Hydraulic Gear Pump CVT With Inverse Volume Adjustment

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Solution Overview

Problem

Existing continuously variable transmission systems, such as push belt transmissions, are prone to slipping, especially in heavy load applications, limiting their use to light applications due to inefficiencies in power transmission and limited transmission ratio options.

Innovation Solution

A continuously variable transmission system comprising two gear pumps with interconnected adjustment members that adjust their pump volumes in inverse correlation, utilizing a closed hydraulic circuit to enhance power transmission efficiency and prevent slipping, allowing for effective use in both light and heavy load applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If push belts are used for continuously variable transmission, then the structure is simple and effective, but slipping occurs especially in heavy load applications

Engineering Contradiction:
Improvetransmission structureVSAvoidpower transmission stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces the mechanical friction-based push belt system with a hydraulic fluid transmission system. The hydraulic system uses fluid pressure and volume displacement through gear pumps to transmit power, eliminating the slipping problem inherent in friction-based mechanical systems while maintaining continuous variable transmission capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention employs hydraulic principles by using fluid as the transmission medium between two gear pumps. The hydraulic circuit transfers power through fluid displacement, where the first gear pump acts as a motor and the second as a pump, providing reliable power transmission without slipping even under heavy loads.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Adaptability or versatility

If push belt transmissions are used, then light applications are covered, but heavy load applications cannot be handled effectively

Engineering Contradiction:
Improveapplication rangeVSAvoidpower transmission capacity
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

The patent changes the fundamental transmission parameter from mechanical friction force to hydraulic pressure and volume displacement. This allows the system to handle a wide range of power levels by adjusting pump volumes and fluid pressure, enabling effective transmission from light to heavy load applications without the power limitations of push belt systems.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If fixed gear ratios are used, then the transmission ratio choice is limited, but the structure remains simple

Engineering Contradiction:
Improvetransmission mechanismVSAvoidtransmission ratio options
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention implements dynamic adjustment of transmission ratios by varying the pump volumes of the gear pumps. Unlike fixed gear systems, the hydraulic system allows continuous variation of the transmission ratio by changing the displacement volume, providing adaptability while maintaining a relatively simple mechanical structure based on two gear pumps.

Inventive Principle:
Principle #15Dynamics

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 system effectively adjusts transmission ratios and optimizes engine operation by maintaining constant volumetric flow, reducing slipping, and enabling efficient power transmission across a wide range of loads, from light to heavy applications.

Implementation Method 1

By using a fluid as the medium to transmit power in a substantially closed hydraulic circuit, slipping can be reduced, prevented or even eliminated

Methodology Applied
Scientific EffectHydraulic principle: Hydraulic Press

Implementation Method 2

each gear pump further comprises an adjustment member for adjusting the pump volume of the respective gear pump

Methodology Applied
Scientific EffectGeometric adjustment: Geometry

Data Source

PatentEP3592976B1Continuously variable transmission and transmission system
Publication Date: 2021.04.14 HCVTRANSMISSION BV
  • EP3592976B1 patent drawingFigure 1
  • EP3592976B1 patent drawingFigure 2
  • EP3592976B1 patent drawingFigure 3

AI summary

The invention relates to a continuously variable transmission and a transmission system comprising said continuously variable transmission, wherein the continuously variable transmission comprises a first gear pump and a second gear pump, wherein each gear pump comprises a first gear and a second gear meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis, wherein each gear pump further comprises an adjustment member for adjusting the pump volume, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other.