2010

[Torque reduced up to 30% when compared with conventional unit!]

NTN Corporation (hereafter NTN) has developed a “Low torque roller lifter unit” for fuel pump drive systems of automotive direct injection engines.

Unlike a normal aspirated engine where air/fuel mixture enters the cylinder, feature of the direct injection engine is that only air is suctioned into cylinders and compressed while fuel highly pressurized by a fuel pump is directly injected into the cylinders. The Roller lifter unit (hereafter “Lifter”) ensures smoother movement in the fuel pump drive system of direct injection engines by means of rotation of a roller between the cam and plunger.

Conventional lifter types (sliding contact with cam) have been mainstream, but use of roller bearings (full complement type) in place of a roller to reduce fiction loss is being increasingly used by automotive manufactures. However, with the roller full complement type bearing, some issues such as heat generation or increase of rotational torque due to contact of roller to roller exists.

NTN developed a lightweight roller lifter by using a with-cage specification to prevent the contact of roller-to-roller, and achieved high-speed performance corresponding to a rotational speed of 36,000min^-1 as well as up to a 30% reduction in rotational torque compared with a full complement roller type lifter. The weight reduction (10%) while ensuring the necessary strength for the lifter was attained by making full use of the NTN's own long life technology (FA heat treatment^*1) and FEM^*2 analysis technology.

NTN initiated sales activity to automotive/pump manufactures to contribute enhancement of engine fuel pump efficiency.

*1 Fine Austenite Strengthening:Complex heat treatment technology combining the crystal grain miniaturization of bearing steel and the carburizing/nitriding treatment

*2 Finite Element Method

Features

(1) Low friction	Bearing rotational torque reduced up to 30% (compared with conventional product)
(2) High speed	Corresponding to bearing rotational speeds of 36,000min-1 (Bearing pitch circle diameter: with 10mm bore diameter, 18,000min-1 or less in roller full complement type)
(3) Light weight	Weight reduction of 10% (compared with the conventional product)

Application

Fuel pump drive system of automotive direct injection engine

Inquiries about this release

Applied position−Ex. Structure of high-pressure fuel pump