Positive displacement pump having a ratchet drive guide for dispersing cyclic compression stresses over the circumference of an internal flexible member

A positive displacement pump apparatus, comprising:

• a hollow member for delivering a subject liquid by a cycle of contraction and restoration of its volume;
• a casing containing said hollow member;
• said hollow member comprising a first end with an inlet passage for receiving the subject liquid and an opposing second end with an outlet passage for delivering the subject liquid;
• said second end comprising a plate which is axially moveable relative to a longitudinal axis in the casing during the cycle of contraction and restoration;
• said outlet passage extending through a lengthwise-flexible bellows that is coupled to said plate;
• and
• a pressurizing means for supplying and evacuating a hydraulic liquid between said casing and said hollow member, said supplying of hydraulic fluid causing said contraction of said hollow member, and said evacuating of said hydraulic fluid causing said restoration of said hollow member.

A positive displacement pump apparatus, comprising:

• a hollow member for delivering a subject liquid by a cycle of contraction and restoration of its volume;
• a casing containing said hollow member;
• a pressurizing means for supplying and evacuating a hydraulic liquid between said casing and said hollow member, said supplying of hydraulic fluid causing said contraction of said hollow member, and said evacuating of said hydraulic fluid causing said restoration of said hollow member;
• a deformation-inducing means for contacting and deforming outer circumferential portions of said hollow member during said restoration to determine an initial contraction position of said hollow member;
• and
• drive means for varying the circumferential position of said deformation-inducing means relative to said hollow member to vary the initial contraction position of said hollow member;
• said deformation-inducing means including (a) a frame-shaped member rotatably surrounding said hollow member to regulate a direction of deformation of said hollow member, and (b) pressing portions formed on said frame-shaped member to contact opposite positions of said hollow member during restoration of said hollow member.