liquid cooling system of brakes
In the normal mode of operation of the car, the temperature of the brake mechanisms is rare when it exceeds 200 C. On the race track, the brakes can be heated to temperatures above 500 C.
(the average statistical data, which depend on the class of the car and the traffic conditions)
It has already turned out in the automotive industry that the air cooling system has ceded liquidity to the issue of engine cooling. High efficiency of "water" cooling here played not the last role.
It would seem that the same process should have happened with the cooling of the brakes? Especially since it was a question of traffic safety, that agree is more important than the possibility of the movement itself.
But such a transformation in the braking system of the car did not happen. More precisely, in mass order liquid cooling of brakes was not used, but there were interesting designs.
For example, Brembo puts liquid-cooled calipers on some rally cars.
Such calipers are used during the rally stages on asphalt.
Conditions for driving on asphalt at the race require perfect driving with minimal correction of the trajectory. As a matter of fact it turns out that on asphalt stages the periods of "rest" of brakes are combined with sharp braking of high intensity (with high braking moment). Therefore, liquid cooling gives the maximum effect under these conditions - the temperature is reduced by 80-100 degrees, which increases the thermal efficiency by 45%, in comparison with air cooling systems.
The use of liquid cooling in sports was not limited. On the principle of liquid cooling, the concept of a brake for trucks from Professor V. Selifonov and candidate of technical sciences N. Vladimirova was developed and tested.
It is known that the greater the mass of a truck with a load, the more difficult it is to develop brakes for it. The main reason is a large amount of heat, which must be dissipated, so the friction surface should be large, but at the same time be placed in the wheel. The brake surface of the disc brakes is always smaller than the drum analogs. The working conditions are also fundamentally different. Large temperature loads cause deformation and destruction of disc brake mechanisms, in contrast to drum brakes, and that is why on trucks and buses it is rare when disc brakes are applied.
The problem of adaptation of disc brakes to heavy trucks and buses was tried at the Moscow State Academy of Automotive and Tractor Engineering, at the Department of Automobiles. A fundamentally new, non-standard solution to the problem was found: disc brakes with a liquid cooling system.
The essence of the design is that the friction material is now located not on the shoe but on the disk. In the shoe made of cast iron, channels for liquid are made, which are connected to the cooling system by fittings.
In the conventional disk brake, the maximum temperature of the friction pair is 600-800 ° C, and the contact area of the parts is small, so heat-resistant and durable materials are required.
With a new design, this area is larger, and the temperature does not exceed 200-250 ° C. The requirements for materials are reduced, and the wear becomes smaller.
The prototype was tested in the laboratory of the academy and tested at the stand of NIIATI (Yaroslavl). The studies confirmed the calculations. The cyclic braking regime did not cause any large temperature changes and confirmed the theory.
Finally, it is worth mentioning the Daimler water cooling patent.
The system works both for heating and cooling tire car. The system consists of water in a special tank, sensors that fix the temperature of the rubber, and three injectors. Depending on traffic conditions and other factors, water spraying takes place with both cold and hot water (anti-icing tires). Replenishment of the water supply is possible due to the collection of rainwater falling on the car.
The idea of cooling by spraying water from the nozzles, and using water from the washer was also in the USSR patent.
But at the moment the idea of liquid cooling has advanced not only on rally cars, but also on specials. Transport, which, it would seem, does not have a high speed of movement.
Disc brakes with liquid cooling function are sometimes used now on Yale loaders with a carrying capacity of 5 to 5.5 tons.
P.S. - Installation of a system of liquid cooling of brakes on the car can have a number of concomitant advantages for the future. In the next article I will consider specific, and possibly unexpected, options for using this method of cooling on electric vehicles and hybrids.
It may be interesting