Electrically operated hydraulic actuator with force feedback position sensing

A hydraulic apparatus comprising:

• a body with a spool bore therein, and having a first work port, a second work port, a supply passage, and a tank passage all of which communicate with the spool bore;
• a control spool accommodated in the spool bore for reciprocal movement therein, the control spool having a first location at which the first work port is coupled to the supply passage and the second work port is coupled to the tank passage, a second location at which the first work port is coupled to the tank passage and the second work port is coupled to the supply passage, and a third location at which the first work port and the second work port are isolated from the supply passage and the tank passage;
• a piston coupled to the control spool and defining a first control chamber and a second control chamber on opposite sides of the piston, the piston having a first end and a second end with a depression there between, the depression having a first tapered section and a second tapered section;
• a first electrohydraulic valve having a first actuator coupled to a valve element which has first state in which the pressurized fluid is proportionally metered to an outlet connected to the first control chamber, a second state in which the first control chamber is coupled to a tank passage, and a third state in which the first control chamber is isolated from both the tank passage and the pressurized fluid;
• a second electrohydraulic valve which has a second actuator coupled to a valve member which has a fourth state in which the second control chamber is coupled to the tank passage, and a fifth state in which the second control chamber is coupled to the outlet of the first electrohydraulic valve;
• and
• a pilot pin which engages the piston and the valve element wherein movement of the pilot pin on the first and second tapered sections exerts a force to the valve element.

A hydraulic apparatus comprising:

• a body with a valve bore therein, and having a first work port, a supply passage, and a tank passage all of which communicate with the valve bore;
• a flow control component movably accommodated in the valve bore to define a first fluid path between the work port and the supply passage and a second fluid path between the work port and the tank passage;
• a piston coupled to the flow control component and defining a first control chamber and a second control chamber on opposite sides of the piston, the piston having a first end and a second end with a depression there between, the depression having a first tapered section and a second tapered section;
• a first electrohydraulic valve having a first actuator coupled to a valve element which has first state in which the pressurized fluid is proportionally metered to an outlet connected to the first control chamber, a second state in which the first control chamber is coupled to a tank passage, and a third state in which the first control chamber is isolated from both the tank passage and the pressurized fluid;
• and
• a second electrohydraulic valve which has a second actuator coupled to a valve member which has a fourth state in which the second control chamber is coupled to the tank passage, and a fifth state in which the second control chamber is coupled to the outlet of the first electrohydraulic valve.