Patent Description:
In one current approach automotive electronic control units, ECU, are being replaced by more complex domain control units, DCU, or, increasingly frequently, multi-domain control units, MDC. Both types of control units or simply controllers are devices designed to support and control various functional domains of a vehicle, like advanced driver assistance systems, ADAS, or infotainment systems. The DCUs are typically less complex devices, developed to operate in a single domain, while MDCs control functionalities from more than one domain. A DCU/MDC controller of different functionalities can be replaced in a vehicle, simply by plugging-in and -out the device from a car, similarly as blades are replaced in a server rack. Such physical replacement of a control unit offers not only new/updated functions to the vehicle, but also new hardware capabilities, such as, increased computing power, by using more efficient logical components, increased system memory capacity, by replacing memory components, improved energy distribution system, by using newer generation of electronic components, and more. With the increased computing power, additional heat is generated from the controllers as a result of this increase which requires additional thermal management to account for the additional heat output. Plugging-in and -out the device from a car may expose the device to damage when being plugged-in and -out. Accordingly, there is a need to address the above issues and problems with current replacement electronic control units, ECU, with domain control units, DCU, or multi-domain control units, MDC and to provide an alternative and improved rack assembly having an improved mounting arrangement for mounting trays for plug-in automotive type control units that addresses the problems with previous set-ups. Reference is made to <CIT> cited as exemplary of the state of the art.

The scope is in accordance with the appended claims.

The specification aims to provide an improved arrangement for coupling control units to a vehicle system, according to the embodiments described and claimed in the attached claims.

According to a first aspect, there is provided a rack assembly unit (<NUM>, <NUM>) for mounting a control unit (<NUM>) to a vehicle rack system (<NUM>), the rack assembly (<NUM>) comprising:.

The arrangement of the rack assembly unit advantageously provides for ease of location of a control unit in the vehicle system while also avoiding any unwanted forces on the components. The rack assembly unit is configured such that at the first open position, the tray is located at a lower position in the vertical direction relative to the rack chassis and a clearance space is provided between the control unit located in the tray and a cold plate located on the rack chassis. The cold plate is coupled to a cooling system. At the second closed position, the tray is located at an upper position relative to the rack chassis and the control unit and the cold plate are thermally coupled. The arrangement provides that a heat transfer surface of the control unit is positively engaged with a heat transfer surface of the cold plate to define a thermal interface, which supports cooling of electronic components located in the control unit. The rack chassis and tray coupled together to define a housing and support for the control unit. In one arrangement, the rack chassis comprises first and second side walls (<NUM>, <NUM>) connected by a rear wall (<NUM>) and having a front opening (<NUM>); the tray (<NUM>) comprising first and second side walls (<NUM>, <NUM>) connected by a rear wall (<NUM>) and having a front opening (<NUM>) and a base portion (<NUM>). The tray is movably coupled to the rack chassis such that it is located within the rack chassis in the upper closed position and movable relative to the rack chassis to the lower open position.

In one arrangement the rack assembly unit further comprises a fixing mechanism for fixing the tray in the closed position, the fixing mechanism and rack assembly configured such that when tray is fixed in the closed position at the fixing mechanism, the control unit is located in contact with the cold plate to define a thermal interface therebetween, and a controlled contact force is applied between the control unit and the cold plate.

The rack assembly is configured to provide for generation of a contact force at a thermal interface between the control unit and the cold plate when the fixing mechanism is engaged. The rack assembly unit is essentially configured to provide for the controlled application of forces between the control unit and components including the tray, chassis and cold plate, including by virtue of the arrangement of the fixing mechanism. As the fixing mechanism is engaged, a controlled force is applied between the control unit and cold plate. The controlled force arising from the interaction of the fixing mechanism with the components of the rack assembly.

According to one arrangement, the control unit when located at the at the control unit operating position is further electrically and/or communicatively coupled via the rack assembly with the vehicle system (<NUM>).

According to another arrangement, the control unit has at least one connector (<NUM>) comprising an electrical and/or communication connector and the rack assembly unit comprising a corresponding header (<NUM>) and a backplane connector (<NUM>) for coupling the control unit to the backplane board.

In one arrangement, the connector of the control unit may comprise a plug-in connector receivable at the header of the tray when the control unit is inserted into the tray. From that single connection to the header, the control unit is further directly coupled to the backplane board (<NUM>) of the vehicle system. This electrical and communicative coupling is provided via the header (<NUM>) and a backplane connector (<NUM>). Taking account of the corresponding features and form of the tray and control unit - the insertion of the control unit is done as a simple plug-in insertion. Effectively the rack assembly unit can be considered as acting as an adaptor between the control unit and the vehicle system. The control unit is directly coupled to the backplane board via the rack assembly unit.

In one arrangement, the rack chassis (<NUM>) comprises a cold plate support (<NUM>) for receiving and supporting a cold plate (<NUM>), and the rack assembly unit (<NUM>, <NUM>) configured such that when the tray (<NUM>) is located in the lower open position, the control unit located in the tray does is spaced apart from the cold plate, and when the tray is located in the upper closed position the control unit in the tray is located such that a heat transfer surface of the control unit is thermally coupled to a heat transfer surface of the cold plate to form a thermal interface (<NUM>) therebetween.

In one arrangement, the cold plate receiver is configured such that a cold plate is supported at an upper portion of the rack assembly relative to the tray and the control unit. The arrangement and features of the rack chassis, tray and control unit, are optimized and configured such that when the rack assembly unit is fixed in the upper closed position, the resulting interactions and forces between the rack chassis, tray and the control unit result in the provision of a controlled force at the interface between the control unit and the cold plate. Advantageously, this engagement of the cold plate and control unit defines a thermal interface between them at which the two components are thermally coupled. Heat transfer from the control unit to the cold plate. The controlled force provided results in a positive engagement and coupling of the cold plate to the control unit at the thermal interface and across the area of overlap of each of the components. The occurrence of air gaps, for example, is reduced by the application of the force. Further a consistent force is maintained across the thermal interface and thus a consistent coupling. As noted from the description and the drawing the thermal interface is formed between that portion of the control unit at which the electronic components that require cooling are located.

In one arrangement, the rack chassis (<NUM>) has first and second side walls (<NUM>, <NUM>), wherein the cold plate support is defined by first and second recesses (<NUM>) formed at a top edge surface (<NUM>-<NUM>, <NUM>-<NUM>) of each of the side walls, wherein the recesses (<NUM>) of the support are located opposite to each other, such that in use the cold plate is arranged extending between the first and second recesses (<NUM>) and over a portion of the control unit located in tray.

In one arrangement, when the control unit is located in the operating position a thermal interface material, TIM (<NUM>), is provided between the control unit (<NUM>) and the cold plate (<NUM>) such that a heat transfer surface of the control unit and a heat transfer surface of the cold plate are thermally coupled via said TIM.

Advantageously, the provision of a TIM layer further promotes heat transfer at the thermal interface and provides for improved thermal coupling.

The control unit (<NUM>) comprises a housing (<NUM>) which comprises a TIM receiver portion (<NUM>) for receiving the TIM (<NUM>) in the form of a TIM layer <NUM>, wherein the TIM receiver portion (<NUM>) may be defined by a recessed groove (<NUM>) formed in an upper surface of the control unit, the recessed groove defining a periphery of the TIM receiver portion (<NUM>) and having a shape generally corresponding to that of the cold plate, and wherein an O-ring (<NUM>) is located in the recessed groove surrounding the TIM receiver portion.

Advantageously, the arrangement of the TIM receiver comprising a seal - provides together with the control unit and the cold plate for a leakproof TIM receiver at the interface between the cold plate and the control unit. As noted above when the control unit is thermally coupled to the cold plate, forces are exerted between the control unit and the cold plate, and the seal is engaged with a corresponding surface of each of the cold plate and the control unit housing. The TIM (<NUM>) may further comprise a phase change TIM. The use of a phase change TIM is supported by the sealed arrangement.

In one arrangement, the coupling mechanism comprises a hinge mechanism (<NUM>),
wherein the tray and rack chassis are coupled at a rear portion of the rack assembly by means of the hinge mechanism configured to provide for a rotational movement of the tray relative to the rack chassis.

In one arrangement, the tray and rack chassis are further coupled at the front portion of the rack assembly by means of a stop mechanism configured to define and to limit the angular range of movement of the tray relative to the rack chassis between the lower open position of the tray and the upper closed position of the tray.

In one arrangement, the stop mechanism comprising fixing brackets (<NUM>) on either side of the tray are receivable in the corresponding fixing bracket receiver slots (<NUM>) of the rack chassis, the range of movement of the fixing bracket in the slot defining the range of angular movement of the tray about the tilting axis (<NUM>) and relative to the rack chassis (<NUM>), each fixing bracket (<NUM>) being moveable in a generally vertical direction (Z) between a lower open position and an upper closed position thereof within the slot. In the open position the front of the tray is located at a distance Z3 relative to the upper edge surfaces of the side walls of the chassis and the tray being tilted about the tilting axis at a rear portion thereof such that the control unit located in the tray is spaced apart relative to the cold plate across the entire surface area thereof. Further in one arrangement, each slot (<NUM>) has a generally rectangular form having upper and lower edge surfaces (<NUM>, <NUM>), wherein the fixing backet (<NUM>) is moveable between said upper and lower edges surfaces of the slot, the lower end defining a stop at the maximum angle of tilting of the tray about the tilting axis and the upper edge thereof defining a stop at the closed position of the tray.

Advantageously, the arrangements of the specification provide that when the tray is in the opened position the arrangement of the rack assembly unit and control unit is such that there is a clearance or separation between the control unit and the cold plate. While the control unit is tilted relative to the cold plate and to the rack chassis, the front portion of the control unit is at a greater separation from the rack chassis or cold plate, that the back portion is. However, the components are arranged to provide a clearance space across the upper surface area of the control unit. This avoids unwanted forces acting on the control unit or the cold plate and allows ease of access.

Further, as the tray is moved to the closed position, the control unit is moved into contact with the cold plate such that a contact force is applied between the control unit and the cold plate. The force applied arises from the interactions between the rack chassis and tray and the control unit and cold plate including as the tray is moved to the closed position and when the fixing mechanism is engaged.

In one arrangement the rack assembly unit further comprises a hinge rotation stop (<NUM>) defined by a hinge stop slot (<NUM>) formed in the rear wall portion (<NUM>) of the rack chassis (<NUM>) and a hinge stop protrusion (<NUM>) attached to the tray (<NUM>) and receivable in the hinge stop slot (<NUM>), the hinge rotation stop (<NUM>) configured such that when the tray is tilted to the open position relative to the rack chassis, the hinge stop protrusion (<NUM>) is engaged with an upper edge surface (<NUM>) of hinge stop slot (<NUM>) and further tilting of the tray relative to the rack chassis is limited.

In one arrangement, the coupling mechanism comprises a guided pin fixing mechanism (<NUM>),.

In one arrangement, the movement of the tray relative to the rack chassis is controlled by the range of movement of the each of the guide pins in each of the corresponding slots as defined by the guide slots, wherein the range of movement provides for translation of the tray relative to the rack chassis in the horizonal (X) and vertical (Z) directions.

In one arrangement, the rack assembly unit of any preceding claim wherein tray (<NUM>) further comprises a bead located on an inner surface of the base the tray and configured to generate a controlled contact force between the tray and the control unit located therein.

In one arrangement the rack assembly unit wherein the fixing mechanism for fixing the rack assembly in the closed position is defined by corresponding features of the rack chassis and the tray or control unit; the rack chassis comprising one or more fixing brackets (<NUM>, <NUM>); and the tray or the control unit coupled to the tray comprising one or more corresponding fixing brackets (<NUM>, <NUM>); wherein a fixing screw (<NUM>, <NUM>) is engaged a corresponding fixing brackets of each of the rack chassis, and the tray or control unit, to fix the position of the tray relative to the rack chassis in the closed position.

In one arrangement, the rack assembly unit comprises: first and second fixing brackets located on each of the side walls of the rack chassis and corresponding third and fourth fixing brackets located on each of the side walls of the tray, wherein in the closed position, the corresponding fixing brackets of the rack chassis and tray are located in proximity to each other and configured to receive a fixing screw (<NUM>) to fix the rack chassis to the tray in the closed position.

In another arrangement a first fixing bracket is provided on the rack chassis extending between the first and second side walls of the rack chassis which is configured for coupling with a second fixing bracket that is provided on the control unit housing. In one arrangement the control unit housing comprises first and second fixing pins (<NUM>) located projecting outwardly relative to the first and second side walls at a front portion thereof and configured to engage with a corresponding control unit coupling slot <NUM> located on the first and second sides walls of the tray.

According to a further aspect there is provided a vehicle rack server system (<NUM>) comprising;.

the rack server system (<NUM>) further comprising:.

The vehicle rack server system may further comprise two or more rack assembly units (<NUM>, <NUM>) arranged in a stack in the housing (<NUM>) for mounting a plurality of control units therein.

The control unit (<NUM>) comprises one or more electrical or communication connectors (<NUM>) and a TIM layer (<NUM>) located on a housing (<NUM>) thereof; wherein the rack assembly unit (<NUM>,<NUM>) is configured such that when the control unit (<NUM>) is located at an operating position therein, the control unit (<NUM>) is directly thermally coupled to the cold plate (<NUM>) at the TIM layer (<NUM>) to provide heat transfer from the control unit (<NUM>) to the cold plate (<NUM>), and the control unit is directly electrically and/or communicatively coupled to backplane board via corresponding headers (<NUM>) and connectors (<NUM>) of the rack assembly unit.

The arrangement of the vehicle server system addresses problems associated with previous approaches and allows for a correct and relatively simplified access and coupling of a control unit to the vehicle system, by virtue of the combination of features. The arrangement also provides for improved cooling and a cooling arrangement that provides an improved thermal coupling for heat transfer. The provision of a TIM layer further promotes efficient and effective cooling.

In an example, a control unit <NUM> is mounted in a tray <NUM>, and subsequently the tray is mounted in a rack. Trays are equipped with fixing mechanisms also referred to herein as coupling mechanism enabling the trays to fix or couple their position in the rack, and headers <NUM> to transmit signals from the control unit <NUM> in the trays to a backplane board <NUM>. The main components of the vehicle rack server system of <FIG> and the rack assembly unit in <FIG> and in the other Figures are a rack chassis, a control unit, a tray, a fixing screw, backplane connectors, and cold plate.

The specification provides different exemplary arrangements including a rack assembly having alternative two blade fixing also referred to as two blade coupling mechanisms. The first coupling mechanism described provides a tilting tray mechanism. The second provides a guide coupling mechanism, an arrangement in which trays are guided by cut-outs or slots provided in a rack chassis. The rack assembly units of the specification advantageously provide a leakproof enclosure for a phase change thermal interface material (TIM) between the control unit housing and cold plate, and for control and generation of a contact force in the thermal interface, between the control unit housing and the cold plate.

In the specification the term design has been used to reference to the exemplary arrangement and alternative exemplary arrangement. A first tray-tilting design or coupling mechanism - is based on a hinge mechanism, allowing the tray to tilt in the rack by a predefined angle, necessary for insertion/extraction of a control unit. In some alternative examples, the coupling mechanism is a guide-based coupling mechanism providing a rack equipped with cut-outs/guides formed in portions of the rack walls, which are configured as guides for movement of a tray, enabling safe replacement of a control unit mounted on the tray.

With reference to the exemplary arrangements of the drawings, the present specification provides a rack assembly unit <NUM>, <NUM> comprising a rack chassis <NUM> and tray <NUM> arranged for supporting a control unit <NUM> for mounting to a vehicle system. The rack chassis <NUM> and tray <NUM> configured for movably coupling together to form the rack assembly unit <NUM>, <NUM>. In the specification the rack assembly has also been referred to as the rack and tray unit, rack assembly unit and rack segment. Each rack assembly unit <NUM>, <NUM> according to the specification is configured for mounting a control unit <NUM> within a vehicle. The vehicle comprises a vehicle server system <NUM> at which the control units are mounted to the vehicle, having a housing for receiving the control units, connectors for interfacing the control units, as required to the overall vehicle system, and coupled to a cooling system. The vehicle system includes the internal communications and electrical system of the vehicle.

The control units <NUM> may comprise plug-in automotive control units including, for example DCUs, ECUs or MDCs. In the arrangements of the specification the rack assembly unit <NUM> is in configured for mounting automotive control units <NUM> to a vehicle by connection at the vehicle rack server system t00.

An exemplary arrangement of the vehicle rack server system <NUM> is described with reference to <FIG> and <FIG>. In the arrangement of <FIG>, the vehicle rack server system <NUM> includes three control units <NUM> mounted in a stacked configuration at rack support <NUM>. The rack support <NUM> is configured to receive one or more control units mounted in one or more rack assembly units <NUM>, <NUM>. The vehicle rack server system <NUM> further comprises a backplane <NUM> configured to interface the control units <NUM> with the vehicle systems. The backplane <NUM> comprises backplane connectors <NUM>. Each control unit <NUM>, when mounted in its respective in use operating position, within the vehicle rack server system <NUM> is directly coupled to the backplane <NUM>. The coupling of the control unit <NUM> to the backplane <NUM> provides for an electrical and/or communicative coupling of the control unit <NUM> to the backplane <NUM> and to external vehicle systems. In addition, each control unit when mounted in the operating position is thermally coupled to a cooling system. The rack assembly unit <NUM>, <NUM> is configured to provide for a thermal coupling of the control unit located therein to a cold plate <NUM> of a cooling system <NUM>, to support a heat transfer between components of the control unit <NUM> and the cold plate <NUM> at a thermal interface <NUM>. A thermal interface material, TIM, <NUM> is provided between the control unit <NUM> and the cold plate <NUM>. In this configuration, the TIM <NUM> is provided in a layer <NUM> located between the control unit <NUM> and the cold plate <NUM> such that a heat transfer surface of the cold plate <NUM> is thermally coupled to a heat transfer surface of the cold plate via the TIM. The rack assembly unit comprises a cold plate receiver for supporting the cold plate as required for coupling to a corresponding control unit <NUM>. This is described in further detail below.

The rack support <NUM> generally defines a housing unit <NUM> in which the one or more control units <NUM> are locatable, each control unit is mountable in a separate rack and tray unit <NUM> therein. The housing <NUM> comprises upper <NUM> and base <NUM> portions, rear <NUM> and side portions and a front <NUM> portion which defines an opening. Access to the one or more rack assembly units <NUM>, <NUM> and to trays or the control units is provided at the front portion <NUM>. The rack support <NUM> is arranged such that each rack assembly unit <NUM> and the control unit <NUM> mounted therein is oriented generally in a horizontal X-Y plane. The front and rear portions of the housing unit <NUM> are oriented generally vertically in a Z-Y plane. As such, in an arrangement comprising two or more control units, the control units <NUM> are effectively arranged in a vertical stack within the housing unit <NUM>. In the exemplary arrangement of <FIG> the backplane <NUM> is located generally adjacent to the rear <NUM> portion of the housing unit <NUM> and between the rear portion <NUM> and the rack and tray units <NUM>.

The rack and tray units or rack assembly units <NUM>, <NUM> of the exemplary arrangements are advantageously configured to allow control of the location of the control unit <NUM> located in the tray <NUM> relative to the rack chassis <NUM> and accordingly relative to the cold plate <NUM> and the backplane <NUM> of the vehicle rack server system. Further the rack assembly unit <NUM>, <NUM> is configured to provide control of forces between the control unit <NUM> and components including the tray <NUM>, chassis <NUM> and cold plate <NUM>. The rack assembly units <NUM>, <NUM> are configured to support ease of user access to the tray <NUM> and control unit <NUM> including for example, to insert, adjust, or exchange a control unit. Each rack assembly <NUM> is configured for stacking with other rack assembly units <NUM> to provide a modular type stacked rack assembly <NUM>'. The stacked rack assembly <NUM>' of <FIG> is configured to be receivable in a vehicle rack server system <NUM>.

Referring to <FIG>, a rack assembly <NUM> according to a first exemplary arrangement is described. In <FIG>, a control unit <NUM> is located in the rack assembly unit and the rack assembly unit is shown in a closed state.

The rack assembly unit <NUM> comprises a rack chassis <NUM> for receiving a corresponding tray <NUM>. the tray <NUM> is moveable relative to the chassis <NUM> between a first open position where the tray is spaced apart from the rack cassis arranged to allow access e.g. for insertion of a control unit <NUM> into the tray <NUM>, and a second closed position where the tray is located fully inserted into the rack chassis, and at which the control unit <NUM> located in the tray <NUM> is at the control unit operating position within the rack assembly <NUM>. As shown, the cold plate <NUM> is located on the rack assembly <NUM> at a support or receiver <NUM>. The rack assembly unit and control unit are configured such that in use in the operating position, the control unit <NUM> is thermally coupled to the cold plate <NUM>. In addition, when located in the operating position, the control unit <NUM> is coupled to backplane board <NUM> via the rack assembly <NUM>. The control unit is accordingly electrically and communicatively coupled to the vehicle system.

The tray <NUM> comprises a front slot <NUM> for engaging with corresponding mating features of the control unit to assist in locating the control unit <NUM> in the tray. In the drawings the front slot comprises a tapered opening at the front facing end of the side walls and the slot extends in the x-direction generally horizontally along a portion of the side walls (for example having a length of the order of <NUM> to <NUM>) of the tray.

The control unit comprises connectors <NUM>-<NUM>, <NUM>-<NUM> which are connected via headers <NUM>-<NUM>, <NUM>-<NUM> of tray <NUM>. Headers <NUM> are connected by means of a flat flexible cable, FFC, and connector <NUM> to backplane connectors <NUM>-<NUM>, <NUM>-<NUM> of the backplane <NUM>. The connectors <NUM> are located to the rear facing side of the control unit for connection to the headers <NUM> at a rear wall <NUM> of the tray. The tray comprises apertures <NUM> formed in the rear wall <NUM> to accommodate the headers <NUM> and connectors <NUM>. The rack chassis <NUM> comprises cut-outs or apertures <NUM> aligned with the headers <NUM> when the tray is coupled to the rack chassis. When the tray is inserted into the rack chassis, the headers <NUM> provides the necessary connections in the direction of the backplane <NUM>. The rack chassis has a width (the distance between the side walls) w1 greater than the width w2 of the tray. The rack chassis has a depth (of the side walls) d1 greater than the depth d2 of the side walls of the tray, and the depth d3 of the control unit.

The depth of each the rack chassis defined by the depth of the walls thereof, is sufficient to accommodate the tilting of the trays relative to the rack chassis in open position and to provide that a tilted tray <NUM> does not contact or result in application of force to a cooling unit located on a rack assembly below it, reference is made to <FIG> in which the middle tray <NUM> is shown tilted relative to the corresponding rack chassis as in <FIG>. <FIG> shows the clearance or separation distance as provided by the rack assembly between the control unit and the top edge portion of the rack assembly and the relative positions of the cold plate and control unit.

Referring to <FIG> further plan views from the front and side are provided. These views illustrate the compact arrangements of the control unit <NUM> in the rack assembly <NUM> in the closed position at which the control unit <NUM> located between a base <NUM> of the tray and the cold plate <NUM> located on the rack chassis.

The rack assembly unit comprise a fixing mechanism comprising one or more fixing screws <NUM> and first and second fixing brackets <NUM>, <NUM>. Fixing screws <NUM> extend through a fixing bracket <NUM> of the rack chassis and a corresponding fixing bracket <NUM> of the tray, to provide a connection between them and to fix the rack assembly unit in the closed position. In the arrangements shown, first and second brackets are provided located at each side wall of the rack chassis and of the tray, and a screw is inserted into each set of fixing brackets. In use, when the rack assembly unit and control unit are located in the vehicle rack server system, the rack assembly unit is fixed in the closed position by the fixing screws.

The rack assembly unit further comprises a coupling mechanism for movably coupling the tray and the rack chassis. The coupling mechanism provides for the movement of the tray relative to the rack chassis and the assembly of the tray and rack chassis for form the unit. The coupling mechanism according to the exemplary arrangements of <FIG>, <FIG>, <FIG> and <FIG> is a tilting tray coupling mechanism <NUM>. The coupling mechanism <NUM> comprises corresponding hinge <NUM>, hinge receiver <NUM>, and rotation stop features <NUM>, <NUM> provided on both the tray and the rack chassis. The tilting tray mechanism is described in further detail below with reference to <FIG> and <FIG>.

Referring to <FIG> the rack chassis <NUM> comprises sides walls <NUM>, <NUM> connected by a rear wall <NUM>. The side walls and rear wall comprise inwardly facing surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and outwardly facing surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and a front opening <NUM>. The side and rear walls have upper edge surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and lower edge surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>. The side walls have front facing edge surface <NUM>-<NUM>, <NUM>-<NUM> and rear facing edge surfaces <NUM>-<NUM>, <NUM>-<NUM>. In use the front portion of the rack assembly unit faces outwardly and is the side at which a user can access the tray and control unit. The rear facing side faces the backplane. Portions of the side and rear walls as shown in the drawings include cut-outs forming apertures <NUM>, <NUM> or openings <NUM>, the external surfaces of the walls of the rack chassis may define the external surfaces of the rack assembly unit <NUM>. In an alternative arrangement a cover panel may be applied to the external surfaces of the side and/or rear walls.

The rear wall <NUM> includes cut-out portions which define connector cut-outs or connector openings <NUM> to accommodate headers <NUM> of the tray <NUM>. In use, the headers <NUM> protrude through the connector openings <NUM> of the rack chassis for connection to a backplane <NUM>. Each side wall <NUM>, <NUM> comprises a recess <NUM> having a lower edge surface <NUM> which is recessed relative to the upper edge surfaces <NUM>-<NUM>, <NUM>-<NUM>. In use, the two recesses <NUM> arranged at opposite side walls <NUM>, <NUM> together define a cold plate receiver of the rack chassis, As shown in <FIG>, in use cold plate <NUM> is supported by the rack chassis. The recesses <NUM> have a depth d4, corresponding to the distance from the upper edge surfaces <NUM>-<NUM>, <NUM>-<NUM> of the side walls <NUM>, <NUM> to the lower edge surface <NUM> of the recess <NUM>, which is greater than the depth of the cold plate. Noting that a number of rack assembly units <NUM> or <NUM> may be provided arranged in a stack, recess <NUM> is provided at a lower side edge of each of the side walls at a location corresponding to the recess <NUM>, such that in a stacked configuration, the lower edge surface of second rack assembly stacked above a first rack assembly is spaced apart from the cold plate <NUM>. The rack assembly unit is configured to accommodate the cold plate and to avoid unwanted forces acting thereon and to allow access.

The tray <NUM> is movably coupled to the rack chassis <NUM> of the rack assembly <NUM>. , each comprises corresponding mating features of the hinge coupling mechanism <NUM>. <FIG> and <FIG> show the tray coupled to the rack chassis.

As shown most clearly in <FIG>, the rack chassis <NUM> comprises hinge receivers <NUM> comprising circular apertures located at to the rear-end portion of each of the side walls configured for mating with corresponding hinges <NUM>. The rack chassis comprises slots <NUM> and a fixing bracket <NUM> located at the front-end portion of each of the side walls which are configured for mating with corresponding fixing brackets <NUM> of the tray <NUM>.

Referring to <FIG>, the tray <NUM> comprises first and second side walls <NUM>, <NUM>, a rear wall <NUM>, a base <NUM>, and a front opening <NUM>. The side walls and rear wall comprise inwardly facing surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and outwardly facing surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>. The side and rear walls have upper edge surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and lower edge surfaces <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>. The side walls have front end edge surfaces <NUM>-<NUM>, <NUM>-<NUM> and rear-end edge surfaces <NUM>-<NUM>, <NUM>-<NUM>. In the exemplary arrangement the base <NUM> and rear wall <NUM> comprise cut-outs defining base apertures <NUM> and rear wall apertures <NUM>. The base apertures <NUM> may be provided to reduce the overall weight of the tray. The rear wall apertures <NUM> are provided to accommodate the one or more headers <NUM> of the tray <NUM>. The base <NUM> of the tray further comprises a bead <NUM>. The bead defines a contact surface for contacting and engaging with the control unit.

With reference to <FIG> and <FIG>, the fixing mechanism, in this arrangement the tilting tray fixing mechanism <NUM> is described in further detail.

The tray comprises hinges <NUM> and fixing brackets <NUM> provided located on the side walls <NUM>, <NUM>. The hinges <NUM> are located to the rear of the side walls in the X direction and in use when coupled to the rack chassis at the hinge receiver, the hinge element <NUM> is located between the rear and side walls of the tray and the rear and side walls of the rack chassis. The hinges <NUM> are attached to each side wall at a hinge attachment plate <NUM> (<FIG> and <FIG>) which allows for location of hinge at a separation in the X-direction relative to the rear end edge surfaces <NUM>-<NUM> and <NUM>-<NUM> of the side walls <NUM>, <NUM>. The hinges <NUM> extend outwardly relative to the side walls in the Y direction to attach to the hinge receivers <NUM> of the rack chassis. The fixing brackets <NUM> are located to the front portion of the side wall also protrude outwardly relative to the wall surfaces in the direction of the rack chassis which is use is located externally to the tray.

The hinges <NUM> and hinge receivers <NUM> of the rack chassis are located and configured for correspondence and mating. The hinges <NUM> are receivable in hinge receivers <NUM> located in the side walls <NUM> and <NUM> of the rack chassis at each side. The hinges <NUM> are inserted into the hinge receivers <NUM> at both sides of the tray movably coupling the tray to the rack chassis and to define a tilting axis <NUM> of the tray relative to the rack chassis. The hinge <NUM> is located offset in the X-direction relative to the rear wall and rear edge surface of each side wall of the tray and the tilting axis if located between the rear wall of the tray and the rear wall of the rack chassis.

The tray <NUM> and rack chassis <NUM> are also coupled together near to the front portion of the rack assembly <NUM>. The fixing brackets <NUM> of the tray and the corresponding slots <NUM> and fixing brackets <NUM> of the rack chassis, are located respectively to the front portions of the corresponding side walls of the tray and the rack chassis. The fixing backets <NUM> of the tray are configured for coupling to the rack chassis at the corresponding slots <NUM> and fixing brackets <NUM> of the rack chassis.

Referring to <FIG>, <FIG>, <FIG> and <FIG> the coupling mechanism <NUM> for coupling of the tray and rack chassis is described in further detail. The slot <NUM> of the exemplary arrangement comprises a rectangular form aperture having an upper edge surface <NUM> and lower edge surface <NUM>, and the fixing bracket <NUM> of the tray receivable in the slot and is movable within the slot <NUM> between the upper and lower edge surfaces <NUM> and <NUM> thereof which provide stops to the range of the movement of the fixing bracket. The interaction of the fixing brackets <NUM> with the slots <NUM> also defines the range of tilting of the tray relative to the rear tilting axis. The fixing brackets <NUM> are moveable generally in the vertical direction (Z) relative to the slot. When the fixing bracket <NUM> of the tray is engaged with the lower surface <NUM> of the slot, the tray is in the open position and tilted at the maximum angle α of the tilting range of movement of tray relative to the rack chassis. In the exemplary arrangement of <FIG> and <FIG>, the lower edge surface <NUM> of the slot is arranged sloping at an angle α to the horizontal (and the orientation of the upper and lower edge surfaces of the side walls), such that in the open position the fixing bracket <NUM> and the lower edge surface <NUM> are at substantially the same angle and the engagement surface of the fixing bracket is aligned for engagement with the lower edge surface <NUM>.

While in <FIG> and <FIG> the tray is shown in the closed position with the fixing pins or fixing screws <NUM> in place in the fixing brackets <NUM> and <NUM>, in <FIG> and <FIG> the tray is shown in the open position. The tray is spaced apart from the rack chassis such that a user can access the tray for inserting, replacing or removing a control unit.

Referring to <FIG>, the location of the one or more headers <NUM> of the tray in the apertures <NUM> of the tray and extending through the connector openings <NUM> of the rack chassis. As noted above, the rack chassis is configured for provide clearance for movement of the tray relative to the chassis and the other rack assembly units of a stack. As shown in <FIG> the base of the tray, in the tilted position, is fully contained within the footprint of the rack chassis and the tilting does not affect the alignment of the header <NUM> of the tray relative to the aperture <NUM> of the rack chassis.

Referring to <FIG>, the hinge <NUM> is located on the tray by means of a hinge plate <NUM>. The hinge plate <NUM> is attachable to an external surface of the side walls <NUM>, <NUM> by fixing means <NUM>.

The tray may comprise a recess <NUM> for receiving the plate <NUM>. The plate is shaped and sized for attachment to the rear-end portion of each side wall - such that a portion of the plate overlaps a portion of the external surface of the side wall and a portion of the plate extends rearwardly relative to the side wall to locate the hinge <NUM> rearwardly of the tray. In use and when the tray is coupled to the rack chassis the hinge element and tilting axis are located between the rear wall of the tray and the rear wall of the rack chassis.

The rack assembly <NUM> may further comprise a hinge rotation stop <NUM> defined by corresponding hinge rotation stop features of the rack chassis and the tray. The rack chassis comprises at least one hinge stop slot <NUM>, having an upper edge surface <NUM> and a lower edge surface <NUM>, formed in the rear wall <NUM> thereof. The tray comprises a least one hinge stopper protrusion <NUM>, arranged to protrude to the rear of the tray and receivable in the corresponding hinge stop slot <NUM>. The hinge rotation stop <NUM> is configured such that when the tray is tilted to the open position relative to the rack chassis, the hinge stop protrusion <NUM> is engaged with the hinge stop slot <NUM> at the upper edge surface <NUM> and further tilting of the tray relative to the rack chassis is limited. The hinge stop <NUM> advantageously provides additional support and stability for the tray <NUM> in the open position and allows control of movement of the tray relative to the chassis.

In <FIG> the tray is in the open position and the hinge stop protrusion <NUM> is engagement with an upper edge of the slot <NUM>. A hinge rotation stop <NUM> may be provided to one or both sides of the rack assembly. The hinge stop protrusion <NUM> may be provided, as shown in the exemplary arrangement of <FIG>, as part of the hinge plate <NUM>. The hinge <NUM> and the hinge stop protrusion <NUM> are accordingly directly coupled at the plate <NUM>. The tilting of the hinge controlled an arrangement which also allows control of forces between the components of the rack assembly units and components located or supported thereon.

Referring to <FIG> and 6A to 6E a rack assembly unit <NUM> according to an alternative arrangement of the drawings is described. The overall arrangement of the rack assembly unit <NUM> is similar to that of the rack assembly <NUM> and many features of the tray and rack chassis correspond in each of the two arrangements. Similar reference numbers have been used where appropriate.

Referring to <FIG>, the rack assembly unit <NUM> comprises a tray <NUM> and rack chassis <NUM> which are movably coupled to form the rack assembly. The tray is configured to receive a control unit. The tray is moveable between an open position and a closed position. In the open position the tray is spaced apart from the rack chassis to allow access for inserting, removing or replacing a control unit. In the closed position the tray is located received in the rack chassis. The rack assembly and the control unit are configured for correspondence, and such that when the tray is engaged in the closed position in the rack chassis, the control unit located in the tray is provided at the operating position of the control unit. At the operating position of the control unit, when the rack assembly is located in the vehicle server <NUM>, then control unit is located for thermal coupling to a cold plate and further is coupled to a backplane connector of the server to provide an electrical and//communication connection. Connectors <NUM> of the control unit <NUM> are coupled via headers <NUM> of the tray to connectors <NUM> of the backplane. The tray <NUM> is movably coupled to the rack chassis <NUM>.

Referring to <FIG>, the tray is shown coupled to the rack chassis. The rack chassis comprises a controller fixing bracket <NUM> that extends in the Y direction between upper portions of the side walls <NUM>, <NUM> of the rack chassis. The controller fixing bracket <NUM> comprises includes a controller fixing aperture <NUM>. When the control unit is located in the tray in the closed position, the controller fixing bracket <NUM> is arranged in alignment with a control unit fixing bracket <NUM> comprising a fixing aperture <NUM> (see for example <FIG> and <FIG>) and a fixing pin <NUM> is inserted through the apertures <NUM> and <NUM> to fix the rack assembly unit and control unit in the closed position. The rack chassis of the arrangement of <FIG> further comprises a side wall cover <NUM>. The side wall cover <NUM> is attachable to the external side walls <NUM>, <NUM> and provides an external cover for the guide coupling mechanism. The side wall cover provides additional support at the side walls and protects the guide coupling mechanism.

The coupling mechanism <NUM> of the rack assembly <NUM> is different from the fixing mechanism <NUM> of the rack assembly <NUM> and is described in further detail with reference to <FIG>. The rack assembly <NUM> comprises a coupling mechanism <NUM> which is based on a guide pin and guide slot arrangement which defines a guide coupling mechanism <NUM>. The guide fixing mechanism <NUM> is configured to provide for movably coupling of a tray <NUM> to a rack chassis <NUM>. In <FIG>, the tray is coupled to the rack chassis at guide and pin fixing mechanism <NUM>. The guide fixing mechanism <NUM> comprises corresponding mating features of the tray and the rack chassis. As shown in <FIG> and <FIG>, each side wall <NUM>, <NUM> of the rack chassis comprises guide slots <NUM> and <NUM>. As shown in <FIG>, each side wall <NUM>, and <NUM> of the tray comprises guide pins <NUM> and <NUM> which are receivable in the guide slots <NUM>. In the arrangement of <FIG>, the tray is moved by translation, generally in the X direction relative to the rack chassis. The tray <NUM> remains oriented generally horizontally in the X-Y plane throughout the range of movement. The guide fixing mechanism is described in further detail below.

Referring to <FIG>, the guide slots <NUM> and <NUM> are described in further detail. The first and second side walls, <NUM>, <NUM> comprise an upper slot <NUM> and a lower slot <NUM>. The slot <NUM> is formed in the wide wall extending in the X direction from an opening <NUM> in a front side edge of the wall in the direction of the rear of the tray. The slot <NUM> is of a length <NUM>. The slot <NUM> is shorter in length than the slot <NUM> - for example, having a length of around <NUM> to <NUM>,<NUM> of the overall length of the side wall. The slot <NUM> comprises a horizontal linear portion <NUM> and sloped portion <NUM>. The slot is angled upwardly to the rear end portion <NUM> of the slot. The slot <NUM> is located above the slot <NUM> in the vertical (Z -direction). The slot <NUM> is of a length l2. The slot <NUM> is longer in length than the slot <NUM> and extends generally the length (X) direction of the side wall. The slot <NUM> comprises a horizontal linear portion <NUM> and sloped portion <NUM>. The slot is angled upwardly at the sloped portion <NUM> to the rear end portion <NUM> of the slot. The slot <NUM> is located above the slot <NUM> in the vertical (Z -direction).

Referring to <FIG> each side wall <NUM>, <NUM> of the tray comprises first <NUM> and second <NUM> guide pins receivable in the corresponding slots <NUM> and <NUM> of the rack chassis. The guide pins extend outwardly, generally at right angles to the external surfaces <NUM>-<NUM>, <NUM>-<NUM> of each side wall. In the exemplary arrangement the guide pins have a cylindrical form and are dimensioned to be receivable in the corresponding guide slots. The guide pins <NUM>, <NUM> are located on guide pin plates <NUM> and <NUM> which are attachable to the side walls by fixing pins or other suitable means. Each plate is clamped to at least a portion of external surface side wall of the tray such that the plate overlaps with a portion of the side wall. Guide pins <NUM> are located generally near the upper edge surfaces <NUM>-<NUM>, <NUM>-<NUM>, of the side walls and to the forward end of the tray. Guide pins <NUM> are located generally near the lower edge surface <NUM>-<NUM>, <NUM>-<NUM> of the side walls and are located to the rear facing end of the tray. The tray is coupled to the rack chassis by inserting the guide pins <NUM> and <NUM> into the guide slots <NUM> and <NUM> respectively. In the arrangement shown, the rear guide pin <NUM> is located off-set in the X-direct relative to the rear wall <NUM> of the tray.

With reference to <FIG>, the tray is shown located in the chassis and in the open position. In use the tray is moved relative to the chassis by application of a force (push or pull) in the X direction. The tray moves by translation as the guide pins <NUM>, <NUM> move in the slots <NUM>, <NUM>. As described above the rear most end <NUM>, <NUM> of each slot is raised (Z-direction) relative to the front ends <NUM>, <NUM> and the linear portions <NUM>, <NUM>. In effect, as the tray is moved from the open position to the closed position, that movement is guided by the guide pins located in the guide slots. As the guide pins are moved along the first horizonal portions <NUM>, <NUM> of the respective guide slots <NUM> and <NUM>, the tray is translated at a first lower vertical position (Z1) relative to the chassis. When the tray is further inserted and moved in the direction of the closed position, the guide pins are moved along the second sloped portions <NUM>, <NUM> of the guide slots, and the vertical position of the tray relative to the chassis is changed - the tray is moved to a second vertical position higher than the first. In the closed position the tray is located at the second higher vertical position (Z2). This provides for coupling of the control unit <NUM> located in the tray <NUM> with the cold plate <NUM> in the operating position. The range of movement of the tray in the X direction relative to the rack chassis is effectively defined by the length L1 of the first upper slot <NUM>. The range of movement of the tray in the vertical (Z direction) relative to the chassis is defined by the difference in height of the raised end portion of the slots relative to the lower linear portion.

<FIG> provide views of the rack assembly <NUM> when the tray <NUM> is located in the open position. The drawings 6A and 6B show the relative location of the tray and rack chassis when the tray is in the open position and vertically located at the first lower vertical position (Z1) relative to the chassis.

Referring to <FIG> the features of the slots and the interaction of the guide pins <NUM> and <NUM> with the slots <NUM> and <NUM> are shown. The upper slot <NUM> comprises an opening <NUM>, horizontal portion <NUM>, sloped portion <NUM> and end stop <NUM>. The lower slot <NUM> comprises an opening <NUM>, horizontal portion <NUM>, sloped portion <NUM> and end stop <NUM>. The upper slot supports the guide pin <NUM> at different levels relative to the lower edge surface <NUM>-<NUM>, <NUM>-<NUM> of the side wall <NUM>, <NUM> including the lower level s1 and uppermost level s2. The lower slot supports the guide pin <NUM> at different levels relative to the lower edge surface <NUM>-<NUM>, <NUM>-<NUM> of the side wall <NUM>, <NUM> including the lower level s3 and uppermost level s4. In <FIG> the guide pins <NUM>, <NUM> are located to the forwardmost position of their range of movement (X-direction) in the slots and at the lower levels (Z-direction) of their range of movement - the tray is in the open position and located at the lower tray level Z1 within the rack chassis. When the tray is in the closed position the guide pins are then at the end stop positions at the rearmost portion of the range of movement in the X direction and at the uppermost levels of the range of movement in the Z- direction. The tray is then located at the upper tray level Z2 within the rack chassis.

Referring to <FIG>, <FIG> and <FIG>, features of the control unit <NUM> are described in more detail. It is appreciated that the rack assembly unit <NUM>, <NUM> and control unit <NUM> are configured for correspondence. Further the control unit <NUM> is configured to be receivable in the tray <NUM> and for mating with the tray. As noted above the exemplary arrangements of the specification advantageously provide for coupling of the control unit as required for operation with the vehicle.

<FIG> and <FIG> shows some further details of the coupling of the interaction of the control unit and rack assembly unit <NUM> (<FIG>) and the rack assembly unit <NUM> (<FIG>) respectively and the arrangement for coupling the control unit with the cold plate.

Referring to <FIG>, the tray comprises a slot <NUM> for receiving a corresponding coupling pin <NUM> of the control unit <NUM>. The control unit comprises a control unit housing <NUM>. The coupling pins are located on opposite side walls of the housing. It is appreciated that various electronic components may be provided in the control unit housing. The control unit is configured such that in the operating position within the rack assembly it is located such that active cooling is provided to the components of the control unit that require cooling. The TIM <NUM> may be provided in a layer <NUM> on a TIM receiver portion <NUM> of the housing <NUM> of the control unit <NUM>. In <FIG>, the tray is in the open position for example, to allow insertion of the control unit, and as can be seen the TIM <NUM> is located on an upper portion of the control unit. The cold plate <NUM> is located supported on the cold plate receivers <NUM> of the rack chassis. The rack assembly and control unit are arranged such that as the tray is inserted to the closed position, the TIM <NUM> will be moved into position with and aligned as required with the cold plate <NUM>, the interaction rack chassis, tray and control unit also provides for a thermal coupling of the control unit to the cold plate <NUM> at the TIM layer <NUM>.

<FIG> shows a rack assembly <NUM> with the tray <NUM> in the open position, tilted relative to the rack chassis <NUM> and with the control unit <NUM> located in the tray. In the open position, the control unit <NUM> and the TIM <NUM> are located below the cold plate <NUM> and at an angle to the cold plate. Some clearance space may be provided between the cold plate and the control unit such that there is no physical contact between the control unit and the TIM layer and the cold plate in the open position. The connector <NUM> of the control unit is connected to header <NUM> of the tray and to FFC connector <NUM> at the rear of the rack assembly unit.

<FIG> shows the rack assembly <NUM> after it has been moved from the open position to the closed position. The control unit <NUM> is by virtue of the combination of features of the rack assembly and the control unit located in the operating position, for use within the vehicle. The control unit <NUM> is coupled via the TIM <NUM> to the cold plate <NUM> for heat transfer. The connectors <NUM> of the control unit <NUM> are coupled via the headers <NUM> of the tray and connectors <NUM> for connection to the backplane of the vehicle system. The detail of <FIG> shows the interaction of the bead <NUM> located on the base <NUM> of the tray with the control unit <NUM>.

Referring to <FIG> the tray is located in the open position of the rack assembly unit <NUM> comprising the guide slot coupling mechanism <NUM>. A guide pin <NUM> of the control unit is located in the slot <NUM> of the tray. A fixing arrangement of the rack assembly <NUM> is also shown. The rack chassis comprises a controller fixing bracket <NUM> having first and second apertures <NUM>. As shown a second fixing bracket <NUM> is provided coupled to the control unit and to the tray.

The control unit <NUM> comprises a TIM <NUM> provided in a TIM layer <NUM> in a receiver <NUM> of the housing thereof. As shown in <FIG> and <FIG> when the tray <NUM> of the rack assembly <NUM> is moved to the closed position - it is translated in the direction of the rear of the rack chassis, and also to the second upper vertical level within the chassis. As described above, each guide rail slot <NUM>, <NUM> comprises two levels (Z-direction). The control unit in the tray is accordingly moved upwardly within the rack chassis and coupled to the cold plate via the TIM <NUM> in the closed position of the tray.

When the tray is moved to the closed position, as shown in <FIG>, the fixing brackets <NUM> and <NUM> are brought into contact, they are engaged together at the fixing apertures <NUM>. <NUM> using fixing screws <NUM> to fix the rack assembly unit <NUM> in the closed position. This fixing is also shown in cross-section in <FIG>.

Referring to <FIG>, an exemplary arrangement of a control unit <NUM> comprising the TIM <NUM> in a layer <NUM> is described. The control unit in the exemplary drawings is located in rack assembly <NUM>. The control unit <NUM> comprises a TIM receiver <NUM> located on an upper external surface of the housing <NUM> thereof. A groove <NUM> is formed in the upper surface, in the exemplary arrangement the groove defines a rectangular shaped TIM receiver. The groove <NUM> defines the perimeter of the receiver <NUM>. As shown in <FIG>, the groove is recessed relative to the surface and a seal <NUM> for example an O-ring is located in groove134. The TIM <NUM> is provided in a layer <NUM> on the housing in the receiver defined by the groove. In the closed position of the tray and the operating position of the control unit, as shown in <FIG>, the control unit is coupled to the lower surface of the cold plate <NUM> via the TIM <NUM>. The seal <NUM> is engaged with respective heat transfer surface of both the control unit housing and the cold plate.

Referring to <FIG> in conjunction with <FIG>, the heat transfer that is provided is described in more detail. <FIG> illustrates an automotive rack server <NUM> equipped with cold plate <NUM> and electronic control units <NUM>, a thermal interface <NUM> where a heat transfer surface of each of the cold plate and the control unit are thermally coupled and heat flow path <NUM> indicated schematically by arrows. In order to allow heat flow from the electric/electronic components <NUM> inside the control unit <NUM> to the cold plate <NUM>, an efficient heat flow path <NUM> is established. In the arrangement of the drawings a heat flow path <NUM> is based on use of the thermal interface material, TIM, <NUM> arranged between the cold plate and the control unit. The TIM <NUM> material is used to reduce the so-called thermal contact resistance between the mating heat transfer surfaces, and hence allows improved heat flow across the thermal interface, TI, <NUM>. TIM <NUM> may be provided in the form of a gel, grease, soft compliant pad, or phase change material. Other TIM types are also possible. To allow efficient heat transfer through the layer <NUM> of TIM, it is arranged such that it is located between the heat source e.g., the control unit housing and the cold plate, while both components are firmly pressed against each other. Contact pressure plays a major role in improving the thermal joint heat conducting efficiency, as it reduces interface thickness and allows to fill micro-scale cavities by TIM. Both effects improve thermal conductance of the thermal interface <NUM>.

Referring to <FIG>, alternative view of the stack <NUM>' of <FIG> are shown. With reference to the Figures the features and control of the relative positions of the control unit <NUM>, TIM <NUM> and cold plate <NUM> located in a tiling tray a rack assembly <NUM>, are described. As shown in <FIG> and <FIG>, the tray in the middle is in the open position, the tray is tiled relative to the rack chassis. The control unit comprises a TIM <NUM> arranged on an upper surface thereof as described with reference to <FIG> in a TIM receiver <NUM> surrounded by a groove <NUM>. A sealing member for example an O-ring <NUM> is located in groove <NUM>. In the open position, the control unit and TIM are not in contact with the control located in proximity to the cold plate and at an angle relative to lower surface thereof and aligned for coupling to the cold plate as the tray is moved to the closed position. Referring to <FIG>, the control units <NUM> located in the upper and lower trays in the closed position are shown coupled to the cold plate <NUM> via the TIM <NUM>. Also shown is the coupling of the connector <NUM> of the control unit to the header <NUM> of the tray.

Further, the exemplary rack assembly arrangements <NUM> and <NUM> are configured to create a leakproof enclosure for a phase change thermal interface material, TIM, <NUM> located between the control unit housing <NUM> of the control unit <NUM> and cold plate <NUM>. The rack assembly <NUM>, <NUM> is further configured to provide for generation of a contact force at the thermal interface, TI, <NUM> between the control unit and the cold plate <NUM>.

The present specification claims priority from the <CIT>, filed on September <NUM>, <NUM>.

An advantage of the exemplary rack assembly arrangements of the specification and an objective problem solved by the example rack and track assembly is to protect the TIM <NUM>, which is a layer <NUM> on a housing <NUM> of a control unit <NUM>, to protect against damage from replacing the control unit following a replacement process. In addition, the example rack and track assembly is configured to overcome a problem of generating a necessary contact pressure at the TIM, between the control unit and the cold plate(s) <NUM>, which are fixed to the rack chassis <NUM>.

For example, some automotive electronic control units, ECU, are being replaced by more complex domain control units, DCU, or, increasingly frequently, multi-domain control units, MDC,. Both type of control units (or simply controllers) are devices designed to support and control various functional domains of a vehicle, like advanced driver assistance systems, ADAS or infotainment systems. The DCUs are typically less complex devices, developed to operate in a single domain, while MDCs control functionalities from more than one domain.

In case of the high-performance control units130, e.g., dedicated to ADAS functionality, for which power dissipation reaches 150W and beyond, utilization of forced liquid cooling is typically the only possibility to keep the temperature of the fragile electronics within the safety and lifetime limits. This is due to a high maximum ambient temperature typically seen in automotive applications when driving the vehicle under operating conditions (<NUM> and more) and limited thermal robustness of logical components, like system-on-a-chip or memory modules. A liquid cooling system <NUM> circulates liquid coolant inside a cold plate <NUM>, which is a device used to dissipate thermal energy from the hot areas. Such a cold plate <NUM> can be integrated within the vehicle rack server <NUM>, not being replaceable with a control unit <NUM>. <FIG> illustrates a schematic representation of the automotive rack server <NUM> equipped with a cold plate <NUM> and electronic control units <NUM>. In the schematic representation, heat flow path <NUM> between these components is marked by arrows.

In order to allow heat flow from the electric/electronic components inside the control unit <NUM> to the cold plate <NUM>, an efficient heat flow path is to be established between these components. One possible method of realization of such a heat flow path is to use thermal interface material, TIM, <NUM>. TIM material <NUM> is used to reduce the so-called thermal contact resistance between the mating surfaces, hence allows improved heat flow across the interface. To allow efficient heat transfer through a layer <NUM> of TIM, it is applied between the heat source (e.g., the control unit housing <NUM>) and the cold plate <NUM>, while both components are firmly pressed against each other. Contact pressure plays a major role in improving the thermal joint heat conducting efficiency, as it reduces interface thickness and allows to fill micro-scale cavities by TIM <NUM>. Both effects improve thermal conductance of the interface.

In case of the vehicle rack server and control unit rack assembly <NUM>, <NUM> in a car, a number of technical issues may arise examples of which are noted below:.

A first problem addressed by the exemplary arrangements of this specification and an advantage of the arrangements of the claims is associated with 'creating thermally efficient heat flow path <NUM> between control unit housing <NUM> and a cold plate <NUM>, for electronics cooling purposes', is addressed by the example designs which use a layer <NUM> of thermal interface material <NUM> in between control unit housing <NUM> and a cold plate <NUM>. In order to maintain the required cleanliness of the device, it is assumed that the solid-state TIM <NUM> will be used between the control unit housing <NUM> and the cold plate <NUM>, which can be easier for replacement, less 'messy' and more stable, compared with thermal greases or gels. However, it is appreciated that alternatives are possible, which is suitable for application of phase change material.

A second problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is associated with assembling a control unit (e.g., a control unit) housing and a layer of TIM into a rack, while protecting the TIM from damage during plugging-in of the control unit is addressed by the example designs by applying the TIM <NUM> to the housing <NUM> of the control unit <NUM> before its insertion to the tray <NUM>. Subsequently, the control unit is inserted to the opened tray. In the next step, the tray is closed by rotating it around the rotation axis <NUM> (hinge mechanism <NUM>) or by pushing it through the guiding cut-outs <NUM>, <NUM> (second guide-pin fixing mechanism <NUM> alternative). In the last step, the control unit's position is fixed, and the necessary contact force is applied to the thermal interface <NUM>, by the fixing screws220, available at the front of the rack <NUM>. In this procedure, TIM is engaged in contact with the cold plate <NUM> already when it reaches its final location in the assembly, therefore it is protected from any physical interaction with the rack components during the assembly process. Hence, the risk of a potential damage to the TIM layer is limited.

Another problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is associated with 'applying suitable contact pressure to the thermal interface filled with a layer of TIM, without damaging fragile electronics or mechanical components (connectors)', is addressed by the example arrangements by elimination of any fragile components from the load transfer path. In both example arrangements, the contact force is transferred between the fixing screws <NUM>, control unit housing <NUM>, tray <NUM>, and rack mechanical components: hinges <NUM>, <NUM> or guiding cut-outs <NUM>, <NUM>, <NUM>, <NUM>. The backplane board connectors <NUM> are isolated from the loading path by using a flat flexible cable <NUM> (FFC), which connects backplane board <NUM> with the connector <NUM> fixed to the tray. Therefore, any force resulting from pushing the tray against the cold plate during the assembly process is compensated by the deflection of an FFC tape. Hence, no damaging force is exerted on the connectors. Another possible realization of electrical connection between the control unit <NUM> and the backplane board <NUM> is to use the so-called floating board-to-board connectors instead of FFC tapes and connectors <NUM> These electrical connectors are capable of compensating translational and angular misalignment, hence do not generate unwanted force on the PCBs, to which they are attached. Another advantage of using floating connectors is higher signal integrity, due to lower electrical noise injected to the system when FFC tapes are eliminated and the number of physical interconnections are minimized.

A further problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is 'utilization of a phase change thermal interface material, development of a leak-proof TIM application region, which would prevent leaking away/dripping off of the TIM in its liquid state', is addressed by the example designs by preparation of a sealed area <NUM> of application for the phase change thermal interface material <NUM>, which is located on the top of the control unit <NUM>. This area is surrounded by a groove <NUM> with an O-ring <NUM> placed inside. In the assembly process, when control unit's housing is pushed against the cold plate, the O-ring <NUM> is pressed to the cold plate surface as well and seals the region it bounds. In this region, a phase change TIM <NUM> can be applied.

A further problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is directed to 'exerting suitable contact force on a thin layer of TIM, under the rack's geometric tolerances resulting from manufacturing process', is addressed by the example invention by introduction of fixing screws <NUM> allowing to adjust and simultaneously limit the contact force and the position of the tray <NUM> (loaded with the control unit <NUM>) in the rack <NUM>. Additionally, a specially designed bead <NUM> in the bottom surface <NUM> of the tray <NUM> improves the distribution of the contact force on the control unit housing <NUM>.

Another problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is connected with 'a universal, cost-efficient and compact rack, suitable for all vehicle classes, from economic to luxury vehicles', is addressed by the present invention by using a simple sheet metal structure for the rack including the rack chassis and the tray components, which can be screwed, riveted or welded into a final product. Sheet metal components of the example rack are cut out or stamped from metal sheets, and bended into the required shape, allowing for cost-efficient design suitable for all classes of vehicles. Additionally, the example design is based on simple geometrical features (hinges or guiding cut-outs) which allow replacement and fixing the position of the control unit <NUM>, without the need for sophisticated or complex mechanisms.

An additional problem addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims is connected with 'elaborating a modular rack design, which could be easily scaled up and down, depending on the required number of plug-in slots', is addressed by the example invention by designing a segment or rack assembly unit <NUM>, <NUM>, which can be replicated in the final rack structure comprising a number of stacked rack assembly units as many times as needed, for accommodating the required number of control units <NUM> for example, DCUs/MDCs.

Another problem, addressed by the exemplary arrangements of the specification and an advantage of the arrangements of the claims , is connected with 'elaborating a design of the rack, that would allow for fast and easy replacement of control unit units <NUM>, with only a limited access to these devices (resulting from rack's placement in a car), particularly from the front side (opposite side to the backplane board in <FIG>)', is addressed by the example invention by designing the rack-tray mechanism <NUM>, <NUM> in such a way, that it requires to be accessed only from the front, in order to insert, extract and fix the position of the control unit <NUM> in a rack. Additionally, if a cold plate <NUM> needs to be cleaned from the unwanted remaining of TIM, this can be done after removal of the control unit <NUM> from the tray <NUM>.

The exemplary rack assembly <NUM>, <NUM> according to the specification may for example be built from components made from metal sheets assembled together. This can be done by means of riveting (example shown in the pictures below) or other suitable method, like welding, screwing or other. Advantage of this approach is the low cost in mass production. The parts are first cut out of large metal sheets (aluminum alloys or steel, possibly other material like magnesium alloy), bended into the required shape, assembled and fixed into the final shape of the rack. Other advantages of such assembly are the low weight and compactness, due to low wall thickness of the components, in an exemplary arrangement, of the order of <NUM>. Additionally, both the rack assembly alternatives based on tray-tilting <NUM> and tray guiding <NUM> mechanisms, can be built by using relatively simple, inexpensive components, like hinges and guiding pins.

<FIG>, <FIG>, and <FIG> show a general view of a rack assembly unit or segment <NUM>, equipped with the hinge mechanism and guided-pin mechanism (<FIG>, <FIG>).

The role of the components enlisted in the figures include as follows:.

<FIG> shows the design details of the tray tilting mechanism, with the tray opened, ready for insertion of the control unit housing. The tilting angle is limited in the example solution by two design features: cut-out <NUM> in the rack side wall, stopping the fixing bracket <NUM> attached to the tray (<FIG> and <FIG>) and cut-out <NUM> in the rack rear wall <NUM> (backplane board side) stopping the hinge rotation stopper <NUM> (<FIG>).

Another possible realization of the rack equipped with tray-tilting mechanism described in this document is based on the utilization of floating connectors, to connect a control unit mounted in the tray, with the backplane board. Floating connectors can replace the FFC tape, allowing for small-scale compensation of angular and planar misalignments. Typical misalignment which can be compensated by floating connectors reaches less than <NUM> of translational positioning inaccuracy in planar X and Y directions, and less than <NUM> degree of angular misalignment. Hence, utilization of this type of devices requires higher rack manufacturing and assembly accuracy compared with the solution based on the FFC tape. The advantage is in the reduction of electrical noise generated in the connection, which is highly desired from the signal integrity point of view.

<FIG> shows the consecutive steps of insertion of a control unit into the rack equipped with the tray-tilting mechanism. In order to do so, the following steps are carried out: Insertion of the guiding pins <NUM> on the control unit's housing <NUM> into the cut-outs <NUM> in the tray side walls <NUM>, <NUM>, while tray tilted at an angle relative to the chassis into the opened position, Pushing the control unit <NUM> into the opened tray <NUM>, until it reaches its final mounting position, in which the control unit's rear connectors <NUM> are fully inserted into the tray's headers <NUM>, Rotating the tray loaded with a control unit <NUM> into its final position, until the TIM <NUM> on the top of the control unit's housing <NUM> is in contact with the cold plate <NUM>, and Fixing the tray's final position and generation of the force in the thermal interface between the control unit and the cold plate, by tightening the fixing screws <NUM> in the fixing brackets <NUM> and <NUM> - contact bead <NUM> in the bottom <NUM> of the tray pushes against the a control unit housing <NUM>. <FIG> illustrates the tray loaded with a control unit fixed in its final position -thermal interface <NUM> is established between the control unit <NUM> and cold plate <NUM>, with an enlarged view detailing the contact bead <NUM> in the bottom wall of the tray pushing against the DCU/MDC housing/control unit housing <NUM>.

<FIG> shows the consecutive steps of insertion of a control unit into the rack equipped with the guided-pin mechanism by performing the following:.

The presented automotive server-like rack assembly arrangements <NUM> allow for utilization of enhanced thermal interface <NUM> between the DCUs/MDCs <NUM> and the cold plate <NUM>, which can be obtained by means of using phase changing thermal interface material <NUM>. Typically, phase change TIMs used in the cooling systems of electronics, are solid materials in room/ambient temperatures, which change into liquid when system's temperature rises. In liquid state, phase change material, PCM, <NUM> flows into surface irregularities, filling the air gaps in the thermal interface, increasing its heat conducting efficiency. Typical phase change temperature of PCMs used in electronic cooling application reaches <NUM> - <NUM>. Above this temperature, solid PCM changes into liquid until the temperature drops again, below the same or similar value.

A problem connected with using PCMs in the automotive applications is the need of assuring leakproof of the PCM application region, which would prevent leaking away/dripping off the melted material, in the vehicle normal operating conditions (vibration, impact, etc.). The two design alternatives presented in this document, can be modified, in order to fulfil this requirement. The modification is applied to a control unit housing, by creating a groove on the surface of the control unit's housing, surrounding the TIM material <NUM> allowing for a control unit to cold plate interface.

As shown in <FIG>, the groove is filled with an O-ring, which pressed against the cold plate, seals the application region of the PCM. <FIG> shows the groove and O-ring used in the tray-tilting rack design; however, the same modification can be applied to the rack equipped with the guided-pin mechanism. <FIG> shows a general view on the control unit housing <NUM> with a groove <NUM>, O-ring <NUM> and a layer <NUM> of phase change TIM. <FIG> depicts a front view of the rack assembly unit with D-D illustrating the cross-section line through the rack assembly and the cross-section through the rack assembly, and a <FIG> shows an enlarged, detailed view of the O-ring pressed against the cold plate, sealing the PCM application region <NUM>.

Claim 1:
A rack assembly unit (<NUM>, <NUM>) for mounting a control unit (<NUM>) to a vehicle rack system (<NUM>), the rack assembly unit (<NUM>, <NUM>) comprising:
a rack chassis (<NUM>);
a tray (<NUM>) for receiving the control unit (<NUM>);
wherein the tray (<NUM>) being movably coupled to the rack chassis at a coupling mechanism (<NUM>, <NUM>), the coupling mechanism (<NUM>, <NUM>) configured to provide for movement of the tray relative to the rack chassis between a first open position and a second closed position; the rack assembly unit characterized in that at the first open position, the tray (<NUM>) is spaced apart from rack chassis (<NUM>) to facilitate user access to the tray and to the control unit receivable therein, and at the second closed position, the tray (<NUM>) is located fully inserted relative to the rack chassis (<NUM>) and such that the control unit (<NUM>) located in the tray is provided at a control unit operating position thermally coupled to a cold plate of a cooling system to provide for cooling of components of the control unit; and
wherein the control unit (<NUM>) comprises a housing (<NUM>) which comprises a thermal interface material, hereinafter named TIM, receiver portion (<NUM>) for receiving a TIM (<NUM>) in the form of a TIM layer (<NUM>), wherein the TIM receiver portion (<NUM>) is defined by a recessed groove (<NUM>) formed in an upper surface of the control unit, the recessed groove defining a periphery of the TIM receiver portion (<NUM>) and having a shape generally corresponding to that of the cold plate, and wherein an O-ring (<NUM>) is located in the recessed groove surrounding the TIM receiver portion.