Performance analysis of hydrodynamic mechanical power-split transmissions

Abstract

The objective of this study was to evaluate the performance of 24 basic hydrodynamic mechanical power-split (HMPS) transmission designs effectively based on their torque multiplication capacities (TMCs) and efficiencies. Firstly, four schemes were preliminarily selected. Secondly, the matching between the four schemes and a reference wheel loader was considered, and an expression for the TMC was developed based on the traditional transmission and a second reference transmission. Thirdly, two performance metrics in terms of the TMC and efficiency – the average torque multiplication capacity (ATMC) and average efficiency – were defined to eliminate the couplings of four transmission parameters with the vehicle speed and speed ratio. Finally, the performances of the two best schemes and traditional hydrodynamic mechanical (HM) transmission were carefully compared. The results show that a transmission with power recirculation cannot present energy savings potential regardless of the ATMC, whereas a transmission with a power split can achieve an ATMC of 0.255, an average efficiency increment of 0.0143 in the short loading cycle, and a miniscule efficiency increment in the long loading cycle compared with the HM transmission.

Research on energy‐saving technology of loader hydraulic torque converter based on MATLAB dynamic characteristic simulation

“…Therefore, this research analyzes the energy saving of the hydraulic torque converter of the loader, and also needs to conduct a dynamic study on the matching characteristics between the two. When the loader is faced with different tasks and working in different environments, the dynamic characteristic here refers to the adjustment of the load control by the torque converter according to the parameters such as speed, temperature, pressure and other parameters fed back by the sensor 18 . Therefore, the following assumptions are proposed for the matching control of engine and hydraulic torque converter: (1) The matching curve is close to the maximum output torque and power of the engine.…”

“…When the loader is faced with different tasks and working in different environments, the dynamic characteristic here refers to the adjustment of the load control by the torque converter according to the parameters such as speed, temperature, pressure and other parameters fed back by the sensor. 18 Therefore, the following assumptions are proposed for the matching control of engine and hydraulic torque converter: (1) The matching curve is close to the maximum output torque and power of the engine. (2) The high efficiency area of the hydraulic torque converter is close to the maximum power point of the engine, ensuring that the vehicle has good power and economy in the high efficiency area.…”

An optimal-pressure control strategy for hydrostatic wheel loader

“…The charge pump continuously replenishes the leakage flow to the low-pressure line and the relief valve (V2) guarantees the low pressure p l constant. Besides, during the normal operating conditions, the relief valve connected to the high-pressure pipeline (V1) will not open, thus, Q h = 0 in equations ( 4) and (5).…”

“…3,4 Compared with gearbox transmission, an HST provides engine optimization and smooth drive owing to its continuously variable transmission (CVT) function. 5 However, the main drawback of HST is its low efficiency due to its double energy conversion. 6,7…”

“…3,4 Compared with gearbox transmission, an HST provides engine optimization and smooth drive owing to its continuously variable transmission (CVT) function. 5 However, the main drawback of HST is its low efficiency due to its double energy conversion. 6,7 There are three methods to reduce fuel consumption of hydrostatic wheel loaders: optimize powertrain configuration, increase hydraulic components efficiency and improve control strategy.…”