Direct-Drive Brushless Power Tool Layout for Compact High Torque

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Solution Overview

Problem

Existing handheld power tools face challenges in achieving a compact design while delivering high torque and efficiency, often requiring conventional gears that occupy valuable installation space and limiting their versatility in handling different types of machining tasks.

Innovation Solution

The system incorporates an electronically commutated electric motor of defined size, directly driving the output shaft without a conventional gear, and a rechargeable battery that can supply energy to multiple tools via flexible interfaces, allowing for wireless or wired energy transfer, and is integrated into a compact housing design that accommodates high-torque motors and efficient energy management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional gears are used to transmit power from the motor to the output shaft, then the motor can be smaller and less expensive, but the overall tool size increases and installation space is consumed

Engineering Contradiction:
Improvemotor powerVSAvoidtool size
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

The patent removes the conventional gear transmission mechanism from the power tool system. The motor is positioned to directly drive the output shaft, extracting the intermediate transmission components (gears, belts, etc.) that previously occupied space. This extraction allows the motor to be larger while keeping the overall tool size compact, as the motor's full power is transmitted directly without needing space for gear trains.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent repositions the motor in a different spatial arrangement within the tool housing, utilizing three-dimensional space more effectively. By changing the motor's orientation and placement relative to the output shaft, the design achieves direct drive without requiring the linear space that conventional gear trains would occupy, thus resolving the volume contradiction.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Power

If conventional gears are used for power transmission, then motor size can be reduced, but efficiency decreases due to mechanical losses and wear

Engineering Contradiction:
Improvemotor powerVSAvoidtransmission efficiency
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent eliminates the gear transmission system that causes mechanical energy losses through friction, tooth engagement, and wear. By directly coupling the motor shaft to the output shaft, the system removes the intermediate transmission stage entirely, achieving near 100% power transmission efficiency and eliminating the energy losses inherent in conventional gear systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical gear transmission system with a direct electromagnetic coupling. Instead of using mechanical gears to transmit power, the motor's electromagnetic field directly drives the output shaft, substituting a complex mechanical transmission system with a simpler, more efficient electromagnetic-direct mechanical connection that minimizes energy loss.

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

3Productivity

If the tool is designed for specific machining tasks, then performance for that task is optimized, but versatility across different tasks is limited

Engineering Contradiction:
Improvetask-specific performanceVSAvoidtask variety
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent designs the power tool with a universal direct-drive architecture that can accommodate multiple types of machining tools and attachments. The motor's high torque output and direct connection to the output shaft provide sufficient power for various tasks (drilling, grinding, cutting, sanding) without requiring task-specific transmission mechanisms, enabling one tool to perform multiple functions effectively.

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

Solution Approach 2:

The patent incorporates electronically commutated motors with electronic speed control that can dynamically adjust operating parameters based on the attached tool and task requirements. This dynamic control system allows the same basic tool platform to optimize performance across different machining tasks by electronically adjusting speed, torque, and power delivery rather than requiring physical reconfiguration.

Inventive Principle:
Principle #15Dynamics

4Volume of moving object

If compact housing design is implemented, then installation space is saved, but accommodating high-torque motors becomes difficult

Engineering Contradiction:
Improvetool sizeVSAvoidmotor torque
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The patent utilizes three-dimensional spatial optimization to position the motor in a compact arrangement that delivers high torque. By changing the motor's orientation and using vertical stacking or radial positioning rather than linear extension, the design accommodates high-torque motors within a compact housing volume, resolving the contradiction between size and torque capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs high-energy-density motor designs that utilize advanced materials and composite construction to maximize torque output relative to motor size. By using high-strength, lightweight materials and optimized magnetic circuits, the motor delivers high torque in a compact form factor that fits within the reduced housing volume without sacrificing force output.

Inventive Principle:
Principle #40Composite materials

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 enables a compact, high-efficiency, and versatile handheld power tool that can operate in various modes (eco and boost) with enhanced power delivery and reduced wear, suitable for diverse applications without the need for additional gear mechanisms.

Implementation Method 1

The energy transfer can be wired or wireless. A wireless energy transmission can take place, for example, via inductive energy transmission.

Methodology Applied
Scientific EffectInductive energy transmission: Electromagnetic Induction

Data Source

PatentEP4230354A1System at least comprising an electronically commutated electric motor of a defined construction size, and a rechargeable battery of at least one voltage class
Publication Date: 2023.08.23 ROBERT BOSCH GMBH
  • EP4230354A1 patent drawingFigure 1
  • EP4230354A1 patent drawingFigure 2
  • EP4230354A1 patent drawingFigure 3

AI summary

The invention relates to a system (10), comprising at least: at least one first hand-held power tool (16a) having at least one first interface for at least one rechargeable battery (14) of a voltage class, with at least one electronically commutated electric motor (12a) of a defined size, with at least one first electronic unit (20a) that is at least designed to energize the electronically commutated electric motor (12a), with at least one first switching element (22a) for activating the electronically commutated electric motor (12a), and at least one second hand-held power tool (16b) having at least one second interface (18b) for the rechargeable battery (14) of the voltage class, with at least one electronically commutated electric motor (12b) of a defined size, with at least one second electronic unit (20b) that is at least designed toto power the electronically commutated electric motor (12b), with at least one second switching element (22b) for activating the electronically commutated electric motor (12b), and with at least one rechargeable battery (14). It is proposed that the rechargeable battery (14) can correspond to both the first interface (18a) and the second interface (18b).