Development And Research On Key Technologies Of Descent Rescue Device Based On Escapement Principle

With the advancement of urbanization in our country, a large number of rural population enter into cities and towns, more and more high-rise buildings can solve the problem of urban land tension. But, high-rise buildings bring more social problems. It has the characteristics of integrated functions, complex performance and crowded personnel. In the event of fire, it is difficult to rescue and produce great harm to the social public security and people’s life and property. A large number of high-rise building fire accident statistic analysis showed that the best choice for the people is self-help escape during the high-rise building fire danger. Therefore, the government should strengthen the education of fire self-help and strengthen the consciousness of self-help at the scene of the fire. The people living and working in the high-rise building need the self-help device with the characteristics of safe, reliable, stable, efficient, easy to install and use. Based on the demand of the high-rise building fire self-help escape, this project studied the rescue and relief device based on the principle of escapement.This paper discusses the research background and significance in the field of high-rise building fire self-help escape systematically, analyzed the existing problems of escape device and life-saving research and development trend of the technology of slow down. Based on the investigation and study, the descent rescue device using intermittent impingement principle was proposed in this paper. Combined with the existing slow down technology, according to the design index and performance parameters of the the rescue and relief device, through the design scheme comparison, the overall design scheme of life-saving slow drop device based on the principle of escapement was formed. The motion and dynamic parameters of the deviceis calculated and determined. The structure design and calculation of the start unit, gear drive unit of mechanical system, speed control unit and the friction pressure unit was carried out detailedly. On the basis of the mechanical system design for the escapement type descent rescue device, the 3D model of all mechanical parts was established using Solidworks software. And the assembly and movement interference inspection was carried out simultaneously. Based on virtual prototype technology, the physical prototype model of mechanical transmission unit and speed control unit was established using the multi-body dynamics analysis software Adams. Adding constraint and load, the dynamic simulation analysis and research was carried on. The simulation results showed that the descent rescue device based on the principle of escapement can effectively control falling speed in the range of security, and reached the requirement of design index. In view of the design problems of existing product, the consumer demand for the self-help fire escape device was surveyed through the questionnaire survey way. From the perspective of the ergonomics, ease of use, security and humanized design, the appearance of the escapement type descent rescue device was designed.In order to guarantee the movement accuracy requirements of the escapement type descent rescue device during the working process, on the basis of the mechanical system structure design, the dynamic characteristics and the reliability and probability analysis theory of movement precision for the crank rocker mechanism considering kinematic pair clearance was studied. According to the theory of dynamics mechanism with clearance, the kinematic pair clearance of the crank rocker mechanism is described using the vector method. Using continuous contact model, kinematic pair clearance can be regarded as a bar without weight. Based on this method, the position analysis, motion parameters analysis, establishment and solving of dynamics equations, binding of motion pair analysis of the crank rocker mechanism with clearance was carried out and multibody system dynamics model was established. In the mechanical system of escapement descent rescue device, the dynamic characteristics of crank rocker mechanism with single kinematic pair clearance was researched and simulated. The studies have shown that the clearance size and crank speed has significant impact for kinematic and dynamic characteristics of mechanism with clearance. Considering the random-ness of kinematic pair clearance error, applying the clearance error to the probability statistics and stochastic process theory in the form of size parameter error, the movement precision of mechanism with clearance reliability probability analysis mathematical modelwas established. For the crank rocker mechanism with clearance, the influence of the variance of mechanism motion in view of kinematic pair clearance was researched. Motion precision reliability of crank rocker mechanism with clearance probability analysis theory was formed.To test the performance of the descent rescue device based on the principle of escapement, according to the conclusion of mechanical system design and theoretical research, by the proportion of real processing production, the experimental prototype of the descent rescue device was processed. According to different test object(sandbags and people), the time data of fall test was tested during different load, different drop height. The performance test results shown that the average falling speed of trapped personnel can be controlled in the range of 2 m/s using the descent rescue device. The device has the function of landing safely, and the average drop speed reached the design requirements. The test control system composed by the test controller and computer was established. The angular velocity and angular acceleration of the main transmission shaft was measured by high precision of photoelectric encoder. PC can monitor and process the live date and show the running state and curve.In order to improve the performance of mechanical system for the escape device, the design idea using runaway escapement to realize the speed control which based on the speed control principle and characteristics of mechanism and structure was formed. According to the structural characteristics of runaway escapement mechanism and the design requirements, the escapement structure design was improved. Using the multi-body dynamics analysis software Adams, the virtual prototype model is set up. The movement cycle and the influence of dynamic performance to runaway escapement mechanism of friction coefficient, driving moment, center distance, moment of inertia of the escapement wheel and pendulum was simulated. The overall mechanical structure design of descent rescue device was improved using the Solidworks software platform. The mechanical system was divided into two parts: speed control unit and friction pressure unit. The virtual prototype model of the improved descent rescue device was built based on virtual prototype technology. And the performance of the device was simulated and analysed. Studies have shown that the performance of the improved device has greatly improved under the same design parameters.