JPH0717981U - Dry vacuum pump - Google Patents

Abstract

(57) [Abstract] [Purpose] Corrosion of the pump material by the coolant for bearing cooling, and prevention of damage by gas products caused by a drop in pump temperature. [Composition] A cooling member having a refrigerant flow path is brought into contact with the outside of an open end surface of a bearing housing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dry vacuum pump that is widely used in semiconductor manufacturing equipment and other vacuum application fields.

[0002]

[Prior art]

 FIG. 2 shows a conventional example of a claw type, which is a type of dry vacuum pump. This is a pump constructed by mounting a pair of rotors 3 and 4 on a drive shaft 1 and a driven shaft 2 arranged in parallel with each other, and enclosing the outer edges of these rotors 3 and 4 with a casing 5. In this embodiment, the pump mechanism is connected in a four-stage tandem on a common shaft. Both ends of the drive shaft 1 and the driven shaft 2 are supported by bearing housing members 8 and 9 via bearings 6 and 7, respectively. The pair of rotors 3 and 4 oppose each other in a non-contact state to perform a pumping action while maintaining a predetermined clearance in the casing 5 to avoid solid contact. Reference numeral 9 is an intake port, and 10 is an exhaust port. The shaft ends of the drive shaft 1 and the driven shaft 2 are connected to each other by timing gears 11 and 12, and by inputting power from a drive source (not shown) to the drive shaft 1, both shafts 1 and 2 rotate in reverse synchronously. In each pump mechanism, however, the gas sucked from the exhaust port 13 of the previous stage through the intake port 14 is compressed and is pumped to the exhaust port 13 'of the next stage. In this case, the pump mechanism at the right end without the exhaust port at the front stage sucks gas from the intake port 14 ', and the pump mechanism at the final stage without the intake port at the next stage, that is, the pump mechanism at the left end pumps gas to the exhaust port 10.

The reason why the pump mechanism is provided in multiple stages in this way is that this type of dry vacuum pump does not use oil, and as described above, secures a sufficient clearance between the rotors 3, 4 and the casing 5. This is because the exhaust efficiency tends to decrease, and this is to compensate for this. Reference numeral 17 is a vacuum sealing cover member.

By the way, in this type of dry vacuum pump, it is necessary to keep the pump temperature high in order to prevent damage from the products generated by the exhaust gas, and therefore the bearing is cooled by cooling water. . Reference numerals 15 and 16 in FIG. 2 denote cooling water return passages for this purpose, which are provided in the left and right bearing housings 8 and 9. On the other hand, the recent trend of the market requires the weight reduction of the entire pump, so aluminum is used for the casing and housing. If a cooling water passage is provided in the bearing housing to cool the bearing, the aluminum material will be corroded by the cooling water.To prevent this, a corrosion resistant coating is applied to the inner surface of the cooling water flow path. It is normal to have.

[0005]

[Problems to be solved by the device]

 The present invention is intended to solve the above-mentioned problem of corrosion of the cooling passage, eliminates the need to replace the entire housing member due to corrosion, and is expensive and corrosion-resistant to prevent corrosion. It was devised to eliminate the costly inner coating of the flow path, and its purpose is to provide a dry vacuum pump with reduced maintenance costs.

[0006]

[Means for Solving the Problems]

 In order to achieve such an object, the present invention eliminates the formation of a refrigerant flow path in the bearing housing part, and applies a small cooling member having a refrigerant flow path inside from the outside of the open end surface of the bearing housing part. It was made to contact.

[0007]

[Action]

 The bearing housing is contact cooled by an external cooling member such as a vacuum seal cover cooled with cooling water. The cooling temperature can be adjusted by the contact area between the bearing housing and the cooling member.

[0008]

【Example】

 An embodiment of this invention will be described below with reference to FIG. Since the basic structure of this pump is almost the same as that shown in FIG. 2, corresponding parts are designated by the same reference numerals.

In the figure, reference numerals 18 and 20 denote elliptical plate-shaped cooling members that form the essential part of the present embodiment. A cooling water return passage 19 is provided in the opening 18, and the open end surface of the bearing housing 8 on the right side is shown. Are abutted via a suitable clamping mechanism (not shown) such as a screw. In this embodiment, this cooling member also has the function of a conventional vacuum sealing cover. Reference numeral 20 is an elliptical plate-shaped cooling member having a spectacle hole which is brought into contact with the open end surface of the left bearing housing 9, and a cooling water return passage 21 is provided therein. In this embodiment, this member 20 also has a function of pressing the bearing 7 from the side.

These members 18 and 20 indirectly cool the bearings 6 and 7 through the respective bearing housings 8 and 9, and the respective cooling capacities appropriately design the contact area between these members and the housing end face. It can be adjusted arbitrarily. Further, in the embodiments, since these cooling members are made of a corrosion-resistant material such as stainless steel, the problem of corrosion due to cooling water can be solved, and since these are small parts as can be seen in the figure, their weight is also a problem. In addition, there is almost no difference in weight reduction. However, if the weight is to be pursued more severely, a material such as aluminum may be used for these cooling members, and if corrosion progresses, only this component may be replaced. Even in this case, maintenance costs are less of an issue because only small parts are needed. Moreover, since these members are only brought into contact with the end surface of the bearing housing, replacement is easy. In some cases, since these members do not receive a large force, it is possible to use a corrosion resistant resin or the like, which can contribute to further weight reduction.

[0011]

[Effect of device]

 As described above, this invention solves the problem of cooling the bearing, which is a cry of dry vacuum pumps used in high temperature conditions, by indirectly contacting the housing end face with a relatively small cooling member provided separately from the bearing housing. As a result, the problem of corrosion by the refrigerant, the problem of reducing the weight of the entire pump, the problem of adjusting the cooling capacity, etc. can be solved all at once, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a sectional view of a dry vacuum pump according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional claw type dry vacuum pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drive shaft 2 ... Drive shafts 3 and 4 ... Rotor 8 and 9 ... Bearing housing 18 ... Right side cooling member (also used as a cover for vacuum seal) 19,21 ... Cooling water return passage 20 ... Left side cooling member (bearing holder) (Combined)

Claims (1)

[Scope of utility model registration request] 1. Two rotating shafts arranged parallel to each other,
A pump mechanism consisting of a pair of rotors that are mounted on these shafts and oppose each other in a non-contact state, and a casing that surrounds the rotors in a non-contact state is connected to a multi-stage tandem on a common shaft in a multi-stage dry system. In the vacuum pump, a dry vacuum pump is characterized in that a cooling member having a refrigerant passage is brought into contact with an open end surface of a bearing housing for bearing the two rotary shafts at both ends thereof.