Pump assembly for an atomizing piston pump

A pump assembly for an atomizing piston pump comprising a housing, means within said housing defining a first cylinder, a first piston having a liquid flow passage therethrough and slidably positioned in said first cylinder to vary the volume thereof, first valve means for opening and closing and liquid flow passage, first biasing means urging said first valve means to a position closing said liquid flow passage, means fixed relative to said first cylinder for opening said first valve means, said first valve means including means positioned to contact said fixed means after a predetermined amount of movement greater than zero of said first piston relative to said housing to open said first valve means against the urging of said first biasing means only after the said first piston and said first valve means have moved relative to said housing by the predetermined amount, means defining a variable volume liquid storage chamber in communication with said first cylinder on one side of said first piston, means for varying the volume of said liquid storage chamber so that the volume enclosed by said liquid storage chamber and said first cylinder on said one said of said first piston remains substantially constant during said predetermined amount of movement of said first piston, second biasing means urging said varying means into a position corresponding to the minimum volume of said liquid storage chamber, means defining a liquid inlet to said liquid storage chamber, second valve means for opening and closing said liquid inlet, and actuation means for moving said first piston toward said fixed means, whereby during each dispensing stroke, after the predetermined amount of movement of said first piston relative to said housing, said first valve means contacts said fixed means to open said liquid flow passage, allowing liquid within said first cylinder and said variable volume chamber to pass therethrough under urging of said second biasing means and said varying means.

A pump assembly for an atomizing piston pump comprising a housing having defined therein a first cylinder of a first cross-sectional area and a second cylinder communicating with said first cylinder and of a second cross-sectional area less than the first cross-sectional area;

• a first piston slidably positioned in said first cylinder and having a liquid flow path therethrough;
• a second piston slidably positioned in said second cylinder and cooperating with said housing and said first piston to define a variable volume chamber between said first and second pistons;
• first valve means positioned in the liquid flow path and movable in a direction away from the variable volume chamber to open the liquid flow path;
• first biasing means urging said first valve means toward the variable volume chamber to close the liquid flow path;
• spacer means positioned between said pistons and movable independent of said first valve means for maintaining said second piston at least a predetermined minimum distance from said first piston;
• stop means fixed with respect to said housing for contacting said first valve means and moving said first valve means against the urging the said first biasing means only after a predetermined amount of movement greater than zero of said first piston and said first valve means to open the liquid flow path after the predetermined amount of movement;
• second biasing means for urging said second piston toward said first piston to tend to reduce the volume of the variable volume chamber;
• means defining a liquid inlet to the variable volume chamber;
• second valve means responsive to increased pressure in the variable volume chamber for closing the liquid inlet and responsive to reduced pressure in the variable volume chamber for opening the liquid inlet;
• and actuation means for moving said first piston and said first valve means toward said stop means, the arrangement being such that during each dispensing stroke after the predetermined amount of movement of said first piston and said first valve means, said first valve means contacts said stop means to open the liquid flow path, allowing liquid within the variable volume chamber to pass therethrough under the pressure of said second biasing means acting on said second piston.

A pump assembly for an atomizing piston pump comprising a housing having defined therein a first cylinder of a first cross-sectional area and a second cylinder communicating with said first cylinder and of a second cross-sectional area less than the first cross-sectional area;

• a first piston slidably positioned in said first cylinder and having a liquid flow path therethrough;
• a second piston slidably positioned in said second cylinder and cooperating with said housing and said first piston to define a variable volume chamber between said first and second pistons;
• first valve means positioned in the liquid flow path and movable in a direction away from the variable volume chamber to open the liquid flow path;
• first biasing means urging said first valve means toward the variable volume chamber to close the liquid flow path;
• spacer means positioned between said pistons and movable independent of said first valve means for maintaining said second piston at least a predetermined minimum distance from said first piston;
• stop means fixed with respect to said housing for contacting said first valve means and moving said first valve means against the urging of said first biasing means only after a predetermined amount of movement greater than zero of said first piston and said first valve means to open the liquid flow path after the predetermined amount of movement;
• second biasing means for urging said second piston toward said first piston to tend to reduce the volume of the variable volume chamber;
• means defining a liquid inlet to the variable volume chamber;
• second valve means for allowing liquid flow through the liquid inlet into the variable volume chamber;
• and actuation means for moving said first piston and said first valve means toward said stop means, the arrangement being such that during each dispensing stroke after the predetermined amount of movement of said first piston and said first valve means, said first valve means contacts said stop means to open the liquid flow path, allowing liquid within the variable volume chamber to pass therethrough under the pressure of said second biasing means acting on said second piston.