JP4475369B2 - Air compressor and its starting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air compression technique such as a screw type, and more particularly to an air compression apparatus and a starting method thereof that can reduce a load at the time of starting.
[0002]
[Prior art]
As shown in FIG. 3, the twin-screw type compressor 10 in the air compressor includes two screw rotors 1, bearings 2a and 2b, a mechanical seal 3 as a high pressure seal, a lip seal 4 as a low pressure seal, a compression It consists of the machine body 5 and the like. The compressor 10 rotates and drives two screw rotors 1 engaged with each other, compresses the air introduced from the air intake port 5a between the two screw rotors, and discharges the compressed air from the discharge port 5b. It has become.
[0003]
FIG. 4 is a block diagram of an air compressor using a screw compressor.
In this block diagram, 7 is a fan motor, 8 is a water tank, 9 is a water cooler, and 11 is a dryer. The fan motor 7 drives the pulley 6b together with the fan 7a that blows air to the water cooler 9, and rotationally drives the rotor driving pulley 6a via the belt. By the rotational driving of the pulley 6a, the screw rotor 1 on the two internal compressors 10 side rotates, and air is introduced from the air introduction line 12a through the air intake port 5a and compressed between the screw rotors 1. Air is supplied to the water tank 8 from the discharge port 5b through the compressed air line 12b.
[0004]
The water tank 8 is supplied with water up to an intermediate position, and the internal water is supplied via the water line 13a by the pressure of the pressurized air supplied to the upper part (about 0.7 MPa: about 7 kg / cm ² g). It is pumped to the water cooler 9, cooled here, and further supplied to the air intake port and the water supply port 5c of the compressor 10 via the water line 13b, and injected into the inside thereof. The water lubricated and cooled in the compressor 10 is circulated to the water tank 8 together with the pressurized air, separated by the steam separator 8a, and mixed into the internal water in the water tank 8. On the other hand, the pressurized air from which moisture has been removed is discharged against the check valve 8b, supplied to the dryer 11 via the compressed air line 12c, dehumidified, and supplied from the air outlet.
[0005]
When starting the compressor 10 configured as described above, if the starting torque of the fan motor 7 is small, suction negative pressure is generated by the rotation of the screw rotor 1, and the suction valve 10a in the air introduction line 12a is temporarily Although it opens, the rotational speed of the screw rotor 1 does not rise rapidly due to insufficient acceleration torque. Thus, it is effective to start the intake valve 10a in a closed state in order to reduce such an activation load. There are the following two methods for closing the intake valve 10a.
[0006]
For example, there is a method in which the intake valve 10a is forcibly “closed” by a spring or the like at startup, and the intake valve 10a is “opened” by high-pressure air when air is introduced. This method is characterized in that the intake valve 10a can always be started as “closed” without using high-pressure air. However, in the spring-type suction valve 10a, the suction throttle control method, which is a general capacity adjustment method of the compressor 10, is configured so that the operating pressure of the suction valve 10a increases as the pressure increases. Since it is gradually “closed”, such suction throttling control cannot be performed.
[0007]
Contrary to this method, there is a method in which the intake valve 10a is forcibly "opened" by a spring or the like at the time of activation, and the intake valve 10a is "closed" by high-pressure air when air is introduced. This method cannot be used when there is no pressure in the compressor 10 and high-pressure air cannot be supplied from the outside. The compressor 10 can keep the pressure in the machine for a certain time from the stop and can close the intake valve 10a. However, when the pressure is released after the stop for a long time or by disassembly or the like. It is inevitable that the engine is started with the intake valve 10a open. In such a case, there has been proposed a method (startup load increase allowable method) in which the load is started while allowing an increase in the start load and the intake valve 10a is closed as the pressure increases. Alternatively, a negative pressure method has been proposed in which a slight suction negative pressure is used to close the suction valve 10a at an early stage (see JP-A-57-105588).
[0008]
[Problems to be solved by the invention]
However, in the above-described start-up load increase permissive system that allows start-up of the start-up load while allowing the start-up load to rise and closes the suction valve 10a as the pressure increases, the pressure in the system is kept constant at the same time or in advance. Since the air release valve 8c that is maintained at “open” is opened, it takes time to obtain the necessary pressure for closing the intake valve 10a, and there is a problem that the increase in the starting load is large.
[0009]
Further, in the negative pressure method in which the suction valve 10a is closed early using a slight suction negative pressure, the structure of the suction valve 10a, piping, and the like becomes complicated in order to enable the operation of the suction valve 10a by the negative pressure. There was a problem.
[0010]
The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a screw-type air compressor and a starting method thereof that can reduce a starting load at the time of starting the compressor by opening and closing a suction valve and a discharge valve of the compressor. There is to do.
[0011]
[Means for Solving the Problems]
According to the present invention, a water tank (8) holding water therein and a compressor (10) for compressing air are provided, and this compressed air is supplied into the water tank (8), In an air compressor for injecting water from the water tank (8) into the compressor (10), water lines (13a, 13b) for introducing pressurized water from the water tank (8) into the compressor (10 ) ; A suction valve (21) configured to control external air introduced into the compressor (10) and to be in a “closed” state as the pressure in the water tank (8) increases. An air discharge valve (22) for adjusting the pressure between the intake valve (21) and the water tank (8), and the air discharge valve (22) is kept constant when the compressor (10) is started. time by a "closed" to raise the pressure of the machine, the suction valve (21) "closed" By obtaining the necessary pressure for the state, and configured to "closed" state in a short time the suction Iriben (21), an air compressor is provided, characterized in that.
[0012]
In the main body (21a), the suction valve (21) is configured such that a piston (21c) is passed through a cylinder body (21b) and an elastic material (21d) is interposed in the piston (21c) so that the valve plate (21e) is always “ When the inside of the water tank (8) is pressurized, the piston (21c) is opposed to the elastic member (21d) so as to be in the “closed” state. ) Is configured to move.
[0013]
In the apparatus of the above invention, the air release valve (22) in the air compressor is kept “closed” for a certain time at the time of startup, and the circuit for releasing the pressure from the inside of the machine to the outside can be closed. Therefore, the pressure inside the machine rises early and the pressure required to close the suction valve (21) can be obtained. As a result, the time from the start to the closing of the intake valve (21) can be greatly shortened, so the start load can be reduced.
[0014]
Moreover, according to the starting method of the present invention, the water tank (8) holding water therein and the compressor (10) for compressing air are provided, and compressed air is supplied into the water tank (8). , A method for starting an air compression device for injecting water into the compressor (10) from the water tank (8) with the pressure. First, when the compressor (10) is started, an air discharge valve (22 ) Is “closed” for a certain period of time to increase the pressure in the machine and obtain the pressure necessary to bring the intake valve (21) into the “closed” state, thereby reducing the intake valve (21) for a short time. The method for starting the air compressor is provided, wherein the air compressor is closed.
[0015]
It is desirable that the time for closing the air discharge valve (8) is a time sufficient to increase the pressure in the compressor (10) and not to increase the pressure in the apparatus more than necessary.
[0016]
In the start-up method of the present invention, the circuit for releasing the pressure from the inside of the machine to the outside is closed by keeping the air release valve (8) “closed” for a certain time at the time of start-up. The pressure required to close the valve (21) can be obtained. As a result, it is possible to reduce the starting load by significantly reducing the time from the starting to the closing of the suction valve (21).
In addition, it is necessary to determine the time for closing the air discharge valve (8) so that the pressure in the machine is not increased more than necessary and sufficient for the pressure increase.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an air compressor according to the present invention. In this figure, 7 is a fan motor, 8 is a water tank, 9 is a water cooler, and 11 is a dryer. The fan motor 7 drives the pulley 6b together with the fan 7a that blows air to the water cooler 9, and rotationally drives the rotor driving pulley 6a on the compressor 10 side via the belt. The screw rotor 1 inside the compressor 10 is rotated by the rotational drive of the pulley 6a, air is introduced from the air introduction line 12a through the air intake port, and the compressed air compressed between the screw rotors 1 is compressed from the discharge port. It is supplied to the water tank 8 through the air line 12b.
[0018]
The water tank 8 includes a water supply valve, a water discharge valve, and the like, and water is always supplied to an intermediate position at a certain level. This amount is, for example, about 10 to 20 liters. A water supply valve (that is, a water supply valve for operating hours) is also near the compressor 10. In addition, compressed air compressed between the screw rotors 1 of the compressor 10 is supplied to the upper portion of the water tank 8, and a pressure within a predetermined range (for example, about 0.7 MPa or more: about 7 kg / cm ² g or more). ). Due to this pressure, during normal operation, the internal water is pumped to the water cooler 9 through the water line 13a, where it is cooled by the air blown from the fan 7a, and is always kept at around + 10 ° C.
[0019]
Further, the cooling water in the water cooler 9 is supplied to the air intake port and the water supply port of the compressor 10 through the water line 13 b by the air pressure in the water tank 8. A nozzle is provided at the junction between the water line 13b and the air intake and the water supply port, and an appropriate amount of water is injected into the compressor 10 while maintaining the pressure on the water tank 8 side. ing. This water injection amount wets and lubricates the sliding surfaces of the screw rotor 1 and the mechanical seal 3 inside the compressor 10, and cools the screw rotor 1 and the mechanical seal 3 to keep the temperature within an appropriate range. In addition, the temperature of the compressed air is lowered so as to increase the compression efficiency of the compressor 10.
[0020]
Next, the water lubricated and cooled inside the compressor 10 is circulated from the discharge port to the water tank 8 through the compressed air line 12b together with the pressurized air, and is separated by the steam separator 8a to be stored in the water tank 8. Mixed into the internal water. The pressurized air from which moisture has been removed is discharged against the check valve 8b, supplied to the dryer 11 through the compressed air line 12c, dehumidified, and supplied from the air outlet. The temperature of the compressed air leaving the water tank 8 is, for example, about the outside air temperature + 20 ° C. and contains moisture. Therefore, in the dryer 11, the pressurized air is once lowered below the outside air temperature to condense and remove the moisture inside, and then reheated to return to the outside air temperature or above. Therefore, dry compressed air having almost no moisture can be supplied.
[0021]
The air compressor of the present invention is provided with water lines 13 a and 13 b for introducing pressurized water from the water tank 8 into the compressor 10 and a suction valve 21. The intake valve 21 is configured to control air from the outside introduced into the compressor 10 and to be in a “closed” state as the pressure in the water tank 8 increases.
[0022]
FIG. 2 is a block diagram of the intake valve of the present invention. In the main body 21a, the intake valve 21 is configured such that a piston 21c is passed through a cylinder body 21b, and an elastic material 21d such as a coil spring is interposed in the piston 21c so that a valve plate 21e that restricts the entry and exit of air is always in an “open” state. It is to make. The suction valve 21 is configured such that when the inside of the water tank 8 is pressurized, the piston 21c moves against the elastic material 21d so that the valve plate 21e moves so as to be in a “closed” state (arrow). Direction two-dot chain line).
[0023]
On the line between the intake valve 21 and the water tank 8, an air discharge valve 22 is provided. The air discharge valve 22 adjusts the pressure between the suction valve 21 and the water tank 8. Therefore, by closing the discharge valve 22 for a certain period of time, when the compressor 10 is started, the circuit for releasing the pressure from the inside of the machine is closed, and the suction valve 21 is set so that the pressure inside the machine rises early. It can be in the “closed” state.
[0024]
That is, when the compressor 10 is started, the air discharge valve 22 is closed for a certain period of time, the circuit for releasing the pressure from the inside of the machine is closed, and then the pressure inside the machine is raised early and the intake valve 21 is closed. By obtaining the pressure, the time from the start to the closing of the intake valve 21 can be greatly shortened.
[0025]
It is desirable that the time during which the air discharge valve 22 is closed is a time sufficient for increasing the pressure and a time during which the pressure in the machine does not increase more than necessary. It is necessary to determine the time for closing the air discharge valve 22 so that the time is sufficient for the pressure increase and the pressure in the machine does not increase more than necessary.
[0026]
In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention. For example, although the case of the screw type compressor 10 has been mainly described, other compressors may be used as long as it is a water injection type. Moreover, although the case where air was compressed was demonstrated, it can apply to other gas as it is.
[0027]
【The invention's effect】
As described above, in the air compressor of the present invention and its starting method, the circuit for releasing the pressure from the inside of the machine to the outside is closed by keeping the air release valve “closed” for a certain time at the time of startup. Since the pressure required to close the suction valve by rising early can be obtained, the starting load can be reduced by greatly reducing the time from the start to the closing of the suction valve.
[0028]
In addition, in the conventional negative pressure system, since the suction valve can be operated by negative pressure, the structure of the suction valve, piping and the like is not complicated, and the starting load at the time of starting the compressor can be reduced. It has excellent effects such as being able to.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a screw-type air compressor according to the present invention.
FIG. 2 is a configuration diagram of an intake valve of the present invention.
FIG. 3 is a schematic view of a screw type air compressor.
FIG. 4 is an overall configuration diagram of a conventional screw type air compressor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Screw rotor 2a, 2b Bearing 3 Mechanical seal 4 Gas seal 5 Compressor main body 6a, 6b Pulley 7 Fan motor 8 Water tank 8a Air-water separator 9 Water cooler 10 Compressor 11 Dryer 12a Air introduction line 12b, 12c Compressed air Lines 13a and 13b Water line 20 Pressurized water injection line 21 Suction valve 21a Main body 21b Cylinder body 21c Piston 21d Elastic material 21e Valve plate 22 Ventilation valve

Claims (4)

A water tank (8) holding water therein and a compressor (10) for compressing air are provided, and this compressed air is supplied into the water tank (8) from the water tank (8) by its pressure. In the air compressor for injecting water into the compressor (10),
A water line (13a, 13b) for introducing pressurized water from the water tank (8) into the compressor (10), an external air introduced into the compressor (10), and the water tank (8) A suction valve (21) configured to be in a “closed” state as the pressure in the interior increases, and a discharge valve for adjusting the pressure between the suction valve (21) and the water tank (8) (22)
To start up the compressor (10), the air release valve (22) is "closed" for a certain period of time, thereby increasing the pressure in the machine and bringing the suction valve (21) into the "closed" state. An air compressor characterized in that the intake valve (21) is brought into a "closed" state in a short time by obtaining a necessary pressure . In the main body (21a), the intake valve (21) passes a piston (21c) through a cylinder body (21b), and an elastic material (21d) is interposed in the piston (21c) so that the valve plate (21e) is always “ When the inside of the water tank (8) is pressurized, the piston (21c) is opposed to the elastic member (21d) so as to be in the “closed” state. The air compressor according to claim 1, wherein the air compressor is configured to move. A water tank (8) holding water therein and a compressor (10) for compressing air are provided, compressed air is supplied into the water tank (8), and the pressure from the water tank (8) A method for starting an air compressor for injecting water into the compressor (10),
First, when the compressor (10) is started, the air release valve (22) is "closed" for a certain period of time to increase the pressure in the machine and bring the intake valve (21) to the "closed" state. A method for starting an air compressor, wherein the suction valve (21) is brought into a "closed" state in a short time by obtaining a necessary pressure.   Air according to claim 3, characterized in that the time during which the air discharge valve (22) is closed is sufficient to increase the pressure in the compressor (10) and the pressure in the apparatus does not increase more than necessary. How to start the compressor.

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