Rack with trays for plug-in automotive control units

A rack assembly unit for mounting a control unit to a vehicle rack system is provided; a rack chassis and a tray are configured to receive the control unit for coupling to a vehicle system. The tray is movably coupled to the rack chassis at a coupling mechanism, which provides for movement of the tray relative to the rack chassis between open and closed positions. At the open position, the tray is spaced apart from rack chassis to facilitate user access to the tray and receiving the control unit therein. At the closed position, the tray is located fully inserted relative to the rack chassis and such that the control unit 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.

BACKGROUND

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 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. 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 exposed 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.

SUMMARY

The present application relates in general to a rack assembly for mounting of control units into a vehicle system. The rack assembly provides an improved mounting arrangement for mounting trays for plug-in automotive type control units.

The specification aims to provides 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 for mounting a control unit to a vehicle rack system, the rack assembly comprising: a rack chassis; a tray for receiving the control unit; wherein the tray being movably coupled to the rack chassis at a coupling mechanism, the coupling mechanism configured to provide for movement of the tray relative to the rack chassis between a first open position and a second closed position; wherein at the first open position, the tray is spaced apart from rack chassis to facilitate user access to the tray and to the control unit receivable therein, and at the second closed position, the tray is located fully inserted relative to the rack chassis and such that the control unit 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.

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 connected by a rear wall and having a front opening; the tray comprising first and second side walls connected by a rear wall and having a front opening and a base portion. 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.

According to another arrangement, the control unit has at least one connector comprising an electrical and/or communication connector and the rack assembly unit comprising a corresponding header and a backplane connector 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 of the vehicle system. This electrical and communicative coupling is provided via the header and a backplane connector. 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 comprises a cold plate support for receiving and supporting a cold plate, and the rack assembly unit configured such that when the tray 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 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 has first and second side walls, wherein the cold plate support is defined by first and second recesses formed at a top edge surface of each of the side walls, wherein the recesses 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 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, is provided between the control unit and the cold plate 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.

In one arrangement, the control unit comprises a housing which comprises a TIM receiver portion for receiving the TIM in the form of a TIM layer701, wherein the TIM receiver portion may be defined by a recessed groove formed in an upper surface of the control unit, the recessed groove defining a periphery of the TIM receiver portion and having a shape generally corresponding to that of the cold plate, and wherein an O-ring 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 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, 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 on either side of the tray are receivable in the corresponding fixing bracket receiver slots 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 and relative to the rack chassis, each fixing bracket 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 Z3relative 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 has a generally rectangular form having upper and lower edge surfaces, wherein the fixing bracket 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 defined by a hinge stop slot formed in the rear wall portion of the rack chassis and a hinge stop protrusion attached to the tray and receivable in the hinge stop slot, the hinge rotation stop configured such that when the tray is tilted to the open position relative to the rack chassis, the hinge stop protrusion is engaged with an upper edge surface of hinge stop slot 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, wherein the tray and rack chassis are movably coupled at the first and second side walls by the guided pin fixing mechanism to provide for movement by translation of the tray relative to the rack chassis between the first open position and the closed position; and wherein the tray and rack chassis comprise corresponding guide pins and guide slots located at the first and second side walls of each of the tray and rack chassis.

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 horizontal (X) and vertical (Z) directions.

In one arrangement, the rack assembly unit of any preceding claim wherein tray 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; and the tray or the control unit coupled to the tray comprising one or more corresponding fixing brackets; wherein a fixing screw 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 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 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 located on the first and second sides walls of the tray.

According to a further aspect there is provided a vehicle rack server system comprising; a rack support for receiving at least one rack assembly unit as claimed in any preceding claim; a backplane board comprising one or more backplane connectors for interfacing with said control unit; a cold plate coupled to a cooling system, the cold plate located in the rack support and receivable on said rack assembly unit; the rack server system further comprising: a rack assembly unit located in the housing for mounting a control unit to the vehicle rack server system, the rack assembly unit comprising one or more headers and connectors coupled to the backplane board, and the cold plate located on the rack assembly unit; a control unit located in said rack assembly unit; wherein the rack assembly unit is configured such that when the control unit is located at an operating position therein, the control unit is directly thermally coupled to the cold plate to provide heat transfer from the control unit to the cold plate.

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

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

DETAILED DESCRIPTION

In an example, a control unit130is mounted in a tray150, 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 headers135to transmit signals from the control unit130sin the trays to a backplane board570. The main components of the vehicle rack server system ofFIG.1Aand the rack assembly unit inFIG.2Dand 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 unit100,300comprising a rack chassis110and tray150arranged for supporting a control unit130for mounting to a vehicle system. The rack chassis110and tray150configured for movably coupling together to form the rack assembly unit100,300. 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 unit100,300according to the specification is configured for mounting a control unit130within a vehicle. The vehicle comprises a vehicle server system500at 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 units130may comprise plug-in automotive control units including, for example DCUs, ECUs or MDCs. In the arrangements of the specification the rack assembly unit100is in configured for mounting automotive control units130to a vehicle by connection at the vehicle rack server system t00.

An exemplary arrangement of the vehicle rack server system500is described with reference toFIGS.1A and1B. In the arrangement ofFIG.1A, the vehicle rack server system500includes three control units130mounted in a stacked configuration at rack support510. The rack support510is configured to receive one or more control units mounted in one or more rack assembly units100,300. The vehicle rack server system500further comprises a backplane570configured to interface the control units130with the vehicle systems. The backplane570comprises backplane connectors575. Each control unit130, when mounted in its respective in use operating position, within the vehicle rack server system500is directly coupled to the backplane570. The coupling of the control unit130to the backplane570provides for an electrical and/or communicative coupling of the control unit130to the backplane570and 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 unit100,300is configured to provide for a thermal coupling of the control unit located therein to a cold plate180of a cooling system181, to support a heat transfer between components of the control unit130and the cold plate180at a thermal interface750. A thermal interface material, TIM,700is provided between the control unit130and the cold plate180. In this configuration, the TIM700is provided in a layer701located between the control unit130and the cold plate180such that a heat transfer surface of the cold plate180is 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 unit130. This is described in further detail below.

The rack support510generally defines a housing unit520in which the one or more control units130are locatable, each control unit is mountable in a separate rack and tray unit100therein. The housing520comprises upper522and base523portions, rear524and side portions and a front526portion which defines an opening. Access to the one or more rack assembly units100,300and to trays or the control units is provided at the front portion526. The rack support510is arranged such that each rack assembly unit100and the control unit130mounted therein is oriented generally in a horizontal X-Y plane. The front and rear portions of the housing unit520are oriented generally vertically in a Z-Y plane. As such, in an arrangement comprising two or more control units, the control units130are effectively arranged in a vertical stack within the housing unit520. In the exemplary arrangement ofFIG.1Athe backplane570is located generally adjacent to the rear523portion of the housing unit520and between the rear portion523and the rack and tray units100.

The rack and tray units or rack assembly units100,300of the exemplary arrangements are advantageously configured to allow control of the location of the control unit130located in the tray150relative to the rack chassis110and accordingly relative to the cold plate180and the backplane570of the vehicle rack server system. Further the rack assembly unit100,300is configured to provide control of forces between the control unit130and components including the tray150, chassis100and cold plate180. The rack assembly units100,300are configured to support ease of user access to the tray150and control unit130including for example, to insert, adjust, or exchange a control unit. Each rack assembly100is configured for stacking with other rack assembly units100to provide a modular type stacked rack assembly100′. The stacked rack assembly100′ ofFIG.1Bis configured to be receivable in a vehicle rack server system500.

Referring toFIGS.2ato2d, a rack assembly100according to a first exemplary arrangement is described. InFIGS.2, a control unit130is located in the rack assembly unit and the rack assembly unit is shown in a closed state.

The rack assembly unit100comprises a rack chassis111for receiving a corresponding tray150. the tray150is moveable relative to the chassis111between 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 unit130into the tray150, and a second closed position where the tray is located fully inserted into the rack chassis, and at which the control unit130located in the tray150is at the control unit operating position within the rack assembly100. As shown, the cold plate180is located on the rack assembly100at a support or receiver120. The rack assembly unit and control unit are configured such that in use in the operating position, the control unit130is thermally coupled to the cold plate180. In addition, when located in the operating position, the control unit130is coupled to backplane board570via the rack assembly100. The control unit is accordingly electrically and communicatively coupled to the vehicle system.

The tray150comprises a front slot159for engaging with corresponding mating features of the control unit to assist in locating the control unit130in 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 10 to 20 mm) of the tray.

The control unit comprises connectors135-1,135-2which are connected via headers165-1,165-2of tray150. Headers165are connected by means of a flat flexible cable, FFC, and connector166to backplane connectors575-1,575-2of the backplane570. The connectors135are located to the rear facing side of the control unit for connection to the headers165at a rear wall153of the tray. The tray comprises apertures156formed in the rear wall153to accommodate the headers165and connectors166. The rack chassis110comprises cut-outs or apertures116aligned with the headers165when the tray is coupled to the rack chassis. When the tray is inserted into the rack chassis, the headers165provides the necessary connections in the direction of the backplane570. The rack chassis has a width (the distance between the side walls) w1greater than the width w2of the tray. The rack chassis has a depth (of the side walls) d1greater than the depth d2of the side walls of the tray, and the depth d3of 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 tray150does not contact or result in application of force to a cooling unit located on a rack assembly below it, reference is made toFIGS.10B and10Cin which the middle tray150is shown tilted relative to the corresponding rack chassis as inFIG.1B.FIG.2Dshows 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 toFIGS.2cand2dfurther plan views from the front and side are provided. These views illustrate the compact arrangements of the control unit130in the rack assembly100in the closed position at which the control unit130located between a base155of the tray and the cold plate180located on the rack chassis.

The rack assembly unit comprise a fixing mechanism comprising one or more fixing screws220and first and second fixing brackets210,265. Fixing screws220extend through a fixing bracket265of the rack chassis and a corresponding fixing bracket210of 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 ofFIGS.1B,2A to2D,3A to4D and4A to4Dis a tilting tray coupling mechanism200. The coupling mechanism200comprises corresponding hinge205, hinge receiver255, and rotation stop features210,260provided on both the tray and the rack chassis. The tilting tray mechanism is described in further detail below with reference toFIGS.3A to3D and4A to4D.

Referring toFIGS.3A to3Cthe rack chassis110comprises sides walls111,112connected by a rear wall113. The side walls and rear wall comprise inwardly facing surfaces111-1,112-1,113-1and outwardly facing surfaces111-2,112-2,113-2, and a front opening114. The side and rear walls have upper edge surfaces111-3,112-3,113-3and lower edge surfaces111-4,112-4,113-4. The side walls have front facing edge surface111-5,112-5and rear facing edge surfaces111-6,112-6. 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 apertures156,157or openings116, the external surfaces of the walls of the rack chassis may define the external surfaces of the rack assembly unit100. In an alternative arrangement a cover panel may be applied to the external surfaces of the side and/or rear walls.

The rear wall113includes cut-out portions which define connector cut-outs or connector openings116to accommodate headers165of the tray150. In use, the headers165protrude through the connector openings116of the rack chassis for connection to a backplane570. Each side wall111,112comprises a recess120having a lower edge surface121which is recessed relative to the upper edge surfaces111-3,112-3. In use, the two recesses120arranged at opposite side walls111,112together define a cold plate receiver of the rack chassis, As shown inFIG.2A, in use cold plate180is supported by the rack chassis. The recesses120have a depth d4, corresponding to the distance from the upper edge surfaces111-3,112-3of the side walls111,112to the lower edge surface121of the recess120, which is greater than the depth of the cold plate. Noting that a number of rack assembly units100or300may be provided arranged in a stack, recess122is provided at a lower side edge of each of the side walls at a location corresponding to the recess120, 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 plate180. The rack assembly unit is configured to accommodate the cold plate and to avoid unwanted forces acting thereon and to allow access.

The tray150is movably coupled to the rack chassis110of the rack assembly100, each comprises corresponding mating features of the hinge coupling mechanism200.FIGS.2A to2D and3A and3Bshow the tray coupled to the rack chassis.

As shown most clearly inFIG.3C, the rack chassis110comprises hinge receivers255comprising circular apertures located at to the rear-end portion of each of the side walls configured for mating with corresponding hinges205. The rack chassis comprises slots260and a fixing bracket265located at the front-end portion of each of the side walls which are configured for mating with corresponding fixing brackets210of the tray150.

Referring toFIG.3D, the tray150comprises first and second side walls151,152, a rear wall153, a base155, and a front opening154. The side walls and rear wall comprise inwardly facing surfaces151-1,152-1,153-1and outwardly facing surfaces151-2,152-2,153-2. The side and rear walls have upper edge surfaces151-3,152-3,153-3and lower edge surfaces151-4,152-4,153-4. The side walls have front end edge surfaces151-5,152-5and rear-end edge surfaces151-6,152-6. In the exemplary arrangement the base155and rear wall153comprise cut-outs defining base apertures157and rear wall apertures156. The base apertures157may be provided to reduce the overall weight of the tray. The rear wall apertures156are provided to accommodate the one or more headers165of the tray150. The base155of the tray further comprises a bead164. The bead defines a contact surface for contacting and engaging with the control unit.

With reference toFIGS.3A to3DandFIGS.4A to4D, the fixing mechanism, in this arrangement the tilting tray fixing mechanism200is described in further detail.

The tray comprises hinges205and fixing brackets210provided located on the side walls151,152. The hinges205are 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 element205is located between the rear and side walls of the tray and the rear and side walls of the rack chassis. The hinges205are attached to each side wall at a hinge attachment plate240(FIG.3CandFIG.4D) which allows for location of hinge at a separation in the X-direction relative to the rear end edge surfaces151-6and152-6of the side walls151,152. The hinges205extend outwardly relative to the side walls in the Y direction to attach to the hinge receivers255of the rack chassis. The fixing brackets210are 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 hinges205and hinge receivers255of the rack chassis are located and configured for correspondence and mating. The hinges205are receivable in hinge receivers255located in the side walls111and112of the rack chassis at each side. The hinges205are inserted into the hinge receivers255at both sides of the tray movably coupling the tray to the rack chassis and to define a tilting axis201of the tray relative to the rack chassis. The hinge205is 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 tray150and rack chassis110are also coupled together near to the front portion of the rack assembly100. The fixing brackets210of the tray and the corresponding slots260and fixing brackets265of the rack chassis, are located respectively to the front portions of the corresponding side walls of the tray and the rack chassis. The fixing brackets210of the tray are configured for coupling to the rack chassis at the corresponding slots260and fixing brackets265of the rack chassis.

Referring toFIGS.4A,4B,4C and4Dthe coupling mechanism200for coupling of the tray and rack chassis is described in further detail. The slot260of the exemplary arrangement comprises a rectangular form aperture having an upper edge surface261and lower edge surface262, and the fixing bracket210of the tray receivable in the slot and is movable within the slot260between the upper and lower edge surfaces261and262thereof which provide stops to the range of the movement of the fixing bracket. The interaction of the fixing brackets210with the slots260also defines the range of tilting of the tray relative to the rear tilting axis. The fixing brackets210are moveable generally in the vertical direction (Z) relative to the slot. When the fixing bracket210of the tray is engaged with the lower surface262of 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 ofFIGS.4A and4B, the lower edge surface262of 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 bracket210and the lower edge surface262are at substantially the same angle and the engagement surface of the fixing bracket is aligned for engagement with the lower edge surface262.

While inFIGS.2A to2DandFIGS.3A and3Bthe tray is shown in the closed position with the fixing pins or fixing screws220in place in the fixing brackets265and210, inFIGS.4A and4Bthe 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 toFIG.4C, the location of the one or more headers165of the tray in the apertures166of the tray and extending through the connector openings116of 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 inFIG.4Cthe 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 header165of the tray relative to the aperture116of the rack chassis.

Referring toFIG.4D, the hinge205is located on the tray by means of a hinge plate240. The hinge plate240is attachable to an external surface of the side walls151,152by fixing means241.

The tray may comprise a recess158for receiving the plate240. 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 hinge205rearwardly 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 assembly100may further comprise a hinge rotation stop242defined by corresponding hinge rotation stop features of the rack chassis and the tray. The rack chassis comprises at least one hinge stop slot270, having an upper edge surface271and a lower edge surface272, formed in the rear wall113thereof. The tray comprises a least one hinge stopper protrusion243, arranged to protrude to the rear of the tray and receivable in the corresponding hinge stop slot270. The hinge rotation stop242is configured such that when the tray is tilted to the open position relative to the rack chassis, the hinge stop protrusion243is engaged with the hinge stop slot270at the upper edge surface271and further tilting of the tray relative to the rack chassis is limited. The hinge stop242advantageously provides additional support and stability for the tray150in the open position and allows control of movement of the tray relative to the chassis.

InFIG.4Dthe tray is in the open position and the hinge stop protrusion243is engagement with an upper edge of the slot270. A hinge rotation stop242may be provided to one or both sides of the rack assembly. The hinge stop protrusion243may be provided, as shown in the exemplary arrangement ofFIG.4D, as part of the hinge plate240. The hinge205and the hinge stop protrusion243are accordingly directly coupled at the plate240. 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 toFIGS.5A to5E and6A to6Ea rack assembly unit300according to an alternative arrangement of the drawings is described. The overall arrangement of the rack assembly unit300is similar to that of the rack assembly100and many features of the tray and rack chassis correspond in each of the two arrangements. Similar reference numbers have been used where appropriate.

Referring toFIG.5A, the rack assembly unit300comprises a tray150and rack chassis110which 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 server500, 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. Connectors135of the control unit130are coupled via headers135of the tray to connectors575of the backplane. The tray150is movably coupled to the rack chassis110.

Referring toFIG.5A, the tray is shown coupled to the rack chassis. The rack chassis comprises a controller fixing bracket117that extends in the Y direction between upper portions of the side walls111,112of the rack chassis. The controller fixing bracket117comprises includes a controller fixing aperture119. When the control unit is located in the tray in the closed position, the controller fixing bracket117is arranged in alignment with a control unit fixing bracket137comprising a fixing aperture139(see for exampleFIGS.8A and8C) and a fixing pin221is inserted through the apertures119and139to fix the rack assembly unit and control unit in the closed position. The rack chassis of the arrangement ofFIGS.5A to5Efurther comprises a side wall cover118. The side wall cover118is attachable to the external side walls111,112and 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 mechanism400of the rack assembly300is different from the fixing mechanism200of the rack assembly100and is described in further detail with reference toFIGS.5B to5E. The rack assembly300comprises a coupling mechanism400which is based on a guide pin and guide slot arrangement which defines a guide coupling mechanism400. The guide fixing mechanism400is configured to provide for movably coupling of a tray150to a rack chassis110. InFIG.5B, the tray is coupled to the rack chassis at guide and pin fixing mechanism400. The guide fixing mechanism400comprises corresponding mating features of the tray and the rack chassis. As shown inFIGS.5B and5D, each side wall111,112of the rack chassis comprises guide slots410and420. As shown inFIG.5E, each side wall151, and152of the tray comprises guide pins420and430which are receivable in the guide slots410. In the arrangement ofFIG.5, the tray is moved by translation, generally in the X direction relative to the rack chassis. The tray150remains oriented generally horizontally in the X-Y plane throughout the range of movement. The guide fixing mechanism is described in further detail below.

Referring toFIGS.5C and5D, the guide slots410and420are described in further detail. The first and second side walls,111,112comprise an upper slot410and a lower slot420. The slot410is formed in the wide wall extending in the X direction from an opening411in a front side edge of the wall in the direction of the rear of the tray. The slot410is of a length11. The slot410is shorter in length than the slot420—for example, having a length of around 0.1 to 0.2 of the overall length of the side wall. The slot410comprises a horizontal linear portion412and sloped portion413. The slot is angled upwardly to the rear end portion414of the slot. The slot410is located above the slot420in the vertical (Z-direction). The slot420is of a length12. The slot420is longer in length than the slot410and extends generally the length (X) direction of the side wall. The slot420comprises a horizontal linear portion422and sloped portion423. The slot is angled upwardly at the sloped portion423to the rear end portion424of the slot. The slot410is located above the slot420in the vertical (Z-direction).

Referring toFIG.5Eeach side wall151,152of the tray comprises first430and second440guide pins receivable in the corresponding slots410and420of the rack chassis. The guide pins extend outwardly, generally at right angles to the external surfaces151-2,152-2of 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 pins430,440are located on guide pin plates431and441which 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 pins430are located generally near the upper edge surfaces111-3,112-3, of the side walls and to the forward end of the tray. Guide pins440are located generally near the lower edge surface111-4,112-4of 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 pins430and440into the guide slots410and420respectively. In the arrangement shown, the rear guide pin440is located off-set in the X-direct relative to the rear wall153of the tray.

With reference toFIGS.6A to6C, 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 pins430,440move in the slots410,420. As described above the rear most end414,424of each slot is raised (Z-direction) relative to the front ends411,421and the linear portions412,422. 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 horizontal portions412,422of the respective guide slots410and420, 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 portions413,423of 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 unit130located in the tray150with the cold plate180in 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 L1of the first upper slot410. 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.

FIGS.6A to6Cprovide views of the rack assembly300when the tray150is located in the open position. The drawings6A and6B 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 toFIG.6Cthe features of the slots and the interaction of the guide pins430and440with the slots410and420are shown. The upper slot410comprises an opening411, horizontal portion412, sloped portion413and end stop414. The lower slot420comprises an opening421, horizontal portion422, sloped portion423and end stop424. The upper slot supports the guide pin430at different levels relative to the lower edge surface111-4,112-4of the side wall111,112including the lower level s1and uppermost level s2. The lower slot supports the guide pin440at different levels relative to the lower edge surface111-4,112-4of the side wall111,112including the lower level s3and uppermost level s4. InFIG.6Cthe guide pins430,440are 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 Z1within 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 Z2within the rack chassis.

Referring toFIGS.7A,7B and7C, features of the control unit130are described in more detail. It is appreciated that the rack assembly unit100,300and control unit130are configured for correspondence. Further the control unit130is configured to be receivable in the tray150and 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.

FIGS.7A to7C and8A to8Dshows some further details of the coupling of the interaction of the control unit and rack assembly unit100(FIG.7) and the rack assembly unit300(FIG.8) respectively and the arrangement for coupling the control unit with the cold plate.

Referring toFIG.7, the tray comprises a slot159for receiving a corresponding coupling pin132of the control unit130. The control unit comprises a control unit housing131. 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 TIM700may be provided in a layer701on a TIM receiver portion133of the housing131of the control unit130. InFIG.7A, the tray is in the open position for example, to allow insertion of the control unit, and as can be seen the TIM700is located on an upper portion of the control unit. The cold plate180is located supported on the cold plate receivers120of the rack chassis. The rack assembly and control unit are arranged such that as the tray is inserted to the closed position, the TIM700is moved into position with and aligned as required with the cold plate180, the interaction rack chassis, tray and control unit also provides for a thermal coupling of the control unit to the cold plate180at the TIM layer701.

FIG.7Bshows a rack assembly100with the tray150in the open position, tilted relative to the rack chassis110and with the control unit130located in the tray. In the open position, the control unit130and the TIM700are located below the cold plate180and 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 connector135of the control unit is connected to header165of the tray and to FFC connector166at the rear of the rack assembly unit.

FIG.7Cshows the rack assembly100after it has been moved from the open position to the closed position. The control unit130is 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 unit130is coupled via the TIM700to the cold plate180for heat transfer. The connectors135of the control unit130are coupled via the headers165of the tray and connectors166for connection to the backplane of the vehicle system. The detail ofFIG.7Cshows the interaction of the bead164located on the base150of the tray with the control unit130.

Referring toFIG.8Athe tray is located in the open position of the rack assembly unit300comprising the guide slot coupling mechanism400. A guide pin132of the control unit is located in the slot159of the tray. A fixing arrangement of the rack assembly300is also shown. The rack chassis comprises a controller fixing bracket117having first and second apertures119. As shown a second fixing bracket137is provided coupled to the control unit and to the tray.

The control unit130comprises a TIM700provided in a TIM layer701in a receiver133of the housing thereof. As shown inFIGS.8B and8Cwhen the tray150of the rack assembly300is 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 slot410,420comprises 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 TIM700in the closed position of the tray.

When the tray is moved to the closed position, as shown inFIG.8B, the fixing brackets137and117are brought into contact, they are engaged together at the fixing apertures119.139using fixing screws221to fix the rack assembly unit300in the closed position. This fixing is also shown in cross-section inFIG.8D.

Referring toFIGS.9A to9C, an exemplary arrangement of a control unit130comprising the TIM700in a layer701is described. The control unit in the exemplary drawings is located in rack assembly300. The control unit130comprises a TIM receiver133located on an upper external surface of the housing131thereof. A groove134is formed in the upper surface, in the exemplary arrangement the groove defines a rectangular shaped TIM receiver. The groove134defines the perimeter of the receiver133. As shown inFIG.9C, the groove is recessed relative to the surface and a seal710for example an O-ring is located in groove134. The TIM700is provided in a layer701on 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 inFIGS.9B and9C, the control unit is coupled to the lower surface of the cold plate180via the TIM700. The seal710is engaged with respective heat transfer surface of both the control unit housing and the cold plate.

Referring toFIGS.9Band C in conjunction withFIG.1A, the heat transfer that is provided is described in more detail.FIG.1Aillustrates an automotive rack server500equipped with cold plate180and electronic control units130, a thermal interface750where a heat transfer surface of each of the cold plate and the control unit are thermally coupled and heat flow path760indicated schematically by arrows. In order to allow heat flow from the electric/electronic components138inside the control unit130to the cold plate180, an efficient heat flow path760is established. In the arrangement of the drawings a heat flow path760is based on use of the thermal interface material, TIM,700arranged between the cold plate and the control unit. The TIM700material 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,750. TIM700may 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 layer701of 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 interface750.

Referring toFIGS.10A,10B and10C, alternative view of the stack100′ ofFIG.1Bare shown. With reference to the Figures the features and control of the relative positions of the control unit130, TIM700and cold plate180located in a tiling tray a rack assembly100, are described. As shown inFIG.1BandFIGS.10A,10B and10c, the tray in the middle is in the open position, the tray is tiled relative to the rack chassis. The control unit comprises a TIM700arranged on an upper surface thereof as described with reference toFIG.9in a TIM receiver133surrounded by a groove134. A sealing member for example an O-ring710is located in groove134. 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 toFIG.10B, the control units130located in the upper and lower trays in the closed position are shown coupled to the cold plate180via the TIM700. Also shown is the coupling of the connector135of the control unit to the header165of the tray.

Further, the exemplary rack assembly arrangements100and300are configured to create a leakproof enclosure for a phase change thermal interface material, TIM,700located between the control unit housing131of the control unit130and cold plate180. The rack assembly100,300is further configured to provide for generation of a contact force at the thermal interface, TI,750between the control unit and the cold plate180.

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 TIM700, which is a layer701on a housing131of a control unit130, 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)180, which are fixed to the rack chassis110.

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 150 W 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 (50° C. and more) and limited thermal robustness of logical components, like system-on-a-chip or memory modules. A liquid cooling system181circulates liquid coolant inside a cold plate180, which is a device used to dissipate thermal energy from the hot areas. Such a cold plate180can be integrated within the vehicle rack server500, not being replaceable with a control unit130.FIG.1Aillustrates a schematic representation of the automotive rack server500equipped with a cold plate180and electronic control units130. In the schematic representation, heat flow path760between these components is marked by arrows.

In order to allow heat flow from the electric/electronic components inside the control unit130to the cold plate180, 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,700. TIM material700is 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 layer701of TIM, it is applied between the heat source (e.g., the control unit housing131) and the cold plate180, 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 TIM700. Both effects improve thermal conductance of the interface.

In case of the vehicle rack server and control unit rack assembly100,300in a car, a number of technical issues may arise examples of which are noted below:1. creating thermally efficient heat flow path between the control unit housing130and a cold plate180, for electronics cooling purposes,2. method for assembling a control unit housing130,13land a layer701of TIM into the rack100,300, while protecting the layer of TIM from damage during plugging-in of the control unit,3. applying suitable contact pressure to the thermal interface filled with a layer701of TIM, without damaging fragile electronics or mechanical components (connectors),4. in the case of utilization of a phase change thermal interface material700, development of a leak-proof TIM application region133,134,710, which would prevent leaking away/dripping off of the TIM in its liquid state,5. exerting suitable contact force on a thin layer701of TIM700, under the rack's geometric tolerances resulting from manufacturing process,6. providing a universal, cost-efficient, and compact rack100,300, suitable for all vehicle classes, from economic to luxury vehicles,7. providing a modular rack100,300, which could be easily scaled up and down, depending on the required number of plug-in slots,8. providing a rack, that allows for fast and easy replacement of control units, 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 inFIG.1A),

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 path760between control unit housing131and a cold plate180, for electronics cooling purposes’, is addressed by the example designs which use a layer701of thermal interface material700in between control unit housing131and a cold plate180. In order to maintain the required cleanliness of the device, it is assumed that the solid-state TIM700is used between the control unit housing131and the cold plate180, 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 TIM700to the housing131of the control unit130before its insertion to the tray150. Subsequently, the control unit is inserted to the opened tray. In the next step, the tray is closed by rotating it around the rotation axis201(hinge mechanism200) or by pushing it through the guiding cut-outs410,420(second guide-pin fixing mechanism400alternative). In the last step, the control unit's position is fixed, and the necessary contact force is applied to the thermal interface750, by the fixing screws220, available at the front of the rack100. In this procedure, TIM is engaged in contact with the cold plate180already 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 screws220, control unit housing130, tray150, and rack mechanical components: hinges205,255or guiding cut-outs410,420,430,440. The backplane board connectors575are isolated from the loading path by using a flat flexible cable166(FFC), which connects backplane board570with the connector165fixed 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 unit130and the backplane board570is to use the so-called floating board-to-board connectors instead of FFC tapes and connectors166These 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 area133of application for the phase change thermal interface material700, which is located on the top of the control unit130. This area is surrounded by a groove134with an O-ring710placed inside. In the assembly process, when control unit's housing is pushed against the cold plate, the O-ring710is pressed to the cold plate surface as well and seals the region it bounds. In this region, a phase change TIM700can 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 introduction of fixing screws220allowing to adjust and simultaneously limit the contact force and the position of the tray150(loaded with the control unit130) in the rack170. Additionally, a specially designed bead164in the bottom surface155of the tray150improves the distribution of the contact force on the control unit housing131.

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 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 unit130, 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 designing a segment or rack assembly unit100,300, 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 units130for 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 units130, 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 inFIG.2)’, is addressed by designing the rack-tray mechanism100,300in 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 unit130in a rack. Additionally, if a cold plate180needs to be cleaned from the unwanted remaining of TIM, this can be done after removal of the control unit130from the tray150.

The exemplary rack assembly100,300according 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 1 mm. Additionally, both the rack assembly alternatives based on tray-tilting200and tray guiding400mechanisms, can be built by using relatively simple, inexpensive components, like hinges and guiding pins.

FIGS.2A to2D,3A to3D, and4A to4Dshow a general view of a rack assembly unit or segment100, equipped with the hinge mechanism and guided-pin mechanism (FIGS.5A to5E,6A to6C).

The role of the components enlisted in the figures include as follows:Rack chassis110—serves as a support to all other components and allows mounting the complete assembly in a car,Tray150—serves as a support for the control unit housing130. Additionally, transmits the thermal interface force between the rack chassis110and the cold plate180, allowing to limit the unwanted mechanical load on the fragile components, like PCB, connectors, etc. The complete force transmitting components' chain is the following: cold plate180→thermal interface material700→control unit housing131→tray150→hinges/guiding pins200,400and fixing screws220,221→rack chassis110,Fixing screws220,221—used to fix the position of the tray in the rack chassis. Screws also generate and limit the fixing force in the mechanism (in both, tray-tilting200, and guided-pin400arrangements), allowing for the required contact pressure in the thermal interface material700, between the control unit's housing131and the cold plate180,Flat flexible cable (FFC) with the connector166—compensates the angular and linear displacements of the tray, resulting from opening and adjusting tray's position by the fixing screws. The FFC connects header165fixed to the tray, with the connector plugged-in to the backplane board570,Headers165in the tray—used to connect rear connectors135of a control unit130with the backplane board570(via the FFC tapes and connectors166),Fixing brackets220,265and117,137—in both alternative arrangements, the fixing brackets265or in the alternative arrangement fixing brackets117are available on the rack chassis110and corresponding fixing brackets210are located on the tray150or provided as a fixing bracket137coupled to the control unit130and to the tray150. In either case, they allow to use fixing screws220,221to fix the position of the tray in the rack,control unit housing contact bead164—a bead164stamped in the tray's bottom wall155, to compensate geometry inaccuracies resulting from manufacturing and assembly processes. When formed on the tray's bottom, bead164creates a line contact between the control unit housing131and the tray150. Because it is separated (lifted above) from the remaining part of the tray's bottom wall155, the bead164assures the presence of the contact, indifferently from the tray tolerances. Additionally, the two fixing screws220generate force, which pushes the tray150against the control unit's housing131. This force can deflect tray's thin-walled structure, improving the contact between the bead164and control unit housing131,Hinges205(tray tilting mechanism200)—connect the tray with the rack chassis at a hinge205and hinge receiver255, allowing rotational movement (tilting) the tray150,Pin guiding cut-outs (guided-pin mechanism400)—cut-outs or slots410,420provided in the side walls111,112of the rack chassis110, which guide the pins430,440located on the sides151,52of the tray150. The shape of the guiding cut-outs410,420provides two-types of movement in the tray relative to the chassis:firstly, linear tray movement is generated by the horizontal portions412,422of the cut-outs/slots410,420, allowing sliding of the tray parallel to the cold plate180bottom surface,secondly, non-linear trajectory movement is generated by the sloped portions413,423of the cut-outs/or slots410,420, forcing the tray150(loaded with the control unit130) to be pushed against the cold plate180, therefore assuring thermal interface750between control unit130and the cold plate180.Guiding cut-outs cover118(guided-pin mechanism400)—a plate118covering the cut-outs410,420in the rack side walls111,112, protecting the mechanism and adding stiffness to the structure,Front and rear guiding pins430,440—cylindrical pins attached to the tray150, arrangement for sliding through the cut-outs410,420in the rack chassis100.

FIGS.4A to4Dshow 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-out260in the rack side wall, stopping the fixing bracket210attached to the tray (FIGS.4C and4D) and cut-out270in the rack rear wall153(backplane board side) stopping the hinge rotation stopper244(FIG.4D).

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 1 mm of translational positioning inaccuracy in planar X and Y directions, and less than 3 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.

FIGS.7A to7Cshows 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 pins132on the control unit's housing131into the cut-outs159in the tray side walls151,152, while tray tilted at an angle relative to the chassis into the opened position, Pushing the control unit130into the opened tray150, until it reaches its final mounting position, in which the control unit's rear connectors135are fully inserted into the tray's headers165, Rotating the tray loaded with a control unit130into its final position, until the TIM700on the top of the control unit's housing131is in contact with the cold plate180, 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 screws220in the fixing brackets265and210—contact bead164in the bottom155of the tray pushes against the a control unit housing131.FIG.7Cillustrates the tray loaded with a control unit fixed in its final position—thermal interface750is established between the control unit130and cold plate180, with an enlarged view detailing the contact bead164in the bottom wall of the tray pushing against the DCU/MDC housing/control unit housing131.

FIGS.8A to8Dshow the consecutive steps of insertion of a control unit into the rack equipped with the guided-pin mechanism by performing the following. Insertion of the guiding pins132of the control unit130into the cut-outs159in the tray side walls151,152, while tray in the opened position. Pushing the control unit into the opened tray, until it reaches its final mounting position, in which the control unit's rear connectors135are fully inserted into the tray's headers165. Pushing the tray loaded with a control unit into its final position, until the TIM700on the top of the control unit's housing131is in contact with the cold plate180(tray slides through a non-linear part of the guiding cut-outs, which results in a simultaneous movement towards the backplane board and the cold plate). Fixing the tray's final position and generation of the force in the thermal interface between the control unit and the cold plate, by tighten the fixing screws221at fixing brackets117and137—contact bead164in the bottom of the tray pushes against a control unit housing.

The presented automotive server-like rack assembly arrangements500allow for utilization of enhanced thermal interface750between the DCUs/MDCs130and the cold plate180s, which can be obtained by means of using phase changing thermal interface material700. 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,703flows 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 50° C.-70° C. 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 material700allowing for a control unit to cold plate interface.

As shown inFIG.9, the groove is filled with an O-ring, which pressed against the cold plate, seals the application region of the PCM.FIG.9shows 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.9Ashows a general view on the control unit housing131with a groove134, O-ring710and a layer701of phase change TIM.FIG.9Bdepicts 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 aFIG.9Dshows an enlarged. detailed view of the O-ring pressed against the cold plate, sealing the PCM application region133.

FIG.10shows a stack of three segments or three rack assembly units100of the tray-tilting rack type, with the middle tray in an opened position. As can be seen, the segments can be replicated and stacked one upon another, to form more capacity of the rack, hence operate with larger number of control units. Due to this feature, the example rack design is a scalable solution.FIG.10Cshows an enlarged, detailed view of a gap between the O-ring and the cold plate when a tray is in opened position. This gap allows easy blade replacement, without the risk of damaging the layer of TIM on the control unit's top surface. The gap between TIM, O-ring, and the cold plate, visible for the opened tray, allowing safe insertion/removal of the control unit modules130, covered by a layer701of TIM700.