hydrostatic transmission
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Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 376
Author(s):  
Biswaranjan Mohanty ◽  
Kim A. Stelson

Hydrostatic transmissions are commonly used in heavy-duty equipment for their design flexibility and superior power density. Compared to a conventional wind turbine transmission, a hydrostatic transmission (HST) is a lighter, more reliable, cheaper, continuously variable alternative for a wind turbine. In this paper, for the first time, a validated dynamical model and controlled experiment have been used to analyze the performance of a hydrostatic transmission with a fixed-displacement pump and a variable-displacement motor for community wind turbines. From the dynamics of the HST, a pressure control strategy is designed to maximize the power capture. A hardware-in-the-loop simulation is developed to experimentally validate the performance and efficiency of the HST drive train control in a 60 kW virtual wind turbine environment. The HST turbine is extensively evaluated under steady and time-varying wind on a state-of-the-art power regenerative hydrostatic dynamometer. The proposed controller tracks the optimal tip-speed ratio to maximize power capture.


2021 ◽  
Author(s):  
Johnathan (Hans) Barkei ◽  
Perry Y. Li

Abstract A hydro-mechanical transmission (HMT) transmits power both mechanically and hydraulically allowing continuously variable transmission ratios and more efficient transmission than hydrostatic transmission. A conventional HMT tends to be costly and bulky since it has a hydrostatic transmission in parallel with a mechanical transmission. An alternative is a compact inline configuration that utilizes a two-shafted pump that is mechanically and hydraulically connected to a motor. This avoids the need for a planetary gear set while providing the HMT functionality. When the pump/motor displacement is zero, all of the power is transmitted mechanically and the transmission ratio is unity, a condition referred to as lock-up that is expected to be very efficient. Previous research however has shown significant losses at this operating condition in experiments. This is thought to be caused primarily by compressibility losses due to the repeated unnecessary opening and closing of the distributor valves. This paper first models the Hondamatic in simulations to confirm that compressibility losses contribute to the low efficiency at lock-up. Second, the paper proposes a solution to reduce these compressibility losses by means of a second cam mode that closes the distributor valves to prevent flow between the piston and the high and low pressure volumes. The performance of the existing inline HMT and the proposed solution at lock-up are modeled in simulations and compared. The results indicate a 10% increase in efficiency at lock-up.


2021 ◽  
Author(s):  
Ashok Kumar Rajendran ◽  
Vijaykumar Bagadekar ◽  
Satya Pavan Alavilli

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 243
Author(s):  
Xiaofan Guo ◽  
Andrea Vacca

This paper presents a novel method for designing and sizing high-efficient hydrostatic transmissions (HTs) for heavy duty propulsion applications such as agricultural and construction machinery. The proposed method consists in providing cost effective HT architectures that maximizes efficiency at the most frequent operating conditions of the transmission, as opposed to the traditional HT design methods based on the most demanding requirements of the system. The sizing method is based on a genetic optimization algorithm for calculating the optimal displacement of the main units of the HT to maximizes the efficiency in the most frequent operating conditions of the vehicle. A simulation model for HTs is built in MATLAB/Simulink® environment to test three different circuit alternatives for basic HTs. Considering a particular 250 kW heavy-duty application for which drive cycle data were available, this study shows great improvement in energy efficiency (14%) and power saving (20.1%) at frequent operating conditions while still achieving the corner power condition.


Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 466
Author(s):  
Zhijie Liu ◽  
Guoqiang Zhang ◽  
Guoping Chu ◽  
Hanlin Niu ◽  
Yazhou Zhang ◽  
...  

In recent years, research into and development of hillside tractors has become a popular topic in the field of agricultural engineering in China. To solve the main problems associated with a low adjustment range of the working speed, complex operation, and low safety for slope operation of medium-sized crawler tractors, a hydrostatic drive system that can be used for hillside crawler tractors was designed. According to the operation requirements of a hillside crawler tractor, the parameters of the three-cylinder diesel engine, hydrostatic transmission (HST), drive rear axle, and other key components of the drive system were matched after the force and motion analyses of the tractor, and then the main performance indicators, including the traction performance, system pressure and working speed of the drive system were verified. On this basis, a drive system performance test bench was built, and the traction performance and starting acceleration performance of the drive system was tested. The results of the traction bench test show that when the engine was at the maximum torque point of 1700 r/min, the maximum theoretical tractive force outputted by the tractor in Gear I was 114,563 N, and the maximum theoretical tractive force outputted by tractor in Gear II was 10,959.2 N, which were both larger than the traction resistance of 9550.6 N experienced by the hillside tractor ploughing on the slope. The results of the initial acceleration bench test show that the tractor driving speed can gradually increase with increasing output of the variable pump and can reach the maximum in 3 s. When the tractor was driving on flat ground, the maximum driving speeds of Gear I, Gear II, and Gear III were 4.65 km/h, 6.58 km/h, and 8.57 km/h, respectively, which are close to the theoretical values. When the tractor was driving on a 15° slope, the maximum driving speeds of Gear I, Gear II, and Gear III were 4.55 km/h, 6.25 km/h, and 8.28 km/h, respectively. It can be concluded that the design matching of the drive system is reasonable, the speed consistency is good and there is enough power reserve, which can meet the requirements for a large workload.


2021 ◽  
Vol 6 (2) ◽  
pp. 2970-2977
Author(s):  
Marco Bolignari ◽  
Gianluca Rizzello ◽  
Luca Zaccarian ◽  
Marco Fontana

Author(s):  
Zhenhe Li ◽  
Zhicheng Wang ◽  
Changjian Zhi ◽  
Daxiang Zhang ◽  
Xianchen Song ◽  
...  

Compared to conventional pumping units with low efficiencies and general hydraulic pumping units using hydraulic accumulators to recover and reuse energy, this article presents a novel multi-source hydraulic pumping unit with the symmetrical structure in order to save energy. First, the balanced mechanical structure through the symmetrical arrangement of double wells can not only decrease the total power of the system significantly but also make the power consumption of the pumping unit drop substantially in the constant speed phase. Uniquely, the proposed pumping unit is jointly driven by a hydrostatic transmission hydraulic system and a small-scale solar–wind hybrid power generation system. The hydrostatic transmission technique enables the system power output to adapt to the load requirements in real time without extra throttling and overflow losses, while the solar–wind hybrid system drives alone in the constant speed phase to save energy and bring environmental benefits. After parameter analyses and calculations, the energy-saving advantage of the proposed system is displayed when compared to a counterpart. Then, the mathematical model of the system is developed, and the rule-based energy management strategy is designed for the energy distribution of the proposed system. The simulation results verify that the feasibility and reasonableness of the proposed system.


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