Patent Publication Number: US-8109745-B2

Title: Floor pump

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to floor pumps and, more particularly, to a floor pump with a stable base. 
     2. Description of the Related Art 
     There are two categories of floor pumps: one floor pump is with a collapsible tripod attached on a base member, and the other floor pump is with an enlarged base member which is adapted for standing on the ground to be stepped on by users. 
     Referring to Taiwan Patent No M278776, a floor pump includes a cylinder  11 , a piston linkage  12 , a channel  13  and a joint  14 . An end of the cylinder  11  is closed and stands on the ground. A tripod  15  is attached to the end of the cylinder  11  and formed by a bent metal. In an operative position of the pump, the tripod  15  is expanded to abut against the ground. The tripod  15  is folded to attach to the cylinder  11  while the pump is in a storage position. The tripod  15  is able to pivot with respect to the cylinder  11  so that the pump is easy for switching between the storage position and the operative position. However, while pumping, the tripod  15  can not provide a stable support, because the cylinder  11  might swing with respect to the tripod  15 . 
     Referring to Taiwan Patent No M260634, another floor pump includes a base member  11 , a cylinder  12 , a hose  13  and a piston linkage  14 . The cylinder  12  and the hose  13  are coupled to the base member  11 . However, an abrasion phenomenon of a connector between the base member  11  and the cylinder  12  is going to occur when the piston linkage  14  is moved in the cylinder  12  up and down over a long period of time. In operation, users step on the base member  11  and operate the piston linkage  14  to pump air into the pump upward and to pump air out of the pump downward. As the piston linkage  14  is moved upward, a piston connected to the piston linkage  14  rubs against the cylinder  12  to provide an upward force to the cylinder  12 , while users standing on the base member  11  provides a downward force to the base member  11 . Therefore, the connector between the base member  11  and the cylinder  12  bears the upward force and the downward force at the same time. The larger the strength users put forth, the larger torque the connector bears. It might cause the cylinder  12  to break easily. In addition, the cylinder  12  is straight, so that the structure strength of the connector is weakened. 
     The present invention is therefore intended to obviate or at least alleviate the problems encountered in the prior art. 
     SUMMARY OF THE INVENTION 
     Accordingly, the object is achieved by providing a floor pump that comprises a base, a cylinder assembly, a linkage assembly and a hose. The cylinder assembly includes a straight inner cylinder and a tapered outer cylinder. A first end of the outer cylinder, which is coupled to the base, has a larger cross-sectional area than a second end of the outer cylinder. 
     Because the first end of the outer cylinder has the larger cross-sectional area than the other portions of the outer cylinder, the pressure of the first end of the outer cylinder has to bear is smaller than the other portions of the outer cylinder. Therefore, the structure of the first end of the outer cylinder is much stronger. 
     Other advantages and features of the present invention will become apparent from the following descriptions referring to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described via detailed illustration of the preferred embodiment referring to the drawings. 
         FIG. 1  is a perspective view of a floor pump according to the preferred embodiment of the present invention. 
         FIG. 2  is an exploded view of the floor pump shown in  FIG. 1 . 
         FIG. 3  is another exploded view of the floor pump similar to  FIG. 2 . 
         FIG. 4  is a cross-section view of the floor pump according to line  4 - 4  shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 through 4 , a floor pump includes a base  10 , a cylinder assembly  20  installed onto the base  10 , a linkage assembly  30  disposed in and reciprocatingly moving with respect to the cylinder assembly  20  for inflating, and a hose  40 . The hose  40  includes a first end  401  coupled to the base  10  and a second end  402  coupled to a thing desired to be inflated. 
     The base  10  includes a coupled member  11  and a pedal member  12 . The coupled member  11  integrally protrudes from the pedal member  12 , and the pedal member  12  expands from two sides of the coupled member  11 . The coupled member  11  includes a first connective portion  111  coupled on the pedal member  12 , a second connective portion  112  surrounded by the first connective portion  111  and a third connective portion  113  adapted to couple to the hose  40 . The first connective portion  111  is in a form of an annular groove, and horizontal positions of the first and second connective portions  111 ,  112  are different. The coupled member  11  has a first side and a second side against the hose. The first and second connective portions  111 ,  112  are defined at the first side, and the third connective portion  113  is defined at the second side of the coupled member  11 . A receptacle  1121  is formed on the second connective portion  112 . A direction of the receptacle  1121  is the same as that of the cylinder assembly  20 . Two engaged holes  114  are longitudinally defined at the coupled member  11  and communicates the first and second connective portions  111 ,  112  with each other. 
     The cylinder assembly  20  includes a straight inner cylinder  21  having a first end  211  and a second end  212  and an outer cylinder  22  having a first end  221  and a second end  222 . The inner cylinder  21  is disposed in the outer cylinder  22 . In this embodiment, the inner and outer cylinders  21 ,  22  are made of aluminum. A diameter of the first end  211  of the inner cylinder  21  is equal to the second end  212  of the inner cylinder  21 . A valve element  213 , which is engaged with the first end  211  of the inner cylinder  21  in a screw manner and disposed in the receptacle  1121 , has two fixed holes  2131 , which are formed on the bottom thereof and correspond to the engaged holes  114 . The first end  211  of the inner cylinder  21  is inserted in the second connective portion  112 . Two fasteners  115  are adapted to insert through the engaged holes  114  to engage with the fixed holes  2131  as to attach the inner cylinder  21  to the base  10 . 
     A cap element  214 , which is mounted on the second end  222  of the outer cylinder  22  and coupled to the second end  212  of the inner cylinder  21  in a screw manner, includes a through-hole  2141  piercing therethrough longitudinally and two hook portions  2142  extending from two sides thereof. The hook portions  2142  are opposite to each other and used for clamping the hose  40  in position selectively. 
     The outer cylinder  22  is with a constant wall thickness, and a cross-sectional area of the first end  221  of the outer cylinder  22  is smaller than that of the second end  222  of the outer cylinder  22 . The first end  221  of the outer cylinder  22  is inserted in the first connective portion  111 , and the outer cylinder  22  is coupled to the base  10  inseparatably. The second end  222  of the outer cylinder  22  is positioned out of the second end  212  of the inner cylinder  21 . 
     The linkage assembly  30  includes a linkage  31  that has a first end  311  and a second end  312 , a handle  32  installed on the second end  312  and a piston  33  coupled to the first end  311 . The linkage  31  is inserted through the inner cylinder  21  to the through-hole  2141  of the cap element  214 , and the piston  33  is driven to reciprocatingly move in the inner cylinder  21  by operation of the handle  32 . The handle  32  is exposed from the cap element  214 . 
     The hose  40  has a first end  401 , which is coupled to the third connective portion  113  of the base  10  and communicates with the cylinder assembly  20 , and a second end  402 . A joint  41  is attached to the second end  402  of the hose  40  and adapted for connecting to the thing desired to be inflated. During inflating, the handle  32  of the linkage assembly  30  is held to drive the linkage  31  to reciprocatingly move with respect of the inner cylinder  21 . An amount of air is inflated into the pump between the piston  33  of the linkage assembly  30  and the inner cylinder  21 . Then, air is inflated into the hose  40 , the joint  41  and finally the thing desired to be inflated. 
     In addition, a pressure gauge (not shown) can be installed on the second end  222  of the outer cylinder  22 . The first end  401  of the hose  40  communicates with the pressure gauge. Therefore, the first end  401  of the hose  40  communicates with the second end  222  of the outer cylinder  22 . 
     The outer cylinder  22  tapers off to the second end  222  from the first end  221 , so that the outer cylinder  22  is shaped as an awl. The cross-sectional area of the first end  221  of the outer cylinder  22  is larger than that of the second end  222  of the outer cylinder  22 . Therefore, the outer cylinder  22  can be stably disposed at the base  10 . An area of the pedal member  12  is much larger than that of the coupled member  11  so that the floor pump can stably stand on the ground. 
     In addition, the cylinder assembly  20  consists of the aluminum inner and outer cylinders  21 ,  22  so that it can save more material cost and so that weight of the pump can also be reduced more than a conventional floor pump which includes one-piece cylinder. 
     The following discussion shows that the larger area of the base  10  of the floor pump in contact with the ground, the larger force the cylinder assembly  20  is capable for bearing. 
     Formula (1) P=F/A represents that relationship of Pressure, Force and Area. In the present invention, the first end  221  of the outer cylinder  22  is coupled to the base  10 , and the pedal member  12  is adapted for being stepped on by users so that the base  10  bears a downward force. Because the first end  221  of the outer cylinder  22  has the larger cross-sectional area than the other portions of the outer cylinder  22 , the force that the first end  221  of the outer cylinder  22  has to bear is smaller than the other portions of the outer cylinder  22 . Therefore, the structure of the first end  221  of the outer cylinder  22  is much stronger. 
     Formula (2) (bending stress)=(bending moment)*(article radius)/(area moment of inertia) represents that in the present invention and because the first end  221  of the outer cylinder  22  has the larger radius of cross-sectional area than the other portions of the outer cylinder  22 , the bending stress that the first end  221  of the outer cylinder  22  can bear is larger than the other portions of the outer cylinder  22 . Therefore, the structure of the first end  221  of the outer cylinder  22  is much stronger and the floor pump will not break easily during long periods of use. 
     While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.