Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1998-11-23
2001-04-10
Oen, William (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
Reexamination Certificate
active
06212946
ABSTRACT:
PRIOR ART
The invention relates to a device for detecting the pressure and the temperature in the intake tube of an internal combustion engine, wherein a temperature sensor and a pressure sensor, secured with little stress on a substrate together with an evaluation circuit, are disposed in a common housing.
A device for detecting the pressure and the temperature in the intake tube of an internal combustion engine, in which a temperature sensor and a pressure sensor are disposed in a common housing, is disclosed for instance in German Patent DE 28 51 716C1.
The combination of a pressure sensor, derived for instance from German Patent Disclosure DE 43 17 312 A1, and a temperature sensor is shown in FIG.
5
.
In the pressure sensor shown in
FIG. 5
, a single-chip silicon pressure sensor (not shown) is used that includes a sensor cell, in which the pressure is introduced to the back side of a diaphragm, while a reference vacuum is provided on the front side of the diaphragm, for measuring the absolute pressure. The pressure sensor is accommodated in a hermetically sealed housing
82
, which in turn is disposed in the housing
80
of the overall device for detecting the pressure and the temperature. Also disposed in the housing
80
is a printed circuit board
83
with capacitors, which are required for the sake of electromagnetic compatibility. The printed circuit board
83
is also used to connect with flat plug contacts
84
, which are disposed on a neck
85
molded onto the housing
80
.
A temperature sensor
86
in the form of an NTC resistor, which is injected into a tubular plastic sheath
87
, is also disposed in a pressure neck
88
, and its connection leads are electrically conductively connected to flat plug contacts
84
via inlet parts
90
that are welded to the NTC wires.
Not only is this kind of device for detecting the pressure and temperature very complicated to produce, but for instance the electrical connections between the connection leads of the temperature sensor
86
and of the pressure sensor
82
and the printed circuit board
85
and the flat plug contacts
84
must be made by a soldered connection in the fully installed state. Then this soldered connection has to be potted, for instance with an adhesive compound
89
, for sealing purposes.
Another problematic aspect of such a device is that the temperature sensor
86
is disposed in a plastic sheath
87
, because the result of this, for many applications, is an overly long response time of the temperature sensor
86
.
Devices for detecting pressure and temperature in the intake tube of an internal combustion engine are also known in which the pressure sensor is subjected to the pressure on its front side. The actual pressure sensor itself is disposed on a glass base. A reference vacuum is enclosed between the glass base and the pressure sensor. The pressure sensor, in the form of a chip, is surrounded by a tiny frame and is protected against environmental factors by a protective gel. Such devices again require expensive and sometimes complicated production. Moreover, it cannot be precluded that via the housing, voltages and the like will be transmitted to the very sensitive pressure sensor and make the measurement outcome incorrect.
It is therefore the object of the invention to refine a device for detecting the pressure and the temperature in the intake tube of an internal combustion engine of the generic type in question, in such a way that while it is simple to produce, it enables a precise temperature measurement and in particular a very precise pressure measurement.
ADVANTAGES OF THE INVENTION
In a device for detecting the pressure and the temperature in the intake tube of an internal combustion engine of the type described at the outset, this object is attained according to the invention in that to introduce a medium that is under pressure, a neck part secured to the housing and an adapter, joined both to the substrate and to the neck part via adhesive seals that decouple mechanical stress are provided.
The two-part embodiment of the pressure connection by means of the neck part and the adapter, where the adapter is connected merely through adhesive seals to the substrate and the neck part, so that mechanical stresses are maximally decoupled, has the particularly major advantage that the measurement precision of the pressure measurement is increased by this design, since stresses that act for instance on the housing or the pressure connection are not transmitted to the pressure sensor. Moreover, by this relatively simple mechanical design, easy and unproblematic production of the entire device is assured.
The substrate to which the pressure sensor is secured may purely in principle be secured to the housing in the most various ways. A particularly advantageous embodiment, which in particular enables very good pressure decoupling, provides that the substrate in the housing is merely glued on at predetermined contact points. These contact points are selected such that as few stresses as possible that adulterate the pressure measurement are transmitted to the pressure sensor.
To protect the pressure sensor from environmental factors, it is advantageously provided that a ring is disposed around the pressure sensor, and that the interstice between the ring and the sensor is filled with a chemical gel.
As the chemical gel, a fluorine-silicone gel has proved especially advantageous.
With regard to the disposition of the temperature sensor in the device, once again the most various embodiments are possible. To enable especially direct coupling of the temperature sensor to the medium to be measured, it is advantageously provided in one exemplary embodiment that the temperature sensor is secured to the neck part in such a way that it protrudes into the interior thereof.
Particularly with a view to especially simple mounting of the temperature sensor, it is provided that the connection leads of the temperature sensor can be clamped, by a resilient clamp molded onto the neck part, to two jaws embodied on the neck part. In this way, the temperature sensor can not only be mounted and positioned on the neck part in a very simple way, but moreover, because of the clamping connection provided through the clips, it becomes possible to secure the connection leads of the temperature sensor in a way free of damage.
In order to assure that the temperature sensor and its connection leads will not be corroded or damaged and attacked by other environmental factors, it is advantageously provided that the temperature sensor and its connection leads are coated with a protective paint or a protective coating.
Preferably, the protective paint is a polyester amide paint.
Particularly with a view to good contacting, which can be established by means of especially simple mounting and assembly, it is also preferably provided that for contacting the connection leads of the temperature sensor with plug contact pins that are disposed in the housing and extended to the outside, insulation displacement contacts are provided.
REFERENCES:
patent: 4796584 (1989-01-01), Goto et al.
patent: 5036808 (1991-08-01), Stumpp
patent: 5505164 (1996-04-01), Hollis
Hirschberger Klaus
Kuhnt Winfried
Lipphardt Uwe
Naegele Erwin
Greigg Edwin E.
Greigg Ronald E.
Oen William
Robert & Bosch GmbH
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