Piston follower device

Claim 2

A piston follower device comprising: a. a body having a control chamber therein; b. a control piston disposed within said control chamber and having a shaft for connecting with a control means; said control piston dividing said control chamber into a power end and a shaft end and having a larger surface exposed to fluid pressure in said power end that is exposed to fluid pressure in said shaft end; said control piston also having therethrough a fluid passageway for communicating at one end with said power end and at the other end with a source of fluid at a different pressure; c. a pilot chamber in fluid communication with said power end; d. a pilot piston disposed within said pilot chamber and dividing said pilot chamber into a pilot pressure end, and a control pressure end that is in fluid communication with said power end of said control chamber; said pilot piston including a regulator surface portion that is positionable adjacent and near said one end of said fluid passageway through said control piston to define a flow restricting means; e. first fluid communication means for connecting said shaft end with a first fluid pressure to effect a pressure Pi therewithin; f. second fluid communication means for connecting said power end with a second fluid pressure tending to effect a control pressure therewithin; g. third fluid communication means for connecting said pilot pressure end with a third fluid pressure to effect a pilot pressure therewithin; h. fourth fluid communication means between said pilot pressure end and said power end having interposed therein a flow restricting device for effecting a dynamic balance on said pistons and for effecting a controlled response to a sudden change of one of the pressures, control pressure and pilot pressure; and i. biasing means disposed to act on said pilot piston and tending to force it to an equilibrium position; whereby when connected with the respective fluid pressures said pilot piston is positioned by forces, including pilot pressure, said biasing means and control pressure, with its regulator surface portion defining said flow restricting means with said one end of said fluid passageway; said flow restricting means being adapted to coact with said second fluid communication means to effect a control pressure in said power end and, consequently, in said control pressure end, and by follower action effect a corresponding position of said control piston.

Claim 3

A piston follower device comprising: a. a body having a control chamber therein; b. a control piston disposed within said control chamber and having a shaft for connecting with a valve means; said control piston dividing said control chamber into a power end and a shaft end and having a larger surface exposed to fluid pressure in said power end than is exposed to fluid pressure in said shaft end; said control piston also having therethrough a fluid passageway for communicating at one end with said power end and at the other end with a source of fluid at a pressure which is less than the fluid pressure on the upstream side of said valve means; c. a pilot chamber in fluid communication with said power end; d. a pilot piston disposed within said pilot chamber and dividing said pilot chamber into a pilot pressure end, and a regulator surface portion that is positionable adjacent and near said one end of said fluid passageway through said control piston to define a flow restricting means; e. first fluid communication means for connecting said shaft end with a first fluid pressure, which is the fluid pressure on the upstream side of said valve means, to effect a pressure Pi therewithin; f. second fluid communication means for connecting said power end with a second fluid pressure tending to effect a control pressure therewithin; g. third fluid communication means for connecting said pilot pressure end with a third fluid pressure to effect a pilot pressure therewithin; and h. biasing means disposed to act on said pilot piston and tending to force it to an equilibrium position; whereby when connected with the respective fluid pressures said pilot piston is positioned by forces, including pilot pressure, said biasing means and control pressure, with its regulator surface portion defining said flow restricting means with said one end of said fluid passageway; said flow restricting means being adapted to coact with said second fluid communication means to effect a control pressure in said power end and, consequently, in said control pressure end, and by follower action effect a corresponding position of said control piston.

Claim 4

A piston follower device comprising: a. a body having a control chamber therein; b. a control piston disposed within said control chamber and having a shaft for connecting with a valve means; said control piston dividing said control chamber into a power end and a shaft end and having a larger surface exposed to fluid pressure in said power end than is exposed to fluid pressure in said shaft end; said control piston also having therethrough a fluid passageway for communicating at one end with said power end and at the other end with a source of fluid at a pressure which is less than the fluid pressure on the upstream side of said valve means; c. a pilot chamber in fluid communication with said power end; d. a pilot piston disposed within said pilot chamber and dividing said pilot chamber into a pilot pressure end, and a regulator surface portion that is positionable adjacent and near said one end of said fluid passageway through said control piston to define a flow restricting means; e. first fluid communication means for connecting said shaft end with a first fluid pressure, which is the fluid pressure on the upstream side of said valve means, to effect a pressure Pi therewithin; f. second fluid communication means for connecting said power end with a second fluid pressure tending to effect a control pressure therewithin; g. third fluid communication means for connecting said pilot pressure end with a third fluid pressure to effect a pilot pressure therewithin; and h. biasing means disposed to act on said pilot piston and tending to force it to an equilibrium position; whereby when connected with the respective fluid pressures said pilot piston is positioned by forces, including pilot pressure, said biasing means and control pressure, with its regulator surface portion defining said flow restricting means with said one end of said fluid passageway; said flow restricting means being adapted to coact with said second fluid communication means to effect a control pressure in said power end and, consequently, in said control pressure end, and by follower action effect a corresponding position of said control piston.

Claim 5

The piston follower device of claim 2 wherein said biasing means is disposed to act on said pilot piston so as to force it toward said pilot pressure end for increasing the flow of fluid through said fluid passageway for effecting movement of said control piston toward said power end.

Claim 6

The piston follower device of claim 2 wherein said biasing means is disposed to act on said pilot piston so as to force it toward said control pressure end for decreasing the flow of fluid through said fluid passageway for effecting movement of said control piston toward said shaft end.

Claim 7

A piston follower device comprising: a. a body having an inlet passage and an inlet chamber for connection with a high pressure source of fluid, and having an outlet passage and an outlet chamber for connection with a low pressure source of fluid; b. wall structure intermediate said inlet chamber and said outlet chamber and having an aperture communicating therebetween and having a valve seat therearound; c. valve portion disposed adjacent said valve seat, operable to control flow of fluid through said aperture by being moved with respect to said valve seat; d. control chamber in fluid communication with said inlet chamber; e. control piston disposed within said control chamber and connected via a shaft with said valve portion so as to position said valve portion with respect to said valve seat; said control piston dividing said control chamber into a power end, and a shaft end that is in fluid communication with said inlet chamber, and having a larger surface exposed to fluid pressure in said power end than is exposed to fluid pressure in said shaft end; said control piston also having therethrough a fluid passageway that communicates at one end with said outlet chamber; f. a pilot chamber in fluid communication with said power end; g. a pilot piston disposed within said pilot chamber; dividing said pilot chamber into a pilot pressure end and a control pressure end that is in fluid communication with said power end; said pilot piston including a regulator surface portion that is positionable adjacent and near said one end of said fluid passageway through said control piston to define a flow restricting means; h. first fluid flow passageway communicating via a first flow restricting means between a first source of fluid pressure and said pilot pressure end of said pilot chamber for effecting a pilot pressure and generating a first force on said pilot piston for moving it in a first direction; i. second fluid passageway communicating via a second flow restricting means between a second source of fluid pressure and said power end of said control chamber for effecting a control pressure generating a force on said control piston and generating a second force on said pilot piston for moving it in a second direction opposite said first direction; j. biasing means disposed to act on said pilot piston so as to effect an equilibrium position thereof; whereby said pilot piston Is positioned in accordance with the forces generated by said first and second forces and said biasing means with its regulator surface portion defining said flow restricting means with said one end of said fluid passageway; said flow restricting means co-acting with said second flow restricting means to effect a control pressure in said power end and, consequently, said control pressure end, and by follower action effect a corresponding position of said control piston and said valve portion.

Claim 8

A piston follower device comprising: a. a body having an inlet passage and an inlet chamber for connection with a high pressure source of fluid, and having an outlet passage and an outlet chamber for connection with a low pressure source of fluid; b. wall structure intermediate said inlet chamber and said outlet chamber and having an aperture communicating therebetween and having a valve seat therearound; c. valve portion disposed adjacent said valve seat, operable to control flow of fluid through said aperture by being moved with respect to said valve seat; d. control chamber in fluid communication with said inlet chamber; e. control piston disposed within said control chamber and connected via a shaft with said valve portion so as to position said valve portion with respect to said valve seat; said control piston dividing said control chamber into a power end, and a shaft end that is in fluid communication with said inlet chamber, and having a larger surface exposed to fluid pressure in said power end than is exposed to fluid pressure in said shaft end; said control piston also having therethrough a fluid passageway that communicates at one end with said outlet chamber; f. a pilot chamber in fluid communication with said power end; g. a pilot piston disposed within said pilot chamber; dividing said pilot chamber into a pilot pressure end and a control pressure end that is in fluid communication with said power end; said pilot piston including a regulator surface portion that is positionable adjacent and near said one end of said fluid passageway through said control piston to define a flow restricting means; h. first fluid flow passageway communicating via a first flow restricting means between a first source of fluid pressure and said pilot pressure end of said pilot chamber for effecting a pilot pressure and generating a first force on said pilot piston for moving it in a first direction; i. second fluid passageway communicating via a second flow restricting means between a second source of fluid pressure and said power end of said control chamber for effecting a control pressure generating a force on said control piston and generating a second force on said pilot piston for moving it in a second direction opposite said first direction; j. biasing means disposed to act on said pilot piston so as to effect an equilibrium position thereof; whereby said pilot piston Is positioned in accordance with the forces generated by said first and second forces and said biasing means with its regulator surface portion defining said flow restricting means with said one end of said fluid passageway; said flow restricting means co-acting with said second flow restricting means to effect a control pressure in said power end and, consequently, said control pressure end, and by follower action effect a corresponding position of said control piston and said valve portion.

Claim 9

The piston follower device of claim 5 wherein a third fluid flow passageway is provided communicating via a third flow restricting means between said pilot pressure end and said power end for effecting dynamic positioning of said pilot piston and for effecting a controlled response to a sudden change in one of said pilot pressure and said control pressure.

Claim 10

The piston follower device of claim 5 wherein said first source of fluid pressure and said second source of fluid pressure are both in fluid communication with said inlet chamber; a third fluid flow passageway is provided communicating via a third flow restricting means between said pilot pressure end and said power end; and a fourth fluid flow passageway is provided communicating with another source of fluid at a different pressure and having a flow control means interposed therein for establishing a dynamic balance on said pilot piston and through follower co-action between said regulator surface portion of said pilot piston and said one end of said fluid passageway through said control piston establishing a dynamic balance on said control piston.

Claim 11

The flow control device of claim 5 wherein said control piston has a stem means defining said fluid passageway, said stem means extending the fluid passageway to near said regulator surface portion of said pilot piston in said control pressure end of said pilot chamber.

Claim 12

The piston follower device of claim 5 wherein said pilot piston has a protruding regulator surface portion that extends into said power end of said control cylinder adjacent said one end of said fluid passageway.

Claim 13

The piston follower device of claim 5 wherein said biasing means is disposed to act on said pilot piston so as to force it toward the pilot pressure end so as to tend to position said valve portion in the open position.

Claim 14

The piston follower device of claim 5 wherein said biasing means is disposed to act on said pilot piston so as to force it toward the control pressure end so as to tend to position the valve portion in the closed position.