JPH07293327A - Vibration damping structure for oil pan of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve vibration damping effect of a double structure oil pan and smoothly discharge lubricating oil in a gap. CONSTITUTION:An oil pan 1 made of a steel plate has a drain cock 11 on a deep bottom 1a at its front end. An inner pan 3 is slightly smaller than the oil pap l and has a shape similar to the oil pan 1 so as to form a thin oil layer 4 between the inner pan 3 and the oil pan 1. The inner pan 3 is not fixed to the oil pan 1, but sunk in oil by its own weight. Three beads 13 are formed in a longitudinal direction so as to improve rigidity of a bottom wall 3c of the inner pan 3. A transverse bead 14 is formed for communicating the beads 13 with each other. An end of the transverse bead 14 reaches an opening 12 corresponding to the drain cock 11. The beads 13 and 14 show projected conditions toward the inside of the inner pan 3.

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 typified by automobile internal combustion engines, an oil pan having a shallow bottom portion and a deep bottom portion is attached to the lower surface of a cylinder block. It is structured so that it is sucked up by and pumped to each part. 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. In particular, a large radiant sound is likely to be generated in the shallow bottom portion as compared with the deep bottom portion where a large amount of lubricating oil is always present.

Therefore, it has been conventionally disclosed in JP-A-58-130.
As disclosed in Japanese Patent Publication No. 010, etc., the oil pan has a double structure of an outer oil pan and an inner oil pan, and a gap between the oil pan and the oil pan is filled with lubricating oil. A low noise oil pan that suppresses the noise has been proposed. In this case, when the outer oil pan vibrates, the oil layer formed between the outer oil pan and the inner oil pan expands and contracts, and the vibration energy is attenuated by the viscous action of the lubricating oil.

[0004]

However, in the above-mentioned conventional structure, since the bottom surface and the side surface of the inner oil pan are substantially flat, the dynamic rigidity thereof is low. Therefore, even if the outer oil pan vibrates, the deformation of the oil layer accompanying this is small,
The damping effect cannot be fully exerted. Therefore, there is a problem that the noise reduction effect is lower than the weight increase due to the addition of the inner oil pan.

Further, in order to enhance the energy damping action, it is better to reduce the thickness of the oil layer. Therefore, if the gap between the inner oil pan and the outer oil pan is set small,
It becomes difficult to discharge the lubricating oil in the gap when replacing the lubricating oil.
In addition, the lubricating oil in the gap is retained for a long period of time, and sludge easily accumulates.

[0006]

Therefore, the present invention provides an inner pan having a wall surface along the oil pan inner wall surface so as to form a slight gap between the oil pan inner wall surface including at least a part of the bottom surface. It is arranged inside the oil pan, a thin oil layer is formed between the inner pan wall surface and the oil pan inner wall surface, and a bead convex toward the inner side of the oil pan is formed on the inner pan. There is.

Further, in the invention of claim 2, the bead comprises:
It is characterized in that it is formed along the crankshaft direction of the internal combustion engine.

Further, in the third aspect of the invention, a plurality of vertical beads formed on the bottom surface of the inner pan along the crankshaft direction of the internal combustion engine are provided in the lateral direction along a direction substantially orthogonal to the crankshaft. And the lateral bead was connected to the opening corresponding to the drain cock.

Further, in the invention of claim 4, the inner pan is settled in the oil of the oil pan in a non-fixed state.

[0010]

A thin oil layer is formed between the oil pan and the inner pan. When the oil pan vibrates in this state, the oil layer expands and contracts with a minute change in the distance between the two. That is, the lubricating oil tends to flow along the wall surface in the thin oil layer, and the viscosity of the lubricating oil provides the energy damping action. This suppresses the vibration of the oil pan. At this time, the rigidity of the inner pan is enhanced by the formation of the beads, so that the oil layer is surely deformed and a large damping action is obtained. Particularly, by providing the beads along the crankshaft direction as in the second aspect, the rigidity of the elongated inner pan along the crankshaft direction is more effectively improved. Here, since the bead is convex toward the inside of the oil pan, the gap between the oil pan and the inner pan, which is an oil layer, does not expand.

Further, when the lubricating oil is discharged, the bead functions as a discharging passage to smooth the flow of the lubricating oil. In particular, according to the third aspect, the plurality of beads merge to reach the drain cock, and the lubricating oil is smoothly discharged. Also,
Lubricating oil flows through the beads even during engine operation, suppressing sludge generation.

Further, when the inner pan is not fixed as in claim 4, the oil layer can be made sufficiently thin without being influenced by the assembling accuracy of the inner pan and the oil pan, the processing accuracy, etc. Pressurization of the oil layer provides a greater vibration damping effect.

[0013]

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 4 show a first embodiment of the present invention. The oil pan 1 is formed by press-forming a steel plate, and the portion near the front end of the engine is a substantially rectangular deep bottom portion 1a, and the remaining portion is a shallow bottom portion 1b. The bottom surfaces of the deep bottom portion 1a and the shallow bottom portion 1b are substantially flat surfaces. A flange portion 2 is formed on the outer peripheral edge portion, and the flange portion 2 is bolted to the lower edge of the cylinder block (not shown).

The oil pan 1 contains an inner pan 3 formed by press-forming a steel plate. Like the oil pan 1, the inner pan 3 has a deep bottom portion 3a and a shallow bottom portion 3b, and has a shape along the inner wall surface of the oil pan 1 as a whole. That is, the oil pan 1 has a bottom wall 3c and a side wall 3d that are substantially similar to each other so that a slight gap may occur between the respective wall surfaces when fitted in the oil pan 1. The size is slightly smaller than the shape. The inner pan 3 is not particularly fixed to the oil pan 1, and when it is settled in the oil in the oil pan 1, a thin oil layer 4 is defined between the bottom surface and the side wall surface of the oil pan 1. It has become. The gap between the side wall surface of the oil pan 1 and the side wall 3d of the inner pan 3 is set to, for example, about 2 to 3 mm in order to ensure smooth inflow of lubricating oil.

As shown in FIG. 1, a drain cock 11 is detachably screwed to one side of the bottom of the deep bottom 1a of the oil pan 1. An opening 12 for discharging the lubricating oil is formed in a portion of the inner pan 3 corresponding to the drain cock 11 so as not to interfere with the drain cock 11.

Further, the bottom wall 3c of the inner pan 3 has:
As shown in FIG. 4, a plurality of, for example, three vertical beads 13 are formed along the longitudinal direction, that is, the crankshaft direction of the engine, and one lateral bead 14 is formed along a direction substantially orthogonal thereto. . The bead 13 in the vertical direction is continuous with the deep bottom portion 1a and the shallow bottom portion 1b and is formed in a substantially linear shape in a plan view. The horizontal bead 14 intersects three vertical beads 13 at the bottom of the deep bottom 1a to connect them to each other, and one end 14a of the bead 14 has an opening 12 for the drain cock 11. It is connected to the. Here, each of the beads 13 and 14 has a semicircular or U-shaped cross section that is convex toward the inner side of the inner pan 3.
The vertical beads 13 and the horizontal beads 14 are formed at the same height.

A baffle plate 5 is fixed to the opening of the upper surface of the oil pan 1 by welding so as to suppress the swing of the oil surface. Below the baffle plate 5, that is, between the bottom surface of the oil pan 1 and the baffle plate 5. Inner bread 3 is housed in. As a result, excessive movement of the inner pan 3 is restricted, and there is no risk of interfering with the connecting rod 6 or the crankshaft 7 (see FIG. 2), for example. The baffle plate 5 is provided with a plurality of oil drop holes (not shown) for letting the lubricating oil dropped on the upper surface thereof flow downward, but a part of the oil drop holes is provided near the side edge of the oil pan 1. Thus, the lubricating oil is dropped into the oil layer 4 between the side wall surface of the oil pan 1 and the side wall 3d of the inner pan 3. Therefore, the oil level 15 of the oil pan 1 during engine operation is lower than the upper edge of the inner pan 3 as shown in the figure, but the lubricating oil is reliably retained in the oil layer 4.

Next, the operation of the above embodiment will be described. In the configuration in which the inner pan 3 is disposed in the oil pan 1 via the thin oil layer 4 as described above, when the bottom wall and the side wall of the oil pan 1 vibrate due to the vibration input from the cylinder block side, A slight change in the distance from the inner pan 3 occurs, and the oil layer 4 expands and contracts accordingly. That is, the lubricating oil in the oil layer 4 tries 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 viscosity of the lubricating oil. Therefore, the vibration that actually occurs is significantly suppressed, and the radiated sound is reduced.
In particular, the dynamic rigidity of the inner pan 3, which is one surface of the oil layer 4, is ensured to be high by the beads 13 and 14, so that the expansion and contraction deformation of the oil layer 4 due to the vibration of the oil pan 1, that is, the minute movement of the lubricating oil is prevented. It is surely generated, and the vibration damping action utilizing the viscosity of the lubricating oil is surely obtained. FIG. 5 shows the relationship between the rigidity of the inner pan 3 and the radiated sound. As shown, the radiated sound can be reduced as the rigidity of the inner pan 3 increases. It should be noted that this damping effect is effective in a wide frequency range as with the damping element in a general vibration model, and the radiated sound can be reduced as a whole.

On the other hand, regarding the thickness of the oil layer 4, as shown in FIG. 6, the thinner the oil layer 4 is, the more the radiated sound can be reduced. As described above, the beads 13 and 14 are moved to the inner side of the inner pan 3. By forming a convex toward the bead 1
The beads 13 and 14 can be formed without thickening the oil layer 4 except the portions 3 and 14. That is, bead 1
If 3 and 14 are convex toward the outside of the inner pan 3, as shown in FIG. 7A, the thickness t1 of the oil layer 4 becomes thicker, but convex toward the inside of the inner pan 3. Thereby, as shown in (b), the thickness t2 of the oil layer 4 can be reduced regardless of the height of the beads 13 and 14. Therefore, the cross-sectional shapes of the beads 13 and 14 necessary for ensuring the rigidity can be secured without any restrictions. Note that FIG. 6 shows the influence of the thickness when the inner pan 3 is in a non-fixed state.

Further, in the above embodiment, since the inner pan 3 is settled in the oil in a non-fixed state, the oil layer is not affected by welding accuracy and the like as compared with the case where the inner pan 3 is welded to the oil pan 1. The thickness of 4 can be made sufficiently thin. Moreover, the bottom of the oil pan 1 and the bottom wall 3c of the inner pan 3
As for the oil layer 4 between and, the inner pan 3 is strongly pressed against the inner wall surface of the oil pan 1 due to the self-weight of the inner pan 3, and the oil flows in the thin oil layer 4 generated thereby, so that the energy damping action is exerted. Can be obtained even more. FIG. 8 is a comparison of the vibration levels when the inner pan 3 is fixed and when it is not fixed. Even if the gap on the bottom surface is the same, the vibration is suppressed more by the non-fixed settling configuration. It

Further, in the above structure, even if the bottom surface of the inner pan 3 is in close contact with the bottom surface of the oil pan 1, the beads 13 and 14 serve as oil passages so that the lubricating oil in the bottom oil layer 4 always flows. Therefore, generation of sludge due to retention of lubricating oil is suppressed. And when replacing the lubricating oil,
In particular, at the time of discharging, the lubricating oil in the oil layer 4 is promptly guided to the drain cock 11 portion by the beads 13 and 14 continuous in the vertical and horizontal directions serving as passages, and is easily discharged. Similarly, when injecting the lubricating oil, the lubricating oil can be reliably introduced into the oil layer 4 via the beads 13 and 14.

Next, FIG. 9 shows a second embodiment of the present invention. In this embodiment, the inner pan 3 is spot-welded to the oil pan 1 at a plurality of welding points 16. That is, the inner pan 3 is fixed to the oil pan 1 in a state in which the gaps forming the oil layer 4 are maintained in the respective portions. According to this embodiment, compared with the first embodiment described above, there is a slight disadvantage in terms of vibration reduction, but interference with the connecting rod 6 or the like can be reliably avoided.

[0024]

As is apparent from the above description, according to the oil pan damping structure for the internal combustion engine of the present invention, the rigidity of the inner pan is increased by the formation of the beads, so that the inner pan is formed between the oil pan and the oil pan. The oil layer that will be deformed will surely be deformed with the vibration of the oil pan, and the vibration damping effect due to the viscosity of the lubricating oil in the oil layer will be highly obtained.

In particular, if the beads are formed along the crankshaft direction as claimed in claim 2, the rigidity of the bottom surface of the elongated inner pan can be effectively increased, and the radiated sound at the bottom portion of the oil pan can be significantly reduced. .

Since the bead also functions as an oil passage,
The lubricating oil in the oil layer can be easily discharged. In particular, by extending the beads that are continuous in the vertical and horizontal directions to the vicinity of the drain cock, the lubricating oil in the oil layer can be smoothly guided to the drain cock portion.

When the inner pan is not fixed to the oil pan but is allowed to settle in the oil as in claim 4, the structure is simpler and less expensive than the case where the inner pan is fixed. In addition to being configured, a sufficiently thin oil layer can be stably secured, and a good vibration damping action can be obtained. Moreover, the inner pan bottom surface is pressed against the oil pan bottom surface by its own weight, so that a larger damping action is obtained.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view of the first embodiment.

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

FIG. 4 is a plan view of the inner pan.

FIG. 5 is a characteristic diagram showing a change in radiated sound depending on the rigidity of the inner pan.

FIG. 6 is a characteristic diagram showing changes in radiated sound depending on the thickness of an oil layer.

FIG. 7 is an explanatory view showing a state (a) of the oil layer when the bead is convex outward and a state (b) of the oil layer when the bead is convex inward.

FIG. 8 is a characteristic diagram showing a relationship between a gap and a vibration level at a bottom surface portion.

FIG. 9 is a vertical sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Oil pan 3 ... Inner pan 4 ... Oil layer 5 ... Baffle plate 11 ... Drain cock 13 ... Vertical bead 14 ... Horizontal bead

Claims (4)

[Claims] 1. An inner pan having a wall surface along the inner wall surface of the oil pan so as to form a slight gap with the inner wall surface of the oil pan including at least a part of the bottom surface is arranged inside the oil pan, An oil pan damping structure for an internal combustion engine, characterized in that a thin oil layer is formed between an inner pan wall surface and an oil pan inner wall surface, and a bead convex toward the inside of the oil pan is formed on the inner pan. 2. The oil pan damping structure for an internal combustion engine according to claim 1, wherein the bead is formed along the crankshaft direction of the internal combustion engine. 3. A plurality of vertical beads formed along the crankshaft direction of the internal combustion engine on the bottom surface of the inner pan,
3. The internal combustion engine according to claim 2, wherein the lateral beads are connected by a lateral bead along a direction substantially orthogonal to the crankshaft, and the lateral bead is connected to an opening corresponding to the drain cock. Oil pan damping structure. 4. The inner pan is settled in the oil of an oil pan in a non-fixed state.
An oil pan damping structure for an internal combustion engine according to any one of 1.