Technical Introduction of Tensioner For Engine Timing System

Briefly introduce some background knowledge to facilitate the understanding of technical principles.

Background knowledge 1: Hydraulic tensioner structure

The tensioner is installed on the loose side of the timing system, which mainly supports the guide plate for the timing system, eliminates the vibration of the crankshaft speed fluctuation and its own polygonal effect. The typical structure mainly includes five parts: shell, one-way valve, plunger, plunger spring and filler. The oil is filled into the low-pressure cavity from the oil inlet, and flows into the high-pressure cavity formed by the plunger and the housing through the one-way valve to build pressure. The oil in the high-pressure cavity can leak out through the damping oil groove and the gap between the plunger generate a larger damping force Ensure the smooth operation of the system.

Timing Belt Tensioner

Background knowledge 2: Damping characteristics of hydraulic tensioners

When a simple harmonic displacement excitation is applied to the plunger of the tensioner, the plunger will produce different damping forces to offset the influence of the external excitation on the system. Extracting the force and displacement data of the plunger and drawing the damping characteristic curve is an effective method to study the characteristics of the tensioner.

The damping characteristic curve can reflect a lot of information, for example: the enclosed area of the curve represents the damping energy consumed by the tensioner in a periodical motion. The larger the enclosed area, the stronger the vibration absorption capacity; another example: the slope of the compression section and the reset section represents the tension The sensitivity of loading and unloading of the tensioner, the faster the loading and unloading, the less the invalid stroke of the tensioner, the more conducive to maintaining the stability of the system under the smaller plunger displacement.

Background knowledge 3: The relationship between the plunger force and the loose edge force of the chain

The loose edge force of the chain is the decomposition of the tensioner plunger force along the tangential direction of the tensioning guide plate. As the tensioning guide plate rotates, the tangent direction changes at the same time. According to the timing system layout, it can be approximately solved for different guide plate positions. The corresponding relationship between the plunger force and the loose edge force, the loose edge force and the plunger force change trend in the working section basically the same.

Although the tight edge force cannot be obtained directly through the plunger force, according to engineering experience, the maximum tight edge force is about 1.1 to 1.5 times the maximum loose edge force, which enables engineers to indirectly predict the maximum chain force of the system by studying the plunger force become possible.

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