- July 16, 2008
- Bosch Rexroth
July 16, 2008 - In conventional flow-sharing (LUDV) systems, the pump controls the supply pressure of the valve control via a hydraulic-mechanical mode. Consequently, the pump reacts to every change of pressure made by consumers. The electrohydraulic flow matching (EFM) system replaces this pressure control loop with a new kind of control. The EFM control generates the adjusting signals for the pump at the same time the valves are controlled, thereby ensuring that adequate flow is made available. With this system, the implement hydraulics react a lot faster to the user’s commands and are therefore easier to operate.EFM also improves the extent to which energy is utilized, namely in the machine’s operating states in which the hydraulic consumers’ demand for flow is smaller than the pump’s maximum flow capacity. Thus, as long as the maximum capacity of the implement hydraulics is not reached, the EFM saves energy by up to 10 percent, depending on the operating point. This savings is based on the fact that the pressure losses between pump and valve adjust themselves according to the operating point. Because of this, they are smaller than the losses created by the hydraulic-mechanical flow-sharing (LUDV) solutions due to rigidly adjusted pressure surpluses.EFM also achieves an improved toughness in closed loop technology. Particularly in critical operating points such as fast changes in set-point values or serious changes in load pressure, this toughness has a positive effect due to a decreased vibration tendency. This advantage is achieved by EEM because the pump in the EFM system is no longer operated in the pressure control loop, but instead in an open control chain as an electro-proportional variable pump. Consequently, fewer breakdowns and mutual influences caused by various consumers occur. This also contributes to the machine’s improved ease of use, thereby making the user’s task easier.The EFM system is based on Rexroth components that include a variable pump with an electrohydraulic pilot control, such as the A10VO, an electronic joystick (e.g. from the Rexroth THE series), an electrohydraulic load-sensing valve (e.g. SX14NGE or M7), as well as a BODAS controller (for instance the RC36-20) with the expanded BODAS VAC (valve control) software to which the specific EFM function has been added. Bosch Rexroth AG, part of the Bosch Group, achieved sales of approximately $7.4 billion (5.4 billion Euros) in 2007 with nearly 33,000 employees. Under the brand name of Rexroth the company offers all drive and control technologies, from mechanics, hydraulics and pneumatics to electronics and associated service. Over 500,000 customers worldwide utilize Rexroth’s unique technological know-how to implement their innovative and future-oriented systems and machine concepts. The global player, represented in over 80 countries, is an extensive supplier of components and systems for industrial and factory automation and mobile applications.
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