JP2517745Y2 - Oil-free scroll fluid machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an oil-free scroll fluid machine such as an oil-free scroll vacuum pump or a scroll compressor.

[Conventional technology]

Conventionally, a scroll compressor as an oil-free scroll fluid machine is provided with a casing, a drive shaft rotatably provided in the casing, and a drive shaft rotatably provided on the drive shaft through a bearing boss portion, and is wound around an end plate. -Shaped orbiting wrap portion is fixed to the casing, and a spiral wrap portion is erected on the end plate so as to form a compression chamber while orbiting while overlapping with the wrap portion of the orbiting scroll. And a fixed scroll that is swirled, and while the swirling scroll is swirling, the air sucked from the suction port provided near the winding end of the wrap portion is contained in the compression chamber and gradually compressed in the compression chamber. Then, the liquid is discharged to the outside from a discharge port provided near the winding start end of the wrap portion.

In such a scroll compressor, air is continuously compressed while the compression chamber is gradually contracted, so that the temperature distribution due to the compression heat increases from the suction port toward the discharge port. As a result, in the oil-free scroll compressor that does not cool with oil, the spiral scroll wrap provided on the orbiting scroll and the fixed scroll causes thermal expansion at the center winding start position rather than the peripheral winding end part. It becomes extremely large, and the tooth tips of the lap portion are pressed against the sliding surface of the end plate, which prevents smooth swiveling motion.

Therefore, in the prior art, for example, by forming the dimension from the tooth bottom surface of the wrap portion to the tooth tip so as to gradually decrease from the winding end position on the outer peripheral side toward the winding start position on the center side, or the orbiting scroll. By forming the end plate sliding surface of the fixed scroll in a concave curved shape or in a mortar bottom shape so that the center side is lower than the outer peripheral side, the axial gap between each wrap portion and the orbiting scroll or the fixed scroll wraps. It is set to be larger on the winding start end side than on the winding end end side of the portion so as to avoid contact between the tooth top of the lap portion and the end plate sliding surface due to thermal expansion during compression operation.

[Problems to be solved by the invention]

However, in the above-mentioned prior art, the respective axial gaps between the tooth tips of each lap portion and the end plate sliding surface determine the amount of thermal expansion based on the rising temperature of either the orbiting scroll or the fixed scroll. The axial gaps on the orbiting scroll side and the fixed scroll side are set to the same size.

On the other hand, in the prior art, a bearing boss portion for fitting the orbiting bearing is provided at the center of the rear face of the orbiting scroll end plate,
Moreover, in order to prevent the slewing bearing from being affected by the compression heat, a gap is provided between the end plate and the slewing bearing to form a heat insulating air layer, or a heat insulating material is interposed between the end plate and the bearing boss portion. It adopts the structure to wear.

For this reason, of the orbiting and fixed scrolls that are heated by compression heat, the fixed scroll is wholly cooled by the outside air, whereas in the orbiting scroll, the end plate center part, which is the highest temperature due to heating, is the rear surface. Since the side is insulated as described above, and it is difficult to receive the cooling action by the cooling air by the cooling fan or the like, the side of the end plate sliding surface is hardly cooled.

Thus, as a result of the difference in thermal expansion length between the wrap portion of the orbiting scroll and the wrap portion of the fixed scroll, even if a gap is formed in advance between each tooth tip of the wrap portion and the end plate sliding surface, There is a drawback that the tip of the wrap portion comes into contact with the sliding surface of the end plate of the fixed scroll, or compressed air leaks from one of a pair of compression chambers that are formed at substantially symmetrical positions, resulting in loss of balance. There are drawbacks such as instability, reduction in compression efficiency, and abnormal bearing wear.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and when the orbiting scroll and the fixed scroll are thermally expanded by the compression heat, the axial gaps between the tooth tips of each lap portion and the end plate sliding surface can be made the same. (EN) An oil-free scroll fluid machine in which the pressure in each compression chamber is maintained independently and the orbiting scroll can perform a stable orbiting motion.

[Means for solving problems]

In order to solve the above-mentioned problems, the feature of the configuration adopted by the oil-free scroll fluid machine according to the present invention is that the wrap portion tooth tip of the orbiting scroll is at least at a position radially inward of the bearing boss portion of the orbiting scroll. The axial gap between the fixed scroll and the end plate sliding surface of the fixed scroll is defined as t _b-3, and the axial gap between the fixed scroll wrap tip and the orbiting scroll end plate sliding surface is defined as t _a-. When setting ₃ , t _b-3 ＞ t _a-3
It has been set to the relationship.

[Action]

In the compression chamber defined while the wrap portion of the orbiting scroll and the wrap portion of the fixed scroll overlap and orbit, the compression heat is generated when the gas is compressed.
At this time, the fixed scroll is cooled by the outside air, whereas the end plate center side of the orbiting scroll, particularly in the vicinity of the bearing boss, is hardly cooled. There will be a difference in expansion length.

However, among the axial gaps between the tooth tips of the wrap portion of the orbiting scroll and the end plate sliding surface of the fixed scroll, at least the axial gap located closer to the center than the bearing boss portion with poor cooling efficiency is the wrap of the fixed scroll. Since it was set to be larger than the axial gap between the tip of the tooth and the sliding surface of the end plate of the orbiting scroll, the variations in the axial gap due to the difference in thermal expansion of the wrap portion were corrected to an average state, The pressure can be maintained independently and the orbiting scroll can perform a stable orbiting motion.

〔Example〕

Hereinafter, a scroll compressor as an embodiment of the present invention will be described as an example with reference to the drawings.

In the drawings, reference numeral 1 denotes a casing, and the casing 1
Is composed of a bearing portion 1A, a large-diameter cylindrical portion 1B, and a flange-shaped bearing sliding contact portion 1C projecting inside the large-diameter cylindrical portion 1B.
Reference numeral 2 denotes a drive shaft rotatably supported by the bearing portion 1A via bearings 3 and 4. One end of the drive shaft 2 projects outside the casing 1 and is connected to a motor (not shown), and the other end is The crankshaft 2A projects into the large-diameter cylindrical portion 1B, and the axis O ₂ -O ₂ of the crankshaft 2A is eccentric with respect to the axis O ₁ -O _{1 of} the drive shaft 2 by a distance δ.

5 shows a orbiting scroll provided in the crank shaft 2A and the same axis O ₂ -O _2, revolving scroll 5 is an end plate 6
The spiral side wrap portion 7 is erected on the sliding surface 6A of the end plate 6 with the center side as the winding start end and the outer peripheral side as the winding end end.
And an annular sliding contact portion 6C having a vent hole 8 formed in the radial direction is projected on the outer periphery of the back surface 6B of the end plate 6, and a cylindrical bearing with a bottom is provided in the center through a heat insulating material 9. The boss portion 10 is fixed, and the bearing boss portion 10 and the orbiting scroll 5 are integrated.

Here, the wrap portion 7 of the orbiting scroll 5 is formed so that the tooth tips 7A are in the same horizontal plane over the entire surface, whereas the sliding surface 6A of the end plate 6 is located on the central portion side corresponding to the bearing boss portion 10. It is formed in a concave curve shape or a mortar bottom shape with respect to the outer peripheral side. In other words, the height dimension of the lap portion 7 (tooth tip)
The distance between 7A and the sliding surface 6A) gradually increases from the outer peripheral portion of the end plate 6 toward the central portion.

The orbiting scroll 5 of the embodiment is formed as described above, and is rotatably attached to the crankshaft 2A via the orbiting bearing 11 fitted in the bearing boss portion 10.

Reference numeral 12 denotes a fixed scroll, and the fixed scroll 12 has a mirror plate 13 and a spirally wound wrap portion 14 erected on the sliding surface 13A of the mirror plate 13 with the center side as a winding start end and the outer peripheral side as a winding end. And a flange portion 15 formed on the outer peripheral side of the wrap portion 14. And the fixed scroll
Reference numeral 12 denotes a plurality of compression chambers by overlapping the wrap portion 14 with the wrap portion 7 of the orbiting scroll 5 at a predetermined angle.
The flange portion 15 is fixed to the tubular portion 1B of the casing 1 in a state in which 16, 16 are formed.

Here, similarly to the wrap portion 7 of the orbiting scroll 5, the wrap portion 14 of the fixed scroll 12 is also formed so that the tooth tips 14A are in the same horizontal plane over the entire surface, and the end plate 13 is also formed.
The sliding surface 13A is formed in a concave curve or a mortar shape with respect to the outer peripheral side on the center side, that is, on the side of the discharge port 18 described later. Especially, in the vicinity of the discharge port 18, the end plate sliding surface of the orbiting scroll 5 is formed. It is formed deeper than the center of 7A.

Thus, between the wrap 7 tooth tip 7A of the orbiting scroll 5 and the end plate sliding surface 13A of the fixed scroll 12, and between the wrap tooth tip 14A of the fixed scroll 12 and the end plate sliding surface 6A of the orbiting scroll 5. The axial clearances t _a-1 , t _a-2 , t _a-3 , respectively
t _b-1 , t _b-2 , t _b-3 (however, t _a-1 <t _a-2 , t _a-2 <t _a-3 , t
_b-1 <t _b-2 , t _b-2 <t _b-3 ) are formed, and the orbiting scroll 5 is positioned radially inward of the bearing boss portion 10.
Axial gap t between the tooth tip 7A of the wrap portion 7 protruding from the end plate 5 and the center side of the end plate sliding surface 13A of the fixed scroll 12
_b-2 and tb _-3 are axial gaps between the wrap portion 14 of the fixed scroll 12 and the tooth top 14A and the end plate sliding surface 7A of the orbiting scroll 5.
It is set to be larger than t _a-2 and t _a-3 , that is, t _b-2 > t _a-2 and t _b-3 > t _a-3 .

Reference numerals 17 and 18 denote a suction port and a discharge port projecting from the fixed scroll 12, the suction port 17 communicates with the outermost compression chamber 16 and the discharge port 18 communicates with the most central compression chamber 16. ing.

Next, 19 is a sliding bearing for receiving the load of the orbiting scroll 5 in the thrust direction. The sliding bearing 19 is the casing 1.
It is provided between the bearing sliding contact portion 1C and the annular sliding contact portion 6C of the orbiting scroll 5, and the annular sliding contact portion 6C swivels on the slide bearing 19.

In the figure, 20 is a drive shaft 2 for cooling the inside of the casing 1.
A cooling fan fixedly attached to the cooling fan 21 is a counter weight provided on the cooling fan 20 in order to balance the mass of the orbiting scroll 5. Further, 22 and 22 are a plurality of intake passages axially bored in the top surface of the large-diameter cylindrical portion 1B, and 23 and 23 are large-diameter cylindrical portions 1B.
In the exhaust passage bored in the radial direction of B, the cooling air flows in the casing 1 through the intake passage 22, the ventilation hole 8 and the exhaust passage 23 by the rotation of the cooling fan 20. .

The scroll compressor according to this embodiment is constructed as described above, and its operation will be described below.

When the motor is rotated, the rotation is transmitted to the orbiting scroll 5 via the drive shaft 2 and the bearing 11, and the orbiting scroll 5 makes a relative circular motion with respect to the fixed scroll 12 about the axis O ₁ -O _1. To do. Then, the air sucked from the suction port 17 is gradually compressed in the compression chamber 16 and discharged from the discharge port 18. During this compression operation, the orbiting scroll 5 and the fixed scroll 12 are gradually heated by the compression heat, the temperature distribution increases from the suction port 17 toward the discharge port 18, and the wrap portions 7 and 14 respectively.
The thermal expansion of the winding start portion, that is, the portion forming the compression chamber 16 on the most center side becomes extremely large.

Therefore, according to the embodiment, the tooth tips 7A, 1 of the respective wrap portions 7, 14 are
Axial gaps t _a-1 , t _a-2 , t _a-3 and t _b-1 , t _b-2 , t _b are calculated in advance in consideration of thermal expansion between 4A and the sliding surfaces 6A, 13A of the end plate. _-3 and formed. Furthermore, since the temperature distribution is at the highest position and the heat insulating material 9 is in close contact, the tip 7A of the wrap 7 and the end plate of the fixed scroll 12 located at the center of the end plate 6 of the orbiting scroll 5 having poor heat dissipation efficiency. The axial gaps t _b-2 and t _b-3 between the sliding surface 13A and the wrap portion 14 of the fixed scroll 12 which are cooled by the outside air, and the tip 14A of the scroll and the end plate sliding surface 6A of the orbiting scroll 5 are since it is set the axial clearance greater than _{t a-2, t a-} 3, the clearance _{t b-2, t b-} 3, t a-2, t a-3 by the fixed scroll and the orbiting scroll 5 side 12 The difference in thermal expansion on the side can be corrected. Therefore, during steady operation, a uniform axial gap can be secured between the tooth tops 7A, 14A of the lap portions 7, 14 and the end plate sliding surfaces 13A, 6A, and compressed air from some of the compression chambers 16 can be compressed. Since it is possible to prevent excessive leakage, the pressures in the pair of compression chambers formed at substantially symmetrical positions around the discharge port 18 become substantially equal, and the orbiting scroll 5 can perform a stable orbiting motion. . Therefore, it is possible to improve the compression efficiency and prevent abnormal wear of the slewing bearing 11 and the slide bearing 19.

In the embodiment, the axial gap t between the wrap portion 7 of the orbiting scroll 5 and the end plate sliding surface 13A of the fixed scroll 12 is t.
_{Of the b-1} , t _b-2 , t _b-3 , the axial gaps t _b-2 , t _b-3 located closer to the center than the bearing boss 10 are provided with the wrap portion 14 of the fixed scroll 12 and the orbiting scroll 5. Although it is set to be larger than the axial gaps t _a-2 , t _a-3 between the end plate sliding surface 6A of the other, depending on the temperature distribution of the orbiting scroll 5, other axial gaps t _a-1 , t _{b- 1} to t
The relationship may be set such that _b-1 > t _a-1 .

In the embodiment, the orbiting scroll 5 and the bearing boss portion 10 are separate scroll compressors, but the bearing boss portion 10 is integrally formed on the rear plate 6B of the orbiting scroll 5 or the scroll compressor. The present invention can also be applied to a vacuum pump.

[Effect of device]

As described in detail above, the axial gap between the tooth tip of the wrap portion of the orbiting scroll and the end plate sliding surface of the fixed scroll is radially inward of the bearing boss portion where cooling efficiency is poor.
Since tb _-3 is set to be larger than the axial gap ta _-3 between the tooth tip of the wrap portion of the fixed scroll and the end plate sliding surface of the orbiting scroll, it is fixed like the end plate of the orbiting scroll. Because the heat dissipation is worse than the center side of the scroll end plate,
Even if the wrap portion of the orbiting scroll has a larger thermal expansion than the wrap portion of the fixed scroll, all the axial gaps between the tooth tops of the scroll wrap portion and the end plate sliding surface are made uniform during compression operation. The size can be corrected, the compressed air can be prevented from leaking from the compression chamber, the compression efficiency can be improved, and the orbiting motion of the orbiting scroll can be stabilized to prevent abnormal wear of the orbiting bearing and the sliding bearing.

[Brief description of drawings]

FIG. 1 is a sectional view of a scroll compressor according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part in FIG. 1 ... Casing, 2 ... Drive shaft, 5 ... Orbiting scroll, 6
... End plate, 7 ... Wrap part, 10 ... Bearing boss part, 12 ... Fixed scroll, 13 ... End plate, 14 ... Wrap part, t _a-1 , t _a-2 , t _a-3 ,
t _b-1 , t _b-2 , t _b-3 … Axial clearance.

Claims (1)

(57) [Scope of utility model registration request] 1. A casing, a drive shaft rotatably provided on the casing, and a drive shaft rotatably provided on the drive shaft via a bearing boss portion, and a spiral wrap portion is erected on an end plate. An oil-free scroll composed of an orbiting scroll, and a fixed scroll fixed to the casing and having a spiral wrap portion erected on an end plate so as to form a compression chamber while overlapping with the wrap portion of the orbiting scroll and orbiting. In a scroll fluid machine, the axial gap between the tooth tip of the wrap portion of the orbiting scroll and the end plate sliding surface of the fixed scroll is t _b-3 at a position at least radially inward of the bearing boss portion of the orbiting scroll. And when the axial gap between the tooth tip of the wrap portion of the fixed scroll and the end plate sliding surface of the orbiting scroll is t _a-3 ,
An oil-free scroll fluid machine characterized by having a relationship of t _b-3 > t _a-3 .