JPH0953760A - Vibration reducing piping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with the use of a vibration damper in effectively suppressing bending vibration which permeates piping. SOLUTION: The center of piping is formed in a semicircular shape. A piping shape whose bending vibration suppressing effect is a maximum, is in a case where an angle θ of a semicircular surface and a vibrating direction is 90 deg., and the ratio R/L between the radial diameter R of a bending line pipe part 13 and the length L of right and left straight line pipe parts 11, 12 is 0.4 to 1.6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration reducing pipe, and more particularly to a pipe having a pipe shape capable of effectively suppressing bending vibration transmitted through the pipe.

[0002]

2. Description of the Related Art A refrigerant piping system in an automobile air conditioner or a refrigerating case is a vibration source because one end is connected to a compressor (compressor) and the other end is connected to a structure such as an evaporator (evaporator). The vibration of the compressor may vibrate the pipe, and the vibration of the pipe may be transmitted to a structure such as an evaporator, causing vibration and noise. Among the vibration components transmitted through the piping system, the level of bending vibration is particularly high, and vibration and noise are likely to occur, but such bending vibration is difficult to remove by simple support.

Therefore, as a method of suppressing the bending vibration transmitted through the pipe, conventionally, as shown in FIG. 6, a vibration absorber 1 such as a damper is used to suppress the bending vibration transmission of the pipe 2.
In addition, the low-pressure side pipe 2 which connects the compressor 3 and the evaporator 4 which are the vibration sources is shown by taking an automobile air conditioner as an example. The vibration absorber 1 is composed of elements having a spring constant k, a damping coefficient c, and the like.

[0004]

However, in such a conventional bending vibration transmission suppressing method, since the vibration absorber 1 is used, there is a problem that the cost is high and the space is required. In many cases, the vibration absorber 1 cannot be used in consideration of space and the like.

Taking an automobile air conditioner as an example (see FIG. 6), for example, in an automobile air conditioner, layout is largely restricted and various devices must be installed in an extremely narrow and limited space. As a result, it is extremely difficult to install the vibration absorber 1 as a sound vibration countermeasure. In addition, the use of the vibration absorber 1 not only raises the cost, but also results in contrary to the idea of reducing the weight of the vehicle. However, today, on the other hand, reduction of vehicle interior noise is one of the important issues, so how to effectively suppress the transmission of bending vibrations of pipes without using a vibration absorber as a measure against noise and vibration of air conditioners. There is a strong demand for the presentation of specific methods.

The present invention has been made in view of the above problems of the prior art, and a vibration reducing pipe capable of effectively suppressing bending vibration transmitted through the pipe without using a vibration absorber. The purpose is to provide.

[0007]

In order to achieve the above object, the vibration reducing pipe according to claim 1 is a pipe for connecting a vibration source and a structure, the pipe being a straight pipe portion and a semi-pipe. And a circular curved pipe portion.

A vibration reducing pipe according to a second aspect is the first aspect.
In the described one, the semi-circular curved pipe portion is provided at the center of the pipe.

A vibration reducing pipe according to a third aspect is the second aspect.
In the description, the angle θ formed by the plane including the semi-circular curved tube portion and the vibration direction is 70 ° to 90 °.

The vibration reducing pipe according to claim 4 is the vibration reducing pipe according to claim 2.
In the above description, the ratio R / L of the radius R of the semi-circular curved pipe portion and the length L of the left and right linear pipe portions is 0.3 to
0.8.

The vibration reducing pipe according to claim 5 is the pipe according to claim 2.
In the description, the angle θ formed by the plane including the semi-circular curved pipe portion and the excitation direction is 70 ° to 90 °, and the radius R of the semi-circular curved pipe portion and the right and left sides are equal to each other. The ratio R / L with the length L of the straight pipe portion is 0.3 to 0.8.

The vibration reducing pipe according to claim 6 is the pipe according to claim 2.
The angle θ formed between the plane including the semi-circular curved pipe portion and the excitation direction is 90 °, and the radius R of the semi-circular curved pipe portion and the straight pipes on the left and right sides. The ratio R / L with the length L of the part is 0.4 to 0.6.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the present invention. In the present invention, from the viewpoint of suppressing the bending vibration transmitting the pipe by the shape design of the pipe,
As shown in FIG. 1, the middle of the pipe 10 is semicircular to form a pipe system in which a straight pipe element and a curved pipe element are connected. That is, the pipe 10 is composed of the left and right straight pipe portions 11 and 12 and the middle semicircular curved pipe portion 13. The semi-circular shape of the middle of the pipe 10 will be referred to as Ω below.
This is called mold piping. Here, L1 and L2 are the lengths of the left and right straight pipe portions 11 and 12, respectively, and R is the radius of the curved pipe portion 13. Further, θ is an angle formed by a plane including the curved tube portion 13 (hereinafter, referred to as a curved tube plane or a semicircular surface) and the vibration direction. The specific shape of the pipe 10 is determined by such various parameters L1, L2, R and θ. In the figure, point m is an excitation point and point n is a support point.
For example, the m-end is attached to a vibration source 3 such as a compressor, and the n-end is attached to a structure 4 such as an evaporator (for example, see FIG. 6 regarding an air conditioner for a vehicle). The boundary condition of the pipe is that the m-end is roller support and the n-end is simple support.

As shown in the simulation results described later, the Ω type pipe 10 has an effect of suppressing bending vibration of the pipe. Such a bending vibration suppressing effect of the Ω type pipe 10 is provided in the middle of the pipe. It is based on the principle that the bending vibration component is suppressed by changing the vibration mode of the pipe using the semicircular shape and converting a part of the excitation energy, that is, a part of the bending vibration into the torsional vibration of the pipe.

The specific shape of the Ω type pipe 10 is determined by the various parameters L1, L2, R and θ as described above. Which shape is actually used is determined by changing the parameter values in advance. The data of the vibration suppression effect of (1) may be obtained by simulation or experiment, and in consideration of the actual layout restriction, the shape capable of obtaining the maximum vibration suppression effect within the restriction may be determined with reference to the data.

As described above, bending vibration is apt to cause vibration and noise of equipment, so it is necessary to keep it as small as possible, but the transmission of the other torsional vibration can be prevented by simple support. Cheap. As described above, the transmission of torsional vibration is easier than the bending vibration. Therefore, by simply suppressing the torsional vibration by suppressing the bending vibration transmission by the Ω type pipe 10 of the present invention, the vibration absorber is practically used. It is possible to sufficiently suppress noise without using. For example, in the sound and vibration problem of an air conditioner, a low-pressure side pipe (that is, a pipe connecting the compressor 3 and the evaporator 4) which is a main vibration transmission path from the compressor 3 which is a vibration source is used as the Ω type pipe 10 according to the present invention. With this configuration, the bending vibration transmitted through the low-pressure side pipe can be significantly reduced without using a vibration absorber, and the air conditioner operating noise can be reduced.

The Ω type pipe 10 of the present invention is not limited to the case of an air conditioner for an automobile as described above, but is a pipe for connecting another vibration source and a structure such as a refrigerating case. -Of course, it can be applied to noise prevention.

[0018]

EXAMPLE A condition (pipe shape) for maximizing the bending vibration suppressing effect of the Ω type pipe 10 was obtained by simulation. FIG. 2 shows the pipe shape used for the calculation. FIG. 2A shows a straight pipe (referred to as I type) used as a reference for comparison, and FIG. 2B shows the same length as the I type pipe and the same inside and outside. In terms of diameter, it is an Ω type pipe 10a in which the center of the pipe is semicircular. That is, here, in the Ω type pipe 10 shown in FIG.
3 is in the center of the pipe and the lengths of the left and right straight pipe portions 11 and 12 are equal (L1 = L2 = L) (this is referred to as a symmetrical .OMEGA. Type pipe).
The relationship between the angle θ between the semi-circular surface and the vibration direction and the vibration suppression effect,
Also, the radius R of the curved pipe portion 13 and the left and right straight pipe portions 11, 1
The relationship between the ratio R / L with the length L of 2 and the vibration suppressing effect was investigated, and the optimum value for each was obtained. The ratio R / L corresponds to the ratio of the slenderness ratio of the curved pipe portion 13 and the slenderness ratio of the straight pipe portions 11 and 12.

The calculation is for a pipe (symmetrical Ω
Mold pipe) x indicating the magnitude of bending vibration at the n-end of 10a
The combined amount Δ of the rotation angles φ and δ around the axis and the y-axis (see FIG. 2A) was obtained on the basis of frequency. The dimensionless quantities and material constants used in the calculation are as follows. That is, the dimensionless frequency is given by the following Equation 1,

[0020]

[Equation 1]

The dimensionless state quantity is given by the following equation 2,

[0022]

[Equation 2]

The combined amount of rotation angles is given by the following equation 3.

[0024]

(Equation 3)

Where u, v, and w are displacements of the pipe axis, β, φ, and δ are rotation angles of the pipe cross section, respectively, U, V, and
W is the sectional force, T, H and M are the sectional moments z, x,
It is the y component. Further, ρ, E, A, I, L0, ω, and Q are the tube material density, the longitudinal elastic modulus, the cross-sectional area, the second moment of area, the total length of the pipe, the angular frequency, and the representative load, respectively. The material of the pipe is a uniform material, for example, ρ = 2.68 × 10 ³ (kg / m ³ ) E = 7.0 × 10 ¹⁰ (Pa).

The analysis method used in the above calculation is as follows. First, using the exact solution of the static equilibrium equation of the three-dimensional space curved beam, the space matrix [Fc] of the space curve tube element is obtained, and the space matrix [Fs] of the three-dimensional straight tube element, the inertia force and A lumped mass rating matrix [P], an internal support point transfer matrix [K], a coordinate transformation matrix [H], which considers the moment of inertia.
Each excitation point transfer matrix [Pf] is created.
The transfer matrices [Tc] _i and [Ts] _i of the curved tube element and the straight tube element are expressed by the following equations 4 and 5.

[0027]

(Equation 4)

[0028]

(Equation 5)

Here, i is the number of divisions of the elements, for example, k = 1 to 13 and q = 1 to 13. Next, by the transfer matrix method, the vibration transfer equation of the entire piping system is as shown in the following expression 6.

[0030]

(Equation 6)

Here, {X} _n and {X} ₀ are state quantity vectors at both ends of the pipe, and {X} = {uvwβφδUVWTHM1}. Further, [E] _n is the entire transfer matrix of the piping system, and is obtained from the transfer matrix of each element constituting the piping system. Further, by applying the boundary condition to the equation 6, the vibration transfer equation of the piping system can be obtained. The above calculation is performed by solving this vibration transfer equation.

The bending vibration suppressing effect (vibration suppressing effect) ζ of the symmetrical Ω type pipe 10a is the sum (integrated value) of the responses of the deflection angles at the m-end of the symmetrical Ω type pipe 10a (see FIG. 2B) and this. Is defined by the ratio of the deflection angle of the I-type pipe (see FIG. 2 (A)) having the same length as the sum of the responses (integral value). More specifically, first, a response curve of the rotation angle composite amount Δ at the point m is calculated on the basis of the frequency, and then the area surrounded by the curve and the frequency is calculated. The ratio of the area to the area of the I-shaped pipe is the bending vibration level ratio of the symmetrical Ω-shaped pipe to the I-shaped pipe, that is, the damping effect ζ. The smaller the value of ζ is, the larger the suppression effect is.

FIG. 3 is a graph showing the relationship between the angle θ and the damping effect ζ obtained by simulation at the ratio R / L = 0.208. From the figure, it can be seen that the vibration suppressing effect is maximum when the angle θ formed by the semicircular surface and the vibration direction is 90 °. Although not shown, even when the value of R / L is changed, the suppression effect is maximized when the angle θ is 90 °. That is, the optimum value of the angle θ (= 90 °) is not affected by the value of the ratio R / L.

Further, in the case of FIG. 3, practically 70 ° to
A range of 90 ° is reasonable. As described above, the angle θ is 90
This is because the effect is maximized at 0 °, but in the range of 70 ° to 90 °, an effect close to that at 90 ° is obtained.

FIG. 4 is a graph showing the relationship between the ratio R / L obtained by simulation and the damping effect ζ at the optimum angle θ = 90 °. From the figure, the radius R of the curved pipe portion 13
And the ratio R / L of the length L of the left and right straight tube portions 11 and 12 is 0.
When 3 to 0.8, the effect is large, especially R / L = 0.4
It can be seen that the maximum effect of suppressing bending vibration is obtained in the range of up to 0.6. Each of these takes a certain range on the left and right of the value of the ratio R / L at which the maximum effect is obtained.

Therefore, in order to obtain the maximum bending vibration suppressing effect in the symmetrical Ω type pipe 10a, the angle θ between the semicircular surface and the vibration direction is 90 °, and the curved pipe portion 1
Ratio R of radius R of 3 and length L of the left and right straight tube portions 11 and 12
This is when / L is 0.4 to 0.6.

As the shape of the symmetrical Ω type pipe 10a,
The angle θ is between 70 ° and 90 °, and the ratio R / L is 0.
It can be seen that when it is in the range of 3 to 0.8, a suppressing effect that can be put to practical use can be obtained.

FIG. 5 shows that the optimum angle θ = 90 ° and the ratio R / L =
Bending vibration response of symmetrical Ω type pipe 10a having 0.48 and I
It is a graph which shows the bending vibration response of type piping. here,
The horizontal axis represents the dimensionless frequency λ, and the vertical axis represents the combined amount Δ of the rotation angle at the support point m.

From the figure, the symmetric Ω type pipe 10a is greatly suppressed in the secondary and subsequent parts except the primary resonance, as compared with the I type.
It can be seen that the effect of suppressing bending vibration is extremely large. It is considered that the suppression effect on the primary vibration is weak because it is a rigid body vibration, but it is generally considered that the noise power becomes large at high frequencies after the second order and small at low frequencies. Therefore, it can be said that the symmetrical Ω type pipe 10a, which has a large effect of suppressing the secondary vibrations and after, is also sufficiently effective in suppressing noise.

[0040]

As described above, according to the invention described in claim 1, since the middle of the pipe is formed in a semicircular shape, the bending vibration which transmits the pipe only by the pipe shape without using the vibration absorber is provided. As a result, it is possible to significantly reduce the vibration and noise of the device, and it is possible to effectively reduce the cost and space of the device.

According to each of the inventions described in claims 2 to 5, since the center of the pipe is formed in a semicircular shape, it is possible to greatly suppress the bending vibration transmitted through the pipe only by the pipe shape without using a vibration absorber. As a result, it becomes possible to effectively reduce the vibration and noise of equipment at low cost and in a small space.

According to the invention described in claim 6, it is possible to obtain a particularly maximum bending vibration suppressing effect in the case where the center of the pipe is semicircular.

[Brief description of drawings]

FIG. 1 is a schematic view of an Ω type pipe showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a pipe shape used in the simulation.

FIG. 3 is a graph showing the relationship between the angle θ and the damping effect ζ in a symmetrical Ω type pipe.

FIG. 4 Ratio R / L and damping effect ζ in symmetrical Ω type piping
Graph showing the relationship with

FIG. 5 is a graph showing a comparison of bending vibration response between symmetrical Ω type pipe and I type pipe.

FIG. 6 is a schematic view showing a conventional method for suppressing bending vibration transmission of piping.

[Explanation of symbols]

 3 ... Compressor (excitation source) 4 ... Evaporator (structure) 10, 10a ... Ω type pipe (vibration reduction pipe) 11, 12 ... Straight pipe part 13 ... Curved pipe part

Claims (6)

[Claims] 1. A pipe (10) for connecting a vibration source (3) and a structure (4), said pipe (10) being a straight pipe portion (11, 12) and a semi-circular curved pipe. A vibration reducing pipe having a portion (13). 2. The vibration reducing pipe according to claim 1, wherein the semi-circular curved pipe portion (13) is provided in the center of the pipe (10). 3. The vibration reduction according to claim 2, wherein an angle (θ) formed by a plane including the semi-circular curved pipe portion (13) and a vibration direction is 70 ° to 90 °. Piping. 4. The ratio (R / L) between the radius (R) of the semi-circular curved pipe portion (13) and the lengths (L) of the left and right linear pipe portions (11, 12) is 0. The vibration reduction pipe according to claim 2, wherein the vibration reduction pipe is 3 to 0.8. 5. The angle (θ) formed by the plane including the semi-circular curved pipe portion (13) and the vibration direction is 70 ° to 90 °, and the semi-circular curved pipe portion ( 13) Radius (R)
The vibration reduction pipe according to claim 2, wherein a ratio (R / L) between the length and the length (L) of the straight pipe portions (11, 12) on the left and right is 0.3 to 0.8. 6. An angle (θ) formed by the plane including the semi-circular curved pipe portion (13) and the vibration direction is 90 °, and the semi-circular curved pipe portion (13) The ratio (R) of the radius (R) and the length (L) of the straight tube portions (11, 12) on the left and right
/ L) is 0.4-0.6, The vibration reduction piping of Claim 2 characterized by the above-mentioned.