Air compressor

• US 20060110258A1
• Filed: 10/26/2005
• Published: 05/25/2006
• Est. Priority Date: 10/27/2004
• Status: Active Grant

• Current Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Iimura, Yoshio, Orikasa, Hiroaki
• Granted Patent: US 7,476,088 B2
• Time in Patent Office: Days
• US Class Current: 417/18
• CPC Class Codes: F04B 49/08 Regulating by delivery pressure

Abstract

A control circuit portion in an air compressor finds the rate of decrease of pressure inside a tank portion when a motor is at rest relative to the time based on a detection signal from a pressure sensor. Where the rate of decrease of pressure is greater than a given value, the motor is started without waiting for the pressure inside the tank to decrease to a motor restart pressure value, the pressure inside the tank portion rises to a given motor stop pressure value and the motor is then controlled to come to a stop. Where the rate of decrease of pressure is less than the given value, the motor is started when the pressure inside the tank has decreased to the motor restart pressure value. After the start of the motor, the motor is controlled such that it comes to a stop when the pressure inside the tank portion increases to a given value lower than the motor stop pressure value.

Claims

1. An air compressor comprising:

a tank portion for storing compressed air;

a compressed air creation portion for creating the compressed air and supplying it into the tank portion;

a driver portion having a motor for driving the compressed air creation portion;

a control circuit portion for controlling the driver portion; and

a pressure sensor for detecting pressure of the compressed air inside the tank portion;

wherein the control circuit portion controls the driver portion based on a detection signal from the pressure sensor in such a way as to stop the motor when the pressure inside the tank portion has increased to a given motor stop pressure value and start the motor when the pressure inside the tank portion has decreased to a given motor restart pressure value after the motor has stopped; and

wherein in a case where rate of decrease of the pressure is less than a given value, the motor is stopped before the pressure inside the tank portion reaches the motor stop pressure value.

2. An air compressor as set forth in claim 1, wherein in a case where the rate of decrease of the pressure is greater than the given value, the motor is started without waiting for the pressure inside the tank portion to decrease to the motor restart pressure value.

3. An air compressor as set forth in claim 2,

wherein the rate of decrease of the pressure is given by a first rate of decrease of pressure (Δ

P1/Δ

T1) inside the tank portion within a first time (Δ

T1) and by a second rate of decrease of pressure (Δ

P2/Δ

T2) inside the tank portion within a second time (Δ

T2) longer than the first time,

wherein the first rate of decrease of pressure is compared with a first given value or the second rate of decrease of pressure is compared with a second given value,

wherein in a case where any one of the first and second rates of decrease of pressure is greater than the first or second given value, the motor is started without waiting for the pressure inside the tank portion to decrease to the motor restart pressure value, and

wherein the motor is stopped when the pressure inside the tank portion has increased to the motor stop pressure value after the start of the motor.

4. An air compressor as set forth in claim 3, wherein the first given value is a rate of decrease of pressure having a value greater than the second given value.