Reversible Gerotor Pump with Active Eccentricity Control

Solution Overview

Problem

Existing gerotor pumps are not reversible, leading to flow direction inversion when the inner rotor changes direction, causing issues such as fluid discharge through the inlet and vice versa, and resulting in friction losses and wear.

Innovation Solution

A reversible gerotor pump design where the inner housing is actively controlled to displace the outer rotor based on the drive shaft's rotation direction, maintaining fluid flow direction without additional friction elements, using a positioning device like a pneumatic cylinder to adjust the rotors' eccentricity, ensuring the inlet always communicates with an expanding cavity and the outlet with a decreasing cavity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If friction elements are arranged between the outer rotor and housing to enable reversibility, then the pump can rotate in both directions, but friction losses and wear increase

Engineering Contradiction:

ImprovereversibilityVSAvoidfriction losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent removes the friction elements from the system entirely. Instead of using friction elements to enable the outer rotor to rotate in both directions, the invention uses a positioning device that actively controls the position of the inner housing and outer rotor based on drive shaft rotation direction, eliminating the need for friction elements and their associated losses.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical friction-based reversing mechanism with an active control system using a positioning device (such as a pneumatic cylinder) that responds to the rotation direction of the drive shaft. This substitution eliminates direct mechanical contact and friction between the outer rotor and housing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If friction elements are used to rotate the outer rotor for reversibility, then bidirectional rotation is achieved, but wear increases

Engineering Contradiction:

ImprovereversibilityVSAvoidwear

Core Design Contradiction:

Adaptability or versatilityVSEase of repair

Solution Approach 1:

The patent removes the friction elements from the system entirely. Instead of using friction elements to enable the outer rotor to rotate in both directions, the invention uses a positioning device that actively controls the position of the inner housing and outer rotor based on drive shaft rotation direction, eliminating the need for friction elements and their associated wear.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical friction-based reversing mechanism with an active control system using a positioning device (such as a pneumatic cylinder) that responds to the rotation direction of the drive shaft. This substitution eliminates direct mechanical contact and friction between the outer rotor and housing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the inner rotor rotation direction changes in a non-reversible pump, then the pump structure remains simple, but flow direction inverts causing fluid discharge through the inlet

Engineering Contradiction:

Improvepump structureVSAvoidflow direction inversion

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces dynamic adjustment of the rotor positions based on the rotation direction of the drive shaft. The positioning device actively responds to changes in drive shaft rotation direction and adjusts the position of the inner housing and outer rotor accordingly, allowing the pump to adapt its geometry to maintain correct flow direction regardless of rotation direction.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the geometric parameters of the pump by adjusting the position of the inner housing and outer rotor relative to each other based on drive shaft rotation direction. This parameter adjustment ensures that the inlet and outlet ports remain in the correct positions relative to the expanding and decreasing cavities, preventing flow direction inversion.

Inventive Principle:

Principle #35Parameter changes

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

The solution achieves a reversible positive displacement pump with minimized drag losses and wear, maintaining efficient fluid flow regardless of rotation direction, eliminating the need for friction elements and reducing friction losses.

Implementation Method 1

A reversible pump (10) for a fluid... A positioning device (32) is arranged in connection with the inner housing (18)... adapted to be actively controlled to displace the inner housing (18) and the outer rotor (14) based on the direction of rotation of the drive shaft (16)

Methodology Applied

Scientific EffectPneumatic pressure: Pressure Increase

Implementation Method 2

an internally toothed outer rotor (14) with a circular periphery surrounding the inner rotor (12)... wherein the outer rotor (14) is eccentrically arranged in meshing engagement with the inner rotor (12), such that variable cavities (26) are formed between the inner rotor (12) and the outer rotor (14)

Methodology Applied

Scientific EffectEccentric rotation: Eccentric

Implementation Method 3

On the suction side a cavity expands, negative pressure is created and the fluid may thereby flow through an inlet into the cavity. On the discharge side a cavity decreases, compression occurs and the fluid is pumped out from the cavity through an outlet

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3295031B1A reversible pump and a method to control a reversible pump

Publication Date: 2022.03.23 SCANIA CV AB

Figure 1
Figure 2a~2b
Figure 3a~3b

AI summary

The invention relates to a reversible pump (10) for a fluid, comprising an externally toothed inner rotor (12); an internally toothed outer rotor (14) with a circular periphery surrounding the inner rotor (12); a drive shaft (16) 5 concentrically connected to the inner rotor (12), an inner housing (18) surrounding the outer rotor (14); an outer housing (20); an inlet (22) and an outlet (24) for the fluid arranged mirror symmetric on opposing sides of the drive shaft (16) and of a reference line (R) extending perpendicularly to the longitudinal extension of the drive shaft (16), wherein the inner rotor (12) has 10 one less tooth than the outer rotor (14) and wherein the outer rotor (14) is eccentrically arranged in meshing engagement with the inner rotor (12), such that variable cavities (26, 26', 26'') are formed between the inner rotor (12) and the outer rotor (14), wherein the inlet (22) and the outlet (24) are each arranged in fluid communication with a cavity (26', 26''). A positioning device 15 (32) is arranged in connection with the inner housing (18), wherein the positioning device (32) is adapted to be actively controlled to displace the inner housing (18) and the outer rotor (14) based on the rotational direction of the drive shaft (16), such that the centre of rotation of the outer rotor (34) is displaced along the reference line (R). 20 The invention also relates to a method to control such a reversible pump (10), a gearbox (4), a vehicle (1), a computer program (P) and a computer program product. 25