Scroll fluid machine

Abstract

A scroll fluid machine includes a fixed scroll and a turning scroll that includes a turning main surface and turns relative to the fixed scroll. The fixed scroll has a sealing structure provided at a location so as to face the turning main surface. The sealing structure includes a sealing groove that is formed in the fixed main surface and that includes a groove bottom surface, a backup unit that is in contact with the groove bottom surface, and a dust seal that is in contact with both the backup unit and the turning main surface and is pressed against the turning main surface by force received from the backup unit. The backup unit includes a lower-stage backup tube that is in contact with the groove bottom surface, and an upper-stage backup tube that is arranged in series along the direction of the groove depth of the sealing groove with respect to the lower-stage backup tube and is in contact with the dust seal.

Description

Scroll fluid machinery

[0001] The present invention relates to a scroll fluid machine.

[0002] A scroll fluid machine has a pair of scrolls arranged opposite each other. Each of the pair of scrolls has a spiral wrap. The scroll fluid machine compresses or expands gas by changing the volume of an internal space formed between the wrap of one scroll and the wrap of the other scroll. The change in volume of the internal space is achieved by orbiting one scroll relative to the other scroll.

[0003] When comparing the pressure in the internal space with the atmospheric pressure of the surrounding environment, the pressure in the internal space may be higher or lower than the atmospheric pressure of the surrounding environment. This difference in pressure may cause gas trapped in the internal space to leak. This difference in pressure may also cause foreign matter to enter the internal space. Therefore, a sealing structure is provided at the location where the pair of scrolls contact each other to separate the internal space from the external space. Patent Document 1 discloses a scroll fluid machine equipped with a dust seal to prevent the intrusion of dust and other particles from the outside.

[0004] Japanese Patent Application Laid-Open No. 2005-320885

[0005] The sealing structure is provided for one of the scrolls. One scroll orbits relative to the other scroll. Therefore, the other scroll slides against the sealing structure provided for the other scroll. This sliding causes wear on the components that make up the sealing structure. In other words, the components that make up the sealing structure are consumables and need to be replaced at predetermined intervals. When replacing a part, the operation of the scroll fluid machine is stopped, so the longer the time interval until the next part replacement, the better. Therefore, in this technical field, there has been a demand for a longer lifespan for the sealing structure.

[0006] The present invention provides a scroll fluid machine that can extend the life of a sealing structure.

[0007] A scroll fluid machine according to one embodiment of the present invention includes a first scroll having a spiral wrap and a second scroll including a second main surface along which the first scroll is slidable and which orbits relative to the first scroll. The first scroll has a sealing structure provided at a portion facing the second main surface, the sealing structure including a sealing groove formed at a portion facing the second main surface and including a groove bottom, an elastic member disposed on the side of the groove bottom, and a sealing member disposed between the elastic member and the second main surface and pressed against the second main surface by a force received from the elastic member. The elastic member includes a first spring element disposed on the side of the groove bottom, and a second spring element disposed in series with the first spring element along the groove depth direction of the sealing groove and on the side of the sealing member.

[0008] In a scroll fluid machine, a sealing member is pressed against the orbiting main surface by an elastic member. The elastic member is composed of a first spring element and a second spring element, which are treated as different mechanical elements. A configuration in which the first spring element and the second spring element are arranged in series allows for a mechanical model in which springs are connected in series. Therefore, the composite spring constant of the elastic member is smaller than the spring constant of an elastic member composed of a single spring element. According to Hooke's law, elastic force is the product of the spring constant and the distance. Therefore, to obtain a predetermined elastic force, a smaller spring constant requires a correspondingly larger distance. Therefore, in a configuration in which the sealing member is pressed against the other main surface with a predetermined pressing force, a smaller spring constant of the elastic member requires a larger deformation amount of the elastic member to obtain the predetermined pressing force. The deformation amount of the elastic member is related to the length of time that the pressing force can be maintained. Therefore, by increasing the deformation amount, the length of time that the pressing force can be maintained can be extended. As a result, the life of the sealing structure can be extended.

[0009] In one embodiment of the scroll fluid machine, the first spring element may be a first tube having a circular cross-sectional shape and a diameter defined by the groove width of the sealing groove. The second spring element may be a second tube having a circular cross-sectional shape and a diameter defined by the groove width of the sealing groove. With this structure, the elastic member can be formed from a tube material that is easily available.

[0010] In one embodiment of the scroll fluid machine, the distance from the groove bottom surface of the sealing groove to the other-side main surface may be shorter than the sum of the natural length of the diameter of the first tube, the natural length of the diameter of the second tube, and the length of the sealing member along the groove depth direction. With this configuration, when one scroll and the other scroll are combined, the diameters of the first tube and the second tube can be made shorter than their natural lengths. Therefore, the first tube and the second tube are reliably deformed, thereby reliably generating a pressing force that presses the sealing member against the other-side main surface.

[0011] In one embodiment of the scroll fluid machine, the groove depth (GD) of the sealing groove may be defined by the following formula (1), which includes the diameter (D1) of the first tube, the diameter (D2) of the second tube, the length (ST) of the sealing member along the groove depth direction, the amount of wear (SW) that is allowable in the sealing member, and the length (AC) of the gap from the portion facing the other main surface to the other main surface. According to this configuration, since the groove depth (GD) of the sealing groove is defined by the following formula (1), a desired amount of wear can be achieved. GD=(D1+D2)+(ST-SW)-AC...(1)

[0012] In one embodiment of the scroll fluid machine, the diameter of the first tube as a natural length and the diameter of the second tube as a natural length may be smaller than the groove width of the sealing groove. With this configuration, a constant spring constant can be ensured against the degree of deformation of the first tube and the second tube.

[0013] In one embodiment of the scroll fluid machine, when the length of the gap from the portion facing the other main surface to the other main surface is a predetermined length (AC), the first tube and the second tube may be deformed so as to be compressed in the groove depth direction of the sealing groove and expanded in the width direction of the sealing groove. The first tube and the second tube expanded in the width direction of the sealing groove may not contact the groove side surface of the sealing groove. This configuration also ensures a constant spring constant regardless of the degree of deformation of the first tube and the second tube.

[0014] In one embodiment of the scroll fluid machine, the first tube may be in separable contact with the second tube. With this configuration, the sealing structure can be formed using tubes that are readily available.

[0015] In one embodiment, the first tube of the scroll fluid machine may be inseparably joined to the second tube, and this configuration makes it possible to reliably form an elastic member in which the first tube, which is the first spring element, and the second tube, which is the second spring element, are connected in series.

[0016] In one embodiment of the scroll fluid machine, the elastic member may be in direct contact with the bottom surface of the groove.

[0017] In one embodiment of the scroll fluid machine, the sealing member may be in direct contact with the elastic member and also with the other main surface.

[0018] In one embodiment, the first spring element of the scroll fluid machine may be in direct contact with the bottom surface of the groove.

[0019] In one embodiment, the second spring element of the scroll fluid machine may be in direct contact with the sealing member.

[0020] According to the present invention, a scroll fluid machine is provided in which the life of the sealing structure can be extended.

[0021] Fig. 1 is an exploded perspective view showing the structure of a scroll fluid machine of an embodiment. Fig. 2 is a cross-sectional view showing a main part of the scroll fluid machine shown in Fig. 1. Fig. 3 is a cross-sectional view showing a sealing structure provided in the scroll fluid machine shown in Fig. 2. Figs. 4(a), 4(b), and 4(c) are diagrams for explaining a first action achieved by the scroll fluid machine of the embodiment. Figs. 5(a), 5(b), and 5(c) are diagrams for explaining a second action achieved by the scroll fluid machine of the embodiment. Figs. 6(a), 6(b), and 6(c) are diagrams for explaining an action achieved by a scroll fluid machine of a comparative example.

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0023] [Scroll Fluid Machine] The scroll fluid machine 1 shown in FIG. 1 includes a pair of scrolls as a main component. In the scroll fluid machine 1, a plurality of partitioned spaces are formed by the pair of scrolls. The volume of each of the plurality of spaces is reduced or expanded by the relative orbital motion of the pair of scrolls. As a result, the gas trapped in the partitioned spaces is compressed or expanded. In other words, the scroll fluid machine 1 is a scroll compressor or a scroll expander. In the following description, the scroll fluid machine 1 will be described as a compressor. Each of the plurality of spaces partitioned by the pair of scrolls is referred to as a pocket.

[0024] In this embodiment, the scroll fluid machine 1 has a pair of scrolls, one of which is a fixed scroll 2 and the other of which is an orbiting scroll 3. One scroll has a fixed main surface 21a as one main surface facing the other scroll. In this embodiment, one scroll is the fixed scroll 2 and the other scroll is the orbiting scroll 3. The other scroll, the orbiting scroll 3, has an orbiting main surface 31a as the other main surface facing the fixed scroll 2, the other scroll. The scroll fluid machine 1 includes components such as a housing and bearings, but these will not be shown in FIG. 1 or described in detail in this embodiment.

[0025] The fixed scroll 2 is a member fixed to a housing or the like. The fixed scroll 2 has a cylindrical outer shape with a bottom. The fixed scroll 2 has a fixed-side bottom portion 21, a fixed-side peripheral wall portion 22, and a fixed wrap 23.

[0026] The fixed-side bottom 21 is one member that forms a pocket. The fixed-side bottom 21 includes a fixed main surface 21a and a fixed-side back surface 21b. The fixed-side bottom 21 is provided with an intake port 211 for taking in gas and an outlet port 212 for discharging compressed gas. In the disc-shaped fixed-side bottom 21, the intake port 211 is provided on the outer periphery close to the fixed-side peripheral wall portion 22. In the disc-shaped fixed-side bottom 21, the outlet port 212 is provided in the center. The fixed main surface 21a faces the orbiting scroll 3. A portion of the orbiting scroll 3 faces the mirror-finished fixed main surface 21a.

[0027] The fixed-side circumferential wall portion 22 forms the outer circumferential wall of the fixed scroll 2. Like the fixed main surface 21a, the fixed-side circumferential wall portion 22 is also a member that forms pockets. A plurality of pockets are formed in the area surrounded by the fixed-side circumferential wall portion 22. The fixed-side circumferential wall portion 22 includes a fixed-side circumferential wall main surface 22a, a circumferential wall outer circumferential surface 22c, and a circumferential wall inner circumferential surface 22d. The fixed-side circumferential wall main surface 22a is a portion that faces the orbiting main surface. The fixed-side circumferential wall main surface 22a faces the orbiting scroll 3. Like the fixed main surface 21a, a portion of the orbiting scroll 3 also faces the fixed-side circumferential wall main surface 22a.

[0028] When viewed from the direction of the rotation axis A, the fixed wrap 23 has a so-called spiral shape. A plurality of pockets are formed by the fixed wrap 23 and the orbiting wrap 33, which will be described later. When the scroll fluid machine 1 is a compressor, the pockets move from the outer circumferential side to the inner circumferential side while orbiting around the rotation axis A in accordance with the orbiting motion of the orbiting scroll 3. The volume of the pockets decreases as they approach the inner circumferential side. Finally, the pockets connect to the discharge port 212. As a result, the compressed gas is discharged from the discharge port 212. The fixed wrap 23 includes a fixed wrap main surface 23a, a fixed wrap outer circumferential surface 23c, and a fixed wrap inner circumferential surface 23d. The fixed wrap main surface 23a faces the orbiting scroll 3.

[0029] The scroll fluid machine 1 includes one drive shaft 41 and three driven shafts 42. The drive shaft 41 has a drive shaft main body 411 and an eccentric connecting end 412. The eccentric connecting end 412 is provided at the tip of the drive shaft main body 411. A drive source such as a motor is connected to the base end of the drive shaft main body 411 via a belt or the like. When the drive shaft 41 rotates, the eccentric connecting end 412 orbits around the rotation axis A of the drive shaft 41. The orbiting of the eccentric connecting end 412 causes the orbiting scroll 3 to orbit relative to the fixed scroll 2. The driven shafts 42 support the orbiting motion of the orbiting scroll 3. The driven shafts 42 are arranged at equal intervals (120-degree intervals) around the rotation axis A of the drive shaft 41. The driven shaft 42 has an orbiting-side connecting portion 421 that is connected to the orbiting scroll 3, and a fixed-side connecting portion 422 that is connected to a fixed member such as a housing.

[0030] The orbiting scroll 3 has an orbiting disk portion 31 and an orbiting wrap 33. The orbiting disk portion 31 has an orbiting main surface 31a, which is the other main surface, and an orbiting back surface 31b. The orbiting main surface 31a faces the fixed scroll 2. The outer circumferential side of the orbiting main surface 31a faces the fixed-side peripheral wall main surface 22a of the fixed scroll 2. The orbiting wrap 33 is provided on the inner circumferential side of the orbiting main surface 31a. The orbiting back surface 31b is provided with a drive bearing receiving portion 311 to which the drive shaft 41 is connected and a driven bearing receiving portion 312 to which the driven shaft 42 is connected.

[0031] Like the fixed wrap 23, the orbiting wrap 33 also has a spiral shape in a plan view. The orbiting wrap 33 includes an orbiting wrap main surface 33a, an orbiting wrap outer peripheral surface 33c, and an orbiting wrap inner peripheral surface 33d. The orbiting wrap main surface 33a faces the fixed main surface 21a of the fixed scroll 2. A portion of the orbiting wrap inner peripheral surface 33d contacts a portion of the fixed wrap outer peripheral surface 23c. A portion of the orbiting wrap outer peripheral surface 33c contacts a portion of the fixed wrap inner peripheral surface 23d. These contact areas move in a spiral shape from the outer periphery toward the center around the rotation axis A in response to the orbiting motion of the orbiting wrap 33. A pair of adjacent contact areas defines one pocket.

[0032] 2 is an enlarged cross-sectional view of the outer periphery of the fixed scroll 2 and the orbiting scroll 3. The portions where the fixed scroll 2 and the orbiting scroll 3 face each other will be described in detail with reference to FIG.

[0033] As described above, each pocket moves while revolving from the outer periphery toward the rotation axis A. The volume of the pocket decreases as it approaches the rotation axis A from the outer periphery. As the volume of the pocket decreases, the volume of the gas trapped in the pocket also decreases. In other words, the gas trapped in the pocket is compressed. The fact that the gas trapped in the pocket is compressed as the pocket shrinks means that the gas does not leak from the pocket even when the pocket's volume decreases. Meanwhile, the orbiting scroll 3 orbits relative to the fixed scroll 2. In other words, the portions where the fixed scroll 2 and the orbiting scroll 3 face each other must be able to slide smoothly while also preventing gas from leaking from the pocket or gas from entering the pocket from outside.

[0034] The first portion where the fixed scroll 2 and the orbiting scroll 3 face each other is the fixed wrap main surface 23a and the orbiting main surface 31a. A fixed seal 231 is disposed on the fixed wrap main surface 23a. The fixed seal 231 is formed, for example, from a self-lubricating fluorine-based resin or the like. The fixed seal 231 is fitted into a fixed wrap groove 23s provided in the fixed wrap main surface 23a. The fixed seal 231 protrudes slightly from the fixed wrap main surface 23a. The fixed seal main surface 231a contacts the orbiting main surface 31a. In other words, the fixed wrap main surface 23a does not contact the orbiting main surface 31a. A very small gap is formed between the fixed wrap main surface 23a and the orbiting main surface 31a.

[0035] The second portion where the fixed scroll 2 and the orbiting scroll 3 face each other is the orbiting wrap main surface 33a and the fixed main surface 21a. As with the first portion, slidability and airtightness are ensured by the orbiting seal 331 fitted into the orbiting wrap groove 33s. The orbiting seal main surface 331a contacts the fixed main surface 21a. In other words, the orbiting wrap main surface 33a does not contact the fixed main surface 21a. A very small gap is formed between the orbiting wrap main surface 33a and the fixed main surface 21a.

[0036] The third portion where the fixed scroll 2 and the orbiting scroll 3 face each other is the fixed-side peripheral wall main surface 22a and the orbiting main surface 31a. That is, the orbiting main surface 31a includes a portion facing the fixed wrap main surface 23a and a portion facing the fixed-side peripheral wall main surface 22a. The entire area of ​​the fixed-side peripheral wall main surface 22a faces the orbiting scroll 3. On the other hand, the portion of the orbiting main surface 31a facing the fixed-side peripheral wall main surface 22a is a portion on the outer circumferential side that surrounds the portion facing the fixed wrap main surface 23a.

[0037] A sealing structure 5 is provided on the fixed-side peripheral wall main surface 22a. The sealing structure 5, like the seals provided on the first and second portions, ensures slidability and airtightness. The fixed-side peripheral wall portion 22 is one element forming the outermost pocket among the multiple pockets. For example, as shown in FIG. 2 , an air intake port 211 is connected to the pocket, and gas is drawn into the pocket through the air intake port 211. That is, when comparing the pressure outside the air intake port 211 with the pressure in the pocket, the pressure in the pocket is lower than the pressure outside the air intake port 211. If an unintended gap exists between the fixed-side peripheral wall main surface 22a and the orbiting main surface 31a, the pressure difference could cause foreign matter (dust) to be drawn into the pocket. The sealing structure 5 also serves to prevent such dust from being drawn into the pocket.

[0038] The sealing structure 5 has a sealing groove 51, a dust seal 52 which is a sealing member, and a backup unit 53 which is an elastic member. The dust seal 52 is formed of a self-lubricating fluorine-based resin or the like, similar to the fixed seal 231. The dust seal 52 has a circular ring shape when viewed in a plan view from the direction of the rotation axis A. The cross-sectional shape of the dust seal 52 is, for example, rectangular. The dust seal main surface 52a protrudes from the fixed-side peripheral wall main surface 22a and contacts the orbiting main surface 31a.

[0039] The backup unit 53 applies a force to the dust seal 52 to press the dust seal 52 against the main turning surface 31 a. The dust seal 52 gradually wears due to friction with the main turning surface 31 a. If the position of the dust seal 52 relative to the fixed-side peripheral wall portion 22 were fixed, a gap would easily form between the dust seal 52 and the main turning surface 31 a due to wear. Therefore, the force pressing the dust seal 52 toward the main turning surface 31 a maintains the dust seal 52 in contact with the main turning surface 31 a.

[0040] Furthermore, the positional relationship between the dust seal 52 and the backup unit 53 is as follows. First, as shown in FIG. 3, the dust seal 52 is disposed between the backup unit 53 and the main turning surface 31a. More specifically, the dust seal 52 is in direct contact with the backup unit 53 and also in direct contact with the main turning surface 31a. Next, the backup unit 53 is disposed on the side of the groove bottom surface 51a. More specifically, the backup unit 53 is in direct contact with the groove bottom surface 51a.

[0041] The sealing structure 5 will be described in further detail below.

[0042] [Configuration of the sealing structure] FIG. 3 is an enlarged cross-sectional view of the sealing structure 5. The sealing groove 51 is an area surrounded by a groove bottom surface 51a, an outer peripheral groove side surface 51c, and an inner peripheral groove side surface 51d. The sealing groove 51 includes a peripheral wall opening 51s formed in the fixed-side peripheral wall main surface 22a. The shape of the sealing groove 51 is annular in plan view. Therefore, the shape of the groove bottom surface 51a is also annular in plan view. In the example shown in FIG. 3, the width of the sealing groove 51 may be defined, for example, as the length from the outer peripheral groove side surface 51c to the inner peripheral groove side surface 51d. The groove depth GD of the sealing groove 51 is greater than the width of the sealing groove 51. The groove depth GD of the sealing groove 51 may be defined, for example, as the length from the fixed-side peripheral wall main surface 22a to the groove bottom surface 51a.

[0043] As described above, the cross-sectional shape of the dust seal 52 is rectangular. The dust seal 52 has a dust seal main surface 52a, a dust seal back surface 52b, a dust seal outer peripheral surface 52c, and a dust seal inner peripheral surface 52d. The dust seal main surface 52a contacts the swirl main surface 31a. The dust seal back surface 52b contacts the upper backup tube 532. The dust seal outer peripheral surface 52c faces the outer peripheral groove side surface 51c. The dust seal outer peripheral surface 52c may or may not contact the outer peripheral groove side surface 51c. Similarly, the dust seal inner peripheral surface 52d may or may not contact the inner peripheral groove side surface 51d. For example, when preventing foreign matter from entering a pocket from the outside, the dust seal 52 is pushed inward in response to a pressure difference. As a result, the dust seal outer peripheral surface 52c moves away from the outer peripheral groove side surface 51c. In this case, the dust seal inner peripheral surface 52d may contact the inner peripheral groove side surface 51d.

[0044] The backup unit 53 is, for example, a series of connected tubular resin ring members. Specifically, the backup unit 53 includes a lower backup tube 531 that contacts the groove bottom surface 51 a, and an upper backup tube 532 that contacts the lower backup tube 531 and the dust seal 52. The lower backup tube 531 is a first spring element or a first tube. The upper backup tube 532 is a second spring element or a second tube. The lower backup tube 531 may be fixed at a contacting portion with the upper backup tube 532, or may simply be in contact with the upper backup tube 532.

[0045] The lower backup tube 531 and the upper backup tube 532 are stacked in the depth direction of the sealing groove 51. The lower backup tube 531 and the upper backup tube 532 each deform so as to be crushed in the depth direction of the sealing groove 51. When the lower backup tube 531 and the upper backup tube 532 are each simulated as a virtual spring element, the backup unit 53 can be expressed as a mechanical model in which a virtual spring simulating the lower backup tube 531 and a virtual spring simulating the upper backup tube 532 are connected in series. As a result, the spring constant of the backup unit 53 can be defined by the spring constant of the lower backup tube 531 and the spring constant of the upper backup tube 532 using equation (3) described below.

[0046] There are no particular limitations on the shapes of the lower backup tube 531 and the upper backup tube 532. The lower backup tube 531 and the upper backup tube 532 are hollow tubes, as shown in FIG. 3 and the like, and may have a circular cross-sectional shape. In this case, the cross-sectional shape of the backup unit 53 formed by the lower backup tube 531 and the upper backup tube 532 is an eight-shaped configuration. The lower backup tube 531 and the upper backup tube 532 may also be solid, string-like members, and may have a circular cross-sectional shape.

[0047] The backup unit 53 may or may not contact the outer peripheral groove side surface 51 c and the inner peripheral groove side surface 51 d. For example, as shown in Fig. 3, when the backup unit 53 is in a state in which it generates a restoring force, the cross sections of the lower backup tube 531 and the upper backup tube 532 may each be elliptical, and their sides may contact the outer peripheral groove side surface 51 c and the inner peripheral groove side surface 51 d, respectively.

[0048] The dimensions of some of the elements described above may be set using the following formula (2): GD = (D1 + D2) + (ST - SW) - AC (2) GD: Groove depth D1: Diameter of lower backup tube D2: Diameter of upper backup tube DS: Height of dust seal SW: Allowable wear amount AC: Set gap

[0049] [Function of Sealing Structure] So far, the structure of the sealing structure 5 has been described. Below, the function of the sealing structure 5 will be described. First, the function of the sealing structure 5C, which is a comparative example, will be described. Then, the function of the sealing structure 5 of this embodiment will be described.

[0050] 6(a), 6(b), and 6(c) are cross-sectional views showing a sealing structure 5C of a comparative example, which differs from the sealing structure 5 of the present embodiment in that it includes one backup tube 533 as a backup unit.

[0051] As shown in FIG. 6A, the allowable wear amount SW can be defined as the distance from the dust seal main surface 52 a to a position spaced above the fixed-side peripheral wall main surface 22 a by the set gap AC when one backup tube 533 and the dust seal 52 are arranged in the sealing groove 51.

[0052] As shown in FIG. 6( b), the orbiting scroll 3 is moved closer to the fixed scroll 2 with the orbiting main surface 31 a in contact with the dust seal main surface 52 a. As a result, the dust seal 52 does not substantially deform, and the backup tube 533 deforms as the orbiting scroll 3 moves. This movement continues until the distance from the orbiting main surface 31 a to the fixed-side peripheral wall main surface 22 a reaches the set gap AC. The state shown in FIG. 6( b) can be considered, for example, to be immediately after the scroll fluid machine 1 is assembled. In other words, it is the initial state S1C before the scroll fluid machine 1 is put into operation.

[0053] In the state shown in FIG. 6( b), the backup tube 533 generates a tube reaction force FR corresponding to the deformation amount D3s. The magnitude of this tube reaction force FR can be defined as the product of the spring constant (kc) of the backup tube 533 and the deformation amount D3s. The backup tube 533 receives a reaction force F51 from the groove bottom surface 51 a. The reaction force F51 has the same magnitude as the tube reaction force FR but is directed in the opposite direction. Furthermore, the backup tube 533 applies the tube reaction force FR to the dust seal back surface 52 b. The backup tube 533 also receives a reaction force F52 from the dust seal 52. Due to the reaction force F52 of the dust seal 52, a pressing force FP and a reaction force F3 of the same magnitude but directed in the opposite direction are generated between the dust seal 52 and the orbiting scroll 3.

[0054] When the scroll fluid machine 1C starts operating from the initial state S1 in FIG. 6B, a state occurs in which the orbiting main surface 31a moves while rubbing against the dust seal main surface 52a. At this time, a frictional force, which can be defined as the product of a pressing force FP, which can be regarded as a normal force, and a friction coefficient, is generated between the dust seal main surface 52a and the orbiting main surface 31a. The orbiting scroll 3 moves relative to the dust seal 52 against this frictional force. As a result, the dust seal 52 gradually wears. The degree of wear depends on the magnitude of the pressing force FP.

[0055] FIG. 6C illustrates a state in which the wear of the dust seal 52 has reached the allowable wear amount SW. In the example illustrated in FIG. 6C, the wear of the dust seal 52 has reached the allowable wear amount SW, and the deformation amount D3s of the backup tube 533 is also zero. In other words, the tube reaction force FR caused by the deformation of the backup tube 533 is no longer generated, and no pressing force FP is generated. Therefore, the dust seal 52 is no longer pressed against the main turning surface 31a with a predetermined pressing force FP. When this state is reached, the sealing structure 5C has lost its sealing function and is therefore determined to have reached the end of its life (life state S2). The dust seal 52 is then replaced.

[0056] Naturally, when the dust seal 52 is replaced, the scroll fluid machine 1 cannot operate. Therefore, by extending the life of the dust seal 52, it is possible to extend the time during which the scroll fluid machine 1 can be continuously operated. In the scroll fluid machine 1 of this embodiment, the sealing structure 5 has a longer life than the scroll fluid machine 1 of the comparative example, and as a result, the time during which the scroll fluid machine 1 can be continuously operated can be extended.

[0057] The life of the sealing structure 5 is the time until the wear of the dust seal 52 reaches the allowable wear amount SW. This is because, once the wear of the dust seal 52 reaches the allowable wear amount SW, the pressing force FP that presses the dust seal 52 against the main turning surface 31a is no longer generated. The pressing force FP is generated when the total length (D3 + DS) of the sealing structure 5 in its natural state is longer than the total length (GD + AC) of the groove depth GD and the set gap AC. The pressing force FP is generated when the allowable wear amount SW set for the dust seal 52 exists. In other words, if the allowable wear amount set for the dust seal 52 can be increased, the time during which the pressing force FP is generated can be extended accordingly. Therefore, the life of the sealing structure 5 can be extended.

[0058] The position of the dust seal main surface 52a coincides with the position of the swivel main surface 31a, and therefore remains unchanged from the initial state S1 to the end-of-life state S2. On the other hand, it can be said that the dust seal 52 moves toward the swivel main surface 31a by the amount of wear. Therefore, the position of the dust seal back surface 52b moves a distance equal to the allowable amount of wear SW from the initial state S1 to the end-of-life state S2. The dust seal back surface 52b is always in contact with the backup tube 533 and receives a tube reaction force FR from the backup tube 533. Therefore, the amount of movement of the dust seal back surface 52b is the deformation amount D3s of the backup tube 533. As a result, it can be seen that increasing the deformation amount of the backup tube 533 is sufficient to extend the life of the sealing structure 5.

[0059] However, considering Hooke's law (F = k × x), as the deformation amount D3s of the backup tube 533 increases, the tube reaction force FR also increases. The tube reaction force FR is related to the frictional force between the dust seal main surface 52a and the swivel main surface 31a. As the tube reaction force FR increases, the frictional force also increases. As a result, the amount of wear per unit time increases. In this case, although the allowable amount of wear SW increases, the amount of wear also increases, so overall, it seems that a long life for the sealing structure 5 cannot be achieved.

[0060] Therefore, the sealing structure 5 of this embodiment employs a structure that can increase the allowable wear amount SW without increasing the tube reaction force FR. As shown in FIG. 3 , this structure uses a lower backup tube 531 and an upper backup tube 532 as the source of the pressing force FP that presses the dust seal 52 against the orbiting scroll 3.

[0061] [First Action] As shown in Fig. 4(a), the lower backup tube 531, the upper backup tube 532, and the dust seal 52 are arranged in the sealing groove 51. At this time, the allowable wear amount SW is set in the same manner as in the comparative example described above. The difference from the comparative example is that the allowable wear amount SW set in the example of the embodiment in Fig. 4(a) is increased by an additional allowable wear amount AW to the allowable wear amount SW set in the example of the comparative example in Fig. 6(a).

[0062] The additional allowable wear amount AW can be set, for example, by two methods. The first method is to increase the height DS of the dust seal 52. In this case, a wear allowance corresponding to the additional allowable wear amount AW is added to the initial height DS of the dust seal 52. As a result, the height of the dust seal 52 becomes "DS + AW." The second method is to decrease the groove depth GD. In this case, the initial groove depth GD is decreased by a length corresponding to the additional allowable wear amount AW. As a result, the depth of the sealing groove 51 becomes "GD - AW." The additional allowable wear amount AW is set by selecting at least one of the height DS and groove depth GD of the dust seal 52. In other words, the additional allowable wear amount AW may be set by adjusting the height DS of the dust seal 52. The additional allowable wear amount AW may be set by adjusting the groove depth GD. The additional allowable wear amount AW may be set by adjusting both the height DS and groove depth GD of the dust seal 52.

[0063] Now, the composite spring constant (ks) of the backup unit 53 is expressed by the formula (3): ks=k1×k2 / (k1+k2) (3) where ks is the composite spring constant of the backup unit 53, k1 is the spring constant of the lower backup tube 531, and k2 is the spring constant of the upper backup tube 532.

[0064] If the spring constant (k1) of the lower backup tube 531 and the spring constant (k2) of the upper backup tube 532 are equal to each other (ke), then equation (4) can be obtained from equation (3): ks = ke × ke / (ke + ke) = ke^2 / 2ke = (1 / 2) × ke ... (4) In other words, the composite spring constant (ks) of the backup unit 53 is half the spring constant (ke) of the lower backup tube 531 and half the spring constant (ke) of the upper backup tube 532.

[0065] Next, consider obtaining a force of the same magnitude as the pressing force FP caused by the backup tube 533 of the comparative example. Since the composite spring constant (ks) is 1 / 2, in order to obtain the same magnitude of force, the displacement should be doubled.

[0066] In other words, by using two or more backup tubes 533, as in the comparative example, the composite spring constant (ks) of the backup unit 53 appears to decrease, making it possible to ensure a larger displacement to obtain the same pressing force FP.

[0067] The pressing force FP may be greater than a preset minimum pressing force (e.g., zero) and less than a maximum pressing force determined by the degree of wear. For example, if the pressing force FP generated in the comparative example is the maximum pressing force, any pressing force FP magnitude can be selected from a numerical range that does not exceed this maximum pressing force but is greater than the minimum pressing force. For example, in the example shown in FIG. 4(a), the additional allowable wear amount AW can be set to the same length as the initial allowable wear amount SW. In other words, the sum of the allowable wear amount SW and the additional allowable wear amount AW in the embodiment shown in FIG. 4(a) is twice the allowable wear amount SW in the comparative example shown in FIG. 6(a). Assuming that the comparative example and the embodiment are otherwise the same, the time required for the embodiment to reach the life state S2 in FIG. 4(c) from the initial state S1C in FIG. 6(b) can be considered to be twice the time required for the comparative example to reach the life state S2C in FIG. 6(c) from the initial state S1C in FIG. 6(b).

[0068] [Second Action] The life of the sealing structure 5 is the time until the wear of the dust seal 52 reaches the allowable wear amount SW. The time until the allowable wear amount SW is reached is determined by the relationship between the original size of the allowable wear amount SW and the magnitude of the frictional force. In the above explanation, the extension of the life of the sealing structure 5 of this embodiment was explained by focusing on increasing the allowable wear amount SW. Separately, the extension of the life of the sealing structure 5 of this embodiment can also be explained by focusing on the magnitude of the frictional force.

[0069] The composite spring constant (ks) of the backup unit 53 in the sealing structure 5 of this embodiment is half (½) of the spring constant (kc) of the backup tube 533 in the sealing structure 5C of the comparative example. For example, assume that the allowable wear amount SW in the sealing structure 5 of this embodiment is the same as the allowable wear amount SW in the sealing structure 5C of the comparative example (see FIG. 5A). In other words, assume that the deformation amount of the backup unit 53 of this embodiment is the same as the deformation amount of the backup tube 533 of the comparative example. The composite spring constant (ks) of the backup unit 53 of this embodiment is ½ of the spring constant (kc) of the backup tube 533 of the comparative example. Therefore, the tube reaction force FR generated by the backup unit 53 of this embodiment is ½ of the tube reaction force FR generated by the backup tube 533 of the comparative example (see FIG. 5B). As a result, the pressing force FP pressing the dust seal 52 against the orbiting scroll 3 is also ½. Since the pressing force FP is reduced, it is possible to extend the time required to reach the end-of-life state S2 shown in FIG. 5C from the initial state S1 shown in FIG. 5B.

[0070] [Third Action] The effect of extending the life of the sealing structure 5 provided in the scroll fluid machine 1 of this embodiment can be explained by only the first effect described above, or by only the second effect. Furthermore, the effect of extending the life of the sealing structure 5 can also be explained as a combination of the first and second effects. For example, it is possible to comprehensively determine the life of the sealing structure 5 by taking into account the limits imposed on the allowable wear amount SW and the limits imposed on the pressing force FP.

[0071] [Operation and Effect] In short, the scroll fluid machine 1 includes a fixed scroll 2, which is one scroll provided with a spiral-shaped fixed wrap 23, and an orbiting scroll 3, which is the other scroll including an orbiting main surface 31a on which the fixed scroll 2 can slide and orbits relatively to the fixed scroll 2. The fixed scroll 2 has a sealing structure 5 provided in a portion facing the orbiting main surface 31a. The sealing structure 5 includes a sealing groove 51 formed in the fixed main surface 21a and including a groove bottom surface 51a, a backup unit 53 in contact with the groove bottom surface 51a, and dust seals 52 in contact with both the backup unit 53 and the orbiting main surface 31a and pressed against the orbiting main surface 31a by a force received from the backup unit 53. The backup unit 53 includes a lower backup tube 531 that contacts the groove bottom surface 51a, and an upper backup tube 532 that is arranged in series with the lower backup tube 531 along the direction of the groove depth GD of the sealing groove 51 and contacts the dust seal 52.

[0072] In the scroll fluid machine 1, the dust seal 52 is pressed against the main orbiting surface 31a by the backup unit 53. The backup unit 53 is composed of a lower backup tube 531 and an upper backup tube 532, which are treated as separate elements. The combined spring constant (ks) of the backup unit 53 composed of the lower backup tube 531 and the upper backup tube 532 is smaller than the spring constant (kc) of the backup unit 53 composed of a single spring element. As a result, it is possible to increase the amount of deformation of the backup unit 53 required to obtain a predetermined magnitude of pressure for pressing the backup unit 53 against the main orbiting surface 31a. The amount of deformation of the backup unit 53 is related to the length of time that the generation of the pressing force can be maintained. Therefore, by increasing the amount of deformation, the length of time that the generation of the pressing force can be maintained can be extended. As a result, the life of the sealing structure 5 can be extended.

[0073] The lower backup tube 531 is a tube member having a circular cross section and a diameter defined by the groove width of the sealing groove 51. The upper backup tube 532 is a tube member having a circular cross section and a diameter defined by the groove width of the sealing groove 51. With this structure, the backup unit 53 can be formed using tube members that are easily available.

[0074] The distance from the groove bottom surface 51 a of the sealing groove 51 to the orbiting main surface 31 a is shorter than the total length obtained by adding the diameter, which is the natural length of the lower backup tube 531, the diameter, which is the natural length of the upper backup tube 532, and the length along the direction of the groove depth GD of the dust seal 52. With this configuration, when the fixed scroll 2 and the orbiting scroll 3 are combined, the diameters of the lower backup tube 531 and the upper backup tube 532 can be made shorter than their natural lengths. Therefore, the lower backup tube 531 and the upper backup tube 532 are reliably deformed, which reliably generates a pressing force that presses the dust seal 52 against the orbiting main surface 31 a.

[0075] The groove depth (GD) of the sealing groove 51 is defined by the following equation (5), which includes the diameter (D1) of the lower backup tube 531, the diameter (D2) of the upper backup tube 532, the length (ST) of the dust seal 52 along the groove depth GD direction, the amount of wear (SW) that can be tolerated in the dust seal 52, and the length (AC) of the gap from the fixed main surface 21a to the swiveling main surface 31a. With this configuration, it is possible to determine the groove depth GD that can achieve the desired amount of wear. GD = (D1 + D2) + (ST - SW) - AC (5)

[0076] The diameter of the lower backup tube 531 at its natural length and the diameter of the upper backup tube 532 at its natural length are smaller than the width of the sealing groove 51. With this configuration, a constant spring constant can be ensured for the degree of deformation of the lower backup tube 531 and the upper backup tube 532.

[0077] When the length of the gap from the fixed principal surface 21a to the pivot principal surface 31a is a predetermined length (AC), the lower backup tube 531 and the upper backup tube 532 are deformed so as to be compressed in the direction of the groove depth GD of the sealing groove 51 and expanded in the width direction of the sealing groove 51. The lower backup tube 531 and the upper backup tube 532 expanded in the width direction of the sealing groove 51 do not come into contact with the groove side surface of the sealing groove 51. This configuration also ensures a constant spring constant regardless of the degree of deformation of the lower backup tube 531 and the upper backup tube 532.

[0078] The lower backup tube 531 is in separable contact with the upper backup tube 532. With this configuration, the sealing structure 5 can be formed using tubes that are readily available.

[0079] The lower backup tube 531 is joined inseparably to the upper backup tube 532. This configuration makes it possible to reliably form the backup unit 53 in which the lower backup tube 531 and the upper backup tube 532 are connected in series.

[0080] [Modifications] The above scroll fluid machine is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0081] For example, the following formula (6) may be used instead of formula (2) to set the dimensions of the members that make up the sealing structure. Formula (6) below assumes that backup tubes of the same diameter are used. Formula (6) below can be suitably applied when two or more backup tubes of the same diameter are used. GD = DS x N + (ST - SW) - AC (6) GD: groove depth DS: diameter of backup tube N: number of backup tubes DS: height of dust seal SW: allowable amount of wear AC: set gap

[0082] In the above embodiment, the sealing structure 5 is provided at a portion of the fixed scroll 2 facing the orbiting main surface 31 a, but this is not limitative. The sealing structure 5 may also be provided at a portion of the orbiting scroll 3 facing the fixed-side peripheral wall main surface 22 a.

[0083] In the above embodiment, the backup unit 53, which is an elastic member, is in direct contact with the groove bottom surface 51a. The dust seal 52, which is a sealing member, is in contact with both the backup unit 53, which is an elastic member, and the swivel main surface 31a, which is the other main surface. Furthermore, the lower backup tube 531, which is a first spring element, is in contact with the groove bottom surface 51a, and the upper backup tube 532, which is a second spring element, is in contact with the dust seal 52, which is a sealing member. The "in contact" here means that the respective members are in direct contact with each other. For example, the respective members may not be in direct contact with each other, and some other member may be sandwiched between the respective members. For example, a plate-like member may be disposed between the backup unit 53, which is an elastic member, and the groove bottom surface 51a. Furthermore, a plate-like member may be disposed between the dust seal 52, which is a sealing member, and the backup unit 53, which is an elastic member, and a plate-like member may be disposed between the dust seal 52, which is a sealing member, and the other main surface, which is the swivel main surface 31a.

[0084] <Additional Remarks> The present disclosure also includes the following configurations.

[0085] The present disclosure is a scroll fluid machine comprising "one scroll having a spiral wrap, and another scroll including a second main surface along which the one scroll is slidable and which orbits relative to the one scroll. The one scroll has a sealing structure provided at a portion facing the second main surface. The sealing structure is formed at a portion facing the second main surface and includes a sealing groove including a groove bottom surface, an elastic member in contact with the groove bottom surface, and a sealing member in contact with each of the elastic member and the second main surface and pressed against the second main surface by force received from the elastic member. The elastic member includes a first spring element in contact with the groove bottom surface, and a second spring element arranged in series with the first spring element along the groove depth direction of the sealing groove and in contact with the sealing member."

[0086] 1, 1C...Scroll fluid machine, 2...Fixed scroll, 3...Orbiting scroll, 5, 5C...Sealing structure, 21a...Fixed main surface, 23...Fixed wrap, 31a...Orbiting main surface, 51...Sealing groove, 51a...Groove bottom surface, 52...Dust seal (sealing member), 53...Backup unit (elastic member).

Claims

1. A scroll fluid machine comprising: one scroll provided with a spiral wrap; and another scroll including a second main surface along which the one scroll can slide and which orbits relative to the one scroll, wherein the one scroll has a sealing structure provided at a portion facing the second main surface, the sealing structure including: a sealing groove formed at a portion facing the second main surface and including a groove bottom surface, an elastic member arranged on the side of the groove bottom surface, and a sealing member arranged between the elastic member and the second main surface and pressed against the second main surface by a force received from the elastic member, wherein the elastic member includes a first spring element arranged on the side of the groove bottom surface, and a second spring element arranged in series with the first spring element along the direction of the groove depth of the sealing groove and arranged on the side of the sealing member.

2. A scroll fluid machine as described in claim 1, wherein the first spring element is a first tube having a cross-sectional shape of a ring and a diameter defined by the groove width of the sealing groove, and the second spring element is a second tube having a cross-sectional shape of a ring and a diameter defined by the groove width of the sealing groove.

3. A scroll fluid machine as described in claim 2, wherein the distance from the bottom surface of the sealing groove to the other main surface is shorter than the total length obtained by adding up the diameter which is the natural length of the first tube, the diameter which is the natural length of the second tube, and the length of the sealing member along the direction of the groove depth.

4. The scroll fluid machine according to claim 2, wherein a groove depth (GD) of the sealing groove is defined by the following formula (1) including a diameter (D1) of the first tube, a diameter (D2) of the second tube, a length (ST) of the sealing member along the groove depth direction, an allowable wear amount (SW) of the sealing member, and a length (AC) of a gap from a portion facing the other main surface to the other main surface: GD=(D1+D2)+(ST-SW)-AC...(1) 5. The scroll fluid machine according to claim 2, wherein the diameter of the natural length of said first tube and the diameter of the natural length of said second tube are smaller than the groove width of said sealing groove.

6. A scroll fluid machine as described in claim 2, wherein, when the length of the gap from the portion facing the other-side main surface to the other-side main surface is a predetermined length (AC), the first tube and the second tube are deformed so as to be compressed in the groove depth direction of the sealing groove and expanded in the width direction of the sealing groove, and the first tube and the second tube expanded in the width direction of the sealing groove do not contact the groove side surface of the sealing groove.

7. The scroll fluid machine according to claim 2, wherein said first tube is in separable contact with said second tube.

8. The scroll fluid machine according to claim 2, wherein said first tube is joined to said second tube so as to be inseparable from said second tube.

9. The scroll fluid machine according to claim 1, wherein said elastic member directly contacts the bottom surface of said groove.

10. A scroll fluid machine according to claim 1, wherein said sealing member is in direct contact with said elastic member and also in direct contact with said other main surface.

11. The scroll fluid machine according to claim 1, wherein said first spring element directly contacts said groove bottom surface.

12. The scroll fluid machine according to claim 1, wherein said second spring element directly contacts said sealing member.

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