The present invention relates to a scroll compressor, and particularly relates to a scroll compressor preferably applied to an on-vehicle air conditioner required to achieve downsizing.
A scroll compressor used in an on-vehicle air conditioner includes a fixed scroll and a rotational scroll. The fixed scroll and the rotational scroll are each a circular end plate with a spiral wrap integrally formed on one of surfaces thereof. The fixed scroll and the rotational scroll are placed facing each other with their wraps being meshed, and the rotational scroll orbits relative to the fixed scroll to decrease the volume of a compression pocket formed between the two wraps while moving the compression pocket radially from outward to inward, thereby performing compression of refrigerant gas.
At actuation of the scroll compressor, reaction force due to the compressed refrigerant gas is applied to the end plate of the rotational scroll and the end plate of the fixed scroll. Thus, the rotational scroll is pressed in a direction in which the rotational scroll becomes separated from the fixed scroll in an axial direction, so that a gap called chip clearance is likely to be generated between a leading end surface (tooth top) of the wrap of each scroll and the other end plate. The refrigerant gas is leaked through the chip clearance, leading to degraded efficiency of the compressor.
For example, PTLs 1 and 2 each disclose a scroll compressor in which a back-pressure chamber is formed adjacent to a back side of the end plate of the rotational scroll with (or without) a thrust plate interposed therebetween, and part of the refrigerant gas compressed in the compression pocket is extracted and supplied to the back-pressure chamber so as to press the rotational scroll toward the fixed scroll so that the leading end surface of each wrap is constantly in contact with the other end plate.
When the back-pressure chamber adjacent to the back side of the end plate of the rotational scroll is formed to press the rotational scroll as described above, a view in an axial direction of a main shaft configured to rotationally drive the rotational scroll indicates that the back-pressure chamber is shaped in a ring around the main shaft. Such a ring-shaped back-pressure chamber has a larger area (width) with a smaller inner diameter and a larger outer diameter, thereby achieving enhanced pressing force on the rotational scroll.
As illustrated in
However, the inner seal ring d and the outer seal ring e are each disposed through a seal ring groove formed on a thrust surface g of a housing f, which provides a limit on expansion of the interval W1 between the inner seal ring d and the outer seal ring e, thereby preventing effective increase in the area of the back-pressure chamber c.
The present invention is made in view of such circumstances and provide a scroll compressor in which the area of a back-pressure chamber can be increased so that pressing force on a rotational scroll due to back pressure is enhanced to reduce leakage of refrigerant gas through a chip clearance, thereby achieving improved compression efficiency.
The present invention is further intended to achieve reduction in activation torque and activation noise.
To solve the above-described problem, a scroll compressor according to the present invention employs the following solutions.
Specifically, a scroll compressor according to the present invention includes a scroll compression mechanism including a fixed scroll, a rotational scroll facing the fixed scroll to form a compression pocket for compressing refrigerant gas, a thrust plate configured to support a load of the rotational scroll in a thrust direction, and a main shaft configured to drive the rotational scroll, a back-pressure supplying mechanism configured to supply part of the refrigerant gas compressed through the scroll compression mechanism to a back side of the thrust plate as back pressure, and a housing that houses the scroll compression mechanism and the back-pressure supplying mechanism. The back-pressure supplying mechanism includes a back-pressure chamber formed on a thrust surface facing the back side of the thrust plate in the housing, a back-pressure supplying path through which the part of the compressed refrigerant gas is extracted and supplied to the back-pressure chamber, and an inner seal ring and an outer seal ring disposed radially inside and outside, respectively, of the back-pressure chamber to prevent leakage of the back pressure from the back-pressure chamber. The outer seal ring is provided to be pressed between an inner peripheral surface of the housing and an outer peripheral surface of the thrust plate.
In the scroll compressor with the above-described configuration, since the outer seal ring disposed radially outside of the back-pressure chamber is provided to be pressed between the inner peripheral surface of the housing and the outer peripheral surface of the thrust plate, a seal ring groove for the outer seal ring does not need to be formed on the thrust surface of the housing unlike the conventional technology. Thus, the back-pressure chamber can have a width increased radially outward without being affected by the seal ring groove. Accordingly, the back-pressure chamber can have an increased area so that pressing force on the rotational scroll due to the back pressure is enhanced to reduce leakage of the refrigerant gas, thereby achieving improved compression efficiency.
In the scroll compressor with the above-described configuration, the outer peripheral surface of the thrust plate may be tilted so that a ring space having a section shaped in a right triangle is formed by the inner peripheral surface of the housing, the thrust surface, and the outer peripheral surface of the thrust plate, and the outer seal ring may be pressed between three surfaces of the inner peripheral surface of the housing, the outer peripheral surface of the thrust plate, and the thrust surface.
With the above-described configuration, a triangle seal structure is formed that the outer seal ring is pressed between three surfaces of the inner peripheral surface of the housing, the outer peripheral surface of the thrust plate, and the thrust surface. Accordingly, the outer seal ring can be disposed in a radially outermost part of the thrust surface, thereby achieving increased width and area of the back-pressure chamber.
In the scroll compressor with the above-described configuration, the outer seal ring may be fitted into an outer peripheral groove formed on the outer peripheral surface of the thrust plate, and pressed between the outer peripheral groove and the inner peripheral surface of the housing.
With the above-described configuration, the outer seal ring is in contact only with the outer peripheral surface (outer peripheral groove) of the thrust plate and the inner peripheral surface of the housing, but is not in contact with the thrust surface, thereby achieving a maximized width and hence an increased area of the back-pressure chamber formed on the thrust surface.
In the scroll compressor with the above-described configuration, a chip clearance between the fixed scroll and the rotational scroll may be set to have a dimension that allows leakage of pressure from the compression pocket before the back pressure is supplied to the rotational scroll but does not allow leakage of pressure from the compression pocket after the back pressure is supplied to the rotational scroll.
With the above-described configuration, at activation of the scroll compressor, the chip clearance between the fixed scroll and the rotational scroll is large to have a large amount of leakage from the compression pocket, and thus needed activation torque is small. Then, after the activation of the scroll compressor, the pressure in the compression pocket gradually increases, and part of the pressure is supplied to the back surface of the thrust plate as the back pressure through the back-pressure supplying mechanism. This back pressure presses the rotational scroll to narrow the chip clearance, thereby reducing leakage from the compression pocket to achieve normal compression efficiency.
This prevents such a situation that, at activation, the rotational scroll receives the back pressure and abruptly moves toward and collides with the fixed scroll, thereby effectively preventing impact noise (activation noise) due to collision.
As described above, in a scroll compressor according to the present invention, the area of a back-pressure chamber can be increased so that pressing force on a rotational scroll due to back pressure is enhanced to reduce leakage of refrigerant gas through a chip clearance, thereby achieving improved compression efficiency, and reduction in activation torque and noise at activation.
Embodiments of the present invention will be described below with reference to the accompanying drawings.
The scroll compressor 1 includes a housing 2 obtained by fastening a rear housing 2b to a front housing 2a through a bolt 3. The housing 2 houses a scroll compression mechanism 5 and a back-pressure supplying mechanism 6.
As well known, the scroll compression mechanism 5 includes a fixed scroll 8 fixed to the housing 2 (2b) through, for example, a bolt 7, a rotational scroll 10 facing the fixed scroll 8 to form a compression pocket 9 for compressing refrigerant gas, a thrust plate 12 configured to support a load of the rotational scroll 10 in a thrust direction, and a main shaft 14 configured to drive the rotational scroll 10. The main shaft 14 is pivotally supported by the front housing 2a through bearings 15 and 16, and has its leading end part externally protruding, to which a drive pulley (not illustrated) is attached.
The fixed scroll 8 and the rotational scroll 10 are provided with spiral wraps 8b and 10b, respectively, integrally formed on surfaces of circular end plates 8a and 10a. Leading end parts of the wraps 8b and 10b are in contact with the end plates 8a and 10a to which the wraps 8b and 10b face so as to smoothly slide relative to the end plates 8a and 10a, thereby forming a pair of the compression pockets 9 enclosed by the end plates 8a and 10a and the wraps 8b and 10b.
A decentering pin 14a provided to the main shaft 14 is engaged with an inner periphery of a boss 10c of the rotational scroll 10 through a bush 21 and a bearing 22. When the main shaft 14 rotates, the rotational scroll 10 rotates while being prevented from spinning by a spin preventing mechanism (not illustrated). With this configuration, the volumes of the pair of the compression pockets 9 formed between the wraps 8b and 10b of the fixed scroll 8 and the rotational scroll 10 decrease as the compression pockets 9 moves radially from outward to inward. Accordingly, refrigerant gas taken in through an intake port (not illustrated) provided to a low-pressure chamber 25 in the front housing 2a is taken into and compressed in the compression pockets 9. Then, the refrigerant gas compressed at high pressure is ejected through a discharge port (not illustrated) provided to the rear housing 2b through a discharge valve 27 and a high-pressure chamber 28.
During the compression of the refrigerant gas, reaction force due to the compressed refrigerant gas is applied to the end plate 8a of the fixed scroll 8 and the end plate 10a of the rotational scroll 10, thereby pressing the rotational scroll 10 movable relative to the fixed scroll 8 in a direction (the thrust direction) in which the rotational scroll 10 becomes separated from the fixed scroll 8 in an axial direction. This thrust load of the rotational scroll 10 is supported by the thrust plate 12, and in addition, transferred to a thrust surface 30 formed in the front housing 2a and facing a back side of the thrust plate 12.
The back-pressure supplying mechanism 6 is configured to supply part of the refrigerant gas compressed through the scroll compression mechanism 5 to the back side of the thrust plate 12 as back pressure. As illustrated in
The back-pressure supplying path 32 is a path through which the part of the refrigerant gas compressed in each compression pocket 9 and ejected to the high-pressure chamber 28 is extracted and supplied to the back-pressure chamber 31. The inner seal ring 33 and the outer seal ring 34 prevent leakage of the back pressure from the back-pressure chamber 31, maintaining air-tightness. The inner seal ring 33 and the outer seal ring 34 are O-rings formed of elastic material such as rubber, and having circular sectional shapes in a non-compression state, but may have any sectional shape other than a circular shape.
Similarly to the conventional structure (refer to
The following describes actions and effects of the scroll compressor 1 configured as described above.
At activation of the scroll compressor 1, the refrigerant gas is compressed in each compression pocket 9, but the pressure of the compression is still low, so that the end plate 10a of the rotational scroll 10 is pressed toward the thrust plate 12 by the compression pressure as illustrated in
After the activation of the scroll compressor 1, upon increase of pressure in the compression pocket 9 and the high-pressure chamber 28, part of the compressed refrigerant gas in the high-pressure chamber 28 is extracted though the back-pressure supplying path 32 and supplied to the back-pressure chamber 31. Accordingly, as illustrated in
In the present embodiment, the outer seal ring 34 disposed radially outside of the back-pressure chamber 31 is provided to be pressed between the inner peripheral surface 37 of the front housing 2a and the outer peripheral surface 12a of the thrust plate 12. This configuration eliminates the need to form, on the thrust surface 30, a seal ring groove (groove for outer seal ring e illustrated in
Accordingly, an interval (width) W2 between the inner seal ring 33 and the outer seal ring 34 can be set to be larger than a conventional width (interval) W1 illustrated in
In addition, the outer peripheral surface 12a of the thrust plate 12 is tilted so that the ring space having a section shaped in an isosceles right triangle is formed by the outer peripheral surface 12a, the inner peripheral surface 37 of the front housing 2a, and the thrust surface 30, and such a triangular seal structure in which the outer seal ring 34 is pressed between these three surfaces 12a, 37, and 30 is formed. With this configuration, the outer seal ring 34 can be disposed in a radially outermost part of the thrust surface 30, which results in increase in the width W2 and the area of the back-pressure chamber 31.
In the back-pressure supplying mechanism 40, an outer peripheral surface 12b of the thrust plate 12 is a cylindrical surface parallel to the inner peripheral surface 37 of the front housing 2a. The outer seal ring 34 is fitted into an outer peripheral groove 41 formed on the outer peripheral surface 12b of the thrust plate 12 and is mounted being pressed between the outer peripheral groove 41 and the inner peripheral surface 37 of the front housing 2a. Thus, the outer seal ring 34 is not in contact with the thrust plate 12.
In the back-pressure supplying mechanism 40 having the above-described configuration, the outer seal ring 34 is in contact only with the outer peripheral surface 12b of the thrust plate 12 (outer peripheral groove 41) and the inner peripheral surface 37 of the front housing 2a, but is not in contact with the thrust surface 30. With this configuration, an interval (width) W3 between the inner seal ring 33 and an outer peripheral part (i.e., the inner peripheral surface 37) of the outer seal ring 34 is larger than the interval W2 in the first embodiment (refer to
When the back pressure is applied on the back-pressure chamber 31 to float the thrust plate 12 at activation of the scroll compressor 1, the outer seal ring 34 slides relative to the inner peripheral surface 37 of the front housing 2a, or deforms, and thus braking force due to slide resistance or deformation resistance is applied to motion of the thrust plate 12. This can prevent generation of abnormal noise (activation noise) due to collision of the rotational scroll 10 with the fixed scroll 8 caused when the thrust plate 12 abruptly floats.
In the third embodiment, as illustrated in
The dimension of the chip clearance C is set to approximately 0.6 mm to 0.8 mm to allow leakage of pressure from the compression pocket 9.
As illustrated in
The well-known chip seal may be provided to the leading end part of the wrap 8b of the fixed scroll 8 and the leading end part of the wrap 10b of the rotational scroll 10. With this configuration, the compression leakage can be more reliably prevented.
According to the present configuration, at activation of the scroll compressor 1, the chip clearance C between the fixed scroll 8 and the rotational scroll 10 is large enough to have a large amount of leakage from the compression pocket 9, and thus needed activation torque is small.
Then, after the activation of the scroll compressor 1, the pressure in the compression pocket 9 gradually increases, and part of the pressure is supplied as back pressure to a back surface (the back-pressure chamber 31) of the thrust plate 12 through the back-pressure supplying mechanisms 6 and 40 illustrated in
This prevents such a situation that, at activation, the rotational scroll 10 receives the back pressure and abruptly moves toward and collides with the fixed scroll 8, thereby effectively preventing impact noise (activation noise) due to collision.
As described above, in the scroll compressor 1 according to the present embodiment, the area of the back-pressure chamber 31 can be increased so that pressing force on the rotational scroll 10 due to the back pressure is enhanced to reduce leakage of the refrigerant gas through the chip clearance, thereby achieving improved compression efficiency, and reduction in activation torque and noise at activation.
The present invention is not limited only to the configurations in the above-described embodiments, but any change or modification may be added as appropriate without departing from the gist of the present invention, and any embodiment including such change or modification is included in the scope of rights in the present invention.
For example, the scroll compressor 1 described in the above embodiments is used in an air conditioning device of an automobile but is not limited thereto. The present invention is applicable to a scroll compressor used in an air conditioning device of a structure such as a house, a building or a warehouse.
The scroll compressor 1 in the above-described embodiments is driven by an external power such as an engine of an automobile, but the present invention is applicable to an electric scroll compressor integrally provided with an electric motor.
Number | Date | Country | Kind |
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2014-189061 | Sep 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/071299 | 7/28/2015 | WO | 00 |