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What measures can be taken to prevent resonance of diesel generator set valve springs?

June 23, 2022
Diesel generator set valve spring is an important part of the gas distribution mechanism, its role is to ensure that the valve can be pressed in the valve seat when closed, while in motion to keep the transmission parts in contact with each other, not due to the action of inertia force and detach from each other, resulting in impact and noise.
The force acting on the valve spring of the diesel generator set is periodic, when the frequency of the force and the valve spring inherent frequency is the same or the spring inherent frequency is an integer multiple of the valve force frequency (10 times more), resonance occurs. Resonance is the largest amplitude of its vibration frequency, may cause the spring and valve instantaneous disconnect, so that the valve lost control, and even the spring broken.
In order to reduce resonance, diesel generator manufacturers use a variety of designs, including the use of stronger springs, unequal pitch springs, double springs, changing the outer diameter of the spring, placing a small damper in the spring, etc.. Specific measures are as follows.
1、Use of unequal pitch springs
This spring structure because the spring pitch is not equal, so the inherent frequency of each circle is different, when the valve rises, the spring is compressed, the end of the circle pitch is gradually stacked, so that the actual number of working turns of the spring is reduced, the inherent frequency of the spring follows the change, to avoid the resonance.
Note: When installing unequal pitch springs, the smaller pitch end should face the cylinder head.
2、Use double spring
Double spring is a small spring installed in the large spring, because the two springs are wound in different directions, the stiffness is different, the frequency of resonance is also different. When a resonance occurs, the other spring plays a damping role, so the use of double springs, can prevent the resonance phenomenon. Top-mounted valve train using double springs, once one of them breaks the other one can still maintain the work, so as to avoid serious accidents in which the valve falls into the cylinder.
In addition, under the condition of ensuring the same elasticity, the height of the double spring can be smaller than a spring, thus reducing the height of the machine. When using a double spring, the spiral direction of the inner and outer springs should be opposite, in order to avoid when a spring breaks, the broken part stuck in another spring.
3、Damping spring
Valve springs with damping springs, damping springs can be embedded in the valve springs.
The above are some effective measures to prevent resonance of diesel generator set valve springs, diesel generator set valve springs in the installation of a large preload, while having a large stiffness, which is to ensure that the valve in the closure of the required operating speed and to overcome the inertial force of the valve and other parts large enough.