Rotor Drive Mechanism for Eccentric Screw Pump
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Solution Overview
Problem
Conventional uniaxial eccentric screw pumps have a lengthy design that increases the size and volume of the pump apparatus, leading to inefficiencies in fluid transfer and reduced seal life due to axial runout and fluid loss during washing.
Innovation Solution
The rotor drive mechanism incorporates a connecting shaft that overlaps with the driving shaft to shorten the axial length, utilizing universal or eccentric joints to prevent fluid contact and axial runout, and sealing the inner space to reduce fluid volume and maintain seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the connecting shaft and joint portions are arranged in series outside the driving shaft, then the rotor can achieve eccentric rotational movement, but the longitudinal length of the pump apparatus increases
Solution Approach 1:
The connecting shaft is positioned inside the driving shaft, and the joint portions are arranged within the fluid accommodating space, creating a nested configuration that reduces the overall longitudinal length while maintaining the eccentric rotational movement capability
Solution Approach 2:
The joint portions are arranged in the radial direction rather than extending axially, changing the spatial dimension of the mechanism layout to reduce longitudinal length while preserving functional capability
2Device complexity
If the connecting shaft and joint portions are arranged in series, then the rotor drive mechanism is simple, but the fluid accommodating space volume increases causing fluid loss
Solution Approach 1:
The connecting shaft is nested within the driving shaft, and the joint portions are contained within the fluid accommodating space boundaries, minimizing the volume occupied by mechanical components and reducing the amount of fluid that must be discarded during washing
3Speed
If the connecting shaft is inclined with respect to the axial direction, then the rotor can rotate, but axial runout occurs reducing seal life
Solution Approach 1:
The second joint portion is positioned asymmetrically on the radially inward side of the bearing portion, creating an offset configuration that compensates for axial runout caused by the inclined connecting shaft, thereby extending seal life while maintaining rotor rotation capability
Data Source
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AI summary
The present invention provides a rotor drive mechanism capable of reducing the longitudinal size of a pump apparatus and the volume of a fluid accommodating space in a casing, and improving the accuracy of a discharge rate. A rotor drive mechanism 25 is configured to transfer rotation of a driving shaft 38 to an external screw type rotor 22 of a uniaxial eccentric screw pump 23 via a connecting shaft 39, the driving shaft 38 being rotated such that the center thereof is located at a fixed position. The rotor drive mechanism 25 is configured such that: the driving shaft 38 includes an inner space 46 which is open toward the rotor 22; the connecting shaft 39 is inserted in the inner space 46; a rear end portion of the connecting shaft 39 is connected to the driving shaft 38 via a second joint portion 48; a tip end portion of the connecting shaft 39 is connected to the rotor 22 via a first joint portion 47; and a first seal portion 55 seals between an inner peripheral surface of an opening of the driving shaft 38, the opening being open toward the rotor 22, and an outer peripheral surface of the rotor shaft 37 connected to the rotor 22 configured to carry out an eccentric rotational movement.