Patent Publication Number: US-2019186576-A1

Title: Damper device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-240668 filed on Dec. 15, 2017, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a damper device that is provided on a vibration part of a transport apparatus (for example, vehicle, airplane, and ship) in which vibration, oscillation, or the like easily occurs, and that suppresses the vibration of the vibration part. 
     Description of the Related Art 
     An object of a damper device according to Japanese Laid-Open Patent Publication No. 2009-204123 is to provide a dynamic damper that is reduced in size in left-right and up-down directions so as to be attached to a limited small space, and to elastically support a damper mass stably and regulate displacement of the damper mass in up-down, front-rear, and left-right directions. 
     To achieve the above object, in the damper device according to Japanese Laid-Open Patent Publication No. 2009-204123, rubber support parts of the dynamic damper are disposed at four corners of the damper mass, and elastically support the damper mass from below. The damper mass includes an extension part and has a thin shape in the up-down direction. The extension part and a pair of elastic support bodies form a stopper mechanism in the left-right direction. An upper bracket and a lower bracket of the elastic support body form the stopper mechanism in the up-down and front-rear directions. 
     SUMMARY OF THE INVENTION 
     In Japanese Laid-Open Patent Publication No. 2009-204123, the rubber support part made of a rubber elastic body that elastically supports the damper mass is provided between the damper mass of the dynamic damper and a vibration part of a vehicle. 
     In general, the single inertance (acceleration characteristic) of a seat back frame has substantially the same frequency in large input (for example, 100 N) and small input (30 N). 
     However, since a member that elastically supports the damper mass is formed by rubber, the single inertance of the dynamic damper has different resonance frequencies in the large input and the small input. 
     Therefore, conventionally, an eigenvalue only can be controlled in the small input or the large input, not both. 
     The present invention has been made in order to solve the above problem and an object is to provide a damper device in which a characteristic of a dynamic damper varies depending on response amplitude with respect to input, and the dynamic damper effect the can be obtained in both the large input and the small input on an actual road. 
     [1] A damper device according to an aspect of the present invention includes: a case; a weight elastically supported in the case; and an elastic member that is fixed to a surface of the case that faces the weight, wherein: the weight and the elastic member are separated from each other; and a spring rate of the elastic member has a nonlinear characteristic. 
     Therefore, if vibration (road surface input) from a road surface is small, the spring rate becomes low, and if the input is large, the spring rate becomes high. That is to say, the damper device has a structure in which a characteristic of a dynamic damper varies depending on response amplitude with respect to the input. Thus, change of an eigenvalue of the dynamic damper due to amplitude dependence, which is inherent in the dynamic damper, is suppressed. As a result, in the large input and the small input, frequencies of the dynamic damper do not shift and become an optimum value. That is to say, even on an actual road, the effect of the dynamic damper can be obtained in both the large input case and the small input case. 
     [2] In the aspect of the present invention, the case may include a plurality of side plates that face each other, and the elastic member may be fixed to a surface of each of the side plates that faces the weight. 
     The side plates are provided in order to prevent a portion that elastically supports the weight from being cut when the amplitude becomes large in rough road traveling, for example. The elastic member can be fixed by using the side plates. As a result, no dedicated component for attaching the elastic member is required, and thus it is possible to prevent the number of components from increasing. 
     [3] In the aspect of the present invention, the elastic member may be a conical spring, and the elastic member may be fixed so that a portion of the elastic member that has smaller diameter faces the weight. 
     The spring rate of the conical spring has a characteristic in which, as deflection (displacement) increases, a load increases exponentially, that is, a nonlinear characteristic. Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     [4] In the aspect of the present invention, the elastic member may include a plurality of coil springs with different diameters and lengths. 
     In a case where the coil springs with different diameters and lengths include, for example, a first coil spring with large diameter and long length and a second coil spring with small diameter and short length, when the deflection is small, the characteristic of only the first coil spring appears. That is to say, as the deflection increases, the load increases along a certain inclination. As the deflection increases more, the characteristic obtained by combining the characteristic of the first coil spring with the characteristic of the second coil spring appears. That is to say, as the deflection increases, the load increases along an inclination that is larger than the above inclination. That is to say, the spring rate has the nonlinear characteristic. 
     Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, the change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     [5] In the aspect of the present invention, the elastic member may include a rubber member and may have a shape in which a cross-sectional area becomes smaller toward the weight. 
     Even in this case, similarly to the conical spring, the spring rate has the characteristic in which, as the deflection increases, the load increases exponentially, that is, the nonlinear characteristic. Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     In the damper device according to the present invention, the characteristic of the dynamic damper varies depending on the response amplitude with respect to the input, and the effect of the dynamic damper can be obtained in both the large input and the small input on the actual road. 
     The above and other objects features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a seat device (mainly, frame structure) that includes a damper device according to the present embodiment; 
         FIG. 2A  is a front view illustrating a first damper device; 
         FIG. 2B  is a right side view illustrating the first damper device; 
         FIG. 2C  is a graph showing a spring rate of a conical spring; 
         FIG. 3A  is an explanatory view showing a hammering test for a single seat back frame; 
         FIG. 3B  is a graph showing an inertance characteristic of the single seat back frame in large input (150 N) and small input (30 N); 
         FIG. 4A  is an explanatory view showing the hammering test for a damper device according to a comparative example; 
         FIG. 4B  is a graph showing the inertance characteristic of the single damper device (comparative example) in the large input (100 N) and the small input (20 N); 
         FIG. 5A  is a graph showing the inertance characteristic of the seat back frame with the damper device (comparative example) in the large input (150 N) and the small input (30 N); 
         FIG. 5B  is a graph showing the inertance characteristic of the seat back frame with the damper device (example of the embodiment) in the large input (150 N) and the small input (30 N); 
         FIG. 6A  is a front view illustrating a second damper device; 
         FIG. 6B  is an explanatory view illustrating a structure example of a double coil spring; 
         FIG. 6C  is a graph showing the spring rate of the double coil spring; 
         FIG. 7A  is a front view illustrating a third damper device; 
         FIG. 7B  is an explanatory view illustrating one example of a second elastic member that is made up of a rubber member (triangular column shape); and 
         FIG. 7C  is a graph showing the spring rate of the second elastic member that is made up of the rubber member. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Description is hereinafter given of embodiments of a damper device according to the present invention with reference to  FIG. 1  to  FIG. 7C . 
     For example, as illustrated in  FIG. 1 , the damper device according to a first embodiment (first damper device  10 A) is installed on a seat device  12 . 
     The seat device  12  includes at least a seat cushion frame  14  and a seat back frame  16 . The seat back frame  16  includes a lower seat back frame  18 L that is rotatably attached to the seat cushion frame  14 , and an upper seat back frame  18 U that is fixed to an upper part of the lower seat back frame  18 L by welding, for example. 
     The seat device  12  is provided so as to be slidable in, for example, a front-rear direction by brackets  20  that are provided on a floor or the like of a transport apparatus such as a vehicle, a ship, or an airplane. Needless to say, the seat device  12  may be fixed to the floor or the like without sliding. 
     The seat cushion frame  14  includes a pair of left and right cushion side frames  22  that extend in the front-rear direction, a front frame  24  that is extended between front parts of the cushion side frames  22 , a rear frame  26  that is extended between rear parts of the cushion side frames  22 , and the like. Thus, the seat cushion frame  14  has a frame shape. The bracket  20  is attached to each cushion side frame  22 . 
     The lower seat back frame  18 L includes a pair of left and right back side frames  30  that extends in an approximately up-down direction, a back lower frame  32  that is extended between lower ends of the left and right back side frames  30 , and reinforcement poles  34  that are extended respectively between upper parts of the back side frame  30  and between lower parts of the back side frame  30 . Thus, the lower seat back frame  18 L has a frame shape. The back lower frame  32  is connected to the lower parts of the back side frames  30  by welding, for example. 
     The upper seat back frame  18 U has an inverted U-letter shape. Each end of the upper seat back frame  18 U is connected to the upper part of the lower seat back frame  18 L by welding, for example. The upper seat back frame  18 U has two tubular holders  36  fixed on a central part thereof, through which stays of a headrest are inserted. 
     Note that a rear part of the seat cushion frame  14  and a lower part of the lower seat back frame  18 L are provided with a support shaft  38  that supports the lower seat back frame  18 L in a manner that the lower seat back frame  18 L is rotatable with respect to the seat cushion frame  14 . For example, the lower part of the lower seat back frame  18 L is rotatably connected to an inner side of the rear part of the cushion side frame  22 . 
     Then, as described above, the first damper device  10 A is provided to the seat device  12 . The first damper device  10 A may be provided to any part of the seat device  12 . However, in order to suppress vibration of the seat back frame  16 , for example, it is preferable that the first damper device  10 A is disposed on a central part of the seat back frame  16 , for example. In the present embodiment, the first damper device  10 A is arranged on the central part of the upper seat back frame  18 U so that the first damper device  10 A is extended between central parts of the reinforcement poles  34 , for example. 
     As illustrated in  FIG. 2A  and  FIG. 2B , the first damper device  10 A includes a case  50 , and a weight  52  that is elastically held at a central part of the case  50 . 
     The case  50  is formed by integrating an upper plate  54   a,  a lower plate  54   b,  and a back plate  54   c  that are made of metal through a sheet metal working of a metal plate, for example. In this case, the upper plate  54   a  projects forward from an upper end of the back plate  54   c,  and the lower plate  54   b  projects forward from a lower end of the back plate  54   c . That is to say, the upper plate  54   a  and the lower plate  54   b  face each other. 
     In one example, the back plate  54   c  has a length of 70 mm in a horizontal direction (left-right direction), the back plate  54   c  has a length of 110 mm in a vertical direction (up-down direction), and the upper plate  54   a  and the lower plate  54   b  have a depth of 30 mm (length in front-rear direction). In addition, the weight  52  has a length of 50 mm in the horizontal direction (left-right direction), a length of 90 mm in the vertical direction (up-down direction), and a height of 20 mm (length in front-rear direction). 
     To a front end of the upper plate  54   a,  for example, an upper attachment plate  56   a  with a semicircular shape that is made of metal is attached integrally. Similarly, to a front end of the lower plate  54   b,  for example, a lower attachment plate  56   b  with a semicircular shape that is made of metal is also attached integrally. Each of the upper attachment plate  56   a  and the lower attachment plate  56   b  has a screw hole  58  on a central part thereof. Therefore, for example, the damper device can be fixed to the reinforcement poles  34  of the seat back frame  16  or the like by inserting screws (not shown) into the screw holes  58 . 
     The upper plate  54   a  of the case  50  and an upper surface  60   a  of the weight  52  are connected to each other through two first elastic members  62   a  each having a plate shape. 
     Similarly, the lower plate  54   b  of the case  50  and a lower surface  60   b  of the weight  52  are connected to each other through two first elastic members  62   a.  Each first elastic member  62   a  has a plate shape, and is provided so that a thickness direction of the first elastic member  62   a  coincides with the left-right direction of the case  50 , and a surface direction of the first elastic member  62   a  coincides with the front-rear direction of the case  50 . In one example, the first elastic member  62   a  has a length of 10 mm (length in up-down direction), a thickness of 3 mm (length in left-right direction), and a depth of 15 mm (length in front-rear direction). Note that the first elastic member  62   a  is not fixed to the back plate  54   c.    
     Furthermore, the case  50  is integrated with four side plates (first side plate  64   a  to fourth side plate  64   d ) that face each other, for example.  FIG. 2A  illustrates an example in which the first side plate  64   a  and the third side plate  64   c  face each other, and the second side plate  64   b  and the fourth side plate  64   d  face each other. In this case, inner surfaces of the first side plate  64   a  and the third side plate  64   c  face one side surface of the weight  52 , and inner surfaces of the second side plate  64   b  and the fourth side plate  64   d  face the other side surface of the weight  52 . Note that the number of side plates is not limited to four. Two side plates may be provided so as to face each other, or six or more side plates may be provided so as to face each other. 
     Each of the first side plate  64   a  to the fourth side plate  64   d  has a second elastic member  62   b  fixed to a surface thereof that faces the weight  52  using an adhesive, for example. In a natural state, the weight  52  and the second elastic member  62   b  are separated from each other, that is, are not in contact with each other. 
     Each second elastic member  62   b  is a conical spring  66 , and fixed so that a smaller-diameter portion of the elastic member faces the weight  52 . As illustrated in  FIG. 2C , a spring rate of the conical spring  66  has a characteristic in which, as deflection (displacement) δ increases, a load P increases exponentially, that is, a nonlinear characteristic. 
     Here, description is given of an experiment example regarding the first damper device  10 A and a comparative example with reference to  FIG. 3A  and  FIG. 3B . 
     First, as illustrated in  FIG. 3A , a hammering test for the single seat back frame  16  (made of iron) was performed. In the hammering test, at the central part of the seat back frame  16 , for example, the central part of the upper reinforcement pole  34 , a G meter  70  was fixed. Then, a portion of one back side frame  30  at the same height as the position at which the G meter  70  was fixed was hit with a hammer  72 . This result is shown in  FIG. 3B . 
     In  FIG. 3B , a curved line La expresses an inertance characteristic of the single seat back frame  16  in the case of large input (150 N), and similarly, a curved line Lb expresses the inertance characteristic in the case of small input (30 N). 
     The result in  FIG. 3B  shows that the inertance characteristics of the single seat back frame  16  in the large input and the small input are substantially the same, and peak frequencies fa (optimum value) are also substantially the same. That is to say, the inertance characteristics of the single seat back frame  16  hardly depend on amplitude. 
     Next, the hammering test for a damper device  100  according to the comparative example was performed. As illustrated in  FIG. 4A , in the damper device  100  according to the comparative example, the case  50  includes neither the four side plates (first side plate  64   a  to fourth side plate  64   d ) nor the second elastic members  62   b  (see  FIG. 2A ). In the hammering test, the G meter  70  was fixed to a central part of the weight  52 , and a center of one side surface of the weight  52  was hit with the hammer  72 . This result is shown in  FIG. 4B . 
     In  FIG. 4B , a curved line Lc expresses the inertance characteristic of the single damper device in the case of the large input whose amplitude is large (100 N), and similarly, a curved line Ld expresses the inertance characteristic in the case of the small input whose amplitude is small (20 N). 
     The result in  FIG. 4B  shows that, in the inertance characteristics of the single damper device  100  (comparative example), a peak Pc of the inertance in the large input is greater than a peak Pd of the inertance in the small input, and the peak frequencies of the peak Pc and the peak Pd are also different largely. 
     Next, the damper device  100  according to the comparative example and the G meter  70  were fixed to the central part of the seat back frame  16 , and the hammering test was performed similarly to the above example. This result is shown in  FIG. 5A . 
     In  FIG. 5A , a curved line Le expresses the inertance characteristic of the seat back frame  16  with the damper device (comparative example) in the case of the large input (150 N), and a curved line Lf expresses the inertance characteristic in the case of the small input (30 N). 
     According to the result in  FIG. 5A  concerning the inertance characteristics of the seat back frame  16  with the damper device (comparative example), the inertance in the small input has a local minimum value at the peak frequency fa (optimum value: see  FIG. 3B ) of the single seat back frame  16 , while the inertance in the large input has a local minimum value at a frequency that is lower than the peak frequency fa. 
     That is to say, in the damper device  100  according to the comparative example, there is a difference in amplitude dependence between the seat back frame  16  and the damper device  100 . Therefore, it is understood that the effect of a dynamic damper (vibration suppressing effect) only can be obtained in one of the large input and the small input. The result in  FIG. 5A  shows that the damper device  100  according to the comparative example has the vibration suppressing effect only in the small input case on an actual road. 
     Next, the damper device (first damper device  10 A) according to the embodiment and the G meter  70  were fixed to the central part of the seat back frame  16 , and the hammering test was performed similarly to the above example. This result is shown in  FIG. 5B . 
     In  FIG. 5B , a curved line Lg expresses the inertance characteristic of the seat back frame  16  with the first damper device  10 A (embodiment) in the case of the large input (150 N), and a curved line Lh expresses the inertance characteristic in the case of the small input (30 N). 
     According to the result in  FIG. 5B  concerning the inertance characteristics of the seat back frame  16  with the first damper device  10 A (embodiment), both the inertances in the small input case and the large input case have local minimum values at the peak frequency fa (optimum value: see  FIG. 3B ) of the single seat back frame  16 . 
     That is to say, in the first damper device  10 A, the characteristic of the dynamic damper varies depending on response amplitude with respect to the input. Therefore, there is little amplitude dependence between the seat back frame  16  and the first damper device  10 A. Thus, the effect of the dynamic damper (vibration suppressing effect) can be obtained in both the large input case and the small input case. The result in  FIG. 5B  shows that, the first damper device  10 A (embodiment) has the vibration suppressing effect both in the large input case and the small input case on an actual road. 
     Next, description is given of a damper device (second damper device  10 B) according a second embodiment with reference to  FIG. 6A  to  FIG. 6C . 
     As illustrated in  FIG. 6A , the second damper device  10 B has a structure that is similar to that of the first damper device  10 A as described above, but differs from the first damper device  10 A in that each of the second elastic members  62   b  includes a plurality of coil springs with different diameters and lengths. 
       FIG. 6A  and  FIG. 6B  show an example in which the second elastic member  62   b  includes a double coil spring  74 . In the double coil spring  74 , for example, a first coil spring  74   a  is arranged inside a second coil spring  74   b.  In one example of the diameter and the length of the double coil spring  74 , when the diameter and the length of the first coil spring  74   a  are denoted respectively by dl and L 1 , and the diameter and the length of the second coil spring  74   b  are denoted respectively by d 2  and L 2 , these diameters and lengths satisfy the following relations. 
       d 1 &gt;d 2   
       L 1 &gt;L 2   
       FIG. 6C  shows the spring rate of the second elastic member  62   b  (double coil spring  74 ) of the second damper device  10 B. When the deflection δ is small, the characteristic of only the first coil spring  74   a  appears. That is to say, as the deflection δ increases, the load P increases along a certain inclination. As the deflection δ increases more, the characteristic containing the characteristic of the first coil spring  74   a  and the characteristic of the second coil spring  74   b  in combination appears. In this case, as the deflection δ increases, the load P increases along an inclination that is larger than the above inclination. That is to say, the spring rate has a nonlinear characteristic, which is similar to that of the second elastic member  62   b  (conical spring  66 ) of the first damper device  10 A. 
     Next, description is given of a damper device (third damper device  10 C) according a third embodiment with reference to  FIG. 7A  to  FIG. 7C . 
     As illustrated in  FIG. 7A  and  FIG. 7B , the third damper device  10 C has a structure that is similar to that of the first damper device  10 A as described above except that the second elastic member  62   b  is made up of a rubber member  76  and has a shape in which a cross-sectional area becomes smaller toward the weight  52 , for example a triangular column shape (see  FIG. 7B ). 
     As illustrated in  FIG. 7C , similarly to the conical spring  66 , the spring rate of the second elastic member  62   b  of the third damper device  10 C has a characteristic in which, as the deflection δ increases, the load P increases exponentially, that is, a nonlinear characteristic. 
     Examples of the shape of the second elastic member  62   b  include, in addition to the triangular column shape as shown in  FIG. 7B , a conical shape, a truncated conical shape, and a hemispherical shape, for example. 
     As described above, the damper device according to the present embodiment includes: the case  50 ; the weight  52  elastically supported in the case  50 ; and the second elastic member  62   b  that is fixed to the surface of the case  50  that faces the weight  52 . The weight  52  and the second elastic member  62   b  are separated from each other, and the spring rate of the second elastic member  62   b  has the nonlinear characteristic. 
     Therefore, if the vibration (road surface input) from the road surface is small, the spring rate becomes low, and if the input is large, the spring rate becomes high. That is to say, the damper device has the structure in which the characteristic of the dynamic damper varies depending on the response amplitude with respect to the input. Thus, change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, is suppressed. As a result, in the large input and the small input, the frequencies of the dynamic damper do not shift and become an optimum value. That is to say, even on the actual road, the effect of the dynamic damper can be obtained in both the large input case and the small input case. 
     In the present embodiment, the case  50  includes the plurality of side plates ( 64   a  to  64   d ) that face each other, and the second elastic member  62   b  is fixed to the surface of each of the side plates that faces the weight  52 . 
     The side plates ( 64   a  to  64   d ) are provided in order to prevent a portion (first elastic member  62   a ) that elastically supports the weight  52  from being cut when the amplitude becomes large in the rough road traveling, for example. The second elastic member  62   b  can be fixed by using the side plates. As a result, no dedicated component for attaching the second elastic member  62   b  is required, and thus it is possible to prevent the number of components from increasing. 
     In the present embodiment, the second elastic member  62   b  is the conical spring  66 , and the second elastic member  62   b  is fixed so that the portion of the elastic member having smaller diameter faces the weight  52 . 
     The spring rate of the conical spring  66  has the characteristic in which, as the deflection δ increases, the load P increases exponentially, that is, the nonlinear characteristic. Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     In the present embodiment, the second elastic member  62   b  includes the plurality of coil springs  74   a,    74   b  with different diameters and lengths. 
     In the case where the coil springs  74   a,    74   b  with different diameters and lengths include, for example, the first coil spring  74   a  with the large diameter and the long length and the second coil spring  74   b  with the small diameter and the short length, when the deflection δ is small, the characteristic of only the first coil spring  74   a  appears. That is to say, as the deflection δ increases, the load P increases along a certain inclination. As the deflection δ increases more, the characteristic obtained by combining the characteristic of the first coil spring  74   a  with the characteristic of the second coil spring  74   b  appears. That is to say, as the deflection δ increases, the load P increases along an inclination that is larger than the above inclination. That is to say, the spring rate has the nonlinear characteristic. 
     Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, the change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     In the present embodiment, the second elastic member  62   b  is made up of the rubber member  76  and has a shape in which the cross-sectional area becomes smaller toward the weight  52 . 
     Even in this case, similarly to the conical spring  66 , the spring rate has the characteristic in which, as the deflection δ increases, the load P increases exponentially, that is, the nonlinear characteristic. Therefore, if the road surface input is small, the spring rate becomes low, and if the road surface input is large, the spring rate becomes high. Thus, change of the eigenvalue of the dynamic damper due to the amplitude dependence, which is inherent in the dynamic damper, can be prevented. Since the spring rate has the nonlinear characteristic, it is possible to deal with a wide range of amplitude input. 
     The present invention is not limited to the embodiments above, and can be changed freely within the range not departing from the concept of the present invention.