JPH02298689A - Start load reducing device of vacuum device using flow control valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a vacuum system in which a rotary pump and a vacuum container are connected via piping, and fluid in the vacuum container is suctioned and discharged into a vacuum state by operation of the rotary pump. The present invention relates to a load reduction device that reduces the load when starting a rotary pump in an apparatus.

(Prior Art) Conventionally, a vacuum device is known in which a rotary pump and a vacuum container are connected through piping, and a fluid in the vacuum container is suctioned and discharged by operation of the rotary pump to create a vacuum state. In the vacuum device, when the rotary pump is started, the entire volume of fluid in the vacuum container and piping becomes a load.

In addition, as a countermeasure, it has been proposed to provide a valve in the pipeline between the rotary pump and the vacuum vessel that is opened by a piston that is operated by negative pressure in the pipeline (Japanese Patent Publication No. 12636/1983). .

[Problems to be Solved by the Invention] In the vacuum device that does not use a valve, the pump is started with a large load capacity, and operates in an overload state for several minutes, resulting in large power consumption and shortening the life of the pump itself. Ta. In some cases, the motor may not rotate due to overload.

For this reason, measures such as using large-capacity pumps have been taken to prevent continued overload operation.

In addition, in a vacuum device using the above-mentioned valve, the valve is screwed.

Since the valve is operated at a constant pressure of 1.5 ton, it causes sliding resistance, has poor airtightness, and has the disadvantage that the valve's operating characteristics are unstable.

Furthermore, in the vacuum device using the valve, the pressure downstream of the valve, that is, between the valve and the rotary pump, is introduced as the pressure in the pipeline to open the valve, so the valve is immediately opened by the operation of the rotary pump. The opening causes the higher pressure fluid from the vacuum vessel side to flow in. The inflow of high-pressure fluid causes the valve to close again, resulting in a hunting phenomenon.

The object of the present invention is to reduce the load on a rotary pump at the time of startup, to achieve a vacuum in a vacuum container with a pump of appropriate capacity and motor output, and to stably reduce the load on startup.

(Means for Solving the Problems) The present invention provides a branch pipe that protrudes in a direction substantially perpendicular to the tubular body between the rotary pump and the vacuum container, and provides a branch pipe integrally with the tubular body, and covers the branch pipe. A bellows concentric with the branch pipe is provided, a bottom plate integral with the bellows is brought into airtight contact, and a holder is provided that slides within the branch pipe, and the holder is provided with an adjustment screw screwed into the tail portion. , the adjusting screw is urged to abut against the free end surface of the bellows by a spring interposed between the tubular body surface and the adjusting screw in the bellows, and a flow control valve is provided on the tubular body connected to the support body. , in the pipeline between the rotary pump and the vacuum vessel, when the rotary pump is started, if the pressure difference between atmospheric pressure and the pressure upstream of the valve exceeds a certain value, the opening of the valve will be adjusted according to the pressure difference. A rotary rotary that controls the flow from fully closed to fully open by increasing the flow rate, reduces the load by reducing the flow rate at startup, and gradually increases the flow rate according to the pressure difference to keep the load almost constant until fully open. This provides a load reduction device when starting a pump.

[For production]

With the above configuration, the pressure inside the vacuum container is close to atmospheric pressure before the rotary pump is started, and when the difference does not reach a certain value, the valve is in the fully closed position, and in this state, the pump is extremely close to atmospheric pressure. It is easily activated, and the fluid in the line on the pump side of the valve is suctioned and the pressure decreases.6 This creates a pressure difference with the fluid in the line on the vacuum vessel side of the valve, and the fluid on the vacuum vessel side is drawn away from the valve. The flow flows from the gap with the pipe wall to the pump side, the pressure in the vacuum vessel side pipe decreases, the pressure in the bellows decreases, and when the differential pressure with the atmospheric pressure outside the bellows exceeds a certain value, the valve closes. The opening degree is increased according to the differential pressure, increasing the amount of fluid inside the vacuum container flowing to the pump side, and when the predetermined pressure difference is reached, the valve is fully opened. From now on, the pump is operated in this state, and the inside of the vacuum container is pumped. A predetermined degree of vacuum is achieved.

〔Example〕

Embodiments of the startup load reduction device of the present invention will be described below based on the drawings.

Figure 1 shows a cross-sectional view of an embodiment of the present invention, in which the valve body (1) has a flange (2) connected to the rotary pump piping at one end, and a flange (3) connected to the vacuum vessel piping at the other end. ), and a branch pipe (4) projecting in a direction substantially perpendicular to the central axis of the tubular body is integrally provided on the circumferential surface of the tubular body.

A bottom plate (6) that covers the branch pipe (4), is provided with a bellows (5) concentric with the branch pipe (4), and is integrated with the bellows (5).
is airtightly attached to the surface of the tubular body. In addition, the support body (7) that slides inside the branch pipe (4) has an adjustment screw (
8). Then, tighten the adjustment screw (8) into the bellows (
5), a spring (9) interposed between the tubular body surface and the adjusting screw (8) urges the bellows to come into contact with the free end surface. As a result, the pressure difference between the inside and outside of the bellows (5) and the spring (9)
opposes. Note that the branch pipe (4) opens into the tubular body on the container side.

As shown in FIGS. 2(a) and 2(b), the inner peripheral surface of the valve body (1) made of the tubular body has a support shaft (a) at an opposing position.
, a disc-shaped valve body 10 that protrudes inward and is fixed, is perpendicular to the axis of the tubular body, and has a peripheral edge in contact with the inner surface of the tubular body.
), which is fixed to the surface of the valve body (lO) and has the support shaft (a);
Connector (11), (11-) pivoted on (a = )
The valve body (10) is rotatably supported around a support shaft (a), (a = ). and the support shaft (a), Ca
=) An annular or semi-annular connecting ring (12) is provided at a position that is perpendicular to the line connecting the valve body and off-center on the center line of the valve body surface. One end of the connecting ring (14) is engaged with the connecting ring (12), and the other end of the connecting ring (14) is a connecting ring (14) fixed to one end in the branch pipe (4) of the ring body (7). 13), and the valve body (10
) can be tilted around support shafts (a) and (a').

Figures 2 and 3 are partial enlarged sectional views of the main parts of Figure 1, showing the connection structure between the valve body (lO) and its ring body (7), and Figure 2 shows the valve fully open. (a) is a cross-sectional view, and (b) is a cross-sectional view taken along the line A-A, exaggerating the gap between the valve body (10) and the inner surface of the valve body (1). However, in reality, they are in contact with each other. Figure 3 shows the valve fully open, (a) is a cross-sectional view, and (b) is an A-
It is a sectional view along the A= line.

Next, its effect will be explained. In Figure 1, the bellows (5
) effective cross-sectional area AcLd, cross-sectional area of ring body (7) a cr
A. Atmospheric pressure P. kg/cot, vacuum vessel internal pressure P+
kg/cot, and the elasticity of the spring (9) is Skg, and the pressure inside and outside the bellows (5) and inside the vacuum container is approximately atmospheric pressure P before the rotary pump is started. , and the spring (
9) The bellows (5) is biased to the right in the figure by the elasticity S,
The elasticity S of the spring (9) is set so that the valve body (10) is fully closed.

When the rotary pump is started, the fluid in the pipeline on the pump side is first sucked from the valve body (10) and the pressure decreases, and the fluid in the pipeline on the vacuum vessel side flows between the valve body (10) and the inner wall of the pipeline. At the same time, the fluid inside the bellows (5) is also sucked through the gap between the branch pipe (4) and the ring body (7) and the pressure decreases, as in the vacuum container. The pressure inside the bellows (5) is atmospheric pressure P. This results in a lower Pl.

Pressure difference P between the inside and outside of the bellows (5). - Force due to Pl (Po
-P, )A becomes greater than the elasticity S of the spring, compressing the spring to an equilibrium position, and thus the ring body (7) moves to the left in the figure and passes through the connecting ring (14) to the valve body ( 10) is tilted around the support shafts (a) and (a') to widen the gap between the inner wall of the valve body (1) made of a tubular body and the valve body (10), thereby increasing the flow rate sucked into the pump side. , pressure difference P. -P, the opening degree is increased in accordance with This is to obtain a degree of vacuum.

Figure 4 is a diagram showing the degree of vacuum in the vacuum container and the power consumption of the pump. Diagram (1) is a conventional example in which no valve is used in the pipeline, and diagram (2) is an example of the present invention. In this conventional example, the fluid in the vacuum container and piping becomes the pump load at startup, so the power consumption is high and as the pump continues to operate, the density of the fluid gradually decreases. As a result, the amount of electricity will gradually decrease.

In the present invention, the pump load at startup is the fluid in the pipeline on the pump side of the valve, so the pump continues to operate smaller than in the conventional example (1), and the pressure on the vacuum vessel side of the valve decreases. The flow rate increases according to the difference from the atmospheric pressure, but the density of the fluid also decreases, so there is not much difference in the pump load, and the power consumption is approximately constant, and the density decreases from the fully open state. As a result, power consumption is reduced.

Therefore, compared to the pump power consumption required for the start-up load in the conventional example (1), the power consumption in the present invention (2) from startup to valve full opening is small and approximately constant; The motor can have an appropriate output corresponding to .

[Effects of the Invention] As explained above, the present invention has the above-mentioned configuration, so that when the pump is started, the entire volume of the fluid in the vacuum container and piping becomes the pump load, unlike when a conventional valve is not used. Since the load can be kept almost constant from startup until the flow rate control valve is fully opened, a pump with an appropriate capacity corresponding to this load is sufficient, and compared to conventional devices, it requires less motor power. The pump can be made smaller and has the effect of reducing power consumption and eliminating overload operation, thereby extending the life of the pump.

In addition, compared to a valve that is opened by a piston operated by negative pressure in the pipe line in the pipe line between the rotary pump and the vacuum container pipe, the present invention opens the valve with a bellows, so it does not slide easily. Because there is no resistance and the airtightness is improved,
The operating characteristics of the valve are stabilized.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the start-up load reduction device for a vacuum apparatus of the present invention, and FIG. 2 is a partially enlarged sectional view of the main part of FIG. 1 showing the fully closed state of the valve. A cross-sectional view, (B) is a cross-sectional view taken along the line A-A', FIG. 3 is a partially enlarged cross-sectional view of the main part of FIG. (b) is a sectional view taken along the line B-B', and FIG. 4 is a diagram showing the relationship between the degree of vacuum and electric power. (1)...Valve body (5)...Bellows (
7)... Ring body (8)... Adjustment screw (9
)...Spring (lO)...Valve body (11)
, (11=)...Connector (12), (13)・
...Connection ring (14) ...Connection ring

Claims (1)

[Claims] In a vacuum device in which a rotary pump and a vacuum container are connected by piping, and a fluid in the vacuum container is suctioned and discharged to create a vacuum state by operation of the rotary pump, a tubular body between the rotary pump and the vacuum container is A branch pipe protruding in a substantially perpendicular direction is provided integrally with the tubular body, a bellows is provided that covers the branch pipe and is concentric with the branch pipe, and a bottom plate integral with the bellows is brought into airtight contact with the interior of the branch pipe. A rod is provided on which the rod slides, and the rod is provided with an adjusting screw screwed into the tail portion, and the adjusting screw is connected to the bellows by a spring interposed between the tubular body surface and the adjusting screw within the bellows. A flow control valve is provided in the tubular body connected to the rod body, and when the rotary pump is started, the pressure difference between atmospheric pressure and the pressure upstream of the flow control valve is equal to or higher than a certain value. This device increases the opening degree of the valve in accordance with the differential pressure and performs control from fully closed to fully open.