AIR COMPRESSOR

• US 20110206538A1
• Filed: 10/09/2009
• Published: 08/25/2011
• Est. Priority Date: 10/09/2008
• Status: Active Grant

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Matsunaga, Kenichi, Yokota, Tomoyoshi, Kodato, Seiichi
• Granted Patent: US 8,784,070 B2
• Time in Patent Office: Days
• US Class Current: 417/1
• CPC Class Codes: F04B 2203/0209 Rotational speed
• CPC Class Codes: F04B 2205/05 Pressure after the pump outlet
• CPC Class Codes: F04B 41/02 having reservoirs
• CPC Class Codes: F04B 49/00 Control , e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
• CPC Class Codes: F04B 49/022 by means of pressure
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

When an air pressure in a tank part (5) drops from a maximum set pressure value (A1) to or below at least one restart set pressure value defined to lie in a range between the maximum set pressure value and a minimum set pressure value, a control circuit part (2) operates an electric motor (3b) at a predetermined revolving speed. When the air pressure in the tank part (5) drops from the restart set pressure value to or below the minimum set pressure value, the control circuit part (2) operates the electric motor (3b) at the predetermined revolving speed or a revolving speed lower than N2 until the air pressure in the tank part (5) reaches the maximum set pressure value.

Claims

1. An air compressor comprising:

a tank part that stores compressed air to be supplied to a pneumatic tool;

a compressed-air generation part for generating the compressed air and supplying the compressed air to the tank part;

a drive part with a motor for driving the compressed-air generation part;

a pressure sensor for detecting an air pressure inside the tank part; and

a control circuit part for controlling the motor of the drive part based on a detection signal from the pressure sensor,

wherein the control circuit part stops operating the motor when detected pressure indicating the air pressure in the tank part acquired from the detection signal is higher than a maximum set pressure value, operates the motor when the detected pressure is lower than a minimum set pressure value lower than the maximum set pressure value, operates the motor at a first predetermined revolving speed when the detected pressure drops from the maximum set pressure value to or below at least one restart set pressure value defined to lie in a range between the maximum set pressure value and the minimum set pressure value, and operates the motor at the first predetermined revolving speed or at a second predetermined revolving speed higher than the first predetermined revolving speed until the detected pressure reaches the maximum set pressure value when the detected pressure is the same as or below the minimum set pressure value.

2. The air compressor according to claim 1, wherein the restart set pressure value includes a first restart set pressure value and a second restart set pressure value lower than the first restart set pressure value, and

the control circuit part operates the motor at the first predetermined revolving speed when the detected pressure drops from the maximum set pressure value to or below the first restart set pressure value and when a pressure drop rate thereof is greater than a predetermined value, and operates the motor at a third predetermined revolving speed lower than the first predetermined revolving speed when the detected pressure drops from the maximum set pressure value to or below the second restart set pressure value and when a pressure drop rate thereof is smaller than the predetermined value.

3. The air compressor according to claim 1, wherein the control circuit part operates the motor at the first predetermined revolving speed until the detected pressure reaches the maximum set pressure value when the detected pressure is equal to or lower than the minimum set pressure value.