JP2004162754A - Transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission capable of preventing resonance of a case and a gear irrespective of the number of teeth of the gear stored in the case and rotation speed. <P>SOLUTION: This transmission 10 is provided with a gear transmission mechanism (not shown) for decelerating rotation of an input shaft 12 and transmitting it to an output shaft 14, the case 16 storing the gear transmission mechanism, and a weight member 18 attachable and detachable to/from the case 16 to adjust natural frequency of the case 16 by attaching and detaching the weight member 18. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission provided in industrial equipment, transportation equipment, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, in industrial equipment and transportation equipment, a transmission including a gear transmission mechanism and a case for housing the gear transmission mechanism has been widely used.
[0003]
The gear transmission mechanism generates vibrations and noises according to the number of teeth, the rotation speed, and the like when the gears mesh with each other. If the frequency of the vibration caused by the gear and the natural frequency of the other members such as the shaft and the case have the same or nearly integral multiple, the shaft and the case and the gear resonate, increasing the vibration and noise. Sometimes.
[0004]
In particular, the case is large relative to other members of the transmission, and the wall surface is liable to amplify the sound. Therefore, when the case and the gear resonate, vibration and noise may be significantly increased.
[0005]
In order to prevent such vibration and noise, there is known a transmission in which the rigidity of the wall of the case is increased to increase the natural frequency and the amplitude of resonance is suppressed to prevent resonance between the case and the gear. (For example, see Patent Documents 1 and 2).
[0006]
[Patent Document 1]
JP 2001-124187 A (all pages)
[Patent Document 2]
JP-A-50-125159 (page 342)
[0007]
[Problems to be solved by the invention]
However, the case of a transmission generally has a complicated shape, and it is not easy to perform a structural analysis for obtaining a relationship between the shape and the natural frequency. Furthermore, since the shape of the case is limited by the contents of the gear transmission mechanism and the like, the installation environment, etc., even if a highly rigid shape can be estimated by structural analysis, the shape must be realized as an actual product. Sometimes you can't. Under such circumstances, a great deal of labor and time were required to design a case having high rigidity.
[0008]
In addition, a plurality of types of transmissions having different speed ratios are often set as a series of series so as to be compatible with various uses. On the other hand, since the case is expensive, a case having a common design is often used for a plurality of types of transmissions in the same series. That is, there are cases where gears having various numbers of teeth are accommodated in one type of case.
[0009]
Therefore, even if it is possible to prevent the resonance between the case and the gears in some types of transmissions of the series by increasing the rigidity of the case and increasing the natural frequency, gears having different numbers of teeth are used in the case. In other types of transmissions accommodated, the case and the gear sometimes resonated. Further, even with the same type of transmission, the rotation speed of the gear is not always constant, and can rotate at various rotation speeds depending on the application and the like. Therefore, even in the same type of transmission, if the rotation speed of the gear is different, the case and the gear may resonate.
[0010]
If various types of cases are prepared and the most suitable case is selected according to the number of gear teeth to be accommodated and the rotational speed, resonance between the case and the gears can be prevented. Cost will increase significantly.
[0011]
The present invention has been made in view of the above problems, and is a low-cost transmission that can prevent resonance between a case and a gear, regardless of the number of teeth and the rotation speed of the gear housed in the case. To provide
[0012]
[Means for Solving the Problems]
The present invention provides a transmission including a gear transmission mechanism and a case accommodating the gear transmission mechanism, comprising a weight member detachably attached to the case, and attaching and detaching the weight member. The above problem has been solved by making the natural frequency of the case adjustable.
[0013]
Conventionally, it has been attempted to prevent the resonance between the case and the gear by suppressing the amplitude by increasing the natural frequency by increasing the rigidity of the case. On the other hand, the present invention focuses on the fact that the natural frequency is affected not only by the rigidity but also by the mass (inertia), and increases / decreases (adjusts) the natural frequency by attaching / detaching the weight member to / from the case. It was made.
[0014]
That is, the present invention focuses on the mass, and not in the direction of increasing the natural frequency of the case, but in many cases, lowering the natural frequency of the case to prevent resonance between the case and the gear. Significantly different from technology.
[0015]
Note that a member having a complicated shape such as a case generally has many vibration modes. However, in this specification, "adjustable natural frequency of the case" does not necessarily mean that all vibration modes of the case are used. It is not limited to the meaning that the natural vibration can be adjusted, and also includes a case where the natural vibration of some vibration modes can be adjusted.
[0016]
The adjustment of the natural frequency can be performed, for example, by actually attaching and detaching the weight member so as to reduce the noise while actually operating the transmission to measure the noise, vibration, etc., and this operation is easy, and Thus, resonance between the case and the gear can be reliably prevented.
[0017]
In addition, since the natural frequency of the case is adjustable, it is not necessary to strictly analyze the natural frequency of the case at the design stage, and the case can be easily designed. Further, since the weight member only needs to be able to change the mass of the case, the degree of freedom of design is high and the manufacture is easy. For example, if the weight member is a plate-shaped body such as a square or a circle, design and manufacture are extremely easy. Further, the weight member may be mounted on the case by using a bolt or the like, and the attaching / detaching operation is easy. That is, in the transmission according to the present invention, the weight member and the case are easily designed and manufactured, and the cost is low.
[0018]
Preferably, the weight member can be mounted near the center of the wall surface of the case.
[0019]
In the process of completing the present invention, the inventor tried to attach weight members to various parts of the case. As a result, it has been found that even when the weight members have the same mass, the change (decrease) in the natural frequency is larger when the weight member is mounted near the center of the wall surface of the case than when the weight member is mounted on another part. In other words, when obtaining the same natural frequency change, if the weight member is mounted near the center of the wall of the case, it is sufficient to attach and detach a weight member having a smaller mass than when mounting it on other parts. The weight member can be reduced in weight and size.
[0020]
In addition, a plurality of types of weight members having different masses and a common arrangement for mounting to the case are prepared, and a weight of the plurality of types of weight members to be mounted on the case is prepared. The natural frequency of the case may be adjustable by selecting the type of the weight member.
[0021]
Thus, if a plurality of types of weight members having different masses are prepared, the natural frequency of the case can be adjusted appropriately and variously, and the present invention can be applied to various types of transmissions having different gear frequencies.
[0022]
In this case, a plurality of types of weight members having different materials and the same outer shape may be prepared as the weight member.
[0023]
For example, if a plurality of types of weight members having different specific gravities and the same shape such as an iron-based material and an aluminum-based material are prepared, regardless of the type of the weight member to be selected, the shape of the transmission is always changed. Can be kept constant. In particular, if a recess having a size large enough to incorporate the weight member is formed in the case as a mounting portion for the weight member, the weight member always projects from the case regardless of the type of the weight member selected. Can be avoided. As a result, interference with peripheral members can be reliably avoided, and a transmission having the same outer shape as a conventional transmission can be provided.
[0024]
Further, by preparing a plurality of the weight members, and by allowing any number of weight members of the plurality of weight members to be mounted on the case, by adjusting the number of mounting of the weight members, The natural frequency of the case may be adjustable.
[0025]
In this way, the present invention can be applied to various types of transmissions having different frequencies of the gears while limiting the increase in the types of weight members. For example, it is possible to adjust the natural frequency of the case in multiple steps by preparing a plurality of one type of weight members having the same shape and changing the number of these members.
[0026]
Further, the weight member may be attachable to the case by magnetic force.
[0027]
By utilizing the magnetic force, the work of attaching and detaching the weight member can be greatly facilitated. Also, the manufacture of the case and the weight member is easy. For example, when the material of the case is a magnetic material such as an iron-based material, if a magnet is provided on the weight member side, the weight member can be detachably attached to the case without forming a bolt hole or the like on the case side. can do. In this case, for example, the present invention can be applied to an existing case. When the material of the case is a non-magnetic material such as an aluminum-based material, a magnet may be provided on the case side, and the material of the weight member may be a magnetic material. Further, a magnetic material attaching portion may be provided in a non-magnetic material case, and a magnet may be provided on the weight member side. Further, magnets may be provided on both sides of the case and the weight member.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0029]
FIG. 1 is a front view showing an outline of the overall structure of a transmission 10 according to the present embodiment, and FIG. 2 is a left side view of the same.
[0030]
The transmission 10 includes a gear transmission mechanism (not shown) for reducing the rotation of the input shaft 12 and transmitting the rotation to the output shaft 14, a case 16 accommodating the gear transmission mechanism, and a weight detachably attached to the case 16. And a weight member 18, and the natural frequency of the case 16 can be adjusted by attaching and detaching the weight member 18.
[0031]
The other structures are the same as those of the conventional transmission, and the description thereof will not be repeated.
[0032]
Note that the transmission 10 is mainly used for industrial machines, and a series of transmissions together with a plurality of other types of transmissions accommodating gear transmission mechanisms having different specifications such as a speed ratio are provided in a case having a common design with the case 16. Make up the series.
[0033]
The gear transmission mechanism specifically includes a bevel gear, a hypoid gear, a worm gear, and other types of gears, and changes the direction of the rotational force to transmit.
[0034]
The case 16 includes a box-shaped lower case 20 opened upward and an upper case 22 that closes an upper part of the lower case 20.
[0035]
The weight member 18 can be mounted near the center of the wall surface 20A on the front of the lower case 20.
[0036]
FIG. 3 is an exploded perspective view showing the structure around the mounting portion of the weight member 18 in an enlarged manner.
[0037]
The weight member 18 is specifically a rectangular plate-like body, and has a plurality of through holes 18A. A plurality of screw holes 20B are formed near the center of the wall surface 20A of the lower case 20 corresponding to the through holes 18A. The weight member 18 can be mounted near the center of the wall surface 20A by a bolt 24 that penetrates the through hole 18A and is screwed into the screw hole 20B.
[0038]
In addition, a plurality of types of weight members 18 having different masses and having a through hole 18A at a common position (a common arrangement for attachment to the case 16) are prepared. Specifically, a plurality of types of weight members 18 having different thicknesses are prepared.
[0039]
Next, the operation of the transmission 10 will be described.
[0040]
The transmission 10 can adjust the natural frequency of the case 16 by attaching and detaching the weight member 18 to and from the case 16, and can prevent resonance between the gears in the case 16 and the case 16.
[0041]
For example, when the weight member 18 is attached to the case 16, the natural frequency of the vibration mode mainly related to the wall surface 20A of the lower case 20 among the vibration modes of the case 16 decreases. On the other hand, when the weight member 18 is removed from the case 16, the natural frequency increases. Further, if the type of the weight member 18 mounted on the wall surface 20A is changed, a natural frequency corresponding to the mass of each weight member 18 can be obtained.
[0042]
The resonance between the case 16 and the gear occurs when the frequency of the vibration caused by the gear and the natural frequency of the case 16 have a relationship that is equal to or close to an integral multiple. By adjusting the natural frequency of the case 16 from the above, resonance between the case 16 and the gear can be prevented.
[0043]
The natural frequency can be adjusted by, for example, actually operating the transmission 10 and attaching and detaching the weight member 18 to and from the case 16 while actually measuring noise, vibration, and the like. This operation is easy if the member 18 is mounted on (or removed from) the case 16. In addition, since the adjustment is made while checking the noise, vibration and the like, the resonance between the case 16 and the gear can be reliably prevented.
[0044]
The case 16 and the gears may resonate when the rotational speed of the accommodated gears increases or decreases due to a change in the use of the transmission 10 or the like. However, by attaching or detaching the weight member 18, the natural frequency is increased or decreased to resonate. Can be easily avoided.
[0045]
In addition, since the natural frequency of the case 16 is adjustable and it is not necessary to strictly analyze the natural frequency of the case at the design stage, the design of the case 16 is easy. Further, the weight member 18 is also a rectangular plate-shaped body, and is very easy to design and manufacture. That is, in the transmission 10, the design and manufacture of the weight member 18 and the case 16 are easy and the cost is low.
[0046]
It should be noted that in the other types of transmissions in the same series as the transmission 10, the resonance between the case and the gears can be easily avoided by adjusting the natural frequency of the case in the same manner as described above. That is, regardless of the number of gear teeth to be accommodated and the rotational speed, a common case that is easy to design and low in cost is used for a plurality of types of transmissions, and resonance between the case and the gear is easily avoided. As a series of transmissions, the effect of cost reduction is particularly large.
[0047]
In addition, since the weight member 18 is mounted in the vicinity of the center of the wall surface 20A of the lower case 20, when obtaining the same change in the natural frequency, the weight member 18 is attached and detached rather than mounted on other parts of the wall surface 20A. A small change in mass is sufficient, and the weight member 18 is reduced in weight and size accordingly.
[0048]
Next, a second embodiment of the present invention will be described.
[0049]
FIG. 4 is an exploded perspective view showing the periphery of the mounting portion of the weight member according to the second embodiment.
[0050]
In the second embodiment, a plurality of weight members 18 of the same type are prepared, and an arbitrary number of the weight members 18 among the plurality of weight members 18 can be attached to a case. The natural frequency of the case 16 can be adjusted by adjusting the number of mountings 18.
[0051]
The other configuration is the same as that of the first embodiment, and the description is omitted.
[0052]
Also in this case, similarly to the first embodiment, resonance between the case 16 and the gear can be easily prevented.
[0053]
Further, since the weight member 18 is shared by one type, the weight member 18 is further reduced in cost.
[0054]
Next, a third embodiment of the present invention will be described.
[0055]
FIG. 5 is an exploded perspective view showing the periphery of the mounting portion of the weight member according to the third embodiment.
[0056]
In the third embodiment, the material of the weight member 40 is a magnet, and the weight member 40 can be attached to the case 16 by magnetic force. The weight member 40 has the same shape as the weight member 18, but has no through hole. The case 16 is made of a magnetic material such as an iron-based material.
[0057]
The other configuration is the same as that of the first embodiment, and the description is omitted.
[0058]
If the magnetic force is used in this way, it is not necessary to use bolts or the like to attach the weight member 40 to the case 16, and the work of attaching and detaching the weight member can be performed more easily. Further, since it is not necessary to form a screw hole and a through hole in the case 16 and the weight member 40, the case and the weight member can be manufactured easily and at low cost.
[0059]
Furthermore, if the material of the case is a magnetic material such as an iron-based material, the case can be easily mounted on the weight member 40 in other transmissions. Can also be prevented.
[0060]
In the third embodiment, the entire weight member 40 is a magnet, but the present invention is not limited to this, and a magnet may be provided as a part of the weight member. The case 16 is made of a magnetic material such as an iron-based material, but the present invention is not limited to this. The case is made of a non-magnetic material such as an aluminum-based material and a magnet is provided on the case side. The weight member may be provided as a magnetic material. Alternatively, a magnetic material mounting portion may be provided in a non-magnetic material case, and part or all of the weight member may be a magnet. Further, magnets may be provided on both the case and the weight member.
[0061]
In the third embodiment and the first embodiment, a plurality of types of weight members 18 and 40 having different thicknesses are prepared. However, the present invention is not limited to this, and the material is not limited thereto. A plurality of different weight members 18 and 40 having different and equal outer shapes may be prepared and selectively mounted on the case.
[0062]
For example, if a plurality of types of weight members 18 and 40 having different specific gravities and the same shape such as an iron-based material and an aluminum-based material are prepared, regardless of the type of weight member to be mounted, the transmission can be used. The shape can always be kept constant. In particular, as shown in FIG. 6, if a concave portion 20C large enough to incorporate the weight member 18 is formed in the lower case 20 as a mounting portion for the weight member 18, regardless of the type of the weight member 18 to be selected. In addition, it is possible to always prevent the weight member 18 from protruding from the case 16. As a result, interference with peripheral members can be reliably avoided, and the external shape can be made equal to that of a conventional transmission.
[0063]
In the third embodiment and the first embodiment, one of a plurality of types of weight members is selectively mounted on the case 16, but the present invention is not limited to this. Instead, a plurality of types of weight members may be combined and simultaneously mounted on the case 16 as in the second embodiment.
[0064]
In the first to third embodiments, each of the weight members is a rectangular plate, but the shape of the weight member is not particularly limited. For example, another weight such as a circular plate may be used. A weight member having a shape may be used. Furthermore, a plurality of types of weight members having different shapes may be prepared. Also in this case, it is preferable that the arrangement for mounting the weight members is common.
[0065]
In the first and second embodiments, the weight member can be attached to the case by bolts. However, the attachment method is not particularly limited as long as the weight member can be attached and detached.
[0066]
In the first to third embodiments, the weight members 18 and 40 can be mounted near the center of the wall surface 20A of the case 16, but the present invention is not limited to this. The weight member may be attached to another portion of the 20A. In order to effectively change the natural frequency, the mounting portion of the weight member is preferably close to the center of the wall surface.
[0067]
Furthermore, in the first to third embodiments, the weight members 18 and 40 can be mounted on the wall surface 20A on the front surface of the lower case 20, but the present invention is not limited to this, and The portion to which the weight member is attached may be appropriately selected according to the vibration mode in which the frequency is to be adjusted.
[0068]
In the first to third embodiments, the transmission is a reduction gear that reduces the rotation of the input shaft and transmits the rotation to the output shaft. However, the transmission increases the rotation of the input shaft and transmits the rotation to the output shaft. The present invention is naturally applicable to a high speed machine.
[0069]
In the first to third embodiments, the gear transmission mechanism includes gears such as a bevel gear, a hypoid gear, and a worm gear that change the direction of rotation and transmit the rotation. However, the type of gear is not particularly limited. The present invention is naturally applicable to a transmission having other types of gears such as a spur gear, a bevel gear, and the like. Furthermore, the present invention is not limited to the field of industrial machinery, but is naturally applicable to, for example, transportation equipment.
[0070]
In the first to third embodiments, the transmission 10 is one of a series of transmissions having a common case design, but the present invention is not limited to this. However, the present invention is naturally applicable to a transmission that is set independently without being serialized.
[0071]
(Example)
FIG. 7 shows the relationship between the input rotation speed and the noise in the transmission 10 in comparison with the case where the weight member 18 is mounted and the case where the weight member 18 is not mounted.
[0072]
It can be seen that when the input rotation speed is near 1500 rpm, the noise value is significantly reduced when the weight member is mounted, compared to when the weight member is not mounted.
[0073]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a low-cost transmission that can prevent resonance between the case and the gears regardless of the number of teeth and the rotation speed of the gears housed in the case. An excellent effect is obtained.
[Brief description of the drawings]
FIG. 1 is a front view showing an entire structure of a transmission according to an embodiment of the present invention. FIG. 2 is a left side view of the transmission. FIG. 3 is an exploded view showing an enlarged structure around a mounting portion of a weight member of the transmission. FIG. 4 is an exploded perspective view showing, on an enlarged scale, a peripheral structure of a weight member mounting portion according to another embodiment of the present invention. FIG. 5 is a mounting diagram of a weight member according to another embodiment of the present invention. FIG. 6 is an exploded perspective view showing, in an enlarged manner, a peripheral structure of a portion. FIG. 6 is a side cross-sectional view showing, in an enlarged manner, a peripheral structure of a mounting portion of a weight member according to another embodiment of the present invention. Graph showing the relationship between the attachment and detachment of the weight member and the noise level [Explanation of reference numerals]
DESCRIPTION OF SYMBOLS 10 ... Transmission 12 ... Input shaft 14 ... Output shaft 16 ... Case 18, 40 ... Weight member 18A ... Through hole 20 ... Lower case 20A ... Wall surface 20B ... Screw hole 22 ... Upper case 24 ... Bolt

Claims (6)

In a transmission including a gear transmission mechanism and a case accommodating the gear transmission mechanism,
A transmission, wherein the case is provided with a detachable weight member, and the natural frequency of the case can be adjusted by attaching and detaching the weight member. In claim 1,
A transmission, wherein the weight member can be mounted near a center of a wall surface of the case. In claim 1 or 2,
A plurality of types of the weight members having different masses and a common arrangement for mounting to the case are prepared, and a weight to be mounted to the case among the plurality of types of weight members. A transmission characterized in that the natural frequency of the case can be adjusted by selecting the type of member. In claim 3,
A transmission, wherein a plurality of types of weight members having different materials and the same outer shape are prepared. In any one of claims 1 to 4,
A plurality of the weight members are prepared, and an arbitrary number of the weight members among the plurality of the weight members can be attached to the case, and by adjusting the number of the weight members attached, A transmission, wherein the natural frequency of the case is adjustable. In any one of claims 1 to 5,
A transmission, wherein the weight member is attachable to the case by magnetic force.

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