CN110714801B

CN110714801B - Expander and fluid circulation system comprising an expander

Info

Publication number: CN110714801B
Application number: CN201810763200.0A
Authority: CN
Inventors: 束宏飞; 杨东辉
Original assignee: Gulun Environmental Technology Suzhou Co ltd
Current assignee: Gulun Environmental Technology Suzhou Co ltd
Priority date: 2018-07-12
Filing date: 2018-07-12
Publication date: 2024-05-31
Anticipated expiration: 2038-07-12
Also published as: CN110714801A

Abstract

The present disclosure relates to an expander that includes a housing, an expansion mechanism, an exhaust pipe, an oil sump, and a lubricant drain passage. An expansion mechanism is disposed within the housing and is configured to expand the high pressure fluid into a low pressure fluid. The exhaust pipe is configured to discharge low pressure fluid out of the expander and includes an end fitting in the first opening of the housing and having an exhaust port, wherein the low pressure fluid enters the exhaust pipe via the exhaust port. An oil sump is located within the housing and stores a lubricant. The lubricant drain passage is configured to drain lubricant in the sump into the exhaust pipe and/or an external system line in communication with the exhaust pipe, and the lubricant drain passage includes an inlet end having an inlet and an outlet end having an outlet, wherein the inlet is at a predetermined oil level in the sump, and lubricant entering the lubricant drain passage is drained into the exhaust pipe and/or the external system line via the outlet. The present disclosure also relates to a fluid circulation system including the expander.

Description

Expander and fluid circulation system comprising an expander

Technical Field

The present disclosure relates to an expander and a fluid circulation system including the expander.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

An expander is a device that utilizes high-pressure fluid to expand into low-pressure fluid to output mechanical work or electric work outwards. One common expander is a scroll expander. The expansion mechanism of the scroll expander comprises an orbiting scroll member and a non-orbiting scroll member. The orbiting and non-orbiting scroll members engage one another to form a series of expansion chambers of progressively increasing volume between their vanes, thereby causing the high pressure fluid to become the low pressure fluid. A driving torque is generated during the expansion of the fluid, for example, to rotate a shaft to output mechanical or electrical work.

Typically, the expander also includes an oil sump in which a lubricant is stored, the lubricant being provided to each associated movable component (e.g., main bearing) to lubricate it. In addition, in a system including an expander, lubricant may enter the expansion mechanism of the expander with the high-pressure working fluid and exit the expander with the expanded low-pressure working fluid, thereby circulating in the system. The lubricant circulating in the system may lubricate the expansion mechanism. In particular, in the case of the low-pressure side expander, since the lubricant in the oil sump is in a low-pressure environment and is difficult to supply to the expansion mechanism, the expansion mechanism is mainly lubricated by the lubricant circulating in the system.

However, the lubricant in the system, when flowing through the various components within the expander, may separate from the working fluid and flow into the sump within the expander. In this way, an excessive amount of lubricant in the sump may result, and correspondingly, an excessive amount of lubricant circulated in the system. This can lead to deterioration of lubrication of the various relevant movable components in the expander, in particular the expansion mechanism, thereby affecting the normal operation of the expander and reducing the expansion efficiency.

Therefore, there is a need for an expander that can improve lubricant distribution and maintain good lubrication.

Disclosure of Invention

It is an object of one or more embodiments of the present invention to provide an expander that is capable of improving lubricant distribution and maintaining good lubrication.

It is a further object of one or more embodiments of the present invention to provide an expander that is simple in construction and low in cost.

According to one aspect of the present invention, there is provided an expander comprising a housing, an expansion mechanism, an exhaust pipe, an oil sump, and a lubricant drain passage. An expansion mechanism is disposed within the housing and is configured to expand the high pressure fluid into a low pressure fluid. The exhaust pipe is configured to discharge low pressure fluid out of the expander and includes an end fitting in the first opening of the housing and having an exhaust port, wherein the low pressure fluid enters the exhaust pipe via the exhaust port. An oil sump is located within the housing and stores a lubricant. The lubricant drain passage is configured to drain lubricant in the sump into the exhaust pipe and/or an external system line in communication with the exhaust pipe, and the lubricant drain passage includes an inlet end having an inlet and an outlet end having an outlet, wherein the inlet is at a predetermined oil level in the sump, and lubricant entering the lubricant drain passage is drained into the exhaust pipe and/or the external system line via the outlet.

According to the above-described expander, since the lubricant discharge passage for discharging the excessive lubricant from the oil pool into the exhaust pipe is provided, it is possible to ensure that the amount of lubricant in the oil pool is not excessive while avoiding that the lubricant entering the system via the exhaust pipe is not too small, thereby ensuring that the expansion mechanism is well lubricated. In addition, the present invention utilizes the Bernoulli effect (i.e., a pressure difference caused by a difference in flow velocity of the working fluid itself) to discharge the lubricant from the oil pool to the exhaust pipe, and/or utilizes a pressure drop caused by a loss of resistance of the pipe to discharge the oil pool to the exhaust pipe, so that the structure of the expander of the present invention is simplified.

In other examples of the present disclosure, the lubricant drain passage is provided by a separate oil drain pipe. In this way, modifications or processing of certain structures of the expander can be avoided.

In other examples of the disclosure, the oil drain tube is secured to an inner wall of the housing. Thus, the structure of the expander can be compact, so that the occupied space is reduced.

In other examples of the present disclosure, the exhaust pipe is provided with an orifice in which an outlet end of the exhaust pipe is fitted.

In other examples of the present disclosure, the orifice of the exhaust pipe is disposed proximate to an exhaust port of an end of the exhaust pipe, or a distance between the orifice and the exhaust port is at least a minimum predetermined distance. When the pressure difference between the pressure at the orifice of the exhaust pipe and the pressure at the inlet of the exhaust pipe is sufficient to suck the lubricant at the predetermined oil level into the exhaust pipe, the orifice of the exhaust pipe is disposed close to the exhaust port, which can make the structure of the expander more compact.

On the other hand, the orifice of the exhaust pipe may be at a distance from the exhaust port, and the longer the distance, the lower the pressure at the orifice due to the pressure drop, and thus the greater the pressure difference between the orifice of the exhaust pipe and the inlet of the exhaust pipe. The minimum predetermined distance between the orifice of the exhaust pipe and the exhaust port may be determined from the minimum pressure differential that draws lubricant from the sump into the exhaust pipe. Thus, the orifice of the exhaust pipe may be positioned at a position at which the distance from the exhaust port is equal to or greater than the minimum predetermined distance.

In other examples of the present disclosure, a second opening is further provided on the housing, and an inlet end of the oil drain pipe is fitted in the second opening.

In other examples of the present disclosure, the second opening is positioned directly below the first opening in a vertical direction. In other examples of the present disclosure, the exhaust pipe extends toward a horizontal plane at which the second opening is located to reduce a height difference between the orifice and the second opening. In other examples of the present disclosure, the oil drain pipe is disposed in a horizontal direction. By reducing the length of the drain pipe or by reducing the height difference between the orifice of the drain pipe and the inlet of the drain pipe, it is facilitated to suck lubricant from the sump into the drain pipe.

In other examples of the present disclosure, the lubricant drain channel is defined by a portion of the housing and a plate secured to the portion of the housing. In other examples of the present disclosure, the plate has an arcuate shape. In this way, no additional machining or modification of the expander housing is required, and no additional installation space is required.

In other examples of the present disclosure, the lubricant drain channel is a hole disposed within the housing. For this example, only the process of drilling the housing and the like is required, and no additional member is required, so that the number of parts is reduced, and the assembly process is simplified.

In other examples of the present disclosure, the lubricant drain channel extends substantially linearly.

In other examples of the present disclosure, the outlet of the lubricant drain channel is substantially flush with the wall of the exhaust pipe or protrudes into the interior of the exhaust pipe; and/or the outlet of the lubricant drain channel is oriented substantially parallel to the direction of flow of fluid within the exhaust pipe, or obliquely or vertically along the direction of flow.

In other examples of the present disclosure, the inlet and/or outlet ends of the lubricant drain channels are linear or curved.

In other examples of the present disclosure, the lubricant discharge passage is provided with: a one-way valve that allows fluid to flow from the oil sump into the exhaust pipe but prevents backflow of fluid from the exhaust pipe to the oil sump; and/or a pump for pumping lubricant in the sump into the exhaust pipe.

In other examples of the present disclosure, the expander is a low pressure side expander.

According to another aspect of the present invention, there is provided a fluid circulation system including the above-described expander.

In other examples of the present disclosure, the fluid circulation system further comprises: a condenser; a first exhaust pipe forming part of the external system piping, the first exhaust pipe connecting the expander to an inlet of the condenser; and a second exhaust pipe forming part of the external system pipe, the second exhaust pipe being connected to an outlet of the condenser. The outlet end of the lubricant drain passage is connected to the first exhaust pipe or the second exhaust pipe. The fluid circulation system can solve the problem of insufficient lubrication of the expansion mechanism caused by low circulation rate of the lubricant.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the particular examples and embodiments described in this section are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

Drawings

The drawings described in this section are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a longitudinal cross-sectional view of an exemplary scroll expander.

Fig. 2a is a longitudinal sectional view of a scroll expander according to an embodiment of the present invention.

Fig. 2b is an external schematic view of the scroll expander of fig. 2 a.

Fig. 2c is an enlarged schematic view of a portion of the exhaust pipe of the scroll expander of fig. 2 a.

FIG. 2d is an enlarged schematic view of a portion of the inlet end of the oil discharge tube of the scroll expander of FIG. 2 a.

Fig. 3 is a longitudinal sectional view of a scroll expander according to another embodiment of the present invention.

Fig. 4 is a longitudinal sectional view of a scroll expander according to yet another embodiment of the present invention.

Fig. 5 is an external view schematically showing a scroll expander according to another embodiment of the present invention.

Fig. 6 is a longitudinal sectional view of a scroll expander according to yet another embodiment of the present invention.

Fig. 7 is a longitudinal sectional view of a scroll expander according to another embodiment of the present invention.

Fig. 8a is a schematic diagram showing a variation of the outlet end of the oil drain pipe.

Fig. 8b is a schematic diagram showing another variation of the outlet end of the oil drain pipe.

Fig. 9a is a schematic diagram showing a modification of the inlet end of the oil discharge pipe.

Fig. 9b is a schematic diagram showing another variation of the inlet end of the oil drain pipe.

Fig. 10 is a schematic diagram of a system including an expander according to an embodiment of the present invention.

Detailed Description

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

The basic construction and principles of the scroll expander 10' will be described below with reference to the accompanying drawings.

As shown in fig. 1, a scroll expander (hereinafter also referred to as an expander) 10' includes a generally cylindrical housing 12, a top cover 14 provided at one end of the housing 12, and a bottom cover 16 provided at the other end of the housing 12. The housing 12, top cover 14, and bottom cover 16 form an enclosure for the scroll expander 10' having a closed space.

The scroll expander 10' further includes a partition 15 disposed between the top cover 14 and the housing 12 to divide the interior space of the expander into a high pressure side (also referred to as a high pressure space) and a low pressure side (also referred to as a low pressure space). The diaphragm 15 and the top cover 14 form a high pressure side therebetween, and the diaphragm 15, the housing 12 and the bottom cover 16 form a low pressure side therebetween. An intake pipe 17 for introducing a high-pressure fluid (also referred to as a working fluid) is provided on the high-pressure side, and an exhaust pipe 18 for exhausting the expanded low-pressure fluid is provided on the low-pressure side.

The scroll expander 10' further includes an expansion mechanism formed by the fixed scroll member 80 and the movable scroll member 70. The orbiting scroll member 70 is capable of translational movement relative to the non-orbiting scroll member 80 (i.e., the central axis of the orbiting scroll member 70 rotates about the central axis of the non-orbiting scroll member 80, but the orbiting scroll member 70 itself does not rotate about its central axis). The translational rotation is achieved by, for example, an oldham ring (not shown) disposed between the fixed scroll member 70 and the orbiting scroll member 80.

Orbiting scroll member 70 includes an end plate 72, a hub 74 formed on one side of the end plate, and spiral vanes 76 formed on the other side of the end plate. The non-orbiting scroll member 80 includes an end plate 82, a spiral vane 86 formed at one side of the end plate, and an inlet 88 formed at a substantially central position of the end plate. A series of expansion chambers are formed between the spiral vane 86 of the fixed scroll member 80 and the spiral vane 76 of the movable scroll member 70, the volumes of which gradually increase when moving from the radially inner side to the radially outer side.

The radially innermost expansion chamber is adjacent the inlet 88 and is at substantially the same suction pressure as the incoming high pressure fluid, and is thus also referred to as a high pressure chamber. The radially outermost expansion chamber is at substantially the same discharge pressure as the low pressure fluid to be discharged from the expansion mechanism, and is thus also referred to as a low pressure chamber. The expansion chamber between the high pressure chamber and the low pressure chamber is between the suction pressure and the discharge pressure and is thus also referred to as the medium pressure chamber.

The high pressure fluid enters the high pressure side within the housing of the expander 10' via the inlet pipe 17 and then enters the expansion mechanism via the inlet 88. The high pressure fluid entering the expansion mechanism is expanded through a series of expansion chambers of progressively increasing volume and becomes a low pressure fluid. The low pressure fluid is discharged to the low pressure side within the housing of the expander 10' and then discharged out of the expander 10' via an exhaust pipe 18 connected to the housing of the expander 10'.

The expander 10' further includes a main bearing housing 40. The main bearing housing 40 is fixed relative to the housing 12 by suitable fastening means. An end plate 72 of orbiting scroll member 70 is supported by main bearing housing 40.

The expander 10' may also include a rotating shaft (which may also be referred to as an output shaft) 30. The rotary shaft 30 is rotatably supported by a main bearing 44 provided in the main bearing housing 40. One end of the rotation shaft 30 is provided with an eccentric crank pin 36. The hub 74 of the orbiting scroll member 70 drives the crank pin 36 of the rotating shaft 30, thereby rotating the rotating shaft 30. When the expander 10' is operated, a driving torque is generated during the expansion of the fluid by the expansion mechanism, and the rotation shaft 30 is driven to rotate to output mechanical work or electric work.

The expander 10' may also include a generator 20 comprised of a stator 22 and a rotor 24. The stator 22 is fixed to the housing 12. The rotor 24 is disposed between the stator 22 and the rotary shaft 30. The rotor 24 is fixed to the outer circumferential surface of the rotation shaft 30 to rotate together with the rotation shaft 30 when the expander 10' is operated, thereby enabling the generator 20 to generate electricity.

The expander 10' may further include an oil sump 90, with lubricant (oil) stored in the oil sump 90. As shown, the oil pool 90 is located at the bottom of the housing of the expander 10', i.e., at the bottom cover 16. The rotating shaft 30 is provided with a bore (not shown) extending along the longitudinal axis of the rotating shaft and optionally with a radially extending bore (not shown). When the rotation shaft 30 rotates, the lubricant B is supplied to a movable member such as a bearing via a hole of the rotation shaft 30. A very small portion of the lubricant B1 after lubrication of the movable components will exit the expander 10' with the working fluid via the exhaust pipe 18, while the majority of the lubricant B2 will be returned to the sump 90. The circulation path of the lubricant supplied from the oil pool 90 is schematically shown with a dotted arrow in fig. 1, and is referred to as an expander internal circulation path for convenience of description.

Further, the lubricant a is mixed in the high-pressure fluid introduced into the expander 10' via the intake pipe 17. Lubricant a enters the expansion mechanism with the high-pressure fluid, thereby lubricating the fixed scroll member 80 and the movable scroll member 70 constituting the expansion mechanism. Most of the lubricant A1 will flow into the sump 90 as the working fluid exits the expander 10' via the exhaust pipe 18, while a small portion of the lubricant A2 is separated from the working fluid. The circulation path of the lubricant supplied from the outside with the high-pressure fluid is schematically shown with solid arrows in fig. 1, and is referred to as a system circulation path for convenience of description.

Typically, the amount of lubricant A2 is greater than the amount of lubricant B1. Thus, after a period of operation of the expander 10', the amount of lubricant in the sump 90 is increasing, while the amount of lubricant discharged into the system comprising the expander via the exhaust pipe 18 is decreasing. Therefore, when the amount of lubricant entering the expander 10' via the intake pipe 17 with the high-pressure fluid is too small, insufficient lubrication of the expansion mechanism may be caused, thereby causing the expansion mechanism to wear seriously, reducing reliability, or even failing.

To solve this problem, the inventors have provided a lubricant discharge passage 100 in the expander to discharge the lubricant in the oil sump into the exhaust pipe by the pressure difference between the exhaust pipe and the oil sump according to the bernoulli effect.

Fig. 2a to 2d illustrate a scroll expander 10 according to an embodiment of the present invention. The scroll expander 10 is different from the scroll expander 10' described above in that it further includes an oil discharge pipe 50 for discharging the lubricant in the oil pool into the exhaust pipe, the oil discharge pipe 50 providing the lubricant discharge passage 100 described above. The same components of the scroll expander 10 as those of the scroll expander 10' described above are denoted by the same reference numerals, and the description will not be repeated.

As shown in fig. 2a to 2d, the scroll expander 10 further includes an oil discharge pipe 50. The oil discharge pipe 50 includes an inlet end 53 connected to the housing of the expander 10 and an outlet end 51 connected to the exhaust pipe 18. The inlet end 53 of the oil drain pipe 50 has an inlet 532. The inlet 532 of the oil drain pipe 50 is positioned substantially at a predetermined oil level so as to drain the lubricant reaching the predetermined oil level into the exhaust pipe 18. In this way, the lubricant in the oil pool 90 can be prevented from exceeding the predetermined oil level, i.e., the amount of lubricant in the oil pool 90 can be prevented from being excessive. The predetermined oil level may be determined according to the operating condition of the expander, the lubrication condition of the expansion mechanism, and the like. The outlet end 51 of the oil drain pipe 50 has an outlet 511, and the lubricant in the oil drain pipe 50 is discharged into the exhaust pipe 18 via the outlet 511.

The housing 12 of the scroll expander 10 is provided with a first opening 121, and the end 182 of the exhaust pipe 18 is fitted in the first housing opening 121. The end 182 of the exhaust pipe 18 has an exhaust port 181 that is open to the interior of the scroll expander 10 such that low pressure fluid within the scroll expander 10 enters the exhaust pipe 18 via the exhaust port 181. The first housing opening 121 of the housing 12 forms a first opening of the outer shell of the scroll expander 10 for fitting the exhaust pipe 18.

A second housing opening 122 is also provided in the housing 12 of the scroll expander 10 and a bottom cover opening 162 is provided in the bottom cover 16, wherein the bottom cover opening 162 is in fluid communication with the second housing opening 122. The second housing opening 122 and the bottom cover opening 162 form a second opening of the housing of the scroll expander 10 for fitting the oil drain pipe 50. The inlet end 53 of the oil drain pipe 50 fits in the second opening of the housing, in particular in the example shown in fig. 2d in the second housing opening 122.

In the illustrated example, the inlet end 53 of the oil drain pipe 50 is connected to the housing 12 at an overlapping portion with the bottom cover 16. However, it should be understood that the inlet end 53 of the oil drain tube 50 may be connected to a portion of the housing 12 that does not overlap the bottom cover 16, for example, connected only to the housing 12 or connected only to the bottom cover 16. Of course, the position of the inlet end 53 of the oil drain pipe 50 is determined mainly based on a predetermined oil level.

The exhaust pipe 18 may be provided with an orifice 183, and the outlet end 51 of the exhaust pipe 50 is fitted in the orifice 183. In the example shown in fig. 2c, an orifice 183 is provided in the end 182 of the exhaust pipe 18, i.e. near the exhaust port 181. However, it should be understood that the location of the orifice 183 may vary depending on the actual needs.

According to the Bernoulli effect, at the end 182 of the exhaust duct 18, the flow rate of the working fluid is greater, and therefore the pressure P1 is smaller; whereas at the second opening of the housing the flow rate of the working fluid is close to zero and thus the pressure P2 is greater. When the oil level of the sump 90 passes through the second opening of the housing, the pressure differential between P2 and P1 causes lubricant within the sump 90 to enter the drain pipe 50 and thus into the drain pipe 18. The expander according to the present invention can optimize the distribution or circulation path of the lubricating oil by a simple structure.

Thus, the greater the pressure differential between P2 and P1, the more advantageous the lubricant is drawn from the sump 90 into the exhaust pipe 18. As shown in fig. 3, the orifice 183 may be disposed at a position remote from the exhaust port 181. Working fluid flows from the exhaust port 181 to the orifice 183, further creating a pressure drop due to loss of flow resistance. In this way, the pressure at the orifice 183 is less than the pressure at the vent 181, thereby further increasing the pressure differential between the inlet end 53 and the outlet end 51 of the oil drain pipe 50. The pressure drop between the orifice 183 and the exhaust port 181, and thus the predetermined distance between the orifice 183 and the exhaust port 181, may be determined based on the desired pressure differential. Therefore, in the case where the distance between the orifice 183 and the exhaust port 181 is equal to or greater than the predetermined distance, it is possible to ensure that the lubricant can be sucked from the oil pool 90 into the exhaust pipe 18.

Fig. 4 is a longitudinal sectional view of a scroll expander according to yet another embodiment of the present invention. In the scroll expander shown in fig. 4, the ability to draw lubricant from the sump 90 into the exhaust pipe 18 is further enhanced by reducing the difference in height between the outlet end 51 and the inlet end 53 of the exhaust pipe 50, i.e., by reducing the fluid potential energy that the pressure differential is to overcome. As shown, the oil drain pipe 50 is disposed in a horizontal direction, i.e., in a horizontal plane of a predetermined oil level. In other words, the difference in height between the outlet end 51 and the inlet end 53 of the oil discharge pipe 50 is zero. For this purpose, the exhaust pipe 18 extends or bends downward, i.e., toward the level of the predetermined oil level, thereby causing the orifice 183 to be in the level of the predetermined oil level. In the example of fig. 4, the orifice 183 is far from the exhaust port 181 compared to the example of fig. 2a, and thus a larger pressure drop may be created between the orifice 183 and the exhaust port 181.

Further, in the example of fig. 4, the oil drain pipe 50 may extend linearly, thereby having a short length. In this way, it is advantageous to reduce the flow resistance of the lubricant in the oil discharge pipe 50, and thus the pressure difference for overcoming the flow resistance can be reduced. Another way of reducing the oil drain pipe is shown in fig. 2b, in which the second housing opening 122 of the cylindrical housing 12 (the second opening of the outer housing) is positioned below the first housing opening 121 (the first opening of the outer housing) in the vertical direction. The difference in height between the first opening and the second opening of the housing may be determined according to the flow rate of the working fluid, the operating condition of the expander, the lubrication condition of the movable member, and the like.

However, it should be understood that the positions of the first and second openings of the housing may be changed according to actual needs, i.e., the structure of the oil discharge pipe 50 may be changed according to the positions of the first and second openings. For example, as shown in fig. 5, the first housing opening 121 of the cylindrical housing 12 is located above the second housing opening 122 while being spaced apart by a certain distance in the circumferential direction of the cylindrical housing 12, thereby avoiding, for example, the lower bearing housing (particularly, avoiding the support frame that supports the lower bearing housing main body).

In the example of fig. 2a to 5, the oil drain pipe 50 is arranged substantially outside the expander. However, it should be understood that the oil drain pipe 50 may also be disposed inside the expander. As shown in fig. 6, the oil discharge pipe 50 is fixed to the inner wall of the casing of the expander. In the example of fig. 6, the second opening of the housing for mounting the inlet end 53 of the oil drain pipe 50 may be omitted. The outlet end 51 of the exhaust pipe 50 may extend into the exhaust pipe 18 or may be generally aligned with the lower wall of the exhaust pipe 18. In this way, the orifice 183 on the exhaust pipe 18 for mounting the outlet end 51 of the exhaust pipe 50 can be omitted. Since the oil drain pipe 50 is provided inside the casing of the expander, the structure of the expander can be made compact, thereby saving installation space.

Fig. 7 is a longitudinal sectional view of a scroll expander according to another embodiment of the present invention. As shown in fig. 7, the example in fig. 7 is different from the example in fig. 6 in the manner in which the lubricant discharge passage 100 is constituted. In the example of fig. 7, the lubricant drain channel 100 is defined by a portion of the housing 12 and the plate 60. Plate 60 is secured to the portion of housing 12. Preferably, the plate 60 is arcuate in shape. The plate 60 may be secured to the housing 12 by welding, adhesive, or the like.

It should be appreciated that the manner in which the lubricant drain channel 100 described above is formed is not limited to that described herein. For example, the lubricant drain passage may be integrated in the housing 12 (shell). Specifically, the lubricant drain passage may be a hole provided in the housing 12 (shell).

Furthermore, it should be understood that the outlet end of the lubricant discharge channel and the arrangement of the outlet may be determined according to the application, installation conditions, etc. Preferably, the outlet end of the lubricant drain channel and the outlet may be arranged in a manner that facilitates the flow of lubricant into the exhaust pipe.

As shown in fig. 2c, the outlet 511 of the outlet end 51 is substantially flush with the wall of the exhaust pipe, i.e. the outlet end 51 does not protrude into the interior of the exhaust pipe. As shown in fig. 8a, the outlet end 51 may extend into the exhaust pipe 18, i.e. beyond the orifice 183. In the example of fig. 8a, the outlet end 51 is substantially perpendicular to the central axis of the exhaust pipe 18, i.e. the outlet 511 is substantially parallel to said central axis. Fig. 8b shows another variant of the outlet end 51. As shown in fig. 8b, the outlet end 51 has an extending portion 513 extending into the interior of the exhaust pipe 18, and the extending portion 513 is curved in the flow direction of the fluid in the exhaust pipe 18, and thus, the extending portion 513 may also be referred to as a curved portion. The protruding portion 513 may be configured such that the outlet 511 is substantially perpendicular to the central axis of the exhaust pipe 18, i.e., such that the outlet 511 is oriented along the flow direction of the fluid in the exhaust pipe 18. It should be understood that the outlet end of the lubricant drain channel and the arrangement of the outlets may be varied in many ways and is not limited to the examples shown or described herein. In some examples, other orientations of the outlet are also possible. For example, the outlet may be inclined with respect to the central axis of the exhaust pipe. The cross-section of the internal passage of the outlet end 51 may be designed in a manner that facilitates the discharge of lubricant into the exhaust pipe.

Similarly, the inlet end of the lubricant drain channel and the arrangement of the inlet may be determined depending on the application, installation conditions, etc. Preferably, the inlet end of the lubricant drain channel and the inlet may be arranged in a manner that facilitates the flow of lubricant from the sump into the lubricant drain channel.

As shown in fig. 2d, the inlet 532 of the inlet end 53 is substantially flush with the housing 12 (shell), i.e. the inlet end 53 does not protrude into the interior of the shell. In the example of fig. 2d, the inlet 532 faces the interior of the expander, i.e. is substantially perpendicular to the lubricant level. As shown in fig. 9a, the inlet end 53 may extend into the interior of the expander, i.e., beyond the housing 12 and bottom cover 16 (shell). In the example of fig. 9a, the inlet end 53 has an overhanging portion 533, and the overhanging portion 533 is curved upward such that the inlet 532 is substantially parallel to the lubricant level. Fig. 9b shows another variation of the inlet end 53. As shown in fig. 9b, the inlet end 53 has a downwardly curved projecting portion 535. It should be understood that the inlet end of the lubricant drain passageway and the arrangement of the inlets may be varied and are not limited to the examples shown or described herein. For example, the run-in portion may be linear and/or the inlet may be inclined with respect to the horizontal. The cross-section of the internal passage of the inlet end 53 may be designed in a manner that facilitates drawing lubricant from the sump to the lubricant drain passage.

Fig. 10 shows a schematic view of a fluid circulation system using the scroll expander described above. As shown in fig. 10, the fluid circulation system includes the scroll expander 10, the condenser 11 connected to the scroll expander 10 via the first exhaust pipe 186, the working fluid pump 19 connected to the condenser 11 via the second exhaust pipe 188, and the evaporator 13 connected between the working fluid pump 19 and the scroll expander 10. An outlet end of the lubricant drain passage 100 is connected to the second exhaust pipe 188, and an inlet end of the lubricant drain passage 100 is connected to the scroll expander 10 for draining lubricant reaching a predetermined oil level in the scroll expander 10 into the second exhaust pipe 188. Connecting the outlet end of the lubricant drain passage 100 to the second exhaust pipe 188 prevents the lubricant from affecting the performance of the condenser.

As shown in fig. 10, a check valve 105 may also be provided in the lubricant discharge passage 100. The check valve 105 is configured to allow fluid to flow from the sump 90 of the expander 10 into the second bleed conduit 188 into the system, but to prevent fluid from flowing back from the second bleed conduit 188 to the sump 90. Further, in order to ensure that the lubricant is discharged from the oil pool 90 to the second exhaust pipe 188, a pump (not shown) may also be provided in the lubricant discharge passage 100.

It should be understood that the fluid circulation system according to the present invention is not limited to the example shown in fig. 10. For example, an outlet end of the lubricant drain passage 100 may be connected to the first exhaust pipe 186.

For purposes of describing the present invention herein, a vertical low pressure side scroll expander is taken as an example. It should be appreciated, however, that the present invention may be applied to any suitable type of expander, such as, for example, a rotor expander, a horizontal expander, a high-side expander, and the like.

Although various embodiments and possible variations of the present disclosure have been described in detail herein, it should be understood that the disclosure is not limited to the particular embodiments described and illustrated herein. The various features of the embodiments illustrated and described above may be combined with each other without conflict or may be omitted. Other modifications and variations can be effected by those of skill in the art without departing from the spirit and scope of the disclosure. All such modifications and variations are intended to be within the scope of the present invention. Moreover, all of the components, parts or features described herein may be replaced by other structurally and functionally equivalent components, parts or features.

Claims

1. An expander, comprising:

a housing (12, 14, 16);

An expansion mechanism (70, 80) disposed within the housing and configured to expand a high pressure fluid into a low pressure fluid;

-an exhaust pipe (18) configured to discharge the low pressure fluid out of the expander (10) and comprising an end (182), the end (182) fitting in a first opening (121) of the housing and having an exhaust port (181), wherein the low pressure fluid enters the exhaust pipe via the exhaust port;

An oil sump (90) located within the housing and storing a lubricant; and

A lubricant drain passage (100) configured to drain lubricant in the sump into the exhaust pipe and/or an external system conduit (186, 188) in communication with the exhaust pipe, and comprising an inlet end (53) having an inlet (532) and an outlet end (51) having an outlet (511), wherein the inlet is located at a predetermined oil level of the sump (90), the lubricant entering the lubricant drain passage being drained via the outlet into the exhaust pipe and/or the external system conduit (186, 188).

2. The expander according to claim 1, wherein the lubricant discharge channel is provided by a separate oil discharge pipe (50).

3. The expander of claim 2, wherein the oil drain tube is secured to an inner wall of the housing.

4. An expander according to claim 2, wherein the exhaust pipe is provided with an aperture (183) in which the outlet end of the exhaust pipe fits.

5. The expander according to claim 4, wherein the orifice of the exhaust pipe is arranged close to an exhaust port (181) of an end (182) of the exhaust pipe or the distance between the orifice and the exhaust port is at least a minimum predetermined distance.

6. The expander according to claim 4, wherein a second opening (122, 162) is further provided in the housing, the inlet end of the oil drain pipe fitting in the second opening.

7. The expander of claim 6, wherein the second opening is positioned directly below the first opening in a vertical direction.

8. The expander of claim 6, wherein the exhaust pipe extends toward a horizontal plane at which the second opening is located to reduce a height difference between the orifice and the second opening.

9. The expander of claim 8, wherein the oil drain pipe is disposed in a horizontal direction.

10. The expander according to claim 1, wherein the lubricant discharge passage is defined by a portion of the housing and a plate (60) secured to the portion of the housing.

11. The expander of claim 10, wherein the plate has an arcuate shape.

12. The expander of claim 1, wherein the lubricant discharge passage is a bore disposed within the housing.

13. An expander according to any one of claims 1 to 12, wherein the lubricant discharge passage extends substantially linearly.

14. The expander according to any one of claims 1 to 2 and 4 to 9, wherein the inlet of the lubricant discharge passageway is substantially flush with the wall of the casing or the inlet end of the lubricant discharge passageway protrudes into the interior of the casing.

15. The expander of claim 14, wherein the outlet of the lubricant discharge passageway is substantially flush with the wall of the exhaust pipe or the outlet end of the lubricant discharge passageway includes a curved portion that protrudes into the interior of the exhaust pipe such that the outlet is oriented in the direction of fluid flow in the exhaust pipe.

16. The expander according to any one of claims 1 to 12, wherein in the lubricant discharge passage, there is provided: a one-way valve (105) that allows fluid to flow from the oil sump into the exhaust pipe but prevents backflow of fluid from the exhaust pipe to the oil sump; and/or a pump for pumping lubricant in the sump into the exhaust pipe.

17. The expander of any one of claims 1 to 12, wherein the expander is a low pressure side expander.

18. A fluid circulation system, wherein the fluid circulation system comprises: the expander of any one of claims 1 to 17.

19. The fluid circulation system of claim 18, further comprising:

A condenser;

a first exhaust pipe forming part of the external system piping, the first exhaust pipe connecting the expander to an inlet of the condenser; and

A second exhaust pipe forming part of the external system pipe, the second exhaust pipe being connected to an outlet of the condenser,

Wherein the outlet end of the lubricant drain passage is connected to the first exhaust pipe or the second exhaust pipe.