Design method for a powertrain mounting system to decrease the vehicle key on/off vibrations

Abstract

Five dynamic response evaluation indices from the viewpoint of the powertrain mount system and the vehicle system during the vehicle key on/off periods (i.e. the engine start and stop) are proposed. By analysis using different methods to minimize the powertrain vibration, it was found that an increase in the mount system damping can decrease the vehicle key on and key off vibration. For this reason, in this paper a semi-active hydraulic damping strut is designed and made which can provide high damping for a mount system when the vehicle key on/off but switches to lower damping to isolate high-frequency vibrations under normal conditions. The calculated longitudinal acceleration of the powertrain, the jerk of the powertrain, the dynamic force of the mount and the vibration dose value for a vehicle with the semi-active hydraulic damping strut and without the semi-active hydraulic damping strut are compared on the basis of the excitation force identified for the powertrain using a 13-degree-of-freedom vehicle model. Experiments were carried out, and the results show that the use of the semi-active hydraulic damping strut can decrease the engine start and stop vibrations to a large extent. Finally, the experimental results are compared with the calculated values from the 13-degree-of-freedom vehicle model.

Research on the dynamic characteristic of semi-active hydraulic damping strut

“…The semi-active HDS is a hydraulic damping element to realize different damping effects through the opening or closing of the electromagnetic valve, which is controlled by the vehicle ECU system, and the solenoid valve of the semi-active HDS is connected to a 12-V battery of the vehicle. The semi-active HDS provides larger damping in the powertrain mounting system to reduce vibration and shock when the vehicle is in the process of in situ shift and engine key on/off, 1,13 and the structure is shown in Figure 1. The bushings of the semi-active HDS at both ends are connected to the engine and the sub-frame, respectively, which absorb the high-frequency vibration of the engine.…”

“…14 Then, the physical parameters of the semi-active HDS can be calculated according to its damping force calculation and analysis method. 1,14…”

“…From Figure 1, it can be seen that the main components of the semi-active HDS are the cylinder block (15) and the solenoid valve (the solenoid valve base (10), the recovery spring (11), the permanent magnet (12), the coil (13), and the spool (14)). The oil of the semi-active HDS mainly flows through the hole of the damping piston (5) and generates larger damping to attenuate the impact and vibration.…”

“…The 13 DOFs vehicle dynamic model mentioned in this paper containing the tire, the unsprung mass, the suspension, the vehicle body, and the powertrain mounting system, which includes 6 DOFs for the powertrain mounting system, 3 DOFs for the car body and 4 DOFs for the four unsprung mass respectively. 1…”

“…The 13 DOFs vehicle dynamic model mentioned in this paper containing the tire, the unsprung mass, the suspension, the vehicle body, and the powertrain mounting system, which includes 6 DOFs for the powertrain mounting system, 3 DOFs for the car body and 4 DOFs for the four unsprung mass respectively. 1 The reports on the dynamic stiffness and damping characteristics of hydraulic damper are mostly based on liquid resistance mount and hydraulic bushings, [2][3][4][5] and a few studies on the dynamic stiffness of HDS and semi-active HDS. Many works about the dynamic characteristics of the HDS are focused on the forcedisplacement and force-velocity relations.…”