Air compressor and control method therefor

• US 20040265134A1
• Filed: 06/23/2004
• Published: 12/30/2004
• Est. Priority Date: 06/24/2003
• 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, Sunaoshi, Mitsuhiro, Segawa, Kazuhiro, Orikasa, Hiroaki
• Granted Patent: US 7,641,449 B2
• Time in Patent Office: Days
• US Class Current: 417/38
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04

Abstract

For a motor that drives a compressed air generator, three operating modes which includes a powerful mode for rotating a motor in a high speed range, a silent mode for rotating the motor in a low speed range, and an automatic mode for automatically changing the rotation speed of the motor from the low speed to the high speed in accordance with a setup condition are prepared. A user can designate a desired operating mode by using an operating mode selection switch.

Claims

1. An air compressor comprising:

a tank unit storing an compressed air;

a compressed air generator generating the compressed air to be supplied to the tank unit;

a drive portion including a motor for driving the compressed air generation portion; and

a controller portion controlling the drive portion,

wherein, when motor rotation speed is N0, N1, N2 or N3, where N0=0, and N0<

N1<

N2<

N3, at least two operating modes selected from a group consisting of a silent mode operating the motor at a rotation speed of N0 or N1, a powerful mode operating the motor at a rotation speed of N0, N2 or N3, and an automatic mode operating the motor at a rotation speed of N0, N1, N2 or N3 are enabled.

3. The air compressor according to claim 1, further comprising:

an operating mode selection switch a user employs to designate the modes.

4. The air compressor according to claim 1, further comprising:

a pressure sensor detecting a pressure in the tank unit,

wherein the rotation speed of the motor in a selected mode is changed based on a signal output by the pressure sensor.

6. The air compressor according to claim 4, wherein the pressure sensor detects a pressure P in the tank unit at a predetermined period Δ

T interval to obtain Δ

P/Δ

T, which is the ratio of a pressure change Δ

P to the predetermined period Δ

T, and based on the ratio Δ

P/Δ

T, the rotation speed of the motor is changed.

7. The air compressor according to claim 4, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1, and Δ

P2/Δ

T2, which is the pressure change ratio for the internal pressure of the tank unit during a period Δ

T2 that is longer than Δ

T1 and, based on information for P, Δ

P1/Δ

T1 and Δ

P2/Δ

T2, the rotation speed of the motor in the automatic mode is changed.

9. The air compressor according to claim 4, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1 and based on the information for P and Δ

P1/Δ

T1, the rotation speed of the motor in silent mode is changed.

11. The air compressor according to claim 4, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1 and based on the information for P and Δ

P1/Δ

T1, the rotation speed of the motor in the powerful mode is changed.

13. The air compressor according to claim 7, further comprising at least one of a temperature sensor detecting temperature of the motor, a voltage sensor detecting a power voltage of the drive portion and a current sensor detecting a current load flowing through the drive portion,

wherein the rotation speed of the motor is changed based on information contained in detection signals output by both the sensor and the pressure sensor.

14. The air compressor according to claim 4, wherein the controller portion has a memory storing information which represents a relationship of the pressure P in the tank unit, a pressure change ratio Δ

P2/Δ

T2 and a motor rotation speed N,

wherein the motor rotation speed is determined by searching the memory.

2. An air compressor comprising:

a tank unit storing a compressed air;

a compressed air generator generating the compressed air to be supplied to the tank unit;

a drive portion including a motor for driving the compressed air generation portion;

a controller portion controlling the drive portion,

wherein at least two modes selected from a group consisting of a first mode switching the motor between at least two rotation speeds including 0, a second mode switching the motor between at least three rotation speeds including 0, and a third mode switching the motor between at least four rotation speeds including 0 are enabled.

5. The air compressor according to claim 2, further comprising:

a pressure sensor detecting a pressure in the tank unit,

wherein the rotation speed of the motor in a selected mode is changed based on a signal output by the pressure sensor.

8. The air compressor according to claim 5, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1, and Δ

P2/Δ

T2, which is the pressure change ratio for the internal pressure of the tank unit during a period Δ

T2 that is longer than Δ

T1 and, based on information for P, Δ

P1/Δ

T1 and Δ

P2/Δ

T2, the rotation speed of the motor in the third mode is changed.

10. The air compressor according to claim 5, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1 and based on the information for P and Δ

P1/Δ

T1, the rotation speed of the motor in the first mode is changed.

12. The air compressor according to claim 5, wherein a detection signal P output by the pressure sensor is calculated to obtain Δ

P1/Δ

T1, which is the pressure change ratio for the internal pressure of the tank unit during a relatively short period Δ

T1 and based on the information for P and Δ

P1/Δ

T1, the rotation speed of the motor in the second mode is changed.

15. A control method for an air compressor that includes a tank unit storing a compressed air, a compressed air generator generating the compressed air to be supplied to the tank unit, a drive portion including a motor for driving the compressed air generation portion, a pressure sensor detecting a pressure in the tank unit, and a controller portion controlling the drive portion, the method comprising:

selecting one of three operating modes including a powerful mode rotating the motor within a high speed range, a silent mode rotating the motor within a low speed range, and an automatic mode automatically changing the rotation speed within a range extending from a low speed to a high speed in accordance with a setup condition;

detecting a pressure P of the compressed air stored in the tank unit; and

changing the rotation speed of the motor at multiple levels based on a selected operating mode and a detection signal received from the pressure sensor.

17. The control method according to claim 15, further comprising:

detecting a temperature T of the motor; and

changing the rotation speed of the motor at multiple levels in accordance with the selected operating mode, the three types of pressure information and a detection signal for the temperature T.

16. A control method for an air compressor that includes a tank unit storing a compressed air, a compressed air generator generating the compressed air to be supplied to the tank unit, a drive portion including a motor for driving the compressed air generation portion, a pressure sensor detecting a pressure in the tank unit, and a controller portion controlling the drive portion, the method comprising:

selecting one of three operating modes including a powerful mode rotating the motor within a high speed range, a silent mode rotating the motor within a low speed range, and an automatic mode automatically changing the rotation speed within a range extending from a low speed to a high speed in accordance with a setup condition;

detecting a pressure P of the compressed air stored in the tank unit;

calculating the detected pressure P to obtain Δ

P1/Δ

T1, which is a pressure change ratio for a relatively short period Δ

T1;

calculating the detected pressure P to obtain Δ

P2/Δ

T2, which is the pressure change ratio for a period Δ

T2 that is longer than the period Δ

T1; and

changing a rotation speed of the motor at multiple levels based on a selected operating mode and three types of pressure information including P, Δ

P1/Δ

T1 and Δ

P2/Δ

T2.

18. The control method according to claim 16, further comprising:

detecting at least one of a power voltage and a load current of the drive portion; and

changing the rotation speed of the motor at multiple levels in accordance with at least one of the detected power voltage and the load current, the selected operating mode and the three types of pressure information.

19. A control method according to claim 16, further comprising:

employing the tank unit pressure P and the pressure change ratio Δ

P2/Δ

T2 to search a table, stored in a memory provided in the controller portion, for the rotation speed of the motor.