WO2008138922A1

WO2008138922A1 - Open frame cooling of an industrial computer

Info

Publication number: WO2008138922A1
Application number: PCT/EP2008/055818
Authority: WO
Inventors: Hans BJÖRKLUND; Krister Nyberg
Original assignee: Abb Technology Ag
Priority date: 2007-05-14
Filing date: 2008-05-13
Publication date: 2008-11-20
Also published as: DE212008000042U1; BRMU8803193U2; CN101657781A; RU94732U1

Abstract

The invention concerns a computer (16) having a frame with walls (24, 26) extending in a first direction and defining and enclosing a chamber (28) having an upper open end and a lower open end provided perpendicular to the first direction. One (26) of the walls is a heat sink and the chamber includes elements (32, 34, 36, 38, 40, 42, 44) of the computer. These elements include a main board (32) extending adjacent the heat sink wall in the chamber and having a first side facing inwards and a second opposite side facing the heat sink wall and comprising heat generating components (40, 42) placed for being cooled by the heat sink wall (26), and auxiliary boards (34, 36, 38) connected to the first side of the main board and being placed for extending at right angles to the main board.

Description

OPEN FRAME COOLING OF AN INDUSTRIAL COMPUTER

FIELD OF INVENTION

The present invention generally relates to the cooling of computers. More particularly, it relates to a computer using natural convection cooling.

BACKGROUND

High performance industrial computers, for instance in high-voltage power transmission systems, such as FACTS (Flexible Alternating Current Transmission System) and HVDC (High Voltage Direct Current) , get very hot and therefore need to be cooled.

Traditionally these and other types of computers are cooled using cooling fans that blow air horizontally through the computer box or computer frame via air filters. One problem with this type of cooling is the accumulation of dust inside the computer frame due to the cooling using forced air. The dust accumulation can be very heavy, even in quite clean control room environments .

There is therefore a need for cooling of computers, especially in an industrial environment, where the accumulation of dust in the computer is avoided.

One alternative to using a fan is to use convection cooling. This is described in some documents. US 5,243,493 does for instance describe a fanless convection cooling design for a personal computer in order to avoid the noise associated with a fan. The document describes that there is an enclosure for housing the personal computer. The enclosure defines a cavity. In this cavity major heat-producing components like the power supply and power transistors are provided at a top front connected to a heat sink. There is furthermore a master printed circuit board attached to a side in the rear of the cavity. Other printed circuit boards are attached vertically and perpendicularly to the master printed circuit board.

In "Natural Convection Enhancement of Channel Array in Conjunction with Wall Surface", Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2004, ITHERM '04, The Ninth Intersociety 1 - 4 June 2004, page 128 - 133, Kazuaki Yazawa describes passive cooling enhancement for consumer electronics thermal management in order to reduce noise that is otherwise associated with active cooling. The document describes the use of the so-called chimney effect using an enclosure wall for dissipating heat to the ambient. The wall includes a channel array. The inside of the wall is furthermore connected to an isothermal spreader. A heat source on a PWB is in turn connected to this spreader .

A similar solution for a PC is described in US 5,671,120 in order to remove the use of a fan, since a fan may be error prone and noisy. In this document a motherboard has ICs mounted on a first side and connections for ports and peripherals on an opposite second side. The motherboard is via said first side mounted to a heat sink plate. A heat conductive structure is provided between the ICs on the motherboard and the heat sink plate. The heat sink plate is furthermore a wall of the enclosure for the computer. A riser card is also provided on the second side of the motherboard in order to allow mounting of expansion cards to the motherboard.

In view of what has been described above there is therefore a need for providing a fanless cooling of a computer .

SUMMARY OF THE INVENTION

One object of the present invention is to provide a computer where the accumulation of dust is avoided during cooling.

This object is according to a first aspect of the present invention solved through a computer using natural convection cooling comprising: a frame with walls extending in a first direction and defining and enclosing a chamber having an upper open end and a lower open end provided perpendicular to the first direction, where one of the walls is a heat sink and the chamber includes elements of the computer, the elements comprising - a main board extending in the first direction in the chamber adjacent the heat sink wall and having a first side facing inwards towards the interior of the chamber and a second opposite side facing the heat sink wall and comprising heat generating components placed for being cooled by the heat sink wall, and at least one auxiliary board connected to the first side of the main board and being placed for extending in the first direction in the chamber as well as at right angles to the main board.

The present invention has a number of advantages. It avoids accumulation of dust in the frame. It has low maintenance requirements because of the removal of a fan. There is furthermore no need for air filters and problems associated with such filters, such as them getting clogged.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will in the following be described with reference being made to the accompanying drawings, where

fig. 1 shows a perspective view of an industrial computer mounted in a control room of a high-voltage power transmission system, fig. 2 shows a perspective view of the frame for the computer of fig. 1, fig.3 shows a view from above of a simplified computer according to a first embodiment of the present invention, fig. 4 shows a view from above of a simplified computer according to a second embodiment of the present invention, fig. 5, shows a view from above of a simplifed computer according to a third embodiment of the present invention, and fig. 6 shows a view from above of the frame for the computer being connected to a mounting plate.

DETAILED DESCRIPTION OF THE INVENTION

In the following, a detailed description of preferred embodiments of a computer according to the present invention will be given.

In fig. 1 there is shown a perspective view of an industrial computer 16 according to the present invention being mounted on a wall of a control room 10. The control room 10 is here a control room provided with air condition and therefore the room 10 is provided with an outlet 12 for drawing air from the room and an inlet 14 for providing the room with air. Here the outlet 12 is proved near the ceiling of the room 10 and the inlet 14 near the floor of the room 10. The computer 16 is furthermore provided in a frame 18, which is here mounted to a wall of the room 10 using a mounting plate 19.

Normally the computer in the control room would be mounted in a control cubicle with other components. Here the computer is shown as being mounted on the wall of the room in order to clearly show that it should not rest immediately on the floor, but should be placed above it. The reason for this will become apparent later on in the description. Fig. 2 shows a perspective view of the frame 18 in fig. 1. The frame 18, which is here provided as a cylinder with quadratic cross-section has a number of walls, which number is at least two and here four. One wall is a front wall and another is a back wall joined to each other by two side walls. The front wall is the furthermost wall in the figure, while the back wall is blocked in the figure. The walls here all extend in a first direction Dl, which in fig. 2 is a vertical direction. The front and back walls additionally extend in a second direction D2 perpendicular to the first direction Dl, while the side walls additionally extend in a third direction D3. The walls thereby define and enclose a chamber 28. The chamber 28 thus here has a quadratic cross-section and has an upper open end 20 and a lower open end 22. The lower open end 22 may be intended to face the floor of the control room, while the upper open end 20 may be intended to face the ceiling of the room. It should here be realized that each open end may be covered by a protective and shielding screen, for instance in the form of a wire mesh or a perforated sheet of a material, like for instance metal. In this way the upper open end 20 is provided in a first plane extending in the second and third directions D2 and D3 and is thus perpendicular to the first direction and the lower open end 22 is provided in a second plane extendin in the second and third directions D2 and D3, which second plane is thus also perpendicular to the first direction as well as parallel with the first plane . According to the present invention one of the walls, here the back wall that may be intended to a face a wall of the room, is provided in the form of a heat sink. It should here be realized that the frame 18 may have any type of suitable cross-section, like quadratic and triangular and that any wall may provide a heat sink. It is advantageous if the heat sink is provided by a wall lacking curvature. This wall would then extend in the first direction Dl as well as one other direction, the second or third direction D2 or D3, and thus be perpendicular to the first and second planes. However, the other walls of the frame may have a curvature, for instance like half an elliptical or half a circular cylinder.

Fig. 3 shows a view from above of a simplified computer 16 according to a first embodiment of the present invention. The chamber 28 is here shown surrounded by four walls, including the front wall 24 and the back wall 26. In the figure it can clearly be seen that the back wall 26 is also a heat sink. The heat sink wall 26 includes a rectangular plate provided with fins on its outer side facing away from the chamber 28. These fins extend in the first direction and thus stretch from the lower open end to the upper open end. These fins are furthermore spaced from each other in the second direction. This spacing of the fins from each other define a number of channels 30 in the heat sink between the fins, which channels thus each run in the first direction from the lower open end to upper open end of the frame. The heat sink wall 26 is preferably made of a suitable cooling material, for instance aluminum. Inside the chamber 28 there is furthermore provided a main board 32, often denoted motherboard. This main board 32 is provided inside the chamber 28 and extends in the first direction and here also in the second direction adjacent and in parallel with the heat sink wall 26 and thus also stretches from the lower to the upper open end. This main board 32 has a first side that faces inwards towards the interior of the chamber 28 and thus towards the centre of the chamber 28 as well as a second opposite side that faces the heat sink wall 26. To the first side of the main board 32 there are connected first, second and third auxiliary boards 34, 36 and 38, often denoted PCI (Peripheral Component Interconnect) boards. These auxiliary boards 34, 36, 38 are placed for extending in the first direction and here also in the third direction in the chamber 28, and thus at right angles to the main board 32. and therefore also stretch from the lower to the upper open end of the chamber.

On the second side of the main board 32 there are provided a number of heat generating components 40 and 42, of which only two are shown. These components 40 and 42 may include a CPU 40 and a chipset 42. Other components that do not generate that much heat may be provided on the first side. The auxiliary boards do also include components, but should in this embodiment of the invention not include components that generate too much heat. These heat generating components 40 and 42 are here provided in direct contact with the heat sink wall 26. Finally there is provided a power supply module 44 providing power to the whole computer. This power supply module 44 is also connected to the heat sink 26.

When the frame is correctly mounted in a room, such as in a control room, the upper open end of the frame faces the ceiling and the lower open end faces the floor. This also means that elements of the computer extending in the first and second directions as well as elements extending in the first and third direction are vertically oriented, while the open ends that extend in the second and third directions are horizontally oriented. Here the first direction is therefore a vertical direction. When the computer is operated in such a situation with such an orientation, cooling will take place automatically through self-convection, i.e. using the chimney principle. This means that cool air will flow in through the lower open end of the frame, up past the vertically arranged auxiliary boards and the vertically arranged main board and thus cool the components on them and thereafter exit through the upper open end of the frame. At the same time cool air will also flow naturally upwards in the channels of the heat sink from the floor towards the ceiling of the room and thereby help in cooling it and the components and modules directly connected to it.

In this way no fan is required. The stream of air created is furthermore not strong enough to make dust enter the chamber. There is thus no accumulation of dust. Since no fan is needed there is also no need for any air filters. Further advantages of this solution are therefore that the filter cleaning is removed and no service due to a failed fan is needed. It is possible to improve the design shown in fig. 3. One way to improve the design will now be described in relation to fig. 4, which shows a view from above of a simplified computer 16 according to a second embodiment of the present invention.

Here there are only two changes made in relation to fig. 3 and that is that there is a further heat generating component 48 on the third auxiliary board

38, which component is connected to the heat sink via a heat pipe 50 and that there is a heat spreader 46 provided between the heat generating components 40 and 42 of the main board 32 and the heat sink wall 26. The heat pipe 50 is at a first end connected to the component 48 and at a second end connected to the heat sink wall 26.

A heat pipe is, as is well known in the art, a pipe including a fluid. The liquid in the first end is originally provided in liquid form but turns into vapor because of the heating. This gas naturally flows to the second end where it condenses to liquid, which then falls or moves by capillary action back to the first end. This is advantageous to use when there are heat generating components that it is not possible to place close to the heat sink, for instance with components on the auxiliary board 38.

A heat spreader is, as is also well-known within the art, a plate for heat removal that can be used in relation to components and various modules, such as COM express and ETX modules. The heat spreader is here arranged to adapt the mechanical properties of the components to that of the heat sink.

It should here be realized that the present invention may be provided with only one of these further heat removal elements, heat spreader or heat pipe. It should also be realized that more heat pipes may be provided in case there are further heat generating components on an auxiliary board needing cooling.

The cooling of a computer may be aided by the air conditioning provided in the control room. This external cooling of the room thus enhances the natural cooling provided through the present invention.

However, this air conditioning may in some very rare instances fail. Because of this the room temperature may rise above a level, where the natural cooling, especially of the auxiliary boards, is not sufficient. In this case a forced cooling on demand function may be provided. One way to provide such forced cooling on demand will now be described in relation to fig. 5, which shows a view from above of a simplified computer 16 according to a third embodiment of the present invention. Here there is only one change made in relation to fig. 3 and that is that there is a fan 52 provided, which is connected to a temperature sensor 54.

The fan 52 may here be arranged to be activated only at an extremely high temperature in the chamber, which temperature is sensed by the temperature sensor 54. The fan 52 may here only be arranged to be active during a short period of time in order to quickly lower the temperature in the chamber. Such a short and limited forced air cooling has a very limited impact on the dust accumulation within the frame. This type of cooling on demand furthermore enhances the operating security of the computer frame.

As mentioned above an air conditioning system associated with the room may be used for enhancing the natural cooling of the computer. In order to describe this situation in more detail, reference is again being made to fig. 1 together with reference to fig. 6, which shows a view from above of the frame 18 of the computer being connected to the mounting plate 19.

A mounting plate 19 may thus be connected to the frame 18 and may then extend in the first direction as well as the second or third direction. In the present example it is furthermore connected to the heat sink wall 26 of the frame. The plate 19 is here provided in parallel with and distanced from the heat sink wall 26 in a direction away from the centre of the chamber 28. This is done in order not to disturb air flow through the channels of the heat sink wall 26. This plate 19 is furthermore placed perpendicular to the first and second planes in which the upper and lower open ends of the frame 18 are provided. It furthermore extends beyond these ends and their planes, as can be seen in fig. 1. In this way it is guaranteed that the frame 18 is mounted above the floor of the room 10. Therefore it is ensured that air blown by the air conditioning system 12, 14 over the floor will reach the frame and cool the computer. When the frame is mounted in a cubicle, this cubicle may be provided with air inlets at the bottom for receiving such air from the air conditioning system. This has the further advantage of increasing the reliability of the computer even further.

There has thus been described a computer which has the advantage of avoiding accumulation of dust in the frame. In a computer that uses forced air cooling this problem may occur as soon as after a year.

The invention also provides a number of further advantages. It has low maintenance requirements because of the removal of a fan. There is furthermore no need for air filters and problems associated with such filters, such as them getting clogged. In the case of letting the air from the air conditioning system pass through the frame via the floor there is provided a very effective cooling with improved reliability.

The present invention may be further varied in a few ways in addition to those already mentioned. The power supply unit may be provided separately as shown in fig. 3 - 5 or it may be provided on the main board. In the drawings three auxiliary boards were shown. It should be realized that there may be more or fewer depending on how many are needed. It is furthermore clear that the frame may be mounted upside down with essentially the same function as was described above. Therefore the upper open end of the chamber may become the lower open end of the chamber and vice versa. The invention was furthermore described in relation to an industrial computer. It should be realized that the present invention can be used for any computer, for instance a PC. It is of course also evident that it does not have to be used in combination with an air-conditioned room.

From the foregoing discussion it is evident that the present invention can be varied in a multitude of ways. It shall consequently be realized that the present invention is only to be limited by the following claims .

Claims

1. A computer (16) using natural convection cooling comprising: - a frame (18) with walls (24, 26) extending in a first direction (Dl) and defining and enclosing a chamber (28) having an upper open end (20) and a lower open end (22) provided perpendicular to said first direction (Dl), where one (26) of said walls is a heat sink and said chamber includes elements (32, 34, 36, 38, 40, 42, 44; 52, 54) of the computer, said elements comprising a main board (32) extending in the first direction in the chamber adjacent said heat sink wall and having a first side facing inwards towards the interior of the chamber and a second opposite side facing said heat sink wall and comprising heat generating components (40, 42) placed for being cooled by said heat sink wall (26), and at least one auxiliary board (34, 36, 38) connected to the first side of the main board and being placed for extending in said first direction in said chamber as well as at right angles to said main board.

2. A computer (16) according to claim 1, wherein the heat generating components (40, 42) of the main board (32) are placed in direct contact with the heat sink wall (26) .

3. A computer (16) according to claim 1, wherein the heat generating components (40, 42) are placed in contact with the heat sink wall via a heat spreader (46) .

4. A computer (16) according to any previous claim, wherein the heat generating components (48) are placed in contact with the heat sink wall via a heat pipe (50) .

5. A computer (16) according to any previous claim, further comprising a power supply module (44) placed in direct contact with said heat sink wall (26) .

6. A computer (16) according to any previous claim, further comprising a cooling fan (52) arranged to be activated at certain temperatures in the chamber.

7. A computer (16) according to any previous claim, further comprising a protective and shielding screen provided over the upper and/or lower open ends.

8. A computer (16) according to claim 7, wherein the protective and shielding screen is provided through a wire mesh or a perforated sheet.

9. A computer (16) according to any previous claim, further comprising a mounting plate (56) for mounting of the computer, said mounting plate being connected to said frame, and extending in said first direction beyond said first and second open ends.

10. A computer (16) according to any previous claim, wherein said first direction is a vertical direction when said computer has been mounted.