Hybrid Construction Machine Battery Heating and Speed Control

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Solution Overview

Problem

Conventional hybrid construction machines face issues with electric storage device performance at low temperatures, leading to excessive assist power generation that can increase hydraulic pump and engine rotational speeds beyond safe limits, potentially causing faults or engine damage.

Innovation Solution

A hybrid construction machine design that includes a generator-motor, electric storage device, power control device, unload valve, and relief valve, which adjusts electric power supply and hydraulic pump discharge pressure to manage excessive assist power and promote self-heating of the electric storage device, thereby preventing excessive speed increases in the hydraulic pump and engine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the generator-motor operates to charge and discharge the electric storage device for warming, then the electric storage device temperature increases, but the assist power becomes excessive and may cause faults in the hydraulic pump or engine

Engineering Contradiction:

Improveelectric storage device temperatureVSAvoidhydraulic pump and engine reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The unload valve acts as an intermediary between the hydraulic pump and the hydraulic motor. By controlling the opening degree of the unload valve, excess hydraulic flow is diverted to the tank, preventing excessive assist power from reaching the hydraulic motor and causing faults, while still allowing sufficient power transmission for normal operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control device dynamically changes the opening degree parameter of the unload valve based on the operating state. When the electric storage device temperature is low and warming is needed, the unload valve opening is adjusted to limit assist power; when temperature is normal, the opening is adjusted to allow full assist power transmission

Inventive Principle:

Principle #35Parameter changes

2Power

If the generator-motor operates as an electric motor for assist power, then the engine gets assistance, but the rotational speed of the hydraulic pump and generator-motor may exceed permitted speed

Engineering Contradiction:

Improveassist powerVSAvoidhydraulic pump and generator-motor rotational speed

Core Design Contradiction:

PowerVSSpeed

Solution Approach 1:

The unload valve serves as a speed control intermediary by diverting excess hydraulic flow. When assist power causes the hydraulic pump and generator-motor to rotate at excessive speeds, the unload valve opens to redirect surplus flow to the tank, thereby limiting the maximum rotational speed to safe operating levels

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex mechanical speed limiting mechanisms with a hydraulic control system using the unload valve. This substitution allows for smoother, more responsive speed control and eliminates the need for mechanical governors or centrifugal governors on the hydraulic pump and generator-motor

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This solution effectively warms up the electric storage device while restraining excessive assist power, preventing engine and hydraulic pump faults and ensuring safe operation by controlling the load on these components.

Implementation Method 1

operating the generator-motor to charge and discharge the electric storage device when the temperature of the electric storage device is lower than a predetermined temperature, thereby causing the electric storage device to generate heat

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a relief valve provided between the discharge port of the hydraulic pump and having a set pressure which is predetermined. The relief valve controls the discharge pressure of the hydraulic pump to adjust the discharge pressure to the set pressure, under the abnormal circumstances

Methodology Applied

Scientific EffectPressure control:

Implementation Method 3

an unload valve provided between a discharge port of the hydraulic pump and a tank; an unload-valve control device which controls opening and closing of the unload valve

Methodology Applied

Scientific EffectHydraulic flow control:

Data Source

PatentUS8880265B2Hybrid construction machine

Publication Date: 2014.11.04 KOBELCO CONSTR MASCH CO LTD

AI summary

Disclosed is a hybrid construction machine including: an engine, a generator-motor, a hydraulic pump, an electric storage device, a power control device which controls electric power between the generator-motor and the electric storage device, a temperature detector which determines a temperature of the electric storage device, an unload valve provided between a discharge port of the hydraulic pump and a tank, an unload-valve control device, and a relief valve. The power control device controls an electric power to be supplied from the electric storage device to the generator-motor, under abnormal circumstances where the temperature of the electric storage device is low, to a power obtained by adding an additional discharge power to a power to be supplied under normal circumstances. The unload-valve control device closes the unload valve, under abnormal circumstances. The relief valve controls the discharge pressure of the hydraulic pump to the set pressure, under abnormal circumstances.