Abstract
A scroll compressor is described. The scroll compressor comprises a case having a high-pressure side and a low-pressure side, a stationary scroll plate having a base plate with a first side having at least one projection, which forms a spiral wrap, and a second side having a first annular protrusion, a pilot plate for separating the high-pressure side of the case from the low-pressure side of the case and the pilot plate abutting the second side of the stationary scroll plate, wherein the pilot plate has a first side, wherein the first side faces the second side of the stationary scroll plate and wherein the first side has a second annular protrusion, and a seal, wherein the seal seals a radial gap between the first annular protrusion and the second annular protrusion.
Claims
1. A scroll compressor comprising: a case having a high-pressure side and a low-pressure side; a stationary scroll plate having a base plate with a first side having at least one projection, which forms a spiral wrap, and a second side having a first annular protrusion; a pilot plate for separating the high-pressure side of the case from the low-pressure side of the case and the pilot plate abutting the second side of the stationary scroll plate, wherein the pilot plate has a first side, wherein the first side faces the second side of the stationary scroll plate and wherein the first side has a second annular protrusion; and a seal, wherein the seal seals a radial gap between the first annular protrusion and the second annular protrusion.
2. The scroll compressor according to claim 1, wherein the seal has an annular shape with an L-shaped cross-section.
3. The scroll compressor according to claim 2, wherein the L-shaped cross-section has a first leg and a second leg extending at an angle of approximately 90 degree and wherein a step is located between the first leg and the second leg.
4. The scroll compressor according to claim 3, wherein the first leg abuts a front surface of the second annular protrusion and the second leg abuts a side of the first annular protrusion; or the first leg abuts a front surface of the first annular protrusion and the second leg abuts a side of the second annular protrusion.
5. The scroll compressor according to claim 3, wherein a taper is added to the first leg.
6. The scroll compressor according to claim 5, wherein an exterior surface of the tapered leg forms an inclined plane with an angle of approximately 5 degree with respect to the approximately 90 degree between the first leg and the second leg.
7. The scroll compressor according to claim 3, further comprising: a ring being placed at the radial gap between the first annular protrusion and the second annular protrusion and having a rectangular or triangular cross-section.
8. The scroll compressor according to claim 7, wherein the L-shaped seal comprises an annular recess opposite of the step and wherein the ring is located in the recess of the L-shaped seal.
9. The scroll compressor according to claim 1, wherein the seal is assembled on a seal plate.
10. The scroll compressor according to claim 9, wherein the seal plate is made from steel or cask iron.
11. The scroll compressor according to claim 1, wherein the seal is at least partially made from a synthetic polymer composed of polyamides, polytetrafiuoroethylene, PTFE, polyether ether ketone, PEEK, or polyimide-based plastics.
12. The scroll compressor according to claim 1, wherein the second side of the stationary scroll plate further comprises a third annular protrusion having a smaller diameter than the first annular protrusion; wherein the first side of the pilot plate further comprises a fourth annular protrusion having a smaller diameter than the second annular protrusion; and wherein the seal is a first seal and the compressor further comprises a second seal, which seals a radial gap between the third annular protrusion and the fourth annular protrusion.
13. The scroll compressor according to claim 12, wherein an intermediate pressure cavity is formed between the first side of the pilot plate and the side of the stationary scroll plate as well as the first, second, third and fourth protrusions.
14. The scroll compressor according to claim 13, further comprising an orbiting scroll plate, wherein the stationary scroll plate and the orbiting scroll plate form a means for compressing; wherein the stationary scroll plate comprises an opening, which forms an outlet of the means for compressing; wherein the pilot plate comprises a corresponding opening and wherein both openings form a channel from the means for compressing to the high-pressure side; and wherein the first seal seals the intermediate pressure cavity from the low-pressure side and wherein the second seal seals the intermediate pressure cavity from the channel between the outlet of the means for compressing and the high-pressure side.
15. The scroll compressor according to claim 12, wherein the second seal has a configuration which is similar to any of the configurations of the first seal according to claim 2.
Description
DRAWINGS
[0032] In the drawings, like reference characters generally refer to the same parts throughout the different drawings. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
[0033] In the following description, various embodiments of the invention are described with reference to the following drawings, in which:
[0034] FIG. 1 shows a cross-sectional view of an exemplary scroll compressor according to the state of the art including an enlarged section with an axial gap formed between the high-pressure side and the low-pressure side of the scroll compressor.
[0035] FIG. 2 shows a cross-sectional view of an exemplary scroll compressor according to the current invention including an enlarged section with radial gap formed between the high-pressure side and the low-pressure side of the scroll compressor.
[0036] FIG. 3a, 3b show schematic views of the arrangement of the pilot plate, the stationary scroll plate and the orbiting scroll plate in a scroll compressor according to the current invention.
[0037] FIGS. 4a to 41 show different views of an exemplary seal for sealing a radial gap according to the current invention, wherein (a) shows a perspective view of a seal, (b) shows a perspective view of a seal plate, (c) shows a cross-sectional view of an L-shaped seal, (d) shows a cross-sectional view of a seal having an L-shape and an additional step, (e) shows a cross-section of the seal of (d) with an additional indication of the annular shape of the seal and (f) shows a cross-section of the seal of (e) being preconfigured on the seal plate.
[0038] FIGS. 5a to 5e illustrate buckling of an L-shaped seal, wherein (a) shows a cross-sectional view of a seal being free to buckle either upwards or downwards, with (b) illustrating buckling downwards and (c) illustrating buckling upwards. (d) shows a cross-sectional view of a seal being restricted at the top, which limits its buckling behavior to buckling downwards, wherein buckling downwards is illustrated in (e).
[0039] FIGS. 6a to 6c show cross-sectional views of an exemplary seal with an L-shaped cross-section with an anti-buckling feature, wherein (a) shows a regular L-shaped seal, (b) a seal with a tapered portion that provides an anti-buckling feature, and (c) a seal with two tapered portions that provide an anti-buckling feature.
[0040] FIGS. 7a to 7c show cross-sectional views of an exemplary seal with an L-shaped cross-section with an annular metal ring, wherein (a), (b) and (c) show different configurations of the annular metal ring.
DETAILED DESCRIPTION
[0041] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced.
[0042] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.
[0043] FIG. 1 shows a cross-sectional view of an exemplary scroll compressor 100 according to the state of the art. The scroll compressor 100 comprises a case 110, a suction port 180, a discharge port 185, a motor 190, a crankshaft 195, a stationary scroll plate 120 and an orbiting scroll plate 130. The scroll compressor 100 has a design with a high-pressure side and a low-pressure side, which are separated by a boundary 140. As can be seen in the enlarged section, the stationary scroll plate 120 has a top side, which contacts a bottom side of the boundary. In other words, the stationary scroll plate 120 is fixed within the case 110 of the scroll compressor wo in a way that the stationary scroll plate 120 is arranged below the boundary 140.
[0044] Between the stationary scroll plate 120 and the boundary 140, i.e. between the top surface of the stationary scroll plate 120 and the bottom surface of the boundary 140, a gap 145 is formed. The gap 145 is along the axial direction of the z direction as defined by the case no of the scroll compressor wo and indicated in FIG. 1. In order to prevent leakage from the low-pressure side to the high-pressure side, a seal 150 is provided in the axial gap 145.
[0045] In a typical scroll compressor, the stationary scroll plate is floating with respect to the boundary, so that the stationary scroll plate cannot be fixed directly at the boundary (e.g. by welding or fastening with a fastening means) in order to keep the gap manageable. However, such axial gaps are rather large, which leads to shortened lifetimes of the seal.
[0046] FIG. 2 shows a cross-sectional view of an exemplary scroll compressor 200 according to the current invention including an enlarged section with radial gap formed between the high-pressure side and the low-pressure side of the scroll compressor. The scroll compressor 200 comprises a case 210, a suction port 280, a discharge port 285, a motor 290, a crankshaft 295, a stationary scroll plate 220 and an orbiting scroll plate 230. The scroll compressor 200 has a design with a high-pressure side and a low-pressure side. The high-pressure side and the low-pressure side are separated by a pilot plate 240. At the high-pressure side, a discharge port 285 is located for discharging compressed fluid. A transition area between the high-pressure side and the low-pressure side is provided in form of a scroll set formed by the stationary scroll plate 220 and the orbiting scroll plate 230. The transition area provides a passage from the low-pressure side through the pilot plate 240. At the low-pressure side, the scroll compressor 200 comprises the suction port 280 for receiving fluid. Further, the motor 290 and the crankshaft 295 connected to the motor 290 and the orbiting scroll plate 230 are located at the low-pressure side. A lubricant reservoir 215 is provided at the low-pressure side as well for providing lubricant to the motor 290, the crankshaft 295 and the scroll plates 220, 230.
[0047] As can be seen in the detailed enlarged section of FIG. 2, the stationary scroll plate 220 comprises a first protrusion 222 having an annular shape and the pilot plate 240 comprises a second protrusion 242 having an annular shape. The first and the second protrusions 222, 242 may be in close proximity to one another, as has been described above. This means that they barely do not contact each other, so that a small radial gap is formed between the annular protrusions 222, 242 around their circumference. The term radial refers to a direction perpendicular to the z direction defined by the case 210 of the compressor 200.
[0048] In the embodiment depicted in FIG. 2, the stationary scroll plate 220 comprises a third protrusion 224 and the pilot plate comprises a fourth protrusion 244. Said third and fourth protrusions 224, 244 also have annular shapes, however at a smaller diameter than the first and second protrusions 222, 242, meaning that the first and second protrusions 222, 242 surround the third and fourth protrusions 224, 244. The third and fourth protrusions 224, 244 may be in close proximity to one another, so that they form a radial gap along their circumference. Although it is possible that the third and fourth protrusions 224, 244 form concentric rings with the first and second protrusions 222, 242, this is not mandatory. Instead, it may also be possible that a center of the third and fourth protrusions 224, 244 is offset with respect to a center of the first and second protrusions 222, 242.
[0049] The radial gaps formed between the first and second protrusions 222, 242 and the third and fourth protrusions 224, 244, respectively, are sealed by annular seals 250 and 255, respectively.
[0050] Between the first and second protrusions 222, 242 and the third and fourth protrusions 224, 244, an intermediate pressure cavity 260 is formed by the stationary scroll plate 220 and the pilot plate 240. Said intermediate pressure cavity 260 may have a pressure higher than the low-pressure side, but smaller than the high-pressure side. Further, a bleed hole (not shown) may be provided which connects the intermediate pressure cavity 260 with a compression chamber formed between the stationary scroll plate 220 and the orbiting scroll plate 230 at least temporarily during the operation of the scroll compressor 200.
[0051] FIG. 3a shows a schematic view of the arrangement of the pilot plate, the stationary scroll plate and the orbiting scroll plate of a scroll compressor according to the current invention. A pilot plate 515, a stationary scroll plate 500 and an orbiting scroll plate 535 are illustrated.
[0052] The stationary scroll plate 500 comprises a first annular protrusion 505 and a third annular protrusion 525 on its second side and a spiral wrap 510 at its first side. In FIG. 3a, the first side of the stationary scroll plate may be referred to as bottom side and the second side of the stationary scroll plate may be referred to as top side. The orbiting scroll plate 535 comprises a spiral wrap 540. The spiral wraps 510, 540 are interleaved and form a means for compressing. In its center, the stationary scroll plate 500 comprises an opening, which forms an outlet of the means for compressing.
[0053] The pilot plate 515 is placed above the stationary scroll plate 500 and comprises a second annular protrusion 520 and a fourth annular protrusion 530 on its first side. In FIG. 3a, the first side of the pilot plate may be referred to as bottom side.
[0054] The first and second annular protrusions 505, 520 are in close proximity to one another and form a radial gap. The radial gap is sealed by a first annular seal 550. Also, the third and fourth annular protrusions 525, 530 are in close proximity to one another and form another radial gap. Said radial gap is sealed by a second annular seal 555, Between the pilot plate, the stationary scroll plate and the first, second, third, and fourth protrusions, an intermediate pressure cavity 545 is formed.
[0055] In FIG. 3b the intermediate pressure cavity 545 is highlighted as hatched area. Further, portions of the case 590 are indicated in order to illustrate the pressure areas within the compressor. The low-pressure side is located below the orbiting scroll plate and around the sides of the stationary scroll plate, as is indicated by reference numeral 580. The high-pressure side is located above the pilot plate, as is indicated by reference numeral 585.
[0056] Within the interleaved scroll plates, the means for compressing 570 is formed. The means for compressing 570 is connected to the high-pressure side 585 via a channel 575, which is formed by corresponding openings in the stationary scroll plate and the pilot plate. The intermediate pressure cavity is sealed from the low-pressure side 580 by ease of the first seal and sealed from the channel 575 between the means for compressing and the high-pressure side 585 by ease of the second seal.
[0057] FIGS. 4a to 4f show different views of an exemplary seal for sealing a radial gap according to the current invention, wherein (a) shows a perspective view of a seal, (b) shows a perspective view of a seal plate, (c) shows a cross-sectional view of an L-shaped seal, (d) shows a cross-sectional view of a seal having an L-shape and an additional step, (e) shows a cross-section of the seal of (d) with an additional indication of the annular shape of the seal and (f) shows a cross-section of the seal of (e) being preconfigured on the seal plate.
[0058] FIG. 4a shows a perspective view of an embodiment of a seal 600. In the preferred embodiment depicted in FIG. 4a, the seal has an annular shape and is configured to be seal a radial gap formed between annular protrusion. Preferably, the seal 600 is attached to a seal plate 650 depicted in FIG. 4b because this reduces the magnitude of seal shrinkage.
[0059] FIG. 4c shows a cross-sectional view of an L-shaped seal 600a. In a perspective view, the L-shaped seal 600a may look similar to seal 600 depicted in FIG. 4a. The L-shape is formed by a first leg 615a and a second leg 615a. The legs may form an angle of approximately 90 degrees between them.
[0060] FIG. 4d shows a cross-sectional view of an L-shaped seal 600b with an additional step 620. In a perspective view, the L-shaped seal 600b may look similar to seal 600 depicted in FIG. 4a, since the step may not be visible in the perspective view. The L-shape is formed by a first leg 610b and a second leg 615b. The legs may form an angle of approximately 90 degrees between them. The step 620 is located between the legs 610b, 615b at a location where the 90 degree angle is formed. The step 620 increases the stiffness of the seal and prevents the seal 600b from being drawn into the gap that is to be sealed.
[0061] FIG. 4e shows an alternative cross-section of the seal 600b. Again, the first and second legs 610b, 615b, 620 are shown. Further, the annular shape is indicated by illustrating a portion of the annular seal located outside of the plane of the cross-section, which is identified by the hatched area. FIG. 4f shows a cross-sectional view of the seal 600b attached to a seal plate 650, wherein the view is similar to the view in figure v.
[0062] FIGS. 5a to 5e illustrate buckling of a seal, wherein (a) shows a cross-sectional view of an L-shaped seal being free to buckle either upwards or downwards, with (b) illustrating buckling downwards and (c) illustrating buckling upwards. (d) shows a cross-sectional view of a seal being restricted at the top, which limits its buckling behavior to buckling downwards, wherein buckling downwards is illustrated in (e).
[0063] The seal 705a depicted in FIG. 5a is an L-shaped seal, wherein the L-shape is formed by a first leg 710a and a second leg 715a, which extend in an angle of approximately 90 degrees with respect to one another. The configuration depicted in FIG. 5a illustrates a seal, which is restricted at its outer diameter by a protrusion 700 of the stationary scroll plate.
[0064] Caused by forces created during compressor operation, like e.g. thermal deformation, the seal 705a can buckle either upwards or downwards. Typical seals may be made from synthetic polymers, for example Teflon, while the stationary scroll plate and the pilot plate may be made from cast iron. Teflon has a thermal expansion coefficient, which is five times the thermal expansion coefficient of cast iron. When the operating temperature increases, the expansion of the seal is restricted by the stationary scroll plate, which generates compressive stress inside the seal. This compressive stress may lead to buckling as is depicted in FIGS. 5b and 5c. FIG. 5b illustrates a seal 705b, which may be similar to the seal 705a of FIG. 5a but with first leg 710b and second leg 715b. The seal 705b buckles downwards. As can be seen, the first leg 710b is deformed and tends to move downwards, i.e. it buckles downwards. In contrast, FIG. 5c illustrates a seal 705c, which may be similar to the seal 705a of FIG. 5a but with first leg 710c and second leg 715c. The seal 705c buckles upwards. As can be seen, the first leg 710c is deformed and tends to move upwards, i.e. it buckles upwards.
[0065] In the configuration of the scroll compressor according to the current invention, the seal is not only restricted by the annular protrusion of the stationary scroll plate, but also by the annular protrusion of the pilot plate. This is illustrated in FIG. 5d, where a seal 705d is shown, which is restricted by the first protrusion 700 and the second protrusion 750. The seal 705d may be similar to the seal 705a of FIG. 5a but with first leg 710d and second leg 715d. The protrusion 750 of the pilot plate is shown in a way that the front surface of the protrusion contacts the first leg 710d of the seal 705d. This restriction prevents the seal from buckling upwards. Accordingly, the first leg 705d can only buckle downwards as is illustrated by the deformed leg 710e depicted in FIG. 5e.
[0066] FIGS. 6a to 6c show cross-sectional views of an exemplary seal with an L-shaped cross-section with an anti-buckling feature, wherein (a) shows a regular L-shaped seal, (b) a seal with a tapered portion that provides an anti-buckling feature, and (c) a seal with two tapered portions that provide an anti-buckling feature.
[0067] FIG. 6a shows an L-shaped seal 800a having a first leg 810a and a second leg 815a. Such a seal may be prone to buckling. This can be illustrated by the dashed line 830a, which corresponds to the middle line of the seal thickness in the first leg 810a. Here, the middle line 830a is horizontal, which means that the first leg 810a is not biased and the seal may buckle downwards or upwards when compression stress develops inside the first leg 810a of the seal 800a.
[0068] FIGS. 6b and 6c show seals 800b, 800c, which have a so-called anti-buckling feature. The anti-buckling feature reduces the chance of the seal buckling downwards by changing the symmetry of the seal. In FIG. 6b, the anti-buckling feature has the form of a taper 820. The taper 820 is added to the first leg 810b and is most effective in reducing the buckling downwards, because an asymmetry is created for the first leg 810b. This asymmetry is illustrated by the dashed line 830b, which again corresponds to the middle line of the seal thickness in the first leg 810b. From left to right, the dashed line tends upwards, thereby indicating a tendency of buckling upwards upon compression stress. However, upwards buckling is restricted by the protrusion of the pilot plate, therefore buckling is almost entirely eliminated. The asymmetry of the first leg can be enhanced by adding a taper 820, 825 to both sides of the first leg 810c of seal 800c as is illustrated by the dashed line 830c shown in FIG. 6c. Alternatively, a taper 825 could also be added only to the bottom side of the first leg 810c.
[0069] FIGS. 7a to 7c show cross-sectional views of exemplary seals with an L-shaped cross-section and a step in combination with a ring, wherein (a), (b) and (c) show different configurations of the ring. The seals 900a, 900b, 900c each comprise a first leg 910 and a second leg 905 and a step 915 for additional stiffness. In the figures, different configurations of the ring 950a, 950b, 950c are illustrated. The first two configurations rest in a recess within the seal 900a, 900b, while the third alternative is used with a seal 900c without an additional recess. The ring may float within the first annular protrusion. Thereby, the ring may reduce the maximum radial gap that the seal needs to seal, which further improves the sealing. The ring may made of a material which has a similar thermal expansion property as the stationary scroll plate. Preferably, the ring may be a metal ring. However, also non-metal materials, which have similar thermal expansion properties, are also possible.
[0070] What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims.
