Patent Description:
Conventional heat pumps typically include a control unit with an electronics circuit board with electrical components that generate significant heat during thermal cycling of the heat pump. Such system generally utilize independent active cooling features, typically electronics fans, for cooling of the electronics circuit board. In addition, since the electronics can act as heat sources, the circuit board is often located remotely and attached to the heat pump through wires. This approach further increases the size, complexity and demands of the overall system. On the other hand, <CIT> discloses a method for thermally cooling a device comprising a heater/cooler, a plate made of a thermally conductive material, a grille type heat sink in contact with the plate, a fan, two circuit boards, and a second fan, wherein the heat sink and the circuit boards are cooled by operating the fans. However, there exists a need to further simplify the thermal management of such heat pump systems as well as reduce the complexity and minimize the occupied size of such thermal cycling systems and associated control systems.

As a first aspect, the present invention provides a thermal management assembly as defined in claim <NUM> capable of dissipating the heat from an electronics board assembly controlling a heat pump while simultaneously controlling the temperature of a heat sink of the heat pump. In particular said thermal management assembly comprises:.

The assembly includes one or more air tubes or conduits that pull air from the back of the instrument by creating a negative pressure. In some embodiments, the assembly includes at least two air tubes or conduits, one on each side of the electronic board assembly. The air then travels through the one or more air tubes and flows into an electronics board assembly thereby providing cooling of the components inside the assembly. The above-described approach simultaneously pulls air from the front of the instrument through the heat sink of the heat pump of the thermocycler as well. The air tubes or conduits can take various cross-sectional shapes (e.g. round, oval, square, rectangular, triangular, a regular polygon, an irregular polygon, or any suitable shape, or combination of shapes). While typically, the air tubes or conduits are straight, it is appreciated they can be curved or can extend along a varied path. The air tubes or conduits can be made out of any suitable material, including but not limited to: polymers (e.g. plastic), metals (e.g. aluminum), ceramic, or composites. The one or more tubes or conduits can be added to an existing assembly, or the one or more tubes or conduits can be integrated within the assembly, for example integrated within the chassis of the instrument. Moreover, the one or more tubes of conduits can be formed of a thermally conductive material (e.g. metal, such as aluminum) so as to provide heat sinking of some other parts which are thermally coupled with the one or more tubes or conduits.

The electronics board assembly is defined by at least two electronic printed circuit boards (PCBs), one of which includes high power electrical components that act as heat sources during thermal cycling operation. The air flowing between the PCBs dissipates heat from these heat sources. The main advantage of such a system is that one or more fans, typically two fans located at the back of the instrument, can be used to create laminar flow through the heat sink while the air tubes draw in air between the PCBs that dissipates heat from the electronics onboard. This approach is advantageous since no independent cooling system is required to dissipate heat from the electronic components.

Due to the relatively high impedance of the heat sink, a proper airflow ratio should be maintained between the heat sink and the electronics board assembly. In addition, due to direct contact between the heat pump and thermal board assembly, some of the heat generated by high electrical current in the heat pumps is transferred to the thermal board assembly which is ultimately dissipated to outside. Thus, the thermal solution described-above can effectively reduce the heat generated by the heat pump and the control circuit board assembly concurrently. In another aspect, this approach can also minimize non-uniformity of the sample block of the heat pump by reduction of the heat generated in the high current circuitry of the PCBs at the top surface of the heat pump. The conformable nature of this approach permits its use even in applications where space is limited. Another benefit of this approach is that it allows the one or more the cooling fans to be positioned elsewhere (for example, at the back, underneath or at the sides of the instrument) which leaves space in the front of the instrument available for other auxiliary components, such as LCD, cables, etc..

The thermal management assembly includes one or more partition plates between the electronics board assembly and the heat sink in order to separate the airflow coming from the heat sink and the airflow drawn through the circuit board assembly. This approach advantageously provides isolation between temperature-elevated air coming from the heat sink and the electronic components. Due to the high efficiency of such systems, hermetic seals are typically not required between different components of the thermal management assembly.

The thermal management assembly of the present invention provides for maintaining stability or minimizing temperature fluctuation of the thermal board assembly in order to minimize failure of the board even at the temperature-elevated environment.

Another technical advantage of the thermal management assembly is that the thermal boards can be directly coupled with the heat pump, thereby reducing or eliminating any cable routing that might obstruct airflow. This approach also allows building of an assembly that includes a heat pump, thermal boards, fans, and air tubes or conduits as a module. Providing this assembly as a module is convenient for both manufacturing and service as the module can be removed for repair or replaced.

Thus, the thermal management assembly described herein provides thermal management without the need of any hood or enclosure. The assembly can contain at least two PCBs that are sandwiched together and directly interface with the heat pump of a thermocycling system.

The components of a thermal management system may not be cooled sequentially, as often seen in certain conventional systems, but rather the heat pump and the electronics board assembly may be cooled concurrently or simultaneously.

Thus, the thermal management device provides thermal management without requiring any moving of the sample. For example, the assembly provides thermal management without requiring any application of centrifugal force, as found in certain conventional systems. There is no reason to move the sample during thermal cycling since the heat pump and electronics board assembly can be cooled simultaneously or concurrently.

Moreover, the cooling system is relatively planar, which contrasts with cooling systems designed for test tubes, and which allows for reduced size as compared to certain conventional systems having additional external cooling components attached thereto.

In a second aspect, the present invention provides a method of thermally cooling a heat pump system in a thermal management assembly of the first aspect above as defined in claim <NUM>. In particular, the method comprises:.

The present invention provides a thermal management assembly as defined above that dissipates the heat from an electronics board control assembly while simultaneously or concurrently controlling the temperature of a heat sink of a heat pump for thermocycling. An example of an electronic board assembly suitable for use in such an assembly is shown in <FIG>. The electronics board assembly <NUM> is configured with a thermal controller and driver board for controlling thermal cycling. The electronics board assembly <NUM> includes two PCBs <NUM>, <NUM> with a space <NUM> therebetween. At least one PCB <NUM> includes high-powered electrical components <NUM>. As can be seen in <FIG>, which shows a thermal simulation of the electronic board assembly <NUM> during thermal cycling operation, the high powered components <NUM> can generate significant heat during operation such that cooling of the electronic board assembly is needed. In this embodiment, the electronic board assembly is configured to be directly connected to a heat pump assembly such that no extra wiring is required.

<FIG> shows a thermal management assembly that includes the electronic board assembly <NUM> directly connected to a heat pump assembly <NUM> having a heat sink. The assembly further includes a pair of air tubes <NUM>, one on each side of the electronics circuit board assembly <NUM>. The heat pump can be that described in <CIT> claiming priority of <CIT>, or it can be various other heat pumps. The assembly can further include one or more partitions <NUM> that separate the airflow from the heat sink and the airflow through the electronic boards assembly <NUM>. Both airflows can be effected by a common airflow source, such as a fan or a set of fans. The airflow source can be controlled based on one or more temperature sensor outputs at various locations or surfaces (e.g. heat sink, sample holder surface, etc.).

The pair of air tubes <NUM> pull air from the back of the instrument when a negative pressure is created within the space in between PCBs. The air then travels through the two air tubes and flows into the space between the PCB of the electronic board assembly, thereby cooling the components within before exiting at the rear of the assembly, as shown by the arrows in <FIG>. The assembly simultaneously pulls air from the front of the instrument through the heat sink of the heat pump of the thermocycler as well, as shown by the arrows in <FIG>. As can be seen in <FIG>, each of the pair of air tubes <NUM> includes an outlet <NUM> positioned near the heat pump and an intake <NUM> positioned toward a rear of the assembly furthest from the heat pump. As can be seen in the detail view of <FIG>, the outlet <NUM> faces inward so as to direct the cooling air drawn through the air tube into the space between the PCBs. A detail view of an exemplary air tube or conduit <NUM> is shown in <FIG> (see arrows indicating airflow during cooling operation).

The main advantage of such an assembly is that one or more fans can be located elsewhere (for example, at the back of the assembly) to create laminar flow through the heat sink and create a negative pressure so that the one or more air tubes provide cooling air through the electronic board assembly. An example of such an assembly is shown in <FIG>, which shows two fans located at the base of the assembly. <FIG> shows a thermocycling test of the assembly shown in <FIG>.

By this approach, no independent cooling system is required to dissipate heat from the electronic components. The speed of the fans can be controlled by sensing the temperature of the heat sink. The fans can be controlled by various means, for example, by PWM signals, changing voltage or any suitable method. The fan speed can also be influenced (e.g., adjusted or modified) based on the temperature of critical parts on the driver board of the electronics board assembly. In another aspect, the fan speed can be further influenced based on an input air temperature that can be measured within the one or more air tubes.

Due to the relatively high impedance of the heat sink, a proper airflow ratio is maintained between the heat sink and the electronic board's assembly. In addition, due to direct contact between the heat pump and thermal board assembly, some of the heat generated by high electrical current in the heat pumps is transferred to the thermal board assembly which will be ultimately dissipated to outside. Thus, the thermal solution can effectively reduce the heat generated by the heat pump and the board assembly at the same time and also minimize non-uniformity of the sample block of the heat pump by reduction of the heat generated in the high current circuitry of the PCB at the top surface of the heat pump. The conformable nature of the thermal solution described herein permits its use even in applications where space is limited.

In some embodiments, the thermal management assembly includes a partition plate between the electronics board assembly and the heat sink in order to separate the airflow coming out of the heat sink and the board assembly. This component is particularly advantageous in providing isolation between temperature-elevated air coming from the heat sink and the electronic components. Due to the high efficiency of such systems, hermetic seals are not required between different components of the thermal solution. Another advantage of this system is the provision of maintaining stability or minimizing temperature fluctuation of the thermal board assembly in order to minimize failure of the board even at the temperature-elevated environment.

In addition, another benefit of such a solution is that it allows having the cooling fans at various other locations (e.g. at the back of the instrument) leaving the space in front available for other components such as LCD, cables, etc. This aspect can be further understood by referring to <FIG>, which shows a side view of a testing system <NUM> that includes a thermal cycling assembly <NUM> (which includes the electronic board assembly <NUM> and heat pump <NUM>), and an analysis module <NUM>, that are both enclosed within an outer housing skin <NUM>. As can be understood further by referring to <FIG>, the analysis module <NUM> carries the samples within and is translated to the front of the system over the heat pump <NUM> to facilitate thermal cycling of the samples and then retracts to the rear of the system to facilitate removal of the samples.

As can be seen <FIG>, there is a void A between the casting of the thermal cycling assembly <NUM> and the outer skin <NUM>. In some embodiments, one or more interface components can be included, for example within void A, to maintain air flow through the fans and into the flowpaths described above while supporting one or more auxiliary components, such as cables or an LCD screen.

<FIG> show interface components, which can be 3D printed or formed by any suitable method. Interface component <NUM> provides vent opening on the sides to maintain adequate air supply and a middle partition which maintains isolation between the airflows from the heat sink and the electronic board assembly. Interface component <NUM> fits into component <NUM> and provide some vent openings on a front face as well as a central square region for supporting an LCD monitor <NUM>, for example, as shown in <FIG> (shown with the outer housing skin <NUM> removed).

Thermocycling test of the system shown in <FIG> are demonstrated in <FIG>and 13A-12B. <FIG> show thermocycling testing without the interface described above, while <FIG> show thermocycling testing of the system of <FIG> operating with the interface installed. Thus, with or without the blocking vents provided by the interface, the cooling system performs well and in an efficient manner.

Another technical advantage of the system is that the thermal boards are directly coupled with the heat pump which eliminates any cable routing that might obstruct the airflow. This aspect also allows building the entire assembly of a heat pump, thermal boards, fans, and air tubes as a module that can be convenient for manufacturing and service, for example, the module <NUM> shown in <FIG> and <FIG>, can be readily removed for repair or replacement.

While the foregoing description describes various alternatives, still further alternatives will be apparent to those who are skilled in the art.

Claim 1:
A thermal management assembly comprising:
a heat pump (<NUM>) having a heat sink;
an electronics board assembly (<NUM>) connected to the heat pump (<NUM>) and configured for controlling thermal cycling of the heat pump (<NUM>) electrically connected thereto, wherein the electronics board assembly comprises at least two circuit boards (<NUM>, <NUM>) with a space (<NUM>) therebetween, wherein at least one circuit board (<NUM>, <NUM>) includes one or more high power components (<NUM>), wherein the heat pump (<NUM>) is situated along a front of the electronics board assembly (<NUM>);
one or more air tubes (<NUM>) or conduits extending between an intake (<NUM>) to an outlet (<NUM>), wherein the outlet (<NUM>) is positioned near a front end of the electronics board assembly (<NUM>) that is nearest the heat pump (<NUM>) when electrically connected thereto and the intake (<NUM>) is positioned near a back end of the electronics board assembly (<NUM>) further from the heat pump (<NUM>);
one or more airflow sources that control airflow from a heat sink of the heat pump (<NUM>) when connected to the electronics board assembly (<NUM>); and
a partition (<NUM>) configured to isolate airflow from a heat sink of a heat pump (<NUM>) when connected thereto from airflow drawn through the electronics board assembly (<NUM>),
wherein the space between the at least two circuit boards (<NUM>, <NUM>) is enclosed sufficiently so that a negative pressure within the space draws air into the space from the outlet (<NUM>) of the one or more air tubes (<NUM>), thereby cooling the electronics board assembly (<NUM>) concurrent with cooling of the heat sink of the heat pump (<NUM>) during thermal cycling of the heat pump (<NUM>).