Air compressor and method for controlling the same

• US 20040191073A1
• Filed: 02/19/2004
• Published: 09/30/2004
• 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
• Granted Patent: US 7,704,052 B2
• Time in Patent Office: Days
• 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. An air compressor, comprising:

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;

a control circuit portion for controlling said drive portion; and

a pressure sensor for detecting pressure of said compressed air reserved in said tank portion;

wherein said control circuit portion includes a unit for controlling the rotational speed of said motor multistageously on the basis of a detection signal output from said pressure sensor.

2. The air compressor according to claim 1,

wherein the rotational speed of said motor is set multistageously to have a plurality of values such as 0, N, 2N, 3N, . . . , and nN (in which n is an arbitrary number);

and

one of said values is selected by said control circuit portion to thereby control said motor.

3. An air compressor, comprising:

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;

wherein the control circuit portion includes a unit for calculating internal pressure P of said tank portion on the basis of a detection signal output from a pressure sensor, calculating the rate Δ

P/Δ

T of pressure change Δ

P to predetermined time Δ

T and deciding the rotational speed of said motor on the basis of at least one of the pressure P and the rate Δ

P/Δ

T of pressure change.

4. An air compressor according to claim 3,

wherein said control circuit portion further includes a memory for storing information indicating relations among the pressure P of said tank portion, the rate Δ

P/Δ

T of pressure change and the rotational speed N of said motor; and

the rotational speed of said motor is decided by means of searching said memory.

5. A method of controlling an 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 having 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 the rate Δ

P/Δ

T of change Δ

P in pressure P to predetermined time Δ

T; and

deciding the rotational speed of said motor of said drive portion on the basis of at least one of the pressure P of said tank portion and the rate Δ

P/Δ

T of pressure change.

6. The method of controlling an air compressor according to claim 5, further comprising:

searching for the rotational speed of said motor by referring to a table stored in a memory of said control circuit portion on the basis of the pressure P of said tank portion and the rate Δ

P/Δ

T of pressure change.

7. An air compressor, comprising:

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;

a control circuit portion for controlling said drive portion; and

a temperature sensor for detecting the temperature of said motor of said drive portion;

wherein said control circuit portion controls the rotational speed of said motor multistageously on the basis of a detection signal output from said temperature sensor.

8. The air compressor according to claim 7, further comprising:

a pressure sensor for detecting pressure of compressed air in said tank portion;

wherein said control circuit portion controls the rotational speed of said motor multistageously on the basis of detection signals output from said temperature sensor and said pressure sensor.

9. The air compressor according to claim 7, further comprising:

a voltage detection circuit for detecting a power-supply voltage of said drive portion; and

a current detection circuit for detecting a load current of said drive portion;

wherein said control circuit portion controls the rotational speed of said motor multistageously on the basis of the detection signal output from said temperature sensor and a detection signal output from at least one of said voltage detection circuit and said current detection circuit.

10. The air compressor according to claim 7, wherein said control circuit portion controls the rotational speed of said motor in at least three stages of high speed, middle speed and low speed.

11. A method of controlling an 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 having a motor for driving said compressed air generation portion, and a control circuit portion for controlling said drive portion, said method comprising:

detecting the temperature of said motor of said drive portion by a temperature sensor; and

controlling the rotational speed of said motor in at least three stages of high speed, middle speed and low speed on the basis of a detection signal output from said temperature sensor.

12. A method of controlling an air compressor according to claim 11, further comprising:

detecting the pressure of compressed air in said tank portion by a pressure sensor; and

controlling the rotational speed of said motor in at least three stages of high speed, middle speed and low speed on the basis of detection signals output from said temperature sensor and said pressure sensor.

13. The method of controlling an air compressor according to claim 11, further comprising:

detecting a power-supply voltage of said drive portion and a load current of said drive portion; and

controlling the rotational speed of said motor in at least three stages of high speed, middle speed and low speed on the basis of the detected voltage and current and a detection signal output from said temperature sensor.

14. An air compressor, comprising:

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;

a control circuit portion for controlling said drive portion; and

a pressure sensor for detecting pressure of said compressed air reserved in said tank portion;

wherein said control circuit portion calculates the rate Δ

P1/Δ

T1 of change Δ

P1 in internal pressure of said tank portion to a relatively short time Δ

T1 and the rate Δ

P2/Δ

T2 of change Δ

P2 in internal pressure of said tank portion to a time Δ

T2 longer than the time Δ

T1 on the basis of detection signals output from said pressure sensor and controls the rotational speed of said motor multistageously on the basis of at least one of the two pressure change rates.

15. The air compressor according to claim 14, further comprising:

a temperature sensor for detecting the temperature of said motor;

wherein said control circuit portion controls the rotational speed of said motor multistageously on the basis of the two pressure change rates and a detection signal output from said temperature sensor.

16. The air compressor according to claim 15, further comprising:

a voltage sensor for detecting a power-supply voltage of said drive portion; and

a current sensor for detecting a load current of said drive portion;

wherein said control circuit portion controls the rotational speed of said motor multistageously on the basis of the two pressure change rates and at least one of detection signals output from said voltage sensor and said current sensor.

17. A method of controlling an 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 having a motor for driving said compressed air generation portion, and a control circuit portion for controlling said drive portion;

said method comprising;

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

calculating the rate Δ

P1/Δ

T1 of pressure change Δ

P1 to a relatively short time Δ

T1 on the basis of the detected pressure P;

calculating the rate Δ

P2/Δ

T2 of pressure change Δ

P2 to a time Δ

T2 longer than the time Δ

T1 on the basis of the detected pressure P; and

controlling the rotational speed of said motor multistageously on the basis of the two pressure change rates.

18. The method of controlling an air compressor according to claim 17, further comprising:

detecting the temperature T of said motor; and

controlling the rotational speed of said motor multistageously on the basis of the two pressure change rates and a detected signal of the temperature T.

19. The method of controlling an air compressor according to claim 17, further comprising:

detecting a power-supply voltage E of said drive portion and a load current I of said drive portion; and

controlling the rotational speed of said motor multistageously on the basis of the two pressure change rates and at least one of the detected power-supply voltage E and the detected load current I.