JP2006037867A - Scroll compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the compression ratio of a scroll compressor and decrease a power loss due to supercompression. <P>SOLUTION: A fixed scroll 10 and a moving scroll 20 on which spiral laps 12 and 22 are erected on the inner surfaces of end plates 11 and 21, respectively, are combined together and compression chambers S1 and S2 moved to the central side as a volume is decreased are formed between the two laps. An inner peripheral surface 12b of one lap consists of a first part 12b1 composed of a part of an inner spiral surface H2 slidably contacting with an outer peripheral surface 22a of the other lap; a recessed circular arc-shaped second part 12b2 continuously connected to the first part and slidably contacting with a small circular face 22c at the tip on the central side of the other lap; a fourth part 12b4 positioned further on the outside in a radial direction than the extension face of the second part and connected to a small circular arc face; and a third part 12b3 discontinuously connected to the second part and rapidly outwardly separated from the extension face of the second part and connected to the fourth part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a scroll compressor, and more particularly to a scroll compressor having a high compression ratio and reduced power loss due to overcompression.

As a scroll compressor that reduces power loss due to overcompression, there is a technique disclosed in Japanese Patent Laid-Open No. 2000-120565 (Patent Document 1). This is a fixed scroll in which a spiral wrap made of an involute curve is erected on an end plate having a discharge hole in the center, and a turning scroll in which a spiral wrap made of an involute curve is erected on the end plate facing the fixed scroll , And a scroll compressor comprising a plurality of compression chambers each comprising a plurality of compression chambers, and the winding start portion of each scroll wrap is smoothly connected to the winding start point of the outer involute curve. It is formed by an outer arc and an inner arc that is discontinuously connected to the winding start point of the inner involute, and the center point of the outer arc is provided on the tangent line of the base circle passing through the winding start point of the outer involute curve, while the outer arc The contact point between the inner arc and the inner arc is provided on a straight line connecting the center point of the outer arc and the center point of the inner arc. According to such a configuration, the gas passage immediately after each compression chamber is communicated with the central chamber in which the discharge holes are formed is widened to reduce power loss due to overcompression due to the discharge resistance and increase the compressor input. The effect that it can reduce and can improve compressor efficiency is acquired.
Japanese Unexamined Patent Publication No. 2000-120565 (paragraph [0006], paragraph [0015]], FIGS. 2 to 4).

  However, in the prior art including Patent Document 1, when increasing the compression ratio without increasing the cylinder diameter of the scroll compressor, it is necessary to extend the scroll spiral to the center side to accelerate the spiral start point. As a result, the central chamber becomes narrow and it becomes difficult to secure a communication area between the compression chambers and the central chamber, and the effect of reducing the discharge resistance becomes insufficient, resulting in increased power loss due to overcompression. is there. Further, if the inner arc is widened so as to secure a communication area between the compression chambers and the central chamber, there arises a problem that the thickness of the central end portion of the scroll wrap becomes small and the strength of the portion becomes insufficient.

  This problem will be described in more detail with reference to FIG. This scroll compressor is composed of a pair of a fixed scroll wrap 1 and a movable scroll wrap 2, and the movable wrap 2 is assembled so as to turn without rotating with respect to the fixed wrap 1. The inner peripheral surface 1b of the fixed side wrap 1 and the outer peripheral surface 2a of the movable side wrap 2 and the inner peripheral surface 2b of the movable side wrap 2 and the outer peripheral surface 1a of the fixed side wrap 1 are in contact with each other at a plurality of locations. A plurality of compression chambers T1 and T2 are respectively formed, and a central chamber T3 is formed between the inner peripheral surface 1b of the fixed side wrap 1 and the inner peripheral surface 2b of the movable side wrap 2 at the central portion. The end plate (not shown) is formed with a discharge hole 5 opened to the central chamber T3.

  The fixed-side wrap 1 is composed of an outer peripheral surface 1a, an inner peripheral surface 1b, and a small circular arc surface 1c that continuously connects the central ends of both peripheral surfaces 1a and 1b. The outer peripheral surface 1a is a part of an involute having a two-dot chain line circle 1d as a base circle, and a connection point Q1 with the small circular arc surface 1c is a winding start point. The inner peripheral surface 1b is composed of a spiral surface 1b1 that is a part of an involute based on a circle 1d common to the outer peripheral surface 1a, and a short flat surface 1b2 that continuously connects the spiral surface 1b1 and the small arc surface 1c. Therefore, the connection point Q2 with the plane 1b2 is the winding start point of the spiral surface 1b1. The shape of the movable wrap 2 is basically the same as the shape of the fixed wrap 1.

  As shown in FIG. 10, if the movable side wrap 2 turns without rotating relative to the fixed side wrap 1, the center Q4 of the small circular arc surface 2c of the movable side wrap 2 has the same radius as the turning radius around the central axis O1. Accordingly, both the compression chambers T1 and T2 move to the center side while the volume gradually decreases, and the gas confined in the compression chambers T1 and T2 is compressed. After the movable side wrap 2 reaches the position of the two-dot chain line 2A and the winding start point Q1 of the outer peripheral surface 2a reaches the seal-off position Q5 of the inner peripheral surface 1b of the fixed side wrap 1, the two-dot chain lines 2B and 2C As shown in FIG. 2, the movable wrap 2 is separated from the inner peripheral surface 1b of the fixed wrap 1 and passes through a communication path formed between the inner peripheral surface 1b and the small arc surface 2c of the movable wrap 2. The gas compressed in the compression chambers T1 and T2 is sent into the central chamber T3. A broken line c in FIG. 8 shows a change characteristic of the communication area of the communication path with respect to the turning angle of the movable wrap 2. The communication area between the inner peripheral surface 1b of the fixed side wrap 1 and the small circular arc surface 2c of the movable side wrap 2 begins to open at the seal-off position Q5 and gradually increases as shown by the broken line c. Therefore, the communication area between the compression chambers T1, T2 and the central chamber T3 immediately after the start of discharge is not sufficient, and there is a problem in that the gas in the compression chambers T1, T2 compression chamber is overcompressed to cause power loss.

  In the scroll compressor shown in FIG. 10, when the compression ratio is to be increased without increasing the body diameter, the winding start point Q1 of the outer peripheral surfaces 1a, 2a of the scrolls 1, 2 is brought closer to the basic circle 1d and It is necessary to extend the surfaces 1a and 2a toward the center and move the seal-off position Q5 of the inner peripheral surfaces 1b and 2b toward the center. However, when doing so, the central chamber T3 becomes narrow, and it becomes difficult to secure a communication path between the compression chambers T1, T2 and the central chamber T3 after the winding start point Q1 passes the seal-off position Q5. There is a problem that power loss due to overcompression increases.

  On the other hand, in Patent Document 1, an inner arc that is discontinuously connected to the winding start point (corresponding to the seal-off position Q5 in FIG. 10) of the inner involute of the wrap is provided, and this inner arc further extends from the winding start point to the basic circle. Since the orbiting scroll turns and the winding start point of the outer involute curve exceeds the winding start point that is near the seal-off position of the inner involute, the outer involute is positioned outside the extended portion of the inner involute. A gap between the winding start point of the curve and the inner arc of the inner involute is larger than that of the prior art in which no inner arc is provided, and the above-described effects can be obtained. However, in the above-described technique of Patent Document 1, in order to sufficiently secure a gas passage area after the start of discharge and sufficiently prevent overcompression, the thickness of the front end portion on the center side of the wrap is set to the start of winding of the inner involute. Since it is necessary to make it considerably smaller than the thickness of the lap before this point, when considering durability, the strength of the center side tip is insufficient and sliding with the other side scroll or The risk of damage due to the force of compressed gas or the like increases.

  Further, in order to increase the compression ratio without increasing the body diameter, the winding start point of the outer involute of the wrap (corresponding to the winding start point Q1 in FIG. 10) is brought closer to the center side as in the prior art shown in FIG. It is necessary to move the winding start point of the involute to the center side. However, if this is done, the central chamber becomes narrower, making it difficult to secure a communication path between each compression chamber and the central chamber, and in order to overcome this, an inner arc connected discontinuously to the winding start point of the involute is further increased. If it is located outside, the thickness of the tip on the center side of the wrap is further reduced, and the risk of damage to this tip is further increased.

  The present invention solves each of these problems by forming a concave arc surface slidably in contact with the tip of the other lap that is swiveled against the inner circumferential surface of the lap. Objective.

  To this end, the scroll compressor according to claim 1 of the present invention includes a fixed scroll in which a spiral fixed side wrap is erected on the inner surface of the fixed side end plate, and a spiral movable side wrap on the inner surface of the movable side end plate. The movable scroll that is erected is combined so that one outer peripheral surface of both wraps is slidably in contact with the other inner peripheral surface, so that the movable scroll can turn relative to the fixed scroll between the two wraps. As the volume gradually decreases, at least one pair of compression chambers moving toward the central chamber formed at the center of both wraps is formed, and the outer peripheral surface and the inner peripheral surface of each wrap at least partially vortex In a scroll compressor that is formed by a surface and an inner spiral surface and has a central arc tip connected through a small circular arc surface, The peripheral surface includes a first portion formed of a part of the inner spiral surface that is slidably contacted with the outer peripheral surface of the other lap, and a central tip of the other wrap that is continuously connected to the first portion. A concave arcuate surface-like second portion that is slidably abutted on the small arc surface of the second portion, and a second portion that is located radially outward from the extended surface of the arc surface of the second portion and is connected to the small arc surface 4 parts and a third part connected discontinuously to the second part and connected to the fourth part immediately away from the extended surface of the arc surface of the second part. It is.

  In the scroll compressor described in the previous section, the outer peripheral surface of each wrap formed by the outer spiral surface is continuously connected to the small arc surface at the spiral start point, and the first portion of the inner peripheral surface of each wrap is the same. The outer peripheral surface of the other wrap that is swung with respect to the lap is formed on the side opposite to the center from the vicinity of the first seal-off position where the outer peripheral surface of the wrap starts to separate from the inner spiral surface of the wrap. A circular arc surface centering on the central axis of rotation at the center of the small circular arc surface at the tip on the central side of the wrap is formed by continuously connecting from the vicinity of the first seal-off position of the first portion to the central side, and the fourth portion is Preferably, the third spiral portion is a concave arc surface formed by a part of the inner spiral surface and continuously connected to the fourth portion.

  In the scroll compressor described in the preceding paragraph, the fourth portion is formed by a part of the inner spiral surface, but is located radially inward of the inner spiral surface on the small arc surface side and on the third portion side. It is preferable to use a concave arc surface located radially outward from the inner spiral surface.

  In the scroll compressor described in the preceding paragraphs, a shallow storage recess is formed on the inner surface of the end plate of each scroll on the periphery of the discharge hole formed in the center of the end plate and on the portion excluding each wrap, and the thickness is It is preferable that a wear prevention plate having the same depth as or slightly thicker than the depth of the storage recess is provided in the storage recess.

  As described above, according to the present invention, the inner peripheral surface of one lap of both scrolls that are swung relative to each other is composed of a part of the inner spiral surface that is slidably contacted with the outer peripheral surface of the other wrap. A first portion, a second portion having a concave arc surface shape that is continuously connected to the first portion and is slidably brought into contact with a small circular arc surface at the tip on the center side of the other lap, and the second portion A fourth portion that is located radially outside the extended surface of the circular arc surface and is connected to the small circular arc surface, and is connected to the second portion discontinuously and quickly from the extended surface of the circular arc surface of the second portion Since the third portion is connected to the fourth portion so as to be separated outward, the small circular arc surface at the tip on the center side of the other wrap is separated from the inner spiral surface of one wrap of both scrolls that are orbited to each other. However, this small circular arc surface is slidably contacted with the concave circular arc second portion of one lap. , Small circular arc surface compression chamber and the central chamber until after the connection portion between the second portion and the third portion is not communicated, the small arc face is communicating is started from after this connecting portion. That is, the position at which the small circular arc surface of the other wrap is separated from the inner peripheral surface of one wrap approaches the center end of both wraps, so that the compression ratio is increased, and the third portion is discontinuously connected to the second portion. The distance from the extended surface of the arcuate surface is quickly released outward, whereby the communication area between the compression chamber and the central chamber increases rapidly, so that power loss due to overcompression can be reduced. In addition, it is not necessary to change the winding start point of the outer spiral surface of the outer peripheral surface of the wrap from the conventional one, and therefore the central chamber is not narrowed. There is no possibility that the strength of the tip portion is lowered.

  The outer peripheral surface of each lap formed by the outer spiral surface is continuously connected to the small circular arc surface at the winding start point of the spiral, and the first portion of the inner peripheral surface of each wrap is the other lap that is swiveled with respect to the same wrap Is formed on the side opposite to the center from the vicinity of the first seal-off position where the outer peripheral surface begins to move away from the inner spiral surface of the wrap at the winding start point, and the second portion of the inner peripheral surface is a small circular arc surface at the tip on the center side of the other wrap A circular arc surface centering around the central axis of the center of the center is formed by continuously connecting from the vicinity of the first seal-off position of the first portion to the center side, and the fourth portion is formed by a part of the inner spiral surface. According to the invention of claim 2, the third portion is a concave arc surface continuously connected to the fourth portion, and the third portion and the fourth portion of the inner peripheral surface of each lap are continuously connected. A smooth concave arc surface is formed as a whole, and the inner peripheral surface of one wrap Since the gas flowing into the central chamber is smoothly guided from the communication path formed between the portion and the small circular arc surface of the central tip of the other lap, in addition to all the effects of the invention of the preceding paragraph, the vortex flow of the gas Energy loss due to can be reduced.

  Instead of being formed by a part of the inner spiral surface, the fourth portion is located radially inward of the inner spiral surface on the small arc surface side and radially outward of the inner spiral surface on the third portion side. According to the invention of claim 3, which is a concave arc surface positioned, the compression immediately after the small circular arc surface at the tip of the other wrap passes the connecting portion between the second portion and the third portion of one inner peripheral surface. Since the communication path between the chamber and the central chamber increases in area and increasing speed than in the previous two items, power loss due to overcompression can be further reduced, and the thickness of the tip of the wrap increases. Therefore, the strength of the tip can be further increased.

  On the inner surface of the end plate of each scroll, a shallow storage recess is formed in the peripheral portion of the discharge hole formed in the center of the end plate and the portion excluding each wrap, and the thickness is the same as or slightly thicker than the depth of this storage recess According to the invention of claim 4 in which the wear prevention plate is provided in the storage recess, the peripheral portion of the discharge hole on the inner surface of the end plate of one scroll where the wear prevention plate is not provided and the movable side wrap of the other scroll. The gap between the top surfaces can be reduced. This gap allows the central chamber and the compression chamber to communicate with each other before the small circular arc surface of one of the wraps reaches the connecting portion between the other second portion and the third portion, and the gas in the central chamber still reaches the predetermined output pressure. However, according to the fourth aspect of the present invention, the power loss of the scroll compressor due to such backflow can be reduced by reducing the gap.

  First, a first embodiment of a scroll compressor according to the present invention will be described with reference to FIGS. As shown mainly in FIGS. 2 and 3, the scroll compressor according to this embodiment includes a fixed scroll 10 including a fixed side end plate 11 and a spiral fixed side wrap 12 standing on an inner surface 11a thereof, and a movable side end plate 21. And the movable scroll 20 which consists of the spiral movable side wrap 22 standingly arranged in the inner surface 21a is comprised. The movable scroll 20 has an outer peripheral portion of the inner surface 21a of the movable side end plate 21 that is airtightly and slidably brought into contact with an upper end surface of a side peripheral wall (not shown) that stands on the entire outer periphery of the fixed end end plate 11. 10 is assembled so as to turn without rotating. In both the scrolls 10 and 20, the inner peripheral surface 12b of the fixed wrap 12 and the outer peripheral surface 22a of the movable wrap 22 are slidably contacted with each other at a plurality of locations, and a plurality of first compression chambers S1 are interposed therebetween. And the outer peripheral surface 12a of the fixed side wrap 12 and the inner peripheral surface 22b of the movable side wrap 22 are slidably brought into contact with each other at a plurality of locations to form a plurality of second compression chambers S2 therebetween. Are combined. Both the compression chambers S1 and S2 move to the center side while the volume gradually decreases as the movable scroll 20 turns with respect to the fixed scroll 10, and compress the gas trapped inside.

  A central chamber S3 is formed between the inner peripheral surfaces 12b and 22b at the center of both wraps 12 and 22 between the two end plates 11 and 21, and the fixed side end plate 11 in contact with the central chamber S3 has an inner surface. A circular discharge hole 15 having a circular counterbore 15 a on the 11 a side is formed so as to penetrate in the direction of the orbiting axis of the movable scroll 20. A reed valve 17 is provided on the outlet side of the discharge hole 15 to allow outflow of gas but prevent inflow. Further, only a spot facing portion 25a similar to the spot facing portion 15a is formed on the inner surface 21a of the movable side end plate 21 in contact with the central chamber S3.

  Next, the shape of each wrap 12, 22 will be described with reference to FIG. In the following, the shape of the fixed side wrap 12 will be described, but in the case of a symmetrical scroll, the shapes of both wraps 12 and 22 are the same. The fixed side wrap 12 is composed of an outer peripheral surface 12a, an inner peripheral surface 12b, and a small circular arc surface 12c that connects the central ends of both 12a and 12b. The outer peripheral surface 12a and the inner peripheral surface 12b are basically formed. It consists of an outer involute curved surface (outer spiral surface) H1 and an inner involute curved surface (inner spiral surface) H2 that share a basic circle H. The outer involute curved surface H1 of the outer peripheral surface 12a starts from the winding start point P1, and the two-dot chain line indicates an extended portion reaching the basic circle H of the outer involute curved surface H1 omitted. The outer peripheral surface 12a is continuously (smoothly) connected to the small circular arc surface 12c at the winding start point P1.

  The inner peripheral surface 12b of the fixed side wrap 12 includes a first portion 12b1, a second portion 12b2, a third portion 12b3, a fourth portion 12b4, and a fifth portion 12b5 that are continuous from the outside toward the center side. . The first portion 12b1 of the inner peripheral surface 12b of the fixed side wrap 12 is a part of the inner involute curved surface H2, and the outer peripheral surface 22a of the movable side wrap 22 swung in the operating direction with respect to the fixed side wrap 12 is the starting point of winding thereof. It is formed on the side opposite to the center from the first seal-off position P5 that starts to move away from the inner involute curved surface H2 at P1. The second portion 12b2 of the inner peripheral surface 12b is an arc surface 14 having a radius r1 centered on the central axis O1 of the turning circle 13 of the center P4 of the small arc surface 22c at the center-side tip of the movable side wrap 22. It is formed by connecting continuously from the first seal-off position P5 of 12b1 to the center side and reaches the second seal-off position P6. The radius r1 of the second portion 12b2 is the sum of the radius of the turning circle 13 at the center P4 of the small arc surface 22c and the radius of the small arc surface 22c. Since the configuration is as described above, the small circular arc surface 22c at the tip of the movable side wrap 22 swung with respect to the fixed side wrap 12 slides with the second portion 12b2 even after exceeding the first seal-off position P5. The contact is possible.

  The fourth portion 12b4 is formed by a part of the inner involute curved surface H2 that is an extension of the first portion 12b1, and is thus spaced outward from the extension surface of the arcuate surface 14 of the second portion 12b2. The third portion 12b3 is provided with a large angle at the second seal-off position P6 and is discontinuously connected to the second portion 12b2. The third portion 12b3 is quickly separated outward from the extended surface of the arc surface 14 of the second portion 12b2. It is a concave arc surface continuously connected to the four portions 12b4. The fifth portion 12b5 is a short plane continuously connected to the fourth portion 12b4 and the small arc surface 12c. The fourth portion 12b4 is not limited to a concave arc surface, and may be an appropriate concave arc surface. The fifth portion 12b5 is not limited to a flat surface, and may be a loose concave arc surface. Alternatively, the fifth portion 12b5 may be omitted and the fourth portion 12b4 may be directly connected to the small arc surface 12c. In addition, you may provide some roundness in the 2nd seal-off position P6 which is a connection part of 2nd part 12b2 and 3rd part 12b3.

  A counterbore 15a of the discharge hole 15 is formed on the inner surface 11a of the fixed side end plate 11 in contact with the central chamber S3, is circular when viewed from the turning axis direction of the movable scroll 20, and surrounds the discharge hole 15 and of the fixed side end plate 11. It is formed to be eccentric toward the first seal-off position P5 of the inner involute curved surface H2 of the fixed side wrap 12, and the depth is constant. The counterbore portion 15a has a winding start point P1 of the outer peripheral surface 22a of the wrap 22 located near the first seal-off position P5 of the inner peripheral surface 12b of the wrap 12, as indicated by a two-dot chain line 22A in FIG. In this state, it is not communicated with the compression chamber S1, but as shown by a two-dot chain line 22B, if the small circular arc surface 22c exceeds the second seal-off position P6, it is communicated with the compression chamber S1, and through this counterbore portion 15a. Also, the compression chamber S1 communicates with the central chamber S3. The spot facing portion 25a formed on the movable side end plate 21 has the same positional relationship as the spot facing portion 15a with respect to the movable side wrap 22 except that there are no discharge holes.

  In the first embodiment configured as described above, if the movable scroll 20 turns without rotating with respect to the fixed scroll 10, the center P4 of the small circular arc surface 22c of the movable side wrap 22 is as shown in FIG. It turns along the turning circle 13 centering on the central axis O1, and both compression chambers S1, S2 move to the center side while the volume gradually decreases along with this, and the gas confined in the inside is compressed. . The first seal-off position of the inner involute curved surface H2 of the fixed-side wrap 12 whose movable side wrap 22 has passed the position of the two-dot chain line 22A and whose winding start point P1 corresponds to the seal-off position Q5 of the prior art shown in FIG. Even after exceeding P5, the small circular arc surface 22c of the movable wrap 22 is slidably contacted with the second portion 12b2 of the inner peripheral surface 12b of the fixed wrap 12, so that the gas in the compression chamber S1 is Compressed. After the small arc surface 22c of the movable side wrap 22 reaches the second seal-off position P6 of the inner peripheral surface 12b of the fixed side wrap 12, as shown by the two-dot chain line 22C, the small arc surface of the movable side wrap 22 The gas 22c is separated from the inner peripheral surface 12b of the fixed side wrap 12, and the gas compressed in the compression chamber S1 through the communication path formed between the inner peripheral surface 12b and the small circular arc surface 22c is central chamber. It is sent in S3.

  Similarly, the gas in the compression chamber S <b> 2 is also compressed after the winding start point P <b> 1 of the fixed side wrap 12 exceeds the first seal-off position P <b> 5 of the inner involute curved surface H <b> 2 of the movable side wrap 22. After the small arc surface 12c moves along the second portion 22b2 of the movable wrap 22 and reaches the second seal-off position P6, the inner peripheral surface 22b of the movable wrap 22 and the small arc surface of the fixed wrap 12 It is fed into the central chamber S3 through a communication passage formed between the central chamber S3 and the central chamber S3. 8 is formed between the inner peripheral surfaces 12b and 22b and the small circular arc surfaces 22c and 12c with respect to the turning angle of the movable wrap 22, and communicates with the compression chambers S1 and S2 and the central chamber S3. This shows the change characteristics of the communication area. As shown in FIG. 8, the change characteristic c of the communication area of the prior art shown in FIG. 10 starts from the seal-off position Q5 and gradually increases, whereas the communication area of the first embodiment gradually increases. In the change characteristic a, communication is started from the second seal-off position P6 delayed from the seal-off position Q5 (= first seal-off position P5), but the communication area increases rapidly, and the increase in the communication area approaches saturation. In the vicinity, the change characteristic c of the communication area of the prior art is caught up. The change characteristic a of the communication area of the first embodiment rapidly increases and catches up with the change characteristic c of the prior art. The fourth part 12b4 of the inner peripheral surface 12b is an inner involute that is an extension of the first part 12b1. Formed by a part of the curved surface H2, the third portion 12b3 is discontinuously connected to the second portion 12b2 at a large angle at the second seal-off position P6, and promptly from the extended surface of the arc surface 14 of the second portion 12b2. This is because they are away outward.

  As described above, according to the first embodiment, the change characteristic of the communication area formed between the inner peripheral surfaces 12b, 22b and the small circular arc surfaces 22c, 12c and communicating the compression chambers S1, S2 and the central chamber S3. a is compared with the change characteristic c of the communication area of the prior art shown in FIG. 10, the communication start position is the front end on the center side of both wraps 12 and 22 by the angular difference between the first seal-off position P5 and the second seal-off position P6. Since the compression ratio is increased and the communication area between the compression chambers S1, S2 and the central chamber S3 increases rapidly, the power loss due to overcompression can be reduced. Further, it is not necessary to change the winding start point P1 of the outer involute curved surface H1 of the outer peripheral surface 12a of the wraps 12 and 22, so that the central chamber S3 is not narrowed. There is no need to reduce the thickness, and there is no possibility that the strength of the tip portion will decrease. Furthermore, since the compression ratio can be changed only by changing the lengths of the second portions 12b2 and 22b2, such a change is easy. Furthermore, in the first embodiment, the third portion 12b3 and the fourth portion 12b4 of the inner peripheral surface 12b of each wrap 12, 22 are continuously connected to form a smooth concave arc surface as a whole. It flows into the central chamber S3 from the compression chambers S1 and S2 through a communication path formed by the surface between the third portion 12b3 of the inner peripheral surface 12b of the one wrap 12 and the small circular arc surface 22c of the other wrap 22. Since gas is smoothly guided, energy loss due to vortex flow can be reduced.

  In the first embodiment, the counterbore portions 15a and 25a are provided, so that the compression chambers S1 and S2 are formed by communication paths formed between the inner peripheral surfaces 12b and 22b and the small circular arc surfaces 22c and 12c. The communication between the compression chambers S1, S2 and the central chamber S3 by the counterbore portions 15a, 25a is also started almost simultaneously with the start of communication between the central chamber S3 and the central chamber S3.

  Next, a second embodiment of the scroll compressor according to the present invention will be described with reference to FIGS. In the second embodiment, the wear for preventing the wear between the inner surfaces 11a and 21a of the end plates 11 and 21 of the scrolls 10 and 20 and the top surfaces 12d and 22d of the wraps 12 and 22 that are in contact with the inner surfaces 11a and 21a. The first embodiment is that the prevention plates 18 and 28 are provided, the shapes of the fourth portions 12b4 and 22b4 of the inner peripheral surfaces 12b and 22b of the wraps 12 and 22 are changed, and the shapes of the spot facing portions 15a and 25a are changed. Since only the configuration is different and other configurations are the same, this difference will be mainly described.

  As shown in FIGS. 5 to 7, in the second embodiment, a circular discharge hole 15 having a counterbore portion 15 b on the inner surface 11 a is formed on the fixed side end plate 11 in contact with the central chamber P <b> 3. A reed valve 17 is provided on the outlet side of the discharge hole 15. The counterbore portion 15b is oval when viewed from the direction of the orbiting axis of the movable scroll 20, and its both sides are in contact with the outer periphery of the discharge hole 15, and the first seal-off position P5 of the inner involute curved surface H2 of the fixed side wrap 12 (FIG. 4). The arc of the tip extends in parallel to the reference) direction, and is located on the inner side of the first seal-off position P5. On the inner surface 21a of the movable side end plate 21, only a spot facing 25b similar to the spot facing 15b is formed.

  On the inner surface 11 a of the fixed side end plate 11, a shallow storage recess 11 b is formed in a portion excluding the peripheral portion of the spot facing portion 15 b that is a part of the discharge hole 15 and the fixed side wrap 12, and the inner surface 21 a of the movable side end plate 21 is formed. A shallow storage recess 21b is formed in a portion excluding the peripheral portion of the spot facing portion 25b and the movable side wrap 22. In each of the storage recesses 11b and 21b, spiral wear prevention plates 18 and 28 made of a thin plate (for example, an iron plate having a thickness of 0.3 mm) that is the same as or slightly thicker than the depth are provided. It is provided in close contact with the bottom surface. The tip 18a on the center side of the wear preventing plates 18 and 28 (the wear preventing plate 28 side is not shown) cannot be sharpened to prevent curling, and must have an arc shape with a considerably large radius. The inner surfaces 11a and 21a of the fixed side end plates 11 and 21 in the vicinity are not covered with the wear preventing plates 18 and 28 over a considerable range. Seals 19 and 29 are provided on the top surfaces 12d and 22d of the wraps 12 and 22 so as to be in contact with the wear preventing plates 18 and 28, respectively.

  As shown in FIG. 4, the fourth portion 12b4 of the inner peripheral surface 12b of the fixed side wrap 12 is approximately the same as the radius r1 of the second portion 12b2 having the central axis O2 near the central axis O1 of the second portion 12b2. It is a part of a concave arc surface K having a radius r2, and the fourth portion 12b4 is located radially inward from the inner spiral surface H2 on the small arc surface 12c side and is closer to the inner spiral surface H2 on the third portion 12b3 side. Located on the radially outer side, one end of the concave arc surface K reaches the first seal-off position P5. Similar to the first embodiment, the third portion 12b3 is provided with a large angle at the second seal-off position P6 and is discontinuously connected to the second portion 12b2. From the extended surface of the arcuate surface 14 of the second portion 12b2, The first portion 12b4 is continuously connected to the fourth portion 12b4 with a rapid outward separation. In the third portion 12b3 of the second embodiment, as described above, the fourth portion 12b4 is located radially outside the inner spiral surface H2 on the third portion 12b3 side. The 4 portion 12b4 side is more outwardly spaced from the extended surface of the second portion 12b2 than the fourth portion 12b4 of the first embodiment, and is positioned radially outward from the inner involute curved surface H2. Since it is configured in this manner, immediately after the small circular arc surface 22c of the distal end portion of the movable side wrap 22 passes the connecting portion between the second portion 12b2 and the third portion 12b3 of the inner peripheral surface 12b of the fixed side wrap 12. The communication path between the compression chambers S1 and S2 and the central chamber S3 has a larger area and increase speed than in the first embodiment. Further, the fourth portion 12b4 is located radially inward of the inner spiral surface H2 on the small circular arc surface 12c side, whereby the thickness I of the distal end portion of the fixed side wrap 12 is larger than that in the first embodiment. . The fourth portion 12b4 is a concave arc surface that is located radially inward of the inner spiral surface H2 on the small arc surface 12c side and radially outward of the inner spiral surface H2 on the third portion 12b3 side. It is not necessary to be a part of the concave arc surface passing through the first seal-off position P5.

  In the second embodiment configured as described above, similarly to the first embodiment, when the movable scroll 20 turns with respect to the fixed scroll 10, both the compression chambers S1 and S2 move toward the center while the volume gradually decreases. The gas trapped inside is compressed, and the small circular arc surface 12c (22c) of one wrap 12 (22) is in the second seal-off position of the inner peripheral surface 22b (12b) of the other wrap 22 (12). If P6 is exceeded, the small circular arc surface 12c (22c) of one wrap 12 (22) is separated from the inner peripheral surface 22b (12b) of the other wrap 22 (12) and is small from this inner peripheral surface 22b (12b). The gas compressed in the compression chambers S1 and S2 through the communication path formed between the arc surface 12c (22c) is sent into the central chamber S3.

  In the second embodiment, as described above, the inner peripheral surface 12b of the fixed side wrap 12 is an extended surface of the second portion 12b2 on the fourth portion 12b4 side of the third portion 12b3 rather than the fourth portion 12b4 of the first embodiment. This is the same for the movable side wrap 22 as it is located outwardly away from the inner involute curved surface H2 and radially outward. Therefore, the small circular arc surface 12c (22c) at the tip of one wrap 12 (22) is the second portion 22b2 (12b2) and the third portion 22b3 (12b3) of the inner peripheral surface 22b (12b) of the other wrap 22 (12). The area and the increasing speed of the communication path between the compression chambers S1, S2 and the central chamber S3 immediately after passing through the connecting portion with respect to the above) are larger than those in the first embodiment as shown by a two-dot chain line b in FIG. Therefore, the power loss due to overcompression can be further reduced. Further, the fourth portion 12b4 is located radially inward of the inner spiral surface H2 on the small circular arc surface 12c side, thereby increasing the thickness I of the distal end portion of the fixed side wrap 12, so that the strength of the distal end portion is increased. It can be further enhanced.

  In the second embodiment, wear prevention plates 18 and 28 for preventing wear of the inner surfaces 11a and 21a are provided in the shallow storage recesses 11b and 21b formed on the inner surfaces 11a and 21a of the end plates 11 and 21, respectively. In such a scroll compressor provided with the wear prevention plate 18, the wear prevention plates 18 and 28 are usually brought into close contact with the inner surfaces 11c of the end plates 11 and 21 (the movable end plate 21 side is not shown). A step corresponding to the thickness of the wear preventing plates 18 and 28 is formed between the surfaces of the wear preventing plates 18 and 28 and the inner surfaces 11c of the end plates 11 and 21. In such a case, as shown in FIG. 9 which is an enlarged cross-sectional view corresponding to the portion along line 7-7 in FIG. 5, the inner surface 11c of the end plate 11 near the outer side of the tip 18a of the wear preventing plate 18 is provided. Is not covered by the wear preventing plate 18, a gap e 'corresponding to the thickness of the wear preventing plate 18 is formed between the inner surface 11c and the top surface 22d of the movable side wrap 22 facing the inner surface 11c. Before the small circular arc surface 22c of the movable wrap 22 reaches the second seal-off position P6 of the fixed wrap 12, as shown in FIG. 9, the central chamber S3 and the compression chamber S1 are communicated with each other through this gap e ′. The gas in the central chamber S3 is backflowed into the compression chamber S1 that has not yet reached the predetermined output pressure, and is similarly generated by a similar gap generated between the inner surface of the movable side end plate 21 and the top surface 12d of the fixed side wrap 12. The gas in the central chamber S3 is also backflowed into the compression chamber S2. Since the backflowed gas is recompressed in the compression chambers S1 and S2, there is a problem that power loss occurs. However, in the second embodiment described above, on the inner surfaces 11a and 21a of the end plates 11 and 21, shallow storage recesses 11b and 21b are formed in the peripheral portions of the spot facing portions 15b and 25b and the portions excluding the wraps 12 and 22, In each storage recess 11b, 21b, thin wear prevention plates 18, 28 that are the same as or slightly thicker than the depth are provided so as to be in close contact with the bottom surface of each storage recess 11b, 21b. As shown in FIG. 7 which is a 7-7 cross-sectional view, even if the inner surface 11 c of the end plate 11, 21 is not covered by the antiwear plate 18 in the vicinity of the outer end 18 a of the antiwear plate 18, 28. The gap e generated between the inner surface 11c of 11 and 21 and the top surfaces 12d and 22d of the wraps 12 and 22 opposite to the inner surface 11c is smaller than the aforementioned gap e 'by the depth of the storage recesses 11b and 21b. That. As a result, the amount of gas flowing back from the central chamber S3 to the compression chambers S1, S2 through the gap e is reduced, so that the power loss of the scroll compressor can be reduced.

  In the case where the wear prevention plates 18 and 28 are in direct contact with the inner surfaces of the end plates 11 and 21, the compressed gas in the central chamber S3 is provided on the back side of the tip of the wear prevention plates 18 and 28 or the central chamber is stopped. The liquid accumulated in S3 may enter and lift the tip, and the lifted tip is repeatedly pressed against the inner surfaces of the end plates 11 and 21 by the top surfaces 12d and 22d of the wraps 12 and 22, and is damaged due to fatigue. However, if the wear prevention plates 18 and 28 are provided in the shallow storage recesses 11b and 21b formed on the inner surfaces 11a and 21a of the end plates 11 and 21, the tips of the wear prevention plates 18 and 28 are provided. Since the risk of the compressed gas in the central chamber S3 or the liquid accumulated in the central chamber S3 at the time of stoppage is reduced on the back side of the section, damage due to fatigue as described above is caused. Ruosore is reduced.

  In each of the above-described embodiments, the description has been given of the case of the symmetrical scroll in which the pair of wraps 12 and 22 are substantially the same shape and provided with a phase difference of 180 degrees, but the present invention is not limited to this. The present invention can also be applied to an asymmetric scroll in which the length of each wrap 12, 22 or the winding start position and winding end position is changed.

It is explanatory drawing of the shape of the center part of the scroll of 1st Embodiment of the scroll compressor by this invention. It is front sectional drawing of the center part of 1st Embodiment shown in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. It is explanatory drawing of the shape of the center part of the scroll of 2nd Embodiment of the scroll compressor by this invention. It is front sectional drawing of the center part of 2nd Embodiment shown in FIG. FIG. 6 is a cross-sectional view taken along 6-6 in FIG. 5. FIG. 7 is an enlarged cross-sectional view taken along line 7-7 in FIG. It is a figure which shows the change characteristic of the communication area between a compression chamber and a center chamber with respect to the turning angle of a movable scroll. It is a figure equivalent to FIG. 7 in an example of a prior art. It is explanatory drawing of an example of the scroll compressor by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fixed scroll, 11 ... Fixed side end plate, 11a ... Inner surface, 11b ... Storage recessed part, 12 ... Fixed side wrap, 12a ... Outer peripheral surface, 12b ... Inner peripheral surface, 12b1 ... First part, 12b2 ... Second part, 12b3 ... 3rd part, 12b4 ... 4th part, 12c ... Small arc surface, 14 ... Arc surface, 15 ... Discharge hole, 18 ... Wear prevention plate, 20 ... Movable scroll, 21 ... Movable side end plate, 21a ... Inner surface, 21b ... Storage recess, 22 ... movable side wrap, 22a ... outer peripheral surface, 22b ... inner peripheral surface, 22c ... small arc surface, 28 ... wear prevention plate, H1 ... outer spiral surface (outer involute curved surface), H2 ... inner spiral surface (inner Involute curved surface), O1... Central axis, P1 .. winding start point P1, P4... Center, P5... First seal off position, S1, S2.

Claims (4)

A fixed scroll in which a spiral fixed side wrap is erected on the inner surface of the fixed side end plate, and a movable scroll in which a spiral movable side wrap is erected on the inner surface of the movable side end plate, and one outer peripheral surface of both wraps is the other The two wraps are combined so as to be slidable so as to slidably contact with the inner peripheral surface of each of the wraps, and the volume gradually decreases with the turning of the movable scroll with respect to the fixed scroll. Forming at least one pair of compression chambers that move to the central chamber side, the outer peripheral surface and the inner peripheral surface of each lap being at least partly formed by the outer spiral surface and the inner spiral surface and the central side thereof In a scroll compressor in which leading ends are connected via a small circular arc surface, the inner peripheral surface of one of the two wraps of the two scrolls swirled with each other is A first portion formed of a part of the inner spiral surface that is slidably contacted with a peripheral surface, and the small arc surface at the center end of the other lap continuously connected to the first portion; A concave arcuate surface-shaped second part that is slidably contacted, and a fourth part that is located radially outward from the extended surface of the arc surface of the second part and is connected to the small arc surface; A scroll compressor characterized by comprising a third part connected discontinuously to the second part and immediately away from an extended surface of the arc surface of the second part and connected to the fourth part. . 2. The scroll compressor according to claim 1, wherein an outer peripheral surface of each of the wraps formed by the outer spiral surface is continuously connected to the small arc surface at a winding start point of the spiral, and an inner peripheral surface of each of the wraps. The first portion of the wrap is formed on the side opposite to the center from the vicinity of the first seal-off position where the outer peripheral surface of the other wrap that is swung with respect to the wrap begins to separate from the inner spiral surface of the wrap at the winding start point, The second portion of the inner peripheral surface is an arc surface centering on the center axis of the rotation of the center of the small arc surface at the center end of the other lap, and from the vicinity of the first seal-off position of the first portion to the center side The fourth portion is formed by a part of the inner spiral surface, and the third portion is a concave arc surface continuously connected to the fourth portion. Scroll compressor 3. The scroll compressor according to claim 2, wherein the fourth portion is positioned on a radially inner side of the inner spiral surface on the small arc surface side instead of being formed by a part of the inner spiral surface. The scroll compressor is characterized in that a concave arc surface positioned radially outward from the inner spiral surface is formed on the third portion side. 4. The scroll compressor according to claim 1, wherein an inner surface of the end plate of each scroll is a portion excluding a peripheral portion of a discharge hole formed in a central portion of the end plate and each lap. A scroll compressor characterized in that a shallow storage recess is formed in the storage recess and a wear prevention plate having a thickness equal to or slightly thicker than the depth of the storage recess is provided in the storage recess.

Images