JPH0696963B2 - Scroll fluid machinery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a scroll fluid machine that functions as a compressor, an expander, and a vacuum pump, and more particularly, to a scroll fluid machine that faces a sliding surface of a counterpart scroll. The present invention relates to a scroll fluid machine in which a tip seal is fitted into a wrap end surface through a seal groove having a rectangular cross section.

“Prior Art” Conventionally, as shown in FIGS. 4 (A) and (B), a fixed scroll 10 in which a first wrap 13 is formed in a concave space 12 surrounded by a peripheral wall 11, and the first scroll It comprises an orbiting scroll 20 having a second wrap 21 that can be fitted into the wrap 13, for example a peripheral wall 11 facing the concave space 12 of the fixed scroll 10 and a second wrap 21 located in the central region of the concave space.
The suction port 16 and the discharge port 17 are respectively provided on the sliding surface 14 (bottom surface) of the and the swirl is performed so that the contact point (or the closest contact point) between both wraps functioning as a compression chamber gradually moves toward the center. Fixed scroll 10 with fixed radius 10
By revolving around the center of the wrap 21, the gas introduced from the suction port into the concave space 12 is wrapped around the winding end end 21b (outer end) of the second wrap 13, Taken into the enclosed space 22 formed by
The orbiting scroll 20 is moved toward the center while gradually reducing its volume along with the orbital movement of the orbiting scroll 20.
A scroll-type compressor is known in which the gas in 22 is electrically connected to the discharge port 17 when the pressure in the gas is increased, and the high-pressure gas can be discharged to the outside through the discharge port 17.

In this type of compressor, a sealing groove having a rectangular cross section is formed in a spiral lap end surface 21a facing the sliding surface 14 of the opposite scroll 10 or 20 (the sliding surface on the orbiting scroll 20 side is not shown). 2 is fitted with a strip-shaped tip seal 1, and particularly in an oilless compressor, the tip seal 1 is formed of a strip-shaped self-lubricating material, and as shown in FIGS. 2 (E ₁ ) and (E ₂ ), high pressure is applied. the clearance between the seal groove side wall 2b than enclosed space P ₁ side
By using the back pressure introduced to the bottom side 1a of the tip seal through 3A and 3B, the tip seal 1 is pressed against the sliding surface 14 side to improve the sealing performance of the closed space P ₁ . .

[Problems to be Solved by the Invention] However, since the enclosed space 22 is configured to move toward the center while gradually decreasing its volume along with the orbital movement of the orbiting scroll 20, it is the center. As the gas in the closed space increases in pressure in a substantially geometrical manner as it goes to the region side, the side wall of the seal groove
The back pressure introduced to the tip seal bottom surface 1a side through the gap 32 between the 2b becomes larger as it goes to the central area side. Therefore, especially in the oil-free compressor, the tip seal is self-lubricating resin. Since it is made of a material, the tip seal is likely to wear due to an increase in surface pressure in the central region.
There is a drawback.

If the gap 32 (hereinafter referred to as a clearance) between the tip seal 1 and the seal groove side wall 2b is made small in order to eliminate such a defect, the clearance in the outer peripheral region becomes small, and the clearance in the outer peripheral region becomes small. The sliding resistance of the tip seal up and down becomes large, and the pushing force of the tip seal in this area is smaller than that in the inner area as shown in Fig. 3, and as a result, the tip seal slides between the side walls of the seal groove. It is not possible to obtain an urging force that smoothly presses against the sliding surface side of another scroll against the resistance, resulting in a drawback that the sealing performance (surface pressure) is reduced.

Therefore, it is extremely difficult to set the fitting accuracy of the tip seal without wear of the seal or deterioration of the sealing performance, and even if it can be set, the tolerance becomes extremely strict.

It is conceivable to set the width of the tip seal and the width of the seal groove located on the central area side to be wide as shown in FIG. 4 in order to eliminate the wear of the tip seal due to the increase of the surface pressure in the central area. (Although such a configuration has a different purpose, it is disclosed in Japanese Utility Model Laid-Open No. 60-128995.) Even in this configuration, the clearance is uniform from the center side to the outer peripheral side, so the sealing performance on the outer peripheral side is The drawback of lowering the value remains.

Therefore, it is possible to prevent the deterioration of the sealing performance on the outer peripheral side by increasing the clearance while widening the tip seal and the like on the center side, but as described above when configured in this way. Not only does the amount of gas leaking through the side wall surface of the seal groove 2 increase due to the increase in the clearance on the center side, but even if the tip seal 1 is formed wide as described above, the inclination of the seal changes the surface pressure. Abnormal wear may occur.

In view of the drawbacks of the prior art, it is an object of the present invention to provide a scroll fluid machine which has improved durability and compression efficiency or expansion effect without deterioration of wear and sealing performance of the tip seal.

Another object of the present invention is to provide a scroll fluid machine that can smoothly achieve the above object even when the fitting accuracy of the clearance is set gently.

"Means for solving the problem" The present invention focuses on the fact that any of the problems in the above-mentioned conventional technology are caused by the clearance, and makes the clearances 3A, 3B different between the central area side and the outer peripheral side, On the area side, the clearance 3A is reduced to the bottom of the tip seal.
By suppressing the amount of gas flow flowing into the 1a side, the surface pressure of the seal is properly maintained, thereby eliminating wear on the seal sliding surface and reducing the amount of gas leakage flowing through the seal groove side wall surface 2b. On the other hand, on the other hand, on the outer peripheral side, by increasing the clearances 3A and 3B in reverse, and increasing the amount of gas flow that flows into the tip seal bottom surface 1a side, even if the back pressure is small, the sliding surface It is intended to increase the biasing force biased to the side, thereby eliminating the disadvantage that the sealing performance is deteriorated.

In this case, the idea is a rice cake drawn in a picture unless the range in which the clearance 3B is large is specified.

Therefore, the present inventor considers from the rotational motion of the scroll fluid machine. As described above, the wraps of the fixed scroll 10 and the spiral scroll 20 are arranged 180 ° (1π) out of phase with each other. ° The orbiting scroll 20 revolves while maintaining the contact state between the peripheral surfaces of the wraps 13 and 21 at the phase-shifted positions, in other words, it makes a 2π movement, so that the tip seal 1 has an outer peripheral side and an inner peripheral side. It is assumed that the differential pressure in (3) shows the maximum differential pressure value in the area up to 3π from the lap center end where the tip seal 1 is fitted, more specifically in the area of 1π-3π.

Therefore, it is understood that the area 3A in the above range may be set to be larger than the clearance 3B in at least another area.

Therefore, the second feature of the present invention is that the average clearance at the spiral position from the lap center end to about 3π
3A is set to be smaller than the clearance 3B of the spiral portion on the outer peripheral side thereof, and preferably, the clearance 3A at the spiral position of about 1 to 3π from the center end of the lap is set to the clearance 3B of any other spiral portion, It is set to be smaller than 3C.

By reducing the clearance 3A, the amount of gas leaked through the seal groove side wall surface 2c is significantly reduced, but since the clearance 3A communicates in the spiral direction, it cannot be completely prevented. Very difficult.

Therefore, in claim 3, the pressure applied to the two adjacent surfaces of the tip seal 1 facing the bottom surface 2a and the side wall surface 2b of the seal groove from the central region side in the spiral direction of the tip seal 1 to the outer peripheral side is received. Then, the protruding members 5a and 5b that are elastically compressed are provided on the seal groove side.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be exemplarily described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only thereto, but merely illustrative examples. Nothing more than.

First, set the discharge pressure to 8 kgf / cm ² and the scroll winding number to about 4,
When the orbiting and fixed scrolls are made of aluminum die cast, and the tip seal 1 is an oil-free scroll compressor made of fluororesin, the wrap angle and the inner circumferential side of the seal groove at each angular position are used. When the relationship between the pressure difference and the differential pressure on the outer peripheral side was confirmed, the relationship shown in FIG. 3 was obtained.

The start end of the seal groove, that is, the start end of the tip seal 1 is set at a position 0.75π from the center end of the lap.

As can be understood from this figure, the differential pressure is at the maximum value line from the center end of the lap where the tip seal 1 is fitted,
It is understood that the maximum differential pressure value (7 kgf / cm ² ) is shown in the region of 2π to 3π, and that the differential pressure sharply decreases after exceeding 3π.

On the other hand, in the mean value line of the differential pressure, the pressure gradually rises from the center end, and 2 k at the tip end position of the tip seal 1.
After reaching gf / cm ² , after that, the maximum differential pressure value of 4 kgf / cm ² is shown at the 2π angular position, and then gradually decreases.

Therefore, from the above graph, 3π from the center end of the wrap,
It is understood that the differential pressure is the largest in the angular range of approximately 1 to 3π.

Next, the relationship between the clearances 3A and 3B and the hitting condition of the tip seal 1 will be examined.
The clearance having the optimum hit is different between the central area up to π and its outer circumference, and in the former, the optimum hit surface is obtained when the clearance 3A is in the range of 50 to 120 μm.
When the thickness exceeds 50 μm, the phenomenon that the contact becomes non-uniform was observed.

It is presumed that this is because if the back pressure of the tip seal 1 is high and therefore the clearances 3A and 3B are large, the tip seal tilts due to the back pressure during floating.

On the other hand, in the latter, the clearance 3B is 120 to 180.
An optimum contact surface was obtained in the range of μm, and a phenomenon was observed in which the contact was non-uniform when the thickness was 120 μm or less.

This is because the back pressure of the tip seal 1 is low, and therefore, if the clearances 3A and 3B are small, a gas flow rate that allows floating is not introduced.

Therefore, based on such knowledge, the average clearance 3A at the spiral position from the center end of the lap to about 3π is 50 to 120 μm.
m, clearance 3B of the spiral part on the outer peripheral side is 120 to 180
It can be understood that it may be set to μm.

When the clearance is set uniformly from the central area side to the outer peripheral area as in the conventional case, the clearance is 120
The preferable sealing property cannot be secured unless it is set to μm, but in the present invention, the clearance accuracy can be set freely and roughly within the above range.

In this case, the clearances 3A and 3B may be set by changing the groove width of either the tip seal 1 side, the seal groove side, or both.

For example, FIG. 1 shows an example in which the groove width of the tip seal is changed. In (B), the central region side up to about 3π from the center end is set wide, and the outer peripheral side is narrowed through the step portion, and the above requirements are met. Is satisfied.

In addition, (A) does not set the groove width to a uniform width as described above,
The maximum width is set at the 2π position corresponding to the average value of the differential pressure, and the width is gradually reduced from the point and set. Further, in (C), the groove width is set to 1π to 3 in correspondence with the differential pressure.
The effect of the present invention can be smoothly achieved even if the clearance is set in multiple stages so that the clearance of 3A <3C≈3B ₁ <3B ₂ is set so that the range of π becomes maximum.

FIG. 2 shows another embodiment in which the seal groove is changed. Reference numeral 21a denotes a wrap end surface facing the opposite scroll sliding surface 14, which has a rectangular cross section in a spiral direction along the longitudinal center line. 2 is recessed, and the seal groove is formed by slightly widening and extending from a point approximately 3π from the center end of the wrap via the step portion 2D.

At this time, the expanding direction may be distributed right and left around the axis, but it is preferable to widen only the high pressure side where the gas flow is introduced, that is, only one side, as shown in FIG. 2 (C).

The sealing groove 2B may be gradually widened at the point of 3π, but it is preferable to widen it through the one-sided arcuate step portion for ease of manufacturing.

That is, for example, as shown in FIG. 2 (D), after the seal groove 2A on the central region side is processed by the end mill 31 having a small diameter, the seal groove 2A along the outer periphery of the seal groove 2A on the central region side from the step 2D position is processed. The seal groove 2B can be easily formed by processing with a large-diameter end mill 32.

On the other hand, as shown in FIG. 2 (B), the tip seal 1 is formed of a self-lubricating resin material into a strip having the same width as shown in FIG. The wedge-shaped notch protrusions 5a, 5b alternately along the longitudinal direction.
The notch projections 5a and 5b are configured to be deformable in the expansion direction by receiving the pressure applied from the central region side toward the outer region side in the spiral direction.

As a result, since the notch protrusions 5a and 5b are arranged so as to be displaced from each other on adjacent surfaces, the bottom surface in the central region of the seal member 1 is arranged.
The 1a side high-pressure air can leak in a zigzag manner while alternately moving each surface along the spiral direction, and it is possible to maintain an incompletely sealed state with a labyrinth effect. Further, between the seal member 1 and the seal groove 2 on the high-pressure side wall surface 1b on the side to which the back pressure is applied, there is a structure in which the seal member 1 and the seal groove 2 are elastically and substantially in line contact with each other at predetermined intervals via the notch protrusion 5b. To
The sliding resistance of the sealing member 1 in the pressing direction on the sliding surface 14 side is reduced, and the sliding surface 14 can be pressed against the sealing member 1 with good followability, and the sealing performance is improved.

Further, the cut protrusions 5a and 5b provided on the two adjacent surfaces are given elastic force, and as shown in FIG. 3B, the cut protrusions 5a and 5b are freely movable in response to the pressure on the high pressure side. Since it can be expanded, even if the clearances 3A and 3B between the seal groove 2 and the seal groove 2 are changed as described above, it is possible to absorb the clearances and secure a smooth contact surface with good accuracy. Is.

[Advantages of the Invention] As described above, according to the present invention, it is possible to improve durability and compression efficiency without decreasing the wear and sealing performance of the tip seal, and improve the fitting accuracy of the clearance. Even when set gently, it is possible to secure the smooth sealing property of the tip seal and improve the durability.

Further, although the compressor has been described in detail in the above embodiment, the invention is not limited to this and can be applied to an expander and a vacuum pump.

[Brief description of drawings]

FIGS. 1 (A), (B) and (C) are schematic views showing the relationship between the tip seal and the seal groove according to the embodiment of the present invention, and FIG. 2 is another view in which the seal groove side of the present invention is changed. In the example,
(A) is a perspective view of a main part thereof, (C) is a plan view thereof, and (B).
Is a perspective view showing the outer shape of the chip seal, (D) is an explanatory view showing the manufacturing procedure of the seal groove, (E ₁ ) and (E ₂ ) are (C).
E ₁ is -E _1, E ₂ -E ₂ sectional view. FIG. 3 is a graph showing the relationship between the wrap angle and the pressure difference between the inner circumference side and the outer circumference side of the seal groove at each angular position, and FIGS. 4 (A) and 4 (B) are scrolls to which the present invention is applied. It is explanatory drawing which shows a compressor.

Claims (3)

[Claims] 1. A tip seal is fitted in a seal groove recessed in a rectangular cross section on an end surface of a spiral wrap facing a sliding surface of a mating scroll, and a space between the sliding surface and the lap is inserted through the tip seal. In the scroll type fluid machine for sealing the enclosed space formed in the above, the average clearance at the spiral position from the center end of the lap to about 3π is set to be smaller than the clearance of the spiral portion on the outer peripheral side. And scroll fluid machinery 2. A scroll fluid machine characterized in that a clearance at a spiral position approximately 1 to 3π from a lap center end is set to be smaller than a clearance at any other spiral portion. 3. A tip seal is fitted into a seal groove having a rectangular cross section in the spiral wrap end surface facing the sliding surface of the mating scroll, and the tip seal is inserted between the sliding surface and the lap. In a scroll type fluid machine for sealing the enclosed space formed in, a clearance in the width direction between the seal groove and the tip seal is provided on two adjacent surfaces of the tip seal facing the bottom surface and the side wall surface of the seal groove. A projection member that receives a pressure applied from the central region side toward the outer peripheral side of the tip seal in the spiral direction and is elastically pressed against the seal groove side, and at least the average clearance located on the central region side Is set to be smaller than the average clearance located on the outer peripheral side of the scroll fluid machine.