JP2000008950A - Cover plate structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain cover for reducing the vibration and noise of the specific frequency of an engine. SOLUTION: In plural ribs formed on the backside of a chain cover 1, an attenuation plate 9 is combined so as to cover the block rib 8 forming a ring shape projection part and an installation hole 9a is provided on the surface of the attenuation plate 9. A specific frequency is decided by the surrounded space 10 and installation hole 9a and the vibration and noise of this frequency are reduced. The rigidity is increased by a simple structure and the minimum weight may be only increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art When an internal combustion engine is mounted on a vehicle, the internal combustion engine is mounted via anti-vibration rubber or the like so as to prevent transmission of noise and vibration during operation. When a cover for covering the drive chain of the internal combustion engine, an oil pan, etc. are attached,
The rigidity is increased and the rigidity is ensured so as not to be affected by vibration. The present invention relates to a cover plate structure of an internal combustion engine which reinforces a flat portion such as a cover and an oil pan.

[0002]

2. Description of the Related Art In an internal combustion engine, a camshaft drive chain is bridged between a crankshaft and a camshaft in order to take timing between a piston and a valve in a cylinder. The camshaft drive chain is arranged outside the cylinder block, is covered with a chain cover having a concave cross section, and the periphery of the chain cover is fastened to the cylinder block with bolts.

The outer periphery of a chain cover 1 shown in FIG. 8A is formed in conformity with the shape of a cylinder block 2, and a mounting hole 3 is formed in a peripheral edge thereof. As shown in FIG. 4 are arranged. In addition, a hole 5 for projecting the crankshaft is formed in the lower center part of the chain cover 1. As shown in FIG. 8B, a sealing material 6 is arranged on the back side of the chain cover 1, and a reinforcing rib 7 is provided on an inner flat surface (see FIG. 7).
Are formed.

[0004] By the way, measures against the vibration and noise of the internal combustion engine in the chain cover 1 are as follows.
The vibration of the entire cover is suppressed by increasing the thickness of the plate or increasing the reinforcing ribs 7. Also, do not create a space created by the concave portion of the chain cover 1 or
Or reduce the volume of the space by filling the space, resonance,
There is also a structure that makes resonance difficult (Japanese Patent Laid-Open No. 5-306632).
No., JP-A-6-146916).

[0005] A zigzag separating passage is formed in the head cover, a chamber is provided in the passage, and a chamber is provided.
67813). In addition, there is a case where a mounting case is provided on the chain case to increase the rigidity (see Japanese Patent Application Laid-Open No. 10-47157), and there is also a structure in which a muffling plate is screwed into the chain cover via an elastic body. Yes (Japanese Patent Laid-Open No. 7-8632
No. 7).

[0006]

However, if the noise and vibration of a specific frequency are abnormally noticeable during the operation of the internal combustion engine even if the vibration is reduced by the rigidity of the chain cover 1, some of the above-mentioned structures are selected. Even so, since the overall level is lowered to reduce noise and vibration at specific frequencies, it is necessary to add extra ribs and increase the wall thickness more than necessary for strength, resulting in an increase in weight and associated cost And other problems.

An object of the present invention is to provide a cover plate structure of an internal combustion engine which can reduce noise and vibration of a specific frequency by simple means.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, there is provided a cover for covering a device which is a source of vibration and noise by forming a closed space inside and covering the device. In the plate, a plurality of ribs are formed on the cover plate, and among the plurality of ribs, a damping plate is joined to the ribs connected in a ring shape in a lid shape to form a space, and the space and the closed space are formed. Characterized in that the partition is provided with an intake hole.

According to a second aspect of the present invention, in the first aspect, a plurality of spaces surrounded by a plurality of ribs and a damping plate are arranged.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a specific resonance frequency is provided by the enclosed space and the hole of the damping plate.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, a plurality of enclosed spaces have different resonance frequencies.

According to a fifth aspect of the present invention, a reinforcing rib on the back side of the chain cover is extended lengthwise and crosswise, an annular convex portion is formed by the reinforcing rib, and a perforated damping plate is formed so as to cover the annular convex portion. It is characterized by being joined.

Normally, when a chain cover (cover plate) having a U-shaped cross section is mounted on a cylinder block, a closed space is formed inside, and a damping plate having an optimally shaped hole is formed in a rib formed on the inner surface of the chain cover. And join them together. Although it is not common, when a plate is attached in the form of a lid to the rib formed on the outer surface of the chain cover and a space is provided outside, the optimally shaped hole is not drilled in the plate but the chain on the closed space side Open the cover. Therefore, the partition of the closed space indicates a chain cover or a damping plate depending on a difference in an assembly structure.

That is, the cover plate is provided with an air chamber (space portion) and an intake hole to a closed space, and functions as a resonator to attenuate noise and vibration at a predetermined frequency. Further, the damping plate forming the space portion is fixed to the contact surface with the rib by applying a sealing material or applying an adhesive, and welding with an adhesive or ultrasonic wave or heating. Alternatively, the size of the damping plate is appropriately larger than the size surrounded by the ribs, and the damping plate is fastened to the cover plate by bolts and screws at a position shifted from the contact surface.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The chain cover 1 shown in FIGS. 1 and 2 is formed in a U-shape in cross section, and a closed space is formed between the chain cover 1 and the chain cover 1 by being attached to the cylinder block 2. (Abbreviated). A plurality of ribs 7 are provided on the back side surface of the chain cover 1, and the area surrounded by the ribs 7 is formed in various sizes.

The ribs 7 forming the enclosed area are particularly called closing ribs 8 (annular convex portions; see FIGS. 3 and 4), and a damping plate 9 having a shape similar to the closing ribs 8 is covered like a lid. A gap is formed between the contact surface 8a and the closing rib 8 with a sealing material 6 or an adhesive so that sound is not leaked from this portion. The material of the damping plate 9 and the chain cover 1 may be a synthetic resin, a light metal alloy such as aluminum, or a sintering material (internal loss is different due to the high attenuation of carbon). They are joined by welding by sound waves or heating.

The attenuating plate 9 is provided at a position where a specific frequency is attenuated and with a predetermined size of the intake hole 9a.
Is open. In addition, the space volume of the chain cover 1
It is desirable to be optimal for a specific vibration generated in the apparatus or to attenuate the frequency of the noise. However, since the size and shape of the closing rib 8 are limited to some extent, the volume of the space 10 becomes a certain value to a certain extent. In order to attenuate the frequency, the size and shape of the intake hole 9a are important. Therefore, an optimally shaped intake hole 9a for attenuating a specific frequency is obtained from each data. Conversely, as shown in FIG. 5, when the reduction frequency f ₀ is determined, by increasing the capacity of the space 10 (a> b), it is possible to expect attenuation of a wide range of frequencies around the reduction frequency.

As shown in FIG. 6, the frequency absorbed in the space 10 does not change, but the sound pressure of the frequency emphasized in accordance with the engine speed follows. Therefore, when tuning is performed in accordance with the frequency of a specific operating state, the reduction effect (arrows c and d) appears periodically with respect to the engine speed.

As shown in FIG. 1, each damping plate 9 is provided with one intake hole 9a, and the shape and size of the hole are generated from a cam sprocket, a crankshaft sprocket, a chain adjuster, a chain, and the like. The shape should be optimal for the frequency of vibrations and sounds that occur.

With the above configuration, vibration and noise generated in the chain cover 1 can be attenuated or absorbed in the space surrounded by the closing rib 8 and the damping plate 9 on the back surface of the chain cover. Noise reduction becomes feasible. In order to prevent the surrounding oil from accumulating in the space and the space volume from changing and the specific frequency from changing, the opening position is preferably set to the lowest position with respect to the space. In addition to the chain cover, the present invention can be applied to a timing belt cover, a cylinder head cover, an oil pan, and a transmission bell housing. In addition, it is effective that the space portion 10 is installed at a position where the ribs 7 are used to avoid interference with the auxiliary equipment and are likely to be antinodes of the membrane vibration. In addition, it is efficient to attach the two adjacent chambers so that both chambers are covered by one attenuation plate.

[0021]

As described above, according to the first aspect of the present invention, the space is formed in the cover plate and the intake hole is formed toward the inner closed space, so that vibration and noise are reduced at this location. And vibration of a specific frequency,
The effect of reducing noise can be obtained. Further, the rigidity of the cover plate is improved by forming the cover plate and the damping plate in a two-layer structure, and the cost can be suppressed because the structure is simple. According to the invention of claim 2, the reduction effect is doubled by arranging a plurality of enclosed spaces. According to the third aspect of the present invention, a plurality of spaces are provided with specific resonance frequencies, so that the reduction frequency has a width, and the reduction effect is obtained in a wide area. According to the fourth aspect of the present invention, the effect of reducing the resonance frequency in each space is doubled. According to the fifth aspect of the invention, the annular convex portion is formed on the back side surface of the chain cover, and the perforated attenuation plate is joined so as to cover the annular convex portion, so that the specific frequency can be attenuated at this location. The reduction effect can be achieved with a minimum increase in rigidity or weight.

[Brief description of the drawings]

FIG. 1 is a rear plan view of a chain cover according to an embodiment of the present invention.

FIG. 2 is a sectional view of the chain cover shown in FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is an enlarged view of a main part of FIG. 1;

FIG. 5 is a graph showing noise and vibration characteristics with respect to a reduced frequency of an air chamber provided in a chain cover.

6 is a graph showing how the noise and vibration of the chain cover shown in FIG. 1 are attenuated by the engine speed.

7 shows a cross-sectional shape of a conventional chain cover, and is a cross-sectional view taken along the line AA of FIG. 8 (b).

FIG. 8 is a plan view showing a front side (a) and a back side (b) of a conventional chain cover.

[Explanation of symbols]

 Reference Signs List 1 cover plate 2 cylinder block 7 rib 8 closing rib 9 damping plate 9a intake hole 10 space

Claims (5)

[Claims] 1. A cover plate in which a device that is a source of vibration and noise is covered by forming a closed space inside.
A plurality of ribs are formed on the cover plate, and among the plurality of ribs, a damping plate is coupled in a lid shape to ribs that are annularly connected to form a space, and a partition between the space and the closed space is formed. A cover plate structure for an internal combustion engine, wherein an intake hole is provided. 2. A cover plate structure for an internal combustion engine according to claim 1, wherein a plurality of spaces surrounded by a plurality of ribs and a damping plate are arranged. 3. The cover plate structure for an internal combustion engine according to claim 1, wherein a specific resonance frequency is provided by the enclosed space and the hole of the damping plate. 4. The cover plate structure for an internal combustion engine according to claim 1, wherein different resonance frequencies are provided for a plurality of enclosed spaces, respectively. 5. The reinforcing ribs on the back side of the chain cover are extended lengthwise and crosswise, an annular convex portion is formed by the reinforcing rib, and a perforated damping plate is joined so as to cover the annular convex portion. Cover plate structure of an internal combustion engine.