JPH0116344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suction adjustment device for adjusting the intake air amount of a compressor, and particularly to a suction adjustment device for an oil-cooled screw compressor.

[Conventional technology]

The discharge amount of the compressor is determined according to the amount of air used, but if the compressor is operated as it is when no air is used, compressed air will be continuously pumped out and the discharge pressure will rise excessively, which is dangerous. It is. For this reason, a suction adjustment device is used in the compressor to adjust the amount of suction air depending on the degree to which the discharged air is used.

As a compressor with a suction duct closing type suction adjustment device, it has been registered as a German utility model.
7811860 etc. are known. Such a suction adjustment device is equipped with a suction duct closing member at the end of the piston, and when the compressor is started, this closing member is pushed into the suction duct open position by the piston being biased by a spring. .
When the compressor is in operation, for example, the switch-off pressure is reached and compressed air is applied to the piston from the pneumatic rip-out regulator.
The closing member has a piston that is pushed into the suction duct closing position against the elastic force of the spring. However, such a suction adjustment device can only perform so-called opening/closing control of fully opening or closing the suction duct using the closing member, and cannot suction air according to the request of the compressor. Additionally, when the switch-off pressure is not reached during startup, complicated operations are required, such as manually closing the intake duct blocking member and opening the manual release valve to reduce the pressure in the cylinder and reduce the load on the compressor. . For this reason, there was a risk that erroneous operation would cause oil lock or abnormally high temperatures to occur within the cylinder, thereby damaging the compressor.

Therefore, recently, when the compressor is started, it is biased by a spring or the like to close the suction duct, but during operation, the suction duct is opened by applying operating pressure in the direction opposite to the direction of the bias by the spring or the like. A suction adjustment device is used which is equipped with a closing member having such a structure and is capable of performing so-called proportional control in which the closing member is held at an intermediate position of the suction duct and the adjustment operation is performed according to the request of the compressor.

[Problem that the invention seeks to solve]

However, according to such conventional suction adjustment devices, proportional control is performed by making the pressure on the compressor side applied in the direction of opening the suction duct opposed to the elastic force of the spring applied in the direction of closing the suction duct, so it is difficult to balance. There is a problem in that it is difficult to perform accurate and detailed control. Furthermore, if the operating pressure applied in the direction opposite to the biasing direction of the spring, etc. is greater than the elastic force of the spring, etc., the closing member will be in the fully open position of the suction duct, and the amount of air suction will be reduced. There is a problem in that it is not possible to make fine adjustments according to the needs of the compressor. Furthermore, in the case of an oil-injected compressor, when the compressor is switched off, operating pressure is still present in the oil reservoir. Therefore, at this time, there is a risk that the oil in the oil storage tank may flow into the suction duct due to the operating pressure, and a special check valve or non-return valve has conventionally been required to prevent this.

The present invention was developed in view of these conventional difficulties, and although it has a simple structure, it allows fine adjustment of the amount of air intake, and also allows oil to flow from the oil storage tank into the intake duct. The object of the present invention is to provide a compressor suction adjustment device that can appropriately prevent inflow.

[Means for solving problems]

For this reason, the present invention provides a cylinder provided with one end closed and the other end opened toward the suction duct, a piston slidably provided within the cylinder, and an end portion of the piston. A closing member for closing the suction duct provided in A first pressure supply line for applying pressure to the pressure area on one end of the piston to cause the piston to slide in the direction of opening the suction duct, and a first pressure supply line for applying supply system pressure on the consumption side to the pressure area on the other end of the piston to cause the piston to slide in the direction of closing the suction duct. a second pressure supply line for applying to the pressure region;
A ventilation passage communicates the suction duct with the first pressure supply line at the piston position where the suction duct is closed, and one end is open to the pressure area in order to communicate the pressure area on the other end of the piston to the suction side of the compressor. Its basic feature is that it consists of small diameter through holes.

[Effect]

Before starting the compressor, the piston of the closing member is biased by a spring to the suction duct closing position. When the compressor is started and operating pressure is generated, this operating pressure is supplied to the pressure area on one end side of the piston (the pressure area where pressure in the suction duct opening direction is applied) via the first pressure supply line. As a result, the piston is pushed in the suction duct opening direction against the elastic force of the spring, and the operating pressure overwhelms the spring, so that the closing member is brought to a position where the suction duct is fully opened.

In addition, to close the suction duct, the supply system pressure on the consumption side of the compressor is used as a control pressure in the pressure area on the other end side of the piston (the pressure area where the pressure in the suction duct closing direction is applied) via the second pressure supply line.
supply to. In this case, the supply system pressure is applied in the biasing direction of the spring, and the piston is pushed back toward the suction duct against the operating pressure, so that the suction duct is closed by the closing member.

Here, the supply system pressure on the consumption side as mentioned above is
By applying pressure to the piston in the suction duct closing direction via the second pressure supply line, proportional control of the opening degree of the suction duct becomes possible. In other words, by applying supply system pressure in this way,
The closing member can be located at an intermediate position between fully open and fully closed depending on the magnitude of the supply system pressure.

When the compressor is switched off, there is still operating pressure in the reservoir, but the switch-off moves the piston to a position that closes off the suction duct, thus opening the ventilation passage between the suction duct and the first pressure supply line. communicate with. Therefore, the compressed air in the oil storage tank through which the first pressure supply line communicates is ventilated into the suction duct through the ventilation passage.

Furthermore, when the compressor is started, air in the pressure area is drawn into the suction side of the compressor through the small diameter through hole opened in the pressure area on the other end of the piston. In cooperation with the operation pressure, the suction duct can be opened quickly when the compressor is started.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2.

The suction adjustment device of the present invention is installed in a boss 1 of a housing wall 2 of a compressor, and includes a cylinder 5 fitted in the boss of the housing wall, and a piston 6 slidably provided in the cylinder. , a suction duct closing member 9 provided at the end of the piston, a spring 15 that urges the piston in the direction of closing the suction duct, and a first spring 15 that applies pressure to the piston in the direction of opening the suction duct.
, and a second pressure supply line Y for applying pressure to the piston in the direction of closing the suction duct. Note that there is another housing wall 3 on the opposite side of the housing wall 2, and this housing wall 3 has an intake duct 4.
is provided opposite the suction adjustment device. The suction duct 4 may be surrounded by an air filter cartridge (not shown). The space between the housing walls 2 and 3 opens directly into the compressor suction opening.

The cylinder 5 is fitted into the boss 1 of the housing wall 2, and one end is closed by contacting the housing wall 2, and the other end is open to the suction duct side. Note that the closed end of the cylinder 5 has an annular shoulder portion 25, and a sealing ring (not shown) is attached to this annular shoulder portion 25, and is pressurized by a pressure supply line described below. The cylinder space (pressure area) is made leak-free.

The piston 6 is slidably provided within the cylinder 5. One end of the piston has a threaded structure, and holds a closing member 9, which will be described later. A recess 7 is provided at the other end of the piston (on the housing wall side), and constitutes a pressure region 7 that receives pressure in the suction duct closing direction. Also, piston 6
By reducing the diameter from the middle part of the main body, an annular surface 20 facing toward the suction duct is provided, and constitutes a pressure region A that receives operating pressure in the direction of opening the suction duct.

The closing member 9 is generally pot-shaped as a whole, and is screwed onto one end of the piston 6 and held therein. The closing member 9 includes an annular surface 20 that can come into contact with the seat surface 11 of the suction duct 4 . A sealing ring 10 is fitted on the annular surface,
When the sealing ring 10 is in the position where the suction duct 4 is closed, it is positioned on the seat surface 11 of the suction duct to prevent leakage. The closure member 9 has a cylindrical portion 12, and the longitudinal dimension of the closure member 9 is designed to be somewhat longer than the length of its stroke. The closure member 9 is guided on the outer circumference of the cylinder 5 by a cylindrical part 12 and has a seal in an annular groove 13 at the end of the cylindrical part 12 and on the circumferential surface of the cylinder 5. to slide.

The spring 15 has one end supported in contact with the housing wall 2, and the other end supported in contact with the recess 7 of the piston 6, so that the spring 15 can bias the piston 6 in the suction duct closing direction.

The first pressure supply line It consists of a perforation 21, an annular groove 22 provided from the perforation 21 in the circumferential direction of the cylinder body, and perforations 23 provided radially from the annular groove 22 and communicating with the pressure region A of the annular surface. The operating pressure of the compressor is supplied to the pressure region A of the annular surface via this first pressure supply line X. Note that the supply pipe 24 is connected to the pressure side of the compressor (for example, an oil storage tank), so that the pressure (operating pressure) directly generated by the compressor can be supplied to the pressure region A. Further, the annular groove 22 is covered with a bush 5' to prevent leakage, and the outer periphery of the bush 5' serves as a guide surface for the closing member 9.

The second pressure supply line Y is formed by connecting a supply pipe 16 for the supply system pressure of the compressor to a through hole 32 communicating with the pressure region B in the cylinder, and the supply pressure of the compressor is determined by this second pressure supply line Y. is supplied to pressure region B via pressure supply line Y of . The supply pipe 16 is connected to the downstream side of a check valve or the downstream side of a pressure holding valve attached to the pressure supply system of the compressor, and supplies supply pressure to the pressure region RO. Note that the regulator known as a proportional regulator is 1
Illustrated at position 7.

The pressure region A of the annular surface of the piston is designed so that the piston 6 can be slid in the suction duct opening direction against the elastic force of the spring even with a low operating pressure. In this case, it is preferable to design the elastic force of the spring 15 to correspond to the pressure on the pressure area of the piston. Also,
For example, the pressure area (b) of the piston recess may be designed to be twice the pressure area (a) of the piston annular surface. Depending on the design of the spring 15, it is possible to set the ratio of pressure regions A and B to other values, but the pressure region B, which receives pressure in the suction duct closing direction, is higher than the pressure region B, which receives pressure in the suction duct opening direction. It is advantageous to make it larger.

Further, the housing wall 2 is provided with a small diameter through hole 28 whose one end opens into the pressure region.
This small diameter through hole 28 is connected to the suction side of the compressor so that air in the cylinder space forming the pressure area can be sucked into the suction side of the compressor. The other end of this small-diameter through hole 28 can be opened, for example, in the space between the housing walls 2 and 3.

Magnetic valve 18 as shown by the dashed line
and/or a pneumatic valve 19 may also be connected to the supply line 16. By doing so, a control pressure can be applied to the piston 6 to close the suction duct 4 using a pneumatic or electric control system.

Further, a ventilation opening 14 is formed in the closing member 9. This ventilation opening 14 is designed to equalize the pressure on both sides of the closure member 9. In addition,
This ventilation opening 14 connects between the suction duct and the cavity, which cavity is arranged between the closure member 9 and the cylinder 5 when the closure member 9 is in the closed position.

The suction adjustment device of this embodiment also includes a ventilation passage Z for releasing the operating pressure (compressed air) working in the oil storage tank into the suction duct 4 when the compressor is stopped.

The ventilation passage Z includes a perforation 27 provided in the radial direction of the cylinder body from the annular groove 22, a perforation 29 provided in the radial direction in the middle part of the piston body, and a perforation 29 provided in the longitudinal direction of the piston body from this perforation. and a perforation 26 that opens into the suction duct, and the perforation 27 and the perforation 29 communicate with each other when the closing member 19 is in the suction duct closing position, and the perforation 27 constitutes the first pressure supply line X. It is designed to communicate with the suction duct 4.

In addition, in the figure, 30 is a cutoff valve of the supply pipe 16. The design structure can be transformed into various shapes. For example, the piston bore 26 can be omitted or a compatible restriction means can be inserted at the tip of the closure member 9.

The suction regulator can be controlled from three different points (proportional regulator 17, magnetic valve 18, pneumatic valve 19). Therefore, proportional control or opening/closing control can be performed from the electric system side or the air control system side.

Next, the operation of the suction adjustment device of this embodiment will be explained.

When the compressor is switched off, the closing member 9 closes off the suction duct 4 under the action of the spring 15. Supply piping 16 is connected to valve 1
It is connected to the atmosphere through one of the ports 8 and 19. In addition, the operating pressure supply side of the compressor (usually the oil storage tank side) is also connected to the supply pipe 24 and the perforations 21, 27,
It is connected to the atmosphere through 29 and 26.

When the compressor switch is turned on, piston 6
The operating pressure acting in pressure region A is accumulated, while at the same time air in pressure region B is gradually sucked in through a small diameter through hole 28 leading to the suction side of the compressor. Therefore, when the compressor starts moving, the piston 6 is displaced to the left to some extent. At the same time, the connection between the boreholes 26 and 27 is severed, thus cutting off communication between the compressor pressure side and the atmosphere. The piston 6 can be pushed into the fully open position (FIG. 2) with a supply pressure (operating pressure) of about 1 atmosphere.

When the suction duct 4 of the compressor is closed, the compressor supply system pressure is supplied to the pressure region L of the piston recess via the second pressure supply line Y (supply piping 16, through hole 32). In this case, the supply pressure is applied in the biasing direction of the spring 15, and the piston 6 is pushed back toward the suction duct against the operating pressure, so the suction duct 4 is closed by the closing member 9.

If the suction regulator is operated with infinitely variable adjustment, the supply line 16 is connected to the pressure supply system via a proportional regulator. Since the pressure area B of the piston 6 that receives the supply pressure is larger than the annular surface 20 of the pressure area A, the suction regulator has a pressure smaller than "supply pressure - spring pressure".
It remains open as long as it is acting downstream of 7. When the pressure on the downstream side of the proportional regulator 17 approaches "supply pressure - spring pressure", the piston 6 begins to move to the right. In the operating mode described above, the suction regulator begins to close the suction duct 4 when the pressure in the supply system reaches 6 atmospheres, for a final pressure of 7 atmospheres. In the case of regulating operation, when the pressure in the supply system drops again, the suction regulating device opens automatically accordingly.

In this way, by supplying the control pressure to the pressure region B through the proportional regulator 17 via the second pressure supply line Y and making proportional adjustments, the closing member 9 can be adjusted to the suction duct 4 between fully closed and fully opened. Can be held in position.

If the compressor is to be operated in another manner, the supply line 16 may be connected to the atmosphere through either valve 18 or 19. By doing so, the suction regulator is maintained in the fully open position during compressor operation as shown. When an electric or pneumatic control system is used, a control pressure (supply system pressure) for quickly closing the suction duct 4 is applied to pressure region RO through either valve 18 or 19. Advantageously, the pressure of the supply system is used as control pressure. In the case of such continuous operation, the suction duct 4 is simply opened and closed without placing the closing member 9 in an intermediate position as in the adjustment operation.

Furthermore, since the closing member 9 is provided with ventilation openings 14, destructive forces that may occur in the closing member 9 during the stroke movement of the piston 6 can be substantially eliminated.

Further, when the closing member 9 is in the position to close the suction duct 4, the perforations 27 provided radially from the annular groove 22 of the cylinder body communicate with the perforations 29 and 26 of the piston body that open into the suction duct 4. For this purpose, the compressed air working in the oil tank is ventilated into the suction duct 4 via the ventilation passage 2 when the compressor is switched off.

Furthermore, when the compressor is started, air in the pressure area B is drawn into the suction side of the compressor through the small diameter through hole 28 opened in the pressure area B on the other end of the piston, and therefore the first pressure supply line In cooperation with the operation pressure from X, the suction duct 4 is quickly opened when the compressor is started.

〔Effect of the invention〕

According to the suction adjustment device of the present invention described above, the structure is simple and the following effects can be obtained.

The supply system pressure of the compressor can also be applied in the suction duct closing direction to the piston, where the elastic force of the spring is acting in the suction duct closing direction, so the supply system pressure can be used as a control pressure and suction can be performed when necessary. The duct can be opened and closed arbitrarily and quickly.

Furthermore, by using the supply system pressure of the compressor, proportional control of the opening degree of the suction duct can be easily performed, and the amount of air intake can be finely adjusted in accordance with requests from the compressor side.

In addition, when the blocking member is in a position to block the suction duct, the compressed air in the oil storage tank is ventilated into the suction duct via the ventilation passage, so there is no need to use a special valve that is conventionally used. , it is possible to appropriately prevent oil in the oil storage tank from flowing into the suction duct.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the suction adjustment device of the present invention. Figure 1 is a longitudinal sectional view showing the suction duct in a closed state, and Figure 2 shows the suction duct in an open state. FIG. In the figure, 5 is a cylinder, 6 is a piston, and 9 is a cylinder.
15 is a closing member, 15 is a spring, 28 is a small diameter through hole, X is a first pressure supply line, Y is a second pressure supply line, A and B are pressure areas, and Z is a ventilation passage.

Claims (1)

[Claims] 1. A cylinder provided with one end closed and the other end opened toward the suction duct, and a piston slidably provided within the cylinder;
A closing member for closing the suction duct provided at the end of the piston, a spring that biases the piston in a direction in which the closing member closes the suction duct, and an operating pressure generated by the compressor that is applied to the piston by the elasticity of the spring. A first pressure supply line for applying pressure to a pressure region on one end side of the piston to cause the piston to slide in the direction of opening the suction duct against a force, and supply system pressure on the consumption side to cause the piston to slide in the direction of closing the suction duct. a second pressure supply line for applying pressure to a pressure area on the other end of the piston, a ventilation passage that communicates the suction duct with the first pressure supply line at a piston position where the suction duct is closed, and the other end of the piston. A suction adjustment device for a compressor, which comprises a small-diameter through hole having one end open to the pressure region in order to communicate the side pressure region with the suction side of the compressor. 2. The compressor suction adjustment device according to claim 1, wherein the pressure region to which the second pressure supply line is connected is larger than the pressure region to which the first pressure supply line is connected. 3 Electrically or pneumatically controlled valve device is the second
A compressor suction adjustment device according to claim 1 or 2, which is provided in a pressure supply line of a compressor. 4. The suction adjustment device for a compressor according to claim 1, 2 or 3, characterized in that the closing member is provided with a ventilation opening for equalizing the pressure applied to the closing member.