JP3083212B2 - air compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air compressor, and more particularly to an air compressor configured to maintain a constant efficiency of intake air from a silencer.

[0002]

2. Description of the Related Art For example, in an air compressor, air is compressed in a cylinder to accumulate pressure in a tank, but a silencer is provided on the air suction side to reduce noise generated from a suction valve or the like at the time of air suction. Have been. As this type of silencer for an air compressor, for example, a relatively small-diameter intake pipe is inserted into a large-diameter silencer main body, and a dustproof filter is mounted inside the silencer main body. Therefore, the air passes through the filter to remove dust in the air, is silenced while passing through the intake pipe, and is supplied into the cylinder of the air compressor.

[0003]

However, in the air compressor having the above-mentioned silencer, dust floating in the air adheres to the filter and only clean air is compressed. During operation, dust gradually accumulates on the filter, and eventually the filter is clogged, reducing the intake efficiency. Therefore, when an air compressor is conventionally used, for example, an operator periodically removes the filter from the silencer and cleans or replaces the filter in order to always generate stable compressed air. However, if the air compressor is operated continuously without interruption, or if it is used in an environment where there is a lot of dust floating in the air, the filter must be cleaned or replaced frequently. However, since the silencer lid is removed and the filter is taken out of the case each time, there is a problem that the maintenance is troublesome.

Therefore, an object of the present invention is to provide an air compressor which has solved the above-mentioned problems.

[0005]

According to the present invention, external air is sucked from a silencer having a filter by driving a motor.
In an air compressor for compressing the sucked air and compressing the air into an air tank, detecting means for detecting a change in the driving characteristics of the motor, and detecting that the driving characteristics of the motor have fallen below a certain value by the detecting means. Compressed air supply means for supplying compressed air from the air tank into the silencer to clean the filter when the air filter is operated.

[0006]

[Function] When the filter is clogged, the amount of air suction from the silencer decreases, and the driving characteristics of the motor deteriorate.
When this is detected, compressed air in the air tank is supplied into the silencer to remove dust adhering to the filter.

[0007]

1 to 3 show an embodiment of an air compressor according to the present invention.

In each of the figures, an air compressor 1 is provided with a compressor main body 3 and a motor 4 for driving the compressor main body 3 above a cylindrical air tank 2.

The compressor body 3 has a piston / cylinder mechanism 3 mounted on an upper part of a crankcase 5 fixed to the air tank 2.
A, 3B. The air compressor 1 is a two-stage compressor, and converts the air compressed by the first-stage piston / cylinder mechanism 3A into higher-pressure compressed air by the second-stage piston / cylinder mechanism 3B. To be stored. or,
FIG. 3 shows the intake side of the first-stage piston / cylinder mechanism 3A.
A silencer 6 for reducing intake noise as shown in FIG.

A driving pulley 7 provided at a rear portion of the compressor body 3 is rotatably driven through a belt 9 wound around a pulley 8 of a motor 4 during an air compression operation, and is driven by each of the piston / cylinder mechanisms 3A, 3B. A piston (not shown) is driven to reciprocate. Thereby, the air sucked from the silencer 6 is compressed by the piston / cylinder mechanism 3A and further supplied to the intake side of the piston / cylinder mechanism 3B via the communication pipe 10 communicating with the piston / cylinder mechanisms 3A and 3B. Compressed by the air tank 2 through the exhaust line 11.
Squeezed.

Reference numeral 12 denotes an electromagnetic valve, which is disposed above the air tank 2. A purge tube 13 has one end connected to the outlet of the solenoid valve 12 and the other end connected to a joint 14 of the silencer 6. Therefore, the solenoid valve 12 is connected to the silencer 6 via the purge tube 13.

A pressure sensor 14 for detecting the pressure in the air tank 2 is attached to the side of the solenoid valve 12. The solenoid valve 12 is normally closed, and supplies the compressed air in the air tank 2 to the silencer 6 via the purge tube 13 when the valve is opened as described later.

A control unit 15 is supported on the air tank 2 by a bracket 16. This control device 15
Is a power switch 17 disposed on cables 16a to 16c for supplying a current from a power source (not shown) to the motor 4.
And a detector (detection means) 18 provided between the power switch 17 and the power supply for detecting a current value flowing through the cables 16a to 16c, and the electromagnetic valve 12 and the power switch 17
And a control circuit 19 for controlling the opening and closing of the switch. Since the detector 18 only needs to be able to detect a physical quantity that changes as the amount of air suction from the silencer 6 decreases, the detector 18 may detect not only a current value but also a voltage value applied to the motor 4, Alternatively, the torque of the motor 4 may be detected.

As shown in FIG. 3, the silencer 6 includes an intake pipe 21 having a plurality of holes 21a formed in a pipe in an internal space 28 of a bowl-shaped silencer main body 20, and an intake pipe 2 having a plurality of holes.
Cylindrical filter 22 formed so as to cover the outer periphery of
And insert it. The intake pipe 21 has an enlarged-diameter portion 21 b whose distal end is enlarged like a flange, and is fixed to the lid 25 by tightening a wing bolt 23 and a nut 24. And
Disc-shaped packing 2 locked at both ends of intake pipe 21
A cylindrical filter 22 made of a porous material such as a sponge or a fine wire mesh is held between the filters 6 and 27. The guide 25a and the guide 20a formed annularly in the silencer main body 20 are fitted and positioned.

The lid 25 has an air inlet 25b at the front.
And a through hole 25c through which the wing bolt 23 penetrates is formed in the center of the front. Also, the peripheral portion 25d of the lid 25
Has an engagement recess 2 provided on the outer periphery of the silencer body 20.
0b is provided with an engaging projection 25e. Therefore, the intake pipe 21 and the filter 22 are attached to the silencer main body 20 while being fixed integrally to the lid 25.

The silencer 6 is attached to the cylinder head 30 of the piston / cylinder mechanism 3A via an elbow 31, as shown in FIG. That is, the elbow 31
One end is screwed into the intake port 30a of the cylinder head 30, and the other end is screwed into the external thread 20d of the outlet 20c of the silencer body 20. Therefore, the air sucked from the air suction port 25 b of the silencer 6 passes through the filter 22 to remove dust in the air, and
a to the outlet 20c, and the passage 31a in the elbow 31
And flows into the intake port 30a of the cylinder head 30.

The distal end of the purge tube 13 is connected to the elbow 31 via a joint 32. Therefore, as will be described later, when the solenoid valve 12 is opened by a valve opening signal from the control circuit 19, the compressed air in the air tank 2 passes through the purge tube 13 and the passage 31 a in the elbow 31 and passes through the silencer 6. And then released to the atmosphere. As a result, dust attached to the filter 22 is purged. Therefore, the control circuit 19, the solenoid valve 12, and the purge tube 13 constitute a compressed air supply unit.

Here, the processing executed by the control circuit 19 together with the operation of the air compressor 1 having the above configuration will be described.

In FIG. 5, when a start switch (not shown) is turned on in step S1 (hereinafter "step" is omitted), the control circuit 19 turns on the power switch 1.
7, the motor 4 is energized, and the pistons (not shown) of the piston / cylinder mechanisms 3A, 3B are driven to reciprocate. Therefore, the air that has passed through the silencer 6 is sucked into the cylinder of the piston / cylinder mechanism 3A, and the compressed air compressed by the piston / cylinder mechanism 3A passes through the communication pipe 10 to the intake side of the piston / cylinder mechanism 3B. The air is supplied, pressurized, and stored in the air tank 2 through the exhaust pipe 11.

In the next step S2, the pressure value output from the pressure sensor 14 is monitored to determine whether the pressure in the air tank 2 has reached a predetermined pressure value Pa (Pa = 13.9 kg / cm ^{2 in} this embodiment). Check if. Therefore, when the operation of the piston / cylinder mechanisms 3A and 3B is continuously performed and the pressure in the air tank 2 reaches the predetermined pressure value Pa, S3
To read the input value (current value supplied to the motor 4 in this embodiment) from the detector 18.

Subsequently, a predetermined pressure value Pb is set in the air tank 2.
It is checked whether (Pb = 14 kg / cm ^{2 in} this embodiment). When the pressure in the air tank 2 reaches the predetermined pressure value Pb, the power switch 17 is opened to stop the power supply to the motor 4, and the piston / cylinder mechanism 3A, 3
The air compression operation of B is stopped (S5).

In step S6, the rate of decrease in the input value (current value) to the motor 4 is monitored. In this embodiment, if the decrease in the input value is 5% or more, the process proceeds to step S7, and the solenoid valve 5 And the solenoid valve 12 is opened. As a result, the compressed air in the air tank 2 is removed from the purge tube 1.
3. Silencer 6 passing through passage 31a in elbow 31
The dust supplied to the inside and adhering to the filter 22 is purged. At this time, the compressed air vigorously flows through a hole 21a formed in the intake pipe 21 in the silencer 6 to remove the filter 22.
The dust that is sprayed on the inner peripheral surface of the filter 22 and adheres to the outer periphery of the filter 22 is blown off, and the filter 22 is cleaned.

As described above, the filter 22 is automatically cleaned when the filter 22 is clogged to some extent.
Can always maintain the initial compressed air discharge amount, and can prevent shortage of air supply due to clogging of the filter 22.

Subsequently, a predetermined pressure value Pc is set in the air tank 2.
(Pc = 12 kg / cm ^{2 in} this embodiment) It is checked whether or not it has fallen below (S8). When the pressure in the air tank 2 reaches the predetermined pressure value Pc or less, the process proceeds to S9, and it is checked whether the solenoid valve 5 is open. At this time, if the solenoid valve 5 is open, the process proceeds to S10 and the solenoid valve 5
And returns to S1. In S9, the solenoid valve 1
When 2 is closed, the process returns to S1.

In S6, if the decrease in the input value to the motor 4 is less than 5%, the process proceeds to S8 without opening the solenoid valve 12, and the processes in S8 to S10 are executed.

As described above, the pressure in the air tank 2 is detected by the pressure sensor 14 and the power switch 17 is turned on or off to thereby control the piston / cylinder mechanism 3.
A and 3B enter the operating state or switch to the stopped state. The pressure of the piston-cylinder mechanism 3A, the air tank 2 by the driver or stop the 3B will vary between 12 kg / cm ² and 14kg / cm ² as shown in FIG. 6 (A).

Since the input value (current value) to the motor 4 is supplied to the motor 4 while the power switch 17 is closed, the pressure in the air tank 2 is increased as shown in FIG. Is supplied while rising from 12 kg / cm ² to 14 kg / cm ² ,
The rate of change is checked. For example, when the amount of air sucked from the silencer 6 is reduced due to clogging of the filter 22, the amount of air suction cannot keep up with the movement of the pistons of the piston / cylinder mechanisms 3A and 3B, and the load on the piston / cylinder mechanisms 3A and 3B is reduced. The input value to the motor 4 is reduced in order not to start the operation.

In this embodiment, when the decrease rate is 5% or more with respect to the reference input value, it is determined that it is necessary to eliminate the clogging of the filter 22, and as shown in FIG. While the valve 4 is stopped, the solenoid valve 12 is opened. Therefore, when compressed air is supplied to the cylinder head 30 of the piston / cylinder mechanism 3A by opening the solenoid valve 12, the piston / cylinder mechanism 3A is in a stopped state, so that generation of compressed air is not hindered.

Immediately after the air purge of the filter 22, even if the input value to the motor 4 is checked while the pressure in the air tank 2 rises from 12 kg / cm ² to 14 kg / cm ² , the filter 22 is clogged. Is eliminated, the solenoid valve 12
And do not perform air purge.

As described above, the degree of clogging of the filter 22 is detected by a change in the input value to the motor 4, and the dust adhered to the filter 22 is automatically discharged by the compressed air blown out from the hole 21 a of the intake pipe 21. To be removed,
Maintenance work can be simplified by eliminating the need for cleaning the filter 22. Also, since the filter 22 can always be cleaned,
The replacement time of the filter 22 can be extended.

Further, since the hole 21a of the intake pipe 21 has a small diameter, it functions as a nozzle, and the compressed air is blown from the inner peripheral side to the outer peripheral side of the filter 22, so that the dust adhering to the outer periphery of the filter 22 is removed. Can be effectively removed.

In the above embodiment, the purge tube 13 is connected to the elbow 31. However, the present invention is not limited to this. For example, as shown in FIG. 7, a connection is made by inserting a joint 32 into the intake port 30a of the cylinder head 30. You may do it.

Although the above embodiment has been described using a two-stage air compressor, it is needless to say that the present invention can be applied to air compressors of other types.

In the above embodiment, the solenoid valve 12 is opened when the current value of the motor 4 drops by 5% or more from the reference input value. However, the rate of decrease when the solenoid valve 12 is opened is arbitrary. And can be changed appropriately according to the capacity of each air compressor and the like.

[0035]

As described above, in the air compressor according to the present invention, when the filter is clogged, the amount of air suction from the silencer is reduced, and the driving characteristics such as the current value, voltage value, and torque of the motor are reduced. When this is detected, compressed air can be supplied into the silencer to automatically remove dust adhering to the filter, eliminating the need for laborious work such as periodically cleaning the filter by the operator. Can be simplified. Also, since the filter can be cleaned according to the degree of contamination of the filter, it is possible to maintain the initial amount of compressed air discharged by always securing a certain amount of air suction at a certain value or more, and to extend the filter replacement time. It has features such as the ability to reduce the number of operations.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of an air compressor according to the present invention.

FIG. 2 is a block diagram of a circuit for controlling a motor and a solenoid valve.

FIG. 3 is a longitudinal sectional view of a silencer.

FIG. 4 is a plan view showing an attached state of a silencer.

FIG. 5 is a flowchart of a process executed by a control circuit.

FIG. 6 is a diagram showing pressure changes in an air tank, opening and closing of a solenoid valve, and input values to a motor.

FIG. 7 is a longitudinal sectional view of a modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air compressor 2 Air tank 3 Compressor main body 4 Motor 6 Silencer 12 Solenoid valve 13 Purge tube 15 Control device 17 Power switch 18 Detector 19 Control circuit 21 Intake pipe 22 Filter 30 Cylinder head 31 Elbow

Claims (1)

(57) [Claims] 1. An air compressor for sucking outside air from a silencer having a filter by driving a motor, compressing the sucked air and accumulating the air in an air tank, detecting means for detecting a change in drive characteristics of the motor, Compressed air supply means for supplying compressed air from the air tank into the silencer and cleaning the filter when the detection means detects that the drive characteristic of the motor has dropped below a certain value. An air compressor characterized by comprising: