Excavator Hydraulic Pump Control for Efficient Leveling

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Solution Overview

Problem

In two-pump type hydraulic drive systems of construction machines like hydraulic excavators, the energy efficiency deteriorates during leveling operations due to excessive delivery pressure of the hydraulic pump supplying fluid to the boom cylinder, especially when arm crowding and boom raising operations are performed simultaneously.

Innovation Solution

A construction machine with variable displacement hydraulic pumps and regulators, controlled by a controller that adjusts displacement volumes based on operation amounts and delivery pressure, ensuring the displacement volume of the first hydraulic pump decreases with reduced boom raising operation, preventing excessive delivery pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the displacement volume of the first hydraulic pump is controlled according to the maximum value among target displacement volumes based on boom raising operation amount and arm crowding operation amount, then the arm crowding operation speed is maintained, but the delivery pressure of the first hydraulic pump rises excessively and energy efficiency deteriorates

Engineering Contradiction:

Improvearm crowding operation speedVSAvoidenergy efficiency of hydraulic pump

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The control method dynamically switches between two control strategies based on real-time detection of boom raising operation amount. When boom raising operation amount exceeds a predetermined threshold, the system uses only the target displacement volume based on boom raising operation. When the threshold is not exceeded, the system uses the maximum value between target displacement volumes based on boom raising and arm crowding operations. This dynamic adaptation resolves the contradiction by adjusting control parameters according to actual operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the control parameter (displacement volume control strategy) based on the boom raising operation amount parameter. By detecting whether the boom raising operation amount exceeds a predetermined threshold, the system switches between different displacement volume control modes, thereby adjusting the delivery pressure and energy consumption characteristics to match actual operational needs.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the displacement volume of the first hydraulic pump is increased to maintain arm crowding operation speed, then the arm crowding operation is performed efficiently, but the delivery pressure rises excessively causing energy waste

Engineering Contradiction:

Improvearm crowding operation efficiencyVSAvoidhydraulic pump energy loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The control system dynamically adjusts the displacement volume control strategy based on real-time boom raising operation amount. When the boom raising operation amount exceeds the predetermined threshold, the system adopts a more energy-efficient control mode that prevents excessive pressure buildup, while still maintaining adequate arm crowding operation speed through the second hydraulic pump.

Inventive Principle:

Principle #15Dynamics

3Speed

If the displacement volume of the first hydraulic pump is controlled based on maximum target displacement volume, then the boom raising operation speed is maintained, but the delivery pressure becomes excessively large during leveling operation

Engineering Contradiction:

Improveboom raising operation speedVSAvoiddelivery pressure of hydraulic pump

Core Design Contradiction:

SpeedVSStress or pressure

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3608548B1Construction machine

Publication Date: 2023.10.25 HITACHI CONSTRUCTION MACHINERY CO LTD

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AI summary

To provide a construction machine that can improve the energy efficiency in a leveling operation in which an arm crowding operation and a boom raising operation are performed simultaneously. A controller (30) controls a first regulator (60a) according to the maximum value among target displacement volume (Qa1) of a first hydraulic pump (1) that is based on a boom raising operation amount (Pi1), and target displacement volume (Qa2) of the first hydraulic pump (1) that is based on an arm crowding operation amount (Pi2) of an arm operation device (18) if the boom raising operation amount (Pi1) of a boom operation device (17) is smaller than a predetermined operation amount, or if a delivery pressure (P2) of a second hydraulic pump (2) is equal to or higher than a predetermined pressure, and controls the first regulator (60a) according only to the target displacement volume (Qa1) of the first hydraulic pump (1) that is based on the boom raising operation amount (Pi1) if the boom raising operation amount (Pi1) is equal to or larger than the predetermined operation amount, and the delivery pressure (P2) of the second hydraulic pump (2) is lower than the predetermined pressure.