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Development of a simplified method for measuring engine motoring friction and its application to valve train friction measurement

Nakashima K., Kato T., Goto K., Murakami Y.

Journal of KONES

2016

Vol. 23, No. 2

261--267

We developed a simpler and less expensive method for measuring friction. Our equipment floats the double-end shaft motor by supporting both sides of the motor shaft with bearings, allowing the stator within the motor case to swing on the rotor with the shaft. Two arms were installed in the motor case; one is attached to a load meter; the other to a balance weight. The motor shaft is connected to the engine shaft, and when the engine is operated by the motor, torque is exerted on the stator with the motor case in the direction opposite to the motor shaft rotation, with engine friction acting as the reaction force. Torque is calculated by multiplying the arm length by the load as measured by the load meter in the arm. As an application of our new motoring friction test method, we measured valve train friction. The cylinder head of a single cylinder gasoline engine was clamped on a test bed, and its camshaft was connected to our friction measuring equipment. Utilizing various follower configurations of the rocker arms, we investigated the friction loss between the rocker arms and the cam. We thus clarified the effect of the valve-opening period and the valve lift on friction loss under various camshaft rotation speeds, and understood the lubricating conditions between the rocker arms and the cam.

Design and evaluation of IP multipath transmission with feedback

Kawamoto T., Goto K.

Systems Science

2009

Vol. 35, no 2

73-79

In this research, a simple multipath IP datagram transmission scheme is proposed and implemented as a user space router program. Delay and congestion vary along with time on each path and their estimation is difficult. In the proposed system, Multipath Tunneling Router (called MTR), traffic and delay of each path are periodically reported to the sender. An IP datagram is encapsulated in a UDP datagram and randomly transmitted to one of the paths according to the weight calculated with the feedback information from the receiving node. The path weight is based on the estimation of delay increase, which is measured as mean delay minus long term minimum delay of each path. The system is implemented as a user space tunneling router program on Linux and the performance is evaluated with a network emulator we have developed in a previous research. The program is rather small and consists of 1252 lines of codes in C++. The system is shown to be practical for two paths of different capacity and delay. Currently maximum throughput of the router implementation is about 65 Mbps with a single core CPU. It can be better with faster CPU.