Heated Lubricant Pump Layout for Low-Temperature Viscosity Control

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Solution Overview

Problem

Lubricant pumps face challenges in efficiently delivering lubricant at low temperatures due to increased viscosity, requiring higher power consumption to overcome the resistance.

Innovation Solution

A lubricant pump design with localized heating elements near the pump elements, controlled by a thermal switch, reduces viscosity by heating only the immediate lubricant needed for pumping, using self-regulating heaters like PTC thermistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the pump operates in a cold environment, then the lubricant becomes highly viscous and difficult to pump, but heating the lubricant creates a risk of overheating and degradation

Engineering Contradiction:
Improvelubricant temperatureVSAvoidlubricant degradation
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The system dynamically changes the temperature parameter of the lubricant using a heating element controlled by a thermal switch. The thermal switch monitors temperature and activates/deactivates the heater to maintain optimal viscosity without overheating, thus changing the temperature parameter within a safe range to improve pumpability while preventing degradation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The thermal switch provides feedback control by continuously monitoring the lubricant temperature and automatically controlling the heating element. When the lubricant reaches a predetermined temperature, the thermal switch deactivates the heater; when temperature drops, it reactivates heating. This feedback mechanism ensures reliable temperature control without overheating.

Inventive Principle:
Principle #23Feedback

2Reliability

If thermal protection devices are added to prevent overheating, then lubricant degradation is reduced, but the device complexity increases

Engineering Contradiction:
Improvelubricant degradation protectionVSAvoidpump structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The thermal switch is self-regulating and automatically controls the heating element without external intervention. It monitors the lubricant temperature directly and switches the heater on/off based on thermal conditions, making the system self-protecting against overheating while minimizing additional complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The thermal switch is integrated into the pump housing structure, merging the thermal protection function with the existing pump components. The heating element is positioned within the pump housing, and the thermal switch is mounted on the housing, combining multiple functions (heating, temperature monitoring, and control) into a compact integrated system.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the pump draws lubricant from the sump, then the lubricant picks up debris and contaminants, but not drawing from the sump reduces lubricant circulation

Engineering Contradiction:
Improvelubricant cleanlinessVSAvoidlubricant circulation
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The pump inlet is positioned at a different vertical level (higher in the sump) compared to conventional pumps. By drawing lubricant from a higher level in the sump rather than the bottom, the pump avoids picking up settled debris and contaminants while still maintaining effective lubricant circulation. This dimensional change in inlet positioning resolves the contradiction between cleanliness and circulation.

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

Ensures efficient lubricant flow and reduced power consumption by heating only the necessary lubricant volume, maintaining effective operation even at very low temperatures.

Implementation Method 1

a first heating element disposed in the wet portion to be exposed to lubricant, the first heating element disposed between the first pump element and the upper wall

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a thermal switch disposed in the pump base and in a dry portion of the lubricant pump, the thermal switch electrically connected to the first heating element and configured to control activation and deactivation of the first heating element

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4375558B1Heated lubricant pump
Publication Date: 2026.04.29 GRACO MINNESTOA INC
  • EP4375558B1 patent drawingFigure 1
  • EP4375558B1 patent drawingFigure 2A
  • EP4375558B1 patent drawingFigure 2B

AI summary

A lubricant pump comprising a pump base having an upper wall, a reservoir housing mounted on the pump base, the reservoir housing and the upper wall defining a wet portion of the lubricant pump, a first pump element at least partially disposed in the wet portion, a first heating element disposed in the wet portion to be exposed to lubricant, the first heating element disposed between the first pump element and the upper wall, and a thermal switch disposed in the pump base and in a dry portion of the lubricant pump, the thermal switch electrically connected to the first heating element and configured to control activation and deactivation of the first heating element, a plug mounted to the upper wall and fluidly separating the wet portion within which the lubricant is disposed and the dry portion, and a power line extending between the thermal switch and the first heating element, the power line extending through a wire bore in the plug..