Horizontal stepped spiral compressor

Abstract

Horizontal stepped spiral compressor (1), wherein step sections (13D, 13E; 14D, 14E) are provided at each of positions of tooth heads and tooth bases in spiral turns (13B; 14B) of a stationary spiral (13) and a rotating spiral (14) forming a pair of compression chambers (15A, 15B) along the spiral directions therether, and wherein a height of the spiral turn (13B; 14B) on an outer circumferential side thereof is greater than a height of the spiral turn (13B; 14B) on an inner circumferential side thereof on the respective sides of the step sections (13D, 13E; 14D, 14E), wherein the horizontal stepped spiral compressor (1) comprises: Bypass openings (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) which, when a pressure in the pair of compression chambers (15A, 15B) reaches or exceeds a certain pressure at an intermediate compression position between a suction shut-off position and a position connected to an outlet opening (13C), divert the pressure into an outlet chamber (21) and are provided along the spiral direction of spiral turns (13B; 14B); and Among the bypass openings (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) is an opening area of ​​the bypass opening (23B, 23B1; 24B, 24B1; 25B) that opens into a first compression chamber (15B) which includes the stage parts (13E, 14D; 13D, 14E) on a lower side in a direction of gravity, larger than an opening area of ​​the bypass opening (23A; 24A; 25A) that opens into a second compression chamber (15A) which forms a pair with the first compression chamber (15B) when the stage parts (13E, 14D; 13D, 14E) begin to engage.

Description

[0001] The present invention relates to a horizontal stepped spiral compressor in which step parts are provided at positions of a stationary spiral and a rotating spiral following a spiral direction.

[0002] A so-called stepped spiral compressor, in which stage elements are provided at all positions of tooth heads and tooth bases in the spiral turns of a stationary spiral and a rotating spiral along the spiral directions thereof, and in which the height of the spiral turn on an outer circumferential side is greater than the height of the turn on an inner circumferential side of the respective sides of the stage elements, can compress a refrigerant gas not only in the circumferential direction of the spiral turns but also in a turn height direction (that is, it can perform three-dimensional compression). The stepped spiral compressor can therefore have a greater displacement and a higher compression volume than a spiral compressor that is not equipped with stages (two-dimensional compression).Accordingly, the compression ratio can be increased and the performance of the compressor improved without increasing the outer diameter of the compressor, and therefore the compressor can be manufactured smaller and lighter.

[0003] Among these staged spiral compressors, JP 2009-287 512 A discloses a staged spiral compressor equipped with an over-compression protection mechanism which, if the pressure in a compression chamber rises abnormally and reaches or exceeds a certain pressure before it communicates with an outlet port, diverts the pressure to an outlet chamber via a bypass port and a bypass valve. On the other hand, JP 2004-270 667 A discloses a two-dimensional compression-type spiral compressor wherein the stationary spiral and the rotating spiral have different numbers of turns, and wherein bypass ports provided in a rear compression chamber and a front compression chamber to form a pair are given different positions and sizes (numbers) to mitigate over-compression and liquid compression.

[0004] Furthermore, JP 2000-345 976 A discloses a horizontal scroll compressor, wherein a drive shaft is arranged in the horizontal direction, where at least four pressure relief ports and one outlet port are provided between a compression chamber formed between two scrolls and an outlet chamber, wherein a pressure relief valve is provided in each port, and one of the pressure relief ports or the outlet port is configured to be in constant communication with the compression chamber. This prevents liquid compression and over-compression throughout the entire compression stroke.

[0005] However, none of JP 2009-287512A, JP 2004-270667A, and JP 2000-345976A discloses a method for efficiently preventing liquid compression when a horizontal step-wound scroll compressor is started from a state in which liquid refrigerant has migrated and accumulated in the compression chamber while the compressor is stopped. When a scroll compressor is started in a state where liquid refrigerant has accumulated, the spiral winding can be damaged by liquid compression. Methods that provide a bypass orifice and divert the liquid refrigerant are therefore employed to prevent excessive liquid compression.

[0006] In the case of a horizontal scroll compressor, where the drive shaft is horizontally oriented, refrigerant fluid typically migrates to and accumulates in the compression chamber on the lower side in the direction of gravity. Therefore, it is assumed that liquid compression occurs more easily in the compression chamber on the lower side in the direction of gravity. Under these circumstances, analyses carried out by the inventors have shown that, in a horizontal staged scroll compressor, the rear compression chamber and the front compression chamber, which form a pair, are connected when the stage parts separate.Accordingly, it is not always the case that liquid compaction occurs more easily in the compression chamber on the lower side in the direction of gravity; rather, it has been found that liquid compaction occurs more easily in the compression chamber where staged elements are present on the lower side in the direction of gravity when the staged elements begin to engage. The result of this analysis is described below.

[0007] Fig. Figures 6A to 6D depict compression operations in the case where the compressor is started from a state in which liquid refrigerant has accumulated to a height of approximately 50% in the compression chamber. Here, stage parts 13D and 13E, and 14D and 14E, are provided at predetermined positions along the spiral direction of the tooth tips and tooth roots of spiral turns 13B and 14B of a stationary spiral 13 and a rotating spiral 14. The drawings illustrate a case in which stage part 13E at the tooth root and stage part 14D at the tooth tip on the lower side, in the direction of gravity, are positioned at a 45° angle on the left underside when the spirals 13 and 14 are engaged.

[0008] Fig. 6A represents a state in which a spiral rotation angle is at a suction shut-off position and stage parts 13E and 14D are in engagement end positions. In this case, it is assumed that the liquid refrigerant has accumulated in a bottom compression chamber (stationary front compression chamber) 15A up to the level of a horizontal line passing through the centers of the spirals. Fig. 6B represents a state reached after the rotation angle has changed from the state that was in Fig. 6A is shown, having progressed 90° further. Here, the stage parts 13E and 14D separate, and consequently, the stationary front compression chamber 15A and the stationary rear compression chamber 15B, which form a pair, are connected, and the liquid refrigerant that is in the stationary front compression chamber 15A in Fig. The accumulated fluid from 6A moves towards the stationary rear compression chamber 15B, thus forming the pair.

[0009] Fig. 6C represents a state reached after the rotation angle has changed from the state that was in Fig. As shown in Figure 6B, the process has progressed 90°. In this position, stage sections 13E and 14D begin to engage, and the liquid refrigerant is enclosed in the two compression chambers 15A and 15B. At this point, a larger quantity of liquid refrigerant is enclosed in the stationary rear compression chamber 15B, which contains stage sections 13E and 14D on its lower side in the direction of gravity, than in the stationary front compression chamber 15A. This liquid refrigerant is then compressed, resulting in the state shown in Figure 6B. Fig. 6D is represented, and this is achieved after the rotation angle has been increased by another 90°, and liquid compression then occurs.

[0010] In the case of a horizontal stepped spiral compressor, liquid compression does not necessarily occur simply in the compression chamber (stationary front compression chamber) 15A, which is located on the lower side in the direction of gravity, at the time of commissioning, as is the case with two-dimensional horizontal compression-type spiral compressors without stages. Liquid compression occurs more readily on the side of the compression chamber (stationary rear compression chamber) 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage.

[0011] Although Fig. Figures 6A to 6D represent a case in which the stage parts 13E and 14D on the lower side are set at a position of 45° on the left underside relative to the horizontal direction in the direction of gravity. It was found that changing the positions of the stage parts 13E and 14D changes the amount of liquid refrigerant enclosed in the stationary rear compression chamber 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage. The circumstances of this change are described using Fig. 7A to 9D described.

[0012] Fig. 7A to 7D represent compaction operations in the case where the positions of the stage parts 13E and 14D on the lower side in the direction of gravity are aligned to a center-bottom position, Fig. 8A to 8D represent compaction operations in the case where the positions of the stage parts 13E and 14D on the lower side are set to a position of 45° on the right underside in the direction of gravity, and Fig. Figures 9A to 9D represent compression operations in the case where the positions of the stage parts 13E and 14D on the lower side are adjusted to a mid-side position (a horizontal position) in the direction of gravity. These diagrams show that the amount of liquid refrigerant enclosed in the compression chamber (stationary rear compression chamber) 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, differs when the stage parts 13E and 14D begin to engage, as can be seen by comparing... Fig. 7C, Fig. 8C and Fig. 9C becomes apparent.

[0013] In other words, in the case of Fig. 6C, when stage parts 13E and 14D begin to engage, a significantly larger quantity of liquid refrigerant is present on the side of the stationary compression chamber 15B, which contains stage parts 13E and 14D on the lower side in the direction of gravity, than in the stationary front compression chamber 15A, which thus form a pair, making the occurrence of liquid compression simple. Meanwhile, in the case of Fig. 7C, a significantly larger quantity of liquid refrigerant on the side of the stationary compression chamber 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, than in the stationary front compression chamber 15A, which thus forms a pair, than in the case of Fig. 6C.

[0014] In contrast, in the case of Fig. As can be seen in Figure 8C, the quantity of liquid refrigerant enclosed on the side of the stationary front compression chamber 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, has decreased to slightly more than approximately half the quantity of refrigerant enclosed in the stationary front compression chamber 15A, thus forming a pair. Furthermore, in the case of Fig. 9C shows that the amount of liquid refrigerant enclosed on the side of the stationary front compression chamber 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, is slightly less than, but still approximately half, the amount of refrigerant enclosed in the stationary front compression chamber 15A, thus forming a pair.

[0015] In light of the knowledge described above, an objective of the present invention is to provide a horizontal step spiral compressor which can efficiently prevent liquid compression even when it is started from a liquid migration state in which liquid refrigerant has migrated into the compressor while the operation of the compressor is stopped.

[0016] US Patent 5,451,146 A discloses a scroll compressor in which a cylinder is provided along an end plate of a stationary scroll element. A plurality of bypass holes, opening in the end plate and commuting to the space within the cylinder, and a plurality of operating chambers formed between the scroll walls of the stationary scroll element and a moving scroll element are sequentially opened by a piston to communicate with the suction side, thus allowing for smooth capacity changes. When reducing the capacity to approximately 0 percent, another cylinder and a plunger are used to direct the discharge pressure to the suction side. In this scroll compressor, the scroll elements have no staged sections.

[0017] DE 699 11 317 T2 discloses a variable-capacity spiral compressor which is in principle similar in design to that of US 5 451 146 A with regard to the bypass holes which open in an end plate and can be connected to a space in a cylinder, and in which the spiral elements also do not have any stepped parts which allow compression in the working spaces in a vertical direction.

[0018] JP 2011-102 579 A discloses a scroll compressor in which an outlet path, connected to a conveying chamber, is formed in the center of a spiral, and a first bypass path and a second bypass path, which are diverted to a pressure chamber during compression, are each formed by a first compression chamber and a second compression chamber. Each bypass path is formed by at least one hole. A check valve is arranged in both the bypass path and the outlet path. The bypass path of the compression chamber on the side of the outer wall of the spiral coil has fewer holes and larger hole areas than the bypass path of the compression chamber on the side of the inner wall of the spiral coil. In this scroll compressor, the spiral elements also lack stepped sections that would allow compression in the working chambers in a vertical direction.

[0019] From JP 2005-61 294 A, a staged spiral compressor is known in which a second bypass hole is provided at a position within 360° of an outer connection end to a middle section side of a spiral, and a first bypass hole is provided at a position on a middle section side of a spiral within a position of a stage section and within 360° of a position of the second bypass hole to the middle section side. Consequently, only the second bypass hole is present in a compression chamber formed at an outermost end of the spiral by blocking the fluid intake; both the first bypass hole and the second bypass hole are present in a compression chamber that moves from there to a middle section side of the spiral; and only the first bypass hole is present in a compression chamber that moves further to the middle section side of the spiral.Consequently, excessive compression prior to the execution of the displacement control at the first bypass hole is prevented by the second bypass hole.

[0020] JP H10-110 688 A discloses that four bypass holes are arranged in an end plate of a fixed spiral element. In this way, the bypass holes are always open throughout the entire compression chamber formed. A bypass valve plate is secured with a bypass screw so that it covers the bypass hole, thus forming a bypass valve. This bypass valve opens when the pressure in the compression chamber exceeds the pressure in a fixed back wall chamber of a delivery system. Since the pressure in the fixed back wall chamber is a delivery pressure, the bypass valve thus connects the compression chamber and the delivery system when the pressure in the compression chamber exceeds the delivery pressure, acting as a control bypass.

[0021] A horizontal stepped spiral compressor of the present invention uses the features of claim 1 or claim 5 to solve the problems described above.

[0022] This means that a horizontal stepped spiral compressor according to claim 1 is a horizontal stepped spiral compressor, wherein step sections are provided at all positions of tooth heads and tooth bases in spiral turns of a stationary spiral and a rotating spiral, forming a pair of compression chambers along the spiral directions thereof, and wherein the height of the spiral turn on an outer circumferential side thereof is greater than the height of the turn on an inner circumferential side thereof on the respective sides of the step sections. Bypass openings, which divert the pressure to the outlet chamber when a pressure in the pair of compression chambers reaches or exceeds a certain pressure at an intermediate compression position between a suction shut-off position and a position connected to an outlet opening, are provided along the spiral direction of the spiral turns.Among the bypass openings, an opening area of ​​the bypass opening that opens into a first compression chamber which includes the stage parts on a lower side in a direction of gravity is larger than an opening area of ​​the bypass opening that opens into a second compression chamber which forms a pair with the first compression chamber when the stage parts begin to engage.

[0023] In a horizontal scroll compressor, the refrigerant fluid migrates and accumulates in a compression chamber located on the lower side (in the direction of gravity) when the compressor is stopped. Consequently, it is easier for the fluid to be compressed on the side of the compression chamber located on the lower side (in the direction of gravity) when the compressor starts. However, in the case of a so-called multi-stage scroll compressor, a rear compression chamber and a front compression chamber, which form a pair, are connected when the stages separate.Therefore, it is not necessarily the case that liquid compaction simply occurs in the compaction chamber on the lower side in the direction of gravity; rather, liquid compaction occurs more easily on the side of the compaction chamber that contains the stage parts on the lower side in the direction of gravity when the stage parts begin to engage.

[0024] According to the present invention, bypass openings are provided which, when a pressure in the pair of compression chambers reaches or exceeds a certain pressure at an intermediate compression position between a suction shut-off position and a position connected to an outlet opening, divert the pressure into the outlet chamber along the spiral direction of spiral turns. Among the bypass openings, an opening area of ​​the bypass opening that opens into a first compression chamber, which contains the stage parts on the lower side in a gravity direction, is larger than an opening area of ​​the bypass opening that opens into a second compression chamber, which forms a pair with the first compression chamber, when the stage parts begin to engage.Therefore, even if the horizontal step-wound compressor is started in a state where liquid refrigerant has accumulated, excessive liquid compression on the first compression chamber side, where liquid compression can easily occur, can be prevented by diverting the liquid refrigerant trapped in the first compression chamber, which contains the stage components on the lower side in the direction of gravity, through the bypass port, which has a larger opening area, to the discharge chamber when the stage components begin to engage. Consequently, liquid compression during the liquid migration start-up of the horizontal step-wound compressor can be effectively prevented, thus reducing the risk of damage to the spirals caused by liquid compression and improving its reliability.

[0025] Furthermore, in the horizontal step spiral compressor according to the present invention, an opening area of ​​a second bypass opening, which is open in a region from a position before the first compression chamber is closed to the bypass opening, to a position where the first compression chamber is in contact with the outlet opening, is preferably also larger than an opening area of ​​a second bypass opening, which is open in a region from a position before the second compression chamber is closed to the second bypass opening, to a position where the second compression chamber is in contact with the outlet opening.

[0026] According to the present invention, an opening area of ​​a second bypass opening, which is open in a region from a position before the first compression chamber is closed to the bypass opening, to a position where the first compression chamber is connected to the outlet opening, is also larger than an opening area of ​​a second bypass opening, which is open in a region from a position before the second compression chamber is closed to the second bypass opening, to a position where the second compression chamber is connected to the outlet opening.Therefore, if liquid compression occurs in the first compression chamber within the engagement area from the point where the first compression chamber is closed to the bypass opening where the first compression chamber is also connected to the outlet opening, this liquid refrigerant can be diverted to the outlet chamber via the second bypass opening, which has a larger opening area. Accordingly, liquid compression in the first compression chamber during the overall compression process can be reliably prevented after the stage components have engaged, and the longevity and reliability of the horizontal multistage spiral compressor can be ensured with regard to the onset of liquid migration.

[0027] Furthermore, in the horizontal step spiral compressor according to the present invention, the opening area is preferably enlarged by providing a larger number of bypass openings and / or second bypass openings opening into the first compression chamber than bypass openings and / or second bypass openings opening into the second compression chamber.

[0028] According to the present invention, the opening area is increased by providing a greater number of bypass openings and / or secondary bypass openings opening into the first compression chamber than bypass openings and / or secondary bypass openings opening into the second compression chamber. Therefore, if the diameter of this type of opening is limited to a predetermined diameter, the opening area can be easily increased by increasing the number of openings.Accordingly, during the liquid migration start, liquid refrigerant trapped in the first compression chamber can be smoothly diverted through the bypass openings and / or second bypass openings, the opening area of ​​which has been increased by increasing the number of openings, and consequently liquid compression on the first compression chamber side can be reliably prevented.

[0029] Furthermore, in the horizontal step spiral compressor, the opening area is preferably increased by providing the bypass openings and / or second bypass openings that open into the first compression chamber with a larger opening area per opening than the opening area per opening of the bypass openings and / or second bypass openings that open into the second compression chamber.

[0030] According to the present invention, the opening area is increased by providing the bypass openings and / or secondary bypass openings opening into the first compression chamber with a larger opening area per opening than the opening area per opening of the bypass openings and / or secondary bypass openings opening into the second compression chamber. Therefore, if the diameter of this type of opening is limited to a previously defined diameter, the opening area can be easily increased by making each opening a longer hole, for example, to change its opening area.Accordingly, during the liquid migration start, liquid refrigerant trapped in the first compression chamber can be smoothly diverted through the bypass openings and / or second bypass openings, the opening area of ​​which has been increased by enlarging the opening area per opening, and consequently, liquid compression on the first compression chamber side can be reliably prevented.

[0031] A horizontal stepped spiral compressor according to claim 5 is further a horizontal stepped spiral compressor, wherein step sections are provided at all positions of tooth heads and tooth bases in spiral turns of a stationary spiral and a rotating spiral, which form a pair of compression chambers along the spiral directions therein, and wherein the height of the spiral turn on an outer circumferential side thereof is greater than the height of the turn on an inner circumferential side thereof on the respective sides of the step sections. Bypass openings, which divert the pressure to the outlet chamber when a pressure in the pair of compression chambers reaches or exceeds a certain pressure at an intermediate compression position between a suction shut-off position and a position connected to an outlet opening, are provided along the spiral direction of spiral turns.Among the pairs of step parts are step parts that are located on a lower side in the direction of gravity in a range between 0° and 45° in a spiral rotation direction relative to a horizontal direction.

[0032] According to the present invention, bypass openings are provided which, when a pressure in the pair of compression chambers reaches or exceeds a certain pressure at an intermediate compression position between a suction shut-off position and a position connected to an outlet opening, divert the pressure into the outlet chamber along the spiral direction of spiral turns. Beneath the pairs of stage sections are stage sections located on a lower side in the direction of gravity at an angle between 0° and 45° in a spiral direction relative to a horizontal direction. Even when the horizontal staged spiral compressor is started in a state in which liquid refrigerant has accumulated, the stage sections located beneath the pairs of stage sections on the lower side in the direction of gravity are situated at an angle between 0° and 45° in a spiral direction relative to a horizontal direction.By ensuring that the amount of liquid refrigerant enclosed in the first compression chamber, which contains the stage parts located on the lower side in the direction of gravity when the stage parts begin to engage, is equal to the amount of liquid refrigerant enclosed in the second compression chamber, thus forming a pair, and by diverting the liquid refrigerants through the bypass ports to the outlet chamber, the risk of liquid compression occurring in the first and second compression chambers, or in other words, in the rear compression chamber and the front compression chamber, which form a pair, can be reduced.Accordingly, liquid compaction during the liquid migration start of the horizontal step spiral compressor can be efficiently prevented, thereby reducing the risk of damage or the like to the spiral windings caused by liquid compaction and improving its reliability.

[0033] In the horizontal step spiral compressor, the step parts, which are located on the lower side in the direction of gravity, are preferably situated in a range between 20° and 40° in the spiral rotation direction relative to the horizontal direction.

[0034] According to the present invention, the stage parts located on the lower side in the direction of gravity are positioned at an angle of 20° to 40° in a helical rotation relative to the horizontal. Accordingly, the amount of liquid refrigerant enclosed in the first compression chamber, which contains the stage parts on the lower side in the direction of gravity when the stage parts begin to engage, and the amount of liquid refrigerant enclosed in the second compression chamber, thus forming a pair, can be brought closer together in the direction of equalization, thereby reducing the risk of liquid compression occurring in the first and second compression chambers.Consequently, liquid compaction in the respective compression chambers during the compaction process can be reliably prevented after the start of the engagement of the stage parts, and the longevity and reliability of the horizontal stage spiral compressor can be ensured with regard to the start of liquid migration.

[0035] In the horizontal step spiral compressor, the step parts, which are located on the lower side in the direction of gravity, are preferably positioned at 30° in the spiral direction of rotation relative to the horizontal direction.

[0036] According to the present invention, the stage parts located on the lower side in the direction of gravity are positioned at a 30° angle in a spiral rotation direction relative to a horizontal direction. Accordingly, the amount of liquid refrigerant enclosed in the first compression chamber, which contains the stage parts on the lower side in the direction of gravity when the stage parts begin to engage, and the amount of liquid refrigerant enclosed in the second compression chamber, thus forming a pair, can be substantially equalized, and the risk of liquid compression occurring in the first and second compression chambers, which form a pair, can be further reduced.Accordingly, liquid compaction in the respective compaction chambers during the compaction process can be reliably prevented after the start of the engagement of the stage parts, and the longevity and reliability of the horizontal stage spiral compressor can be ensured with regard to the start of liquid migration.

[0037] Even if, according to the present invention, the horizontal step spiral compressor is started in a state in which liquid refrigerant has accumulated, the occurrence of excessive liquid compression on the first compression chamber side, where liquid compression can easily occur, can be prevented by diverting the liquid refrigerant enclosed in the first compression chamber, which contains the stage parts on the lower side in the direction of gravity, to the outlet chamber via the bypass opening, whose opening area is larger, when the stage parts begin to engage.Accordingly, liquid compaction during the liquid migration start of the horizontal step spiral compressor can be efficiently prevented, thereby reducing the risk of damage or the like to the spirals caused by liquid compaction and improving its reliability.

[0038] Furthermore, if the horizontal step spiral compressor, according to the present invention, is started in a state in which liquid refrigerant has accumulated, the stage parts, among the pairs of stage parts located on the lower side in the direction of gravity, are in a range between 0° and 45° in a spiral rotation direction relative to a horizontal direction.By ensuring that the amount of liquid refrigerant enclosed in the first compression chamber, which contains the stage parts located on the lower side in the direction of gravity when the stage parts begin to engage, is equal to the amount of liquid refrigerant enclosed in the second compression chamber, thus forming a pair, and by diverting the liquid refrigerants through the bypass ports to the outlet chamber, the risk of liquid compression occurring in the first and second compression chambers, or in other words, in the rear compression chamber and the front compression chamber, which form a pair, can be reduced.Accordingly, liquid compaction during the liquid migration start of the horizontal step spiral compressor can be efficiently prevented, thereby reducing the risk of damage or the like to the spiral windings caused by liquid compaction and improving its reliability. Fig. Figure 1 is a vertical cross-sectional view of a horizontal spiral compressor according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view along AA in Fig. 1. Fig. 3A to 3D are explanatory diagrams of compression operations that represent a transition to an engagement state of stationary and rotating spirals in the spiral compressor mentioned. Fig. Figures 4A to 4E are explanatory diagrams of compression operations that represent a transition to an engagement state of both spirals in a horizontal step spiral compressor according to a second embodiment of the present invention. Fig. Figure 5 is an explanatory scheme that illustrates a relationship between the height of the liquid surface of a liquid refrigerant that has accumulated in a compression chamber of the aforementioned scroll compressor and a liquid compression pressure that is generated. Fig. Figures 6A to 6D are explanatory diagrams of compression operations during the liquid migration start in the case where stage parts of a horizontal stage spiral compressor are on the lower side in the direction of gravity in a position of 45° on the left underside relative to the horizontal direction. Fig. Figures 7A to 7D are explanatory diagrams of compression operations during the liquid migration start in the case where the stage parts of the listed compressor are positioned on the lower side in the direction of gravity at a mid-bottom position relative to the horizontal direction. Fig. Figures 8A to 8D are explanatory diagrams of compression operations during the liquid migration start in the case where the stage parts of the listed compressor are on the lower side in the direction of gravity in a position of 45° on the right underside relative to the horizontal direction. Fig. Figures 9A to 9D are explanatory diagrams of compression operations during the liquid migration start in the case where the stage parts of the listed compressor are positioned on the lower side in the direction of gravity at a mid-side position (a horizontal position) relative to the horizontal direction.

[0039] The embodiments of the present invention are described below with reference to the drawings.

[0040] A first embodiment of the present invention will now be described below with reference to Fig. 1 to 3D and 5 described.

[0041] Fig. Figure 1 is a vertical cross-sectional view of a horizontal spiral compressor according to the first embodiment of the present invention. Fig. 2 is a cross-sectional view, taken along AA in Fig. 1, and Fig. Figures 3A to 3D are explanatory diagrams of compression operations of the spiral compressor mentioned.

[0042] A horizontal stepped spiral compressor 1 comprises a housing 2, which forms an outer shell. The housing 2 is formed by a cup-shaped housing 3 with a closed end, which is sealed at one end, and a front housing 4, which is attached and mounted to the open end of the cup-shaped housing 3, the two housings being fastened and connected to each other by screws or the like to form an integrated unit.

[0043] In the front housing 4, a crankshaft 5 is supported by a main bearing 6 and a lower bearing 7, such that it can rotate freely about an axis of the crankshaft 5. One end of the crankshaft 5 (a left end in Fig. 1) serves as a small diameter shaft part 5A, and the small diameter shaft part 5A runs through the front housing 4 and points to the left in Fig. 1. A known electromagnetic coupling, a belt, or the like, to which a driving force is transmitted from the outside, is provided on one end of the small-diameter shaft section 5A, which projects outwards, and a driving force is supplied by an external drive source, such as a motor via a belt. A lip seal 8 is fitted between the main bearing 6 and the sub-bearing 7, thereby forming a seal between the interior of the housing 2 and the atmospheric air.

[0044] A large-diameter shaft section 5B is located on another end face of the crankshaft 5 (a right end face in Fig. 1) A crankpin 5C, which is off-center from the axis of the crankshaft 5 by a predetermined dimension, is integrally formed with a large-diameter shaft section 5B. Because the large-diameter shaft section 5B and the small-diameter shaft section 5A are supported by the main bearing 6 and the lower bearing 7, the crankshaft 5 is supported by the front housing 4 in such a way that it can rotate freely. A rotating spiral 14, which will be described later, is connected to the crankpin 5C by a drive sleeve 9 and a rotating bearing 10, and the rotating spiral 14 is driven to rotate by the rotary drive of the crankshaft 5.

[0045] A locating hole, into which the crankpin 5C is mounted, is provided in the drive sleeve 9. The crankpin 5C and the rotating spiral 14 are connected by mounting a hub section 14C of the rotating spiral 14 on the outer circumference of the drive sleeve 9, which is attached to the crankpin 5C, via the rotating bearing 10. A known auxiliary crank mechanism, by which the radius of curvature of the rotating spiral 14 is variable, can be provided between the drive sleeve 9 and the crankpin 5C. Furthermore, a counterweight 11 for eliminating unbalanced loads generated by the rotating rotating spindle 14 is provided on the drive sleeve 9 and is driven to rotate together with the rotating spiral 14.

[0046] A spiral compression mechanism (compression mechanism) 12, consisting of a stationary spiral 13 and a rotating spiral 14 forming a pair, is integrated into the housing 2. The stationary spiral 13 consists of an end plate 13A and a spiral turn 13B erected from the end plate 13A, and the rotating spiral 14 consists of an end plate 14A and a spiral turn 14B erected from the end plate 14A.

[0047] According to the present embodiment, the stationary spiral 13 and the rotating spiral 14 each comprise step parts 13D and 13E and step parts 14D and 14E, which are located at predetermined positions of tooth heads and tooth bases of the spiral turns 13B and 14B along the spiral directions thereof (see Fig. 2) are provided. The tooth tips of the spiral turns 13B and 14B are formed such that a tooth tip on an outer circumferential side is higher in a circumferential axial direction, and a tooth tip on the inner circumferential side is lower on the respective sides of the step sections 13D and 13E and step sections 14D and 14E. Furthermore, the tooth roots are formed such that a tooth root on the outer circumferential side is lower in the circumferential axial direction, and a tooth root on the inner circumferential side is higher. Therefore, the spiral turns 13B and 14B have a greater turn height on the outer circumferential side than the turn height on the inner circumferential side.

[0048] The stationary spiral 13 and the rotating spiral 14 are connected such that their centers are separated by a distance equivalent to the curve radius, and the phases of the spiral turns 13B and 14B are shifted by 180 degrees. They are assembled such that a small gap exists in the turn height direction between the tooth tips and tooth roots on the spiral turns 13B and 14B on the respective spirals at normal temperature. Consequently, as in Fig. Figure 1 shows a pair of compression chambers 15, which are delimited by the end plates 13A and 14A and the spiral turns 13B and 14B, formed between the spirals 13 and 14, such that they are symmetrical relative to the spindle centers, and the orbiting spiral 14 rotates frictionlessly around the stationary spiral 13.

[0049] The compression chambers 15 are configured such that their height in the circumferential axial direction is greater on an outer circumferential side of the spiral coils 13B and 14B than on an inner circumferential side, thereby forming the compression mechanism 12, which can perform three-dimensional compression in which a gas can be compressed not only in the circumferential direction of the spiral coils 13B and 14B, but also in a coil height direction. Note that in the tooth heads of the spiral coils 13B and 14B, a head seal 16 is fitted, sealing a head sealing surface formed with the tooth base of the partner spiral in a groove provided in the tooth head. The horizontal stage spiral compressor 1 configured in this way is well known.

[0050] The stationary spiral 13 is fastened to an inner base surface of the cup-shaped housing 3 by a plurality of screws 17. Furthermore, the rotating spiral 14 connects the crankpin 5C, located on one end of the crankshaft 5, to the hub part 14C, located on the rear surface of the end plate 14A, via the drive sleeve 9 to the rotating spiral 14, as previously described. The rear surface of the end plate 14A is supported by a thrust bearing surface of the front housing 4, and the rotating spiral 14 is driven such that it rotates circularly around the stationary spiral 13. Its rotation is prevented by an anti-rotation mechanism 18, such as an Oldham coupling, located between the thrust bearing surface and the rear surface of the end plate 14A. The self-rotation protection mechanism 18 can be a known pin-ring-type self-rotation protection mechanism.

[0051] An outlet opening 13C, which releases compressed refrigerant gas, is formed in the stationary coil 13 in a central region of the end plate 13A. An outlet line valve 19 is mounted in the outlet opening 13C via a bracket. Furthermore, a sealing element 20, such as an O-ring, is provided on the rear surface of the end plate 13A of the stationary coil 13 to establish close contact with the inner surface of the cup-shaped housing 3. An outlet chamber 21, which is separated from the interior of the housing 2, is formed with the inner surface of the cup-shaped housing 3. Consequently, the configuration is such that the interior of the housing 2, in addition to the outlet chamber 21, serves as an inlet chamber 22.

[0052] In the horizontal staged spiral compressor 1, configured as described above, over-compaction, liquid compaction, and the like can occur in response to changes in operating conditions. In this case, excessive stress caused by over-compaction, liquid compaction, or the like can act, for example, on the base parts of the stage sections 13D and 14D and on the toothed faces of the spiral turns 13B and 14B in the stationary spiral 13 and the rotating spiral 14. There is a risk that this stress will cause cracks to form in the bases of the stage sections 13D and 14D and damage the spiral turns 13B and 14B.

[0053] Accordingly, the present embodiment employs a configuration in which a plurality of pairs of bypass openings, i.e., first bypass openings 23A and 23B, second bypass openings 24A and 24B, and third bypass openings 25A and 25B, are provided along the spiral direction, which open into the respective compression chambers 15 and prevent over-compression or liquid compression in the overall compression stroke from a suction shut-off position of the pair of compression chambers 15 (θd) until the stage parts 13D and 14E begin to engage (a θs position), through a position where this engagement ends (θs + n), and finally to a position where the pair of compression chambers 15 is joined and communicates with the outlet opening 13C (θp).

[0054] It is assumed that bypass valves (not shown) are provided in the openings of the first bypass openings 23A and 23B, 24A and 24B, and 25A and 25B leading to the outlet chamber 21 when a pressure in the compression chambers 15 reaches or exceeds a certain pressure. Note that providing bypass valves in this manner is known.

[0055] As previously described, it was further discovered that in the horizontal step spiral compressor 1, when the compressor is started in a liquid migration state in which liquid refrigerant migrates into the compressor while the operation of the compressor is stopped, liquid compression does not occur more easily in the compression chamber located on the lower side in the direction of gravity at the time of start-up, but rather on the side of a first compression chamber (stationary rear compression chamber) 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13D and 14E begin to engage.Based on this knowledge, the following configuration is used in addition to the first bypass openings 23A and 23B, second bypass openings 24A and 24B and third bypass openings 25A and 25B described above to efficiently prevent liquid compaction that occurs when starting from a liquid migration state.

[0056] This means that an additional first bypass opening 23B1 is provided next to the first bypass opening 23B, which opens into the first compression chamber (stationary rear compression chamber) 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13D and 14E begin to engage, such that the opening area of ​​the first bypass openings 23B and 23B1, which open into the side of the first compression chamber (stationary rear compression chamber) 15B, is larger than the opening area of ​​the first bypass opening 23A, which opens into a second compression chamber (stationary front compression chamber) 15A and forms a pair with the first compression chamber 15B. This allows the liquid refrigerant to be diverted more easily and consequently prevents liquid compression.

[0057] Furthermore, a second bypass opening 24B1 is provided at a position of the second bypass opening 24B, which opens into the first compression chamber (stationary rear compression chamber) 15B, while the first compression chamber (stationary rear compression chamber) 15B moves from the engagement start position (θs), through the engagement end position (θs + n), and to the contact point with the outlet opening 13C (θp). Consequently, the opening area of ​​the second bypass openings 24B and 24B1, which open into the side of the first compression chamber (stationary rear compression chamber) 15B, is larger than the opening area of ​​the second bypass opening 24A, which opens into the second compression chamber (stationary front compression chamber) 15A and forms a pair with the first compression chamber 15B.

[0058] This allows the liquid refrigerant to be redirected more easily, thus ensuring that no liquid compression occurs.

[0059] Note that it is assumed that bypass valves opening the bypass ports 23B1 and 24B1 to the outlet chamber 21 when the pressure in the first compression chamber 15B reaches or exceeds a certain pressure are also provided in the additionally provided first bypass port 23B1 and second bypass port 24B1. The bypass valves for the first bypass port 23B1 and the second bypass port 24B1 may be the same as the bypass valves provided for the first bypass port 23B and the second bypass port 24B.

[0060] According to the configuration described above, the present embodiment has the following operational effects. In the horizontal stepped spiral compressor 1, a low-pressure refrigerant gas, which is drawn into the inlet chamber 22 in the housing 2 from an outlet opening (not shown), is drawn into the pair of compression chambers 15 by the rotating drive of the rotating spiral 14. This refrigerant gas is subjected to three-dimensional compression while the compression chambers 15 move from the outer circumferential side towards the central side in the circumferential direction and in the direction of the spiral turns 13B and 14B, and decrease in volume after the pair of compression chambers 15 merge and connect with the outlet opening 13C. The outlet valve 19 opens and consequently discharges into the outlet chamber 21.The high-pressure gas is directed to the outside through an outlet opening provided in housing 2.

[0061] In this compression process, depending on the operating conditions, there are instances where the pressure in the compression chambers 15 rises abnormally, creating a state of over-compression. Liquid refrigerant may be drawn in, and the pressure may rise abnormally under liquid compression, or similar conditions. In such cases, excessive stress caused by over-compression, liquid compression, or similar factors can act on the base parts of the stage sections 13D and 14D, as well as on the toothed faces of the spiral windings 13B and 14B in the stationary spiral 13 and the rotating spiral 14. There is a risk that this stress concentration will cause cracks to form in the bases of the stage sections 13D and 14D and damage the spiral windings 13B and 14B.

[0062] However, in the present embodiment, the plurality of pairs of bypass openings, i.e., the first bypass openings 23A and 23B, the second bypass openings 24A and 24B, and the third bypass openings 25A and 25B, are provided along the spiral direction, opening into the respective compression chambers 15 in the overall compression stroke from the suction shut-off position of the pair of compression chambers 15 (θd) to the position where the compression chambers 15 are connected with the outlet opening 13C (θp). Accordingly, unusual pressure caused by over-compression or liquid refrigerant under liquid compression in the compression chambers 15 can be successively diverted from the first bypass openings 23A and 23B, the second bypass openings 24A and 24B, and the third bypass openings 25A and 25B via the line valves to the outlet chamber 21. The risk of damage to the spiral windings 13B and 14B can thus be eliminated.

[0063] On the other hand, liquid refrigerant can migrate and accumulate in the compression chambers 15 while the operation of the horizontal step-volume spiral compressor 1 is stopped. When the compressor is started in this liquid migration state, it is known that liquid compression occurs more simply on the side of the first compression chamber (stationary rear compression chamber) 15B in the horizontal step-volume spiral compressor 1, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage.The opening area of ​​the first bypass openings 23B and 23B1, which open into the first compression chamber (fixed rear compression chamber) 15B, is larger than the opening area of ​​the first bypass opening 23A, which opens into the second compression chamber (fixed front compression chamber) 15A and forms a pair with the first compression chamber (fixed rear compression chamber) 15B.

[0064] Accordingly, it can be facilitated to divert the liquid refrigerant to the first compression chamber (stationary rear compression chamber) on side 15B, where liquid compression occurs more readily. This effectively prevents liquid compression in the horizontal step-wound compressor 1.

[0065] Meanwhile, the further second bypass opening 24B1 is provided at a position of the second bypass opening 24B that opens into the first compression chamber (fixed rear compression chamber) 15B, while the first compression chamber (fixed rear compression chamber) 15B moves from the position of the start of engagement (θs), via the end of engagement position (θs + n) and to the position of contact with the outlet opening 13C (θp), and therefore a larger opening area is provided than the second bypass opening 24A, which opens into the second compression chamber (fixed front compression chamber) 15A and forms a pair with the first compression chamber 15B. Accordingly, liquid compaction in the first compaction chamber (stationary rear compaction chamber) 15B can be reliably suppressed throughout the entire compaction process after the start of the engagement of stage parts 13D and 14E and stage parts 13E and 14D.

[0066] Furthermore, in the aforementioned embodiment, the additional first bypass opening 23B1 and second bypass opening 24B2 are provided for the first bypass opening 23B and the second bypass opening 24B, respectively, to enlarge the opening area of ​​the openings into the first compression chamber (stationary rear compression chamber) 15B, which contains the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13D and 14E begin to engage. This allows the opening area to be easily enlarged, which in turn simplifies the diversion of the liquid refrigerant.

[0067] Note that instead of increasing the number of openings as described above, the bypass opening 23B and the second bypass opening 24B themselves may, for example, be formed as long holes or the like to increase the opening area of ​​the first bypass opening 23B and the second bypass opening 24B opening into the first compression chamber (fixed rear compression chamber) 15B.

[0068] It goes without saying that the degree of the aforementioned liquid compression is determined by the amount of liquid refrigerant that accumulates in the compression chambers 15. As in Fig. As shown in Figure 5, if the liquid refrigerant has accumulated to the point where the pair of compression chambers 15 is full (a liquid surface height of 100%), for example at the suction shut-off position (θd), it is pointless to simply drain liquid from one of the compression chambers 15. This means that further measures are necessary in this case. In contrast, if the liquid surface height is less than or equal to 30%, the pressure generated by liquid compression is less than or equal to an acceptable range and therefore does not pose a problem. Consequently, it is assumed that the effects described above are effective when the liquid surface height is greater than 30% and at most approximately 70%.

[0069] A second embodiment of the present invention is described below with reference to Fig. 4A to 4E described.

[0070] The present embodiment differs from the first embodiment described above in that liquid compaction is prevented by defining the positions of the stage parts 13E and 14D, which are located on the lower side in the direction of gravity, for a corresponding range without changing the opening area of ​​the bypass openings. Other aspects are similar to the first embodiment, which is why descriptions of them are omitted here.

[0071] In other words, the present embodiment was obtained on the basis of the knowledge that changing the set positions of the stage parts 13E and 14D, which are located on the lower side in the direction of gravity, causes a change in the amount of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage.

[0072] Even if, as in Fig. As described in sections 4A to 4E, the same quantity of liquid refrigerant is enclosed in the compression chambers 15. Changing the positions of the stage parts 13E and 14D causes a change in the quantity of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, which contains the stage parts 13E and 14D on its lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage. This is, as previously described, with reference to Fig. 6A to 9D, and Fig. 4A to 4D are diagrams, each of which Fig. 6C, Fig. 7C, Fig. 8C and Fig. 9C corresponds.

[0073] Fig. 4A shows the positions of the step parts 13E and 14D on the lower side in the direction of gravity, which are set to a position of 45° on the left underside relative to the horizontal direction. Fig. 4B, Fig. 4C, Fig. 4D and Fig. Figures 4E represent compression states in the case where the positions of stage parts 13E and 14D are fixed to a mid-bottom position, the positions of stage parts 13E and 14D are fixed to a 45° position on the right bottom, the positions of stage parts 13E and 14D are fixed to a mid-side position (a horizontal position), and the positions of stage parts 13E and 14D are fixed to a 30° position on the right bottom. As shown in these drawings, the amount of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, which contains stage parts 13E and 14D on the bottom in the direction of gravity, changes when stage parts 13E and 14D and stage parts 13D and 14E begin to engage.

[0074] In the cases of Fig. 4A and Fig. 4B, the amount of liquid refrigerant enclosed on the first compression chamber (fixed rear compression chamber) 15B side is much greater than the amount of liquid refrigerant enclosed in the second compression chamber (fixed front compression chamber) 15A, forming a pair with it, and consequently, it is simpler for liquid compression to occur in the first compression chamber (fixed rear compression chamber) 15B. But in the cases of Fig. 4C and Fig. 4D is the amount of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, essentially the same as the amount of liquid refrigerant enclosed in the second compression chamber (stationary front compression chamber) 15A, forming a pair with it (there is slightly more on the first compression chamber 15B side in the case of Fig. 4C and slightly more on the second compression chamber 15A side in the case of Fig. 4D). In the case of Fig. 4E is the amount of liquid refrigerant enclosed in compression chambers 15A and 15B, closer to being equal.

[0075] By thus equalizing the amount of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity when the stage parts 13E and 14D begin to engage, with the amount of liquid refrigerant enclosed in the second compression chamber (stationary front compression chamber) 15A, which forms a pair with the compression chamber 15B, this means that the amounts of liquid refrigerant enclosed in the compression chambers 15A and 15B can be reduced and the risk of liquid compression can be decreased.

[0076] Based on the aforementioned knowledge, in the horizontal step-spiral compressor 1, which is provided with the first bypass openings 23A and 23B, the second bypass openings 24A and 24B, and the third bypass openings 25A and 25B, which are open in the total compression stroke from the suction shut-off position of the pair of compression chambers 15 (θd) to the position where the compression chambers 15 are connected to the outlet opening 13C (θp) and prevent over-compression or liquid compression in the compression chambers 15, as in the first embodiment, the present embodiment defines the positions of the stage parts 13E and 14D on the lower side in the direction of gravity to the areas that are in Fig.4C to 4E are indicated, or in other words, preferably to a range between 0° and 45° clockwise (the spiral direction of rotation) relative to the horizontal direction, preferably in a range between 20° and 40° in the spiral direction of rotation relative to the horizontal direction and particularly to a position of 30° in the spiral direction of rotation relative to the horizontal direction.

[0077] As described above, the positions of the stage parts 13E and 14D on the lower side in the direction of gravity are fixed to a range between 0° and 45° in the spiral direction of rotation relative to the horizontal direction, preferably to a range between 20° and 40°, and particularly to a position of 30°. In this way, the amount of liquid refrigerant enclosed in the first compression chamber (stationary rear compression chamber) 15B, which includes the stage parts 13E and 14D on the lower side in the direction of gravity, when the stage parts 13E and 14D begin to engage, can be approximately equalized with the amount of liquid refrigerant enclosed in the second compression chamber (stationary front compression chamber) 15A, which forms a pair with the compression chamber 15B.

[0078] Consequently, according to the present embodiment, liquid compaction during the liquid migration start of the horizontal stage spiral compressor 1 can be efficiently prevented, thereby reducing the risk of damage or the like to the spirals caused by liquid compaction and improving its reliability.

[0079] For example, although the foregoing embodiments describe examples in which the present invention is applied in a type of horizontal stepped spiral compressor 1 in which a first end section of the crankshaft 5 projects outwards from the housing 2 and the compressor is driven by a driving force which it receives from the outside, the present invention can of course be applied in a similar way in a hermetically sealed, horizontal stepped spiral compressor in which an electric motor is integrally installed in the housing 2 and the compressor is driven by this electric motor.

[0080] Although the foregoing embodiments further describe a configuration in which the first bypass openings 23A and 23B, the second bypass openings 24A and 24B, or the third bypass openings 25A and 25B open into a pair of compression chambers 15 during the total compression stroke from the suction shut-off position (θd) to the position in which the compression chambers 15 communicate with the outlet opening 13C (θp), it is self-evident that the present invention is applied similarly in a horizontal stepped spiral compressor 1 in which bypass openings extend in a range from a position in which the stage parts 13D and 14E begin to engage (the θs position) to the position of communication with the outlet opening 13C (θp), or from a position in which these stage parts begin to engage (the θs-position), to the position where the intervention ends (θs + n), are provided. List of reference symbols 1 Horizontal stepped spiral compressor 13 Fixed spiral 13B, 14B spiral winding 13C Outlet 13D, 14D stepped part of the tooth head 13E, 14E Step portion of the tooth base 14 Circulating spiral 15 compression chamber 15A Second compression chamber (fixed front compression chamber) 15B First compression chamber (fixed rear compression chamber) 21 Outlet chamber 23A, 23B, 23B1 First bypass opening 24A, 24B, 24B1 Second bypass opening 25A, 25B Third bypass opening

Claims

[1] A horizontal step scroll compressor (1), wherein step parts (13D, 13E; 14D, 14E) are provided at each of positions of tooth crests and tooth roots in spiral wraps (13B; 14B) of a fixed scroll (13) and an orbiting scroll (14) forming a pair of compression chambers (15A, 15B) along the spiral directions thereof, and wherein a height of the spiral wrap (13B; 14B) on an outer peripheral side thereof is greater than a height of the spiral wrap (13B; 14B) on an inner peripheral side thereof on the respective sides of the step parts (13D, 13E; 14D, 14E), the horizontal step scroll compressor (1) comprising: Bypass ports (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) which, when a pressure in the pair of compression chambers (15A, 15B) reaches or exceeds a certain pressure at an intermediate compression position between a suction cut-off position and a position communicating with a discharge port (13C), bypass the pressure into a discharge chamber (21) and are provided along the spiral direction of scroll wraps (13B; 14B); and among the bypass openings (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B), an opening area of the bypass opening (23B, 23B1; 24B, 24B1; 25B) opening into a first compression chamber (15B) including the step parts (13E, 14D; 13D, 14E) on a lower side in a gravity direction is larger than an opening area of the bypass opening (23A; 24A; 25A) opening into a second compression chamber (15A) forming a pair with the first compression chamber (15B) when the step parts (13E, 14D; 13D, 14E) start to engage. [2] A horizontal staged scroll compressor (1) according to claim 1, wherein an opening area of a second bypass port (24B; 24B1) open in a range from a position before the first compression chamber (15B) is closed to the bypass port (24B; 24B1) to a position where the first compression chamber (15B) communicates with the discharge port (13C) is also larger than an opening area of a second bypass port (24A) open in a range from a position before the second compression chamber (15A) is closed to the second bypass port (24A) to a position where the second compression chamber (15A) communicates with the discharge port (13C). [3] A horizontal staged scroll compressor (1) according to claim 1 or 2, wherein the opening area is increased by providing a larger number of bypass openings (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) and / or second bypass openings (23B; 24B) opening into the first compression chamber (15B) than bypass openings and / or second bypass openings (23A; 24A) opening into the second compression chamber (15A). [4] A horizontal staged scroll compressor (1) according to claim 1 or 2, wherein the opening area is increased by providing the bypass ports (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) and / or second bypass ports (23B; 24B) opening into the first compression chamber (15B) with a larger opening area per port than the opening area per port of the bypass ports and / or second bypass ports (23A; 24A) opening into the second compression chamber (15A). [5] A horizontal step scroll compressor (1), wherein step parts (13D, 13E; 14D, 14E) are provided at each of positions of tooth tips and tooth roots in spiral wraps (13B; 14B) of a fixed scroll (13) and an orbiting scroll (14) forming a pair of compression chambers (15A, 15B) along the spiral directions thereof, and wherein a height of the spiral wrap (13B; 14B) on an outer peripheral side thereof is greater than a height of the spiral wrap (13B; 14B) on an inner peripheral side thereof on the respective sides of the step parts (13D, 13E; 14D, 14E), the horizontal step scroll compressor (1) comprising: Bypass ports (23A, 23B, 23B1; 24A, 24B, 24B1; 25A, 25B) which, when a pressure in the pair of compression chambers (15A, 15B) reaches or exceeds a certain pressure at an intermediate compression position between a suction cut-off position and a position communicating with a discharge port (13C), bypass the pressure into a discharge chamber (21) and are provided along the spiral direction of scroll wraps (13B; 14B); and among the pairs of step parts (13D,13E; 14D,14E), step parts (13E,14D; 13D,14E) located on a lower side in the direction of gravity are located in a range between 0° and 45° in a spiral rotation direction relative to a horizontal direction. [6] A horizontal step scroll compressor (1) according to claim 5, wherein the step parts (13D,14E) located on the lower side in the direction of gravity are located in a range between 20° and 40° in the scroll rotation direction relative to the horizontal direction. [7] A horizontal step scroll compressor (1) according to claim 5 or 6, wherein the step parts (13D,14E) located on the lower side in the direction of gravity are located at a position of 30° in the scroll rotation direction relative to the horizontal direction.

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