Patent Publication Number: US-2019186590-A1

Title: Damper device

Description:
INCORPORATION BY REFERENCE 
     The disclosure of Japanese Patent Application No. 2017-241034 filed on Dec. 15, 2017 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a damper device. 
     2. Description of Related Art 
     Japanese Unexamined Patent Application Publication No. 4-321839 (JP 4-321839 A) discloses a technology relates to a mass body that is joined to a main body surface of a pulley via a rubber elastic body having a predetermined thickness and functions as a bending damper. 
     SUMMARY 
     A bending damper is mounted on a rotary shaft member, for example, a crankshaft or the like of an internal combustion engine, and a mass body moves with the rotation of the crankshaft to attenuate vibration of the internal combustion engine. The bending damper effectively functions in a low rotation range or a medium rotation range of the internal combustion engine and effectively attenuates the vibration of the internal combustion engine. However, when the engine speed of the internal combustion engine enters a high rotation range, the noise, vibration (hereinafter referred to as “NV”) of a vehicle increases compared to the vibration of the internal combustion engine. When the bending damper continues to operate in the high rotation range of the internal combustion engine, the bending damper becomes a vibration source, and thus, rather, there is a possibility that the NV characteristic of the vehicle may deteriorate. 
     The disclosure provides a damper device that suppresses deterioration of an NV characteristic in a high rotation range of equipment on which a rotary shaft member is mounted. 
     An aspect of the disclosure relates to a damper device including a first damper and a behavior limiter. The first damper includes a base and a first mass body. The base is mounted on a rotary shaft member and configured to rotate together with the rotary shaft member, and the first mass body is provided on the base via a first elastic part. The behavior limiter is disposed around the first mass body on the outside in a rotation radial direction of the first mass body, and configured to limit a movement of the first mass body by coming into contact with the first mass body when a rotational frequency of the rotary shaft member has become equal to or higher than a threshold value. 
     The damper device may further include a buffer material that is interposed between the first mass body and the behavior limiter. 
     The damper device may further include a second damper having a second mass body. The second mass body may be provided on an outer periphery of a main body that is joined to the base via a second elastic part. The behavior limiter may be provided inside an accommodation portion that is provided at the main body and accommodates the first mass body. 
     With the above-mentioned damper device, it is possible to suppress deterioration of an NV characteristic in a high rotation range of equipment on which a rotary shaft member is mounted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is a perspective sectional view of a damper device of an embodiment; 
         FIG. 2  is a sectional view of the damper device of the embodiment; 
         FIG. 3  is a front view of a first damper that is included in the damper device of the embodiment; 
         FIG. 4  is a back view of the first damper that is included in the damper device of the embodiment; 
         FIG. 5  is a sectional view of the first damper of the embodiment taken along line V-V in  FIG. 3 ; 
         FIG. 6  is a sectional view of the first damper of the embodiment taken along line VI-VI in  FIG. 3 ; 
         FIG. 7  is a front view of a second damper that is included in the damper device of the embodiment; 
         FIG. 8  is a sectional view of the second damper of the embodiment taken along line VIII-VIII in  FIG. 7 ; 
         FIG. 9  is an explanatory diagram showing a state where a first mass body of the first damper is in contact with a behavior limiter; and 
         FIG. 10  is a graph showing a change in a gap S between the first mass body of the first damper and the behavior limiter. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the disclosure will be described with reference to the accompanying drawings. In the drawings, there is a case where the dimensions, the ratio, and the like of each part are not shown so as to completely coincide with the actual dimensions, ratio, and the like. Depending on the drawing, there is also a case where the drawing is drawn with details omitted. 
     EMBODIMENT 
     A schematic configuration of a damper device  1  of an embodiment will be described with reference to  FIG. 1  and  FIG. 2 .  FIG. 1  is a perspective sectional view of the damper device  1 , and  FIG. 2  is a sectional view of the damper device. However, the sections of  FIG. 1  and  FIG. 2  are sections taken along line I-I in  FIG. 3  that shows a front view of a first damper  10 . 
     The damper device  1  includes the first damper  10  and a second damper  50 . The damper device  1  is mounted on a crankshaft  71  of an internal combustion engine, as shown in  FIG. 2 . The crankshaft  71  is an example of a rotary shaft member. Bending vibration and torsional vibration are generated in the crankshaft  71  according to a movement of a piston. The first damper  10  functions as a bending damper that suppresses mainly the bending vibration. The second damper  50  functions as a torsional damper that suppresses mainly the torsional vibration. The damper device  1  has, as the rotation center thereof, an axis that coincides with a center axis AX of the crankshaft  71 . In the following description, a direction away from the center axis AX will be described as being the outside in a rotation radial direction. 
     The first damper  10  has a flange-like portion  11  serving as a base. The flange-like portion  11  is mounted on the crankshaft  71  via a main body  51  of the second damper  50  (described in detail later) and rotates together with the crankshaft  71 . A first mass body  14  is provided at the flange-like portion  11  via a first elastic part  13 . A first buffer part  15  is provided at the first mass body  14 . The main body  51  of the second damper  50  has a first damper accommodation portion  51   a  that accommodates the first damper  10 , and a behavior limiter  51   a   1  is provided in a part of the first damper accommodation portion  51   a . The behavior limiter  51   a   1  is disposed around the first mass body  14  on the outside in the rotation radial direction of the first mass body  14 . A gap S is formed between the first mass body  14  (the first buffer part  15 ) and the behavior limiter  51   a   1  in a state where the crankshaft  71  does not rotate. Due to the presence of the gap S between the first mass body  14  (the first buffer part  15 ) and the behavior limiter  51   a   1 , the first mass body  14  moves according to the rotation of the crankshaft  71  and the first damper  10  functions as a bending damper. 
     The behavior limiter  51   a   1  limits a movement of the first mass body  14  by coming into contact with the first mass body  14  when the rotational frequency of the crankshaft  71  has become equal to or higher than a threshold value. When the rotational frequency of the crankshaft  71  increases, a centrifugal force acting on the first mass body  14  increases with an increase in the rotational frequency. When the centrifugal force acting on the first mass body  14  increases, a swing width of the first mass body  14  increases. Then, the first mass body  14  comes into contact with the behavior limiter  51   a   1 , and finally, the movement of the first mass body  14  is limited. When the movement of the first mass body  14  is limited, an attenuation function of the first damper is reduced, and thus the damper device  1  avoids becoming a vibration source. In this way, deterioration of a noise, vibration (NV, hereinafter referred to as “NV”) characteristic in a high rotation range of equipment on which the crankshaft  71  is mounted, that is, an internal combustion engine, is suppressed. 
     Here, the first damper  10  will be described in detail with reference to mainly  FIG. 3  to  FIG. 6 . The flange-like portion  11  of the first damper  10  is a disk-shaped member and has four bolt holes  11   a  provided every 90°. A fastening bolt  12  shown in  FIG. 1  and the like is inserted into each of the bolt holes  11   a , and thus the flange-like portion  11  and the main body  51  of the second damper  50  are joined to each other. Two opening portions  11   b  are provided in the flange-like portion  11  between the bolt holes  11   a . A rubber material forming the first elastic part  13  is poured into the opening portions  11   b  at the time of manufacturing the first damper  10 . In the completed first damper  10 , a state where the first elastic part  13  is exposed from the opening portions  11   b  is created. 
     The first damper  10  includes the first mass body  14  provided at the flange-like portion  11  via the first elastic part  13  formed of a rubber material as an example of an elastic material. The first mass body  14  in this embodiment is made of metal. The first elastic part  13  is interposed between the flange-like portion  11  and the first mass body  14 , whereby the first mass body  14  can move with the rotation of the flange-like portion  11 . The first mass body  14  moves with the rotation of the flange-like portion  11 , thereby attenuating the vibration of the crankshaft  71 . 
     The first mass body  14  has an approximately tubular shape. However, the cross-sectional shape of the first mass body  14  varies according to a position at which a cross section is taken. For example, as shown in  FIG. 5 , in the cross section along line V-V in  FIG. 3 , the thickness of the cross section of the first mass body  14  is relatively thin, and as shown in  FIG. 6 , in the cross section along line VI-VI in  FIG. 3 , the cross section of the first mass body  14  is made to be thick in a radial direction. Portions having a cross section that is thick in the radial direction are provided at four locations between the bolt holes  11   a . In this way, the mass distribution of the first mass body  14  is made uniform. 
     The first buffer part  15  having an annular shape is provided on the outer periphery of the first mass body  14  on the side away from the flange-like portion  11 . The first buffer part  15  is formed of a resin member. The first buffer part  15  is interposed between the first mass body  14  and the behavior limiter  51   a   1 , whereby the direct contact of the first mass body  14  with the behavior limiter  51   a   1  is avoided, and therefore, generation of abnormal noise is suppressed. Further, abrasion of the first mass body  14  or the behavior limiter  51   a   1  is suppressed. The first buffer part  15  of this embodiment is provided on the outer periphery of the first mass body  14 . However, the first buffer part  15  may be provided on the behavior limiter  51   a   1  side. In short, it is favorable that a buffer material that is interposed between the first mass body  14  and the behavior limiter  51   a   1  is provided so as to be able to avoid the contact between metals. 
     A second buffer part  16  having an annular shape is also provided on the outer periphery of the first mass body  14  on the side close to the flange-like portion  11 . The second buffer part  16  is formed of a resin member. The first mass body  14  has a tubular shape and is in a state of being supported on the first elastic part  13 . For this reason, it is assumed that the first mass body  14  rotates in a state of being inclined with respect to the center axis AX. When the first mass body  14  is inclined, it is also assumed that a state where the side of the first mass body  14  close to the flange-like portion  11  comes into contact with the flange-like portion  11  is created. Also in the case described above, when the first mass body  14  comes into direct contact with the flange-like portion  11 , generation of abnormal noise or abrasion is caused. Therefore, the second buffer part  16  is provided on the outer periphery of the first mass body  14  on the side close to the flange-like portion  11 , whereby generation of abnormal noise or abrasion is suppressed. 
     A cap member  17  is mounted on each of the first buffer part  15  side and the second buffer part  16  side in the first mass body  14 . The cap member  17  functions as a stopper for suppressing falling-off of the first buffer part  15  or the second buffer part  16 . 
     The second damper  50  will be described in detail with reference to mainly  FIG. 7  and  FIG. 8 . The second damper  50  has the cylindrical main body  51  provided with the first damper accommodation portion  51   a  and a shaft mounting portion  51   b  provided continuously with the first damper accommodation portion  51   a . The first damper accommodation portion  51   a  has a tubular shape and is provided with the behavior limiters  51   a   1  protruding inward at positions separated by 90°. In this embodiment, four behavior limiters  51   a   1  are provided. A bolt hole  51   a   11  is provided in each of the behavior limiters  51   a   1 . When the flange-like portion  11  is mounted on the main body  51 , the fastening bolt  12  is fastened to the bolt hole  51   a   11 . 
     The first elastic part  13 , the first mass body  14 , and the first buffer part  15  of the first damper  10  are accommodated in a region surrounded by the four behavior limiters  51   a   1 . In this way, the behavior limiters  51   a   1  are in a state of being disposed around the first mass body  14  on the outside in the rotation radial direction of the first mass body  14 . The first mass body  14  and the first buffer part  15  are accommodated in the first damper accommodation portion  51   a  such that the gap S (refer to  FIG. 2 ) is formed between each of the first mass body  14  and the first buffer part  15  and each of the behavior limiters  51   a   1  when being in a state where the crankshaft  71  does not rotate. 
     The inner peripheral surface of each behavior limiter  51   a   1  is a contact surface  51   a   12  that comes into contact with the first mass body  14  (the first buffer part  15 ) when the rotational frequency of the crankshaft  71  has become equal to or higher than a threshold value. 
     The behavior limiter  51   a   1  in this embodiment has an approximately rectangular shape. However, the shape of the behavior limiter  51   a   1  is not limited to a rectangular shape. The number of behavior limiters  51   a   1  in this embodiment is four. However, the number of behavior limiters  51   a   1  is also not limited to four. However, it is favorable that at least two behavior limiters  51   a   1  are provided, and it is favorable that the behavior limiters  51   a   1  are installed at equal intervals. 
     The shaft mounting portion  51   b  has a tubular shape, and a key groove  51   b   1  extending along the axial direction is provided on the inner peripheral surface of the shaft mounting portion  51   b . A key provided on the crankshaft  71  side is inserted in the key groove  51   b   1 . The main body  51  is fixed to the crankshaft  71  inserted into the shaft mounting portion  51   b  by fastening a shaft mounting bolt  70  (refer to  FIG. 1  and  FIG. 2 ). 
     A flange-like portion accommodation portion  51   a   2  formed in a recessed shape is provided at an end portion of the first damper accommodation portion  51   a  on the side opposite to the side on which the shaft mounting portion  51   b  is provided. The flange-like portion  11  is accommodated in the flange-like portion accommodation portion  51   a   2  in a state where the bolt hole  11   a  and the bolt hole  51   a   11  are aligned, and is integrated with the main body  51  by fastening the fastening bolt  12 . In this way, the flange-like portion  11  can rotate together with the crankshaft  71 . As described above, in the damper device  1  of this embodiment, the flange-like portion  11  can be removed from the main body  51 . For this reason, firstly, the shaft mounting bolt  70  is fastened in a state where the flange-like portion  11  is removed from the main body  51 , and thereafter, the flange-like portion  11  is mounted on the main body  51 , whereby the damper device  1  can be easily mounted on the crankshaft  71 . 
     A second mass body  53  is mounted on the outer periphery of the cylindrical main body  51  via a second elastic part  52  provided in an annular shape, and a third mass body  55  is further mounted on the outer periphery of the cylindrical main body  51  via a third elastic part  54  provided in an annular shape. In this way, the second damper  50  can function as a torsional damper. In this example, the second mass body  53  is used as a pulley for a timing belt. 
     In this embodiment, the main body  51  is equipped with the second mass body  53  or the third mass body  55 , thereby forming the second damper  50 , and the behavior limiter  51   a   1  is provided at the main body  51 . In this way, the first damper  10  and the second damper  50  are integrally provided, and thus downsizing of the damper device  1  is attained. However, the behavior limiter  51   a   1  does not need to be necessarily provided integrally with the second damper  50 , and may be provided separately from the second damper  50 . In other words, it is not indispensable to mount the second mass body  53  or the third mass body  55  on the main body  51  provided with the behavior limiter  51   a   1 . 
     Hereinafter, the effect of the damper device  1  of this embodiment will be described with reference to  FIG. 9 .  FIG. 9  shows a state where the first mass body  14  is in contact with the behavior limiter  51   a   1 . The hatching in  FIG. 9  is applied in order to easily distinguish the first mass body  14  and the behavior limiter  51   a   1  from other elements, and does not show the cross sections of the elements. When the crankshaft  71  on which the damper device  1  is mounted enters a high rotation state, the swing width of the first mass body  14  increases due to the centrifugal force, and, as shown in  FIG. 9 , the first mass body  14  comes in contact with any one of the behavior limiters  51   a   1 , so that the movement of the first mass body  14  is limited. As a result of the limitation of the movement of the first mass body  14 , the first damper  10  does not become a vibration source in the high rotation range of the internal combustion engine, and thus deterioration of the NV of a vehicle is suppressed. 
     A direction in which the first mass body  14  swings is affected by various factors such as variation in manufacturing of the first mass body  14  or the mounting state of the damper device  1  on the crankshaft  71 . However, in the damper device  1  of this embodiment, due to the contact of the first mass body  14  with any one of the behavior limiters  51   a   1  in the high rotation range of the internal combustion engine, the movement of the first mass body  14  is limited. Due to the above, it is unnecessary to designate or manage the behavior limiter  51   a   1  with which the first mass body  14  comes into contact, among the four behavior limiters  51   a   1 . 
     The first mass body  14  is set so as to come into contact with the behavior limiter  51   a   1  when the rotational frequency of the crankshaft  71  has become equal to or higher than a threshold value set in advance. Here, the threshold value is associated with an initial value S0 of the gap S between the first mass body  14  and the behavior limiter  51   a   1 . Referring to  FIG. 10 , the gap S between the first mass body  14  (the first buffer part  15 ) and the behavior limiter  51   a   1  decreases as an engine speed, that is, the rotational frequency of the crankshaft  71  increases, and finally becomes zero. The threshold value is the engine speed that becomes the boundary between an attenuation needed range and an attenuation unneeded range. The initial value S0 is set such that the engine speed at which the gap S between the first mass body  14  (the first buffer part  15 ) and the behavior limiter  51   a   1  becomes zero becomes the boundary between the attenuation needed range and the attenuation unneeded range. The movement of the first mass body  14  is affected by the dimensions, the shape, and the mass of the first mass body  14 , and further, the hardness, the shape, and the dimensions of the first elastic part  13 , or the like. Due to the above, the initial value S0 is adjusted in consideration of the above factors as well. In a case where it is desired to set the attenuation unneeded range to a higher engine speed region, the initial value S0 may be set to be larger. 
     In the attenuation needed range, the first mass body  14  does not come into contact with the behavior limiter  51   a   1 , and therefore, the damper device  1  can exhibit an attenuation function. In contrast, in a case where the engine speed increases and enters the attenuation unneeded range, the first mass body  14  comes into contact with the behavior limiter  51   a   1 , so that the movement of the first mass body  14  is limited, and therefore, the first damper  10  does not become a vibration source and deterioration of the NV of the vehicle is suppressed. In a case where the engine speed decreases and returns to the attenuation needed range again, the damper device  1  returns to a state of being able to exhibit the attenuation function. 
     As described above, with the damper device  1  of this embodiment, deterioration of the NV characteristic in the high rotation range of the internal combustion engine on which the crankshaft  71  is mounted can be suppressed. 
     The above embodiment is merely an example for implementing the disclosure, and the disclosure is not limited to the embodiment. Various modifications of the embodiment are within the scope of the disclosure, and it is obvious from the above description that various other examples are possible within the scope of the disclosure.