Solenoid actuator design and modeling with application in engine vibration isolators

This paper investigates the performance of a modified conventional solenoid valve as a low-cost controllable reciprocating force actuator. The applied modifications include adding a spring for plunger return mechanism, applying a bias current for pre-compression of the spring, and minor machining of the plunger rod. Potentially, this actuator can be employed in many applications, e.g. active noise and vibration control systems. A mathematical model of the actuator is given using the fundamental electromagnetic relationships. This model identifies the transfer function between the applied current and the output force. An experimental analysis in the frequency domain is conducted to obtain the current/force transfer function and validate the mathematical model. It is shown that in the stroke range of interest, the nonlinear analytical model of this actuator can be well estimated by a linear model. To investigate the performance of the actuator in a real application, this actuator is installed and tested in an active engine mount prototype. The analytical model of this engine mount is modified to include the actuator. The simulation result indicates that the stiffness and damping of this mount is tunable by controlling the input current to the actuator. The experimental results are also in close agreement with the simulations.