LIQUID COOLING SYSTEMS FOR HEAT GENERATING ELECTRONIC DEVICES THAT REPORT COOLANT TEMPERATURE VIA A TACHOMETER SIGNAL

A liquid cooling system for a computer. The liquid cooling system may have a cold plate configured to be positioned on a heat generating electronic device of the computer, the cold plate configured to pass a coolant therethrough. The liquid cooling system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The liquid cooling system may also include a pump in fluid communication with the cold plate, the pump configured to circulate the coolant through the cold plate and send a pump signal to a control system associated with the computer. The pump signal may represent a tachometer signal for the pump and the coolant temperature signal of the coolant.

TECHNICAL FIELD

The present disclosure relates generally to liquid cooling systems for heat generating electronic devices, and more particularly, liquid cooling systems that report coolant temperature and/or temperature conditions via a tachometer signal.

BACKGROUND

Coolant temperature can be an important operating parameter of liquid cooling systems for computer systems or other systems having heat generating electronic devices. If the coolant becomes too hot it will first reduce the useful life of the liquid cooling system, second damage the liquid cooler preventing it from cooling, and third cause damage which results in coolant loss that may damage the host computer. These consequences can occur sequentially as the coolant temperature increases above the safe operating temperature range. Coolant temperature is not an operating parameter that is currently monitored by most computers and therefore current computer systems are not compatible (e.g., physical electrical connections do not exist) with a liquid cooling system that measures and outputs coolant temperature. The disclosed systems and methods are directed to overcoming one or more of the problems set forth above.

SUMMARY

In accordance with the present disclosure, one aspect of the present disclosure is directed to a liquid cooling system for a heat generating electronic device. The liquid cooling system may include a cold plate configured to be positioned on the heat generating electronic device, the cold plate configured to pass a coolant therethrough. The liquid cooling system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The liquid cooling system may also include a pump in fluid communication with the cold plate, the pump configured to circulate the coolant through the cold plate and send a pump signal to a control system associated with the heat generating electronic device. The pump signal may represent a tachometer signal for the pump and the coolant temperature signal of the coolant.

Another aspect of the present disclosure is directed to a method of controlling a liquid cooling system for a heating generating electronic device. The method may include circulating a coolant through a cold plate configured to be positioned on the heat generating electronic device. The method may also include measuring a temperature of the coolant via a temperature sensor configured to generate a coolant temperature signal indicative of the temperature of the coolant. The method may further include pumping the coolant through the cold plate via a pump configured to send a pump signal to a control system associated with the heating generating electronic device. The pump signal may represent a tachometer signal for the pump and the coolant temperature signal of the coolant.

Another aspect of the present disclosure is directed to a liquid cooling system for a heat generating electronic device. The system may include a cold plate configured to be positioned on the heat generating electronic device, the cold plate configured to pass a coolant therethrough. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The system may further include a pump in fluid communication with the cold plate, the pump configured to circulate the coolant through the cold plate and send a pump signal to a control system associated with the heat generating electronic device. The pump signal may represent a tachometer signal for the pump and when the coolant temperature goes out-of-bounds the pump signal is held at a specific state indicating and out-of-bounds temperature to the control system.

Another aspect of the present disclosure is directed to a method of controlling a liquid cooling system for a heat generating electronic device. The method may include circulating a coolant through a cold plate configured to be positioned on the heat generating electronic device. The method may also include measuring a temperature of the coolant via a temperature sensor configured to generate a coolant temperature signal indicative of the temperature of the coolant. The method may further include pumping the coolant through the cold plate via a pump configured to send a pump signal to a control system associated with the heat generating electronic device. The pump signal may represent a tachometer signal for the pump and when the coolant temperature goes out-of-bounds the pump signal is held at a specific state indicating and out-of-bounds temperature to the control system.

Another aspect of the present disclosure is directed to a liquid cooling system for a heat generating electronic device. The system may include a pump configured to circulate a coolant through the system and send a pump signal to a control system associated with heat generating electronic device, wherein circulating the coolant removes heat from the heat generating electronic device. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The pump signal may represent a tachometer signal for the pump and the coolant temperature signal of the coolant.

Another aspect of the present disclosure is directed to a liquid cooling system for a heat generating electronic device. The system may include a pump configured to circulate a coolant through the system and send a pump signal to a control system associated with heat generating electronic device, wherein circulating the coolant removes heat from the heat generating electronic device. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The pump signal represents a tachometer signal for the pump and when the coolant temperature goes out-of-bounds the pump signal is held at a specific state indicating an out-of-bounds temperature to the control system.

Another aspect of the present disclosure is directed to a liquid cooling system for a heat generating electronic device. The system may include a cold plate configured to be positioned on the heat generating electronic device, the cold plate configured to pass a coolant therethrough. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The system may further include a flow sensor operatively connected to the temperature sensor and in fluid communication with the cold plate, the flow sensor is configured to receive the coolant temperature signal and send a device signal to a control system associated with the heat generating electronic device. The device signal may indicate to the control system when the coolant temperature goes out-of-bounds by holding the device signal at a specific state indicative of out-of-bounds temperature.

Another aspect of the present disclosure may be directed to a liquid cooling system for a heat generating electronic device. The system may include a cold plate configured to be positioned on the heat generating electronic device, the cold plate configured to pass a coolant therethrough. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The system may further include a pump in fluid communication with the cold plate, the pump configured to circulate the coolant through the cold plate and send a pump signal to a control system associated with the heat generating electronic device. The pump may be programmed to substitute the pump signal so it represents the coolant temperature signal of the coolant rather than the tachometer signal for the pump.

Another aspect of the present disclosure may be directed to a liquid cooling system for a heat generating electronic device. The system may include a cold plate configured to be positioned on the heat generating electronic device, the cold plate configured to pass a coolant therethrough. The system may also include a temperature sensor configured to generate a coolant temperature signal indicative of a temperature of the coolant. The system may further include a device operatively coupled to the temperature sensor and configured to send a device signal representative of a running pump to a control system associated with the heat generating electronic device. The device is programmed to send the device signal, whether or not the device signal is representative of an actual pump, while the coolant temperature is in-bounds and when the coolant temperature goes out-of-bounds the device signal is held at a specific state indicating an out-of-bounds temperature to the control system associated with the heat generating device.

DETAILED DESCRIPTION

FIG. 1is a schematic for a liquid cooling system10, according to an exemplary embodiment. System10may be configured to cool a computer12, server, or other electronic device, which may have heat generating electronic component(s)14, for example, CPU, GPU, etc. System10may include a cold plate16that may be configured to be positioned on the heat generating component14. Cold plate16may be fluidly coupled to a cooling device18and configured to circulate a coolant therethrough in order to remove heat from heat generating electronic component14. Cooling device18may be for example, a liquid-to-air heat exchanger or liquid-to-liquid heat exchanger. In some embodiments, cooling device18may be a liquid-to-liquid heat exchanger configured to transfer heat from the coolant circulating in system10to another coolant circulating in a liquid cooling system external to computer or server12. System10may also include a pump20fluidly coupled to cold plate16configured to circulate the coolant through cold plate16and cooling device18. System10may include conduits configured to circulate coolant between cold plate16/pump20and cooling device18. Pump20may be configured to send a pump signal22to a control system24, which may be associated with computer12and/or heat generating electronic component14.

In some embodiments, as shown inFIG. 1, pump20and cold plate16may be integrated into a pump/cold plate assembly30that is configured to be positioned on the heat generating component. In other embodiments, pump20and cold plate16may be separate components fluidly connected, for example, using conduits. System10may also include a temperature sensor26configured to generate a coolant temperature signal indicative of a temperature of the coolant. In some embodiments, as shown inFIG. 1, temperature sensor26may be integrated as part of assembly30. For example, assembly30may include a printed circuit board assembly (PCBA) and temperature sensor26may be mounted to the PCBA. In some embodiments, temperature sensor26may be mounted in a coolant well at, for example, the outlet of pump20so it may measure the coolant temperature of coolant as it is discharged from pump20. In other embodiments, temperature sensor26may be positioned elsewhere along the flow path of the coolant.

In some embodiments, liquid cooling system10may be configured to circulate coolant through a plurality of cold plates16in order to cool a plurality of heat generating electronic components14of computer12. For example,FIG. 2is a schematic of liquid cooling system10having a plurality of pump/cold plate assemblies30, where each pump/cold plate assembly30is positioned on a different heat generating electronic component14.

FIG. 3is a schematic of a pump/cold plate assembly30ofFIG. 1. As shown inFIG. 3, cold plate16may be positioned on heat generating component14and cold plate16and20may be integrated into assembly30. For some embodiments, based on the positioning of temperature sensor26there may be an offset for the measured coolant temperature from the actual coolant temperature based on the difference between the liquid temperature and the ambient air temperature surrounding pump20. For these embodiments, assembly30may also include an ambient temperature sensor32configured to measure the ambient temperature around assembly30enabling the offset for the measured coolant temperature to be determined and applied to obtain the actual coolant temperature. Ambient temperature sensor34may be mounted to the PCBA of assembly30. According to some embodiments, coolant temperature sensor32may be positioned such that it is sufficiently surrounded by the coolant and therefore unaffected by the ambient temperature, preventing the need for an ambient temperature sensor34and an offset determination.

As explained above, coolant temperature is not an operating parameter that is currently monitored by most computers and therefore current computer systems are not compatible with a liquid cooling system that measures and outputs coolant temperature because physical electrical connections do not exist to receive the coolant temperature signal. The disclosed liquid cooling systems10,100solves this problem by programming pump signal22to include information about pump20as well as the coolant temperature.

Most current computers have a tachometer (tach) signal port available that is intended to be used to monitor the speed of a pump or fan and also detect irregular operation of the pump or fan. System10as described herein, may be configured to utilize the existing tach signal port of control system24of computer12to send pump signal22, which may provide information about pump20as well as the coolant temperature. For example, pump signal22may include a tachometer signal portion and a temperature signal portion. In some embodiments, pump20may be programmed so pump signal22just represents the coolant temperature signal of the coolant rather than the tachometer signal for the pump.

The tachometer signal portion of pump signal22may be used to monitor the speed of pump20and also detect irregular operation of pump20. Such detection may be simple or more complex. For example, detection of irregular operation may include monitoring for a tach signal indicating zero speed, it may detect irregular operation by monitoring whether pump20is within normal operating speed bands, or it may monitor how quickly pump20responds to changes in power or duty cycle signals to predict when pump20may be at risk of failing.

In some embodiments, the temperature signal portion of pump signal22may be configured to signal control system24when the coolant temperature reaches one or more out-of-bounds conditions (e.g., greater than about 70° C.). In other words, the temperature signal portion of pump signal may simply indicate a high temperature state. In some embodiments, the temperature signal portion of pump signal22may signal when the temperature is out-of-bounds (e.g., too high) and control system24of computer12must take corrective action (e.g., forcing pump20to run at full speed). In some embodiments, rather than a simple binary state (e.g., high/not high) the temperature signal portion of pump signal22may transmit the coolant temperature to control system24enabling control system24to be programmed to determine when to take action. In some embodiments, system10may be configured to identify when coolant temperature is out-of-bounds and determine a corrective action based on how far the coolant temperature is out-of-bounds.

Pump signals traditionally report pump speed via a tach signal that is a square wave signal that shifts from high to low as the pump revolves. The number of shifts per revolution is dependent on the number of motor poles and is typically either 2, 4, or 8 shifts per revolution. For example,FIG. 4shows a pump signal plot (A) where the pulse per second may be multiplied by a scalar to determine pump speed in revolutions per minute. Pump signal plot (B) represents a tach signal where the pump is running at twice the speed of the pump in plot (A).

In some embodiments, pump20may include hardware and software logic programmed to receive the coolant temperature signal from temperature sensor26and determine whether the coolant temperature is out-of-bounds (e.g., too high) and when an excessive temperature is detected locking pump signal22of pump20in a specified state (e.g., high or low state). A non-spinning pump20may also lock pump signal22in either its high or low state. Upon receiving the locked state pump signal22, control system24may respond by taking one or more actions to address the situation. For example, in some embodiments control system24may respond as it would to a failed pump motor. For some embodiments, pump signal22may be locked low for an out-of-bounds temperature and locked high for a pump failure (e.g., non-spinning pump) enabling control system24to identify and differentiate between an out-of-bounds temperature vs. a pump failure enabling control system24to take appropriate action specific to the identified condition.

Pump signal22may be configured to represent a tachometer signal for pump20and the coolant temperature signal of the coolant measured by temperature sensor26by time slicing temperature measurements with pump speed measurements into pump signal22. According to some embodiments, pump signal22may report speed and coolant temperature by alternating between the two signals on a fixed time basis. For example, speed may be reported normally via a set number of pulses per revolution (e.g., 2, 4, or 8 pulses per revolution) for a fixed window of time—the speed-reporting window. This report may range from 45 to 600 pulses per second during the speed-reporting window. During a second fixed window of time, coolant temperature may be reported in degrees Celsius plus 1000 resulting in 1000 to 1150 pulses per second. For some embodiments these two fixed windows may be equal spans of time and in other embodiments they may be different spans of time. For some embodiments, the windows may be separated by either a short period of time where the signal is locked high or low.

According to some embodiments, pump signal22may report the tach signal pump speed in RPM and coolant temperature in Celsius using a serial communication protocol and communicating these values one following the other via binary encoding. For example, a two-byte value may be used to communicate RPM and a one-byte value may be used to communicate coolant temperature.

According to some embodiments, pump signal22may report the tach signal pump speed normally via a set number of pulses per rotation, as long as the coolant temperature is within a safe range. If the pump is stopped, the signal will be constantly high. For example, plot (C) ofFIG. 5shows a scenario where pump20is operating normally and pump signal is reporting the tach signal normally and then the pump is stopped so the pump signal goes constantly high, which may indicate a stalled pump impeller, failed pump motor, or pump has been disconnected. If the coolant temperature is outside the safe range, the signal will be constantly low. For example, plot (D) ofFIG. 5shows a scenario where pump20is operating normally and pump signal is reporting the tach signal normally and then the pump signal goes constantly low, which may indicate an out-of-bounds high temperature. System10may be configured such that this constantly low pump signal22will have priority over normal pump speed signals. If pump20has an internal failure, or for other reason stops, pump signal22will be set constantly high. The constantly high condition representing an internal failure may have priority over the pump speed signal and the out-of-bounds coolant temperature signal (i.e., constantly low).

According to some embodiments, pump signal22may report the tach signal for the pump normally via 4 pulses per rotation while the frequency of this signal represents the speed of the pump, and the duty cycle of the signal represent the coolant temperature. If pump20is stopped, the frequency will be set to a low value, and the duty cycle may continue representing the coolant temperature. If pump20has an internal failure, the signal may be set constantly high. The constantly high condition representing an internal failure may have priority over the other signals.

FIG. 5is a schematic of a liquid cooling system100. System100may include all or a portion of the components as system10. System100may also include a coolant measuring device34operatively connected to the temperature sensor25and in fluid communication with cold plate16and the flow path of the coolant. Coolant measuring device34, may be for example, a flow sensor configured to measure the flow rate of coolant through system100or a pressure sensor configured to measure the pressure of coolant within system100. In some embodiments, device34may be integrated as part of cold plate16or assembly30, for example, mounted to the PCBA. In other embodiments, device34may be positioned elsewhere separate from cold plate16along the flow path of the coolant within system100. For example, device34may be mounted in-line with the conduit between cold plate16and cooling device18.

Device34may be configured to receive the coolant temperature signal and send a device signal36to control system24associated with computer12or heat generating electronic device14. As described herein, most current computers have a tachometer (tach) signal port available that is intended to be used to monitor the speed of a pump or fan and also detect irregular operation of the pump or fan. System100as described herein, may be configured to utilize the existing tach signal port of control system24of computer12to receive device signal36, which may provide information about device34as well as the coolant temperature. Device signal36may function similar to pump signal22described herein, such that device signal36may be programmed to include information about device34as well as the coolant temperature. For example, device signal36may represent a measurement signal (e.g., pressure or flow) for device34and the coolant temperature signal of the coolant measured by temperature sensor26. In some embodiments, out-of-bound conditions measured by device34(e.g., pressure or flow) may also be determined and the device signal36may be used to indicate the out-of-bound condition to a control system by holding the signal high or low. In some embodiments, the measured pressure and/or flow may be utilized to estimate the temperature of the coolant enabling temperature measurement without a temperature sensor.

In some embodiments, device34may be programmed to send a device signal36representative of a running pump to control system24. Device34may be programmed to send the device signal36, whether or not the signal is representative of an actual pump, while the coolant temperature is in-bounds and when the coolant temperature goes out-of-bounds the device signal36is held at a specific state indicating an out-of-bounds temperature to control system24.

Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the present disclosure disclosed herein. It is intended that the specification and examples be exemplary only, with a true scope and spirit of the present disclosure being indicated by the following claims.