Electric or Hydraulic Energy Recovery Systems in a Reach Truck– A Comparison

Abstract

In this paper, electric and hydraulic regeneration methods of recovering potential energy from an electro-hydraulic forklift truck are studied. Two similar forklift setups equipped with either electric or direct hydraulic energy storage are compared. In the first setup, the forklift lifting system is controlled directly with an electric servomotor drive. The servomotor drives a hydraulic pump capable of also operating as a hydraulic motor during lowering motion. In the second setup, the hydraulically operated forklift is equipped with an energy recovery system consisting of pressure accumulators for storing energy and a hydraulic digital valve package for precise leakage free flow control. This paper describes the arrangements of the experimental setups. The results of the proposed systems are then compared from the energy efficiency point of view. Energy-savings ratios for electric and hydraulic test systems were calculated for different fork velocities and payloads.

Dynamic characteristics of coupling model of valve-controlled cylinder parallel accumulator

“…To address energy conservation, the accumulator is integrated to develop a five-valve flow control and is combined with a new algorithm to keep accurate motion-tracking performance of the hydraulic cylinder and reduce energy consumption [13]. According to modeling and simulation, the accumulator's highest energy conservation rate of potential energy recovery in an electric hydraulic forklift is 36% [14,15]. As a source of auxiliary power, the accumulator improves the complex nonlinear response and control accuracy of valve-controlled motors; AMESIM and Simulink models are adopted to make dynamic simulations [16].…”

Investigation of the Energy Regeneration and Control Strategy of a Crane Hoisting System

“…Minav et al proposed using a forklift as an experimental platform for comparing hydraulic with electrical recovery schemes in terms of fuel consumption and service performance [3] and [4]. It can be seen from the results that the hydraulic type is the better choice rather than the electric one in terms of fuel-saving rate.…”

Structural-parametric synthesis of hydro-mechanical drive of hoisting and lowering mechanism of package-forming machines

“…Energy regeneration system for hybrid hydraulic transport modules [12] revealed that approximately 41 % of potential energy can be regenerated in case of introduction of a battery. On the other hand, it is a widely acknowledged [13] that many of hydraulic systems for prevention of hydraulic pulse and overloading are equipped with hydraulic batteries. Hydro-gas batteries are used in drives of hoisting and lowering mechanisms of package-forming machines, which requires new technical solutions for energy efficient systems.…”

“…To solve the set problem, it is proposed to construct a drive of a hoisting and lowering mechanism of a package-forming machine by the following scheme ( Fig. 1) with the use of the hydro-gas battery NTR 0.35 [13]: maximum operating pressure up to 250 bars, operation temperature (-20...+80 ºC). In the presence of an elastic element (gas) and significant weight, accordingly, inertia of the piston can cause its self-oscillations.…”