JP3873897B2 - Oil pan damping structure of internal combustion engine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a vibration damping structure for an oil pan attached to a lower surface of a cylinder block of an internal combustion engine.
[0002]
[Prior 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 the cylinder block. The lubricating oil is stored in the oil pan and sucked up by an oil pump. It is configured to pump. Here, the oil pan generally has a thin structure in which a metal plate is press-molded. Therefore, there is a problem that a relatively large radiated sound is generated due to membrane vibration caused by the excitation input of the engine. In particular, compared to a deep bottom portion where a large amount of lubricating oil is always present, a large radiated sound is likely to be generated at the shallow bottom portion.
[0003]
Therefore, conventionally, as shown in JP-A-58-13010, etc., the oil pan has a double structure of an outer oil pan and an inner oil pan, and the gap between them is filled with lubricating oil, A low-noise oil pan has been proposed in which vibration is suppressed by an energy damping action caused by the deformation of the oil layer. In this case, when the outer oil pan vibrates, the oil layer formed between the inner oil pan and the inner oil pan expands and contracts, and the vibration energy is attenuated by the action of the viscosity of the lubricating oil.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, the bottom and side surfaces of the inner oil pan are substantially flat, so that the dynamic rigidity is low. Therefore, even if the outer oil pan vibrates, there is little deformation of the oil layer that accompanies this, and the vibration damping effect cannot be fully exhibited. Accordingly, there is a problem that the noise reduction effect is low as compared with the weight increase by adding the inner oil pan.
[0005]
In order to enhance the energy damping effect, it is better to reduce the thickness of the oil layer. For this reason, if the gap between the inner oil pan and the outer oil pan is set small, the lubricating oil in the gap is changed when the lubricating oil is replaced. Discharge becomes difficult. In addition, the lubricating oil in the gap is retained for a long time, and sludge is likely to accumulate.
[0006]
[Means for Solving the Problems]
Therefore, in the present invention, an oil pan for storing lubricating oil flowing down is fixed to the lower part of the internal combustion engine,
In'napan having walls along the oil pan wall to produce between gap between the oil pan wall including at least a portion of the bottom surface being disposed on the inner side of the oil pan,
Gap between the In'napan wall and the oil pan wall, have been opened in the space in the oil pan at the periphery of at least the In'napan, by lubricating oil enters, it forms an oil layer,
In the oil pan damping structure of the internal combustion engine that attenuates the energy of the oil pan film vibration by the flow of the lubricating oil generated when the interval between the two wall surfaces changes minutely and the oil layer expands and contracts,
A bead is formed on the bottom surface of the inner pan, and the bead is convex toward the inner pan, and an oil layer having a thickness (t2) smaller than the height (t1) of the bead is formed between the inner pan wall surface and the oil pan. It is characterized by that.
[0007]
According to a second aspect of the present invention, the bead is formed along a crankshaft direction of the internal combustion engine.
[0010]
[Action]
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 an energy damping action is obtained by the viscosity of the lubricating oil. Thereby, the vibration of the oil pan is suppressed. At this time, since the rigidity of the inner pan is enhanced by the formation of the beads, the oil layer is reliably deformed, and a large damping action is obtained. In particular, by providing the bead along the crankshaft direction as in claim 2, the rigidity of the elongated inner pan along the crankshaft direction is further effectively improved. Here, the bead, since become convex toward the In'napan inside, never oil pan as the oil layer, a gap between In'napan widens.
[0011]
Further, when the lubricating oil is discharged, the bead functions as a discharge passage and smoothes the flow of the lubricating oil . Also, during the operation of the engine also in the bead flows through the lubricating oil, suppresses the generation of sludge.
[0013]
【Example】
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0014]
1 to 4 show a first embodiment of the present invention. The oil pan 1 is formed by press-molding a steel plate, the portion near the engine front end 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 at the outer peripheral edge portion, and the flange portion 2 is bolted to the lower edge of a cylinder block (not shown).
[0015]
In the oil pan 1, an inner pan 3 formed by press-molding a steel plate is accommodated. The inner pan 3 has a deep bottom portion 3 a and a shallow bottom portion 3 b, similar to the oil pan 1, 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 substantially similar to the oil pan 1 so that a slight gap can be formed between the wall surfaces in a state where the oil pan 1 is fitted. The dimensions are slightly smaller than the shape. The inner pan 3 is not particularly fixed to the oil pan 1 and settles in the oil in the oil pan 1 so that a thin oil layer 4 is defined between the bottom surface of the oil pan 1 and the side wall surface. It has become. In addition, 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 smoothly flow the lubricating oil.
[0016]
As shown in FIG. 1, a drain cock 11 is detachably screwed to one side portion of the bottom portion 1 a of the oil pan 1. And the opening part 12 for lubricating oil discharge | emission is formed in the site | part corresponding to the said drain cock 11 of the inner pan 3 so that this drain cock 11 may not be interfered.
[0017]
Further, on the bottom wall 3c of the inner pan 3, as shown in FIG. 4, a plurality of, for example, three longitudinal beads 13 along the longitudinal direction, that is, the crankshaft direction of the engine, and 1 along the direction substantially orthogonal thereto. A book transverse bead 14 is formed. The bead 13 in the vertical direction is formed in a substantially straight line in a plane continuously from the deep bottom portion 1a and the shallow bottom portion 1b. The lateral bead 14 intersects the three longitudinal beads 13 at the bottom of the deep bottom portion 1a and connects them to each other, and one end portion 14a thereof is the 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 bead 13 and the horizontal bead 14 are formed at the same height.
[0018]
Further, a baffle plate 5 for suppressing fluctuation of the oil level is fixed to the upper surface opening of the oil pan 1 by welding, and the inner pan 3 is located below the baffle plate 5, that is, between the bottom surface of the oil pan 1. Is housed. Thereby, the excessive movement of the inner pan 3 is restricted, and there is no possibility of interfering with, for example, the connecting rod 6 and the crankshaft 7 (see FIG. 2). The baffle plate 5 is formed with a plurality of oil dropping holes (not shown) through which the lubricating oil dropped on the upper surface flows downward, part of which is provided close to the side edge of the oil pan 1. 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. Accordingly, 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, but the lubricating oil is reliably held in the oil layer 4.
[0019]
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 through the thin oil layer 4 as described above, when the bottom wall or the side wall of the oil pan 1 is vibrated by 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 tends to flow along 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. As a result, vibrations that actually occur are greatly suppressed, and the radiated sound is reduced. In particular, since the dynamic rigidity of the inner pan 3 serving as one surface constituting the oil layer 4 is ensured by the beads 13 and 14, expansion and contraction of the oil layer 4 accompanying the vibration of the oil pan 1, that is, minute movement of the lubricating oil is prevented. It is generated reliably and the vibration damping action utilizing the viscosity of the lubricating oil can be obtained with certainty. 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. In addition, this damping action is effective in a wide frequency range like a damping element in a general vibration model, and can reduce radiated sound as a whole.
[0020]
On the other hand, as shown in FIG. 6, the thinner the oil layer 4, the more the radiated sound can be reduced. However, as described above, the beads 13 and 14 protrude toward the inner pan 3. By doing so, it is possible to form the beads 13 and 14 without increasing the thickness of the oil layer 4 except for the portions of the beads 13 and 14. That is, if the beads 13 and 14 are convex toward the outer side of the inner pan 3, as shown in FIG. 7A, the thickness t1 of the oil layer 4 is increased, but the inner layer 3 is convex toward the inner side. By doing so, as shown in (b), the thickness t2 of the oil layer 4 can be made thin irrespective of the height of the beads 13,14. Therefore, the cross-sectional shape of the beads 13 and 14 necessary for securing rigidity can be secured without any limitation. FIG. 6 shows the influence of the thickness when the inner pan 3 is in an unfixed state.
[0021]
Moreover, in the said Example, since the inner pan 3 has settled in oil in the non-fixed state, compared with the case where the inner pan 3 is welded to the oil pan 1, the thickness of the oil layer 4 is not influenced by welding accuracy etc. The thickness can be made sufficiently thin. Moreover, the oil layer 4 between the bottom surface of the oil pan 1 and the bottom wall 3c of the inner pan 3 is affected by the weight of the inner pan 3, so that the inner pan 3 is strongly pressed against the inner wall surface of the oil pan 1, and the thin oil layer 4 generated thereby. Since oil flows in the chamber, the energy damping effect can be further increased. FIG. 8 shows a comparison of vibration levels when the inner pan 3 is fixed and when it is not fixed. Even if the gap at the bottom surface is the same, vibration is suppressed in the configuration where the non-fixed configuration is allowed to settle. The
[0022]
Further, in the above configuration, 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. Sludge generation due to retention of lubricating oil is suppressed. When the lubricating oil is replaced, particularly when discharged, the beads 13 and 14 that are continuous vertically and horizontally serve as a passage, and the lubricating oil in the oil layer 4 is promptly guided to the drain cock 11 portion and easily discharged. Similarly, when the lubricating oil is injected, the lubricating oil can be reliably introduced into the oil layer 4 through the beads 13 and 14.
[0023]
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 with the gap to be the oil layer 4 being maintained in each part. According to this embodiment, although it is slightly disadvantageous in terms of vibration reduction compared to the first embodiment described above, it is possible to reliably avoid interference with the connecting rod 6 and the like.
[0024]
【The invention's effect】
As is apparent from the above description, according to the oil pan damping structure for an internal combustion engine according to the present invention, the rigidity of the inner pan is increased by the formation of the bead, and therefore the oil layer formed between the oil pan and the oil pan As a result, the vibration is surely deformed, and a high vibration damping effect due to the viscosity of the lubricating oil in the oil layer is obtained. By making the bead convex toward the inside of the inner pan, it is possible to form a bead without increasing the thickness of the oil layer other than the bead portion, and the thickness of the oil layer is reduced regardless of the height of the bead. it can.
[0025]
In particular, if the bead is formed along the crankshaft direction as 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 surface of the oil pan can be greatly reduced.
[0026]
Further, since the bead functions as an oil passage, the lubricating oil in the thin oil layer can be easily discharged .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along line AA of FIG. 2 showing a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the first embodiment.
3 is a cross-sectional view taken along line BB in FIG. .
FIG. 4 is a plan view of inner bread.
FIG. 5 is a characteristic diagram showing a change in radiated sound due to the rigidity of the inner pan.
FIG. 6 is a characteristic diagram showing a change in radiated sound depending on the thickness of the oil layer.
FIG. 7 is an explanatory diagram showing a comparison between the state (a) of the oil layer when the bead is convex toward the outside and the state (b) of the oil layer when the bead is convex toward the inside.
FIG. 8 is a characteristic diagram showing the relationship between the gap at the bottom surface portion and the vibration level.
FIG. 9 is a longitudinal sectional view showing a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Oil pan 3 ... Inner pan 4 ... Oil layer 5 ... Baffle plate 11 ... Drain cock 13 ... Longitudinal bead 14 ... Lateral bead

Claims (2)

An oil pan for storing lubricating oil flowing down is fixed to the lower part of the internal combustion engine,
In'napan having walls along the oil pan wall to produce between gap between the oil pan wall including at least a portion of the bottom surface being disposed on the inner side of the oil pan,
Gap between the In'napan wall and the oil pan wall, have been opened in the space in the oil pan at the periphery of at least the In'napan, by lubricating oil enters, it forms an oil layer,
In the oil pan damping structure of the internal combustion engine that attenuates the energy of the oil pan film vibration by the flow of the lubricating oil generated when the interval between the two wall surfaces changes minutely and the oil layer expands and contracts,
A bead is formed on the bottom surface of the inner pan, and the bead is convex toward the inner pan, and an oil layer having a thickness (t2) smaller than the height (t1) of the bead is formed between the inner pan wall surface and the oil pan. An oil pan damping structure for an internal combustion engine, characterized by 2. The oil pan damping structure for an internal combustion engine according to claim 1, wherein the bead is formed along a crankshaft direction of the internal combustion engine.

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