GB2058360A

GB2058360A - A measuring sensor for gases

Info

Publication number: GB2058360A
Application number: GB8027951A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-09-01
Filing date: 1980-08-29
Publication date: 1981-04-08
Also published as: JPS5637545A; IT8024387A0; DE2935364A1; SE8006054L; IT1132598B; FR2464458A1

Abstract

A measuring sensor for gases comprising at least one wafer-like sensor member (14/1 .. 14/2) with layer-like measuring elements disposed thereon is integrated in a flat seal (10) serving as measuring sensor housing. The flat seal or gasket 10 is disposed between two pipes carrying gas. That end portion of the sensor member which faces the gas to be measured carries the measuring elements which are directly exposed to the gas to be measured. The arrangement enables a measuring sensor to be constructed in an inexpensive manner and frequently enables it to be fitted in those regions of devices, carrying gases to be measured, where there are normally no facilities for installing measuring sensors. The measuring elements may be solid electrolyte sensors, and the members (14/1 ... 14/2) may be elongated or circular. <IMAGE>

Description

SPECIFICATION A measuring sensor for gases The present invention relates to a measuring sensor for gases.

More particularly the invention relates to a measuring sensor having at least one sensor member which is enclosed in a housing for sealingly installing it in a device carrying the gas to be measured. However, a measuring sensor of this kind, which is already known from USA Patent Specification No. 4,007,435, has the disadvantage that its screw-in housing renders it relatively expensive. Moreover, the screw-in region, generally the exhaust pipe of a motor vehicle engine or, alternatively, the intake pipe of an engine of this kind, has to be prepared for the installation of a measuring sensor of this kind, thus involving additional expense.Measurements taken by means of measuring sensors are usually entirely excluded if the measurements are to be made in the combustion chamber of massproduced engines, since the manufacturer provides only one screw-in facility for spark plugs in engines of this kind.

According to the invention there is provided a measuring sensor, for gases, comprising a housing in the form of a flat gasket which, in use, is disposed between two components of the device carrying the gas to be measured, and at least one wafer-like sensor member sealingly enclosed within the housing, the sensor member carrying measuring elements which are directly exposed to the gas to be measured.

In contrast to the prior art, the measuring sensor in accordance with the invention has the advantage that the cost of the measuring sensor can be reduced by a considerable extent, and that the installation of measuring sensors of this kind usually does not require any special measures in the region of the motor vehicle engine and, furthermore, that a measuring sensor in accordance with the invention can also be used for measurements on mass-produced engines, even for measurements in the combustion chamber of engines of this kind.

The present invention will now be described further, by way of example only, with reference to the accompanying drawings, in which: - Figure 1 is a plan view, drawn to a reduced scale, of a pipe seal having two integrated sensor wafers in accordance with the invention, Figure 2 is a portion, drawn to an enlarged scale, of the pipe seal of Figure 1, Figure 3 is a cross section, taken on the line A/B, through the pipe seal having the sensor of Figure 2, Figure 4 shows a different embodiment for installing a sensor in a pipe seal, Figure 5 is a cross section, taken on the line C/D, through the pipe seal having the sensor of Figure 4, and Figure 6 is a plan view, drawn to a reduced scale, of a gasket having a sensor for each port.

Figures 1 to 3 show a flat seal 10 which is made from a conventional sealing material such as asbestos, plastics material, rubber or the like, and which is 2.5 mm thick. This flat seal 10 is in the form of a sealing ring and can be fitted between, for example, two flanges (not illustrated) of an exhaust pipe (also not illustrated) and has four through holes 11 through which are guided connection bolts (not illustrated) for the flanges of the exhaust pipe. The port 12 of the flat seal 10 is provided with a metal rim reinforcement 13 which is made from sheet steel or the like. Two sensors 14/1 and 14/2 in the form of elongate wafers are integrated in the flat seal 10 such that their end portions which face the gas to be measured, and which carry the known measuring elements (not illustrated), extend into the port 12 in the flat seal 10 serving as a sensor housing.A single sensor 14/1 or 14/2 can be fitted in a flat seal 10 of this kind according to requirements, although, as is illustrated, more than one sensor 14/1 ... can be integrated in a flat seal 10 of this kind.

Furthermore, it is also possible to mount a plurality of measuring elements (not illustrated) on each sensor 14/1 ... in the manner known from, for example, German Offenlegungsschrift No. 28 22 391. In accordance with this German Offenlegungsschrift, the actual sensor is equipped with a measuring element and a temperature sensor and, moreover, since it is a gas sensor, it is also provided with a heating element. Those end portions of the sensors 14/1 and 14/2 which are remote from the gas to be measured are enclosed by the flat seal 10, this being particularly important for reasons of sealing when the gas to be measured is subjected to pressure.If the gas to be measured is subjected to particularly high pressure ratios, a plastics reinforcement (not illustrated) can be jointly provided in addition to the widened portions 1 5/1 and 15/2 formed on the flat seal 10 at those end portions of the sensors 14/1 and 14/2 which are remote from the gas to be measured. The plastics reinforcement is applied by methods such as spraying, pressing or welding, it also being possible to provide a metal reinforcement if required. The widened portions 1 5/1 and 1 5/2 of the flat seal are provided with respective windows 16/1 and 16/2 which lead to the respective sensors 14/1 and 14/2 and which permit the electrical connection of the conductors (not illustrated) leading from the measuring elements in this region.Parts (not illustrated) of a casing for the electrical connections can also be commonly formed with the reinforcements (not illustrated) of the widened portions 1 5/1 and 15/2.

The metal rim reinforcement 13 has openings 17 in those regions in which sensors 14/1 and 14/2 are disposed and preferably also projections 1 8 which are disposed on the upper side and the underside of the flat seal and which are directed towards the respective windows 1 6/1 and 1 6/2 in the flat seal and which serve to reinforce this region of the flat seal 10 and whose free end portions are preferably provided with lugs 19 which are anchored in the flat seal 10.

Alternatively, however, according to the case of application, those end portions of the sensors 14/1 and 14/2 which face the gas to be measured can be flush with the metal rim reinforcement 13, and they can even be set back somewhat behind the metal rim reinforcements 13 when, as is illustrated, the flat seal 10 and those end portions of the sensors 14/1 and 14/2 which face the gas to be measured are provided with a recess 20. By providing the sensors 14/1 and 14/2 with a corrugated side configuration (not illustrated) or a side configuration incorporating projections and depressions, the sensors can be integrated very tightly in a flat seal 10.With respect to satisfactory sealing of sensors 14/1 ... in a flat seal 10, it is also advantageous if they have a trapezoidal configuration instead of the rectangular configuration illustrated, the wide base line of the trapezium being directed towards the port 12.

Figures 4 and 5 show a portion of a flat seal 10' which can also be used as a pipe seal or as a cylinder head gasket, but which differs from the embodiment of the flat seal 10 of Figures 1 to 3.

The sensor 14/1' shown in Figures 4 and 5 is in the form of a circular disc whose contact points 21 associated with the measuring elements (not illustrated) are jointly formed in the flat seal 10' together with electrical leads 22 and plug contacts 23. The plug contacts 23 are disposed in a widened portion 15/1' of the flat seal 10'. The circular shape of the sensor 14/1', the zig-zag arrangement of the electrical leads 22, and the arrangement of through holes 24 for bolts (not illustrated) at each side of the sensor 14/1', ensure that leakage losses are avoided in this region. The construction of the flat seal 10' otherwise corresponds substantially to the construction of the flat seal 10 of Figures 1 to 3.

Figure 6 shows a gasket 25 of the kind used to seal intake pipe flange or flanges of exhaust manifolds of engines. When using the present invention, gaskets 25 of this kind render it possible to monitor all four (or more) inlets and/or outlets of an internal combustion engine by measuring technology. The same applies to cylinder head gaskets. The ports in the sealing gasket 25 are designated 26/1 to 26/4, and the sensors, including the measuring elements (not illustrated), are designed 27/1 to 27/4. The sensors 27/1 to 27/4 are arranged and installed substantially in the same way as is shown in Figures 1 to 5.

It may be mentioned that the sensors 14 and 27 can be provided with any suitable measuring elements, including the gas or oxygen measuring sensors which operate with ion-conducting solid electrolytes on the principle of the oxygen concentration chain.

Claims

1. A measuring sensor, for gases, comprising a housing in the form of a flat gasket which, in use, is disposed between two components of the device carrying the gas to be measured, and at least one wafer-like sensor member sealingly enclosed within the housing, the sensor member carrying measuring elements which are directly exposed to the gas to be measured.

2. A measuring sensor as claimed in claim 1, in which the sensor member is substantially in the form of an elongate wafer or a circular disc.

3. A measuring sensor as claimed in claims 1 or 2, in which that end portion of the sensor member, which faces the gas to be measured is located in a recess in the inside of the flat seal.

4. A measuring sensor as claimed in claims 1, 2 or 3, in which the flat seal incorporates at least one aperture for the electrical connection of each sensor member.

5. A measuring sensor as claimed in any of claims 1 to 4, in which plug contacts are formed in the flat seal for the electrical connection of the sensor member.

6. A measuring sensor as claimed in claim 5, in which electrical leads are interposed between the plug contacts and the at least one sensor member.

7. A measuring sensor as claimed in any of claims 1 to 6, in which the flat seal incorporates in the region of each sensor member and the connections thereof an integral widened portion directed towards the outside of the flat seal.

8. A measuring sensor as claimed in any of claims 1 to 7, in which that end portion of each sensor member which is exposed to the gas to be measured passes through a respective opening in a metal rim reinforcement, of the flat seal, disposed adjacent the gas to be measured.

9. A measuring sensor as claimed in claim 8, in which the rin reinforcement disposed on the inside of the flat seal is provided with at least one projection which is directed towards the sensor connections and which is anchored in the flat seal.

10. A measuring sensor as claimed in claim 9, in which the rim reinforcement is achored in the flat seal by means of the free end of the at least one projection.

11. A measuring sensor constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.