JP4940630B2 - Scroll expander - Google Patents

Description

  The present invention engages the fixed scroll and the orbiting scroll where the spiral wrap rises from the end plate to form an expansion chamber between the two, and the orbiting scroll revolves along a circular orbit under the restriction of rotation by the rotation restricting mechanism. The present invention relates to a scroll expander that performs suction, expansion, and discharge by moving the expansion chamber while changing its volume.

  Conventionally, in a scroll compressor of this type of scroll fluid machine, a back pressure chamber is provided at the back of the orbiting scroll to suck, compress, and discharge fluid in a compression chamber between the orbiting scroll and the fixed scroll. Conventionally, the orbiting scroll is pressed against the fixed scroll by the high-pressure back pressure guided to the side so that the orbiting scroll is not pushed away from the fixed scroll by the fluid pressure in the compression chamber.

  This back pressure is obtained when oil is supplied to each part of the compression mechanism using the discharge fluid pressure of the compression mechanism, the fluid pressure during compression, the differential pressure between the discharge side and suction side of the pump mechanism or compression mechanism linked to the orbiting scroll. However, if the orbiting scroll is strongly pressed against the fixed scroll due to fluctuations in the back pressure, abnormal wear of the thrust sliding part and increased input will occur. Therefore, various improvements have been made using a back pressure adjusting mechanism.

  Also, in a scroll compressor, if the thrust sliding part is actively lubricated with oil, the oil flows into the compression chamber during the compression stroke, and the efficiency is greatly reduced due to the overheat loss of the oil. Had. In order to solve this problem, a technique of providing an oil supply groove in a thrust sliding portion of a fixed scroll has been disclosed (for example, see Patent Document 1).

  FIG. 7 shows a thrust sliding portion in a conventional scroll compressor described in Patent Document 1. As shown in FIG. In FIG. 7, the oil that has reached the back pressure chamber enters the oil supply groove 271 through the digging portion 270 and reaches the entire length thereof by the capillary phenomenon, and the sliding portion is appropriately lubricated to prevent problems such as efficiency reduction. Is.

Even in the scroll expander, a thrust support structure and the like can be considered as in the scroll compressor, but this type of technical disclosure in the scroll expander is very small compared to the scroll compressor.
JP 2000-291571 A

  In the scroll expander, it is relatively easy to use the same means as the compressor as the support method of the orbiting scroll. However, it is very important to improve the lubrication performance at the thrust sliding part in the scroll expander due to the following problems. It will be a difficult task.

  When the scroll compressor and scroll expander are configured with the same size and operated under the same conditions (frequency, high pressure / low pressure, working fluid, thrust loss), “compressor input” and “expander output” Generally, the ratio of the thrust loss to the ratio is “expander”> “compressor”. This is qualitatively determined from the relationship between theoretical compression power and theoretical expansion power determined by the physical properties of the working fluid.

Therefore, improving the lubrication performance of the thrust sliding portion and reducing the thrust loss in the scroll expander is very important from the viewpoint of higher efficiency and higher reliability.
The present invention solves such a problem, and improves the lubricity at the thrust sliding portion by using the characteristics unique to the scroll expander among the scroll fluid machines, and is highly efficient and reliable with little thrust loss. An object is to provide a high scroll expander.

  In order to solve the above-described conventional problems, the scroll expander of the present invention has a back pressure chamber in which the pressure of the working fluid in the oil or oil atmosphere acts on the back side of the orbiting scroll, and the inner back pressure chamber is substantially omitted. An annular sliding partition band that slides on the back of the orbiting scroll so as to set the suction pressure and the outer back pressure chamber to a substantially discharge pressure is provided, and the back pressure chamber is configured in a double structure. A thrust load of the orbiting scroll is supported by the fixed scroll, an expansion chamber near the end of expansion formed by the wrap outer wall side of the orbiting scroll and the wrap inner wall side of the fixed scroll, and the outer back pressure chamber, In this configuration, a minute pressure difference is provided through a thrust surface that supports the thrust load.

  As a result, the double-structure back pressure chamber can be optimally designed so that, while the orbiting scroll is thrust-supported by the fixed scroll, the orbiting scroll can be slightly separated from the fixed scroll due to fluctuations in the pressure distribution in the expansion chamber. Thus, the sliding gap between the fixed scroll and the orbiting scroll can be reliably lubricated using the separation gap, and a highly efficient and highly reliable scroll expander can be provided.

  The scroll expander of the present invention is highly efficient and reliable by using a characteristic that does not greatly reduce the expander performance even when lubricating oil that lubricates the thrust sliding surface flows into the expansion chamber due to the configuration unique to the scroll expander. It is possible to realize a highly efficient expander efficiency.

  In addition, a particularly high effect can be realized by using a high-pressure refrigerant such as carbon dioxide as the working fluid, and an expander is used as an alternative to the expansion valve in the refrigeration apparatus using carbon dioxide as the working fluid. Thus, the energy consumption efficiency of the refrigeration cycle can be further increased.

  According to a first aspect of the present invention, a fixed scroll and a turning scroll where a spiral wrap rises from an end plate are meshed to form an expansion chamber therebetween, and the turning scroll is formed into a circular orbit under the restriction of rotation by a rotation restriction mechanism. In the scroll expander provided with an expansion mechanism that performs suction, expansion, and discharge by moving the expansion chamber while changing the volume when swung along, the oil or oil atmosphere is provided on the back side of the orbiting scroll. A back pressure chamber in which the pressure of the working fluid acts is formed, and an annular sliding partition band that slides on the back of the orbiting scroll so that the inner back pressure chamber is set to a substantially suction pressure and the outer back pressure chamber is set to a substantially discharge pressure. And the back pressure chamber has a double structure, and the thrust load of the orbiting scroll is supported by the fixed scroll by the pressure of the back pressure chamber, and the orbiting scroll A small pressure difference between the expansion chamber near the end of expansion formed by the outer wall side of the wrap and the inner wall side of the fixed scroll and the outer back pressure chamber via a thrust surface that supports the thrust load. Or set to a substantially discharge pressure.

As a result, the orbiting scroll is supported by the fixed scroll, and the optimum design of the double-structure back pressure chamber enables a configuration in which the orbiting scroll is slightly separated from the fixed scroll due to fluctuations in the pressure distribution in the expansion chamber. The working fluid in the oil or the oil atmosphere can be supplied to the thrust sliding portion using the separation gap, and the mechanical loss in the thrust sliding portion can be suppressed. In addition, the oil that has finished lubricating the thrust sliding portion flows into the expansion chamber near the end of expansion, but in the expansion chamber near the end of expansion, the influence on the expander performance due to the influence of oil inflow is relatively small. For this reason, there is little damage to the expander performance.

  The second invention is the first invention, in particular, in which oil supply means is provided on the thrust sliding surfaces of the orbiting scroll and the fixed scroll. As a result, oil can be positively supplied even when the lubrication of the thrust sliding portion is severe by merely supplying oil using the separation gap from the fixed scroll of the orbiting scroll.

  The third invention is particularly the second invention, wherein the oil supply means comprises at least one oil supply groove. In this case, it becomes possible to positively supply oil to the intended thrust sliding surface position depending on the configuration position of the oil supply groove, and it is also possible to locally cope with a lubriciously severe part in the thrust sliding part. .

  According to a fourth aspect of the present invention, a fixed scroll and a turning scroll where a spiral wrap rises from an end plate are meshed to form an expansion chamber between the two, and the turning scroll is formed into a circular orbit under the restriction of rotation by a rotation restriction mechanism. In the scroll expander provided with an expansion mechanism that performs suction, expansion, and discharge by moving the expansion chamber while changing the volume when swung along, the oil or oil atmosphere is provided on the back side of the orbiting scroll. A back pressure chamber in which the pressure of the working fluid acts is formed, and the thrust load of the orbiting scroll is supported by the fixed scroll by the pressure of the back pressure chamber, and the wrap outer wall side of the orbiting scroll and the wrap of the fixed scroll Between the expansion chamber near the end of expansion formed on the inner wall side and the back pressure chamber, the back pressure is adjusted using a means such as a back pressure adjustment mechanism. Pressure set higher than the discharge pressure of the pressure differential via a thrust surface for supporting the thrust load provided, in which communication via the back pressure chamber and said expansion chamber diaphragm portion. As a result, the orbiting scroll is stably supported by the fixed scroll, and oil can be supplied to the thrust sliding portion where the orbiting scroll is sliding appropriately through the throttle portion. The oil that has finished lubricating the thrust sliding portion is guided to the expansion chamber near the end of expansion, but in the expansion chamber near the end of expansion, the influence of the oil inflow on the expander performance is relatively small.

  The fifth aspect of the invention is the fourth aspect of the invention, in which the throttle portion is composed of at least one oil supply groove formed on the thrust sliding surface. As a result, oil can be actively supplied to the intended position, and a local response to a severely lubricated portion of the thrust sliding portion is also possible.

  The sixth aspect of the invention is particularly the third and fifth aspects of the present invention, wherein the flow direction in the oil supply groove is configured in substantially the same direction as the turning direction of the orbiting scroll. As a result, not only the differential pressure but also the oil supply effect due to the orbiting motion of the orbiting scroll is added, and a higher effect can be exhibited even in the case of high speed operation where the temperature rise of the thrust sliding portion is a concern.

  In a seventh aspect of the invention, in particular, in the fourth aspect of the invention, the throttle portion is configured by a wedge-shaped portion formed by pressure deformation of the end plate of the orbiting scroll. As a result, not only oil supply to the thrust sliding surface is more positively performed on the entire outer periphery of the orbiting scroll, but also more stable oil film generation due to the wedge effect can be expected.

  The eighth invention is the seventh invention, in particular, in which a groove portion that opens to the anti-thrust sliding surface side is formed on the end plate on the anti-thrust sliding surface side of the orbiting scroll, and a flexible structure portion is provided. is there. This makes it possible to intentionally control the wedge-shaped portion that cannot be controlled by the seventh aspect of the orbiting scroll due to the positive pressure deformation caused by the flexible structure portion.

  The ninth aspect of the invention is particularly the fourth aspect of the invention, wherein the throttle portion is constituted by a minute groove or a minute convex concave portion formed by etching or the like on the thrust sliding surface. This makes it possible to form the throttle part relatively easily over a wide range of the thrust sliding part, reducing the thrust sliding loss to the maximum and forming the fine throttle part, so that the amount of oil flowing into the expansion chamber Can be minimized.

  The tenth aspect of the invention is particularly any one of the first to ninth aspects of the invention, in which a high-pressure gas such as carbon dioxide is used as the working fluid. Since carbon dioxide has a larger differential pressure than a chlorofluorocarbon refrigerant, the loss at the thrust sliding portion is further increased, and the effects of the present invention can be further enhanced.

  According to an eleventh aspect of the present invention, in the refrigeration cycle apparatus having a compressor, a radiator, an expander, and an evaporator, the scroll expander according to any one of the first to tenth aspects is used as decompression means of the refrigeration cycle apparatus. Is. This makes it possible to recover energy that has been lost as an energy loss during decompression, and can improve the energy consumption efficiency of the entire refrigeration cycle apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of the scroll expander according to the first embodiment of the present invention. An orbiting scroll 13 that meshes with the fixed scroll 12 between the main bearing member 11 of the crankshaft 4 fixed by welding or shrink fitting in the sealed container 1 and the fixed scroll 12 bolted on the main bearing member 11. A scroll-type expansion mechanism 2 is formed by sandwiching a rotary scroll mechanism 13, and an anti-rotation mechanism 14 such as an Oldham ring that guides the orbiting scroll 13 to rotate in a circular orbit between the orbiting scroll 13 and the main bearing member 11. Is provided, and the orbiting scroll 13 is eccentrically driven by the eccentric shaft portion 4 a at the upper end of the crankshaft 4, thereby causing the orbiting scroll 13 to move circularly. As a result, the expansion pipe 15 formed between the fixed scroll 12 and the orbiting scroll 13 increases in volume while moving from the central portion to the outer peripheral side, and the suction pipe 16 communicating with the outside of the sealed container 1 is utilized. The working fluid is sucked from the suction port 17 at the center of the fixed scroll 12 and expands, and the working fluid having a predetermined pressure or less is discharged from the discharge port 18 on the outer peripheral side of the fixed scroll 12 to the outside of the sealed container 1. Repeat that.

  The power generated by the expansion of the working fluid is converted as electric power by the generator 3 disposed at the lower part of the expansion mechanism 2. In this embodiment, the generator 3 is used. However, if another compression mechanism is connected to the crankshaft 4, the power generated by the expansion can be used as it is as an assist for the compression mechanism.

  The other end side of the crankshaft 4 is supported by the auxiliary bearing member 21, and a pump 25 is provided at the tip end of the other end side of the crankshaft 4. The oil 6 is supplied from an oil reservoir 20 by a pump 25, and lubricates and cools the main bearing portion 11a and the eccentric bearing portion 11b through an oil supply path (not shown) provided in the axial center of the crankshaft 4. Thereafter, recirculation is performed through the oil return hole 26.

On the other hand, part of the oil 6 that has reached the eccentric bearing portion 11 b is decompressed by the throttle portion 28 provided inside the orbiting scroll 13 and supplied to the back pressure chamber 29. Here, a seal member 46 is disposed on the back of the end plate on the side opposite to the wrapping side of the orbiting scroll 13 as an annular sliding partition band that partitions the central portion and the outer peripheral portion. A high pressure that is approximately the suction pressure of the expansion mechanism 2 acts on the center portion side, and a low pressure that is approximately the discharge pressure of the expansion mechanism 2 acts on the outer peripheral portion side. The seal member 46 serves to seal the pressure of the oil 6 reaching the eccentric bearing portion 11b and the pressure of the back pressure chamber 29 on the low pressure side. The oil 6 supplied to the back pressure chamber 29 under reduced pressure flows into the expansion chamber 15 through a communication path 104 that connects the back pressure chamber 29 and the expansion chamber 15 near the end of expansion. The pressure in the back pressure chamber 29 may be a discharge pressure that is approximately low due to the resistance of the throttle portion 28 and the communication path 104, or may be slightly higher than the discharge pressure.

  With the above configuration, the orbiting scroll 13 is pressed against the fixed scroll 12 with an appropriate pressing force, and the thrust load of the orbiting scroll 13 is supported by the fixed scroll 12. However, the diameter of the seal member 46 and the back pressure chamber 29 are selected. By finely adjusting the pressure, it is possible to set a condition in which the orbiting scroll 13 is slightly separated from the fixed scroll 12 as the pressure distribution in the expansion chamber 15 varies. A separation that is too large causes a significant decrease in the performance of the expander 15, but there are many cases in which the performance of the expander 15 is not particularly lowered with respect to a small separation of a few μm level. The scroll 13 is set to generate a slight separation of several μm while being pressed against the fixed scroll 12 with an appropriate pressing force.

  When the above setting is performed, the thrust sliding portion 101 between the fixed scroll 12 and the orbiting scroll 13 enters a taste-moving movement state in which the orbiting movement is performed with a small gap of several μm during operation. The oil 6 in the back pressure chamber 29 flows into the thrust sliding portion 101 and the thrust sliding portion 101 can be lubricated effectively. Further, new oil 6 is always supplied to the thrust sliding portion 101 due to the miso movement, so that the oil 6 is prevented from staying and better thrust lubrication can be realized.

  Here, the pressure in the back pressure chamber 29 is preferably set to a low discharge pressure or a pressure slightly higher than the discharge pressure. If the pressure in the back pressure chamber 29 is intentionally set to be higher than the discharge pressure using a back pressure adjustment mechanism or the like, it is difficult to stably set the back pressure under the taste-impairing state, and there is a variation in reliability. It can be a factor. It is less difficult to set the pressure in the back pressure chamber 29 to a discharge pressure that is approximately low pressure or a pressure that is slightly higher than the discharge pressure.

  In the case of a scroll expander, the oil 6 that has flowed into the expansion chamber 15 from the back pressure chamber 29 hardly affects the expansion performance of the expansion mechanism 2. This is because the expansion stroke of the working fluid starts from the center portion of the lap, the expansion stroke is almost completed at the outer peripheral portion of the lap, and the discharge stroke is started. In the case of a scroll compressor, the place where the oil 6 flows in corresponds to the compression chamber near the start of compression, so if the high-temperature oil 6 flows in, it causes a large loss due to suction overheating. There are few.

  By using the configuration as described above, it is possible to provide a highly efficient scroll expander in which the thrust sliding portion 101 is highly reliable.

  In addition, when the supply of the oil 6 to the thrust sliding part 101 is insufficient, the supply means of the oil 6 may be intentionally provided on the orbiting scroll 13 side or the fixed scroll 12 side. Even when there is means for supplying the oil 6, the differential pressure between the back pressure chamber 29 and the expansion chamber 15 near the end of expansion is small, and the oil 6 is not excessively supplied.

FIG. 2 is a plan view of a main part in the first embodiment or the second embodiment described later. As shown in FIG. 2, an example of the supply means for the oil 6 includes at least one oil supply groove 103. In the example, the oil supply groove 103 is provided on the thrust surface of the fixed scroll 12 which is the thrust sliding portion 101 of the orbiting scroll 13. The oil supply groove 103 is formed by a relatively thin shallow groove. When the oil supply groove 103 exists,
The adjustment of the pressure in the back pressure chamber 29 is naturally different from the adjustment described above, and an optimization design for each specification is required.

  The oil supply groove 103 can be configured at an arbitrary position. However, when the lubrication state of the thrust sliding portion 101 is configured at a severe position, oil can be positively supplied to the portion. . Thereby, the scroll expander in which the lubrication state of the thrust sliding portion is better can be provided.

  Further, when the flow direction in the oil supply groove 103 is configured in the same direction as the turning direction of the orbiting scroll 13, the pumping effect of the end plate portion of the orbiting scroll 13 that orbits in the back pressure chamber 29 causes the oil 6 pumping effect. Can also be expected. During high-speed operation, which is concerned about the temperature rise of the thrust sliding portion 101, the pumping effect is further enhanced, and not only depends on the pressure difference, but also a higher lubrication environment using a turning motion can be realized.

(Embodiment 2)
Detailed descriptions of portions that are the same as those in the first embodiment of the present invention are omitted, but portions that are different from the first embodiment will be described in detail below with reference to FIG.

  FIG. 3 is a sectional view of a scroll expander according to the second embodiment of the present invention. As shown in FIG. 3, a seal member 46 that partitions the central portion and the outer peripheral portion is disposed on the rear surface of the scroll 13 on the side opposite to the wrap. The seal member 46 has a role of sealing the pressure of the oil 6 reaching the eccentric bearing portion 11 b and the pressure of the back pressure chamber 29. As the oil 6 supplied to the back pressure chamber 29 accumulates, the pressure in the back pressure chamber 29 rises. In order to keep the pressure constant, the back pressure adjusting mechanism 9 is configured. When the pressure becomes higher than the set pressure, the back pressure adjusting mechanism 9 is activated. The outlet side of the back pressure adjustment mechanism 9 communicates with the discharge port 18, and the pressure in the back pressure chamber 29 can be adjusted to an arbitrary pressure higher than the discharge pressure of the expansion mechanism 2. The back pressure adjusting mechanism 9 used in the scroll compressor as in the prior art (Patent Document 1) can be applied to the scroll expander as it is.

  With the above configuration, the orbiting scroll 13 is pressed against the fixed scroll 12 with an appropriate pressing force without the orbiting scroll 13 being separated from the fixed scroll 12, and the thrust load is supported by the fixed scroll 12.

  Since the scroll fluid machine is a positive displacement fluid machine, the compression ratio or the expansion ratio is determined by the scroll wrap shape when no special configuration is used. Even if the scroll expander is operated within a certain operating pressure range and overexpansion or underexpansion occurs, the selection of the wrap shape and the adjustment of the back pressure adjusting mechanism 9 are performed optimally, so that the back pressure chamber 29 The pressure can be set to an optimum value. In the present embodiment, the pressure of the back pressure chamber 29 is set higher than the pressure of the expansion chamber 15 near the end of expansion formed by the wrap outer wall side of the orbiting scroll 13 and the wrap inner wall side of the fixed scroll 12. .

  By adopting the above configuration, the pressure in the back pressure chamber 29 where the oil 6 is rich is higher and the expansion chamber 15 is lower through the thrust sliding portion 101 between the fixed scroll 12 and the orbiting scroll 13. It becomes. As a matter of course, the thrust sliding portion 101 intervenes oil 6 and performs thrust lubrication with an appropriate oil film force. However, the oil film force is not necessarily generated uniformly. In the portion where the oil film force is reduced, the thrust sliding portion 101 itself acts as a throttle portion, and the oil 6 is supplied to the thrust sliding portion 101 due to the pressure difference described above, and not only brings about a cooling action but also the oil 6 Stagnation is prevented and better thrust lubrication can be realized.

  In the case of a scroll expander, the oil 6 that has flowed from the back pressure chamber 29 into the expansion chamber 15 does not significantly affect the performance of the expansion mechanism 2. This is because the expansion stroke of the working fluid starts from the center portion of the lap, the expansion stroke is almost completed at the outer peripheral portion of the lap, and the discharge stroke is started. In the case of the scroll compressor, the place where the oil 6 flows in corresponds to the compression chamber near the start of compression. Therefore, when the high-temperature oil 6 flows in, the suction overheat loss occurs and causes a large loss. Therefore, in the case of the scroll compressor, the oil 6 cannot be actively introduced, and it has been a problem to achieve both efficiency and reliability of the thrust sliding portion.

  However, in the scroll expander, there is little need to pay special attention to the inflow of the oil 6, and it is very easy to achieve both efficiency and reliability of the thrust sliding portion. Thereby, the reliability of the thrust sliding part 101 is high, and a highly efficient scroll expander can be provided.

  Further, the above effect can be similarly obtained even in a configuration in which the seal member 5 that partitions the center portion and the outer peripheral portion is not disposed on the back surface of the end-wrap side of the orbiting scroll 13 (not shown).

  Although similar to the first embodiment of the present invention, as shown in FIG. 2, the throttle portion may be configured on the thrust surface of the fixed scroll 12 that is the thrust sliding portion 101 with the orbiting scroll 13. . In FIG. 2, two oil supply grooves 103 are provided along the rotation direction of the orbiting scroll 13, so that a narrowing effect is generated due to viscous resistance even when the oil 6 flows due to a relatively thin shallow groove. belongs to. With this configuration, oil is positively supplied by the pressure in the back pressure chamber 29 and the rotation of the orbiting scroll 13, and the lubricity of the thrust sliding portion 101 is further improved.

  When the oil supply groove 103 exists, the pressure of the back pressure chamber 29 is determined in consideration of the back pressure adjusting mechanism 9 and the throttle effect of the oil supply groove 103, but can be set to an arbitrary pressure by optimization. It is. In order to generate the squeezing effect, the oil supply groove 103 may be locally squeezed.

  Further, when the flow direction in the oil supply groove 103 is configured to be substantially the same as the turning direction of the orbiting scroll 13 and along the rotation direction, the same effect as that of the first embodiment of the present invention can be obtained. it can.

  As another configuration of the aperture portion, a configuration as shown in FIG. 4 may be used. FIG. 4 shows an example of the configuration of the throttle section in the second embodiment of the present invention, and conceptually shows the state of pressure deformation during operation of the orbiting scroll and the fixed scroll.

  In this configuration example, the orbiting scroll 13 is pressed against the fixed scroll 12 by a pressure difference, and the elastic deformation in which the surroundings are lifted as shown in FIG. 4 is caused. The amount of elastic deformation varies depending on the rigidity of the end plate 13a of the orbiting scroll 13 and the like, and none of them is a very large amount and is about several μm to 20 μm or less, and the wedge-shaped portion 102 is formed on the thrust sliding portion 101. Is.

  On the lubrication surface of the thrust sliding portion 101, the wedge-shaped portion 102 not only compensates for the generation of oil film force due to the wedge effect, but also acts as a narrow gap narrowing portion to promote the inflow of the oil 6. This deformation can occur on the entire outer periphery of the end plate 13a of the orbiting scroll 13, and a great improvement in sliding of the thrust sliding portion 101 can be expected, and a more efficient scroll expander can be provided.

  FIG. 5 is a plan view of the main part of the orbiting scroll 13 as viewed from the anti-thrust sliding surface side. As shown in FIG. 5, a groove portion 105 that opens to the anti-thrust sliding surface side is formed in the end plate 13a on the anti-thrust sliding surface side of the orbiting scroll 13, and a flexible structure portion is provided on the end plate 13a. The configuration of the unit 102 can be facilitated, and the amount of deformation can be intentionally controlled. The groove portion 105 may be substantially annular or may be a plurality of grooves that are partially interrupted, and is not subject to any special shape limitation.

  This is a result of the rigidity of the end plate 13a of the orbiting scroll 13 being reduced in the vicinity of the groove 105 and the elastic deformation being promoted, and the wedge-shaped portion 102 can be controlled by controlling the rigidity.

  As another configuration of the aperture portion, a configuration as shown in FIG. When the micro-groove 106 formed on the thrust sliding surface 101 of the fixed scroll 12 by etching or the like is configured over a wide range, the sliding loss reducing effect on the thrust sliding surface 101 becomes more effective. When the etching process is used, the throttle part can be formed over a wide range relatively easily, and the throttle effect of the throttle part itself can be increased, so that the amount of oil 6 flowing into the expansion chamber 15 is reduced to the minimum necessary amount. It becomes possible to suppress to. Although some measures can be taken by providing a large number of oil supply grooves by machining, there is a limit to realizing the required throttling effect, resulting in excessive inflow of oil 6 into the expansion chamber 15. . Providing a large number of micro grooves 106 formed by etching or the like is very effective as a countermeasure for a situation where the lubrication state of the thrust sliding surface 101 is more severe.

  In the first or second embodiment of the present invention, when the working fluid is a high-pressure refrigerant, for example, carbon dioxide, the differential pressure is larger than that of the chlorofluorocarbon-based refrigerant. However, the effect of the present invention can be further enhanced.

  Further, in a refrigeration cycle apparatus having a compressor, a radiator, an expander, and an evaporator, when a scroll expander is used as a decompression means of the refrigeration cycle apparatus, energy recovery that has been lost as an energy loss at the time of decompression is conventionally performed. Thus, the energy consumption efficiency of the entire refrigeration cycle apparatus can be increased. When the refrigerant of the refrigeration cycle apparatus is carbon dioxide, the theoretical recovery power in the expansion process is much larger than that of the chlorofluorocarbon refrigerant, so that the energy recovery effect is very large.

  As described above, since the scroll expander according to the present invention can improve the lubrication state at the thrust sliding portion of the orbiting scroll and the fixed scroll, it is a highly reliable and highly efficient scroll expander. be able to. Further, the present invention can be applied to a scroll expander that uses air or helium as a working fluid without limiting the working fluid to a refrigerant.

The longitudinal cross-sectional view of the scroll expander in Embodiment 1 of this invention The principal part top view of the scroll expander in Embodiment 1 of this invention The longitudinal cross-sectional view of the scroll expander in Embodiment 2 of this invention The conceptual diagram which shows the principal part of the scroll expander in Embodiment 2 of this invention. The principal part top view of the scroll expander in Embodiment 2 of this invention The principal part top view of the scroll expander in Embodiment 2 of this invention The top view which shows the structure of the thrust sliding part in the conventional scroll compressor

Explanation of symbols

2 Expansion mechanism 6 Oil 12 Fixed scroll 13 Orbiting scroll 14 Rotation restriction mechanism 15 Expansion chamber 27 Working fluid 29 Back pressure chamber 101 Thrust sliding portion 102 Wedge shape portion 103 Oil supply groove 104 Connection path 105 Groove portion 106 Micro groove

Claims (3)

When the fixed scroll and the orbiting scroll where the spiral wrap rises from the end plate are engaged to form an expansion chamber between the two, and the orbiting scroll is orbited along a circular orbit under the restriction of rotation by the rotation restricting mechanism In the scroll expander including an expansion mechanism that performs suction, expansion, and discharge by moving the expansion chamber while changing the volume,
On the back side of the orbiting scroll, a back pressure chamber in which the pressure of the working fluid in the oil or oil atmosphere acts is formed, and the thrust load of the orbiting scroll is supported by the fixed scroll by the pressure of the back pressure chamber, Using a means such as a back pressure adjusting mechanism between the expansion chamber near the end of expansion formed on the wrap outer wall side of the orbiting scroll and the wrap inner wall side of the fixed scroll, and the back pressure chamber, the back pressure chamber pressure is set higher than the discharge pressure, provided the pressure differential via a thrust surface for supporting the thrust load, and communicating through said back pressure chamber and said expansion chamber diaphragm portion,
The throttle part is at least one oil supply groove formed on a thrust sliding surface, and a flow direction in the oil supply groove is substantially the same as a turning direction of the orbiting scroll. Scroll expander to do. The scroll expander according to claim 1, wherein the working fluid is a high-pressure refrigerant, for example, carbon dioxide. The scroll expander according to claim 1 or 2, wherein the scroll expander is used as decompression means of the refrigeration cycle apparatus in a refrigeration cycle apparatus having a compressor, a radiator, an expander, and an evaporator.

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