JPH0637915B2 - Dynamic damper - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper that is mounted around a rotary shaft such as a drive shaft of an automobile and suppresses harmful vibration generated on the rotary shaft.

[Prior Art] Dynamic dampers are provided to suppress harmful vibrations that should not occur originally, such as bending vibrations and torsional vibrations due to rotational imbalance caused by the rotation of rotary shafts such as drive shafts and propeller shafts of automobiles. Is often used. These dynamic dampers fulfill their function by matching the natural frequency with the predominant frequency of the harmful vibration to be excited, and by converting the vibration energy of the rotating shaft into the vibration energy of the dynamic damper by absorption and absorbing it. .

As shown in FIG. 9, a dynamic damper that has been conventionally used for a drive shaft of an automobile or the like has a fixing member 101 that is inserted and held on a rotating shaft and a fixing member 101.
It is composed of a cylindrical mass member 102 arranged on the outer periphery of the, and an elastic member 103 sandwiched between the fixing member 101 and the mass member 102 and connecting them. The natural frequency of the dynamic damper is basically determined by the mass of the mass member 102 and the spring constant of the elastic member 103.
At this time, since the elastic member 103 receives a load in the compression / tension direction against the vibration of the mass member 102 in the radial direction, the elastic member 103 supports the mass member 102 in the direction having the compression / tension spring constant. is doing.

[Problems to be Solved by the Invention] However, in the above-described conventional dynamic damper, the mass member, the fixing member that is inserted and held by the rotating shaft, and the mass member that is interposed between the mass member and the fixing member support the mass member. The elastic member has a shape laminated in the radial direction of the dynamic damper. Therefore, in the conventional dynamic damper,
Since the outer diameter of the elastic member is increased due to the laminated structure of the fixed member, the elastic member, and the mass member, the outer periphery of the elastic member is constrained by the metal mass member. It was accompanied by great difficulties. Further, when it is necessary to set the natural frequency of the dynamic damper to be low, it is necessary to reduce the spring constant of the elastic member or increase the mass of the mass member. In order to reduce the spring constant of the elastic member, it is necessary to lengthen the shape of the elastic member in the vibration direction, which further increases the outer diameter of the dynamic damper. on the other hand,
In order to increase the mass of the mass member, it is necessary to increase the mass member, and especially when it is necessary to set the natural frequency of the dynamic damper low, avoid increasing the outer diameter of the dynamic damper. I couldn't do it. The dynamic damper is an additional device, and it is desired that the dynamic damper be downsized while maintaining a predetermined performance due to restrictions such as mounting space. However, as described above, it is difficult to reduce the size of the conventional dynamic damper while maintaining the predetermined performance. On the contrary, when the natural frequency needs to be lowered, the outer diameter becomes larger. There was also the problem of becoming.

Therefore, it is an object of the present invention to reduce the size of the shape while maintaining the performance as a dynamic damper and to simplify the mounting.

[Means for Solving the Problem] A dynamic damper according to a first aspect of the present invention is a dynamic damper according to the first aspect, wherein a pair of ring-shaped fixing members are inserted into and supported by a rotary shaft at predetermined intervals in the axial direction, and an outer peripheral surface of the rotary shaft. A cylindrical mass member that has a larger inner surface and is inserted into the rotary shaft and is arranged between a pair of the fixing members, and each of the fixing members and each axial end of the mass member adjacent to the fixing member. The mass member is connected integrally, and the mass member can be displaced in the radial direction between the inner peripheral surface of the mass member and the outer peripheral surface of the rotating shaft over substantially the entire axial direction of the mass member. It is characterized in that it has a pair of elastic members that define an annular space.

The dynamic damper according to the second aspect is the first damper.
The dynamic damper according to claim 1, characterized in that it has one slit extending parallel to the axis, and has a bending means for facilitating opening and closing of the slit in a portion which is substantially axially symmetrical with respect to the slit. To be done.

[Operation] In the dynamic damper of the present invention, the mass member and the pair of fixing members are arranged in a state where there is no overlapping portion in the radial direction of the rotating shaft, and a predetermined width is provided between the mass member and the rotating shaft. The void is formed. The elastic member that supports the mass member connects the shaft end of each fixing member and the shaft end of the mass member. That is, the members of the dynamic damper of the present invention are arranged side by side in the axial direction of the rotating shaft. Therefore, the outer diameter of the dynamic damper is substantially the same as the radius of the rotary shaft plus the thickness of the mass member, and can be significantly smaller than the outer diameter of the conventional dynamic damper. Further, since the elastic member supports the mass member from the lateral direction with respect to the vibration direction, the support becomes shear support, and the spring constant thereof is given by the shear spring constant. The shear spring constant varies depending on its shape, but as shown in FIG. 8, its value is a fraction to several hundredths, which is considerably smaller than the compression / tensile spring constant. Therefore, in the dynamic damper of the present invention, since the spring constant can be lowered, it is possible to reduce the mass and size, particularly the outer diameter dimension, while maintaining the predetermined performance.

Further, S is called a shape ratio, and is given by S = pressure receiving area / free surface area, so that the shape of the elastic member can be appropriately changed according to the natural frequency to be set.

In this way, the shape of the dynamic damper of the present invention can be greatly reduced. Further, since there is no member for restraining the outer peripheral surface of the fixing member, it is easier to insert and mount the present dynamic damper through the rotary shaft, as compared with the conventional dynamic damper, and the workability of insertion work can be improved. .

In addition to these actions, by forming a protrusion on the inner peripheral surface of the mass member, it is possible to reduce the impact at the time of excessive amplitude or reduce the performance deterioration at the time of excessive amplitude.

Further, according to the second aspect, by forming a slit extending in parallel with the axial direction in the dynamic damper, the dynamic damper can be mounted on the rotary shaft without being inserted from the shaft end of the rotary shaft. , The workability can be greatly improved.

Example 1 Example 1 according to the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view of the dynamic damper of the first embodiment cut in parallel with the mounting axis,
FIG. 2 is a right side view thereof. FIG. 3 is a mounting state diagram of the first embodiment.

The dynamic damper of the first embodiment is used for damping a drive shaft of an automobile, and is a dynamic damper of a type that is press-fitted and attached to the drive shaft.

The dynamic damper 1 of the first embodiment is supported by being inserted through a drive shaft S, which is a rotating shaft, at a predetermined interval.
A pair of fixing members 11, 11 having an inner peripheral surface larger than the outer peripheral surface of the drive shaft S and a pair of fixing members 11, 11
The mass member 12 disposed between the fixing members 11 and 1
1 and elastic members 13, 13 that integrally connect each end of the mass member 12. The overall shape is a cylindrical shape with the outer diameter of the central portion being larger than the outer diameters of both end portions. Here, the mass member 12 corresponds to the central portion, and the fixing members 11 and 11 correspond to both end portions. The elastic members 13, 13 correspond to connecting portions connecting the central portion and both end portions with an inclination.

The fixing members 11 and 11 are formed in a ring shape and are used as a pair, and are made of a rubber material such as natural rubber. The diameter of the inner peripheral surface forming the central axis hole of the ring-shaped fixing member 11 is
It is about 1 mm smaller than the diameter of the outer peripheral surface of the drive shaft S. A ring-shaped locking groove 11a is formed on the outer peripheral surface of the fixing member 11.

The mass member 12 is formed by coating a metal mass body such as a cylindrical thick-walled steel pipe with a rubber material such as natural rubber on both the outer peripheral surface and the inner peripheral surface with a thickness of about 1 mm, and is provided on the outer periphery of the drive shaft S. To be done. Between the inner peripheral surface of the mass member 12 and the outer peripheral surface of the drive shaft S, an annular space (about 1 mm) is formed over the entire axial length of the mass member 12 that allows the mass member 12 to be displaced in the radial direction. A gap of 0.5 mm) is formed. If this gap is about 1 to 2 mm, its function can be sufficiently fulfilled.

The elastic member 13 has a hollow truncated cone shape formed of a rubber material such as natural rubber, and integrally connects the fixing member 11 and the mass member 12. That is, the inner peripheral surface 1 of the elastic member 13
3a shows the inner peripheral surface of the mass member 12 having a gap of about 1.5 mm from the outer peripheral surface of the drive shaft S while gradually increasing the inner diameter from the inner peripheral surface end of the fixing member 11 that is in close contact with the drive shaft S. It is tapered toward the end. The outer peripheral surface 13b of the elastic member 13 is fixed to the fixing member 11
The engaging groove 11a is formed so that its outer diameter is gradually increased from the end of the engaging groove 11a formed on the outer peripheral end of the mass member 12.

The rubber coatings on both the fixing members 11, 11, the elastic members 13, 13 and the mass member 12 are integrally vulcanized and molded.

The dynamic damper 1 of the first embodiment configured as described above is used as follows. First, when the dynamic damper 1 is attached to the drive shaft S, the insertion opening in the fixing member 11 of the dynamic damper 1 is aligned with the axial end of the drive shaft S before the drive shaft S is attached to the vehicle body. Since the diameter of the inner peripheral surface of the fixing member 11 is smaller than the outer diameter of the drive shaft S by about 1 mm, the drive shaft S spreads the inner peripheral surface of the fixing member 11 made of a rubber material and press-fits it. To be done. After arranging the dynamic damper 1 at a predetermined position, the locking groove 11 formed in both the fixing members 11, 11.
a and 11a are stainless steel fixing bands 11b and 11
The dynamic damper is attached to the drive shaft by fixing with b. The fixing band 11
b is not limited to stainless steel as long as it can be firmly fixed.

When the drive shaft S rotates and the harmful vibration is excited, the mass member 12 of the dynamic damper 1 in which the natural frequency is adapted to the frequency of the harmful vibration resonates. The adjustment of the natural frequency is performed by changing the shape of the elastic member 13, but the elastic member 13 is separated from the outer peripheral surface of the drive shaft S and reaches the end of the thick steel pipe of the mass member 12. The length of the elastic member 13 greatly affects its natural frequency. The longer the length of the elastic member is, the smaller the shear spring constant of the elastic member 13 is. Therefore, the natural frequency is lower, and conversely, the shorter the length of the elastic member is, the higher the natural frequency is. The dynamic damper 1 thus formed can resonate the mass member 12 to absorb the vibration energy of the drive shaft S and suppress the harmful vibration excited in the drive shaft S.

Second Embodiment Next, a second embodiment will be described with reference to FIG.

The dynamic damper of the second embodiment is used for damping the drive shaft of an automobile as in the first embodiment.
The first embodiment is added with the impact mitigation at the time of excessive amplitude and the automatic adjustment function of suppressing the excessive amplitude within a certain limit.

The dynamic damper 2 of the second embodiment has the same configuration as that of the first embodiment except that the shape of the mass member is different.

The mass member 22 is formed by coating a metal mass such as a ring-shaped thick-walled steel pipe with a rubber material such as natural rubber to a thickness of about 1 mm on both the outer peripheral surface and the inner peripheral surface.
2a is formed. The protrusion 22a has a substantially conical shape, and a gap having a maximum amplitude value of the mass member 22 in the use range of the dynamic damper is formed between the pointed portion and the outer peripheral surface of the drive shaft S. . Further, when the projection 22a is compressed from the pointed portion, it has a non-linear compression spring constant that is small when the amount of compression is small and increases with the amount of compression. The other fixing members 21 and elastic members 23 have the same configurations as in the first embodiment.

Next, the effect added by forming the protrusion will be described.

When the magnitude of vibration from the drive shaft S is within the use range of the dynamic damper 2, the protrusion 22a of the mass member 22 and the outer peripheral surface of the drive shaft S do not come into contact with each other. The same operation as the dynamic damper 1 is performed.

When the mass member 22 excessively responds to the vibration from the drive shaft S, the protrusion 22a of the mass member 22 is brought into contact with or compressed by the drive shaft S to absorb and mitigate the impact at the time of the collision. When excessive vibration is continuously input to some extent, the mass member 22 of the dynamic damper 2 vibrates while the protrusion 22a is periodically compressed.
The natural frequency of the dynamic damper 2 is basically determined by the mass of the mass member 22 and the spring constant that supports this mass in the vibration direction. In the second embodiment, the mass of the mass member 22 is constant, but the spring constant differs depending on the amplitude value of the mass member 22. The mass member 22 has a substantially constant value in a proper vibration range, that is, in a range in which the protrusion 22a does not contact the drive shaft S. However, the mass member 22
Of the drive shaft S due to the excessive amplitude of
When compressed by contacting the
It is a value obtained by adding the nonlinear compression spring constant of the protrusion 22a to the shear spring constant of 3. The natural frequency of the dynamic damper 2 is the same as the vibration excited in the drive shaft S in a range where the protrusion 22a does not contact the drive shaft S. However, when the projection 22a comes into contact with or is compressed by the drive shaft S, the natural frequency of the dynamic damper 2 increases because the spring constant increases as the amount of compression increases. In this case, since the natural frequency of the dynamic damper 2 is different from the frequency excited in the drive shaft S, its response amplitude amount is small. As a result, the amount of compression of the protrusion 22a decreases, and the natural frequency approaches the original value. After such transient response, it becomes a steady response having a constant response amplitude.

As described above, the dynamic damper of the second embodiment has a function of automatically adjusting to a proper response amplitude even when excessive vibration is input. At this time, although the vibration damping performance is somewhat lowered, it is possible to play a role as a dynamic damper over a wide input amplitude range, and it is possible to prevent adverse effects on the drive shaft and the dynamic damper.

Regarding the number of protrusions, the magnitude of the response amplitude to be set,
Also, it is determined from the stability. Further, as for the shape, if it has a non-linear spring constant having the above-mentioned characteristic, the whole shape can be formed into another shape such as a stripe shape.

Third Embodiment Next, a third embodiment will be described with reference to FIGS. 5 and 6.

FIG. 5 is a front view of the dynamic damper of the third embodiment, and FIG.
The figure is also a side view thereof. FIG. 7 is a mounting state diagram of the third embodiment. The upper half of each figure is a sectional view.

The dynamic damper of the third embodiment is used for damping a drive shaft of an automobile as in the case of the first and second embodiments, and is particularly easy to mount on the drive shaft.

The dynamic damper 3 of the third embodiment includes the fixing member 31,
31, the mass member 32, and the elastic members 33, 33, and the configuration is substantially the same as that of the first embodiment. Therefore, only different points will be described here.

The dynamic damper 3 of the third embodiment has a structure in which a slit 34 extending in parallel to the axis is formed in the dynamic damper of the first embodiment, and a cross section perpendicular to the axis is C-shaped. In the axially symmetrical portion of the slit 34, a bendable groove-shaped bent portion (folding means) 35 is formed so as to extend parallel to the axis. Further, a ring-shaped locking groove 31 is formed on the outer peripheral surfaces of the fixing members 31, 31.
a and 31 a are formed, and a ring-shaped locking groove 32 a is also formed on the outer peripheral surface of the mass member 32. In order to fix the dynamic damper 3 to the drive shaft S, the fixing grooves 31a and 32a made of stainless steel, which are connecting means for closing and connecting the slit 34, are made of stainless steel.
2b is wound.

The mass member 32 forming a part of the bent portion 35 is divided in the axial direction at a predetermined interval so as not to obstruct the bending. In addition, also in the fixing member 31, it is possible to form a substantially U-shaped recessed portion on the outer peripheral surface which is a part of the bent portion 35 in order to facilitate opening and closing. In addition, a finger hook portion 36 for facilitating opening and closing with fingers is formed along the slit 34 in the portion of the mass member 32 that is a part of the slit 34.

The dynamic damper 3 of the third embodiment is used as follows. A finger or the like is hung on the finger hooking portion 36 formed in the mass member 32 portion of the slit 34 of the dynamic damper 3, and the bending portion 35 is pivoted outward and pivoted outward. Then, the slit 34 having a large opening of the dynamic damper 3 is aligned with a predetermined mounting position of the drive shaft S,
It is attached to the drive shaft S. Close the slit 34,
Fixing bands 31b and 32 made of stainless steel which are connecting means
b is the locking groove 31a of the fixing member 31, the mass member 3
It is wound around and fixed to the second locking groove 32a. Fixed band 31
b and 32b have sufficient rigidity other than stainless steel,
Other materials can be used as long as they can be securely fixed.

The subsequent steps are the same as in the first embodiment. The removal of the dynamic damper 3 from the drive shaft S is performed in the reverse order of the above.

[Effects of the Invention] As is clear from the above description, the dynamic damper of the present invention has a structure in which the elastic member shears and supports the mass member, and thus can be made significantly smaller than the conventional dynamic damper. . Furthermore, by making it possible to open and close these dynamic dampers in parallel with the axis, a simple attachment could be realized.

As described above, the dynamic damper of the present invention can make the dynamic damper smaller, and can greatly contribute to the improvement of stability and workability.

[Brief description of drawings]

FIG. 1 is a front sectional view of a dynamic damper according to a first embodiment of the present invention, FIG. 2 is a right side view of the same, and FIG. 3 is its mounting state diagram. FIG. 4 is a front view of the dynamic damper according to the second embodiment, FIG. 5 is a front view of the dynamic damper according to the third embodiment, FIG. 6 is a side view of the same, and FIG. FIG. 8 is a characteristic diagram showing a spring constant ratio between compression (tensile) and shear of the elastic member. 9th
The figure is a schematic view of a conventional dynamic damper. 1, 2, 3 ... Dynamic damper 11, 21, 31 ... Fixing member 12, 22, 32 ... Mass member 13, 23, 33 ... Elastic member 22a ... Protrusion 31b, 32b .. Means) 34 ... Slit

Claims (2)

[Claims] 1. A pair of ring-shaped fixing members that are inserted into and supported by a rotating shaft at a predetermined interval in the axial direction, and an inner peripheral surface that is larger than an outer peripheral surface of the rotating shaft and are inserted into the rotating shaft. A cylindrical mass member arranged between a pair of the fixing members, and integrally connecting each fixing member and each shaft end of the mass member adjacent to the fixing member, and A pair of elastic members defining an annular space extending substantially over the entire length in the axial direction of the mass member, which enables the mass member to be displaced in the radial direction between the inner peripheral surface and the outer peripheral surface of the rotating shaft; A dynamic damper characterized by having. 2. Having one slit extending parallel to the axis,
2. The dynamic damper according to claim 1, further comprising bending means for facilitating opening and closing of the slit in a portion of the slit that is substantially axially symmetrical.