JP2001123830A - Belt chamber cooling structure for small sea craft engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt chamber cooling structure for a small sea craft engine, capable of improving durability of timing belt, while preventing temperature rise in a belt chamber. SOLUTION: This small sea craft engine 3, in which a cam shaft 28 is driven by the timing belt 32 stored in a belt chamber S covered with timing belt covers 40, 43 has water jackets 45, 46 formed in the timing belt covers 40, 43. With the water jackets 45, 46 formed in the timing belt covers 40, 43, the belt chamber S for storing the timing belt 32 is cooled by a cooling water flowing in the water jackets 45, 46 and is restrained from rise in temperature rise, whereby the overheating of the timing belt 32 stored in the belt chamber S is prevented, and the deterioration in durability is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt room cooling structure for a small marine engine that drives a cam shaft by a timing belt.

[0002]

2. Description of the Related Art For example, a personal watercraft travels on water by thrust generated by a jet propulsion device driven by an engine. To 4
Attempts have been made to use a cycle engine.

[0003]

In a four-stroke engine, a timing belt for rotating a camshaft constituting a valve mechanism is indispensable. Particularly, in a small boat sailing on water, a timing belt is required. There is a possibility that water adheres to the belt, and the durability of the timing belt may be reduced by the adhesion of water.

Therefore, a configuration in which the timing belt is covered with a timing belt cover is conceivable. However, since the belt chamber covered with the timing belt cover forms a closed space, the temperature in the belt chamber rises and the belt chamber is accommodated in the belt chamber. The timing belt may overheat and its durability may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to cool the belt compartment cooling of a small marine engine capable of preventing the temperature rise in the belt compartment and improving the durability of the timing belt. It is to provide a structure.

[0006]

According to the first aspect of the present invention, a cam shaft is driven by a timing belt and the timing belt is housed in a belt chamber covered by a timing belt cover. In the small boat engine, a water jacket is formed on the timing belt cover.

According to a second aspect of the present invention, in the first aspect of the present invention, the water jacket is formed at a portion of the timing belt cover facing the timing belt.

According to a third aspect of the present invention, in the first or second aspect of the invention, the water jacket is formed at least in a portion of the timing belt cover overlapping the timing belt when viewed in the crankshaft direction. .

Therefore, according to the present invention, since the water jacket is formed on the timing belt cover, the belt chamber accommodating the timing belt is cooled by the cooling water flowing through the water jacket, so that the temperature rise is suppressed, and the belt chamber is suppressed. The overheating of the timing belt housed in the vehicle is prevented, and the durability of the timing belt is prevented from lowering.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side view of a personal watercraft equipped with a four-cycle engine having a belt chamber cooling structure according to the present invention, and FIG. 2 is a plan view of the personal watercraft.

A personal watercraft 1 shown in FIGS. 1 and 2 has a hull 2a having a substantially V-shaped cross section and a deck 2 mounted on the hull 2a.
b is joined and integrated, and the hull 2
A hull 2a has a four-cycle engine 3 as a drive source mounted at a substantially central portion in the front-rear direction. And engine 3
1 (in the direction of arrow F in FIGS. 1 and 2).
The hatch cover 5 and a pair of left and right cover members 6 cover the upper part of the engine 3, the fuel tank 4, and the like. A steering handle 7 is provided outside the cover member 6 above the engine 3. Have been.

An upper end of a pair of left and right intake ducts (ventilation hoses) 8 is opened in front of the steering handle 7 of the deck 2b constituting the boat body 2.
A seat 9 is detachably provided behind the steering handle 7, and a storage box 10 is provided below a rear portion of the seat 9.
Are arranged. Each intake duct 8 communicates the interior of the hull 2 with the atmosphere to supply intake air to the engine 3 and
It is for ventilating inside.

On the other hand, as shown in FIG. 1, at the rear end of the hull 2 and at the center of the hull 2 in the width direction, the jet propulsion unit 1
1 is disposed, and a crankshaft 12 of the engine 3 is provided.
The front end of an impeller shaft 13 extending in the front-rear direction at the center in the width direction of the hull 2 is connected to a rear end of the boat body 2 by a coupling 14. The impeller shaft 13 is introduced into the jet propulsion device 11, and the rear end of the impeller shaft 13 is
An impeller (not shown) built in the impeller housing 11a is attached. At the rear end of the jet propulsion device 11, a steering nozzle 15 whose direction changes left and right by a steering operation of the steering handle 7 is swingably attached.

Here, details of the four-cycle engine 3 and its belt chamber cooling structure will be described with reference to FIGS. 3 is a partially cutaway front view of the engine, FIG. 4 is a front view of the engine with a second timing belt cover removed, and FIG. 5 is a cutaway side view of a timing belt portion of the engine.

[0016] Four-cycle engine 3 according to the present embodiment
Is a fuel injection type multi-cylinder engine. As shown in FIG. 3, a crankcase 17 is attached to a lower portion of a cylinder block 16 of the engine 3 and a cylinder head 18 is attached to an upper portion of the cylinder block 16. A head cover 19 is attached to an upper portion of the cylinder head 18.

The cylinder block 16 has four
The three cylinders are arranged side by side in the front-rear direction of the hull 2 (the direction perpendicular to the paper surface of FIG. 3).
The piston 21 is connected to the crankshaft 12 via a connecting rod 22. Note that the crankshaft 12 is arranged long in the front-rear direction of the hull 2 in the crankcase 17.

The cylinder head 18 attached to the upper surface of the cylinder block 16 is formed with an intake passage 23 and an exhaust passage 24 for each cylinder. The intake valve 25 and the exhaust valve 26 are respectively opened and closed at appropriate timings, whereby required gas exchange is performed in each cylinder 20.

That is, the intake valve 25 and the exhaust valve 26
Are opened and closed at appropriate timing by an intake camshaft 27 and an exhaust camshaft 28 (see FIGS. 4 and 5) arranged in parallel with each other on the cylinder head 18. As shown in FIGS. 4 and 5, , Intake camshaft 27 and exhaust camshaft 28
Belt pulleys 29, 30 of the same diameter are attached to the respective ends of the belt pulleys 29, 30, respectively.
An endless timing belt 32 is wound between the drive shaft 31 and a small-diameter drive pulley 31 attached to the front end of the crankshaft 12. A tension pulley 33 is in contact with the timing belt 32.
3, a required tension is applied to the timing belt 32. As shown in FIG. 5, a flywheel magneto 34 is attached to the front end of the crankshaft 12.

When the engine 3 is driven, the crankshaft 12 rotates from the drive pulley 31 via the timing belt 32 and the belt pulleys 29 and 30 to the intake camshaft 2.
7 and the exhaust camshaft 28, respectively, and the intake camshaft 27 and the exhaust camshaft 28 are respectively driven to rotate at a predetermined speed (a half speed of the crankshaft 12). The exhaust valves 26 are opened and closed at appropriate timings, and required gas exchange is performed in each cylinder 20 as described above.

The engine 3 according to the present embodiment
In FIG. 4, the end face on the side where the timing belt 32 is provided has a cylinder block 16 as shown in FIG.
And the crankcase 17, one sealing surface 35 is formed. Similarly, the cylinder head 18 and the head cover 19
One sealing surface 36 is formed.

The intake camshaft 27 and the exhaust camshaft 28 and the belt pulleys 29, 3 attached to their respective ends are located in a region surrounded by the one (upper) seal surface 36.
0, and a part of the timing belt 32 is facing,
A part of the timing belt 32, the tension pulley 33, the driving pulley 31, and a starter motor 37 face a region surrounded by the other (lower) seal surface 35. The crankshaft 12 penetrates and protrudes outside in a region surrounded by the seal surface 35, and the flywheel magneto 34 (see FIG. 5) is attached to the protruding end.

As shown in FIG. 4, a plurality of bolt holes 39 are formed in the sealing surfaces 35 and 36, respectively. The belt cover 40 is joined, and the first
The timing belt cover 40 has seal surfaces 35a and 36a that contact the seal surfaces 35 and 36, and the bolt holes 39.
And bolt holes 38 formed in the sealing surfaces 35a and 36a so as to correspond to. The first timing belt cover 40 seals the sealing surfaces 35a and 36a with the engine 3
In contact with the sealing surfaces 35, 36 formed on the
A plurality of bolts 41 screwed into the bolt holes 38 and 39
(See FIG. 5).

An opening S2 is formed inside the sealing surface 36a of the first timing belt cover 40, and an opening S1 is formed inside the sealing surface 35a. Seal surface 36
Then, the opening S2 is closed by the cylinder head 18 and the head cover 19, while the opening S1 is closed by the cylinder block 16 and the crankcase 17 by bringing the sealing surface 35a into contact with the sealing surface 35 on the engine 3 side. .

Further, the first timing belt cover 4
As shown in FIG.
0a is formed, and a plurality of bolt holes 42 are formed in the sealing surface 40a. And the sealing surface 40
As shown in FIG. 5, a second timing belt cover 43 made of an aluminum alloy is joined to the first timing belt cover 40 so as to cover the opening of the first timing belt cover 40. The first timing belt cover 40 is attached to the first timing belt cover 40 by a plurality of bolts 44 (see FIG. 5) screwed into the first timing belt cover.

As shown in FIG. 5, the peripheral wall of the first timing belt cover 40 (that is, the engine 3
Water jackets 45 and 46 are formed on at least a portion of the front wall of the second timing belt cover 43 (a portion facing the timing belt 32), respectively, at a portion overlapping the timing belt 32 in a side view. The cooling water supplied from the flow path downstream of the impeller in the jet propulsion device 11 flows through the water jackets 45 and 46. Note that the water jacket 46 is configured by attaching a lid member separate from the second timing belt cover 43 to a peripheral wall formed integrally with the second timing belt cover 43 with a bolt. In the present embodiment, the water jacket 45 is formed over the entire peripheral wall of the first timing belt cover 40. However, the water jacket 45 may be formed on a part of the peripheral wall.

As shown in FIG. 5, the second timing belt cover 43 has a mounting boss 43a connected to an intake chamber 51 connected to the upstream end of an intake pipe connected to the intake passage 23 (see FIG. 3). Is attached via
The suction port 51 a formed integrally therewith is open so as to face the second timing belt cover 43.

When the jet propulsion device 11 is driven by the engine 3 in the personal watercraft 1 shown in FIGS. 1 and 2 on which the four-stroke engine 3 having the above configuration is mounted, the jet propulsion device 11 The personal watercraft 1 slides on the water by the generated thrust. In the four-stroke engine 3 according to the present invention, the first and second timing belt covers 40 and 43 form the belt chamber S as a closed space. Since the timing belt 32 is stored in the belt chamber S, the intrusion of water into the belt chamber S is reliably prevented. Therefore, water does not adhere to the timing belt 32 in the belt chamber S, and the durability of the timing belt 32 is improved.

Water jackets 45 and 46 are formed on the timing belt covers 40 and 43, respectively. Cooling water flows through the water jackets 45 and 46, so that the belt chamber S in which the timing belt 32 is accommodated is formed. The cooling is carried out by the cooling water flowing through the water jackets 45 and 46, so that the temperature rise is suppressed, and the timing belt 32 is prevented from being overheated and the durability of the timing belt 32 is prevented from being lowered.

Then, the water jackets 45, 46
Is supplied with the cooling water taken out from the jet propulsion device 11, so that a dedicated cooling water supply device is not required, and the structure is simplified.

Here, another embodiment of the cooling structure of the belt chamber S will be described with reference to FIGS.

FIG. 6 is a front view of the engine viewed from the direction of the timing belt cover, and FIG. 7 is a sectional view taken along the line AA of FIG. A water jacket 47 is formed at the center in the width direction of the upper half of the wall (the area indicated by oblique lines).
The timing belt cover 43 and the belt chamber S are cooled to prevent the timing belt 32 from overheating.
In FIG. 6, reference numeral 52 denotes the water jacket 4.
Reference numeral 53 denotes a cooling water inlet to the water jacket 45, reference numeral 53 denotes a cooling water outlet to the water jacket 47, and reference numeral 55 denotes a cooling water outlet from the water jacket 47.

On the front surface of the second timing belt cover 43, a plurality of reinforcing ribs 43b are integrally formed. The reinforcing ribs 43b form a peripheral wall of the water jacket 47, and a front end face of the peripheral wall. A lid 56 (see FIG. 7) is removably attached to the front surface of the lid 56, the second timing belt cover 43, and the reinforcing ribs 43.
The water jacket 47 is formed by b. And the water jacket 47 is provided with the reinforcing ribs 4.
Although divided into a plurality of small chambers by 3b, as shown in FIG. 7, a communication passage 43b-1 for communicating each small chamber is formed in the reinforcing rib 43b. These configurations are the same in the cooling structure shown in FIGS.

FIG. 8 is a front view of the engine viewed from the direction of the timing belt cover. In the embodiment shown in FIG.
A water jacket 48 is formed in a ring-shaped portion (region indicated by oblique lines) covering the flywheel magneto in the lower half of the front wall of the timing belt cover 43, and the second timing belt cover is formed by the cooling water flowing through the water jacket 48. 43 and the belt chamber are cooled to prevent the timing belt 32 from overheating. FIG.
In the figure, 57 is a cooling water inlet to the water jacket 48, and 58 is a cooling water outlet from the water jacket 48.

FIG. 9 is a front view of the engine viewed from the direction of the timing belt cover. In the embodiment shown in FIG.
The water jacket 49 is formed in the area around the timing belt cover 43 shown by hatching in FIG. 9 (the area other than the area shown by hatching in FIGS. 6 and 8), and the cooling water flowing through the water jacket 49 The second timing belt cover 43 and the belt chamber are cooled to prevent the timing belt 32 from overheating. Note that FIG.
In the figure, 59 is a cooling water inlet to the water jacket 49, and 60 is a cooling water outlet from the water jacket 49.

FIG. 10 is a cutaway side view of the end of the engine 3. In the embodiment shown in FIG. 10, the water jacket 5 formed on the front wall of the second timing belt cover 43 is formed.
0 to the suction port 51 a of the suction chamber 51, and the second cooling water flows through the water jacket 50.
The timing belt cover 43 and the belt chamber are cooled to prevent the timing belt 32 from overheating, and the intake air (air) sucked into the intake chamber 51 is cooled to increase the charging efficiency of the intake air in the engine 3.

Thus, even in the cooling structure described above, the timing belt 32 can be prevented from being overheated and the durability thereof can be improved.

Although the present invention has been described with reference to the case where the present invention is applied particularly to a belt-chamber cooling structure of a four-stroke engine mounted on a small personal watercraft, the present invention is applicable to any small boat other than the small personal watercraft. It is needless to say that the present invention can be similarly applied to a belt chamber cooling structure of a mounted four-cycle engine.

[0039]

As is clear from the above description, according to the present invention, a camshaft is driven by a timing belt, and the timing belt is housed in a belt chamber covered by a timing belt cover. In the engine, since the water jacket is formed on the timing belt cover, the belt chamber can be cooled by the cooling water flowing through the water jacket, and the temperature inside the belt chamber can be prevented from increasing, and the durability of the timing belt can be improved. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a personal watercraft equipped with a four-cycle engine having a belt room cooling structure according to the present invention.

FIG. 2 is a plan view of a personal watercraft equipped with a four-stroke engine having a belt room cooling structure according to the present invention.

FIG. 3 is a partially cutaway front view of a four-cycle engine including the belt chamber cooling structure according to the present invention.

FIG. 4 is a front view of the four-stroke engine including the belt chamber cooling structure according to the present invention, with a second timing belt cover removed.

FIG. 5 is a cutaway side view of a timing belt portion of a four-stroke engine including the belt chamber cooling structure according to the present invention.

FIG. 6 is a front view of an engine for illustrating another embodiment of the belt chamber cooling structure according to the present invention, as viewed from a timing belt cover direction.

FIG. 7 is a sectional view taken along line AA of FIG. 6;

FIG. 8 is a front view of an engine for illustrating another embodiment of the belt chamber cooling structure according to the present invention, as viewed from a timing belt cover direction.

FIG. 9 is a front view of an engine for illustrating another embodiment of the belt chamber cooling structure according to the present invention, as viewed from a timing belt cover direction.

FIG. 10 is a cutaway side view of an engine end showing another embodiment of the belt chamber cooling structure according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Small personal watercraft (small boat) 3 4 cycle engine (small boat engine) 12 Crankshaft 27 Intake camshaft (camshaft) 28 Exhaust camshaft (camshaft) 32 Timing belt 40 First timing belt cover 43 Second Timing Belt Cover 45-50 Water Jacket S Belt Chamber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02B 67/06 F16H 7/02 A F16H 7/02 57/04 C 57/04 GB63H 21/24 F term (Reference) 3G016 AA02 AA08 AA12 BA22 BA24 BB04 CA17 CA18 CA33 CA35 CA36 CA51 CA56 GA00 GA10 3J049 AA03 BH11 BH13 CA02 3J063 AA23 AB22 BA03 BA15 BB11 CA10 CB22 CD67 XH02 XH13 XH22 XH43

Claims (3)

[Claims] 1. A small marine engine in which a cam shaft is driven by a timing belt and the timing belt is housed in a belt chamber covered by a timing belt cover, wherein a water jacket is formed on the timing belt cover. Features a cooling structure for the belt chamber of a small marine engine. 2. The cooling structure for a belt of a small marine engine according to claim 1, wherein said water jacket is formed in a portion of said timing belt cover facing said timing belt. 3. The cooling structure for a belt of a small marine engine according to claim 1, wherein the water jacket is formed at least in a portion of the timing belt cover overlapping the timing belt when viewed in the crankshaft direction. .