JPH09250355A - Timing belt cover of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise by providing with a spacer member being protuberantly arranged on a timing belt cover for enclosing a timing belt which transfers driving force from a crank shaft sprocket to a cam shaft, so as to enclose the outer peripheral part of the crank shaft sprocket. SOLUTION: In a timing belt cover 20 for covering a timing belt 15 wrapped around a crank shaft sprocket 9 and a cam shaft sprocket 11, the lower part of the timing belt cover 20 is formed as a notch 20b by cutting of a side wall 20a. The shape of a part where the notch 20b is cut off is matched with the shape of a rib 18 arranged on the lower side of the crank shaft sprocket 9 for half enclosing the crank shaft sprocket 9 and a crank angle sensing plate 16. In the lower part of the timing belt cover 20, a circular opening hole 22 having the same center axis as the crank shaft 8 is protruberantly arranged, and a spacer part 24 is protuberantly arranged along the circumferential rim of the opening hole 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timing belt cover for an internal combustion engine mounted on a vehicle, and more particularly to a timing belt cover capable of suppressing noise caused by traveling of the timing belt.

[0002]

2. Related Background Art In recent years, an overhead cam (OHC) type engine having a structure in which a camshaft is provided on the upper part of the engine has become mainstream. In this OHC engine, a camshaft sprocket is provided at the tip of the camshaft so as to project from the engine body, and similarly, a crankshaft sprocket is provided at the tip of the crankshaft so as to project from the engine body. These sprockets are connected endlessly with a timing belt having teeth formed on the inner peripheral surface. As a result, the camshaft is rotated in synchronization with the rotation of the crankshaft, and the intake and exhaust valves provided in each cylinder are opened and closed with good timing.

Normally, a timing belt cover is provided on the side of the internal combustion engine on the side of the timing belt so as to protect the timing belt. Specifically, the timing belt cover is joined to the side surface of the internal combustion engine so as to cover the traveling range of the timing belt almost completely. By the way, the timing belt is a belt with teeth, and when the timing belt is driven by a crankshaft sprocket and travels, the sound of the timing belt teeth cutting the air (wind noise) and the sound of the timing belt meshing with the sprocket (biting noise). )
Occurs. And these sounds are usually inside the timing belt cover, that is, since a space much larger than the volume occupied by the timing belt is formed between the side surface of the internal combustion engine and the timing belt cover,
It may resonate and increase in the timing belt cover, resulting in noise.

Therefore, it has been considered to suppress such a resonance phenomenon, and a timing belt cover having a structure in which a space reducing means for reducing the volume of the space is provided between the crankshaft sprocket and the camshaft sprocket is special. It is disclosed in Japanese Patent Laid-Open No. 5-306632.

[0005]

In recent years, since the detection accuracy is high, the number of internal combustion engines having a crank angle sensor around the crankshaft is increasing. In such an internal combustion engine, a crankshaft sprocket is provided with a crank angle sensing plate which has the same axis and has a larger diameter than the crankshaft sprocket and has a thin plate shape.

A rib for securing the sealing surface of the timing belt cover is provided below the crankshaft sprocket of the internal combustion engine so as to surround the sprocket halfway. Therefore, the lower end portion of the timing belt cover is in contact with the edge portion of the rib, whereby the rib also has a function as a part of the timing belt cover.

By the way, a necessary and sufficient internal space is formed between the rib and the crankshaft sprocket in consideration of the ease of mounting the timing belt on the sprocket. In this way, when a space is formed between the crankshaft sprocket and the rib, as in the timing belt cover disclosed in the above publication,
Simply providing the space reducing means between the crankshaft sprocket and the camshaft sprocket does not lead to noise reduction. That is, in this case, in the above-mentioned timing belt cover, the biting sound generated by the meshing of the timing belt with the crankshaft sprocket easily diffuses around the crankshaft sprocket, and further, the internal sound around the sprocket is increased. After all, it will cause a resonance phenomenon in space. Usually, the ratio of this biting noise in noise is relatively large, and therefore the noise reducing effect is small only by the space reducing means disclosed in the above publication.

The present invention has been made under the above circumstances, and an object of the present invention is to provide a timing belt cover for an internal combustion engine which can suppress noise more preferably.

[0009]

In order to achieve the above-mentioned object, according to the invention of claim 1, a crankshaft sprocket fixed to one end of a crankshaft and the crankshaft sprocket is wound around the crankshaft sprocket. A timing belt cover surrounding a timing belt that transmits the driving force from the camshaft to the camshaft, characterized by comprising a spacer member that is provided so as to surround the outer periphery of the crankshaft sprocket.

Therefore, when the camshaft sprocket rotates due to the operation of the internal combustion engine, the timing belt also runs, and when the timing belt meshes with the camshaft sprocket, a biting noise is generated. Is satisfactorily insulated by the spacer member positioned so as to surround the outer circumference of the camshaft sprocket, and the noise generated when the timing belt runs is reduced.

Further, the invention according to claim 2 is characterized in that the spacer member surrounds a range of the outer circumference of the crankshaft sprocket around which the timing belt is wound. Therefore, at least the outer peripheral range of the camshaft sprocket in which the timing belt meshes with the camshaft sprocket, that is, the range in which the bite noise is generated, is preferably surrounded by the spacer member, and the bite noise is reduced with a small amount of material. Sound is surely isolated,
Noise generated due to the traveling of the timing belt is reduced.

Further, the invention according to claim 3 is characterized in that the spacer member is provided so as to fill an internal space formed around the outer periphery of the crankshaft sprocket inside the timing belt cover. Therefore,
The inner space formed inside the timing belt cover, that is, around the outer circumference of the crankshaft sprocket by the internal combustion engine and the timing belt cover is almost completely filled with the spacer member, and the biting sound resonates and is amplified in the inner space. There is no. Therefore, the spacer member has not only the sound insulation but also the function of preventing the resonance, and the noise generated by the traveling of the timing belt can be more surely reduced.

Further, in the invention of claim 4, the spacer member is formed integrally with the timing belt cover. Therefore, the spacer member is easily provided on the timing belt cover, and the manufacturing cost of the timing belt cover is reduced.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a mounting state of a timing belt cover 20 of the present invention applied to an internal combustion engine (hereinafter, simply referred to as an engine) 1 mounted on a vehicle to the engine 1, and FIG. FIG. 2 is a detailed view of a lower portion of the timing belt cover 20 viewed from the direction of arrow A in FIG. 1. Further, referring to FIG. 3, there is shown a sectional view taken along the line BB in FIG. 1 in a state where the timing belt cover 20 is attached to the engine 1.

As shown in FIG. 1, in the engine 1, the cylinder head 3 is mounted on the cylinder block 2, and the rocker cover 4 is mounted on the upper surface of the cylinder head 3.
Furthermore, an oil pan 5 is attached to the lower portion of the cylinder block 2. An oil pump case 6 is fixed to a side surface 2a of the cylinder block 2 of the side surface 1a of the engine 1, and a crankshaft 8 supported by the cylinder block 2 penetrates and projects from the oil pump case 6. A crankshaft sprocket 9 with teeth is fitted on the crankshaft 8.

A camshaft 10 penetrates and projects from a side surface 3a of the cylinder head 3 among the side surfaces 1a of the engine 1, and a camshaft sprocket 11 having teeth is externally fitted to the camshaft 10. . The reference numeral 12 on the side surface 2a is an idler pulley, and the reference numeral 13
Is a tensioner pulley. The crankshaft sprocket 9, the camshaft sprocket 11, the idler pulley 12, and the tensioner pulley 13 arranged in this way
A timing belt 15 is endlessly wound around and has teeth formed on its inner peripheral surface. Therefore, when the engine 1 operates and the crankshaft sprocket 9 rotates together with the crankshaft 8, the camshaft sprocket 11 satisfactorily rotates via the timing belt 15 in synchronization with this, and the camshaft 10 rotates. As a result, the intake valve and the exhaust valve (both not shown) arranged in the cylinder head 3 for intake and exhaust of the engine 1 are opened and closed with good timing.

Side 2 of crankshaft sprocket 9
A thin plate-shaped crank angle sensing plate 16 having a diameter larger than that of the crankshaft sprocket 9 and having a plurality of cutouts in the outer peripheral portion is attached to the surface on the a side substantially integrally with the crankshaft sprocket 9. There is. Therefore, the crank angle sensing plate 16 is adapted to rotate together with the crankshaft sprocket 9. The crank angle sensing plate 16 constitutes a detection unit of a crank angle sensor (not shown) for detecting the rotation angle of the crank angle.

Below the crankshaft sprocket 9, a thin rib 1 is spaced apart from the crankshaft sprocket 9 by a predetermined distance so as to partially surround the crankshaft sprocket 9 and the crank angle sensing plate 16.
8 are provided. The rib 18 is integrally provided with the oil pump case 6, and is provided so as to project in parallel with the axis of the crankshaft 8. The protruding height of the rib 18 is set so as to slightly project from the side end surface 9a of the crankshaft sprocket 9. ing. The rib 18 is provided to secure a sealing surface when the timing belt cover 20 is attached to the oil pump case 6, mainly because the oil pump case 6 has many surface irregularities. Therefore, the rib 18 facilitates attachment of the lower portion of the timing belt cover 20 to the oil pump case 6. Further, on the lower surface side of the oil pump case 6, it is usually necessary to provide a flange portion projecting to the front of the engine 1 for mounting the oil pan 5 and the like. Since the engine 1 is also provided with a function, space saving is achieved without inviting an increase in the size of the engine 1. The predetermined distance is, for example, a distance that can secure a working space required when the timing belt 15 is wound around the crankshaft sprocket 9.

Crankshaft sprocket 9
Also, the timing belt cover 20 having the timing belt cover main body 21 around which the side wall 20a is formed so as to cover the timing belt 16 wound around the camshaft sprocket 11 is provided with the bolt 30 on the side surface 1a of the engine 1. It is attached by fasteners such as. As shown in the figure, the side wall 20 a is removed from the lower portion of the timing belt cover 20, and the notch 20
b is formed. The shape of the removed portion of the notch 20b matches the shape of the rib 18, and therefore, in the state where the timing belt cover 20 is attached to the side surface 1a of the engine 1, as shown in FIG. ,
The peripheral edge of the notch 20b and the peripheral edge of the rib 18 are in contact with each other in a substantially sealed state. The timing belt cover 20 is
For example, it is formed of a heat resistant resin material.

At the bottom of the timing belt cover 20,
A circular opening 2 having the same axis as the crankshaft 8
When the timing belt cover 20 is attached to the side surface 1a of the engine 1, the crankshaft 8 penetrates through the opening 22 (see FIG. 3). Referring to FIG. 2, a spacer portion 24, which functions as a sound insulating member, is provided around the periphery of the opening hole 22 integrally with or separately from the timing belt cover body 21 in the same direction as the extension direction of the side wall 20a. ing. The spacer portion 24 can substantially completely fill the space (internal space) formed between the crankshaft sprocket 9 and the rib 18 when the timing belt cover 20 is attached to the side surface 1a of the engine 1. Thus, the predetermined height and thickness are set (see FIG. 3). The spacer portion 24 is not provided over the entire circumference of the peripheral edge of the opening hole 22, but a predetermined range is cut out as a cutout 24a. This notch 2
4a allows the timing belt cover 20 to move to the engine 1
The traveling of the timing belt 15 (shown by the broken line in FIG. 2) is not hindered in the state where the timing belt 15 is attached to the side surface 1a of the.

The operation of the timing belt cover 20 constructed as above will be described below. Normally, when the engine 1 is operated and the timing belt 15 is made to travel via the crankshaft 8 and the crankshaft tosprocket 9, when the timing belt 15 is meshed with the crankshaft tosprocket 9, the tooth gap of the timing belt 15 is reduced. The air will be swept out rapidly. As a result, a so-called timing belt 15 biting sound is generated. Normally, the biting sound is generated by the timing belt 15
Runs at a high speed, the timing belt 15 is generated along the outer circumference of the crankshaft tosprocket 9 in the entire range in which the timing belt 15 is meshed with the crankshaft tosprocket 9, that is, the entire range of the ribs 18. Then, this biting sound becomes louder as the rotation speed of the engine 1 increases.

However, in the timing belt cover 20 of the present invention, as shown in FIG. 3 described above, when the timing belt cover 20 is attached to the side surface 1a of the engine 1, the spacer portion 24 is It is positioned so as to substantially completely fill the space between the crankshaft sprocket 9 and the rib 18 with its tip slightly separated from the crank angle sensing plate 16.

Therefore, even if the timing belt 15 is made to travel and the above-mentioned biting noise is generated due to the meshing with the crankshaft sprocket 9, there is almost no space between the crankshaft sprocket 9 and the rib 18. This crankshaft sprocket 9 and rib 1
Between 8 the biting sound will not resonate and be amplified. Further, since the spacer portion 24 has a predetermined thickness, it also functions as a shield plate, and therefore, the biting sound is almost completely shielded by the spacer portion 24,
It is prevented from spreading to the surroundings.

Referring to FIG. 4, there is shown a measurement result obtained by measuring a noise level such as a biting noise generated as the timing belt 15 runs at a position about 30 cm before the crankshaft sprocket 9. In the figure, the broken line shows the noise level when the timing belt cover that does not have the spacer portion 24 is used, and the solid line shows the spacer portion 2.
4 shows the noise level when the timing belt cover 20 of the present invention having No. 4 is used.

According to FIG. 3, the noise level increases with increasing engine speed Ne of the engine 1 in both the broken line and the solid line, but in the case of the solid line, that is, the timing belt cover 20 having the spacer portion 24. It can be seen that the case where is used is made smaller overall.
In particular, this tendency is remarkable in the region where the engine speed Ne is large, and the noise level is much smaller when the timing belt cover 20 having the spacer portion 24 is used.

That is, as the engine speed Ne increases, the bite noise also increases. By using the timing belt cover 20 of the present invention having the spacer portion 24, the crankshaft sprocket 9 of the bite noise is generated. The resonance between the rib and the rib 18 can be prevented, and the spacer portion 2
Due to the sound insulation effect of No. 4, it is possible to prevent the biting sound from being diffused to the surroundings, and the noise level can be appropriately reduced.

By the way, when the timing belt 15 is loosely tensioned, when the timing belt 15 meshes with the crankshaft sprocket 9, the timing belt 15 floats from the crankshaft sprocket 9 and a so-called tooth jump phenomenon may occur. is there. However, in the timing belt cover 20 of the present invention, since the spacer portion 24 is provided close to the timing belt 15 with a slight gap, the timing belt 15 tends to float from the crankshaft sprocket 9. In that case, the floating of the timing belt 15 is restricted by the abutment of the timing belt 15 with the spacer portion 24, so that the tooth jumping phenomenon can be preferably prevented.

In the timing belt cover 20 of the above embodiment, the spacer portion 24 is provided only between the crankshaft sprocket 9 and the rib 18, that is, in the range where the timing belt 15 is wound around the crankshaft sprocket 9. Although configured, but not limited to this,
As shown in FIG. 5, the spacer portion 24 ′ having the same thickness and the same height as the spacer portion 24 is also in the range sandwiched by the endless timing belts 15 on the extension of the spacer portion 24.
The timing belt cover 20 ′ provided with may be used. Here, the spacer portion 24 ′ may be integrated with the timing belt cover body 21 or may be a separate body.

Hereinafter, the timing belt cover 20 'will be described.
The operation of will be described. The timing belt cover 20 'is the same as the timing belt cover 20 except for the spacer portion 24'.
The same reference numerals are given. Referring to FIG. 6, the timing belt cover 20 ′ shown in FIG.
4 is a sectional view similar to that of FIG. As described above, if the timing belt cover 20 'is used so that the crankshaft sprocket 9 is substantially completely surrounded by the spacer portion 24 and the spacer portion 24', a central space formed on the camshaft sprocket 11 side in the drawing is used. Propagation of the biting sound to 40 is satisfactorily blocked.
This not only prevents the resonance of the biting sound in the space between the crankshaft sprocket 9 and the rib 18 and the diffusion of the biting sound around the spacer portion 24, which is an effect of the timing belt cover 20, but also the biting sound. Resonance in the central space 40 is also suitably prevented, and a better sound insulation effect is obtained.

In this case, instead of the spacer portion 24 ',
It is of course possible to apply the above-mentioned conventional space phenomenon means to the central space 40, but if the timing belt cover 20 'having the spacer portion 24' is used, the space phenomenon means is provided. The same effect as that of the case can be facilitated and realized at low cost.

[0031]

As described above in detail, according to the timing belt cover of the internal combustion engine of claim 1 of the present invention, the crankshaft sprocket fixed to one end of the crankshaft and the crankshaft sprocket wound around the crankshaft sprocket. The timing belt cover encloses the timing belt that transmits the driving force from the crankshaft sprocket to the camshaft, and the timing belt cover is provided with a spacer member that is provided so as to surround the outer periphery of the crankshaft sprocket. When the belt meshes with the camshaft sprocket, the biting noise can be satisfactorily shielded by the spacer member positioned so as to surround the outer circumference of the camshaft sprocket, and the noise generated when the timing belt runs can be reduced appropriately. .

Further, according to the timing belt cover of the internal combustion engine of the second aspect, the spacer member surrounds the range of the outer circumference of the crankshaft sprocket around which the timing belt is wound. The noise can be surely insulated, and the noise generated by the traveling of the timing belt can be reduced in cost and satisfactorily reduced.

Further, according to the timing belt cover of the internal combustion engine of claim 3, the spacer member is provided so as to fill the internal space formed around the outer periphery of the crankshaft sprocket inside the timing belt cover. With the timing belt cover, the biting noise can be prevented from resonating in the internal space formed around the outer circumference of the crankshaft sprocket. That is, the spacer member can well have not only the sound insulation function but also the resonance prevention function, and the noise generated due to the traveling of the timing belt can be further surely reduced.

Further, according to the timing belt cover of the internal combustion engine of the fourth aspect, the spacer member is formed integrally with the timing belt cover, so that the spacer member can be easily provided on the timing belt cover and the timing belt cover can be provided. The manufacturing cost of the belt cover can be reduced.

[Brief description of drawings]

FIG. 1 is a view showing a mounting state of a timing belt cover of the present invention on an internal combustion engine.

FIG. 2 is a perspective view of the timing belt cover viewed in the direction of arrow A in FIG.

FIG. 3 is a cross-sectional view taken along the line BB in FIG. 1 with the timing belt cover attached to the internal combustion engine.

FIG. 4 is a diagram showing a noise prevention effect of the timing belt cover of the present invention.

FIG. 5 is a perspective view of another timing belt cover.

FIG. 6 is a cross-sectional view showing another timing belt cover attached to the internal combustion engine.

[Explanation of symbols]

 1 Internal Combustion Engine 1a Side 2 Cylinder Block 3 Cylinder Head 8 Crank Shaft 9 Crank Shaft Sprocket 10 Cam Shaft 11 Cam Shaft Sprocket 15 Timing Belt 16 Crank Angle Sensing Plate 18 Rib 20, 20 'Timing Belt Cover 21 Timing Belt Cover Body 24, 24 '' Spacer part (spacer member)

Front page continuation (72) Inventor Yuji Nakamura 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (4)

[Claims] 1. A timing belt cover surrounding a crankshaft sprocket fixed to one end of a crankshaft and a timing belt which is wound around the crankshaft sprocket and which transmits a driving force from the crankshaft sprocket to a camshaft. A timing belt cover for an internal combustion engine, comprising a spacer member provided so as to surround an outer periphery of the crankshaft sprocket. 2. The timing belt cover for an internal combustion engine according to claim 1, wherein the spacer member surrounds a range of the outer circumference of the crankshaft sprocket around which the timing belt is wound. 3. The timing of an internal combustion engine according to claim 1, wherein the spacer member is provided inside the timing belt cover so as to fill an internal space formed around the outer periphery of the crankshaft sprocket. Belt cover. 4. The timing belt cover for an internal combustion engine according to claim 1, wherein the spacer member is formed integrally with the timing belt cover.