A Hydraulic Tappet with Variable Timing Properties

Mathieson, M.F.; Charlton, S J; Johnston, D N; Horrocks, R. W.; Watts, Michael

doi:10.4271/930823

Cited by 4 publications

(2 citation statements)

References 3 publications

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“…12 The cam-driven system has been widely adopted in four-stroke gasoline engines as it has simple structure, reliable operation, and quick response, while the camless systems are yet to be implemented in production for commercial issues. 13 The conventional variable valve timing system (VVT), such as VVT-i phaser of Toyota, 14 VANOS of BMW, 15 and VLD systems, 16,17 are hardly applied on a VSE. Moreover, variable valve lift system (VVL), such as VTEC mechanism of Honda 18 and RFF structure of Meta 19 cannot be used as valve movement would be in disorder when operating in 2/4-stroke mode.…”

Section: Introductionmentioning

confidence: 99%

Design and Dynamic Analysis of an Innovative Axial Shift Valvetrain System (ASVS) for Variable Stroke Engine

Cui

Li-ping

Long

et al. 2021

International Journal of Engine Research

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A variable valvetrain system is the key part of the variable stroke engine (VSE), which could achieve higher power performance and low-speed torque. An innovative axial shift valvetrain system (ASVS) was put forward to meet the air-charging requirements of a 2/4-stroke engine and complete a changeover within one working cycle. Two sets of intake and exhaust cam profiles for both intake and exhaust sides in the 2/4-stoke mode were designed for 2/4-stoke modes. Furthermore, a simulation model based on ADAMS was established to evaluate the dynamic valve motion and the contact force at different engine speeds. The dynamic simulation results show that the valve motion characteristics meet the challenges at the target engine speed of 3000 r/min. In two-stroke mode, the maximum intake valve lift could achieve 7.3 mm within 78°CaA, and the maximum exhaust valve lift could achieve 7.5 within 82°CaA on the exhaust side. In four-stroke mode, the maximum intake valve lift can achieve 8.8 mm within 140°CaA, and the maximum exhaust valve lift can achieve 8.4 mm within 140°CaA. The valve seating speeds are less than 0.3 m/s in both modes, and the fullness coefficients are more than 0.5 and 0.6 in the 2-stroke and 4-stroke mode, respectively. At the engine speed of 3000 r/min, the contact force on each component is acceptable, and the stress between cam and roller can meet the material requirement.

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Section: Introductionmentioning

confidence: 99%

Design and Dynamic Analysis of an Innovative Axial Shift Valvetrain System (ASVS) for Variable Stroke Engine

Cui

Li-ping

Long

et al. 2021

International Journal of Engine Research

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“…Because of their high quality and good reliability, these VVA systems have been currently applied in various production engines. For example, Toyota's VVT-i 13 and BMW's Vanos 14 implement cam phasing continuously with a fixed valve lift and a fixed duration. Honda's i-VTEC 15 switches between two discrete cams in different operation ranges.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the development and the controllability of a compact multi-functional, fully variable-valve-actuation system

Cui

Long

Yang

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part D:

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A compact multi-functional, fully variable valve actuation system for six-cylinder engines was proposed. The system can run in both the drive mode and the brake mode of internal-combustion engines. With the help of a distributor, fully variable valve events were achieved with two oil-supply sets, two solenoid valves and one drain valve. The operational parameters of the valve can be adjusted independently for individual cylinders. A numerical study on the controllability of the system was carried out with AVL Hydsim. The calculation results revealed that the timing of the valve opening, the maximum lift, the duration and the time-area value can be adjusted independently or synchronously by controlling the solenoid valves and/or the drain valve. Further correlation analysis results revealed that all the operational parameters of the valve had approximately linear relationships with the corresponding control parameters, and all the correlation coefficients were larger than 0.95, indicating good controllability of the system.

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