JP3494457B2 - Vacuum pump device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is suitable for obtaining a clean high vacuum or ultra-high vacuum in an analyzer, an IC manufacturing apparatus, a test apparatus, etc. used in the chemical industry, electronic industry, laboratory, etc. The present invention relates to a vacuum pump device.

[0002]

2. Description of the Related Art Conventionally, as a vacuum pump device of this type,
It is known that a dry reciprocating vacuum pump is used as an auxiliary pump in combination with a turbo molecular pump.

[0003]

In this conventional vacuum pump device, the ultimate pressure of the dry reciprocating vacuum pump is about 100 Pa, which is the limit performance as the auxiliary pump of the turbo molecular pump, and the intake gas is hydrogen. When a light gas such as gas is included, the exhaust speed of the turbo molecular pump is greatly hindered, and there is a problem that the exhaust performance decreases.
In addition, it is technically difficult to lower the ultimate pressure of the dry reciprocating vacuum pump, and there is a problem that the cost is extremely high to improve it.

The present invention solves the above problems, reduces the intake port pressure of a turbo molecular pump by a simple means, and greatly improves the exhaust performance of light gas such as hydrogen gas by the turbo molecular pump. With the goal.

[0005]

Means for Solving the Problems] To achieve the above object the present invention is de turbo molecular pump of the intake gas is lighter gas
In a vacuum device in which an auxiliary pump of a lie reciprocating vacuum pump is connected, an introduction pipe for introducing a specific gas having a large molecular weight is connected to an intake side of the auxiliary pump.

[0006]

When the auxiliary pump is a positive displacement vacuum pump whose performance does not depend on the type of gas, when an appropriate amount of nitrogen gas is introduced from the suction side of the vacuum molecular pump at the ultimate pressure of the turbo molecular pump, The partial pressure of hydrogen gas at the intake port is drastically reduced, which greatly improves the exhaust performance of hydrogen gas.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a turbo molecular pump (hereinafter referred to as TMP).

Reference numeral 2 denotes an auxiliary pump, which is composed of, for example, a dry reciprocating vacuum pump which is a kind of volume transfer vacuum pump.

Reference numeral 3 denotes a vacuum gauge, which measures the degree of vacuum in the chamber 5 communicating with the TMP 1.

Reference numeral 4 denotes an introduction pipe for introducing nitrogen gas into the intake side of the auxiliary pump 2, and reference numeral 6 denotes a mass flow controller (hereinafter referred to as MFC) interposed in the introduction pipe 4 for introducing and adjusting nitrogen gas.

Next, the operation of this embodiment will be described.

When the TMP1 and the auxiliary pump 2 are operated, the gas containing hydrogen gas in the chamber 5 is compressed by the TMP1 and further discharged to the atmosphere by the auxiliary pump 2.

At this time, the pressure in the chamber 5 is measured by the vacuum gauge 3, the nitrogen gas is adjusted by the MFC 6 so that the pressure in the chamber 5 becomes the minimum, and the nitrogen gas is introduced from the intake side of the auxiliary pump. As a result, the intake port pressure of TMP1 is lowered, and the exhaust performance is greatly improved.

The above aspect will be described below with reference to FIGS.

FIG. 2 shows the exhaust speed (Sb) of the auxiliary pump 2.
Intake port pressure (Psb) curve, and Fig. 3 shows hydrogen gas 30P
a1 / s, the nitrogen gas 30 and the back pressure (Pb) and the intake pressure (Pb) of the TMP1 when the gas of 90 Pa1 / s is exhausted.
s) is shown.

Now, the hydrogen gas 30P from the intake port of TMP1
When a1 / s is flowing in, the back pressure (P
b) is 200 Pa at the intersection of this and the characteristic curve sb of the auxiliary pump of FIG. 2, that is, point A, and from FIG.
s) of 53Pa, and the pumping speed of the TMP1 to hydrogen gas _{(S H2)} is

[0018]

[Number I]

From the above, it becomes 0.571 / s.

Next, when nitrogen gas of 30 Pa1 / s is introduced from the intake side of the auxiliary pump 2, 30 Pa of hydrogen gas (Q _H2 ) is supplied to the back pressure side of the TMP1, that is, the intake side of the auxiliary pump 2.
1 / s and 30 Pa1 / s of nitrogen gas (Q _N2 ) are flowing, and this is shown in FIG. 2 and the exhaust speed curve S of the auxiliary pump.
Although the inlet pressure (Psb) of the auxiliary pump 2 is 200 Pa from the intersection with b,

[0021]

[Formula II]

From the back pressure (Pb) of TMP, the hydrogen partial pressure (P
_H2 ) is 100 Pa (point B in FIG. 2), and from FIG. 3, the intake port pressure (Ps) of TMP1 drops to 10 Pa,
Pumping speed of the hydrogen gas in the TMP1 _{(S H2)} is

[0023]

[Formula III]

It is improved to 31 / s.

At this time, the nitrogen gas partial pressure on the back pressure side increases from almost 0 to 100 Pa, but the intake port pressure is not affected at all by FIG.

Similarly, when 90 Pa1 / s of nitrogen gas is introduced from the intake side of the auxiliary pump 2, the back pressure Psb remains 200 Pa from the intersection with the characteristic curve Sb of the auxiliary pump of FIG.

[0027]

[Equation IV]

From the TMP1 back pressure, the hydrogen gas partial pressure
(P _H2 ) is point C in FIG. 2, that is, 50 Pa, and the inlet pressure (Ps) of the TMP1 is reduced to 1.35 Pa from FIG. 3, and the exhaust speed (S) at this time is

[0029]

[Number V]

Is improved to 221 / s.

Thus, the auxiliary pump 2 of FIG. 2 and the T of FIG.
When it is combined with MP1, it has almost no exhaust capability for hydrogen gas, but by introducing nitrogen gas from the intake side of the auxiliary pump 2, the exhaust performance for hydrogen gas is greatly improved.

FIG. 4 shows a second embodiment of the present invention. In this embodiment, a control means 7 composed of, for example, a microcomputer is interposed between the vacuum gauge 3 and the MFC 6 and introduced into the auxiliary pump 2. The flow rate of nitrogen gas is controlled so that the exhaust performance of the TMP1 is maximized, and it has a feature that the exhaust efficiency can be improved.

A storage device is added to the control means 6 to store the Sb-Psb curve corresponding to FIG. 2, and the flow rate in the range where Psb is constant in the Sb-Psb curve of the auxiliary pump of FIG. The sum of the flow rate of hydrogen and the flow rate of nitrogen becomes
The nitrogen gas flow rate is set so that Ps falls within a certain range in the Ps-Pb curve for the nitrogen gas in the preceding TMP1.

In this case, when hydrogen gas is not introduced into the chamber 5, the open / close valve of the MFC 6 is closed.

Further, although nitrogen gas was used as the introduction gas in the above embodiments, a gas having a large molecular weight such as air or argon gas may be introduced instead of the nitrogen gas.

[0036]

As described above, according to the present invention, in a vacuum device in which an auxiliary pump is connected to a turbo molecular pump, a specific gas having a large molecular weight is introduced to the intake side of the auxiliary molecular pump. This has the effect of lowering the intake port pressure and greatly improving the exhaust performance of hydrogen gas or the like of the turbo molecular pump.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a first embodiment of the present invention.

FIG. 2 is a Sb-Psb curve of an auxiliary pump.

FIG. 3 is a Ps-Pb curve of a turbo molecular pump.

FIG. 4 is a schematic diagram of a second embodiment of the present invention.

[Explanation of symbols]

1 Turbo molecular pump 2 Auxiliary pump 4 introduction pipes 6 Mass flow controller 7 Control means

[Number I]

[Formula II]

[Formula III]

[Equation IV]

[Number V]

Continuation of the front page (56) Reference JP-A-4-31394 (JP, A) JP-A-1-219367 (JP, A) JP-A-4-276197 (JP, A) JP-A-2-102385 (JP , A) Actually developed 62-197782 (JP, U) Actually developed 1-118190 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04D 19/04 F04B 37/16

Claims (4)

(57) [Claims] 1. A vacuum device in which a turbo reciprocating pump of a dry reciprocating vacuum pump is connected to a turbo molecular pump of a gas having a light intake gas , and an introduction pipe for introducing a specific gas having a large molecular weight is provided on the intake side of the auxiliary pump. A vacuum pump device characterized by being connected. 2. The vacuum pump device according to claim 1, wherein the light gas is hydrogen gas . 3. A process according to claim 1, characterized in that a control means for adjusting and controlling the introduction amount of a specific gas in the vacuum apparatus also
Is the vacuum pump device according to claim 2 . 4. A vacuum pump apparatus according to claim 1 or claim 2, wherein the specific gas is nitrogen gas.