WO2023182457A1

WO2023182457A1 - Screw compressor and freezer

Info

Publication number: WO2023182457A1
Application number: PCT/JP2023/011627
Authority: WO
Inventors: 純幸植村; 貴司井上
Original assignee: ダイキン工業株式会社
Priority date: 2022-03-23
Filing date: 2023-03-23
Publication date: 2023-09-28
Also published as: JP2023143865A

Abstract

The present invention provides a screw compressor in which a compression chamber (25) is formed inside a cylinder part (16) by a screw rotor (40) and a gate (53), wherein an intake-side end part (42) of the screw rotor (40) is formed into a cylindrical shape such that an outer peripheral surface (42a) of said end part conforms to the inner peripheral surface of the cylinder part (16), and a seal part (80) that minimizes the flow of a fluid is provided in a first surface (F) toward which the outer peripheral surface (42a) of the intake-side end part (42) or an axial-direction first end surface (42b) of the intake-side end part (42) faces.

Description

Screw compressor and refrigeration equipment

The present disclosure relates to a screw compressor and a refrigeration device.

Patent Document 1 discloses a screw compressor that includes a screw rotor and a gate rotor. The screw rotor is inserted into the cylinder, and a compression chamber is formed by meshing the gate of the gate rotor with the screw groove of the screw rotor.

Japanese Patent Application Publication No. 2009-197794

By the way, there is a screw compressor in which the suction side end of the screw rotor has no suction cut that closes the compression chamber. Such a suction side end portion is formed into a cylindrical shape so that its outer circumferential surface follows the inner circumferential surface of the cylinder portion.

Due to this suction cutless shape, the pressure difference generated between the space near the suction side end in the compression chamber and the space outside the compression chamber adjacent to the suction side end creates a gap between the suction side end and the inner surface of the cylinder. There is a risk that refrigerant may flow through the gaps. For example, if intermediate-pressure refrigerant in a space outside the compression chamber adjacent to the suction side end leaks into the suction side of the compression chamber, the suction pressure will increase and compression efficiency will decrease.

An object of the present disclosure is to suppress the flow of refrigerant at the suction side end of the compression chamber of a screw compressor.

A first aspect of the present disclosure includes:
a casing (11) having a cylinder part (16) therein;
an electric motor (13) disposed within the casing (11);
a drive shaft (19) connected to the electric motor (13) and driven to rotate;
a screw rotor (40) disposed within the cylinder portion (16) and connected to the drive shaft (19);
a gate rotor (50) having a gate (53) that meshes with the screw groove (41) of the screw rotor (40);
A screw compressor in which a compression chamber is formed by the screw rotor (40) and the gate (53) inside the cylinder part (16),
The suction side end (42) of the screw rotor (40) is formed in a cylindrical shape so that the outer peripheral surface (42a) follows the inner peripheral surface of the cylinder part (16),
A first surface (F) opposite to the outer circumferential surface (42a) of the suction side end (42) or the first axial end surface (42b) of the suction side end (42) is configured to allow fluid to flow therethrough. This is a screw compressor provided with a sealing part (80) for suppressing the pressure.

The space near the suction side end (42) of the compression chamber (25) has a low pressure due to the suction refrigerant. Therefore, if the space adjacent to the compression chamber (25) via the suction side end (42) has an intermediate pressure, the refrigerant will flow between the first surface (F) and the suction side due to the pressure difference (differential pressure) of the refrigerant. It attempts to flow into the compression chamber (25) through the gap with the end (42). However, in the first aspect, the seal portion (80) provided on the first surface (F) can suppress the refrigerant from flowing through the gap between the first surface (F) and the suction side end (42). . As a result, it is possible to sufficiently ensure the pressure difference between high and low levels within the compression chamber (25), and it is possible to suppress a decrease in the capacity of the screw compressor.

A second aspect of the present disclosure provides, in the first aspect,
a bearing part (21) fixed within the cylinder part (16) and supporting the drive shaft (19);
The bearing part (21) is arranged adjacent to the suction side end part (42),
The seal portion (80) is provided on the bearing portion (21).

In the second aspect, the first surface (F) facing the suction side end (42) is located on the bearing portion (21). The seal portion (80) formed on the first surface (F) of the bearing portion (21) can suppress the refrigerant from flowing between the suction side end portion (42) and the bearing portion (21). In this way, the bearing portion (21) has a bearing function and a sealing function.

A third aspect of the present disclosure provides, in the second aspect,
The seal portion (80) is provided on the first surface (F) of the bearing portion (21) opposite to the axial end surface of the suction side end portion (42).

In the third aspect, the seal portion (80) can be provided on the end surface of the bearing portion (21).

A fourth aspect of the present disclosure is, in the second or third aspect,
The bearing portion (21) has a flange portion (21c) disposed between the inner surface of the cylinder portion (16) and the outer peripheral surface (42a) of the suction side end portion (42),
The seal portion (80) is provided on the collar portion (21c).

In the fourth aspect, the seal portion (80) is provided on the inner circumferential surface of the brim (21c), with the inner circumferential surface of the brim (21c) serving as the first surface (F). In this way, the seal portion (80) can also be provided in the bearing portion (21) having the flange portion (21c).

A fifth aspect of the present disclosure provides, in any one of the first to fourth aspects,
The gate rotor (50) has a first gate rotor (50a) and a second gate rotor (50b),
The compression chamber (25) is
a first compression chamber (23) formed by the first gate rotor (50a) and the screw rotor (40) and compressing fluid at suction pressure introduced into the casing (11) to an intermediate pressure;
A second compression chamber (24) is formed by the second gate rotor (50b) and the screw rotor (40) and compresses the fluid at the intermediate pressure to the discharge pressure.

In the fifth aspect, the screw compressor is configured as a two-stage compression type. While the intermediate pressure refrigerant discharged from the first compression chamber (23) moves to the suction port of the second compression chamber (24), there is a gap between the first surface (F) and the suction side end (42). It is possible to prevent the air from passing through the air and being sucked into the first compression chamber (23) again.

A sixth aspect of the present disclosure provides, in any one of the first to fifth aspects,
The seal portion (80) is composed of a labyrinth seal.

A seventh aspect of the present disclosure provides, in any one of the first to fifth aspects,
The seal portion (80) is configured with a surface texture.

An eighth aspect of the present disclosure is the screw compressor according to any one of the first to seventh aspects.

FIG. 1 is a schematic piping system diagram of a refrigeration system according to an embodiment. FIG. 2 is a vertical cross-sectional view showing a main part of the schematic configuration of the screw compressor according to the embodiment. FIG. 3 is a cross-sectional view taken along the line III--III in FIG. 2. FIG. 4 is a perspective view showing the state of engagement between the screw rotor and the gate rotor. FIG. 5 is a schematic plan view showing the suction process, compression process, and discharge process of the screw compressor. FIG. 6 is a perspective view showing the flow of low-stage compression refrigerant. FIG. 7 is a perspective view showing the flow of high-stage compression refrigerant. FIG. 8 is a side sectional view illustrating the flow of refrigerant in the compression mechanism. FIG. 9 is an enlarged side cross section illustrating the flow of refrigerant around the first end of the compression mechanism. FIG. 10 is a side sectional view and an enlarged view of a part of the compression mechanism for explaining the seal portion of this embodiment. FIG. 11 corresponds to an enlarged view of FIG. 10 of a screw compressor according to modification 2. FIG. 12 is a diagram corresponding to an enlarged view of FIG. 10 of a screw compressor according to modification 3. FIG. 13 is a diagram corresponding to FIG. 10 of a screw compressor according to modification 4. FIG. 14 is a piping system diagram of a refrigerant circuit to which a screw compressor according to modification 5 is connected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its applications, or its uses. In addition, the configurations of the embodiments, modifications, and other embodiments described below can be combined or partially replaced within the scope of implementing the present invention.

(1) Air conditioner As shown in FIG. 1, the screw compressor (10) of this embodiment is provided in an air conditioner (1) that air-conditions indoor space. The air conditioner (1) is an example of the refrigeration device (1) of the present disclosure. The air conditioner (1) has a refrigerant circuit (2) filled with refrigerant.

The refrigerant circuit (2) has a screw compressor (10), a condenser (3), an expansion valve (4), and an evaporator (5). The refrigerant circuit (2) performs a vapor compression type refrigeration cycle. The arrows in FIG. 1 indicate the direction in which the refrigerant flows. In the refrigeration cycle, heat is radiated from the refrigerant compressed by the screw compressor (10) in the condenser (3). The heat radiated refrigerant is depressurized by the expansion valve (4), evaporated by the evaporator (5), and then sucked into the screw compressor (10).

(2) Screw Compressor The screw compressor (10) compresses refrigerant. The screw compressor (10) sucks in low-pressure gas refrigerant and compresses the sucked gas refrigerant. The screw compressor (10) discharges compressed high-pressure gas refrigerant. The screw compressor (10) of this embodiment is configured to compress refrigerant in two stages.

As shown in FIGS. 2 to 4, the screw compressor (10) includes a casing (11), an electric motor (13), a drive shaft (19), and a compression mechanism (30). In the following, "upper", "lower", "right", and "left" refer to directions when the side of the screw compressor (10) shown in FIG. 2 is viewed from the front.

(2-1) Casing The casing (11) is formed into a horizontally long cylindrical shape. A suction port and a discharge port (not shown) are formed in the casing (11). A low pressure space (S1) and a high pressure space (S2) are formed inside the casing (11). The low-pressure space (S1) is a space through which low-pressure gas refrigerant is sucked into the compression mechanism (30) through the suction port. The high pressure space (S2) is a space into which the high pressure gas refrigerant discharged from the compression mechanism (30) flows. The refrigerant in the high pressure space (S2) flows out of the screw compressor (10) from the discharge port. A cylinder portion (16) is formed within the casing (11). The cylinder portion (16) is formed into a horizontally elongated substantially cylindrical shape. A screw rotor (40), which will be described later, is disposed within the cylinder portion (16).

(2-2) Electric motor The electric motor (13) is housed within the casing (11). The electric motor (13) is arranged at one end inside the casing (11). The electric motor (13) has a stator (14) and a rotor (15). The stator (14) is fixed to the inner wall of the casing (11). The rotor (15) is arranged inside the stator (14). A drive shaft (19) is fixed inside the rotor (15). The rotation speed of the electric motor (13) can be changed. In this example, the electric motor (13) is an inverter-driven electric motor.

(2-3) Drive shaft The drive shaft (19) is arranged inside the casing (11). The drive shaft (19) extends along the longitudinal direction of the casing (11). The drive shaft (19) extends substantially horizontally. The drive shaft (19) is inserted into the cylinder portion (16) along the cylinder axis direction. The drive shaft (19) is arranged so that its axial center coincides with the cylindrical axis center of the cylinder portion (16).

The drive shaft (19) is driven by an electric motor (13). The rotation speed of the drive shaft (19) changes as the rotation speed of the electric motor (13) changes. In other words, the rotation speed of the drive shaft (19) can be changed. The drive shaft (19) connects the electric motor (13) and the compression mechanism (30).

The drive shaft (19) is rotatably supported by a first bearing part (21) and a second bearing part (22) that are fixed within the cylinder part (16). The first bearing portion (21) is arranged at an intermediate portion of the drive shaft (19). The second bearing portion (22) is arranged at the discharge side end of the drive shaft (19) (the end opposite to the electric motor (13)).

The first bearing part (21) is composed of a first bearing (21a) and a first bearing holder (21b). The second bearing portion (22) includes a second bearing (22a) and a second bearing holder (22b). The drive shaft (19) is supported by each bearing holder (21b, 22b) via each bearing (21a, 22a). In the following description, the first bearing (21a) and the second bearing (22a) may be collectively referred to simply as bearings (21a, 22a). Further, the first bearing holder (21b) and the second bearing holder (22b) may be collectively referred to simply as bearing holders (21b, 22b).

The bearing holder (21b, 22b) is formed into a substantially cylindrical shape that surrounds the entire circumference of the bearing (21a, 22a). The outer peripheral surface of the bearing holder is fixed to the inner peripheral surface of the cylinder portion (16). The first bearing holder (21b) and the second bearing holder (22b) are arranged to sandwich the screw rotor (40).

Each of the bearing parts (21) has a cylindrical peripheral wall (21c, 22c). The peripheral wall (21c, 22c) is provided at the outer peripheral edge of the axial end surface of the bearing holder (21b, 22b). The peripheral walls (21c, 22c) are formed along the inner circumferential surface of the cylinder portion (16). Specifically, the peripheral wall (21c, 22c) is arranged between the inner peripheral surface of the cylinder portion (16) and the outer peripheral surface of the end portion (42, 43) of the screw rotor (40). The outer peripheral surface of the peripheral wall (21c, 22c) is fixed to the inner peripheral surface of the cylinder part (16). The inner peripheral surface of the peripheral wall (21c, 22c) is close to the outer peripheral surface of the end portion (42, 43) of the screw rotor (40). The peripheral walls (21c, 22c) of the first bearing part (21) are referred to as first peripheral walls (21c), and the peripheral walls (21c, 22c) of the second bearing part (22) are referred to as second peripheral walls (22c). The first peripheral wall (21c) is an example of the collar (21c) of the present disclosure.

(2-4) Compression mechanism The compression mechanism (30) has one cylinder part (16), one screw rotor (40), two gate rotors (50), and two slide valves (65).

(2-4-1) Cylinder section The cylinder section (16) accommodates the screw rotor (40). A first slit (16a) and a second slit (16b) are formed in the cylinder portion (16). The first slit (16a) and the second slit (16b) are elongated openings extending in the cylinder axis direction. The first slit (16a) and the second slit (16b) are arranged adjacent to each other in the circumferential direction. A gate rotor (50) passes through each of the first slit (16a) and the second slit (16b). Details of the first slit (16a) and the second slit (16b) will be described later.

The cylinder portion (16) is provided with a valve accommodating portion (66) in which the slide valve (65) is accommodated. Two valve housing portions (66) are provided in the circumferential direction of the cylinder portion (16). Each valve housing portion (66) is formed to bulge radially outward from the cylinder portion (16). The outer peripheral wall of the valve accommodating part (66) is a partition wall (66a) that partitions the low pressure space (S1) and the high pressure space (S2), and a partition wall (66a) that extends from the widthwise center position of the partition wall (66a) toward the high pressure space (S2) side. It has a guide wall (66b) extending in the axial direction.

(2-4-2) Screw rotor The screw rotor (40) is arranged inside the cylinder part (16). The screw rotor (40) is a metal member formed into a generally cylindrical shape. The screw rotor (40) is fixed to the drive shaft (19). The screw rotor (40) rotates as the drive shaft (19) rotates. The outer circumferential surface of the screw rotor (40) is close to the inner circumferential surface of the cylinder portion (16).

Of both ends of the screw rotor (40) in the cylinder axis direction, one end is called a first end (42), and the other end is called a second end (43). Both the first end (42) and the second end (43) are formed into a cylindrical shape. The first end (42) is an end on the suction side of the compression chamber (25), which will be described later. The first end (42) is the suction side end (42) of the present disclosure. The second end (43) is the discharge side end of the compression chamber (25).

The first end (42) is arranged adjacent to the first bearing part (21). The second end (43) is arranged adjacent to the second bearing part (22). Hereinafter, the outer circumferential surface of the first end (42) will be referred to as a first outer circumferential surface (42a), and the end surface of the first end (42) will be referred to as a first end surface (42b). Further, the outer circumferential surface of the second end (43) is referred to as a second outer circumferential surface (43a), and the end surface of the second end (43) is referred to as a second end surface (43b).

The first outer circumferential surface (42a) and the second outer circumferential surface (43a) are along the inner circumferential surface of the cylinder portion (16). Specifically, the first outer circumferential surface (42a) is close to the inner surface of the first circumferential wall (21c) of the first bearing section (21), and the second outer circumferential surface (43a) is close to the inner surface of the first circumferential wall (21c) of the second bearing section (22). 2 Close to the inner surface of the peripheral wall (22c).

The first end surface (42b) and the second end surface (43b) are formed as flat surfaces perpendicular to the cylinder axis direction. The first end surface (42b) faces the end surface of the first bearing holder (21b). The second end surface (43b) faces the end surface of the second bearing holder (22b). Specifically, the first end surface (42b) is close to the end surface of the first bearing holder (21b), and the second end surface (43b) is close to the end surface of the second bearing holder (22b).

A plurality of screw grooves (41) extending spirally are formed on the outer peripheral surface of the screw rotor (40). The screw groove (41) extends from the first end (42) to the second end (43) in the axial direction of the screw rotor (40).

(2-4-3) Gate rotor The gate rotor (50) includes a first gate rotor (50a) and a second gate rotor (50b). Each gate rotor (50) has a plurality of gates (53) arranged radially. The gate (53) is inserted through the slits (16a, 16b) of the cylinder portion (16) and engages with the screw groove (41).

Each gate rotor (50) is supported by a gate rotor shaft (58). The gate rotor shaft (58) extends in a direction perpendicular to the axial direction of the drive shaft (19). The gate rotor shaft (58) is housed in a bearing housing (55) defined within the casing (11). The gate rotor shaft (58) is rotatably supported via a ball bearing (56) provided within the bearing housing (55). The gate rotor (50) and the gate rotor shaft (58) are arranged in the gate rotor chamber (18).

The gate rotor chamber (18) is defined within the casing (11) and adjacent to the cylinder portion (16). The gate rotor chamber (18) includes a first gate rotor chamber (18a) and a second gate rotor chamber (18b). A first gate rotor (50a) is arranged in the first gate rotor chamber (18a). A second gate rotor (50b) is arranged in the second gate rotor chamber (18b). The first gate rotor chamber (18a) is configured to supply refrigerant to a first compression chamber (23), which will be described later. The second gate rotor chamber (18b) is configured to supply refrigerant flowing out from the first compression chamber (23) to a second compression chamber (24), which will be described later.

(2-4-4) Slide Valve The slide valve (65) is housed in the valve housing section (66). The slide valve (65) is configured to be slidable in the axial direction of the cylinder portion (16) by a drive mechanism (71) to be described later. The slide valve (65) faces the outer peripheral surface of the screw rotor (40) while being inserted into the valve accommodating portion (66).

The drive mechanism (71) includes a cylinder portion (16), a piston (73), a piston rod (74), an arm (75), a connecting rod (76), and a spring (77). The cylinder portion (16) is formed on the right side wall surface of the fixed plate (29). The piston (73) is loaded into the cylinder section (16). The piston rod (74) has one end fixed to the center of the piston (73) and extends to the left. The arm (75) is connected to the other end of the piston rod (74). The connecting rod (76) connects the arm (75) and the slide valve (65). The spring (77) is provided on the connecting rod (76) so as to bias the arm (75) to the right. The drive mechanism (71) controls the movement of the piston (73) by adjusting the gas pressure acting on the left and right end surfaces of the piston (73), and adjusts the position of the slide valve (65).

The slide valve (65) is a valve that can adjust the position of the screw rotor (40) in the axial direction. This slide valve (65) can be used as an unloading mechanism that changes the operating capacity by returning the refrigerant that is being compressed in the compression chamber (25) to the suction side. Furthermore, the slide valve (65) can be used as a compression ratio adjustment mechanism that adjusts the compression ratio (internal volume ratio) by adjusting the timing of discharging refrigerant from the compression chamber (25).

(2-4-5) Compression chamber In the compression mechanism (30) of this embodiment, the inner peripheral surface of the cylinder part (16), the screw groove (41) of the screw rotor (40), and the two gate rotors (50) ) A compression chamber (25) is formed.

A fixed discharge port (not shown) is formed in the cylinder portion (16), which always communicates with the compression chamber (25) regardless of the position of the slide valve (65). This fixed port is provided to prevent the compression chamber (25) from being in a sealed state so as to avoid liquid compression when the screw compressor (10) is started up or under low load.

The compression chamber (25) includes a first compression chamber (23), which is the lower stage side of two-stage compression, and a second compression chamber (24), which is the higher stage side. The first compression chamber (23) and the second compression chamber (24) are formed by a screw rotor (40) and a gate rotor (50) inside the cylinder part (16). The first compression chamber (23) compresses the refrigerant at the suction pressure introduced into the casing (11) to an intermediate pressure higher than the suction pressure. The second compression chamber (24) compresses the intermediate pressure refrigerant to a discharge pressure (high pressure) higher than the intermediate pressure.

In this embodiment, the low pressure space (S1) communicates with the first compression chamber (23) via the first gate rotor chamber (18a). Low pressure space (S1), first gate rotor chamber (18a), first compression chamber (23), second gate rotor chamber (18b) which is intermediate pressure space, second compression chamber (24), and high pressure space (S2 ) are connected in order from the side with lower refrigerant pressure to the side with higher refrigerant pressure.

The first slit (16a) communicates the low pressure space (S1) and the first gate rotor chamber (18a) with the first compression chamber (23). The second slit (16b) communicates the second gate rotor chamber (18b), which is an intermediate pressure space, with the second compression chamber (24). The first slit (16a) constitutes a first suction port that introduces the low-pressure refrigerant in the low-pressure space (S1) into the first compression chamber (23). The second slit (16b) constitutes a second suction port that introduces the refrigerant in the intermediate pressure space into the second compression chamber (24).

(3) Operation of the compression mechanism In the suction stroke shown in FIG. 5, the shaded compression chamber (25) (strictly speaking, the suction chamber) communicates with the suction side space. The screw groove (41) corresponding to this compression chamber (25) meshes with the gate (53) of the gate rotor (50). When the screw rotor (40) rotates, the gate (53) moves relatively toward the end of the screw groove (41), and the volume of the compression chamber (25) expands accordingly. As a result, refrigerant is sucked into the compression chamber (25).

When the screw rotor (40) further rotates, the compression stroke shown in FIG. 5 is performed. In the compression stroke, the shaded compression chamber (25) is completely closed. That is, the screw groove (41) corresponding to this compression chamber (25) is partitioned off from the suction side space by the gate (53). As the gate (53) approaches the end of the screw groove (41) as the screw rotor (40) rotates, the volume of the compression chamber (25) gradually decreases. As a result, the refrigerant in the compression chamber (25) is compressed.

When the screw rotor (40) further rotates, the discharge stroke shown in FIG. 5 is performed. In the discharge stroke, the shaded compression chamber (25) (strictly speaking, the discharge chamber) communicates with the fixed discharge port via the discharge side end. As the screw rotor (40) rotates and the gate (53) approaches the end of the screw groove (41), the compressed refrigerant is pushed out from the compression chamber (25) through the fixed discharge port and into the discharge side space. It goes down.

(3-1) Two-stage compression Next, the operation of two-stage compression will be explained using FIGS. 6 and 7. The refrigerant sucked into the casing (11) flows into the low pressure space (S1), and is introduced from the low pressure space (S1) into the first gate rotor chamber (18a).

The low-pressure refrigerant in the first gate rotor chamber (18a) is sucked into the first compression chamber (23) through the first slit (16a). The intermediate pressure refrigerant compressed in the first compression chamber (23) flows out of the first compression chamber (23) and flows into the second gate rotor chamber (18b), which is an intermediate pressure space.

The intermediate pressure refrigerant in the second gate rotor chamber (18b) is sucked into the second compression chamber (24) through the second slit (16b). The high-pressure refrigerant compressed in the second compression chamber (24) flows out of the second compression chamber (24) and flows into the high-pressure space (S2), which is the second space. The oil in the refrigerant that has flowed into the high-pressure space (S2) is separated by an oil separator (not shown) and flows out of the casing (11) through the discharge port (10b).

(4) Problems caused by differential pressure between the outside and outside of the compression chamber In a screw compressor having a structure in which two-stage compression is performed in the first compression chamber (23) and the second compression chamber (24) as in this embodiment, the screw rotor The suction side end is required to have a suction cutless structure that seals the inner peripheral surface of the cylinder part and the outer peripheral surface of the screw rotor (corresponding to the first end (42) in this example).

As shown in FIG. 8, the refrigerant sucked into such a screw compressor is sent to a low pressure space (S1), a first gate rotor chamber (18a), a first compression chamber (23), and a second intermediate pressure space. It flows in the order of the gate rotor chamber (18b), the second compression chamber (24), and the high pressure space (S2).

Here, as shown in FIG. 9, the intermediate pressure discharged refrigerant compressed in the first compression chamber (23) flows into the screw rotor (40) before flowing into the second gate rotor chamber (18b). It passes outside the first end (42), which is the suction side end. Since the inside of the first end (42) is at a low pressure due to the refrigerant sucked into the first compression chamber (23), a pressure difference occurs between the outside and inside of the first end (42). Therefore, the intermediate pressure refrigerant outside the first end (42) may flow through the gap between the first end (42) and the cylinder part (16) and flow into the first compression chamber (23) (Fig. 9 dashed line). When the intermediate pressure refrigerant flows into the suction side of the first compression chamber (23), the pressure difference between the suction pressure and the discharge pressure of the refrigerant becomes small in the first compression chamber (23), resulting in a decrease in compression efficiency.

In contrast, in the screw compressor (10) of the present embodiment, the outer circumferential surface (42a) at the first end (42) that is the suction side end or the axial direction at the suction side end (42) A seal portion (80) for suppressing the flow of refrigerant is provided on the first surface (F) facing the first end surface (42b). The seal portion (80) will be specifically explained below.

(5) Seal portion As shown in FIG. 10, the seal portion (80) of this embodiment is provided in the first bearing portion (21). Specifically, the seal portion (80) is provided on the inner peripheral surface (F) of the first peripheral wall (21c). The inner peripheral surface (F) of the first peripheral wall (21c) is an example of the first surface (F) facing the first end (42) of the present disclosure.

The seal portion (80) of this embodiment is a labyrinth seal. Specifically, the first circumferential wall (21c) has a plurality of grooves (81) formed along the entire circumference of its inner circumferential surface (F), which are lined up at regular intervals in the axial direction. be done. The plurality of grooves (81) form an expansion chamber. For example, the intermediate pressure refrigerant flows into the gap (flow path) between the first end (42) and the first bearing holder (21b) and flows toward the first compression chamber (23). ) and expands (depressurizes), then flows into the flow path. This refrigerant flows into the next groove (81) and is expanded (depressurized), and then flows into the flow path. In this way, the intermediate pressure refrigerant repeatedly flows into the flow path from the expansion chamber multiple times. When the refrigerant flows from the expansion chamber to the flow path, its ease of flow is suddenly inhibited, resulting in flow resistance and pressure loss. The occurrence of pressure loss can suppress the intermediate refrigerant from flowing into the first compression chamber (23).

(6) Features (6-1) Feature 1
In the screw compressor (10) of the present embodiment, the first end (42) (suction side end) of the screw rotor (40) has a first outer circumferential surface (42a) that is the inner circumferential surface of the cylinder portion (16). It is formed into a cylindrical shape along the A seal portion (80) for suppressing the flow of refrigerant is provided on the first surface (F) facing the first end portion (42).

The intermediate pressure refrigerant discharged from the first compression chamber (23) flows through the space outside the first end (42) when moving to the inlet of the second compression chamber (24). The space inside the first end (42) is the first compression chamber (23) and forms a space into which low-pressure refrigerant is sucked, so a pressure difference is generated across the first end (42). According to the present embodiment, the seal portion (80) is provided on the first surface (F) that the first end (42) faces, so that the intermediate pressure refrigerant can flow between the first end (42) and the first surface. (F) can be suppressed from being distributed between. As a result, a sufficient level differential pressure within the compression chamber can be ensured, and a decrease in the capacity of the screw compressor can be suppressed.

(6-2) Feature 2
The screw compressor (10) of this embodiment includes a first bearing part (21) fixed within the cylinder part (16) and supporting the drive shaft (19). The first bearing portion (21) is arranged adjacent to the first end portion (42), and the seal portion (80) is provided on the first bearing portion (21).

According to this embodiment, the first surface (F) of the first end (42) is located on the first bearing holder (21b), and the seal portion (80) is provided on the first bearing holder (21b). This can suppress the refrigerant from flowing between the first bearing holder (21b) and the first end (42). In this way, the first bearing portion (21) has a bearing function for the drive shaft (19) and a sealing function for suppressing the flow of refrigerant. In addition, since the seal part (80) can be provided before installing the first bearing holder (21b) into the cylinder part (16), it is easier to install the seal part (80) than if the seal part (80) is provided inside the cylinder part (16). The seal portion (80) can be easily formed.

(6-3) Feature 3
In the screw compressor (10) of the present embodiment, the first bearing portion (21) has a first peripheral wall (21c) disposed between the inner surface of the cylinder portion (16) and the outer peripheral surface of the first end portion (42). ) (flange portion), and the seal portion (80) is provided on the first peripheral wall (21c).

According to this embodiment, the seal portion (80) can be provided on the inner peripheral surface of the first peripheral wall (21c). Moreover, the inner peripheral surface of the first peripheral wall (21c) and the first end surface (42b) can increase the contact area between the first bearing holder (21b) and the first end (42). By increasing this area, the flow path through which the refrigerant flows, which is the gap between the first bearing holder (21b) and the first end (42), can be lengthened. The effect of suppressing the flow of refrigerant can be increased.

(6-4) Feature 4
In the screw compressor (10) of the present embodiment, the compression chamber (25) includes a first compression chamber (23) that compresses the suction pressure fluid introduced into the casing (11) to an intermediate pressure, and a first compression chamber (23) that compresses the fluid at the suction pressure introduced into the casing (11) to an intermediate pressure. and a second compression chamber (24) for compressing the fluid to the discharge pressure.

According to this embodiment, a part of the intermediate pressure fluid discharged from the first compression chamber (23) passes through the suction side end (42) again during the process of moving to the second compression chamber (24). Inhalation into the first compression chamber (23) can be suppressed.

(6-5) Feature 5
In the screw compressor (10) of this embodiment, the seal portion (80) is configured with a labyrinth seal. Thereby, the seal portion (80) can be configured relatively easily.

(7) Modification The above embodiment may have the following configuration. Below, configurations different from those of the above embodiment will be explained.

(7-1) Modification example 1
The seal portion (80) in this example has a surface texture (surface texturing). The surface texture is formed on the inner peripheral surface of the first peripheral wall (21c). In the surface texture, Rayleigh steps that generate positive pressure and reverse Rayleigh steps that generate negative pressure are formed as appropriate. The Rayleigh step can suppress friction between the inner peripheral surface of the first peripheral wall (21c) and the outer peripheral surface of the first end (42). In the reverse Rayleigh step, the refrigerant flowing into the gap between the inner peripheral surface of the first peripheral wall (21c) and the outer peripheral surface of the first end (42) can be sucked back. In this example, a reverse Rayleigh step may be adopted so that the intermediate pressure refrigerant does not flow into the first compression chamber (23).

(7-2) Modification example 2
As shown in FIG. 11, the seal portion (80) of this example is formed on the surface facing the first end surface (42b) of the first bearing holder (21b). The surface facing the first end surface (42b) is an example of the first surface (F) of the present disclosure. For example, when the seal portion (80) is a labyrinth seal, a plurality of concave grooves (81) are formed on the first end surface (42b) concentrically around the cylindrical axis of the first bearing holder (21b). are formed at intervals of .

(7-3) Modification example 3
As shown in FIG. 12, the seal portion (80) of this example is formed on the inner peripheral surface of the first peripheral wall (21c) and the first end surface (42b) of the first bearing holder (21b). By providing the seal portions (80) on both surfaces facing the first end (42) in this manner, the refrigerant is prevented from flowing into the gap between the first end (42) and the bearing holder (21b, 22b). It can definitely be suppressed.

(7-4) Modification example 4
As shown in FIG. 13, the first bearing part (21) of this example does not have the first bearing holder (21b). In this case, the first bearing (21a) is embedded inside the cylinder part (16), and a cylinder end face (26) facing the first end face (42b) is formed inside the cylinder part (16). There is. In this example, the first surface (F) of the present disclosure is the inner peripheral surface of the cylinder part (16) facing the first outer peripheral surface (42a), and the cylinder end surface (26) facing the first end surface (42b). be. In this example, the seal portion (80) is provided on the inner circumferential surface of the cylinder portion (16) facing the first outer circumferential surface (42a). The seal portion (80) may be provided on the cylinder end surface (26) opposite to the end surface of the first end (42). Further, the seal portion (80) is attached to both the inner peripheral surface of the cylinder portion (16) facing the first outer peripheral surface (42a) and the cylinder end surface (26) facing the end surface of the first end portion (42). may be provided.

(7-5) Modification example 5
As shown in FIG. 14, the refrigerant circuit (2) of this example includes an economizer circuit (90). The economizer circuit (90) of this example supplies intermediate pressure refrigerant to the compression chamber (25). The arrows in FIG. 14 indicate the direction in which the refrigerant flows.

A gas-liquid separation space (S3) in which the refrigerant is separated into gas and liquid is formed within the casing (11) of this example. The gas-liquid separation space (S3) is adjacent to the suction side of the compression chamber (25). The high pressure space (S2) within the casing (11) is adjacent to the discharge side of the compression chamber (25). A refrigerant suction port is provided on the suction side of the compression chamber (25). The screw compressor (10) of this example is configured in a single stage.

In the refrigerant circuit (2) of this example, the inflow side of the condenser (3) communicates with the high pressure space of the screw compressor (10). The outflow side of the condenser (3) communicates with the gas-liquid separation space (S3) of the screw compressor (10). A first expansion valve (4a) is provided between the condenser (3) and the gas-liquid separation space (S3).

The inflow side of the evaporator (5) communicates with the gas-liquid separation space (S3) of the screw compressor (10). The outflow side of the evaporator (5) communicates with the suction side of the compression chamber (25) of the screw compressor (10). A second expansion valve (4b) is provided between the gas-liquid separation space (S3) and the evaporator (5).

The economizer circuit (90) communicates the gas-liquid separation space (S3) and the compression chamber (25). In the economizer circuit (90), the gas phase intermediate pressure refrigerant in the gas-liquid separation space (S3) flows into the intermediate pressure space in the compression chamber (25). A flow rate control valve (91) is connected to the economizer circuit (90). The flow control valve (91) adjusts the flow rate of refrigerant flowing into the economizer circuit (90).

In the configuration of the screw compressor (10) of this example, the compression chamber (25) is adjacent to the gas-liquid separation space (S3) on its suction side. Therefore, the seal part (80) allows the intermediate pressure refrigerant in the gas-liquid separation space (S3) to flow through the gap between the first end (42) of the screw rotor (40) and the cylinder part (16) into the compression chamber. (25).

(8) Other Embodiments In the above embodiment and each modification, the seal portion (80) may also be provided on the second bearing holder (22b). For example, the seal portion (80) may also be provided on the inner peripheral surface of the second peripheral wall (22c).

In the above embodiment, the first bearing holder (21b) does not need to have the first peripheral wall (21c). In this case, the first surface (F) of the present disclosure includes the inner peripheral surface of the cylinder part (16) facing the first outer peripheral surface (42a) and the end surface of the bearing holder (21b, 22b) facing the first end surface (42b). It is. In this case, the seal portion (80) is attached to the inner peripheral surface of the cylinder portion (16) facing the first outer peripheral surface (42a), the end surface of the bearing holder (21b, 22b) facing the first end surface (42b), or both. provided.

In the above embodiment and each modification, the seal portion (80) only needs to be able to suppress the flow between the inside (compression chamber) of the first end (42) and the space outside the first end (42); It may be configured to suppress the distribution of either one.

There is no particular limitation on the structure of the labyrinth of the seal portion (80). The labyrinth may be an axial labyrinth, a radial labyrinth, an aligned labyrinth, or the like.

The refrigeration device (1) may be applied to a water heater, a chiller unit, or a cooling device that cools the air inside the refrigerator.

Although the embodiments and modifications have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or replaced as appropriate, as long as the functionality of the object of the present disclosure is not impaired. The descriptions of "first", "second", etc. mentioned above are used to distinguish the words to which these descriptions are given, and do not limit the number or order of the words. .

As explained above, the present disclosure is useful for screw compressors and refrigeration equipment.

1 Air conditioner (refrigeration equipment)
10 Screw compressor 11 Casing 13 Electric motor 16 Cylinder section 19 Drive shaft 21 First bearing section (bearing section)
21c 1st peripheral wall (brim part)
23 Compression chamber 24 First compression chamber 25 Second compression chamber 40 Screw rotor 41 Screw groove 42 First end (suction side end)
50 Gate rotor 53 Gate 80 Seal part F 1st surface (inner peripheral surface)

Claims

a casing (11) having a cylinder part (16) therein;
an electric motor (13) disposed within the casing (11);
a drive shaft (19) connected to the electric motor (13) and driven to rotate;
a screw rotor (40) disposed within the cylinder portion (16) and connected to the drive shaft (19);
a gate rotor (50) having a gate (53) that meshes with the screw groove (41) of the screw rotor (40);
A screw compressor in which a compression chamber is formed by the screw rotor (40) and the gate (53) inside the cylinder part (16),
The suction side end (42) of the screw rotor (40) is formed in a cylindrical shape so that the outer peripheral surface (42a) follows the inner peripheral surface of the cylinder part (16),
A first surface (F) opposite to the outer circumferential surface (42a) of the suction side end (42) or the first axial end surface (42b) of the suction side end (42) is configured to allow fluid to flow therethrough. A screw compressor characterized by being provided with a sealing part (80) for suppressing.
a bearing part (21) fixed within the cylinder part (16) and supporting the drive shaft (19);
The bearing part (21) is arranged adjacent to the suction side end part (42),
The screw compressor according to claim 1, wherein the seal portion (80) is provided in the bearing portion (21).
3. The seal portion (80) is provided on the first surface (F) of the bearing portion (21) opposite to the axial end surface of the suction side end portion (42). screw compressor.
The bearing portion (21) has a flange portion (21c) disposed between the inner surface of the cylinder portion (16) and the outer circumferential surface (42a) of the suction side end portion (42),
The screw compressor according to claim 2 or 3, wherein the seal portion (80) is provided in the collar portion (21c).
The gate rotor (50) has a first gate rotor (50a) and a second gate rotor (50b),
The compression chamber (25) is
a first compression chamber (23) formed by the first gate rotor (50a) and the screw rotor (40) and compressing fluid at suction pressure introduced into the casing (11) to an intermediate pressure;
Claims 1 to 3, further comprising a second compression chamber (24) formed by the second gate rotor (50b) and the screw rotor (40) and compressing the fluid at the intermediate pressure to a discharge pressure. 4. The screw compressor according to any one of 4.
The screw compressor according to any one of claims 1 to 5, wherein the seal portion (80) is comprised of a labyrinth seal.
The screw compressor according to any one of claims 1 to 5, wherein the seal portion (80) is configured with a surface texture.
A refrigeration system comprising the screw compressor according to any one of claims 1 to 7.