Control device for controlling a pneumatic piston

Claim 2

A control device for a pressure fluid operated actuator, which device comprises a casing providing a cylinder bore, and a differential piston which is mounted in the bore for reciprocating movement between two end positions and which has a larger diameter end portion and a smaller diameter end portion, said cylinder bore having a smaller diameter portion and a larger diameter portion in which the smaller and larger diameter end portions of the differential piston are respectively slidably disposed for said reciprocating movement and which are closed at their ends remote from each other, a chamber being formed within the bore between said larger and smaller diameter end portions of the differential piston, and said casing providing first and second ports which open to said ends of the smaller and larger diameter end portions of the bore, respectively, a by-pass passage having opposite ends thereof opening to the larger diameter portion of the bore for enabling fluid to by-pass the larger diameter end portion of said differential piston to flow into the chamber over a part of the travel of said differential piston between said end positions, a third port opening to the smaller diameter portion of the bore which third port communicates with said first port when said differential piston is in one of said two end positions and communicates with the chamber when said differential piston is in the other of said two end positions, a fourth port opening to the larger diameter portion of the bore which fourth port communicates with said chamber when said differential piston is in said one of its end positions and communicates with said second port when said differential piston is in said other of its end positions, and a fifth port placing said chamber in permanently open communication with the ambient atmosphere.

Claim 3

In combination, a pressure-fluid operated actuator comprising a cylinder and a piston slidably mounted in the cylinder, said cylinder having pipe connections at opposite ends thereof, a device for controlling said actuator, which device comprises a casing providing a cylinder bore, and a differential piston which is mounted in the bore for reciprocating movement between two end positions and which has a larger diameter end portion and a smaller diameter end portion, said cylinder bore having a smaller diameter portion and a larger diameter portion in which the smaller and larger diameter end portions of the differential piston are respectively slidably disposed for said reciprocating movement and which are closed at their ends remote from each other, a chamber being formed within the bore between said larger and smaller diameter end portions of the differential piston, and said casing providing first and second ports which open to said ends of the smaller and larger diameter end portions of the bore, respectively, a by-pass passage having opposite ends thereof opening to the larger diameter portion of the bore for enabling fluid to by-pass the larger diameter end portion of said differential piston to flow into the chamber over a part of the travel of said differential piston between said end positions, a third port which opens to the smaller diameter portion of the bore and which communicates with the first port when the said differential piston is in one of said two end positions, a fourth port which opens to the larger diameter portion of the bore and which communicates with said chamber when said differential piston is in said one of its end positions and with said second port when said differential piston is in said other of its end positions, an exhaust port which is in permanently open communication with said chamber, a first pipe leading from one of said pipe connections of the actuator to said third port, and a second pipe leading from the other said pipe connections of the actuator to said fourth port.

Claim 4

In combination, a pressure-fluid operated actuator comprising a cylinder and a piston slidably mounted in the cylinder, said cylinder having pipe connections at opposite ends thereof, a device for controlling said actuator, which device comprises a casing providing a cylinder bore, and a differential piston which is mounted in the bore for reciprocating movement between two end positions and which has a larger diameter end portion and a smaller diameter end portion, said cylinder bore having a smaller diameter portion and a larger diameter portion in which the smaller and larger diameter end portions of the differential piston are respectively slidably disposed for said reciprocating movement and which are closed at their ends remote from each other, a chamber being formed within the bore between said larger and smaller diameter end portions of the differential piston, and said casing providing first and second ports which open to said ends of the smaller and larger diameter end portions of the bore, respectively, a by-pass passage having opposite ends thereof opening to the larger diameter portion of the bore for enabling fluid to by-pass the larger diameter end portion of said differential piston to flow into the chamber over a part of the travel of said differential piston between said end positions, a third port which opens to the smaller diameter portion of the bore and which communicates with the first port when the said differential piston is in one of said two end positions, a fourth port which opens to the larger diameter portion of the bore and which communicates with said chamber when said differential piston is in said one of its end positions and with said second port when said differential piston is in said other of its end positions, an exhaust port which is in permanently open communication with said chamber, a first pipe leading from one of said pipe connections of the actuator to said third port, and a second pipe leading from the other said pipe connections of the actuator to said fourth port.

Claim 5

In combination, a changeover valve, a control device controlled by the valve, and a pressure-fluid-operated actuator which is controlled by the control device and which comprises a cylinder and a piston slidably mounted in the cylinder, said cylinder having pipe connections at opposite ends thereof; the valve providing a passage communicating with the control device, and an exhaust connection and a supply connection to a source of pressure fluid which connections can selectively be placed in communication with said passage by operation of the valve; said control device comprising a casing providing a cylinder bore, and a differential piston which is mounted in the bore for reciprocating movement between two end positions and which has a larger diameter end portion and a smaller diameter end portion, said cylinder bore having a smaller diameter portion and a larger diameter portion in which the smaller and larger diameter end portions of the differential piston are respectively slidably disposed for said reciprocating movement and which are closed at their ends remote from each other, a chamber being formed within the bore between said larger and smaller diameter end portions of the differential piston, and said casing providing first and second ports which open to said ends of the smaller and larger diameter end portions of the bore, respectively, a by-pass passage having opposite ends thereof opening to the larger diameter portion of the bore for enabling fluid to by-pass the larger diameter end portion of said differential piston to flow into the chamber over a part of the travel of said differential piston between said end positions, said first port being in communication with said source of pressure fluid and said second port communicating with said passage provided by the valve, a third port which opens to the smaller diameter portion of the bore and which communicates with the first port when the said differential piston is in one of said two end positions, a fourth port which opens to the larger diameter portion of the bore and which communicates with said chamber when said differential piston is in said one of its end positions and with said second port when said differential piston is in said other of its end positions, an exhaust port which is in permanently open communication with said chamber, a first pipe leading from one of said pipe connections of the actuator to said third port, and a second pipe leading from the other said pipe connections of the actuator to said fourth port.

Claim 6

In combination, a changeover valve, a control device controlled by the valve, and a pressure-fluid-operated actuator which is controlled by the control device and which comprises a cylinder and a piston slidably mounted in the cylinder, said cylinder having pipe connections at opposite ends thereof; the valve providing a passage communicating with the control device, and an exhaust connection and a supply connection to a source of pressure fluid which connections can selectively be placed in communication with said passage by operation of the valve; said control device comprising a casing providing a cylinder bore, and a differential piston which is mounted in the bore for reciprocating movement between two end positions and which has a larger diameter end portion and a smaller diameter end portion, said cylinder bore having a smaller diameter portion and a larger diameter portion in which the smaller and larger diameter end portions of the differential piston are respectively slidably disposed for said reciprocating movement and which are closed at their ends remote from each other, a chamber being formed within the bore between said larger and smaller diameter end portions of the differential piston, and said casing providing first and second ports which open to said ends of the smaller and larger diameter end portions of the bore, respectively, a by-pass passage having opposite ends thereof opening to the larger diameter portion of the bore for enabling fluid to by-pass the larger diameter end portion of said differential piston to flow into the chamber over a part of the travel of said differential piston between said end positions, said first port being in communication with said source of pressure fluid and said second port communicating with said passage provided by the valve, a third port which opens to the smaller diameter portion of the bore and which communicates with the first port when the said differential piston is in one of said two end positions, a fourth port which opens to the larger diameter portion of the bore and which communicates with said chamber when said differential piston is in said one of its end positions and with said second port when said differential piston is in said other of its end positions, an exhaust port which is in permanently open communication with said chamber, a first pipe leading from one of said pipe connections of the actuator to said third port, and a second pipe leading from the other said pipe connections of the actuator to said fourth port.

Claim 7

A control device for a pressure fluid operated actuator, as claimed in claim 1, in which said chamber is defined by the inner surface of said casing and by a reduced diameter portion of said piston located between said larger and smaller diameteR end portions of said piston.

Claim 8

A control device for a pressure fluid operated actuator, as claimed in claim 1, including means connecting said first port continuously to a source of fluid under pressure, and means selectively operable to connect said second port to said source or to atmosphere.