Mechanical Efficiency of HMCVT under Steady‐State Conditions

Zhang, Guangqing; Zhang, Hengtong; Ge, Yaojun; Qiu, Wei; Xiao, Maohua; Xu, Xiaomei; Zhou, Minghui

doi:10.1155/2021/4275922

Cited by 8 publications

(9 citation statements)

References 23 publications

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“…According to relevant standards [15], the pressure pulsation under steady-state conditions is evaluated using peak to peak values. For steady-state data, when the data analysis duration meets certain conditions, the peak to peak value is approximately independent of the duration [16]; Under transient conditions, the peak to peak values obtained when the length is large can not accurately reflect the variation law of the peak to peak values, while the peak to peak values obtained when the length is small are unstable. Therefore, table 3 gives the peak to peak values of the pressure pulsation at the spiral casing inlet and the draft tube cone inlet for different time lengths (One time of the rated speed rotation period 1.0Tn, 1.2Tn, 1.4Tn... 3.0Tn), with the quantile of 1.5% and 98.5% (97% confidence level) respectively.…”

Section: % Rated Load Rejection Testmentioning

confidence: 98%

Study on load rejection test of pumped storage units

Luo,

Wang,

Zhao

et al. 2024

J. Phys.: Conf. Ser.

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The rise rate of rotating speed, the maximum inlet pressure of the spiral casing and the minimum inlet pressure of the draft tube cone of unit 2 in Jinzhai pumped storage power station were analyzed when 50% and 100% of the rated load were rejected in this paper. The low pass filtering method (cut off frequency is 0.2 times of the frequency) was used to process the pressure data at the inlet of the spiral casing and the draft tube cone to retain the trend term. The peak to peak values (97% confidence) of the pressure pulsation term under different data durations were studied, which provided technical support for rational and accurate calculation of the maximum inlet pressure of the spiral casing and the minimum inlet pressure of the draft tube cone, and provided an example reference for the load rejection test analysis of pumped storage units.

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Section: % Rated Load Rejection Testmentioning

confidence: 98%

Study on load rejection test of pumped storage units

Luo,

Wang,

Zhao

et al. 2024

J. Phys.: Conf. Ser.

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“…According to Equation (10), when displacement ratio ε ≥ 0, i a cI i b cI ≥ 0. In this working condition, the HMCVT's work doesn't have any phenomenon of the power cycle.…”

Section: Stage Hm 2 and Stage Hmmentioning

confidence: 99%

“…According to Equation (10), when displacement ratio ε < 0, i a cI i b cI < 0. In this working condition, the HMCVT has a power cycle phenomenon, and the calculation formula of HMCVT efficiency is as follows:…”

Section: Stage Hm 2 and Stage Hmmentioning

confidence: 99%

“…The performance of speed regulating transmission system of tractors, such as transmission ratio, the variation range of transmission ratio, transmission efficiency and so on, has a great influence on the fuel economy, dynamic property and other key performance indexes of the full tractor. The HMCVT (Hydro-Mechanical Continuously Variable Transmission) can realize continuously variable speeds in a large range and also inherits the advantages of mechanical transmission's high efficiency and hydraulic transmission's high power [7][8][9][10] while overcoming the disadvantages, and thus, can meet the requirements of agricultural machinery like tractors better. Therefore, the HMCVT is applied widely to agricultural and engineering machinery, such as tractors, and the research on HMCVT has great significance [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Research on HMCVT Parameter Design Optimization Based on the Service Characteristics of Agricultural Machinery in the Whole Life Cycle

Cheng

2023

Machines

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The HMCVT (Hydro-mechanical Continuously Variable Transmission) can realize continuously variable speed in a large range and transmit high power through power diving, and thus, it is widely applied in agricultural machineries, such as tractors. The engineering technology requirements of precision agriculture and intelligent agriculture have put forward higher requests for the research and development of HMCVT. In order to further improve the performance of HMCVT in the design stage and match the service characteristics of agricultural tractors in the whole life cycle, this paper proposes a new HMCVT optimization design method which mainly consists of 5 steps. The proposed method takes the regular and continuous transmission ratio variation, matching the working requirements in the whole life cycle of agricultural tractors and transmission efficiency maximization as comprehensive objectives. The improved genetic algorithm (I-GA) is applied. The HMCVT efficiency characteristic model combines the characteristic efficiency model of the hydraulic system, which has been verified, and the theoretical calculation model based on the engaging power method. By analyzing the statistical data of the tractor speed operating frequency in the whole life cycle, the proposed method is used to determine the weight of each hydro-mechanical power dividing stage (i.e., HM stage) service time. In the design process, the HMCVT efficiency is integrated with the displacement ratio so as to realize the evaluation of the maximum efficiency in the whole life cycle of the tractor. Research results show that the proposed method can improve HMCVT performance significantly, and the mean error between speed regulating characteristics and expected value in design is 1.04% or so. The HMCVT service efficiency in the whole life cycle of the tractor has been improved by 19.93%. The research in the paper offers a valuable reference for getting the law of HMCVT characteristics and performance improvement design of tractors.

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“…However, the above standards only provide a peak-to-peak value calculation method without noise interference, but actual vibration signals are inevitably affected by noise interference, and the relevant standards do not explain how to calculate the peak-to-peak values in this case. Fei Zhang et al [7,8] have systematically summarized the problems related to the calculation of peak-to-peak values under steady-state and transient operating conditions. At present, there is no doubt about the selection of the number of cycles for peak-to-peak value calculation under steady-state conditions, and the latest revised standards, GB/T 17189-2017 [9], IEC 60994 [10], and ISO 20816-2017 [11], require that the number of calculation cycles not be less than 8 or 10, and Fei Zhang et al [7] show that the number of cycles should not be less than 6 under steady-state conditions through a study of related cases.…”

Section: Introductionmentioning

confidence: 99%

Design of Non-Intrusive Online Monitoring System for Traction Elevators

Li,

Ning,

2024

Applied Sciences

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With the increase in elevator usage, more and more elevator real-time monitoring equipment is being applied to the operation of elevators. Traditional elevator monitoring equipment adopts a multi-sensor decentralized installation and layout, and the monitoring accuracy is low, which directly affects the effective alarm of the monitoring system; however, existing online monitoring systems cannot quickly alarm for faults. Aiming to solve the above problems, an elevator online monitoring system based on narrow-band Internet of Things (NB-IoT) is designed. The system is highly integrated with an STM32 main control chip, a six-axis acceleration gyroscope sensor, and an air pressure sensor to realize the edge calculation of the monitoring system. At the same time, this paper eliminates the temperature drift of the pressure sensor by using a temperature compensation algorithm and inputs the extracted characteristic parameters into the BP neural network for training to eliminate the zero drift so as to obtain the real-time height data of the elevator. The six-axis acceleration gyroscope sensor is used to calculate the posture so as to avoid the problem that a three-axis acceleration sensor or a three-axis gyroscope sensor alone cannot obtain accurate posture data. In order to further improve the monitoring accuracy, the peak-to-peak value of the signal is calculated by using a 95% confidence interval algorithm to reduce the suppression of the high-frequency components of the signal by noise and ensure that the signal has a large signal-to-noise ratio so that the obtained elevator car posture and vibration operation data are more accurate. Finally, the effectiveness of the proposed method is verified by experiments.

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Mechanical Efficiency of HMCVT under Steady‐State Conditions

Cited by 8 publications

References 23 publications

Study on load rejection test of pumped storage units

Study on load rejection test of pumped storage units

Research on HMCVT Parameter Design Optimization Based on the Service Characteristics of Agricultural Machinery in the Whole Life Cycle

Design of Non-Intrusive Online Monitoring System for Traction Elevators

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