JPH07166834A - Oil pan vibration damping structure for internal combustion engine - Google Patents

Abstract

PURPOSE:To attain both lightening of weight and decrease of noise by effectively reducing vibration in a shallow bottom part which occupies a large proportion of emitted noise generated from an oil pan. CONSTITUTION:An oil pan 1 comprises an oil pan main unit 2 and a subtank 3, and a shallow bottom part 2b of the oil pan main unit 2 is placed in a position higher than arm oil level during operation of an engine. An inner pan 7, formed in almost similar shape, is received in an unfixed condition to the inside of the oil pan main unit 2, and wall surfaces of both the oil pan main unit and the inner pan are brought into contact with each other through an oil layer. An oil holding wall 9 is formed along the boundary between deep/ shallow bottom parts 7a, 7b of the inner pan 7, and by weight of lubricating oil accumulated in this wall 9, the inner pan 7 is pressed stronger. In the bottom part center of the oil holding wall 9, a communication hole 10 is opened so as to drop down lubricating oil to a side of a tank part when the engine is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping structure for an oil pan attached to the lower surface of a cylinder block of an internal combustion engine.

[0002]

2. Description of the Related Art In many internal combustion engines represented by automobile internal combustion engines, a lower surface of a cylinder block is provided with a relatively deep oil pan in which lubricating oil is stored and is sucked up by an oil pump to be pumped to respective parts. It is composed. Here, the oil pan generally has a thin structure in which a metal plate is press-molded, and therefore, there is a problem in that the vibration of the film causes the vibration of the engine to generate a relatively large radiated sound.

Therefore, the conventional method has been used.
As disclosed in Japanese Patent No. 41, Japanese Unexamined Patent Publication No. 3-294611, etc., an oil pan has a double structure of an outer plate and an inner plate, and a gap between the two is filled with lubricating oil to flow the oil layer. A low-noise oil pan has been proposed in which vibration is suppressed by the energy damping action of the.

Further, the oil pan of an internal combustion engine is generally
It has a tank part (deep bottom part) for storing the lubricating oil, and the rest is a shallow bottom part, but during engine operation, the oil level drops below the shallow bottom part, so the lubricating oil The radiated sound in the shallow bottom occupies a larger proportion than in the deep bottom where the water is stored. For that reason,
Japanese Patent No. 84309 discloses an oil pan in which a protruding portion is formed at the boundary between the shallow bottom portion and the deep bottom portion, and the lubricating oil is retained in the shallow bottom portion.

[0005]

However, if the oil pan has a double structure over the entire oil pan, that is, both the shallow bottom part and the deep bottom part, as in the former case, as described above, the radiated noise is large. It is not possible to concentrate the vibration on the shallow part. Moreover, in the above-mentioned conventional structure, since the inner plate is fixed to the inside of the outer plate with a slight gap maintained, the oil layer between the inner plate and the outer plate cannot be made so thin. Since the effect of pressing the inner pan composed of the inner plate against the oil layer cannot be utilized, it is not possible to obtain a large energy damping action due to the flow of the lubricating oil in the oil layer. Therefore, there is a problem that the noise reduction effect is lower than the weight increase due to the addition of the inner plate.

Further, in the latter case, in which the lubricating oil is retained in the shallow bottom portion, the radiated sound can be reduced to some extent as compared with the conventional oil pan in which the shallow bottom portion is exposed in the crankcase. However, there is a limit to the vibration damping effect only by holding the lubricating oil, and it was not possible to obtain a sufficient radiation noise reduction effect.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention provides an oil pan which is mounted on the lower surface of a cylinder block of an internal combustion engine and has a tank portion for storing lubricating oil in a part thereof and a shallow bottom portion. An inner pan having a bottom wall and a side wall having a shape along the bottom wall surface and side wall surface of the shallow bottom portion is placed on the shallow bottom portion without being fixed to an oil pan, and the lubricating oil is retained in the inner pan. Another feature is that an oil retaining wall is formed on the inner pan.

According to the second aspect of the invention, a communication hole is formed in the lowermost portion of the oil retaining wall.

[0009]

The lubricating oil flowing down the inner wall surface of the crankcase and the oil droplets scattered in the crankcase are constantly supplied to the upper surface of the shallow bottom. Therefore, the inner wall surface of the oil pan and the outer wall surface of the inner pan are close to each other via the thin oil layer. When the shallow bottom of the oil pan vibrates in this state, the lubricating oil tries to flow along the wall surface in the thin oil layer due to a slight change in the gap between the two, and an energy damping action is obtained. This suppresses the vibration of the shallow bottom of the oil pan. In particular, the lubricating oil that drops from above is held in the inner pan, and the weight of the lubricating oil is added to the inner weight of the inner pan to press the inner pan against the bottom wall of the oil pan. Therefore, the energy damping action of the oil film can be further enhanced. In addition, vibration of the tank portion is suppressed by a large amount of the lubricating oil stored therein.

If a communication hole is provided in the oil retaining wall as in the second aspect, all the lubricating oil in the shallow bottom portion flows into the tank portion when the engine is stopped.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention. The oil pan 1 is composed of an oil pan body 2 formed by press-molding a steel plate, and a sub-tank 3 that is a separate member fixed to the front end portion of the oil pan body 2. In the oil pan body 2, a portion near the front end of the engine is a substantially rectangular deep bottom portion 2a, and the remaining portion is a shallow bottom portion 2b. A substantially rectangular opening 4 is formed on the bottom surface of the deep bottom portion 2a, and the sub tank 3 is fixed to the lower surface of the deep bottom portion 2a by welding. The sub-tank 3 constitutes a tank portion 5 for storing the lubricating oil, and the tank portion 5 communicates with the inside of the oil pan body 2 through the opening 4. The sub-tank 3 has a width larger than the width of the oil pan body 2, as shown in FIG. The bottom wall surface of the shallow bottom portion 2b is a substantially flat surface. Also, the oil pan 1 in detail, the oil pan body 2
A flange portion 6 is formed on the outer peripheral edge portion of the cylinder, and the flange portion 6 is bolted to the lower edge of the cylinder block (not shown).

An inner pan 7 formed by press forming a steel plate is housed inside the oil pan body 2. The inner pan 7 has a deep bottom portion 7 like the oil pan body 2.
It has a and a shallow bottom portion 7b, and has a shape along the inner wall surface of the oil pan body 2 as a whole. That is, the bottom wall and the side wall are shaped along the bottom wall surface and the side wall surface of the oil pan main body 2, and a slight gap may be generated between the respective wall surfaces when the oil pan main body 2 is stacked and arranged. The overall size of the oil pan body 2 is slightly smaller than the inner wall shape of the oil pan body 2. Further, a substantially rectangular opening 8 that matches the opening 4 of the oil pan body 2 is formed on the bottom surface of the deep bottom portion 7a. The side wall of the inner pan 7 is
It is formed lower than the side wall of the oil pan body 2.
The inner pan 7 can also be molded using a hard synthetic resin.

The inner pan 7 is not fixed to the oil pan 1 and is freely movable up and down. A baffle plate (not shown) is attached to the upper surface opening of the oil pan body 2, and the inner pan 7
It regulates excessive movement that interferes with the crankshaft.

The inner bottom 7 has a deep bottom portion 7a and a shallow bottom portion 7a.
An oil retaining wall 9 is fixed along the width direction of the inner pan 7 at the boundary with b. That is, the oil retaining wall 9 is provided at a position along one side edge of the opening 8. The oil retaining wall 9 is formed by press-molding a metal plate and welded to the inner side of the inner pan 7. The oil retaining wall 9 has the same height as the side wall of the inner pan 7 itself and surrounds the shallow bottom 7b together with the side wall. Surrounds. Thereby, the shallow bottom portion 7b of the inner pan 7
The part is constructed as a dish-shaped container.

A communication hole 10 is formed at the center of the lowermost portion of the oil retaining wall 9 for communicating the shallow bottom portion 7b side and the deep bottom portion 7a side. The communication hole 10 is formed in a semicircular shape as shown in FIG. 3 or a rectangular shape elongated to the left and right so that sludge is less likely to accumulate. Further, the opening edge of the communication hole 10 has an R shape toward the downstream side, that is, the deep bottom portion 7a side, as shown in the sectional shape of FIG.
When the inner pan 7 is made of synthetic resin, the oil retaining wall 9 can be integrally formed.

Next, the operation of the above embodiment will be described. The lubricating oil stored in the tank portion 5 formed by the sub tank 3 is sucked up by an oil pump (not shown),
And it is pumped to each part of the engine. Therefore, during engine operation,
As shown in FIG. 5, the oil level L1 in the oil pan 1 is lower than that when the engine is stopped, and the oil pan body 2 is in a high engine speed range.
The height may be lower than the shallow bottom portion 2b. The lubricating oil used in each part is discharged from an oil return hole or the like on the upper surface of the crankcase, flows along the inner wall surface of the crankcase, and flows down to the oil pan 1. Part of it flows down to the upper surface of the inner pan 7, and part of it flows between the inner pan 7 and the oil pan body 2. Therefore, a very thin oil layer is formed between the inner pan 7 and the oil pan body 2 that are pressed against the oil pan body 2 by their own weight.

When the bottom wall of the oil pan body 2, particularly the bottom wall of the shallow bottom portion 2b, vibrates due to the vibration input from the cylinder block side with the oil layer thus formed, the gap between the oil pan body 2 and the inner pan 7 is increased. Of the lubricating oil in the oil layer tends to flow along the two surfaces. Therefore, the vibration energy is converted into the kinetic energy of the lubricating oil, and is attenuated by the friction with each wall surface and the friction between the oils. Therefore, the vibration that actually occurs is significantly suppressed, and the radiated sound is reduced. Since this damping action acts on a plurality of membrane resonances similarly to the damping element in a general vibration model, it has an effect in a wide frequency range, and radiated sound can be reduced as a whole. Since the lubricating oil is stored in the tank portion 5 to a sufficient height during the engine operation, the noise emitted from the tank portion 5 is reduced.

Here, as shown in FIG. 5, on the upper surface of the inner pan 7 which has a container shape by the oil retaining wall 9, the lubricating oil flowing down in the crankcase has a height of L2 which is substantially equal to the oil retaining wall 9 and the like. Retained. Therefore, the weight of the lubricating oil causes the inner pan 7 to be pressed more strongly against the bottom wall surface of the oil pan body 2, and a greater energy damping action can be obtained. The characteristic diagram of FIG. 6 shows the effect of this weight increase. The comparative example indicated by the broken line shows the vibration noise level when only the own weight of the inner pan 7 is used, and the solid line shows the own weight of the inner pan 7. The characteristic of the Example which added the weight of lubricating oil is shown. in this way,
In the present embodiment, the energy damping action can be enhanced by utilizing the lubricating oil without increasing the weight of the inner pan 7 itself.

Therefore, also in the oil pan 1 having the sub-tank 3, the vibration noise can be effectively reduced without an excessively complicated structure and without increasing the weight of the oil pan 1 as a whole.

In the above structure, the oil retaining wall 9 is provided with the communication hole 1
Since 0 is open, all the lubricating oil in the inner pan 7 moves into the tank portion 5 when the engine is stopped. Therefore, when replacing the lubricating oil, the entire lubricating oil in the crankcase can be reliably replaced. In addition, the retention of lubricating oil in the inner pan 7 is prevented, and the accumulation of sludge is suppressed. Moreover, since the communication hole 10 has a semicircular shape, clogging by sludge does not occur, and the opening edge has an R shape, so that sludge is less likely to adhere to the edge.

In the above embodiment, the inner pan 7 is provided over the entire oil pan body 2, that is, both the deep bottom portion 2a and the shallow bottom portion 2b, but the inner pan 7 is formed so as to cover only the shallow bottom portion 2b. However, the oil retaining wall 10 may be formed at the end thereof.

[0023]

As is apparent from the above description, according to the oil pan damping structure for the internal combustion engine of the present invention, the oil layer is formed in the shallow bottom portion where the radiated sound becomes louder than the tank portion. Since the inner pan is brought into close contact with the inner pan, the radiated sound can be effectively reduced. In particular, since the inner pan is housed without being fixed to the oil pan, its structure is simple, and a sufficiently thin oil layer can be stably secured, and a good vibration damping action can be obtained. Moreover, since the weight of the lubricating oil accumulated on the upper surface of the inner pan can be used to strongly press the inner pan to enhance the vibration damping action, it is possible to reduce the noise while suppressing the increase in the weight of the entire oil pan.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a plan view of the entire oil pan of this embodiment.

3 is a cross-sectional view taken along the line BB of FIG.

FIG. 4 is an enlarged cross-sectional view of portion C of FIG.

FIG. 5 is a cross-sectional view showing the position of the oil level during engine operation.

FIG. 6 is a vibration characteristic diagram of the oil pan of this embodiment.

[Explanation of symbols]

 1 ... Oil pan 2 ... Oil pan main body 2b ... Shallow bottom part 4 ... Opening part 5 ... Tank part 7 ... Inner pan 9 ... Oil holding wall 10 ... Communication hole

Claims (2)

[Claims] 1. An oil pan, which is mounted on a lower surface of a cylinder block of an internal combustion engine and has a tank portion for storing lubricating oil in a part thereof, and has a shallow bottom portion, wherein a bottom wall surface and a side wall surface of the shallow bottom portion are provided. An inner pan having a bottom wall and a side wall in a conformal shape is placed on the shallow bottom without being fixed to an oil pan, and an oil retaining wall is formed on the inner pan so as to retain lubricating oil in the inner pan. An oil pan damping structure for an internal combustion engine, which is characterized in that 2. The oil pan damping structure for an internal combustion engine according to claim 1, wherein a communication hole is formed in the lowermost portion of the oil retaining wall.