Air pump

Abstract

An air pump comprises a cylinder, a piston, a piston rod, and four substantially rigid members. The piston is reciprocably movable within the cylinder and is secured to the piston rod. The first member is pivotably connected at its first end to the cylinder. The second member is pivotably connected at its first end to the piston rod and at its second end to the second end of the first member. The third member is pivotably connected at its first end to the connected second ends of the first and second members. The fourth member is pivotably connected to the cylinder and to the second end of the third member. The third member is arranged to transmit between the handle and the connected second ends of the first and second members a force resulting from a force applied to the handle.

1 . An air pump, comprising:
 a cylinder having a first end and a second end;   a piston reciprocably movable within the cylinder and defining a compression volume within the cylinder between the piston and the first end of the cylinder;   a piston rod substantially rigidly secured to the piston and extending along the cylinder towards the second end of the cylinder;   a substantially rigid first member having a first end and a second end, wherein the first end pivotably connected to the cylinder;   a substantially rigid second member having a first end and a second end, wherein the first end is pivotably connected to the piston rod and the second end is pivotably connected to the second end of the first member;   a substantially rigid third member having a first end and a second end, wherein the first end is pivotably connected to the connected second ends of the first and second members; and   a substantially rigid fourth member having a first end, a second end, and a connection point, wherein the first end is pivotably connected to the cylinder adjacent the second end of the cylinder, and wherein fourth member is pivotably connected to the second end of the third member at the connection point, and   wherein the third member is arranged to transmit, between the fourth member and the connected second ends of the first and second members, a force resulting from a force applied to the fourth member.   
   
   
       2 . The air pump of  claim 1 , wherein the fourth member is a handle, and wherein the connection point is positioned between the first and second ends of the fourth member. 
   
   
       3 . The air pump of  claim 1 , wherein the fourth member is pivotable to a closed position approximately parallel to the cylinder with the first, second and third members being nested together between the fourth member and the cylinder. 
   
   
       4 . The air pump of  claim 1 , wherein rotation axes of the pivotable connections among the cylinder, the piston rod, the first member, the second member, the third member and the fourth member are substantially parallel to one another and are substantially perpendicular to the axis of the cylinder. 
   
   
       5 . The air pump of  claim 3 , wherein the first and second members are arranged substantially parallel to the cylinder when the piston is positioned substantially at the end of a pump stroke. 
   
   
       6 . The air pump of  claim 1 , wherein the fourth member is pivotable from an open position through an arc to a closed position, the arc corresponding to a stroke of the piston within the cylinder, and wherein, at a position between the open position and the closed position of the fourth member, the relative positions of the fourth member and at least one of the other members together define an inversion point, and wherein further rotation of the fourth member beyond the inversion point in a direction toward the closed position does not exert a force on the third member. 
   
   
       7 . The air pump of  claim 6 , wherein the piston is movable to expand the compression volume and exert a force tending to retain the fourth member in the closed position. 
   
   
       8 . The air pump of  claim 6 , wherein the pivot connection between the fourth member and the third member is elongated to allow translation, and wherein the third member is free to translate when the fourth member is in the closed position. 
   
   
       9 . The air pump of  claim 6 , wherein the fourth member and the third member are configured to have a clutch arrangement by which force is transmitted from the fourth member to the third member as the fourth member is rotated from the open position to the inversion point, and wherein the clutch arrangement allows the third member to translate as the fourth member is rotated from the inversion point toward the closed position. 
   
   
       10 . The air pump of  claim 6 , wherein the third and fourth members are fitted with a cam and follower arrangement, and wherein the follower is free to translate over a portion of the stroke between the inversion point and the closed position. 
   
   
       11 . The air pump of  claim 6 , wherein the fourth member comprises a slot or groove shaped to correspond to a length of the arc, the slot or groove having an elongated portion corresponding to the portion of travel between the inversion point and the closed position, and wherein the third member has a pin positioned to travel within the slot or groove. 
   
   
       12 . The air pump of  claim 1 , wherein the cylinder is secured to an air gun, and the air pump is operatively coupled to the air gun for compressing air to fire the air gun. 
   
   
       13 . The air pump of  claim 1 , wherein the first and second members and the handle are arranged substantially parallel to the cylinder when the piston is positioned substantially at the end of a pump stroke. 
   
   
       14 . The air pump of  claim 1 , wherein the first member, the second member, the third member, and the fourth member are arranged so that pressure within the cylinder urges the handle against the cylinder when the piston is positioned substantially at the end of a pump stroke.