JPH06123295A - Capacity controller in compressor - Google Patents

Abstract

PURPOSE:To prevent housing of a closing valve of an unloader at transition from a capacity-regulated operation to a no-load operation by connecting a gas passage communicating to a control pressure chamber of the unloader to a gas passage communicating to a receiver tank through a regulator valve. CONSTITUTION:When a pressure in a receiver tank 7 for reserving compression gas discharged by a compressor body 1 exceeds a first set value and a first regulator valve 40 is opened, a pressure is supplied from a passage 22 to a control pressure chamber 38 of an unloader 3, and a part of the gas is introduced into a suction passage 12 through an orifice 29 and an opening 19. When the pressure in the passage 22 exceeds a second set value, a second regulator valve 50 is opened, and a part of the pressure gas is introduced into the suction passage 12 through the regulator valve 50 and the orifice 29. When the pressure in the receiver tank 7 reaches a third set value, a pressure switch PS is actuated so as to bring a directional control valve 26 to B position and the pressure in the passage 21 is supplied to the control pressure chamber 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor provided with a compressor body, an unloader provided on the suction side of the body, and a receiver tank on the discharge side of the body. The present invention relates to a capacity control device for a compressor, which activates an unloader when the pressure exceeds a predetermined value and controls the amount of gas sucked into the compressor body steplessly by the unloader.

[0002]

2. Description of the Related Art In a compressor, particularly a rotary compressor, when the gas pressure stored in a receiver tank exceeds a predetermined value, a method of controlling the capacity by closing an intake port of the compressor with an unloader is known. A cylinder that slidably accommodates a piston connected to a valve body that opens and closes a suction port in an unloader, a control pressure chamber that applies pressure in the receiver tank to one surface of the piston, and the suction port to the other surface of the piston. When the gas pressure in the receiver tank exceeds the first specified value by being partitioned by the piston into a secondary pressure chamber that applies pressure in the suction passage on the working chamber side for gas compression of the compressor. The gas pressure in the receiver tank is supplied to the control pressure chamber of the unloader, and the gas pressure in the receiver tank is depressurized and supplied to the secondary pressure chamber. The opening area of the suction port is controlled steplessly by the valve body of the feeder, and a pressure switch for detecting the gas pressure in the receiver tank is provided so that the pressure in the receiver tank becomes larger than the set value. When the second set value is exceeded, the gas pressure supply to the secondary pressure chamber of the unloader is stopped by one solenoid valve, and the unloader control is further performed by the one solenoid valve via the bypass passage. Japanese Utility Model Laid-Open No. 1-78284 discloses that the suction port of the unloader is closed rapidly by supplying the pressure in the receiver tank to a pressure chamber.

[0003]

SUMMARY OF THE INVENTION In the above-mentioned prior art, a regulator valve for supplying the pressure in the receiver tank to the control pressure chamber of the unloader when the pressure in the receiver tank exceeds a first specified value, Since the unloader is controlled steplessly, and the compressed gas in an amount corresponding to the consumption amount of the compressed gas stored in the receiver tank is supplied from the compressor body to the receiver tank, the fluctuation range of the gas pressure on the consumption side However, the problem is that the load power (power consumption ratio) after the unloader closes the intake port and shifts to no-load operation can be reduced to only about 70% of full-load operation. is there. The capacity control device in this type of compressor can make the load power of the compressor substantially match the rated output of the prime mover with the unloader fully opening the suction port, and provide a compressor with high power efficiency. However, the return pressure from no-load operation to full-load operation of the unloader is determined in consideration of the minimum return pressure range of each control device such as a solenoid valve, and the specified pressure at full load of the compressor (regulator It is usually set to a value lower than the specified value at the time of starting operation of the valve). Therefore, the pressure in the pipe on the consuming side drops and the pressure fluctuation range is large, which causes a trouble in the operation of the equipment used. If the specified pressure value is increased to avoid this, the load power of the compressor increases correspondingly, which may cause overheating of the compressor and the driving prime mover.

Therefore, an attempt has been made to improve the timing of closing and opening the suction port during operation of the unloader by providing a throttle in the passage for supplying the gas pressure in the receiver tank on the side of the secondary pressure chamber of the unloader. Proposed (JP-A-3
No. -121291) urges a spring acting in a fully open direction to a valve body that closes the suction port of the unloader to ensure that the suction port of the unloader is fully opened, the gas pressure of the spring is higher than the specified pressure. If the pressure that clears the set load is not increased, capacity control will not start, and the compressor and prime mover may become overloaded. The present invention maintains the feature of the capacity control device in which the opening / closing valve of the unloader controls the opening area of the suction port steplessly, and the pressure in the piping system communicating with the discharge port of the compressor body such as the receiver tank is predetermined. When the opening / closing valve starts capacity control after exceeding the set value and before the opening / closing valve completely closes the suction port and shifts to no-load operation, the movement of the opening / closing valve is slowed down, whereby the receiver tank An object of the present invention is to provide a capacity control device capable of operating a compressor without frequently repeating the opening / closing operation of opening / closing the suction port even when the amount of consumption of the gas stored therein changes greatly.

[0005]

According to the present invention, an on-off valve opens and closes an intake port in response to a gas pressure introduced into a compressor body and a control pressure chamber, and is sucked into the working chamber of the compressor body. The present invention relates to a capacity control device in a compressor that includes an unloader that controls a gas flow rate and a receiver tank that stores the compressed gas discharged by communicating with a discharge side of the working chamber via a check valve. The unloader is fixed to the opening / closing valve, and is opened / closed by a gas pressure supplied to the control pressure chamber and a spring force of a spring for urging the opening / closing valve in a direction of opening, i.e., a direction away from the suction port. On-off valve moving means for moving the valve is provided. First communicating with the receiver tank
And a second gas passage communicating with the control pressure chamber of the unloader are connected to each other to provide a first regulator valve. The first reguulator valve opens the fluid passage when the gas pressure in the first gas passage exceeds a predetermined first set value, and causes the second gas passage to become the first gas passage. I can communicate.

A third gas passage is connected to the suction passage on the side of the working chamber of the compressor main body from the suction port of the unloader, and the third gas passage is connected to the first and second gas passages. A switching valve is provided. The switching valve has a valve body having a first position in which the second gas passage and the third gas passage communicate with each other and a second position in which the second gas passage communicates with the first gas passage. The position is selectively switched to. The gas supplied to the third gas passage is opened in the third gas passage when the gas pressure supplied through the switching valve exceeds a second preset value. A second regulator valve for supplying pressure to the suction passage on the compressor body side from the suction port of the unloader and an orifice provided with a predetermined fixed fluid passage are provided in parallel. A pressure switch for detecting the pressure in the gas passage between the check valve and the receiver tank to the first gas passage; and the switching valve when the pressure exceeds a predetermined third set value. Is switched from the first position to the second position, and switching means is provided for switching the switching valve to the first position when the pressure falls below the first set value. The second reguulator valve includes a housing having a first opening communicating with the switching valve and a second opening communicating with a suction passage on the working chamber side of the compressor body from a suction opening of the unloader. A valve formed in the housing, disposed in a fluid passage that connects the first opening and the second opening, and urged by a spring to close the first opening. The orifice may be a through hole that is formed on the valve body and that always connects the first opening and the second opening.

[0007]

According to the present invention, the compressed gas compressed in the working chamber by the operation of the compressor body is stored in the receiver tank which is communicated with the discharge side through the check valve to meet the demand of the consumer side. Accordingly, it is taken out from the receiver tank and consumed.
When the demand on the consumer side decreases and the gas pressure in the receiver tank exceeds a predetermined first set value (for example, 7.1 kgf / cm ² ), the first regulator valve opens and the second gas passage opens from the first gas passage. The pressure is supplied to the control pressure chamber of the unloader through the gas passage of the second unloader, and a part of the pressure gas flows from the second gas passage to the third gas passage because the valve body of the switching valve is at the first position. It is introduced into the suction passage on the side of the working chamber of the compressor body from the suction port of the unloader via the orifice. The opening / closing valve of the unloader starts to move in the direction of closing the suction port by the pressure of the control pressure chamber in the moving means and the elastic force of the spring acting in the direction against the pressure, and starts the capacity control.
The rise in the discharge pressure of the compressor body slows down. When the gas pressure between the check valve on the discharge side of the compressor main body and the first gas passage, for example, the gas pressure in the receiver tank becomes higher, the second gas passage is provided in the third gas passage. Regulator valve has a second set value (eg 0.7 kgf / c
At m ² ), the fluid passage is opened and the compressed gas is introduced from the intake port of the unloader into the intake passage on the working chamber side of the compressor body. This slows down the rate of increase of the gas pressure in the control pressure chamber.

From the check valve on the discharge side of the compressor body, the first
When the gas pressure up to the gas passage of, for example, the gas pressure in the receiver tank exceeds a third set value (for example, 8.0 kgf / cm ² ) slightly larger than the predetermined first set value, The pressure switch detects this, and the switching means switches the valve body of the switching valve to the second position. As a result, the second gas passage is directly connected to the first gas passage, and the third gas passage is disconnected from the second gas passage, so that the opening / closing valve moving means of the unloader is connected to the control pressure chamber. Due to the gas pressure in the supplied first gas passage, the on-off valve is reliably seated in the suction port against the elasticity of the spring, the suction port is completely closed, and no-load operation starts. When a large amount of the compressed gas stored in the receiver tank is consumed and the gas pressure in the receiver tank falls below the first set value, the switching means switches the switching valve to the first position, and The first regulator valve closes its fluid passage. Therefore, the opening / closing valve of the unloader returns to the position where the suction port is completely opened by the elastic force of the spring, and the compressor body returns to the full load operation state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a piping diagram of an embodiment of a capacity control device for a screw type air compressor to which the present invention is applied, FIG. 2 is a sectional view of its unloader, and FIG. 3 is a sectional view of its reguulator valve. An intake block type unloader 3 is attached to the suction side of the compression working chamber 2 of the Screwil type rotary compressor body 1, and the discharge chamber 4 on the discharge side of the compression working chamber 2 includes a check valve 5 and a discharge pipe 6. The receiver side tank 7 is connected to the receiver tank 7, and the compressed air outlet 8 of the receiver tank 7 is connected to the consumption side air pipe 11 via the opening / closing valve 9 and the check valve 10. The unloader 3 includes a housing 31 as shown in FIG.
A piston 34 is fixed to an opening / closing valve 33 that opens and closes an intake port 32 that sucks air into the housing 31 through an air filter (not shown), and a shaft of a cylinder 35 that slidably accommodates the piston 34. Two springs 36, 37 for urging the piston 34 in a direction of enlarging the opening area of the suction port 32 by arranging the opening / closing valve 33 from the suction port 32 are disposed on one side in the direction. A control pressure chamber 38 is formed on the other side in the axial direction of 34. The spring 3
The cylinder chamber accommodating 6, 37 communicates with the passage forming a part of the intake passage 12 to the working chamber 2 of the compressor body 1 through the opening 39. When the male rotor 13 of the compressor body 1 is rotationally driven by a prime mover (not shown), the male rotor 13
Together with the female rotor (not shown) meshing with the rotor 13, the air sucked from the suction port 32 of the unloader 3 through the suction passage 12 is compressed in the working chamber 2 and discharged into the discharge chamber 4. The discharged compressed air is discharged into the receiver tank 7 through the check valve 5 and the discharge pipe 6. Oil for lubricating the male and female rotors and cooling the compressor body 1 is sent to the working chamber 2 via the oil supply pipe 14, the cooler 15, and the oil amount adjusting valve 16 by utilizing the pressure in the receiver tank 7. The oil is discharged into the discharge chamber 4 together with the compressed air, and is sucked into the pump 17 as a gas-liquid mixed fluid from the lowest level portion of the discharge chamber 4, and the pipe 18
It is collected in the receiver tank 7 via the discharge pipe 6 and separated from the compressed air in the receiver tank 7.

The other end of the first gas passage 21 made of a pipe, one end of which is connected to the air outlet 8 of the receiver tank 7, is connected to the inlet side 41 of the first regulator valve 40, and the other end of the unloader 3 is connected. The other end of the second gas passage 22 formed of a pipe, one end of which is connected to the opening 30 formed in the housing 31 and which is connected to the control pressure chamber 38, is connected to the outlet side 42 of the first regurator valve 40. It
As shown in FIG. 3, in the first regulator valve 40, a valve seat 44 is formed in a fluid passage 43 that connects the inlet side 41 and the outlet side 42, and the valve body 45 seated on the valve seat 44 is In the housing of the reguulator valve 40, it is fixed to a diaphragm 46 whose peripheral edge is fixed by the housing, and one surface of the diaphragm 46 is provided with an inlet side 41.
Is applied to the inlet side 41 via the passage 47, and the elastic force of the spring 48 is urged to the other surface of the diaphragm 46 in a direction against the pressure, and the elastic force of the spring 48 is applied to the housing. It can be adjusted by a screw rod 49 that is screwed. Therefore, the receiver tank 7 reaches the first regulator valve 40 via the air outlet 8 of the receiver tank 7 and the first gas passage 21 and is applied to the diaphragm 48 from the inlet side 41 via the passage 47.
When the internal air pressure becomes larger than the biasing force of the spring 48, the valve body 45 separates from the valve seat 44 and the fluid passage 43
Is opened, and the pressure in the first gas passage 21 is supplied to the control pressure chamber 38 through the second gas passage 22, the orifice 28 provided in the passage 22, and the opening 30 formed in the housing 31 of the unloader 3. . In this embodiment, the elastic force of the spring 48 adjusted by the screw rod 49 is adjusted so that the air pressure (first set value) for opening the fluid passage 43 of the first reguulator valve 40 becomes 7.1 kgf / cm ^2. Set in advance.

A branch passage 2 that branches from between the air outlet 8 of the first gas passage 21 and the first regurator valve 40.
4, a branch passage 25 branching between the orifice 28 of the second gas passage 22 and the unloader 3, and a housing 31 of the unloader 3 formed in the housing 31 of the unloader 3. A third pipe consisting of one end of which is connected to an opening 19 which is connected to the passage 12.
The gas passage 23 is connected to the electromagnetic three-way switching valve 26. While the switching valve 26 is energized, the A portion of the valve body 27 is in the communicating position so that the branch passage 25 of the second gas passage 22 communicates with the third gas passage 23. When the de-excitation is performed, the portion B of the valve body 27 is in the communicating position, and the branch passage 25 of the second gas passage 22 is made to communicate with the branch passage 24 of the first gas passage 21. It is in position 2. A second regulator valve 50 and an orifice 29 having a fixed fluid passage having a predetermined flow passage area are connected in parallel to the third gas passage 23. The second regulator valve 50 has the same configuration as the first regulator valve 40. Therefore, the reference numerals 41 to 49 used for the following description refer to the same portions as the reference numerals 41 to 49 of the first reguulator valve 40, respectively. When the valve body 27 of the switching valve 26 is in the first position for positioning the A portion in the communication position, when the first regulator valve 40 opens the fluid passage 43, the outlet side 42 of the reguulator valve 40 is opened. To second gas passage 2
2, the compressed air supplied to the third gas passage 23 through the orifice 28, the branch passage 25, and the portion A of the valve body 27 passes only the orifice 29 while the pressure is low, and passes through the opening 19 to the compressor main body. 1 is introduced into the suction passage 12. Next, when the pressure in the receiver tank 7 becomes high and the force applied to the diaphragm 46 by the air pressure supplied to the second regulator valve 50 becomes larger than the elasticity of the spring 48,
The second regulator valve 50 opens the fluid passage 43.
At this time, the compressed air that has passed through the orifice 29 and the second regulator valve 50 is both introduced into the suction passage 12 of the compressor body 1 through the opening 19. In the present embodiment, the air pressure (second set value) for opening the fluid passage 43 of the second regulator valve 50 is set to approximately 0.7 kgf / cm ^2.
4 adjusted by the screw rod 49 so that
The elasticity of 8 is predetermined.

The pressure of the compressed air stored in the receiver tank 7 is detected, and when the pressure exceeds a predetermined value from the first set value (7.1 kgf / cm ² ), the circuit is opened and detected. A pressure switch PS that closes when the pressure drops below the first set value is provided in the receiver tank 7, and the pressure switch PS is connected to the electromagnetic three-way switching valve 26. As a result, the switching valve 26 is provided with the valve body 2 until the pressure in the receiver tank 7 reaches a predetermined value.
7 is in the first position for placing the A portion in the communication position, and the second position
Is connected to the third gas passage 23, and when the pressure in the receiver tank 7 exceeds the predetermined value, the valve body 27 is switched to the second position where the portion B is in the communication position. , The second gas passage 22 and the first gas passage 21
When the pressure in the receiver tank 7 falls below the first set value from this state, the valve body 27 is returned to the first position. In this embodiment, the predetermined value (third set value) of the pressure detected by the pressure switch PS is preset to 8.0 kgf / cm ² .

In the present embodiment, the discharge of the compressor body 1 when the opening / closing valve 33 in the unloader 3 is in the state where the suction port 32 is completely opened and the compressor body 1 is in full load operation by the prime mover. Air pressure is 7kgf / cm
^Set to ² . When the compressor body 1 is in full load operation,
When the amount of compressed air taken out from the receiver tank 7 to the consumer side air pipe 11 decreases, the air pressure inside the receiver tank 7 gradually rises. Then, when this air pressure exceeds 7.1 kgf / cm ² which is the first preset value set in the first regulator valve 40, the fluid passage 43 of the first regulator valve 40 opens. Since the first set value is lower than the preset third set value of 8.0 kgf / cm ² set in the pressure switch PS, the valve body 27 of the switching valve 26 places the A portion in the communicating position. The compressed air which is in the position and has passed through the fluid passage 43 of the first regulator valve 40 is supplied to the control pressure chamber 38 of the unloader 3 through the second gas passage 22 and applies the pressure to one surface of the piston 34. A part of the compressed air supplied to the second gas passage 22 is introduced into the suction passage 12 of the compressor body 1 through the switching valve 26, the third gas passage 23 and the opening 19. The air pressure supplied to the third gas passage 23 is the second
Is greatly decompressed by the orifice 28 disposed in the gas passage 22 of No. 1, and the decompressed air pressure is lower than 0.7 kgf / cm ² which is the second preset value set in the second reguulator valve 50. In the interval, the fluid passage 43 of the second regulator valve 50 is introduced into the suction passage 12 of the compressor body 1 via the orifice 29 without opening the fluid passage 43. The piston 34 moves in a direction approaching the suction port 32 against the biasing force of the springs 36 and 37 by the air pressure supplied to the control pressure chamber 38, and the opening area of the suction port 32 is changed by the opening / closing valve 33. Intake passage 12 of the compressor body 1
Start the capacity control to limit the intake air flow rate to the. After that, stepless capacity control is performed as the pressure in the first gas passage 21 rises.

When the consumption of the compressed air taken out from the consumption side air pipe 11 is still small, the pressure in the receiver tank 7 rises and the first gas passage 21 passes through the branch passage 25 of the second gas passage 22 to reach the first gas passage 21. When the compressed air pressure supplied to the gas passage 23 of No. 3 also gradually increases and exceeds the predetermined second set value which is 0.7 kgf / cm ² set for the second reguulator valve 50, the second reguulator valve is set. 5
0 fluid passage 43 is opened, and suction passage 1 of compressor body 1 is opened.
Compressed air passing through the orifice 29 and compressed air passing through the fluid passage 34 of the second reguulator valve 50 are introduced into the nozzle 2 in parallel through the opening 19. When the unloader 3 starts the stepless capacity control, the springs 36 and 37 that urge the opening / closing valve 33 in the opening direction are compressed. Of the two springs 36, 37, the spring 36 having the larger diameter has a smaller spring constant than the spring 37 having the smaller diameter, and the spring 36 flexes more than the other spring 37.
The spring 37 is largely bent after the collar that locks 37 abuts the piston 34. On the other hand, when the gas pressure in the second gas passage 22 rises, the moving speed of the piston 34 also increases, but when the fluid passage 34 of the second regulator valve 50 opens, the third passage 23 and the opening 19 are opened.
The amount of compressed air introduced into the suction passage 12 of the compressor body 1 through the passage increases, so that the moving speed of the opening / closing valve 33 is the second.
It does not increase so much regardless of the rise in the gas passage 22 of
Rather slow down. In the present embodiment, the pressure in the second gas passage 22 is the second set value (0.7 kgf / cm ² ).
Has reached the third set value (8.0 kgf / c) and the second regulator valve 50 has started to operate, the pressure switch PS has reached the third set value (8.0 kgf / c).
Until operating at m ^2), the pressure in the control chamber 38 of the unloader 3 are approximately 1.0 kgf / cm ² before and after (0.9
~1.3kgf / cm ²⁾ to be pressing. When the pressure in the receiver tank 7 exceeds a preset third set value of 8.0 kgf / cm ² , the pressure switch PS detects this and demagnetizes the electromagnetic three-way switching valve 26, and the valve body 27 is switched to the second position where the circulation position is B part. Therefore, the second gas passage 22 communicates with the first gas passage 21 via the branch passage 25, and the air pressure exceeding the first set value is supplied to the control pressure chamber 38 of the unloader 3. The supply of the pressurized air to the third gas passage 23 is cut off. As a result, the piston 34 immediately opens the on-off valve 3
3 is securely seated at the fully closed position of the suction port 32, and the compressor main body 1 is shifted to the no-load operation. In the above-described embodiment, the piston 34 fixed to the valve rod of the opening / closing valve 33 is described as the opening / closing valve moving means for moving the opening / closing valve 33 with respect to the suction port 32. Even if the diaphragm is fixed, the opening / closing valve moving means having the same function can be configured.

The operation of the above embodiment will be described with reference to FIGS. FIG. 4 is a diagram showing the relationship between the pressure supplied into the control pressure chamber 38 of the unloader 3 and the opening degree (position) of the opening / closing valve 33 by a solid line. Control pressure chamber 38 of unloader 3
When the pressure is not supplied to the opening / closing valve 33, the opening / closing valve 33 is at the position L ₁ farthest from the suction port 32 due to the urging force of the springs 36 and 37. When the pressure in the first gas passage 21 exceeds the first set value (7.1 kgf / cm ² ), the valve body 45 of the first reguulator valve 40 starts to open the fluid passage 43,
The compressed air is decompressed through the second gas passage 22 and the orifice 28 and supplied to the control pressure chamber 38, and at the same time, a part of the compressed air is passed through the switching valve 26 and the third gas passage 2 is formed.
3 is also supplied. The pressure in the control pressure chamber 38 rises rapidly, and when the pressure exceeds the set load of the springs 36, 37 (corresponding to 0.5 kgf / cm ² equivalent), the on-off valve 33 starts to move. As the pressure inside the first gas passage 21 rises, the fluid passage 43 of the first regulator valve 40 increases.
When the opening degree of the third gas passage 23 increases, the pressure in the control pressure chamber 38 acting on the piston 34 in the direction against the elasticity of the springs 36 and 37 also increases as the opening degree increases. The compressed air in the second gas passage 22 is introduced from the opening 19 through the orifice 29 provided in the suction passage 12
Therefore, the opening / closing valve 33 is not moved from the position L ₁ very rapidly, and the pressure in the control pressure chamber 38 starts to increase linearly. Next, when the pressure in the second gas passage 22 supplied to the third gas passage 23 exceeds the second set value (0.7 kgf / cm ² ), the valve body 45 of the second reguulator valve 50 is Away from the valve seat 44, the fluid passage 4
3 starts to open, a portion of the compressed air in the second gas passage 22 passes through the orifice 29 of the third gas passage 23 and the fluid passage 43 of the second reguulator valve 50 to open the opening 1.
9 is introduced into the suction passage 12. The position of the opening / closing valve 33 of the unloader 3 when the valve body 45 of the second regulator valve 50 leaves the valve seat 44 is L ₂ . The pressure in the receiver tank 7 exceeds the first set value, and the pressure of the compressed air supplied to the second gas passage 22 through the orifice 28 increases, but the pressure in the fluid passage of the second regulator valve 50 increases. The amount of compressed air introduced into the intake passage 12 through 43 is added to the amount of compressed air introduced into the intake passage 12 through the orifice 29, and the valve body 45 of the second reguulator valve 50 is As the pressure of the compressed air supplied to the third gas passage 23 rises, the opening of the fluid passage 43 is enlarged and the flow rate is gradually increased, so that the opening / closing valve 33 when the valve body 45 fully opens the fluid passage 43. to the position L ₃ of is blunted the pressure increase in the control pressure chamber 38. However, after the valve body 45 of the second regulator valve 50 fully opens the fluid passage 43, the pressure switch PS detects the third set value (8.0 kgf / cm ² ) and the valve body of the switching valve 26. The pressure in the control pressure chamber 38 is rapidly increased until 27 is switched to the second position in which the portion B is in the circulation position. When the position of the opening / closing valve 33 when the pressure switch PS detects the third set value is L ₄ , the pressure in the control pressure chamber 38 between the positions L ₂ and L ₃ of the opening / closing valve 33 is approximately 1. 0 kgf / cm ²
Longitudinal (0.7~1.3kgf / cm ²⁾ in is kept in the position L ₄ of the on-off valve 33, the pressure in the control pressure chamber 38 is approximately from 2.0 kgf / cm ² third set value It is switched to 8.0 kgf / cm ² and the on-off valve 33 is held at the position L ₅ that surely closes the suction port 32.

FIG. 5 is a diagram showing the relationship between the opening (position) of the on-off valve 33 shown in FIG. 4 and the intake air amount ratio of the compressor body 1 by a solid line, and FIG. It is a diagram showing a drive power ratio corresponding to the change in the receiver tank pressure during control by a solid line. Here, the intake air amount ratio is a percentage ratio obtained by dividing the intake air amount during capacity control by the intake air amount when the unloader is fully opened, and the drive power ratio is the power consumption (KW / hr) of the drive motor during capacity control. ) Is divided by the rated power (KW / hr) of the drive motor. As is clear from FIG. 5, the intake air amount ratio is determined by the position L ₁ of the opening / closing valve 33 at the start of the operation of the first regulator valve 40.
To the open / close valve 3 at the start of the operation of the second reguulator valve 50
3 to the position L ₂ changes linearly with a low decrease rate up to about 90%, and from the position L ₂ to the position L ₃ of the opening / closing valve 33 when the second regulator valve 50 is fully opened, it is about 80%.
It gradually decreases to the front and back, and further rapidly decreases from the position L ₃ . However, the intake air amount ratio of 50 to 70% is obtained at the position L ₄ of the opening / closing valve 33 which switches the valve body 27 of the switching valve 26 by detecting the third set value by the pressure switch PS. Therefore, the first set value (7.1 kg
When the capacity control operation by the unloader 3 is started at f / cm ² ), the relationship between the pressure in the control chamber and the opening degree of the on-off valve shown in FIG. 4 is obtained. Since the relationship between the degree and the intake air amount ratio can be obtained, the compressor main body 1 is operated at the rated power of the driving prime mover to discharge the compressed air into the receiver tank 7 that exceeds the first set value to even boosts the pressure in the receiver tank 7 is approximately 7 at the position L ₂ of the on-off valve 33.
5 kgf / cm ² , 7.8 kgf / cm at position L ₃
² , but the intake air amount into the compressor body 1 decreases as shown by the solid line in FIG.
Power consumption is within the rated output of the drive motor, and the drive power ratio during capacity control can be maintained at almost 100% as shown in FIG.

In the present embodiment, the compressor body 1
The consumption of the compressed air in the receiver tank 7 via the consumption-side air pipe 11 rapidly increases during the no-load operation, and the pressure in the receiver tank 7 gradually decreases to the first set value (7.1 k).
When gf / cm ² ) is exceeded, the pressure switch PS detects this and excites the switching valve 26, and the valve body 27 is switched to the first position where the flow position is the portion A. As a result, the control pressure chamber 38 of the unloader 3 is communicated with the suction passage 12 via the second gas passage 22, the switching valve 26, the third gas passage 23 and the opening 19, and the high pressure in the control pressure chamber 38 is increased by the suction passage. 12 is released into the first regu- lator valve 4 at the same time.
The valve body 45 of 0 closes the fluid passage 43 and releases the capacity control operation. When the pressure in the receiver tank 7 exceeds the first set value, the compressor body 1 is brought into the capacity control operation state again. And the pressure in the receiver tank 7 is about 7.5.
When it is ˜7.8 kgf / cm ² , as shown in FIG. 6, the opening / closing valve 33 of the unloader 3 is near the positions L ₂ and L ₃ , and the second regulator valve 50 is in operation. As shown in 5, the pressure in the control pressure chamber 38 is approximately 1.0 kg.
Since there is no drastic change around f / cm ² and no drastic change in the intake air amount ratio around 90-80%,
The operation of the opening / closing valve 33 is slowed down, and even if the compressed air consumption on the consumption side frequently changes before and after the third set value (8.0 kgf / cm ² ) at which the pressure switch PS operates, the opening / closing valve 33 It is possible to maintain the drive power ratio of the compressor at an extremely high state without causing so-called hunting reduction in which 33 frequently opens and closes the suction port 32. If the second regulator valve 50 is not provided in the present embodiment, the pressure in the control pressure chamber 38 of the unloader 3 is controlled along the solid line in FIG. 4 between the positions L _{1 and} L ₂ of the opening / closing valve 33. However, after that, the valve body 4 of the first reguulator valve 40 is
After the state in which the fluid passage 43 is fully opened by the valve 5, the element that slows down the pressure increase in the control pressure chamber 38 is the two fixed orifices 2.
Since there are only 8, 29, the pressure in the control pressure chamber 38 rises rapidly, and when the pressure in the receiver tank 7 is 7.6 kgf / cm ² or lower which is not sufficiently accumulated. The on-off valve 33 will fully close the suction port 32. As a result, the pressure in the pipe on the consumption side is entirely reduced, and when the compressed air is rapidly consumed, the presence of the orifice 29 provided in the third gas passage 23 discharges the pressure in the control pressure chamber 38 of the unloader. The speed is slow, so that there is a delay in opening the on-off valve 33, which causes a problem that the intake of air and the supply of compressed air cannot immediately follow in the compressor body 1. Therefore, in addition to causing a significant decrease in the pressure in the piping on the consumption side, when the consumption of compressed gas is intermittently and frequently performed, the on-off valve causes a so-called hunting phenomenon in which it repeatedly opens and closes,
This will cause a failure in driving the equipment used. On-off valve 33
When the intake port 32 is fully closed, neither suction of air into the compressor body 1 nor discharge of compressed air into the receiver tank 7 is performed. In this case, therefore, the third set value set in the pressure switch PS is set to 8. If the pressure is maintained at 0 kgf / cm ² , the first set value set for the first reguulator valve 40 is 7.
The compressor body 1 has to be set to about 3 kgf / cm ² and the discharge air pressure during full load operation is 7 kgf / cm ^2.
Will be forced to overload. Further, when the pressure in the receiver tank 7 is changed largely and frequently around the third set value due to the consumption of compressed air on the consumption side, the opening / closing valve 33 causes the pressure in the receiver tank 7 to be 7.8 to 8. 0
When the pressure is kgf / cm ² , hunting for opening and closing the suction port 32 is frequently reduced, and the driving power ratio is also inferior.

FIG. 7 is a piping diagram of another embodiment of the capacity control device for the Skrill type air compressor to which the present invention is applied. In this embodiment, the second gas passage 23 is arranged in parallel with the second gas passage 23.
1 is different from the embodiment shown in FIG. 1 only in that the regulator valve 50 and the orifice 29 of FIG. 1 are combined into one regulator valve 60 shown in cross section in FIG. In FIG.
The housing of the reguulator valve 60 comprises two housing halves 61, 62, one housing half 6
2 has a stepped cylindrical shape, and a first opening portion 63 communicating with the switching valve 26 is formed at the end of the small diameter portion along the central axis, and is formed inside the housing half 62. Is
A guide wall 64 connected to the first opening 63 and having a diameter larger than the inner diameter of the opening 63 is coaxially formed.
Connecting inner wall 6 having a diameter larger than the inner diameter of the guide wall 64.
5 is formed coaxially and opens at the end surface of the large diameter portion, and an internal thread 66 is engraved on the inner wall 65. The first
A frusto-conical valve seat 67 is formed on the stepped portion connecting the opening 63 of the cylindrical guide wall 64 and the cylindrical guide wall 64, and a male thread 68 is engraved on the outer circumference of the small diameter portion. The outer half of the other half of the housing 63 has a stepped cylindrical shape, and a male thread 69 to be screwed into the female thread 66 of the connecting inner wall 65 of the housing half 62 is engraved on the outer circumference of the small diameter portion. At the end of the small diameter portion, a bottomed cylindrical guide wall 70 serving as a spring receiver described later is formed along the central axis. A second opening 71 communicating with the opening 39 formed in the housing 31 of the unloader 3 is formed at the end of the large diameter portion along the central axis.
An internal thread 72 is engraved on the inner wall of the opening 71, and the opening 71 and the bottom of the guide wall 70 are communicated with each other by a communication wall 73 having a small diameter.

When a packing 74 is interposed and screwed between the end of the large diameter portion of the housing half 61 and the large diameter portion of the housing 62, the first opening 63 and the second opening 71 are formed.
A fluid passage surrounded by the cylindrical guide wall 64, the connecting inner wall 65 in which the female thread 66 is engraved, the cylindrical guide wall 70, and the small-diameter communication wall 73 is formed between and. Before screwing the two housing halves 61, 62 into the fluid passage, a valve body 75
And the spring 76 are inserted. The valve body 75 has an outer circumference smaller than the inner diameter of the cylindrical guide wall 64 and has a through hole 77.
A cylindrical wall portion penetrating through the skirt, a skirt portion 78 formed of a cylindrical wall having an outer diameter larger than the outer diameter of the cylindrical wall portion and slidable on the guide wall 64, and the through hole 77. Is formed of an end wall 79 that closes the axial end of the cylindrical wall portion that forms the valve wall 80, and a valve portion 80 that seats on the valve seat 67 is formed at the peripheral edge of the end wall 79. The spring 76 has a valve body 75 at one end.
Of the housing half body 6 is brought into contact with the step portion of the boundary portion between the skirt portion 78 and the cylindrical wall portion in which the through hole 77 is formed, and the other end thereof is
The second guide wall 70 and the communication wall 73 are brought into contact with the stepped portion of the boundary portion, and the valve portion 80 of the valve body 75 is connected to the valve seat 6 of the housing half body 61.
The valve body 75 is biased in the direction in which the valve body 75 is seated on the seat 7. The orifice 29 is formed so as to penetrate the end wall 79 of the valve body 65 so as to open in the first opening 63.

According to the present embodiment, the receiver tank 7
The inner pressure is 8.0 kgf, which is the third preset value.
/ Cm ² or less, the electromagnetic three-way switching valve 26 is excited, and when the valve body 27 is in the first position with the circulating position being the A part, the pressure in the receiver tank 7 is predetermined. When the first set value of 7.1 kgf / cm ² is exceeded, the pressure in the first gas passage 21 is supplied to the second gas passage 22 through the first reguulator valve 40 and passes through the orifice 28. The air pressure supplied to the control pressure chamber 37 of the unloader 3 and depressurized by the orifice 28 provided in the second gas passage 22 passes through the branch passage 25 and the switching valve 26 of the second gas passage 22. Then, it reaches the reguulator valve 60. The regulator valve 60 has a first opening 63 communicating with the switching valve 26 and an unloader 3.
The second opening 71 communicating with the opening 39 formed in the housing 31 is communicated by the fluid passage, and the valve body 75 arranged in the fluid passage opens the valve portion 80 by the elasticity of the spring 76. It is seated on the valve seat 67, and the end wall 79 of the valve body 75 has the orifice 29 penetratingly formed so as to connect the first and second openings 63, 71 to each other. While the air pressure supplied to the opening 63 of No. 1 is low, the air pressure supplied to the suction passage 12 from the opening 39 of the housing 31 of the unloader 3 is reduced by the orifice 29 and introduced. However, the air pressure supplied to the first opening 63 of the regulator valve 60 further increases, and the force acting on the end wall 79 of the valve body 75 causes the flow resistance of the orifice 29 and the spring 76.
The second set value (for example, 0.7K) that is determined by the elasticity of
gf / cm ² ) is exceeded, the valve body 75 becomes the spring 76.
The air pressure supplied to the first opening 63 is introduced into the suction passage 12 through the orifice 29 and the gap between the valve portion 80 of the valve body 75 and the valve seat 67. As a result, even in this embodiment, the same operation and effect as those of the embodiment shown in FIG. 1 can be obtained.
Further, in the present embodiment, the pressure in the receiver tank 7 is rapidly reduced due to a rapid increase in the consumption of the compressed air in the receiver tank 7 via the consumption side pipe 11 during the no-load operation of the compressor body 1. The first set value (7.1 Kgf / c
m ² ), which causes the electromagnetic three-way switching valve 26 to move from the second position where the portion B of the valve body 27 is in the circulating position to A
When the operation of the compressor body 1 is switched from the no-load operation to the capacity control operation or the full-load operation by switching to the first position with the section as a circulation position, high-pressure compressed air in the control pressure chamber 38 of the unloader 3 Is introduced into the intake passage 12 through the second gas passage 22, the switching valve 26, the regulator valve 60 and the opening 19. At this time, the valve body 75 of the regulator valve 60 is separated from the valve seat 67 for a short time against the elasticity of the spring 76 by the dynamic pressure of the high-pressure compressed air flowing from the control pressure chamber 38, and the third gas is released. The amount of air flowing through the passage 23 is increased. Therefore, the pressure in the control pressure chamber 38 of the unloader 3 rapidly decreases in the short time, and therefore the opening / closing valve 33 of the unloader 3 closes the suction port 32 when switching from no-load operation to capacity control operation. From the suction port 32 to accelerate the start of sucking air from the suction port 32 into the working chamber 2 of the compressor body 1, so that the pressure in the receiver tank 7 is recovered early and the consumption side pipe 11 The pressure drop can be prevented. Control pressure chamber 3 of unloader 3
If the pressure inside 8 decreases, the valve body 75 of the reguulator valve 60 is seated on the valve seat 67 by the elasticity of the spring 76,
It returns to the state where capacity control operation is possible.

FIG. 9 shows a piping diagram of another embodiment of the capacity control device for a Skrill type air compressor to which the present invention is applied. This embodiment is basically the same as the embodiment shown in FIG. 7, in which the opening 19 through which the third gas passage 23 communicates is a cylinder chamber in which the two springs 36 and 37 of the unloader 3 are housed. The only difference is that the housing 31 is provided so as to communicate with. Therefore, the same parts as those of the embodiment shown in FIG. 7 are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, until the pressure in the receiver tank 7 exceeds the first set value and reaches the second set value, the compressed air that has been depressurized through the first reguulator valve 40 is the regurator valve. 60, the third gas passage 23, and the opening 19 to supply the cylinder chamber of the unloader 3 with the opening 39.
It is introduced into the suction passage 12 through However, the pressure in the receiver tank 7 exceeds the second set value, and the high-pressure compressed air in the first gas passage 21 is supplied into the control pressure chamber 38 via the second gas passage 22 and the opening 30. , After the compressor main body 1 shifts to the no-load operation, when it is detected that the pressure switch PS falls below the first set value due to a rapid increase in consumption of compressed air on the consumption side, the electromagnetic three-way switching valve 26
The high pressure compressed air in the control pressure chamber 38 is
Is supplied to the reguulator valve 60 from the gas passage 22 of the valve body 75, as described in the embodiment shown in FIG.
Are separated from each other in a short time, and a large amount of high-pressure compressed air is temporarily sent out to the third gas passage 23. In this embodiment, the high pressure compressed air is supplied to the third gas passage 23 and the opening 19.
Is supplied to the cylinder chamber via. Therefore, the high pressure of the compressed air supplied to the cylinder chamber temporarily acts on the back surface of the piston 34 and in the same direction as the urging force of the springs 36 and 37, and at the same time, the pressure in the control pressure chamber 38 rapidly decreases. Therefore, the opening / closing valve 33 of the unloader 3 can be rapidly moved from the position where the suction port 32 is closed to the position where the suction port 32 is fully opened during the no-load operation. This movement is shown in FIG.
Compared with the embodiment shown in FIG. 5, the air pressure sent to the third gas passage 23 is accelerated by the amount of acting on the back surface of the piston 34. In the embodiment shown in FIGS. 1 and 7, the piston 3 is used as a moving means of the opening / closing valve 33 in the unloader 3.
4, the unloader 3 is used instead of the piston 34.
It is obvious that even if a diaphragm whose outer peripheral edge is fixed to the housing 31 is used, the same effect can be obtained.

The first preset value (7.1 kgf / cm ² in the embodiment) predetermined in the present invention is
It is determined by the discharge pressure (7.0 kgf / cm ² in the embodiment) during full load operation of the compressor body, and is a predetermined pressure value that is the same as or slightly higher than the discharge pressure. Further, the third set value is a pressure determined as a maximum value for accumulating in the receiver tank depending on the property and use of the compressed gas, and is generally used as a compressor for supplying compressed air to pneumatic equipment using compressed air as a power source. Is 1 to 2 k from the first set value in consideration of the pressure drop in the pipe to the pneumatic equipment.
Pressure value higher by gf / cm ² (8.0 in the example)
(kgf / cm ² ). The second set value determined in advance in the present invention is a pressure value determined by the circuit configuration including the first regurator valve and the unloader. In the embodiment of the present invention, the configuration in which the piston of the unloader is operated at a high discharge pressure (7.0 kgf / cm ² ) of the compressor is avoided, and an orifice is provided between the first reguulator valve and the control pressure chamber of the unloader. In order to reduce the pressure supplied to the control pressure chamber due to the above, the value is 0.7 kgf / cm ² in the embodiment, but this set value is naturally a value different depending on the configurations of the orifice and the unloader. At the time when the second regulator valve starts operating, the gas pressure existing between the check valve on the discharge side of the compressor body, the receiver tank, and the first regulator valve is set to the first set value. And a third set value, it should be understood as a predetermined pressure value supplied to the third gas passage at that time.

[0023]

According to the present invention, the on-off valve moving means fixed to the on-off valve of the unloader uses the gas pressure supplied into the control pressure chamber and the elastic force of the spring for urging the on-off valve in the opening direction. A second gas passage communicating with the control pressure chamber of the unloader, the first gas communicating with a receiver tank via a first regulator valve. Connected to the aisle,
In the first gas passage, the first regulator valve does not open the fluid passage of the regulator valve until the gas pressure in the first gas passage exceeds a first preset value. When the gas pressure of is less than the first set value, the unloader holds the opening / closing valve of the gas intake port at the fully opened position by the urging force of the spring, and the compressor body is operated at full load by the prime mover. . When the pressure of the compressed gas pressure from the check valve provided on the discharge side of the compressor body to the first gas passage through the receiver tank exceeds the first preset value, the first To open the fluid passage of the regulator valve to supply pressure to the control pressure chamber of the unloader,
The on-off valve is moved according to the supplied pressure, and the capacity control operation is started. At this time, a part of the compressed air that has passed through the first regulator valve is introduced into the suction passage on the working chamber side of the compressor body from the suction port through the switching valve and the third gas passage. The third gas passage is provided with an orifice, which is provided with a predetermined fixed fluid passage. Therefore, by introducing a part of the compressed air into the suction passage through the orifice, a control pressure chamber of the unloader is provided. The pressure rise can be slowed.

When the compressed gas in the first gas passage 21 further increases from this state, the pressure in the second gas passage also increases in accordance with the increase in the pressure. When this pressure exceeds the second set value, the fluid passage of the second regulator valve is opened, and the compressed gas is sucked from the suction port of the unloader to the compressor main body side together with the orifice provided in parallel with the regulator valve. It will be introduced into the passage. The second reguulator valve increases the amount of compressed gas introduced into the suction passage on the compressor body side from the suction port of the unloader as the pressure supplied to the third gas passage via the switching valve increases, and during this period. The pressure increase in the control pressure chamber of the unloader is slowed down regardless of the increase in the gas pressure in the first gas passage. But the second
When the amount of compressed gas passing through the regulator valve reaches the maximum amount allowed by the configuration of the regulator valve, the pressure in the control pressure chamber of the unloader also rises as the pressure in the first gas passage increases. Then, it is detected that the gas pressure existing between the check valve on the discharge side of the compressor main body, the receiver tank and the first gas passage exceeds the third preset value by the pressure switch. And the switching valve is switched from the first position to the second position, and the pressure of the first gas passage is directly supplied to the control pressure chamber of the unloader via the second gas passage without passing through the first regulator valve. Then, since the third gas passage is shut off, the opening / closing valve moving means of the unloader moves the opening / closing valve to the position where the suction port is completely closed, and shifts the compressor to the no-load operation. Therefore, the pressure in the first gas passage exceeds a predetermined first value,
After the first reguulator valve opens the fluid passage,
The capacity control operation of the compressor main body until the gas pressure exceeds a predetermined third value is determined by the gas existing between the check valve on the discharge side of the compressor main body, the receiver tank, and the first passage. The pressure is set to the first set value (7.1 k in the embodiment).
gf / cm ² ) and the third set value (8.0 kgf / cm ² in the embodiment) can be reliably maintained.

As is clear from the above description, when the first set value existing between the check valve on the discharge side of the compressor body, the receiver tank, and the first gas passage is exceeded, In response to this increase in gas pressure, the on-off valve moving means of the unloader continuously moves the on-off valve from the position where the suction port is fully opened to the position where it is fully closed to control the amount of gas suctioned. As a result, the compressor main body performs a capacity control operation in which the amount of intake gas is controlled steplessly.Therefore, when the amount of compressed gas consumed on the consumption side of the compressor fluctuates, it responds to changes in the gas pressure. The opening / closing valve moving means of the unloader adjusts the opening degree of the intake port by the opening / closing valve, and discharges the compressed gas amount according to the consumption amount to the receiver tank. When a large fluctuation occurs in the consumption amount of the compressed gas on the consumption side during the no-load operation of the compressor body, between the check valve on the discharge side of the compressor body, the receiver tank, and the first gas passage. When the pressure switch detects that the existing gas pressure has dropped below the first set value, the switching valve is switched from the second position to the first position, and the compressor body shifts to capacity control operation. When the consumption amount of the compressed gas on the consumption side falls below the amount of compressed gas discharged from the compressor body to the receiver tank and it is detected that the pressure switch exceeds the third set value, the switching valve moves from the first position. The no-load operation of the compressor is started again after switching to the second position. However, during the capacity control operation of the compressor body and the operation of the second regulator valve, the second and third operations are performed. In accordance with an increase in the gas pressure supplied to the passage of the unloader, the amount of gas introduced from the suction port of the unloader into the suction passage on the working chamber side of the compressor body increases through the third gas passage. The pressure in the control pressure chamber does not increase as much as the pressure of the compressed gas supplied to the second gas passage increases, and accordingly, the inlet port of the unloader is not closed rapidly by the opening / closing valve. Fluctuations in compressed gas consumption The open / close valve can prevent the occurrence of the so-called hunting phenomenon of the open / close valve, which frequently opens and closes the suction port, and between the check valve on the discharge side of the compressor body, the receiver tank, and the first gas passage. The pressure of the compressor gas existing in the compressor is set to be equal to or slightly higher than the rated discharge pressure of the compressor body under full load operation.
After exceeding the set value of, the opening of the opening / closing valve that controls the intake port of the unloader is controlled steplessly so that the driving power of the compressor stays within the rated output of the driving prime mover. When the third set value, which is set to a value about 1 kgf / cm ² higher than the rated discharge pressure, is reached, the intake port of the unloader can be completely blocked by the on-off valve, and then the no-load operation can be performed. Even if the compressed gas is consumed intermittently and frequently on the consumer side, it is possible to minimize the pressure drop in the consumer side pipe and the pressure fluctuation range, and drive the compressor to its rated output during full load operation. The prime mover can be used to drive the compressor body with high power efficiency, and stable operation control of the compressor body and the drive prime mover can be performed.

[Brief description of drawings]

FIG. 1 is a piping diagram according to an embodiment of the present invention.

FIG. 2 is a sectional view of the unloader.

FIG. 3 is a sectional view of the reguulator valve.

FIG. 4 is a diagram showing the relationship between the pressure in the control pressure chamber and the opening degree of the on-off valve.

FIG. 5 is a diagram showing a relationship between an opening degree of an opening / closing valve and an intake air amount ratio.

FIG. 6 is a diagram showing the relationship between the pressure in the receiver tank and the drive power ratio of the compressor during capacity control.

FIG. 7 is a piping diagram according to another embodiment of the present invention.

FIG. 8 is a sectional view of the reguulator valve.

FIG. 9 is a piping diagram in another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor body 2 Compressor working chamber 3 Unloader 21 First gas passage 22 Second gas passage 23 Third gas passage 26 Switching valve 28,29 Orifice 32 Suction port 33 Opening valve 36,37 Spring 38 Control pressure Chamber 40, 50, 60 Regulator valve

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[Procedure amendment]

[Submission date] October 2, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

In the present embodiment, the compressor body 1
The consumption of the compressed air in the receiver tank 7 via the consumption-side air pipe 11 rapidly increases during the no-load operation, and the pressure in the receiver tank 7 gradually decreases to the first set value (7.1 k).
When gf / cm ² ) is exceeded, the pressure switch PS detects this and excites the switching valve 26, and the valve body 27 is switched to the first position where the flow position is the A portion. As a result, the control pressure chamber 38 of the unloader 3 is moved to the second gas passage 22,
The high pressure in the control pressure chamber 38 is released into the suction passage 12 while being communicated with the suction passage 12 through the switching valve 26, the third gas passage 23, and the opening 19, and at the same time, the valve body of the first regulator valve 40. 45 closes the fluid passage 43 and releases the capacity control operation. When the pressure in the receiver tank 7 exceeds the first set value, the compressor body 1 is brought into the capacity control operation state again. The pressure in the receiver tank 7 is almost 7.
5-7. At 8 kgf / cm ² , as shown in FIG. 6, the opening / closing valve 33 of the unloader 3 is located near the positions L ₂ and L ₃ , and the second regulator valve 50 is in operation, as shown in FIGS. 4 and 5. Thus, the pressure in the control pressure chamber 38 is almost 1.
Since there is no drastic change around 0 kgf / cm ² and no drastic change in the intake air amount ratio around 90-80%, the operation of the on-off valve 33 is slowed down, and the third pressure switch PS operates. Set value of (8.0 kgf / c
Even if the compressed air consumption on the consumption side frequently changes before and after m ² ), the so-called hunting phenomenon in which the opening / closing valve 33 frequently opens and closes the suction port 32 does not occur, and the driving power ratio of the compressor is extremely high. Can be kept high. For example, in the present embodiment, the second regulator valve 50
If not provided, the control pressure chamber 3 of the unloader 3
The pressure in the valve 8 is controlled along the solid line in FIG. 4 between the positions L _{1 and} L ₂ of the opening / closing valve 33, but thereafter, after the valve body 45 of the first regulator valve 40 fully opens the fluid passage 43. Since there are only two fixed orifices 28 and 29 as elements for slowing down the pressure rise in the control pressure chamber 38, the control pressure chamber 3
The pressure in 8 rises rapidly and the pressure in the receiver tank 7 is not yet sufficiently accumulated at 7.6 kgf / cm.
When the pressure is ² or lower, the on-off valve 33 will completely close the suction port 32. As a result, the pressure in the pipe on the consumption side is entirely reduced, and when the compressed air is rapidly consumed, the presence of the orifice 29 provided in the third gas passage 23 discharges the pressure in the control pressure chamber 38 of the unloader. The speed is slow, so that there is a delay in opening the on-off valve 33, which causes a problem that the intake of air and the supply of compressed air cannot immediately follow in the compressor body 1. Therefore, in addition to causing a large decrease in the pressure inside the piping on the consumption side, when the compressed gas is consumed intermittently and frequently, the on-off valve causes a so-called hunting phenomenon in which it repeatedly opens and closes, and drives the equipment used. There will be obstacles. When the on-off valve 33 fully closes the suction port 32, the compressor body 1
Since neither intake of air into the receiver tank 7 nor discharge of compressed air into the receiver tank 7 is performed, in this case, if the third set value set in the pressure switch PS is maintained at 8.0 kgf / cm ² , First set on the reguulator valve 40
Setting the inevitable to set to about 7.3kgf / cm ^2, discharge pressure at full load operation is forcing the overload operation the compressor body 1 is 7 kgf / cm ^2. Further, when the pressure in the receiver tank 7 is changed largely and frequently around the third set value due to the consumption of compressed air on the consumption side, the opening / closing valve 33 causes the pressure in the receiver tank 7 to be 7.8 to 8. Frequent suction port 32 at 0 kgf / cm ²
As a result, hunting for opening and closing is reduced, and the drive power ratio becomes inferior.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

FIG. 9 shows a piping diagram of another embodiment of the capacity control device for a Skrill type air compressor to which the present invention is applied. This embodiment is basically the same as the embodiment shown in FIG. 7, in which the opening 19 through which the third gas passage 23 communicates is a cylinder chamber in which the two springs 36 and 37 of the unloader 3 are housed. The only difference is that the housing 31 is provided so as to communicate with. Therefore, the same parts as those of the embodiment shown in FIG. 7 are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, until the pressure in the receiver tank 7 exceeds the first set value and reaches the third set value, the compressed air whose pressure has been reduced through the first reguulator valve 40 is the reguulator valve. 60, the third gas passage 23, and the opening 19 to supply the cylinder chamber of the unloader 3 with the opening 39.
It is introduced into the suction passage 12 through However, the pressure in the receiver tank 7 exceeds the third set value, and the high-pressure compressed air in the first gas passage 21 is supplied into the control pressure chamber 38 via the second gas passage 22 and the opening 30. , After the compressor main body 1 shifts to the no-load operation, when it is detected that the pressure switch PS falls below the first set value due to a rapid increase in consumption of compressed air on the consumption side, the electromagnetic three-way switching valve 26
The high pressure compressed air in the control pressure chamber 38 is
Is supplied to the reguulator valve 60 from the gas passage 22 of the valve body 75, as described in the embodiment shown in FIG.
Are separated from each other in a short time, and a large amount of high-pressure compressed air is temporarily sent out to the third gas passage 23. In this embodiment, the high pressure compressed air is supplied to the third gas passage 23 and the opening 19.
Is supplied to the cylinder chamber via. Therefore, the high pressure of the compressed air supplied to the cylinder chamber temporarily acts on the back surface of the piston 34 and in the same direction as the urging force of the springs 36 and 37, and at the same time, the pressure in the control pressure chamber 38 rapidly decreases. Therefore, the opening / closing valve 33 of the unloader 3 can be rapidly moved from the position where the suction port 32 is closed to the position where the suction port 32 is fully opened during the no-load operation. This movement is shown in FIG.
Compared with the embodiment shown in FIG. 5, the air pressure sent to the third gas passage 23 is accelerated by the amount of acting on the back surface of the piston 34. In the embodiment shown in FIGS. 1 and 7, the piston 3 is used as a moving means of the opening / closing valve 33 in the unloader 3.
4, the unloader 3 is used instead of the piston 34.
It is obvious that even if a diaphragm whose outer peripheral edge is fixed to the housing 31 is used, the same effect can be obtained.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

As is clear from the above description, the gas pressure existing between the check valve on the discharge side of the compressor body, the receiver tank and the first gas passage exceeds the first set value. When the gas pressure increases, the on-off valve moving means of the unloader continuously moves the on-off valve from the position where the intake port is fully opened to the position where it is fully closed to control the gas intake amount. To do. As a result, the compressor body performs capacity control operation in which the amount of intake gas is controlled steplessly,
When the amount of compressed gas consumed on the consumer side of the compressor fluctuates, the on-off valve moving means of the unloader adjusts the opening of the suction port by the on-off valve in response to the change in the gas pressure to reduce the consumption amount. The corresponding compressed gas amount is discharged to the receiver tank. When a large fluctuation occurs in the consumption amount of the compressed gas on the consumption side during the no-load operation of the compressor body, between the check valve on the discharge side of the compressor body, the receiver tank, and the first gas passage. When the pressure switch detects that the existing gas pressure has dropped below the first set value, the switching valve moves from the second position to the first position.
Is switched to the position of, and the compressor main body shifts to capacity control operation. When the consumption amount of the compressed gas on the consumption side falls below the amount of compressed gas discharged from the compressor body to the receiver tank and it is detected that the pressure switch exceeds the third set value, the switching valve moves from the first position. The no-load operation of the compressor is started again after switching to the second position. However, during the capacity control operation of the compressor body and the operation of the second regulator valve, the second and third operations are performed. In accordance with an increase in the gas pressure supplied to the passage of the unloader, the amount of gas introduced from the suction port of the unloader into the suction passage on the working chamber side of the compressor body increases through the third gas passage. The pressure in the control pressure chamber does not increase as much as the pressure of the compressed gas supplied to the second gas passage increases, and accordingly, the inlet port of the unloader is not closed rapidly by the opening / closing valve. Fluctuations in compressed gas consumption The open / close valve can prevent the occurrence of the so-called hunting phenomenon of the open / close valve, which frequently opens and closes the suction port, and between the check valve on the discharge side of the compressor body, the receiver tank, and the first gas passage. After the pressure of the compressed gas existing in the compressor exceeds the first set value which is the same as or slightly higher than the rated discharge pressure in the full load operating state of the compressor, the drive power of the compressor is driven. The opening that controls the inlet and outlet of the unloader is controlled steplessly so that it stays within the rated output of the prime mover, and the third discharge is set to a value higher than the rated discharge pressure of the compressor body by about 1 kgf / cm ² . When the set value is reached, the intake port of the unloader can be completely closed by the on-off valve, and then the operation can shift to no-load operation, so even if the consumption of compressed gas on the consuming side is intermittent and frequent. It is possible to minimize the pressure drop in the piping on the consumption side and the pressure fluctuation range, and to drive the compressor body with high power efficiency by using the drive prime mover that provides the rated output during full load operation of the compressor body. The stable operation control of the compressor body and the driving prime mover can be performed.

Claims (3)

[Claims] 1. A compressor body, and an unloader for controlling a flow rate of gas sucked into an operation chamber of the compressor body by an opening / closing valve opening and closing an intake port in response to a gas pressure introduced into a control pressure chamber, A compressor provided with a receiver tank that communicates with a discharge side of the working chamber via a check valve and stores discharged compressed gas, wherein the compressor is fixed to an opening / closing valve of the unloader and is supplied to the control pressure chamber. Opening / closing valve moving means for moving the opening / closing valve steplessly by the gas pressure and the elastic force of the spring for urging the opening / closing valve in the opening direction, the first gas passage communicating with the receiver tank, and the unloader. A second gas passage communicating with the control pressure chamber is connected to the first gas passage to open the fluid passage when the gas pressure in the first gas passage exceeds a predetermined first set value. Gas pressure from the gas passage to the second gas passage A first reguulator valve for supplying, a third gas passage communicating with an intake passage on the working chamber side of the compressor body from the intake port of the unloader, the second gas passage, and the first gas passage. A first position for connecting the valve body to the second gas passage and the third gas passage, and a second position for connecting the second gas passage to the first gas passage. And a switching valve for selectively switching, and a fluid passage provided in the third gas passage when the gas pressure supplied through the switching valve exceeds a predetermined second set value. A second regulator valve that opens and introduces the gas in the third gas passage from the suction port of the unloader into the suction passage on the working chamber side of the compressor body, and the third regulator valve in parallel with the second regulator valve. Is equipped with a predetermined fixed fluid passage provided in the gas passage of And a pressure switch for detecting the gas pressure existing between the check valve on the discharge side of the compressor body and the receiver gas through the receiver tank to the first gas passage.
When the pressure falls below the first set value, the changeover valve is moved from the second position when the pressure falls below the first set value. A capacity control device for a compressor, comprising: switching means for switching to a first position. 2. The second reguulator valve comprises:
The capacity control device for a compressor according to claim 1, wherein the set value of is adjustable. 3. A second reguulator valve provided in the third gas passage, and a first opening communicating with the switching valve,
A housing having a second opening communicating with the suction passage on the working chamber side of the compressor body from the suction port of the unloader;
A fluid passage formed in the housing to connect the first opening and the second opening, and a spring disposed in the fluid passage for closing the first opening with a spring. 2. The orifice is a hole formed in the valve body for allowing the first opening and the second opening to communicate with each other at all times.
A capacity control device in the compressor according to.