Air compressor and method for controlling the same

• US 7,704,052 B2
• Filed: 02/19/2004
• Issued: 04/27/2010
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Iimura, Yoshio, Sunaoshi, Mitsuhiro, Segawa, Kazuhiro, Uchida, Toshiaki, Orikasa, Hiroaki
• Primary Examiner(s): Kramer; Devon C
• Assistant Examiner(s): Hamo; Patrick
• Application Number:
  US10/780,876
• Publication Number:
  US 20040191073A1
• Time in Patent Office: 2,259 Days
• Field of Search: 417/44.2, 700/25, 700/30, 700/31
• US Class Current: 417/44.2
• CPC Class Codes: F04B 2203/0209 Rotational speed
• CPC Class Codes: F04B 41/02 having reservoirs
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

An air compressor includes: a tank portion for reserving compressed air used in a pneumatic tool; a compressed air generation portion for generating compressed air and supplying the compressed air to the tank portion; a drive portion including a motor for driving the compressed air generation portion; a control circuit portion for controlling the drive portion; and a pressure sensor for detecting pressure of the compressed air reserved in the tank portion. The control circuit portion includes a unit for controlling the rotational speed of the motor multistageously on the basis of a detection signal output from the pressure sensor.

Claims

1. A method of controlling an air compressor, said air compressor including a tank portion for reserving compressed air used in a pneumatic tool, a compressed air generation portion for generating compressed air and supplying said compressed air to said tank portion, a drive portion including a motor for driving said compressed air generation portion, and a control circuit portion for controlling said drive portion, the method comprising:

detecting pressure P of said compressed air reserved in said tank portion;

storing a plurality of values indicating different rotational speeds of the motor;

calculating a rate Δ

P/Δ

T between pressure change Δ

P and time Δ

T;

selecting one of the values based on the pressure P of said tank portion and the rate Δ

P/Δ

T of pressure change; and

controlling the rotational speed of said motor in accordance with the selected value.

2. The method according to claim 1, wherein the plurality of values comprise integral times of a predetermined rotational speed.

3. The method according to claim 1, wherein said controlling comprises:

judging whether the pressure P in the tank is higher than a predetermined value; and

controlling the motor to stop when the pressure P is higher than the predetermined value.

4. The method according to claim 1, wherein said calculating includes calculating a first rate Δ

P1/Δ

T1 of pressure change Δ

P1 to a relatively short time Δ

T1 and a second rate Δ

P2/Δ

T2 of pressure change Δ

P2 to a time Δ

T2 longer than the time Δ

T1, and

wherein said selecting includes selecting one of the rotational speeds based on the first and second rates of pressure change.

5. The method according to claim 1, further comprising:

storing a plurality of patterns indicating relations among the pressure P of said tank portion, the rate Δ

P/Δ

T of pressure change, and the rotational speeds of said motor; and

selecting one of the patterns based on a currently operating motor speed.

6. A method of controlling an air compressor, said air compressor including a tank portion for reserving compressed air used in a pneumatic tool, a compressed air generation portion for generating compressed air and supplying said compressed air to said tank portion, a drive portion including a motor for driving said compressed air generation portion, and a control circuit portion for controlling said drive portion, the method comprising:

detecting pressure P of said compressed air reserved in said tank portion;

calculating a rate Δ

P/Δ

T between pressure change Δ

P and time Δ

T;

storing a plurality of tables each indicating relations among the pressure P, the rate Δ

P/Δ

T and different rotational speeds of the motor;

selecting one of the plurality of tables based on a currently operating motor speed; and

searching for the rotational speed of the motor by referring to the selected table.