JP2515606Y2 - Engine cooling system for small planing boats - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an engine cooling device for a small planing boat (also called a small boat).

[0002]

2. Description of the Related Art A hull is molded of synthetic resin or the like, and a base end of a handle pole is rotatably supported on an upper surface of a bow.
At the free end of the handle pole, the left and right handlebars are pivotally supported so that they can be rotated almost in the horizontal plane, and the floor is formed behind the engine room in the center of the hull. Equipped with a jet propulsion device that drives a propulsion pump mounted on the bottom of the stern and sprays pressurized water from a nozzle to run, and the driver gets on the floor in an upright position and handles bar 2. Description of the Related Art A small-sized planing boat has been put into practical use, in which a steering device set on the bottom of a stern can be swung to the left and right to steer by gripping a grip portion at the tip and rotating the grip portion.

The engine in a small planing boat of this type is water-cooled, and cooling water is also introduced into the exhaust manifold, the exhaust pipe, and the exhaust pipe system such as a muffler in which high-temperature exhaust gas flows to cool them. The method has been adopted. As the cooling water, water pressurized by a propulsion pump is taken and sent to the engine, the cylinder head part is cooled from the engine cylinder, and then the cooling water is guided to an exhaust manifold having a double structure and exhaust gas. Is indirectly cooled, and then the cooling water is passed through a cooling water pipe and jetted into the exhaust pipe on the upstream side of the muffler to be mixed with the exhaust gas to cool the exhaust gas. (For example,
(See Japanese Utility Model Publication No. 52-18551)

[0004]

As described above, when the engine section and the exhaust pipe system are cooled by using the water pressurized by the propulsion pump, when the engine speed increases, the engine output shaft Since the rotation speed of the directly connected propulsion pump increases, the amount of cooling water taken in from the propulsion pump also increases in proportion to the rotation speed. (See FIG. 4) This increase in the amount of cooling water is desirable for cooling the cylinder and the cylinder head portion of the engine because the engine output increases as the engine speed increases.

However, the engine is generally a water-cooled type.
Since the engine is equipped with a cycle engine and an exhaust inertia type muffler is installed to improve the output as an exhaust pipe muffler, increasing the amount of cooling water to the muffler in the maximum output range of the engine will cool the exhaust gas. There is a possibility that the sound speed will decrease and the pulsating wave that returns will be delayed, the maximum output point will move to the low rotational speed side (matching will shift), and the output of the engine will decrease. (A in FIG. 3
Shows a performance curve when the amount of cooling water is optimum, and b and c show the case where the amount of cooling water covers. ) The present invention has been made in view of the above point, and ejects the amount of cooling water, which increases from the propulsion pump in proportion to the number of revolutions, into the exhaust pipe with some limitation during high-speed operation. It is an object of the present invention to provide a cooling device for an engine for a small planing boat, which can optimize the matching with a muffler and maintain a good engine output.

[0006]

Means for Solving the Problems The gist of the present invention for achieving the above object is to introduce water pressurized by a propulsion pump into an engine to cool the engine portion, and then to exhaust pipe. In a small planing boat engine that cools the system, a cooling water amount control device is installed in the cooling water pipe that ejects cooling water from the engine part to the exhaust pipe upstream of the muffler and mixes it into the exhaust gas. Viper to the device
The cooling water pressure flowing through the cooling water pipe is
When the pressure exceeds, the valve will open and the cooling water will flow through the bypass pipe.
An engine cooling device for a small planing boat, which is characterized in that the amount of cooling water discharged and ejected into an exhaust pipe is controlled .

[0007]

[Operation] During high-speed operation, the fuel is injected into the exhaust pipe upstream of the muffler.
Controls the amount of cooling water that is emitted and mixed with the exhaust gas,
Since the matching with the muffler is optimized, the output of the engine can be kept good without sacrificing the cooling of the engine.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view with an essential part cut away showing an example of an engine cooling system of a small planing boat.

In this invention, the hull 1 is molded of synthetic resin or the like, and the base end of the handle pole 3 is rotatably supported by a handle pole bracket 2 fixed to the upper surface of the bow. The left and right handlebars 4 made of pipes are pivotally supported on the lower surface of the free end of the engine so that they can be pivoted in a substantially horizontal plane, and the engine cover 5 is attached to the center of the hull.
The engine room 6 is covered with a floor 8 having a deck 7 on the left and right, and a high-power water-cooled two-cycle engine 9 is mounted on the engine room 6 to stern the hull. The propulsion pump 10 installed in the engine is driven, and the muffler 11, the fuel tank 12 and the like are installed in the engine room 6 in association with the engine 9 to propel the engine and the exhaust pipe system for cooling. Cooling water introduction pipe 13 for taking in pressurized water from the pump 10 and sending it to the engine 9.
The basic structure of a small planing boat equipped with an engine cooling device having the above is known.

The engine cooling system of this invention is constructed as follows.

The pressurized cooling water introduced from the propulsion pump 10 through the cooling water introduction pipe 13 cools the cylinder head portion of the cylinder of the engine 9 and then the cooling water provided with the cooling water amount control device 15. It is passed through the pipe 16 and ejected into the upstream exhaust pipe 17 of the first muffler 11a to be mixed with the exhaust gas.

After that, the cooling water and the exhaust gas flow from the first muffler 11a through the second muffler 11b to the third muffler 11c to receive a sound absorbing effect, and then in the third muffler from the top thereof. It is vertically installed to open the inlet end 18a near the bottom of the muffler, and the outlet end 18b is discharged to the outside of the ship via the discharge pipe 18 set outside the bow.

However, the cooling water amount control device 15 is
It consists of a control valve and an operating part, and in order to optimize matching with the muffler during high-speed operation, the cooling water volume, cooling water pressure,
It is configured to be appropriately controlled based on the muffler temperature and the engine speed.

For example, since the cooling water pressure is proportional to the number of revolutions, there is a cooling water control device 15 which operates by the cooling water pressure as shown in FIG.

This cooling water control device 15 has a check valve 20 held by a spring 19 having a target value set, and when the pressure of the cooling water flowing through the cooling water pipe 16 exceeds a predetermined pressure during high speed operation, the spring is controlled. Valve 20 against the force
Is opened and excess cooling water is discharged to the outside through the bypass pipe 21.

[0017]

As described above, according to the present invention, the amount of cooling water jetted into the exhaust pipe on the upstream side of the muffler and mixed with the exhaust gas is controlled at high speed to optimize matching with the muffler. Can be maintained well.

[Brief description of drawings]

FIG. 1 is a side view in which a main part is cut away showing an example of an engine cooling system of a small planing boat.

FIG. 2 is a schematic configuration diagram showing an example of a cooling water control device.

FIG. 3 is an explanatory diagram illustrating a shift in matching with a muffler.

FIG. 4 is a diagram showing a relationship between a rotation speed and a pump absorption output.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hull 9 ... Engine 10 ... Propulsion pump 11 ... Muffler 13 ... Cooling water introduction pipe 14 ... Exhaust manifold 15 ... Cooling water amount control device 16 ... Cooling water pipe 17 ... Exhaust pipe 18 ... Discharge pipe

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F01N 7/12 F01N 7/12 (72) Inventor Yukio Nishimura 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Akashi Plant Co., Ltd. (56) Reference JP-A-4-265407 (JP, A) Actually developed 49-71993 (JP, U) Actually developed 56-122722 (JP, U) Actually developed 2-144613 ( JP, U)

Claims (1)

(57) [Scope of utility model registration request] Claim: What is claimed is: 1. In a small planing boat engine, wherein water pressurized by a propulsion pump is introduced into an engine to cool the engine part, and then the exhaust pipe system is cooled. A cooling water amount control device is installed in the cooling water pipe that is jetted to the exhaust pipe of the above and mixed into the exhaust gas, and a bypass pipe is connected to the cooling water amount control device,
If the pressure of the cooling water flowing in the pipe exceeds the specified pressure,
Open the valve and discharge the cooling water from the bypass pipe to the exhaust pipe.
An engine cooling device for a small planing boat, which is characterized by controlling the amount of cooling water ejected .