Patent Description:
International patent application <CIT> relates to a sensor assembly for a motor vehicle adapted for sensing impacts including pedestrian impacts. The sensor assembly integrates functions of pressure based sensors used in combination with a compressible tube extending laterally across the front surface of the vehicle and the outboard front boundary areas of the front end of the vehicle. Both acceleration and pressure based sensors are mounted into an integrated sensor housing which is mounted in a desired position at the vehicle front fascia front boundary areas.

German patent application <CIT> relates to a sensor which has a sensing unit for recording a pressure change in a tubular body and detecting an impact on the pressure change. The sensor is arranged in a housing unit, and an adjusting unit adjusts pressure between the tubular body and a surrounding area.

The tubular body is pressurized-connected with the housing unit of the sensing unit, and the pressure is adjusted at the housing unit. A pressure compensation opening is provided at an inner side of the housing unit between the tubular body and the sensing unit and is arranged at the housing unit of the sensing unit.

The European Patent Application <CIT> discloses a pressure sensor with a housing, defining an internal space, which is in fluid communication with the pressure sensor so that the pressure of gas within the internal space can be sensed by the pressure sensor. A first connection arrangement, allowing connection of the sensor to a substantially enclosed and compressible sensing member, so that variations in pressure in the sensing member are communicated to the internal space. A venting arrangement, allowing gas communication between the internal space and the surrounding atmosphere. The venting arrangement leads to an exit port. A filter arrangement having an inner end and an outer end and being positioned within the passage so that it partially occludes the passage. The filter arrangement having at least one flow path formed therein passing from the inner end to the outer end but preventing or substantially preventing the passage of water through the filter arrangement.

The Chinese Patent Application <CIT> discloses a waterproof and breathable sensor protection mechanism, which comprises a protection cover, a sensor, a base material and a waterproof and breathable film. The sensor is arranged inside the protection cover. A first breathable hole is opened in the protection cover. A second breathable hole is opened in the base material.

The US Patent Application <CIT> discloses a pressure sensor with a case with an air passageway having a first opening leading to an inside of the case and a second opening leading to an outside of the case. The pressure sensing means that is placed inside the case and includes a pressure sensing surface for detecting pressure. A breathable filter that is provided with the air passageway to cover at least one of the first and second openings.

The US Patent Application <CIT> discloses an integrated pressure sensor assembly. The integrated pressure sensor assembly includes a printed circuit board assembly comprising a plurality of boards. A pressure die mounted on at least a portion of the printed circuit board assembly; and a housing engaged to the printed circuit board assembly. The printed circuit board assembly includes at least one pressure transmission channel and at least one electrical transmission channel. A filter prevents certain materials from receiving the pressure die.

It is therefore an object of the present invention to provide a sensor assembly which enables a reliable determination of pressure changes (caused by an impact with a vehicle) and protects the inside of a housing of the sensor assembly from the ingress of dust and/or fluid.

The above object is achieved by a sensor assembly which comprises the features of claim <NUM>.

According to an embodiment of the present invention a sensor assembly is disclosed. The sensor assembly comprises a housing which defines a hollow body. A formed connection defines a fluid communication from outside of the hollow body into the hollow body. A printed circuit board is placed in the hollow body, wherein the printed circuit board carries a pressure sensor. A ventilation connection of the housing allows an equalized pressure inside the hollow body. A further breathable seal is placed in the ventilation connection to avoid as well ingress of fluid, moisture, dirt or dust into the hollow body.

A pressure change, which might be caused by an impact with an object, is sensed by the pressure sensor. The pressure change is determined in relation to the external environmental conditions. A breathable seal is placed in relation to the connection. The fluid communication, caused by the pressure change, has to pass the breathable seal prior to causing a signal of the pressure sensor. The advantage is that the hollow body (internal sensor cavity) is protected from fluid, moisture, dirt or dust ingress.

According to the claimed invention, the sensor assembly has at least one first ventilation hole which provide the fluid communication from the connection to the hollow body. At least one second ventilation hole provide the fluid communication from the hollow body to the ventilation connection. The advantage is, that with the ventilation connection the pressure inside the sensor assembly is equalized with respect to external environment pressure conditions.

According to the claimed invention, a further breathable seal is placed in the ventilation connection and covers the at least one second ventilation hole which leads from the hollow body to the ventilation connection. The further breathable seal has the advantageous effect that no dirt, dust and/or moisture can ingress the hollow body through the ventilation connection.

According to a preferred embodiment of the invention, the breathable seal and the further breathable seal can be breathable and waterproof materials, e.g. foams, membranes or the like. The advantage of this embodiment is as well that the pressure inside the hollow body, which impacts the pressure sensor, is equalized with external environment conditions, and ventilation through the ventilation connection, which is identical to the connection for the inlet of the pressure change into the hollow body, is maintained. According to the embodiment described above, the breathable seal is a membrane which covers the connection into the hollow body and the ventilation connection out from the hollow body. In yet another embodiment, the membrane is waterproof and carries a marking.

According to an example which does not fall within the scope of the claimed invention, the at least one first ventilation hole is designed so that it provides the fluid communication from the hollow body to the ventilation connection. The ventilation connection ends on a left side and on a right side of the housing. In this example a further breathable seal is placed in the ventilation connection and covers the at least one first ventilation hole leading from the hollow body to the ventilation connection. As mentioned above, the further breathable seal can be a breathable and waterproof foam or other suitable materials are thinkable as well. In order to avoid fluid retention inside the ventilation connection (channel), in another an example which does not fall within the scope of the claimed invention, additional ventilation holes are formed on both sides of the further breathable seal. The additional ventilation holes provide the fluid communication from the ventilation connection out of the housing.

With the invention described herein the pressure sensor, positioned in a hollow body of the housing (cavity), is protected from fluid and dust ingress and the ventilation through holes or connections into the hollow body are kept free. Additionally, electronics and the pressure sensor inside the hollow body are protected against high jet water as well.

Same reference numerals refer to same elements or elements of similar function throughout the various figures. Furthermore, only reference numerals necessary for the description of the respective figure are shown in the figures. The shown embodiments represent only examples of how the invention can be carried out. This should not be regarded as a limitation of the invention.

<FIG> is a sectional view of sensor assembly <NUM> according to an embodiment of the present invention. Conveniently, the sensor assembly <NUM> has a housing <NUM> which is formed, for example, by injection moulding of a plastic material (thermoplast or resin). The housing <NUM> has an extending tube connection <NUM> and an electrical connector <NUM> formed thereon. According to the embodiment shown here, a deformable tube <NUM> is mounted to the extending tube connection <NUM>. According to a preferred application of the deformable sensor assembly <NUM> the tube <NUM> is part of a system (not shown) which is used for impact detection in road usage of a vehicle. One detected impact, besides others, it the impact of a pedestrian (not shown) with a vehicle. Preferably, the deformable tube <NUM> is a silicon tube. Preferably, the electrical connector <NUM> includes internal terminals <NUM> which are electrically connected to a logic unit or a printed circuit board <NUM> which is mounted inside the housing <NUM>. A pressure sensor <NUM> is mounted to the lower surface of the printed circuit board <NUM>. The printed circuit board <NUM> is mounted within a hollow body <NUM> of the housing <NUM>.

The formed on extending tube connection <NUM> of the sensor assembly <NUM> is in fluid communication <NUM> with the pressure sensor <NUM> via a connection <NUM>. The fluid communication <NUM> with the hollow body <NUM> takes place via a breathable seal <NUM>. In the embodiment shown here, the breathable seal <NUM> is a breathable and water repellent material (e.g. foam, membrane). The housing <NUM> has formed a ventilation connection <NUM> which is in fluid communication <NUM> with the tube connection <NUM> via at least one first ventilation hole <NUM><NUM> and at least one second ventilation hole <NUM><NUM>. For example, the at least one first ventilation hole <NUM><NUM> connects the tube connection <NUM> with the hollow body <NUM>, and at least one second ventilation hole <NUM><NUM> connects the hollow body <NUM> with the ventilation connection <NUM>. Accordingly, the fluid communication <NUM> is established from the tube connection <NUM> to the ventilation connection <NUM>.

<FIG> shows an enlarged view of the section of <FIG> which is marked with a dashed circle B. The tube connection <NUM> is separated from the ventilation connection <NUM> by the material of the housing <NUM>. The at least one first ventilation hole <NUM><NUM> and the least one second ventilation hole <NUM><NUM> establish the fluid communication <NUM> from the tube connection <NUM> to the ventilation connection <NUM>. A further breathable seal <NUM> covers the least one second ventilation hole <NUM><NUM>. The further breathable seal <NUM> is as well made from a breathable and a water repellent material. The further breathable seal <NUM> prevents dirt, dust and moisture from ingress into the hollow body <NUM> of the housing <NUM>.

<FIG> shows a perspective view of one example of the sensor assembly <NUM>. The housing <NUM> of the sensor assembly <NUM> has a mounting element <NUM>, which is permanently attached to the housing <NUM> by, for example, an injection moulding process. The housing <NUM> has the electrical connector <NUM> formed thereon. Opposite to the electrical connector <NUM>, a breathable seal <NUM> is attached to the housing <NUM>. The breathable seal <NUM> carries a marking <NUM>. According to the example shown here, the breathable seal <NUM> is a membrane.

As shown in the sectional view of <FIG> of the example of the sensor assembly <NUM> of <FIG>, a connection <NUM> into the hollow body <NUM> and a ventilation connection <NUM> out from the hollow body <NUM> are covered by the breathable seal <NUM>. Inside the hollow body <NUM>, the pressure sensor <NUM> is positioned. The hollow body <NUM> of the housing is sealed with a cover <NUM>, which is applied, for example, by a potting process. The cover <NUM>, applied by the potting process, provides resistance to shock and vibration and supports the exclusion of water, moisture, or corrosive agents. In the potting process, the printed circuit board <NUM> (electronic assembly) is placed inside the housing <NUM>. Then the cover <NUM> is attached to seal the hollow body <NUM>. As mentioned already in connection with the embodiment of <FIG>, the electrical connector <NUM> is an injection moulded part of the housing <NUM> and includes internal terminals <NUM> which are electrically connected to the printed circuit board <NUM> in the hollow body <NUM>.

<FIG> shows an enlarged view of the sensor assembly <NUM> of <FIG>, which is marked with a dashed rectangle C. The breathable seal <NUM>, which optionally is a membrane, covers the connection <NUM> into the hollow body <NUM> and a ventilation connection <NUM> out from the hollow body <NUM>. The breathable seal <NUM> allows a fluid communication <NUM> into the hollow body <NUM> and a fluid communication <NUM> out of the hollow body <NUM>. Consequently, a pressure change outside of the hollow body <NUM> can reach the pressure sensor <NUM> inside the hollow body <NUM>. Thereby, the ingress of moisture, dirt or water hollow body <NUM> of the housing is avoided.

<FIG> shows a perspective view of a further example of the sensor assembly <NUM>.

The tube connection <NUM> with the deformable tube <NUM> mounted thereon and the electrical connector <NUM>, formed with the housing <NUM>, are arranged perpendicular to each other. The deformable tube <NUM> is mounted to the tube connection <NUM> for example with a cable strap <NUM>. The ventilation connection <NUM> extends across the housing <NUM> from a left side <NUM> to a right side <NUM> of the housing <NUM>.

<FIG> shows a perspective sectional view along the cutting line A-A of the example of the sensor assembly <NUM> shown in <FIG>. Here a further breathable seal <NUM> is placed in the ventilation connection <NUM>. Thereby the further breathable seal <NUM> covers the at least one second ventilation hole <NUM><NUM> which provide the fluid communication <NUM> leading from the hollow body <NUM> to the ventilation connection <NUM>. The breathable seal <NUM>, arranged in relation with the connection <NUM> into the hollow body <NUM>, and the further breathable seal <NUM> are, for example, breathable and waterproof foams.

As shown in <FIG>, the ventilation connection <NUM> has formed at least one additional ventilation hole <NUM> on each side of the further breathable element <NUM>. The additional ventilation holes <NUM> connect the ventilation connection <NUM> with the ambient air. The additional ventilation holes <NUM> help to avoid fluid retention in the ventilation connection <NUM>. As shown in <FIG>, the housing <NUM> is closed with a cover <NUM>, which is applied, for example, by a potting process.

<FIG> shows a sectional view of a sensor assembly <NUM> according to a further embodiment of the present invention. <FIG> shows an enlarged view of the section of <FIG> which is marked with a dashed rectangle D. In this embodiment and the embodiment shown in <FIG>, the tube connection <NUM> and the ventilation connection <NUM> are arranged in a <NUM>° orientation, in one line, with respect to each other. There is no direct fluid communication between the tube connection <NUM> and the ventilation connection <NUM>. The deformable tube <NUM> is mounted to the tube connection <NUM> with a cable strap <NUM> or the like. The printed circuit board <NUM> with the mounted pressure sensor <NUM> is positioned in the housing <NUM>. The housing <NUM> is closed with a cover <NUM>, which is applied, for example, by a potting process.

The enlarged view of <FIG> shows the position of the further breathable seal <NUM> in the ventilation connection <NUM>. The further breathable seal <NUM> is positioned such that it covers the at least one second ventilation hole <NUM><NUM> from the hollow body <NUM> to the ventilation connection <NUM>. Additionally, the further breathable seal <NUM> can abut against a separation wall <NUM> between the tube connection <NUM> and the ventilation connection <NUM>. As mentioned in the embodiment disclosed in <FIG>, the breathable seal <NUM> (see <FIG>) is placed in the connection <NUM> leading to the hollow body <NUM>. The further breathable seal <NUM> is for example a breathable and waterproof material.

Claim 1:
A sensor assembly (<NUM>) comprising:
a housing (<NUM>) defining a hollow body (<NUM>),
a formed connection (<NUM>) defining a fluid communication (<NUM>) from outside of the hollow body (<NUM>) into the hollow body (<NUM>),
a printed circuit board (<NUM>) placed in the hollow body (<NUM>), wherein the printed circuit board (<NUM>) carries a pressure sensor (<NUM>), and
a ventilation connection (<NUM>);
a breathable seal (<NUM>) placed such that in relation to the connection (<NUM>), the fluid communication (<NUM>) has to pass the breathable seal (<NUM>) prior to reaching the pressure sensor (<NUM>);
at least one first ventilation hole (<NUM><NUM>) providing the fluid communication (<NUM>) from the connection (<NUM>) to the hollow body (<NUM>), and at least one second ventilation hole (<NUM><NUM>) providing the fluid communication (<NUM>) from the hollow body (<NUM>) to the ventilation connection (<NUM>); and
a further breathable seal (<NUM>) covering the at least one second ventilation hole (<NUM><NUM>) leading from the hollow body (<NUM>) to the ventilation connection (<NUM>).