The Development And Research Of Monitoring System In Hydraulic Transmissions

The production and sales volume of loaders occupy an absolute market share in construction machinery industry. China has now become a big manufacturing country of loaders in the world. However, what distinguishes foreign-made loaders from homemade loaders is in their high reliability and long life cycle. The current situation within domestic loading machinery manufacturers is that production capacity determines production and sales volume. In order to meet their planned production indexes, most loading machinery manufacturers give more attention to production than to the study of improvement of products reliability and life cycle. Statistics show that problems with the power system of homemade loading machines account for about 44%. The key parts of the power system are the engine and hydraulic transmission (herein refers to the power shifting transmission case and the hydraulic torque converter). This paper probes into the monitoring of pressure, fluid flux, temperature, speed of revolution, torque and other major performance parameters before the hydraulic transmission assembly is fitted on ZL40 and ZL50 loaders. Through research and analysis of the structure and performance parameters of hydraulic transmissions for loaders, this paper points out that the monitoring and analysis of performance parameters of hydraulic transmissions should be conducted before they are assembled in the loaders. In this paper, a test stand for monitoring performances of hydraulic transmissions for loaders has been designed, putting to an end judging performances of transmission cases and torque converters for loaders by intuition and experience. This paper is also of great importance for the design of test stand for monitoring performances of hydraulic transmissions for construction machinery of the same kind in terms of analysis in theory, the setting of monitoring parameters, whole design of structure, selection of monitoring sensors and design of man-machine interface. The paper is divided into five parts, including: 1.The paper points out the urgency and necessity of the study of hydraulic transmissions after analyzing the production and sales volume of homemade loaders in the same industry and the current situation of homemade and foreign-made transmission cases and torque converters for loaders. 2.Deep analysis of the structure of hydraulic transmissions for loaders and their performances has been made so as to have a full understanding of key parameter indexes that could affect the power transmitting efficiency of loaders, based on which thoughts on the design of test stand are formulated. This makes troubleshooting process simple and easy and the analysis of data obtained from test possible. 3.This paper elucidates the importance and purpose of testing items to be monitored in terms of the performances of torque, pressure, flow, temperature, rotate speed and other relevant parameters exhibited in operation, thus formulating a parameter cross reference table for key items to be monitored. In this paper, the overall structure of the test stand and a whole set of testing proposals for it have been designed, with the focus laying on mechanical connection of key machinery parts. And this can help to test different transmissions in relation to different connecting parts. 4.In this paper, the sensor selection principle is described based on the study and analysis of the collection of test parameters. In particular, a fairly comprehensive theoretical analysis of sensors for testing parameters has been made. Top priority has been given to economy, practicality, precision and reliability in choosing sensors for testing parameters, which will provide references for future design of test stand of the same kind. 5.In this paper, the test and control system software for the monitoring test stand of transmission assembly is developed, and its design thought and the software structure diagram are described. The description focuses on how collection card/control card software is programmed with BV6.0 platform in windows98 operating system. Of high test precision, the monitoring test stand can be operated automatically, with powerful data processing capacity. It also boasts computer controlled gear shifting function and variable speed pump start-up testing function. In the end, the paper gives a description of man-machine interface, which is far from being perfect and still needs further improvement.