JPH02199287A - Screw type pump device - Google Patents

Abstract

PURPOSE:To reduce the size of a pump driving means by a method wherein an intake air regulating valve designed to close when a pressure in a suction port exceeds a given value is mounted in a suction pipe. CONSTITUTION:A casing 5 is provided at the one end with a suction pipe 2 and at the other end with a delivery pipe 4. A pair of male and female screw rotors 7 are rotatably contained in a rotor chamber 6 of a casing 5 in a manner that the screw rotors are engaged with each other in a state to keep a non- contact state with a fine gap therebetween. An intake air regulating valve 10 designed to close when a pressure in a suction port 1 exceeds a given value is situated in a suction pipe 2. This constitution enables reduction of given shaft torque, resulting in the possibility to reduce the size of a pump driving means.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a screw pump device including a screw compressor and a screw vacuum pump suitable for, for example, semiconductor manufacturing, vacuum drying of foods, etc. .

(Prior Art) Conventionally, in the fields of semiconductor manufacturing and food vacuum drying, for example, oil-free screw vacuum pumps have been used to maintain a high level of clean atmosphere.

This screw-type vacuum pump rotatably houses a pair of male and female screw rotors that mesh with each other in the rotor chamber of the casing, and operates without supplying lubricating oil to the rotor chamber. However, it is designed so that it does not flow into the vacuum area at all. That is,
Since there is no supply of lubricating oil into the rotor chamber, a pair of male and female screw rotors are meshed with each other while maintaining a non-contact state due to a small gap between them, and are isolated from the rotor chamber by a sealing means. The rotor shafts are configured to rotate synchronously in opposite directions by meshing synchronous gears attached to both rotor shafts outdoors.

A lubricant flow path including an oil pump, an oil cooler, and an oil filter is provided to lubricate the synchronous gear.

(Problem to be Solved by the Invention) In the conventional device described above, the internal compression ratio is generally constant, so when the vacuum container side is at atmospheric pressure or close to atmospheric pressure, such as during startup, the screw There is a problem in that a large torque is required to drive the rotor, and as a result, a motor with a large shaft output is required.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a screw type pump device in which the screw rotor driving means can be downsized.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a casing with a suction pipe leading to a suction port on one side and a discharge pipe leading to a discharge port on the other side, which is open to both the ports. A pair of male and female screw rotors are housed in a rotor chamber so as to be able to mesh and rotate with each other while maintaining a non-contact state due to a small gap between them, and outside the rotor chamber is separated from the rotor chamber by a sealing means. 1. The two rotors are rotated synchronously in opposite directions by meshing synchronous gears attached to both rotor shafts. In the screw type pump device, the suction pipe is provided with an intake control valve that closes when the pressure in the suction port becomes higher than a predetermined value.

(Example) FIG. 1 shows a screw type vacuum pump according to the present invention,
A pair of male and female screw rotors 7 (in the drawing, only one rotor ) are housed so that they can rotate while meshing with each other while maintaining a non-contact state with a small gap between them, and both rotor shafts are connected to each other in an outdoor room that is separated from the rotor chamber 6 by a sealing means. The loaf shafts are formed to rotate synchronously in opposite directions by means of synchronous gears 8 (only one loaf shaft gear is shown in the drawing) which are attached to the loaf shafts and mesh with each other.

In addition, the suction pipe 2 is connected to the vacuum vessel 9, and an intake control valve IO is provided in the intermediate portion thereof, and the opening degree of the intake control valve IO is controlled by a pressure gauge 11 provided at the suction port I portion so as to be able to detect pressure. It is shaped to adjust. That is, the intake control valve IO is configured to close when the pressure detected by the pressure gauge 11 is higher than a predetermined value. Then, a rotation driving means, for example, a high frequency motor 1 in this embodiment.
2 rotates the male rotor of the screw rotor 7, and rotates the female rotor in synchronization with the male rotor via the synchronizing gear 8, and gas is transferred from the vacuum container 9 to the suction pipe 2. It is designed to be sucked in by a screw rotor 7 through a suction port 1 and discharged from a discharge port 3 into a discharge pipe 4 while being compressed.

By the way, for example, when the apparatus is started up, the pressure inside the vacuum container 9 is at or near atmospheric pressure, and if gas in this state is sucked into the apparatus, an excessive load will be placed on the apparatus. However, in this device, in this case, the intake air control valve 1O is closed, and the pressure inside the suction port 1 is maintained below a predetermined value, so that an excessive load is not applied to the drive section of the device.

In addition, Fig. 2 shows the relationship between the vacuum vessel internal pressure (Torr), the discharge volume II (%) of this device, and the required shaft torque (%), and the two-dot chain line extending from the curve of the required shaft torque P is This shows the situation when there is no suction pressure adjustment by the intake control valve IO, and the required shaft torque increases considerably compared to the case of this device.

On the other hand, since the curve of the discharge volume IQ exhibits a substantially flat characteristic as the pressure increases, there is almost no change due to suction pressure adjustment.

Further, in the above embodiments, a screw type vacuum pump has been described, but the present invention also includes a screw type compressor.

(Effects of the Invention) As is clear from the above description, according to the present invention, a rotor that is open to both ports of a casing having a suction pipe leading to a suction port on one side and a discharge pipe leading to a discharge port on the other side. A pair of male and female screw rotors are housed in a room so that they can rotate while meshing with each other while maintaining a non-contact state with a small gap between them. In a screw type pump device in which synchronized gears attached to a rotor shaft are meshed and rotated synchronously in opposite directions, the suction pipe is provided with an intake control valve that closes when the pressure in the suction port becomes higher than a predetermined value. It is formed by providing.

Therefore, the suction pressure can be adjusted even when the pressure on the vacuuming side is still high, such as when starting up the device, and the required shaft torque can be reduced, making it possible to downsize the pump drive means. play.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing the applied side of the screw type vacuum pump according to the present invention, and Fig. 2 shows the internal pressure of the vacuum container and the discharge capacity Q.
, and the required shaft torque P. 1... Suction port, 2... Suction pipe, 3... Discharge port, 4... Discharge pipe, 5... Casing, 6...
Rotor chamber, 7... Screw rotor, 8... Synchronous gear, 10... Suction control valve.

Claims (1)

[Claims] (1) A pair of male and female screw rotors are installed in a rotor chamber opened to both ports of a casing, which has a suction pipe leading to a suction port on one side and a discharge pipe leading to a discharge port on the other side, with a small gap between them. While maintaining a non-contact state, they are housed so that they can rotate while meshing with each other, and are synchronized in opposite directions by meshing synchronous gears attached to both rotor shafts in an outdoor room that is isolated from the rotor chamber by a sealing means. A screw type pump device configured to rotate, characterized in that the suction pipe is provided with an intake control valve that closes when the pressure in the suction port becomes higher than a predetermined value.