A self-sealing planetary rotor pump designed by GKN Sinter Metals has the potential to revolutionize pump applications in automotive, commercial, and industrial vehicle engines and transmissions that require high pressures and efficiencies across a wide engine-speed range. According to Harald Neubert, Vice President, Product Management & European Sales, GKN Sinter Metals, the proprietary planetary micro/macro gear design "has been proven to reduce noise and energy consumption."
The company's planetary rotor fits into conventional G-rotor housings with only small modifications to achieve improved performance and efficiencies. In addition, the relationship of high pressures and unique volume flow characteristics to engine speed make this pump concept a good fit for hydraulic pump applications, which demand high performance from the start of flow control movement. "In these applications," said Dr. Neubert, "our planetary rotor pump can outperform even piston pump systems."
The new rotor's unique self-sealing mechanism is the result of tooth tip areas that self-adjust and tighten automatically. The design feature eliminates the typical teeth-flank-clearance back-flow losses often generated by conventional G-rotor designs. The circular teeth of the planetary outer gears are driven by the inner rotor while rolling over the micro teeth of the inner rotor. Thus, they slide freely in the open bores of the outer rotor without friction or a sliding movement in the sealing function.
The design allows GKN Sinter Metals' planetary rotor pump to perform at high pressures with improved flow characteristics from as low as 30 rpm to over 6500 rpm, covering virtually the entire spectrum of pump industry needs. The planetary rotor's volumetric flow stays close to theoretical flow, making it proportional to rpm while simultaneously providing high efficiencies at all pressures. The pump exceeds traditional piston pump or G-rotor pump efficiencies, with its typical drop at higher pressures, and it does not lose volumetric efficiency at low control flows.
According to Neubert, the planetary rotor also performs at substantially reduced noise levels. Its innovative micro/macro gear rolling-over teeth concept, which results in drastically reduced friction, extends the rotor's working life considerably. "Although complex in design," said Neubert, "this self-sealing pump is ideally suited for powder metal production, due to the net shape processing and minimal waste in material that are features of our powder metal manufacturing technology.
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SAE Off-Highway Engineering June 2000
