Air Compressor Variable Stop Pressure Control

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Solution Overview

Problem

Air compressors used in nailing machines face difficulties in restarting due to residual pressure in the high-pressure side cylinder when supply voltage decreases, leading to reduced working efficiency and potential start failures, as the drive torque of the motor is insufficient to overcome the load torque caused by the residual pressure.

Innovation Solution

An air compressor with a control unit that detects the stop time and adjusts the operation stop pressure and restart pressure based on the supply voltage, reducing the pressure lowering only when necessary to maintain high storage pressure without compromising the control pressure range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the compressor compresses air to the maximum specified pressure to improve working efficiency, then the compression pressure increases, but the residual pressure in the high pressure side cylinder becomes a load torque that prevents restart when supply voltage is low

Engineering Contradiction:
Improvecompression pressureVSAvoidrestart capability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent applies dynamics by making the operation stop pressure variable rather than fixed. The control unit dynamically adjusts the operation stop pressure based on detected supply voltage levels: at normal voltage, the compressor operates to maximum pressure for high efficiency, while at low voltage, the operation stop pressure is reduced to minimize residual pressure and load torque, enabling successful restart.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the control pressure range is lowered to reduce residual pressure and secure startability, then the restart capability is improved, but the amount of air that can be stored in the storage tank decreases

Engineering Contradiction:
ImprovestartabilityVSAvoidamount of air stored
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The control pressure range is made dynamic based on supply voltage conditions. The control unit adjusts the operation stop pressure according to detected voltage levels, maintaining a high control pressure range (maximum compression pressure) when voltage is normal to maximize air storage capacity, and reducing it only when voltage drops to ensure restart capability.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the operation stop pressure is reduced to minimize residual pressure, then the load torque decreases and restart becomes possible, but the storage pressure in the storage tank is lowered

Engineering Contradiction:
Improverestart capabilityVSAvoidstorage pressure
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The operation stop pressure is dynamically adjusted based on supply voltage detection. When voltage is normal, the operation stop pressure is maintained at maximum levels to ensure high storage pressure. When voltage drops below the threshold, the control unit reduces the operation stop pressure to minimize residual pressure and enable restart, thus optimizing both storage pressure and restart capability under different operating conditions.

Inventive Principle:
Principle #15Dynamics

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 approach enhances working efficiency by maintaining high storage pressure in the tank even at low supply voltage, reducing the likelihood of start failures and improving usability by allowing more efficient air storage and usage.

Implementation Method 1

a motor that rotates a rotary shaft to drive the compressor main body

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a compressor main body that compresses air

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3715633B1Air compressor
Publication Date: 2022.05.11 HITACHI IND EQUIP SYST CO LTD
  • EP3715633B1 patent drawingFigure 1
  • EP3715633B1 patent drawingFigure 2
  • EP3715633B1 patent drawingFigure 3

AI summary

An air compressor includes a compressor main body that compresses air; a storage tank that stores the gas compressed by the compressor main body; a motor that rotates a rotary shaft to drive the compressor main body; and a control unit that controls a drive of the motor. In a case where a value of a voltage to be supplied to the motor is lower than a first voltage value, the control unit detects a stop time of the compressor and changes an operation stop pressure which is a pressure to stop the drive of the motor, based on the stop time.