Abstract:
A wheel simultaneous brake mechanism for simultaneously braking two wheels includes two respective engaging members that are selectively movable between an engaged position and a disengaged position for selectively braking or releasing the two wheels. Each engaging member is biased by a spring toward its respective engaged position. The two engaging members are connected to one another in a manner transmitting a tensile force therebetween by a wire, so that the engagement or release of both engaging members can be actuated together in unison.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a wheel simultaneous brake mechanism and a caster rotation preventing mechanism and more particularly, it relates to a wheel simultaneous brake mechanism and a caster rotation preventing mechanism which always work on the safe side and have a simple constitution. 
   2. Description of the Background Art 
   A conventional wheel stopping apparatus is disclosed in Japanese Unexamined Patent Publication NO. 60-240566, for example. According to the conventional wheel stopping apparatus, wheel stopping mechanisms are provided at two rear wheels in a baby carriage and they are constituted so as to be moved together by a wire. Both wheel stopping mechanisms can be operated at the same time by operating an operating member provided at either one of the two rear wheels. 
   The conventional wheel stopping mechanism is constituted as described above. Although both wheel stopping mechanisms can be operated at the same time by operating one operating member, little consideration is given to a case where the operating member is broken or a wire or the like connected to the operating member is cut. In addition, there is a problem that a constitution of the wheel stopping mechanism is complicated and the number of parts is large so that the cost is increased. 
   SUMMARY OF THE INVENTION 
   The present invention was made in view of the above problems and it is an object of the present invention to provide a wheel simultaneous brake mechanism in which measures are taken for a case where an operating member or the like is broken, and which the construction or constitution is simple. 
   Another object of the present invention is to provide a caster rotation preventing mechanism in which measures taken for a case where an operating member or the like is are broken, and in which the construction or constitution is simple. 
   Still another object of the present invention is to provide a baby carriage having four casters whose movement is stable. 
   A wheel simultaneous brake mechanism for stopping a first wheel and a second wheel at the same time according to the present invention comprises first and second wheel engagement equipments provided at the first and second wheels, respectively. The first wheel engagement equipment comprises a first engaging member movable between a first position in which it engages with the first wheel and a second position in which it does not engage with the first wheel, a first spring for forcing the first engaging member to the first position, and an operating member operated to position the first engaging member at the first position or at the second position. The second wheel engagement equipment comprises a second engaging member movable between a first position in which it engages with the second wheel and a second position in which it does not engage with the second wheel and a second spring for forcing the second engaging member to the first position. The wheel simultaneous brake mechanism further comprises a connecting unit for connecting the first and second engaging members so that they are moved together in such a manner that when the operating member is operated so as to position the first engaging member at the first position, then the second engaging member may also be positioned at the first position, and when the operating member is operated so as to position the first engaging member at the second position, then the second engaging member may also be positioned at the second position, and still further comprises a position holding unit for holding the second engaging member at the second position, when the operating member is operated so as to position the first engaging member at the second position. 
   Since the first and the second engaging members are forced so as to engage with the first and the second wheels by the first and the second springs, even when the operating member is broken or the wire is cut, the state in which the brake is put on can be maintained. As a result, there can be provided the wheel simultaneous brake mechanism in which measures are taken for a case where the operating member or the like is broken. 
   Preferably, first and second wheel holding units for holding the first and second wheels are provided, and the first wheel engagement equipment is rotatably connected to the first wheel holding unit through a pin, the first wheel holding unit and the first wheel engagement equipment comprise a concave part provided on one side and a convex part provided on the other side, and the position holding unit holds the first engaging member at the second position by engagement of the concave part and the convex part. 
   Since the holding unit holds the first engaging member at the second position by the engagement of the concave part and the convex part, the state in which the brake is put off can be maintained with a simple constitution. 
   Further preferably, the connecting unit is a wire having a predetermined length so that tensile force is always provided between the first and second engaging members. 
   Still further preferably, two concave parts are provided on one side of the first wheel holding unit and the first wheel engagement equipment, and one of the two concave parts corresponds to the first position and the other corresponds to the second position. 
   Another aspect of the present invention relates to a caster rotation preventing mechanism for simultaneously stopping rotation of rotation yokes of a first caster and a second caster which each respectively comprise one of the rotation yokes which can be rotated in any direction around an axis line in the vertical direction, and a wheel rotatably supported by the rotation yoke by an axle extending in the horizontal direction. This mechanism comprises first and second caster engaging devices provided at the first and second casters, respectively. The first caster engaging device comprises a first engaging member movable between a first position in which it engages with the first caster and a second position in which it does not engage with the first caster, a first spring forcing the first engaging member to the first position, and an operating member by which the first engaging member is positioned at the first position or the second position. The second caster engaging device comprises a second engaging member movable between a first position in which it engages with the second caster and a second position in which it does not engage with the second caster, and a second spring forcing the second engaging member to the first position. The caster rotation preventing mechanism further comprises a connecting unit for connecting the first and second engaging members such that the second engaging member is also positioned at the first position when the operating member is operated so as to position the first engaging member at the first position, or the second engaging member is also positioned at the second position when the operating member is operated so as to position the first engaging member at the second position, and still further comprises a position holding unit for holding the second engaging member at the second position when the operating member is operated so as to position the first engaging member at the second position. 
   Since the first and the second engaging members are forced so as to engage with the first and the second casters by the first and the second springs, respectively, the caster can be held in a state in which the caster is not rotated even when the operating member is broken or the wire is cut. As a result, there can be provided a caster rotation preventing mechanism in which measures are taken for breakdown of the operating part or the like. 
   Preferably, the caster rotation preventing mechanism comprises first and second caster holding units for holding the first and the second casters, the first caster engaging device is rotatably connected to the caster holding unit through a pin, the first caster holding unit and the first caster engaging device have a concave part provided at one of them and a convex part provided at the other of them, and the position holding unit holds the first engaging member at the second position by engagement between the concave part and the convex part. 
   Further preferably, the connecting unit is a wire having a predetermined length in which tensile force is always provided between the first and the second engaging members. 
   Still further preferably, two concave parts are provided at one of the first caster holding unit and the first caster engaging device, and one of the two concave parts corresponds to the first position and the other corresponds to the second position. 
   According to still another aspect of the present invention, a baby carriage having four casters consisting of a pair of front caster and a pair of rear casters comprises a push rod by which the moving direction of the baby carriage can be changed so as to be pushed from behind or pushed from the front i.e. face-to-face, a first caster rotation stopping unit for simultaneously stopping the rotation of the pair of front casters, and a second caster rotation stopping unit for simultaneously stopping the rotation of the pair of rear casters. 
   Since the rotation of the pair of casters positioned on the rear side can be simultaneously stopped in either case in which the baby carriage is pushed from behind or pushed face-to-face by the push rod of the baby carriage, a stable movement can be achieved in the baby carriage having four casters. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing a baby carriage to which a wheel simultaneous brake mechanism according to one embodiment of the present invention is applied; 
       FIG. 2 . includes a top plan view ( FIG. 2A ) and a side view ( FIG. 2B ) showing a state in which a wheel engagement equipment of the wheel simultaneous brake mechanism is mounted on one of the rear wheels of the baby carriage; 
       FIG. 3  includes  FIGS. 3A and 3B  which are each an exploded perspective view of two wheel engagement equipments connected to each other by a wire, and  FIG. 3C  which is a detail view of a portion of a back side of the wheel engagement equipment of  FIG. 3A ; 
       FIG. 4  is a sectional view showing essential parts of two wheel engagement equipments connected to each other by a wire in a state in which the brake is put on; 
       FIG. 5  is a sectional view showing essential parts of the two wheel engagement equipments connected to each other by the wire in a state in which the brake is put off; 
       FIG. 6 . includes  FIGS. 6A and 6B  which are views showing operation states of the two wheel engagement equipments connected to each other by the wire; 
       FIG. 7 . includes four schematic views in  FIGS. 7A ,  7 B,  7 C and  7 D showing a baby carriage according to another embodiment of the present invention; and 
       FIG. 8  includes two views ( FIGS. 8A and 8B ) showing a concrete example of constitution according to another embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, an embodiment of the present invention is described with reference to the drawings. 
     FIG. 1  is a perspective rear view of a baby carriage to which a wheel simultaneous brake mechanism according to one embodiment of the present invention is applied. Referring to  FIG. 1 , the baby carriage comprises two front legs  11  and  12  and two rear legs  13  and  14 . Front wheel units  15  and  16  and rear wheel units  17  and  18  each consisting of double wheels are rotatably provided at lower ends of the front legs  11  and  12 , and the rear legs  13  and  14 , respectively. 
   According to this baby carriage, the wheel simultaneous brake mechanism is provided at the two wheel units selected from the four wheel units  15  to  18 . In general, the wheel simultaneous brake mechanism is preferably provided at the rear wheel units  17  and  18  in view of easiness of operations. Thus, a description is made of the case where the wheel simultaneous brake mechanism is provided at the rear wheel units  17  and  18  hereinafter. 
   As shown in  FIG. 1 , an operating member  30  to be described later is mounted on the rear wheel unit  17  and its operation movement is transmitted to the rear wheel Unit  18  by a wire provided in a tube  25 . In addition, the rear wheel unit  17  comprises an outer rear wheel  21  and an inner rear wheel  22 , and the rear wheel unit  18  comprises an outer rear wheel  24  and an inner rear wheel  23 . 
     FIG. 2A  is a plan view of a wheel engagement equipment  20  provided at the rear wheel unit  17  of the rear leg  13 , and  FIG. 2B  is a view taken along line B—B in  FIG. 2A . Referring to  FIGS. 2A and 2B , the wheel engagement equipment  20  comprises a wheel mounting member  28  provided at a lower part of the rear leg  13 , and the operating member  30  provided so as to be rotatable around the wheel mounting member  28  through a pin  35 . The outer rear wheel  21  and the inner rear wheel  22  are rotatably held by an axle  32 . The axle  32  is supported by a bearing part  34  provided at the wheel mounting member  28 . A plurality of ribs  33  extending in the radius direction are provided around the axle  32  of the outer rear wheel  21  and the inner rear wheel  22 . 
   The outer rear wheel  24  and the inner rear wheel  23  provided at the rear leg  14  have the same constitution as the wheels  21  and  22  basically. 
     FIGS. 2A and 2B  show a state in which the brake is put on the outer rear wheel  21  and the inner rear wheel  22 , in which a longitudinal engaging member  31  provided at the lower part of the operating member  30  engages with the ribs  33 . 
   When the brake is put off, that is, when the baby carriage is moved, the operating member  30  is operated to be rotated around the pin  35  in the direction shown by an arrow in the drawing, to disengage the engaging member  31  from the ribs  33 . 
   A concave part  56  (referring to  FIG. 3C ) for fixing a wire  26  is provided at the operating member  30  on the side of the inner rear wheel  22  in the vicinity of the engaging member  31 , and the wire  26  extends to a driven member to be described later with reference to the rear leg  14 , through a wire guide  27 . In addition, the wire  26  is guided by a tube  25 . The operating member  30  has a configuration so as to be easily operated in rotating the member  30  around the pin  35  by a foot as shown in  FIG. 2 . 
     FIG. 3A  is an exploded perspective view of the wheel engagement equipment  20  on the side of the rear leg  13 , and  FIG. 3B  is an exploded perspective view of a wheel engagement equipment  43  on the side of the rear leg  14 . Referring to  FIG. 3A , the operating member  30  and the wheel mounting member  28  which constitute the wheel engagement apparatus  20  are connected by passing the pin  35  through pierced holes  37   a  and  37   b  provided in the opposed walls  52   a  and  52   b  of the operating member  30 , and through pierced holes  38   a  and  38   b  provided in the opposed walls  53   a  and  53   b  of the wheel mounting member  28 . 
   The operating member  30  and the engaging member  31  are integrally constituted. Pierced holes  41   a  and  41   b  and pierced holes  42   a  and  42   b , whose usage is described later, are provided in the opposed walls  52   a  and  52   b  of the operating member  30 . In addition, projections  40  which engage with the pierced holes  41   a  and  41   b , and the pierced holes  42   a  and  42   b  are provided on an outer face of the opposed walls  53   a  and  53   b  of the wheel mounting member  28 . The wheel mounting member  28  and the bearing part  34  rotatably holding the axle  32  are integrally constituted. 
   Referring to  FIG. 3B , the wheel engagement equipment  43  on the side of the rear wheel  14  consists of a wheel mounting member  29  and a driven member  58  which is operated in accordance with the operation of the operating member  30 , similar to the wheel engagement equipment  20  on the side of the rear leg  13 . The driven member  58  is connected to the wheel mounting member  29  so as to be rotatable around a pin  47 , by passing the pin  47  through pierced holes  50   a  and  50   b  provided in a pair of opposed walls  73   a  and  73   b  of the wheel mounting member  29  and pierced holes  49   a  and  49   b  provided in a pair of walls  72   a  and  72   b  of the driven member  58 . In addition, projections  70   a  and  70   b , whose function is to be described later, are provided at predetermined positions outside of the opposed walls  73   a  and  73   b  of the wheel mounting member  29 . 
   The driven member  58  and an engaging member  45  are integrally constituted. On top of the wall  49   b  of the driven member  58 , there is provided a concave part  57  having a side wall, for holding an opposite end of the wire  26  mounted on the concave part  56  of the operating member  30  (referring to  FIG. 4 ). 
     FIG. 3C  is a view showing a configuration of the concave part  56  having a side wall, which is provided on a back face of the wall  52   b  shown in  FIG. 3A  and described in  FIG. 2 . The cylindrical end of the wire  26  is housed in the concave part  56 . 
     FIG. 4  is a view showing essential parts of inner structures of the wheel engagement equipment  20  on the side of the rear leg  13  and the wheel engagement equipment  43  on the side of the rear leg  14 . The view of the wheel engagement equipment  20  corresponds to a sectional view taken along line IV—IV in  FIG. 2A . 
   Referring to  FIG. 4 , when the operating member  30  and the wheel mounting member  28  are connected through the pin  35 , a spring  61  held by the pin  35  is pressed by a locking part  60  on the operating member side which is fixed to the operating member  30  and a locking part  62  on the wheel mounting member side which is fixed to the wheel mounting member  28  in the inside. In other words, by the spring  61 , the operating member  30  is always forced such that the engaging member  31  may engage with the ribs  33  as shown in  FIG. 2B , and in this state, the brake is put on the wheels. 
   Similar to the wheel engagement equipment  20 , according to the wheel engagement equipment  43 , when the driven member  58  and the wheel mounting member  29  are connected through the pin  47 , a spring  66  held by the pin  47  is pressed by a locking part  65  of the driven member side which is fixed to the driven member  58  and a locking part  67  on the wheel mounting member side which is fixed to the wheel mounting member  29 . In other words, by the spring  66 , the driven member  58  is always forced to come close to or pivot toward the bearing  46  of the wheel mounting member  29  as shown by an arrow in  FIG. 4 , so that the engaging member  45  provided at the lower end thereof may engage with ribs (not shown) provided around the axle of the outer rear wheel  24  and the inner rear wheel  23  of the rear leg  14 , and in this state, the brake is engaged or put on the wheels of the rear leg  14 . 
   Meanwhile, in this state, the other end of the wire  26  whose one end is held by the concave part  56  of the operating member  30  is housed in the concave part  57  of the driven member  58 . A length of the wire  26  is provided such that the operating member  30  and the driven member  58  are pulled to each other with tensile force without slack as shown by an arrow in the drawing. 
   Thus, since both operating member  30  and the driven member  58  are constituted such that the respective engaging members  31  and  45  may engage with the corresponding ribs  33 , the state where the brake is put on is still maintained in the event that the operating member  30  is broken or the wire  26  is cut, which is safe. 
   In addition, even when the wire  26  is removed, since the operating member  30  of the wheel engagement equipment  20  and the driven member  58  of the wheel engagement equipment  43  are both forced in the direction in which the brake is put on or engaged by the springs  61  and  66 , the state can be maintained even after the wire  26  was removed. Therefore, maintenance can be easily performed in the state in which the wire  26  is removed. 
   Furthermore, as shown in  FIGS. 2 and 3 , since both ends of the wire  26  are mounted on the concave parts  56  and  57  on the outer walls of the operating member  30  and the driven member  58  on the sides of the inner rear wheels  22  and  24 , respectively, the wire  26  can be easily removed. In this respect also, the maintenance can be easily performed. 
     FIG. 5  is a view showing a state in which the operating member  30  is operated against the force of the spring  61  to separate the engaging member  31  from the bearing part  34  on the side of the wheel engagement equipment  20  as shown by an arrow “a” in the drawing so as not to engage with the ribs  33 . At this time, the concave part  57  of the driven member  58  is pulled by the wire  26  in the direction shown by an arrow in the drawing and the driven member  58  is also moved against the force of the spring  66  as shown by an arrow “b” in the drawing. Thus, the engaging member  45  is separated from the ribs of the outer rear wheel  24  and the inner rear wheel  23 . As a result, the outer rear wheel  21  and the inner rear wheel  22  of the rear leg  13  and the outer rear wheel  24  and the inner rear wheel  23  of the rear leg  14  can be rotated. 
     FIG. 6  is a view showing operational states of the wheel engagement equipment  20  on the side of the rear leg  13  and the wheel engagement equipment  43  on the side of the rear leg  14  in which  FIG. 6A  shows a state in which the brake is engaged or put on and  FIG. 6B  shows a state in which the brake is disengaged or put off. When the brake is put on, the projection  40  (referring to  FIG. 3A ) provided at the wheel mounting member  28  engages with the positioning hole  41   a  for a stopped state, and when the brake is put off, it engages with the positioning hole  42   a  for a moving state (in addition, although the front side is shown only, the same engagement is made also on the opposite side). 
   Thus, since the state in which the brake is put on the wheels and the state in which the brake is put off the wheels are maintained by engagement of the projections and the positioning holes, the state in which the brake is put on and the state in which the brake is put off can be maintained with a simple constitution. 
   Meanwhile, the driven member  58  is pulled by the wire  26  in the direction shown by the arrow in the drawing and rotated around the pin  47 . At this time, since a projection  70  which follows an outer periphery of the driven member  58  is provided at the wheel mounting member  29 , the driven member  58  can be smoothly rotated. 
   Although the description was made of the example in which the wheel simultaneous brake mechanism is provided at the pair of rear wheels of the baby carriage in the above embodiment, the present invention is not limited to this. The wheel simultaneous brake mechanism can be applied to any two wheels of the baby carriage or a mobile object having a plurality of wheels other than the baby carriage. 
   Although the brake is put on the wheels in such a manner that the engaging member engages with ribs radiating from the axle in the above embodiment, the present invention is not limited to this and it may engage with a member provided at an arbitrary position of the axle. 
   Although the description was made of the case where the coil spring is used as a spring in the above embodiment, the present invention is not limited to this and another type of spring may be used. 
   Next, a description is made of another embodiment of the present invention. According to this embodiment, when four casters are provided as wheels of a baby carriage, the above mechanism is employed as a rotation preventing mechanism of two rear casters among the four casters of the baby carriage in the moving direction. 
     FIG. 7  is a schematic view of the baby carriage shown in  FIG. 1 .  FIG. 7A  is a schematic view showing an arrangement of the wheels when pushed face-to-face,  FIG. 7B  is a view (schematic side view) taken in the direction of arrows B in  FIG. 7A ,  FIG. 7C  is a schematic view showing an arrangement of the wheels when pushed from behind, and  FIG. 7D  is a view (schematic side view) taken in the direction of arrows D in  FIG. 7C . 
   Here, four wheel units  15  to  18  of a baby carriage  10  are all casters having rotation yokes  91  and  94 . Thus, when all of the wheel units of the baby carriage are casters, the moving direction of the baby carriage can be changed over between a state pushed from behind ( FIGS. 7C and 7D ) and a state pushed face-to-face ( FIGS. 7A and 7B ) only by switching a push rod  80  of the baby carriage  10  as shown in  FIG. 7B  or  7 D, so that the baby carriage can be moved in any direction. 
   However, when all of the four wheels of the baby carriage  10  are casters, the traveling path of the baby carriage  10  meanders. In order to avoid such meandering movement, it is necessary to prevent the rotation of the wheels positioned at the back of the baby carriage  10  in the moving direction. Thus, according to this embodiment, the mechanism described above is used as a mechanism for preventing the rotation of the casters positioned at the back of the baby carriage  10  in the moving direction. 
   Referring to  FIGS. 7A and 7B , in the case of the state pushed face-to-face, the wheel units  17  and  18  positioned backward in the moving direction are held so as to be positioned in a predetermined relation with each other by a wire  26 , in order to prevent the casters of the wheel units  17  and  18  from rotating around the rotation yoke  91 . 
     FIG. 8A  is an enlarged view of a part shown by VIII in  FIG. 7A  and  FIG. 8B  is a side view taken in the direction of the arrows B in  FIG. 8A . 
   Referring to  FIGS. 8A and 8B , a wheel part comprises a caster holding member  87  (which corresponds to the wheel mounting member  28  in the prior embodiment), an engaging member  83  rotatably held by the caster holding member  87  through a pin  84 , and a caster  90  held by the caster holding member  87 . 
   The caster  90  comprises a rotation yoke  91 , a supporting part  92  held by the rotation yoke  91 , for supporting an axle  32 , and a pair of rotation stopping members  93   a  and  93   b  provided at an upper part of the supporting part  92 . 
   The position of the engaging member  83  can be changed by an operating member  82 . When the engaging member  83  is moved around the pin  84  in the lower direction of an arrow in  FIG. 8B , the engaging member  83  is positioned between the pair of rotation stopping members  93   a  and  93   b  to prevent the caster  90  or particularly the axle supporting part  92  from rotating about the rotation yoke  91 . Meanwhile, when the engaging member  83  is moved around the pin  84  in the upper direction shown by the arrow in  FIG. 8B , the engaging member  83  is separated from the rotation stopping members  93   a  and  93   b  and the axle supporting part  92  can be rotated in any direction by or about the rotation yoke  91 . 
   In addition, similar to the prior embodiment, the engaging member  83  comprises a spring forcing the engaging member  83  in the lower direction shown by the arrow and a wire and the like as the connecting unit although they are not shown. 
   In addition, the engaging member  83  comprises two concave parts  85  and  86  provided at a position in which the rotation of the caster  90  is prevented and at a position in which the rotation of the caster  90  is allowed, respectively. A convex part (not shown) is provided in the caster holding member  87  so as to correspond to the two concave parts  85  and  86 . These concave and convex parts may be provided other way round. 
   Furthermore, the position of the engaging member  83  may be changed by setting the operating member  82  by hand or by moving the operating member  82  in a synchronized manner with the position of the push rod. 
   Although one embodiment of the present invention was described with reference to the drawings, the present invention is not limited to the illustrated embodiment only. Various kinds of modifications can be added to the illustrated embodiment within the same scope as that of the present invention or the equivalent scope as that.