Fluid pump

Abstract

The present invention inhibits suction of dust and moisture into a drive chamber for driving a piston of a fluid pump while reducing drive load through feeding/discharging of fluid to/from the drive chamber. In the interior of a cylinder, a pressure increasing/decreasing chamber is formed between a valve unit on the cylinder head side and the piston. On the opposite side of the pressure increasing/decreasing chamber, the drive chamber is disposed. There are provided a ventilation path for communicating the drive chamber and the outside space, a fluid path connected to the feeding/discharging space of the valve unit, a merging space where the fluid path is merged with the ventilation path midway, and a fluid filter provided in the merging space.

1 . A fluid pump comprising:
 a cylinder;   a piston mounted inside the cylinder to be moved back and forth, the piston partitioning the inside of the cylinder between a pressure increasing/decreasing chamber on the side of the cylinder head and a drive chamber opposite the pressure increasing/decreasing chamber;   a valve unit having a control space for causing fluid of the pressure increasing/decreasing chamber to act on a pressurizing/depressurizing object and a feeding/discharging space for feeding/discharging fluid between the pressure increasing/decreasing chamber and the outside space, the valve unit being provided in the cylinder head so as to control flow of the fluid to the pressure increasing/decreasing chamber at the time of a reciprocal movement of the piston:   a path block mounted to the cylinder;   a ventilation path communicating the drive chamber and the outside space with each other via the path block;   a fluid path connected to the feeding/discharging space and the path block so as to be merged with the ventilation path in a merging space inside the path block;   a fluid filter mounted in the merging space; and   an opening defined in a bottom wall of the path block for establishing communication between the interior space of the path block and the outside space; and   wherein an upper face of the bottom wall is formed with an inclined posture such that the upper face is positioned lower as it extends toward a position closer to the opening.   
     
     
         2 . The fluid pump according to  claim 1 , wherein the valve unit includes:
 an intake valve disposed in the control space and configured to be opened only when the piston is operated in the sucking direction for sucking air as the fluid from a depressurizing object as the pressurizing/depressurizing object to the pressure increasing/decreasing chamber;   a discharge valve disposed in the feeding/discharging space and configured to be opened only when the piston is operated in the discharging direction for feeding air as the fluid to the pressure increasing/decreasing space; and   a discharging path as the fluid path for feeding air from the discharge valve to the merging space.   
     
     
         3 . The fluid pump according to  claim 1 , wherein the valve unit includes:
 a discharge valve disposed in the control space and configured to be opened only when the piston is operated in the discharging direction for feeding air as the fluid from the pressure increasing/decreasing space to a pressurizing object as the pressurizing/depressurizing object;   an intake valve disposed in the feeding/discharging space and configured to be opened only when the piston is operated in the sucking direction for sucking air as the fluid to the pressure increasing/decreasing chamber; and   an intake path as the fluid path for feeding fluid sucked via the fluid filter to the intake valve.   
     
     
         4 . (canceled) 
     
     
         5 . The fluid pump according to  claim 1 , wherein in an annular area surrounding the opening as its center, there are formed a plurality of vertical walls extending upward from the upper face of the bottom wall,
 the merging space is formed by the region surrounded by the vertical walls, and   the fluid path and the ventilation path are communicated with each other outside the merging space.   
     
     
         6 . The fluid pump according to  claim 1 , wherein a tubular body is provided to project downwards at a position on the side of the lower face of the bottom wall of the path block and surrounding the opening.