Concentric Piston Hydraulic Pump With Locking for Variable Flow

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Solution Overview

Problem

Current axial piston pump designs face issues with mechanical complications, operational inefficiency, and vibration/noise due to dynamic torque changes, particularly in systems with varying fluid flow requirements.

Innovation Solution

A variable displacement hydraulic device with concentrically positioned pistons and a locking mechanism that allows for independent control of piston motion, enabling variable displacement by inhibiting the reciprocal motion of one piston while maintaining operation of the other, using hydraulic or mechanical locking mechanisms to decouple pistons from the actuator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable angle rotating drive plates (wobble plate) are used to dynamically change fluid flow in response to changing torque conditions, then adaptability to dynamic torque conditions is improved, but device complexity and mechanical complications increase

Engineering Contradiction:
Improveadaptability to dynamic torque conditionsVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The hydraulic device is segmented into multiple independent piston-cylinder assemblies (first and second pistons with respective cylinders) that can operate independently or in combination. Each piston assembly can be individually locked or unlocked, allowing selective control of fluid displacement. This segmentation enables adaptability to varying torque conditions without requiring complex variable angle drive plates, as the system can simply engage or disengage specific piston assemblies based on demand.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If variable angle rotating drive plates (wobble plate) are used to dynamically change fluid flow, then adaptability is improved, but maintenance costs and operational efficiency worsen

Engineering Contradiction:
Improveadaptability to dynamic torque conditionsVSAvoidmaintenance costs and operational efficiency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The locking mechanism is designed to be actuated by the system's own hydraulic fluid, allowing the pistons to lock and unlock automatically based on system conditions without requiring external mechanical intervention. The hydraulic fluid itself serves as the actuating medium, simplifying the control system and reducing maintenance requirements compared to mechanically complex variable angle drive plate mechanisms.

Inventive Principle:
Principle #25Self-service

3Power

If current axial piston pump designs are used, then hydraulic power transmission is achieved, but vibration and noise are generated

Engineering Contradiction:
Improvehydraulic power transmissionVSAvoidvibration and noise
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

Multiple piston-cylinder assemblies are merged into a single integrated housing with common inlet and outlet ports. The pistons are positioned concentrically along the same reciprocation axis, and their fluid outputs are combined and delivered through a common outlet. This merging approach balances the reciprocating motions of multiple pistons, reducing vibration and noise while maintaining effective hydraulic power transmission.

Inventive Principle:
Principle #5Merging (Combining)

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 reduces maintenance costs and operational inefficiencies by allowing adaptive fluid flow control, minimizing vibration and noise, and enhancing operational efficiency in dynamic torque conditions.

Implementation Method 1

a locking mechanism for inhibiting the first reciprocal motion of the first piston; wherein when engaged the locking mechanism inhibits the first portion of said outputting of the hydraulic fluid by decoupling the first piston from the actuator

Methodology Applied
Scientific EffectMechanical locking: Mechanical Fastener

Implementation Method 2

a first cylinder positioned in the housing along the reciprocation axis, the first cylinder having a first input for receiving the hydraulic fluid on a first intake stroke and a first output for ejecting the hydraulic fluid on a first exhaust stroke

Methodology Applied
Scientific EffectHydraulic pressure and flow: Hydraulic Press

Data Source

PatentEP4474643B1Piston in piston variable displacement hydraulic device
Publication Date: 2026.02.04 TONAND BRAKES INC
  • EP4474643B1 patent drawingFigure 1
  • EP4474643B1 patent drawingFigure 2
  • EP4474643B1 patent drawingFigure 3

AI summary

A variable displacement hydraulic device (20) comprising a housing (25) having an inlet (135) for receiving hydraulic fluid and an outlet (125) for outputting the hydraulic fluid, the housing (25) having a reciprocation axis (11); a first cylinder (110) having a first input (112) for receiving the hydraulic fluid on a first intake stroke and a first output (127) for ejecting the hydraulic fluid on a first exhaust stroke; a first piston (105) within the first cylinder (110), the first piston (105) coupled to an actuator (85) causing the first reciprocal motion; a second cylinder (120) positioned in the first piston (105) having a second input (113) and a second output (126); a second piston (115) positioned for a second reciprocal motion within the second cylinder (120) coupled to the actuator (85); and a locking mechanism (14) for inhibiting a first reciprocal motion of the first piston (105); wherein when engaged the locking mechanism (14) inhibits a first portion of the outputting of the hydraulic fluid by decoupling the first piston (105) from the actuator (85) while continued operation of the actuator (85) provides a second portion of the outputting of the hydraulic fluid by the second piston (115).