Patent Grant
8475149
The present invention relates to a scroll fluid machine that can be used as a compressor or expander in a refrigerating cycle for freezing or air conditioning, and in which an orbiting scroll is disposed between a pair of fixed scrolls so as to enable orbiting motion, and particularly relates to a port construction that allows a working fluid to enter or leave a central chamber.
In a refrigerating cycle that can be used for freezing or air conditioning, if a pressurization or pressure reduction process is performed by a scroll-type fluid machine, appropriately supporting or handling gas load that acts axially on an orbiting scroll as a result of differential pressure between an inlet and an outlet, also known as “thrust load”, is important for increasing cycle efficiency and ensuring reliability.
In refrigerating cycles such as those that use carbon dioxide as a refrigerant, in particular, high-to-low differential pressure is extremely large. For this reason, supporting thrust load is difficult by conventional methods such as supporting the thrust load by a hydrodynamically lubricated surface.
In order to solve problems of this kind that relate to supporting thrust load, double-sided scroll fluid machines are commonly-known in which spirals are disposed on two surfaces of a base plate of an orbiting scroll, the two spirals of the orbiting scroll are mated with respective spirals of fixed scrolls that are disposed on two sides of the orbiting scroll such that a compression chamber and an expansion chamber are formed on both sides of the orbiting scroll, and axial thrust loads that act on the orbiting scroll in the compression/expansion process are canceled out.
In these double-sided scroll fluid machines, spirals are formed on two surfaces of a base plate of an orbiting scroll, and a main shaft that drives or supports the orbiting scroll is supported at two ends by shaft bearing portions that are disposed centrally on the two fixed scrolls so as to pass through central portions of the spirals of the orbiting scroll. Here, it is necessary for ports that are formed on bottom surfaces of winding start portions of the spirals of the fixed scrolls to be positioned outside an orbiting motion range of a boss portion of the orbiting scroll through which the main shaft passes. Thus, in order to ensure port aperture area, it is necessary for the winding start portions of the spirals of the fixed scrolls to be positioned partway along involute curves near outer circumferences of the shaft bearing portions, reducing efficiency. If attempts are made to ensure port aperture area by disposing the winding start portions of the spirals of the fixed scrolls closer to the starting points of the involute curves, the port openings interfere with the boss portion of the orbiting scroll, increasing fluctuations in the port aperture area.
To solve problems of this kind in double-sided scroll fluid machines, double-sided scroll fluid machines have been proposed in which a peripheral wall surface near a scroll center of a spiral groove of a fixed scroll is formed into a semi-circular surface, a port opening is disposed on the semi-circular surface on an inner wall side of the spiral groove, an inner peripheral end of a spiral lap of an orbiting scroll slides in contact along the peripheral wall surface near the scroll center, and a working fluid is discharged through or sucked into the port opening (see Patent Literature 1, for example).
In conventional scroll fluid machines such as that described in Patent Literature 1, because the port opening is formed on the peripheral wall surface near the scroll center of the spiral groove of the fixed scroll, interference between the port opening and the boss portion of the orbiting scroll can be avoided. Thus, the winding start portions of the spirals of the fixed scrolls can be shifted toward a starting end of the involute curve compared to when a port opening is formed on a bottom surface of the spiral groove, enabling increased efficiency.
Although not double-sided, scroll compressors that have a penetrating axis construction have been proposed in which two discharge ports are disposed on a fixed scroll, and these discharge ports are disposed symmetrically about a central axis of the fixed scroll (see Patent Literature 2, for example).
In conventional scroll compressors such as that described in Patent Literature 2, vibration and noise are reduced by making a discharging process balanced, enabling effects that can improve reliability.
In conventional scroll fluid machines such as that described in Patent Literature 1, because the port opening is formed on the peripheral wall surface near the scroll center of the spiral groove of the fixed scroll, one disadvantage has been that sufficient port aperture area cannot be ensured. In addition, since pressure loss that passes through this narrow portion is great as the inner peripheral end of the spiral lap of the orbiting scroll slides in contact along the peripheral wall surface near the scroll center, another disadvantage has been that the substantial aperture area is not uniform relative to a chamber near an inward facing surface of the spiral lap and a chamber near an outward facing surface that are positioned on opposite sides of the inner peripheral end of the spiral lap.
In conventional scroll compressors such as that described in Patent Literature 2, a diagram is shown in which the boss portion of the orbiting scroll spiral through which the shaft passes is cut away so as not to block the ports that are disposed symmetrically about the central axis, and one disadvantage has been that balancing the discharging process by a symmetrical port layout inevitably leads to increases in dead volume in exchange for avoiding problems such as interference with the boss portion described above.
Since new problems such as those described above arise when port openings are formed on peripheral wall surfaces near a scroll center of a spiral groove, and when port openings are disposed symmetrically about a central axis, the present invention aims to solve the problems described above that result from port openings being formed on a bottom surface of a spiral groove by minimizing overlap between a layout of port openings that are formed on the bottom surface of the spiral groove and an orbiting motion range of a boss portion of an orbiting scroll.
Specifically, an object of the present invention is to provide a highly efficient and highly reliable scroll fluid machine by disposing ports that allow a working fluid to enter or leave a central chamber so as to have openings on a bottom surface of a spiral groove in a vicinity of a winding start end portion of a spiral tooth, and near an inward facing surface of the spiral tooth that is separated from the winding start end portion of the spiral tooth by an involute angle of approximately 90 degrees to suppress fluctuations in port aperture area during each revolution of an orbiting scroll while ensuring port aperture area.
In order to achieve the above object, according to one aspect of the present invention, there is provided a scroll fluid machine including: a sealed vessel; a first fixed scroll that is disposed so as to partition off an upper portion space inside the sealed vessel, and in which a first spiral tooth and a first spiral groove are formed on a lower surface of a first base plate; an orbiting scroll that is configured such that an upper spiral tooth and an upper spiral groove, and a lower spiral tooth and a lower spiral groove, are formed on two surfaces of a third base plate, and that is disposed so as to face a lower surface side of the first fixed scroll such that the upper spiral tooth intermeshes with the first spiral tooth; a second fixed scroll that is configured such that a second spiral tooth and a second spiral groove are formed on an upper surface of a second base plate, that is disposed so as to face a lower surface side of the orbiting scroll such that the second spiral tooth intermeshes with the lower spiral tooth, and that partitions off a lower portion space inside the sealed vessel; and a main shaft that is disposed so as to be rotatably supported by a first shaft bearing portion of the first fixed scroll and a second shaft bearing portion of the second fixed scroll, and so as to pass through a boss portion of the orbiting scroll, and that makes the orbiting scroll perform orbital motion, wherein the orbiting scroll compresses or expands a working fluid on each of an upper surface side and a lower surface side of the orbiting scroll by performing the orbital motion relative to the first and second fixed scroll. The ports that allow the working fluid to enter or leave are disposed on the first base plate and the second base plate so as to have openings in a vicinity of a winding start end portion of each of the first spiral tooth and the second spiral tooth, and near an inward facing surface of each of the first spiral tooth and the second spiral tooth at a position that is separated from the winding start end portion of each of the first spiral tooth and the second spiral tooth by an involute angle of approximately 90 degrees.
According to the present invention ports that allow a working fluid to enter or leave are disposed so as to have openings on a first base plate and a second base plate in a vicinity of winding start end portions of a first spiral tooth and a second spiral tooth, respectively, and near inward facing surfaces of the first spiral tooth and the second spiral tooth, respectively, at positions at an involute angle of approximately 90 degrees away from the winding start end portions of the first spiral tooth and the second spiral tooth, respectively. Thus, because the ports that allow the working fluid to enter or leave are disposed at two positions near the winding start end portions of the first spiral tooth and the second spiral tooth, respectively, sufficient port aperture area can be ensured without having to shift the winding start portions of the first spiral tooth and the second spiral tooth inordinately in the involute direction of the involute curves, and without inviting increases in dead volume due to cutting away the boss portion such as when two ports are disposed at symmetrical positions. Even if a portion of the opening of one port is blocked due to interference with the boss portion of the orbiting scroll as the orbiting scroll orbits, the other port will not interfere with the boss portion, reducing fluctuations in total aperture area of the ports during each revolution of the orbiting scroll. As a result, deterioration in efficiency due to significant pressure loss arising and occurrences of intermittent expansion steps can be suppressed, enabling high efficiency and high reliability to be achieved.
In
A main shaft 78 is held rotatably at two ends by shaft bearing portions 51b and 52b that are formed centrally on the second fixed scroll 51 of the expansion mechanism 2 and the first fixed scroll 52 of the subcompression mechanism 3, respectively. A sleeve 75 is fitted coaxially over a portion of the main shaft 78 that corresponds to a shaft bearing portion 51b. A slider 74 is fitted into an orbiting shaft bearing portion 53b that is disposed centrally through the orbiting scroll 53. An eccentric shaft portion 80 that is formed on a central portion of the main shaft 78 is fitted into a shaft insertion aperture 81 that is disposed through the slider 74. A distance between an outside diameter center of the slider 74 and a central axis of the main shaft 78 can thereby fluctuate, and the slider 74 constitutes a variable radius crank mechanism that is moved in a direction in which orbiting radius is greatest by force from gas pressure that acts on the orbiting scroll 53, enabling the orbiting scroll 53 to perform orbital motion.
An expansion suction pipe 15 that sucks in refrigerant and an expansion discharge pipe 16 that discharges expanded refrigerant are installed on side surfaces of the sealed vessel 4 outside the expansion mechanism 2. Similarly, a subcompression suction pipe (not shown) that sucks in refrigerant and a subcompression discharge pipe 20 that discharges compressed refrigerant are installed on side surfaces of the sealed vessel 4 outside the subcompression mechanism 3.
In the subcompression mechanism 3, tip seals 71 that partition off a subcompression chamber 3a that is formed by the first spiral tooth 52c of the first fixed scroll 52 and the upper spiral tooth 53d of the orbiting scroll 53 are mounted to tips of the first spiral tooth 52c and the upper spiral tooth 53d of the first fixed scroll 52 and the orbiting scroll 53, respectively. An outer seal 73 that forms a seal between the orbiting scroll 53 and the first fixed scroll 52 is disposed on an outer circumference of the first spiral tooth 52c on a surface of the first fixed scroll 52 that faces the orbiting scroll 53.
In the expansion mechanism 2, on the other hand, an inner seal 72 that forms a seal between the orbiting scroll 53 and the second fixed scroll 51 is disposed on an outer circumference of the orbiting shaft bearing portion 53b on a surface of the orbiting scroll 53 that faces the second fixed scroll 51. Tip seals 71 that partition off an expansion chamber 2a that is formed by the second spiral tooth 51c of the second fixed scroll 51 and the lower spiral tooth 53c of the orbiting scroll 53 are also mounted to tips of the second spiral tooth 51c of the second fixed scroll 51 and the lower spiral tooth 53c of the orbiting scroll 53.
Autorotation of the orbiting scroll 53 is restricted by an Oldham ring 77 that is disposed near the subcompression mechanism 3. Upper and lower balancers 79a and 79b are mounted to two ends of the main shaft 78 in order to cancel out centrifugal forces that the orbiting scroll 53 generates by its orbiting motion. An oil pump 76 is mounted to a lower end of the main shaft 78, and supplies to each of the shaft bearing portions lubricating oil 9 that is stored in a bottom portion of a lower portion space of the sealed vessel 4.
An oil gallery 78a that supplies oil mainly to the shaft bearing portion 51b, an oil gallery 78b that supplies oil to the shaft bearing portion 52b and the orbiting shaft bearing portion 53b, and a gas venting aperture 78c are disposed inside the main shaft 78. A spiral groove (not shown) is disposed on an outer circumferential surface of a portion of the main shaft 78 that corresponds to the shaft bearing portion 52b, and lubricating oil 9 that has been supplied to the shaft bearing portion 52b by means of the oil gallery 78b passes through the spiral groove and overflows into the upper portion space of the sealed vessel 4. Refrigerant that is to be subcompressed is supplied from a main compressor 5 by means of the subcompression suction pipe so as to include lubricating oil, is subcompressed by the orbiting scroll 53 and the first fixed scroll 52, is then separated from the oil by being opened to the upper portion space temporarily, and is discharged through the subcompression discharge pipe 20. The lubricating oil 9 that has overflowed from the shaft bearing portion 52b, and also that has been separated and accumulated in a lower portion of the upper portion space, is returned to the lower portion space by means of an oil return aperture 31.
Next, a refrigerating cycle that uses a scroll expander 1 that is configured in this manner will be explained with reference to
In the refrigerating cycle, the subcompression mechanism 3 of the scroll expander 1 is disposed upstream from a gas cooler 11, and the expansion mechanism 2 is disposed downstream from the gas cooler 11. The expansion mechanism 2 is disposed upstream from an evaporator 12, and the subcompression mechanism 3 is disposed downstream from the main compressor 5 which is disposed downstream from the evaporator 12.
In a refrigerating cycle that is configured in this manner, when electric power is supplied to a motor 6, the main compressor 5 is driven, and refrigerant is compressed. The compressed refrigerant is conveyed into the subcompression mechanism 3 through the subcompression suction pipe, and is compressed and pressurized inside the subcompression chamber 3a that is formed by the first spiral tooth 52c of the first fixed scroll 52 and the upper spiral tooth 53d of the orbiting scroll 53. The refrigerant that has been compressed and pressurized inside the subcompression chamber 3a is discharged through the discharge valve 32, is opened to the upper portion space of the sealed vessel 4 temporarily and separated from the oil, is then discharged outside the sealed vessel 4 through the subcompression discharge pipe 20. The refrigerant that has been discharged through the subcompression discharge pipe 20 is conveyed into the gas cooler 11, and is cooled. The cooled refrigerant is conveyed through the expansion suction pipe 15 into the expansion mechanism 2, and is expanded and decompressed inside the expansion chamber 2a that is formed by the second spiral tooth 51c of the second fixed scroll 51 and the lower spiral tooth 53c of the orbiting scroll 53. The refrigerant that has been expanded and decompressed inside the expansion chamber 2a is discharged through the expansion discharge pipe 16, is conveyed into the evaporator 12 and heated, and is then conveyed into the main compressor 5.
Operation of the refrigerating cycle at this time will be explained using
The refrigerant is compressed to an intermediate pressure Pm in the main compressor 5 (a to d′). The refrigerant at intermediate pressure Pm that has been compressed by the main compressor 5 is conveyed into the subcompression chamber 3a of the subcompression mechanism 3 through the subcompression suction pipe, and is pressurized to a high pressure Ph (d′ to d). The refrigerant that has been pressurized to the high pressure Ph is conveyed into the gas cooler 11 through the subcompression discharge pipe 20, and is cooled (d to c). Next, the cooled refrigerant is conveyed into the expansion chamber 2a of the expansion mechanism 2 through the expansion suction pipe 15, and is expanded and decompressed to a low pressure Pl (c to b). Here, if the refrigerant that has been cooled by the gas cooler 11 were decompressed by a restrictor such as an expansion valve that does not recover power, it would decompress at a constant specific enthalpy from point c to point b′. A specific enthalpy difference (=b′−b) during this decompression is recovered as expansion power, and is used as compression power proportionate to a specific enthalpy difference (=d−d′) in the subcompression mechanism 3. After power required for subcompression is recovered in the expansion step, the refrigerant is discharged through the expansion discharge pipe 16, is conveyed into the evaporator 12, and is heated (b to a). The heated refrigerant is conveyed into the main compressor 5.
Here, because the main shaft 78 and the Oldham ring 77 that restrict motion and phase when the orbiting scroll 53 is performing compression work are disposed, the expansion power that has been recovered by the expansion mechanism 2 is added to the compression power of the subcompression mechanism 3, and makes up for work proportionate to sliding loss that accompanies driving the orbiting scroll 53, the main shaft 78, the Oldham ring 77, etc.
The subcompression chamber 3a of the subcompression mechanism 3 is at intermediate pressure Pm internally, and an outer circumferential side of the subcompression chamber 3a of the subcompression mechanism 3 is at low pressure Pl after expansion. Thus, the outer seal 73 that is disposed on the outer circumference of the first spiral tooth 52c on the surface of the first fixed scroll 52 that faces the orbiting scroll 53 forms a seal against internal and external differential pressure of the subcompression chamber 3a. The inner seal 72 that is disposed on the outer circumference of the orbiting shaft bearing portion 53b on the surface of the orbiting scroll 53 that faces the second fixed scroll 51 forms a seal against the differential pressure between the expansion chamber 2a and a side near the orbiting shaft bearing portion 53b.
Next, specific configurations of the subcompression mechanism 3 and the expansion mechanism 2 will be explained with reference to
In
A discharge port 40b is disposed through the first base plate 52a so as to have an opening on a bottom surface of the first spiral groove 52d in a vicinity of a winding start end portion of the first spiral tooth 52c. A discharge port 40a is disposed through the first base plate 52a so as to have an opening on a bottom surface of the first spiral groove 52d near an inward facing surface of the first spiral tooth 52c at a position that is advanced from a winding start end portion of the first spiral tooth 52c by an involute angle of approximately 90 degrees. As shown in
In
A suction port 35b is disposed through the second base plate 51a so as to have an opening on a bottom surface of the second spiral groove 51d in a vicinity of a winding start end portion of the second spiral tooth 51c. A suction port 35a is disposed through the second base plate 51a so as to have an opening on a bottom surface of the second spiral groove 51d near an inward facing surface of the second spiral tooth 51c at a position that is advanced from a winding start end portion of the second spiral tooth 51c by an involute angle of approximately 90 degrees. As shown in
Because the suction ports 35a and 35b and the discharge ports 40a and 40b are formed so as to have openings on bottom surfaces of the second spiral groove 51d and the first spiral groove 52d in this manner, the suction ports 35a and 35b and the discharge ports 40a and 40b can be formed on the second base plate 51a and the first base plate 52a so as to ensure sufficient aperture area.
Next, port obstruction due to the orbiting motion of the orbiting scroll in the subcompression mechanism 3 will be explained with reference to
The orbiting scroll 53 revolves without rotating as shown in
Thus, a discharge port 40b is formed so as to be shifted from an involute starting point of a peripheral wall surface near an outward facing surface of the first spiral tooth 52c approximately 90 degrees inward along a curved peripheral wall of a winding start end portion of the first spiral tooth 52c, and have an opening on a bottom surface of the first spiral groove 52d in close proximity to the curved peripheral wall at the winding start end portion of the first spiral tooth 52c. A discharge port 40a is formed so as to have an opening on a bottom surface of the first spiral groove 52d alongside a peripheral wall near an inward facing surface of the first spiral tooth 52c at a position that is advanced from a winding start end portion of the first spiral tooth 52c by an involute angle of approximately 90 degrees. Thus, even if a portion of the opening of the discharge port 40a is blocked due to interference with the bulbous portion 53g, interference between the discharge port 40b and the bulbous portion 53g can be avoided, enabling occurrences of significant loss due to discharge resistance to be prevented.
Because the discharge port 40a is formed so as to have a rectilinear oblong aperture shape that is parallel to a peripheral wall surface near the inward facing surface of the first spiral tooth 52c, and the discharge port 40b is formed so as to have an approximately circular aperture shape, aperture area when fully open can be increased while reducing the amount of blockage during interference with the bulbous portion 53g.
Next, port obstruction due to the orbiting motion of the orbiting scroll in the expansion mechanism 2 will be explained with reference to
The orbiting scroll 53 revolves without rotating as shown in
Thus, a suction port 35b is formed so as to be shifted from an involute starting point of a peripheral wall surface near an outward facing surface of the second spiral tooth 51c approximately 90 degrees inward along a curved peripheral wall of a winding start end portion of the second spiral tooth 51c, and have an opening on a bottom surface of the second spiral groove 51d in close proximity to the curved peripheral wall at the winding start end portion of the second spiral tooth 51c. A suction port 35a is formed so as to have an opening on a bottom surface of the second spiral groove 51d alongside a peripheral wall near an inward facing surface of the second spiral tooth 51c at a position that is advanced from a winding start end portion of the second spiral tooth 51c by an involute angle of approximately 90 degrees. Thus, even if a portion of the opening of the suction port 35a is blocked due to interference with the bulbous portion 53g, interference between the suction port 35b and the bulbous portion 53g can be avoided, preventing suction volume to the expansion mechanism 2 from being cut off or significantly reduced. As a result, situations such as intermittent expansion steps being repeated can be preempted.
Because the suction port 35a is formed so as to have a rectilinear oblong aperture shape that is parallel to a peripheral wall surface near the inward facing surface of the second spiral tooth 51c, and the suction port 35a is formed so as to have an approximately circular aperture shape, aperture area when fully open can be increased while reducing the amount of blockage during interference with the bulbous portion 53g.
Now, fluctuation in aperture area of the suction ports 35a and 35b relative to crank angle in the expansion mechanism 2 of this scroll fluid machine is represented by a solid line in
From
Moreover, effects can also be similarly achieved by making the discharge port into two ports in the discharging process in the subcompression mechanism 3.
Thus, according to the present invention ports that allow a working fluid to enter or leave are disposed so as to have openings on a first base plate and a second base plate in a vicinity of winding start end portions of a first spiral tooth and a second spiral tooth, respectively, and near inward facing surfaces of the first spiral tooth and the second spiral tooth, respectively, at positions that are separated by an involute angle of approximately 90 degrees from the winding start end portions of the first spiral tooth and the second spiral tooth, respectively. Thus, even if the opening of one port is blocked due to interference with the boss portion of the orbiting scroll, the other port is open, suppressing fluctuations in total aperture area of the ports. Thus, deterioration in efficiency due to significant pressure loss arising, and occurrences of intermittent expansion steps, etc., are eliminated, enabling a highly efficient and highly reliable scroll fluid machine to be provided.
Moreover, in the above embodiment, an expansion mechanism 2 is configured in a lower portion inside a sealed vessel 4, and a subcompression mechanism 3 is configured in an upper portion inside the sealed vessel 4, but the subcompression mechanism 3 may also be configured in a lower portion inside the sealed vessel 4, and the expansion mechanism 2 configured in an upper portion inside the sealed vessel 4.
In the above embodiment, a double-sided scroll-type compressor-integrated expander that performs expansion on one side, and that performs compression on the other side has been explained as a scroll fluid machine, but the present invention may also be applied to scroll fluid machines such as double-sided scroll-type compressors that perform compression on both sides, double-sided scroll-type expanders that perform expansion on both sides, etc.
In the above embodiment, aperture shapes of the suction port 35a and the discharge port 40a are rectilinear oblong shapes, but the aperture shapes of the suction port 35a and the discharge port 40a need only be oblong shapes that have longitudinal axes that are parallel to peripheral wall surfaces near inward facing surfaces of the second spiral tooth 51c and the first spiral tooth 52c, and, for example, may also be elliptical shapes, or oblong shapes that curve along the peripheral wall surfaces near the inward facing surfaces of the second spiral tooth 51c and the first spiral tooth 52c.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-099527 | Apr 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/050005 | 1/5/2009 | WO | 00 | 9/29/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/125608 | 10/15/2009 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5145344 | Haga et al. | Sep 1992 | A |
| Number | Date | Country |
|---|---|---|
| 59 119080 | Jul 1984 | JP |
| 62 157288 | Jul 1987 | JP |
| 63 59032 | Nov 1988 | JP |
| 3 275901 | Dec 1991 | JP |
| 4 234591 | Aug 1992 | JP |
| 11 141301 | May 1999 | JP |
| Entry |
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| International Search Report issued Mar. 31, 2009 in PCT/JP09/50005 filed in Jan. 5, 2009. |
| Number | Date | Country | |
|---|---|---|---|
| 20110027114 A1 | Feb 2011 | US |
