JPS63235742A - Cylindrical type hollow rotary drive shaft - Google Patents

Abstract

PURPOSE:To restrain occurrence of vibration and noise by specifying the monomer primary bending angular frequency of the hollow section of a cylindrical hollow rotary drive shaft, by setting the ratio between the wall thickness and the outer diameter of the hollow section to a value less than a predetermined value, and by fitting a resilient material vibration restraining body, closely onto the outer periphery of the hollow section. CONSTITUTION:In a cylindrical hollow rotary drive shaft made of metal, having solid parts in its both end sections by means of which the shaft is supported, the monomer primary natural bending angular frequency of the hollow section thereof is set to a value more than 500Hz while the ratio between the wall thickness and the outer diameter of the hollow section is set to a value less than 0.06, and a resilient material vibration restraining body is fitted closely onto the outer periphery of the hollow section. With this arrangement, the vibration restraining body may effectively absorbs bending vibration energy having a high level. In particular, when the thickness of a pipe is decreased, the amplitude of vibration is increased so that the vibration restraining body is subjected to large deformation, thereby it is possible to effectively damp vibration due to the history of resiliency of the vibration restraining body.

Description

DETAILED DESCRIPTION OF THE INVENTION LL Upper Plate 1 Dish 1 The invention relates to a fully flexible cylindrical hollow rotary drive shaft having solid parts at both ends and supported by the solid parts.

, J″′-1 The drive shaft of a front-wheel drive vehicle is generally formed as a solid body, but in recent years hollow bodies have also been used to reduce vehicle weight or reduce power transmission loss. ing.

The drive shaft has a function of transmitting the torque output from the drive source to the drive width.

Torsional vibrations, bending vibrations, and membrane surface vibrations occur in the drive shaft, and these are the causes of heavy body vibrations and noise that cause discomfort to passengers. This vibration has the maximum amplitude of the first-order bending mode in the frequency range of 200 to 500 cores (see the curve in Figure 10). ■It is difficult to reduce vibrations in this range using methods such as preventing vibrations and noise from entering the vehicle interior using vibration damping materials. ■A dynamic damper is attached, ■The drive shaft is made of an elastic material (meaning a material with high elasticity).
Techniques such as coupling the two through a damping body formed of

However, when using a dynamic damper, although it is possible to reduce the imaging of the target frequency, there is a problem that the amplitude (ffi dynamic level) of the frequency range lower and higher than the target frequency increases (see Figure 10). (See IQB)
In the case of a split type drive shaft, there is a problem in that a power light is generated because the transmission is carried out through a vibration damping body made of an elastic material.

On the other hand, an oscillating body made of an elastic material is press-fitted into the hollow part of the propulsion @ (propeller shirt 1 ~), and vibration, l! ! Technological ideas to reduce sound have been proposed (e.g., Special Publication No. 49-2
No. 0644, Japanese Utility Model Application Publication No. 5G-87647).

However, this idea remains at the basic level of using the elastic hysteresis phenomenon to convert the vibration energy of one hour of propulsion into heat by the internal friction of the vibration suppressor, and the propulsion shaft has a low right angular frequency (or eigenvalue) as a single unit. The main aim was to reduce the vibration level of membrane surface resonance.

Therefore, it has not been possible to effectively reduce the vibration label of -order bending resonance.

The present invention was devised in the light of such technical past, and its purpose is to solve the problem of primary bending resonance, which is a particular problem in hollow rotary drive shafts. The purpose is to effectively reduce the vibration level by analyzing the relationship between the hollow part and the press-fitted elastic material allocating body.

The purpose of this is to provide a metal cylindrical hollow rotary drive shaft that has a solid part at both ends and is supported by the solid part. This is achieved by setting the ratio (t/D) of wall thickness (X) to outer diameter (D) to 0.06 or less, and tightly fitting a vibration damper made of an elastic material around the outer periphery of the hollow portion.

Figure 1 shows the vibration characteristics of a closed tube body and a tube body with both ends open in a state where both ends are free.

As shown in FIG.

The present invention is intended to reduce primary bending resonance (see FIGS. 1 and 2), which could not be effectively dealt with conventionally. It is effective to have a damper absorb vibrations in areas where the vibration frequency is large and the vibration energy level is high.
We decided to set a large value (eigenvalue).

The bending natural angular frequency when both ends of the circular pipe are free is called the simple bending natural angular frequency, and the single value of the −th order bending resonance is the bending natural angular vibration of the circular pipe given by the following formula. Number (f
), it is sufficient to set λ=4.730.

(However, λ is the frequency coefficient that is compatible with the boundary conditions, p is the pipe length, E is Young's modulus, I G is the cross-sectional moment of inertia 1~, 8 is the pipe cross-sectional area, and ρ is the dense eave) (t According to the equation ), in order to increase the single bending natural angular frequency ([) of a circular pipe, the pipe length (A) and pipe cross-sectional area (A) should be made smaller. If the inner diameter or outer diameter of the circular pipe is the same, the cross-sectional area (^) of the pipe can be reduced by reducing the wall thickness.

If a vibration damper is press-fitted into a circular pipe whose single bending natural angular frequency is increased according to these conditions, or if a cylindrical vibration damper is tightly fitted around the outer circumference of the circular pipe, a high level of bending vibration energy will be generated. is effectively absorbed by the damping body, and especially when the pipe wall thickness is made small, the amplitude increases and the damping body undergoes large bending deformation, and the vibration becomes effective due to the elastic history phenomenon of the damping body. It will be attenuated to

Here, compared to the case where a vibration damper (referred to as a solid vibration damper) is press-fitted into a circular pipe, a cylindrical vibration damper (referred to as a hollow vibration damper) is tightly fitted around the outer periphery of a circular pipe. It should be noted that the damping effect is greater when the In other words, when the cross-sectional areas of the solid damper and the hollow damper are equal, the second moment of inertia h(
I) is larger than that of the former, and since the deformation (tlln'M) accompanying bending vibration is larger, the latter absorbs a large vibration energy of 1!- (see Test Example 4). This means that the same damping effect can be expected using a hollow damper with a smaller volume than a solid damper.

In addition, the hollow vibration damper can be fitted onto the outside of the circular tube after being heat-treated and painted, which has solid parts at both ends, so that deterioration due to heating can be prevented and control The vibration effect is guaranteed.

■Multiple steel hollow shafts with different lengths (outer diameter 50mmφ,
A solid cylindrical acrylic rubber piece (hardness: 50 mm) with a length of 50 mm and an outer diameter of 50 mm is prepared inside each hollow shaft.
°) was press-fitted.

■The vibration reduction effect of -order bending first rotation was investigated for hollow shafts containing rubber pieces that have different natural angular frequencies of single-order bending. This test was conducted by hitting one end of the hollow shaft 1 with a hammer and detecting the vibration level at the other end. The results are shown in FIG. 3 as a graph. However, the vibration level of the hollow shaft in which the acrylic rubber piece was not press-fitted was used as a reference, and this was defined as 0-dB.

<Evaluation of test results> It can be seen that as the natural angular frequency of single-order bending increases, the vibration level decreases. According to FIG. 3, when the single natural angular frequency is about 30011'z, hardly any vibration reduction effect can be obtained, but when the natural angular frequency is about 50011z or more, a vibration reduction effect can be expected.

■Prepare multiple steel hollows with different outer diameters (length 250M, inner diameter 4amφ), and insert a length of 100mm inside each hollow shaft.
, a solid cylindrical acrylic rubber piece (hardness 50°) with an outer diameter sommφ was press-fitted.

(2) The vibration reduction effect of primary bending resonance was investigated in the same manner as in Test Example 1 for each hollow shaft containing a rubber piece having a ratio (t/D) of the wall thickness (t> and the outer diameter (D>).

The results are shown in FIG. 4 as a graph.

It can be seen that as the ratio (t/D) of the test results becomes smaller, the vibration level decreases. According to FIG. 4, the effect of reducing vibration by 8J becomes large when the ratio (t/D> is approximately 0.06 or less).

W 旌■Y■ The hollow part that holds mass members 2, 2 (quality 0 parts) at both ends is 250 mm long, outer diameter 50 mmφ, and wall thickness 2. Om
, ratio (t/D) -0.04, single-order bending natural angular frequency (f) = 107111z (Fig. 5).

■Multiple solid cylindrical acrylic rubber pieces of different lengths (
A diameter of 50° and an outer diameter of 50 m++φ was prepared.

・■An acrylic rubber piece was press-fitted into the hollow @1, and the influence of the length of the acrylic rubber piece on the vibration reduction effect was investigated. The test procedure is the same as Test Example 1. The results are not shown as a graph in FIG. In the figure, ■ is the resonance-order mode (
■ indicates the vibration reduction level of the second-order resonance mode (secondary bending resonance), and ■ indicates the vibration reduction level of the third-order resonance mode (secondary film surface resonance). There is.

Evaluation of test results> ■The vibration reduction effect of press-fitting the acrylic rubber piece is greatest for third-order mode resonance (secondary membrane surface resonance).

■The longer the length of the acrylic rubber piece, the greater the vibration reduction effect.

■As for bending resonance, the vibration reduction effect of primary bending resonance is greater than that of secondary bending resonance.

■In addition, the natural angular frequency of the primary bending (f) = 300H7
It should be noted that even if rubber pieces of various lengths are press-fitted into the hollow shaft described below, it is not possible to expect a vibration reduction effect of the -order bending resonance (see Fig. 3).

L151 ■ Five steel drive shafts 3 (outer diameter 50 #φ, wall thickness 2.0 mm) having solid shaft portions 4, 4 at both ends of the hollow body 5 are prepared (Fig. 7).

■ Acrylic rubber pieces 6 (outer diameter 50 mφ, length 70 tnm, volume 1.37
x 10" m, 3, hardness 50"), /' A piece of krill rubber 7.7 (outer diameter 50 mφ, length 35.m, hardness 5°) was press-fitted. The press-fitting position is each drive+I'ib
Although it differs for each model, the total press-fit rubber length is all 70# (Figure 8).

■Similarly, a cylindrical hollow acrylic rubber piece 8 (inner diameter 48 mmφ, outer diameter 64 mmφ, length 50 mm, closed VA 1.48 x 105 mm!, hardness 50°) was fitted onto the center of the hollow body 5 of the drive shaft 3. (Figure 8).

<Evaluation of test results> ■As shown in Fig. 8, the vibration reduction level of the -order bending resonance is determined in the central part of the hollow body 5 among (a), (b), (c), and (d). The case (a) in which the rubber pieces 7.7 are press-fitted into the hollow body 5 is the largest, and the case (d) in which the hollow body 5 is divided into both ends and the rubber pieces 7.7 are press-fitted is the smallest. This is because the central portion is the maximum amplitude position of the primary bending resonance, and the rubber piece 6 press-fitted at this position undergoes the largest bending deformation and absorbs vibration energy. However, in the case of a hollow body with a thin wall on one side and a thick wall on the other side in the length direction, the maximum amplitude position is at a point slightly deviated toward the thin wall side from the boundary between the thin wall section and the thick wall section, and there is a rubber section in the same area. should be press-fitted.

■Also, when a rubber piece is press-fitted into the center of the hollow body 5 (
a), the vibration reduction effect of 11.4 dB is 17, whereas the hollow body 5. A rubber piece 8 of approximately the same volume is placed in the center of the
When (e) is fitted externally, a vibration reduction effect of 15.7 dB is obtained, indicating that external fitting is more effective.

Formula 2 Using a plate-top drive shaft 3 (Fig. 7), inside the hollow body 5, acrylic rubber pieces of different lengths (outer diameter 50 mφ, hardness 50°) and bubble rubber pieces (outer diameter 50 mφ, hardness 5
0°), natural rubber piece (outer diameter 50JIIIφ).

The effect of the amount of press-fit on the vibration reduction effect of primary bending resonance was investigated for each type of stiffness.

The results are shown in Figure 9 as a graph.

<Evaluation of test results> It is effective to use a rubber type with a large damping coefficient, and the use of acrylic rubber pieces is most effective in reducing vibration.

Chiku 1■1 An acrylic rubber piece is press-fitted into the center of the hollow body 5.
The drive shaft 3 (outer diameter of the hollow body 5: 42.2 mm, length of the hollow body 5: 190 m, total length: 420 m) (Fig. 7) is assembled into an actual vehicle as a front wheel drive shaft, and the drive shaft 3 is assembled into the actual vehicle as a front wheel drive shaft. III Axis 3 no Kaku! J.I.
The a-side end was hit with a hammer, and the vibration level was measured at the opposite end. The results are shown in FIG. 10 as a graph (curve C).

For comparison, we also show the vibration level of a conventionally shaped drive shaft without any vibration reduction measures (curve Δ), and the vibration level of a conventionally shaped drive shaft with a dynamic damper (curve Δ).
Curve B) is also shown in FIG.

Evaluation of test results〉 ■With conventional drive shafts without vibration reduction measures, 20
The maximum point Δ, (
-Next bending point: approx. 40011z), whereas
In a conventional drive shaft equipped with a dynamic damper, the maximum point does not shift separately to the low frequency side and the high frequency side.
→B) 1 Maximum point Bs of curve B.

B2 are located at about 2001tz and about 5007 positions, respectively.

■Characteristic curve C of Drive@3 is a form in which the maximum point A1 of a conventional drive shaft without vibration reduction measures has shifted to the high frequency side, and the maximum point ClG174411z 4
fLrj, and the 8 pressure level at the maximum point C1 is lower than that at Δ1.

(2) In the range of 200.about.500H2, the line C is lower than the curve B, and it can be seen that the sound pressure level of the drive shaft 3 into which the rubber piece is press-fitted is low in this range.

W Mouse J [ Drive shaft 3 (7th
(Figure) was installed in an actual vehicle as a front wheel drive shaft, and the sound pressure level inside the vehicle (measured at the center of the front seat using a filter that extracts only the sound of 200 to 500 H2) was investigated while the vehicle was running. The results are shown as a graph in Figure 11 (the horizontal axis is the engine rotation speed (rlPH) and the vertical axis is the sound pressure level).
. Song 8!2C is a characteristic curve of the drive shaft 3 into which a rubber piece is press-fitted, and song FIB is a characteristic curve of a conventional example in which a dynamic damper is attached to the drive shaft 3.

Evaluation of test results> From Fig. 11, if a front wheel drive shaft into which a rubber piece is press-fitted is used, compared to a conventional front wheel drive shaft equipped with a dynamic damper, it is 3.000 to 5.00% lower. It can be seen that a vibration reduction effect of 2 to 3 dB can be obtained in the range of 50 ORPM.

As is clear from the above description, it is a metal cylindrical hollow rotary drive shaft that has a solid part at both ends and is supported by the solid part, and the hollow part is bent in a single unit. Natural angular frequency is 500H
z or more, the ratio of the wall thickness (t) of the hollow part to the outer diameter (D) (t/
D) is 0.06 or less, and a cylindrical hollow rotary drive with reduced primary bending resonance, characterized in that a vibration damper made of an elastic material is tightly fitted around the outer periphery of the hollow part! IJ+@ was proposed.

This cylindrical hollow rotary drive shaft has a single-order bending natural angular frequency of 500 tlz or more, and the ratio (t/D)
0.06 or less to enhance the mounting effect of the vibration damping body, and a cylindrical vibration damping body made of an elastic material, which is even more effective than press-fitting the elastic material 11 vibration damping material, is externally fitted into the hollow part. ,−
Next bending resonance is effectively reduced and generation of vibration 9g sound is suppressed.

[Brief explanation of the drawing]

Figure 1 is a graph showing the vibration characteristics of a tube with both ends open, with both ends free, Figure 2 is a graph showing the vibration characteristics of a tube with both ends open, with both ends open. A graph showing the relationship between the natural angular frequency and the dynamic reduction effect when a rubber piece is press-fitted onto the drive shaft. Figure 4 shows the pipe wall thickness/outer diameter when a rubber piece is press-fitted onto the drive shaft. A graph showing the relationship between the ratio (t/D) and the vibration reduction effect. Fig. 5 is a perspective view of a test steel cylindrical hollow rotary drive shaft with two ends cut out. Fig. 6 shows a rubber part on the drive shaft. FIG. 7 is a graph showing the relationship between the length of a press-fitted rubber piece and the vibration reduction effect when a piece is press-fitted, and FIG. FIG. 8 is a schematic diagram showing the relationship between the press-fitting position and the vibration reduction effect when a rubber piece is press-fitted into the hollow part of the drive shaft,
Fig. 9 is a graph showing the relationship between press-fitting and vibration reduction effect when three different types of rubber pieces are press-fitted into the hollow part of the drive shaft, and Fig. 10 is a graph showing the relationship between press-fitting and vibration reduction effect when rubber pieces are press-fitted into the hollow part of the drive shaft. A diagram showing the vibration characteristics of a drive shaft with a dynamic damper, a drive shaft without vibration countermeasures, and a drive shaft with a dynamic damper.
FIG. 11 is a graph showing the results of a vibration characteristic test when a dynamic damper was attached to the drive shaft and when rubber was press-fitted into the hollow part, which were assembled into an actual vehicle. 1...Hollow shaft, 2...Massive piece, 3...Drive shaft,
4... Solid shaft portion, 5... Hollow body, 6... Acrylic rubber piece, 7... Acrylic rubber piece, 8... Hollow acrylic rubber piece.

Claims (1)

[Scope of Claims] A metal cylindrical hollow rotating drive shaft having solid parts at both ends and supported by the solid parts, wherein the hollow part has a single primary bending natural angular frequency of 500 Hz or more, and the hollow part has a solid part at both ends. The ratio of the wall thickness (t) to the outer diameter (D) (t/D) is 0.06 or less, and a vibration damper made of an elastic material is tightly fitted around the outer periphery of the hollow portion. Cylindrical hollow rotary drive shaft with reduced primary bending resonance.