Battery Pack Drain Hole with Raised Outer Edge

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Solution Overview

Problem

Existing battery packs face challenges in efficiently draining water from the housing case without allowing dust or foreign materials to enter, and in preventing electrical connections between terminal members when they become soaked, which can lead to short circuits.

Innovation Solution

A battery pack design with a drainage function-shape portion at the bottom of the housing case, featuring a drain hole with an outer end edge that rises inward, positioned between terminal members, and optionally including flow guide devices and draw guide devices to direct water to the drain hole, while also using foreign material-introduction restricting ribs to prevent contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple drain holes are provided at the bottom portion of the housing case to improve drainage effect, then water discharge efficiency is improved, but water or dust may easily enter into the housing case from the drain holes

Engineering Contradiction:
Improvewater discharge efficiencyVSAvoidwater and dust entry
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The drain hole is given a specific shape where the outer end edge rises toward the inside of the housing case, creating a localized structural feature that prevents water and dust entry while maintaining drainage function. This local quality change allows the single drain hole to achieve both efficient drainage and protection against contamination.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Instead of preventing water entry through multiple holes or complex sealing mechanisms, the invention inverts the approach by allowing drainage while using the raised outer end edge geometry to naturally prevent water and dust from entering through the drain hole, thus solving the contradiction through geometric inversion.

Inventive Principle:
Principle #13The other way round (Inversion)

2Object-affected harmful factors

If the number of drain holes is reduced to prevent water and dust entry, then protection against contamination is improved, but water discharge efficiency deteriorates

Engineering Contradiction:
Improvewater and dust entry preventionVSAvoidwater discharge efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The drain hole's outer end edge is shaped with a rise toward the inside of the housing case, creating a localized barrier that prevents water and dust entry. This local structural feature enables a single drain hole to maintain both protection function and adequate drainage efficiency without requiring multiple holes.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameters of the drain hole by forming an outer end edge that rises toward the inside of the housing case. This parameter change optimizes the drain hole's dual function of draining water efficiently while preventing water and dust entry, eliminating the need for multiple holes.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If drain holes are positioned at the bottom portion of the housing case for effective drainage, then water discharge capability is improved, but the drain holes may be closed by the placement surface when the battery pack is placed on a desk or ground

Engineering Contradiction:
Improvewater discharge capabilityVSAvoiddrain hole accessibility
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

Instead of positioning the drain hole flat at the bottom surface where it can be blocked, the invention inverts the approach by forming an outer end edge that rises toward the inside of the housing case. This geometric inversion ensures the drain hole remains accessible and functional even when the battery pack is placed on surfaces.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The drain hole is given a three-dimensional structure with the outer end edge rising toward the inside of the housing case, adding a vertical dimension to the drainage pathway. This dimensional change prevents the drain hole from being closed by placement surfaces while maintaining effective water discharge capability.

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

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 efficiently drains water from the battery pack, minimizes the number of drain holes required, prevents short circuits by removing water between terminal members, and maintains a clean internal environment by restricting foreign material entry.

Implementation Method 1

it is possible to easily guide the water, which is present in the housing case, to the outside of the housing case by utilizing the surface tension of the water introduced into the clearance

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP3273502B1Battery pack with water drain holes
Publication Date: 2018.12.12 MAKITA CORP
  • EP3273502B1 patent drawingFigure 1
  • EP3273502B1 patent drawingFigure 2
  • EP3273502B1 patent drawingFigure 3

AI summary

A battery pack comprises a housing having a bottom portion (211) with water drain holes (25). An opening end edge of the drain hole (25), which is disposed at the outer portion of the housing case (20), is set as an outer end edge (261); an opening end edge of the drain hole (25), which is disposed at the inner portion of the housing case (20), is set as an inner end edge (262). The shape of the outer end edge (261) of the drain hole (251) is set so that the outer end edge (261) slightly rises toward the inside of the housing case (20) as compared with a support lower surface (201) of the housing case (20) that corresponds to the peripheral portion of the outer end edge (261). For this reason, a clearance C is formed between the outer end edge 261 and the placement surface F with which the support lower surface 201 of the housing case 20 corresponding to the peripheral portion of the outer end edge 261 comes into contact. Accordingly, even when the battery pack (10) mounted on the tool body (not shown) is placed on a desk or the ground such that the support lower surface (201), which is the bottom portion of the battery pack (10), comes into contact with the placement surface F, the outer end edge (261) of the drain hole (25) is positioned above the placement surface F by the clearance C.Therefore, it is possible to prevent the drain hole (25) from being closed by the placement surface F, and hence it is possible to discharge the water.