Implantable therapeutic substance delivery device having a piston pump with an anti-cavitation valve

An implantable therapeutic substance delivery device with an anti-cavitation valve, comprising:

• a housing;
• a therapeutic substance reservoir coupled to the housing, the therapeutic substance reservoir having a reservoir outlet;
• a power source carried in the housing;
• electronics carried in the housing and coupled to the power source;
• means for pumping coupled to the electronics and coupled to the reservoir outlet, the means for pumping configured to pump a therapeutic substance from the therapeutic substance reservoir through an infusion outlet at a programmed rate;
• and,
• means for inlet valving configured to control the flow of therapeutic substance from the reservoir outlet into a pumping chamber.
• means for anti-cavitation valving configured to substantially prevent retrograde flow of therapeutic substance from the inlet chamber back toward the reservoir outlet.

A therapeutic substance delivery piston pump having an anti-cavitation valve, comprising:

• a pump cylinder having an inlet enclosure with a therapeutic substance inlet coupled to a reservoir outlet and an outlet enclosure with an infusion outlet;
• a pump piston moveable within the pump cylinder, the pump piston having a piston fluid path, a piston inlet end and a piston outlet end, the pump piston forming an inlet chamber between the pump piston and the inlet enclosure and a pumping chamber between the pump piston and the outlet enclosure;
• at least one permanent magnet carried on the pump piston;
• at least two coils formed around the pump cylinder, the coils positioned in operating relation to the permanent magnet;
• an inlet valve carried on the pump piston in operating relation to the piston fluid path configured to control the flow of the therapeutic substance into the inlet chamber;
• and,
• an anti-cavitation valve in fluid communication with the reservoir outlet and the inlet chamber, the anti-cavitation substantially preventing retrograde flow of therapeutic substance from the inlet chamber back toward the reservoir outlet.

An implantable therapeutic substance delivery piston pump with an anti-cavitation, comprising:

• a pump cylinder having an inlet enclosure and an outlet enclosure;
• a therapeutic substance inlet coupled to the therapeutic substance reservoir and coupled to the inlet enclosure;
• an infusion outlet coupled to the outlet enclosure;
• means for pumping to pump therapeutic substance from the therapeutic substance reservoir through an infusion outlet at a programmed rate, the means for pumping having a pump piston and a pump chamber;
• means for creating at least one permanent magnet field carried on the pump piston to impart a magnetic potential to the pump piston;
• means for creating at least one electromagnetic field around the pump cylinder to act upon the means for creating a permanent magnetic field to impart movement to the pump piston;
• means for inlet valving to control therapeutic substance flow into the pump chamber;
• and,
• means for anti-cavitation valving configured to substantially prevent retrograde flow of therapeutic substance from the inlet chamber back toward the reservoir outlet.

A method for controlling the flow of therapeutic substance into a piston pump for an implantable therapeutic substance delivery device, comprising:

• retracting a piston when the electromagnetic axial force acts on the piston;
• closing an anti-cavitation valve when pressure in the inlet chamber exceed pressure in the therapeutic substance inlet;
• opening the inlet valve when the inlet chamber pressure exceeds the pumping chamber pressure;
• filling the pump chamber with therapeutic substance flowing from a reservoir through the inlet valve into the pumping chamber;
• actuating the piston by changing the electromagnetic axial force acting on the piston;
• closing the inlet valve when the pumping chamber pressure exceeds the inlet chamber pressure;
• opening the anti-cavitation valve when inlet chamber pressure becomes lower than therapeutic substance inlet pressure;
• and,
• expulsing a stroke volume through an infusion outlet while the pump piston is actuating.

A method for operating an anti-cavitation valve in a piston pump for an implantable therapeutic substance delivery device, comprising:

• closing an anti-cavitation valve when pressure in the inlet chamber exceed pressure in the therapeutic substance inlet;
• preventing retrograde flow of therapeutic substance from the inlet chamber through the therapeutic substance inlet;
• and,
• opening the anti-cavitation valve when inlet chamber pressure becomes lower than therapeutic substance inlet pressure.