JP2833940B2 - Vacuum pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump and, more particularly, to a dry pump.

[0002]

2. Description of the Related Art Conventional dry pumps are classified into a one-chamber system and a multi-chamber system. In each case, the principle is the same.

FIG. 3 is a sectional view of a vacuum pump showing an example of the prior art. Conventionally, this type of vacuum pump is, for example, shown in FIG.
, A casing 5 having an inlet 6 and an outlet 7
And two rotors 8 housed in the casing 5 and arranged in parallel with each other and attached via a bearing, and the rotor 8 is attached to the drive shaft 3 exposed from the casing 5 of the rotor 8 and rotates the rotor 8 via the gear 4. And a motor 2. The gap between the casing 5 and the rotor 8 is
To the exhaust port 7 are the same size or gradually narrower.

Next, the operation of the vacuum pump will be described. First, the rotation of the motor 2 causes the rotors 8 to rotate in opposite directions. Due to this rotation, the pressure on the rotor 8 side becomes low, and gas is sucked into the intake port 6 from the outside. The gas that has flowed in from the intake port 6 gradually increases in pressure through the gap between the casing 5 and the rotor 8 by the rotation of the rotor 8 and is discharged from the exhaust port 7.

[0005]

In the above-described conventional vacuum pump, although the sucked gas is gradually compressed and delivered from the exhaust port, the reaction product is liable to adhere to the CVD apparatus using the reaction gas. Reaction products are deposited between the casing and the rotor near the exhaust port due to stagnation or the like near the exhaust port, causing an overload on the motor, often causing the vacuum pump to stop.

An object of the present invention is to provide a vacuum pump that can always operate stably without overloading the motor even when reaction products accumulate.

[0007]

Feature of the present invention SUMMARY OF THE INVENTION, the exhaust and casing having an exhaust port at the other end has an inlet at one end, while rotating parallel to one another rotating shaft housed in the casing A pair whose frustoconical ends are frustoconical
Is a vacuum pump having the rotor of FIG .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a vacuum pump showing one embodiment of the present invention. As shown in FIG. 1, in this vacuum pump, the end of the rotor 1 on the exhaust port 7 side is formed into a truncated conical shape so that the axial gap on the exhaust port 7 side is larger than that on the suction port 6 side. is there. Otherwise, it is the same as the conventional example.

As described above, by increasing the gap between the exhaust port side and the rotor 1 and the casing 5, even if reaction products accumulate, the motor 2 is not overloaded.
The vacuum pump does not stop.

FIG. 2 is a sectional view showing a vacuum pump according to a technique related to the present invention. As shown in FIG. 2, this vacuum pump is provided with a rotor on a part of the casing 5a near the exhaust port 7.
8 of the recess 9 for expanding the gap between the end portion is that setting digit. That is, the recess 9 is provided to further increase the gap between the casing 5a and the end face of the rotor 8.

In the above embodiment, the rotor must be machined symmetrically with respect to the axis in order to balance the rotor. However, in the later embodiments, the balance of the rotation is irrelevant. It is only necessary to provide a dent only at a place where it is easy to perform, and there is an advantage that it is not necessary to consider the balance in processing. In addition, if the recess 9 can be removed, there is an advantage that cleaning can be performed without disassembling after a certain period.

Further, by using such a structure in a process in which a reaction product easily adheres, there is an effect that the life of the dry pump can be extended corresponding to the width of the gap.

[0014]

As described above, the present invention widens the gap between the casing and the rotor where the reaction products are likely to adhere near the exhaust port of the dry pump, so that even if the exhausted reaction products accumulate. In addition, there is an effect that the motor can be stably operated without stopping without giving an overload to the motor.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vacuum pump showing an outline of an embodiment of the present invention.

A vacuum pump in the relevant art to the present invention; FIG Display
A to cross section.

FIG. 3 is a cross-sectional view of a vacuum pump showing an outline of an example of the related art.

[Explanation of symbols]

 1,8 rotor 2 motor 3 drive shaft 4 gear 5,5a casing 6 intake port 7 exhaust port 9 recess

Claims (1)

(57) [Claims] A casing having a 1. A discharge port at the other end has a one end side inlet, an end portion of the exhaust port side while rotating parallel to one another rotating shaft housed in the casing
A vacuum pump comprising a pair of rotors having a truncated cone shape .