Scroll type vacuum pump

Abstract

To provide a scroll type vacuum pump 10 capable of operating with low power without sliding loss of power, and also capable of eliminating troublesome replacement work for a chip seal.SOLUTION: A labyrinth groove 15c is formed on a tip surface of a revolving wrap 15a and a tip surface of a fixing wrap 16a. Since sealing can be performed in a non contact manner between the fixing wrap 16a and a revolving end plate 15b, and between the revolving wrap 15a and a fixing end plate 16b, there is no sliding loss of power, operation can be performed with low power, and troublesome replacement work for a tip seal can be eliminated. The cross-sectional shape of the labyrinth grooves 15c, 16c is made triangular. A molybdenum-based lubricating coating can be formed uniformly to the required thickness on the inner surfaces of the labyrinth grooves 15c, 16c. Then, by adjusting the thickness of the coating, a clearance between the fixing wrap 16a and the revolving end plate 15b and a clearance between the revolving wrap 15a and the fixing end plate 16b can be adjusted to improve sealability of a closed space 10a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a scroll vacuum pump. [Background technology]

[0002] A scroll vacuum pump 100 disclosed in JP-A-7-332269, JP-A-2007-132220, JP-A-2016-37937, etc. is shown in Fig. 7. An eccentric shaft portion 102 is rotatably assembled to a casing 101 of the scroll vacuum pump 100 and is connected to a drive shaft (not shown) of a motor.

[0003] An orbiting scroll 103 is connected to the eccentric shaft portion 102. The orbiting scroll 103 has a structure in which an orbiting wrap 105 having a spiral shape and a predetermined height is provided upright on a disk-shaped orbiting end plate 104.

[0004] A fixed scroll 106 is fixed to the casing 101. The fixed scroll 106 has a structure in which a fixed wrap 108 having a spiral shape and a predetermined height is provided upright on a disk-shaped fixed end plate 107.

[0005] The fixed scroll 106 and the orbiting scroll 103 are assembled to the casing 101 so that the fixed wrap 108 and the orbiting wrap 105 mesh with each other, and a closed space 109 is defined by the fixed end plate 107 and the fixed wrap 108, and the orbiting end plate 104 and the orbiting wrap 105.

[0006] Further, the casing 101 is provided with an anti-rotation mechanism 110 for the orbiting scroll so that the orbiting scroll 103 revolves without rotating on its axis when the eccentric shaft portion 102 is rotated by the motor.

[0007] In the conventional scroll vacuum pump 100, as the eccentric shaft portion 102 rotates, the closed space 109 moves from the suction port 111 provided on the outer periphery of the fixed scroll 106 toward the discharge port 112 provided in the center of the fixed scroll 106. As the closed space 109 moves, outside air is sucked into the closed space 109 from the suction port 111 and the closed space 109 shrinks, compressing the air in the closed space 109. The compressed air is then discharged from the discharge port 112. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 7-332269 [Patent Document 2] JP 2007-132220 A [Patent Document 3] JP 2016-37937 A Summary of the Invention [Problem to be solved by the invention]

[0009] In the above-mentioned conventional scroll vacuum pump 100, in order to increase the airtightness of the closed space 109, tip seals 113, 114 are attached to the leading end surface of the orbiting wrap 105 and the leading end surface of the fixed wrap 108, and the tip seals 113, 114 are respectively pressed against the orbiting end plate 104 and the fixed end plate 107. The orbiting scroll 103 rotates while the tip seals 113, 114 are in sliding contact with the fixed end plate 107 and the orbiting end plate 104, which generates a sliding loss of power. Furthermore, the tip seals 113, 114 gradually wear out, and therefore it is necessary to stop operation periodically to carry out troublesome replacement work, resulting in poor operating efficiency. SUMMARY OF THE PRESENT EMBODIMENT In view of the above problems, it is an object of the present invention to provide a scroll type vacuum pump which is free from sliding loss of power, can be operated with low power, and can omit the troublesome task of replacing tip seals. [Means for solving the problem]

[0010] The present invention relates to a rotor having a casing, a shaft having an eccentric shaft portion and rotatably assembled to the casing, a fixed scroll having a structure in which a fixed wrap having a spiral shape and a predetermined height is provided upright on a fixed end plate; The orbiting scroll has a structure in which a spiral-shaped orbiting wrap having a predetermined height is provided upright on a orbiting end plate, A fixed scroll is fixed to the casing. The orbiting scroll is integrally connected to the eccentric shaft. The fixed wrap and the swivel wrap are engaged to define a closed space between the fixed wrap, the fixed end plate, the swivel wrap and the swivel end plate; a rotation prevention mechanism for the orbiting scroll is provided so that the orbiting scroll revolves without rotating when the shaft is rotated by the motor; As the shaft rotates, the closed space moves from the intake port on the outer periphery of the fixed scroll to the discharge port in the center of the fixed scroll. A scroll type vacuum pump in which, as the closed space moves, outside air is sucked into the closed space through a suction port, the closed space shrinks, and the air in the closed space is compressed, and the compressed air is discharged from a discharge port, A plurality of labyrinth grooves having a triangular cross-sectional shape are formed on a tip surface of the swivel wrap facing the fixed end plate and on a tip surface of the fixed wrap facing the swivel end plate, The present invention is characterized in that a molybdenum-based lubricating coating is formed to a thickness of 10 to 100 μm on the tip surface of the orbiting wrap having a labyrinth groove, the tip surface of the fixed wrap, the surface of the fixed end plate facing the tip surface of the orbiting wrap, and the surface of the orbiting end plate facing the tip surface of the fixed wrap. Effect of the Invention

[0011] According to the present invention, labyrinth grooves are formed on the tip surfaces of the orbiting wrap and the fixed wrap, so that non-contact sealing can be achieved between the fixed wrap and the orbiting end plate, and between the orbiting wrap and the fixed end plate. As a result, there is no sliding loss of power, so operation can be performed with low power, and the troublesome work of replacing tip seals can be omitted. The labyrinth groove has a triangular cross section, which allows a molybdenum-based lubricating coating to be formed uniformly on the inner surface of the labyrinth groove to the required thickness. By adjusting the thickness of this coating, the clearance between the fixed wrap and the rotating end plate and the clearance between the rotating wrap and the fixed end plate can be adjusted, improving the sealing of the closed space. The thickness is preferably 10 to 100 μm. If the thickness is less than 10 μm, the thickness is small and the clearance formed between the fixed wrap or the orbiting wrap and the end plate due to the processing accuracy becomes large, so that the amount of air leakage becomes large and a sufficient degree of vacuum cannot be obtained. On the other hand, if the film thickness is more than 100 μm, the film thickness is too thick and the molybdenum-based lubricating coating is prone to peeling off from the tips of the fixed wrap and orbiting wrap during operation. [Brief description of the drawings]

[0012] [Figure 1] 1 is a vertical sectional side view of a scroll vacuum pump according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a revolving scroll of the scroll vacuum pump. [Diagram 3] FIG. 2 is a perspective view showing a fixed scroll of the scroll vacuum pump. [Figure 4] 4 is a cross-sectional view taken along line 4-4 in FIG. 1. [Diagram 5] FIG. 2 is an enlarged cross-sectional view of part A in FIG. [Figure 6] FIG. 2 is an enlarged cross-sectional view of part B in FIG. [Figure 7] FIG. 1 is a vertical sectional side view of a conventional crawler type vacuum pump. EXAMPLES

[0013] The present invention will be described below with reference to the drawings. FIG. 1 shows a scroll vacuum pump 10 according to an embodiment of the present invention. A shaft 13 is rotatably mounted to a casing 11 of the scroll vacuum pump by a ball bearing 12. The shaft 13 is provided with an eccentric shaft portion 13a, and an orbiting scroll 15 is mounted to the eccentric shaft portion 13a via a bearing sleeve 14. A fixed scroll 16 is fixed to an opening on the left side surface of the casing 11. The shaft 13 passes through a through hole 27 formed in the fixed scroll 16 and protrudes from the fixed scroll 16, and a cooling fan 17 is connected to the protruding tip portion by a bolt 18. A fan cover 19 is placed over the cooling fan 17. A bearing sleeve 20 is fitted into the through hole 27. An oil seal 21 is provided adjacent to the ball bearing 12, and an oil seal 22 is provided adjacent to the bearing sleeve 14.

[0014] The orbiting scroll 15 has a structure in which a spiral orbiting wrap 15a having a predetermined height is provided upright on a disk-shaped orbiting end plate 15b as shown in Fig. 2. The fixed scroll 16 has a structure in which a spiral fixed wrap 16a having a predetermined height is provided upright on a disk-shaped fixed end plate 16b as shown in Fig. 3. 1 and 4, the fixed scroll 16 and the orbiting scroll 15 are assembled by meshing the fixed wrap 16a with the orbiting wrap 15a so that a closed space 10a is defined by the fixed wrap 16a, the fixed end plate 16b, the orbiting wrap 15a, and the orbiting end plate 15b. This closed space 10a communicates with a suction port 23 provided in the casing 11 on the outer periphery side of the fixed scroll 16 and a discharge port 24 provided in the center of the fixed scroll 16. A rotation prevention crank pin 25 is provided between the orbiting scroll 15 and the casing 11 so that the orbiting scroll 15 revolves without rotating when the shaft 13 is rotated by a motor (not shown).

[0015] An enlarged view of part A in Fig. 1 is shown in Fig. 5. An enlarged view of part B in Fig. 1 is shown in Fig. 6. As shown in Fig. 5, a plurality of labyrinth grooves 16c having a triangular cross-sectional shape are formed in the tip surface of the fixed wrap 16a facing the orbiting end plate 15b. As shown in Fig. 6, a plurality of labyrinth grooves 15c having a triangular cross-sectional shape are also formed in the tip surface of the orbiting wrap 15a facing the fixed end plate 16b.

[0016] A molybdenum-based lubricating coating 26 is formed on the surface of the leading end face of the orbiting wrap 15a in which the labyrinth groove 15c is formed and on the surface of the leading end face of the fixed wrap 16b in which the labyrinth groove 16c is formed. A molybdenum-based lubricating coating 26 is also formed on the surface of the fixed end plate 16b facing the tip end face of the orbiting wrap 15a and on the surface of the orbiting end plate 15b facing the tip end face of the fixed wrap 16a. The thickness of this coating is appropriately selected from the range of 10 to 100 μm.

[0017] The scroll vacuum pump 10 according to this embodiment has the above-described structure, and as the shaft 13 rotates, the closed space 10a moves from the suction port 23 provided on the outer periphery of the fixed scroll 16 toward the discharge port 24 provided in the center of the fixed scroll 16. As the closed space 10a moves, outside air is sucked into the closed space 10a through the suction port 23, and the closed space 10a shrinks, compressing the air in the closed space 10a. The compressed air is then discharged from the discharge port 24.

[0018] According to this embodiment, labyrinth grooves 15c are formed on the tip surfaces of the orbiting wrap 15a and the fixed wrap 16a, so that non-contact sealing can be achieved between the fixed wrap 16a and the orbiting end plate 15b, and between the orbiting wrap 15a and the fixed end plate 16b. As a result, there is no sliding loss of power, so operation can be performed with low power, and the troublesome work of replacing tip seals can be omitted.

[0019] Since the cross-sectional shape of the labyrinth grooves 15c, 16c is triangular, a molybdenum-based lubricating coating 26 can be formed uniformly with a required thickness on the inner surfaces of the labyrinth grooves 15c, 16c. By adjusting this film thickness, the clearance between the fixed wrap 16a and the orbiting end plate 15b and the clearance between the orbiting wrap 15a and the fixed end plate 16b can be adjusted, thereby improving the sealing performance of the closed space 10a.

[0020] The thickness is preferably 10 to 100 μm. If the thickness is less than 10 μm, the film thickness is small, and the clearance between the fixed wrap 16a and the orbiting end plate 15b and the clearance between the orbiting wrap 15a and the fixed end plate 16b caused by machining accuracy becomes large, so that the amount of air leakage increases and a sufficient degree of vacuum cannot be obtained. On the other hand, if the film thickness is more than 100 μm, the film thickness is too thick, and the molybdenum-based lubricating coating 26 is likely to peel off from the tip of the fixed wrap 16a or the orbiting wrap 15a during operation. [Explanation of symbols]

[0021] 10...Scroll type vacuum pump 10a…Enclosed space 11…Casing 12...Ball bearing 13...Shaft 13a...Eccentric shaft part 15...Rotary Scroll 15a…Circling rap 15b... Swivel end plate 15c...Labyrinth groove 16...Fixed scroll 16a…Fixed wrap 16b…Fixed end plate 16c...Labyrinth groove 23…Suction port 24…Discharge port 25...Crank pin for preventing rotation 26...Molybdenum-based lubricating coating 27…Through hole

Claims

[Claim 1] A casing; a shaft having an eccentric shaft portion and rotatably attached to the casing; a fixed scroll having a structure in which a fixed wrap having a spiral shape and a predetermined height is provided upright on a fixed end plate; The orbiting scroll has a structure in which a spiral-shaped orbiting wrap having a predetermined height is provided upright on a orbiting end plate, A fixed scroll is fixed to the casing. The orbiting scroll is integrally connected to the eccentric shaft. The fixed wrap and the swivel wrap are engaged to define a closed space between the fixed wrap, the fixed end plate, the swivel wrap and the swivel end plate; a rotation prevention mechanism for the orbiting scroll is provided so that the orbiting scroll revolves without rotating when the shaft is rotated by the motor; As the shaft rotates, the closed space moves from the intake port on the outer periphery of the fixed scroll to the discharge port in the center of the fixed scroll. A scroll type vacuum pump in which, as the closed space moves, outside air is sucked into the closed space through a suction port, the closed space shrinks, and the air in the closed space is compressed, and the compressed air is discharged from a discharge port, A plurality of labyrinth grooves having a triangular cross-sectional shape are formed on a tip surface of the swivel wrap facing the fixed end plate and on a tip surface of the fixed wrap facing the swivel end plate, A scroll vacuum pump characterized in that a molybdenum-based lubricating coating is formed to a thickness of 10 to 100 μm on a tip surface of a rotating wrap having a labyrinth groove formed therein, a tip surface of a fixed wrap, a surface of a fixed end plate with which the tip surface of the rotating wrap faces, and a surface of a rotating end plate with which the tip surface of the fixed wrap faces.

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