Coolant cartridge

Abstract

There is provided a coolant cartridge (8) comprising: a housing (34) having at least one wall enclosing an internal space; a first chamber (11) and a second chamber (12) arranged within the internal space, wherein the first chamber (11) is for storage of replacement coolant, and the second chamber (12) is for storage of used coolant; an outlet (31) in fluid communication with the first chamber (11) for dispensing the replacement coolant; and an inlet (32) in fluid communication with the second chamber (12) for receiving the used coolant. The first chamber (11) is isolated from the second chamber (12) such that the replacement coolant and the used coolant do not mix within the coolant cartridge. Each of the first and second chambers (11, 12) is at least partially defined by a movable or flexible wall (36, 38).

Description

[0001] COOLANT CARTRIDGE

[0002] Technical Field

[0003] This disclosure relates to a coolant cartridge, a cooling system, a method of exchanging coolant of a cooling system using a coolant cartridge and a method of filling the cooling system with coolant. More particularly, but not exclusively, the coolant cartridge and the cooling system are suitable for use with an industrial printing or marking machine, such as an industrial laser marking machine that can be integrated within a production line.

[0004] Background

[0005] Figure 1 is a schematic representation of an exemplary laser marking machine (hereinafter, “laser marker”) 100’. The laser marker 100’ includes a laser beam generator 102’ which works in pulsed or continuous operation to produce a laser beam 110’ with a small diameter. For example, the laser beam 110’ may be an infrared invisible laser beam. The laser beam 110’ is expanded by means of a two-lens telescope 103’, thereby generating an expanded laser beam 120’. The expanded laser beam 120’ reaches a marking head 104’ where movable mirrors 130’ deflect the expanded laser beam 120’. The deflected laser beam is focussed onto a product surface 107’ by a laser scan lens 105’ to produce a marking on the product surface 107’. Generally the marking is produced at the focus 106’ of the lens 105’. The control of the laser beam generator 102’ and the marking head 104’ is performed by a controller card in a supply unit 10T.

[0006] The laser beam generator 102’ generates heat during operation of the laser marker 100’ and requires efficient cooling. An industrial laser marker is fitted within a production line and typically operates at a high power level with high intensity. Therefore, the laser beam generator 102’ of an industrial laser marker can easily overheat. Providing efficient cooling to the laser beam generator 102’ is useful for maximising the life span and reducing the maintenance costs of an industrial laser marker. In addition, the trend towards miniaturization increases the need for efficient cooling even further.

[0007] It is known to cool laser markers by air. For example, cooling fin(s) may be attached to the laser beam generator, and a fan is then used to generate an air stream which passes through the cooling fins. This approach is generally insufficient for high-power or compact laser markers.

[0008] Liquid cooling can be a better solution when it comes to heat removal from small volumes. Via the liquid, heat can be transported to a heat sink at a certain distance from a heat source and then be released to the environment. The heat-transporting liquid (i.e. , the coolant) plays a role in the cooling process and it is desirable to fulfil certain requirements, such as prevention of corrosion, avoidance of freezing and boiling, and lubrication of pump components, etc. Such properties of the coolant can change over time, as the coolant interacts with the piping, constituents may evaporate through the piping, parts may be lost through small leaks, etc. It is therefore desirable to exchange the coolant in regular intervals to maintain the cooling system's performance.

[0009] The coolant exchange processes could be a manual process that requires several steps, such as, removing the cooling system from its installation location or connecting hoses to the system, obtaining and positioning a suitable container that can take the used coolant, opening valves in the correct order, waiting until all the used coolant is drained from the system, closing valves, filling the system with new coolant to the correct level, returning everything to the correct locations and disposing of the used coolant. Besides numerous sources of errors that can be made during this process by potentially unexperienced operators, the process itself has numerous sources of errors, such as, incomplete drainage of the system or remaining air pockets when refilling (which may depend on the installation situation and the relative heights of the cooler, the apparatus to be cooled and the hoses in-between). In addition to the error-prone process it is also very time consuming and therefore results in long downtimes of industrial equipment, which could lead to high costs. Furthermore, the manual coolant exchange processes involves easy accessibility to the coolant (e.g. when draining the coolant to a container), and the coolant can easily be spilled and thus become a risk to the operator's health and the environment.

[0010] It is therefore desirable to equip machinery with a coolant exchange mechanism that is less prone to error, quicker, requires less operator interaction, and avoids direct access to the coolant. It is an object of this disclosure, among others, to provide such a coolant exchange mechanism. Summary

[0011] According to a first aspect of the present disclosure, there is provided a coolant cartridge comprising: a housing having at least one wall enclosing an internal space; a first chamber and a second chamber arranged within the internal space, wherein the first chamber is for storage of replacement coolant, and the second chamber is for storage of used coolant; an outlet in fluid communication with the first chamber for dispensing the replacement coolant; and an inlet in fluid communication with the second chamber for receiving the used coolant; wherein the first chamber is isolated from the second chamber such that the replacement coolant and the used coolant do not mix within the coolant cartridge; and wherein each of the first and second chambers is at least partially defined by a movable or flexible wall.

[0012] Advantageously, the coolant cartridge allows the coolant used within a cooling system to be readily changed, by supplying replacement coolant to the cooling system from the first chamber and receiving used coolant from the cooling system into the second chamber. The use of the coolant cartridge enables a coolant exchange process which is quick and less prone to error as it requires a reduced amount of user interaction. Further, during the coolant exchange process, an operator does not need to directly access the coolant (which may be a hazard to the operator and / or the environment).

[0013] The coolant cartridge may be for use to change coolant in a liquid cooling system.

[0014] The first chamber may store replacement coolant which comprises a liquid.

[0015] The second chamber may be configured to receive the used coolant from an initially empty state.

[0016] Further or alternatively, the coolant cartridge may be for use to fill a liquid cooling system with coolant. When the coolant cartridge is used to fill the liquid cooling system, the second chamber may be configured to receive air from the initially empty state. The air may be from an internal space of the liquid cooling system.

[0017] The term “at least partially defined” means that the first / second chamber may be wholly or partially surrounded by the respective movable or flexible wall. The movable / flexible wall allows a volume of each of the first and second chambers to be changeable (e.g., in response to dispensing replacement coolant from the first chamber and / or receiving used coolant by the second chamber).

[0018] The movable wall may be a rigid wall which is movable (e.g., slidable) with respect to the at least one wall of the housing.

[0019] The movable or flexible wall may be an internal wall enclosed by the at least one wall of the housing. Alternatively, the movable or flexible wall may be a part of the at least one wall of the housing.

[0020] The at least one wall of the housing may be rigid. Alternatively, at least a part of the at least one wall may be flexible.

[0021] It would be understood that each of the inlet and outlet may be sealed so that coolant does not leak from the first and second chambers inadvertently.

[0022] The movable or flexible wall may be configured such that each of the first and second chambers is expandable to occupy substantially an entire volume of the internal space.

[0023] The movable or flexible wall may be enclosed by the at least one wall of the housing.

[0024] The first chamber may be at least partially defined by a first movable or flexible wall, and the second chamber may be at least partially defined by a second movable or flexible wall. The first movable or flexible wall may be distinct from the second movable or flexible wall.

[0025] Alternatively, each of the first and second chambers may be at least partially defined by a common movable or flexible wall. In other words, the first movable or flexible wall may be the same as the second movable or flexible wall.

[0026] The coolant cartridge may have a unitary structure. The term “unitary structure” means that the coolant cartridge can be handled as a single-piece item, which has a single housing enclosing both the first chamber and the second chamber. The coolant cartridge may be free from any electric pump. In other words, the coolant cartridge is a passive device and requires an external pump to initiate a coolant exchange process.

[0027] The coolant cartridge may be configured such that an increase in a volume of the second chamber causes a decrease in a volume of the first chamber.

[0028] In other words, the increase in the volume of the second chamber applies a pressure to wall(s) that at least partially define the first chamber, and the pressure pushes the replacement coolant out of the first chamber, thereby resulting in a decrease in the volume of the first chamber.

[0029] The coolant cartridge may be configured such that a decrease in a volume of the first chamber causes an increase in a volume of the second chamber.

[0030] Advantageously, the increase in the volume of the second chamber reduces the pressure within the second chamber, which in turn sucks the used coolant into the second chamber.

[0031] The coolant cartridge may be adapted to prevent ambient air from entering the internal space from outside the coolant cartridge. In other words, the coolant cartridge may be ventless. The housing of the coolant cartridge may not contain any vent which allows ambient air to enter the internal space.

[0032] A total volume of the internal space may remain constant. A total volume of the internal space may be of the order of several litres.

[0033] The second chamber may be initially empty.

[0034] The first chamber may initially occupy substantially an entire volume of the internal space. The expression “initially” used in the present disclosure refers to a state (e.g., brand new, pristine, unopened, unused, as-shipped or factory-fresh) of the coolant cartridge before it is used.

[0035] The coolant may be water or oil.

[0036] The coolant may comprise at least one additive, such as an anti-frozen additive, anticorrosion additive and / or an anti-algae additive.

[0037] According to a second aspect of the present disclosure, there is provided a method of exchanging coolant of a cooling system using a coolant cartridge, wherein the cooling system is for cooling a heat source of an apparatus and comprises: an interface for thermally coupling to the heat source of the apparatus; a heat sink for thermally coupling to the heat source or the interface; a pump; a first coolant-exchange port; and a second coolant-exchange port, wherein the coolant cartridge comprises a housing having at least one wall enclosing an internal space; a first chamber and a second chamber arranged within the internal space, wherein the first chamber is configured to store replacement coolant, and the second chamber is for storage of used coolant; an outlet in fluid communication with the first chamber; and an inlet in fluid communication with the second chamber, wherein the method comprises: coupling the first coolant-exchange port of the cooling system to the outlet of the coolant cartridge; coupling the second coolant-exchange port of the cooling system to the inlet of the coolant cartridge; and operating the pump to cause replacement coolant to flow along a coolant exchange path from the first chamber, through the first coolant-exchange port, the heat sink and the second coolant-exchange port, to the second chamber.

[0038] The coolant exchange process as described above is quick, safe and less prone to error. In particular, the coolant exchange process is quicker than existing manual processes and reduces the downtime of the apparatus. Further, the coolant exchange process is less prone to error because it requires a reduced amount of user interaction. In addition, the coolant exchange process avoids direct user contact with coolant, and reduces the risks of spilling coolant, thereby protecting both the user and the environment. The expression “coupling” refers to fluidly coupling such that a fluid communication is established between the coupled elements, and encompasses that one or more intervening elements may exist between the coupled elements.

[0039] The expression “thermally coupling” means that thermal energy (e.g., heat) is able to flow from the heat source to the heat sink. Intermediate elements may exist along a thermal conduction path between the heat source to the heat sink.

[0040] The interface may comprise a system coolant outlet for coupling to a coolant inlet of the apparatus and a system coolant inlet for coupling to a coolant outlet of the apparatus.

[0041] The system coolant outlet of the cooling system may be coupled to the coolant inlet of the apparatus; and the system coolant inlet of the cooling system may be coupled to the coolant outlet of the apparatus. Accordingly, the coolant exchange path may pass through the system coolant outlet of the cooling system, the coolant inlet of the apparatus, the coolant outlet of the apparatus and the system coolant inlet of the cooling system. In this way, coolant within the piping of the apparatus can also be exchanged during the coolant exchange process.

[0042] Further or alternatively, the interface may also comprise a cooling block for attaching to the heat source.

[0043] The heat sink may be in fluid communication with the interface. In other words, coolant may flow between the heat sink and the interface.

[0044] The heat sink may be for thermally coupling to both the heat source and the interface.

[0045] The replacement coolant may comprise a liquid.

[0046] Operating the pump may comprise operating the pump to draw the replacement coolant from the first chamber, through the first coolant-exchange port, and into the cooling system, and to cause used coolant within the cooling system to flow from the cooling system, through the second coolant-exchange port, into the second chamber. The method may be a method of filling the cooling system with coolant by using the coolant cartridge. In such a method, operating the pump may comprise operating the pump to draw the replacement coolant from the first chamber, through the first coolantexchange port, and into the cooling system, and to cause air within the cooling system to flow from the cooling system, through the second coolant-exchange port, into the second chamber.

[0047] The coolant cartridge (in particular the first chamber) may be positioned at a higher elevation than the first coolant exchange port.

[0048] The method may further comprise: operating the apparatus concurrently with operating the pump. In other words, the apparatus being cooled by the cooling system may continue with its operation during the coolant exchanging / filling process of the cooling system.

[0049] The method may further comprise: stopping the operation of the pump; decoupling the first coolant-exchange port of the cooling system from the outlet of the coolant cartridge; and decoupling the second coolant-exchange port of the cooling system from the inlet of the coolant cartridge.

[0050] The operation of the pump may be stopped in response to an exhaustion of the replacement coolant from the first chamber.

[0051] The method may further comprise: operating the pump to cause coolant to circulate through the cooling system and the apparatus in a closed loop so as to cool the heat source of the apparatus.

[0052] In other words, the same pump may be used for exchanging / filling coolant and for maintaining circulation during a cooling mode of the cooling system.

[0053] Drawing the replacement coolant from the first chamber into the cooling system may automatically cause the used coolant and / or air to flow from the cooling system into the second chamber. More specifically, drawing the replacement coolant from the first chamber into the cooling system may increase the pressure inside the cooling system, and the increased pressure, in turn, causes used coolant and / or air to be pushed out of the cooling system.

[0054] The first chamber may be isolated from the second chamber such that the replacement coolant and the used coolant do not mix within the coolant cartridge. Each of the first and second chambers may be at least partially defined by a movable or flexible wall. The second chamber may be configured to receive the used coolant and / or air from an initially empty state.

[0055] Other optional features of the coolant cartridge according to the first aspect similarly apply to the second aspect.

[0056] According to a third aspect of the present disclosure, there is provided a cooling system for cooling a heat source of an apparatus. The cooling system comprises: an interface for thermally coupling to the heat source of the apparatus; a heat sink for thermally coupling to the heat source or the interface; a pump; a first coolant-exchange port for coupling to a first chamber of a coolant cartridge which is for storing replacement coolant; and a second coolant-exchange port for coupling to a second chamber of the coolant cartridge which is for receiving used coolant; wherein the pump is operable to cause coolant to flow along a coolant exchange path from the first coolant-exchange port, through the heat sink, to the second coolant-exchange port.

[0057] The first chamber may store replacement coolant which comprises a liquid.

[0058] The pump may be operable to draw the replacement coolant from the first chamber into the first coolant-exchange port.

[0059] The coolant exchange path may be established in use of the cooling system (i.e., when the cooling system is coupled to the apparatus).

[0060] The coolant flowing along the coolant exchange path may comprise the replacement coolant and the used coolant. Each of the replacement coolant and the used coolant may flow along at least a part of the coolant exchange path. The pump may be operable to cause coolant to flow along a cooling path through the interface and the heat sink.

[0061] The cooling system may further comprise: a coolant flow passageway between two fluid ports of the interface, wherein the coolant flow passageway comprises the heat sink, the pump, an expansion chamber comprising a first coolant outlet and a second coolant outlet and a valve; wherein: the second coolant-exchange port is in fluid communication with the second coolant outlet of the expansion chamber; the valve is in fluid communication with each of the first coolant outlet, the first coolant-exchange port and one of the two fluid ports of the interface; and the valve is controllable to fluidly connect either (i) the first coolant outlet to the one of the two fluid ports of the interface or (ii) the first coolant-exchange port to the one of the two fluid ports of the interface.

[0062] The valve may be configured to automatically switch from allowing for a fluid connection between the first coolant outlet and the one of the two fluid ports of the interface, to allowing for a fluid connection between the first coolant-exchange port and the one of the two fluid ports of the interface, in response to a coupling between the coolant cartridge and the first and second coolant-exchange ports.

[0063] The interface may comprise a system coolant outlet and a system coolant inlet for respectively coupling to a coolant inlet and a coolant outlet of the apparatus.

[0064] The coolant exchange path may also pass through the system coolant outlet, coolant piping of the apparatus, and the system coolant inlet.

[0065] The pump may be operable to cause coolant to flow along a cooling path from the system coolant inlet, through the heat sink, to the system coolant outlet.

[0066] In other words, the pump of the cooling system serves a dual purpose of establishing a cooling path (for transferring heat from the heat source to the cooling system and returning cooled coolant back to the heat source) and establishing a coolant exchange path (for replacing the used coolant within the cooling system with the replacement coolant).

[0067] The cooling path may be a closed-loop cooling path which flows through the cooling system and the apparatus. The cooling system may further comprise an expansion chamber in fluid communication with each of the system coolant inlet and the system coolant outlet.

[0068] The cooling system may further comprise: a coolant flow passageway between the system coolant inlet and the system coolant outlet, wherein the coolant flow passageway comprises the heat sink, the pump, an expansion chamber comprising a first coolant outlet and a second coolant outlet and a valve; wherein: the second coolant-exchange port is in fluid communication with the second coolant outlet of the expansion chamber; the valve is in fluid communication with each of the first coolant outlet, the first coolantexchange port and the system coolant outlet; and the valve is controllable to fluidly connect either (i) the first coolant outlet to the system coolant outlet or (ii) the first coolantexchange port to the system coolant outlet.

[0069] In the present disclosure, the expression “in fluid communication” means that fluid is able to flow between two elements that are in fluid communication with one another, and encompasses that one or more intervening element(s) adapted to provide a fluid flow passage (e.g., a valve that can be controlled to provide a fluid flow path) may exist between the two elements.

[0070] The expansion chamber may store both coolant and air.

[0071] The coolant flow passageway may further comprise coolant piping which fluidly connects the heat sink, the expansion chamber, the pump and the valve with one another.

[0072] The functioning of the pump depends upon a particular fluid connection provided by the valve. When the valve allows for a fluid connection between the first coolant outlet and the system coolant outlet, the cooling system operates in a cooling mode. When the valve allows for a fluid connection between the first coolant-exchange port and the system coolant outlet, the cooling system operates in a coolant exchange mode.

[0073] More specifically, the pump may be operable to cause coolant to flow along a cooling path from the system coolant inlet, through the first coolant outlet of the expansion chamber, to the system coolant outlet when the valve is controlled to fluidly connect the first coolant outlet to the system coolant outlet in use of the cooling system. The pump may be operable to cause coolant to flow along a coolant exchange path from the first coolant-exchange port, through the second coolant outlet of the expansion chamber, to the second coolant-exchange port when the valve is controlled to fluidly connect the first coolant-exchange port to the system coolant outlet in use of the cooling system.

[0074] The valve may be configured to automatically switch from allowing for a fluid connection between the first coolant outlet and the system coolant outlet, to allowing for a fluid connection between the first coolant-exchange port and the system coolant outlet, in response to a coupling between the coolant cartridge and the first and second coolantexchange ports.

[0075] Advantageously, the amount of user interaction required for coolant exchange is minimised, thereby making the cooling exchange process fail proof.

[0076] The first coolant outlet may be positioned at a lower coolant level of the expansion chamber than the second coolant outlet.

[0077] The second coolant outlet may be positioned to set a predetermined filling level of coolant in the expansion chamber.

[0078] In other words, during the coolant exchange mode, any coolant above the predetermined filling level would flow out of the expansion chamber at the second coolant outlet to the second chamber of the coolant cartridge.

[0079] The expansion chamber may comprise a coolant inlet, and a barrier which defines a fluid flow path between the coolant inlet and the second coolant outlet.

[0080] A length of the fluid flow path may be longer than a straight-line distance between the coolant inlet and the second coolant outlet.

[0081] In other words, the barrier may be configured to restrict a coolant flow from the coolant inlet to the second coolant outlet. The expansion chamber may comprise a third coolant outlet, and the third coolant outlet may be positioned at a lower coolant level of the expansion chamber than each of the first and second coolant outlets.

[0082] The expansion chamber may have a tapered bottom, and the third coolant outlet may be positioned adjacent to a lowest point of the tapered bottom.

[0083] The valve may be a first valve, and the cooling system may further comprise a second valve in fluid communication with each of the second coolant outlet, the second coolantexchange port and the third coolant outlet. The second valve may be controllable to provide a fluid connection between either (i) the second coolant outlet and the second coolant-exchange port or (ii) the third coolant outlet and the second coolant-exchange port.

[0084] The pump may be operable to cause used coolant to drain from the cooling system, through the third coolant outlet to the second coolant-exchange port when the second valve is controlled to provide a fluid connection between the third coolant outlet and the second coolant-exchange port.

[0085] During the draining of the used coolant from the cooling system, the first valve may be controlled to fluidly connect the first coolant-exchange port to the system coolant outlet.

[0086] The second valve may be configured to automatically switch from providing a fluid connection between the third coolant outlet and the second coolant-exchange port to providing a fluid connection between the second coolant outlet and the second coolantexchange port, in response to a coolant level in the expansion chamber dropping below a threshold level.

[0087] According to a fourth aspect of the present disclosure, there is provided an assembly comprising: a cooling system according to the third aspect of the present disclosure; and a coolant cartridge according to the first aspect of the present disclosure.

[0088] The first chamber of the coolant cartridge may initially store air above the replacement coolant, and a volume of the air in the first chamber may be equal to or greater than a volume of coolant stored by the expansion chamber. The volume of coolant stored by the expansion chamber may be determined by a position of the second coolant outlet.

[0089] The coolant cartridge may be configured such that the pump is operable to draw all of the air from the first chamber into the first coolant-exchange port of the cooling system before drawing the replacement coolant from the first chamber during a coolant exchange process.

[0090] According to a fifth aspect of the present disclosure, there is provided a system comprising: an apparatus comprising a heat source; and a cooling system for cooling the heat source according to a third aspect of the present disclosure or an assembly according to a fourth aspect of the present disclosure.

[0091] The replacement coolant initially stored by the first chamber of the coolant cartridge may have a volume greater than a total volume of coolant stored by the apparatus and the cooling system.

[0092] The apparatus may be an industrial printing or marking machine.

[0093] The industrial printing or marking machine may be suitable for integration with a production line.

[0094] The apparatus may be a laser marking machine.

[0095] The laser marking machine may be an industrial laser marking machine. The industrial laser marking machine may be suitable for integration with a production line.

[0096] The heat source may comprise a laser beam generator of the laser marking machine.

[0097] The laser beam generator may be a CO2 laser source configured to generate electromagnetic radiation. The CO2 laser source may comprise a pair of opposing mirrors arranged to form a resonator; and a pair of opposing electrodes configured to receive RF energy and thereby excite a gaseous gain medium located between the pair of electrodes and the pair of mirrors. The heat source may comprise the pair of opposing electrodes.

[0098] The heat source may comprise a marking head of the laser marking machine. The marking head may comprise an electromagnetic radiation steering mechanism which comprises optical elements and actuators configured to rotate the optical elements. The heat source may comprise the actuators.

[0099] The heat source may comprise an electromagnetic radiation steering mechanism of the laser marking machine.

[0100] The electromagnetic radiation steering mechanism may be configured to steer the electromagnetic radiation generated by the CO2 laser source to address a specific location within a two-dimensional field of view. The electromagnetic radiation steering mechanism may comprise a first optical element having an associated first actuator configured to rotate the first optical element about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view; and a second optical element having an associated second actuator configured to rotate the second optical element about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view. The heat source may comprise the first and second actuators.

[0101] Where appropriate any of the optional features described above in relation to one of the aspects of the disclosure may be applied to another one of the aspects of the disclosure.

[0102] Brief Description of the Drawings

[0103] In order that the disclosure may be more fully understood, a number of embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:

[0104] Figure 1 is a schematic representation of an exemplary laser marking machine;

[0105] Figure 2 is a schematic representation of a cooling system and a coolant cartridge according to a first aspect of the present disclosure; Figure 3 is a schematic representation of a laser marking machine equipped with coolant piping for use with the cooling system and the coolant cartridge of Figure 2;

[0106] Figure 4 is a schematic representation of a cooling system and a coolant cartridge according to a second aspect of the present disclosure;

[0107] Figure 5 is a schematic representation of a laser marking system for use with the cooling system and the coolant cartridge of Figure 2 or Figure 4;

[0108] Figure 6 schematically depicts a perspective view of internal components of a marking head for the laser marking system of Figure 5;

[0109] Figure 7 schematically depicts a cross-sectional side view of a CO2 laser source of the marking head of Figure 6;

[0110] Figure 8 schematically depicts a side view of an electromagnetic radiation steering mechanism of the marking head of Figure 6;

[0111] Figure 9 schematically illustrates processing steps of a method of exchanging coolant of a cooling system using a coolant cartridge, according to an aspect of the present disclosure.

[0112] In the figures, like parts are denoted by like reference numerals.

[0113] It will be appreciated that the drawings are for illustration purposes only and are not drawn to scale.

[0114] Detailed Description of the Preferred Embodiments

[0115] Figure 2 schematically illustrates a cooling system 1 and a coolant cartridge 8 according to a first embodiment of the present disclosure. The cooling system 1 comprises a system coolant inlet 5, a heat sink 6, an expansion chamber 2, a pump 9, a valve 10 and a system coolant outlet 4. Coolant piping 18 is used to fluidly connect adjacent components of the cooling system 1 . Therefore, the heat sink 6, the expansion chamber 2, the pump 9 and the valve 10 are in fluid communication with one another, and collectively form a coolant flow passageway between the system coolant inlet 5 and the system coolant outlet 4.

[0116] In more detail, heat-carrying coolant enters the cooling system 1 at the system coolant inlet 5, and is then led through a heat sink 6. The heat sink 6 releases heat from the heatcarrying coolant to the environment and therefore cools the heat-carrying coolant. In Figure 2, the heat sink 6 is shown as a simple radiator. However it would be appreciated that other types of heat sinks (e.g. radiator with fan, water-water heat exchanger, active cooler, etc.) can also be used. In an example, the heat sink 6 is able to cool the heatcarrying coolant to a certain temperature level that is below the ambient temperature, which may result in higher efficiencies in an apparatus (e.g., 100 in Figure 3) that is cooled by the cooling system 1.

[0117] The coolant then flows from the heat sink 6 to the expansion chamber 2. The heat sink 6 is in fluid communication with a coolant inlet 14 of the expansion chamber 2. The expansion chamber 2 is useful for compensating for temperature-induced volume changes of coolant 7 within the cooling system 1. The expansion chamber 2 has two coolant outlets 3, 13, which may be referred to as the “first coolant outlet” and the “second coolant outlet” of the expansion chamber 2. The first coolant outlet 3 is closer to a bottom wall of the expansion chamber 2 than the second coolant outlet 13 along the direction of gravity. Therefore, the first coolant outlet 3 corresponds to a lower coolant level than the second coolant outlet 13. The second coolant outlet 13 is positioned at the height of an ideal (predetermined) coolant level of the expansion chamber 2. The level is set such that temperature-driven expansions and contractions of coolant can be compensated for by the remaining coolant and air in the expansion chamber 2, and that to-be-expected losses of coolant due to permeation / evaporation processes would not lead to detrimental effects. In general, the second coolant outlet 13 is arranged such that the expansion chamber 2 stores both coolant and air when the cooling system 1 operates in a cooling mode (which is described below). The first coolant outlet 3 is connected to the pump 9 via coolant piping and the valve 10. When the cooling system 1 operates in the cooling mode, the pump 9 draws coolant from the first coolant outlet 3 of the expansion chamber 2, and pumps the coolant towards the system coolant outlet 4, where the coolant leaves the cooling system 1 and enters the apparatus (e.g., 100 in Figure 3) that is to be cooled. Figure 3 schematically illustrates an apparatus 100 that is used together with the cooling system 1. In this example, the apparatus 100 is a laser marker. The laser marker may be utilized to imprint bar codes, unique identifying marks, expiration dates, or other information on items passing through a production line. The laser marker 100 includes a laser beam generator 102 attached to a cold plate 150. The laser beam generator 102 and the cold plate 150 are enclosed in a housing 140. The laser beam generator 102 generates a laser beam 120 which enters a marking head 104. The marking head 104 includes moving mirrors 130 which direct the laser beam 120 through a focusing lens 105. The focusing lens 105 focuses the laser beam onto a work piece to be marked. The cold plate 150 is thermally coupled to the laser beam generator 102, and is made of a thermally conductive material such as metal. Coolant piping 160 is formed within the cold plate 150. One end of the coolant piping 160 acts as a coolant inlet 162, while the other end of the coolant piping 160 acts as a coolant outlet 164. In use, the coolant inlet 162 and outlet 164 are connected, via fluid-tight means, to the system coolant outlet 4 and system coolant inlet 5 of the cooling system 1 , respectively. Therefore, during the cooling mode of the cooling system 1 , the pump 9 causes the coolant to flow along a close-loop cooling path which is formed by the coolant piping 160, the coolant outlet 164, the system coolant inlet 5, the heat sink 6, the expansion chamber 2, the first coolant outlet 3, the valve 10, the pump 9, the system coolant outlet 4 and the coolant inlet 162. In this way, heat generated by the laser beam generator 102 is continuously transported by the coolant to the heat sink 6. It would be appreciated that the coolant may be thermally coupled to the laser beam generator 102 in any suitable way, and that the cold plate 150 may be suitably modified or even omitted completely. For example, components (e.g., laser diodes or laser crystals) of the laser beam generator 102 may be cooled by the coolant directly.

[0118] In the event that the coolant 7 (Figure 2) flowing along the close-loop cooling path needs to be exchanged, a coolant cartridge 8 (Figure 2) is connected to the cooling system 1. With reference to Figure 2, the coolant cartridge 8 is a dual-chamber coolant cartridge and comprises a housing 34 having at least one wall enclosing an internal space. In an example, the housing 34 comprises six rigid walls joined together to enclose an internal space of a cuboid shape. The rigid walls allow the housing 34 to maintain its shape without experiencing noticeable deformation during the coolant exchange process as described below. A first chamber 11 and a second chamber 12 are arranged within the internal space enclosed by the housing 34. The first chamber 11 contains new coolant (used interchangeably with “replacement coolant”) 40 and is initially full. Although Figure

[0119] 2 shows that the first chamber 11 does not contain any air, it would be appreciated that a small amount of air may be present within the first chamber 11 . The second chamber 12 is for receiving used coolant from the cooling system 1 and is initially empty. The first chamber 11 is enclosed (hence defined) by a wall 36, and the second chamber 12 is enclosed (or defined) by a wall 38. The walls 36, 38 are enclosed by the housing 34, and are made from flexible material which allows the first chamber 11 or the second chamber 12 to expand to substantially the whole internal volume of the housing 34. The internal volume of the housing 34 may be in the order of several litres. Due to the walls 36, 38, the first chamber 11 is isolated from the second chamber 12 such that the new coolant 40 and the used coolant to be collected do not mix within the coolant cartridge 8. The coolant cartridge 8 has an outlet 31 in fluid communication with the first chamber 11 for dispensing the new coolant 40. The coolant cartridge 8 also has an inlet 32 in fluid communication with the second chamber 12 for receiving used coolant from the cooling system 1 . Each of the inlet 32 and the outlet 31 may be fitted with a fluid-tight seal so that coolant does not leak from the chambers 11 , 12 inadvertently.

[0120] The cooling system 1 has a first coolant-exchange port 21 and second coolant-exchange port 22, which can form a fluid-tight engagement with the outlet 31 and the inlet 32 of the coolant cartridge 8, respectively. The second coolant-exchange port 22 is in fluid communication with the second coolant outlet 13 by way of coolant piping connected therebetween. The valve 10 is a three-way valve and is in fluid communication with each of the first coolant outlet 3, the first coolant-exchange port 21 and the pump 9. The valve 10 can be controlled to provide a fluid connection between either the first coolant outlet

[0121] 3 and the pump 9, or the first coolant-exchange port 21 and the pump 9.

[0122] To initiate the coolant exchange process, the outlet 31 and the inlet 32 of the coolant cartridge 8 are connected, via fluid-tight means, to the first and second coolant-exchange ports 21 , 22 of the cooling system 1 , respectively. This may be done by manually connecting hoses from the outlet 31 and the inlet 32 to the coolant-exchange ports 21 , 22, respectively. Alternatively, the outlet 31 and the inlet 32 may be connected to the coolant-exchange ports 21 , 22 by a mechanism that automatically provides the fluid-tight connection once the outlet 31 and the inlet 32 are pushed onto coolant-exchange ports 21 , 22. The mechanism may further allow the coolant cartridge 8 to be released by e.g., pressing a button. The connection between the coolant cartridge 8 and the cooling system 1 triggers a switching of the valve 10 such that the connection from the first coolant outlet 3 of the expansion chamber 2 to the pump 9 is blocked and the pump 9 is instead connected to the first coolant-exchange port 21. The switching of the valve 10 may be automatically triggered. For example, a sensor may be provided to sense the connection between the coolant cartridge 8 and the cooling system 1 , and accordingly send a signal (e.g., electronic signal) to the valve 10 causing the valve 10 to switch its fluid connection as described above. The sensor may be located on a side surface of the cooling system 1 (on which the coolant-exchange ports 21 , 22 are formed) to sense the proximity of the coolant cartridge 8. In another example, the aforementioned connection mechanism between the outlet 31 and the inlet 32, on the one hand, and the coolant-exchange ports 21 , 22, on the other hand, may be able to send a signal to the valve 10 causing the valve 10 to switch its fluid connection, in response to a connection between the outlet 31 and the first coolant-exchange port 21 and / or a connection between the inlet 32 and the second coolant-exchange port 22. Likewise, removing the coolant cartridge 8 from the cooling system 1 may automatically trigger a switching of the valve 10 such that the connection from the first coolant-exchange port 21 and the pump 9 is blocked, and the pump 9 is connected to the first coolant outlet 3 of the expansion chamber 2. Alternatively, the switching of the valve 10 may be triggered by a user selecting an icon (e.g., “start coolant exchange process”) on a user interface (e.g., a graphical user interface) of the cooling system 1 . In the event that the valve 10 is a mechanical T-port valve, the switching of the valve 10 may be manually performed by a user following the installation or the removal of the coolant cartridge 9.

[0123] Once the valve 10 provides a fluid connection between the first coolant-exchange port 21 and the pump 9, the coolant exchange process is started by operating the pump 9 which pumps the new coolant 40 from the first chamber 11 , through the coolant piping 18 of the cooling system 1 between the first coolant-exchange port 21 and the system coolant outlet 4, and through the coolant piping 160 (Figure 3) of the laser marker 100. This process increases the pressure in the expansion chamber 2 causing the coolant to be pushed out of the expansion chamber 2 through the second coolant outlet 13. Depending on the coolant level inside the expansion chamber 2, air and / or used coolant 7 is drained from the expansion chamber 2 until the coolant level is at the same level as the second coolant outlet 13, and the coolant level then remains constant during the remaining coolant exchange process. Pockets of air that may have been present in hoses or pipes after connecting the coolant cartridge 8 therefore would not have a detrimental effect on the coolant exchange process.

[0124] Air and / or old coolant (used interchangeably with “used coolant”) 7 drained from the expansion chamber 2 subsequently enters the second chamber 12 via the second coolant-exchange port 33 and the inlet 32. This causes the volume of the initially empty second chamber 12 to increase which then exerts pressure onto the wall 36 of the first chamber 11 , thereby pushing the new coolant 40 out of the first chamber 11. In this way, the expansion of the second chamber 12 assists the dispensing of the new coolant 40 from the first chamber 11. During the process of coolant extraction, depending upon the material of the wall 36, the pump 9 may typically be required to provide a gradually increasing minimum (negative) pressure in order to continuously extract coolant from the first chamber 11. The expansion of the second chamber 12 eases the requirement on the pressure generated by the pump 9 and ensures that most (if not all) of the new coolant 40 can be extracted from the first chamber 11.

[0125] Consequently, the piping 18 of the cooling system 1 and the piping 160 of the laser marker 100 are flushed with the new coolant 40. Once the piping 18, 160 is filled with the new coolant 40, the new coolant 40 starts to enter the expansion chamber 2. If the pump 9 continues pumping the new coolant 40 into the cooling system 1 , then old and new coolant would mix in the expansion chamber 2, and subsequently a mix of old and new coolant is drained from the expansion chamber 2 with a constantly changing mixing ratio of old to new coolant. The mixing ratio of old to new coolant becomes smaller with more new coolant 40 being pumped into the expansion chamber 2. Typically, the expansion chamber 2 holds a small percentage of the overall volume of coolant within the system (i.e., by taking into account both the cooling system 1 and the laser marker 100) while a majority of the coolant is in the piping 18, 160 of the system. In an example where the expansion chamber 2 holds about 10% of the overall volume of coolant within the system, if the first chamber 11 of the coolant cartridge 8 initially holds the same amount of coolant as the overall volume of old coolant within the system, once the piping 18, 160 is filled with the new coolant 40, the remaining new coolant (around 10% of the overall volume) will mix with the old coolant 7 (around 10% of the overall volume) within the expansion chamber 2. Assuming an ideal mixing in the expansion chamber 2, the remaining amount of the old coolant 7 in the system would be around 5% of the overall volume. On the other hand, if the first chamber 11 initially holds 120% of the overall volume of coolant within the system, once the piping 18, 160 is filled with the new coolant 40, the remaining new coolant (around 30% of the overall volume) will mix with the old coolant 7 (around 10% of the overall volume) within the expansion chamber. Assuming an ideal mixing in the expansion chamber 2, the remaining amount of the old coolant 7 in the system would be around 1.25% of the overall volume. Therefore, the volume of the new coolant 40 in the first chamber 11 affects a remaining amount of the old coolant 7 within the system after the coolant exchange process is completed. Ideally, the new coolant 40 initially stored by the first chamber 11 may have a volume greater than a total volume of coolant stored by the cooling system 1 and the laser marker 100.

[0126] In case only a minor excess amount of the new coolant 40 and / or a lower remaining amount of the old coolant 7 is desired, the expansion chamber 2 can be equipped with barriers 15. As shown in Figure 2, the barriers 15 include three barrier plates 15-1 , 15-2, 15-3 which separate the expansion chamber 2 into four compartments 25-1 to 25-4. The four compartments 25-1 to 25-4 are arranged in a non-overlapping manner along a lateral direction L. The lateral direction is perpendicular to the direction of gravity. The coolant inlet 14 and the coolant outlets 3, 13 are formed at opposite sides of the expansion chamber 2 along the same lateral direction L. Therefore, coolant entering the coolant inlet 14 flows through the compartments 25-1 to 25-4 in a sequential manner before exiting the expansion chamber 2.

[0127] Each of the barrier plates 15-1 to 15-3 restricts a flow of coolant between adjacent compartments. In an example, the barrier plates 15-1 to 15-3 are solid plates without any holes formed therein. Therefore, the coolant must flow past an edge of the respective barrier plate in order to enter the next compartment. With reference to Figure 2, the barrier plate 15-1 extends downwards into the coolant 7 such that the coolant follows a flow path 26-1 (which is adjacent to a bottom wall of the expansion chamber 2) to enter the second compartment 25-2. The barrier plate 15-2 extends upwards from the bottom wall of the expansion chamber such that the coolant follows a flow path 26-2 (which is adjacent to a top surface of the coolant) to enter the third compartment 25-3. The barrier plate 15-3 is similar to the barrier plate 15-1 as it forces the coolant to follow a flow path 26-3 (which is adjacent to the bottom wall of the expansion chamber 2) to enter the fourth compartment 25-4. Therefore, the barrier plates define an undulating coolant flow path (formed by the flow paths 26-1 to 26-3) between the coolant inlet 14 and the second coolant outlet 13. The undulating coolant flow path has a greater length than a straight- line distance between the coolant inlet 14 and the second coolant outlet 13.

[0128] Due to the presence of the barrier plates 15-1 to 15-3, when the new coolant 40 starts to fill the expansion chamber 2, it enters the first compartment 25-1 and will not immediately mix with the old coolant 7 within the third and fourth compartments 25-3, 25-4. In the meantime, the old coolant 7 is drained from the fourth compartment 25-4 into the second chamber 12 without any substantial amount of new coolant therein. As the new coolant 40 continues to fill the expansion chamber 2, it is expected that the ratio of the new coolant 40 decreases from the first compartment 25-1 to the fourth compartment 25-4. In other words, the barriers 15 impede the mixing of the new coolant 40 with the old coolant 7 in the expansion chamber 2 during the coolant exchange process. In this way, the old coolant 7 can be drained from the expansion chamber 2 more quickly as compared to a scenario where the barriers 15 were not provided within the expansion chamber 2.

[0129] It would be appreciated that the barriers 15 may be suitably modified insofar as they can restrict a coolant flow from the coolant inlet 14 to the second coolant outlet 13. It would further be understood that the barriers 15 are entirely optional and may be omitted from the cooling system 1.

[0130] Therefore, during the coolant exchange process, the pump 9 is operated to cause coolant to flow along a coolant exchange path. The coolant exchange path starts from the first chamber 11 , through the outlet 31 of the coolant cartridge 8, the first coolantexchange port 21 , the valve 10, the pump 9, the system coolant outlet 4, the coolant inlet 162, the coolant piping 160 and the coolant outlet 164 of the laser marker 100, the system coolant inlet 5, the heat sink 6, the expansion chamber 2, the second coolant outlet 13 of the expansion chamber 2, the second coolant-exchange port 22, and the inlet 32 of the coolant cartridge 8, leading to the second chamber 12 of the coolant cartridge 8.

[0131] After a successful exchange of the coolant, the coolant cartridge 8 has an empty first chamber 11 and a full second chamber 12 storing used coolant (and air if the coolant level inside the expansion chamber 2 is below the second coolant outlet 13 before the starting of the coolant exchange process). The coolant cartridge 8 can be removed from the cooling system 1. The used coolant cartridge can be disposed of or recycled. After the coolant cartridge 8 is removed, the valve 10 is controlled (either manually or automatically) to switch back to provide a fluid connection between the first coolant outlet 3 of the expansion chamber 2 and the pump 9. It would be understood that the second coolant-exchange port 22 needs to be closed to prevent a leakage of coolant through the second coolant outlet 13 of the expansion chamber 2. During the coolant exchange process, there is a constant flow of coolant through the piping 160 of the laser marker 100. Therefore, the laser marker 100 is able to continue its operation even during the coolant exchange process.

[0132] As described above, the pump 9 serves a dual purpose of establishing a cooling path during the cooling mode of the cooling system 1 and establishing the coolant exchange path during the coolant exchange mode of the cooling system 1 . The functioning of the pump 9 as well as the working mode of the cooling system 1 depend upon the particular fluid connection provided by the valve 10. When the valve 10 provides a fluid connection between the first coolant outlet 3 and the pump 9, the cooling system 1 operates in the cooling mode. When the valve 10 provides a fluid connection between the first coolantexchange port 21 and the pump 9, the cooling system 1 operates in the coolant exchange mode.

[0133] During the coolant exchange mode, once the coolant cartridge 8 is engaged with the cooling system 1 , the coolant can be readily exchanged by suitably controlling the valve 10 and operating the pump 9, and no further user interaction is required. In the event that the valve 10 can be automatically switched by the connection / disconnection of the coolant cartridge 8 to / from the cooling system 1 , the amount of user interaction is further reduced. Therefore, the cooling system 1 and the coolant cartridge 8 collectively provide a coolant exchange mechanism that is fail proof as it requires a minimised amount of user interaction. The coolant exchange process carried out by the coolant exchange mechanism is quicker than manual processes of removing used coolant and re-filling with new coolant, thereby reducing the downtime of the laser marker 100. Further, this coolant exchange mechanism avoids direct user contact with coolant. This is useful for reducing the risks of spilling coolant, which may be undesirable to the user’s health and the environment.

[0134] Figure 4 schematically shows a cooling system 1A and a coolant cartridge 8A according to a second embodiment of the present disclosure. Elements that are identical to those of Figure 2 are identified using the same labels. Elements that correspond to, but are different from those of Figure 2 are labelled using the same numerals but with a letter ‘A’ for differentiation. The features and advantages described above with reference to the first embodiment are generally applicable to this embodiment.

[0135] The cooling system 1 A allows the old coolant to be drained completely from the system (i.e. , by taking into account both the cooling system 1A and the laser marker 100) during the coolant exchange process. As compared to the cooling system 1 , the expansion chamber 2A of the cooling system 1A has a tapered bottom 19 which is formed by sloping bottom walls 19-1 , 19-2, and a third coolant outlet 16 formed close to the lowest point of the tapered bottom 19 (along the direction of gravity). In addition to the valve 10, a second valve 17 is used. The second valve 17 is a three-way valve and is in fluid communication with each of the second coolant outlet 13, the second coolant-exchange port 22 and the third coolant outlet 16. The second valve 17 can be controlled to provide a fluid connection between either the second coolant outlet 13 or the third coolant outlet 16, on the one hand, and the second coolant-exchange port 22, on the other hand. The second valve 17 may be of the same type as the first valve 10.

[0136] A coolant cartridge 8A is used with the cooling system 1A. The coolant cartridge 8A differs from the coolant cartridge 8 of Figure 2 in that its first chamber 11A initially contains both air 42 and new coolant 40. The initial volume of the air 42 is equal to or greater than the volume of coolant in the expansion chamber 2A (which is generally determined by the position of the second coolant outlet 13). The coolant cartridge 8A is designed such that in use, the air 42 is drawn from the first chamber 11A completely before any of the new coolant 40 is dispensed. That may be achieved by locating the exit point of the first chamber 11 A at the top along the direction of gravity.

[0137] The coolant exchange process is initiated by connecting the outlet 31 and the inlet 32 of the coolant cartridge 8A, via fluid-tight means, to the first and second coolant-exchange ports 21 , 22 of the cooling system 1A, respectively. The connection between the coolant cartridge 8A and the cooling system 1 A triggers a switching of the valve 10 such that the connection from the first coolant outlet 3 of the expansion chamber 2A to the pump 9 is blocked and the pump 9 is instead connected to the first coolant-exchange port 21. At the beginning of the coolant exchange process, the second valve 17 provides a fluid connection between the third coolant outlet 16 and the second coolant-exchange port 22, and blocks a fluid connection between the second coolant outlet 13 and the second coolant-exchange port 22.

[0138] The pump 9 then operates to drain the air 42 from the first chamber 11 A, before draining any of the new coolant 40 from the first chamber 11 A. The air 42 flows through the piping 18 of the cooling system 1A and the piping 160 of the laser marker 100. This process increases the pressure in the expansion chamber 2A and causes the old coolant 7 to be drained through the third coolant outlet 16, the second valve 17, the second coolantexchange port 22, to the second chamber 12. Once all of the air 42 from the first chamber 11A has arrived at the expansion chamber 2A, the old coolant 7 from the expansion chamber 2A has been fully drained. At this point in time the second valve 17 switches to provide a fluid connection between the second coolant outlet 13 and the second coolantexchange port 22 and blocks the fluid connection between the third coolant outlet 16 and the second coolant-exchange port 22. The switching of the second valve 17 may be automatically triggered without user interaction. For example, a level sensor may be attached to the bottom wall 19-1 or 19-2 of the expansion chamber 2A. The level sensor may send a signal (e.g., electronic signal) to the valve 17 causing the valve 17 to switch its fluid connection as described above, once the coolant level drops below a threshold level within the expansion chamber 2A. The threshold level depends upon the installed location of the level sensor and may be close to zero if the level sensor is installed proximate to the lowest point of the tapered bottom 19. It would be appreciated that other suitable means may be used to automatically trigger the valve 17 in response to the coolant level dropping below a threshold level in the expansion chamber 2A.

[0139] Since the pump continues to pump the new coolant 40 into the cooling system 1A, the new coolant 40 starts to fill the expansion chamber 2A. The location of the second coolant outlet 13 ensures that the filling level of the expansion chamber 2A is where it needs to be.

[0140] The design of the cooling system 1A and the coolant cartridge 8A enables the drainage of the expansion chamber 2A at the bottom of the chamber 2A, so that the entire old coolant 7 including any potential debris that may have built up at the bottom of the expansion chamber 2A can be fully drained from the system. In the cooling systems 1 and 1A, the system coolant outlet 4 and the system coolant inlet 5 may be collectively regarded as an “interface” of the cooling system for thermally coupling to a heat source of an apparatus (e.g., the laser marker 100) to be cooled. It would be understood that the interface may take a different form, for example, a cooling block although other arrangements are possible. The cooling block may be a block of thermally conducting material (e.g., metal) with an internal piping, which is part of the cooling path established by the pump 9 during a cooling mode of the cooling system. In use, the cooling block may be attached to the apparatus to be cooled in any suitable way (e.g., adhesives, bolts etc.) as long as heat is transferable from the apparatus to the cooling block. With the use of the cooling block, the cooling path (along which coolant circulates in the cooling mode) is established by the cooling system alone, and does not require any coolant piping being provided by the apparatus to be cooled.

[0141] In the cooling systems 1 and 1A, the coolant cartridges 8, 8A (in particular the first chambers 11 , 11 A) may be positioned at a higher elevation than the first coolant exchange port 21. Advantageously, this arrangement allows gravity to facilitate the flow of the replacement coolant from the first chambers 11 , 11A into the first coolantexchange port 21 , thereby easing the requirement on the pressure generated by the pump 9.

[0142] As described above, the cooling systems 1 and 1A are used with the laser marker 100 to cool the laser beam generator 102 of the laser marker 100. It would be understood that the cooling systems 1 and 1A can be used with other industrial printing or marking machines which typically operate with high power and heavy duty on production lines and thus requires efficient cooling. It would further be appreciated that the cooling systems 1 and 1A can be used with any type of apparatus to cool a heat source therein.

[0143] Figures 5 to 8 illustrate a laser marking system 100A which may be used with the cooling systems 1 , 1A and the coolant cartridges 8, 8A. Elements of the laser marking system 100A that correspond to, but are different from those of the laser marker 100 of Figure 3 are labelled using the same numerals but with a letter ‘A’ for differentiation.

[0144] With reference to Figure 5, the laser marking system 100A comprises a compact marking head 104A (which includes a carbon dioxide (CO2) laser source 102A and an electromagnetic radiation steering mechanism 130A), a supply unit 101 and an umbilical assembly 175 connecting the supply unit 101 to the marking head 104A. The umbilical assembly 175 may have a length of between 3m and 10m, and is configured to transmit signals (e.g. power signals such as an RF power input provided to the CO2 laser source 102A via a coaxial cable, control signals, sensor signals, etc.) and the coolant between the supply unit 101 and the marking head 104A. The laser marking system 100A comprises a sealing plug 170 configured to receive the umbilical assembly 175 at a first end and the CO2 laser source 102A at a second end. The marking head 104A comprises a cylindrical housing 180, and an end cap 190 having a window for emitting the electromagnetic radiation towards a product to be marked. The CO2 laser source 102A may also be referred to as a laser beam generator.

[0145] With reference to Figure 6, the CO2 laser source 102A is configured to generate electromagnetic radiation 120 which exits the CO2 laser source 102A via a beam exit 90. The electromagnetic radiation steering mechanism 130A is configured to steer the electromagnetic radiation 120 to address a specific location within a two-dimensional field of view. The CO2 laser source 102A has a dimension in a first direction 800 that is greater than a dimension of the CO2 laser source 102A in either orthogonal direction 810, 820 to the first direction 800. Similarly, the marking head 104A has a dimension in the first direction 800 that is greater than a dimension of the marking head 104A in either orthogonal direction 810, 820 to the first direction 800. Both the CO2 laser source 102A and marking head 104A are elongate in the first direction 800 compared to the second and third directions 810, 820. Similarly, the electromagnetic radiation steering mechanism 130A may also be considered as being elongate in the first direction 800 compared to the second and third directions 810, 820. A length of the marking head 104A is substantially parallel to a length of the CO2 laser source 102A. Both the CO2 laser source 102A and the electromagnetic radiation steering mechanism 130A comprise compact arrangements of components that, when combined, provide a marking head 104A having a significantly reduced weight and volume compared to known marking heads that comprise a CO2 laser source. The compact arrangement of the marking head 104A means that the marking head 104 tends to suffer from heat dissipation issues during operation and requires efficient cooling.

[0146] Figure 7 schematically depicts a cross-sectional side view of the CO2 laser source 102A. The CO2 laser source 102A is a CO2 slab laser comprising a pair of opposing mirrors 938, 940 arranged to form a resonator 950. The CO2 laser source 102A comprises a pair of opposing elongate electrodes 934, 936 configured to receive RF energy and thereby excite a gaseous gain medium located in the resonator 950. A first mirror 938 of the pair of mirrors 938, 940 is mechanically coupled to a first electrode 936 of the pair of electrodes 934, 936. A second mirror 940 of the pair of mirrors 938, 940 is mechanically coupled to a second electrode 934 of the pair of electrodes 934, 936. In the example of Figure 7, the mechanical coupling between the electrodes 936, 938 and the mirrors 938, 940 is provided by bolts 952, 954. Mechanical coupling means other than, or in addition to, bolts may be used.

[0147] The CO2 laser source 102A comprises an actuation mechanism 920, 921 configured to change a relative positioning of the pair of mirrors 938, 940 and the pair of electrodes 934, 936. In the example of Figure 7, the actuation mechanism 920, 921 comprises first and second screws 920, 921 that are mechanically coupled to opposing end faces 923, 924 of the CO2 laser source. The end faces 923, 924 are also mechanically coupled to the electrodes 934, 936. As such, rotating one or more of the first and second screws 920, 921 moves the respective one or more of the end faces 923, 924 which in turn moves the respective one or more electrodes 934, 936 and mirrors 938, 940. In this way, the relative positioning of the pair of mirrors 938, 940 and the pair of electrodes 934, 936 may be changed. The actuation mechanism 920, 921 may comprise other actuating means. For example, the actuation mechanism 920, 921 may comprise one or more of piezoelectric elements, elastic elements, magnetic elements, expandable and contractible elements (e.g. bellows), etc. The CO2 laser source 102A comprises a deformable housing 910. The end faces 923, 924 are mechanically coupled to the housing 910. Deformation of the housing 910 changes a spatial arrangement (e.g. a separation) of the end pieces 923, 924, and thereby also changes a relative positioning of the pair of mirrors 938, 940 and the pair of electrodes 934, 936. For example, plastic deformation of the housing 910 and / or the end faces 923, 924 of the CO2 laser source 102A would move the electrodes 934, 936 and, due to the mechanical coupling, would also move the mirrors 938, 940. In this way, the position of the mirrors 938, 940 may be adjusted relative to each other to form a desired resonator 950 configuration. That is, by using the actuation mechanism 920, 921 and / or deforming the deformable housing 910 a spatial arrangement of the resonator 950 (e.g. an alignment of the pair of mirrors 938, 940) may be adjusted to a desired state. Referring again to Figure 6, the housing 910 of the CO2 laser source 102A is cylindrical. In the example of Figure 6, the pair of electrodes 934, 936 are shaped so as to each form at least part of a circle in cross-section. That is, the electrodes 934, 936 are shaped so as to nest within the cylindrical housing 910. Alternatively, the electrodes 934, 936 may be substantially planar. In general, the electrodes 934, 936 may be relatively thin to increase the free space available in the resonator 950 for the gaseous gain medium comprising CO2. However, the electrodes 934, 936 may have sufficient thicknesses to allow one or more tunnels to be formed in the electrodes 934, 936. The tunnels act as coolant piping and may be configured to receive one or more coolant inlets 942, 946 and coolant outlets 944, 948 at the end points. The coolant inlet 942 and the coolant outlet 944 can be coupled to the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A), so as to cool the electrode 934. Similarly, the coolant inlet 946 and the coolant outlet 948 can be coupled to the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A), so as to cool the electrode 936. The coolant piping between the coolant inlet 942 and the coolant outlet 944 and the coolant piping between the coolant inlet 946 and the coolant outlet 948 may be connected in series or in parallel between the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A). Alternatively, if the electrodes 934, 936 are too thin to form coolant piping therein, one or more of the electrodes 934, 936 may be thermally coupled to a cold plate (e.g., the cold plate 150 of Figure 3) and coolant piping as well as coolant inlets and outlets may be formed in the cold plate.

[0148] Figure 8 schematically depicts a side view of an electromagnetic radiation steering mechanism 130A comprising an electromagnetic radiation manipulator “a”, “b”. The electromagnetic radiation steering mechanism 130A (or “deflection unit”) may be of the type described in international patent application WO2019 / 101887, which is incorporated herein by reference. The electromagnetic radiation steering mechanism 130A comprises a first optical element 700A having an associated first actuator A configured to rotate the first optical element 700A about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view. The electromagnetic radiation steering mechanism further comprises a second optical element 700B having an associated second actuator B configured to rotate the second optical element 700B about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view. The first optical element 700A is adjacent the second optical element 700B. The first optical element 100A is offset from the second optical element 100B along an axis that is substantially parallel to the first and second rotational axes. The first optical element 700A comprises a first reflective surface configured to receive and reflect electromagnetic radiation 120 and the second optical element 700B comprises a second reflective surface configured to receive and reflect the electromagnetic radiation 120. The first rotational axis and the first reflective surface are substantially parallel, and the second rotational axis and the second reflective surface are substantially parallel. The first and second rotational axes are substantially parallel to the first direction 800. The first and second reflective surfaces are substantially parallel to the first direction 800.

[0149] The electromagnetic radiation steering mechanism 130A further comprises an electromagnetic radiation manipulator “a”, “b” optically disposed between the first and second optical elements 100A, 100B. The first optical element 700A is configured to receive electromagnetic radiation 120 and direct the electromagnetic radiation 120 to the electromagnetic radiation manipulator “a”, “b”. The electromagnetic radiation manipulator “a”, “b” is configured to direct the electromagnetic radiation 120 to the second optical element 700B. The second optical element 700B may be configured to direct the electromagnetic radiation 120 to an optical output of the electromagnetic radiation steering mechanism 130A. The electromagnetic radiation manipulator comprises a first mirror “a” and a second mirror “b”. The first mirror “a” is configured to receive the electromagnetic radiation 120 after the electromagnetic radiation 120 has interacted with the first optical element 700A and direct the electromagnetic radiation 120 to the second mirror “b”. The second mirror “b” is configured to receive the electromagnetic radiation 120 after the electromagnetic radiation 120 has interacted with the first mirror “a” and direct the electromagnetic radiation 120 to the second optical element 700B. The first mirror “a” and the second mirror “b” are fixed with respect to each other. The first mirror “a” is arranged so as to apply about a 90° change in a propagation direction of the electromagnetic radiation 120. To achieve this, the first mirror “a” may be optically disposed at a 45° angle with respect to incident electromagnetic radiation 120. The second mirror “b” is arranged so as to apply about a 90° change in a propagation direction of the electromagnetic radiation 120. To achieve this, the second mirror “b” may be optically disposed at a 45° angle with respect to incident electromagnetic radiation 120. The electromagnetic radiation steering mechanism comprises a third reflector 710. The electromagnetic radiation 120 is turned by the third reflector 710 by 90° to hit the first optical element 700A of the first actuator A. This is useful in the formation of a coaxial device in which the electromagnetic radiation 120 generally propagates in a direction parallel to the first and second axes of rotation of the first and second optical elements 700A, 700B (e.g. when the electromagnetic radiation enters and exits the electromagnetic radiation steering mechanism). It will be appreciated that at various positions within the electromagnetic radiation steering mechanism the electromagnetic radiation propagates in a direction that is not along an axis parallel to the first and second axes of rotation. However, the electromagnetic radiation manipulator advantageously enables the first and second rotational axes to be parallel with one another. Further optical elements such as reflectors may be introduced to allow electromagnetic radiation to enter and exit the electromagnetic radiation steering mechanism along an axis parallel to the first and second rotational axes. For example, after the electromagnetic radiation 120 has reflected from the second optical element 700B, the electromagnetic radiation 120 may be turned by a fourth reflector (not shown) by 90°. The electromagnetic radiation 120 may then exit the electromagnetic radiation steering mechanism and be incident upon an object such as a product that is to be marked by the electromagnetic radiation 120.

[0150] The compact arrangement of the components of both the CO2 laser source 102A and the electromagnetic radiation steering mechanism 130A provides a significant reduction in the weight and volume of the marking head 104A compared to known marking heads. The marking head 104A has a mass of about 15 kg or less, and has a volume of about 10L or less. The marking head 104A has a length of about 500 mm or less, and has a diameter of about 100 mm or less.

[0151] The first and second actuators A, B of the electromagnetic radiation steering mechanism 130A may get hot during use and therefore need cooling. With reference to Figure 8, a body that is configured to support the actuator A or B has a tunnel formed therein, and the tunnel acts as coolant piping and receives a coolant inlet 943 or 947 and a coolant outlet 945 or 949 at its two ends. The coolant inlet 943 and the coolant outlet 945 may be coupled to the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A), so as to cool a body of the electromagnetic radiation steering mechanism 130A proximate the actuator A and thereby indirectly cool the actuator A. Similarly, the coolant inlet 947 and the coolant outlet 949 may be coupled to the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A), so as to cool a body of the electromagnetic radiation steering mechanism 130A proximate the actuator B and thereby indirectly cool the actuator B. The coolant piping between the coolant inlet 943 and the coolant outlet 945 and the coolant piping between the coolant inlet 947 and the coolant outlet 949 may be connected in series or in parallel between the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1A).

[0152] Further, the coolant piping for cooling the electrodes 934, 936 and the coolant piping for cooling the actuators A, B may be connected in series or in parallel between the system coolant outlet 4 and the system coolant inlet 5 of the cooling system 1 (or 1 A). Therefore, a single instance of the cooling system 1 (or 1A) may be used to cool all of the electrodes 934, 936 and the actuators A, B.

[0153] Alternatively, the actuators A, B may be cooled by directing air streams into the coolant inlets 943, 947. The air streams flow through the tunnels formed within the bodies that support the actuators A, B and exit the bodies at the respective coolant outlets 945, 949. In that case, the cooling system 1 (or 1A) is used to cool the electrodes 934, 936 only.

[0154] In the example described above, the cooling system 1 (or 1 A) is used to cool the compact marking head (of a laser marker) which includes the CO2 laser source 102A and the electromagnetic radiation steering mechanism 130A. It would of course be appreciated that the cooling system 1 (or 1 A) can be used with any type of laser markers with different laser wavelengths or different beam generation systems (e.g. gas lasers other than CO2, solid-state lasers, semiconductor lasers, fibre lasers), and / or different types of marking heads, or more generally any type industrial printing or marking machines. In addition to cooling a laser beam generator 102 of a laser marker (Figure 3), the cooling system 1 (or 1A) is also useful for cooling a marking head of a laser marker, regardless of whether the marking head is a compact marking head with laser beam generator incorporated. In general, a marking head of a laser marker includes an electromagnetic radiation steering mechanism (e.g., the moving mirrors 130 (Figure 3) and actuators for rotating the moving mirrors 130). The actuators are heat sources and may require efficient cooling. The cooling system 1 (or 1A) may be used to cool the actuators. Similarly, the cooling system 1 (or 1 A) may also be useful for cooling another heat generating component of a marking system, such as, for example, a power supply within a supply unit 101.

[0155] The cooling systems 1 and 1A may be modified in various ways. For example, the position of the pump 9 and the position of the heat sink 6 may be exchanged, or the pump 9 may be installed at a position to the left or to the right of the heat sink 6 with reference to Figures 2 and 4. These modifications would affect the sequence of components along the coolant flow passageway between the system coolant inlet 5 and the system coolant outlet 4, but would be immaterial to the coolant exchange mechanism described above. Regardless of the exact location of the pump 9 along the coolant flow passageway between the system coolant inlet 5 and the system coolant outlet 4, the valve 10 can be generally considered as being in fluid communication with each of the first coolant outlet 3, the first coolant-exchange port 21 and the system coolant outlet 4. The fluid communication between the valve 10 and the system coolant outlet 4 may be via coolant piping 18 alone, via the heat sink 6 together with the coolant piping 18, or via the pump 9 together with the coolant piping 18. Further, the valve 10 can be generally considered as being controllable to allow for a fluid connection between either (i) the first coolant outlet 3 and the system coolant outlet 4 or (ii) the first coolant-exchange port 21 and the system coolant outlet 4.

[0156] In addition, the cooling systems 1 and 1A may be modified to significantly deviate from Figures 2 and 4, while still being able to use the coolant cartridges 8, 8A in a coolant exchange process. By way of an example, the coolant exchange ports 21 , 22 may be provided in other suitable ways. For instance, the coolant piping 18 of the cooling system 1 or 1A may have a removable section, with two ends of the removable section being connected (in a fluid-tight manner) to two end points of the remaining coolant piping, respectively. Once the removable section is removed by a user, the two end points of the remaining coolant piping may act as the coolant exchange ports 21 , 22 to engage with the outlet 31 and the inlet 32 of the coolant cartridge respectively. Subsequently, the pump 9 operates to withdraw the new coolant 40 from the first chamber 11 or 11 A of the coolant cartridge. The removable section of the coolant piping 18 may be formed at any position along the coolant flow passageway between the system coolant inlet 5 and the system coolant outlet 4. The removable section may be installed and removed in any suitable manner. When the removable section is installed, the cooling system 1 or 1A operates in the cooling mode. When the removable section is removed, the cooling system 1 or 1A operates in the coolant exchange mode. In this embodiment, the valve

[0157] 10 and the second coolant outlet 13 of the expansion chamber 2 may be omitted. The valve 17 and the third coolant outlet 16 of the expansion chamber 2 may be omitted as well. Further, there may be more than one heat sink 6 and / or more than one expansion chamber 2 or 2A within the cooling system 1 or 1 A. In the event that the coolant piping of the apparatus to be cooled includes an expansion chamber, the expansion chamber 2 or 2A may be omitted from the cooling system 1 or 1 A.

[0158] Each of the coolant cartridges 8, 8A described above has a unitary structure, and can be handled as a single-piece item. In particular, the coolant cartridge 8 or 8A has a single housing 34 that encloses two chambers, and the single housing 34 allows the coolant cartridge 8 or 8A to have a unitary structure. Further, the coolant cartridges 8, 8A are passive devices and are free from any electric pump. Rather, the pump 9 of the cooling systems 1 , 1A is used to drive the coolant exchange process.

[0159] In the examples provided above, the coolant cartridges 8, 8A are suitable with a coolant exchange mechanism that is based upon overpressure. That is, the pump 9 increases the pressure at the downstream of the pump 9, and the overpressure pushes the used coolant into the second chamber 12 of the coolant cartridge, causing the volume of the second chamber 12 to increase. An expansion of the second chamber 12 further applies a pressure against the wall 36 of the first chamber 11 or 11 A, thereby pushing the new coolant 40 out of the first chamber 11 or 11 A and causing a volume of the first chamber

[0160] 11 or 11A to decrease. It would be understood that under-pressure may also be the driving force of the coolant exchange process. For example, when the volume of the first chamber 11 or 11A is reduced during the dispensing of the new coolant, the volume of the second chamber 12 may increase, thereby generating an under-pressure within the second chamber 12, and the under-pressure may cause used coolant from the cooling system 1 / 1A to be sucked into the second chamber 12. Under-pressure within the second chamber 12 may naturally occur if the housing 34 is sealed so that ambient air cannot enter the housing 34 from outside. In order to more effectively utilize underpressure as the driving force of coolant exchange or in order to create the under-pressure within the second chamber 12 if the housing 34 is not sealed, a top part of the wall 38 may be attached to internal surfaces of the walls of the housing 34 and a bottom part of the wall 36 may be also attached to the internal surfaces of the housing walls. Further, a bottom part of the wall 38 that faces the wall 36 may be attached to a top part of the wall 36. In this way, a decrease of the volume of the first chamber 11 or 11A would cause an increase of the volume of the second chamber 12 due to the joined parts of the walls 36, 38. It would be appreciated that if overpressure is solely used to drive the coolant exchange, the walls of the housing 34 may have air vent.

[0161] Further, the coolant cartridges 8, 8A used with the cooling systems 1 and 1A may be modified in various ways. In the examples provided above, the entire wall 36 that encloses the first chamber 11 or 11 A is flexible and the entire wall 38 that encloses the second chamber 12 is also flexible. The coolant cartridges 8, 8A may be modified such that only a part of the wall that defines the first or the second chamber is flexible. For example, the internal space within the housing 34 may be divided into two chambers by a partition wall. A periphery of the partition wall is attached (in a fluid-tight manner) to the internal surfaces of the housing walls. As such, the first chamber is defined (or enclosed) by some of the housing wall(s) and the partition wall, and the second chamber is defined by the remaining part(s) of the housing wall(s) and the same partition wall. The partition wall may be a flexible wall, which can be stretched substantially to allow each of the first and second chambers to expand to substantially the entire internal volume of the housing 34. Alternatively, the partition wall may be a rigid but movable wall. The movable partition wall may be slidable with respect to the housing walls while still maintaining a fluid-tight joint with the housing walls. The sliding movement of the partition wall allows each of the first and second chambers to expand to the entire internal volume of the housing 34. The examples described above which use the common movable / flexible partition wall may use both overpressure and under-pressure to drive the coolant exchange. This is because the total volume of the first and second chambers remains the same (as defined by the rigid housing walls). Consequently, a decrease in the volume of the first chamber causes a corresponding increase in the volume of the second chamber, and vice versa.

[0162] In the examples provided above, the walls of the housing 34 are rigid. It would however be appreciated that at least some of the walls of the housing 34 may be flexible. Accordingly, the overall volume of the housing 34 may not be constant, and instead may depend on the compression of the air inside the chambers 11 or 11A and 12. For example, if coolant was lost in the cooling system 1 or 1A (for example by evaporation), during the coolant exchange process more new coolant may be pumped into the cooling system than used coolant being pumped into the cartridge. As a result, the overall volume of the housing 34 may decrease after the coolant exchange process. The replacement coolant stored in the first chamber 11 or 11 A of the coolant cartridge 8 or 8A may consist essentially of water or oil (or other suitable types of liquid that is suitable for carrying heat). Additives may be added into the coolant. For example, if the coolant is water-based, the coolant may comprise an additive for preventing the water from being frozen, and / or an additive for preventing a growth of algae in the water. In addition, anti-corrosion additive may be added into the coolant to prevent corrosion of the piping and / or corrosion of the structures along the coolant flow path.

[0163] Figure 9 schematically illustrates processing steps of a method of exchanging coolant of a cooling system (e.g., the cooling system 1 , 1A) using a coolant cartridge (e.g., the coolant cartridge 8, 8A). The cooling system is for cooling a heat source of an apparatus and comprises: a system coolant outlet (e.g., the outlet 4) for coupling to a coolant inlet (e.g., the inlet 162) of the apparatus and a system coolant inlet (e.g., the inlet 5) for coupling to a coolant outlet (e.g., the outlet 164) of the apparatus; a heat sink (e.g., the heat sink 6) for thermally coupling to the heat source; a pump (e.g., the pump 9); a first coolant-exchange port (e.g., the port 21); and a second coolant-exchange port (e.g., the port 22). The coolant cartridge comprises a housing (e.g., the housing 34) having at least one wall enclosing an internal space; a first chamber (e.g., the first chamber 11 , 11A) and a second chamber (e.g., the second chamber 12) arranged within the internal space, wherein the first chamber is configured to store replacement coolant, and the second chamber is for storage of used coolant; an outlet (e.g., the outlet 31) in fluid communication with the first chamber; and an inlet (e.g., the inlet 32) in fluid communication with the second chamber.

[0164] At step S1 , the first coolant-exchange port (e.g., the port 21) of the cooling system is coupled to the outlet (e.g., the outlet 31) of the coolant cartridge.

[0165] At step S2, the second coolant-exchange port (e.g., the port 22) of the cooling system is coupled to the inlet (e.g., the inlet 32) of the coolant cartridge.

[0166] At step S3, the pump (e.g., the pump 9) is operated to cause replacement coolant to flow along a coolant exchange path from the first chamber, through the first coolant-exchange port, the heat sink and the second coolant-exchange port, to the second chamber. In particular, the pump may be operated to draw replacement coolant from the first chamber, through the first coolant-exchange port, and into the cooling system, and to cause used coolant within the cooling system to flow from the cooling system, through the second coolant-exchange port, into the second chamber.

[0167] Drawing the replacement coolant into the cooling system may also cause air within the cooling system to flow into the second chamber, if the coolant level inside the cooling system is relatively low before the starting of step S3.

[0168] Prior to the steps S1 to S3, the system coolant outlet of the cooling system may be coupled to the coolant inlet of the apparatus; and the system coolant inlet of the cooling system may be coupled to the coolant outlet of the apparatus. In other words, coolant within piping of the apparatus can also be exchanged during the coolant exchange process.

[0169] After the steps S1 to S3, the method may comprise the following optional steps:

[0170] At step S4, the operation of the pump (e.g., the pump 9) is stopped.

[0171] The pump may be stopped in response to an exhaustion of replacement coolant from the first chamber.

[0172] At step S5, the first coolant-exchange port (e.g., the port 21) of the cooling system is decoupled from the outlet (e.g., the outlet 31) of the coolant cartridge.

[0173] At step S6, the second coolant-exchange port (e.g., the port 22) of the cooling system is decoupled from the inlet (e.g., the inlet 32) of the coolant cartridge.

[0174] It would be appreciated that the steps may be performed in a temporal order that is different from the order of description. For example, steps S1 and S2 may be performed simultaneously; steps S5 and S6 may be performed simultaneously.

[0175] The method described above may also be used to fill a cooling system with coolant. A factory-fresh cooling system may not be filled with any coolant for the ease of shipment. Further, a cooling system may be drained for repair / maintenance. Those cooling systems must be filled or re-filled with coolant before they can be used to cool a heat source of an apparatus. Filling a cooling system also includes topping up the cooling system with coolant if the coolant level within the system is low.

[0176] To fill the cooling system with coolant, the pump is operated at step S3 to draw replacement coolant from the first chamber, through the first coolant-exchange port, and into the cooling system, and to cause air within the cooling system to flow from the cooling system, through the second coolant-exchange port, into the second chamber.

[0177] Pumping the replacement coolant from the first chamber into the cooling system increases the gas pressure in the cooling system. The increased pressure, in turn, pushes air within the cooling system to enter the second chamber of the coolant cartridge. This causes the volume of the second chamber to increase which then exerts a force onto the flexible / movable wall (e.g., the wall 36) of the first chamber, thereby pushing the replacement coolant out of the first chamber. In this way, the expansion of the second chamber assists the dispensing of the replacement coolant from the first chamber, and accelerates the filling process of the cooling system. Further, the expansion of the second chamber eases the requirement on the pressure generated by the pump and ensures that most (if not all) of the replacement coolant can be extracted from the first chamber.

[0178] For the cooling system 1 , the setup for filling the cooling system 1 may be identical to the setup for exchanging the coolant within the cooling system 1. Both requires the valve 10 to provide a fluid connection between the first coolant-exchange port 21 and the pump 9.

[0179] Filling the cooling system 1A may be achieved by controlling the valve 17 to provide a fluid connection between the second coolant outlet 13 and the second coolant-exchange port 22, and by controlling the valve 10 to provide a fluid connection between the first coolant-exchange port 21 and the pump 9.

[0180] When the coolant cartridge (e.g., the cartridge 8) is used to top up the cooling system (e.g., the system 1) with coolant, there is a constant flow of coolant through the piping 160 of the laser marker 100 to take away heat generated by the laser beam generator 102. Therefore, the laser marker 100 is able to continue its operation during the coolant top-up process.

[0181] It is described above that the second chamber 12 of the coolant cartridge 1 or 1 A is initially empty. It is meant that when the coolant cartridge is brand new (in other words, pristine, unopened, unused, as-shipped or factory-fresh), the second chamber does not contain any noticeable (or substantial) amount of liquid (e.g., coolant) and thus is substantially empty. Preferably, the volume of the second chamber may be at a very low level (e.g., close to zero) in the brand new state of the coolant cartridge so as to reduce the overall dimension of the coolant cartridge 1 or 1A. However, subject to manufacturing limitations and / or the design of the flexible / movable wall between the first and second chambers, the second chamber may contain a small amount of residual air and thus the initial volume of the second chamber may not be zero. For example, the initial volume of the second chamber may be less than 10% (or more preferably, less than 5%) of the initial volume of the first chamber (e.g., in the order of several litres).

[0182] The terms “having”, “containing”, “including”, “comprising” and the like are open and the terms indicate the presence of stated structures, elements or features but not preclude the presence of additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0183] Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the disclosure, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

CLAIMS:

1. A coolant cartridge for use to change coolant in a liquid cooling system, the coolant cartridge comprising: a housing having at least one wall enclosing an internal space; a first chamber and a second chamber arranged within the internal space, wherein the first chamber stores replacement coolant which comprises a liquid, and the second chamber is for storage of used coolant; an outlet in fluid communication with the first chamber for dispensing the replacement coolant; and an inlet in fluid communication with the second chamber for receiving the used coolant; wherein the first chamber is isolated from the second chamber such that the replacement coolant and the used coolant do not mix within the coolant cartridge; and wherein each of the first and second chambers is at least partially defined by a movable or flexible wall, and wherein the second chamber is configured to receive the used coolant from an initially empty state.

2. The coolant cartridge of claim 1 , wherein the movable or flexible wall is configured such that each of the first and second chambers is expandable to occupy substantially an entire volume of the internal space.

3. The coolant cartridge of claim 1 or 2, wherein the movable or flexible wall is enclosed by the at least one wall of the housing.

4. The coolant cartridge of any preceding claim, wherein the first chamber is at least partially defined by a first movable or flexible wall, and the second chamber is at least partially defined by a second movable or flexible wall, and wherein the first movable or flexible wall is distinct from the second movable or flexible wall.

5. The coolant cartridge of any of claims 1 to 3, wherein each of the first and second chambers is at least partially defined by a common movable or flexible wall.

6. The coolant cartridge of any preceding claim, wherein the coolant cartridge has a unitary structure.

7. The coolant cartridge of any preceding claim, wherein the coolant cartridge is free from any electric pump.

8. The coolant cartridge of any preceding claim, wherein the coolant cartridge is configured such that an increase in a volume of the second chamber causes a decrease in a volume of the first chamber.

9. The coolant cartridge of any preceding claim, wherein the coolant cartridge is configured such that a decrease in a volume of the first chamber causes an increase in a volume of the second chamber.

10. The coolant cartridge of any preceding claim, wherein the coolant cartridge is adapted to prevent ambient air from entering the internal space from outside the coolant cartridge.

11. The coolant cartridge of any preceding claim, wherein a total volume of the internal space remains constant.

12. A method of exchanging coolant of a cooling system or filling the cooling system with coolant, by using a coolant cartridge, wherein the cooling system is for cooling a heat source of an apparatus and comprises: an interface for thermally coupling to the heat source of the apparatus; a heat sink for thermally coupling to the heat source or the interface; a pump; a first coolant-exchange port; and a second coolant-exchange port, wherein the coolant cartridge comprises a housing having at least one wall enclosing an internal space; a first chamber and a second chamber arranged within the internal space, wherein the first chamber is configured to store replacement coolant which comprises a liquid, and the second chamber is for storage of used coolant; an outlet in fluid communication with the first chamber; and an inlet in fluid communication with the second chamber, wherein the method comprises: coupling the first coolant-exchange port of the cooling system to the outlet of the coolant cartridge; coupling the second coolant-exchange port of the cooling system to the inlet of the coolant cartridge; andoperating the pump to draw the replacement coolant from the first chamber, through the first coolant-exchange port, and into the cooling system, and to cause used coolant and / or air within the cooling system to flow from the cooling system, through the second coolant-exchange port, into the second chamber.

13. The method of claim 12, further comprising: stopping the operation of the pump; decoupling the first coolant-exchange port of the cooling system from the outlet of the coolant cartridge; and decoupling the second coolant-exchange port of the cooling system from the inlet of the coolant cartridge.

14. The method of claim 13, further comprising: operating the pump to cause coolant to circulate through the cooling system and the apparatus in a closed loop so as to cool the heat source of the apparatus.

15. The method of any one of claims 12 to 14, wherein drawing the replacement coolant from the first chamber into the cooling system automatically causes the used coolant and / or air to flow from the cooling system into the second chamber.

16. A cooling system for cooling a heat source of an apparatus, comprising: an interface for thermally coupling to the heat source of the apparatus; a heat sink for thermally coupling to the heat source or the interface; a pump; a first coolant-exchange port for coupling to a first chamber of a coolant cartridge which stores replacement coolant comprising a liquid; and a second coolant-exchange port for coupling to a second chamber of the coolant cartridge which is for receiving used coolant; wherein the pump is operable to draw the replacement coolant from the first chamber into the first coolant-exchange port and to cause coolant to flow along a coolant exchange path from the first coolant-exchange port, through the heat sink, to the second coolant-exchange port.

17. The cooling system of claim 16, wherein the pump is operable to cause coolant to flow along a cooling path through the interface and the heat sink.

18. The cooling system of claim 16 or 17, further comprising: a coolant flow passageway between two fluid ports of the interface, wherein the coolant flow passageway comprises the heat sink, the pump, an expansion chamber comprising a first coolant outlet and a second coolant outlet and a valve; wherein: the second coolant-exchange port is in fluid communication with the second coolant outlet of the expansion chamber; the valve is in fluid communication with each of the first coolant outlet, the first coolant-exchange port and one of the two fluid ports of the interface; and the valve is controllable to fluidly connect either (i) the first coolant outlet to the one of the two fluid ports of the interface or (ii) the first coolant-exchange port to the one of the two fluid ports of the interface.

19. The cooling system of claim 18, wherein the valve is configured to automatically switch from allowing for a fluid connection between the first coolant outlet and the one of the two fluid ports of the interface, to allowing for a fluid connection between the first coolant-exchange port and the one of the two fluid ports of the interface, in response to a coupling between the coolant cartridge and the first and second coolant-exchange ports.

20. The cooling system of claim 18 or 19, wherein the expansion chamber comprising a third coolant outlet, and the third coolant outlet is positioned at a lower coolant level of the expansion chamber than each of the first and second coolant outlets.21 . The cooling system of claim 20, wherein the valve is a first valve, and the cooling system further comprises a second valve in fluid communication with each of the second coolant outlet, the second coolant-exchange port and the third coolant outlet; and wherein the second valve is controllable to provide a fluid connection between either (i) the second coolant outlet and the second coolant-exchange port or (ii) the third coolant outlet and the second coolant-exchange port.

22. An assembly comprising: a cooling system according to any one of claims 16 to 21 ; and a coolant cartridge according to any one of claims 1 to 12.

23. A system comprising:an apparatus comprising a heat source; and a cooling system for cooling the heat source according to any of claims 16 to 21 or an assembly according to claim 22.

24. The system of claim 23, wherein the apparatus is an industrial printing or marking machine.

25. The system of claim 23 or 24, wherein the apparatus is a laser marking machine.

26. The system of claim 25, wherein the heat source comprises a laser beam generator of the laser marking machine.

27. The system of claim 25 or 26, wherein the heat source comprises an electromagnetic radiation steering mechanism of the laser marking machine.

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