Patent Description:
High-voltage junction boxes usually connect an external power source to the vehicle battery in a charging event, in particular in a DC-charging event. They comprise a contactor, which might be a relay and which can couple and decouple the external power source and the vehicle battery. In case of an overvoltage, the contactor serves to disconnect the charger from the battery to prevent damage to electronic components.

Typically, the contactor is fixed to a housing of the junction box by means of screws. However, the tolerances of the contactor and other elements of the junction box, in particular of a connector and a bus bar, are comparatively large. This may result in considerable gaps between e.g. the housing and the mounting surface of the contactor and therefore in high tensions applied to the connector. These tensions can be passed on to the connector, which is mechanically and electrically connected to the contactor by the bus bar.

While some of these tolerances may be balanced during the assembly, it is not always possible to compensate tolerances in the case of a repair. The contactor is a rather vulnerable component, which might be replaced during the lifetime of the vehicle. In this case, the replacement contactor may have dimensions differing from those of the original one due to manufacture tolerances by several millimetres. These tolerances cannot be balanced without applying tension to the contactor, the bus bar and the connector.

Document <CIT> discloses a power electronics assembly for a mobile application including a first power electronics component selectively coupled to a high source on a first side and coupled to a high voltage battery on a second side, a second power electronics component selectively coupled to one of a low load or a low voltage battery on a first side and coupled to the high voltage battery on a second side; and a controller, including an operating mode circuit structured to determine a discharge operating mode for the mobile application, a power electronics configuration circuit structured to provide a switch state value for the first power electronics component and the second power electronics component in response to the discharge operating mode, and wherein the first power electronics component and the second power electronics component are responsive to the switch state value to coupled selected ones of the high source, low load, and low voltage battery to the high voltage battery.

Document <CIT> discloses a fixing structure including an attaching portion, a nut, and a spacer. The attaching portion has an attaching hole through which an attaching bolt provided to a vehicle body is inserted. The nut fixes the attaching portion to the vehicle body by being tightened to the attaching bolt with a washer interposed between the nut and the attaching portion.

It is therefore an object of the present invention to provide a high-voltage junction box for an electrically driven vehicle, in which components such as the contactor are easily replaceable without damage to other components.

This object is achieved by means of the high-voltage junction box according to the independent claim.

Advantageous embodiments and developments are objects of the dependent claims.

According to the invention, a high-voltage junction box for an electrically driven vehicle is provided, comprising a housing part with at least one mounting hole. The junction box further comprises a contactor with a through-hole, the contactor is mechanically connected to the housing part by at least one fastening element extending through the through-hole into the mounting hole. The junction box further comprises at least one bus bar having a first contact area and the second contact area, wherein the first contact area is electrically and mechanically connected to the contactor and the second contact area is electrically and mechanically connected to a connector or another component. A tolerance compensation element suitable to compensate for tolerance variations (size variations, dimension variations) in the distance between the housing element and the contactor is provided and mounted in the at least one mounting hole.

The high-voltage junction box has the advantage, that mounting a tolerance compensation element in the mounting hole and therefore between the housing and the contactor, makes it possible to balance tolerances (variations in size or dimensions) of the contactor with respect to the housing. The result is a fixed position of the contactor, in particular of some of its surfaces, with respect to the housing.

The position of the bus bar, which might be mechanically and electrically connected to an upper side of the contactor, is therefore fixed with respect to the housing and independent of tolerances of the contactor. Therefore, no tensions will be induced in the bus bar and the connector or the other component when the contactor is replaced, even if the new component has different dimensions.

The housing part is a part of the housing of the junction box. The housing may be in one part or may have several parts joined together.

A bus bar is a strip for high current power distribution in an electric vehicle and usually comprises copper, steel and/or aluminium. The bus bar usually does not comprise an insulating coating but is self-supporting or supported by insulated pillars and may be effectively cooled by air or another coolant. In a junction box, the bus bar transmits power from an external source via the contactor to a connector or to another high voltage electric component, e.g. a power measuring unit.

According to the invention, the mounting hole extends into a tubular hollow protrusion of the housing part. The tubular hollow protrusion may be formed to accommodate the fastening element, preferably a screw, and the tolerance compensation element.

Tolerance compensation elements are known in the art. There are different types of tolerance compensation elements which might differ e.g. in the way they are fixed in the mounting hole. Typically, they comprise a left-hand thread on their outer side and a frictional connection element for establishing a frictional connection between the tolerance compensation element and the screw.

According to an embodiment, the tolerance compensation element can be placed in the mounting hole during the assembly. Subsequently, the contactor is placed in its mounting position with respect to the housing part, in which the through-hole is aligned with the mounting hole in the housing part. In this position, a screw can be placed in the through-hole extending into the mounting hole with the tolerance compensation element. While the screw is being screwed in, the tolerance compensation element is screwed out due to its left-hand thread and due to the frictional connection between the tolerance compensation element and the screw.

The tolerance compensation element is screwed out of the mounting hole until it is in contact with the contactor. Subsequently, the forces exerted by the screw via the contactor on the tolerance compensation element are larger than the frictional forces of the frictional connection and the screw can be screwed in with a suitable tightening torque.

The result is a connection between the contactor and the housing part free from distortion.

According to an embodiment of the invention, the tolerance compensation element includes a shoulder (collar) facing outwards from the mounting hole, the shoulder extending radially over an edge of the mounting hole, wherein the shoulder is in contact with the perimeter region of the through-hole when the contactor is connected to the housing part. According to this embodiment, the shoulder contacts the contactor when the screw has been partially screwed in and the tolerance compensation element has been screwed out to a maximum extent.

According to an embodiment, the contactor comprises two mounting ears, each having a through-hole for mechanically connecting the contactor to the housing part. The mounting ears provide a position for the through holes. If the contactor housing is made of a plastic material, a metal bushing may be provided in the mounting ears and the through-hole may be positioned in the bushing in order to provide a reliable and robust connection between the contactor and housing.

According to an aspect of the invention, the bus bar has a heat dissipation area arranged between the first contact area and the second contact area, the heat dissipation area being in thermal contact with a cooling element.

The advantage is that the bus bar, which will be heated by high currents during charging, maybe cooled effectively. A heat conducting paste may be placed between the heat dissipation area of the bus bar and the cooling element. While the heat conducting paste is soft during the first assembly, it may harden over time and is typically not ductile when the contactor has to be replaced at a later time. Therefore, the tolerance compensation between the contactor and the housing is advantageous for an effective cooling of the bus bar as well not allowing the movement of the busbar and the avoiding the risk of detaching from the cooling surface.

According to an aspect of the invention, an electrically driven vehicle is provided with a charging unit comprising the above described high voltage junction box.

Further advantages, advantageous embodiments and developments of the junction box will become apparent from the exemplary embodiments which are described below in association with schematic figures.

<FIG> shows a part of a high-voltage junction box <NUM> for an electrically driven vehicle. The junction box <NUM> comprises a housing, of which a housing part <NUM> is shown. The junction box <NUM> further comprises a contactor <NUM> for coupling an external power source to a vehicle battery and decoupling it in case of an overvoltage. The junction box <NUM> further comprises a connector <NUM> for the connection to the vehicle battery and a bus bar <NUM> for the electrical connection of the contactor <NUM> and the connector <NUM>. Typically, the junction box further comprises a second bus bar which is not shown here. Hence, the junction box <NUM> connects the vehicle battery to an external charging device, the contactor <NUM> being placed towards the external charging device and the connector <NUM> towards the battery.

The contactor <NUM> is fixed to the housing part <NUM> by means of two screws <NUM>. The bus bar <NUM> is fixed to the contactor <NUM> by means of a screw <NUM> and to the connector <NUM> by means of a screw <NUM>.

The contactor <NUM> has comparatively large tolerances. Its mounting between the housing part <NUM> on one hand and the bus bar <NUM> on the other hand might therefore lead to tensions which might damage the connector <NUM> and/or weaken the electrical and thermal contacts. Therefore, tolerance compensation elements <NUM> are used to compensate tolerance variations of the contactor <NUM>.

The mounting of the tolerance compensation elements <NUM> is described with respect to the <FIG>. The contactor <NUM> has two mounting ears <NUM>, which protrude from opposite sides of the contactor <NUM>. Each mounting ear <NUM> has a bushing <NUM> with a through-hole <NUM> to accommodate the screw <NUM>. The housing part <NUM> has two mounting holes <NUM> to accommodate the screws <NUM>. The mounting holes <NUM> are allocated in a tubular hollow protrusion <NUM> of the housing part <NUM> which can be best seen in <FIG>. The screw <NUM> has a right-hand thread.

The tolerance compensation element <NUM> is essentially cylindrical with an inner side and an outer side and has a shoulder <NUM> extending radially outwards from the end of the tolerance compensation element <NUM> facing towards the contactor <NUM>. The tolerance compensation element <NUM> includes a left-hand thread on its outer side <NUM> and a through-hole on its inner side.

This is shown in more detail in the detailed view of <FIG>, which shows one exemplary embodiment with a suitable tolerance compensation element known in the art. However, other tolerance compensation elements of a different design may be used instead. On its inner side, the housing <NUM> has a right-hand thread <NUM> interacting with the right-hand thread of the screw <NUM>.

The tolerance compensation element <NUM> has at least one frictional connection element <NUM> on its end and facing away from the contactor <NUM>. In the embodiment shown in <FIG>, the frictional connection element <NUM> is formed by a number of axial projections which are preloaded to be pressed against the screw <NUM>.

During the assembly of the junction box <NUM>, the contactor <NUM> is placed in its mounting position on the housing part <NUM>, where the through-holes <NUM> are aligned with the mounting holes <NUM>. A tolerance compensation element <NUM> is placed in each mounting hole <NUM>. Subsequently, a screw <NUM> is inserted into each through-hole <NUM> and screwed in to extend into the mounting hole <NUM> with the tolerance compensation element <NUM>. When the screw <NUM> is screwed in, a frictional connection between the screw <NUM> and the tolerance compensation element <NUM> is established by means of the frictional connection element <NUM>.

When the screw <NUM> is screwed in further, the tolerance compensation element <NUM> is screwed out. The tolerance compensation element <NUM> is screwed out while the screw <NUM> is screwed in until the shoulder <NUM> of the tolerance compensation element <NUM> contacts an underside of the contactor <NUM>.

When the screw <NUM> is screwed in further, the vertical force exerted by the underside of the contactor <NUM> on the tolerance compensation element <NUM> exceeds the frictional force between the tolerance compensation element <NUM> and the screw <NUM> and the frictional connection between those is broken. Consequently, the tolerance compensation element <NUM> is no longer fixed with respect to the screw <NUM> and the screw <NUM> can be screwed in further up to an end position. When this position is reached, a distance D might remain between the housing part <NUM> and the contactor <NUM>, the distance D depending on the tolerances (size variations, dimension variations) of the contactor <NUM>. Due to the tolerance compensation element <NUM>, there is a stable connection between the contactor <NUM> and the housing <NUM>.

Claim 1:
High-voltage junction box (<NUM>) for an electrically driven vehicle, comprising
- a housing part (<NUM>) with at least one mounting hole (<NUM>);
- a contactor (<NUM>) with a through-hole (<NUM>), the contactor (<NUM>) being mechanically connected to the housing part (<NUM>) by at least one fastening element extending through the through hole (<NUM>) into the mounting hole (<NUM>);
- a bus bar (<NUM>) having a first contact area and a second contact area, wherein the first contact area is electrically and mechanically connected to the contactor (<NUM>) and the second contact area is electrically and mechanically connected to a connector (<NUM>);
wherein a tolerance compensation element (<NUM>) suitable to compensate for tolerance variations in the distance between the housing element (<NUM>) and the contactor (<NUM>) is provided in the at least one mounting hole (<NUM>) wherein the mounting hole (<NUM>) extends into a tubular hollow protrusion (<NUM>) of the housing part (<NUM>).