System that maintains the last commanded position of device controlled by a two-stage, four-way electrohydraulic servo valve upon power interruption

Patent metadata

Field	Value
Publication number	US-11242875-B2
Application number	US-202016810068-A
Country	US
Kind code	B2
Filing date	Mar 5, 2020
Priority date	Mar 5, 2020
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

A system uses a two-stage electrohydraulic servo valve that includes an additional control port that commands a fail-fixed valve to lock the position of a device in the last commanded position. The additional port is modulated by an existing land on the EHSV valve element, adding little to no complexity. Major technical benefits of the disclosed system are that it adds little to no cost, complexity, size, or weight the device being controlled. The disclosed configuration allows for the use of a relatively small and simple fail-fixed valve, and the control ports on the controlled device keep “drift” to a minimum, when transitioning between normal operating mode and fail-fixed operating mode.

First claim

What is claimed is:

1. A system, comprising:
a fail-fixed valve body including a first inlet port, a second inlet port, a third inlet port, a first outlet port, and a second outlet port;
a fail-fixed valve element disposed within the fail-fixed valve body and moveable therein between a first position, in which the first inlet port is in fluid communication with the first outlet port and the second inlet port is in fluid communication with the second outlet port, and a second position, in which the first inlet port is not in fluid communication with the first outlet port and the second inlet port is not in fluid communication with the second outlet port; and
a two-stage electrohydraulic servo valve (EHSV) including:
a servo valve body including a supply pressure port, a return pressure port, a head pressure port, a rod pressure port, and a fail-fixed control pressure port, the head pressure port in fluid communication with the first inlet port, the rod pressure port in fluid communication with the second inlet port, the fail-fixed control pressure port in fluid communication with the third inlet port, and
a servo valve element disposed within the servo valve body and moveable therein between a centered control position and a plurality of non-centered control positions, and further moveable to an electrical null bias fail-fixed position,
wherein:
in the centered control position, the supply pressure port and the return pressure port are both fluidly isolated from the head pressure port, the rod pressure port, and the fail-fixed control pressure port,
in the plurality of non-centered control positions, the supply pressure port and the return pressure port are both fluidly isolated from the fail-fixed control pressure port, and either (i) the supply pressure port is in fluid communication with the head pressure port and the return pressure port is in fluid communication with the rod pressure port or (ii) the supply pressure port is in fluid communication with the rod pressure port and the return pressure port is in fluid communication with the head pressure port, and
in the electrical null bias fail-fixed position, the supply pressure port is in fluid communication with the fail-fixed control pressure port and the head pressure port, and the return pressure port is in fluid communication with the rod pressure port, whereby the fail-fixed valve element is moved from the first position to the second position.

2. The system of claim 1 , further comprising:
a bias spring disposed within the fail-fixed valve body and engaging the fail-fixed valve element, the bias spring supplying a bias force to the fail-fixed valve element that urges the fail-fixed valve element toward the first position.

3. The system of claim 1 , wherein the fail-fixed valve element comprises:
a first end portion;
a second end portion; and
an intermediate portion,
wherein:
the first end portion and the second end portion have a first diameter,
the intermediate portion has a second diameter, and
the second diameter is less than the first diameter.

4. The system of claim 1 , further comprising:
a first plurality of dynamic seals mounted on the first end portion of the fail-fixed valve element; and
a second plurality of dynamic seals mounted on the second end portion of the fail-fixed valve element.

5. The system of claim 1 , further comprising:
a first flow restriction formed in the head pressure port; and
a second flow restriction formed in the rod pressure port.

6. The system of claim 1 , wherein the two-stage EHSV further comprises a torque motor, the torque motor coupled to the servo valve body.

7. The system of claim 6 , wherein the torque motor is a dual-channel torque motor.

8. The system of claim 1 , wherein the rod pressure port is in fluid communication with the fail-fixed control pressure port via a flow path.

9. The system of claim 8 , further comprising:
a bleed orifice disposed within the flow path.

10. The system of claim 1 , further comprising:
an actuator housing having an inner surface, an outer surface, a first actuator pressure port, and a second actuator pressure port, the inner surface defining an actuator cavity, the first and second actuator pressure ports spaced apart from each other and extending between the inner and outer surfaces; and
an actuator disposed at least partially in, and movable within, the actuator cavity, the actuator including a piston that divides the actuator cavity into a variable head pressure cavity and a variable rod pressure cavity,
wherein:
the first actuator pressure port is in fluid communication with the variable head pressure cavity and the first outlet port, and
the second actuator pressure port is in fluid communication with the variable rod pressure cavity and the second outlet port.

11. The system of claim 10 , wherein the piston includes:
a first side,
a second side, and
an orifice that extends between the first side and the second side and provides fluid communication between the variable head pressure cavity and the variable rod pressure cavity.

12. A system, comprising:
a fail-fixed valve body including a first inlet port, a second inlet port, a third inlet port, a first outlet port, and a second outlet port;
a fail-fixed valve element disposed within the fail-fixed valve body and moveable therein between a first position, in which the first inlet port is in fluid communication with the first outlet port and the second inlet port is in fluid communication with the second outlet port, and a second position, in which the first inlet port is not in fluid communication with the first outlet port and the second inlet port is not in fluid communication with the second outlet port; and
a two-stage electrohydraulic servo valve (EHSV) including:
a servo valve body including a supply pressure port, a return pressure port, a head pressure port, a rod pressure port, and a fail-fixed control pressure port, the head pressure port in fluid communication with the first inlet port, the rod pressure port in fluid communication with the second inlet port, the fail-fixed control pressure port in fluid communication with the third inlet port and in fluid communication with the rod pressure port via a flow path, the flow path having a bleed orifice disposed therein,
a first flow restriction formed in the head pressure port,
a second flow restriction formed in the rod pressure port,
a servo valve element disposed within the servo valve body and moveable therein between a centered control position and a plurality of non-centered control positions, and further moveable to an electrical null bias fail-fixed position, and a dual-channel torque motor coupled to the servo valve body,
wherein:
in the centered control position, the supply pressure port and the return pressure port are both fluidly isolated from the head pressure port, the rod pressure port, and the fail-fixed control pressure port,
in the plurality of non-centered control positions, the supply pressure port and the return pressure port are both fluidly isolated from the fail-fixed control pressure port, and either (i) the supply pressure port is in fluid communication with the head pressure port and the return pressure port is in fluid communication with the rod pressure port or (ii) the supply pressure port is in fluid communication with the rod pressure port and the return pressure port is in fluid communication with the head pressure port, and
in the electrical null bias fail-fixed position, the supply pressure port is in fluid communication with the fail-fixed control pressure port and the head pressure port, and the return pressure port is in fluid communic

Assignees

• Honeywell Int Inc

Inventors

• Futa Paul W
• Arend Matthew
• Walejewski Charles
• Bondariu Calin

Classifications

• F15B2211/30565

  having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve · CPC title

• F15B20/002 Primary

  Electrical failure · CPC title

• F15B13/0438

  the pilot valves being of the nozzle-flapper type · CPC title

• F15B13/0436 Primary

  the pilot valves being of the steerable jet type · CPC title

• F15B2211/8752

  Emergency operation mode, e.g. fail-safe operation mode · CPC title