Abstract: The invention relates to a flow sensor comprising a substrate with integrated heat source and temperature sensors. Solder bumps are arranged on the heat source and the temperature sensors and the substrate is attached to the outside of a tube using flip chip technology. Preferably, the outside of the tube is structured for being wetted at appropriate positions by the solder. This allows to assemble the sensor easily and accurately.

Abstract: A device for measuring the flow of a fluid has a primary duct and a bypass arranged in series to the primary duct. The bypass has a first section and a second section. A baffle plate with a hole for the passage of the fluid is arranged in the first section. The second section comprises two parallel secondary ducts. In the first section, a turbulent flow dominates, while the flow in the second section is primarily laminar. If the turbulent effects in the bypass are sufficiently strong, the ratio of the flows in the primary duct and the bypass can be substantially independent of the fluid properties and of the flow rate. By using two parallel secondary ducts in the second section, high flow rates and therefore strongly turbulent effects can be achieved without exceeding the measuring range of the sensor.

Abstract: To measure the flow in a liquid, the liquid (1) is led in a duct (2) along a flow sensor (3). The flow sensor (3) is integrated together with a processing and control circuit on a semiconductor substrate. It comprises a heating and, symmetrically thereto, two temperature sensors. The flow is determined from the temperature difference between the temperature sensors and/or from the power dissipation of the heating. For calibrating the sensor, a valve (4) is provided by means of which the duct (2) can be interrupted. This arrangement allows a flow measurement of high accuracy.

Abstract: A device for measuring the flow of a fluid has a primary duct and a bypass arranged in series to the primary duct. The bypass has a first section and a second section. A baffle plate with a hole for the passage of the fluid is arranged in the first section. The second section comprises two parallel secondary ducts. In the first section, a turbulent flow dominates, while the flow in the second section is primarily laminar. If the turbulent effects in the bypass are sufficiently strong, the ratio of the flows in the primary duct and the bypass can be substantially independent of the fluid properties and of the flow rate. By using two parallel secondary ducts in the second section, high flow rates and therefore strongly turbulent effects can be achieved without exceeding the measuring range of the sensor.

Abstract: A sensor is described for measuring the parameters of a fluid, in particular for detecting substances in a gas. It comprises a measuring section (4) on a semiconductor chip (1), which is protected by a housing (3). A partition wall (12) of the housing (3) divides the semiconductor chip (1) into two parts (1a, 1b). The first part (1a) is connected to the outside by means of openings in the housing and carries the measuring section. The second part (1b) is covered by a hardened sealing material (11). The sealing material (11) protects the semiconductor chip (1) from undesired environmental influences. The dividing wall (12) forms a capillary between the chip and the housing, the capillary action of which draws in the sealing material and the end of which stops the sealing material.

Abstract: The A/D-converter with optional analog preprocessing comprises two analog inputs (I1, I2), wherein a converter (1, 2) is connected to each input for generating a first and a second digital value (D1, D2) respectively. These are fed to a table (3) for generating a lookup value (D). A decimation filter (4) processes several such lookup values and generates an output value (O). With this arrangement the table can be kept comparatively small while it is still possible to reach high resolution and precision. The A/D-converter is especially suited for applications where two or more analog signals have to be combined and digitized.

Abstract: For measuring the flow and the thermal conductivity of a fluid, a sensor is used, which has a first temperature detector for measuring a first temperature and a second temperature detector for measuring a second temperature. A heating is arranged between the temperature detectors. Two measured quantities are determined by means of the temperature detectors, a first of which is e.g. a difference between the temperatures and a second one of which is one of the temperatures. By comparing the two measured quantities, the flow and the thermal conductivity of the fluid can be determined.

Abstract: A heating element (4) is arranged between two temperature sensors (5, 6) in order to measure the mass flow of a liquid or a gas. The mass flow is determined from the temperature difference of the temperature sensors (5, 6). The heating element (4) is operated by pulses in order to reduce power consumption of the device. A further reduction of the power consumption is reached by means of a monitoring circuit (12), which switches the actual measuring section (11) on only if the signals from the temperature sensors (5, 6) fulfil a threshold condition.