JP4807056B2 - Scroll expander - Google Patents

Description

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

  Conventionally, this type of scroll fluid machine (compressor) has a spiral wrap winding start portion of each scroll, an outer arc in which the wrap tip smoothly connects to the winding start point of the outer wall involute curve, and the inner wall involute curve winding. An arc composed of two arcs of a starting point and an inner arc smoothly connected, and an outer arc whose wrap end smoothly connects with the winding start point of the outer wall involute curve of the spiral wrap of each scroll, There is one constituted by two arcs of a winding start point of an inner wall involute curve and an inner arc that is not smoothly connected (for example, see Patent Document 1).

  That is, the scroll compressor has two compression chambers as shown in FIGS. 4 and 5, and a first compression chamber 25a formed by an inner wall surface 26d of the orbiting scroll wrap 26b and an outer wall surface 24c of the fixed scroll wrap 24b. The second compression chamber 25b is formed by the outer wall surface 26e of the orbiting scroll wrap 26b and the inner wall surface 24d of the fixed scroll wrap 24b, and both the compression chambers 25a and 25b are arranged in the center direction of the scroll. The gas in the compression chamber is compressed by the relative movement of both scrolls so as to reduce the volume as it moves, and is discharged from the discharge hole 21.

  Since the second compression chamber 25b reaches the design volume ratio (suction volume / discharge volume) and then communicates with the discharge hole 21 (arrow X in FIG. 5), a sufficient discharge passage can be secured. In contrast, the first compression chamber 25a communicates with the discharge hole 21 only after passing through between the inner wall surface 26d of the orbiting scroll wrap 26b and the outer wall surface 24c of the fixed scroll wrap 24b (arrow Y in FIG. 5). Not.

  However, when the compressed gas flows into the discharge chamber, it passes between the wall surfaces of the scroll wrap, but if the distance between the wraps is narrow, the resistance of the discharge gas passage (hereinafter referred to as discharge resistance) increases, so the compressor input is It has the problem of increasing and reducing efficiency.

To solve the above problem, as shown in FIG. 6, the winding start portion of the fixed scroll wrap 24b is connected to the outer arc 24e in which the wrap tip smoothly connects to the winding start point B of the outer involute curve, and the inner involute winding. A scroll having a configuration in which the starting point A and the inner arc 24f that is not smoothly connected constitute two arcs to widen the gas passage immediately after discharge, reduce the increase in compressor input due to discharge resistance, and improve compression efficiency. A compressor has been proposed.
JP 2000-120565 A

  However, when the scroll fluid machine is used as an expander, the refrigerant confined by the expansion chamber formed in the winding start portion of the involute curve expands by moving to the winding end portion. In particular, when the working fluid is carbon dioxide refrigerant, the density is high, so suction pulsation occurs, and if the pipe breaks due to the pipe vibration of the expander or the water hammer phenomenon occurs at the same time, there is a problem that lap breakage occurs. It was.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a scroll expander that realizes high reliability by preventing pipe breakage and lap breakage even when a scroll fluid machine is used as an expander. To do.

  In order to solve the above-described conventional problems, the scroll fluid machine of the present invention is configured so that the winding start portion of the spiral wrap of the orbiting scroll is both at the outer wall winding start point of the outer wall involute curve and the inner wall winding start point of the inner wall involute curve. It is formed by one outer arc that connects smoothly. As a result, the suction points of the two expansion chambers formed in the scroll expander can be shifted by 180 °, so that the suction pulsation can be reduced. At the same time, the strength of the wrap at the winding start portion of the orbiting scroll can be increased, so that a scroll expander that prevents pipe breakage and wrap breakage and realizes high reliability is provided.

  The scroll expander of the present invention can achieve high reliability, particularly when a carbon dioxide refrigerant, which is a high pressure / low compression ratio refrigerant, is used.

  In the first invention, the winding start portion of the spiral wrap of the orbiting scroll is formed by one outer arc smoothly connected to both the outer wall starting point of the outer wall involute curve and the inner wall winding starting point of the inner wall involute curve. Is. As a result, the suction points of the two expansion chambers formed in the scroll expander can be shifted by 180 °, so that the suction pulsation can be reduced. At the same time, the strength of the wrap at the winding start portion of the orbiting scroll can be increased, so that a scroll expander that achieves high reliability can be provided.

  In particular, the second invention is a first outer arc that smoothly connects the winding start portion of the spiral wrap of the fixed scroll to the outer wall winding start point of the outer wall involute curve, and the inner wall of the inner wall involute curve of the first invention. From the point where the outer wall winding start point of the outer wall involute curve of the orbiting scroll is in contact with the inner wall involute curve of the fixed scroll, comprising a winding start point and a second inner arc smoothly connected to both the first outer arc Also, the inner wall winding start point of the inner wall involute curve of the fixed scroll is formed on the winding start side. As a result, the suction port can be made larger, so that the pressure loss due to suction can be reduced while reducing the suction pulsation, providing a scroll expander that realizes higher reliability and higher efficiency. can do.

  The third aspect of the invention is particularly the swirl wrap of the fixed scroll by the inner wall involute curve of the fixed scroll swirl wrap extending to the vicinity of the winding end of the outer wall involute curve of the swirl scroll spiral wrap of the first and second inventions. The inner wall is formed. Thereby, since the volume ratio of the expansion chamber formed on the outer wall side of the spiral wrap of the orbiting scroll and the expansion chamber formed on the inner wall side can be made substantially equal, there is little overexpansion loss and insufficient expansion loss, A scroll expander that achieves higher efficiency can be provided.

In the fourth invention, the orbiting scroll is made of an aluminum-based metal material and the fixed scroll is made of an iron-based metal material, in particular, in the first to third inventions. The seizure load when pressing the iron-based metal material and the aluminum-based metal material is higher than the seizure load when pressing the iron-based materials, so that galling and abnormal wear can be suppressed. In addition, since the aluminum-based metal material has a lower density than the iron-based metal material, the centrifugal force during operation can be kept small, so that the load on the shaft can be reduced. As a result, it is possible to provide a scroll expander that realizes higher efficiency by reducing the loss of the bearing portion. In addition, since the aluminum-based metal material has lower rigidity than the iron-based metal material, the amount of distortion of the orbiting scroll is larger than that of the fixed scroll, and it slides strongly at the center. As a result, the winding start portion of the orbiting scroll generates a greater stress than the winding start portion of the fixed scroll. However, when the orbiting scroll winding start portion is configured by one arc, the generation of stress can be suppressed to a small value. Therefore, a more reliable scroll expander can be provided.

  In the fifth invention, in particular, the refrigerant as the working fluid of the first to fourth inventions is carbon dioxide. As a result, carbon dioxide has a larger power recovery effect by the expander than other working fluids, so if a scroll expander that achieves high reliability and high efficiency is used, higher reliability and high efficiency characteristics can be achieved. A refrigeration cycle apparatus having the above can be provided.

  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)
1 is a sectional view of a scroll expander according to Embodiment 1 of the present invention.

  In FIG. 1, a main bearing member 11 that pivotally supports a main shaft portion 4 a of a crankshaft 4 fixed by welding or shrink fitting in the sealed container 1, and a fixed scroll 12 bolted on the main bearing member 11. A scroll-type expansion mechanism is formed by sandwiching the orbiting scroll 13 that meshes with the fixed scroll 12 between them, so that the orbiting scroll 13 is prevented from rotating between the orbiting scroll 13 and the main bearing member 11 and moves in a circular orbit. A rotation restricting mechanism 14 is provided by an Oldham ring or the like that guides the motor.

  In the above configuration, the orbiting scroll 13 is eccentrically driven by the eccentric shaft portion 4 b at the upper end of the crankshaft 4 to cause the orbiting scroll 13 to move in a circular orbit, thereby forming between the fixed scroll 12 and the orbiting scroll 13. A refrigerant gas is sucked from a suction pipe 16 communicating with the outside of the hermetic container 1 and a suction port 17 at the center of the fixed scroll 12 by using the expansion chamber 15 which is enlarged while moving from the center to the outer peripheral side. The refrigerant gas that has been expanded and reduced to a predetermined pressure or less is repeatedly discharged out of the sealed container 1 from the discharge port 18 on the outer peripheral side of the fixed scroll 12.

  Further, the other end side of the crankshaft 4 is supported by the auxiliary bearing member 21, and a positive displacement pump 25 is provided at the tip of the other end side of the crankshaft 4. The lubricating oil 6 lubricates and cools the main bearing portion 11a and the eccentric bearing portion 11b through a lubricating oil reservoir 20 through a positive displacement pump 25 (not shown) provided in the center of the crankshaft 4 in the axial direction. After that, recirculation is performed through the lubricating oil return hole 26. On the other hand, a part of the lubricating oil 6 that has reached the eccentric bearing portion 11 b is depressurized from the throttle passage 28 provided inside the orbiting scroll 13 and supplied to the back pressure chamber 29. A seal member 5 that partitions the central portion and the outer peripheral portion is disposed on the back surface of the end plate on the opposite side of the orbiting scroll 13. The seal member 5 has a role of partitioning the pressure of the lubricating oil 6 reaching the eccentric bearing portion 11 b and the pressure of the back pressure chamber 29. The lubricating oil 6 supplied to the back pressure chamber 29 is discharged out of the sealed container 1 together with the discharged refrigerant.

FIG. 2 is an enlarged plan view of the main part of the winding start portion of the orbiting scroll wrap and the fixed scroll wrap in the scroll expander of the present embodiment. A wrap outer wall from the outer wall winding starting point A of the orbiting scroll 13 toward the outer peripheral side is configured by an outer wall involute curve, and a lap inner wall from the inner wall winding initial point B of the orbiting scroll 13 toward the outer peripheral side is configured by an inner wall involute curve. A point A and a point B at the winding start portion of the orbiting scroll 13 are smoothly connected by a single arc. FIG. 2A shows the time when the outer wall of the orbiting scroll 13 forms the expansion chamber 15 and the closing is completed (immediately after the start of the expansion process), and FIG. 2B shows the inner wall of the orbiting scroll 13 as the expansion chamber 15. The time when the closing is completed is shown. As can be seen from these figures, between the winding start point A and point B of the orbiting scroll 13, when smoothly connected by one arc, the expansion chamber formed by the outer wall of the orbiting scroll 13 is formed. 15 and the expansion chamber 15 formed by the inner wall can change the phase by 180 °. As a result, since the refrigerant can be sucked into two times per one rotation, the suction pulsation can be suppressed small, so that the pipe breakage due to the pipe vibration of the expander can be prevented.

  Further, if the winding start portion of the orbiting scroll 13 is formed by one arc, the corner stress concentration value when an external force is applied can be lowered, and the strength of the wrap is increased. In particular, when the working fluid is a carbon dioxide refrigerant, the density is high, so that in addition to vibration due to suction pulsation, even when a water hammer phenomenon occurs, wrap breakage can be prevented and high reliability can be ensured.

  Further, the outer wall wrap outer wall from the outer wall winding starting point C of the fixed scroll 12 toward the outer peripheral side is configured by an outer wall involute curve, and the inner wall wrap inner wall from the inner wall winding initial point E of the fixed scroll 12 to the outer peripheral side is configured by an inner wall involute curve. Yes. A first arc that smoothly connects to the outer wall involute curve at the point C of the winding start portion of the fixed scroll 12 and a second arc that smoothly connects to the outer wall involute curve at the point E are points C and E. The connection is made smoothly at a point D between them. Further, the outer wall winding start point A of the orbiting scroll 13 forms the inner wall winding start point E of the fixed scroll 12 on the winding start side from the place where the inner wall of the fixed scroll 12 and the expansion chamber 15 are formed. As can be seen from the figure, if the inner wall winding start point E of the fixed scroll 12 is formed on the winding start side, the wrap thickness does not increase, so that the suction port 17 can be formed larger. As a result, the pressure loss due to the suction can be reduced while the suction pulsation is further reduced, so that higher reliability and higher efficiency can be realized.

  FIG. 3 is a plan view of the orbiting scroll wrap and the fixed scroll wrap in the scroll expander of this embodiment. When the winding start portion of the orbiting scroll 13 is connected by one arc, the volume ratio of the expansion chamber 15 formed by the outer wall of the orbiting scroll 13 is smaller than that of the expansion chamber 15 formed by the inner wall. As can be seen, the inner wall involute curve of the spiral wrap of the orbiting scroll 13 is formed on the outer wall side of the spiral wrap of the orbiting scroll 13 by the inner wall involute curve of the spiral wrap of the fixed scroll 12 extending to the vicinity of the winding end of the outer wall involute curve of the orbiting scroll 13. The volume ratio between the expansion chamber 15 and the expansion chamber 15 formed on the inner wall side can be made substantially equal. As a result, it is possible to provide a scroll expander that achieves higher efficiency with less overexpansion loss and insufficient expansion loss.

  When the orbiting scroll 13 is made of an aluminum-based metal material and the fixed scroll 12 is made of an iron-based metal material, if the winding start portion of the orbiting scroll 13 is composed of one arc, the stress concentration when force is applied Since the value can be lowered, high reliability can be maintained even if an aluminum-based metal material that is weaker than the iron-based metal material is used for the orbiting scroll 13. On the other hand, since the aluminum-based metal material has a lower density than the iron-based metal material, the centrifugal force during operation can be kept small, so that the load on the shaft can be reduced. As a result, it is possible to provide a scroll expander that realizes higher efficiency by reducing the loss of the bearing portion.

When the orbiting scroll 13 is formed of an aluminum-based metal material and the fixed scroll 12 is formed of an iron-based metal material, the seizure load when pressing the iron-based metal material and the aluminum-based metal material is the same between the iron-based materials. Higher than the seizure load when pressing, especially under the presence of refrigeration oil in a carbon dioxide refrigerant atmosphere, the seizure load when pressing ferrous and aluminum materials presses the ferrous materials together Since it is about twice as high as the seizure load in the case, galling and abnormal wear can be suppressed. In addition, since the aluminum-based metal material has a lower density than the iron-based metal material, the centrifugal force during operation can be kept small, so that the load on the shaft can be reduced. As a result, it is possible to provide a scroll expander that realizes higher efficiency by reducing the loss of the bearing portion. In addition, since the aluminum-based metal material has lower rigidity than the iron-based metal material, the amount of distortion of the orbiting scroll 13 is larger than that of the fixed scroll 12, and it slides strongly at the center. As a result, the winding start portion of the orbiting scroll 13 generates a greater stress than the winding start portion of the fixed scroll 12. However, when the winding start portion of the orbiting scroll 13 is configured by one arc, the stress generation is reduced. Since it can suppress, a more reliable scroll expander can be provided.

  In addition, when the refrigerant | coolant as a working fluid is carbon dioxide, since the power recovery effect by an expander is large compared with another working fluid, the scroll expander which implement | achieves high reliability and high efficiency. Can be used to provide a refrigeration cycle apparatus having higher reliability and higher efficiency.

  As described above, the scroll expander according to the present invention smoothly connects the winding start portion of the spiral wrap of the orbiting scroll to both the outer wall winding start point of the outer wall involute curve and the inner wall winding start point of the inner wall involute curve. Are formed by one outer arc. As a result, the suction points of the two expansion chambers formed in the scroll expander can be shifted by 180 °, so that the suction pulsation can be reduced. At the same time, it is possible to increase the strength of the wrap at the winding start portion of the orbiting scroll, so that it is possible to provide a scroll expander that prevents pipe breakage and wrap breakage and achieves high reliability, so that the working fluid is limited to refrigerant. Without limitation, the present invention can be applied to a scroll fluid machine including air and helium as a working fluid and a scroll fluid machine including a compressor.

Sectional drawing of the scroll expander in Embodiment 1 of this invention The principal part enlarged plan view of the winding start part of the turning scroll wrap and fixed scroll wrap in Embodiment 1 of this invention The top view of the turning scroll wrap and the fixed scroll wrap in Embodiment 1 of this invention The principal part top view which shows the compression chamber in the conventional scroll compressor The main part enlarged plan view of the lap center in the conventional scroll compressor Main part enlarged plan view of lap center in another conventional scroll compressor

Explanation of symbols

2 Compression Mechanism 5 Seal Member 6 Lubricating Oil 12 Fixed Scroll 13 Orbiting Scroll 14 Rotation Restriction Mechanism 15 Expansion Chamber 17 Suction Port 29 Back Pressure Chamber 30 Groove 31 Communication Path 32 Narrow Hole 33 Ring Groove 34 Seal Member

Claims (4)

An expansion chamber is formed between the fixed scroll and the orbiting scroll where the spiral wrap rises from the end plate, and when the orbiting scroll is swung under the restriction of rotation by the rotation restriction mechanism, the expansion chamber has a volume. In the scroll expander that sucks and discharges the working fluid by moving while changing
A winding start portion of the spiral wrap of the orbiting scroll is formed by one outer arc smoothly connected to both the outer wall winding start point of the outer wall involute curve and the inner wall winding start point of the inner wall involute curve ;
A first outer arc smoothly connecting the winding start portion of the spiral wrap of the fixed scroll to the outer wall winding start point of the outer wall involute curve, and both the inner wall winding start point of the inner wall involute curve and the first outer arc The inner wall of the inner wall involute curve of the fixed scroll than the point where the outer wall winding start point of the outer wall involute curve of the orbiting scroll is in contact with the inner wall involute curve of the fixed scroll. A scroll expander characterized in that a winding start point is formed on a winding start side. By the inner wall involute curve of the spiral wrap of said fixed scroll extending to the winding end near the outer wall involute curve of the spiral wrap of the orbiting scroll, to claim 1, characterized in that the formation of the inner wall of the spiral wrap of the fixed scroll The scroll expander described. 3. The scroll expander according to claim 1, wherein the orbiting scroll is made of an aluminum-based metal material and the fixed scroll is made of an iron-based metal material. 4. The scroll expander according to any one of claims 1 to 3 , wherein the refrigerant as the working fluid is carbon dioxide.

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