Ring Gear Driven Pump Pinion for Compact Transmission

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Solution Overview

Problem

Existing motor vehicle transmissions, particularly those for electric vehicles, face challenges of increased weight and manufacturing costs due to the need for additional gears to mechanically drive the oil pump.

Innovation Solution

A transmission design that eliminates the need for additional gears by directly meshing the pump pinion with the ring gear, using the existing ring gear to drive the pump pinion, thereby reducing weight and manufacturing costs, and incorporating a bevel or hypoid gear configuration to enhance efficiency and space-saving features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If additional gears are used to mechanically drive the oil pump, then the oil pump can be driven, but the weight and manufacturing costs increase

Engineering Contradiction:
Improvemanufacturing costsVSAvoidnumber of gears
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The ring gear is designed to serve dual functions: transmitting power in the transmission system and simultaneously driving the oil pump through an integrated pump pinion. This multi-functionality eliminates the need for separate drive gears, reducing both weight and manufacturing costs while maintaining reliable oil pump operation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pump drive mechanism is merged with the ring gear structure by integrating the pump pinion directly onto the ring gear. This combination consolidates multiple components into a single integrated unit, reducing the overall number of parts and simplifying the transmission system architecture.

Inventive Principle:
Principle #5Merging (Combining)

2Weight of moving object

If additional gears are used to mechanically drive the oil pump, then the oil pump can be driven, but the weight increases

Engineering Contradiction:
Improvetransmission weightVSAvoidnumber of gears
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The ring gear serves dual purposes as both a power transmission element and a drive mechanism for the oil pump. By making the ring gear multi-functional, the patent eliminates redundant components that would add weight, achieving weight reduction without compromising the oil pump's drive capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the pump drive function from the main transmission path and integrates it directly into the ring gear structure. This extraction and integration approach removes the need for separate intermediate gears and their associated mounting structures, thereby reducing overall transmission weight.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If the pump pinion meshes directly with the ring gear, then weight and costs are reduced, but the engagement areas must be carefully positioned

Engineering Contradiction:
Improvenumber of gearsVSAvoidengagement area positioning
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The ring gear is designed with differentiated local characteristics: specific engagement areas are provided at defined positions (e.g., opposite ends or specific angular intervals) to mesh with either the pinion or pump pinion. This local quality approach allows precise positioning of engagement areas while maintaining overall manufacturing feasibility through standardized gear cutting processes.

Inventive Principle:
Principle #3Local quality

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 weight, manufacturing costs, and friction losses, while improving efficiency, especially at start-up and low speeds, and allows for a more compact and adaptable transmission.

Implementation Method 1

The pump includes a pump pinion which, in addition to the pinion, meshes directly with the ring gear in a second engagement area

Methodology Applied
Scientific EffectGear meshing: Gear

Implementation Method 2

If the pinion is designed as a bevel pinion and/or the pump pinion is designed as a pump bevel pinion. In this regard, it is also advantageous if the ring gear is designed as a bevel ring gear

Methodology Applied
Scientific EffectBevel gear: Gear

Implementation Method 3

According to the invention, the pump pinion forms hypoid gearing together with the ring gear. In addition, it is provided that the pinion forms a hypoid toothing together with the ring gear

Methodology Applied
Scientific EffectHypoid gearing: Gear

Data Source

PatentEP3452741B1Transmission comprising a pump mechanically driven on a ring gear of the transmission
Publication Date: 2020.08.26 ZF FRIEDRICHSHAFEN AG
  • EP3452741B1 patent drawingFigure 1
  • EP3452741B1 patent drawingFigure 2

AI summary

Disclosed is a transmission (1) for a motor vehicle, in particular for an electrically driven rail vehicle, comprising a ring gear (2), a pinion (3) that meshes with the ring gear (2) in a first engagement zone (4), and a mechanically driven pump (9). According to the invention, the pump (9) includes a pump pinion (10) which, in addition to the pinion (3), directly meshes with the ring gear (2) in a second engagement zone (11).