JPH0137191Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a control device used in oil-fed compressors such as oil-fed screw compressors and oil-fed single-rotor compressors, and is particularly applicable to control devices that control the power during no-load conditions. The present invention relates to a control device that is effective in reducing.

[Prior art]

Generally, in the above-mentioned oil-fed compressor, during no-load operation, it is possible to close the suction valve to prohibit air intake into the compressor, and to release the pressure on the primary side of the pressure regulating valve to the outside air. It is being done.

FIG. 4 shows a conventional configuration of an oil-fed compressor, its peripheral equipment, and a control device for controlling the pressure of the compressor.

In this device, the compressor 10 has a suction valve 11 which is a piston type during normal load operation.
It operates to suck air from the suction filter 12 through the suction filter 12 and increase the pressure of this air to a predetermined pressure. However, the compressed air pressurized by the compressor 10 is mixed with lubricating oil. Therefore, with this device,
The oil component is separated from the compressed air pressurized by the compressor 10 in the oil sump 13 to obtain pure compressed air without any lubricating oil, and then the pressure is regulated to the required pressure by the pressure regulating valve 14. I am sending it to the place where it will be used. After this, when the consumption of the compressed air at the place of use decreases and the load state is lower than the predetermined load or is completely no-load state (hereinafter referred to as no-load state), the control device is activated. The pressure control described above is started. In other words, if such a no-load condition occurs, the compressed air transmission line
Since the pressure within AP1 increases accordingly, the control device uses the pressure switch 21 to detect that the pressure within this transmission path AP1 has risen to a pressure that indicates a no-load state, and further detects this. The three-way solenoid valve 22 and the escape solenoid valve 23 are controlled to be opened by the signal DS. As a result, the suction valve 11 is closed by the compressed air propagated through the three-way solenoid valve 22 and the transmission path AP2, so that the air suction of the compressor 10 is prohibited, and the air intake from the oil sump 13 is prohibited. The compressed air to be output is also connected to the above-mentioned escape solenoid valve 23 arranged in the escape path AP3.
The air is then blown into the atmosphere through the orifice 24 and further through the air blown silencer 25.

[Problems with conventional technology]

In order to reduce the power of the compressor 10 during the above-mentioned no-load operation, two conditions are required: the back pressure of the compressor 10 should be made as low as possible, and this should be done in a short time. However, it is known that when attempting to complete the above-mentioned release in a short time to satisfy these conditions, the lubricating oil separated in the oil sump 13 also blows out to the outside air, and as a result, as shown in FIG. In the conventional control device as shown, in order to perform the above-mentioned air release, two methods as shown below have to be used. Hereinafter, with reference to FIG. 5, these conventional methods of escape will be explained.

First, as shown by curve L1 in FIG. 5, the first method is to gradually release a small amount of the lubricating oil over time through the orifice 24 described above so that the lubricating oil does not blow out. However, contrary to the above conditions, this hardly results in power reduction.

Although the second method does not directly correspond to the configuration shown in FIG. 4, the curve L2 in FIG.
As shown in the figure, this is a method in which air is released in a relatively short period of time up to a pressure of about 1.8 kg/cm ³ , and thereafter the pressure is maintained at the same pressure using an appropriate pressure-holding valve. This is because it is known from experience that the lubricating oil is blown out into the outside air only after the pressure reaches 1 kg/cm ³ or ^less . Depends on the consideration given. However, as is clear from FIG. 5, even this does not substantially reduce the power at all.

As described above, with the conventional control device, it has not been possible to reduce the power during no-load operation of the compressor.

[Purpose of invention]

This invention provides a control device for an oil-filled compressor that can effectively reduce power by letting the compressed air escape in a short time without blowing out the lubricating oil into the outside air during no-load operation of the compressor. The purpose is to

[Structure of the idea]

In this invention, focusing on the fact that the lubricating oil is blown into the outside air only after the pressure drops below a predetermined low pressure, as described above, at least two solenoid valves for escape are installed in the escape path of the compressed air. The solenoid valves are provided in parallel, and the opening/closing mode of these solenoid valves is controlled based on the discharge pressure of the compressed air discharged through the air escape passage. The amount of air released is increased to release the compressed air in a short time until the pressure reaches the predetermined low pressure, and after the pressure reaches the predetermined low pressure, the amount of air released is reduced and the compressed air is gradually released. I told him to let him escape.
Compressed air is discharged into the atmosphere in at least two steps (of course, three or more steps are possible) with different amounts of released air. As a result, the release of the compressed air is completed in a much shorter time than in the conventional control described above, and the situation where the lubricating oil is blown out into the outside air can be avoided.

In addition, the form of the plurality of solenoid valves provided in parallel,
The opening/closing method thereof, and the form of the escape path corresponding to each of these solenoid valves are arbitrary as long as the above-mentioned stepwise escape can be realized. Therefore, for example, each solenoid valve or each The escape capacity of the escape passages themselves may be made different, and these passages may be sequentially opened and closed based on the discharge pressure described above, starting with the one with the highest escape capacity. Alternatively, solenoid valves or escape passages with the same escape capacity may be used. Even when using a pipe, various configurations and methods can be used depending on the actual situation, such as switching the number of these to be actually opened based on the above-mentioned discharge pressure, or even combining these methods. I can do it.

[Effect of idea]

As described above, according to the control device for a lubricating compressor according to this invention, the compressed air can be released in a short time without blowing out the lubricating oil into the outside air, thereby preventing any inconvenience. The power required during no-load operation of the compressor can be reduced without causing any damage.

〔Example〕

FIG. 1 shows an embodiment of a control device for an oil-fed compressor according to this invention. However, in this embodiment, the compressor 10 to be controlled, as well as its peripheral devices such as a piston-type suction valve 11, a suction filter 12, an oil sump 13, and a pressure regulating valve 14, are used.
is assumed to be similar to that shown in FIG. 4 earlier, and redundant explanation will be omitted.

Now, the control device of this embodiment is configured to release the generated compressed air in two steps with different amounts of air release when the above-mentioned no-load condition occurs. In order to realize air escape, the air escape path AP3 is further connected as shown in the figure.
The air passage AP3a has a high air escape capacity, and the air passage AP3b has an orifice 36, that is, has a low air escape capacity, which are branched into two, and the opening and closing of these air paths can be selectively switched.

First, the functions of each part that makes up the control device will be explained.

The first pressure switch 31, like the pressure switch 21 shown in FIG. This is a switch that detects this fact, and operates to output a detection signal DS1 when it detects a rise in pressure to the predetermined pressure.

Further, the three-way solenoid valve 32 is also connected to the first pressure switch 3 in the same way as the three-way solenoid valve 22 shown in FIG.
This is a solenoid valve that opens the compressed air transmission path AP2 when the detection signal DS1 is applied from the three-way solenoid valve 32. The opening of the three-way solenoid valve 32 closes the intake valve 11, and the air intake of the compressor 10 is stopped. As mentioned above, it may become prohibited.

As shown in the figure, the second pressure switch 33 is a switch that monitors the pressure of the compressed air released from the air escape path AP3, that is, the discharge pressure when the compressed air is discharged into the atmosphere. Here, it is assumed that when the discharge pressure reaches a low pressure of about 1 kg/cm ³ as described above, a detection signal DS2 indicating this fact is output.

Of the above-mentioned escape paths AP3, the first escape electromagnetic valve 34 disposed in the above-mentioned escape path AP3a having a high escape capacity receives the detection signal DS1 outputted from the above-mentioned first pressure switch 31. the escape path when
It is a solenoid valve that functions to open AP3a and close the same escape path AP3a when the detection signal DS2 output from the second pressure switch 33 is applied, and the other escape path AP3b with a lower escape capacity. The second escape solenoid valve 35 arranged in the second pressure switch 33 is a solenoid valve that functions to open the escape path AP3b to which the detection signal DS2 output from the second pressure switch 33 is applied.

Next, the overall operation of the control device of this embodiment will be explained with reference to FIG. However, in FIG. 2, the curve L3 corresponds to the control of this embodiment, and the other curves L1 and L2 are the conventional control modes shown in FIG. 5 for reference. It is.

Now, let us assume that the place of use, which was in a loaded state, has now become in the above-mentioned no-load state, and this fact is detected by the first pressure switch 31. Therefore, the first pressure switch 31 outputs the above-mentioned detection signal DS1, and based on this, the three-way solenoid valve 32 and the first escape solenoid valve 34 are each opened. As a result, the air intake of the compressor 10 is prohibited as described above, and furthermore, the air intake of the compressor 10 is prohibited.
The compressed air output from AP 3 is also released all at once through the air passage AP 3a, which has a high air escape capacity, and is discharged into the atmosphere. At this time, the discharge pressure of the compressed air released at this time rapidly decreases in a short period of time, as shown by the initial change in curve L3 in FIG. When this discharge pressure decreases to about 1 Kg/cm ³ , this fact is detected by the second pressure switch 33, and the second pressure switch 33 outputs the aforementioned detection signal DS2. This results in
The first escape electromagnetic valve 34 is "closed," and the second escape electromagnetic valve 35 is instead "open." Therefore, at this point, the compressed air output from the oil sump 13 switches its escape path to the AP3b side, which has a lower air escape capacity, and thereafter escapes through the orifice 36 little by little over time. It becomes like this. At this time, the discharge pressure of the compressed air gradually decreases as shown by the change after the pressure of 1 kg/cm ³ in curve L3 of FIG. 2. Of course, this also effectively avoids the situation where the lubricating oil blows out as described above.

As described above, according to this embodiment, it is possible to complete the release of the compressed air in a much shorter time than in conventional control, and the power loss is also reduced as indicated by diagonal lines in FIG. As shown, it is very small.

In the case of this embodiment, the amount of escape of the compressed air at any time, in other words, the degree of change (inclination) of the curve L3 shown in FIG. 2 at any time depends on the escape path AP3.
It is determined by the escape capacity of each of AP3a and AP3b, and these escape paths AP3a and AP
The escape capacity of 3b is curve L3 in Fig. 2.
It is assumed that the ability to achieve the escape corresponding to the above is set in advance.

In addition, if it is possible to realize such a gradual escape, it is necessary to consider the form of multiple solenoid valves installed in parallel in the escape path, their opening/closing method, and the form of the escape path corresponding to each of these solenoid valves. As mentioned above, this is not limited to the aspect of the embodiment described above, but is arbitrary.

By the way, when such a compressor is actually used in a factory, etc., it generally undergoes repeated load and no-load operation in the manner shown in Figure 3, and is operated at 60 to 80% of its total capacity. However, even in such cases, the control of this invention significantly reduces the power required each time there is no load, as shown in Figure 3, and has a very favorable economic effect. can be obtained. The effect is particularly significant when the no-load time continues for a long time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a control device for a lubricated compressor according to this invention, and FIGS. 2 and 3 are lines showing an example of a pressure control mode according to the embodiment shown in FIG. 1, respectively. 4 are block diagrams showing an example of the conventional control device, and FIG. 5 is a diagram showing an example of a pressure control mode by the conventional control device. 10...Compressor, 11...Suction valve, 12...Suction filter, 13...Oil sump, 14...Pressure regulating valve, 2
1, 31, 33... Pressure switch, 22, 32... Three-way solenoid valve, 23, 34, 35... Relief solenoid valve, 2
4, 36... Orifice, 25... Air discharge silencer.

Claims (1)

[Scope of utility model registration request] The presence or absence of a load is detected based on the pressure of the compressed air output through the oil sump, and when there is no load, the air suction of the compressor is suppressed, and
In a control device for an oil-fed compressor that opens a first solenoid valve disposed in an air escape passage to discharge the compressed air, the control device includes: A plurality of second solenoid valves and a control means for controlling the opening/closing mode of the first and second solenoid valves based on the discharge pressure of the compressed air to be blown out are provided, 1. A control device for an oil-filled compressor, characterized in that air is discharged in at least two different steps.