The principle of operation of a new optimized Caterpillar pipelayers

Energy Saving from Caterpillar pipelayers

Back in 2009, Caterpillar decided to develop conceptual designs with two types of hybrid drives and pipelayer pl87 – now you can enjoy pipelayer video. Both drives had to recover energy, which is dissipated in conventional excavators – the braking energy of the rotating superstructure. One hybrid design was created on the basis of electrical equipment, the other – on the basis of hydraulic components.

In a conventional excavator, when the operator releases the lever that activates the superstructure’s turning mechanism and the superstructure’s rotation starts to slow down, it continues to rotate by inertia. The hydraulic motor causes it to operate in pump mode. An oil flow is created that does not have an outlet, the pressure valve in the circuit opens a bypass valve, and the oil is drained into the hydraulic tank. A resistance is created in the contour of the hydraulic system, under the action of which the rotational motor gradually stops, a part of the kinetic energy of rotation is converted into heat and dissipates.

This lost energy can be accumulated and turned into useful work with the help of a braking energy recovery system. In a system built on the basis of electrical equipment. A turning motor is usually used, which, when the superstructure is braked, starts operating in generator mode and charges the battery or capacitor. The energy thus accumulated is then used to accelerate the rotation or to assist the internal combustion engine (ICE) in driving the main hydraulic pumps.

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Special system

In a system built on the basis of hydraulic equipment, the oil flow generated by the rotation motor (operating during braking of the rotating superstructure in pump mode) is accumulated in the high-pressure accumulator containing nitrogen (and does not open the overflow valve). From the battery, the flow of oil can be directed to the drive motor of the superstructure’s rotation to increase the speed of rotation.

The “heart” of the hydraulic energy recovery system of braking mod 336E N is the “Braking Energy for the Deceleration Energy Recovery Valve” SERV, which operates as an electronic controller for the amount of oil passing between the superstructure turning hydraulic motor and the accumulator. It also coordinates the amount of oil flow from the hydraulic pump. The flow rate through the SERV depends on the mode of operation of the machine and is about 200-300 l/min.

Recovery systems of both types reduce the load on the main hydraulic pump, which in turn reduces the load on the engine and provides significant fuel savings.