What is a 'Thermal Management Module'? PH Explains


A 'Thermal Management Module' is effectively an electronically controlled thermostat that uses rotary valves to regulate the flow of coolant and other fluids.

Using a TMM grants several benefits, including the ability to restrict or completely stop the flow of coolant around the engine for an extended period - which, for example, can greatly reduce its warm-up time. This improves its emissions and fuel consumption, helping manufacturers meet ever-tightening regulations and customer demands.

These electronically actuated multi-purpose thermostats were co-developed by technology group Schaeffler and Audi, and introduced in 2012.


How do TMMs work?

A conventional thermostat features wax elements that are specified to melt when they reach a certain temperature, causing them to expand - which opens the thermostat and allowing coolant to circulate.

In a TMM, this function is instead carried out by electronically controlled rotary slide valves. Besides allowing the flow to be shut off entirely whenever desired, this method of actuation allows for precise and quick adjustments to suit the load and conditions at any moment. One valve closes off the pressurised flow of coolant from the water pump, while the other is used to distribute the coolant between the intake of the pump and the return to the radiator.


The precise control permitted means that the temperature stays more consistent while the engine is operating, further improving efficiency. Reportedly, using a TMM, the engine's temperature can be controlled as accurately as +/-2 degrees Celsius.

Crucially, the TMM can also be used to regulate the flow of coolant through ancillary systems, such as the cabin heater or a water-cooled engine oil heat exchanger - typically a compact plate-type unit.

Again, this allows for more accurate temperature regulation and quicker warm-up times; the time taken to hit the desired water temperature is reputedly cut by 30 per cent, compared to a conventional wax thermostat set-up, while the target oil temperature is achieved in half the time.


Is this degree of complexity really beneficial?

Potential emissions and efficiency benefits aside, manufacturer Schaeffler claims that the use of a TMM can reduce the time taken to warm up the car's heater core by 40 per cent. Consequently, owners don't have to endure a cold cabin for as long.

There are fail-safes in place to ensure that damage won't occur even if the TMM packs up, too. Many units use a conventional wax-based thermostat which will open if the coolant reaches a critical temperature. This will allow the driver to get the car home, or to a safe stopping point, should the worst happen. Some manufacturers, such as Magna, offer this as an optional upgrade to their TMMs.

The fact that several functions are handled by one unit further reduces development cost and complexity for manufacturers - and they can even be used in hybrid and battery cooling systems. TMMs also reduce assembly time, which again helps a manufacturer cut costs.

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Comments (11) Join the discussion on the forum

  • jakesmith 6 days ago

    Didn't know any of this thanks
    Especially that cars used wax, that sounds bizarre

  • DJT 6 days ago

    "Potential emissions benefits". Hmmm? Part of the cheat device package me thinks.

  • Haltamer 6 days ago

    DJT said:
    "Potential emissions benefits". Hmmm? Part of the cheat device package me thinks.
    In this case I'd say it's fairly reasonable, given that it reduces warmup times - Quicker to achieve optimal engine temperatures, bring catylitic converter up to heat etc.

  • mac96 6 days ago

    I was surprised that this device is thought to be so unreliable that a traditional thermostat has to remain as a back up. It is not as if it is a safety critical part either.

  • Pope 6 days ago

    Not only used to speed warm-up times; thermal management can also be used to give different running temps on the same engine - engines are more efficient at over 100C, but can quickly lose performance at higher temps - the thermal management system can replicate the effects of a low temp thermostat (enforced running at 80C) when required (via mapping shifts - SPORT button for example).

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