Abstract:
To provide a braking device that achieves unidirectionality without limiting the direction of rotation of a rotor. The present invention is characterized by being equipped with a housing ( 10 ), a rotor ( 20 ) provided inside the housing ( 10 ), brake shoes ( 30 ) provided between the rotor ( 20 ) and the housing ( 10 ), first protruding parts ( 40 ) that move together with the brake shoes ( 30 ), and second protruding parts ( 50 ) that move in conjunction with the rotation of the rotor ( 20 ), with the first protruding parts ( 40 ) riding up on the second protruding parts only when the rotor ( 20 ) rotates in the normal direction, and thereby generating greater friction between the brake shoes ( 30 ) and the housing ( 10 ) than the friction that can be generated between the brake shoes ( 30 ) and the housing ( 10 ) when the rotor ( 20 ) rotates in the reverse direction.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a braking device and, in more detail, relates to a device that stops or decelerates an object in motion, with friction. 
       BACKGROUND ART 
       [0002]    Conventionally, a device that stops or decelerates an object in motion with friction, has been known. For example, JP 2011-012750 A discloses a braking device including a bearing including a frictional material, a shaft inserted into the bearing, and a unidirectional clutch that rotates the shaft only in one direction. The device generates friction between the shaft and the bearing upon normal rotation of the shaft. However, this is a configuration in which the friction between the shaft and the bearing also occurs upon reverse rotation of the shaft. Therefore, the device prevents the reverse rotation of the shaft, with the unidirectional clutch. According to the device, only when an object to be controlled (hereinafter, the object to be controlled is simply referred to as an “object”) rotates in the one direction, motion of the object can be stopped or decelerated. Performance in which motion of an object can be stopped or decelerated only when the object rotates in one direction, is referred to as “unidirectionality”, below. 
         [0003]    However, the unidirectional clutch is required in order to regulate a rotational direction of the shaft in the conventional technique. Therefore, the amount of assembly man-hours inevitably also increases because of a large number of components. As a result, there is a problem that manufacturing costs are high. In addition, dimensional accuracy of the shaft to be integrated with the unidirectional clutch is high, and hardness of a surface of the shaft is required. Thus, there is a problem that processing costs of the shaft are high. Furthermore, there is a problem that providing the unidirectional clutch results in an increase of the device in size. 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent Literature 1: JP 2011-012750 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    An object of the present invention is to provide a braking device capable of achieving unidirectionality without regulating a rotational direction of a rotor. 
       Solution to Problem 
       [0006]    In order to solve the above problem, the present invention provides a braking device including: a housing; a rotor provided inside the housing; a brake shoe provided between the rotor and the housing; a first protruding part configured to move together with the brake shoe; and a second protruding part configured to move in association with rotation of the rotor. The first protruding part gets on the second protruding part only when the rotor is in normal rotation such that friction larger than friction occurring between the brake shoe and the housing when the rotor is in reverse rotation, occurs between the brake shoe and the housing. 
       Advantageous Effects of Invention 
       [0007]    The present invention provides a configuration in which the first protruding part gets on the second protruding part only when the rotor is in normal rotation such that friction larger than friction occurring between the brake shoe and the housing when the rotor is in reverse rotation, occurs between the brake shoe and the housing. Therefore, according to the present invention, the unidirectionality can be achieved without the rotational direction of the rotor regulated. In addition, the present invention requires no unidirectional clutch so as to be able to solve all various problems caused by providing the unidirectional clutch. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1  is a sectional view of a braking device according to Example 1. 
           [0009]      FIG. 2  is a sectional view taken along line A-A of  FIG. 1 . 
           [0010]      FIG. 3  is a plan view of a rotor. 
           [0011]      FIG. 4  is a partially sectional view for describing operation of the braking device. 
           [0012]      FIG. 5  is another partially sectional view for describing the operation of the braking device. 
           [0013]      FIG. 6  is another partially sectional view for describing the operation of the braking device. 
           [0014]      FIG. 7  is a sectional view of a braking device according to Example 2. 
           [0015]      FIG. 8  is a sectional view taken along line B-B of  FIG. 7 . 
           [0016]      FIG. 9  is a partially sectional view for describing operation of the braking device. 
           [0017]      FIG. 10  is another partially sectional view for describing the operation of the braking device. 
           [0018]      FIG. 11  is another partially sectional view for describing the operation of the braking device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0019]    Embodiments of the present invention will be more specifically described below based on examples according to the present invention. However, the technical scope of the present invention is not limited to the detailed descriptions below. 
       Example 1 
       [0020]    As illustrated in  FIG. 1 , a braking device according to Example 1 includes a housing  10 , a rotor  20 , brake shoes  30 , first protruding parts  40 , and second protruding parts  50 . 
         [0021]    The housing  10  includes a peripheral wall  11 , a bottom wall  12 , flanges  13 , and a lid  14 . As illustrated in  FIG. 1 , the peripheral wall  11  has a cylindrical shape. As illustrated in  FIG. 2 , the bottom wall  12  is integrally formed with the peripheral wall  11  so as to blockade the side of a lower end of the peripheral wall  11 . As illustrated in  FIG. 2 , the flanges  13  are integrally formed with the peripheral wall  11  so as to protrude from the peripheral wall  11  to the outside. As illustrated in  FIG. 2 , the lid  14  is integrated with the peripheral wall  11  so as to blockade the side of an upper end of the peripheral wall  11 . The housing  10  is fixed so as to be used. Bolts for fixing the housing  10  are individually inserted into holes  13   a  formed through the flanges  13 . 
         [0022]    As illustrated in  FIGS. 1 and 2 , the rotor  20  is provided to the inside of the housing  10 . The rotor  20  is coupled to a shaft that operates together with motion of an object and rotates (not illustrated, hereinafter, the shaft is simply referred to as the “shaft of the object”) so as to be used. The rotor  20  has a hole  20   a  with which the shaft of the object combines. The rotor  20  combined with the shaft of the object performs normal rotation in the housing  10  when the object moves in one direction (rotation in a clockwise direction in  FIG. 1 ). The rotor  20  performs reverse rotation in the housing  10  when the object moves in the reverse direction (rotation in a counterclockwise direction in  FIG. 1 ). 
         [0023]    As illustrated in  FIG. 3 , the rotor  20  includes first grooves  21  and second grooves  22 . The first grooves  21  have predetermined depths from an outer circumferential surface  20   b  of the rotor  20 . The second grooves  22  have predetermined depths from bottoms  21   a  of the first grooves  21 . The “depths” described here correspond to lengths in a diameter direction. Semicircular grooves  23  are formed in bottoms  22   a  of the second grooves  22 . 
         [0024]    As illustrated in  FIG. 1 , the brake shoes  30  are provided between the rotor  20  and the housing  10 . The brake shoes  30  are formed of rubber or elastomer. The brake shoes  30  arranged in the first grooves  21  formed on the rotor  20  are formed so as to include shapes having outer surfaces abutting on an inner surface  11   a  of the peripheral wall  11  of the housing  10 , and inner surfaces abutting on the bottoms  21   a  of the first grooves  21 . 
         [0025]    One brake shoe  30  is at least provided at one position. However, that type of configuration has a risk that partial wear of the one brake shoe  30  occurs. Therefore, brake shoes  30  are preferably arranged at a plurality of positions at regular intervals. Partial wear barely occurs in a configuration including two brake shoes  30  arranged at two positions at regular intervals, in comparison to the configuration including the one brake shoe  30  arranged at the one position. However, there is still a risk that the partial wear occurs. Therefore, three brake shoes  30  are most preferably arranged at at least three positions at regular intervals. According to the present example, as illustrated in  FIG. 1 , the brake shoes  30  are arranged at three positions mutually at an interval of 120°. With this configuration, partial wear of the brake shoes  30  can be prevented. 
         [0026]    As illustrated in  FIG. 1 , the first protruding parts  40  are provided so as to move together with the brake shoes  30 . The first protruding parts  40  may be integrally formed with the brake shoes  30 . However, in a case where the first protruding parts  40  are incapable of rotating, the first protruding parts  40  are easily worn due to friction between the first protruding parts  40  and the second protruding parts  50 . Therefore, preferably, the first protruding parts  40  are independent of the brake shoes  30 , and are capable of rotating. 
         [0027]    As illustrated in  FIG. 1 , the second protruding parts  50  are provided so as to move in association with rotation of the rotor  20 . The second protruding parts  50  may be integrally formed with the rotor  20 . However, in a case where the second protruding parts  50  are incapable of rotating, the second protruding parts  50  are easily worn due to the friction between the first protruding parts  40  and the second protruding parts  50 . Therefore, preferably, the second protruding parts  50  are independent of the rotor  20 , and are capable of rotating. 
         [0028]    The first protruding parts  40  and the second protruding parts  50  are preferably selected from parallel pins and steel balls in consideration of easy rotation and wear resistance. However, in a case where one or both of a first protruding part  40  and a second protruding part  50  are steel balls, since an area with which mutually coming in contact is small, wear easily occurs in comparison to a case where both are parallel pins. In a case where the parallel pins come in contact with each other, since an area with which mutually coming in contact is large, wear barely occurs. Therefore, the first protruding parts  40  and the second protruding parts  50  both are preferably parallel pins. 
         [0029]    The first protruding parts  40  adopted in the present example are the parallel pins, and fit into semicircular grooves  31  formed on inner surfaces of the brake shoes  30 . As illustrated in  FIG. 1 , parts of the first protruding parts  40 , protruding from the brake shoes  30  are arranged in the second grooves  22 . The second protruding parts  50  adopted in the present example are also parallel pins. As illustrated in  FIG. 1 , the second protruding parts  50  fit into the grooves  23  formed in the bottoms  22   a  of the second grooves  22 . 
         [0030]    The first protruding parts  40  are preferably in contact with the second protruding parts  50  at all times. This is because a configuration in which a state where the first protruding parts  40  and the second protruding parts  50  are in no contact with each other, is present, requires time for the second protruding parts  50  to come in contact with the first protruding parts  40  when the rotor  20  is in normal rotation, and responsiveness degrades. In addition, collision sounds occur when the first protruding parts  40  and the second protruding parts  50  come in contact with each other. When the first protruding parts  40  and the second protruding parts  50  remain in continually contact with each other, the responsiveness is satisfactory. The occurrence of the collision sounds can be also prevented. 
         [0031]    The braking device including the above configuration operates as follows: That is, when the rotor  20  performs the normal rotation, the second protruding parts  50  move in the clockwise direction in  FIG. 1  in association with the rotation of the rotor  20  (hereinafter, this direction is referred to as a “braking direction”). In this case, the outer surfaces of the brake shoes  30  come in surface contact with the inner surface  11   a  of the peripheral wall  11  of the housing  10 . Thus, the brake shoes  30  do not move in the braking direction simultaneously with starting of the rotor  20  so that the first protruding parts  40  get on the second protruding parts  50 . The brake shoes  30  are compressed between the first protruding parts  40  and the peripheral wall  11  so as to be deformed. As a result, the brake shoes  30  move in the braking direction, thrusting the inner surface  11   a  of the peripheral wall  11  with elastic force of the brake shoes  30 . Thus, friction that stops or decelerates the motion of the object, occurs between the brake shoes  30  and the housing  10 . 
         [0032]    When the rotor  20  is in the normal rotation, the degree of causing the first protruding parts  40  to get on the second protruding parts  50  is proportional to rotating force of the rotor  20 . Thus, the magnitude of the friction occurring between the brake shoes  30  and the housing  10  varies in proportion to the rotating force of the rotor  20 . That is, when the rotating force of the rotor  20  is small, as illustrated in  FIG. 4 , the first protruding parts  40  slightly get on the second protruding parts  50  (the degree of getting-on is low) so that the elastic force of the brake shoes  30  also decreases. Therefore, the friction occurring between the brake shoes  30  and the housing  10 , is small. Meanwhile, when the rotating force of the rotor  20  is large, as illustrated in  FIG. 5 , the first protruding parts  40  considerably get on the second protruding parts  50  (the degree of getting-on is high) so that the elastic force of the brake shoes  30  is made to be large. Therefore, the friction occurring between the brake shoes  30  and the housing  10  is large. 
         [0033]    When the rotor  20  performs the reverse rotation, side wall surfaces  22   b  of the second grooves  22  formed on the rotor  20  thrust the first protruding parts  40  in the counterclockwise direction in  FIG. 1  (hereinafter, the direction is referred to as a “non-braking direction). However, in this case, the second protruding parts  50  move in the non-braking direction in association with the rotation of the rotor  20  so that the first protruding parts  40  do not get on the second protruding parts  50  as illustrated in  FIG. 6 . Therefore, no elastic force of the brake shoes  30  occurs so that a degree of friction that stops or decelerates the motion of the object, does not occurs between the brake shoes  30  and the housing  10 . 
         [0034]    As described above, the braking device according to the present example includes the configuration in which the first protruding parts  40  get on the second protruding parts  50  only when the rotor  20  is in the normal rotation so that friction larger than the friction that can occur between the brake shoes  30  and the housing  10  when the rotor  20  is in the reverse rotation, occurs between the brake shoes  30  and the housing  10 . Therefore, according to the braking device, unidirectionality can be achieved without the rotational direction of the rotor  20  regulated. The braking device also requires no unidirectional clutch so that the number of components is remarkably small. Therefore, there is an advantage that the amount of assembly man-hours is remarkably small and manufacturing costs are low. The braking device also has a simple configuration and requires no unidirectional clutch so that miniaturization of the device can be achieved. 
       Example 2 
       [0035]    As illustrated in  FIGS. 7 and 8 , a braking device according to Example 2 further includes supporting members  60  for supporting brake shoes  30 , differently from the braking device according to Example 1. 
         [0036]    The supporting members  60  are provided between a rotor  20  and the brake shoes  30 . Inner surfaces  60   a  of the supporting members  60  are in contact with bottoms  21   a  of first grooves  21  formed on the rotor  20 . Before starting of the rotor  20 , gaps between outer surfaces  60   b  of the supporting members  60  and an inner surface  11   a  of a peripheral wall  11  of a housing  10 , are formed. Grooves  61  on which the brake shoes  30  are mounted are formed on the outer surfaces  60   b  of the supporting members  60 . Grooves  62  into which first protruding parts  40  fit are formed on the inner surfaces  60   a  of the supporting members  60 . The supporting members  60  are formed of a material that barely deforms in comparison to the brake shoes  30 , such as rubber, elastomer, or metal, having elasticity lower than that of the brake shoes  30 . 
         [0037]    The supporting members  60  have a function for preventing the first protruding parts  40  from getting over second protruding parts  50 . That is, when a situation in which the first protruding parts  40  that have got on the second protruding parts  50  get over the second protruding parts  50  due to rotating force exceeding a normal range of the rotor  20 , occurs, braking force due to friction no longer occurs. Thus, there is a need to prevent this. As illustrated in  FIG. 10 , the outer surfaces  60   b  of the supporting members  60  abut on the peripheral wall  11  of the housing  10  so that the brake shoes  30  are inhibited from further deforming even in a case where the first protruding parts  40  are about to get over the second protruding parts  50  due to the rotating force exceeding the normal range of the rotor  20  when the rotor  20  is in normal rotation. Thus, the braking device according to the present example, can effectively prevent the first protruding parts  40  from getting over the second protruding parts  50 . 
         [0038]    The braking device according to the present example, operates, similarly to the braking device according to Example 1, in a case where the rotating force of the rotor  20  remain in the normal range. That is, when the rotor  20  performs the normal rotation, the second protruding parts  50  move in a braking direction in association with rotation of the rotor  20 . In this case, outer surfaces of the brake shoes  30  come in surface contact with the inner surface  11   a  of the peripheral wall  11  of the housing  10 . Accordingly, the brake shoes  30  do not move in the braking direction simultaneously with the starting of the rotor  20  so that the first protruding parts  40  get on the second protruding parts  50  as illustrated in  FIG. 9 . The brake shoes  30  are compressed between the supporting members  60  and the peripheral wall  11  so as to deform. As a result, the brake shoes  30  move in the braking direction, thrusting the inner surface  11   a  of the peripheral wall  11  due to elastic force of the brake shoes  30 . Thus, friction that stops or decelerates motion of an object, occurs between the brake shoes  30  and the housing  10 . 
         [0039]    Meanwhile, when the rotor  20  performs reverse rotation, side wall surfaces  22   b  of second grooves  22  formed on the rotor  20  thrust the first protruding parts  40  in a non-braking direction. However, in this case, the second protruding parts  50  move in the non-braking direction in association with the rotation of the rotor  20  so that the first protruding parts  40  do not get on the second protruding parts  50  as illustrated in  FIG. 11 . Therefore, no elastic force of the brake shoes  30  occurs so that a degree of friction that stops or decelerates the motion of the object, does not occurs between the brake shoes  30  and the housing  10 . 
         [0040]    As described above, the braking device according to the present example includes the configuration in which the first protruding parts  40  get on the second protruding parts  50  only when the rotor  20  is in the normal rotation so that friction larger than the friction that can occur between the brake shoes  30  and the housing  10  when the rotor  20  is in the reverse rotation, occurs between the brake shoes  30  and the housing  10 . Therefore, according to the braking device, unidirectionality can be achieved without the rotational direction of the rotor  20  regulated. The braking device requires no unidirectional clutch, similarly to the braking device according to Example 1, so that the number of components is remarkably small. Therefore, there is an advantage that the amount of assembly man-hours is remarkably small and manufacturing costs are low. The braking device also has a simple configuration and requires no unidirectional clutch so that miniaturization of the device can be achieved. 
       REFERENCING LIST 
       [0000]    
       
           10  housing 
           11  peripheral wall 
           11   a  inner surface of the peripheral wall 
           12  bottom wall 
           13  flange 
           13   a  hole 
           14  lid 
           20  rotor 
           20   a  hole 
           20   b  outer circumferential surface of the rotor 
           21  first groove 
           21   a  bottom of the first groove 
           22  second groove 
           22   a  bottom of the second groove 
           22   b  side wall surface of the second groove 
           23  groove 
           30  brake shoe 
           31  groove 
           40  first protruding part 
           50  second protruding part 
           60  supporting member 
           60   a  inner surface of the supporting member 
           60   b  outer surface of the supporting member 
           61  groove 
           62  groove