JPH037563Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a timing belt cover seal structure that prevents foreign matter from entering the timing belt cover of an engine.

(Prior Art) Conventionally, the seal structure of a timing belt cover includes a timing pulley 2 and a belt pulley 3 fixed to a crankshaft 1, as shown in FIG. 4, in order to prevent foreign matter from entering the timing belt cover. The peripheral edge of the guide plate 11 provided between the
d, and the timing belt cover 8
A guide plate groove 8a is formed in the guide plate groove 8a, and the flange-shaped tip 11d is formed in the guide plate groove 8a.
is known (for example, see Japanese Utility Model Application No. 59-172239).

However, with the above-described sealing structure of the timing belt cover 8, foreign matter that once enters the gap 14 between the belt pulley 3 and the timing belt cover 8 is subject to centrifugal force caused by the rotation of the crankshaft 1 during engine operation. There was a problem in that the timing belt cover 8 easily entered the interior of the timing belt cover 8 as shown by the arrow 15 due to this action.

If a foreign object enters the inside of the cover 8 and gets caught in the groove of the timing belt cover 7 or the groove of the timing pulley 2, the belt 7a and the pulley 2
As a result, the timing between the piston lifting and lowering operations and the valve opening/closing operations will be out of order, which will impede the smooth operation of the engine.

Furthermore, if moisture enters the cover 8 as the foreign matter, the timing belt 7 itself will deteriorate due to this moisture, reducing its durability.

(Purpose of the invention) This invention was made to solve the above-mentioned problems, and the purpose is to provide a sealing structure for an engine timing belt cover that can prevent foreign matter from entering the timing belt cover. shall be.

(Structure of the invention) In order to achieve this purpose, in the present invention, an opening is formed in the timing belt cover,
In an engine in which a crankshaft is disposed through the opening, a plate-like body is integrally attached to the outer peripheral side of the crankshaft so as to expand outward in the radial direction of the crankshaft, and A cylindrical portion that is inserted into the opening so as to surround the outer periphery of the crankshaft is protrudingly provided on a plate surface of the plate-like body, and the cylindrical portion extends outward from at least the timing belt cover. The sealing structure of a timing belt cover for an engine is characterized in that the outer circumferential surface of the cylindrical portion is located close to the inner circumferential surface of the opening.

With the above configuration, when the engine is operating, the rotation of the cylindrical part causes air, which is a viscous fluid around the cylindrical part, to flow in the direction of rotation of the cylindrical part, thereby causing the air to flow on the outer side of the timing belt cover. (extending part of the cylindrical part), even if a foreign object approaches from the outside in the radial direction of the cylindrical part, it will be blown away by the air flow.
Even if a foreign object were to pass through the layer of air flow, the foreign object would be blown outward in the radial direction of the cylindrical section due to the centrifugal force exerted by the cylindrical section itself. It becomes difficult for foreign objects to approach the gap between the cylindrical portion and the opening in the timing belt cover. Therefore, in combination with the fact that the gap between the cylindrical portion and the opening is reduced, it is possible to reliably prevent foreign matter from entering the timing belt cover.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 1, 1 is a crankshaft, 2 is a timing pulley, and 3 is a belt pulley. Both the timing pulley 2 and the belt pulley 3 are fixed to the crankshaft 1. A belt pulley 4 formed of a metal plate is fixed to the belt pulley 3 with bolts 16, and its elastic force suppresses torque fluctuations of the belt pulley 3.

Further, 5 is a camshaft, and a timing pulley 6
is fixed. A timing belt 7 is suspended between the timing pulley 6 and the timing pulley 2, and the rotation of the crankshaft 1 is thereby transmitted to the camshaft 5.

8 is a timing belt cover that covers the timing belt 7. This timing belt cover 8 consists of a main body 8A and a front cover 8B coupled to the lower end of the main body 8A, and a belt is inserted into the timing belt cover 8 so that the crankshaft 1 can be inserted thereinto and protrude to the outside of the engine. Behind the pulley 3, across the timing belt cover main body 8A and the front cover 8B, an opening 1 is formed.
0 is formed.

Reference numeral 11 denotes a guide plate as a plate-shaped body held between the timing pulley 2 and the belt pulley 3. This guide plate 11 prevents the timing belt 7 from shifting laterally, and also functions as a cover body that covers the opening 10.

As shown in FIG. 2, the guide plate 11 is provided with a cylindrical portion 11a by bending the peripheral edge of the guide plate 11 outward. This cylindrical portion 11a is arranged such that its outer circumferential surface 11b is close to the inner circumferential surface of the opening 10.
0, and the outer end portion 11c extends outward from the timing belt cover 8.

Therefore, in the above structure, during engine operation, the guide plate 11 rotates with the rotation of the crankshaft 1, and the cylindrical portion 11 rotates.
a will also rotate. For this reason, the cylindrical portion 11
Air, which is a viscous fluid, around the cylindrical portion 11a
Therefore, on the outside of the timing belt cover 8, even if foreign matter a approaches from the outside in the radial direction of the cylindrical portion 11a (see Fig. 2), the air flow , and even if the foreign object passes through the layer of air flow, the foreign object will be radially outward of the cylindrical section 11a due to the centrifugal force of the cylindrical section 11a itself. As a result, it becomes difficult for the foreign matter to approach the gap 17 between the cylindrical portion 11a and the opening 10 in the timing belt cover 8. Therefore, together with the small gap 17, it is possible to reliably prevent foreign matter from entering the timing belt cover.

Further, as shown in FIG. 2, the cylindrical portion 11a
Even if the foreign object b that has once entered the interior 12 of the
Since the outer end portion 11c of the cylindrical portion 11a protrudes outward from the timing belt cover 8, it does not enter into the cover 8 through the gap 17.

Therefore, foreign matter that has entered the cover 8 as in the conventional case gets caught in the grooves of the timing pulley 2 and the timing belt 7, causing a misalignment between the belt 7 and the pulleys 2 and 6 (Fig. 1). Therefore, the timing of the piston lifting and lowering operations and the valve opening and closing operations will not be out of order. Furthermore, it is possible to prevent the timing belt 7 from deteriorating or decreasing its durability due to the ingress of moisture.

FIG. 3 shows another embodiment. In this embodiment, the same components as those in the previous embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, a cylindrical portion 13a is provided separately, and an outer end 13c of the cylindrical portion 13a is attached to the belt pulley 4 by riveting or welding. As a result, the belt pulley 4 can be used as a plate-shaped body, and the belt pulley 4 and the cylindrical part 13a can constitute the cover body 13 against foreign objects.

Of course, in this embodiment as well, the outer end 13c of the cylindrical portion 13a extends outside the timing belt cover 8, and the outer peripheral surface 13b of the cylindrical portion 13a is brought close to the inner peripheral surface of the opening 10. Therefore, based on the same effect as in the embodiment described above, foreign matter will not enter into the timing belt cover 8 through the gap 18 between the cylindrical portion 13 and the opening 10.

In the above two embodiments, the structure in which the front cover 8B is coupled to the lower end of the timing belt cover main body 8A has been described, but the structure is not limited to this, and the front cover 8B portion also connects to the timing belt. This invention can also be applied to a cover integrally molded with the cover main body 8A.

(Effects of the invention) As described above, according to this invention, it is possible to reliably prevent foreign matter from entering the timing belt cover with a simple structure.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing one embodiment of this invention, Fig. 2 is a sectional view of main parts to explain the operation of this invention, and Fig. 3 is a side sectional view showing another embodiment. FIG. 4 is a side sectional view showing a conventional example. 1...Crankshaft, 4...Belt pulley, 8...
...Timing belt cover, 10...Opening, 1
1... Guide plate, 11a, 13a... Cylindrical part, 11b, 13b... Outer peripheral surface, 11c, 13c
...outer end.

Claims (1)

[Scope of claim for utility model registration] An opening is formed in the timing belt cover,
In an engine in which a crankshaft is disposed through the opening, a plate-like body is integrally attached to the outer peripheral side of the crankshaft so as to expand outward in the radial direction of the crankshaft, and A cylindrical portion that is inserted into the opening so as to surround the outer periphery of the crankshaft is protrudingly provided on a plate surface of the plate-like body, and the cylindrical portion extends outward from at least the timing belt cover. A seal structure for a timing belt cover for an engine, characterized in that the outer circumferential surface of the cylindrical portion is located close to the inner circumferential surface of the opening.