Abstract:
A shock absorbing device that has high strength rigidity and good attenuation characteristics, that can be reduced in weight and size, is free from degassing, and has stable temperature characteristics. The device connects between a first and second member so as to be applicable to shock absorption therebetween, and includes: a first and a second shock absorbing member; and a holding and connecting mechanism which holds the first member via the first and second shock absorbing members and which is connected to the second member. The first shock absorbing member, the first member, and the second shock absorbing member are disposed in that order. The holding and connecting mechanism sandwiches the first shock absorbing member, the first member, and the second shock absorbing member from outside the first and second shock absorbing members, thereby holding the first member while applying stress to the first and second shock absorbing members.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a shock absorbing device. Particularly, the present invention relates to a shock absorbing device having high strength and rigidity and excellent attenuation characteristic, a shock absorbing device enabling miniaturization and weight reduction to be realized, a shock absorbing device free from worry about degassing, and a shock absorbing device having stable damping and stiffness characteristics in wide temperature range. 
         [0003]    2. Description of the Related Art 
         [0004]    JP-A-2012-197864 (Patent Document 1) discloses a hysteretic damper having shape self-restoration capability added thereto by tensile force of a super elastic alloy. The hysteretic damper comprises a first super elastic alloy member to which a tensile force acts under tension and a second super elastic alloy member to which a tensile force acts under compression, has a structure for carrying out self-restoration of a damper shape by the first super elastic alloy member and the second super elastic alloy member, and characteristics under tension and compression can be set freely. 
       SUMMARY OF THE INVENTION 
       [0005]    As a basic characteristic required for a shock absorbing device, there should be noted attenuation of vibration while maintaining high strength and rigidity, stable temperature characteristic and so on. Additionally, a shock absorbing device used for an aerospace field is required to be small in size and weight, and to decrease degassing procedures and so on. For example, however, a shock absorbing device which is suitable for an aerospace field, small in size and weight, and has high strength and rigidity and excellent attenuation characteristic has not yet been necessarily provided. Additionally, for use in the aerospace field, it is necessary to consider degassing from the shock absorbing device, and also consideration should be made for stability of the temperature characteristic. 
         [0006]    An object of the present invention is to provide a shock absorbing device having high strength and rigidity and excellent attenuation characteristic. Furthermore, another object of the present invention is to provide a shock absorbing device enabling miniaturization and weight reduction to be realized. A further object of the present invention is to provide a shock absorbing device free from worry about degassing, and also, a shock absorbing device having stable temperature characteristic. 
       SUMMARY OF THE INVENTION 
       [0007]    In order to solve the above problems, according to the present invention, there is provided a shock absorbing device for connecting a first member and a second member, and applicable for shock between said first member and said second member, comprising; first cushioning members and second cushioning members, and a holding connecting mechanism for holding said first member through said first cushioning members and said second cushioning members, and being connected to said second member, wherein said first cushioning members, said second cushioning members and said first member are arranged in order of said first cushioning members, said first member and said second cushioning members, said holding connecting mechanism holds said first member by clamping said first cushioning members, said first member and said second cushioning members from outside of said first cushioning members and said second cushioning members while adding stress to said first cushioning members and said second cushioning members, and said first member and said second member are connected thereby. 
         [0008]    When said first member is a plate material comprising a first surface and a second surface which is an opposite surface of said first surface, and said plate material has a penetration hole reaching said second surface from said first surface, a shock absorbing device may have following features: said holding connecting mechanism comprises a first coupler located on a side of said first surface and a second coupler located on a side of said second surface, said first coupler comprises a first holding portion for holding said first cushioning members between said plate material and said first holding portion, and a first connecting portion being connected to said second coupler through said penetration hole, said second coupler comprises a second holding portion for holding said second cushioning members between said plate material and said second holding portion, and a second connecting portion being connected to said first coupler through said penetration hole, said first cushioning members are subject to said stress between a first holding portion and said plate material, and second cushioning members are subject to said stress between a second holding portion and said plate material by connecting said first connecting portion and said second connecting portion. In this case, said first cushioning members and said second cushioning members may comprise a plurality of columnar cushioning members, and said plurality of columnar cushioning members may be arranged around said first connecting portion and said second connecting portion. Furthermore, said first cushioning members and said second cushioning members may comprise cylindrical cushioning members having a penetration hole between a top surface and a bottom surface, and said first connecting portion and said second connecting portion may be connected through said penetration hole of said cylindrical cushioning members. 
         [0009]    When said first member is a plate material having a first surface and a second surface which is an opposite surface of said first surface, said plate material comprises a penetration hole reaching said second surface from said first surface, a shock absorbing device may have following features: said holding connecting mechanism comprises a first holding portion arranged on a side of said first surface, a second holding portion arranged on a side of said second surface, and a connecting portion for connecting said first holding portion arid said second holding portion through said penetration hole, said first cushioning members and said second cushioning members comprises a plurality of plate cushioning members, said plurality of plate cushioning members are deflected each other, one end is fixed on said first member, and another end is fixed on said first holding portion or said second holding portion, and stress will be applied to said plate cushioning members thereby. 
         [0010]    Said first cushioning members and said second cushioning members may be made of singlecrystal shape memory alloy, and said singlecrystal shape memory alloy is in austenite condition in working environment temperature, and becomes martensite condition by adding stress. In this case, said holding connecting mechanism may be adjusted so that the stress to be applied to said first cushioning members and said second cushioning members in a condition which said first member is held between said first cushioning members and said second cushioning members is neutrality of stress range having the condition that said singlecrystal shape memory alloy is in martensite condition. 
         [0011]    In the above-mentioned summary of the invention, description is not made for all of necessary features of the present invention. Furthermore, sub-combination of these feature groups can be potential inventions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIGS. 1A and 1B  shows a shock absorbing device  100 ,  FIG. 1A  is an exploded perspective view, and  FIG. 1B  is an assembly perspective view, 
           [0013]      FIG. 2  shows a cross-sectional view of a shock absorbing device  100 . 
           [0014]      FIG. 3  shows a partially assembled, state of a shock absorbing device  100 . 
           [0015]      FIG. 4  shows a partially assembled state of a shock absorbing device  100 . 
           [0016]      FIG. 5  shows an assembled state of a shock absorbing device  100 . 
           [0017]      FIG. 6  is a photo showing a state chat a shock absorbing device  100  is arranged between a first member  110  and a second member  120 . 
           [0018]      FIG. 7  is a graph showing a stress-strain characteristic of a singlecrystal shape memory alloy of copper/aluminum/nickel series. 
           [0019]      FIG. 8  is a graph showing a result of a shock test, in which a time response of acceleration is shown in a case that a shock absorbing device  100  exists or not, respectively. 
           [0020]      FIG. 9  is a graph showing a result of a shock test, in which frequency response of acceleration is shown in a case that a shock absorbing device  100  exists or not, respectively. 
           [0021]      FIG. 10  is a graph showing a result of an shock test, in which frequency response of response acceleration is shown in a case that a shock absorbing device  100  exists or not, respectively. 
           [0022]      FIG. 11  is a graph showing a result of a random vibration test, in which frequency response of a response magnification is shown in a case that a shock absorbing device  100  exists or not, respectively. 
           [0023]      FIGS. 12A and 12B  is a shock absorbing device  200 .  FIG. 12A  is an exploded perspective view, and  FIG. 12B  is an assembly perspective view. 
           [0024]      FIG. 13  is a perspective view of a shock absorbing device  300 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Now, hereinafter description of the present invention will be made with reference to embodiments of the present invention, however, following embodiments of the invention never limit a scope of claims. Furthermore, all of features explained in the embodiments of the invention are not necessarily required as means to solve the problems of the present invention. 
       EXAMPLE 1 
       [0026]      FIGS. 1A and 1B  shows a shock absorbing device  100 .  FIG. 1A  is an exploded perspective view, and  FIG. 1B  is an assembly perspective view.  FIG. 2  shows a cross-sectional view of a shock absorbing device  100 .  FIGS. 3 and 4  are photos showing a partially assembled state of a shock absorbing device  100 , respectively, and  FIG. 5  is a photo showing an assembled state of a shock absorbing device  100 .  FIG. 6  is a photo showing a state that a shock absorbing device  100  is arranged between a first member  110  and a second member  120 . 
         [0027]    A shock absorbing device  100  connects a first member  110  and a second member  120 , and suitable for cushioning the first member  110  and the second member  110 . A second member  120  may be satellites, for example, such as a body (housing) of an apparatus which is difficult to avoid vibration or shock to be added to the body. A first member  110  is fixed on a body (housing) such as a precision apparatus and so on, and also a supporting member for a built-in apparatus which should prevent propagation of vibration from the body. The vibration or shock to be added to the second member  120  can be suppressed by arranging a shock absorbing device  100  between the second member  120  and the first member  110 . 
         [0028]    A shock absorbing device  100  comprises first cushioning members  130 , second cushioning members  140 , and a holding connecting mechanism. The first cushioning members  130 , the second cushioning members  140  and the first member  110  are arranged in order of a first cushioning members  130 , a first member  110  and a second cushioning members  140 , and a holding connecting mechanism holds a first member  110  by clamping the first cushioning members  130  and the second cushioning members  140  from the outside. The holding connecting mechanism holds the first member  110  through the first cushioning members  130  and the second cushioning members  140 . 
         [0029]    The holding connecting mechanism is connected to the second member  120 . Accordingly, the first member  110  held by the holding connecting mechanism is also supported by the second member  120  through the holding connecting mechanism, and vibration and shock added to the second member  120  are absorbed by the first cushioning members  130  and the second cushioning members  140  and the propagation of the vibration and so on to the first member  110  can be suppressed. 
         [0030]    Description will be made in detail about a structure of the shock absorbing device  100  shown in  FIGS. 1A, 1B and 2 . The first member  110  is a plate material comprising a first surface  112  and a second surface  114  which is an opposite surface of the first surface  112 . The first member  110  of the plate material comprises a penetration hole  116  reaching the second surface  114  from the first surface  112 . 
         [0031]    The holding connecting mechanism comprises a first coupler  150  located on a side of the first surface  112  and a second coupler  160  located on a side of the second surface  114 . The first coupler  150  comprises a first holding portion  152  and a first connecting portion  154 , and a second coupler  160  comprises a second holding portion  162  and a second connecting portion  164 , 
         [0032]    The first holding portion  152  holds the first cushioning members  130  between the first member  110  of the plate material and the first holding portion  152 , and the first connecting portion  154  is connected to the second coupler  160  through the penetration hole  116 . The second holding portion  162  holds the second cushioning members  140  between the first member  110  of the plate material and the second holding portion  162 , and the second connecting portion  164  is connected to the first coupler  150  through the penetration hole  116 . 
         [0033]    The first cushioning members  130  comprise a plurality of columnar cushioning members, which are movably held the inside of a hole  172  formed in a first collar  170 . Since the plurality of columnar cushioning members are held in the hole  172  of the first collar  170 , the first cushioning members  130  are arranged around the first connecting portion  154 . One end of the columnar first cushioning member  130  is abutted on a bottom surface of the hole  172 , and another end is abutted on the first holding portion  152  of the first coupler  150 . By tightening a bolt  190 , the first coupler  150  is pressed in a direction of the first member  110  to be held, and the first cushioning members  130  are subject to stress. 
         [0034]    The second cushioning members  140  comprise a plurality of columnar cushioning members, which are movably held inside of a hole  182  formed in a second collar  180 . Since the plurality of columnar cushioning members are held in the hole  182  of the second collar  180 , the second cushioning members  140  are arranged around the second connecting portion  164 . One end of the columnar second cushioning member  140  is abutted on a bottom surface of the hole  182 , and another end is abutted on the second holding portion  162  of the second coupler  160 . By tightening the bolt  190 , the second coupler  160  is pressed in a direction of the first member  110  to be held, and the second cushioning members  140  are subject to stress. 
         [0035]    As described above, by tightening the bolt  190 , and connecting the first connecting portion  154  of the first coupler  150  and the second connecting portion  164  of the second coupler  160 , the first cushioning members  140  are subject to stress between the first holding portion  152  and the plate material, and the second cushioning members  140  are subject to stress between the second holding portion  162  and the plate material. However, when the first connecting portion  154  and the second connecting portion  164  are engaged on an engaging surfaced  192 , further clamping force is not applied to the first cushioning members  130  and the second cushioning members  140 , and the stress applied to a first cushioning members  130  and the second cushioning members  140  is restricted. Namely, under a state that the shock absorbing device  100  is assembled and arranged between the first member  110  and the second member  120 , if it is in a state of neutrality without adding vibration and so on, a certain stress is applied to the first cushioning members  130  and the second cushioning members  140 . 
         [0036]    As the first cushioning members  130  and the second cushioning members  140 , a singlecrystal shape memory alloy should be noted. Specifically, the singlecrystal shape memory alloy of copper/aluminum/nickel series is preferable. Furthermore, the singlecrystal shape memory alloy becomes austenite condition in a working environment temperature, and it is preferable to be martensite condition by applying the stress. 
         [0037]      FIG. 7  is a graph showing a stress-strain characteristic of the singlecrystal shape memory alloy of copper/aluminum/nickel series. The stress-strain characteristic in  FIG. 7  shows hysteresis that the stress increases between 0 to 300 MPa, and decreases to 0 MPa thereafter. The singlecrystal shape memory alloy of copper/aluminum/nickel series are in austenite condition which increases in strain in proportion to the stress from O point to A point, and become martensite condition which large distortion will be made by a small increase of stress from A point to B point. Beyond a maximum distortion (B point) in the martensite condition, after applying the stress and decreasing the same, the martensite condition can be obtained between C point to D point. Beyond D point, it becomes austenite condition. 
         [0038]    A shock absorbing device  100  according to embodiments of the present invention uses a shape memory alloy which becomes the martensite condition by applying the stress as the first cushioning members  130  and the second cushioning members  140 . Namely, under a state that the shock absorbing device  100  is arranged between the first member  110  and the second member  120 , and neutrality state without adding vibration and so on is kept, a certain stress is applied in advance to the first cushioning members  130  and the second cushioning members  140  so as to be martensite condition. 
         [0039]    It is preferable that the stress to be applied in advance, namely the stress to be applied to the first cushioning members  130  and the second cushioning members  140  in a state that the first member  110  is held between the first cushioning members  130  and the second cushioning members  140 , is neutrality of the stress range in the condition that the singlecrystal shape memory alloy is in the martensite condition. It is preferable that the stress to be applied in advance has an intermediate value of each stress at A point and D point in  FIG. 7 , or an intermediate value of each stress at B point and C point. 
         [0040]    The value of the stress to be applied in advance can be determined by adjusting the holding connecting mechanism. For example, in the shock absorbing device  100 , neutrality of the stress range in the martensite condition can be obtained in a manner that lengths of the first connecting portion  154  of the first coupler  150  and the second connecting portion  164  of the second coupler  160 , and lengths of the first cushioning members  130  and the second cushioning members  140  are adjusted so that distortion of the first cushioning members  130  and the second cushioning members  140  becomes 4.5%. 
         [0041]    In the shock, absorbing device  100 , the shape memory alloy is used for the first cushioning members  130  and the second cushioning members  140 , and the shape memory alloy is in martensite condition by applying the stress in advance. Therefore, damping force can be obtained from a hysteresis loop in the martensite condition, and excellent attenuation characteristic can be obtained while maintaining high strength and rigidity. When the a singlecrystal shape memory alloy, especially the singlecrystal shape memory alloy of copper/aluminum/nickel series is used as the first cushioning members  130  and the second cushioning members  140 , strain range becomes relatively large 9% in the martensite condition, and the stress range of the hysteresis becomes narrow. Therefore, even if stress change is small, amount of distortion change becomes large and effective attenuation can be realized. As a result, it becomes easy to realize a device small in size and weight. Since the singlecrystal shape memory alloy of copper/aluminum/nickel series has wide transition temperature range of −270° C. to +250° C., stability of the temperature characteristic of the shock absorbing device  100  can be realized. Furthermore, the shock absorbing device  100  consist of metals, and there can be obtained the device free from worry about degassing. 
         [0042]      FIGS. 8 to 10  are graphs showing a result of a shock test, in which a test is carried out about vibration state of the first member  110  when the shock is added to the second member  120 .  FIG. 8  shows a time response of acceleration of the first member  110 ,  FIG. 9  shows frequency response of acceleration of the first member  110 , and  FIG. 10  shows frequency response of response acceleration of the first member  110  in a case the shock absorbing device  100  exists or not, respectively. When the shock absorbing device  100  exists, an absolute value of the acceleration is small in comparison with the case the shock absorbing device  100  does not exist, and it is apparent that the acceleration and response acceleration are reduced in high frequency range more than 1 kHz. 
         [0043]      FIG. 11  is a graph showing a result of a random vibration test, and frequency response of response magnification in a case the shock absorbing device  100  exists or not, respectively. When the shock absorbing device  100  exists, a maximum value of the response magnification is largely reduced in comparison with the case the shock absorbing device  100  does not exist, and it is apparent that a peak value is shifted to a low frequency side. 
         [0044]    As apparent from the results of  FIGS. 8 to 11 , the test found that the vibration and shock are reduced by the shock absorbing device  100 , in particular, vibration in a high frequency range more than 1 kHz can be reduced. 
         [0045]    The present invention is described above with reference to embodiments of the present invention, and a technical scope of the invention is never limited by the above description. It is obvious to those skilled in the art to add various modification and improvement to the above embodiments of the present invention. It is apparent from description of claims that such embodiments to which these modification and improvement are added are also included in the technical scope of the present invention. 
         [0046]    For example, as a shock absorbing device  200  in  FIGS. 12A and 12B , third cushioning members  230  and fourth cushioning members  240  can be included.  FIG. 12A  is an exploded perspective view, and  FIG. 12B  is an assembly perspective view. The shock absorbing device  200  is made by eliminating the first collar  170  and the second collar  180  of the shock absorbing device  100 , and replacing the first cushioning members  130  and the second cushioning members  140  with the third cushioning members  230  and the fourth cushioning members  240 . The third cushioning members  230  and the fourth cushioning members  240  are cylindrical cushioning members and comprise penetration holes  232  and  242  between a top surface to a bottom surface, respectively. The first connecting portion  154  and the second connecting portion  164  are connected through the penetration holes  232  and  242  of the cylindrical cushioning members. The shock absorbing device  200  has a similar effect as that of the shock absorbing device  100 . 
         [0047]    As a shock absorbing device  300  of  FIG. 13 , fifth cushioning members  330  and sixth cushioning members  240  can be included.  FIG. 13  shows a perspective view of the shock absorbing device  300 . In the shock absorbing device  300 , as same as structure of the shock absorbing device  100 , the first member  110  is the plate material comprising the first surface  112  and the second surface  114  which is an opposite surface of the first surface  112 , and the first member  110  of the plate material comprises the penetration hole  116  reaching the second surface  114  from the first surface  112 . In the shock absorbing device  300 , the holding connecting mechanism comprises a third holding portion  352  arranged on a side of the first surface  112 , a fourth holding portion  352  arranged on a side of the second surface  114 , and a connecting portion  370  for connecting the third holding portion  352  and the fourth holding portion  362  through the penetration hole  116 . The fifth, cushioning members  330  and the sixth cushioning members  340  comprise a plurality of plate cushioning members, which are deflected each other, one end is fixed on the first member  110 , and another end is fixed on the third holding portion  352  or the fourth holding portion  362 . The stress will be applied to the plate cushioning members thereby. 
         [0048]    The fifth cushioning members  330  and the sixth cushioning members  340  of the shock absorbing device  300  have a plate shape, which is transitional to the martensite condition by bending stress. This is a different point from that the first cushioning members  130  and the second cushioning members  140  of the shock absorbing device  100 , or the third cushioning members  230  and the fourth cushioning members  240  of the shock absorbing device  200  are transitional to the martensite condition by compressed force. Since the fifth cushioning members  330  and the sixth cushioning members  340  have a plate shape, the shock absorbing device  300  is excellent in absorbing shock at low frequency range in comparison with the shock absorbing device  100  or the shock absorbing device  200 . Other than this point, similar effect as that of the shock absorbing device  100  or the shock absorbing device  200  can be obtained.