JPS62157289A - Roots blower for high vacuum - Google Patents

Abstract

PURPOSE:To maintain a balance between the intake side pressure and discharge side pressure and prevent a bursting sound from occurring by continously communicating spaces between blades enclosing the free air of the intake side to cooling communicating sections and not communicating a discharge port to them during the 360 deg. rotation of rotors. CONSTITUTION:A cooling communicating section 8 is provided at an interval from the immediately front side to the immediately rear side in the rotating direction of blades at the angle where the center line C of a casing 1 coincides with center lines Ca of four blades 6 of Roots rotors 5, i.e., the interval 11 of the casing 1; and a cooling communicating section 9 is provided at the interval 12 of a housing 2. Accordingly, during the 360 deg. rotation of the rotors 5 spaces between the blades 6 enclosing the free air of the intake side are continuously communicated to one or both of the cooling communicating passages 8, 9, and a discharge port 4 is not communicated to the cooling communicating sections 8, 9. As a result, the vacuum pressure of the intake side enclosed between the blades of the Roots rotors 5 via the intake outside air from the cooling communicating sections 8, 9 and the pressure on the discharge side become almost equal, thus a bursting sound generated at the discharge port 4 can be prevented due to the balanced pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a roots blower for high vacuum use that includes a pair of four-lobed roots rotors.

(Prior Art) Roots blowers have already been commonly used for high vacuum applications. This is because the Roots blower can obtain a clean high vacuum without contaminating oil or water, but on the other hand, it has poor volumetric efficiency and generates a high amount of heat.

When the Roots blower is used for vacuum, if the discharge flflll is 500+n+n11g, the temperature on the discharge side becomes higher than (environmental temperature+loo'c). Conventionally, a two-lobed or three-lobed Roots blower is used for vacuum purposes, but in order to cope with the temperature rise, a cooling nozzle is provided in the casing, or a communication portion is provided in the housing that constitutes the casing or side wall surface. It is common practice to draw in air such as outside air or cold air due to a pressure difference for cooling.

Also, from the suction hose, you can use the Roots Pro '7r for vacuum.
2. The generated vacuum sucks powder, etc., and the cyclone separates the powder, etc., and drops it into a transport pipe. In the suction conveyor system, the suction conveyor system continues to generate vacuum by entering the suction port of the Roots blower for vacuum, and sends the pressurized air from the outlet of the Roots blower to the transportation pipe described in 111j to transport powder, etc. to the destination. If compensation is not provided by inflowing outside air proportional to the degree of vacuum from the communication part provided on one or both sides of the housing, the air sent from the discharge port to the transport pipe will be at a pressure suitable for transport, for example 0°. 2Kg
/c+n2 cannot be set.

The theoretical amount of air for compensation is expressed by the following equation.

Q = 760/760- HX Q 'Q = Compensation 2
Air volume Q' = Vacuum air volume including suction plate (free air volume) H = Vacuum degree According to the above formula, when the vacuum degree H is 759 In totl g, Q is 760.00
Double 700In+ol1g/i 12.7
0xCrOOInmIIgit 4.7
5 times 500+t+IIt3 n 2.9
It becomes 0 times. υt-C suction port is 500 +o In
When the degree of vacuum is II g, it is necessary to flow in from the communication portion, and it is necessary to increase the amount of air for one compensation by a factor of 2.9 times.

In conventional Roots blowers that can also be used for vacuum purposes, the casing a has an elliptical cross section as shown in Figure 4.7.8, or a cocoon-shaped one with narrow suction and discharge ports as shown in Figure 5.6. Also, as shown in Fig. 1.5.7, a communication part C is provided in the casing a, and as shown in Fig. 6.8, the communication part C is provided in the housing b.
4.5.6, a pair of two-lobed Roots rotor f is used, and fjS7.
As shown in Fig. 8, a rotor using a three-lobed Roots rotor 9 of -S 11 is well known. It is provided in a convex shape near the discharge port of b, and the one in f: tS7 is located slightly away from the discharge port in comparison with the Pt54.5 diagram in casing a, and the one in FIG. 9 is located near the discharge port and suction. Place it in the middle of your mouth.

When using a Roots blower with these configurations for vacuum use, the region x on the suction port side shown by the dotted line is in a vacuum state, and the region y on the discharge port side shown by the white background has a silencer attached to the discharge pipe connected to the discharge port. Since it is connected to, or connected to, the transportation pipe of the conveyor system described above, there is pipe resistance, and the pressure is slightly higher than the outside air pressure, and the temperature is also high.

However, as is clear from FIGS. 4 to 6, the area X communicates with the communication parts c and d is the roots rotor r,
9 occurs frequently during the high-speed oral transmission, so the gas in the slightly high pressure region X is ejected backwards from the communication portions C and d. (The same phenomenon occurs in Fig. 7.8.) On the other hand, the vacuum-like gas x on the suction side trapped by the two-lobed Roots rotor
In the casing configuration shown in PIS4, outside air is sucked in due to the pressure difference between the angles θ-1 and in the casing configuration shown in FIG. 5, it is between the angles θ-2 and -C5. It is difficult to compensate so that the pressure is balanced with the side pressure. However, in the configuration where the communication part d is provided in the housing b as shown in Fig. 6, the conditions are different from those in the communication part C provided in the casing a, so the angle θ-1 for sucking outside air from the communication part d is the angle plotted in Fig. 5. θ−2
Since it can be made larger, the compensation indicated by +'+ij can be made slightly more advantageous. When the three-lobed Roots rotor f shown in Fig. 7 is used and the communication portion C is provided in the casing a,
The angle θ-4 for sucking in outside air can be made larger than in FIGS. 4-6. Also, as shown in Figure 8, 1 this A unong b is connected to
! When the first part d is provided, the angle θ-1 becomes even larger, and the compensation for the outside air is improved accordingly.

However, as shown in the following table, the two-leaf and three-leaf roots rotors are still not satisfactory. This is presumed to be related to the reverse eruption mentioned above.

The following table shows the two-lobed type and the three-lobed type, with each group using the same casing or the same housing. A vacuum roots blower was used, and when the degree of vacuum was 500 + n + n If g, a test was conducted to determine how close the compensation air amount of outside air is to 2.9 times the free air amount (theoretical value).

When the discharge side pressure is 0.00Kg/c+n2, the discharge side pressure is 0.
．． In the case of 20Kg/c+n2, as is clear from the table above (this is a three-lobed type, and when a communication part is provided in the housing, the passing score is finally reached), but any type of Roots blower will correspond to the side of the Roots rotor. ) It is not possible to provide a communication part in the A housing, and it is not possible to provide a communication part in the housing for the multi-stage type.

(Problems to be Solved by the Invention) The present invention provides a vacuum Roots blower using a conventional two-lobed or three-lobed Roots rotor, even if one or both of the casing and the housing are provided with a cooling communication section. The problem of the lack of stable outside air compensation has been overcome, and the objective of the development is to provide stable outside air compensation.

(Means for Solving the Problems) The present invention aims to solve the problems explained in the previous section. Therefore, a four-leaf Roots rotor that is meshed and rotated by a timing gear is provided. At an angle where the center line of the young leaves of the roots rotor coincides with the longitudinal center line of the shuttle 1 circular (cocoon-shaped) casing, that angle (from immediately l1ii 1llllll in the direction of rotation of the young leaves to V<
Casing ``in the section up to Mugi 1 rule, Haunoa 7'
, 7) - Install a cooling communication part that opens into the twin J; During the 360 rotation of the Roots rotor, the air on the suction port side is trapped. The special feature is that the opening of the leaf is constantly communicated with the communication portion and rotated.

(For 1 unit) By using a four-leaf Roots rotor, the present invention can replenish outside air (in an appropriate amount), not only when the communication part is provided in the housing, but also when it is provided in the casing, the theoretical value is higher than that. It has the effect of

That is, to describe the experimental results based on the table shown above, the discharge side pressure is 0. The amount of compensation in the case of OOkε/ctn 2 was 2.88 times the amount of free air when the cooling communication section was provided in the casing, and 2.89 times when the cooling communication section was provided in the housing. Also, the discharge side pressure is 0.
In the case of 20kg/c+n2, the supplementary air amount is 2.94 times the own air amount when the casing is provided with a '& passage section, and 2.95 times when the housing is provided with a communication section. This is also superior to the case where a two-lobed Roots rotor is used, and when the degree of vacuum H is 50 (L+nm 1-1 g), the theoretical compensation amount can be made more than 2.9 times.

(Embodiment) Fig. 1 shows an embodiment of the present invention, in which 1 is a casing that is basically oval shaped and approximates a cocoon shape, 2 is a housing, and 3
4 is a suction port, 4 is a discharge port, and 5 is a pair of four-leaf Roots rotors. C is the center line of the casing 1 in the longitudinal direction, Ca
is the center line of the young leaves 6 of the roots rotor 5.

The present invention provides a cooling communication section that extends from the immediate surface side of the young leaves in the rotation direction of the young leaves at an angle where the center line Ca of the four young leaves of the roots rotor 5 coincides with the center line C of the casing 1. The section 11 of the casing 1 and the section 12 of the housing 2 are different from each other. A communication portion 9 for 11 is provided. Since the cooling multiple connection IJTI section 8.9 is a multi-F1 type and a 113-stage type, it is not possible to provide a communication part in the C-Haunong.
Although it is sufficient to provide a cooling communication portion 8.
9 may be combined to form 'C'.

Vacuum air (free air) on the suction side is trapped between the two rotors and the four-leaf root rotor. : til
It rotates, and at any of the rotation angles illustrated in FIGS. There is no formation of metal that communicates with the cooling communication portion 8 or 9.

(Effects of the present invention) The present invention utilizes a four-leaf Roots rotor;
During 360° rotation of the rotor, the vacuum air (free air) on the suction side is constantly communicated between the leaves with one of the cooling communication portions 8 or 9 or the twin J, and the discharge port 4 is connected to the cooling communication portion 4. Those with vIJ& that do not communicate with communication part 8.9,
The vacuum air pressure on the suction side trapped between the young leaves of the roots rotor is compensated by the outside air sucked in from the cooling communication section until it becomes almost the same pressure as the discharge side, thereby preventing the popping sound that occurs at the discharge port due to pressure balance. It has the effect that it can.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view showing an embodiment of the present invention, Fig. 2.3
The figure is a detailed explanatory diagram of the present invention. Figures 4 to 8 show conventional rJe′/f using a two-lobed or three-lobed roots rotor.
! FIG. 2 is a cutaway side view of the Roots blower. 1→Casing 2→Hanong 3→Suction port 6→Each leaf 8.9→Cooling oil part 11→Section 12→Section C→→Core C→→Core wire Applicant Ann Shit He Co., Ltd. Showa year time

Claims (1)

[Claims] A four-leaf roots rotor is provided which is rotated in mesh with a timing gear, and the center line of each leaf of the roots rotor is rotated at an angle where the center line of each leaf of the roots rotor coincides with the longitudinal center line of an elliptical (cocoon-shaped) casing. A cooling communication section that opens in one or both of the casing and housing is installed in the section from the immediate front side to the immediately rear side in the rotation direction of each angled leaf, and during the 360° rotation of the Roots rotor, the cooling communication section is installed on the suction side. A roots blower for high vacuum use, characterized in that the leaves in which free air is trapped are constantly communicated with the communication portion and rotated.