Patent ID: 6921252

Claim:
A hydraulic pump for injecting a predetermined amount of a fluid product into a line carrying fluid that is subject to cyclic pressure, comprising: a chamber having a rigid inner wall adapted to be fluidly coupled to said line; a flexible bladder positioned within said chamber forming a cavity between said bladder and said inner wall of said chamber; said chamber having a first opening and a second opening, both said first opening and said second opening being in fluid communication with said cavity, said first opening adapted to be fluidly coupled to said fluid product, said second opening adapted to be fluidly coupled to said line; said flexible bladder being responsive to fluid pressure in said chamber by moving toward said inner wall of said chamber under a relatively high pressure from said fluid from said line and rebounding to a predetermined position away from said inner wall of said chamber when under a relatively low pressure from said fluid from said line; a first one-way check valve in fluid communication between said fluid product and said first opening allowing said fluid product to pass only into said cavity from outside of said chamber; and a second one-way check valve in fluid communication between said second opening and said line allowing said fluid product to pass only from said cavity to said line.