Oil free type scroll compressor

Abstract

To provide an oil free type scroll compressor which improves adhesion between a fixed scroll and a revolving scroll to prevent leak from a small gap.SOLUTION: An oil free type scroll compressor 1 of the invention includes: a fixed scroll 20 in which a fixed lap 22 is erected; a revolving scroll 30 in which a revolving lap 30 is erected; a housing 12; a main crank 40 which eccentrically rotates the revolving scroll 30; and an auxiliary crank 50 which prevents autorotation of the revolving scroll 30. A compression spring 60 is disposed between a rotary shaft bearing 52 and an auxiliary crank pin bearing 54 of the auxiliary crank 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an oil-free scroll compressor that performs an eccentric orbiting motion for compressing air that is sensitive to impurities such as oil mist and is used, for example, in air compressors, gas compressors, and vacuum pumps. [Background technology]

[0002] In response to the demand for clean compressed air in the medical, food-related and other fields, oil-free scroll compressors that use solid lubricants instead of oil to lubricate the compressor have long been known, as disclosed in, for example, JP-A-9-228966 (Patent Document 1), and there is a growing demand for scroll compressors, which are particularly excellent in terms of efficiency and quietness.

[0003] In oil-free scroll compressors, it is known to provide tip seals at the tips of the fixed wrap and the orbiting wrap for the purposes of preventing leaks, making sliding smooth, and preventing wear due to contact, and it is known to use materials with excellent lubricity and wear resistance, for example, as in the invention described in JP 2002-174188 A (Patent Document 2). Such tip seals also act to float due to the pressure difference between the compression chambers, maintaining the sealing performance between the compression chambers.

[0004] In addition, after the orbiting movement, pressure is generated between the fixed scroll and the orbiting scroll, and a thrust load is applied to the auxiliary crank due to the force that tries to separate the two scrolls. Therefore, for example, an invention described in JP 11-101185 A (Patent Document 3) is known in which an angular bearing that can withstand thrust loads is used as a bearing for the auxiliary crank.

[0005] Japanese Patent Laid-Open Publication No. 2023-056437 (Patent Document 4) previously filed by the applicant of the present application also discloses, as a conventional example, an oil-free scroll compressor 1A using an angular bearing as shown in FIG.

[0006] Angular bearings can support both radial loads and unidirectional thrust loads, and by combining them, the thrust load resistance can be improved. However, angular bearings are relatively costly, and when used in combination, the number of parts increases, leading to further cost increases.

[0007] Therefore, the applicant of the present application proposed a scroll compressor 1B as shown in Fig. 7 in the above-mentioned Patent Document 4. The basic structure of scroll compressor 1B is similar to that of scroll compressor 1A shown in Fig. 6, but differs in that each bearing does not use an angular bearing but an ordinary radial ball bearing, and that it has an introduction hole through which compressed fluid can be introduced from a high-pressure section, and a piston that is pushed down by the pressure of the compressed fluid to apply a thrust load to the main crank pin bearing.

[0008] According to the scroll compressor 1B, the thrust load, which was conventionally supported at three points on the auxiliary crank, is supported at a total of four points, that is, the main crank and three points on the auxiliary crank. By distributing the thrust load on the auxiliary crank, the durability of the auxiliary crank is improved. In addition, by changing the type of bearing to a radial ball bearing, the number of bearing parts can be reduced, which contributes to cost reduction.

[0009] However, in Patent Document 4, no emphasis is placed on the adhesion between the fixed scroll and the orbiting scroll in the scroll compressor 1B, and it cannot be denied that there is a possibility that pressure will be generated between the fixed scroll and the orbiting scroll after the orbiting movement, and that the force that moves the two scrolls apart will cause leakage from the small gap between the fixed scroll and the orbiting scroll.

[0010] On the other hand, it is conceivable that a force pushing up the orbiting scroll would be generated as a reaction to the force pushing down on the piston, thereby preventing leakage from small gaps. However, it is expected that it would be difficult to obtain a sufficient pushing up force when the pressure in the introduction hole is low, for example, at the start of operation. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 9-228966 [Patent Document 2] JP 2002-174188 A [Patent Document 3] Japanese Patent Application Publication No. 11-101185 [Patent Document 4] JP 2023-056437 A Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide an oil-free scroll compressor that improves the adhesion between the fixed scroll and the orbiting scroll to prevent leakage from minute gaps. [Means for solving the problem]

[0013] The oil-free scroll compressor according to the present invention, which has been made to solve the above problems, comprises: a fixed scroll having a spiral-shaped fixed wrap provided on a surface of a fixed side end plate; an orbiting scroll disposed opposite the fixed scroll and having a spiral orbiting wrap standing on a surface of a rotating side end plate, the spiral orbiting wrap forming a plurality of compression chambers between the orbiting scroll and the fixed orbiting wrap; a housing disposed opposite the fixed scroll with the orbiting scroll therebetween; a main crank that eccentrically rotates the orbiting scroll about the main crank pin bearing, the main crank pin being eccentrically held in the housing so as to be axially rotatable via a drive shaft bearing and a main crank pin formed eccentrically at the tip of the main crank pin being inserted into a central boss portion erected at a central position on the back surface of the orbiting side end plate so as to be eccentrically rotatable via a main crank pin bearing; a plurality of auxiliary cranks, each of which is located outside the main crank and has a rotating shaft rotatably held in the housing via a rotating shaft bearing, and an auxiliary crank pin formed eccentrically at the tip of the rotating shaft is rotatably held in an eccentric shaft manner via an auxiliary crank pin bearing inserted into an outer boss portion erected on the back surface of the rotating side end plate, for preventing the main crank from rotating the orbiting scroll on its axis, An oil-free scroll compressor in which a fluid introduced into the compression chamber is sequentially transferred to a center and compressed, and the fluid compressed in a high pressure section formed at a center of the fixed scroll and the orbiting scroll is discharged from a discharge port formed at a center of the fixed scroll, A compression spring is disposed between the rotary shaft bearing of the auxiliary crank and the auxiliary crank pin bearing.

[0014] According to the present invention, by using a compression spring to push the rotating scroll toward the fixed scroll, the adhesion between the fixed scroll and the rotating scroll is increased, and leakage from small gaps can be effectively prevented by resisting the force tending to separate the two scrolls.

[0015] In the present invention, there is provided a flange formed on the auxiliary crank, and a retaining member attached to the outer periphery of the auxiliary crank and movable in the axial direction of the auxiliary crank, and when the compression spring is externally mounted on the auxiliary crank and disposed between the flange and the retaining member, the compression spring can be prevented from falling off the auxiliary crank while the retaining member prevents unnecessary friction, thereby pushing up the orbiting scroll toward the fixed scroll.

[0016] In the present invention, when a tip seal having a T-shaped cross section is provided, and a groove is formed at the tip of the fixed wrap and the tip of the swirl wrap, and the narrow portion of the tip seal is inserted into the groove of the fixed wrap and the groove of the swirl wrap, respectively, the tip seal can improve sliding properties and prevent contact wear, and can more effectively prevent leakage from small gaps. Effect of the Invention

[0017] According to the present invention, the orbiting scroll is pushed up toward the fixed scroll against the force acting to separate the two scrolls, thereby making it possible to effectively prevent leakage from minute gaps. [Brief description of the drawings]

[0018] [Figure 1] 1 is a longitudinal sectional view showing an embodiment of an oil-free scroll compressor according to the present invention. [Diagram 2] FIG. 2 is a partial enlarged view of the embodiment shown in FIG. [Diagram 3] 2 is a schematic plan view showing the arrangement of auxiliary crank pins in the embodiment shown in FIG. 1; [Figure 4] 2A and 2B are a perspective view and a cross-sectional view, respectively, of a compression spring in the embodiment shown in FIG. 1. [Diagram 5] 2A and 2B are a perspective view and a cross-sectional view showing a pressing member in the embodiment shown in FIG. 1. [Figure 6] FIG. 1 is a vertical cross-sectional view showing a conventional example of an oil-free scroll compressor. [Figure 7] FIG. 2 is a vertical cross-sectional view showing another conventional example of an oil-free scroll compressor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] FIG. 1 shows a vertical cross-sectional view of an oil-free scroll compressor according to an embodiment of the present invention.

[0021] The scroll compressor 1 is composed of a cylindrical case 10 having a cover body 11 and a housing 12, a fixed scroll 20 having a spiral fixed wrap 22 standing on the surface of a fixed side end plate 21 that corresponds to the bottom surface of the cover body 11, a rotating scroll 30 arranged opposite the fixed scroll 20 and having a spiral orbiting wrap 32 standing on the surface of a rotating side end plate 31 that forms a plurality of compression chambers 2 between the fixed wrap 22, a main crank 40 arranged in the center of the housing 12 and having a drive shaft 61 rotatably held in the housing 12 via a drive shaft bearing 42 and having a main crank pin 43 formed eccentrically at its tip, and a plurality of auxiliary cranks 50 arranged at outer positions around the main crank 40 and having a rotating shaft 51 rotatably held in the housing 12 via a rotating shaft bearing 52 and having an auxiliary crank pin 53 formed eccentrically at its tip.

[0022] The present invention is characterized in that a compression spring 60 is attached between a flange 55 formed on the base end side of the auxiliary crank 50, which faces the housing 12, and a retaining member 56 attached to the outer periphery of the auxiliary crank pin 53 and movable in the axial direction of the auxiliary crank pin 53.

[0023] Another feature of the present invention is that grooves 23, 33 are formed in the tip end of the fixed wrap 22 and the tip end of the orbiting wrap 32, and a tip seal 70 is attached to the grooves 23, 33.

[0024] Below the scroll compressor 1, there is a motor 3 which shares the case 10 and rotates the main crank 40.

[0025] The main crank pin 43 is held eccentrically rotatably via a main crank pin bearing 44 inserted into a central boss portion 34 provided in a vertical position at the center of the back surface of the rotating side end plate 31, and the rotating scroll 30 can be eccentrically rotated on the main crank pin bearing 44.

[0026] The auxiliary crank pin 53 is held rotatably on an eccentric shaft via an auxiliary crank pin bearing 54 inserted into an outer boss portion 35 provided on the back surface of the rotating side end plate 31, thereby preventing the main crank 40 from rotating the rotating scroll 30 on its axis.

[0027] A plurality of the auxiliary cranks 50 are provided in order to stably support the fixed scroll 20 and the orbiting scroll 30, and three are provided in this embodiment (see FIG. 2).

[0028] When the main crank 40 is driven to rotate by the motor 2, the rotation of the main crank 40 is transmitted to the orbiting scroll 30 from the main crank pin 43 formed on the orbiting scroll 30 side of the main crank 40 via the main crank pin bearing 44, and the orbiting scroll 30 is prevented from rotating on its own axis by the auxiliary cranks 50, and the three auxiliary cranks 50 are spaced apart from each other at a predetermined interval, maintaining the plane formed on the orbiting scroll 30 in parallel and perpendicular directions, while maintaining a small gap with the fixed scroll 20, and performs eccentric orbital motion that describes the radius of rotation of the main crank 40, centered on the axis of the main crank 40.

[0029] Furthermore, due to this eccentric orbiting motion, the compression chamber 2 is continuously reduced in size, and as the orbiting scroll 30 orbits, the fluid introduced into the compression chamber 2 is sequentially transferred to the center and compressed. Thereafter, in the high-pressure section 4 formed in the center of the fixed scroll 20 and the orbiting scroll 30, the compressed fluid is discharged from the discharge port 5 formed in the center of the fixed scroll 20 to an external air tank or the like. This is an oil-free scroll compressor.

[0030] The compression spring 60 is a compression coil spring having a non-circular cross-sectional shape (see FIG. 4), the inner diameter side of which is loosely fitted into the auxiliary crank pin 53 to prevent the compression spring 60 from falling off the auxiliary crank 50, and is arranged so that one end 61 contacts the flange 55 and the other end 62 contacts the retaining member 56.

[0031] The retaining member 56 is a cylindrical member with a flange on one side, having a cylindrical portion 56a and a flange portion 56b extending in the centrifugal direction from one end of the cylindrical portion 56a (see FIG. 5). The cylindrical portion 56a is attached to the outer periphery of the auxiliary crank pin 53 and is movable in the axial direction of the auxiliary crank 50.

[0032] The compression spring 60 exerts a biasing force, via the retaining member 56, that pushes up the orbiting scroll 30 toward the fixed scroll 20. More precisely, the compression spring 60 pushes up the auxiliary crank pin bearing 54, which is in contact with the retaining member 56, via the retaining member 56.

[0033] By interposing the pressure member 56 between the compression spring 60 and the rotating scroll 30 rather than directly contacting the rotating scroll 30, the pressure member 56 can prevent unnecessary friction and push the rotating scroll 30 up toward the fixed scroll 20.

[0034] At this time, the compression spring 60 has a rectangular cross-sectional shape, so that it can exert a high biasing force with a short free length.

[0035] In this way, by pushing the rotating scroll 30 toward the fixed scroll 20 by the biasing force of the compression spring 60, against the force tending to separate the two scrolls, leakage from small gaps that exist between the fixed side end plate 21 and the tip of the rotating wrap 32, or between the rotating side end plate 31 and the tip of the fixed wrap 22, can be effectively prevented.

[0036] The tip seal 70 has a T-shaped cross section having a narrow portion 71 and a wide portion 72, and is a member formed in a string or spiral shape from a material with excellent lubricity and abrasion resistance such as PTFE, and in this embodiment, two are provided, one on the side of the fixed wrap 22 and the other on the side of the swirl wrap 32. The narrow portion 71 is inserted into the groove 23 at the tip of the fixed wrap 22 and the groove 33 at the tip of the swirl wrap 32 and attached.

[0037] Therefore, when the fixed scroll 20 and the orbiting scroll 30 slide due to the eccentric orbiting motion of the orbiting scroll 30, the wide portion 72, which is formed to approximately match the width of the tip of the fixed wrap 22 and the width of the tip of the orbiting wrap 32, slides in contact with the opposing fixed side end plate 21 or orbiting side end plate 31, thereby effectively improving the sliding properties and preventing contact wear by the tip seal 70, and further effectively preventing leakage from small gaps.

[0038] As described above, according to the present invention, the orbiting scroll is pushed up toward the fixed scroll against the force acting to separate the two scrolls, thereby making it possible to effectively prevent leakage from minute gaps. [Explanation of symbols]

[0039] 1 scroll compressor, 2 compression chamber, 3 motor, 4 high pressure section, 5 discharge port, 10 case, 11 cover, 12 housing, 20 fixed scroll, 21 fixed side end plate, 22 fixed wrap, 23 groove, 30 orbiting scroll, 31 orbiting side end plate, 32 orbiting wrap, 33 groove, 34 central boss portion, 35 outer boss portion, 40 main crank, 41 drive shaft, 42 drive shaft bearing, 43 main crank pin, 44 main crank pin bearing, 50 auxiliary crank, 51 rotating shaft, 52 rotating shaft bearing, 53 auxiliary crank pin, 54 auxiliary crank pin bearing, 55 flange, 56 retaining member, 56a cylindrical portion, 56b flange portion, 60 compression spring, 61 one end, 62 other end, 70 tip seal, 71 narrow width portion, 72 Wide section

Claims

1. a fixed scroll having a spiral-shaped fixed wrap provided on a surface of a fixed side end plate; an orbiting scroll disposed opposite the fixed scroll and having a spiral orbiting wrap standing on a surface of a rotating side end plate, the spiral orbiting wrap forming a plurality of compression chambers between the orbiting scroll and the fixed orbiting wrap; a housing disposed opposite the fixed scroll with the orbiting scroll therebetween; a main crank that eccentrically rotates the orbiting scroll about the main crank pin bearing, the main crank pin being eccentrically held in the housing so as to be axially rotatable via a drive shaft bearing and a main crank pin formed eccentrically at the tip of the main crank pin being inserted into a central boss portion erected at a central position on the back surface of the orbiting side end plate so as to be eccentrically rotatable via a main crank pin bearing; a plurality of auxiliary cranks, each of which is located outside the main crank and has a rotating shaft rotatably held in the housing via a rotating shaft bearing, and an auxiliary crank pin formed eccentrically at the tip of the rotating shaft is rotatably held in an eccentric shaft manner via an auxiliary crank pin bearing inserted into an outer boss portion erected on the back surface of the rotating side end plate, for preventing the main crank from rotating the orbiting scroll on its axis, In an oil-free scroll compressor, a fluid introduced into the compression chamber is sequentially transferred to the center and compressed, and the fluid compressed in a high pressure section formed at the center of the fixed scroll and the orbiting scroll is discharged from a discharge port formed at the center of the fixed scroll, 2. An oil-free scroll compressor comprising: a compression spring disposed between the rotary shaft bearing of the auxiliary crank and the auxiliary crank pin bearing.

2. a flange formed on the auxiliary crank; and a pressing member attached to an outer periphery of the auxiliary crank and movable in an axial direction of the auxiliary crank, 2. The oil-free scroll compressor according to claim 1, wherein the compression spring is attached to the exterior of the auxiliary crank and is disposed between the flange and the retaining member.

3. A tip seal having a T-shaped cross section, A groove is formed at a tip of the fixed wrap and a tip of the orbiting wrap, 3. The oil-free scroll compressor according to claim 1, wherein narrow portions of the tip seal are inserted into the recessed grooves of the fixed wrap and the orbiting wrap, respectively.

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