Design of the integrated precision pneumatic seed metering device for rapeseed using TRIZ-AD

A pneumatic seed metering device is required for the high speed and intelligent variable operation in recent years. However, the existing complicated transmission and pneumatic system and mechanical structure cannot fully meet the large-scale production of pneumatic supply with the high stability, due mainly to the pressure loss caused by a curved pipe. In this study, the invention problem problem-solving theory (TRIZ) and axiomatic theory design (AD) methods were applied to carry out the innovative design of a pneumatic seeding device for rapeseed. Firstly, the seeding maturity prediction and evolution were used to clarify the development stage, evolution path, and potential of seed metering using TRIZ technology. The existing seeding technology was in a recession recovery period, while the evolution of the technology system was in line with the S-curve evolutionary law and evolutionary model. The future seed metering device was preferred for the integration in the simple, microscopic, controllable, and automated evolutionary path. Secondly, the design process model was established using the integration of TRIZ and AD. TRIZ tools were introduced in the process of mapping functional to structural domains. Among them, the "conflict resolution principles" was adopted to solve the contradiction and conflicts of the transmission and pneumatic systems in the existing seed metering device. The invention principles were selected to optimize the structural parameters. Finally, the motor was utilized to directly drive the seeding disk and the built-in air chamber of the fan. The original design matrix was developed using independent design axioms and the minimum entropy. An innovative system was designed to integrate the motor- fan with the pneumatic seed metering device for rape. The trial production and processing were performed on two technical implementation schemes. The motor fan was determined to arrange on the same side after optimization, particularly for the better airtightness and structural stability. The integrated motor drive was used to simplify the transmission, whereas, the integrated fan was to eliminate the gas transmission pipe, in order to reduce the wind pressure loss. As such, the improved transmission and pneumatic system were required only a small space without the additional power. The test results show that the integrated seed metering device was fully meetmet the requirements of single seed metering. A better performance was achieved in the qualified index is more than 90%, even reached reaching up to 99.82%, when the absolute value of suction negative pressure was 1.0-2.0 kPa and the working speed was less than 7 km/h. The required pressure for the qualified index of 90% was lower than before. The innovative design of the pneumatic seed metering device was integrated the power and pneumatic sources, which was were in the line with the technological system evolution path, individual start and stop of the seeding unit without any influence on the rows. More importantly, the mechanical structure and transmission were better matched for the development trend of intelligent variables. This finding can provide an innovative design idea and references for the design of a pneumatic seed device.