US 4,430,899 AGranted

Fluid pressure sensor, particularly diesel engine injection pump pressure sensor

AssigneeRobert Bosch GmbH

InventorWolf Wessel

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Abstract

To provide a high output signal, a strain bolt (12, 12a) is screwed (13, 13a) into a tapped bore extending through the housing wall (10), the bolt having a bore (14) extending therethrough, and a region or zone (18) of reduced outer diameter to form a comparatively thin-walled tubular or sleeve-like region which, upon application of fluid, typically liquid fuel pressure within the housing, tends to elongate the portion of the bolt of reduced wall thickness; a piezo-ceramic transducer assembly, preferably formed of two oppositely polarized disks (23, 24) is clamped between an integral head (FIG. 1: 19) or a separate clamping nut (FIG. 2: 31) and the outer wall of the housing, or an abutment surface formed by the upper surface of an intermediately positioned tightening nut (FIG. 2: 19a) so that, upon application of fluid pressure, and straining of the thin-walled portion (18) of the bolt, the bias pressure on the piezo-ceramic disks (23, 24) changes, thus providing an output signal available from a central terminal (25a).

Claims9

Dependent claims

Fluid pressure sensor, particularly for high fluid pressures (P) in a chamber within a housing (10) having

a bolt (12, 12a) secured in a wall of the housing, said bolt (12, 12a) being formed with a bore (14) which communicates with said chamber so that fluid, under pressure, in said chamber will penetrate into the bore;
and a pressure-sensitive element (21-26) providing an output signal representative of the pressure of the fluid
wherein
the bolt has one end (13, 13a) thereof secured in fixed position in the wall of the housing;
means (19, 30, 31) are provided clamping the pressure-sensitive element between the wall of the housing and the other end of the bolt;
and said bolt has a region (18) which is elasticallly deformable upon application of said fluid pressure (P), which region is positioned between both said ends,
the outer diameter of the bolt being reduced in said region (18) to leave a thin-walled section of the bolt permitting deformation thereof under application of fluid pressure, and thus provide for reduction of clamping pressure on the pressure-sensitive element to provide said output signal representative of pressure in the chamber.

4 more elements

Dependencies are inferred from the claim text.