Scroll compressor

Abstract

The area of a back-pressure chamber is 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. A scroll compression mechanism configured to form a compression pocket between a fixed scroll and a rotational scroll 10 facing each other and including a thrust plate 12 configured to support a thrust load of the rotational scroll 10, and a back-pressure supplying mechanism 6 configured to supply part of compressed refrigerant gas to a back side of the thrust plate 12 as back pressure are provided. The back-pressure supplying mechanism 6 includes a back-pressure chamber 31 formed on a thrust surface 30 facing the back side of the thrust plate 12, a back-pressure supplying path 32 through which the compressed refrigerant gas is supplied to the back-pressure chamber 31, and an inner seal ring 33 and an outer seal ring 34 disposed radially inside and outside, respectively, of the back-pressure chamber 31. The outer seal ring 34 is provided to be pressed between an inner peripheral surface 37 of a housing 2a and an outer peripheral surface 12a of the thrust plate 12.

Claims

1. A scroll compressor comprising: 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, wherein: 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 inner seal ring is provided in a space formed radially inside of the back-pressure chamber so that the inner seal ring is pressed between the thrust plate and the thrust surface, the outer seal ring is provided in a space formed radially outside of the back-pressure chamber so that the outer seal ring is pressed between an inner peripheral surface of the housing and an outer peripheral surface of the thrust plate, and the back-pressure supplying path communicates a high pressure chamber to which the refrigerant gas is ejected from the compression pocket and an outer peripheral side surface of the back-pressure chamber.

2. The scroll compressor according to claim 1, wherein the outer seal ring is fitted into an outer peripheral groove formed on the outer peripheral surface of the thrust plate and is pressed between the outer peripheral groove and the inner peripheral surface of the housing.

3. A scroll compressor comprising: 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, wherein: 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 a 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, an outer peripheral surface of the thrust plate is tilted so that a ring space having a section shaped in a right triangle is formed radially outside of the back-pressure chamber by an inner peripheral surface of the housing, the thrust surface, and the outer peripheral surface of the thrust plate, and 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.

4. The scroll compressor according to claim 3, wherein a chip clearance between the fixed scroll and the rotational scroll is 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.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a longitudinal sectional view illustrating an exemplary scroll compressor according to the present invention.

(2) FIG. 2 is a longitudinal sectional view of a back-pressure supplying mechanism according to a first embodiment of the present invention, illustrating Part II in FIG. 1 in an enlarged manner, in which (a) illustrates a case in which back pressure is not acting, and (b) illustrates a case in which back pressure is acting.

(3) FIG. 3 is a longitudinal sectional view of a back-pressure supplying mechanism according to a second embodiment of the present invention, in which (a) illustrates a case in which back pressure is not acting, and (b) illustrates a case in which back pressure is acting.

(4) FIG. 4 is a longitudinal sectional view partially illustrating a rotational scroll and a fixed scroll according to a third embodiment of the present invention, in which (a) illustrates a case in which back pressure is not acting, and (b) illustrates a case in which back pressure is acting.

(5) FIG. 5 is a longitudinal sectional view of the vicinity of a back-pressure chamber, indicating a problem with the conventional technology.

DESCRIPTION OF EMBODIMENTS

(6) Embodiments of the present invention will be described below with reference to the accompanying drawings.

First Embodiment

(7) FIG. 1 is a longitudinal sectional view illustrating an exemplary scroll compressor according to the present invention. This scroll compressor 1, incorporated in, for example, an air conditioning device of an automobile, and is driven by power of an engine (not illustrated) to compress refrigerant gas and supply the compressed refrigerant gas to a refrigerant circuit of the air conditioning device.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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 FIG. 2, the back-pressure supplying mechanism 6 includes a ring-shaped back-pressure chamber 31 formed on the thrust surface 30, a back-pressure supplying path 32 formed inside of the front housing 2a and communicating the high-pressure chamber 28 and the back-pressure chamber 31 with each other, and an inner seal ring 33 and an outer seal ring 34 disposed radially inside and outside, respectively, of the back-pressure chamber 31.

(14) 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.

(15) FIGS. 2(a) and 2(b) are longitudinal sectional views of the back-pressure supplying mechanism 6 according to a first embodiment of the present invention, illustrating Part II in FIG. 1 in an enlarged manner. The thrust plate 12 is interposed between the thrust surface 30 of the front housing 2a and the rotational scroll 10 (end plate 10a) so as to close off the back-pressure chamber 31.

(16) Similarly to the conventional structure (refer to FIG. 5), the inner seal ring 33 is formed on the thrust surface 30 and fitted to a seal ring groove 35 positioned radially inside of the back-pressure chamber 31. An outer peripheral surface 12a of the thrust plate 12 is obliquely tilted at approximately 45 degrees, and forms, together with the thrust surface 30 and an inner peripheral surface 37 of the front housing 2a, a ring space having a section shaped in an isosceles right triangle. The outer seal ring 34 is mounted inside of this ring space. With this configuration, the seal ring 34 is pressed between three surfaces of the slanted outer peripheral surface 12a of the thrust plate 12, the thrust surface 30, and the inner peripheral surface 37.

(17) The following describes actions and effects of the scroll compressor 1 configured as described above.

(18) 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 FIG. 2(a). At this stage, pressure inside of the high-pressure chamber 28 is low, and thus no back pressure is supplied to the back-pressure chamber 31.

(19) 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 FIG. 2(b), back pressure acts on the thrust plate 12 and presses to float the thrust plate 12 and the rotational scroll 10 (end plate 10a) above the thrust surface 30. With this configuration, the leading end parts of the wraps 10b and 8b of the rotational scroll 10 and the fixed scroll 8 illustrated in FIG. 1 can be reliably made contact with the corresponding end plates 8b and 10b to prevent generation of a chip clearance (gap) and leakage of the refrigerant gas, thereby achieving improved efficiency of the scroll compressor 1.

(20) 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 FIG. 5) for engagement with the outer seal ring 34, which has been conventionally done.

(21) 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 FIG. 5, and thus the width of the back-pressure chamber 31 formed therebetween can be increased. The back pressure applied to the back-pressure chamber 31 having an increased width acts on the thrust plate 12 across the entire width W2 between the inner seal ring 33 and the outer seal ring 34. Accordingly, pressing force on the rotational scroll 10 by the back pressure can be increased to reduce leakage of the refrigerant gas, thereby achieving improved compression efficiency of the scroll compressor 1.

(22) 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.

Second Embodiment

(23) FIGS. 3(a) and 3(b) are longitudinal sectional views of a back-pressure supplying mechanism 40 according to a second embodiment of the present invention. The back-pressure supplying mechanism 40 has a configuration same as that of the back-pressure supplying mechanism 6 according to the first embodiment except for disposition of the outer seal ring 34 maintaining the air-tightness of the back-pressure chamber 31. Any identical component is denoted by an identical reference sign, and description thereof will be omitted.

(24) 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.

(25) 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 FIG. 2), and thus the width of the back-pressure chamber 31 formed therebetween can be larger than that in the first embodiment. The back pressure applied to the back-pressure chamber 31 having an increased width acts on the thrust plate 12 across the entire interval W3 between the inner seal ring 33 and the outer peripheral part (inner peripheral surface 37) of the outer seal ring 34. Accordingly, pressing force on the rotational scroll 10 by the back pressure can be further increased to reduce leakage of the refrigerant gas, thereby achieving improved compression efficiency of the scroll compressor 1.

(26) 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.

Third Embodiment

(27) FIGS. 4(a) and 4(b) are longitudinal sectional views partially illustrating the rotational scroll and the fixed scroll according to a third embodiment of the present invention. The present embodiment is preferably performed in combination with the configurations in the first embodiment and the second embodiment.

(28) In the third embodiment, as illustrated in FIG. 4(a), before the back pressure is supplied to the rotational scroll 10, a predetermined chip clearance C is provided between the leading end part of the wrap 8b of the fixed scroll 8 and the end plate 10a of the rotational scroll 10, and between the leading end part of the wrap 10b of the rotational scroll 10 and the end plate 8a of the fixed scroll 8.

(29) 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.

(30) As illustrated in FIG. 4(b), after the back pressure is supplied to the rotational scroll 10, the chip clearance C disappears due to floating of the rotational scroll 10 by the back pressure, thereby preventing leakage of pressure from the compression pocket 9.

(31) 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.

(32) 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.

(33) 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 FIGS. 2 and 3. This back pressure presses the rotational scroll 10 to narrow the chip clearance C, thereby reducing leakage from the compression pocket 9 to achieve normal compression efficiency.

(34) 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.

(35) 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.

(36) 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.

(37) 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.

(38) 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.

REFERENCE SIGNS LIST

(39) 1 scroll compressor 2 housing 5 scroll compression mechanism 6 back-pressure supplying mechanism 8 fixed scroll 9 compression pocket 10 rotational scroll 12 thrust plate 12a, 12b outer peripheral surface of thrust plate 14 main shaft 25 low-pressure chamber 28 high-pressure chamber 30 thrust surface 31 back-pressure chamber 32 back-pressure supplying path 33 inner seal ring 34 outer seal ring 37 inner peripheral surface of housing 41 outer peripheral groove C chip clearance