Positive-displacement fluid motor having self-stopping function, and method and control circuit for stopping the motor

A positive-displacement fluid motor having a plurality of fluid chambers, and a rotating member which is rotated continuously by means of flows of a pressurized fluid to and from said fluid chambers, and which can be stopped at a desired one of at least one predetermined angular position comprising:

• a motor-stop fluid passage selectively communicating with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction;
• said rotating member being operable to select, by rotation thereof, the fluid communication of said motor-stop fluid passage with said at least one advancing fluid chamber or said at least one reversing fluid chamber;
• and
• a motor-stop fluid control circuit connected to said motor-stop fluid passage, for permitting the fluid to flow therethrough for supplying and discharging the fluid to and from said at least one advancing fluid chamber and said at least one reversing fluid chamber, so as to rotate said rotating member in a direction toward said desired predetermined angular position and thereby stop said rotating member at said desired angular position.

A positive-displacement fluid motor having a plurality of fluid chambers, and a rotating member which is rotated by means of flows of a pressurized fluid to and from said fluid chambers, and which can be stopped at one of a first and a second predetermined angular position, comprising:

• a motor-stop fluid supply passage and a motor-stop fluid discharge passage selectively communicating with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction;
• said rotating member being operable to select, by rotation thereof, the fluid communication of said motor-stop fluid supply and discharge passages with said at least one advancing fluid chamber and said at least one reversing fluid chamber;
• switching means operable between a first position in which said motor-stop fluid supply passage communicates with a pressure source for pressurizing the fluid, and a second position in wihch said motor-stop fluid discharge passage communicates with a reservoir;
• first fluid supply/discharge means, operable when said switching means is placed in said first position, for supplying the fluid from said pressure source to at least one approaching fluid chamber of said plurality of fluid chambers through said motor-stop fluid supply passage to rotate said rotating member toward said first predetermined position, while permitting the fluid to be discharged from at least one departing fluid chamber of said plurality of fluid chambers, said at least one approaching fluid chamber serving to rotate said rotating member in a direction toward said one of the first and second predetermined angular positions, while said at least one departing fluid chamber serving to rotate said rotating member in a direction away from said one predetermined angular position;
• and
• second fluid supply/discharge mens, operable when said switching means is placed in said second position, for discharging the fluid from said at least one departing fluid chamber to said reservoir through said motor-stop fluid discharge passage while supplying the fluid from said pressure source to said at least one approaching fluid chamber to rotate said rotating member toward said second predetermined position.

A positive-displacement fluid motor having a a plurality of fluid chambers, and a rotating member which is rotated by means of flows of a pressurized fluid to and from said fluid chambers, and which can be stopped at a desired one of at least one predetermined angular position, comprising at least one of:

• a motor-stop fluid supply passage having at one of opposite ends thereof a connection port adapted to be connected to a pressure source for pressuring the fluid, the other of said opposite ends communicating with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor when said desired predetermined angular position is ahead of a current position of said rotating member, said other end of said motor-stop fluid supply passage communicating with at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member from said desired angular position in a direction opposite to said operating direction, when said current position of the rotating member is ahead of said desired angular position, said rotating member being operable to select, by means of rotation thereof, the fluid communication of said motor-stop fluid supply passage with said at least one advancing fluid chamber or said at least one reversing fluid chamber;
• and
• a motor-stop fluid discharge passage having at one of opposite ends thereof a connection port adapted to be connected to a reservoir, the other of said opposite ends communicating with said at least one reversing fluid chamber when said desired angular position is ahead of said current position of said rotating member in said operating direction of the motor, said other end of said motor-stop fluid discharge passage communicating with said at least one advancing fluid chamber when the current position of said rotating member is ahead of said desired angular position.

A fluid control circuit for controlling a positive-displacement fluid motor which has (a) a rotating member, (b) a plurality of fluid chambers, (c) an entrance port and a discharge port, and (d) a motor-stop fluid supply passage which selectively communicates with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction, said motor being normally operated with said rotating member rotated by means of flows of a fluid to and from the motor through said entrance and discharge ports, said rotating member being stopped at a desired one of at least one predetermined angular position by means of a flow of the fluid into the motor through said motor-stop fluid supply passage, said fluid control circuit comprising:

• a first fluid passage for connecting said entrance port and a pressure source for pressurizing the fluid;
• a second fluid passage for connecting said discharge port and a reservoir;
• a third fluid passage for connecting said motor-stop fluid supply passage and said pressure source;
• shutoff means for closing said third fluid passage when the motor is normally operated, and opening said third fluid passage when the motor is commanded to stop;
• restrictor means disposed in each of said first and second fluid passages;
• and
• selector means for effecting fluid communication between said entrance port and said pressure source through said first fluid passage, and between said discharge port and said reservoir through said second fluid passage, without restricting the fluid flows through said first and second fluid passages by said restrictor means, while said motor is normally operated, said selector means being operable to effect restricted fluid communication of said first and second fluid passages with said reservoir through said restrictor means, at least when the motor is stopped.

A fluid control circuit for controlling a positive-displacement fluid motor which has (a) a rotating member, (b) a plurality of fluid chambers, (c) an entrance port and a discharge port, and (d) a motor-stop fluid discharge passage which selectively communicates with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction, said motor being normally operated with said rotating member rotated by means of flows of a fluid to and from the motor through said entrance and discharge ports, said rotating member being stopped at said desired predetermined angular position by means of a flow of the fluid from the motor through said motor-stop fluid discharge passage, said fluid control circuit comprising:

• a first fluid passage for connecting said entrance port and a pressure source for pressurizing the fluid;
• a second fluid passage for connecting said discharge port and a reservoir;
• a third fluid passage for connecting said motor-stop fluid discharge passage and said reservoir;
• shutoff means for closing said third fluid passage when the motor is normally operated, and opening said third fluid passage when the motor is commanded to stop;
• restrictor means disposed in each of said first and second fluid passages;
• and
• selector means for effecting fluid communication between said entrance port and said pressure source through said first fluid passage, and between said discharge port and said reservoir through said second fluid passage, without restricting the fluid flows through said first and second fluid passages by said restrictor means, while said motor is normally operated, said selector means being operable to effect restricted fluid communication of said first and second fluid psssages with said pressure source through said restrictor means, at least when the motor is stopped.

A fluid control circuit for controlling a positive-displacement fluid motor which has (a) a rotating member that can be stopped at a desired one of at least one predetermined angular position, (b) a plurality of fluid chambers, (c) an entrance port and a discharge port, and (d) a motor-stop fluid supply passage which selectively communicates with at least one advancing fluid chamber of said plurality of fluid chambers which serve to rotate said rotating member in an operating direction of the motor against a load torque, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction, said motor being normally operated with said rotating member rotated against said load torque by means of flows of a fluid to and from the motor through said entrance and discharge ports, said rotating member being stopped at said desired predetermined angular position by means of a flow of the fluid into the motor through said motor-stop fluid supply passage, said fluid control circuit comprising:

• a first fluid passage for connecting said entrance port and a pressure source for pressurizing the fluid;
• a second fluid passage for connecting said discharge port and a reservoir;
• a third fluid passage for connecting said motor-stop fluid supply passage and said pressure source;
• shutoff means for closing said third fluid passage when the motor is normally operated, and opening said third fluid passage when the motor is commanded to stop;
• and
• selector means for effecting fluid communication between said entrance port and said pressure source through said first fluid passage, and between said discharge port and said reservoir through said second fluid passage, while said motor is normally operated, said selected means being operable to close said first fluid passage and maintain the fluid communication between said second fluid passage and said reservoir when the motor is stopped.

A fluid control circuit for controlling a positive-displacement fluid motor wherein a rotating member can be stopped at a desired one of at least one predetermined angular position, and which has (a) a plurality of fluid chambers, (b) an entrance port and a discharge port, and (c) a motor-stop fluid discharge passage which selectively communicates with at least one advancing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in an operating direction of the motor against a load torque, or at least one reversing fluid chamber of said plurality of fluid chambers which serves to rotate said rotating member in a direction opposite to said operating direction, said motor being normally operated against a load torque with said rotating member rotated by means of flows of a fluid to and from the motor through said entrance and discharge ports, said rotating member being stopped at said desired predetermined angular position by means of a flow of the fluid from the motor through said motor-stop fluid discharge passage, said fluid control circuit comprising:

• a first fluid passage for connecting said entrance port and a pressure source for pressurizing the fluid;
• a second fluid passage for connecting said discharge port and a reservoir;
• a third fluid passage for connecting said motor-stop fluid discharge passage and said reservoir;
• shutoff means for closing said third fluid passage when the motor is normally operated, and opening said third fluid passage when the motor is commanded to stop;
• and
• selector means for effecting fluid communication between said entrance port and said pressure source through said first fluid passage, and between said discharge port and said reservoir through said second fluid passage, while said motor is normally operated, said selector means being operable to maintain the fluid communication between said first fluid passage and said pressure source and close said second fluid passage when the motor is stopped.

A fluid control circuit for controlling a positive-displacement fluid motor which has (a) a rotating member, (b) a plurality of fluid chambers, (c) an entrance port and a discharge port which selectively communicate with said plurality of fluid chambers, and (d) a motor-stop fluid passage which selectively communicates with at least one fluid advancing fluid chamber of said plurality of fluid chambers which serve to rotate said rotating member in an operating direction of the motor against a load torque, or at least one reversing fluid chamber of said plurality of fluid chambers which serve to rotate said rotating member in a direction opposite to said operating direction, said fluid control circuit comprising:

• a first fluid passage whose one end is adapted to be connected to said entrance port;
• a second fluid passage whose one end is adapted to be connected to said discharge port;
• a third fluid passage whose one end is adapted to be connected to said motor-stop fluid passage;
• first switching means connected to the other ends of said first and second fluid passages, said first switching means being operable between a first position in which said first fluid passage communicates with a pressure source while said second fluid passage communicates with a reservoir, and a second position in which said first fluid passage is closed while said second fluid passage is held in communication with said reservoir;
• and
• second switching means connected to said first fluid passage, and receiving a pressure in said third fluid passage as a pilot pressure, said second switching means being normally closed, and being opened when said pilot pressure exceeds a predetermined limit and thereby connecting said first fluid passage which has been disconnected from said pressure source by said first switching means, to said pressure source,
• said rotating member being rotated in said operating direction against said load torque while said first switching means is placed in said first position, and being stopped at a desired predetermined angular position when said first switching means is operated to said second position.