JP5832175B2 - Liquid tanks and engines - Google Patents

Description

  The present invention relates to a liquid tank in which a plurality of partition plates are arranged in a tank, and stores a liquid, and an engine including the same.

  An engine oil pan is usually formed by welding thin plate materials and has low rigidity. Therefore, as shown in FIG. 14, a partition plate 41 is provided in the oil pan 40 for the purpose of reinforcement. When the oil pan 40 vibrates in response to the vibration of the engine when the engine is driven, the partition plate 41 may also vibrate and a crack may occur at the connection portion between the partition plate 41 and the oil pan 40. Therefore, for example, in Patent Document 1, as shown in FIG. 15, a vibrating body 51 corresponding to an engine cylinder block and an insulated object 50 are provided so as not to transmit vibration to the insulated object 50 corresponding to an oil pan. A structure is disclosed in which vibration-proof rubber 52 is interposed at the connection portion and fixed with bolts 53 to prevent transmission of vibration to the object to be insulated 50.

JP-A-7-243478

  However, in the structure described in Patent Document 1 described above, there has been a problem in that work efficiency during engine manufacture is reduced because an anti-vibration rubber must be attached between the vibrating body and the object to be insulated. In addition, since the number of parts increases, the cost increases, and the weight of the engine increases.

  Therefore, the present invention is to solve such a problem, and to provide a liquid tank that can be manufactured at low cost without greatly increasing the number of parts and that can suppress vibrations efficiently. Objective.

The liquid tank according to the present invention that solves the above-described problem has a bottom plate and a wall plate that surrounds the periphery of the bottom plate and is raised from the bottom plate, and is in a space on the bottom plate surrounded by the wall plate. In a liquid tank that stores liquid,
A plurality of partition plates that are erected on the bottom plate so as to partition the space, and are connected to the wall plates facing each other, and overlap each other;
A fastener for fastening the plurality of partition plates together,
The fastening force by the fastener is less than the fatigue limit stress of the partition plate.

  In this way, when the plurality of partition plates fastened by the tightening force less than the fatigue limit stress are vibrated together, the partition plates start to slide with each other before reaching the fatigue limit stress of the partition plate. Thereby, the bending stress which arises in a partition plate can be reduced. Therefore, it can prevent that a partition plate reaches | attains fatigue limit stress and is damaged. Further, when the plurality of partition plates slide, friction occurs between the partition plates. Vibration can be efficiently damped by the damping effect due to friction. Furthermore, since only a new fastener is added as compared with the conventional liquid tank, it can be manufactured at low cost.

  The fastener may be provided symmetrically with respect to a vertical center line of the partition plate in an in-plane direction of the partition plate.

  Since shear stress acts on both sides of the vertical center line of the partition plate due to vibration of the partition plate, a plurality of partition plates can be effectively fastened by providing a fastener at a location where the shear stress acts. .

  When the length between the both ends of the partition plate connected to the wall plate is L, and the length from the vertical center line of the partition plate to the fastener attached to the partition plate is M, The relationship 1/8 ≦ M / L ≦ 1/4 may be established.

  In this way, when the fastener is attached at a position of 1/8 ≦ M / L ≦ 1/4 from the vertical center line of the partition plate, that is, at a position where the amplitude of the partition plate is large, it is larger when slipping occurs. Since dissipative energy due to friction can be generated, a vibration damping effect can be obtained efficiently.

  When the height of the partition plate is b and the height from the upper surface of the bottom plate to the fastener attached to the partition plate is c, a relationship of 1/2 ≦ c / b <1 is established. Also good.

  In this way, by attaching the fastener to the position of 1/2 ≦ c / b <1 of the height of the partition plate, that is, the position where the amplitude of the partition plate is large, when slipping occurs, the friction is caused by greater friction. Since dissipated energy can be generated, a vibration damping effect can be obtained efficiently.

  The partition plates may have the same thickness in the overlapping direction.

  In this way, the partition plate can be manufactured at low cost by making the thickness of the partition plate in the overlapping direction, that is, the plate thickness all the same.

The liquid tank according to the present invention includes a bottom plate and a wall plate that surrounds the bottom plate and rises from the bottom plate, and stores liquid in a space on the bottom plate surrounded by the wall plate. In the liquid tank
A pair of partition plates with different thicknesses are provided on the bottom plate at predetermined intervals so as to partition the space, and both ends are respectively connected to the wall plate facing each other,
The liquid is interposed between the pair of partition plates.

  Thus, since the thicknesses of the pair of partition plates are different from each other, they resonate with different natural vibrations. For this reason, both partition plates do not resonate with the liquid tank body at the same time. In addition, when each partition plate vibrates, a liquid is interposed between the pair of partition plates, so that the liquid functions as a damper, so that the vibration can be attenuated efficiently.

  Of the pair of partition plates, when the thickness of one of the partition plates is d1 and the thickness of the other partition plate is d2, 1 / 2.4 ≦ d1 / d2 ≦ 1 / 1.5. A relationship may be established.

  Thus, when the thickness of one of the pair of partition plates is d1 and the thickness of the other is d2, the relationship of 1 / 2.4 ≦ d1 / d2 ≦ 1 / 1.5 is established. By forming, vibration can be damped efficiently.

The liquid tank according to the present invention includes a bottom plate and a wall plate that surrounds the bottom plate and rises from the bottom plate, and stores liquid in a space on the bottom plate surrounded by the wall plate. In the liquid tank
While being erected on the bottom plate on at predetermined intervals so as to partition the space and a pair of partition plate whose both ends are connected to the wall plate opposite to each other,
An elastic body sandwiched between the pair of partition plates;
A fastener that is inserted into the elastic body and fastens the partition plates,
The liquid is interposed between the pair of partition plates ,
Clamping force by the fastener, characterized by fatigue limit stress than der Rukoto of the partition plate.

  In this way, when the plurality of partition plates fastened by the tightening force less than the fatigue limit stress are vibrated together, the partition plates start to slide with each other before reaching the fatigue limit stress of the partition plate. Thereby, the bending stress which arises in a partition plate can be reduced. Therefore, it can prevent that a partition plate reaches | attains fatigue limit stress and is damaged.

  The engine of the present invention includes any one of the liquid tanks described above.

  Thus, since the liquid tank having the partition plate having an excellent damping effect is provided, an engine having excellent vibration rigidity can be provided.

  According to the present invention, it is possible to provide a liquid tank that can be manufactured at a low cost without greatly increasing the number of components and that can efficiently suppress vibration.

It is the top view which shows a part of oil pan which concerns on 1st embodiment of this invention, and A arrow directional view of the said top view. It is an enlarged top view near a fastener. It is a figure which shows the relationship between the displacement amount of a partition plate, and the bending stress which arises with the displacement of a partition plate. It is a distribution map of bending stress in the state where two partition plates are vibrated together. It is a distribution map of the shear stress in the state where two partition plates vibrate together. It is a distribution map of the bending stress in the state where two partition plates are sliding with each other. It is a distribution map of the shear stress in the state where two partition plates are sliding with each other. It is a figure which shows the attenuation | damping waveform of the conventional partition plate. It is a figure which shows the attenuation | damping waveform of a some partition plate. It is the top view which shows a part of oil pan which concerns on 2nd embodiment of this invention, and the B arrow view of the said top view. It is the top view which shows a part of oil pan which concerns on 3rd embodiment of this invention, and C arrow line view of the said top view. It is a conceptual diagram which shows the fluid state of the oil between a pair of partition plates. It is a conceptual diagram which shows the fluid state of the oil between a pair of partition plates. It is a figure which shows the conventional oil pan. It is a figure which shows the conventional vibration isolating method.

  Hereinafter, the liquid tank according to the present invention will be described in detail with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following examples are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative. It is just an example. In the following embodiments, the case where the liquid tank is applied to an engine oil pan will be described. However, the liquid tank is not limited to the engine oil pan, and may be applied to, for example, a water tank. .

FIG. 1 is a top view showing a part of an oil pan according to the first embodiment of the present invention, and a view as seen from an arrow A in the top view. FIG. 2 is an enlarged top view of the vicinity of the fastener.
As shown in FIGS. 1 and 2, the oil pan 1 is erected on the bottom plate 2 to divide a space in the oil pan 1 and a plurality of partition plates 4 are fastened together. Fasteners 10 are provided.
The some partition plate 4 is arrange | positioned in the oil pan 1 so that it may mutually superpose | polymerize. The left and right side edges and the lower edge of each partition plate 4 are welded to a wall plate 3 raised from the bottom plate 2. Further, a hole 7 for allowing oil to pass therethrough is provided at the lower part of each partition plate 4. All the partition plates 4 have the same thickness d.

ここで、Ｔ：締め付け力、σ_ｓ：疲労限応力、ｂ：仕切板４の高さ、ｄ：仕切板４の厚さ、μ：摩擦係数、Ｌ：仕切板４の幅である。 The fastener 10 includes a bolt 11 that penetrates the plurality of partition plates 4 and a nut 12 that is screwed into the bolt 11. The plurality of partition plates 4 can be integrated by tightening the bolts 11.
The partition plate 4 is formed with a through hole 8 through which the bolt 11 is inserted. The diameter of the through hole 8 is formed to be larger than the diameter of the threaded portion of the bolt 11. Thereby, although mentioned later for details, it can prevent that a shearing acts on the thread part of the volt | bolt 11 when the partition plates 4 slip. The tightening force by the fastener 10 is set to be less than the fatigue limit stress of the partition plate 4. The tightening force is calculated by the following equation (1).

Here, T: tightening force, σ _s : fatigue limit stress, b: height of the partition plate 4, d: thickness of the partition plate 4, μ: friction coefficient, L: width of the partition plate 4.

Since the plurality of partition plates 4 are fastened by the fastener 10, the plurality of partition plates 4 vibrate together when the engine is vibrating. On the other hand, when the vibration displacement of the partition plate 4 is increased due to resonance or the like and the frictional force generated between the plurality of partition plates 4 is smaller than the tightening force of the fastener 10, slip occurs between the plurality of partition plates 4. 4 vibrate while sliding against each other. At this time, the vibration can be damped by the damping effect caused by the friction generated between the plurality of partition plates 4. Since the tightening force by the fastener 10 is set to be less than the fatigue limit stress of the partition plate 4, as shown in FIG. 3, each partition plate 4 before the fatigue limit stress σ _s of the partition plate 4 is reached. Can begin to slide on each other, so that each partition plate 4 can be prevented from being damaged.

As shown in FIG. 1 again, the fastener 10 is disposed symmetrically with respect to the vertical center line of the partition plate 4. When the width and height of the partition plate 4 are L and b, respectively, the length from the fastener 10 to the vertical center line of the partition plate 4 is M, and the height from the fastener 10 to the bottom plate 2 is c, The fastener 10 is arrange | positioned so that following Formula (2) and following Formula (3) may be satisfy | filled.
M = (1/4) × L (2)
c = (2/3) × b (3)
In the present embodiment, the length M from the fastener 10 to the vertical center line of the partition plate 4 is (1/4) × L, and the height c from the fastener 10 to the bottom plate 2 is (2/3). Although the case where it was set as xb was demonstrated, it is not limited to this, About length M from the fastener 10 to the vertical centerline of the partition plate 4, it is 1/8 <= M / L <= 1/4. The relationship is established, and the height c from the fastener 10 to the bottom plate 2 may be a position where the relationship of 1/2 ≦ c / b <1 is established. Even within this range, the length M from the fastener 10 to the vertical center line of the partition plate 4 satisfies the relationship of 1/6 ≦ M / L ≦ 1/4. As for the height c, the position where the relationship of 1/2 ≦ c / b ≦ 2/3 is satisfied is preferable.

ここで、E：ヤング率である。
このときの２枚の仕切板４の断面２次モーメントＩは、次式（５）にて算出される。

図５は、２枚の仕切板４が一体となって振動している状態におけるせん断応力の分布図である。
図５に示すように、せん断力をＱとしたときの最大せん断応力τ_ｍａｘは、次式（６）にて算出される。

また、２枚の仕切板４の振幅を曲げ変位ｗとしたときに蓄えられる弾性エネルギーＵは、次式（７）にて算出される。

Next, the calculation method of the tightening force T described above will be described using an example in which two partition plates 4 are used.
FIG. 4 is a distribution diagram of bending stress in a state where the two partition plates 4 vibrate together.
As shown in FIG. 4, in normal engine vibration, the two partition plates 4 are integrated and behave like a single plate. At this time, the maximum bending stress σ _max is calculated by the following equation (4), where d is the thickness of each partition plate 4 (2d when two sheets are overlapped) and R is the curvature radius.

Here, E is Young's modulus.
The secondary moment I of the cross section of the two partition plates 4 at this time is calculated by the following equation (5).

FIG. 5 is a distribution diagram of shear stress in a state where the two partition plates 4 vibrate together.
As shown in FIG. 5, the maximum shear stress τ _max when the shear force is Q is calculated by the following equation (6).

The elastic energy U stored when the amplitude of the two partition plates 4 is the bending displacement w is calculated by the following equation (7).

式（８）により算出される最大曲げ応力σ’_ｍａｘと、式（４）により算出される最大曲げ応力σ_ｍａｘとを比較すると、最大曲げ応力σ’_ｍａｘは、最大曲げ応力σ_ｍａｘの半分となる（図３参照）。これにより、仕切板４の振幅が大きくなっても仕切板４の疲労限応力σ_ｓに到達することを防止できる。
また、このときの各仕切板４の断面２次モーメントＩ’は、次式（９）にて算出される。

式（９）により算出される断面２次モーメントＩ’と、式（５）により算出される断面２次モーメントＩとを比較すると、断面２次モーメントＩ’は、断面２次モーメントＩの１／４となる。
図７は、２枚の仕切板４が互いに滑っている状態におけるせん断応力の分布図である。
図７に示すように、せん断力Ｑ’は、断面２次モーメントに比例するので、次式（１０）にて算出される。
Ｑ’＝（１／４）Ｑ ・・・（１０）
これにより、最大せん断応力τ’ _ｍａｘは、次式（１１）にて算出される。

式（１１）により算出される最大せん断応力τ_ｍａｘと、式（６）により算出される最大せん断応力τ_ｍａｘとを比較すると、最大せん断応力τ’_ｍａｘは、最大せん断応力τ_ｍａｘの半分となる。
また、各仕切板４の振幅を曲げ変位wとしたときに蓄えられる弾性エネルギーU’は、次式（１２）にて算出される。

式（１２）により算出される弾性エネルギーＵ’と、式（７）により算出される弾性エネルギーＵとを比較すると、弾性エネルギーＵ’は、弾性エネルギーＵの１／４となる。 FIG. 6 is a distribution diagram of the bending stress in a state where the two partition plates 4 slide on each other.
As shown in FIG. 6, when the partition plate 4 resonates and the amplitude increases, the frictional force becomes smaller than the shear stress and slippage occurs between the two partition plates 4. The maximum bending stress σ ′ _max of each partition plate 4 at this time is calculated by the following equation (8).

When the maximum bending stress σ ′ _max calculated by the equation (8) is compared with the maximum bending stress σ _max calculated by the equation (4), the maximum bending stress σ ′ _max is half of the maximum bending stress σ _max . (See FIG. 3). Thereby, even if the amplitude of the partition plate 4 increases, it is possible to prevent the fatigue limit stress σ _s of the partition plate 4 from being reached.
Further, the sectional secondary moment I ′ of each partition plate 4 at this time is calculated by the following equation (9).

Comparing the sectional secondary moment I ′ calculated by the equation (9) with the sectional secondary moment I calculated by the equation (5), the sectional secondary moment I ′ is 1 / of the sectional secondary moment I. 4
FIG. 7 is a distribution diagram of the shear stress in a state where the two partition plates 4 slide on each other.
As shown in FIG. 7, since the shearing force Q ′ is proportional to the cross-sectional second moment, it is calculated by the following equation (10).
Q ′ = (1/4) Q (10)
Thereby, the maximum shear stress τ ′ _max is calculated by the following equation (11).

When the maximum shear stress τ _max calculated by the equation (11) is compared with the maximum shear stress τ _max calculated by the equation (6), the maximum shear stress τ ′ _max is half of the maximum shear stress τ _max. .
The elastic energy U ′ stored when the amplitude of each partition plate 4 is the bending displacement w is calculated by the following equation (12).

When the elastic energy U ′ calculated by the equation (12) is compared with the elastic energy U calculated by the equation (7), the elastic energy U ′ is ¼ of the elastic energy U.

Next, the attenuation effect due to the sliding of the partition plates 4 will be examined.
As described above, when each partition plate 4 starts to slide, the elastic energy stored by elastic deformation is dissipated and becomes about 1/4. At this time, since the maximum vibration speed amplitude is (1/4) ^1/2 = ^1/2 , the vibration amplitude becomes 1/2 for each period. The attenuation ratio ζ at this time is calculated by the equation (13).

このときの最大変位Ｗ_ｍａｘ、最大曲げモーメントＭ_ｍａｘは、それぞれ次式（１５）、（１６）にて算出される。
Ｗ_ｍａｘ ＝ＰＬ^３／（９６ＥＩ） ・・・式（１５）
Ｍ_ｍａｘ ＝ＰＬ／４ ・・・式（１６）
ここで、式（１５）を変形すると次式（１７）となる。

この式（１７）を式（１４）に代入すると、次式（１８）となる。

仕切板４の最大曲げ応力σ_ｍａｘは、次式（１９）により算出される。

ここで、Ｚ：断面定数である。式（１９）に式（１６）及び式（１７）を代入すると、次式（２０）となる。

ここで、最大曲げ応力σ_ｍａｘが疲労限応力σ_ｓとして式（２０）に代入して、式を変形すると、次式（２１）となる。

そして、式（２１）を式（１８）に代入すると、次式（２２）となる。

一方、仕切板４が滑り始める前の断面定数Zは、次式（２３）にて算出される。

式（２３）を式（２２）に代入すると、疲労限応力σ_ｓに達する曲げ応力発生時のせん断力の総和Ｆｓは、次式（２４）となる。

このとき仕切板４が滑り始めるようにボルト１１の締め付け力Ｔは、次式（２５）となる。

ここで、μ：摩擦係数である。式（２５）に式（２４）を代入すると、上記式（１）となる。

次に、ボルト１１の締め付け力Ｔの一例を示す。例えば、疲労限応力σ_ｓを１０Ｎ／ｍｍ^２、仕切板の厚さｄを３ｍｍ、高さｂを１０００ｍｍ、幅Ｌを３０００ｍｍ、摩擦係数μを０．５とした場合、これらの値を式（１）に代入すると、次式（２６）となり、締結具１０の締め付け力Ｔが算出される。

Next, the frictional force when the partition plate 4 starts to slide will be examined.
When the sum total of the shearing forces Q becomes larger than the sum total of the frictional forces, the partition plates 4 start to slide with each other. At this time, even if the partition plates 4 slide with each other, the diameter of the through hole 8 provided in the partition plate 4 is larger than the diameter of the screw portion of the bolt 11, so that the partition plate 4 contacts the screw portion of the bolt 11. There is nothing. That is, it is possible to prevent shearing from acting on the threaded portion of the bolt 11.
Then, when a load of P is applied to the center of the partition plate 4, the total sum FS of shear forces (assuming a simple support beam, the total sum of one side of the beam) is obtained by integrating the shear stress τ as follows: Calculated in (14).

The maximum displacement W _max and the maximum bending moment M _{max at} this time are calculated by the following equations (15) and (16), respectively.
W _max = PL ³ / (96EI) (15)
M _max = PL / 4 Formula (16)
Here, when Expression (15) is modified, the following Expression (17) is obtained.

Substituting this equation (17) into equation (14) yields the following equation (18).

The maximum bending stress σ _max of the partition plate 4 is calculated by the following equation (19).

Here, Z is a cross-sectional constant. Substituting Equation (16) and Equation (17) into Equation (19) yields the following Equation (20).

Here, when the maximum bending stress σ _max is substituted into the equation (20) as the fatigue limit stress σ _s and the equation is transformed, the following equation (21) is obtained.

Then, when Expression (21) is substituted into Expression (18), the following Expression (22) is obtained.

On the other hand, the sectional constant Z before the partition plate 4 starts to slide is calculated by the following equation (23).

When Expression (23) is substituted into Expression (22), the total sum Fs of shearing forces when a bending stress that reaches the fatigue limit stress σ _s is generated is expressed by the following Expression (24).

At this time, the tightening force T of the bolt 11 is expressed by the following equation (25) so that the partition plate 4 starts to slide.

Here, μ is a friction coefficient. Substituting equation (24) into equation (25) yields equation (1) above.

Next, an example of the tightening force T of the bolt 11 is shown. For example, when the fatigue limit stress σ _s is 10 N / mm ² , the partition plate thickness d is 3 mm, the height b is 1000 mm, the width L is 3000 mm, and the friction coefficient μ is 0.5, these values are expressed by the formula ( When substituting into 1), the following expression (26) is obtained, and the fastening force T of the fastener 10 is calculated.

Next, a description will be given of the results of analysis of vibration attenuation when the two partition plates 4 fastened with the fastening force T of the fastener 10 described above and when the conventional partition plate 4 is used.
FIG. 8 is a diagram illustrating the attenuation waveform of the conventional partition plate 4, and FIG. 9 is a diagram illustrating the attenuation waveforms of the plurality of partition plates 4 fastened by the tightening force T.
As shown in FIGS. 8 and 9, it can be seen that the two partition plates 4 fastened with the tightening force T can attenuate the vibration in a shorter time than the conventional partition plate 4 is attenuated.

As described above, in the oil pan 1 according to this embodiment, when the plurality of partition plates 4 fastened by the predetermined tightening force T vibrate together, the oil pan 1 reaches the fatigue limit stress σ _s of the partition plate 4. Before, the partition plates 4 begin to slide on each other. Thereby, the bending stress which arises in the partition plate 4 can be reduced. Therefore, the partition plate 4 can be prevented from reaching the fatigue limit stress σ _s and being damaged. Further, when the partition plates 4 slide, friction occurs between the partition plates 4. The vibration can be attenuated in a short time by the damping effect by this friction.
Further, since the shearing stress acts on both sides of the vertical center line of the partition plate 4 due to the vibration of the partition plate 4, the plurality of partition plates 4 can be effectively connected to each other by providing the fastener 10 at the location where the shear stress acts. Can be fastened.
Then, by attaching the fastener 10 to a position L / 4 from the vertical center line of the partition plate 4 and a position (2b) / 3 of the height of the partition plate 4, that is, a position where the amplitude of the partition plate 4 is large, When slipping occurs, dissipated energy due to greater friction can be generated, so that a vibration damping effect can be obtained efficiently.
Moreover, the partition plate 4 can be manufactured at low cost by making the thickness of the partition plate 4 in the overlapping direction, that is, the same plate thickness.

For example, if the plate thickness of the partition plate 4 is increased to have different natural frequencies so that the partition plate 4 does not resonate, the section modulus increases and the bending stress also increases. Therefore, since the bending stress can be reduced by sliding the plurality of partition plates 4 as in the present invention, the partition plate 4 has a fatigue limit as compared with the case where the thickness of the partition plate 4 is simply increased. It becomes difficult to reach the stress σ _s . Furthermore, since the engine vibrates at various frequencies, even if the thickness of the partition plate 4 is changed, there is a possibility that the engine will resonate at other frequencies. That is, it is difficult to adjust the plate thickness of the partition plate 4 so that the natural vibration does not resonate. Therefore, it is realistic to attenuate the vibration efficiently in a short time even when resonating.

Next, a second embodiment of the present invention will be described. In the following description, portions corresponding to the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
The oil pan 21 according to the second embodiment of the present invention is provided with an elastic body 22 between a pair of partition plates 4.

FIG. 10 is a top view showing a part of the oil pan 21 according to the second embodiment of the present invention and a view as seen from the arrow B in the top view.
As shown in FIG. 10, the oil pan 21 includes an elastic body 22 sandwiched between a pair of partition plates 4, and a pair of partition plates 4 and a fastener 10 that penetrates the elastic body 22. The fastener 10 includes a bolt 11 that passes through the pair of partition plates 4 and the elastic body 22, and a nut 12 that is screwed into the bolt 11. By tightening the bolt 11, the pair of partition plates 4 and the elastic body 22 can be integrated. Although the nitrile rubber which has oil resistance was used as the elastic body 22 in this embodiment, it is not limited to this.
Further, the diameter of the through hole 14 formed in the elastic body 22 for inserting the bolt 11 is formed to be larger than the diameter of the threaded portion of the bolt 11. Thereby, the elastic body 22 clamped between the pair of partition plates 4 does not prevent the partition plates 4 from sliding. The tightening force T by the fastener 10 is set to be less than the fatigue limit stress of the partition plate 4 as in the first embodiment, and is calculated by the above formula (1).
According to the oil pan 21 according to the present embodiment, when the plurality of partition plates 4 fastened by the fastener 10 vibrate together as in the first embodiment, the fatigue limit stress σ _s of the partition plate 4 is increased. The partition plates 4 begin to slide with each other before reaching. Thereby, the stress which arises in the partition plate 4 can be reduced. Therefore, the partition plate 4 can be prevented from reaching the fatigue limit stress σ _s and being damaged.

Next, a third embodiment of the present invention will be described.
The oil pan 31 according to the third embodiment of the present invention includes a pair of partition plates having different plate thicknesses.

FIG. 11 is a top view showing a part of the oil pan 31 according to the third embodiment of the present invention, and a view as seen from the arrow C in the top view.
As shown in FIG. 11, the oil pan 31 includes a pair of partition plates 34 and 36 having different plate thicknesses. When the thickness of one of the pair of partition plates 34 and 36 is d1 and the other is d2, the relationship d1 / d2 = 1/2 is satisfied. In the present embodiment, the relationship between the thicknesses of the pair of partition plates 34 and 36 has been described as satisfying d1 / d2 = 1/2. However, the present invention is not limited to this, and 1 / 2.4 ≦ Any material satisfying the relationship of d1 / d2 ≦ 1 / 1.5 may be used. Even within this range, a thickness that satisfies the relationship of 1 / 2.4 ≦ d1 / d2 ≦ 1/2 is preferable.

ここで、ｈ_０：仕切板３４、３６間の長さ、Ｂ：オイルパン３１内に貯留されているオイルの深さである。
続いて、式（３０）を変形すると、次式（３１）となる。

式（３１）により、一対の仕切板３４、３６間の長さｈ_０が算出される。ここで、長さｈ_０は、仕切板３４の下端の中心から仕切り板３６の下端の中心まで長さである。仕切り板３４、３６の下端は共に底板２に接続されているため、長さｈ_０の値は一定である。 The pair of partition plates 34 and 36 are arranged at a predetermined interval, and a hole 7 for allowing oil to pass therethrough is provided at the lower portion of each partition plate 34 and 36. Therefore, oil exists between the partition plates 34 and 36. Since the oil existing between the partition plates 34 and 36 functions as a damper, a damping effect can be obtained. The damping coefficient C due to the oil layer is calculated by the following equation (30).

Here, h _{0 is} the length between the partition plates 34 and 36, and B is the depth of oil stored in the oil pan 31.
Subsequently, when Expression (30) is transformed, the following Expression (31) is obtained.

The length h ₀ between the pair of partition plates 34 and 36 is calculated by Expression (31). Here, the length h ₀ is the length from the center of the lower end of the partition plate 34 to the center of the lower end of the partition plate 36. Since the lower end of the partition plate 34 and 36 are both connected to the bottom plate 2, a length value h ₀ is a constant.

式（３２）を変形すると、次式（３３）となる。

また、振動によって変化する両仕切板３４、３６間の長さｈをｈ（ｘ，ｔ）＝ｈ_０＋αｘη（ｔ）として、式（３３）に代入すると、次式（３４）となる。

Next, a method for calculating the above-described attenuation coefficient C will be described.
FIG. 12 is a conceptual diagram showing a flow state of oil between the pair of partition plates 34 and 36.
As shown in FIG. 12, the length between the partition plates 34 and 36 when the pair of partition plates 34 and 36 vibrate is assumed to be h. The length h between the partition plates 34 and 36 changes due to the vibration of the partition plates 34 and 36. At this time, the oil velocity v between the partition plates 34 and 36 also changes. When it is approximated that the oil velocity v flows uniformly between the partition plates 34 and 36, the following equation (32) is established.

When the equation (32) is transformed, the following equation (33) is obtained.

Further, when the length h between the partition plates 34 and 36 that changes due to vibration is substituted into the equation (33) as h (x, t) = h ₀ + αxη (t), the following equation (34) is obtained.

また、仕切板３４、３６間のオイルはポアズイユ流れに基づいていると仮定すると、速度勾配ｖ’は次式（３６）となる。
ｖ’＝（６／ｈ_０）×ｖ ・・・式（３６）
そして、式（３６）を式（３５）に代入すると、次式（３７）となる。

また、仕切板３４、３６が受ける全荷重は、次式（３８）で示すように、圧力ｐを仕切板３４、３６の幅に沿って積分することにより算出される。

このときの境界条件は、仕切板３４、３６とオイルとの接触している位置は大気圧なのでｐ＝０として、式（３８）に式（３７）を代入すると、次式（３９）となる。

ここで、

は、仕切板３４、３６間に作用する減衰係数Ｃとみなすことができる。 FIG. 13 is a conceptual diagram showing a flow state of oil between the pair of partition plates 34 and 36.
As shown in FIG. 13, when oil flows between the partition plates 34 and 36 due to the vibration of the partition plates 34 and 36, it depends on the flow velocity gradient at the contact surface where the partition plates 34 and 36 are in contact with the oil. Resistance is generated. And pressure p arises by flowing oil in opposition to this resistance. The pressure p at this time is calculated by the following equation (35).

Further, assuming that the oil between the partition plates 34 and 36 is based on the Poiseuille flow, the velocity gradient v ′ is expressed by the following equation (36).
v ′ = (6 / h ₀ ) × v Expression (36)
Then, when Expression (36) is substituted into Expression (35), the following Expression (37) is obtained.

Further, the total load received by the partition plates 34 and 36 is calculated by integrating the pressure p along the width of the partition plates 34 and 36 as shown by the following equation (38).

The boundary condition at this time is expressed by the following equation (39) by substituting equation (37) into equation (38) with p = 0 because the position where the partition plates 34 and 36 are in contact with the oil is atmospheric pressure. .

here,

Can be regarded as a damping coefficient C acting between the partition plates 34 and 36.

Next, an example of the size of the pair of partition plates 34 and 36 and the length h ₀ between the partition plates 34 and 36 will be shown. For example, the width L of the pair of partition plates 34 and 36 is 1000 mm, the height b is 400 mm, the thickness d1 of one partition plate 36 is 3 mm, the thickness d2 of the other partition plate 34 is 6 mm, and the pair of partition plates 34 , the length _{h 0} between 36 and 10 mm. Based on the size of the pair of partition plates 34 and 36, the length h ₀ between the partition plates 34 and 36 is increased in proportion to the width L and the height b, or the partition plate is inversely proportional to the thickness d. An appropriate length h ₀ can be obtained by narrowing the length h ₀ between 34 and 36. The length h ₀ between the partition plates 34 and 36 is particularly preferably 10 mm or less.

As described above, according to the oil pan 31 according to the present embodiment, the pair of partition plates 34 and 36 have different thicknesses, and thus resonate with different natural vibrations. For this reason, both the partition plates 34 and 36 do not resonate with the oil pan 31 body at the same time. Further, when the partition plates 34 and 36 vibrate, the oil interposed between the pair of partition plates 34 and 36 functions as a damper, so that the vibration can be damped efficiently.
Further, when the thickness of one of the pair of partition plates 34 and 36 is d1 and the thickness of the other is d2, it is formed such that the relationship d1 / d2 = 1/2 is established, thereby further improving the efficiency. Vibration can be damped well.

DESCRIPTION OF SYMBOLS 1 Oil pan 2 Bottom plate 3 Wall plate 4 Partition plate 7 Hole 8 Through hole 10 Fastener 11 Bolt 12 Nut 14 Through hole 21 Oil pan 22 Elastic body 31 Oil pan 34 Partition plate 36 Partition plate 40 Oil pan 41 Partition plate 50 Insulation Object 51 Vibrating body 52 Anti-vibration rubber 53 Bolt

Claims (9)

In a tank for liquid that has a bottom plate and a wall plate surrounding the bottom plate and raised from the bottom plate, and stores liquid in a space on the bottom plate surrounded by the wall plate,
A plurality of partition plates that are erected on the bottom plate so as to partition the space, and are connected to the wall plates facing each other, and overlap each other;
A fastener for fastening the plurality of partition plates together,
The liquid tank, wherein a tightening force by the fastener is less than a fatigue limit stress of the partition plate.   The liquid tank according to claim 1, wherein the fastener is provided symmetrically with respect to a vertical center line of the partition plate in an in-plane direction of the partition plate.   When the length between the both ends of the partition plate connected to the wall plate is L, and the length from the vertical center line of the partition plate to the fastener attached to the partition plate is M, The liquid tank according to claim 1, wherein a relationship of 1/8 ≦ M / L ≦ 1/4 is established.   When the height of the partition plate is b and the height from the upper surface of the bottom plate to the fastener attached to the partition plate is c, a relationship of 1/2 ≦ c / b <1 is established. The liquid tank according to claim 1, wherein the liquid tank is a liquid tank.   5. The liquid tank according to claim 1, wherein the partition plates have the same thickness in the overlapping direction. 6. In a tank for liquid that has a bottom plate and a wall plate surrounding the bottom plate and raised from the bottom plate, and stores liquid in a space on the bottom plate surrounded by the wall plate,
A pair of partition plates with different thicknesses are provided on the bottom plate at predetermined intervals so as to partition the space, and both ends are respectively connected to the wall plate facing each other,
A liquid tank, wherein the liquid is interposed between the pair of partition plates.   Of the pair of partition plates, when the thickness of one of the partition plates is d1 and the thickness of the other partition plate is d2, 1 / 2.4 ≦ d1 / d2 ≦ 1 / 1.5. The liquid tank according to claim 6, wherein the relationship is established. In a tank for liquid that has a bottom plate and a wall plate surrounding the bottom plate and raised from the bottom plate, and stores liquid in a space on the bottom plate surrounded by the wall plate,
While being erected on the bottom plate on at predetermined intervals so as to partition the space and a pair of partition plate whose both ends are connected to the wall plate opposite to each other,
An elastic body sandwiched between the pair of partition plates;
A fastener that is inserted into the elastic body and fastens the partition plates,
The liquid is interposed between the pair of partition plates ,
The fastening force by the fastener, the liquid tank, characterized in der Rukoto less than the fatigue limit stress of the partition plate.   An engine comprising the liquid tank according to any one of claims 1 to 8.

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