Resistive particle sensor

Abstract

A resistive particle sensor is described for detecting soot in the exhaust gas of an internal combustion engine, including a sensor element having two strip conductors, which extend spaced apart in meanders in parallel to one another in an area of the sensor element that may be exposed to the exhaust gas, and a resistance strip conductor, the two strip conductors each being capacitively connected via capacitor elements to the resistance strip conductor.

Claims

1. A resistive particle sensor for detecting soot in the exhaust gas of an internal combustion engine, comprising: a sensor element having two strip conductors, which extend spaced apart in meanders in parallel to one another in an area of the sensor element that may be exposed to the exhaust gas, and a resistance strip conductor, the two strip conductors each being capacitively connected via capacitor elements to the resistance strip conductor, wherein the two strip conductors are branch-free strip conductors, which each originate from a contact surface, which is situated outside the area that may be exposed to the exhaust gas, for contacting the sensor element, each of the two strip conductors lead from the contact surface to the area of the sensor element that may be exposed to the exhaust gas, extend in meanders in the area of the sensor element that may be exposed to the exhaust gas, and subsequently lead to the capacitor elements, and the resistance strip conductor originates from a contact surface, which is situated outside the area that may be exposed to the exhaust gas, for contacting the sensor element and lead to a further contact surface, which is situated outside the area that may be exposed to the exhaust gas, for contacting the sensor element and the resistance strip conductor includes a capacitor element and/or is electrically connected to a capacitor element via a branch line.

2. The resistive particle sensor as recited in claim 1, wherein the capacitor elements are full-surface layers, between which an insulation layer is situated.

3. The resistive particle sensor as recited in claim 1, wherein the capacitor elements are metallic grids and/or line structures, between which an insulation layer is situated.

4. The resistive particle sensor as recited in claim 1, wherein a value of the capacitive connection is 50 to 800 pF (picofarad).

5. The resistive particle sensor as recited in claim 1, wherein the resistance strip conductor is a resistance heater and/or a temperature measurement resistance strip conductor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an overview of a particle sensor according to the present invention.

(2) FIG. 2 shows a first specific embodiment in schematic form.

(3) FIG. 3 shows a second specific embodiment in schematic form.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(4) FIG. 1 shows an overview of a particle sensor 110 according to the present invention in cross section along the longitudinal axis of particle sensor 110. This particle sensor 110 includes a metallic housing 111 having a through-hole 112, in which a ceramic sensor element 113 is fixed by a seal packing 131 and an exhaust-gas-side insulation sleeve 132 and a contact-side insulation sleeve 114. For example, 4 to 6 contact springs 115, which are in turn held in a contact holder 214, are pushed onto a contact-side end area of sensor element 232. On its side facing away from the exhaust gas, protective sleeve 116 is closed by a seal bushing 122, through which insulated conductors 123 electrically connected to contact springs 115 are guided.

(5) Two coaxial protective tubes 141, 142 are fixed with the aid of a shared peripheral weld seam 160 on an exhaust-gas-side collar 161 of housing 111 on the side of metallic housing 111 facing toward the exhaust gas. Protective tubes 141, 142 include openings and cover and exhaust-gas-side end area of sensor element 233. This exhaust-gas-side end area of sensor element 233 is thus an area of sensor element 113 that may be exposed to the exhaust gas. In contrast, the contact-side end area of sensor element 232 is an area which may not be exposed to the exhaust gas in the meaning of the present invention.

(6) Particle sensor 110 includes an external thread 151 and an external hexagon profile 152 for the installation in an exhaust system.

(7) FIG. 2 schematically shows elements of sensor element 113 of the resistive particle sensor from FIG. 1. Strip conductors 25, 26 are branch-free and each originate from a contact surface 251, 261, which is situated outside the area that may be exposed to the exhaust gas, for contacting sensor element 113. From contact surface 251, 261, strip conductors 25, 26 lead to the area of sensor element 113 that may be exposed to the exhaust gas, where they extend in meanders 252, 262 in parallel to one another. Subsequently, strip conductors 25, 26 extend via supply line sections 253, 263 to capacitor elements 254, 264, which are situated flatly adjacent to one another in the example.

(8) A resistance strip conductor 28, which is a resistance heater in the example, extends essentially in a layer plane below strip conductors 25, 26. A further resistance strip conductor 29, which is a temperature measurement resistance strip conductor in the example, extends essentially in a layer plane situated still further below.

(9) Resistance strip conductor 28 and further resistance strip conductor 29 each include a contact surface 281, 291, which is situated outside the area that may be exposed to the exhaust gas, for contacting sensor element 113.

(10) Resistance strip conductor 28 and further resistance strip conductor 29 lead to a further contact surface 282, which is situated outside the area that may be exposed to the exhaust gas and is shared in the example, for contacting sensor element 113. Shared contact surface 282 is connectable, for example, to a ground potential.

(11) Resistance strip conductor 28 is connected via a branch line 283 to capacitor element 284, which is situated opposite to capacitor elements 254, 264 flatly and separated by an insulation layer (not shown) outside the area of sensor element 113 that may be exposed to the exhaust gas.

(12) The two capacitor elements 254, 264 are formed over the entire surface and situated adjacent to one another. The two capacitor elements 254, 264 and the insulation layer form, together with capacitor element 284, a capacitance, whose value in the example may be a total of 150 pF (picofarad), 200 pF, or 300 pF.

(13) A second specific embodiment is shown in FIG. 3. This differs from the specific embodiment shown in FIG. 2 in that capacitor element 284 of resistance strip conductor 28 is not formed separately, but rather is part of resistance strip conductor 28. In the example, capacitor element 284 is formed by widened strip conductors of resistance strip conductor 28, which are situated opposite to capacitor elements 254, 264 flatly and separated by an insulation layer (not shown). Capacitor elements 254, 264 are situated in the example in a different layer plane than the contact-side parts of strip conductors 25, 26. For this purpose, supply line sections 253, 254 are formed as a through-contact through a layer of sensor element 113.

(14) Sensor element 113 may be manufactured, for example, in conventional thick-film technology.