Abstract: An oxygen concentration-sensing device has an oxygen concentration-sensing element which senses the concentration of oxygen contained in a gas, and a heater which heats the sensing element. A control device is electrically connected to the heater for controlling the supply of electricity to the heater so as to bring the temperature of the heater to a desired temperature. A coupler connects between the sensing element and the control device. A compensating resistance is accommodated in the coupler, which has a resistance value corresponding to a resistance value of the heater assumed at the desired temperature. The control device controls the supply of electricity to the heater based upon electrical information obtained from the compensating resistance.

Abstract: An oxygen concentration detecting device includes at least one oxygen concentration detecting element formed by an oxygen-pumping element and a cell element, composed of an oxygen ion-conductive wall, separating a pair of electrodes. The oxygen-pumping element and cell element define a gas diffusion chamber. A current detecting resistance forms a series circuit with the oxygen-pumping element. A voltage applying circuit applies to the series circuit an output voltage corresponding to the difference between a voltage between the electrodes of the cell element and a first reference voltage. An output detecting circuit outputs a voltage signal corresponding to a value of pumping current flowing through the resistance. An operational amplifier has a non-inverting input terminal supplied with a second reference voltage, an inverting input terminal connected to one end of the resistance, and an output terminal connected to the other end of the resistance.

Abstract: An air-fuel mixture heating device for heating an air-fuel mixture supplied from a carburetor to an intake manifold includes an insulator mounted between the carburetor and the intake manifold and having a first air-fuel mixture passage communicating with the primary air-fuel mixture passage in the carburetor, an electric heater disposed in the first air-fuel mixture passage of the insulator for heating the air-fuel mixture, and a plurality of conductors embedded in the insulator and having portions connected to the electric heater and an electric power supply. The insulator has access holes extending to the portions of the conductors for allowing said portions to be joined to the electric heater therethrough. The access holes are filled up with masses of sealing resin after said portions are joined to the electric heater.

Abstract: A flow control honeycomb structure for use in an intake passage of an engine for producing turbulent flow in an air-fuel mixture flowing through the intake passage, which structure includes a short cylindrical peripheral wall defining therein a circular passage having a substantially circular cross section, a plurality of substantially crisscross partitions joined to and disposed in the peripheral wall and dividing the circular passage into a first group of square passageways each having a substantially square cross section and a second group of four triangular passageways each having a substantially triangular cross section and a relatively large cross-sectional area, and a plurality of ribs extending obliquely from joints of those of the passageways which define the triangular passageways radially outwardly to the peripheral wall through the triangular passageways to divide each of the triangular passageways into a plurality of subpassageways of substantially the same cross-sectional area as the square pass