Vehicle hybrid free-piston engine-generator

Abstract

Abstract. The study of dynamical performance and effectiveness of on-board power generators having freepiston linear internal combustion engine combined with electrical generator completed with auxiliary drive is presented. The proposed concept is successfully applicable in all types of automobiles, specifically in hybrid vehicles and electric motor cars, and would be used for a design of all kinds of motor vehicles, cars, trucks, offroad machines, transport and agricultural machinery.Keywords: free-piston linear internal combustion engine, electrical generator, controlled auxiliary engine drive. IntroductionThe on-board power generators presented by free-piston linear internal combustion engine without crankshaft combined with electrical generator are widely discussed in recent publications as a device that radically reshapes the hybrid vehicle powertrain. The studies dealt with systematic analysis and synthesis of the main parts of this type of on-board power generators: free-piston linear internal combustion engine without the crankshaft, electrical generator and the control system interconnecting the two above-mentioned components. An important improvement for free-piston linear internal combustion engine without crankshaft combined with electrical generator is the usage of generating component as a partial auxiliary engine drive developed by the authors of the current study. The term "combined" means that the considered device is assembled as one unit. One of the latest perspective devices is presented in [1; 2], where Toyota Central R&D Labs Inc. demonstrates a free piston engine linear generator consisting of a two-stroke combustion system, a linear generator, and a gas spring chamber. The authors paid a lot of attention (among others) to a. control of precise position of the piston, and its velocity as well; b. periodically stop operation of the generator as a driving motor during the generating operation. The authors wrote that they used two versions of combustion: spark ignition -SI, and premixed charged compression ignition -PCCI. For SI case the power output was 10.4 kW, and overall efficiency was 36.2 %; for PCCI case the power output was 12.7 kW, and overall efficiency was 42.0 %.The industrial evaluation of all existing free-piston engine -electric generating devices reflects two major problems: it is difficult to create the piston motion automatically achieving the desirable top-dead-center (TDC) and bottom-dead-center (BDC) at the necessary moment in the absence of the crankshaft; there is increased the heating problem due to close location of two heat sources, i.e. the piston in the cylinder and the electromagnetic generator. The focus of the current study is development of the auxiliary drive in the generator scheme for raising the effectiveness of free-piston linear internal combustion engine by achieving the stroke parameters and combustion equal to regular values of Internal combustion engine having the crankshaft.

Energy Harvesting in Vehicle’s Drive

“…The implementation of VEH in vehicles was dictated by two combined reasons: necessity of a reduction of intensive vibrations and proper usage of damped vibration energy. For instance, the Hybrid Complexes are the sources of intensive vibrations [6] - [8]. The application of developed VEH (having Controlled Tuned Mass Damper scheme) in vehicle propulsion environment for reaching two goals: reduction of vibration levels and effective usage of wasted vibration is demonstrated in the current study using some examples.…”

“…Furthermore it is possible to pay attention on a specific of the dynamic properties of Tuned Mass Damper coupled to Alternator. The selected sample of object for analysis is Free-Piston Linear Internal Combustion Engine without crankshaft combined with Electrical Generator completed by auxiliary drive [6], [7]. It was established that the vibrations of an object body are along one axis mainly.…”

“…The Free-Piston Linear Internal Combustion Engine without crankshaft combined with Electrical Generator completed by auxiliary drive [6], [7] is an example of device vibrating in one line direction (rectilinear) or object having single degree of freedom. Its model can be described by an equation (1).…”

“…The prototype of EVEH focused on tuning damping of Hybrid Complex vibrations was designed and fabricated. The design parameters were composed specifically for mounting on 18 kW Free-Piston Linear Internal Combustion Engine linked to Electrical Generator equipped by Additional Auxiliary Drive [6], [7], and main its characteristics were based on previously presented modelling. EVEH was horizontally installed, and it was capable to annihilate rectilinear vibrations.…”

“…The authors developed several configurations of EVEH applicable for vibration damping in various rectilinear directions. The prototype of EVEH focused on tuning damping of Hybrid Complex vibrations was assembled on 18 kW Free-Piston Linear Internal Combustion Engine linked to Electrical Generator equipped by Additional Auxiliary Drive [6], [7] and tested. The operational frequency of Hybrid Complex was fixed and equal to 50 Hz.…”