Glow-plug adaptor for pressure measurements

Patent metadata

Field	Value
Publication number	US-10168242-B2
Application number	US-201515119785-A
Country	US
Kind code	B2
Filing date	Feb 13, 2015
Priority date	Feb 25, 2014
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A glow plug adaptor for pressure measurement in a combustion chamber of an internal combustion engine includes an adaptor sleeve attached to an adaptor head that contains a pressure sensor with a diaphragm. A sealing shoulder can be screwed into an opening in a combustion chamber to provide a pressure-tight seal and permit passage of signal conductors from the pressure sensor through the adaptor sleeve. The adaptor head is tapered at the proximal combustion chamber end, and in the adaptor head a cavity is formed in such a way that the cavity is bounded by the diaphragm of the pressure sensor mounted therein and by a closed end wall of the adaptor head.

First claim

The invention claimed is:

1. A pressure measurement apparatus for measuring pressure within the interior of a combustion chamber of an internal combustion engine, the apparatus comprising:
a chamber wall defining the combustion chamber, the chamber wall further defining a hollow glow-plug socket that is open at both opposite ends thereof and communicating with the interior of the combustion chamber via a chamber opening at one of the open opposite ends of the glow-plug socket; and
a glow-plug adaptor disposed in a pressure-tight manner in the glow plug socket, the glow plug adaptor including:
an adaptor head elongating along a longitudinal axis and defining a proximal combustion chamber end and a distal combustion chamber end disposed opposite the proximal combustion chamber end of the adaptor head, the adaptor head defining an external surface with a sealing shoulder disposed between the proximal combustion chamber end and the distal combustion chamber end and configured for forming a pressure-tight seal upon contacting an opposing surface of the socket, the proximal combustion chamber end defining a tapered external surface and an internal surface that defines part of a cavity;
a pressure sensor including a diaphragm and signal conductors, the pressure sensor being mounted in the adaptor head with the diaphragm defining one opposite end of the cavity;
a hollow adaptor sleeve elongating along the longitudinal axis and attached to the distal combustion chamber end of the adaptor head and receiving the signal conductors passing through the adaptor sleeve, which defines an external surface that is configured for being screwed into the glow-plug socket so as to dispose the sealing shoulder of the adaptor head in a pressure-tight engagement with the socket while disposing the signal conductors extending from one of the opposite ends of the socket;
wherein opposite the diaphragm the cavity is defined by a closed end wall that defines a flat external surface that is perpendicular to the longitudinal axis and has a diameter that is less than the diameter of the external surface of the adaptor head, the adaptor head further defining a side wall connected to the end wall and extending toward the diaphragm, wherein the side wall defines a tapered region through which are formed a plurality of gas exchange channels that extend into the cavity; and
wherein the front height of the cavity extending along the longitudinal axis from the diaphragm as far as the external surface of the end wall is less than the diameter of the adaptor head in the area of the cavity; and

wherein the glow plug adaptor is arranged recessed in the glow-plug socket from the chamber opening at a recess distance in such a way that the adaptor head rests entirely within the glow-plug socket and the recess distance, which is measured along the longitudinal axis between a central point on the external surface of the end wall and the center of the chamber opening, is greater than zero; and
wherein the glow-plug socket is defined by an inner wall and a portion of the exterior of the adaptor head located between the side wall of the adaptor head and the sealing shoulder of the adaptor head is disposed alongside and spaced apart from the inner wall by a gap, wherein the size of the gap is no more than 0.05 mm.

2. The pressure measurement apparatus according to claim 1 , wherein the recess distance is less than 10 mm.

3. The pressure measurement apparatus according to claim 1 , wherein the adaptor head is integrally formed from at least two parts.

4. The pressure measurement apparatus according to claim 1 , wherein the proximal combustion chamber end of the adaptor head is designed in the shape of a frustum.

5. The pressure measurement apparatus according to claim 1 , wherein the diaphragm of the pressure sensor is part of a piezoelectric sensor.

6. The pressure measurement apparatus according to claim 1 , wherein three gas exchange channels are defined in the adaptor head.

7. The pressure measurement apparatus according to claim 6 , wherein each of the gas exchange channels is disposed to extend at an angle between 30° and 90° to the longitudinal axis.

8. The pressure measurement apparatus according to claim 6 , wherein each of the gas exchange channels is disposed to extend at an angle 60° to the longitudinal axis.

Assignees

• Kistler Holding Ag

Inventors

• Brechbühl Stefan
• Brunner Simon

Classifications

• F23Q7/001

  Glowing plugs for internal-combustion engines · CPC title

• G01L9/008

  using piezoelectric devices (piezoelectric resonators G01L9/0022; surface acoustic waves G01L9/0025) · CPC title

• G01L19/0681 Primary

  Protection against excessive heat · CPC title

• F23Q2007/002

  with sensing means · CPC title

• G01L23/22

  for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines · CPC title