Hybrid Construction Machine Power Distribution Control

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Solution Overview

Problem

Existing hybrid construction machine control systems face efficiency decreases when the total power required exceeds the output power of the driving source, particularly due to the prioritization of the electrically driven actuator over the hydraulic actuator, leading to reduced operating speed and efficiency.

Innovation Solution

A control system that detects the output power and required power of both actuators, restricting the torque or acceleration of the rotation motor and preferentially distributing power to the hydraulic actuator when the required power exceeds the output power, ensuring a greater proportion of power is allocated to the hydraulic actuator, even if it means limiting the rotation motor's power based on lever manipulation signals and using stored electricity to supplement power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the output power is divided between the hydraulic actuator and the rotation motor in accordance with the amounts of manipulation of the levers, then the power distribution follows the operator's input, but the speed of the highly loaded hydraulic actuator significantly decreases, resulting in decrease of operating efficiency

Engineering Contradiction:
Improvepower distribution according to manipulation amountVSAvoidoperating efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The control system dynamically changes the power distribution parameters based on real-time detection of required power and output power. When the required power exceeds the output power, the system automatically adjusts the distribution ratio to prioritize the hydraulic actuator, deviating from the standard proportional distribution based on lever manipulation amounts.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The power distribution system transitions from a static proportional distribution (based on fixed lever manipulation ratios) to a dynamic distribution mechanism that adapts in real-time. The control device continuously monitors power requirements and adjusts the distribution strategy, enabling the system to switch between proportional distribution and preferential distribution modes.

Inventive Principle:
Principle #15Dynamics

2Productivity

If the torque or acceleration of the rotation motor is restricted to distribute power preferentially to the hydraulic actuator, then the operating speed of the hydraulic actuator is maintained, but the rotation motor's performance is limited

Engineering Contradiction:
Improveoperating speed of hydraulic actuatorVSAvoidrotation motor power
Core Design Contradiction:
ProductivityVSPower

Solution Approach 1:

The control system applies preliminary anti-action by preemptively restricting the rotation motor's torque or acceleration when power shortage is detected. This prevents the rotation motor from consuming excessive power that would otherwise be unavailable to the hydraulic actuator, thereby maintaining the hydraulic actuator's operating speed during power-deficient conditions.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The system applies partial action to the rotation motor by providing only the portion of power that does not compromise the hydraulic actuator's performance. Instead of fully satisfying the rotation motor's power demand, the system deliberately provides a limited amount of power, accepting partial performance of the rotation motor to ensure adequate power supply to the hydraulic actuator.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP2540917B1Control device for hybrid construction machine
Publication Date: 2023.04.12 NABTESCO CORP
  • EP2540917B1 patent drawingFigure 1
  • EP2540917B1 patent drawingFigure 2

AI summary

[Object] When total power required by a hybrid construction machine increases above output power available from a driving source, power supplied to a rotation motor is restricted, [Means to Realize Object] Driving power from an engine 2 is distributed to a hydraulic pump 6 and a generator 4. Electric power generated by the generator 4 is used to drive a rotation motor 12, and pressurized oil provided by the hydraulic pump 6 is used to drive a hydraulic machine 14. When both of the hydraulic machine 14 and the rotation motor 12 are simultaneously manipulated, the output power outputted by the engine 2 and the required power required by the hydraulic machine 14 and the rotation motor 12 are detected. When the required power exceeds the output power, the torque or acceleration of the rotation motor 12 is restricted to preferentially provide output power to the hydraulic machine 14.