JP2005255071A - Engine undercover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress noise outside a vehicle caused by an engine as a sound source by blocking the whole downside of the engine with an engine undercover, without shortening the minimum road clearance of a vehicle and without damaging the maintainability of the engine in change of the oil. <P>SOLUTION: The engine undercover 10 is disposed under the engine 4, and covers the whole lower surface of the engine. The engine undercover has an opening 15 into which the deepest section 9 of an oil pan 8 mounted to the lower surface of the engine body 4a can be inserted, and the opening except for a predetermined clearance 16 formed between the opening edge of the opening and the oil pan deepest section is blocked with the deepest section of the oil pan. The oil pan deepest section projects downward from the opening. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine under cover, and more particularly, to an engine under cover that is arranged on the lower side of an engine mounted on a vehicle and configured to cover the entire lower surface of the engine.

  In general, in a vehicle such as an automobile equipped with an internal combustion engine, driving force for traveling the vehicle is obtained by explosion combustion of an air-fuel mixture in a combustion chamber. Noises such as mixed-air explosion sounds and intake / exhaust sounds generated during engine operation propagate outside the vehicle and are perceived as outside noise using the engine as a sound source, so the engine is recognized as the main sound source of outside noise.

  From the viewpoint of environmental protection and the like, in recent years, there has been an increasing demand for a vehicle equipped with such an engine to reduce vehicle noise and obtain quietness. In addition to measures to reduce the noise level of the sound source itself by measures such as soundproofing or vibration suppression for the engine itself, noise from outside the vehicle can be reduced by solid sound and airborne sound due to sound insulation measures or insulation measures in the engine sound propagation process. It is thought that measures to block out are effective.

  Here, in many vehicles, an engine under cover is disposed below the engine. FIG. 9 is a side view and a cross-sectional view illustrating a vehicle including an engine undercover. The vehicle 1 is shown as a small or medium truck with a cab 2 and a chassis 3.

  The engine 4 is mounted on the lower part of the cab 2, and the driving force of the engine 4 is transmitted to the rear wheels 6 or the front wheels 5 and the rear wheels 6. An engine under cover C is disposed below the engine 4. The engine under cover C is fixed to the left and right side frames 7 and extends between the left and right side frames 7 so as to cover the entire engine including the oil pan from below.

  In general, the lowermost part of the vehicle engine is formed by an oil pan 8. The lowermost surface of the oil pan 8 is disposed at a height h1 with respect to the traveling roadbed G. On the other hand, the engine under cover C disposed so as to conceal the entire lower surface of the engine 4 is disposed at a height h2 (h2 <h1) with respect to the traveling roadbed G.

  This type of engine undercover improves the aerodynamic characteristics by smoothing the air flow under the vehicle body, and protects the engine from scattered objects (pebbles, etc.) that the wheels bounce off the road surface during braking. This is the main purpose (Japanese Patent Laid-Open No. 2001-233252). In such an engine undercover, an engine undercover manufactured from a material having high sound insulation performance or an engine undercover using a sound absorbing wall structure is known (Patent No. 3296928) to reduce outside noise. .

In addition, for vehicles with a configuration in which vertical sound insulation plates are arranged on both sides of the engine instead of the engine under cover to prevent deterioration of engine cooling performance due to the installation of the engine under cover and deterioration of maintainability of the lower part of the engine. A soundproofing device is known (Japanese Patent No. 3129203). This vehicle soundproofing device is intended to prevent engine noise from propagating outside the vehicle without concealing the lower part of the engine with an engine undercover, and the sound insulation plate includes a sound absorbing member at the peripheral edge.
JP 2001-233252 A Japanese Patent No. 3296928 Japanese Patent No. 3129203

  Installation of the engine under cover is an effective means from the viewpoint of improving aerodynamic characteristics, protecting the engine, and reducing noise outside the vehicle, but on the other hand, with the conventional engine under cover intended for sound insulation of engine noise, The engine under cover is designed so as to conceal the entire lower surface of the engine from the viewpoint of suppressing outside noise. For this reason, the ground clearance (FIG. 9, h2) of the engine undercover is smaller than the ground clearance (FIG. 9, h1) of the lowermost surface of the oil pan. Therefore, in a vehicle without an engine under cover, the bottom surface of the oil pan is a factor that defines the minimum ground clearance of the vehicle, whereas in a vehicle with an engine under cover, the engine under cover has a minimum vehicle height. It becomes a factor that regulates the ground clearance. That is, in a vehicle equipped with an engine under cover, the minimum ground clearance is shortened compared to a vehicle not equipped with an engine under cover, resulting in a disadvantage in vehicle design.

  Further, the engine under cover that covers the entire lower surface of the engine makes it difficult to inspect and attach / detach the drain bolt disposed at the deepest part of the oil pan, so that the maintainability during oil replacement deteriorates.

  The present invention has been made in view of such a problem, and the object of the present invention is to reduce the minimum ground clearance of the vehicle and to reduce the engine undercover without impairing maintainability during oil change. Therefore, it is an object of the present invention to provide an engine undercover that can shield the outside of the engine as a whole and suppress external noise using the engine as a sound source.

In order to achieve the above object, the present invention provides an engine undercover that is arranged under an engine mounted on a vehicle and configured to cover the entire lower surface of the engine.
The oil pan is provided with an opening into which the deepest part of the oil pan mounted on the lower surface of the engine body can be inserted, and the opening is formed in the oil pan except for a predetermined clearance formed between the opening edge of the opening and the deepest part of the oil pan. Provided is an engine undercover characterized in that it is closed by the deepest part and the deepest part of the oil pan protrudes downward from the opening.

  According to the above configuration of the present invention, the opening into which the deepest part of the oil pan can be inserted is formed in the engine under cover, and the opening is substantially closed by the oil pan. The ratio of the acoustic energy radiated from the lower surface of the oil pan when the engine is operated is very small relative to the acoustic energy radiated by the entire engine, and the ratio of the acoustic energy radiated from the deepest part of the oil pan is even smaller. That is, a predetermined clearance is secured between the opening edge of the opening and the deepest part of the oil pan in order to avoid physical mutual interference, stress transmission, vibration transmission, heat transmission, etc. during engine operation. The acoustic energy of the engine that leaks to the outside through this clearance is extremely small compared to the acoustic energy radiated by the entire engine, and the acoustic energy radiated by the deepest part of the oil pan exposed on the lower side of the engine undercover is also Compared to the acoustic energy radiated as a whole, it is extremely small. Therefore, the engine undercover exhibits almost the same engine noise prevention effect regardless of the presence or absence of the opening.

  In a vehicle employing such an engine under cover, the bottom surface of the deepest part of the oil pan that protrudes downward from the opening is located below the engine under cover. Therefore, the deepest part of the oil pan is a factor that defines the minimum ground clearance of the vehicle. For this reason, the disadvantage that the minimum ground clearance of the vehicle is determined by the ground clearance of the engine undercover does not occur, and the disadvantages in vehicle design associated with the installation of the engine undercover are eliminated. In addition, since the deepest part of the oil pan is exposed on the lower side of the engine under cover, the drain bolt inspection and attachment / detachment operations can be easily performed.

  According to the engine under cover of the present invention, the engine under cover totally shields the lower side of the engine without reducing the minimum ground clearance of the vehicle and without impairing maintainability when changing oil. Noise outside the vehicle as a sound source can be suppressed.

  In a preferred embodiment of the present invention, the engine undercover includes a sealing material capable of closing the clearance. A polymer material having a sound insulation performance capable of effectively blocking air-propagating sound passing through the clearance, for example, a rubber sheet or an elastomer sheet having a predetermined thickness, can be preferably used as the sealing material. Desirably, a sealing material is provided with the deformability and elasticity which can prevent that stress transmission and vibration transmission arise between the said opening edge and an oil pan at the time of engine operation.

  As a modified example, a sound absorbing material or a sound absorbing mechanism capable of preventing air-borne sound from passing through the clearance is attached to or disposed on the opening edge, or a sound insulating mechanism for preventing the air-borne sound from passing through the clearance is provided in the oil pan deepest. It is also possible to form in the part and / or the opening edge.

  Preferably, the oil pan is made of a damping steel plate. As a modified example, a general-purpose metal oil pan may be coated or coated with a coating-type damping material or damping coating. This type of damping material converts vibration energy into heat energy by internal friction, and exhibits an action of attenuating vibration and noise of the sound source. In an engine equipped with an oil pan made of damping steel plate or an oil pan coated or coated with damping material, the acoustic energy emitted by the oil pan is reduced to less than 10% of the total acoustic energy emitted by the engine. . The acoustic energy emitted by the deepest part of the oil pan is even smaller. For this reason, in an engine equipped with such an oil pan, the acoustic energy passing through the clearance using the oil pan as a sound source is extremely small, and the acoustic energy radiated from the portion exposed from the opening (the deepest portion of the oil pan) is also Very small. Therefore, when the oil pan is manufactured from a damping steel plate, or the coating type damping material or the coating material is coated or applied to the oil pan, the sound insulation performance of the engine undercover accompanying the formation of the opening is reduced. The engine undercover exhibits substantially the same sound insulation effect as a conventional engine undercover having no opening.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 and 2 are a side view and a cross-sectional view schematically showing a vehicle provided with an engine undercover according to an embodiment of the present invention.

  In this embodiment, the vehicle 1 has a cab 2 and a chassis 3, 4 × 2 (front 1 axis / rear 1 axis / 1 axis drive) or 4 × 4 (front 1 axis / rear 1 axis / 2 axis). It is illustrated as a small or medium truck with a drive system. An engine 4 is mounted below the cab 2, and the driving force of the engine 4 is transmitted to the rear wheel 6 or the front wheel 5 and the rear wheel 6 via an axle (not shown).

  A metal engine under cover 10 is disposed below the engine 4. The engine under cover 10 is fixed to the left and right side frames 7, extends between the side frames 7, and shields the lower region of the engine 4 as a whole.

  3A is a plan view showing the configuration of the engine undercover 10, and FIGS. 3B, 3C, and 3D are cross-sectional views taken along the line I-I showing the structure of the engine undercover 10. FIG. It is the II-II sectional view and III-III sectional view. FIG. 3E is an enlarged cross-sectional view showing the structure around the opening edge of the opening 15.

  The engine under cover 10 includes left and right edges 11 that can be fixed to the side frame 7. The bent portion 12 is bent downward from the edge portion 11 at a predetermined inclination angle, and the shielding plate 13 extends substantially horizontally between the left and right bent portions 12. The left and right boundary portions of the shielding plate 13 are connected to the lower end portion of the bent portion 12. The engine undercover 10 including the edge portion 11, the bent portion 12, and the shielding plate 13 has a shape that is symmetrical with respect to the central axis of the engine 4 in a plan view, and includes a shape / dimension that includes the entire outline of the engine 4. Have

  An oil pan 8 of the engine 4 is disposed above the shielding plate 13 as shown in FIGS. 3 (B) and 3 (D). The oil pan 8 assembled to the engine body 4 a includes a deepest portion 9 in which engine oil stays, and the bottom surface of the oil pan 8 bulges downward in the deepest portion 9. An oil strainer (not shown) is disposed inside the deepest portion 9 (inside the engine region), and a drain bolt 9b for engine oil replacement is disposed on the lower surface (bottom surface) 9a of the deepest portion 9.

  An opening 15 that can accommodate the deepest portion 9 of the oil pan 8 is formed at the center in the width direction of the shielding plate 13. In the present embodiment, the opening 15 has a rectangular shape or a rectangular outline, and the opening dimension (width dimension W, depth dimension D) of the opening part 15 is set to a value slightly larger than the cross-sectional dimension of the deepest part 9. Is done. Between the opening edge of the opening 15 and the outer surface of the oil pan 8, mechanical interference, stress transmission, vibration transmission, heat transmission, etc. of the engine 4 and the shielding plate 13 that may occur during operation of the engine 4 should be avoided. A clearance (gap) 16 having a predetermined dimension is formed. The clearance 16 separates the engine 4 and the shielding plate 13 and effectively prevents stress transmission and vibration transmission between them. Desirably, the dimension of the clearance 16 is limited to a minimum value as long as the engine 4 and the shielding plate 13 can be physically separated from each other in order to prevent leakage of air-borne sound using the engine 4 as a sound source.

  The deepest portion 9 of the oil pan 8 penetrates the opening 15 and slightly protrudes to the lower side of the engine undercover 10. Accordingly, the lower surface (ground height h2) of the shielding plate 13 is the bottom level (ground height) of the deepest portion 9. It is arranged at a position higher than h1). Therefore, the minimum ground clearance around the engine is defined by the bottom surface 9 a of the deepest portion 9 without being shortened by the installation of the engine under cover 10.

  Preferably, as the oil pan 8, an oil pan made of a vibration-damping steel plate is used. As an action of the damping steel plate, an action of absorbing or reflecting noise and an action of reducing noise by suppressing vibration of a noise generation source are known. Those having superior performance in the latter are mainly employed. As the damping steel plate, for example, a damping steel plate having a structure in which a viscoelastic resin having a thickness of about 40 to 60 μm is sandwiched between two steel plates can be used. In this type of damping steel plate, the viscoelastic resin repeatedly undergoes shear deformation due to bending vibration, and vibration energy is converted into thermal energy. Therefore, resonance or vibration propagation is suppressed, and a desired soundproof effect can be obtained. As a modification, a general-purpose metal oil pan coated or coated with a coating-type damping material or damping coating may be adopted as the oil pan 8.

  FIG. 5 is a pie chart showing the acoustic energy radiation ratio of the engine 4 provided with the oil pan 8 made of damping steel plate. In FIG. 5, the radiated acoustic energy of each surface of the engine 4 is shown as a ratio to the total acoustic radiant energy of the engine 4.

  As shown in FIG. 5, in the engine 4 provided with the oil pan 8 made of damping steel plate, the acoustic radiant energy emitted by the engine 4 is mainly distributed on the side surfaces LH and RH, the front surface FR and the upper surface UP of the engine. The acoustic energy radiated from the bottom surface LW of the engine 4, that is, the bottom surface of the oil pan 8 is only less than 10% of the total acoustic energy, and from the bottom surface 9 a of the oil pan deepest portion 9 that defines the minimum ground height h. The radiated acoustic energy is even smaller.

  6 to 8 are diagrams showing the sound insulation effect of the engine undercover 10. FIG. 6 shows the noise characteristics of the acoustic energy radiated from the lower surface of the engine 4, and FIGS. 7 and 8 show the noise characteristics of the acoustic energy radiated from the right and left surfaces of the engine 4, respectively. In each figure, the noise characteristic of the engine 4 provided with the engine under cover 10 is indicated by a solid line, and the noise characteristic of the engine 4 not provided with the engine under cover 10 is indicated by a broken line as a comparative example.

  6 to 8, the noise characteristics of each surface of the engine 4 are indicated by a frequency (horizontal axis) and a VA (dB) value (vertical axis), and a line parallel to the horizontal axis indicates an absolute value of 5 dB ( It is displayed at intervals of A).

  Each characteristic line means that the higher the VA (dB) value, the more easily the engine 4 is in a state of noise propagation. The difference in the soundproof performance due to the presence or absence of the undercover 10 is the difference between the two characteristic lines. Appears in each figure.

  As shown in FIGS. 6 to 8, the engine under cover 10 is effective not only for preventing the propagation of engine noise to the lower side of the engine 4 but also for preventing the noise propagation to the side of the engine 4. work. Moreover, this noise prevention effect is generally observed in a wide frequency band. That is, the engine undercover 10 exhibits a sound insulation effect effective in preventing engine noise despite the formation of the opening 15.

  4A is a plan view showing an engine undercover according to another embodiment of the present invention, and FIGS. 4B and 4C are sectional views taken along line IV-IV showing the structure of the engine undercover. And FIG. 4D is an enlarged cross-sectional view showing the structure around the opening edge of the opening. In each figure, the same reference numerals are assigned to substantially the same components as those shown in FIG.

  The engine under cover 10 shown in FIG. 4 includes a sealing material 20 that prevents leakage of acoustic energy from the clearance formed around the opening 15. The sealing material 20 is made of, for example, a rubber sheet that can be arranged along the periphery of the opening 15, and closes the clearance over the entire periphery of the opening 15. Such a sealing material 20 is preferably used when the propagation of engine noise from the clearance should be prevented more reliably.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the present invention described in the claims. Is possible.

  For example, the overall shape of the engine undercover, the sound absorption / sound insulation structure of the engine undercover itself, the shape / dimensions of the opening, the clearance dimensions, etc. should be appropriately changed in accordance with the dimensions, shape and characteristics of the engine. Can do.

  Further, the type of damping material, the type of sealing material, and the like can be appropriately changed in design according to the vibration characteristics and noise characteristics of the engine.

  The present invention is preferably applied to an engine undercover for a vehicle engine, particularly an engine undercover to be disposed in a vehicle in which the minimum ground clearance of the vehicle is defined by the lower surface of the engine. According to the engine under cover of the present invention, the minimum ground clearance of the vehicle is not shortened by installing the engine under cover, and there is no disadvantage in vehicle design. Further, according to the engine under cover of the present invention, the deepest part of the oil pan is exposed on the lower side of the engine under cover, and the drain bolt inspection and attachment / detachment operations can be easily performed. In addition, the engine undercover exhibits an engine noise prevention effect substantially equivalent to that of a conventional engine undercover that does not have an opening.

  The engine undercover of the present invention is also manufactured by manufacturing an oil pan with a damping steel plate, or coating the oil pan with a coating type damping material or damping coating, or applying such damping material to the oil pan. By doing so, the noise prevention effect substantially the same as that of a conventional engine undercover having no opening is exhibited. For this reason, considering that the engine noise suppression effect can be obtained more reliably by combining the engine undercover of the present invention with an engine equipped with this type of oil pan, the effects of the present invention (minimum ground clearance and The improvement in maintainability becomes even more remarkable when combined with such an engine.

It is a side view which shows roughly the vehicle provided with the engine undercover which concerns on embodiment of this invention. It is a schematic sectional drawing of the vehicle shown in FIG. 3A is a plan view showing the configuration of the engine undercover, and FIGS. 3B, 3C, and 3D are cross-sectional views taken along the line I-I showing the structure of the engine undercover, II- FIG. 3E is an enlarged cross-sectional view showing the structure around the opening edge of the opening. 4A is a plan view showing an engine undercover according to another embodiment of the present invention, and FIGS. 4B and 4C are sectional views taken along line IV-IV showing the structure of the engine undercover. And FIG. 4D is an enlarged cross-sectional view showing the structure around the opening edge of the opening. It is a pie chart which shows the acoustic energy radiation rate of the engine provided with the oil pan made from a damping steel plate. It is a diagram showing the noise characteristics of the acoustic energy radiated from the lower surface of the engine, the noise characteristics of the engine with the engine under cover are shown by solid lines, and the noise characteristics of the engine without the engine under cover are as a comparative example This is indicated by a broken line. It is a diagram which shows the noise characteristic of the acoustic energy which the right surface of an engine radiates | emits similarly to FIG. It is a diagram which shows the noise characteristic of the acoustic energy which the left surface of an engine radiates | emits similarly to FIG.6 and FIG.7. It is the side view and sectional view which show roughly the whole structure of the vehicle provided with the conventional engine undercover.

Explanation of symbols

4 Engine 4a Engine body 8 Oil pan 9 Oil pan deepest part 9a Bottom surface 9b Drain bolt 10 Engine under cover 11 Edge 12 Bent part 13 Shield plate 15 Opening part 16 Clearance 20 Sealing material h1, h2 Ground height

Claims (6)

In the engine under cover that is arranged under the engine mounted on the vehicle and is configured to cover the entire lower surface of the engine,
The oil pan is provided with an opening into which the deepest part of the oil pan mounted on the lower surface of the engine body can be inserted, and the opening is formed in the oil pan except for a predetermined clearance formed between the opening edge of the opening and the deepest part of the oil pan. An engine undercover characterized in that it is closed by the deepest part and the deepest part of the oil pan protrudes downward from the opening.   The engine undercover according to claim 1, further comprising a sealing material capable of closing the clearance.   The engine undercover according to claim 1, wherein the oil pan is made of a damping steel plate.   The engine undercover according to claim 1, wherein the oil pan is coated with a coating-type damping material or is coated with a damping paint.   The engine undercover according to any one of claims 1 to 4, wherein the acoustic energy emitted by the oil pan is less than 10% of the total acoustic energy emitted by the engine. The engine undercover according to any one of claims 1 to 5, wherein a ground clearance (h1) of the deepest part of the oil pan protruding downward from the opening defines a minimum ground clearance of the vehicle. .

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