Internal Gear Pump Pressure Balancing for Rotor Clearance
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Solution Overview
Problem
The unbalanced load in the discharge region of internal gear pumps causes a reduction in gear clearance and increases torque, leading to deteriorated sliding characteristics.
Innovation Solution
The internal gear pump incorporates a volume chamber with a restriction portion and a drain passage to guide and drain pressurized liquid, utilizing a wedge effect to counteract the unbalanced load by increasing oil pressure and reducing interference with suction flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pump operates in the discharge region, then liquid is pressurized and discharged, but an unbalanced load acts on the rotors causing gear clearance to decrease
Solution Approach 1:
The pump housing is segmented into multiple chambers: discharge chamber, volume chamber, and suction chamber. This segmentation allows independent pressure control in different regions, enabling the discharge chamber to maintain high pressure while the volume chamber maintains lower pressure to preserve gear clearance in the suction region.
Solution Approach 2:
The volume chamber acts as an intermediary between the discharge chamber and suction chamber. It receives pressurized liquid from the discharge chamber through a restriction portion, and releases it to the suction chamber through a drain passage, thereby mediating the pressure distribution to prevent excessive pressure buildup that would reduce gear clearance.
2Productivity
If the unbalanced load increases in the discharge region, then more liquid can be pressurized, but the sliding characteristics deteriorate due to reduced gear clearance
Solution Approach 1:
Different regions of the pump housing are given different pressure characteristics: the discharge chamber has high pressure for productivity, while the volume chamber and suction chamber maintain lower pressures to preserve gear clearance and sliding characteristics. This local differentiation of pressure quality resolves the contradiction between discharge capacity and reliability.
3Force
If the gear clearance becomes smaller, then the torque increases, but the sliding characteristics between the rotors deteriorate
Solution Approach 1:
The volume chamber serves as a pressure buffer that prevents direct transmission of high discharge pressure to the suction region. By controlling the flow through the restriction portion and drain passage, it maintains an intermediate pressure level that allows sufficient torque transmission while preserving adequate gear clearance for reliable sliding operation.
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 configuration effectively reduces the influence of unbalanced loads, suppresses oil pressure drops, and prevents cavitation, thereby improving sliding characteristics and torque performance.
Implementation Method 1
utilizing a wedge effect to counteract the unbalanced load by increasing oil pressure
Data Source
Figure 1
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Figure 3
AI summary
The internal gear pump 100A includes the pump portion 10 configured to discharge the oil when the drive shaft 1 is rotated, and the housing 20A that accommodates the pump portion 10. The pump portion 10 has: the inner rotor 11 having the plurality of external teeth 11a and connected to the drive shaft 1; and the outer rotor 12 having the plurality of internal teeth 12a in sliding contact with the external teeth 11a, the outer rotor 12 being arranged outside the inner rotor 11. The internal gear pump 100A has: the first volume chamber R1 facing the outer circumference of the outer rotor 12 in the discharge region 66, the first volume chamber R1 having the restriction portion T formed to extend along the outer circumference, the first volume chamber R1 being configured such that the pressurized oil discharged from the pump portion 10 is guided to the first volume chamber R1; and the drain passage 50 configured to drain, from the first volume chamber R1, the oil passed through the restriction portion T.