JPH0312676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combination of non-contact dry vacuum pumps (screw pumps, roots pumps, turbo pumps, etc.) and contact dry vacuum pumps (vane pumps, cam pumps, etc.). The combination relates to a shaft seal for a non-contact dry vacuum pump.

(Prior technology) Conventionally, oil rotary vacuum pumps have been used to evacuate from atmospheric pressure to 10 ^-3 Torr, but since oil liquid was used, oil contamination inside the vacuum container and indoor contamination due to oil mist were caused. In the case of exhausting condensable gases such as moisture, there were problems such as decreased performance due to oil deterioration, and in the case of exhausting corrosive gases, there were problems such as pump damage due to oil seepage.

In order to solve the above problem, the applicant filed a patent application in 1983-
241389 provided. The invention on the right includes a screw pump and a single-stage or multiple-stage vane pump disposed after it, and the screw pump and the vane pump are
It is a composite dry vacuum pump characterized by being driven by a single drive source, with a screw pump, which is a type of non-contact type dry vacuum pump, and a vane pump, which is a type of contact type dry vacuum pump, in the front stage. is arranged in the latter part, and its outline will be explained below.

FIG. 4 is a schematic diagram showing an embodiment of the invention on the right. The gas in the vacuum container is sucked in through the vacuum suction port 9, compressed by the screw pump 1 by driving the screw pump drive shaft 5, passes through the screw pump exhaust port 10, the first stage vane pump suction port 11, Driven by the vane pump drive shaft 7, the first stage vane pump 2, second stage vane pump 3, and third stage vane pump 4 are compressed in this order and discharged into the atmosphere from the discharge port 14. The invention on the right has a screw pump in the front stage, so the right screw pump shows good performance in high vacuum, which is a general feature of non-contact dry vacuum pumps, and the invention has a vane pump in the rear stage. Therefore, the right vane pump exhibits good performance at low vacuum, which is a common feature of contact dry vacuum pumps, and both pumps together can efficiently obtain a vacuum state. A rubber packing 6 is used as a sealing material on the drive shaft 5, which is the drive shaft of the screw pump 1.

(Problem to be solved by the invention) As described above, the composite dry vacuum pump shows efficient performance, but in order to further improve the pump performance, it is greatly influenced by the performance of the screw pump in the previous stage. Increasing the rotational speed of screw pumps will help improve pump performance.
However, the rotation speed of the screw pump
If the rotational speed is increased above 3000r.pm, there is a possibility that the rubber used for the rubber packing 6 will generate heat or wear out, and therefore, it has been difficult to increase the rotational speed above 3000r.pm.

(Means for Solving Problems) The present invention provides a labyrinth seal groove on the drive shaft 5 of a non-contact dry vacuum pump in place of the conventional airtight seal material, and drains the atmosphere leaking into the right groove into the downstream stage. This invention relates to a shaft seal structure characterized in that the rotation speed of a non-contact type dry vacuum pump in the preceding stage can be increased by evacuation using a contact type dry vacuum pump.

That is, in a composite dry vacuum pump that connects a non-contact type dry vacuum pump and a contact type dry vacuum pump, a labyrinth seal groove is provided on the drive shaft of the non-contact type dry vacuum pump, and a labyrinth seal groove is provided in the groove via an exhaust path. , relating to a labyrinth seal for a non-contact dry vacuum pump characterized in that it is connected to a contact dry vacuum pump (first invention);
And in a composite dry vacuum pump that connects a non-contact dry vacuum pump and a contact dry vacuum pump, a labyrinth seal groove is provided on the drive shaft of the non-contact dry vacuum pump, and an exhaust path is connected to the groove, This invention relates to a shaft seal for a non-contact dry vacuum pump, characterized in that a contact dry vacuum pump is connected to the groove, and a screw or rotary blade mechanism is added to the groove (second invention of the present invention).

(Function) To explain the function of the present invention with reference to an embodiment thereof, Fig. 2 is a general overview of the right embodiment.
It gradually leaks to the vacuum side in the order of 3, 22, and 21. First, the air leaking to the right side 23 is sucked by the third stage vane pump 4 and passes through the third stage exhaust port 26 through the exhaust passage 29, enters the pipe 13 which is the inlet of the third stage vane pump 4, and passes through the third stage vane pump 4. , are discharged to the atmosphere from the exhaust port 14. Similarly,
The air leaking from the right side 23 to 22 is sucked by the second stage vane pump 3 from the second stage exhaust port 25, passes through the exhaust path 28, enters the pipe 12 which is the inlet of the second stage vane pump 3, and enters the second stage vane pump 3. , the third stage vane pump 4, and is discharged to the atmosphere from the exhaust port 14. Similarly, right 23 to 22 and 21
The leaked air is sucked by the first stage vane pump 2, passes through the first stage exhaust port 24, passes through the exhaust passage 27, enters the first stage vane pump 2 from the first stage vane pump inlet 11, and flows into the second stage vane pump 3 and the third stage vane pump 2. It passes through the stage vane pump 4 and is exhausted to the atmosphere from the exhaust port 14.

(Example) Figures 1 and 2 show an example of the present invention. A screw pump drive shaft 5 is inserted into the pump case 15. A drive bearing 16 is installed around the screw pump drive shaft 5, and a bearing presser 17 is pressed against the drive bearing 16. Inside the drive bearing 16, the pump case 15 has a first stage labyrinth seal groove 21, a second stage labyrinth seal groove 22,
A third stage labyrinth seal groove 23 is connected. A first stage exhaust port 24 is connected to the first stage labyrinth seal groove 21.
is connected to the first stage vane pump suction port 11 via an exhaust path 27. Similarly, the second stage labyrinth seal groove 22 is connected to the second stage exhaust port 25, the third stage labyrinth seal groove 23 is connected to the third stage exhaust port 26, and the second stage exhaust port 25 is connected to the exhaust path 28. The third stage exhaust port 26 is connected to the pipe 12 which is the inlet of the second stage vane pump 3 through the exhaust passage 27, and the third stage exhaust port 26 is connected to the pipe 1 which is the inlet of the third stage vane pump 4 through the exhaust passage 27.
3 are connected to each other. By adopting the structure shown on the right, the pressure difference from the atmosphere to the vacuum can be changed in stages, and the influence of leaks to the vacuum side can be reduced.

FIG. 3 shows another embodiment of the invention. Inside the drive bearing 16, there is a pump case 15.
A first stage labyrinth seal groove 21 and a second stage labyrinth seal groove 22 are connected to each other. A first stage exhaust port 24 is connected to the first stage labyrinth seal groove 21, and the first stage exhaust port 24 is connected to the exhaust path 28.
(not shown), it is connected to the second stage vane pump inlet 12. A second stage exhaust port 25 is connected to the second stage labyrinth seal groove 22, and the second stage exhaust port 25 is connected to the third stage vane pump 4 via an exhaust path 29 (not shown). It is connected to a pipe 13 which is an inlet. Screws 30, 3 are provided between the drive bearing 16 and the second stage labyrinth seal groove 22, between the second stage labyrinth seal groove 22 and the first stage labyrinth seal groove 21, and inside the first stage labyrinth seal groove 21, respectively.
The screws 30, 30, 30 rotate together with the screw pump drive shaft 5. The air leaking from the atmosphere side by clockwise rotation can be pushed back to the atmosphere side by rotating the screw, and the first stage labyrinth seal groove 21 and the second stage labyrinth seal groove 22
Combined with this, the influence of leakage on the vacuum side can be minimized.

Note that instead of the right-handed thread, a rotary blade mechanism (not shown) with blades provided at the periphery may be used.

Furthermore, the present invention is not limited to a combination of a screw pump and a vane pump, but may be any composite dry vacuum pump that connects a non-contact type dry vacuum pump and a contact type dry vacuum pump. A vacuum pump and a contact dry vacuum pump connected in parallel may also be used.

(Effects) The effects of the present invention are as follows. In other words, by using a labyrinth seal for the shaft seal of a non-contact dry vacuum pump, 3000r.pm
Since the above rotation can be made possible, a higher vacuum can be obtained, there is less worry about leakage, and there is no need to worry about heat generation or abrasion of the airtight sealing material.

Furthermore, by connecting a contact type dry vacuum pump to the labyrinth seal groove, leaked atmosphere can be exhausted and the contact type dry vacuum pump can be operated efficiently.

Furthermore, the airtightness becomes higher when using a screw 30 or a rotary blade.

[Brief explanation of the drawing]

FIG. 2 is a side view showing the overall appearance of an embodiment of the present invention, FIG. 1 is an enlarged view of the vicinity of the labyrinth seal grooves 21, 22, and 23 in FIG. 2, and FIG. FIG. 4 is a side view showing an embodiment of the second invention, and FIG. 4 is a side view of an embodiment of a composite dry vacuum pump in which a conventional non-contact dry vacuum pump and a contact dry vacuum pump are connected. FIG. 5 shows an enlarged view of the rubber packing 6 in FIG. 4. 1... Screw pump, 2... First stage vane pump, 3... Second stage vane pump, 4... Third stage vane pump, 5... Screw pump drive shaft, 7... Vane pump drive shaft, 6, 8 ... Rubber packing, 9 ... Vacuum inlet, 10 ... Screw pump exhaust port, 11 ... First stage vane pump inlet, 12, 13 ... Pipe, 14 ... Discharge port, 1
5...Pump case, 16...Drive bearing, 17...
...Bearing holder, 21...First stage labyrinth seal groove, 22...Second stage labyrinth seal groove, 2
3... Third stage labyrinth seal groove, 24... First stage exhaust port, 25... Second stage exhaust port, 26... Third stage exhaust port, 27, 28, 29... Exhaust path, 30...
…screw.

Claims (1)

[Claims] 1. In a composite dry vacuum pump that connects a non-contact type dry vacuum pump and a contact type dry vacuum pump, a labyrinth seal groove is provided on the drive shaft of the non-contact type dry vacuum pump, and a labyrinth seal groove is provided in the groove. A labyrinth seal for a non-contact dry vacuum pump, characterized in that it is connected to a contact dry vacuum pump via an exhaust path. 2. In a composite dry vacuum pump that connects a non-contact type dry vacuum pump and a contact type dry vacuum pump, a labyrinth seal groove is provided on the drive shaft of the non-contact type dry vacuum pump, and a labyrinth seal groove is provided in the groove via an exhaust path. A shaft seal for a non-contact type dry vacuum pump, characterized in that a contact type dry vacuum pump is connected to the shaft seal, and a screw or rotary blade mechanism is added to the groove.