JPH01224411A - Rust proof structure for tension pulley - Google Patents

Abstract

PURPOSE:To prevent the occurrence of rust at a bearing at what regulates the tensile strength of a timing belt by means of a tension pulley shaft-supported at the outer wall of an engine through the bearing, by furnishing on the outer side of the tension pulley a cover covering the bearing. CONSTITUTION:An outboard motor is arranged with an engine 15 at its upper part, and a crank shaft 21 and a cam shaft 22 protrude out of the upper well of this engine 15. And a crank shaft pulley 23 and a flywheel 24 are fitted to the crank shaft 21 and also, a cam shaft pulley 25 is fitted to the cam shaft 22, respectively. A timing belt 26 is wound around hangingly between both pulleys 23, 25. Also, a tension pulley 27 is provided in order to regulate the tensile strength of this belt 26, and this pulley 27 is rotatably supported at a shaft 28 projecting out of the upper wall of the engine 15, through a bearing 29. In this instance, an approximately disk-shaped cover 30 is furnished on the outside surface of the tension pulley 27 and the attachment of water and mud on the bearing is prevented.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a rust-proof structure for a tension pulley.

In particular, the present invention relates to a rust-proof structure for a tension pulley used to adjust the tension of a timing belt in a marine engine.

[Prior Art] Generally, in vehicle engines, a timing belt drive is the mainstream camshaft drive method, and a tension pulley is used to adjust the tension of the timing belt.

This timing belt drive system is also used in marine engines, but in the case of ships, there is a possibility of water and mud entering, which can cause the tension pulley and the bearings that support it to rust, causing the tension pulley to become damaged. This will cause rotational problems and the camshaft will not be able to drive smoothly.
This may even cause the engine to stop.

Therefore, as a rust prevention measure, it may be possible to cover all the parts related to the timing belt with one cover, but this would lead to an increase in the number of parts, and the heat dissipation of the timing belt must be taken into consideration separately. Therefore, it is conceivable to make the tension pulley and the bearing itself from a material with good corrosion resistance, but although there is no problem with the tension pulley itself, the bearing itself would be extremely expensive and would be impractical.

If the bearings rust, the grease sealed inside the bearings may leak out and cause the bearings to seize, so bearing rust prevention is extremely important for smooth camshaft operation.

Note that, conventionally, no rust prevention means have been applied to the bearing of this tension pulley.

[Invention or Problem to be Solved] The present invention was made in view of the current situation, and its purpose is to provide a simple structure and practical rust prevention for tension pulley bearings in marine engines. To provide a rust-proof structure for the tension pulley.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a marine engine in which the tension of a timing belt is adjusted by a tension pulley rotatably supported on the outer wall of the engine via a bearing. In this case, a cover covering the bearing is attached to the outer surface of the tension pulley when viewed from the engine.

[How it works] The simple structure of attaching a cover to the outer surface of the tension pulley protects the bearing from water and mud, thereby preventing it from rusting.

[Example] The present invention will be explained below based on embodiments shown in the drawings.

1 to 3 show an embodiment in which the present invention is applied to an outboard motor. First, as shown in FIG. 1, an outboard motor is attached to the stern [12] of a boat body via a clamp bracket 11 in its drive shaft casing 10. As shown in FIG. The drive shaft casing 10 is rotatable around a tilt shaft 13. An engine 15 is mounted on the upper part of the drive shaft casing 10 via a spacer 14. In this engine 15, 16 is a cylinder body, 17 is a cylinder head, 18 is a crankcase, 19 is a plug, and 20 is an exhaust manifold. A crankshaft 21 and a camshaft 22 protrude from the upper wall of the engine 15, and the crankshaft 21 has a crankshaft pulley 23 and a flywheel 24.
is attached to the camshaft 22, and a camshaft pulley 25 is attached to the camshaft 22.

As shown in detail in FIG. 2, a timing belt 26 is wound between the crankshaft pulley 23 and the camshaft pulley 25, so that the rotation of the crankshaft pulley 23 is transmitted to the camshaft via the camshaft pulley 25. 22. A tension pulley 27 is provided to adjust the tension of the timing belt 26.

As shown in detail in FIG. 3, the tension pulley 27 is
A bearing 2 is attached to a shaft 28 protruding from the earthen wall of the engine 15.
9 and is rotatably supported.

As shown in FIG. 2, the intermediate portion of the timing belt 26 is pressed to apply a predetermined tension to the timing belt 26. A substantially disc-shaped cover 30 is attached to the outer surface of the tension pulley 27 when viewed from the outer wall of the engine 15, that is, the earthen wall in this embodiment, and the bearing 29 is covered by the cover 30.

In FIG. 1, 31 is a bottom cowling, 32 is an upper cowling attached to the bottom cowling 31 via a hook 33, 34 is an intake duct, 35 is a lever, and 36 is a metal fitting. Also, in Figure 2, 37
38 is an intake manifold, 38 is a carburetor, 39 is an intake silencer, and arrow A indicates the flow of air from the intake duct 34.

In this way, the cover 30 is attached to the outer wall of the tension pulley 27.
With the extremely simple structure of mounting the tension pulley 27, the bearing 29 that rotatably supports the tension pulley 27 is covered from the outside, thereby preventing water, mud, etc. entering from the intake duct 34 from coming into contact with the bearing 29. to prevent the bearing 29 from rusting. Especially tilt axis 1 for outboard motors.
When the upper cowling 3 is held in the tilted up position rotated approximately 60 degrees to the left as shown in Figure 1, the upper cowling 3
The tension pulley 2 is placed below the cowling inlet 34a of 2.
It will be located at 7. Even if the engine is stopped, if wave spray enters, it will drip around the tension pulley 27, but the cover 30 protects the bearing 29.

Therefore, according to this embodiment, an ordinary bearing that is currently mass-produced can be used as the bearing 29, and since the structure of the cover 30 is small and simple, the bearing can be used at low cost and without increasing the number of parts. 29 rust prevention can be ensured.

Further, since the timing belt 26 itself is not covered with any cover or the like, there is no need to use a particularly heat-resistant belt, and there is no need to provide a separate heat dissipation means.

Next, FIG. 4 shows another embodiment of the present invention, and this embodiment is an example in which the present invention is applied to an inboard/outboard motor. here,
The crankshaft 21 and camshaft 22 protrude from the side of the engine 15, and therefore the timing belt 26
A tension pulley 27 for adjusting the tension of the engine 15 is also provided to protrude from the side of the engine 15. The structure of the tension pulley 27 is similar to that shown in FIG. 3 above. Here, 40 is an engine cover, 41 is an engine bracket, 42 is an air intake port, 43 is a drive unit, 44 is a propeller, and 45 is an output shaft of the engine.

In the embodiments described above, the cover 30 is fitted by fitting into the recess 27' of the tension pulley 27, but there is no need to limit it to this. For example, as shown by the two-dot chain line in FIG. Needless to say, it may be attached to the periphery.

[Effects] As explained above, according to the present invention, the rust of the tension pulley bearing can be prevented with an extremely simple structure, and the camshaft can therefore be driven smoothly. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the main parts of an outboard motor which is an example of the anti-corrosion structure of the tension pulley according to the present invention, and FIG.
An enlarged sectional view along the line ■-■ in the figure, Figure 3 is m-- in Figure 2.
FIG. 4 is a cross-sectional view taken along line 1, and FIG. 4 is a cross-sectional view showing another embodiment of the present invention. 15... Engine 26... Timing belt 27... Tension pulley 29, conflict, bearing 30... Cover agent, patent attorney Yoshiyuki Inaba Figure 3 Figure 4 Figure 15: Jν5shi2shiO:# /′

Claims (1)

[Claims] (1) In a marine engine in which the tension of a timing belt is adjusted by a tension pulley that is rotatably supported on the outer wall of the engine via a bearing, a cover that covers the bearing is attached to the outer surface of the tension pulley when viewed from the engine. Rust-proof structure of tension pulley.