A microvalve in multi-layer structure is proposed, where an inlet connector, a return connector and an outlet connector are produced by planar structuring of material layers. The microvalve has a first and a second stage, which is disposed behind the first stage in respect to the flow direction of the fluid. In the first stage the flow direction of the fluid is directed into a cavity formed by two chambers by means of a flexible tongue, which in the position of rest is oriented parallel to the flow direction of the fluid. At least one outlet connector is disposed in the second stage.

Hydrocleaning apparatus for pipelines and the like includes a frame capable of advancing lengthwise of the pipeline, such frame carrying a plurality of liquid jetting modules which, in use, are disposed in an array around the pipeline surface to enable cleaning of the entire surface to be effected. The frame can be opened up to allow the apparatus to be fitted to or removed from a continuous pipeline. The frame arrangement and module mounting system are designed to provide good cleaning efficiency and proper orientation of the various modules in spite of pipeline irregularities including out-of round conditions, uneven coating thicknesses and wrinkles. A pivoting module mount helps to maintain cleaning efficiency in the case where thick coatings are being removed. The frame drive wheels are disposed forwardly of the modules to avoid contamination of the cleaned surfaces by deposits that may build up on the wheels. A shroud system connected to the modules prevents substantial escape of contaminating liquids and debris into the environment.

A piezoceramic valve includes a valve actuator sandwich assembly including a piezoceramic bending element flexibly bonded between two metal sheets. Flexible elastomeric sheets are bonded to outer surfaces of the metal sheets, respectively, to form the sandwich assembly. The valve includes a first supporting member which sealingly engages an outer surface of the first elastomeric sheet and a second supporting member which sealingly engages an outer surface of the second elastomeric sheet to flexibly support the valve actuator sandwich assembly between the two supporting members. The valve actuator is engageable with a valve seat to prevent flow through the valve and is deflectable away from the valve seat to allow flow through the valve. The piezoceramic bending element is isolated in the valve actuator sandwich assembly from the flow stream to prevent diffusion of low molecular weight gases through the porous ceramic and to isolate electrically active elements of the bending element from the flow stream.

Various micro-transducers incorporating piezoelectric materials for converting energy in one form to useful energy in another form are disclosed. In one embodiment, a piezoelectric micro-transducer can be operated either as a micro-heat engine, converting thermal energy into electrical energy, or as a micro-heat pump, consuming electrical energy to transfer thermal energy from a low-temperature heat source to a high-temperature heat sink. In another embodiment, a piezoelectric micro-transducer is used to convert the kinetic energy of an oscillating or vibrating body on which the micro-transducer is placed into useful electrical energy. A piezoelectric micro-transducer also is used to extract work from a pressurized stream of fluid. Also disclosed are a micro-internal combustion engine and a micro-heat engine based on the Rankine cycle in which a single fluid serves as a working fluid and a fuel.