JPS648195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a water-sealed Roots blower, and is particularly suitable for high-pressure vacuum use.

(Prior Art) A water-sealing roots blower is known in which a multi-lobed roots rotor such as a two-lobed or three-lobed type is housed in a casing and a water-sealing water supply mechanism for sealing the rotor is provided in the casing. However, there is no one in which a roots rotor is loaded with a pressure-sensitive deformable member as in the present invention.

(Problems to be Solved by the Invention) Unlike rotary pumps, piston pumps, etc., the Roots blower rotates the Roots rotor with a clearance between the inner peripheral wall of the casing and the rotors, and generates negative pressure (vacuum). ) or to obtain compression pressure, and there is almost no wear and tear, but high vacuum and high compression cannot be expected due to the above-mentioned clearance. However, by using a water ring type, the vacuum or compression pressure can be increased, and the cooling effect can also be increased.For example, the vacuum attainment of a non-water ring single-stage Roots blower is said to be about 550 mmHg. However, if it is water-sealed, it is possible to increase it to around 740mmHg, and this has been confirmed through various experiments.

However, the biggest disadvantage of using a water seal type is that water seal water supplied into the casing is trapped by the Roots rotor and generates noise and vibration. That is, as shown in Fig. 7, in the case of a vacuum blower, the water sealed water supplied into the casing tends to flow backward from the discharge side to the suction side on both sides of the Roots rotor, and the water seal water supplied into the casing tends to flow backwards from the discharge side to the suction side on both sides of the Roots rotor, and the water seal water supplied into the casing tends to flow backward from the discharge side to the suction side on both sides of the Roots rotor, and the water seal water supplied into the casing tends to flow backward from the discharge side to the suction side on both sides of the Roots rotor. As the rotor rotates, the water seal s is rapidly compressed by the inner peripheral wall surface of the casing a, the head c of one rotor b, and the recess d between the heads of the other rotor b, resulting in a so-called confinement phenomenon. The confinement of this water seal is also related to the amount of sealed water, and the ultimate vacuum level is 700 mmHg.
The amount of sealed water is required to be 1/1000 of the casing volume, and it is unavoidable because the volume does not shrink due to pressure like a gas body, but the operation noise is enormous. Also, the practical machine is 15Kw~
Some machines have high horsepower such as 30Kw, and the drawback is that the horsepower required to overcome the above-mentioned confinement phenomenon increases, and in addition, vibrations often cause accidents such as breakage of the rotor shaft and damage to bearing members. Of course, various countermeasures have been taken to address these shortcomings. For example, as shown in Figure 8, an axial cut groove e is formed in the head c of the Roots rotor b to rapidly compress the water seal. Some attempts have been made to avoid this and thereby suppress the entrapment noise, but the groove e is formed at a position at the rear in the direction of rotation, avoiding the top surface of the head c so that the effective radius of the head c is not reduced. In addition, there is still a phenomenon of confinement in water that exceeds the volume of the cut groove, so there is a drawback that noise and vibration similar to those described above cannot be avoided. In addition, the 9th
As shown in the figure, there is also a configuration in which a relief hole f is formed in the head c to communicate the discharge side and the suction side through a hollow part g, but in this case, efficiency can be improved by creating an air pocket in the hollow part g, etc. It has the disadvantage of causing severe deterioration. Furthermore, as shown in Fig. 10, in a relatively low-horsepower vacuum Roots blower, the Roots rotor b is made of rubber, which bends under the compressive force of water sealing water, thereby preventing entrapment noise and vibration. There is also a type of rotor, but in this case, the roots rotor becomes fatigued after long-term use and gradually loses its restoring force, increasing the clearance, which has the disadvantage of reducing vacuum efficiency.

(Means for Solving the Problems) In view of the above, the present invention aims to solve the above-mentioned disadvantages caused by the use of water sealing water, and the present invention is to provide a two-lobed type, a three-lobed type, etc. to the casing. In a water-sealed roots blower that houses a multi-lobed roots rotor and is equipped with a water-sealing water supply mechanism for sealing the rotor in its casing, there are several A horizontal hole is formed in the head that is substantially orthogonal to the direction of rotation, a pressure-sensitive deformable member such as an elastic tube or solid rod is loaded into the horizontal hole, and a water seal is provided on the circumferential surface of the head that communicates with the horizontal hole. This structure is characterized by the formation of an entrance and exit, and with this configuration, it is possible to provide a Roots blower that is free from operating noise and vibration.

(Example) Figures 1 to 6 show an example of the present invention using a three-lobed Roots rotor. One side is defined as a discharge side (discharge side) 3, and a pair of Roots rotors 4, 4 are rotated in the meshing direction of the arrow by a timing gear. A circular horizontal hole 7 in the axial direction is provided in the center of three heads 5 of each Roots rotor. The wall thickness of the outer peripheral edge 8 of the horizontal hole 7 is preferably as thin as possible, and approximately 10 mm is appropriate. The head 5 of each leaf shown in the figure has many horizontal rows of water arranged in a staggered manner in the axial direction at angles slightly offset in the direction of rotation from the center line C, at angles offset about 90 degrees, and at angles in between. Water sealing ports 9, 10, and 11 are formed to communicate with the horizontal hole 7, respectively, and shallow grooves 9a to 11a are formed outside the horizontal rows of the water sealing ports 9 to 11 to communicate with each other. Further, a pressure-sensitive deformable member 12 such as an elastic tube or solid rod is tightly inserted into the side hole 7. 3 to 6 illustrate various shapes of the pressure-sensitive deformable member 12, which are made of rubber or plastic that is soft and has restoring elasticity. The pressure-sensitive deformable member 12a shown in FIG. 3 is formed into a tube shape with both ends cut off to match the length of the horizontal hole 7, and the pressure-sensitive deformable member 12b shown in FIG. The pressure-sensitive deformable member 12c in FIG. 5 has the shape of a solid rod with both ends cut to match the length of the horizontal hole 7, and the pressure-sensitive deformable member 12c in FIG. The deformable member 12d is
A plate-shaped forming piece is cut to match the length of the horizontal hole 7, and the seam is brought into contact with the radial direction at an angle to form a tube shape according to Fig. 3.
The shape has an axial seam on the flank.

To explain the operation of this embodiment, a water seal water supply pipe 13 is installed on the suction side 2 of the casing 1, and the water seal water forms a water film on the inner circumference and side surface of the casing 1. Each top end of the head 5 of the Roots rotor 4 is sealed. This water seal water W is discharged little by little from the discharge side 3 in the form of mist, and the discharged amount is replenished from the replenishment pipe 13, and as the roots rotors 4, 4 rotate at high speed in the arrow direction, It is returned to the suction side 2, which is the vacuum side, by the recess 6 between the heads 5 of both rotors 4, 4, and the head 5 rotating in the meshing direction in contact with the recess 6. However, the entrapment of the water seal W is mainly caused by the heads 5 of the Roots rotors 4, 4 which rotate in contact with the water film formed on the inner circumferential surface of the casing 1. The pressure generating portion is indicated by the symbol M.

The confinement phenomenon is not continuous, but occurs as the Roots rotors 4, 4 rotate at high speed, the amount of water sealed in the portion M increases, and the pressure in that portion increases, and its occurrence is approximately periodic. However, in this embodiment, when the amount of water sealed in the portion M increases and the pressure increases due to the rotation of the head 5, a part of the water sealed water W enters the water sealed water inlet/outlet 10, and the pressure further increases. The water seal enters the water seal inlet/outlet 9, and the pressure of the water seal W deforms the pressure-sensitive deformable member 12 as shown in the figure to reduce the amount of pressure water, causing explosive noise and roots rotor 4 due to the entrapment phenomenon. , 4 and their respective axes continue to rotate quietly and smoothly, and the head 5
The high pressure acting on the pressure-sensitive deformable member 12 is removed at the moment when the pressure-sensitive deformable member 12 separates from the inner circumferential surface of the casing 1, and at the same time, the member 12 elastically restores its elasticity and releases water from the water seal mainly through the water seal ports 9 and 10. This process is repeated to prevent noise and vibration from being trapped.

Since the pressure in the M portion increases to 5Kg/cm ² to 10Kg/cm ² , the pressure-sensitive deformable member 12 is formed of a material that can have elasticity to expand and contract in accordance with the water pressure.

Grooves 9a, 10a, 11a are not necessarily required. When creating grooves, if the depth is too large, air pockets are likely to be formed in some areas, which will reduce performance.

The number of water seal inlets and outlets 9, 10, and 11 is determined depending on the size of the Roots rotor 4. In other words, it is not a good idea to have more than necessary. The number of formations is determined by experiment.

(Actions and effects of the present invention) The effects of the present invention are similar to those described in the examples.
This invention has the effect of supplying water to seal the clearance, thereby preventing noise and vibration from being trapped by the water-sealed Roots rotor, which is intended to improve efficiency.

[Brief explanation of drawings]

1 to 6 show embodiments of the present invention, in which FIG. 1 is a vertical sectional side view of a Roots blower, FIG. 2 is a partially cutaway side view of a Roots rotor, and FIGS. The perspective view and FIGS. 7 to 10 are explanatory diagrams of a conventional Roots blower. 1...Casing, 2...Suction side, 3...Discharge side, 4
... Roots rotor, 5... Head, 6... Recess, 7... Horizontal hole, 9, 10, 11... Water seal water inlet/outlet, 12... Pressure-sensitive deformable member.

Claims (1)

[Claims] 1. In a water-sealed roots blower in which a multi-lobed roots rotor such as a two-lobed or three-lobed type is housed in a casing and a water-sealed water supply mechanism is installed in the casing to seal the rotor, the casing of each rotor Horizontal holes are formed in several heads that are in contact with the inner circumferential wall surface and are substantially perpendicular to the direction of rotation, and pressure-sensitive deformable members such as elastic tubes and solid rods are loaded into the horizontal holes, and the heads are A water-seal type roots blower characterized in that a water-seal water inlet/outlet communicating with a side hole is formed on the circumferential surface of the part.