WO2019130514A1

WO2019130514A1 - Method of reducing powder load of dry vacuum pump and powder load reducer

Info

Publication number: WO2019130514A1
Application number: PCT/JP2017/047083
Authority: WO
Inventors: 信明土屋; 則光田中; 拓也榊原; 治武井
Original assignee: 樫山工業株式会社
Priority date: 2017-12-27
Filing date: 2017-12-27
Publication date: 2019-07-04
Also published as: JP6895692B2; JPWO2019130514A1

Abstract

The purpose of the present invention is to receive and then temporarily accumulate a powder from an exhaust pipe (7) into a powder load reducer (10) disposed in a stage preceding a dry vacuum pump (3), thereby making it possible to prevent problems due to the entry of a large amount of powder into the dry vacuum pump (3) at once. The powder received into the powder load reducer (10) is temporarily accumulated on a powder receiving surface (18) at the bottom thereof. The powder accumulated on the powder receiving surface (18) is carried by a rotating gas flow (A) generated internally by vacuuming performed by the dry vacuum pump (3), and is discharged via a container exit (16). The powder is not kept accumulating in the powder load reducer (10). The need for a maintenance work and the like to remove the internally accumulated powder periodically is also eliminated.

Description

Powder load reducing method and powder load reducing device for dry vacuum pump

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a powder load reducing method and a powder load reducing device for reducing an increase in pump load caused by powder entering into a pump from an intake port of a dry vacuum pump.

In a film forming process such as CVD which is a semiconductor manufacturing process, evacuation of a reaction chamber or the like is performed using a dry vacuum pump. The exhaust gas drawn into the dry vacuum pump by vacuum drawing contains a powdery product. Small quantities of such powders do not cause problems in driving the pump even if they are drawn into a dry vacuum pump. However, when a large amount of powder enters the dry vacuum pump at one time, the pump may be overloaded and may not be able to start up.

For example, the product deposited on the inner wall of the exhaust gas pipe leading the exhaust gas to the suction port of the dry vacuum pump may react with the air flowing in when the pump is stopped and grow, and may be vacuum dried and separated from the inner wall during pump operation . The exfoliated powder penetrates the dry vacuum pump at one time in the form of lumps. If a large amount of powder enters at one time, the pump will be overloaded and shut down, making it impossible to restart. In order to prevent such an adverse effect, it is general to place an h-type piping or powder trap for capturing and storing powder at the front stage of the dry vacuum pump. For example, Patent Document 1 proposes a dry vacuum pump in which a centrifugal separation cylinder for trapping powder is attached to a pump intake port.

JP 2007-205287 A

Since the h-type piping and powder trap that are used conventionally capture in front of them so that a large amount of generated powder does not intrude into the pump, it is necessary to periodically take out the powder that has been trapped and accumulated inside. Maintenance is required. For maintenance, it is necessary to stop equipment such as the pump and its upper semiconductor manufacturing apparatus. Field work is required, and costs and man-hours are required. Further, in the case of a process in which a large amount of powder is generated in a short period, the maintenance cycle may be shortened, the operation rate may be reduced, and the operation may be difficult.

In view of the foregoing, it is an object of the present invention to provide a powder load reducing method and powder for a dry vacuum pump capable of preventing a large amount of powder from entering the pump without basically requiring maintenance. It is in providing a body relief.

In order to solve the above problems, in the powder load reducing method of a dry vacuum pump according to the present invention, a cylinder in which powder directed from an external pipe to an intake port of the dry vacuum pump is disposed between the external pipe and the intake port The inside of the container is received from the container inlet formed at the top of the container. The powder received inside the container is dropped onto the powder receiving surface disposed inside the container and temporarily stored in the powder receiving surface. Inside the container, the gas flows from the container inlet into the container interior, flows along the powder receiving surface, and flows out from the container outlet formed at the lower part of the cylindrical container. By this gas flow, the powder collected on the powder receiving surface is sent out from the container outlet which is opened at the downstream end of the flow direction of the gas flow on the powder receiving surface.

As the gas flow, a gas flow can be used which is generated by vacuuming of a dry vacuum pump and travels from the external piping side to the air inlet via the inside of the container. In this case, the powder temporarily accumulated on the powder receiving surface is pumped from the container outlet toward the suction port of the dry vacuum pump by the gas flow.

In the present invention, the powder from the external pipe on the upstream side is temporarily received inside the cylindrical container installed at the front stage of the dry vacuum pump. A large amount of powder can enter the dry vacuum pump at one time at the time of restart after pump stop and the like, and occurrence of adverse effects such as unintended pump stop can be prevented.

The powder received inside the cylindrical container temporarily accumulates on the powder receiving surface. A gas flow is generated inside the container by evacuation of a dry vacuum pump. The powder collected on the powder receiving surface is carried toward the downstream end of the powder receiving surface by the gas flow. The container outlet is open at the downstream end of the powder receiving surface, so that the powder is sent out from the container outlet together with the gas flow. The powder delivered from the container outlet is drawn into a dry vacuum pump. Since the relative positional relationship between the powder receiving surface and the container outlet is set such that the powder collected on the powder receiving surface is carried to the container outlet by the gas flow, the inside of the container of the cylindrical container is The powder is not stored in the reservoir, it is only stored temporarily. Maintenance for periodically removing the powder stored in the cylindrical container is not necessary.

In the present invention, it is desirable that the powder carried by the gas flow from the powder receiving surface is passed through a sieve disposed inside the container, and the powder in the form of lumps is crushed before being led to the container outlet. By passing through the sieve, it is possible to prevent the powder from being carried into the gas flow and being sucked into the dry vacuum pump in the form of a large lump.

In the present invention, the gas flow flowing inside the container is a swirling gas flow from the container inlet to the container outlet along the inner peripheral side surface inside the container, and the powder temporarily accumulated on the powder receiving surface is Preferably, it is carried to the vessel outlet by a swirling gas flow. By forming a swirling gas flow flowing along the inner peripheral side surface inside the narrow container of the cylindrical container, the powder accumulated on the powder receiving surface can be efficiently sent out to the container outlet.

In this case, the swirling gas flow flowing through the first sieve along the powder receiving surface may flow through the second sieve smaller than the first sieve to the container outlet. The agglomerated powder carried by the swirling gas flow is broken up more finely through the second sieve. The powder can be reliably prevented from being sucked into the dry vacuum pump in the form of lumps.

Next, according to the present invention, in order to reduce the driving load of the dry vacuum pump generated due to the powder entering from the external piping, the dry vacuum is used by being attached between the external piping and the suction port of the dry vacuum pump. A powder load reducer for the pump,
With a cylindrical container,
A container inlet formed at the top of the cylindrical container and connected to the external piping;
A container outlet formed at the lower part of the cylindrical container and connected to the suction port of the dry vacuum pump;
A powder receiving surface formed on the bottom of the inside of the cylindrical container and temporarily storing the powder received from the container inlet into the container;
Inside the container, a guide member for guiding the gas flow flowing in from the container inlet to the container outlet along the powder receiving surface;
The container outlet is open at the downstream end of the flow direction of the gas flow on the powder receiving surface so that the powder collected on the powder receiving surface is delivered from the container outlet by the gas flow.

It is desirable to arrange a sieve inside the container for breaking up a mass of powder carried from the powder receiving surface to the outlet of the container by the gas flow.

Preferably, the guide member includes a guide member for guiding the gas flow flowing in from the container inlet so that a swirling gas flow flowing in a direction along the inner circumferential side surface inside the container is formed.

The container inlet and the container outlet may be coaxially disposed above and below the cylindrical container. In this case, for example, the following configuration is adopted. The guide member includes, between the container inlet and the container outlet, an inclined plate for guiding the powder falling from the container inlet obliquely downward along the inner circumferential side to the powder receiving surface. Inside the container are arranged a first sieve through which the powder carried by the swirling gas flow passes and a second sieve through which the powder passes through the first sieve and towards the container outlet. A sieve finer than the first sieve is used as the second sieve.

In addition, the container inlet and the container outlet may be disposed at positions above and below the inside of the container and offset in a direction along the inner circumferential side surface inside the container. In this case, too, it is possible to arrange in the container a first sieve through which the powder carried by the swirling gas flow passes and a second sieve smaller than this.

FIG. 2 is an explanatory view showing an exhaust device to which a powder load reducer according to Embodiment 1 is attached. (A), (b), (c) and (d) are respectively a plan view of a powder load reducer, a side view thereof, an arrangement position of its mesh filter, and an explanatory view showing its internal structure . (A) is explanatory drawing which shows the flow of the swirling-like gas flow and powder body which passes a powder load reduction device, (b) is explanatory drawing which shows the flow of swirling-like gas flow. (A), (b), (c) and (d) are a plan view showing the powder load reducer according to the second embodiment, a side view thereof, an explanatory view showing an arrangement position of the mesh filter, and It is an explanatory view showing the internal structure. (A) And (b) is explanatory drawing which respectively shows another shape example of a powder load reducing device, (c) is explanatory drawing which shows the example of a powder load reducing device at the time of attaching a heat retention material. (A) And (b) is explanatory drawing which shows the example of arrangement | positioning of a dry vacuum pump, respectively.

Hereinafter, with reference to the drawings, a powder load reducer of a dry vacuum pump according to an embodiment of the present invention will be described.

First Embodiment
FIG. 1 is an explanatory view showing an exhaust device to which a powder load reducer according to Embodiment 1 is attached. The exhaust device 1 includes a two-stage dry vacuum pump 3 disposed inside the device case 2. For example, the mechanical booster pump 4 at the front stage and the screw type vacuum pump 5 at the rear stage are provided. The intake port 6 of the dry vacuum pump 3 opens upward on the top surface of the device case 2. A powder load reducer 10 is attached to the intake port 6. The intake port 6 is connected to an exhaust pipe 7 which is an external pipe on the upstream side via the powder load reducing device 10.

2 (a), (b), (c) and (d) are respectively a plan view of the powder load reducer 10, a side view thereof, an explanatory view showing the arrangement position of the mesh filter, and the inside thereof It is explanatory drawing which shows a structure. The powder load reducing device 10 prevents or suppresses an increase in the driving load of the dry vacuum pump 3 caused by the powdery product (hereinafter referred to as “powder”) entering from the exhaust pipe 7 side. It is to do. The powder load reducer 10 includes a bottomed cylindrical container 11 and a disc-like lid 12 closing the upper end opening.

In the cover plate 12, a circular container inlet 13 is opened at a position offset from the center to one side. An intake side connecting pipe 14 extending vertically upward is attached to the container inlet 13. The intake side connecting pipe 14 is connected to the upper exhaust pipe 7. A circular container outlet 16 is formed on the bottom plate 15 of the cylindrical container 11 at a position coaxial with the container inlet 13. An exhaust side connection pipe 17 is connected to the container outlet 16. The exhaust side connection pipe 17 is connected to the suction port 6 of the dry vacuum pump 3.

The internal structure of the cylindrical container 11 sealed by the lid plate 12 will be described. The top surface of the bottom plate 15 defining the bottom surface inside the container is a powder receiving surface 18 which is a horizontal flat surface except for the portion where the container outlet 16 is open. At a position of height between the container inlet 13 and the container outlet 16, an inclined plate 19 is coaxially disposed. The inclined plate 19 is a plate having an elliptical contour, and is inclined downward along the circular inner circumferential surface 20 of the cylindrical container 11 in the tangential direction. A semicylindrical lower vertical guide plate 21 extending to the edge portion of the container outlet 16 is formed at the lower edge portion of the outer peripheral edge of the inclined plate 19. In addition, a semi-cylindrical upper vertical guide plate 22 reaching the edge portion of the container inlet 13 is formed at the edge portion on the upper end side of the outer peripheral edge of the inclined plate 19. Therefore, inside the container, the top surface defined by the cover plate 12, the circular inner peripheral surface 20 of the cylindrical container 11, the powder receiving surface 18 of the cylindrical container 11, the upper vertical guide plate 22, and the inclined plate An internal flow path extending from the side of the container inlet 13 in the circumferential direction of the circular inner circumferential surface 20 to the container outlet 16 is formed by the guide member consisting of 19 and the lower vertical guide plate 21.

Moreover, the mesh filter 23 (1st sieve) is arrange | positioned inside a container. The mesh filter 23 comprises a horizontal upper surface portion 23a and a vertical end surface portion 23b. The upper surface portion 23 a is located between the semi-cylindrical lower vertical guide plate 21 and the circular inner circumferential surface 20 opposed thereto at a height position of the middle of the inclined plate 19 above the powder receiving surface 18. It is disposed and covers the powder receiving surface 18 except for the portion of the powder receiving surface 18 on the side of the container outlet 16. The end surface portion 23 b is bent at a right angle from the end of the upper surface portion 23 a on the side of the container outlet 16 and extends to the powder receiving surface 18.

A finer mesh filter 24 (second sieve) is attached to the end face portion 23 b of the mesh filter 23. The mesh filter 24 comprises an upper surface portion 24 a having a triangular contour and an end surface portion 24 b bent at a right angle from the edge on the container outlet 16 side and extending to the powder receiving surface 18.

In this example, the evacuation by the dry vacuum pump 3 forms an exhaust flow drawn from the exhaust pipe 7 through the inside of the container of the powder load reducing device 10 to the intake port 6 of the dry vacuum pump 3. An internal flow path is formed inside the container as described above. The exhaust flow from the container inlet 13 changes along the inclined plate 19 in the direction along the circular inner circumferential surface 20, and flows along the circular inner circumferential surface 20 on the surface of the powder receiving surface 18 to the container. It flows as a swirling gas flow towards the outlet 16.

Fig.3 (a) is explanatory drawing which shows the flow of the swirling-like gas flow and the powder which are formed inside the powder load reducing device 10, FIG.3 (b) is explanatory drawing which shows the flow of the swirling-like gas flow It is. By evacuation of the dry vacuum pump 3, exhaust air from the side of the exhaust pipe 7 once enters the powder load reducer 10 as shown by the hollow arrow A, and passes through this through the dry vacuum pump 3. It is drawn into the pump from the intake port 6. The powder carried by the exhaust or the lump of the powder carried away by peeling off from the wall surface of the exhaust pipe 7 does not directly enter the pump, and the powder load reducer 10 is It is accepted.

When the dry vacuum pump 3 is restarted or the like, a large amount of powder may be discharged in the form of lumps from the side of the exhaust pipe 7. In this case, a large amount of powder lump B enters the inside of the container from the container inlet 13 of the powder load reducer 10. As shown by the broken arrow C, the powder that has entered the inside of the container falls on the inclined plate 19 immediately below and is guided by the inclined plate 19 in the direction along the circular inner circumferential surface 20. The powder sliding on the inclined plate 19 falls on the portion of the powder receiving surface 18 covered by the mesh filter 23.

In a state where the vacuum drawing by the dry vacuum pump 3 is not performed, the powder that has entered the powder load reducing device 10 from the exhaust pipe 7 temporarily accumulates on the powder receiving surface 18 inside the container. That is, since the powder receiving surface 18 is a horizontal flat surface, the powder dropped onto the powder receiving surface 18 is not accumulated in the powder receiving surface 18 and is self-weighted from the powder receiving surface 18 to the container outlet 16. It does not slide down to the side.

When evacuation is performed by the dry vacuum pump 3 to form an exhaust flow, the exhaust flow flows as a swirling gas flow along the internal flow path formed inside the container. The swirling gas flow flows along the circular inner circumferential surface 20 on the surface of the powder receiving surface 18 and reaches the container outlet 16 opened at the downstream end of the powder receiving surface 18. The powder accumulated on the powder receiving surface 18 is conveyed through the mesh filter 23 and the mesh filter 24 sequentially by the swirling gas flow. The finely ground powder is conveyed by means of the swirling gas flow towards the container outlet 16 which is open at approximately the same height position. The powder, together with the swirling gas flow, is discharged from the opening of the container outlet 16 and fed to the suction port 6 of the dry vacuum pump 3.

By mounting the powder load reducing device 10, a large amount of powder does not infiltrate into the pump of the dry vacuum pump 3 at one time. It is possible to reliably prevent the pump from being overloaded or unable to start up. Further, when an exhaust flow is formed, the powder temporarily accumulated in the powder load reducing device 10 is discharged by the exhaust flow and fed into the pump of the dry vacuum pump 3. On the dry vacuum pump 3 side, the powder is sucked little by little, so the load does not increase excessively and normal operation is maintained. Furthermore, since the powder accumulated in the powder load reducing device 10 is automatically discharged by the exhaust flow, maintenance such as taking out the accumulated powder is basically unnecessary.

Second Embodiment
4 (a), (b), (c) and (d) are plan views showing a powder load reducing device according to Embodiment 2, a side view thereof, and an explanatory view showing the arrangement position of the mesh filter, FIG. 7 is an explanatory view showing an internal structure of the same. The powder load reducing device 30 shown in these figures comprises a bottomed cylindrical container 31 and a disc-like cover plate 32 closing the upper end opening. In the cover plate 32, a circular container inlet 33 is opened at a position offset from the center to one side. An intake side connecting pipe 34 extending vertically upward is attached to the container inlet 33. The intake side connection pipe 34 is connected to the upper exhaust pipe 7 (see FIG. 1). A circular container outlet 36 is formed on the bottom plate 35 defining the bottom of the cylindrical container 31. An exhaust side connection pipe 37 is connected to the container outlet 36.

The powder load reducing device 30 is disposed at a position where the container inlet 33 and the container outlet 36 are offset. In the present example, the container inlet 33 and the container outlet 36 are located on both sides of the center of the cylindrical container 31. In other words, the container inlet 33 and the container outlet 36 are disposed at positions separated by a predetermined angle in the circumferential direction of the cylindrical container 31, which is 180 degrees in this example. The exhaust pipe 7 and the suction port 6 of the lower dry vacuum pump 3 are generally arranged in coaxial positions. In this case, the aforementioned powder load reducing device 10 is used. When both are at offset positions, the powder load reducer 30 of this example is used.

The structure inside the cylindrical container 31 sealed by the cover plate 32 in the powder load reducing device 30 will be described. The bottom surface inside the container is a powder receiving surface 38 which is a horizontal flat surface except for the portion where the container outlet 36 is open. A semi-cylindrical vertical guide plate 41 extends to a height position of the lid plate 32 so as to surround the bottom center portion of the container outlet 36 over an angle of approximately 180 degrees. Therefore, inside the container, the top surface defined by the cover plate 32, the circular inner peripheral surface 40 of the cylindrical container 31, the powder receiving surface 38 formed on the bottom of the cylindrical container 31, and the vertical guide plate 41 The guide member) forms an internal flow path which branches from the side of the container inlet 33 to both sides in the circumferential direction of the circular inner circumferential surface 40 toward the container outlet 36.

The powder receiving surface 38 is covered by a mesh filter 43 (first sieve) except for a portion on the container outlet 36 side. The mesh filter 43 includes an upper surface portion 43 a located above the powder receiving surface 38 and an end surface portion 43 b. The upper surface portion 43a has a substantially semicircular outline, and is disposed between the convex side surface of the semicylindrical vertical guide plate 41 and the circular inner circumferential surface 40 of the cylindrical container 31 opposed thereto. The upper surface portion 43 a has a circular opening at a portion located immediately below the container inlet 33. The end surface portion 43b is bent at a right angle from each of both circumferential edges of the top surface portion 43a and extends to the powder receiving surface 38.

In the powder receiving surface 38, the portions on the container outlet 36 side of the end surface portions 43b on both sides of the mesh filter 43 are covered by the mesh filter 44 (second sieve). The mesh filter 44 is finer than the mesh filter 43. Each mesh filter 44 includes a top surface portion 44a having a triangular profile and an end surface portion 44b bent at a right angle from the edge of the top surface portion 44a and extending to the powder receiving surface 38.

Even when the powder load reducing device 30 of this configuration is used, the powder or powder lump from the exhaust pipe 7 does not directly intrude into the pump of the dry vacuum pump 3, and once, It is accepted by the powder load reducer 30. For example, a large amount of powder lumps discharged from the side of the exhaust pipe 7 enter the inside of the container from the container inlet 33 of the powder load reducing device 30. The powder that has entered the inside of the container falls to the portion of the powder receiving surface 38 covered by the mesh filter 43, which is located immediately below it. In a state where the vacuum drawing by the dry vacuum pump 3 is not performed, the powder that has entered the powder load reducing device 30 from the exhaust pipe 7 temporarily accumulates on the powder receiving surface 38 inside the container.

When evacuation is performed and an exhaust flow is formed, the exhaust flow flows from the container inlet 33 toward the powder receiving surface 38 below and then bifurcated along the circular inner circumferential surface 40 to form a circular shape. It flows as a swirling gas flow along the inner circumferential surface 40 and the powder receiving surface 38. Each swirling gas stream flows sequentially through mesh filter 43 and mesh filter 44 and merges at vessel outlet 36.

Since the powder receiving surface 38 is a horizontal surface, the powder (reserved powder) collected here is carried by the swirling gas flow toward the container outlet 36 which is open at substantially the same height position. And is fed into the suction port 6 of the dry vacuum pump 3. That is, the powder accumulated on the lower powder receiving surface 38 of the mesh filter 43 is carried by the swirling gas flow, and the end surface portion 43 b of the mesh filter 43 and the end surface portion 44 b of the mesh filter 44 And finely ground. Then, it is fed into the pump from the intake port 6 of the dry vacuum pump 3 through the container outlet 36.

By attaching the powder load reducing device 30, a large amount of powder does not infiltrate into the pump of the dry vacuum pump 3 at one time, and it is possible to reliably prevent the pump from falling into an overload state or a non-startable state. Further, when powder is temporarily accumulated in the powder load reducing device 30 and an exhaust flow is formed, the accumulated powder is discharged by the exhaust flow and is fed into the pump of the dry vacuum pump 3. On the side of the dry vacuum pump 3, a small amount of powder is drawn, so the load does not increase excessively and normal operation is maintained. Furthermore, since the powder accumulated in the powder load reducing device 30 is automatically discharged by the exhaust flow, maintenance such as taking out the accumulated powder is basically unnecessary.

[Other Embodiments]
The

powder load reducer

10, 30 described above comprises

cylindrical containers

11, 31. The present invention is not limited to a cylindrical container, and may be, for example, a polygonal cylindrical container such as a square or a regular octagon as shown in FIGS. 5 (a) and 5 (b).

Further, in order to suppress deposition and deposition of the powder on the inner wall inside the container of the powder

load reducing devices

10 and 30, the outer periphery or the like of the cylindrical container may be covered with a heat insulating material. For example, as shown in FIG. 5C, the outer peripheral surface of the suction side connecting pipe 14 in the powder load reducing device 10, the surface of the cover plate 12 and the outer peripheral surface of the cylindrical container 11 are made of

heat insulating materials

51, 52, 53, respectively. cover.

Furthermore, in the above example, the powder receiving surfaces 18, 38 are horizontal planes. The powder receiving surfaces 18 and 38 only have to be able to temporarily store the powder, and may be a curved surface, a convex curved surface, or a slightly inclined inclined surface. It is good that the powder does not slide down toward the

container outlet

16 or 36 by its own weight.

Further, in the above example, the mesh filters 43, 44 are shaped to include horizontal

upper surface portions

43a, 44a and vertical

end surface portions

43b, 44b. The shape of the mesh filters 43 and 44 is not limited to the above example. These shapes may be set so that the powder collected on the powder receiving surfaces 18 and 38 always passes through the mesh filters 43 and 44 before reaching the

container outlets

16 and 36. Also, in some cases, only one mesh filter may be arranged.

On the other hand, in each of the above-described examples, the powder temporarily accumulated on the powder receiving surface is discharged to the side of the dry vacuum pump using the exhaust flow generated by vacuuming of the dry vacuum pump. Another suction mechanism may be attachable to the outlet of the powder load reducer. Alternatively, the connection destination of the container outlet can be switched from the dry vacuum pump to the suction mechanism. The powder may be discharged to the outside by forming a gas flow passing through the powder receiving surface inside the container by the suction mechanism.

Further, in the above example, as shown in FIG. 6A, the exhaust device 1 is a multistage dry vacuum pump 3 disposed inside the device case 2, for example, the mechanical booster pump 4 at the front stage and the rear stage. A screw type vacuum pump 5 is provided. An exhaust pipe 7, which is an external pipe, extends upward from the exhaust device 1, and performs, for example, an exhaust process from the semiconductor manufacturing apparatus 100 installed on the upper floor.

As an arrangement example of the dry vacuum pump, for example, as shown in FIG. 6B, the mechanical booster pump 4 is connected to the side of the semiconductor manufacturing apparatus 100 on the upper floor, and the exhaust pipe 7 which is an external pipe is connected. , And may be connected to a screw type vacuum pump 5 disposed on the lower floor side of the exhaust system 1. In this case, the powder load reducer 10 may be connected between the suction port of the screw type vacuum pump 5 and the exhaust pipe 7.

In the above description, the material of each part of the powder load reducing device is not particularly mentioned. A metal material is generally used as a material of each part. An appropriate material may be used depending on the gas flow to be handled and the properties of the powder.

Claims

The powder directed from the external piping to the suction port of the dry vacuum pump is received from the container inlet formed in the upper portion inside the cylindrical container disposed between the external piping and the suction port,
The powder received inside the container is dropped onto the powder receiving surface disposed inside the container, and temporarily stored in the powder receiving surface,
Inside the container, a gas flow which flows from the container inlet into the container interior, flows along the powder receiving surface, and flows out from the container outlet formed at the lower part of the cylindrical container is formed.
A powder load reducing method of a dry vacuum pump for delivering the powder collected on the powder receiving surface from the outlet of the container opened at the downstream end of the flow direction of the gas flow on the powder receiving surface by the gas flow .
In claim 1,
The gas flow is a gas flow which is generated by vacuuming of the dry vacuum pump and which is directed from the side of the external piping to the air inlet via the inside of the container.
A powder load reducing method of a dry vacuum pump, wherein the powder collected on the powder receiving surface is sent out from the container outlet toward the suction port of the dry vacuum pump by the gas flow.
In claim 2,
The powder load reducing method for a dry vacuum pump according to claim 1, wherein the powder accumulated on the powder receiving surface is passed through a sieve disposed inside the container by the gas flow, and then introduced to the outlet of the container.
In claim 2,
The flow of gas flowing inside the container is made to flow as a swirling gas flow from the container inlet through the powder receiving surface toward the container outlet along the inner circumferential side of the container interior.
A powder load reducing method for a dry vacuum pump, wherein the powder accumulated on the powder receiving surface is guided to the outlet of the container by the swirling gas flow.
In claim 2,
The flow of gas flowing inside the container is made to flow as a swirling gas flow from the container inlet through the powder receiving surface toward the container outlet along the inner circumferential side of the container interior.
The powder collected on the powder receiving surface is guided to the outlet of the container after sequentially passing through the first sieve and the second sieve smaller than the first sieve by the swirling gas flow. Powder load reduction method of dry vacuum pump.
A powder vacuum relief device for a dry vacuum pump, which is installed between an external pipe and a dry vacuum pump inlet,
With a cylindrical container,
A container inlet formed at an upper portion of the cylindrical container and connected to the external pipe;
A container outlet formed at a lower portion of the cylindrical container and connected to the suction port of the dry vacuum pump;
A powder receiving surface formed on the bottom of the inside of the cylindrical container and temporarily storing the powder received from the container inlet into the container;
A guide member disposed inside the container for guiding a gas flow flowing from the container inlet to the container outlet along the powder receiving surface;
A dry vacuum in which the container outlet is open at the downstream end of the flow direction of the gas flow on the powder receiving surface so that the powder collected on the powder receiving surface is delivered from the container outlet by the gas flow. Powder load reducer for pumps.
In claim 6,
A powder load reducing device for a dry vacuum pump, wherein a sieve is disposed inside the container for passing the powder carried from the powder receiving surface to the container outlet by the gas flow.
In claim 7,
The powder load reducing device for a dry vacuum pump, wherein the guide member guides a gas flow flowing from a container inlet so that a swirling gas flow is formed in a direction along an inner circumferential side surface inside the container.
In claim 8,
The container inlet and the container outlet are coaxially disposed above and below the cylindrical container,
The guide member includes an inclined plate inclined obliquely downward toward the inner peripheral side surface between the container inlet and the container outlet.
Inside the container, a first sieve and a second sieve disposed between the first sieve and the container outlet are disposed as the sieves,
The powder load reducer of a dry vacuum pump, wherein the second sieve has a screen mesh finer than the first sieve.
In claim 8,
The container inlet and the container outlet are disposed at upper and lower portions inside the container at circumferentially offset positions along the inner peripheral side surface of the container inside,
Inside the container, a first sieve and a second sieve disposed between the first sieve and the container outlet are disposed as the sieves,
The powder load reducer of a dry vacuum pump, wherein the second sieve has a screen mesh finer than the first sieve.