Abstract: A thermal type flow meter has a first heating resistor, a second heating resistor for blocking heat transfer from the first heating resistor to a console, a temperature measuring resistor interposed between the two heating resistors, and a controller for calculating a flow rate unrelated to temperatures of fluid from temperatures of the resistors and currents supplied to the heating resistors.

Abstract: An engine that re-circulates its exhaust gas suffers decreased accuracy in estimating an EGR rate real-time especially while the operating state of the engine is in a transitional state, which often results in torque fluctuations and deteriorated exhaust gas. A sensor for directly detecting an EGR flow rate is disposed in an EGR path. An EGR rate and in-cylinder oxygen concentration are calculated from the output value of that sensor. In addition, when this EGR rate calculation method is used, the calculation is properly switched between a steady operation state characterized by a low load and small rotational fluctuations and a transitional operating state including the acceleration and deceleration. This makes it possible to correctly estimate the EGR rate and the in-cylinder oxygen concentration under a wide range of engine operation conditions, and thereby to avoid the fluctuation of torque and the deterioration of exhaust gas.

Abstract: The present invention prevents an EGR sensor installed in an engine's EGR path from being soiled by soiling substances in exhaust. A catalyst is positioned upstream of the EGR sensor to purify the soiling substances in EGR gas. The status of the EGR sensor is properly controlled in accordance with the conditions of the catalyst. This ensures the EGR sensor is less likely to be affected by the soiling substances in the exhaust under any circumstances of the EGR path and allows the EGR sensor to avoid a decrease in the accuracy of EGR gas detection. An alternative configuration may be employed such that the EGR gas recirculates from the downstream side of a catalyst installed in a main exhaust path.

Abstract: In a gas flowmeter in which a rod and a sensor element are formed as a single body, for preventing heat of the sensor element from flowing into a sensor probe through a substrate (rod) so as to suppress considerable power consumption, and for obtaining a necessary response speed with respect to a flow rate of gas to be measured or a change in temperature, the gas column (rod) is made of an insulating material on a center axis of the sensing probe and is formed with a conductor pattern on its surface, and the sensing probe connects the sensor element disposed in a pipe through which the gas to be measured flows and a harness terminal through the conductor on the surface of the rod, so as to measure a gas flow rate by using the sensing prove.

Abstract: There is provided a thermal type flow meter capable of accurately detecting a flow rate even when a fluid temperature varies rapidly or when the fluid temperature is high. A probe includes: a first main heating resistor; a second main heating resistor set at a temperature different from that of the first main heating resistor; and a sub-heating resistor for heating lead wires of the two main heating resistors. A CPU of a sensor control circuit finds a fluid temperature by using the two main heating resistors, and finds a fluid flow rate by using at least one of the two main heating resistors.

Abstract: A high-accuracy EGR sensor is provided. A recirculation system is provided which controls the flow rate of EGR by use of the sensor. A thermal gas flowmeter includes a heating resistor disposed in a flow of gas to be measured for detecting the flow rate of the gas, and an external circuit electrically connected to the heating resistor for outputting a signal according to the flow rate of the gas to be measured using the heating resistor. The heating resistor is controlled to be heated at a temperature equal to or higher than a vapor film forming temperature for forming a vapor film.

Abstract: A conventional technique performs valve close control of an EGR valve after an EGR-gas back flow is detected. Therefore, the conventional technique has a subject that, if an EGR-gas flow direction changes from forward flow to back flow, a back flow condition will last not only for a response delay time of a detector but also for the judgment time by calculation processing and the actuation time of the EGR control valve.

Abstract: A thermal type gas flowmeter comprising a sensor element which, in turn, comprises at least one first heating resistor, two or more resistors in fluid and a second heating resistor which is disposed between the first heating resistor and a housing supporting the sensor element. The first and second heating resistors are electrically independent from each other. A temperature sensing unit is provided between the first and second heating resistors. A temperature of the first or second heating resistor is controlled by a temperature sensed by the temperature sensing unit.

Abstract: Disclosed herein is a fluid flow rate measurement apparatus which prevents accumulation of pollutional substances in a sub-passage to enable high-accuracy fluid flow rate measurement. A heater pattern 34 is formed on the surface of a cylindrical rod 3. When electricity is conducted in the heater pattern 34 and heat is generated, the heat is transmitted to the sub-passage 26 through an insulating layer. The heat is gradually transmitted up to the leading end of the sub-passage 26, and burns out pollutional substances adhering to the sub-passage 26. In this way, accumulation in the sub-passage 26 of pollutional substances can be prevented, thus attaining a fluid flow rate measurement apparatus that enables high-accuracy fluid flow rate measurement.

Abstract: An engine that re-circulates its exhaust gas suffers decreased accuracy in estimating an EGR rate real-time especially while the operating state of the engine is in a transitional state, which often results in torque fluctuations and deteriorated exhaust gas. A sensor for directly detecting an EGR flow rate is disposed in an EGR path. An EGR rate and in-cylinder oxygen concentration are calculated from the output value of that sensor. In addition, when this EGR rate calculation method is used, the calculation is properly switched between a steady operation state characterized by a low load and small rotational fluctuations and a transitional operating state including the acceleration and deceleration. This makes it possible to correctly estimate the EGR rate and the in-cylinder oxygen concentration under a wide range of engine operation conditions, and thereby to avoid the fluctuation of torque and the deterioration of exhaust gas.

Abstract: A thermal flow meter corrects flow rate detection errors produced by vaporization of liquid phase components included in a gas to be measured. The thermal flow meter includes a correction circuit 500 that applies respectively different predetermined voltages to heating resistors consisting of first heating resistor Rh1 and second heating resistor Rh2 of a sensor element disposed in the gas to be measured to set a first temperature state and a second temperature state, calculates a first flow rate value Q1 of the gas to be measured in the first temperature state and a second flow rate value Q2 of the gas to be measured in the second temperature state, and calculates a flow rate correction value ?Q based on a ratio (Q1/Q2) between the first flow rate value and second flow rate value or a fourth-power value (Q1/Q2)4 of the ratio to correct a flow rate of the gas to be measured.

Abstract: In a gas flowmeter in which a rod and a sensor element are formed as a single body, for preventing heat of the sensor element from flowing into a sensor probe through a substrate (rod) so as to suppress considerable power consumption, and for obtaining a necessary response speed with respect to a flow rate of gas to be measured or a change in temperature, the gas column (rod) is made of an insulating material on a center axis of the sensing probe and is formed with a conductor pattern on its surface, and the sensing probe connects the sensor element disposed in a pipe through which the gas to be measured flows and a harness terminal through the conductor on the surface of the rod, so as to measure a gas flow rate by using the sensing prove.

Abstract: A thermal type flow meter has a first heating resistor, a second heating resistor for blocking heat transfer from the first heating resistor to a console, a temperature measuring resistor interposed between the two heating resistors, and a controller for calculating a flow rate unrelated to temperatures of fluid from temperatures of the resistors and currents supplied to the heating resistors.

Abstract: The present invention prevents an EGR sensor installed in an engine's EGR path from being soiled by soiling substances in exhaust. A catalyst is positioned upstream of the EGR sensor to purify the soiling substances in EGR gas. The status of the EGR sensor is properly controlled in accordance with the conditions of the catalyst. This ensures the EGR sensor is less likely to be affected by the soiling substances in the exhaust under any circumstances of the EGR path and allows the EGR sensor to avoid a decrease in the accuracy of EGR gas detection. An alternative configuration may be employed such that the EGR gas recirculates from the downstream side of a catalyst installed in a main exhaust path.

Abstract: A thermal type gas flowmeter comprising a sensor element which, in turn, comprises at least one first heating resistor, two or more resistors in fluid and a second heating resistor which is disposed between the first heating resistor and a housing supporting the sensor element. The first and second heating resistors are electrically independent from each other. A temperature sensing unit is provided between the first and second heating resistors. A temperature of the first or second heating resistor is controlled by a temperature sensed by the temperature sensing unit.

Abstract: An intake manifold for an internal combustion engine, being variable in an intake length, comprising: a first volume chamber disposed in a downstream side of a throttle valve for controlling an intake air passing through an air-cleaner; first independent intake passages being divided from said first volume chamber for guiding the air within said first volume chamber into each of cylinders; second independent intake passages joining and conducting to each of said first independent intake passages, each of which is provided for said each of cylinders respectively; a second volume chamber conducting to all of said second independent intake passages; and valves being provided in said independent intake passages for conducting/shutting off between said second volume chambers and said first independent intake passage, wherein said first independent intake passage and said first volume chamber are built up with a plural number of synthetic resin molded members, and said second independent intake passage surrounding