to the boat by the reaction force of the water jet injected by the jet pump.

Conventionally, in cooling the engine of such a jet propulsion device, a part of the pressurized water in the nozzle portion is forcibly taken in, and the water is guided to an engine and an exhaust system such as a muffler to cool them. (For example, see Japanese Utility Model Laid-Open No. 1-139021).

[0005]

However, in a structure in which cooling water is simply taken in from a nozzle to cool a required cooling portion, even if overheating of the engine can be prevented, the engine may be overcooled. In order to prevent such overcooling of the engine, it is conceivable to adjust the temperature of the cooling water using a thermostat or the like. However, when a part of the cooling water is discharged inside the muffler to cool the muffler and discharged outside the boat, the thermostat is turned on and off.
When the amount of cooling water flowing through the muffler is changed by turning OFF, when the cooling water flow rate is increased, the exhaust efficiency is reduced and the engine output is affected. As a result, the engine output is reduced and becomes unstable. There was a problem.

According to the present invention, when cooling water is controlled using a thermostat, the flow rate of the cooling water to the muffler is kept constant, the exhaust efficiency is stabilized, the engine output is prevented from lowering, and the piston is scuffed by supercooling. It is an object of the present invention to provide a cooling device for a jet propulsion boat, which eliminates the occurrence of troubles. [Configuration of the invention]

[0007]

In order to solve the above-mentioned problems, a cooling device for a jet propulsion boat according to the present invention pressurizes water sucked by a jet pump driven by an engine and jets the water into the water. In a jet propulsion boat that propels a boat by force, the cooling water passage is branched into an engine cooling system equipped with a thermostat and an engine exhaust cooling system that cools exhaust pipes etc. with an exhaust manifold that guides part of the jet water Then, the bypass passage branched from the engine exhaust cooling system is communicated with the downstream side of the thermostat of the engine cooling system, and the downstream side of the thermostat is communicated with the outside of the boat, and the excess cooling water is discharged out of the boat through the bypass passage. It is configured as follows.

[0008]

[Function] Water from the jet pump taken into the exhaust manifold is branched into an engine cooling system equipped with a thermostat and an exhaust cooling system that cools exhaust pipes, etc., and the engine is cooled through a bypass passage branched from the exhaust cooling system. Since it is connected to the downstream of the thermostat of the system and discharged from the boat from the downstream of the thermostat, the flow rate required for engine cooling is obtained when the thermostat is ON, and the cooling water discharged from the muffler is also output Does not affect When the thermostat is OFF, part of the cooling water guided to the engine exhaust cooling system is discharged out of the boat from the bypass passage, so that the engine exhaust cooling system discharges to the muffler stably and affects the engine output. There is no.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a side view of an engine / jet unit incorporated in a jet propulsion boat to which the present invention is applied.
FIG. 2 is a plan view of the engine / jet unit, and FIG. 3 is a left front view of FIG. The structure of the jet pump 8 is similar to the conventional one, and a drive shaft 11 is inserted into a bearing portion 10 of an intake duct 9 so as to be rotatably supported, and an impeller (not shown) is accommodated in an impeller housing 12 at a rear portion of the intake duct 9. The impeller is rotationally driven to suck and pressurize water from a water suction port 9a of the intake duct 9, and pressurized water is jetted from a nozzle 13 at a rear portion of the impeller housing 12 as a jet stream. Reference numeral 14 denotes a deflector for moving the jet propulsion boat backward.

An inlet 13a for pressurized water is provided at the side of the nozzle 13.
The cooling water piping system 15 introduced from the intake 13a enters the passage around the exhaust manifold 17 of the engine 16 from the nozzle 13 as described with reference to the drawings together with the flow shown in FIG. As shown in FIG. 5, the exhaust pipe 18 and the engine exhaust cooling system 2 of the muffler 19 are provided by the exhaust manifold 17.
0 and branches to an engine cooling system 22 of an engine body 21 such as a cylinder.

The cooling water distributed to the engine exhaust cooling system 20 is divided by an exhaust pipe 18 into a passage to a muffler 19 and a bypass passage 24 connected to a thermostat cap 23, as shown in FIGS. Can be The cooling water distributed to the engine cooling system 22 passes through the cylinder head 25, the thermostat manifold 26, and the thermostat 27, and is distributed to the engine exhaust cooling system 20 in the thermostat cap 23 as shown in FIGS. 2 and 3. The water merges with the water and is discharged to the outside of the boat via a drain passage (not shown) provided separately from the engine exhaust system of the exhaust pipe 18 and the muffler 19.

The cooling water guided to the engine cooling system 22 is adjusted by turning on and off the thermostat 27, while the cooling water guided to the engine exhaust cooling system 20 is turned on and off by the thermostat 27 via the bypass passage 24. As a result, the flow rate of the cooling water discharged into the muffler 19 can be kept constant, and the temperature rise of the engine exhaust system can be suppressed.

Therefore, when the thermostat 27 is ON, a flow rate required for cooling the engine is obtained, and the cooling water discharged from the muffler 19 does not affect the engine output. When the thermostat 27 is OFF, if there is no bypass passage 24, all the cooling water is exhausted from the exhaust pipe 1.
The cooling water is discharged to the inside of the vessel 8 and there is a risk that the exhaust efficiency may be reduced and the engine output may be reduced. However, in this embodiment, a part of the cooling water is guided to the outside of the boat from the bypass passage 24 and is discharged. The water discharge into 19 is stable and does not affect the engine output.

In FIG. 5, reference numeral 28 denotes a crankcase upper, 29 denotes a crankcase lower, and 3 denotes a crankcase lower.
0 is a water pump.

[0016]

As described above, in the cooling system for a jet propulsion boat according to the present invention, the cooling water passage is formed by the exhaust manifold through which a part of the jet water from the jet pump is guided, and the engine cooling system having the thermostat is provided. And an engine exhaust cooling system for cooling an exhaust pipe and the like, and a bypass passage branched from the engine exhaust cooling system is communicated with the downstream side of the thermostat of the engine cooling system, and the downstream side of the thermostat is communicated with the outside of the boat. As a result, the excess cooling water is discharged from the bypass passage to the outside of the boat, so that the amount of cooling water to the muffler can be kept constant, thereby stabilizing the exhaust efficiency and preventing the engine output from lowering. You. Further, since the engine cooling flow rate is appropriately controlled using the thermostat, scuffing of the piston due to supercooling or the like is prevented, and engine troubles can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a left front view of FIG. 1;

FIG. 4 is an enlarged view of a thermostat portion.

FIG. 5 is an enlarged view of an exhaust manifold portion.

FIG. 6 is a cross-sectional view of an exhaust pipe portion.

FIG. 7 is a flowchart.

[Explanation of symbols]

 Reference Signs List 8 Jet pump 9 Intake duct 13a Nozzle 15 Piping system 16 Engine 17 Exhaust manifold 18 Exhaust pipe 19 Muffler 20 Engine exhaust cooling system 21 Engine body 22 Engine cooling system 23 Thermostat cap 24 Bypass passage 25 Cylinder head 26 Thermostat manifold 27 Thermostat

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01P 3/20 B63B 35/73 F01P 7/16 508 F01P 11/02 F01P 11/04

Claims (1)

(57) [Claims] 1. A jet propulsion boat in which water sucked by a jet pump driven by an engine is pressurized and jetted into the water, and the boat is propelled by a reaction force thereof. An exhaust manifold in which part of the jetted water is guided. The cooling water passage branches into an engine cooling system equipped with a thermostat and an engine exhaust cooling system that cools exhaust pipes, etc., and a bypass passage branched from the engine exhaust cooling system communicates with the downstream side of the thermostat of the engine cooling system. A cooling device for a jet propulsion boat, wherein the downstream side of the thermostat is connected to the outside of the boat to discharge excess cooling water to the outside of the boat from the bypass passage.