Study of External Characteristics of Hydraulic Electromagnetic Regenerative Shock Absorber

According to the composition and the principle of the liquid-electric ener-gy-sensing damper, the corresponding hydraulic regenerative model is designed. In this paper, an advanced type of shock absorber combined with the mechanical and electromagnetic hydraulic structure has been proposed that recycles the energy dissipated by shock absorber in the driving process. In addition, the damping characteristics of the conventional mechanical vehicle and the advanced hydraulic regenerative mechanical vehicle have been analyzed by using AMESim simulation. The regenerative suspension is reformed from the traditional hydraulic and pneumatic suspension. The suspension absorbs kinetic energy converts it into hydraulic potential and pneumatic power to be stored in the accumulator. The kinetic energy is then converted into electricity instead of heat by using the hydraulic suspension and Pow-er-Generating Shock Absorber (PGSA). The AMESim simulation results have efficiently verified the displacement characteristics curves and flow rate of hydraulic fluid in the body. Finally the conversion of energy produced by advanced hydraulic regenerative mechanical vehicle transferred into electrical energy. The designed hydraulic shock absorber allows a significant fuel saving of 1.5% to 4% depending on the vehicle and driving conditions.


Introduction
Suspension plays a vital role in vehicles, especially to maintain the ride comfort and road handling performances, by using oil shock absorbers to dissipate the vibration energy in them. Energy recovery from shock absorbers is a kind of method recovery energy of vibrations. Researchers have developed energy recovery since the early 1990s. Early energy recovery with active control and regenerative control of active vibration damper concept was proposed in 1996 [1] [2], and the idea was relying on linear DC motors. However, linear motors were generally costly, and linear motors efficiency was much lower than rotary. Then Graves [3] developed their energy-regenerative shock absorber by using a ball screw mechanism and rotary DC motor, while the results suggested that some parts still needed to be improved. Nakano [4] found rotating electromagnetic dampers had the advantage of mechanical amplification, and they have developed extra dynamic elements in series to enhance the vehicle dynamics. Two configurations of regenerative electromagnetic shock absorber have been designed for recovering the energy dissipated in shock absorber a linear device and a rotary device [5]. Li designed and analyzed an electromagnetic harvester for potential applications from vehicle suspension based on rack and pinion [6]. Zhang designed a regenerative shock absorber based on an arm teeth mechanism [7]. But energy-regenerative characteristic and the damping characteristic of their program still needed to be improved. Liu has stimulated and modeled a energy regenerative suspension based on neural network PID control [8], and Zou stimulated a hydraulic energy interconnected suspension based on hydraulic energy-regenerative shock absorber (HESA) comparatively with the passive suspensions [9]. This study tries to develop another program with rotary motor-HESA to obtain higher efficiency and better reliability [10]. US Patent Publications [11] [12] [13] [14] reveal various similar liquid-electric energy-feeding suspensions, which utilize the oil circuit system design to convert the reciprocating vibration energy of the piston into the hydraulic energy of the damping oil, and the hydraulic motor in the driving system rotates. The damper converts mechanical energy into heat by friction and then dissipates it to reduce vehicle vibration. If this part of the power can be recovered, it is possible to reduce fuel consumption and achieve energy saving. The damping force created by shock absorbers in traditional suspension is mainly based on orifice compensation and hydraulic actuator [15], which transfers the vibration energy into the damper oil heat, then dissipating into surroundings through the tubes. When vehicles are driving on the road, many factors affect on the vehicle [16] like vibration between spring-mass and unspring mass. These vibrations are dissipated into heat waste through friction during the damping process. The Damper converts mechanical energy into heat energy through dissipation and reduces the vibratory motion of the vehicle. If this part of the power can be recycled, then it would reduce fuel consumption and achieve the purpose of energy-saving.
The structure of regenerative energy suspension is different such as making reforms on traditional active suspensions [17] [18] [19] [20]. In this paper, we recover the vibration energy of the vehicle caused by uneven road surface, a liquid-electric energy-sensing damper for vehicles are designed on LMS AMESim.
The hydraulic accumulators are used in a variety of applications to minimize the pressure difference in hydraulic circuits and to store energy. The hydraulic sys-tem pressure changes with the quantity of energy stored, and the energy density is significantly lower than other energy domains. Shock is defined as "a transient condition whereas the kinetic energy is transferred to a system in a period which is short, relative to the natural period of oscillation of the system". Usually, shock contains a single impulse of the energy of the large intensity and short duration, which replicates in a dramatic change in velocity of the system undergoing shock.
The principle involved in both vibration and shock isolation is similar. The damper is an essential component in the automotive suspension system, and the hydraulic oil flows back and forth during the work. The primary function of vehicle suspension is to reduce the vibrational acceleration, deceleration disturbance from road roughness and chassis for better ride comfort and to sustain reasonable tire ground contact force for better vehicle handling. The suspension system is consists of the viscous and spring shock absorber. The regenerative braking systems have become increasingly popular because of recovering energy that would be lost through braking. However, another energy recovery mechanism that is still in the research stages is regenerative suspension systems. This technology can continuously recover a vehicle's vibration less energy dissipation that occurs due to road irregularities, vehicle acceleration, braking, and use the energy to reduce fuel consumption. The research group of Wuhan [21] has carried out a lot of research on the liquid-electric energy-feeding suspension, and proposed several implementation schemes of liquid-electric energy-feeding suspensions, from establishing dynamic models and simulation analysis. In addition, Fang [22] also studied the influence of road excitation frequency, external load and damping coefficient on energy efficiency. Lin Xu [23] have designed a hydraulic transmission electromagnetic energy regenerative active suspension system but in that system have used double accumulators, one was low and other higher precharge pressure accumulator that is not more efficient due to volume dynamic response. But in our research, we are using one accumulator getting more active, and this study analyses the modeling and simulation of shock absorbers, actuators, and dampers. The main work of this paper designs a hybrid energy damper that can make the oil flow in one direction, drive the generate electricity and obtained asymmetric damping ratio.

Working Principle
In this paper simulation includes some parameters like a hydraulic cylinder, check valves, hydraulic actuator, accumulator, hydraulic motor, electromotor, pressure sensor, and elastic elements ( Table 1).
As shown in the below Table 1, the main structures of the current shock absorbers are integrated. It is found that the structure of the hydraulic electromagnetic structure is excellent, which has excellent development potential during the hydrostatic energy-storage type and the electromagnetic coil shock absorber capture a part of the energy losses by suspension, and most of the vibration energy dissipated in the form of heat, so the efficiency is low. In contrast, the electromagnetic structure has high efficiency and reliable structural design.  The working principle when the absorber is in the compression stroke, the pis-

AMESim Simulation Model of Hydraulic Electromagnetic Energy Regenerative Shock Absorber
We build a model in AMESim by using hydraulic, mechanical, electrical, and  signal control library. No matter the shock absorber is in the extension stroke or compression stroke in the presence of hydraulic rectifier, the hydraulic motor is driven from one side. If hydraulic rectifier is removed, then oil will drive the motor from two sides, and the motor will change its rotational direction twice.
In advanced modeling are using a motor of 8 cc/rev displacement and 4000 rev/min while in traditional no use of motor, accumulator and check valve. The configuration of the hydraulic electromagnetic type shock absorber is shown in the following Figure 2. The hydraulic cylinder piston drives the oil to flow toward the accumulator under the excitation of the external; then the oil is sent to the hydraulic motor to rotate the motor, which will drive the generator to generate electricity (Figure 3).
We are using many sub-models components in our advanced hydraulic rege- The piston speed 0.52 m/s is the damping force of time resistance. When the cylinder bore diameter is 50 mm required we get restoration resistance 4000 -7000 N and compression resistance 700 -2800 N, as above Table 3.
The force rate ratio is always greater than 1 and less than 3. This model gets the compression force is F 1 , 3367.65 N, and expansion force F 2 , 3676.107 N, and recovery resistance 7043 N.
The total liquid flow rate of the hydraulic motor can be calculated by given below equation When the slope of signal incentive, the positive portion of the absorber is in the compression stroke and negative is extension stroke. The real parameters of the sine wave frequency are 1.67 Hz, and the phase shift is 270 degree ( Figure 5).
The components which are used to harvest energy includes hydraulic motor, electromagnetic generator, hydraulic rectifies in the form of a check valve and accumulator ( Figure 6).

Simulation Results and Discussions
According to the requirements of QC/T 491-1999 the national standard one car damper size series and follow the technical conditions, as a hydraulic cylinder with the bore diameter, is used 50 mm as the test object of the prototype as World Journal of Engineering and Technology     which ultimately leads to a reduction in energy recovery efficiency.
By measuring the damping force on piston (Figure 11), we can see that when compression resistance point A is corresponding to that before the control, with the active control over generator load, the hump drag in extension resistance point B is over 3900 N, which is far greater than before the control. The damping force in hydraulic electromagnetic energy regenerative absorber meets the  For conventional and non-accumulating HESA, the damping force gradually changes with the damping movement to reach a maximum value at maximum displacement and then gradually decreases. The maximum damping force only occurs for a short period, in combination with the maximum absorption speed and accumulators play an essential role in energy conservation in HESA.
The damping coefficient of the advanced hydraulic regenerative shock absorber is not more efficient than the damping coefficient of the traditional conventional system at a different frequency, as shown in Figure 12 and Figure

Conclusion
The damping force of the hydraulic electromagnetic energy regenerative absorber meets the standard requirements of QC/T 545-1999. This paper proposes a design of an advanced energy regenerative absorber structure and expounds its working principles. An effective simulation modeling way based on AMESim for hydraulic suspension control has been presented in this paper. Simulation with AMESim avoids cumbersome traditional modeling method. The efficiency of suspension simulation modeling for vehicle chassis dynamics system is enhanced.
The advanced hydraulic electromagnetic shock absorber is more efficient and reliable than the convention suspension and other suspension systems. The damping characteristic of HESA meets the requirements so that the traditional shock absorbers can be replaced by HESA to some extent. The generator can rotate unidirectionally and stably, which can extend the life of the generator and can improve energy recovery efficiency. The compression resistance force in advanced hydraulic regenerative shock system is always greater than the recovery resistance.