Pressure Measuring Instrument
First Claim
1. A pressure sensor comprising:
- a body defining an interior space;
a diaphragm dividing the interior space into a measured pressure cavity and a reference pressure cavity;
a measured pressure inlet in the body in fluid communication with the measured pressure cavity;
a single electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body;
a ceramic seal member disposed between the electrode and the body to provide electrical insulation there between, a first portion of the ceramic seal member being brazed to the body and a second portion of the ceramic seal member being brazed to the electrode to form a hermetic seal there between and to support the plate portion within the reference pressure cavity in a position spaced from the body by a vacuum relief space;
the plate portion of the electrode dividing the reference pressure cavity into a front volume adjacent the face and a rear volume behind the plate portion, the front volume and rear volume in fluid communication through the vacuum relief space; and
an evacuation opening through the body and into the rear volume, such that a vacuum applied at the evacuation opening will evacuate the rear volume directly and will evacuate the front volume through the vacuum relief space.
1 Assignment
0 Petitions
Accused Products
Abstract
A pressure sensor (40) useful as a vacuum manometer. A reference pressure cavity (50) of the sensor is evacuated through an evacuation opening (72) located behind a plate portion (54) of the sensor electrode (52) having a non-planar surface for supporting the diaphragm (44) during an overpressure event. The electrode is hermetically sealed to the body (42) of the sensor by a brazed joint with a ceramic seal member (60) disposed there between. The brazed joint may include a layer of buffer material (79) which provides a degree of malleability to the joint to avoid cracking of the ceramic seal member. The brazed ceramic/metal joint permits the selection of materials such that differential thermal expansion effects can be passively minimized. The electrode is connected to the sensor circuitry (84) by a wire having a spring section (53), thereby providing a stress free interconnection.
5 Citations
20 Claims
-
1. A pressure sensor comprising:
-
a body defining an interior space; a diaphragm dividing the interior space into a measured pressure cavity and a reference pressure cavity; a measured pressure inlet in the body in fluid communication with the measured pressure cavity; a single electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body; a ceramic seal member disposed between the electrode and the body to provide electrical insulation there between, a first portion of the ceramic seal member being brazed to the body and a second portion of the ceramic seal member being brazed to the electrode to form a hermetic seal there between and to support the plate portion within the reference pressure cavity in a position spaced from the body by a vacuum relief space; the plate portion of the electrode dividing the reference pressure cavity into a front volume adjacent the face and a rear volume behind the plate portion, the front volume and rear volume in fluid communication through the vacuum relief space; and an evacuation opening through the body and into the rear volume, such that a vacuum applied at the evacuation opening will evacuate the rear volume directly and will evacuate the front volume through the vacuum relief space. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A pressure sensor comprising:
-
a body; a diaphragm separating a measured pressure cavity from a reference pressure cavity within the body; an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through a body of the pressure sensor; circuitry supported by the body and electrically connected to the electrode to receive a capacitance signal; and a wire comprising a coil surrounding the electrode post at a first end and connected to the circuitry at a second end to conduct the capacitance signal. - View Dependent Claims (9)
-
-
10. A pressure sensor comprising:
-
a body; a diaphragm separating a measured pressure cavity and a reference pressure cavity within the body; an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body; a ceramic seal member disposed between the post and the body; and a hermetic seal between the post and the body comprising a braze joint comprising a buffer material between the ceramic seal member and at least one of the post and the body. - View Dependent Claims (11, 12, 13, 14, 15, 16)
-
-
17. A pressure sensor comprising:
-
a body; a diaphragm separating a measured pressure cavity and a reference pressure cavity within the body; an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body; a ceramic seal member disposed between the post and the body; and a hermetic seal between the post and the body comprising a ceramic seal member and a braze interface joining the ceramic seal member to the post and to the body; wherein materials and axial length proportions of the ceramic seal member, braze interface, and electrode are chosen so as to match a thermal expansion characteristic of the body in order to substantially eliminate thermal offset sensitivity of the gap. - View Dependent Claims (18, 19, 20)
-
Specification