JPS62265483A - Rotary vane type vacuum pump - Google Patents

Abstract

PURPOSE:To reduce the generation of noise, by a method wherein each discharge opening is disposed in a position where discharge timings are staggered, and a check valve, opened at a pressure exceeding a given value, is located to a discharge opening except a final discharge opening. CONSTITUTION:Discharge openings 12 and 13 are disposed at intervals of a proper distance so that the discharge timings of compressed air discharged from a casing 5 are staggered. A check valve 14 is incorporated in a discharge opening 12 except a discharge opening 13. The check valve 14 is opened when the pressure of compressed air in the casing 5 exceeds an atmospheric pressure. This constitution enables sufficient control of the generation of noise of a pump without using the internal space of an electric motor and a muffler for exclusive use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary vane type vacuum pump.

[Conventional technology]

With rotary vane vacuum pumps, if there is a sudden change in pressure during evacuation, a large amount of noise is generated from the pump discharge port that performs the evacuation action. It is desired to suppress VI sound. Therefore, conventionally, for example,
As disclosed in Publication No. 165269, the air discharged from the discharge port of the vacuum pump is discharged into the inside of the electric motor for driving the vacuum pump, and noise generation is suppressed by utilizing the silencing effect of the internal space of the electric motor. Measures have been proposed to achieve this.

Although such noise generation prevention means have the rationality of allowing the electric motor to also function as a muffler, they have had the following first-order problems.

[Problem that the invention seeks to solve]

That is, according to the prior art described above, when an oil-filled rotary vane vacuum pump is used, oil may be scattered inside the motor along with the discharged air.

In the case of oil-free rotary vane vacuum pumps, vane wear particles enter the motor, resulting in abnormal wear of the commutator due to oil, and vane wear particles adhering to the area around the brushes, causing insulation damage. There was a fear that the resistance would decrease.

The present invention has been made in view of one or more points, and its purpose is to sufficiently suppress the generation of noise from a vacuum pump without using the internal space of the electric motor or a dedicated muffler. The purpose of the present invention is to provide a rotary vane type vacuum pump.

[Means for solving problems]

The above purpose is to arrange a plurality of discharge ports of a one-rotation vane type vacuum pump in the casing of the vacuum pump, and to arrange these discharge ports at positions whose discharge timings are shifted from each other.
This can be achieved by providing check valves that open when a predetermined discharge pressure is applied to the discharge ports other than the final discharge port which has the slowest discharge timing among the discharge ports.

(Function) First, before explaining the present invention in detail, the noise generation phenomenon of the rotary vane type vacuum pump will be explained.The gas sucked from the suction port by the rotation of the rotary vane is compressed in the pump chamber and then transferred to the discharge port. However, the compression ratio at this time is determined by the placement position of the suction port and discharge port in a rotary vane type vacuum pump.Also, the discharge pressure discharged from the discharge port is determined by the pressure of the tank connected to the suction side. (1'l: empty object).Therefore, when the pressure inside the suction side tank is close to the maximum vacuum level, the discharge pressure is slightly higher than atmospheric pressure. When the positional relationship is fixed, when the pressure inside the vacuum tank on the suction side becomes low (state H close to atmospheric pressure), the discharge pressure at the discharge port becomes several times the atmospheric pressure, and as a result, the pressure at the discharge port increases. Instantaneous rapid pressure fluctuations occur and the noise becomes a pest.

However, in the present invention, a plurality of discharge ports are provided with different discharge timings, and check valves are provided in the discharge ports other than the final discharge port among these discharge ports. When the compressed air in the pump chamber (pump chamber pressure) reaches a higher pressure than the atmospheric pressure before reaching the final discharge port, the check valve is opened and compressed air can be constantly discharged from each discharge port at a small pressure. Therefore, the compressed air inside the pump that reaches the final discharge port also remains at a pressure slightly higher than atmospheric pressure, so that the discharge pressure can be constantly reduced and exhausted, and the generation of noise generated from the discharge port can be sufficiently suppressed. Can be done.

In addition, if the pressure inside the pump chamber at the discharge ports other than the l & final discharge ports is not compressed to atmospheric pressure.

The check valve remains closed, in which case the compressed air in the pump will be discharged only from the final outlet.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 is a schematic view of a main part showing the internal structure of a rotary vane vacuum pump which is an embodiment of the present invention, and FIG. 2 is a sectional view showing the overall structure of the above embodiment.

First, the overall structure of this embodiment will be explained based on FIG. 2. 1 is an electric motor for driving a vacuum pump, 2 is an output shaft of the electric motor 1, 3 is a rotor shaft of the vacuum pump, and the rotor shaft 3 is an output shaft. It is connected to 2.

4 is a rotor attached to the rotor shaft 3, and 5 is a casing. The casing 5 is formed into a hollow cylindrical shape, and both ends thereof are closed by covers 6 and 7.

A rotor 4 is arranged in an eccentric state inside an interior 5a of a casing 5. 8 and 9 are bearings that support the rotor 151II3, and 10 is a plurality of vanes arranged on the rotor 4. The vane 1o is slidably held in the radial direction of the rotor 4, and when the rotor 4 rotates, centrifugal force causes vane 10
is adapted to rotate while slidingly contacting the inner surface of the casing 5.

Next, the internal structure of the casing 5 will be described in detail based on FIG. A suction port 11 is disposed at the air suction site of the casing 5, and a first discharge port 12 and a second discharge port 13 are disposed at appropriate intervals in the circumferential direction at the air discharge site. Although not shown, the suction port 11 communicates with a tank for creating a vacuum (suction side tank). Also, casing 5
．． The volume of the internal space 5a of the casing 5 formed by the vane 10, the rotor 4, and the covers 6 and 7 is the same as that of the suction port 11.
The volume gradually increases from the vicinity, reaches the maximum volume near the middle, and gradually decreases as it reaches the discharge ports 12 and 13. Therefore, when the rotor 4 rotates, the gas sucked from the suction port 11 is compressed, and the gas sucked from the suction port 11 is compressed.
pushed in the direction. The discharge ports 12 and 13 are arranged at appropriate intervals in order to shift the discharge timing of the compressed air discharged from the casing 5, and are arranged at appropriate intervals other than the second discharge port (! & final discharge port) 13. A check valve 14 is built into the discharge port 12 . The check valve 14 is connected to the casing 5
The valve is set to open only when the internal compressed air reaches atmospheric pressure or higher.

Next, the operation of the rotary vane vacuum pump of this embodiment will be explained.

As the rotor 4 rotates, the gas sucked from the suction port 11 is compressed, and is discharged from the discharge port 13 and the discharge port 12 (in the case of the discharge port 12, the discharge operation is performed as necessary by the operation described below). . Here, when the pressure of the gas sucked from the suction port 11 is sufficiently small (when the inside of the suction side tank is in a vacuum state), the gas inside the casing 5 is at atmospheric pressure or lower near the first discharge port 12. Since the check valve f, ], 4 does not open, the gas in the casing 5 is not exhausted from the first discharge port 12 and reaches the second discharge port 13, The pressure becomes slightly higher than atmospheric pressure near 13, and is discharged into the atmosphere from the second discharge port 13 with slight pressure fluctuations. In this case, the first discharge port 1
Since the second check valve 14 is closed, atmospheric air does not flow in from the outside.

Next, when the pressure of the gas sucked from the suction port 11 is relatively high (at least atmospheric pressure), the pressure of the gas inside the casing 5 will be slightly higher than the atmospheric pressure even near the first discharge port 12. , the check valve 14 opens, and the gas in the casing 5 is first discharged into the atmosphere from the first discharge port 12 with a slight pressure fluctuation.

Further, the remaining gas in the casing 5 is then pressure-fed to the casing space on the second discharge port 13 side, where the volume gradually decreases, and is released from the second discharge port 13, but some of the gas has already been discharged from the second discharge port 13. Since it is discharged from the discharge port 12 of 1,
The pressure of the compressed air reaching the vicinity of the second discharge port 13 does not become very high (slightly higher than atmospheric pressure 1'!l) and is released from the second discharge port 13.

Therefore, according to this embodiment, the discharge pressure at the discharge port is always slightly higher than atmospheric pressure.

Since gas can be released, sudden pressure fluctuations do not occur at the discharge port, and noise generation can be effectively suppressed. Furthermore, since the gas is not compressed more than necessary, power consumption can also be reduced. Figure 3 is.

The negative pressure on the suction side of the rotary vane type vacuum pump in the above embodiment and the conventional vacuum pump of this type and 11! This is a characteristic diagram showing the relationship between motor inputs, and as shown in the figure, when the negative pressure on the suction side is small (close to atmospheric pressure), the motor input/output is lower in this embodiment than in the conventional example. l! It can be powered by one-cost power. Furthermore, since there is a surplus in terms of output, it is possible to reduce the size and weight of the electric motor, and since the gas is not compressed more than necessary in the pump, heat generation due to unnecessary adiabatic compression can be suppressed to a minimum.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a rotary vane vacuum pump that can sufficiently suppress the generation of %l if in the vacuum pump without using the internal space of the electric motor or a dedicated muffler. .

[Brief explanation of drawings]

Fig. F is a schematic view of the main parts showing the internal structure of the pump section of a rotary vane vacuum pump according to an embodiment of the present invention, Fig. 2 is a partially cutaway sectional view showing the overall structure of the above embodiment, and Fig. FIG. 3 is a characteristic diagram showing the relationship between the suction negative pressure and the motor input of the rotary vane vacuum pump of the above embodiment and the conventional rotary vane vacuum pump. ]... is the motive, 3... rotor axis, 4... rotor,
5 River casing, 10... Vane, 11... Suction port, 12... First discharge port, 13... Second discharge port (
final outlet). , ri 4... check valve 6
, - (1 idiot) 1st Figure 4 - Rotor δ - Gehlen Kun 10 - "Z - Kun A - Reverse double valve quick 271

Claims (1)

[Claims] 1. A rotary vane that includes a rotor eccentrically arranged in a casing and a plurality of vanes arranged on the rotor, and that rotates the vanes together with the rotor to push air sucked into the casing toward the discharge port side. In the vacuum pump of the formula, a plurality of the discharge ports are arranged in the casing, and each of the discharge ports is arranged at a position with a shifted discharge timing, and the discharge timing is the slowest among the discharge ports. A rotary vane vacuum pump characterized in that the discharge ports other than the final discharge port are provided with check valves that open when a discharge pressure equal to or higher than a predetermined pressure is applied.