Patent Publication Number: US-2023158840-A1

Title: Air supply system

Description:
TECHNICAL FIELD 
     The present disclosure relates to an air supply system that supplies the air to a tire by using rotation of a wheel. 
     BACKGROUND ART 
     An existing air supply system of this type has a pump that is attached to the wheel and keeps supplying the air to the tire by operating in concert with the rotation of the wheel. When the pressure inside the tire reaches or exceeds a reference level, the air that the pump discharges is released to the outside air (see, for example, Patent Literature 1). 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: JP 6-510252 T (Page 2, L25 lower left column to L11 lower left column,  FIG.  6   ) 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
      The existing air supply system described above sometimes has an issue of pump durability, because of which a technique that makes the pump durability higher than before is being sought to be developed. 
     Means of Solving the Problems 
     An air supply system according to one aspect of the present invention made to solve the above problem includes: a telescopic pump attached to a wheel and discharging compressed air into a tire by extending and contracting in directions perpendicular to a rotation axis of the wheel; and a cam member rotatably supported on the wheel and having a center of gravity eccentric to the wheel and an annular cam surface eccentric to the wheel, wherein the cam member rotating relative to the wheel as the wheel rotates, with one end part of the pump following the cam surface, causing the pump to extend and contract to supply air into the tire by a rotary power of the wheel being transmitted to the pump via the cam member, and the air supply system includes a pump on/off mechanism that is activated upon receiving a pressure inside the tire, allowing the pump to operate when the pressure inside the tire is at or below a reference lower limit, and stopping the pump when the pressure inside the tire is at or above a reference upper limit that is larger than the reference lower limit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional side view of a wheel equipped with an air supply system of a first embodiment. 
         FIG.  2    is a cross-sectional side view of the air supply system. 
         FIGS.  3  (A) and (B)  are front views of the air supply system. 
         FIG.  4  (A)  is a cross-sectional side view of a first actuator in which a piston is at a first position, and  FIG. (B)  is a cross-sectional side view of the first actuator in which the piston is at a second position. 
         FIG.  5    is a cross-sectional side view of the air supply system in which a cam member and a dummy member are locked. 
         FIG.  6    is a cross-sectional side view of an air supply system of a second embodiment. 
         FIG.  7    is a cross-sectional side view of an air supply system of a third embodiment. 
         FIGS.  8  (A) and (B)  are front views of an air supply system of a fourth embodiment. 
         FIGS.  9  (A) and (B)  are conceptual diagrams of an air supply system in a variation example of the present disclosure. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     Hereinafter an air supply system  100 A according to a first embodiment of the present disclosure will be described with reference to  FIG.  1    to  FIG.  5   . As illustrated in  FIG.  1   , the air supply system  100 A of this embodiment is entirely covered by a case  40 , for example. The case  40  forms a structure in which one end part of a cylindrical wall  42  is closed by a circular base plate  41 , and the other end is closed by a lid (not shown). The base plate  41  is overlapped on an outer face of a disc part  81  of a tire wheel  80  of a wheel  91  of a vehicle  90 , and attachment pieces  43  extending out from the base plate  41  are fixed to the tire wheel  80  with bolts, in a state where the center axis of the case  40  is matched with the rotation axis J 1  of the wheel  91 . 
     While the air supply system  100 A is preferably attached to all the wheels  91  of the vehicle  90 , the system may be attached to only one or more of the wheel(s)  91  of the vehicle  90 . 
     As illustrated in  FIG.  2   , a ring-shaped cam member  21  and a ring-shaped dummy member  22  are coaxially arranged inside the cylindrical wall  42 , each of them being rotatably supported on the cylindrical wall  42  by bearings  50 , for example. 
     The cam member  21  disposed on the side closer to the base plate  41  includes, as illustrated in  FIG.  3   , an outer circumferential surface  21 A being concentric to the cylindrical wall  42  (e.g., concentric to the rotation axis J 1  of the wheel  91 ), and a cam surface  21 B that is an inner circumferential surface of a circle or oval or ellipse being eccentric to the outer circumferential surface  21 A. Consequently, the cam member  21  has a center of gravity G 1  that is eccentric to the outer circumferential surface  21 A of the cam member  21 . 
     The cam member  21  is symmetrical around a fictional centerline of symmetry connecting the center of gravity G 1  and the center axis of the outer circumferential surface  21 A, and formed with holes  21 C for weight reduction of the cam member  21  on both sides of the centerline of symmetry. Further, a lock hole  23  is opened in the outer circumferential surface  21 A on the centerline of symmetry in a thick part of the cam member  21 . 
     The dummy member  22  has the same shape as that of the cam member  21  except for the position of a lock hole  24 . This lock hole  24  is located on the centerline of symmetry in a thin part of the dummy member  22  (see  FIG.  2   ). 
     As illustrated in  FIG.  2   , the cylindrical wall  42  is provided with first and second actuators  31  and  34  for locking the cam member  21  and dummy member  22  so that they can be rotated with the cylindrical wall  42 . The first actuator  31  has a cylinder  32  supporting a piston  33  such as to be movable linearly, and, as illustrated in  FIG.  4   , is configured such that a resilient member  60  (specifically, a compression coil spring, for example) accommodated inside the cylinder  32  biases the piston  33  to be retracted inside the cylinder  32 . The cylinder  32  is fixedly fitted into a through hole  42 A formed in the cylindrical wall  42  so that the piston  33  is abutted on the outer circumferential surface  21 A of the cam member  21 , as illustrated in  FIG.  2   . 
     The interior of the cylinder  32  is connected to the tire  92  by a pipe  63 . A pressure receiving plate  33 P fixed to the proximal end of the piston  33  inside the cylinder  32  receives pressure inside of the tire  92  to push the piston  33  out of the cylinder  32 . Moreover, as illustrated in  FIG.  4 (A) , first and second locking protrusions  33 A and  33 B are provided at two points along the longitudinal direction of the piston  33 , for example. The piston  33  moves between a first position where the protruding amount from the cylinder  32  is smallest as illustrated in  FIG.  4 (A) , and a second position where the protruding amount of the piston  33  from the cylinder  32  is largest as illustrated in  FIG.  4 (B) , in the course of which the piston overcomes the engagement between a locking portion  32 M of the cylinder  32  that is an opening edge of a through hole for the piston  33  to pass through, and the first and second locking protrusions  33 A and  33 B. 
     More specifically, when the piston  33  is located at the first position shown in  FIG.  4 (A)  and the pressure inside the tire  92  builds up and reaches a reference upper limit, the piston  33  moves from the first position to the second position shown in  FIG.  4 (B)  against the engagement force between the first locking protrusion  33 A and the locking portion  32 M, and the resilient force of the resilient member  60 , where the second locking protrusion  33 B and the locking portion  32 M engage each other to retain the piston  33  at the second position. 
     When the piston  33  is located at the second position and the pressure inside the tire  92  lowers and reaches a reference lower limit, the resilient force of the resilient member  60  moves the piston  33  from the second position to the first position against this pressure and the engagement force between the second locking protrusion  33 B and the locking portion  32 M, where the first locking protrusion  33 A and the locking portion  32 M engage each other to retain the piston  33  at the first position. When the piston  33  is placed at the first position, it is separated sideways from the cam member  21 , and when placed at the second position, it is abutted on the outer circumferential surface  21 A of the cam member  21 . When the piston comes to face the lock hole  23 , the piston goes into the lock hole  23  to lock the cam member  21  to the cylindrical wall  42  so that the cam member can rotate therewith. Namely, the first actuator  31  moves in concert with the pressure inside the tire  92  such as to allow the cam member  21  to rotate when the pressure inside the tire  92  is at or below the reference lower limit, and to lock the cam member  21  when the pressure inside the tire  92  is at or above the reference upper limit. 
     The second actuator  34  has the same structure as that of the first actuator  31 . The cylinder  32  of the second actuator  34  is aligned with the cylinder  32  of the first actuator  31  along the axial direction of the cylindrical wall  42 , and fixedly fitted to the cylindrical wall  42 A of the cylindrical wall  42 . The piston  33  of the second actuator  34  is abutted on the outer circumferential surface of the dummy member  22 . The second actuator  34  also moves in concert with the pressure inside the tire  92  to allow the dummy member  22  to rotate when the pressure inside the tire  92  is at or below the reference lower limit, and to lock the dummy member  22  when the pressure inside the tire  92  is at or above the reference upper limit. When the cam member  21  and the dummy member  22  are both locked, the center of gravity G 1  of the cam member  21  and the center of gravity G 2  of the dummy member  22  are placed at symmetrical positions around the rotation axis J 1  of the wheel  91 , as shown in  FIG.  5   . 
     As shown in  FIG.  2   , a telescopic pump  10  is attached to the base plate  41 . The pump  10  has a cylinder  11  and a piston  12  engaged therewith such as to be movable linearly. A pressure receiving plate  12 P is fixed to the proximal end of the piston  12  inside the cylinder  11 , and a resilient member  59  that biases the piston  12  in a direction in which the piston protrudes from the cylinder  11  is accommodated between this pressure receiving plate  12 P and one end face of the cylinder  11 . The cylinder  11  is fixed to the base plate  41  in a state in which its center is perpendicular to the rotation axis J 1  of the wheel  91  and extends in the radial direction of the case  40 , with the distal end of the piston  12  abutted on the cam surface  21 B that is an inner circumferential surface of the cam member  21 . A roller  12 R that rolls on the cam surface  21 B is provided to a distal end part of the piston  12 . These allow the distal end part of the piston  12  to follow the cam surface  21 B and to move back and forth relative to the cylinder  11 , as the cam member  21  rotates relative to the case  40  (see  FIG.  3   ). 
     A first check valve  58 A and a second check valve  58 B are connected to the cylinder  11 . The first check valve  58 A allows the air to be let out of the cylinder  11  and restricts the air from flowing into the cylinder  11 . The second check valve  58 B, conversely, restricts the air from being let out of the cylinder  11 , and allows the air to flow into the cylinder  11 . The first check valve  58 A has an air outlet connected to the tire  92  by a pipe  61 , while the second check valve  58 B has an air inlet that is open so that the outside air can be taken in. These allow the air to be supplied from the pump  10  into the tire  92  as the piston  12  moves back and forth in the cylinder  11 . 
     The structure of the air supply system  100 A according to this embodiment is as has been described above. The “locking mechanism” as set forth in the claims includes, in this embodiment, the first locking protrusion  33 A, the second locking protrusion  33 B, and the locking portion  32 M. The “pump on/off mechanism” as set forth in the claims includes the first actuator  31  and cam member  21  as major parts. 
     Next, the advantageous effects of the air supply system  100 A will be explained. When the pressure inside the tire  92  is at or above the reference upper limit, the cam member  21  and dummy member  22  are locked by the first and second actuators  31  and  34  which have received tire pressure so that the cam member and dummy member rotate with the wheel  91 . This causes the piston  12  of the pump  10  to be retained in a state abutted on one point on the cam surface  21 B of the cam member  21  and to be stopped, so that the pump  10  does not operate during the drive of the vehicle  90 . 
     Even when the pressure inside the tire  92  lowers to a level slightly below the reference upper limit, the lock of the cam member  21  and dummy member  22  by the first and second actuators  31  and  34  is not released, unless the pressure reaches or falls below the reference lower limit. Specifically, unless the pressure inside the tire  92  reaches or falls below the reference lower limit, the resilient force of the resilient members  60  of the first and second actuators  31  and  34  cannot overcome the pressure inside the tire  92  and the engagement force between the second locking protrusion  33 B and the locking portion  32 M to retract the pistons  33  into the cylinders  32 , so that the lock of the cam member  21  and dummy member  22  by the first and second actuators  31  and  34  is not released. This prevents a “hunting phenomenon” or the oscillating motion of the pump  10  frequently and repeatedly stopping and starting in response to slight changes in pressure inside the tire  92  near the reference upper limit. 
     When the pressure inside the tire  92  reaches or falls below the reference lower limit, the resilient force of the resilient members  60  of the first and second actuators  31  and  34  overcomes the pressure inside the tire  92  and the engagement force between the second locking protrusion  33 B and the locking portion  32 M, so that the pistons  33  are retracted into the cylinders  32  and move from the second position to the first position. This releases the lock of the cam member  21  and dummy member  22  by the first and second actuators  31  and  34 , so that the cam member  21  and dummy member  22  become able to rotate relative to the wheel  91 . Even when the vehicle  90  is driven and the wheel  91  is rotated, the cam member  21  and dummy member  22  are kept in a state in which their centers of gravity G 1  and G 2  are positioned below the rotation axis J 1  of the wheel  91 . This allows the piston  12  of the pump  10  that rotates with the wheel  91  to follow the cam surface  21 B of the cam member  21  and to move back and forth relative to the cylinder  11  (i.e., allows the pump  10  to extend and retract) so that the air is supplied to the tire  92 . 
     In this case, too, even when the pressure inside the tire  92  rises slightly and exceeds the reference lower limit, the cam member  21  and dummy member  22  will not be locked by the first and second actuators  31  and  34  unless the pressure reaches or exceeds the reference upper limit. This prevents the hunting phenomenon or the oscillating motion of the pump  10  frequently and repeatedly stopping and starting in response to slight changes in pressure inside the tire  92  near the reference lower limit. 
     When the pressure inside the tire  92  reaches or exceeds the reference upper limit, the pressure inside the tire  92  overcomes the resilient force of the resilient members  60  of the first and second actuators  31  and  34  and the engagement force between the first locking protrusion  33 A and the locking portion  32 M, so that the pistons  33  are pushed out of the cylinders  32  and move to the second position. This causes the first actuator  31  and second actuator  34  to lock the cam member  21  and dummy member  22 , which brings the pump  10  to a halt. In this state, the centers of gravity G 1  and G 2  of the cam member  21  and dummy member  22  are positioned symmetrically around the rotation axis J 1  of the wheel  91 , which gives a good balance to the wheel and suppresses vibration during the rotation of the wheel  91 . 
     As described above, the air supply system  100 A of this embodiment allows the pump  10  to operate in concert with the rotation of the wheel  91  to automatically supply the air to the tire  92 . When the pressure inside the tire  92  reaches or exceeds the reference upper limit, this pressure activates the pump on/off mechanism to stop the pump  10 . Namely, when air supply to the tire  92  is not necessary, the pump  10  is paused even when the wheel  91  is rotating, so that the pump  10  can have higher durability than before. 
     Second Embodiment 
       FIG.  6    shows major parts of an air supply system  100 B according to a second embodiment of the present disclosure. Hereinafter, the configuration of this air supply system  100 B will be described only with respect to the features different from the first embodiment. In this air supply system  100 B, a plurality of poles  25  protrude into a case  40  from equidistant points of a circular outer edge of a base plate  41  of the case  40  (see  FIG.  2   ). A roller  25 R is rotatably supported on each pole  25 , these rollers  25 R rotatably supporting a cam member  21  and a dummy member  22 . The positions of the cam member  21  and dummy member  22  are inverted from those of the first embodiment, i.e., the dummy member  22  is positioned closer to the base plate  41  than the cam member  21 . 
     The air supply system  100 B of this embodiment does not include the first and second actuators  31  and  34  described in the first embodiment. When the pressure inside the tire  92  reaches or exceeds the reference upper limit, a pump  10  locks the cam member  21  so that the cam member rotates with the pump  10 . 
     Specifically, the pump  10  has a similar structure as that of the first embodiment, and is connected to the tire  92  via the first check valve  58 A (see  FIG.  2   ). The higher the pressure inside the tire  92 , the larger the resistance of the piston  12  being pressed into the cylinder  11 . Using this, the pump is designed such that, when the pressure inside the tire  92  reaches or exceeds the reference upper limit, the piston  12  cannot be pressed into the cylinder  11  by the own weight of the cam member  21  when the piston  12  is most protruded from the cylinder  11 . 
     The lock of the cam member  21  by the pump  10  cannot be released in a case where the pressure inside the tire  92  lowers only slightly below the reference upper limit due to the fluid resistance when the air is supplied from the cylinder  11  to the tire  92 , the resistance when opening the first check valve  58 A, etc. Accordingly, the hunting phenomenon is prevented. The lock of the cam member  21  by the pump  10  is released only when the pressure inside the tire  92  has lowered to or below the reference lower limit. 
     Abutment parts (not shown) are provided between the cam member  21  and the dummy member  22  that abut each other to cause the dummy member  22  to rotate with the cam member  21  when the center of gravity G 1  of the cam member  21  and the center of gravity G 2  of the dummy member  22  come to symmetrical positions around the rotation axis J 1  of the wheel  91  (see  FIG.  5   ). This gives a good balance to the wheel and prevents vibration when the cam member  21  rotates with the wheel  91 . 
     The structure of the air supply system  100 B according to this embodiment is as has been described above. The air supply system  100 B of this embodiment uses its own pump  10  that supplies the air to the tire  92  to stop the pump  10  itself by stopping the cam member  21  relative to the wheel  91  when the pressure inside the tire  92  reaches or exceeds the reference upper limit. The air supply system  100 B of this embodiment thus makes efficient use of the pump  10 . 
     Third Embodiment 
     The air supply system  100 C of this embodiment is illustrated in  FIG.  7   , and includes a balancer device  26  on the back side of a base plate  41 , instead of the dummy member  22  of the air supply system  100 B of the second embodiment. Specifically, only a cam member  21  is rotatably supported on the front side of the base plate  41 , and no dummy member  22  is provided. The balancer device  26  on the back side of the base plate  41  has a structure in which a block  27  is fixed to the tip of a piston  33  of an actuator  34 W having the same structure as that of the second actuator  34  described in the first embodiment. A cylinder  32  of the actuator  34 W is disposed parallel to a cylinder  11  (see  FIG.  7   ) of a pump  10  on the front side of the base plate  41 . The piston  33  of the actuator  34 W protrudes from the cylinder  32  in the opposite direction to the direction in which a piston  12  of the pump  10  protrudes from the cylinder  11 . 
     The cylinder  32  is fixed to the base plate  41 . When the pressure inside a tire  92  is at or below the reference lower limit, the piston  33  is retracted into the cylinder  32  so that the block  27  is positioned near the center of the base plate  41 . In this state, the center of gravity of the entire balancer device  26  is positioned on or near the rotation axis J 1  of the wheel  91 . When the pressure inside the tire  92  reaches or exceeds the reference upper limit, the piston  33  is pushed out of the cylinder  32  so that the block  27  is positioned away from the center of the base plate  41 . In this state, the center of gravity of the entire balancer device  26  is placed symmetrically to the center of gravity G 1  of the cam member  21  with respect to the rotation axis J 1  of the wheel  91 . 
     Fourth Embodiment 
     The air supply system  100 D of this embodiment is illustrated in  FIG.  8   . The mechanism for locking the dummy member  22  and cam member  21  in the air supply system  100 B of the second embodiment is omitted. The air supply system has a structure in which the entire pump  10  is moved relative to the base plate  41  so that the piston  12  does not follow the cam surface  21 B of the cam member  21  to stop the pump  10 . 
     Specifically, a pair of actuators  31 W having the same structure as that of the first actuator  31  described in the first embodiment are provided one each on both sides of the pump  10 , and cylinders  32  of this pair of actuators  31 W are fixed to the base plate  41 . The pistons  33  of the pair of actuators  31 W protrude in the opposite direction to the direction in which the piston  12  of the pump  10  protrudes. A first band plate  28 A extends between the distal ends of both pistons  33 . The cylinder  11  of the pump  10  is fixed to this first band plate  28 A. A second band plate  28 B links the proximal ends of the cylinders  32  of the pair of actuators  31 W. The piston  12  of the pump  10  is slidably supported in a through hole formed in this second band plate  28 B. 
     When the pressure inside the tire  92  is at or below the reference lower limit, the pistons  33  are retracted into the cylinders  32  so that the distal end of the piston  12  of the pump  10  abuts on the cam surface  21 B of the cam member  21 , allowing the piston  12  to follow the cam surface  21 B and to move back and forth relative to the cylinder  11  as the cam member  21  rotates relative to the wheel  91  (see  FIG.  8 (A) ). When the pressure inside the tire  92  reaches or exceeds the reference upper limit, the pistons  33  are pushed out of the cylinders  32 , moving the pump  10  so that the distal end of the piston  12  is moved away from the cam surface  21 B (see  FIG.  8 (B) ), which stops the pump  10 , as the piston  12  stops following the cam surface  21 B. 
     Other Embodiments 
     (1) In the first to fourth embodiments described above, the cam member  21  has a ring shape, its inner circumferential surface serving as the cam surface  21 B. Alternatively, for example as illustrated in the conceptual diagrams of an air supply system  100 E in  FIG.  9   , the cam member  21 X may have a cam surface  21 B on its outer circumferential surface. Specifically, this air supply system  100 E includes a disc-shaped rotary plate  21 Y (not entirely shown) that is rotatably supported on the base plate  41 . A columnar cam member  21 X being eccentric to the rotation axis J 1  of the wheel  91  protrudes from a center part of this rotary plate  21 Y, the outer circumferential surface of this cam member forming a cam surface  21 B. The piston  12  of the pump  10  fixed to the base plate  41  abuts on the cam surface  21 B to allow the pump  10  to operate with the rotation of the rotary plate  21 Y relative to the wheel  91 .  
     (2) In the first to fourth embodiments described above, a roller  12 R is provided to the distal end of the piston  12 . Alternatively, the roller  12 R may be omitted, and the distal end part of the piston  12  may make slidable contact with the cam surface  21 B. 
     While specific examples of techniques included in the claims are disclosed in the specification and drawings, the techniques set forth in the claims are not limited to these specific examples but rather include various modifications and alterations of the specific examples, as well as partial extracts from the specific examples. 
     DESCRIPTION OF THE REFERENCE NUMERAL 
     
       
         
           
               
               
            
               
                 
                   10 
                 
                 Pump 
               
               
                 
                   11 
                 
                 Cylinder 
               
               
                 
                   12 
                 
                 Piston 
               
               
                   12 P 
                 Pressure receiving plate 
               
               
                   12 R 
                 Roller 
               
               
                 
                   20 
                 
                 JP-xxxx-A 
               
               
                   21 ,  21 X 
                 Cam member 
               
               
                   21 B 
                 Cam surface 
               
               
                 
                   22 
                 
                 Dummy member 
               
               
                 
                   27 
                 
                 Block 
               
               
                   31 ,  31 W,  34 ,  34 W 
                 Actuator 
               
               
                   32 M 
                 Locking portion (locking mechanism) 
               
               
                   33 A 
                 First locking protrusion (locking mechanism) 
               
               
                   33 B 
                 Second locking protrusion (locking mechanism) 
               
               
                 
                   91 
                 
                 Wheel 
               
               
                 
                   92 
                 
                 Tire 
               
               
                   100 A to  100 E 
                 Air supply system 
               
               
                 G 1 , G 2 G 
                 Center of gravity 
               
               
                 J 1 
 
                 Rotation axis