Abstract:
An embodiment provides a damper a damper including: a housing; a rotor; and a sealing member. The housing includes outer and inner cylinder portions to define a filling space portion therebetween for filling with a viscose fluid. The rotor includes a head portion and a cylinder portion extended downwardly therefrom so as to be inserted into the filling space portion. The sealing member seals the filling space portion. The rotor further includes axially-extending first and second groove portions provided on outer and inner peripheral surfaces of the cylinder portion near the bottom portion thereof. At least one of the first groove portions includes a communicating portion which communicates the inside and the outside of the rotor, and the second groove portion is apart from the communicating portion in a circumferential direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority from Japanese Patent Application No. 2013-213233 filed on Oct. 10, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD 
     An aspect of the present invention relates to a damper producing torque by relative rotation of a housing and a rotor, and a handle device having the damper. 
     BACKGROUND 
     For example, in a vehicle, a handle device to be gripped by the passenger is provided to in-vehicle wall surfaces of a passenger seat and backseats. The handle device includes a grip portion provided rotatably, a spring portion arranged to urge the grip portion in a given rotational direction, and a damper arranged to damp the rotation of the grip portion. 
     For example, JP-2002-221247-A discloses an assist grip device including a rotary damper. This rotary damper includes a housing having an annular groove, a rotor having a main portion to be inserted into the annular groove and relatively rotatable to the housing, silicone oil filled in the annular groove, and sealing members for sealing the space between the rotor and the housing. 
     In JP-2002-221247-A, silicone oil is filled in the annular groove. In the annular groove, bubbles may be left in the silicone oil when being filled, or bubbles may enter the annular groove when the silicone oil leaks due to thermal expansion. When the bubbles spread in the annular groove at the time of relative rotation of the housing and the rotor, resistance by silicone oil cannot be obtained at the part where the bubbles spread, thereby reducing the torque to be produced by the damper. Since the annular groove is sealed in order to prevent leakage of the silicone oil, it is difficult to remove the bubbles after the damper has been assembled. 
     SUMMARY 
     One object of the present invention is to provide a technique for preventing reduction in torque during operation of a damper. 
     An aspect of the present invention provides 
     a damper including: 
     a housing that includes
         an outer cylinder portion,   an inner cylinder portion provided inwardly of the outer cylinder portion,   a bottom portion arranged to connect the outer cylinder portion and the inner cylinder portion and   a filling space portion defined between the outer cylinder portion and the inner cylinder portion, a viscose fluid being filled in the filling space portion;       

     a rotor that includes
         a head portion and   a rotor cylinder portion extended downwardly from the head portion and disposed in the filling space portion; and       

     a sealing member arranged to seal the filling space portion, 
     wherein the rotor further includes
         first groove portions provided on an outer peripheral surface of the rotor cylinder portion near the bottom portion apart from the sealing member so as to extend in an axial direction and   a second groove portion provided on an inner peripheral surface of the rotor cylinder portion near the bottom portion apart from the sealing member so as to extend in the axial direction, and       

     wherein at least one of the first groove portions includes a communicating portion which communicates the inside and the outside of the rotor, and the second groove portion is apart from the communicating portion in a circumferential direction. 
     According to the present embodiment, bubbles in the filling space portion that were left at the time of assembling the damper can be collected at the first groove portions and the second groove portion, which can prevent the bubbles from spreading onto a peripheral surface of the rotor. The bubbles on the outer side of the rotor can be moved to the inner side of the rotor through the communicating portion, and be made to stay in the second groove portion, which can prevent reduction in torque during operation of the damper. Because the second groove portion is apart from the communicating portion in the circumferential direction, the bubbles can be prevented from moving from the inner side to the outer side of the rotor. 
     Another aspect of the present invention provides 
     a handle device including: 
     a grip portion provided rotatable from a normal state to a usage state and arranged to be gripped by a user; 
     a shaft portion arranged to pivotally support the grip portion; 
     a spring portion arranged to urge the grip portion in a direction of returning from the usage state to the normal state; and 
     a damper arranged to damp a rotational movement of the grip portion, 
     wherein the damper includes: 
     a housing that includes
         an outer cylinder portion,   an inner cylinder portion provided inwardly of the outer cylinder portion,   a bottom portion arranged to connect the outer cylinder portion and the inner cylinder portion and   a filling space portion defined between the outer cylinder portion and the inner cylinder portion, a viscose fluid being filled in the filling space portion;       

     a rotor that includes
         a head portion and   a rotor cylinder portion extended downwardly from the head portion and disposed in the filling space portion; and       

     a sealing member arranged to seal the filling space portion, 
     wherein the rotor further includes
         first groove portions provided on an outer peripheral surface of the rotor cylinder portion near the bottom portion apart from the sealing member so as to extend in an axial direction and   a second groove portion provided on an inner peripheral surface of the rotor cylinder portion near the bottom portion apart from the sealing member so as to extend in the axial direction, and       

     wherein at least one of the first groove portions includes a communicating portion which communicates the inside and the outside of the rotor, and the second groove portion is apart from the communicating portion in a circumferential direction. 
     According to the present embodiment, bubbles in the filling space portion that were left at the time of assembling the damper can be collected at the first groove portions and the second groove portion, which can prevent the bubbles from spreading onto a peripheral surface of the rotor. The bubbles on the outer side of the rotor can be moved to the inner side of the rotor through the communicating portion, and be made to stay in the second groove portion, which can prevent reduction in torque during operation of the damper. Because the second groove portion is apart from the communicating portion in the circumferential direction, the bubbles can be prevented from moving from the inner side to the outer side of the rotor. 
     According to the present invention, reduction in torque during operation of the damper can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an assembly drawing of a handle device according to an embodiment. 
         FIGS. 2A and 2B  are perspective views of a damper according to the embodiment. 
         FIG. 3A  is a front view of a rotor, and  FIG. 3B  is a perspective view of the rotor. 
         FIG. 4A  is a cross-sectional view of the damper taken along the line A-A of  FIG. 2A , and  FIG. 4B  is a cross-sectional view of the rotor, a first O-ring, and a second O-ring. 
         FIGS. 5A and 5B  are views for illustrating a rotor according to a modification. 
         FIG. 6  is a cross-sectional view of the damper according to the modification along the axial direction. 
     
    
    
     DETAILED DESCRIPTION 
     A damper includes a housing filled with oil as a viscose fluid, and a rotor inserted in the housing. The damper produces torque by shear resistance and agitating resistance at the time of relative rotation of the housing and the rotor. 
     Bubbles may be left in a filling space portion when filling the viscose fluid at the time of assembling the damper, or bubbles may enter the housing upon volumetric change of the viscose fluid changes depending on the temperature. The bubbles may spread onto the peripheral surface of the rotor by being pressurized at the time of relative rotation of the housing and the rotor. Thus, the spread of the bubbles may change the shear resistance and may reduce the torque. That is, if the relative rotation of the housing and the rotor is performed many times, the torque produced by the damper may be reduced. 
     In order to solve these problems, first groove portions and a second groove portion are provided on the inner and outer peripheral surfaces of the rotor to collect the bubbles at the groove portions, which can prevent the bubbles from spreading onto the peripheral surfaces of the rotor. Further, the pressure of viscose fluid on the outer peripheral side of the rotor in the filling space portion is increased by centrifugal force at the time of rotation, so that bubbles that are lighter than the viscose fluid can be moved to the inner side of the rotor through a communicating portion provided to the rotor. The pressure of viscose fluid on the inner side of the rotor is lower than the pressure of viscose fluid on the outer side, so that the change in shear resistance by the bubbles that have moved to the inner side of the rotor becomes small. In addition, the moment on the outer side of the rotor is larger than the moment on the inner side of the rotor. Thus, stabilizing the production of torque on the outer side of the rotor can prevent reduction in torque as a whole of the damper. Because the second groove portion is provided on the inner peripheral surface of the rotor, bubbles can be collected at the second groove portion, which can prevent the bubbles from spreading onto the peripheral surfaces of the rotor. In addition, because the second groove portion is distanced from the communicating portion, the bubbles can be prevented from moving from the inner side to the outer side of the rotor even when the operation of the damper is completed. That is, the bubbles can be blocked in the second groove portion provided on the inner peripheral surface of the rotor. Thus, reduction in torque during operation of the damper can be prevented. 
       FIG. 1  is an assembly drawing of a handle device  10  according to an embodiment. The handle device  10  includes shaft portions  12 , holding portions  14 , a spring portion  16 , a grip portion  18 , and a damper  20 . The handle device  10  is provided rotatably to an in-vehicle wall surface. The holding portions  14  hold the spring portion  16  and the damper  20 . The spring portion  16  urges the grip portion  18  such that the grip portion  18  is folded to the in-vehicle wall surface. The grip portion  18  is gripped by a user. The shaft portions  12  pivotally support the grip portion  18  in a rotatable manner. 
     A normal state is defined as a state where the grip portion  18  is folded to the in-vehicle wall surface or a state where the grip portion  18  is close to the in-vehicle wall surface for resting. A usage state is defined as a state where the grip portion  18  is rotated from the normal state to be apart from the in-vehicle wall surface. The spring portion  16  urges the grip portion  18  in a rotational direction rotating from the usage state to the normal state. 
     In using the handle device  10 , the user holds the grip portion  18  to rotate the shaft portions  12 . After use, the user releases the hand from the grip portion  18  to put back the grip portion  18  to the original rotational position. The grip portion  18  is urged by the spring portion  16  to return toward the in-vehicle wall surface. In order to reduce an impact noise when the grip portion  18  is brought into contact with the wall surface, the speed of rotation of the grip portion  18  is slowed down by the damper  20 . 
       FIGS. 2A and 2B  are perspective views of the damper  20  according to the embodiment.  FIG. 2A  is a perspective view of the damper  20  on the side of an opening portion  33 .  FIG. 2B  is a perspective view of the damper  20  on the side of a bottom portion  38 . Same or equivalent components and members shown in the drawings are provided with same reference numerals, and repeated descriptions of the same or equivalent components and members are omitted as appropriate. 
     The damper  20  includes a housing  30 , a rotor  50 , a first O-ring  80 , and a second O-ring  82 . The rotor  50 , the first O-ring, and the second O-ring are housed in the housing  30 . The housing  30  and the rotor  50  have a cylindrical shape, and the shaft portion  12  is inserted into the center of the housing  30  and the rotor  50 . 
     The housing  30  includes an outer cylinder portion  32 , the opening portion  33 , an inner cylinder portion  34 , a protruding portion  36 , and the bottom portion  38 . The housing  30  has a double structure consisting of the outer cylinder portion  32  and the inner cylinder portion  34 . A viscose fluid is filled between the outer cylinder portion  32  and the inner cylinder portion  34 . Liquid such as oil is used as the viscose fluid. 
     A cylinder portion  54  of the rotor  50  is inserted between the outer cylinder portion  32  and the inner cylinder portion  34 . The housing  30  and the rotor  50  are relatively rotatable to each other, so that the damper  20  generates a damping force given by viscosity resistance at the time of the relative rotation. 
       FIG. 3A  is a front view of the rotor  50 , and  FIG. 3B  is a perspective view of the rotor  50 .  FIG. 4A  is a cross-sectional view of the damper  20  taken along the line A-A of  FIG. 2A , and  FIG. 4B  is a cross-sectional view of the rotor  50 , a first O-ring  80 , and a second O-ring  82 .  FIG. 4B  cross-sectionally shows the damper  20  of  FIG. 4A  by removing the housing  30 . 
     As shown in  FIG. 4A , the housing  30  includes a filling space portion  37  that is defined between the outer cylinder portion  32  and the inner cylinder portion  34  and in which the viscose fluid is filled. The filling space portion  37  has a cylindrical shape like the outer cylinder portion  32  and the inner cylinder portion  34 . The first O-ring  80  is disposed on the outer side of the rotor  50 , and the second O-ring  82  is disposed on the inner side of the rotor  50 . The first O-ring  80  and the second O-ring  82  (referred to as the O-rings when they are not distinguished from each other) seal the filling space portion  37 . The first O-ring  80  and the second O-ring  82  are disposed between the rotor  50  and the housing  30 . The first O-ring  80  and the second O-ring  82  function as the sealing member arranged to prevent leakage of the viscose fluid, and are made from a rubber material. 
     The first O-ring  80  and the second O-ring  82  have substantially the same wire diameter. The outer cylinder portion  32  and the inner cylinder portion  34  are connected at a one-end portion by the bottom portion  38 . The inner cylinder portion  34  provided inwardly of the outer cylinder portion  32  includes a groove portion  40  extending along the axial direction on the inner peripheral surface. 
     The protruding portion  36  protrudes outwardly in the radial direction on the outer peripheral surface of the outer cylinder portion  32 . The protruding portion  36  is brought into contact with the holding portion  14  or an in-vehicle inner wall to limit the rotation of the housing  30 . 
     The rotor  50  includes a head portion  52 , the cylinder portion  54 , protruding portions  56 , an annular concave portion  58 , first groove portions  60   a , first groove portions  60   b , notch portions  62 , communicating holes  64 , and second groove portions  66 . The head potion  52  has a disk shape including a center hole  53 . The protruding portions  56  protruding outwardly in the axial direction are disposed on the surface of the head portion  52 . The head portion  52  and the protruding portions  56  are exposed from the opening portion  33  of the housing  30 . 
     The protruding portions  56  are brought into contact with the grip portion  18  to limit the rotation of the rotor  50 . The cylinder portion  54  extends downwardly from the head portion  52 . The annular concave portion  58  is provided on the outer peripheral surface of the cylinder portion  54  near the head portion  52 , that is, disposed around the connecting portion between the head portion  52  and the cylinder portion  54 . The first O-ring  80  is disposed in the annular concave portion  58 . 
     The cylinder portion  54  includes the first groove portions  60   a  and the first groove portions  60   b  (referred to as the first groove portions  60  when they are not distinguished from each other) that are disposed on the outer peripheral surface near the bottom portion  38  apart from the first O-ring  80 , that is, on the distal end side, and extend along the axial direction. The first groove portions  60  are formed as concaves on the outer peripheral surface of the cylinder portion  54 . Thus, the first groove portions  60  can collect bubbles that are left on the outer peripheral side of the rotor  50 . The plural first groove portions  60  are provided in the circumferential direction apart from each other at regular intervals. 
     The first groove portions  60   a  each includes the notch portions  62  formed by notching a distal end portion of the cylinder portion  54  at the side of the bottom portion  38 . The first groove portions  60   b  each includes the plural communicating holes  64 . The notch portions  62  and the communicating holes  64  function as communicating portions through which the inside of the rotor  50  is communicated with the outside of the rotor  50 . Thus, bubbles in the filling space portion  37  that were left at the time of assembling the damper  20  can be moved to the inner side of the rotor  50  through the communicating portions, that is, through the notch portions  62  and the communicating holes  64 . Because the notch portions  62  and the communicating holes  64  are provided to the first groove portions  60 , bubbles collected at the first groove portions  60  can be easily moved to the notch portions  62  and the communicating holes  64 . Then, the bubbles that have moved to the inner side of the rotor  50  are kept in the second groove portions  66 , so that reduction in torque during operation of the damper  20  can be prevented. 
     The first groove portions  60   a  including the notch portions  62  and the first groove portions  60   b  including the communicating holes  64  are alternately arranged in the circumferential direction as shown in  FIG. 3B . In comparison with a configuration where both of the notch portion  62  and the communicating holes  64  are provided to each of the first groove portions  60   a  and the first groove portions  60   b , the present configuration can prevent reduction in rigidity of the rotor  50 . By providing the notch portions  62  at the distal end of the cylinder portion  54  and providing the communicating holes  64  midway of the cylinder portion  54 , the notch portions  62  and the communicating holes  64  are disposed at different positions in the axial direction. Thus, bubbles extending in the axial direction can be moved to the inner side of the rotor  50  by the notch portions  62  and the communicating holes  64 . As described above, while reduction in rigidity of the rotor  50  can be prevented, performance for collecting bubbles can be improved. By providing the notch portions  62  at the distal end of the cylinder portion  54 , the communicating portions of the rotor  50  can be easily processed while bubbles staying at the bottom portion  38  can be easily collected. 
     The cylinder portion  54  includes the second groove portions  66  that are disposed on the inner peripheral surface near the bottom portion  38  apart from the second O-ring  82 , that is, on the distal end side, and extend along the axial direction as shown in  FIG. 4B . The second groove portions  66  are apart from the notch portions  62  and the communicating holes  64  in the circumferential direction. Thus, by collecting the bubbles that have moved to the inner side of the rotor  50  through the notch portions  62  and the communicating holes  64  to the second groove portions  66 , the bubbles in the second groove portions  66  can be prevented from moving to the outer side of the rotor  50  through the notch portions  62  and the communicating holes  64  when the rotation is completed. If groove portions for collecting bubbles were provided to the housing  30 , the groove portions of the housing  30  and the notch portions  62  and the communicating holes  64  of the rotor  50  would be opposed to each other many times at the time of relative rotation of the housing  30  and the rotor  50 , and thus, the bubbles in the inner side of the rotor  50  may move to the outer side of the rotor  50  through the notch portions  62  and the communicating holes  64 . Providing the first groove portions  60  and the second groove portions  66  to the rotor  50  and making the positions of the first groove portions  60  and the second groove portions  66  different from each other in the circumferential direction can prevent the bubbles from moving to the outer side of the rotor  50  at the time of relative rotation. 
     A second holding portion  70  for holding the second O-ring  82  is provided on the inner peripheral surface of the rotor  50  and the outer peripheral surface of the inner cylinder portion  34 . A first holding portion  68  for holding the first O-ring  80  is provided on the outer peripheral surface of the rotor  50  and the inner peripheral surface of the outer cylinder portion  32 . A holding space defined by the second holding portion  70  is longer in the axial direction than the first holding portion  68 . The O-rings can move in the axial direction in the holding spaces. The length in the axial direction of the second holding portion  70  is two times as large as or larger than the wire direction of the second O-ring  82 . Thus, the bubbles that have moved to the inner side of the rotor  50  can be moved to the space of the second holding portion  70 . If the viscose fluid is filled with excess amount in the housing  30 , the second holding portion  70  can absorb variation in amount of the viscose fluid. Assembling the damper  20  in a space under reduced pressure can reduce bubbles from being left in the filling space portion  37 . When the damper  20  is moved under atmospheric pressure after the assembly, the second O-ring  82  is pulled to the distal end side of the cylinder portion  54  in the second holding portion  70  by a difference in pressure between the inside and the outside. 
       FIGS. 5A and 5B  are views for illustrating a rotor  150  according to a modification.  FIG. 5A  is a front view of the first O-ring  180  and the rotor  150 , and  FIG. 5B  is a cross-sectional view of the rotor  150  taken along the axial direction in the middle. In  FIG. 5B , the first O-ring  180  and the second O-ring  182  are shown.  FIG. 6  is a cross-sectional view of a damper  120  according to the modification along the axial direction. 
     The rotor  150  according to the modification is different from the rotor  150  shown in  FIGS. 3A and 3B  in configuration of groove portions, communicating portions, and holding portions. The rotor  150  includes a head portion  152  and a cylinder portion  154  extended downwardly from the head portion  152 . The cylinder portion  154  includes first groove portions  160   a  and first groove portions  160   b  (referred to as the first groove portions  160  when they are not distinguished from each other) that are disposed on the outer peripheral surface near the bottom portion  138  apart from the first O-ring  180  to be extended along the axial direction, and second groove portions  166  that are disposed on the inner peripheral surface near the bottom portion  138  apart from the second O-ring  182  to be extended along the axial direction. 
     A housing  130  includes an outer cylinder portion  132 , an inner cylinder portion  134 , and a filling space portion  137  having a cylindrical shape and provided between the outer cylinder portion  132  and the inner cylinder portion  134 . A cylinder portion  154  of the rotor  150  is inserted into the filling space portion  137 . 
     The first groove portions  160   a , the first groove portions  160   b , and the second groove portions  166  can collect bubbles that are left in the filling space portion  137 . The first groove portions  160   a  each includes the notch portions  162  formed by notching a distal end portion of the cylinder portion  154  at the side of the bottom portion  138 . The notch portions  162  function as communicating portions through which the inside of the rotor  150  is communicated with the outside of the rotor  150 . Meanwhile, communicating portions such as the notch portions  162  are not provided to the first groove portions  160   b . To be specific, the first groove portions  160   a  including the notch portions  162  and the first groove portions  160   b  including no notch portions  162  are alternately arranged in the circumferential direction on the outer peripheral surface of the cylinder portion  154  as shown in  FIG. 5A  Thus, reduction in rigidity of the rotor  150  on the distal end side can be prevented. 
     The number of provided first groove portions  160  is eight, which is double in number of the first groove portions  160  of the rotor  150  shown in  FIGS. 3A and 3B . Increasing the number of the groove portions of the rotor  150  can increase agitating resistance at the time of relative rotation, which can produce large torque. 
     The number of provided second groove portions  166  on the inner peripheral surfaces of the cylinder portion  154  is four, which is half of the first groove portions  160  as shown in  FIG. 5B . In addition, the second groove portions  166  are apart from the notch portions  162  in the circumferential direction. Thus, the bubbles that have moved to the second groove portions  166  can be prevented from moving to the outer side of the rotor  150  through the notch portions  162 . 
     The present invention is not limited to the embodiments described above, and it is also possible to add modifications such as various kinds of design changes to the embodiments based on the knowledge of those skilled in the art. Embodiments to which such modifications will also fall within the scope of the present invention. 
     In the present embodiment, the protruding portion  36  of the housing  30  is brought into contact with the holding portion  14  or the in-vehicle inner wall while the protruding portions  56  of the rotor  50  are brought into contact with the grip portion  18 , and thereby torque is conveyed to the grip portion  18 . However, the present invention is not limited to the present embodiment. For example, a configuration such that the protruding portion  36  of the housing  30  is brought into contact with the grip portion  18  while the protruding portions  56  of the rotor  50  are brought into contact with the holding portion  14  or the in-vehicle inner wall is possible. 
     In the present embodiment, the grip portion  18  is folded to the in-vehicle wall surface in its normal state. However, the present invention is not limited to the present embodiment. For example, the handle device  10  may include limiting means for limiting rotation of the grip portion  18  at a given rotational position, and the normal state may be defined as a state where the grip portion  18  is at the given rotational position. Being at the given rotational position, the grip portion  18  remains still so as not to jut into the vehicle interior. The limiting means is brought into contact with the grip portion  18  at the given rotational position to limit the rotation. 
     In the present embodiment, the O-rings are used as the sealing member. However, the present invention is not limited to the present embodiment. For example, T-shaped packings or U-shaped packings may be used as the sealing member to prevent leakage of the viscose fluid from the filling space portion  37  to the outside.