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VARIABLE MILLER TIMING

IP.com Disclosure Number: IPCOM000246316D
Publication Date: 2016-May-27
Document File: 3 page(s) / 91K

Publishing Venue

The IP.com Prior Art Database

Abstract

A device to control the operation of the valve timing device in an IC engine is disclosed. The invention introduces a hydraulically connected chamber with variable pressurized volume in the timing mechanism. A plunger on which the valve stem bears through a spring is configured to move up and down with variation in pressure of hydraulic oil, thereby controlling valve opening. The chamber is pressurized through an oil inlet and the pressure is controlled via a servo valve receiving inputs from a controller. The controller may receive sensor inputs for engine torque, speed, engine pressure or other suitable variables. During engine startup, the sensor inputs to the controller to maintain a chamber pressure such that normal valve timing is ensured for smooth startup. During running conditions, the Miller cycle for operation of the engine is restored.

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BACKGROUND

The invention is in general related to internal combustion (IC) engines and in particular to devices and method for implementing variable valve timing in an IC engine. IC engines can utilize a Miller cycle to reduce parasitic pumping losses and fuel consumption rate. A Miller cycle can be performed by controlling the intake valve closing using an early intake valve closing (EIVC) or late intake valve closing (LIVC) strategy. However, these methods pose difficulties with engine start and ramp-up, when torque requirements may be difficult to meet if the special valve timing mechanism is active.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses a device and method for implementing variable valve timing in an IC engine, wherein:

FIG. 1 shows a valve timing device with hydraulic adjustment related to engine parameters.

DETAILED DESCRIPTION

The disclosed device is a hydraulic mechanism to control the operation of the valve timing device as shown in FIG. 1. As shown in the figure, the valve is operated by a roller-cam mechanism. The invention introduces a hydraulically connected chamber with variable pressurized volume in the timing mechanism. A plunger on which the valve stem bears through a spring, is configured to move up and down with variation in pressure of hydraulic oil. The chamber is pressurized through an oil inlet and the pressure is controlled via a servo valve at an outlet, receiving inputs from a controller. The controller may receive sensor inputs for variables such as engine torque, speed, or engine pressure. During engine startup, the engine torque is high, the speed is low and pressure in the engine cylinder is high, which when fed to the controller provides normal valve timing. This will make the expansion and compression cycles more...