Cover member for internal combustion engine

Abstract

The present invention provides a cover member for an internal combustion engine capable of improving the noise reduction performance. The cover member (1) has a plate body (2) formed of resin in a plate shape and having a plurality of fixing portions (21) fixed to a fixing object. The plate body (2) has a thin-walled portion (3) formed at a position adjacent to a node (A) of strain, and the strain is generated by vibration that displaces the plurality of fixing portions (21) in the plate thickness direction with the fixing ends being fixed.

Description

Technical Field

[0001] The present invention relates to a cover member for an internal combustion engine. Background Art

[0002] Conventionally, vibration damping plates installed in automobile engines and the like have been proposed, consisting of multiple stacked steel plates (see, for example, Patent Document 1). The vibration damping plates described in Patent Document 1 dissipate vibration energy through friction between the steel plates during vibration, thereby suppressing radiated noise.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-106809.

[0006] Problems to be solved by the invention

[0007] As a method of consuming vibration energy, there is not only the method of generating friction between components as described in Patent Document 1, but also a method of forming a plate-like component from resin and generating dynamic strain (hereinafter referred to as "strain") inside the component. In this case, the plate-like component is easy to deform, and if the strain increases, the consumption of vibration energy will increase. However, the amplitude of the component itself will increase, which may become the main reason for the generation of sound. On the other hand, when the plate-like component is difficult to deform, although the vibration of the component itself is suppressed, the strain generated is small, and it is difficult to obtain a vibration attenuation effect. Therefore, it is difficult to achieve both the vibration attenuation effect and the suppression of the vibration of the component itself. Summary of the Invention

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a cover member for an internal combustion engine that can improve the noise reduction performance.

[0009] Solutions for solving problems

[0010] In order to solve the above problems, the cover component for an internal combustion engine of the present invention is characterized in that it has a plate body, which is formed into a plate shape by resin and has multiple fixing parts fixed to a fixed object. In the plate body, a thin-walled part is formed at a position adjacent to a node of strain, and the strain is generated by vibration with the multiple fixing parts as fixed ends and displaced along the plate thickness direction.

[0011] This method facilitates deformation of the plate body by utilizing thin-walled sections adjacent to strain nodes (locations where the strain is zero during vibration). This increases the strain, dissipating more vibration energy and facilitating vibration attenuation, thereby enhancing the noise reduction effect. This eliminates the need to thin the entire plate body to increase the strain, suppresses the increase in the vibration amplitude of the cover member itself, and facilitates achieving a more effective noise reduction effect.

[0012] A pair of thin-walled portions may be formed at positions sandwiching the node of strain. According to this embodiment, the amount of strain can be increased on both sides of the node of strain, further improving the noise reduction effect.

[0013] The thin-walled portion can be formed by forming recesses on both sides of the plate body. This approach reduces the depth of each recess, improving workability. Furthermore, it suppresses asymmetry in the plate body caused by the recesses and reduces changes in vibration characteristics caused by the thin-walled portion.

[0014] The thin-walled portion can be formed adjacent to a node of strain generated by the natural vibration of the plate body at 700 to 1300 Hz. This configuration can easily reduce noise radiated from the front cover due to engine sound and vibration, for example, when the cover member is an engine front cover.

[0015] Effects of the Invention

[0016] According to the internal combustion engine cover member of the present invention, the noise reduction performance can be improved by forming the thin-walled portion at a position adjacent to a node of strain. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a perspective view showing a cover member for an internal combustion engine according to an embodiment of the present invention;

[0018] Figure 2 is a cross-sectional view schematically showing a cover member for an internal combustion engine and a graph showing strain distribution according to an embodiment of the present invention;

[0019] Figure 3 is a diagram schematically showing a cross-sectional view and strain distribution of the internal combustion engine cover member of Comparative Example 1;

[0020] Figure 4 is a diagram schematically showing a cross-sectional view and strain distribution of the internal combustion engine cover member of Comparative Example 2;

[0021] Figure 5 Graph showing vibration transmissibility characteristics of the internal combustion engine cover member according to the embodiment of the present invention and the internal combustion engine cover member according to Comparative Example 3;

[0022] Figure 6Graph showing noise characteristics of the internal combustion engine cover member according to the embodiment of the present invention and the internal combustion engine cover member according to Comparative Example 3;

[0023] Figure 7 is a cross-sectional view and a graph schematically showing strain distribution of a cover member for an internal combustion engine according to a modified example of the present invention;

[0024] Figure 8 is a cross-sectional view schematically showing a main portion of a cover member for an internal combustion engine according to another modified example of the present invention;

[0025] Figure 9 is a cross-sectional view schematically showing a main portion of a cover member for an internal combustion engine according to another modified example of the present invention;

[0026] Figure 10 is a cross-sectional view schematically showing a main portion of a cover member for an internal combustion engine according to another modified example of the present invention;

[0027] Figure 11 It is a cross-sectional view schematically showing a main portion of a cover member for an internal combustion engine according to another modified example of the present invention. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 It is a perspective view showing a cover member 1 for an internal combustion engine according to an embodiment of the present invention.

[0029] An internal combustion engine cover member 1 according to an embodiment of the present invention includes a plate body 2 formed from resin into a plate shape and having a plurality of fixing portions 21 for fixing to an object (engine). Thin-walled portions 3 are formed in the plate body 2 adjacent to nodes A that generate strain. This strain is generated by vibration that displaces the fixing portions 21 in the plate thickness direction.

[0030] The cover member 1 is a front cover attached to an engine body, such as a timing chain cover of the engine. In the example shown in the figure, a through hole O for passing a crankshaft is formed in the cover member 1.

[0031] The cover member 1 includes a plate body 2, and the plate body 2 is made of a resin such as PA (polyamide) or PP (polypropylene) in a flat plate shape. The plate body 2 can extend along the plane, or it can have some deflection relative to the plane in a natural state (a state without deformation). This direction perpendicular to the plane is called the "plate thickness direction". A plurality of fixing portions 21 are formed on the plate body 2 along its outer periphery. The fixing portion 21 is formed in the shape of a through hole, and a fixing member such as a screw is inserted therein, through which the plate body 2 is fixed to the fixed object. In addition, the fixing structure of the fixing portion 21 is not limited to this, and various fixing structures can be adopted.

[0032] When the cover member 1 is fixed to a fixed object, when sound is radiated from a sound source such as an engine or when vibration of the engine is transmitted, the cover member 1 vibrates and generates radiated noise. That is, vibration is generated in which each part of the plate body 2 is displaced in the plate thickness direction with the fixing portion 21 as the fixed end. Figure 1 In this example, the outer edge of the plate body 2 serves as a fixed end, and the portion surrounded by this outer edge is displaced. While the vibration mode in this case corresponds to the wavelength of the radiated noise, the following diagrams and explanations illustrate the strain node A and thin-walled portion 3 corresponding to the fundamental vibration. The plate body 2 includes not only thin-walled portions 3 corresponding to the strain node A of the fundamental vibration but also thin-walled portions corresponding to strain nodes generated by other vibration modes (particularly the natural vibration in the 700-1300 Hz frequency range, described later).

[0033] Figure 2 2 is a graph schematically showing a cross-sectional view of the cover member 1 and strain distribution. Figure 2 From top to bottom, the plate body 2 in its natural state, the situation where the plate body 2 performs basic vibration, and the amount of strain at this time are shown in sequence. When the plate body 2 performs basic vibration, the two ends become fixed ends (nodes of vibration), and the central part becomes the antinode of vibration. At this time, a compressive moment (negative strain) is generated near the fixed end, and a tensile moment (positive strain) is generated in the central part, and the amount of strain at the position where they switch is 0 (no strain is generated). That is, the position where no strain occurs like this becomes the node A of strain. The node of strain is the position where the strain amount is 0, which is different from the node of vibration where the displacement amount is 0.

[0034] Figure 2 The cross-sectional view shown in FIG. 2 shows a case where the plate body 2 is cut in a manner passing through the two fixing portions 21 and crossing the node A of strain. Figure 1 As shown, the node A of the strain is arc-shaped, and the cross-sectional view is Figure 2 It appears in two places.

[0035] In the plate body 2, recesses 22 and 23 are formed on both sides at positions adjacent to the node A of strain. The recesses 22 and 23 are arranged on the central side (the side opposite to the fixed end) relative to the node A of strain. The recess 22 is formed by a pair of side surfaces 221 along the plate thickness direction and a bottom surface 222 connecting these surfaces, and has a cross-sectional shape surrounded by three straight lines. The recess 23 also has the same shape as the recess 22. The recesses 22 and 23 are formed as arc-shaped grooves on the inner side of the arc-shaped node A of strain. It should be noted that the recesses 22, 23 and the thin-walled portion 3 described later can be continuous arc-shaped or discontinuous arc-shaped.

[0036] The plate body 2 has a substantially constant thickness except for the portions where recesses 22 and 23 are formed. Consequently, the portion between recesses 22 and 23 (the portion sandwiched by their bottom surfaces) in the plate body 2 has a smaller thickness than the rest of the plate body 2, forming a thin-walled portion 3. Thin-walled portion 3 is formed adjacent to a strain node A. Here, "adjacent location" refers to, for example, a range within 5 mm of a strain node A (e.g., within 2% of the distance between the fixed ends).

[0037] The smaller the thickness of the plate body 2, the easier it is to deform and the larger the strain amount is. Figure 2 As shown in the graph, the amount of strain increases at the position where the thin portion 3 is formed (the position adjacent to the node A of the strain).

[0038] Here, a comparative example in which no thin-walled portion is formed (the entire plate body has a substantially constant plate thickness) will be described. Figure 3 : is a diagram schematically showing a cross-sectional view of the internal combustion engine cover member of Comparative Example 1 and a graph of strain distribution. Figure 3 , for Comparative Example 1 in which the plate body 4 has a large plate thickness, the plate body 4 in a natural state, the state in which the plate body 4 performs basic vibration, and the amount of strain at that time are shown. Figure 4 : is a diagram schematically showing a cross-sectional view of the internal combustion engine cover member of Comparative Example 2 and a graph of strain distribution. Figure 4 , for the cover member of Comparative Example 2 in which the plate body 5 has a smaller plate thickness, the plate body 5 in a natural state, the state in which the plate body 5 performs basic vibration, and the amount of strain at that time are shown.

[0039] In Comparative Example 1, while the amplitude of the plate body 4 can be suppressed, the strain is small, making it difficult to dissipate the vibration energy. On the other hand, in Comparative Example 2, although the strain is large, making it easier to dissipate the vibration energy, the amplitude of the plate body 5 increases, and the vibration of the plate body 5 itself becomes the main cause of the sound.

[0040] Compared to Comparative Examples 1 and 2, the cover member 1 of this embodiment can increase the strain while suppressing the amplitude of the plate body 2. This makes it easier to consume vibration energy and attenuate vibration.

[0041] Figure 5 Graph showing vibration transmissibility characteristics of the cover member 1 and the internal combustion engine cover member of Comparative Example 3. Figure 5 The graph shows the vibration transmissibility (amplitude) characteristics of the cover member 1 of the present embodiment and the cover member of Comparative Example 3. The cover member of Comparative Example 3 does not have a thin-walled portion and is identical to the cover member 1 of the present embodiment in all other respects (plate thickness, etc.). It can be seen that the amplitude of the cover member 1 of the present embodiment is reduced, particularly at the resonant frequency, compared to the cover member of Comparative Example 3.

[0042] Figure 6 Graph showing noise characteristics of the cover member 1 and the internal combustion engine cover member of Comparative Example 3. Figure 6 The noise characteristics of the cover member 1 of the present embodiment and the cover member of Comparative Example 3 are shown. In the cover member 1 of the present embodiment, since the amplitude is reduced as described above, a noise reduction effect can be achieved compared to the cover member of Comparative Example 3, particularly in the area surrounded by the dotted line (700-1300 Hz).

[0043] As described above, according to the cover member 1 of the embodiment of the present invention, by forming the thin-walled portion 3 at a position adjacent to the node A of strain, the plate body 2 can be easily deformed, thereby increasing the amount of strain. As a result, vibration can be easily attenuated, thereby improving the sound-absorbing effect. In addition, since the thin-walled portion 3 is formed at a position adjacent to the node A of strain, the overall rigidity of the cover member 1 can be suppressed from decreasing compared to the case where it is formed at other positions. Furthermore, since the plate body 2 is formed of resin, the cover member 1 can be made lightweight.

[0044] Furthermore, by forming recesses 22 and 23 on both sides of plate body 2, the depth of each recess 22 and 23 can be reduced, thereby improving workability. Furthermore, the asymmetry of plate body 2 caused by forming recesses 22 and 23 can be suppressed, and changes in vibration characteristics caused by providing thin-walled portion 3 can be suppressed.

[0045] Furthermore, by forming a thin-walled portion at a position adjacent to a node of strain generated by the natural vibration of the plate body 2 at 700 to 1300 Hz, when the cover member 1 is, for example, a front cover of an engine, the sound generated by the engine and the radiated noise from the front cover caused by the vibration of the engine can be easily reduced.

[0046] The present invention is not limited to the above-described embodiment and includes other structures that can achieve the objectives of the present invention. The following modifications are also included in the present invention. For example, in the above-described embodiment of the present invention, the thin-walled portion 3 is formed only on the central portion side relative to the strain node A. However, the thin-walled portion may be formed only on the fixed end side.

[0047] Figure 7It is a cross-sectional view and a graph of strain distribution of a cover member for an internal combustion engine, schematically showing a modified example of the present invention. In this modified example, a pair of thin-walled portions 3 and 3A are formed at the position of the node A where the strain is clamped. In addition, the thin-walled portion 3A can also be formed by recessed portions on both sides in the same manner as the thin-walled portion 3. In addition, for other vibration modes, thin-walled portions can also be formed on both sides of the node where the strain is. According to such a structure, the amount of strain can be increased on both sides of the node A where the strain is, vibration can be easily attenuated, and the silencing effect can be further improved. Furthermore, both positive and negative strains can be increased on both sides of the node A where the strain is, and compared with a structure in which either positive strain or negative strain is generated in two places, the total amount of strain can be easily ensured.

[0048] In addition, although the thin-walled portion 3 is formed by forming the recessed portions 22 and 23 on both sides in the above-mentioned embodiment of the present invention, Figure 8 As shown, the thin portion 3B may be formed by forming the recess 24 only on one side of the plate body 2. In this case, the side where the recess 24 is formed may be the side facing the sound source or the side opposite thereto.

[0049] Furthermore, although in the above-described embodiment of the present invention, the recesses 22 and 23 have a pair of side surfaces and a bottom surface, and have a cross-sectional shape surrounded by three straight lines, the recesses may have other shapes. For example, Figure 9 As shown in FIG. 1 , the thin-walled portion 3C can be formed by forming recesses 25 and 26 having a V-shaped cross-sectional shape (surrounded by two straight lines). Figure 10 As shown, for the recessed portion 22 in the above embodiment, a tapered portion 223 may be provided between the side surface 221 and the bottom surface 222 (the same also applies to the recessed portion 23). Figure 11 As shown in FIG. 1 , the concave portions 27 and 28 can be formed by continuously forming a plurality of concave portions, thereby forming the thin-walled portion 3D. Figure 11 In the example shown, each concave portion is Figure 9 The recessed portions 25 and 26 are similarly formed in a V-shaped cross section.

[0050] Furthermore, thin-walled portions are not limited to being formed by localized recesses. Specifically, thin-walled portions can be formed by forming portions with gradually decreasing wall thickness. Furthermore, thin-walled portions only need to be formed at least adjacent to a strain node. Thin-walled portions can also be formed across strain nodes (i.e., thin-walled portions can be formed at strain nodes).

[0051] Although in the embodiments of the present invention and Figures 7 to 11 In the modification examples, the positions, numbers, shapes, etc. of the thin-walled portions and the recessed portions are exemplified, but these elements may be appropriately combined.

[0052] Furthermore, while the aforementioned embodiment of the present invention forms thin-walled portions adjacent to nodes of strain generated by the natural vibration of the plate body 2 between 700 and 1300 Hz, thin-walled portions may alternatively be formed adjacent to nodes of strain in an appropriate frequency range, depending on the intended use of the cover member. For example, if the cover member is an engine oil pan, the thin-walled portion is preferably formed adjacent to nodes of strain generated by the natural vibration between 300 and 1500 Hz. Furthermore, if the cover member is an engine cylinder head cover, the thin-walled portion is preferably formed adjacent to nodes of strain generated by the natural vibration between 300 and 1500 Hz.

[0053] While the embodiments of the present invention have been described above, the present invention is not limited to the internal combustion engine cover member of the aforementioned embodiments and encompasses all embodiments encompassed by the concepts of the present invention and the scope of the claims. Furthermore, various structures may be appropriately and selectively combined to address the aforementioned issues and achieve at least a portion of the aforementioned effects. For example, in the aforementioned embodiments, the shape, material, configuration, and dimensions of the various components may be appropriately modified based on the specific usage of the present invention.

[0054] Description of Reference Numerals

[0055] 1: Cover component

[0056] 2: Board body

[0057] 21: Fixed part

[0058] 22~28: concave part

[0059] 3, 3A, 3B, 3D: Thin-walled parts

[0060] A: Strain node

Claims

1. A cover member for an internal combustion engine, characterized in that: have: The plate body is formed of resin into a plate shape and has a plurality of fixing portions fixed to a fixing object. The plate body has a thin-walled portion formed at a position adjacent to a node of strain generated by vibration that displaces in the plate thickness direction with the plurality of fixing portions as fixed ends, wherein the node of strain is a position where the amount of strain is zero.

2. The cover member for an internal combustion engine according to claim 1, wherein: A pair of the thin-walled portions are formed at positions sandwiching the node of the strain.

3. The internal combustion engine cover member according to claim 1 or 2, wherein: The thin-walled portion is formed by forming recessed portions on both surfaces of the plate body.

4. The cover member for an internal combustion engine according to claim 1 or 2, wherein: The thin-walled portion is formed at a position adjacent to a node of strain caused by natural vibration of the plate body at 700 to 1300 Hz.

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