Patent Description:
Camera devices of a vision system for a motor vehicle are usually protected by a metal housing. The housing should not only give a protection against mechanical stress or damage, but also shield against electromagnetic waves. However, when the housing is put together by two or more housing parts, the Faraday cage built by the housing parts may have gaps at the connection surfaces of the housing parts. In such case electromagnetic waves could penetrate into the housing and cause a malfunction of the electrical components inside the housing. Also, electromagnetic waves originating from the electrical components inside the housing could penetrate to the exterior of the housing and cause malfunctions of other electrical devices in the motor vehicle.

<CIT> discloses a housing according to the preamble of claim <NUM>.

The problem underlying the present invention is to provide a fail-safe Faraday cage giving a better protection and shielding against electromagnetic waves for electrical components inside and outside the housing.

The invention solves this object with the features of the independent claims. Cooperating first and second metal housing parts each have circumferential connection surfaces and the metal housing parts are designed to be connected to each other along the connection surfaces such that said circumferential connection surfaces lie face to face to each other in the connected state of the housing parts. According to the invention, at least one of the housing parts comprises a plurality of cutting elements protruding from the corresponding circumferential connection surface. At least a part of the cutting elements has an oversize with respect to the other circumferential connection surface, such that said cutting elements cut into the other circumferential connection surface during connection of the housing parts. The cutting elements are distributed over the circumference of the circumferential connection surface. The cutting elements of the invention generate metal to metal contact points distributed over the circumference of the circumferential connection surface, and thus close the Faraday cage built by the housing parts, bridging the gap between the first and the second housing part so that no electromagnetic waves can penetrate into or out from the housing.

In order to achieve a good fit between the first and the second metal housing part, the circumferential connection surfaces of the first and the second housing parts are advantageously oriented parallel to the connection direction, so that the connection can be achieved by a simple translational motion.

According to the invention, the cutting elements have a longitudinal axis oriented parallel to the connection surfaces of the first and the second metal housing part. In this case there is no lateral force pushing one of the metal housing parts away from the connection direction and a fixing of both housing parts by a simple translational motion is possible.

According to the invention, the cutting elements are tapering in the connection direction in a view onto the corresponding circumferential surface. Therefore a force during the connecting process increases when the first and the second metal housing part are connected, so that the connecting process can be reliably controlled.

According to the invention, the cutting elements are arranged with a distance to a front edge of the corresponding metal housing part which comes first into contact with said other metal housing part during the connection of the housing parts. As a result, the edge of the one metal housing part can be used as a centering means during connecting both metal housing parts, which eases the connecting process.

According to the invention, a front part of said cutting elements has an undersize with respect to the other circumferential connection surface. Therefore the front part of the cutting elements will fit easily in the other metal housing part. The connection will be strengthened when a back part of the cutting elements on one of the metals housing parts provide an advantageous press-fit with the circumferential connection surface of the other metal housing part.

In a preferred embodiment of the invention at least one of the metal housing parts has a planar surface so that the cutting elements on one of the metal housing parts can scratch or cut into said planar surface of the other metal housing part.

Preferably the housing parts are made of aluminum. Aluminum has a comparably light weight and a high electrical conductivity and is therefore a preferred material for the housing parts. More preferably the housing parts are made of die-cast aluminum as a die cast process allows to build a complex geometry on the housing parts including the circumferential connection surfaces as well as the cutting elements. The manufacturing tolerances of a die-cast aluminum are sufficient to reach the tolerances for components such as housings.

According to the invention, tapering of the cutting elements avoids high forces in the first state of the connection process. The oversize of the rear part of the cutting elements with respect to the circumferential connection surface of the second metal housing part allows a safe and reliable press-fitting when the rear part of the cutting elements cut into the surface of the other housing part. The surface of the cutting elements should have a relatively small angle with the longitudinal axis through the cutting elements to avoid high forces when the housing parts are connected. To build up a fail-safe Faraday cage the length of the cutting elements is preferable between <NUM> and <NUM>, more preferable between <NUM> and <NUM>.

In a preferred embodiment of the invention the cutting elements are spaced from each other by a distance of not more than <NUM>, preferably not more than <NUM>, more preferably not more than <NUM>. A highly efficient Faraday cage protects against high-frequency alternating fields, because on the surface of the cage eddy currents are induced which counteract the external field. The shielding effect is in this case characterized by finite shielding attenuation and penetration into the housing so that the electronic components inside the housing are protected. Smaller distances between the cutting elements are generally preferred as the penetration gets smaller and the shielding effect more reliable.

According to the invention, the cutting elements have a maximum thickness which is larger than a gap between the circumferential connection surfaces in the connected stated of the metal housing parts. Therefore the cutting elements fit into the other housing part with a press-fitting, scratching or cutting action into the circumferential connection surface, thus penetrating any passivation layer of an aluminum housing part. Herein, the thickness of the cutting elements is measured in a non-connected state of the housing parts.

According to the invention the cutting elements are spike-shaped. Such shape is to cut into the other housing part, penetrate a passivation layer and build up a Faraday cage.

In the following the invention shall be illustrated on the basis of preferred embodiments with reference to the accompanying drawings, wherein:.

<FIG> shows a housing <NUM> for enclosing at least one electronic component of a motor vehicle, such as one or more camera modules not shown in the figures. The housing <NUM> comprises a first metal housing part <NUM> with a first circumferential connection surface <NUM> and a second metal housing part <NUM> with a second circumferential connection surface <NUM>. The circumferential connection surfaces <NUM>, <NUM> of the metal housing parts <NUM>, <NUM> are planar surfaces. The first metal housing part <NUM> and the second metal housing part <NUM> are designed to be connected to each other along a connection direction <NUM> such that the circumferential connection surfaces <NUM>, <NUM> lie face to face to each other in a connected state of those metal housing parts <NUM>, <NUM>.

The first metal housing part <NUM> comprises a plurality of cutting elements <NUM> protruding from the planar surface of the circumferential connection surface <NUM>. The cutting elements <NUM> are arranged with a distance to a front edge <NUM> of the first metal housing part <NUM>. The cutting elements <NUM> have a length of <NUM> to <NUM>, preferably between <NUM> to <NUM>. Each cutting element has a front part <NUM>, a rear part <NUM> and may have a straight part <NUM>. The front part <NUM> has an undersize with respect to the circumferential connection surface <NUM> of the second metal housing part <NUM> and the rear part <NUM> has an oversize with respect to the circumferential connection surface <NUM> of the second metal housing part <NUM>. The straight part <NUM> can also have an oversize with respect to the circumferential connection surface <NUM>.

The cutting elements <NUM> are equally spaced along the circumferential connection surfaces <NUM>, <NUM>, preferably by a distance of not more than <NUM>, preferably not more than <NUM>, more preferably not more than <NUM> relative to each other. The cutting elements <NUM> have a spike-shape.

The connection direction <NUM> is shown with arrows alongside the both metal housing parts <NUM>, <NUM> in <FIG>. The numbers <NUM> to <NUM> relate to different states of the connection process, starting from a non-connected state <NUM> to a fully connected state <NUM>. In state <NUM> the front edge <NUM> of the first metal housing <NUM> dives into the second metal housing part <NUM> and there is no contact, as the front edge <NUM> of the first metal housing part <NUM> has an undersize with respect to a collar <NUM> of the second metal housing part <NUM>. In state <NUM> the front parts <NUM> of the cutting elements <NUM> dive into the collar <NUM> of the second metal housing part <NUM> until the cutting elements <NUM> get in touch with the connection surface <NUM> of the second metal housing part <NUM>. In state <NUM> the rear part <NUM> of the cutting elements <NUM> cut into the connection surface <NUM> of second metal housing part <NUM>. Following state <NUM> the straight part <NUM> of the cutting elements <NUM> come into press-fit contact with the connection surface <NUM> until a fully connected state <NUM> is reached.

<FIG> shows the housing <NUM> with the first metal housing part <NUM> and the second metal housing part <NUM> in a fully connected state corresponding to level <NUM> in <FIG>, wherein at least the rear parts <NUM> and, if present, the straight parts <NUM> of the cutting elements <NUM> have an oversize with respect to the circumferential connection surface <NUM> of the second housing part <NUM>.

The circumferential connection surfaces <NUM>, <NUM> are orientated parallel to the connection direction <NUM> of the metal housing parts <NUM>, <NUM>. The first metal housing part <NUM> and the second metal housing part <NUM> provide a press fitting along the cutting elements <NUM> when both metal housing parts <NUM>, <NUM> are connected to each other. The metal housing parts <NUM>, <NUM> thus build a Faraday cage along the circumferential connection surfaces <NUM>, <NUM>, such that the cutting elements <NUM> close a gap between the two metal housing parts <NUM>, <NUM>. A maximum thickness of the cutting elements <NUM> is larger than a gap between the circumferential connecting surfaces <NUM>, <NUM> in the connected state of the first metal housing part <NUM> and the second metal housing part <NUM>.

The metal housing parts <NUM>, <NUM> not only provide mechanical protection but also shielding against electromagnetic waves to electronic components inside and outside the housing <NUM>. The cutting elements <NUM> have a longitudinal axis <NUM> which is orientated parallel to the connection direction of the two housing parts <NUM>, <NUM>. The cutting elements <NUM> are tapering in the connection direction in a view onto the corresponding circumferential connection surface <NUM> and in a view along the corresponding circumferential connection surface <NUM>.

The metal housing parts <NUM>, <NUM> are made of an electrical conductive material such as aluminum, preferable die-cast aluminum, and built in a casting process. Therefore the metal housing parts <NUM>, <NUM> and the cutting elements <NUM> are advantageously made from the same material.

<FIG> show different views of a practical embodiment of a first housing part <NUM>. The first metal housing part <NUM> has an opening <NUM> for receiving a camera module, and ribs <NUM>, such as cooling ribs or reinforcing ribs. The first metal housing part <NUM> has a circumferential connection surface <NUM> with a planar base. A plurality of cutting elements <NUM> is distributed over the circumference of said circumferential connection surface <NUM> and protrudes from said planar base. The cutting elements <NUM> are equidistantly spaced over the circumference of the connection surface <NUM>, with a distance of <NUM> to <NUM> between one cutting element <NUM> and an adjacent cutting element <NUM>. The first housing part <NUM> has a preferably circumferential flange <NUM>, which can be used as a stop surface <NUM> when the first housing part <NUM> and the second housing part <NUM> are connected.

The detail F of <FIG> shows an enlarged view onto one of the cutting elements <NUM>. The cutting element <NUM> is tapering and has a front part <NUM> with is smaller and thinner than a rear part <NUM>. The detail F also shows an enlarge view onto the flange <NUM> and the stop surface <NUM>. Therefore the level of the fully connected state <NUM> can also lie on a level, where a front edge of the second housing part <NUM> gets in contact with the stop surface <NUM> of the flange <NUM> of the first housing part <NUM>.

<FIG> shows an enlarged cross sectional view of the first metal housing part <NUM>. As shown in <FIG> the cutting element <NUM> is distanced from the front edge <NUM> of the first metal housing part <NUM> and has a front part <NUM>, a rear part <NUM> and a straight part <NUM>. The straight part <NUM> extends to the preferably circumferential flange <NUM>, so the stop surface <NUM> can build a stop for the front edge of the second housing part when the two housing parts <NUM>, <NUM> are connected in the connection direction <NUM>.

When the housing <NUM> is mounted the first metal housing part <NUM> and the second metal housing part <NUM> are connected along a connection direction, the circumferential connection surfaces <NUM>, <NUM> being oriented parallel to the connection direction. When the front edge <NUM> of the first housing part <NUM> dives into a collar <NUM> of the second housing part <NUM> there is a gap between those two housing parts <NUM>, <NUM>. The front parts <NUM> of the cutting elements <NUM> on the circumferential connection surface <NUM> of the first metal housing part <NUM> have an undersize with respect to the other circumferential connection surface <NUM> of the second metal housing part <NUM>. Due to the tapered shape of the cutting elements <NUM> and the fact that the cutting elements <NUM> have a thickness that is larger than the gap between the two metal housing parts <NUM>, <NUM> in a connected state, the rear part <NUM> of each cutting element <NUM> scratches or cuts into the other circumferential connection surface <NUM>. The cutting elements <NUM> thus penetrate a passivation layer on the aluminum of the second metal housing part <NUM>. Furthermore, when the two metal housing parts <NUM>, <NUM> are connected in the fully connected state, the straight parts <NUM> of the cutting elements <NUM> are in press-fit contact with the connection surface <NUM> of the second metal housing part <NUM> and thus form a tight connection of the two metal housing parts <NUM>, <NUM>. The stop surface <NUM> can assist in a connection process so that the fully connected state <NUM> is not only defined by a force for the press fitting connection but also by a defined stop.

Claim 1:
A housing (<NUM>) for enclosing at least one electronic component of a motor vehicle, comprising at least a first metal housing part (<NUM>) with a first circumferential connection surface (<NUM>) and a second metal housing part (<NUM>) with a second circumferential connection surface (<NUM>), wherein said metal housing parts (<NUM>, <NUM>) are designed to be connected to each other along a connection direction such that said circumferential connection surfaces (<NUM>, <NUM>) lie face to face to each other in the connected state,
wherein at least one of the housing parts (<NUM>) comprises a plurality of cutting elements (<NUM>) protruding from the corresponding circumferential connection surface (<NUM>), wherein at least a part of said cutting elements (<NUM>) have an oversize with respect to said other circumferential connection surface (<NUM>), such that said cutting elements (<NUM>) cut into said other circumferential connection surface (<NUM>) during connection of the housing parts (<NUM>, <NUM>), wherein said plurality of cutting elements (<NUM>) are distributed over the circumference of said circumferential connection surfaces (<NUM>, <NUM>),
wherein said cutting elements (<NUM>) have a longitudinal axis (<NUM>) oriented parallel to said connection direction,
wherein the cutting elements (<NUM>) have a maximum thickness which is larger than a gap between the circumferential connection surfaces (<NUM>, <NUM>) in the connected state of the housing parts (<NUM>, <NUM>),
wherein said cutting elements (<NUM>) are arranged with a distance to a front edge (<NUM>) of the corresponding housing part (<NUM>) which comes first into contact with said other housing part (<NUM>) during the connection of the housing parts (<NUM>, <NUM>),
and each cutting element has a front part (<NUM>) and a rear part (<NUM>), the front part (<NUM>) has an undersize with respect to the circumferential connection surface (<NUM>) of the second metal housing part (<NUM>) and the rear part (<NUM>) has an oversize with respect to the circumferential connection surface (<NUM>) of the second metal housing part (<NUM>),
wherein the cutting elements (<NUM>) are tapering in the connection direction in a view along the corresponding circumferential connection surface (<NUM>),
characterized in that
the cutting elements (<NUM>) are tapering in the connection direction in a view onto the corresponding circumferential connection surface (<NUM>) and the cutting elements (<NUM>) have a spike-shape.