Electric Oil Pump Failure Control for Hybrid Vehicle Creep Driving
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Solution Overview
Problem
Hybrid vehicles lack a mechanism to ensure continued operation and safety when an Oil Pump Unit (OPU) fails, as existing systems rely on Mechanical Oil Pumps that decrease fuel efficiency and lack direct monitoring and control capabilities for hydraulic pressure formation.
Innovation Solution
A method for controlling a vehicle in the event of an OPU failure, involving comparisons of actual Electric Oil Pump (EOP) RPM with set values to enable creep driving using the motor, restricting torque transmission, and charging the motor to prevent battery discharge, ensuring the vehicle can travel safely and efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an Electric Oil Pump (EOP) is exclusively applied to form hydraulic pressure, then fuel efficiency is improved, but there is no extra device capable of forming hydraulic pressure when the EOP fails
Solution Approach 1:
The patent applies beforehand cushioning by establishing a monitoring system that detects EOP performance degradation before complete failure occurs. The controller continuously monitors actual RPM versus target RPM, and when deviation exceeds a threshold, it proactively initiates creep driving mode to prevent transmission shutdown, thus cushioning against the potential failure consequence.
Solution Approach 2:
The patent uses an intermediary approach by introducing a control system that mediates between the EOP status and vehicle operation. When EOP performance degrades, the controller acts as an intermediary to switch the vehicle to creep driving mode, allowing continued limited operation rather than complete shutdown, thus maintaining some hydraulic pressure formation capability through alternative means.
2Reliability
If functions for measuring OPU performance and controlling vehicle are added, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by making the existing controller perform multiple functions: it not only controls the EOP operation but also monitors EOP performance by comparing actual RPM with target RPM, detects failures, and initiates creep driving mode. This multi-functionality adds reliability without requiring separate dedicated monitoring and control devices.
Solution Approach 2:
The controller performs self-service by using its own computational resources to monitor EOP performance and make control decisions. The system leverages existing sensors and processing capabilities to detect failures and initiate protective measures, rather than requiring external monitoring equipment or additional control units.
3Reliability
If creep driving is enabled using motor when OPU failure is detected, then driving safety is improved, but battery discharge increases
Solution Approach 1:
The patent applies partial action by enabling creep driving mode which provides limited but sufficient motion capability for safety purposes. Instead of full driving performance, the system provides just enough motor torque to move the vehicle at low speeds, balancing safety requirements with energy conservation. The creep driving mode operates at reduced power levels compared to normal driving.
Data Source
AI summary
A method for controlling a vehicle in the event of an oil-pump failure may include: a first comparison step of comparing, by a controller, an actual RPM of an EOP with a first set value set in advance based on a target RPM of the EOP; a maximum EOP driving step of driving the EOP to a maximum output by the controller when a result of the comparison in the first comparison step shows that the actual RPM is smaller than or equal to the first set value; a second comparison step of comparing the actual RPM of the EOP with a second set value by the controller after the maximum EOP driving step; and a creep driving step of making the vehicle perform creep driving using a motor by the controller when a result of the comparison in the second comparison step shows that the actual RPM is larger than the second set value.