Fuel Pump Casing Recessed Portion Rotation Stopper
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Solution Overview
Problem
Conventional fuel pumps are prone to efficiency deterioration and discharge amount reduction due to positional displacement of the casing caused by foreign substances getting stuck between the rotors, leading to a locked state where the outer rotor cannot rotate relative to the inner rotor, resulting in a single body rotation with the casing, which applies a large force and attempts to rotate the housing, potentially offsetting the intake or discharge ports.
Innovation Solution
The fuel pump incorporates a recessed portion on the casing's outer surface, which prevents deformation in specific areas during press fitting, acting as a rotation stopper when foreign substances cause a locked state, thereby preventing casing displacement and maintaining pump efficiency by catching on the recessed portion's wall surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the casing is press fit into the housing without a recessed portion, then the casing can be securely fixed, but the casing may rotate and displace when foreign substances cause a locked state between the rotors
Solution Approach 1:
The recessed portion is formed at a specific location on the outer circumferential surface of the casing, creating a localized feature that prevents rotation. This local modification allows the rest of the casing to maintain its press fit fixation while adding rotational prevention capability at the specific location where the recessed portion is formed.
Solution Approach 2:
The recessed portion acts as an intermediary element between the casing and the housing. When the casing is press fit into the housing, the recessed portion engages with the housing to prevent rotation, serving as a mediator that transmits and limits rotational force while maintaining the press fit connection.
2Adaptability or versatility
If foreign substances get stuck between the rotors, then the rotors become locked, but this causes the casing to rotate and displace, deteriorating pump efficiency
Solution Approach 1:
The recessed portion is pre-formed on the casing before operation, creating a preventive measure against rotation. When foreign substances cause the rotors to lock, the recessed portion already exists to counteract the rotational force, preventing casing displacement and maintaining pump efficiency.
Solution Approach 2:
The recessed portion converts the harmful rotational force generated by rotor locking into a beneficial stopping mechanism. When the rotors lock due to foreign substances, the resulting rotational force is counteracted by the recessed portion engaging with the housing, transforming the potential harm into a controlled stopping action that prevents efficiency deterioration.
3Ease of operation
If the outer rotor is disposed eccentrically with respect to the inner rotor, then the pump can function, but the rotors become a single body in locked state, applying large force to the housing
Solution Approach 1:
The recessed portion is strategically positioned on the outer circumferential surface of the casing to specifically address the rotational force issue. This local feature does not interfere with the eccentric operation of the rotors but provides a localized stopping point where the rotational force is counteracted when the rotors lock.
Solution Approach 2:
The recessed portion is pre-formed on the casing to prepare for the event of rotor locking. Before the rotors lock and generate large rotational force, the recessed portion is already in place to receive and counteract this force, preventing the casing from rotating and displacing relative to the housing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses casing displacement and maintains pump efficiency by utilizing recessed portions on the casing to function as rotation stoppers, preventing the casing from rotating and ensuring optimal port positioning, thus preventing efficiency deterioration.
Implementation Method 1
a portion of the housing which does not face the recessed portion (press fitting deformation portion) is deformed so as to be enlarged in a radial direction (press fitting deformation) when the casing is press fit into the housing
Data Source
AI summary
A fuel pump includes an inner rotor, an outer rotor, a casing, and a housing. The inner rotor includes outward teeth. The outer rotor includes inward teeth geared with the outward teeth. The casing houses the inner rotor and the outer rotor, and forms a variable capacity pump chamber between the inward teeth and the outward teeth. The housing is formed in a cylindrical shape and includes a cylindrical inner portion, the casing being press fit into the cylindrical inner portion. A recessed portion is formed at a predetermined position in a circumferential direction of an outer circumferential surface of the casing, the recessed portion being recessed toward a radial direction center of the outer circumferential surface.