APPARATUS FOR SUPPLYING COOLING FLUID

Abstract: The apparatus circulates cooling fluid through a plura­ lity of cooling modules (11) for cooling electronic components (33), such as IC or LSI. A plurality of cooling fluid supply systems are independently connected to the respective cooling modules (11), and each of the supply systems includes a fluid line (7a, 7b, ...) connected to a single tank (2) containing cooling fluid and provided with a pump (3) and a heat exchanger (5), so that the cooling fluid in the tank is circulated through the respective cooling modules (11) and returned to the tank (2), in which the cooling fluid is then mixed.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a cooling system, and more particularly, to an apparatus for compulsorily supplying a cooling fluid or coolant, such as water, fluorocarbon liquid, or the like, for circulation through a plurality of cooling modules for cooling electronic components, such as integrated circuits (IC), large-scale integrated circuits (LSI), or the like, mounted on printed circuit boards for computers. 2. Description of the Related Art Electronic components, such as IC s, LSI s or the like, are now very highly sophisticated, and thus the density of such electronic components that can be mounted on a printed circuit board has increased. Accordingly, it has become very important to effectively cool these electronic components, since the amount of heat generated therefrom has correspondingly increased, and thus various compulsory cooling systems using a cooling media having a strong cooling capacity have been proposed. U.S. Patent No. 3,481,393 discloses a modular cooling system in which a plurality of modular cooling chambers are connected in series, each having a flat heat conductive side which can be attached to a flat backplate of an electronic module, to provide a good heat conduction to a cooling fluid circulating in the cooling chambers. Flexible conduits are connected between the outlet and inlet of the successive series-connected cooling chambers, so that the chambers can be attached to electronic modules of different heights and can be easily detached from the backplate without interrupting the coolant fluid flow therethrough, to enable the underlying electronic module to be tested, repaired or replaced without affecting the cooling of other modules in the series. In this prior art, however, only a single supply system including a pump and a heat exchanger is provided for the plurality of modular cooling chambers, and therefore, such a coolant supplying system must be provided with a pressure or flow capacity sufficient to cover all of the modular chambers, even if the number of such chambers is increased. Also, it is impossible to adjust the pressure and temperature of the coolant to suit individual modular chambers. U.S. Patent No. 3,512,582 discloses an immersion cooling system for modularly packaged components, in a plurality of modular units are connected to a vessel containing a low-boiling-point liquid, so that an auxiliary cooling chamber of each modular unit is filled with the low-boiling point liquid. Each auxiliary chamber contains heat generating components which are cooled by the low-boiling-point liquid in which a nucleate boiling takes place, and a separate heat exchanger located in each auxiliary chamber removes the heat from the low-boiling-point liquid. The vessel provides a common venting and degassing of, and a pressure for, the individual cooling chambers. U.S. Patent No. 3,774,677 discloses a cooling system in which a spare condensing and cooling arrangement is provided in a liquid cooling system to condense vapors generated by nucleate boiling at a heat source. A two-phase flow is caused between the heat source, in the form of liquid and boiling vapors, and the spray condensing and cooling means, where the vapors are condensed by a cooler spray contained therein. The amount of spray, and accordingly the amount of vapor condensation, is controlled by a servo arrangement which regulates the pressure within the system. SUMMARY OF THE INVENTION An object of this invention is to provide an apparatus for circulating a coolant through a plurality of cooling modules for cooling electronic components, wherein the pipe construction is easily arranged in accordance with the cooling capabilities of the respecttive cooling modules. Another object of this invention is to provide an apparatus for circulating the coolant, and obtaining an effective operation of the heat exchangers and an easy observation and maintenance of the temperature, flow, nature, or the like of the coolant. According to this invention, there is provided an apparatus for supplying cooling liquid for circulation through a plurality of cooling modules for cooling electronic components, as defined in claim 1. The tank may be provided with a liquid cleaning means and/or a mixing promoting means. In the coolant supply apparatus of this invention, the cooling fluid is supplied independently to the respective cooling systems, in such a manner that the pressure and flow of the cooling fluid in each cooling system are not affected by the other cooling systems, but is in accordance with the needs of the cooling module in question in the system. After flowing through the cooling module and carrying out the desired cooling, the cooling fluid in the respective cooling systems is collected in the tank and mixed therein. Therefore, the pressures and temperatures of the cooling fluid after carrying out the desired cooling in the respective cooling systems is made uniform, and the cooling liquid is then redistributed to the respective cooling systems. The removal of foreign substances, cleaning of the cooling fluid, monitoring the temperature thereof, and the like can be concentratedly carried out in the tank. Accordingly, the heat exchangers in the respective cooling systems can be effectively operated, since the cooling fluids are independently supplied to the respective cooling systems in accordance with the needs of the individual cooling modules, and further the observation or maintenance of the temperature, flow, nature, or the like of the cooling fluid can be easily carried out. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram illustrating a pipe arrangement of the cooling fluid supply apparatus according to this invention; Figure 2 is a perspective view of a cooling fluid supply system; Figure 3 is a perspective view of an electronic system; Figures 4A, 4B, and 4C illustrate embodiments of the mixing promoting means used in the apparatus of this invention; and, Figures 5A and 5B illustrate embodiments of the cooling fluid cleaning means used in the apparatus of this invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a cooling fluid supply system, generally indicated by a reference numeral 1 in Fig. 1, includes a common mixing tank 2 having a relatively large volume. The mixing tank 2 is a closed reservoir tank provided with a pressure release means (not shown), a strainer 20 comprising a metal sieve having a predetermined mesh, a mixing promoting means, and a liquid cleaning means, as described later. The tank 2 contains a coolant or cooling fluid, such as pure water including fluorocarbon or the like. The liquid supply system 1 comprises a plurality of supply lines 7a, 7b, ... arranged independently and in parallel to each other. Each of the fluid supply lines 7a, 7b, ... comprises, at the downstream side of the strainer 20 of the mixing tank 2, a liquid pipe 6 on which a pair of pumps 3 and check valves 4, a heat exchanger 5, and a coupling 8 are arranged in series, and at the upstream side of the strainer 20, each of the fluid lines 7a, 7b, ... comprises a return pipe 6 providing with a coupling 9. Further, an electronic system, generally indicated by a reference numeral 10 in Fig. 1, comprises a plurality of supply lines 17a, 17b, ... arranged independently and in parallel to each other and connected to the supply lines 7a, 7b, ..., respectively, via external liquid pipes 15 and 16. Each of the supply lines 17a, 17b, ... includes a pipe 12 provided with a single 11oling module 11a, 11b, ... and couplings 13 and 14, which are connected to the couplings 8 and 9 via the external pipes 15 and 16, respectively, to constitute a plurality of cooling fluid circulation lines. In each of the circulation lines, the pump 3 and the heat exchanger 5 are selected in such a manner that the capacities, flows, or pressures thereof are sufficient to cover the amount of heat, number of elements in the cooling module 11, and the like. In Fig. 2, one of the embodiments of the cooling fluid supply system 1 is illustrated in a perspective view, in which the above-mentioned single mixing tank 2, respective pairs of pumps 3, and respective heat exchangers 5 are accommodated in a locker case 40. A main supply pipe 31 is constituted by a plurality of pipe sections which are connected to each other in series by flanges 32. One end of the main supply pipe 31 is connected to the mixing tank 2. Thus, the main pipe 31 may have a desired length in accordance with the number of the cooling fluid supply lines 6, i.e., the number of cooling modules 11. In Fig. 2, reference numerals 8 and 9 indicate coupling; 15, the external supply pipes; 16, the external return pipes; and 29(30), a liquid cleaning means as will be described later. The main supply pipe 31 is connected to and opened at the center of the bottom wall of the mixing tank 2. On the other hand, the plurality of return pipes ′ are connected to the bottom wall of the mixing tank 2 and arranged to open therearound. Such an arrangement of the main supply pipe 31 and the plurality of return pipes 6′ is effective to promote the mixing of the cooling water in the mixing tank 2. Fig. 3 is a perspective view illustrating one of the embodiments of the electronic system 10, in which a desired number of cooling modules 11 are provided in accordance with the number of the printed circuit boards 33 on which various heat generating electronic elements, such as, IC or LSI, are mounted. Each cooling module 11 comprises a cooling plate which is known in the prior art and connected to the external supply and return pipes 15 and 16 via the couplings 13 and 14, respectively. Figures 4A to 4C illustrate the other embodiments of the cooling water mixing promoting means provided in the mixing tank 2. In the embodiment shown in Fig. 4A, provided at the inlet side of the mixing tank 2 is a cylindrical header 21 to which the return pipes 6a′ , 6b′ , ... of the respective supply lines 7a, 7b, ... are connected. Similarly, provided at the outlet side of the mixing tank 2 is a cylindrical header 22 to which the liquid pipes 6a, 6b, ... are connected. Each of the cylindrical headers 21 and 22 has a volume smaller than that of the mixing tank 2, and accordingly, in this embodiment, the mixing of the cooling fluid is promoted by the differences in volume of the mixing tank 2 and the cylindrical headers 21 and 22. In the embodiment shown in Fig. 4B, the return pipes 6a′, 6b′, ... of the respective supply lines 7a, 7b, ... (not shown) are connected, alphabetical order, from the top to the bottom of the mixing chamber 2. Conversely, the respective distributing pipes 6a, 6b, ... are connected, in alphabetical order, from the bottom to the top of the mixing tank 2. Therefore, in this embodiment, the streams of cooling fluid flowing into and out of the tank 2 cross and impinge on each other, whereby the mixing of the cooling water is promoted. In the embodiment of Fig. 4C, the mixing tank 2 is partitioned into upper and lower chambers 2a and 2b by a control plate 23 having holes or openings 24 of predetermined sizes for promoting the mixing of the cooling water. The return pipes 6a′, 6b′, ... are connected to the upper chamber 2a and the distributing pipes 6a, 6b, ... are connected to the lower chamber 2b, whereby the streams of cooling fluid flowing into and out of the tank 2 cross and impinge on each other when passing through the openings 24, and thus the mixing of the cooling water is promoted by the control plate 23. Embodiments of the liquid cleaning means will now be described with reference to Figs. 5A and 5B. In the embodiment of Fig. 5A, a pipe 27 is connected at both ends to the mixing tank 2 via couplings 25 and 26, respectively, and is provided with a exclusive-use pump 28, a micro-filter 29 having a predetermined mesh such as 10.45 µm, and an ion exchanger 30. This pipe 27 may be connected to the mixing tank 2 permanently or occasionally, for example, during maintenance or the like. When the pump 28 is operated, the cooling fluid within the mixing tank 2 is circulated through the micro-filter 29 and the ionic exchanger 30, whereby the cooling fluid for all of the liquid supply systems is thoroughly cleaned. In the embodiment of Fig. 5B (also shown in Fig. 2), a pipe 27 provided with a micro-filter 29, an ion exchanger 30, and a flow control valve 31 is connected at one end to the mixing tank 2 via a coupling 25 and connected at the other end to the downstream side of the pumps 3 in the pipe 6 of one of the cooling fluid supply systems (e.g., 7a) via a coupling 26. In this embodiment, a part of the cooling fluid flows from the cooling fluid supply system 7a to the ion exchanger 30 and the micro-filter 29 via the control valve 31, so that the cooling fluid is cleaned without the need for an exclusive-use pump. In the liquid cleaning means as shown in Figs. 5A and 5B, either the micro-filter 29 or the ion exchanger 30 may be provided.

Claims: An apparatus for supplying cooling liquid for circulation through a plurality of cooling modules (11) for cooling electronic components, comprising: a single tank (2) for containing cooling fluid; a plurality of cooling fluid supply systems independently connected to said plurality of cooling modules; each one of said cooling fluid supply systems including a fluid line (6, 15, 12, 16) connected to said tank (2) each said fluid line having its own pumping means (3) and a heat exchanger (15) that is separate from said cooling module (11) to circulate the cooling fluid from said tank (2) through said respective cooling modules (11) and back to said tank, in which the cooling fluid is then mixed. An apparatus according to claim 1, wherein said tank (2) containing said cooling fluid is provided with a liquid cleaning means (28-30). An apparatus according to claim 2, wherein said liquid cleaning means (28-30) comprises a further fluid line (27) connected to said tank (2) provided with a pump (28) and a liquid cleaning element (29, 30), so that said cooling fluid from said tank is circulated through said liquid cleaning element (29, 30) when returned to said tank. An apparatus according to claim 3, wherein said liquid cleaning element comprises at least one of a filter (29) for removing foreign substances from the cooling fluid and an ion exchanger (30) for neutralizing metal ions contained in the cooling fluid. An apparatus according to claim 3, wherein both ends of said further fluid line (27) are connected to said tank (2) and said pump (28) of said liquid cleaning means is an exclusive-use pump. An apparatus according to claim 3, wherein said further fluid line (27) comprises a pipe provided with said liquid cleaning element and having one end connected to said tank (2) and the other end connected to the fluid line of one of said cooling fluid supply systems, at a point downstream of the pump (3) of said cooling fluid supply system, so that said pump not only circulates the cooling fluid through said cooling fluid supply system, but also circulates a part of the cooling fluid through said pipe of said further fluid line (27). An apparatus according to claim 1, wherein said tank (2) is provided with a mixing promoting means. An apparatus according to claim 7, wherein said mixing promoting means comprises: a control plate (23) partitioning said tank into first and second chambers (resp. 2a, 2b) which are communicated with each other via a plurality of openings (24) provided in said control plate; and, the supply and return pipes (resp. 6', 6) of each of said liquid supply systems being connected to said first and second chambers, respectively. An apparatus according to claim 7, wherein said mixing promoting means comprises supply and return pipes (resp. 6', 6) of said fluid supply systems connected to said tank at different positions. An apparatus according to claim 7, wherein said mixing promoting means comprises a header (21) having one side connected to said tank (2) and the other side connected to a plurality of supply pipes (6) of said respective fluid supply systems. An apparatus according to claim 7, wherein said mixing promoting means comprises a header (22) having one side connected to said tank and the other side connected to a plurality of return pipes (6') of said respective fluid supply systems. An apparatus according to claim 7, wherein said mixing promoting means comprises: a first header (21) having one side connected to said tank (2) and the other side connected to a plurality of supply pipes (6) of said respective fluid supply systems; and a second header (22) having one side connected to said tank (2) and the other side connected to a plurality of return pipes (6') said respective fluid supply systems. An apparatus according to claim 7, wherein said mixing promoting means comprises: said mixing tank (2) having a cylindrical chamber and a bottom wall; a main supply pipe (6) connected to and opened at a center of said bottom wall of the mixing tank, a plurality of supply pipes of said fluid supply systems being distributed from said main supply pipe; and, a plurality of return pipes (6') of said fluid supply systems being connected to said bottom wall of the mixing tank and opened therearound.

Inventors: KAWASHIMA, HISASHI, OKADA, TSUGUO, YAMAMOTO, HARUHIKO
Applicants: FUJITSU LIMITED
Application year: 1988
Main classification: H05K7
IPC codes: H05K7, H01L23