The Design Of Thermo-bulb Of Thermal Expansion Valve Stiffness Test System

The eligibility of thermal expansion valve thermal envelope stiffness directly determines the throttling function of automotive air conditioning refrigeration system.accurately testing the thermal expansion valve thermal envelope stiffness is a prerequisite for ensuring the performance of automotive air conditioning refrigeration systems.This paper focuses on the detection technology of the thermal expansion valve thermal bag stiffness,aiming to develop a system for testing the thermal bag stiffness of the thermal expansion valve.Firstly,according to analyzing temperature sensor package structure and working principle and the existing domestic and foreign industry standards and enterprise technical requirements,the hardware and software design scheme of the thermo-bulb of thermal expansion valve stiffness test system is put forward.The hardware part includes the main control unit,the detection unit,the crawling mobile unit,the EMS(Manufacturing Execution System)unit and the temperature control unit.The software part is divided into PLC software and interpersonal interface software.Secondly,the paper elaborates the structural design,unit implementation mechanism and the selection of key components of each unit in the hardware design of the thermal expansion valve stiffness test system for thermal expansion valve.After that,the PLC software design and human-computer interaction interface design in the software design of thermal expansion valve stiffness test system are introduced in detail.In order to ensure the test system's test data has a higher accuracy and accuracy,the test system adopts the speed segmentation method to achieve the position control of the stepper motor.Focused on verifying the control effect of different speed segmentation methods,the paper verifies the four-speed segmentation method and the three-speed segmentation method from the aspects of test force,operation displacement and detection cycle.It is verified that the displacement control accuracy of the four-step speed segmentation method is more in line with the requirements,and the accuracy of the test can be guaranteed.Finally,the paper verified the test system's production beat and uncertainty through test experiments.The performance index of the thermal expansion valve thermal bulb test system was introduced by introducing the machine capability index.The test results verified that the machine capability indices Cm and Cmk of the test system were all equal to or greater than 1.67,which was in line with the industry standards.