Abstract: The microvalve device includes a pilot microvalve and a pilot operated spool valve. The pilot microvalve includes a pilot input orifice; a pilot output orifice, at least one of the pilot input orifice and the pilot output orifice having a cross-section flow area that changes as the pilot microvalve is actuated; and a passageway providing fluid communication between the pilot input orifice and the pilot output orifice. The pilot operated spool valve includes a spool having a surface in fluid communication with the passageway; a spool input port; and a spool output port, at least one of the spool input port and the spool output port having a cross-section flow area that changes as the spool is actuated. The spool valve is operable by the pilot microvalve such that a ratio of the cross-sectional flow area of the spool input port to the spool output port will substantially equal to a ratio of the cross-sectional flow area of the pilot input orifice to the pilot output orifice.

Abstract: A spool valve assembly includes a spool that is moveable by differential pressure across the spool.

Abstract: A method to prevent movable structures within a MEMS device, and more specifically, in recesses having one or more dimension in the micrometer range or smaller (i.e., smaller than about 10 microns) from being inadvertently bonded to non-moving structures during a bonding process. The method includes surface preparation of silicon both structurally and chemically to aid in preventing moving structures from bonding to adjacent surfaces during bonding, including during high force, high temperature fusion bonding.

Abstract: A non-abrading method to facilitate bonding of semiconductor components, such as silicon wafers, that have micro structural defects in a bonding interface surface. In a preferred method, micro structural defects are removed by forming an oxide layer on the bonding interface surface to a depth below the level of the defect, and then removing the oxide layer to expose a satisfactory surface for bonding, thereby increasing line yield and reducing scrap triggers in fabrication facilities.

Abstract: A microvalve device is disclosed for controlling fluid flow in a fluid circuit. The microvalve device comprises a body having a bore formed therein. A pilot-operated main valve spool supported by the body is movably disposed in the bore for opening and closing ports formed in the body. A pilot microvalve is operable for controlling movement of the pilot-operated main valve. The pilot microvalve may include a movable valve element that controls the cross-sectional area of two variable orifices in series. When the pilot microvalve is at rest, one orifice is closed and the other is open. Upon actuating the pilot microvalve, the closed orifice may begin to open and the open orifice may begin to close. Pressure between the orifices is used as a command pressure, which is utilized to position the pressure control valve to control load pressure. A method of operating a microvalve device is also disclosed.

Abstract: A heat exchanger structure including multiple fluid circuits, through which respective streams of a first fluid pass from a stream inlet to a stream outlet to transfer heat to or from a second medium. The fluid circuits are arranged into at least a first group and a second group, at least the first group consisting essentially of only fluid circuits that perform substantially similarly according to at least one selected performance criterion. A control sensor for at least the first group generates a signal representative of a parameter of the first fluid in the associated group. A valve for at least the first group is in fluid communication with of all the streams of the associated group so as to be able to control the flow of fluid through the streams of the associated group in parallel.

Abstract: A microvalve device for controlling fluid flow includes a body defining a chamber having first and second ends. The first end is in communication with a source of command pressure. The second end in communication with a source of load pressure. A micromachined spool valve is disposed in the chamber between the first and second ends for sliding movement by differential pressure across the spool between a first position in which allows fluid flow between the source of load pressure and a source of supply pressure and a second position which allows fluid flow between the source of load pressure and a pressure vent. The spool valve has a closed position intermediate the first position and the second position which restricts fluid flow between the source of load pressure and both the source of supply pressure and the pressure vent. The spool valve is moveably connected to the body.

Abstract: A device has been disclosed that may include a spool valve including a body having a first connector and a second connector and a spool movable relative to the body for controlling flow between the first connector and the second connector. The reversible flow control assembly further may include a pilot valve device developing a single pressure command in the form of a fluid at a command pressure. The spool valve may be responsive to the single pressure command developed in said pilot valve device to control flow between the first connector and the second connector without regard to the direction of flow. The majority of axial forces acting on the spool to position the spool relative to the body when fluid is flowing through the valve may be fluid forces.

Abstract: A MEMS device is disclosed having a single microvalve actuator for controlling multiple microvalves. Exemplary embodiments include a MEMS device including two microvalves formed on a beam positioned by an actuator, the two microvalves controlling separate flow paths between two separate pairs of ports; a device with a two-way pilot operated microvalve and a four-way pilot microvalve for controlling the two-way pilot operated microvalve; a device with two three-way microvalves actuated by a common microvalve actuator; and a two-way microvalve with a moveable microvalve element and a feedback port formed in the moveable element operable to regulate the pressure on an end of the moveable element relative to the movement of the moveable element between the first position and the second position. Also disclosed is a MEMS device including a beam with a plurality of apertures formed therein, resulting in a mass reduction of at least 10 percent.

Abstract: A microvalve device includes a body, a valve element supported for movement relative to the body, and an actuator operatively coupled to the valve element for moving the valve element in a normal range of travel. A travel limiting structure operatively cooperates with at least one of the valve element and the actuator to effectively limit the magnitude of movement of the valve element or the actuator outside the normal range of travel to prevent failure of the body, the valve element, or the actuator due to exceeding failure stress limits. A method of forming a microvalve with such a travel limiting structure is also disclosed.

Abstract: A method for forming a micromachined device is disclosed that includes providing a first silicon layer and a second silicon layer. A coating is provided on a first portion of the first layer. The first layer and the second layer are bonded to each other to form a micromachined device, the coating being effective to prevent the coated first portion of the first layer from bonding to the second layer.

Abstract: A microvalve device for controlling the supply of pressurized fluid to a load in a fluid circuit, and having multiple internal fluid conduits for providing pressure feedback.

Abstract: The microvalve device includes a pilot microvalve and a pilot operated spool valve. The pilot microvalve includes a pilot input orifice; a pilot output orifice, at least one of the pilot input orifice and the pilot output orifice having a cross-section flow area that changes as the pilot microvalve is actuated; and a passageway providing fluid communication between the pilot input orifice and the pilot output orifice. The pilot operated spool valve includes a spool having a surface in fluid communication with the passageway; a spool input port; and a spool output port, at least one of the spool input port and the spool output port having a cross-section flow area that changes as the spool is actuated. The spool valve is operable by the pilot microvalve such that a ratio of the cross-sectional flow area of the spool input port to the spool output port will substantially equal to a ratio of the cross-sectional flow area of the pilot input orifice to the pilot output orifice.

Abstract: A device is disclosed for controlling a variable displacement compressor. The device comprises a microvalve operated control valve. A microvalve device for controlling fluid flow and a micro spool valve for use as a microvalve are also disclosed.