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.