Apparatus for measuring the mass of a flowing medium

Claim 1

An apparatus for measuring the mass of a flowing medium, such as the intake air mass to an internal combustion engine comprising: a tubular member having an inner surface which defines a flow cross section of the flowing medium, a mounting aperture, an insert element which is plugged into the mounting aperture and mounted to the tubular member, a probe ring mounted to the insert element and arranged within the flow cross section, a bridge circuit including at least two resistors supported within the probe ring so that they are exposed to the flowing medium, one of said resistors being embodied as a hot wire, a parameter of which is controlled in dependence on the mass of the flowing medium, a multiple contact plug connected to the tubular member which connects the bridge circuit to a source of D.C. voltage and from which the parameter control is detected, a terminal box mounted to the tubular member, a mounting board mounted within the terminal box to the insert element, an electrical control circuit mounted to the mounting board, a printed circuit board having minimal conductive paths, (i) the extent to which the controlled parameter of said one of said resistors is controlled being a measure of the mass of the flowing medium and (ii) the electrical control circuit being connected by the printed circuit board to the multiple contact plug and to the bridge circuit, (iii) the electrical control circuit comprising a hybrid switching circuit, a frame, (iv) the frame being arranged between the mounting board and the printed circuit board, and includes perforations which taper in the direction toward the printed circuit board, and (v) the bridge circuit, the hybrid switching circuit and the multiple contact plug each including contacts, said contacts extending through the perforations in said frame.

Claim 2

An apparatus for measuring the mass of a flowing medium, such as the intake air mass to an internal combustion engine comprising: a tubular member having an inner surface which defines a flow cross section of the flowing medium, a mounting aperture, an insert element which is plugged into the mounting aperture and mounted to the tubular member, a probe ring mounted to the insert element and arranged within the flow cross section, a bridge circuit including at least two resistors supported within the probe ring so that they are exposed to the flowing medium, one of said resistors being embodied as a hot wire, a parameter of which is controlled in dependence on the mass of the flowing medium, a multiple contact plug connected to the tubular member which connects the bridge circuit to a source of D.C. voltage and from which the parameter control is detected, a terminal box mounted to the tubular member, a mounting board mounted within the terminal box to the insert element, an electrical control circuit mounted to the mounting board, a printed circuit board having minimal conductive paths, (i) the extent to which the controlled parameter of said one of said resistors is controlled being a measure of the mass of the flowing medium and (ii) the electrical control circuit being connected by the printed circuit board to the multiple contact plug and to the bridge circuit, (iii) the electrical control circuit comprising a hybrid switching circuit, a frame, (iv) the frame being arranged between the mounting board and the printed circuit board, and includes perforations which taper in the direction toward the printed circuit board, and (v) the bridge circuit, the hybrid switching circuit and the multiple contact plug each including contacts, said contacts extending through the perforations in said frame.