Hydraulic Pump Oil Supply Detection Without Level Sensors
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Solution Overview
Problem
Hydraulic systems in motor vehicles face challenges in ensuring a sufficient oil supply to assemblies without relying on oil level or pressure sensors, particularly due to leaks, production defects, or foreign particles, which can lead to system pressure loss and dry-running of the hydraulic pump, compromising cooling and lubrication.
Innovation Solution
A method and control unit that determine the sufficiency of the oil supply based on the temperature of the hydraulic oil, actual electric current, and rotation speed of the hydraulic pump, allowing for monitoring without the need for oil level or pressure sensors, by using temperature and current/rotation speed data to assess oil delivery adequacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil level sensors or pressure sensors are used to monitor oil supply, then the reliability of detecting oil supply sufficiency is improved, but the device complexity and cost increase
Solution Approach 1:
The hydraulic pump serves itself as a measurement device by monitoring its own operating parameters (electric current, rotation speed, temperature) to detect oil supply sufficiency. The control unit evaluates these self-generated signals to determine whether sufficient oil is being supplied, eliminating the need for separate sensing devices.
Solution Approach 2:
The patent replaces mechanical sensing devices (oil level sensors, pressure sensors) with an evaluation method based on electrical and operational parameters. By substituting physical sensors with an analytical approach using existing motor and pump data, the system achieves reliable detection without additional hardware complexity.
2Measurement precision
If additional sensors are installed to monitor oil supply, then the measurement precision is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The existing motor and pump components serve multiple functions: they not only perform the hydraulic pumping function but also act as measurement devices. The electric current and rotation speed data, originally used for motor control, are additionally utilized to monitor oil supply conditions, achieving multi-functionality without additional components.
Solution Approach 2:
The motor-pump system monitors its own operational state through its inherent parameters. The system uses its own electric current consumption and rotation speed characteristics to self-diagnose oil supply conditions, eliminating the need for external measurement devices and simplifying manufacturing.
3Difficulty of detecting and measuring
If traditional dry-running detection methods are used, then the detection capability is improved, but the reliability in detecting actual oil supply issues is worsened due to false positives from sealing plugs or production defects
Solution Approach 1:
The patent changes the detection parameters from binary dry-running detection to continuous evaluation of multiple parameters (temperature, electric current, rotation speed). By analyzing the relationships and trends among these parameters rather than relying on a single threshold, the system can distinguish between actual oil supply deficiencies and conditions caused by sealing plugs or production defects.
Solution Approach 2:
The control unit continuously evaluates the motor and pump parameters and uses this feedback to determine oil supply sufficiency. The system monitors the interrelationships between temperature, current, and rotation speed over time, allowing it to distinguish between genuine oil supply problems and anomalies caused by production defects or sealing plugs.
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
Enables reliable monitoring of oil supply adequacy, preventing system failures and ensuring adequate cooling and lubrication, while eliminating the need for additional sensors, and can be applied to various hydraulic systems beyond motor vehicles.
Implementation Method 1
an actual electric current in the electric motor that powers the hydraulic pump, and/or an actual rotation speed of the hydraulic pump or of the electric motor that powers the pump
Implementation Method 2
a hydraulic pump which draws hydraulic oil from an oil sump and delivers the oil to the assembly that is to be cooled and/or lubricated with hydraulic oil
Implementation Method 3
as a function of the temperature of the hydraulic oil, either the actual electric current in the electric motor that powers the hydraulic pump or the actual rotation speed of the hydraulic pump or that of the electric motor powering the hydraulic pump is better suited for the above determination
Data Source
AI summary
A method for operating a hydraulic system, in particular a hydraulic system of a motor vehicle, which comprises a hydraulic pump (10) powered by an electric motor (11) operated with rotation-speed regulation, the pump for drawing hydraulic oil from an oil sump (6) and supplying it to at least one assembly (8) that is to be cooled and/or lubricated. As a function of a temperature of the hydraulic oil and as a function of an actual electric current in the electric motor (11) powering the hydraulic pump (10) and/or an actual rotation speed of the hydraulic pump (10) or the electric motor (11) powering the pump, it is determined whether a sufficiently large oil supply is ensured for the at least one assembly (8) that is to be cooled and/or lubricated.